What is boring in machining? And how to apply?
1. Definition of boring
Boring: It is the cutting process of cutting the surface of the workpiece by the relative movement between the file and the workpiece on the equipment, so that a layer of metal is cut off from the machined surface and the machining surface is obtained with certain machining precision and surface roughness.
Difference: Compared with other hole machining processes, the boring is not limited by the size of the tool; and the boring has a strong error correction capability, and the error of the original coarse hole axis can be corrected by multiple passes, and The hole and positioning reference maintain a high positional accuracy.
2, the type of sickle
Type 1. Blade number classification: single-edged trowel/double-edged trowel/multi-blade boring tool. Processing classification: through-hole boring tool/blind hole boring tool/stepped hole boring tool/section boring tool. Structure classification: integral type/ Assembly / modular.
Type 2. Single-edged boring tool: integral boring tool / welding boring tool / machine clamp boring tool / indexable boring tool. Double blade boring tool: fixed double blade boring tool / floating double blade boring tool
Expand boring tool Module boring boring tool Step boring tool Single blade boring tool Overall boring tool
Third, the application of boring
When we encounter problems, we can first consider these aspects.
3.1, rough application:
1, blind hole processing
When machining blind holes, it is important to ensure proper chip removal. Correct cutting parameters are necessary to obtain proper chip shape. Ensure/check that the chips are not obstructed or wear the blade. The coolant pressure and cutting fluid flow should be sufficient to allow the chips to drain. Machine tools have higher requirements for effective chip removal than horizontal machine tools.
2, interrupted cutting
When performing interrupted cutting (such as cross-holes), the cutting conditions of the inserts are highly demanded. Select a material with higher toughness. Under stable conditions, in order to improve the processing safety, choose a solid square negative rake basic shape. Blade. If there are multiple interruptions, reduce the cutting parameters.
3, sand casting cast iron
Sand inclusions in the casting increase the wear of the insert. Select a material with higher toughness. Reduce cutting parameters. To improve machining safety and minimize wear, choose a solid square negative rake basic shape insert. PS: Sand is meant There are sand inclusions on the casting.
4, gas burning hole
The local area of the gas burnt hole may harden, which will aggravate the wear of the blade. Select a material with higher toughness. Reduce the cutting parameters. In order to improve the processing safety and minimize wear, choose a solid square negative rake angle basic shape blade.
3.2, fine application
1, cutting force
Effect of cutting force on the product When the tool is in the cutting state, the tangential and radial components of the cutting force will attempt to deflect the tool away from the workpiece. The tangential element will attempt to force the tool down and away from the centerline. In this way, the tool clearance angle is reduced. Any radial deformation means that the depth of cut and the thickness of the chip are reduced, resulting in a tendency to vibrate.
The effect of balancing forces on machining The imbalance caused by asymmetric tools or large strokes produces a force that acts on the file. In most applications, the force generated by the imbalance is negligible compared to the cutting force. At high speeds, imbalance can cause vibration and affect the quality of the hole.
Fourth, the pupil case
4.1 blade wear
In the boring process, the tool is continuously cut, which is prone to wear and breakage, reduces the dimensional accuracy of the hole machining, and increases the surface roughness value. At the same time, the adjustment of the fine-tuning feed unit is abnormal, resulting in adjustment error causing deviation of the machining aperture. Even caused product quality accidents.
4.2 Surface quality
The scaly or thread-like cut of the machined surface is a common surface quality phenomenon. Left: mainly due to mismatch between boring feed and drilling speed. Right: rigid vibration mainly due to boring And the tool wear caused.
Five, boring Q and A
Q: How to use the spindle positioning when machining?
A:1 Using the dial gauge measuring device to find the positioning method, you must first use the dial gauge centering device or positioning mandrel to set the reference hole coordinates on the workpiece, and then determine the spindle according to the reference hole coordinates. Coordinate position. Its characteristics are high precision and convenient operation. 2 Using the test rod to find the correct positioning This method is characterized by low positioning accuracy and time consuming. However, this positioning method can directly find the coordinate position of the main shaft of the boring machine and the starting hole. 3Using the interface of the hole to form the positive positioning This method is characterized by the boring process of the separate box hole system. The disadvantage is that the auxiliary time is longer. 4 Using the template to find the correct positioning This method is characterized by simple structure and no complicated adjustment. However, the template is easy to deform, and when the workpiece needs to process several different surface holes, several samples are needed, and the alignment and positioning accuracy are also low.
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