History of machine tools
Machine tool (English name: machine tool) refers to the machine that manufactures the machine, also known as the working machine or machine tool, which is customarily referred to as the machine tool.
Generally divided into metal cutting machine tools, forging machine tools and woodworking machine tools.
There are many methods for processing mechanical parts in modern machinery manufacturing: in addition to cutting, there are casting, forging, welding, stamping, extrusion, etc., but all parts with high precision requirements and fine surface roughness requirements are generally required. The final machining is carried out by cutting on the machine. Machine tools play a major role in the modernization of the national economy.
A lathe is a machine tool that mainly turns a rotating workpiece with a Turning tool. On the lathe, drills, reamer, reamer, taps, dies and knurling tools can also be used for machining. Lathes are mainly used for machining shafts, discs, sleeves and other workpieces with a rotating surface. They are the most widely used machine tools in machine building and repair plants.
In the prototype of the fifteenth-century machine tool, due to the need to manufacture watches and weapons, threaded lathes and gear processing machines for watchmakers, as well as hydraulically driven barrel boring machines. Around 1501, the Italian Leonardo da Vinci had sketched the concept of lathes, boring machines, threading machines and internal grinding machines, including new mechanisms such as cranks, flywheels, tops, and bearings. The structure of the grinder is also contained in the "Tiangong Kaiwu" published by the Ming Dynasty in China. The iron plate is rotated by the method of pedaling, and sand and water are used to cut the jade.
The industrial revolution led to the creation and improvement of various machine tools. The industrial revolution of the eighteenth century promoted the development of machine tools. In 1774, the British Wilkinson (full name John Wilkinson) invented a more sophisticated barrel trampoline. The following year, he used the barrel of this barrel to meet the requirements of the Watt steam engine. In order to build a larger cylinder, he built a water wheel-driven cylinder boring machine in 1775, which promoted the development of steam engines. From then on, the machine tool was driven by a steam engine through the crankshaft.
In 1797, the English machine made by Mozley was driven by a screw-drive tool holder, which was able to realize motorized feed and Turning thread. This was a major change in the machine structure. Mozley is therefore also known as "the father of the British machine tool industry."
In the 19th century, various types of machine tools emerged due to the promotion of textile, power, transportation machinery and arms production. In 1817, the British Roberts created a planer; in 1818, American Whitney (full name Eli Whitney) made the horizontal milling machine; in 1876, the United States made the universal cylindrical grinding machine; 1835 and 1897 Invented the hobbing machine and gear shaping machine.
The center of industrial technology development has quietly moved from the UK to the United States since the 19th century. Among the people who took Britain's technological prestige, Whitney is a leader. Whitney is brilliant and visionary, and he pioneered the development of systems for mass-produced replaceable parts. Whitney Engineering, which is still active today, developed a turret-type turret lathe as early as the 1940s. This type of lathe is made with the complexity and refinement of the workpiece. In this type of lathe, a winch is mounted, and various required tools are mounted on the winch. Thus, the turret is rotated by a fixed tool. , you can turn the tool to the desired location.
With the invention of the electric motor, the machine tool was first driven by a motor, and then a separate motor was widely used.
At the beginning of the twentieth century, coordinate boring machines and thread grinders were created for the machining of workpieces, fixtures and threading tools with higher precision. At the same time, in order to meet the needs of mass production in industries such as automobiles and bearings, various automatic machine tools, profiling machines, combined machine tools, and automatic production lines have been developed.
In 1900, it entered the period of precision. From the end of the 19th century to the beginning of the 20th century, single lathes have gradually evolved milling machines, planers, grinding machines, drilling machines, etc. These main machine tools have been basically shaped, which has created conditions for the precision machine tools and mechanization and semi-automation of the early 20th century.
In the first 20 years of the 20th century, people mainly focused on milling machines, grinding machines and assembly lines. Due to the requirements of automotive, aircraft and engine production, precision, automatic milling machines, and grinding machines are urgently needed in the processing of complex shapes, high precision, and high-gloss parts. Due to the advent of multi-spiral blade milling cutters, the vibration and smoothness produced by single-blade milling cutters are basically solved, which makes the milling machine undeveloped, making the milling machine important equipment for processing complex parts.
Ford, who is hailed as the "father of cars" by the world, said: Cars should be "lightweight, strong, reliable and cheap." In order to achieve this goal, high-efficiency grinding machines must be developed. For this reason, American Norton made large and wide grinding wheels with corundum and corundum in 1900, as well as heavy and strong heavy-duty grinding machines. The development of grinding machines has brought mechanical manufacturing technology into a new stage of precision.
In 1920, it entered a semi-automatic period. In the 30 years after 1920, mechanical manufacturing technology entered a semi-automated period, and hydraulic and electrical components were gradually applied in machine tools and other machinery. In 1938, hydraulic systems and electromagnetic control not only promoted the invention of new milling machines but also promoted them on machine tools such as planer. After the 1930s, the travel switch - solenoid valve system almost used automatic control of various machine tools.
In 1950, it entered the period of automation. After the Second World War, the development of machine tools began to enter the automation period due to the emergence of CNC and group-controlled machine tools and automatic lines. After the invention of the electronic computer, the numerical control machine uses the principle of digital control to store the operation code, the requirements and the operation digital and text code of the replacement tool as information, and control the machine tool according to the instructions issued by the computer, and process according to the established requirements. New machine tools.
The world's first CNC machine tool (milling machine) was born (1951). The solution for CNC machine tools was proposed to the US Air Force by Parsons (full name John Parsons) of the United States when developing a blade machine for inspecting the profile of the propeller blade of the aircraft. With the participation and assistance of the Massachusetts Institute of Technology, it was finally successful in 1949. In 1951, they officially made the first CNC machine tool prototype, successfully solved the automation problem of complex parts processing in multiple varieties and small batches. Later, on the one hand, the numerical control principle extends from the milling machine to the milling and boring machine, the drilling machine and the lathe, on the other hand, the transition from the electron tube to the transistor and the integrated circuit. In 1958, the United States developed a machining center that can automatically change tools for multi-process machining.
