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Damaged Carbide Milling Cutter

2017/09/06 Hits:

1 tool easy to break the factors
Formed carbide cutting cutters are widely used due to the small tolerance of the shape, because the blade can not be directly replaced, the cutter cut down most of the waste disposal, greatly improving the processing costs.
(1) the properties of the milling material
In the cutting of titanium alloy, due to the poor thermal conductivity of titanium alloy, chip easily bonded to the tip of the blade or the formation of BUE, in the vicinity of the tip of the knife on the formation of high temperature area, the tool red hardness loss, wear Intensified. In the continuous cutting under high temperature conditions, the binder and the weld are subject to subsequent processing of the impact, in the process of being forced to take away part of the tool material, resulting in tool defects and damage. In addition, when the cutting temperature reaches 600 ℃ or more, the surface of the parts will form hardened hard layer, the tool has a strong wear effect. Titanium alloy elastic modulus is low, elastic deformation, close to the flank surface of the workpiece surface rebound, so the surface has been processed with the flank contact area, wear serious.
(2) normal wear and tear
In the normal production and processing, when the continuous milling titanium alloy parts to 15mm-20mm margin when there will be serious blade wear situation. Continue to milling the efficiency is very low, and the workpiece surface finish is poor, can not meet the production and quality requirements.
(3) improper operation
Production and processing of titanium alloy casting box and box cover process, the assembly is unreasonable, cutting depth is not appropriate, the spindle speed is too fast, the cooling is not sufficient and other improper operation will lead to cutting tools, broken, broken and so on. In addition to this type of defect milling cutter can not be effective milling, but also in the milling process due to "gnawing knife" caused by the surface of the surface is depressed surface defects, not only affect the milling surface processing quality, serious cases will lead to scrap parts.
Improved method
(1) cutting edge micro-collapse
Cutting edge micro-collapse (that is, mild damage) is the most common situation, just through the grinding wheel will be part of the grinding edge of the grinding off, you can re-use the tool. Grinding carbide carbide cutter should use silicon carbide wheel, and can not be dipped in water grinding, otherwise the carbide will be completely scrapped due to cold cracking. The sharpening process is shown in Figure 1. Figure 2 shows the contrast between the new tool and the cutting tool.
After grinding the grinding machine, the effective length of the tool after grinding is shorter than that of the unused new tool, but this process indirectly enhances the tool rigidity, makes the processing surface quality better and improves the milling efficiency.
As the titanium alloy cast blank forming after the formation of hard and brittle uneven skin, can easily cause chipping phenomenon, making the removal of hard skin titanium alloy processing into the most difficult process. (2mm-4mm), to control the tip of the workpiece under the hard skin is appropriate, to prevent the tip of the direct contact with the crust and chipping phenomenon.
(2) change the tool geometry
In the tool sharpening process, you can change the tool geometry to improve the tool life, processing surface quality and cutting efficiency.
The study of the cutting edge part of the scrapped carbide cutter found that the cutting edge of the new tool was designed to be defective, that is, the lack of transition and transition. This is the main cutting edge strength is not enough, resulting in faster tool wear, prone to "chipping" phenomenon of the main reasons.
Through the edge of the grinding edge of the arc to achieve the edge of the cutting edge to add a circular transition blade to achieve the purpose of enhancing the tip strength, both to solve the cutting edge easy to wear, easy to chipping the problem, but also improve the workpiece surface finish and milling effectiveness. While reducing the cutting edge of the cutting thickness, in a smaller cutting thickness to form a machined surface, is conducive to improve the milling surface roughness. In addition, you can also repair the grinding edge, and make it parallel to the machined surface, play a smooth surface effect, improve the quality of the surface processing. Through repeated practice, we can get the radius parameters of the corresponding arc transition blade of different specifications.
Table 1 Common specifications End mill Rotary edge (mm)
(3) re-use of discarded knife handle
After the cutter has been repeatedly chipped and sharpened, the cutting edge portion is grinded and only the shank portion is left; or the tool is broken directly from the shank because of improper operation. In this case, you can use the remaining length of the remaining length of the handle by wire cutting, grinding, heat treatment and other methods into a single-shot, so that single-pole can be safe and effective use of the clamping range, both the use of its milling plane, , Chamfer, and can be used for boring, etc., to achieve the reusable tool waste. Figure 4 is a single knife that is processed by a scrapped handle.
In order to increase the rigidity and strength of the edge portion of the end mill, the corresponding part is subjected to heat treatment and surface coating, and the cutting part of the tool is specially treated. In view of this approach, in order to make better use of broken end mill cutter part (YG carbide) grinding into a single pole, need to heat quenching, the blade edge hardness increased to 54-57HRC, thereby improving the tool life The
After a large number of carbide scrap scissors to improve the practice and repeated use, has now formed a complete set of scrapped carbide cutter re-grinding into a single-pole process line: ① wire cutting knife handle cut; ② in the grinder blade Grinding the tip of the general shape; ③ edge quenching after heating into the salt in the cooling, so that the hardness of 54-57HRC; ④ fine grinding out the head part, the general order of grinding: grinding blade - Face - grinding razor face - grinding out the transition blade.
3 to improve the effect
Through the manual grinding method to scrapped carbide cutter into a reusable titanium alloy material for the special cutter, the type can be divided into cylindrical cutter, ordinary single-pole, T-type single-pole and so on. According to incomplete statistics, the use of the method has been successfully sharpened forming milling cutter about 100, repeated grinding more than 1200 times, and sharpening tool life longer than the re-sharpened 2-3 times.
In the actual processing, the use of sharpened Walterφ16mm cemented carbide end mill processing surface finish up to Ra1.6.
By analyzing the cause of the damage of the cemented carbide milling cutter, according to the different parts of the scraped carbide cutter and the length of the available parts, the broken edge of the micro-cutting edge is increased by hand, The tool holder is reworked into a single-pole method to re-use the scrapped carbide cutter to improve service life and milling efficiency, significantly reducing processing costs.