JPS61204375A - coated hard alloy - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a coated hard alloy for cutting metals, etc., and in particular to a coated hard alloy for tools with excellent chipping resistance suitable for interrupted cutting (milling). It concerns alloys.

[Prior art]

Conventionally, coated hard alloys, in which the surface of hard sintered alloys such as cemented carbide and cermets are coated with various ceramics using chemical vapor deposition (hereinafter abbreviated as CVD method), have been mainly used for turning purposes. It is well known that the coated hard alloy described above has higher wear resistance than hard sintered alloys that do not have a layer [problem to be solved by the invention]. There are problems. One of the reasons for this is thought to be that after the hard sintered alloy is coated, tensile stress acts near the surface layer and the chipping resistance decreases.Therefore, the coated hard alloy obtained by the CVD method It is often unsuitable as a milling tool that is subject to intermittent impact. As a countermeasure to these problems, coated hard alloys treated by physical vapor deposition (PvD method), which have excellent fracture resistance, are used, but PVD method has disadvantages such as higher cost compared to CDv method. There is.

[Purpose of the invention]

The present invention coats hard sintered alloys such as cemented carbide and Sarno-Lido using the CvD method, which is cost-effective and has high fracture resistance that can withstand use for milling. The purpose is to develop coated hard alloys.

[Means for solving problems]

In view of the above-mentioned problems, the present invention solves the problems with the following configuration.

In other words, the base materials such as cemented carbide and Sarno Lido are used as Rock Uni A/A Skate/I/ (hereinafter referred to as HRA).
It has a hardness of 87 to 90, and the surface of the base material is coated with Tic, TiN, T1CN, Al2O3 by chemical vapor deposition method.
One or two of these are coated hard alloys on which a layer thickness of 0.5 to 70 μm is formed.

[Action of the invention]

In the present invention, the hardness of the cemented carbide or cermet that is the base material of the coated hard alloy can be controlled mainly by changing the amount of binder phase or the particle size of carbide or carbonitride. Therefore, for example, by increasing the amount of binder phase in the base material, the hardness of the base material decreases, but the toughness increases, which increases the effect of preventing the extension of surface cracks that occur in the coating layer, and as a result, the cutting edge chipping or chipping is less likely to occur. However, if the hardness of the base material is reduced too much, chipping or chipping will hardly occur (but the amount of plastic deformation of the base material itself will be large, even in interrupted cutting where the cutting edge temperature is lower than in continuous turning). This is based on the knowledge that wear increases with plastic deformation.

The reason why the hardness of the base material of the coated hard alloy such as cemented carbide or cermet is limited to a range of HRA 87 to 90 is because plastic deformation of the cutting edge occurs when using the base material with HRA less than 87. This is because the cutting tool is not able to fully demonstrate its performance as a cutting tool, and there is a high risk of breakage or chipping of the cutting edge during cutting in coated hard alloys coated using base materials that exceed HRA90. It is.

On the other hand, Tic, Tj-N, T1 coated on the base material
The layer thickness of one or more of CN and AjHO3 is 0.5
The reason why the layer thickness is limited to ~7.0 μm is that if the layer thickness is less than α5 μm, sufficient wear resistance cannot be obtained and the intended purpose cannot be achieved, and if the layer thickness exceeds 7.0 μm, the coating will fail. The layer is likely to peel off from the base material and chiliving may occur, which is not a desirable condition for a cutting tool as it will shorten its life.

〔Example〕

Examples will be described below.

Powders such as raw materials WC, Tj-C, TaC, Co, etc. are blended, mixed in a wet ball mill, dried, press shaped, and vacuum sintered at 1360-11100°C x 60ml to form the coated hard alloy according to the present invention. I made the base material.

This was ground and made into SNG 1153 insert.
Next, a coating was formed on the surface by CVD.

In addition, in order to compare with the coated hard alloy of the present invention, Comparative Examples A and B in which the hardness of the base material is outside the range of the base material according to the present invention were sintered and ground in the same manner as above to obtain SNG 1135.
A film was formed on the surface of the insert by CVD. Comparative Example C was also prepared, in which only the thickness of the coating layer was outside the range of the base material of the present invention. Details of each sample described above are shown in the table below.

Each of the inserts shown in the table above was fixed to a crosshair, and this was attached to a machine tool at a cutting speed of 150 m/min and a depth of cut of 5.
0 tm, feed rate per tooth 850 under cutting conditions of α55
A cutting test was conducted on a rigid material of 0.

As a result, Comparative Example A became uncuttable due to the insert being damaged at a cutting length of α3m, and Comparative Example B became uncuttable due to abnormal wear associated with plastic deformation at a cutting length of α5m. Further, in Comparative Example C, the coating layer peeled off at a cutting length of 0.6 m, whereas the coated hard alloys according to the present invention did not chip even at a cutting length of 2 m, and the wear state was normal.

Next, an interrupted turning test was conducted using the inserts shown in the table above.

The conditions are as follows.

Covering material 2 SCMlILI5 (grooves were provided at 4 locations on the outer periphery) Cutting conditions: Cutting speed = 120 m, /+ = , depth of cut = 2.5 rrm, feed = 0.15 u/reV 100 impacts starting from Every ton of feed is 0.15
rtrm, maximum 1.3 by increasing by 1 rev
As a result of the above tests performed up to 5M/rev, Comparative Example A has 330 impacts (feed α60
11aR/rev), Comparative Example B was 57ml.
At the 0th turn (at a feed rate of 0.60 w11/rev), the cutting edge plastically deformed and became uncuttable. Comparative example C is 311
On the other hand, the coated hard alloy according to the present invention suffers from chipping at 0 times (at a feed rate of α60 mm/reV) and becomes uncuttable, whereas the coated hard alloys of the present invention all have impact times of 900 times (at a feed rate of 1-55 wR).
/rev), cutting was possible with no defects observed.

〔Effect of the invention〕

As mentioned above, the coated hard alloy of the present invention has excellent fracture resistance, and is not only effective when used in cutting tools for turning such as milling machines and milling cutters, but also excellent when used in interrupted turning. It is a coated hard alloy that has a wide range of applications and is used in wear-resistant tools that require high performance and impact resistance.

Claims (1)

[Claims] (1) The base material, such as cemented carbide or cermet, has a hardness of 87 to 90 on the Rockwell A scale, and the surface of the base material is coated with TiC, TiN, TiCN, Al, etc. by chemical vapor deposition.
0.5 to 7.0 μm of one or more of _2O_3
A coated hard alloy characterized by forming a layer thickness of .