The world's first CNC production line was born in 1968. The British Marlins Machinery Company developed the first automatic line of CNC machine tools. Soon, the United States General Electric Company proposed "the prerequisite for factory automation is the CNC of the part processing process and the program control of the production process." Thus, by the mid-1970s, an automated workshop had emerged and an automated factory had begun construction. From 1970 to 1974, three small technological breakthroughs occurred due to the widespread use of small computers in machine tool control. The first time was a direct digital controller, which enabled a small electronic computer to control multiple machines at the same time, and “group control” appeared. The second time was computer-aided design, design and modification of design and calculation procedures with a light pen; Three times, according to the actual situation of the machining and the unexpected change feedback and automatically change the machining amount and cutting speed, the machine tool of the adaptive control system appeared.
After more than 100 years of ups and downs, the family of machine tools has matured and become a “working machine” in the mechanical field.
1) "Bow lathe" of ancient pulleys and bows.
As early as in ancient Egypt, people have invented the technique of Turning with a tool when rotating wood around its central axis. At first, people used two standing timbers as brackets to set up the wood to be turned. Using the elastic force of the branches to roll the rope onto the wood, pull the rope by hand or foot to turn the wood, and carry the cutter to cut.
This ancient method evolved and evolved into two or three rounds of rope on a pulley. The rope was placed on an elastic rod that was bent into a bow. The bow was pushed back and forth to rotate the workpiece for Turning. This is a "bow lathe."
2) "Crank lathe" for medieval crankshaft and flywheel transmission.
In the Middle Ages, someone designed a "pedal lathe" that used a pedal to rotate the crankshaft and drive the flywheel, which was then driven to the main shaft to rotate. In the middle of the 16th century, a French designer named Besson designed a lathe for a car screw that used a screw to slide the tool. Unfortunately, this type of lathe was not promoted.
3) The bed box and chuck were born in the 18th century.
In the 18th century, someone designed a rotating crankshaft with a foot pedal and a connecting rod, which can store the rotational kinetic energy on the lathe on the flywheel and develop from the direct rotating workpiece to the rotating headstock. The headstock is an A chuck for holding a workpiece.
4) British Mozley invented the knife lathe (1797)
In the story of the invention of the lathe, the most striking thing is an Englishman named Mozley, who invented the epoch-making tool holder lathe in 1797. The lathe has a precision lead screw and is interchangeable. gear.
The birth of various special lathes in order to improve the degree of mechanization automation. In 1845, Fitch in the United States invented the turret lathe. In 1848, a reversing lathe appeared in the United States. In 1873, Spencer of the United States made a single-axis automatic lathe, and soon he made a three-axis automatic lathe. At the beginning of the 20th century, a lathe with a geared transmission driven by a separate motor appeared. Thanks to the invention of high-speed tool steel and the application of electric motors, the lathe has been continuously improved, and finally reached the modern level of high speed and high precision.
After the First World War, various efficient automatic lathes and specialized lathes developed rapidly due to the needs of the arms, automobiles and other machinery industries. In order to increase the productivity of small batches of workpieces, lathes with hydraulic profiling devices were promoted in the late 1940s, and multi-tool lathes were also developed. In the mid-1950s, program-controlled lathes with perforated cards, latch plates, and dials were developed. CNC technology began to be used in lathes in the 1960s and developed rapidly after the 1970s.
The lathes of lathes are classified into various types depending on the purpose and function.
The general lathe has a wide processing target, and the adjustment range of the spindle rotation speed and the feed amount is large, and the inner and outer surfaces, end faces, and internal and external threads of the workpiece can be processed. This type of lathe is mainly operated by workers and has low production efficiency. It is suitable for single-piece, small batch production and repair workshops.
The turret lathe and the rotary lathe have a turret or a reTurning tool holder that can hold a plurality of tools. The workpiece can be used in a single clamping process by the worker to perform various processes in turn, which is suitable for batch production.
The automatic lathe can automatically complete the multi-step processing of small and medium-sized workpieces according to a certain program. It can automatically load and unload, and repeatedly process a batch of the same workpiece, which is suitable for mass production and mass production.
Multi-tool semi-automatic lathes are available in single, multi-axis, horizontal and vertical. The layout of the single-axis horizontal type is similar to that of a conventional lathe, but the two sets of tool holders are respectively mounted on the front, rear or up and down of the main shaft for machining discs, rings, and shaft-like workpieces, and the productivity is 3 to 5 times higher than that of ordinary lathes.
The profiling lathe can automatically complete the machining cycle of the workpiece according to the shape and size of the sample or sample. It is suitable for small batch and batch production of more complex workpieces, and the productivity is 10 to 15 times higher than that of ordinary lathes. There are multiple tool holders, multi-axis, chuck type, vertical type and so on.
The main axis of the vertical lathe is perpendicular to the horizontal plane, and the workpiece is clamped on a horizontal rotary table, and the tool holder moves on the beam or column. It is suitable for processing large, heavy and difficult to install on ordinary lathes. It is generally divided into two categories: single column and double column.
While Turning the lathe, the tool holder periodically reciprocates radially and is used for the forming tooth surface of the forklift milling cutter, the hob, and the like. Usually with a shovel attachment, the small grinding wheel driven by a separate motor shovel the tooth surface.
Special lathes are lathes for the machining of specific surfaces of certain types of workpieces, such as crankshaft lathes, camshaft lathes, wheel lathes, axle lathes, roll lathes, and ingot lathes.
The combined lathe is mainly used for Turning to the machine, but with the addition of some special parts and accessories, it can also be processed by boring, milling, drilling, inserting, grinding, etc. It has the characteristics of “one machine multi-energy” and is suitable for engineering vehicles, ships or mobile. Repair work on the repair station.
