Cutting tool

Abstract

The invention provides a cutting tool. The cutting tool comprises a cutting edge and a coating formed on the cutting edge. The cutting edge comprises a front tool face, a rear tool face and a blade connected between the front tool face and the rear tool face. The blade comprises an exposed part which is not covered with the above coating. The coating comprises a thickness gradual change part. Thethickness of the part, close to the exposed part, of the thickness gradual change part is smaller, the thickness of the part, away from the exposed part, of the thickness gradual change part is larger, the thickness gradual change part meets that Tmin / Tmax<=0.58, Tmin is the thickness of the thinnest portion of the thin end of the coating in the thickness gradual change part, and Tmax is the thickness of the thickest portion of the thick end of the coating in the thickness gradual change part. The width W of the exposed part=k*Tmax, and 0.2<=k<=20.

Description

technical field [0001] The invention relates to the field of mechanical finishing, in particular to a cutting tool capable of superfinishing. Background technique [0002] With the continuous development of science and technology, the demand for precision machining of various workpieces is getting higher and higher. For example, metal cutting has gradually developed from ordinary rough and finish machining to superfinishing and nanoscale machining. It is even expected that the cutting process of the surface of the metal workpiece can directly meet the requirements of the mirror effect without subsequent polishing treatment. [0003] In the past, for the cutting of metal workpieces with relatively low processing accuracy and surface roughness requirements, uncoated bare tools can also be used for processing. However, for high finish, high brightness of the cutting surface, or ultra-finishing requirements, it must be processed with a tool protected by a hard coating. Becaus...

AI Technical Summary

Problems solved by technology

But the cutting tool that uses coating protection in the prior art also often has the following defects: the surface finish of the tool edge coating is low and the consistency is poor, and there are defects such as liquid droplets, pits, and serrations at the cutting edge; During the process, the coating on the cutting edge often has chipped film with a size of micron or above, which can easily lead to sticky chips

[0006] 1. For the sputtering deposition process, its main defect is that the low energy of the deposited particles leads to low bonding strength between the coating and the substrate, and between coating grains and grains, making it difficult to avoid chipping and chipping during cutting. Phenomenon

Therefore, the direction of improvement is to use high-energy pulse sputtering. High-energy pulse sputtering has improved the bonding strength of particles, but it will bring new problems, such as severe ash falling in the furnace chamber and the appearance of point-like particles on the surface of the coating, resulting in surface damage. The smoothness becomes poor, and the internal stress of the coating also increases, and the coating chipping occurs on the cutting edge

At present, there is no suitable coating process in application to solve the above problems

[0007] 2. For the cathodic arc deposition process, the main problem is the poor surface finish caused by the droplets, and the local fragmentation of the film due to the high stress of the film layer during cutting

[0014] Although the droplets on the coating can be reduced or removed through the above-mentioned various coating post-treatment processes, or the surface roughness of the coating can be optimized to a predetermined range, but no matter which coating passivation process is used, the above-mentioned coating For the passivated tool, the coating on the cutting edge is still extremely prone to local peeling after the tool has been used for a period of time, resulting in scratches or cutting lines on the processed surface, and it is easy to cause chip sticking on the tip of the tool

All in all, the above-mentioned various coating process optimization methods, as well as the coated tools after coating treatment, are still difficult to meet the actual requirements in terms of performance, and the machine yield rate is very low, which cannot be used in mass production at all.

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