Milling machine refers to a machine tool that mainly uses a milling cutter to machine various surfaces on a workpiece. Usually, the rotary motion of the milling cutter is the main motion, and the movement of the workpiece (and) milling cutter is the feed motion. It can process planes, grooves, and various surfaces, gears, and so on. A milling machine is a machine that mills a workpiece with a milling cutter. In addition to milling planes, grooves, gears, threads, and spline shafts, milling machines can also process more complex profiles with higher efficiency than planers and are widely used in the mechanical manufacturing and repair departments.
In the 19th century, the British invented the trampoline and planer for the needs of the industrial revolution such as steam engines, and the Americans devoted themselves to the invention of milling machines in order to produce a large number of weapons. A milling machine is a machine with different shapes of milling cutters that cut specially shaped workpieces such as spiral grooves, gear shapes, and more.
As early as 1664, the British scientist Hooker used a rotating circular cutter to create a machine for cutting. This was the original milling machine, but the society did not respond enthusiastically. In the 1940s, Pratt designed the so-called Lincoln milling machine. Of course, if you really establish the status of milling machines in machine manufacturing, you should count American Whitney.
The first ordinary milling machine (Whitney, 1818). In 1818, Whitney built the world's the first ordinary milling machine, but the patent for the milling machine was the British Bodmer (the inventor of the planer with the knife feeder) in 1839. of. Because the cost of milling machines was too high, there were not many people at the time.
The first universal milling machine (Brown, 1862). After the milling machine was silent for a while, it was active in the United States. In contrast, Whitney and Pratt can only be said to have made a groundbreaking work for the invention of the milling machine. The success of the invention of the milling machine that can be applied to various operations in the factory should belong to American engineer Joseph Brown.
In 1862, Brown in the United States created the world's first universal milling machine, which is an epoch-making initiative in the provision of universal indexing plates and integrated milling cutters. The table of the universal milling machine can be rotated at a certain angle in the horizontal direction and has accessories such as a vertical milling head. His “Universal Milling Machine” was extremely successful when it was exhibited at the 1867 Paris Exposition. At the same time, Brown also designed a forming cutter that was not deformed by grinding, and then a grinding machine that made the milling cutter, which made the milling machine reach the current level.
In the process of invention, many things are often complementary and interlocking: in order to manufacture steam engines, trampoline assistance is needed; after the steam engine is invented, the planer is called for the planer. It can be said that it is the invention of the steam engine that led to the design and development of the "working machine" from the boring machine to the lathe to the planer. In fact, the planer is a kind of planer for metal shaving.
Machining large plane planer (1839). Since the beginning of the 19th century, many technicians have started research in this area, including Richard Robert, Richard Pratt, James Fox, and Joseph Clemente. They began to manufacture the planer independently in 25 years from 1814. The planer is to fix the workpiece on the reciprocating platform, and the planer cuts one side of the workpiece. However, this planer has no knife-feeding device and is in the process of conversion from “tool” to “mechanical”. By 1839, a British man named Boomer had finally designed a planer with a knife-feeding device.
Processing facet planers. Another Britishman, the Smith, invented the facet planer in 40 years from 1831. It can fix the object to the bed and the tool moves back and forth.
Since then, due to the improvement of tools and the emergence of electric motors, the planer has been developed towards high-speed cutting and high-precision direction, and on the other hand, it has been developed in the direction of large-scale.
Although the factory handicraft industry is relatively backward, it has trained and created many skilled workers. Although they are not experts in the manufacture of machines, they can manufacture a variety of hand tools, such as knives and saws. Needles, drills, cones, mills, shafts, sleeves, gears, bed frames, etc., in fact, the machine is assembled from these components.
The earliest trampoline designer - Da Vinci. The trampoline is called the "mother of machinery." Speaking of the trampoline, I have to talk about Da Vinci first. This legendary figure is probably the first designer of a trampoline for metalworking. The trampoline he designed is powered by hydraulic or pedals, the boring tool is rotated against the workpiece, and the workpiece is fixed on a mobile platform driven by a crane. In 1540, another painter drew a painting of "Firework" and also had the same trampoline map. The trampoline at that time was specifically used to finish hollow castings.
The first trampoline that was born for the processing of cannon barrels (Wilkinson, 1775). In the 17th century, due to military needs, the artillery manufacturing industry developed very rapidly. How to make the cannon barrel has become a major problem that people need to solve. The world's first real trampoline was invented by Wilkinson in 1775. In fact, Wilkinson's trampoline is a drill that can precisely process cannons. It is a hollow cylindrical mast with both ends mounted on bearings.
In 1728, Wilkinson was born in the United States. When he was 20, he moved to Staffordshire and built the first iron furnace in Bilston. Therefore, Wilkinson is known as the "master of blacksmiths in Staffordshire." In 1775, the 47-year-old Wilkinson worked hard in his father's factory to finally create a new machine that could drill cannon barrels with rare precision. Interestingly, after Wilkinson's death in 1808, he was buried in his own cast iron enamel.
The trampoline made an important contribution to the steam engine of Watts. If there was no steam engine, then the wave of the first industrial revolution could not have occurred at that time. The development and application of the steam engine itself, in addition to the necessary social opportunities, some of the technical prerequisites can not be ignored, because the manufacture of steam engine parts is far less easy than carpenter cutting wood, to make some special metal The shape and the precision of the processing are high, and there is no corresponding technical equipment. For example, in the manufacture of cylinders and pistons of steam engines, the accuracy of the outer diameter required in the manufacturing process of the piston can be cut from the outer side, but to meet the accuracy requirements of the inner diameter of the cylinder, it is not easy to use the general processing method. .
Smithton was the best mechanical technician in the eighteenth century. There are 43 waterwheel and windmill equipment designed by Smithton. When making steam engines, the most troublesome thing for Symington was machining the cylinders. It is quite difficult to machine a large cylinder inner circle into a circle. To this end, Stirton made a special machine for cutting the inner circle of the cylinder at the Karen Iron Works. The boring machine powered by a water truck is equipped with a cutter at the front end of its long shaft, which can be rotated in the cylinder to process the inner circle. Since the tool is mounted on the front end of the long axis, problems such as the deflection of the shaft occur, so it is very difficult to machine a truly circular cylinder. To this end, Smith had to change the position of the cylinder several times for processing.
For this problem, Wilkinson's invention of the trampoline in 1774 played a big role. The boring machine uses a water wheel to rotate the material cylinder and advance it against a centrally fixed tool. Due to the relative motion between the tool and the material, the material is scooped out of the cylindrical hole with high precision. At that time, a 72-inch diameter cylinder was made with a trampoline, and the error did not exceed the thickness of the six-penny coin. This is a big error measured by modern technology, but it is not easy to achieve this level under the conditions of the time.
However, Wilkinson's invention was not patented, and people copied it and installed it. In 1802, Watt also talked about Wilkinson's invention in the book and copied it at his Soho Iron Factory. Later, when Watt made steam cylinders and pistons, Wilkinson used this magical machine. It turns out that for the piston, the size can be measured on the outside while cutting, but the cylinder is not so simple, and the trampoline is not used. At that time, Watt used the water wheel to rotate the metal cylinder, and the center fixed tool was pushed forward to cut the inside of the cylinder. As a result, the 75-inch diameter cylinder had an error of less than one coin. It is very advanced.
The workbench lift boring machine was born (Hutton, 1885). In the next few decades, many improvements have been made to Wilkinson's trampoline. In 1885, Hutton of the United Kingdom built a table lift boring machine, which has become the prototype of a modern trampoline.
Ancient drilling machine - "bow". Drilling technology has a long history. Archaeologists have now discovered that in 4,000 BC, humans invented devices for punching. The ancients placed a beam on the two columns, and then hang a rotatable awl from the beam, and then used the bowstring to drive the awl to rotate so that the wood stone could be punched. Soon, people also designed a perforating tool called "辘轳", which also uses a flexible bowstring to make the awl rotate.
The first drilling machine (Whitworth, 1862). By around 1850, the German Martignoni was the first to make a twist drill for metal punching. At the international fair held in London in 1862, the British Whitworth exhibited a drill press with a cast iron frame driven by a power, which became the prototype of a modern drilling machine.
In the future, various drilling machines appeared one after another, including a radial drilling machine, a drilling machine equipped with an automatic feeding mechanism, and a multi-axis drilling machine capable of simultaneously punching a plurality of holes at the same time. Thanks to improvements in tool materials and drill bits, and the use of electric motors, large, high-performance drill presses were finally built.
Grinding is an ancient technique that humans have known since ancient times. In the Paleolithic era, this technique was used to grind stone tools. Later, with the use of metal appliances, the development of grinding technology was promoted. However, the design of a veritable grinding machine is still a modern thing. Even in the early 19th century, people still rotated the natural grinding stone to make it contact with the processed object for grinding.
The first grinding machine (1864). In 1864, the United States made the world's first grinding machine, which was equipped with a grinding wheel on the lathe turret of the lathe, and it was equipped with a device for automatic transmission. After 12 years, Brown in the United States invented the universal grinding machine that is close to modern grinding machines.
Artificial grindstone - the birth of the grinding wheel (1892). The demand for artificial grindstones has also arisen. How to develop a grindstone that is more wear-resistant than natural grindstone? In 1892, American Acheson successfully produced silicon carbide made of coke and sand, which is a kind of artificial grindstone now known as C abrasive; two years later, A-alumina with alumina as the main component was trial-produced. Success, in this way, the grinding machine has been more widely used.
In the future, due to the further improvement of the bearing and guide rail parts, the precision of the grinding machine is getting higher and higher, and the direction of specialization has developed, and internal cylindrical grinding machines, surface grinding machines, barrel grinding machines, gear grinding machines, universal grinding machines and the like have appeared.
Forging presses are metal and mechanical cold working equipment that only changes the outer shape of the metal. Forging machine tools include coiling machines, shearing machines, punching machines, presses, hydraulic presses, hydraulic presses, bending machines, etc.
There are many types of machine tool accessories, including flexible organ shields (leather tigers), cutter blades, steel plate stainless steel rail guards, telescopic screw guards, roller blinds, protective skirts, dustproof fabrics, steel Towline, engineering plastic towline, machine tool work light, machine mattress iron, JR-2 rectangular metal hose, DGT conduit protective sleeve, adjustable plastic cooling tube, vacuum tube, ventilation tube, explosion-proof tube, stroke slot plate , bump block, chip conveyor, deflection instrument, platform \ granite plate \ cast iron plate and various operating parts.
CNC machine tool
It is the abbreviation of the digital control machine tool, which is an automatic machine tool with a program control system. The control system can logically process a program having a control code or other symbol command specification and decode it, thereby causing the machine tool to operate and machine the part control unit. The operation and monitoring of the CNC machine tool are all completed in this numerical control unit. It is the brain of CNC machine tools.
High processing precision and stable processing quality;
The multi-coordinate linkage can be performed to process parts with complex shapes;
When the machining parts are changed, generally only the NC program needs to be changed, which saves production preparation time;
The machine tool itself has high precision and rigidity and can choose favorable processing amount, and the productivity is high (usually 3~5 times of ordinary machine tools);
The high degree of automation of the machine tool can reduce the labor intensity;
The requirements for the quality of the operators are higher, and the technical requirements for the maintenance personnel are higher.
CNC machine tools generally consist of the following parts:
The main machine is the main body of the CNC machine tool, including the machine parts, columns, spindles, feed mechanisms, and other mechanical components. It is a mechanical part used to perform various cutting operations.
The numerical control device is the core of the CNC machine tool, including hardware (printed circuit board, CRT display, key box, tape reader, etc.) and corresponding software for inputting digital part programs and completing the storage of input information and data. Transform, interpolate, and implement various control functions.
The drive unit is the drive unit of the CNC machine tool actuator, including the spindle drive unit, the feed unit, the spindle motor and the feed motor. It realizes spindle and feeds drive through an electric or electro-hydraulic servo system under the control of a numerical control device. When several feeds are linked, the positioning, straight line, plane curve and space curve can be processed.
Auxiliary devices, some necessary components of the index control machine to ensure the operation of CNC machine tools, such as cooling, chip removal, lubrication, lighting, monitoring, etc. It includes hydraulic and pneumatic devices, chip removal devices, exchange tables, CNC rotary tables, and CNC indexing heads, as well as tools and monitoring and inspection devices.
Programming and other ancillary equipment can be used to program, store, etc. parts outside the machine.
CNC machine tool description
The CNC program can be divided into the main program and a subprogram (subprogram). Any part that is repeatedly processed can be written in a subprogram to simplify the design of the main program.
Character (numerical data) → word → single section → machining program.
Just open the Notepad in the Windows operating system to edit the CNC code, and the written CNC program can use the simulation software to simulate the correctness of the tool path.
CNC machine tool processing flow description
CAD: Computer-Aided Design, which is computer-aided design. 2D or 3D workpiece or perspective design
CAM: Computer-Aided Making, which is computer-aided manufacturing. Generate G-Code using CAM software
CNC: CNC machine tool controller, read into G-Code and start machining
CNC machine tool basic function instructions
The so-called function command is composed of address code (English alphabet) and two numbers. It has a certain meaning of actions or functions. It can be divided into seven categories, namely, G function (preparation function), M function (auxiliary function), T function (tool function), S function (spindle speed function), F function (feed rate function), N function (single section number function) and H/D function (tool correction function).
CNC machine reference point description
Usually, when programming a CNC machine tool, at least one reference coordinate point must be selected to calculate the coordinate values ??of each point on the work chart. These reference points are called zero points or origins. Common reference points have mechanical origin, regression reference point, Work origin, program origin.
Machine reference point: A mechanical reference point, or mechanical origin, which is a fixed reference point on a machine.
Reference points: There is a regression reference point on each axis of the machine. The position of these return reference points is pre-precisely set by the limit switch of the stroke monitoring device as the regression point of the table and the spindle.
Work reference points: The working reference point or work origin, which is the origin of the working coordinate system. This point is floating and is set by the programmer as needed. It is usually set on the workbench ( Work on) any location.
Program reference points: The program reference point or program origin, which is the reference point for the coordinate values ??of all Turning points in the work. This point must be selected when the program is written, so the programmer must select one when selecting. Convenient point to facilitate the writing of the program.
The steel telescopic rail guard is made of a high-quality 2-3mm thick steel plate and can be made of stainless steel according to requirements. Special surface finish will give it an additional value. We can provide the appropriate rail protection type (horizontal, vertical, tilt, lateral) for all machine types.
The crankshaft high-efficiency special machine tool also has its processing limitations. Only by properly applying the appropriate machining machine tool can the high-efficiency specialty of the crankshaft machining machine be realized, thereby improving the processing efficiency of the process.
1. When the crankshaft journal has an undercutting groove, the CNC internal milling machine cannot be machined; if the crankshaft journal has an undercutting groove, the CNC high-speed external milling machine and the CNC internal milling machine cannot be processed, but the CNC car-car The drawing machine can be easily processed.
2. When the side of the balance block needs to be machined, the CNC internal milling machine should be the preferred machine tool. Because the inner milling cutter is positioned outside the circle and has good rigidity, it is especially suitable for machining large forged steel crankshafts. At this time, it is not suitable for CNC car-car pulling. The machine tool, because it needs to be machined on the side of the balance block of the crankshaft, is machined by CNC car-car pulling machine, the side of the balance block is interrupted cutting, and the crankshaft speed is very high. Under this condition, the phenomenon of chipping is compared. serious.
3. When the journal of the crankshaft has no undercutting groove and the side of the balance block does not need to be machined, in principle, several machine tools can be processed. When machining the car crankshaft, the spindle neck adopts the CNC car-car pull machine tool, and the connecting rod neck adopts the numerical control high-speed router milling machine tool, which should be the best efficient machining option; when processing the large forged steel crankshaft, the main journal and the connecting rod neck are both It is more reasonable to use CNC internal milling machine.
The crankshaft can be divided into a large forged steel crankshaft and a lightweight car crankshaft. The forged steel crankshaft journal generally has no undercutting grooves, and the side needs to be processed, and the margin is large; the car crankshaft generally has a sunken slot, and No machining is required on the side. Therefore, it can be concluded that the machining forged steel crankshaft adopts the numerical control internal milling machine tool, the machining of the crankshaft main neck of the car adopts the numerical control vehicle-car pulling machine tool, and the connecting rod neck adopts the numerical control high-speed outer milling machine tool, which is a reasonable and efficient processing option.
The quality of the machine itself directly affects the quality of the machine. Measuring the quality of a machine tool is multi-faceted, but mainly requires good processability, serialization, generalization, a high degree of standardization, simple structure, lightweight, reliable work, and high productivity. The specific indicators are as follows:
1. The possibility of craft
The possibility of a process is the ability of the machine to adapt to different production requirements. The universal machine tool can complete multi-process machining of various parts within a certain size range, and the process possibility is wide, so the structure is relatively complicated, and it is suitable for single-piece small batch production. Special machine tools can only complete a specific process of one or several parts, and the process possibilities are narrow. It is suitable for mass production, which can improve productivity, ensure processing quality, simplify machine structure and reduce machine tool cost.
2, accuracy and surface roughness
To ensure the accuracy and surface roughness of the machined parts, the machine tool itself must have certain geometric accuracy, motion accuracy, transmission accuracy, and dynamic accuracy.
Geometric accuracy refers to the positional accuracy between components and the shape accuracy and positional accuracy of the main parts when the machine is not in operation. The geometric accuracy of the machine tool has an important influence on the machining accuracy, so it is the main indicator for evaluating the accuracy of the machine tool.
The motion accuracy refers to the geometric position accuracy of the main components when the machine is running at the working speed. The larger the change of the geometric position, the lower the motion accuracy.
Transmission accuracy refers to the coordination and uniformity of motion between actuators at each end of the machine drive chain.
The above three kinds of precision indicators are all tested under no-load conditions. In order to fully reflect the performance of the machine tool, the machine tool must have certain dynamic precision and shape and position accuracy of the main components under temperature rise. The main factors affecting the dynamic accuracy are the rigidity, vibration resistance and thermal deformation of the machine tool.
The rigidity of the machine tool refers to the ability of the machine tool to resist deformation under the action of external force. The greater the rigidity of the machine tool, the higher the dynamic precision. The stiffness of the machine tool includes the stiffness of the machine tool component itself and the contact stiffness between the components. The stiffness of the machine tool component itself depends mainly on the material properties, cross-sectional shape, size, etc. of the component itself. The contact stiffness between the components is not only related to the contact material, the geometry and hardness of the contact surface, but also related to the surface roughness, geometric accuracy, processing method, contact surface medium, pre-stress and other factors of the contact surface.
The vibrations appearing on the machine tool can be divided into forced vibration and self-excited vibration. Self-excited vibration is a continuous vibration generated inside the cutting process without being disturbed by any external force or exciting force. Under the continuous action of the exciting force, the vibration forced by the system is forced vibration.
The seismic resistance of the machine tool is related to the rigidity, damping characteristics and quality of the machine tool. Due to the different thermal expansion coefficients of the various parts of the machine tool, different deformations and relative displacements of various parts of the machine tool are caused. This phenomenon is called the thermal deformation of the machine tool. The error due to thermal deformation can account for up to 70% of the total error.
For the dynamic precision of the machine tool, there is no uniform standard, and the dynamic precision of the machine tool is indirectly evaluated by the precision achieved by cutting typical parts.
3, serialization, etc.
The serialization, generalization and standardization of machine tools are closely related. Variety serialization is the basis for component generalization and component standardization, and the generalization of components and the standardization of components promote and promote the serialization of varieties.
4, the life of the machine tool
The reliability and wear resistance of machine tool structures are the main indicators for measuring the life of machine tools.
Machine tool movement
According to the role played during the cutting process, the cutting motion is divided into the main motion and feed motion.
Main motion: It is the working motion that forms the cutting speed of the machine or consumes the main power.
Feed motion: A work motion that continuously removes excess material from a workpiece.
There is only one main motion during the cutting process, and the feed motion can be more than one. The main motion and the feed motion can be performed separately by the tool or the workpiece, or by the tool alone. In addition to the cutting motion, the movement of the machine tool also has some auxiliary movements that must be performed to assist the cutting process of the machine tool.
Machine tool drive
The transmission mechanism of the machine tool refers to the mechanism that transmits motion and power, which is referred to as the transmission of the machine tool.
According to the characteristics of the transmission mechanism, the transmission mode of the machine tool is divided into the mechanical transmission, hydraulic transmission, electric drive, pneumatic transmission and the combined transmission of the above several transmission modes. According to the characteristics of the transmission speed adjustment and change, the transmission is divided into a stepped drive and a stepless drive.
The transmission system is also called the drive chain. He has the first and last end pieces. The headpiece is also called the active part, and the end piece is also called the follower. Each transmission system is composed of a certain transmission law from the head end piece to the end piece. This is the gear ratio to ensure the performance of the machine tool. The general machine tool transmission system can be divided into three types: the main motion transmission system, the feed motion transmission system and the fast air travel transmission system according to the nature of the motion it is responsible for. You can generally understand the drive system diagram.
Machine tool classification
1. Ordinary machine tools: including ordinary lathes, drilling machines, boring machines, milling machines, planing machines, etc.;
2, precision machine tools: including grinding machines, gear processing machines, thread processing machines and other various precision machine tools;
3, high-precision machine tools: including coordinate boring machine, gear grinding machine, thread grinding machine, high-precision hobbing machine, high-precision scribe machine and other high-precision machine tools;
4. CNC machine tools: CNC machine tools are short for digital control machine tools;
5, according to the size of the workpiece and the weight of the machine can be divided into instrument machine tools, small and medium-sized machine tools, large machine tools, heavy-duty machine tools, and super heavy-duty machine tools;
6, according to the processing accuracy can be divided into ordinary precision machine tools, precision machine tools, and high-precision machine tools;
7, according to the degree of automation can be divided into the manual operation of machine tools, semi-automatic machine tools, and automatic machine tools;
8. According to the control mode of the machine tool, it can be divided into copying machine tool, program control machine tool, CNC machine tool, adaptive control machine tool, machining center and flexible manufacturing system;
9, according to processing methods or processing objects can be divided into lathes, drilling machines, boring machines, grinding machines, gear processing machines, thread processing machines, spline processing machines, milling machines, planers, grooving, broaching machines, special processing machines, sewing machines, and engraving machines Wait. Each class is divided into several groups according to its structure or processing object, and each group is divided into several types;
10. According to the applicable scope of the machine tool, it can be divided into general-purpose, specialization and special machine tools.
Special machine tools are based on standard common parts, with a small number of automatic or semi-automatic machine tools designed according to the specific shape of the workpiece or the processing process, called the combined machine tool.
For the processing of one or several parts, a series of machine tools are arranged according to the process, and an automatic loading and unloading device and an automatic workpiece transfer device between the machine tool and the machine tool are arranged, so that a group of machine tools composed of such a machine group is called an automatic cutting production line.
The flexible manufacturing system is composed of a set of digital control machine tools and other automated process equipment. It is controlled by electronic computers and can automatically process workpieces with different processes, which can adapt to multi-variety production.
Machine tool composition
All types of machine tools usually consist of the following basic parts: support parts for mounting and supporting other parts and workpieces, bearing their weight and cutting forces, such as bed and column; shifting mechanism for changing the speed of the main movement; Mechanism for changing the feed rate; headstock for machine tool spindle; tool holder, tool magazine; control and control system; lubrication system; cooling system.
Machine tool attachments include machine tool loading and unloading devices, robots, industrial robots, and other machine tool attachments, as well as chucks, suction cup spring collets, vise, rotary table, and indexing head.
The cutting of the machine tool is realized by the relative motion between the tool and the workpiece, and the motion can be divided into two types: surface forming motion and auxiliary motion.
The surface forming motion is a motion that causes the workpiece to achieve the desired surface shape and size, including main motion, feed motion, and cut motion. The main motion is the main motion when peeling off excess material from the workpiece blank. It can be the rotary motion of the workpiece (such as Turning), linear motion (such as planing on a planer), or the rotary motion of the tool (such as Milling and drilling) or linear motion (such as cutting and broaching); the feed motion is the movement of the tool and the part to be machined to move, so that the cutting can continue, such as the tool holder slide along the machine guide when Turning the outer circle The movement of the cutting motion is a movement that cuts the tool into the surface of the workpiece to a certain depth. The function is to cut a certain thickness of material from the surface of the workpiece during each cutting stroke, such as the transverse cutting motion of the small tool holder when Turning the outer circle.
Auxiliary movements mainly include rapid approach and exit of tools or workpieces, adjustment of machine component positions, workpiece indexing, tool post indexing, feeding of materials, starting, shifting, reversing, stopping, and automatic tool change.
The indicators for evaluating the technical performance of machine tools can ultimately be attributed to machining accuracy and production efficiency. Machining accuracy includes dimensional accuracy, shape accuracy, positional accuracy, surface quality, and precision retention of the machined workpiece. Productivity involves cutting time and auxiliary time, as well as the degree of automation and reliability of the machine. On the one hand, these indicators depend on the static characteristics of the machine tool, such as static geometric accuracy and stiffness; on the other hand, they are more related to the dynamic characteristics of the machine tool, such as motion accuracy, dynamic stiffness, thermal deformation, and noise.
Machine tool accessories
Machine tool accessories refer to all components that can be easily replaced except the machine body.
Machine tool accessories mainly include tool holders, operating parts, indexing heads, work tables, chucks, joints, chip removal devices, hoses, drag chains, protective covers, etc. Among them, the tool fixture is divided into cutting tools, tooling fixtures, planing knives, CNC tools and supporting systems, knife belts, broaches, cutters, hobs, gear cutters, machine saw blades, CNC cutters, chucks, punches, Turning tools. Reamers, boring tools, pinion knives, shaving knives, machine blades, shanks, milling cutters, thread cutters, drill bits, shanks, other tools, clamps, taps; operating parts, handwheels, handles, handles, handles , door knobs, other operating parts.
Direction of development
1. Virtual machine tools: Improve the design level and performance of machine tools by developing electromechanical integration, hardware and software integration simulation technology.
2. Green machine tools: Emphasize energy conservation and emission reduction, and strive to minimize the environmental load of the production system.
3. Intelligent machine tools: Improve the intelligence, reliability, processing accuracy and comprehensive performance of the production system.
4. e-machine tool: Improve the independent autonomy of the production system and the interaction with users and managers, so that the machine tool is not only a processing device, but a node in the enterprise management network.
Among them, green machine tools will become a research hotspot. The working machine that converts the blank into parts not only consumes energy during use, but also produces solid, liquid and gaseous waste, causing direct or indirect pollution to the working environment and the natural environment. According to this, the green machine tool should have the following characteristics: the main parts of the machine tool are made of recycled materials; the weight and volume of the machine tool are reduced by more than 50%; the power consumption is reduced by 30% to 40% by reducing the moving mass and reducing the idle running power; The waste generated during the use process is reduced by 50% to 60% to ensure a basically non-polluting working environment; after scrapping, the machine tool material can be recycled 100%. According to statistics, the power used to cut metal during machine tool use only accounts for about 25%, and various losses and auxiliary functions account for the majority. The first measure of machine tool greening is to build eco-efficient machine tools by significantly reducing machine weight and reducing drive power. Green machine tools offer a new concept that significantly reduces weight and strives to save material while reducing energy consumption.
The operator must pass the test and hold the Machine Operation Certificate of this machine to operate the machine.
1. Read the shift record carefully to understand the operation and problems of the previous machine tool;
2. Check the machine tool, work table, guide rail, and each main sliding surface. If there are obstacles, tools, iron filings, impurities, etc., it must be cleaned, wiped clean and oiled;
3. Check the workbench, the guide rail and the main sliding surface for the new pull, grinding and bumping. If there is any notice, please inform the team leader or equipment staff to make a record and make a record;
4. Check the safety protection, braking (stop), limit and reversing devices should be complete;
5, check mechanical, hydraulic, pneumatic and other operating handles, cutting doors, switches, etc. should be in a non-working position;
6. Check that each tool holder should be in a non-working position;
7. Check that the electrical distribution box should be closed firmly and the electrical grounding is good;
8. Check the oil quantity of the oil storage part of the lubrication system should meet the requirements and be well sealed. Oil marks, oil windows, oil cups, grease nipples, oil lines, linoleum, oil pipes, and oil separators should be completed and installed correctly. According to the lubrication indicator chart, make manual oiling or motorized (hand position) pump oil to check whether the oil window is oily;
9. For machine tools that have been parked for more than one shift, the test procedure and the requirements for the use of hydrostatic devices (see Appendix I for details) should be carried out in accordance with the driving procedures and requirements for 3 to 5 minutes.
1) Whether the joystick, cutting the door, switch, etc. are flexible, accurate and reliable.
2) Whether the safety protection, braking (stopping), interlocking, clamping mechanism and other devices are effective.
3) Whether the proofreading mechanism has enough travel, adjust and fix the limit position, the fixed stop, and the reversing block.
4) Whether there is oil in the lubrication part by the motor pump or the hand pump, and the lubrication is good.
5) Whether the movement, working cycle, temperature rise, sound, etc. of the mechanical, hydraulic, static pressure, pneumatic, mold, and profiling devices are normal. Whether the pressure (hydraulic, pneumatic) is in compliance. Only after confirming that everything is normal can you start working.
In the case of equipment that is handed over to the shift, the shifting person shall check together in accordance with the provisions of (9) above. After the shift is clear, the shifter may leave. Any equipment that succeeds in a shift, if it is found that there is a serious violation of the operating procedures in the previous class, must inform the team leader or equipment staff to check and make a record, otherwise, it will be handled according to the violation rules of this class.
After the equipment is overhauled or adjusted, the equipment must also be inspected in detail according to the above (9), and it is considered that everything is correct before starting work.
1. Stick to the post, meticulously operate, and do nothing to do with work. Stop when leaving the machine due to things, turn off the power and air supply;
2. Processing according to the process regulations. It is not allowed to increase the amount of feed, the amount of grinding and the cutting speed. It is not allowed to use the machine tool for over-standard, overload and overweight. It is not allowed to use the coarse machine and small machine;
3. The tool and workpiece should be correctly clamped and fastened. Do not touch the machine when loading or unloading. If you are looking for a positive tool, the workpiece is not allowed to be hit by a heavy hammer. It is not allowed to tighten the tool and workpiece by increasing the torque by lengthening the handle.
4. It is not allowed to install thimbles, knives, knife sleeves, etc., which are inconsistent with taper or aperture, surface notched and unclean, in the taper hole of the machine tool spindle, the taper hole of the tailstock sleeve and other tool mounting holes;
5. The mechanical shifting of the transmission and feed mechanism, the clamping and adjustment of the tool and the workpiece, and the manual measurement between the workpieces should be stopped at the cutting and grinding, and the cutter and the grinding tool should be stopped after leaving the workpiece;
6. The sharpness of the tool and the grinding tool should be kept. If it becomes dull or cracked, it should be sharpened or replaced in time;
7. During cutting and grinding, the tool and the grinding tool have not left the workpiece and are not allowed to stop;
8. It is not allowed to dismantle the safety protection device on the machine tool without authorization, and the machine tool lacking the safety protection device is not allowed to work;
9, the hydraulic system in addition to throttling and other hydraulic cutting is not allowed to adjust privately;
10. On the machine tool, especially the guide rail surface and the work surface, it is not allowed to directly place tools, workpieces, and other sundries;
11. Always remove iron filings and oil stains on the machine tool, and keep the rail surface, sliding surface, rotating surface, positioning reference surface and work surface clean;
12. Pay close attention to the operation of the machine tool and the lubrication situation. If abnormal phenomena such as malfunction, vibration, heat, crawling, noise, odor, and bump are found, stop the vehicle immediately and check the fault before proceeding.
13. When an accident occurs in the machine tool, immediately press the general stop button to keep the accident site and report to the relevant departments for analysis and processing;
14. It is not allowed to weld and repair the workpiece on the machine tool.
1. Mechanical, hydraulic, pneumatic and other operating handles, cutting doors, switches, etc. to the non-working position;
2, stop the machine running, cut off the power supply, gas source;
3. Remove iron filings, clean the work site, and carefully clean the machine. Refueling and maintenance of the guide surface, the rotating and sliding surfaces, the positioning reference surface, the work surface, etc.;
4. Carefully fill in the machine tool problems found in the class, fill in the shift record book, and do the shift work.
Fault diagnosis method
The electrical fault diagnosis of CNC machine tools has three stages: fault detection, fault judgment, isolation and fault location. The first stage of fault detection is to test the CNC machine to determine whether there is a fault; the second stage is to determine the nature of the fault and separate the faulty components or modules; the third stage is to locate the fault to a replaceable module or print Circuit board to reduce repair time. In order to find out the faults in the system in time, quickly determine the location of the fault and eliminate it in time. The fault diagnosis should be as small and simple as possible, and the time required for fault diagnosis should be as short as possible. To this end, the following diagnostic methods can be used:
Use the sensory organs to pay attention to various phenomena when a fault occurs, such as whether there is spark or malfunction when the fault occurs, whether there is abnormal noise, where the abnormal heat is generated, and whether there is a burnt smell. Careful observation of the surface condition of each printed circuit board that may have failed, with or without burnout and damage to further narrow the inspection range, is one of the most basic and most common methods.
CNC system self-diagnosis function
Rely on the ability of the CNC system to quickly process data, perform multi-channel and fast signal acquisition and processing on the faulty part, and then perform logic analysis and judgment by the diagnostic program to determine whether the system has a fault and locate the fault in time. The modern CNC system self-diagnosis function can be divided into the following two categories:
(1) Power-on self-diagnosis Power-on self-diagnosis means that the system's internal diagnostic program automatically executes modules such as CPU, memory, bus, I/O unit, and printed circuit board from the start of each power-on to the normal operation preparation state. , CRT unit, optoelectronic reader and floppy disk drive and other equipment before the functional test, to confirm whether the system's main hardware can work properly.
(2) Fault message prompt When a fault occurs during machine operation, the number and contents are displayed on the CRT display. Follow the prompts and consult the service manual to confirm the cause of the malfunction and how to eliminate it. In general, the richer the fault information of the CNC machine tool diagnostic function prompts, the more convenient it is for fault diagnosis. However, it should be noted that some faults can directly confirm the cause of the fault according to the fault content prompt and the manual. The true cause of some faults does not match the fault content prompt, or one fault indicates that there are multiple fault causes, which requires the repair personnel to Find out the intrinsic link between them and indirectly confirm the cause of the failure.
Data and status check
The CNC system's self-diagnosis not only displays fault alarm information on the CRT display but also provides machine parameter and status information in the form of multiple pages of “diagnostic address” and “diagnostic data”. Common data and status checks have parameter checksums. Interface check two.
(1) Parameter checks The machine data of CNC machine tools is an important parameter obtained through a series of tests and adjustments, which is the guarantee for the normal operation of the machine tool. These data include gain, acceleration, contour monitoring tolerances, backlash compensation values, and screw pitch compensation values. When external interference occurs, the data will be lost or confusing, and the machine will not work properly.
(2) Interface check The input/output interface signals between the CNC system and the machine tool include the interface inpu
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