RU2278905C2 - Method of production of the multilayer coating for the cutting tool - Google Patents

Abstract

FIELD: mechanical engineering; methods of deposition of the wear-resistant coatings on the cutting tools.

SUBSTANCE: the invention is pertaining to the methods of deposition of the wear-resistant coatings on the cutting tools and may be used in the metal working. The invention presents the method of production of the multilayer coating for a cutting tool, which includes the vacuum-plasma deposition of the coating layers, which include the lower layer made out of the titanium and silicon compound doped with chromium, the upper layer made out of titanium nitride or carbonitride and silicon, and the intermediate layer made out of the upper layer material doped with chromium. At that deposition of the coating layers is conducted by the horizontally located in the single plane three cathodes, two of which are placed oppositely and made composite out of titanium and silicon, and the third electrode is made composite out of titanium and chromium. Instead of silicon it is possible to use molybdenum, zirconium and aluminum.

EFFECT: the invention ensures production of the cutting tools with reliable wear-resistant coatings.

4 cl, 1 tbl

Description

The invention relates to methods for applying wear-resistant coatings to a cutting tool and can be used in metalworking.

There is a method of increasing the resistance of a cutting tool, in which a wear-resistant coating of titanium nitride (TiN) or titanium carbonitride (TiCN) is applied by vacuum-plasma method to its surface (see Tabakov V.P. Performance of a cutting tool with wear-resistant coatings based on complex nitrides and titanium carbonitrides. Ulyanovsk: UlSTU, 1998.123 s.).

The reasons that impede the achievement of the technical result indicated below when using the known method include the fact that in the known method, the applied coating does not provide the same high efficiency when the cutting tool is used with this coating under intermittent cutting conditions, in particular during milling, as during continuous cutting.

The closest method of the same purpose to the claimed invention in terms of features is a method of increasing the resistance of the cutting tool, comprising applying to the tool base of a hard alloy a multilayer wear-resistant ion-plasma coating consisting of an outer layer of titanium nitride TiN with a thickness of 4 μm and a lower layer of titanium carbonitride TiCN with a thickness of 2 microns (see Smirnov M.Yu. Improving the performance of end mills by improving the design of wear-resistant coatings. Diss .... Candidate of Technical Sciences., - U yanovsk -. 2000 - 232), taken as a prototype..

For reasons that impede the achievement of the following technical result when using the known method adopted as a prototype, the multilayer coating in the known method contains layers of titanium nitride and carbonitride having low adhesion strength to the tool base and to each other and low crack resistance. As a result, the coating poorly resists the processes of wear and tear and quickly collapses when cutting.

Recently, the increase in the cost of metal-cutting tools and stricter requirements for the accuracy of machined parts have made the problem of increasing the resistance of the cutting tool even more urgent. The main reason for the destruction of the coating is the occurrence of cracks due to deformation of the cutting wedge and adhesion-fatigue phenomena, which are the cause of the appearance of chipping material wear-resistant coating on the contact pads. Moreover, for multilayer coatings, layer separation is observed under the influence of descending chips. One of the ways to increase the resistance and, as a consequence, the performance of a coated cutting tool is to apply multilayer coatings with layers with different physical and mechanical properties, which makes it possible to create barriers in the form of boundaries between layers on the crack path. The presence in the coating of an intermediate layer having high residual compressive stresses further enhances the crack resistance of the coating. To increase the adhesion strength of the coating to the tool base, it should include a lower layer with improved adhesive properties. An increase in the adhesion strength of the layers is ensured by their chemical affinity for each other.

The technical result is an increase in the efficiency of the cutting tool.

The specified technical result in the implementation of the invention is achieved by the fact that they produce vacuum-plasma deposition of coating layers.

The feature of the proposed method lies in the fact that the lower layer is applied from a compound of titanium and silicon doped with chromium, the upper layer is from titanium nitride or carbonitride and silicon and the intermediate layer is from the material of the upper layer doped with chromium, while the coating layers are applied horizontally in one the plane with three cathodes, two of which are located opposite and are made of titanium and silicon, and the third is made of titanium and chromium. Instead of silicon, molybdenum, aluminum, zirconium are also used. This coating structure allows to obtain high adhesion to the base of the lower layer, which has high adhesion to the tool base. Introduction to the lower layer as an alloying element of chromium enhances its strength properties. In this case, the intermediate layer has high compressive stresses necessary for braking the cracks. The presence between the upper and lower layers of the transition layer, including the components of the upper and lower layers, increases the bond strength of the layers in the coating. The transition layer also contributes to a smoother change in the mechanical properties of the coating from the lower layer to the upper. An increase in crack resistance is facilitated by the layered structure of the coating, due to which cracks are inhibited at the boundaries of the layers.

The invention consists in the following. In the coating during intermittent cutting, cracking processes occur, leading to its destruction. In addition, due to insufficient adhesion to the tool base and layers inside the multilayer coating, the latter can be destroyed as a result of adhesion-fatigue phenomena on the contact pads. Under these conditions, the coating should have a layered structure with areas of different hardness to inhibit cracks. The bottom layer of the coating must have high adhesion to the tool material. The intermediate layer must have a high level of residual compressive stresses to increase crack resistance. In this case, the upper and lower layers of the multilayer coating should have high bond strength with each other, which is ensured by the introduction of an intermediate layer containing the components of the upper and lower layers.

Coated plates obtained with deviations from the indicated production technology showed lower results.

For experimental verification of the claimed method, a prototype coating was applied with a layer ratio corresponding to the optimal value specified in the known method, as well as a three-layer coating according to the proposed method. The coatings were applied to carbide plates in the vacuum chamber of the Bulat-6T installation, equipped with three vacuum-arc evaporators located horizontally in the same plane.

The proposed coating is as follows. MK8 carbide inserts (4.7 × 12 × 12 mm in size) are washed in an ultrasonic bath, wiped with acetone, alcohol and mounted on a rotary device in the vacuum chamber of the Bulat-6 installation equipped with three evaporators located horizontally in the same plane. Two opposite composite cathodes of titanium and metal Me (silicon, molybdenum, aluminum, zirconium) and a composite cathode of titanium and chromium are used. The chamber is pumped out to a pressure of 6.65 · 10 ^-3 Pa, the rotary device is turned on, a negative voltage of 1.1 kV is applied to it, one evaporator is turned on, and at an arc current of 100 A, the plates are cleaned and heated to a temperature of 560-580 ° C. The focusing coil current is 0.4 A. Then, with a negative voltage of 160 V and a coil current of 0.3 A, all three evaporators are turned on and a 2.0 μm thick TiMeCr coating is deposited. A second layer of TiMeCrN (or TiMeCrCN) with a thickness of 2 μm is applied at a negative voltage of 160 V, a coil current of 0.3 A, a supply of nitrogen (or a mixture of nitrogen and acetylene) and the inclusion of all three evaporators. A third layer of TiMeN (or TiMeCN) with a thickness of 2 μm is applied at a negative voltage of 160 V, a current of coils of 0.3 A, the Ti-Me evaporators turned on, and a supply of reaction gas — nitrogen (or a mixture of nitrogen and acetylene). Then shut off the evaporators, the supply of reaction gas, voltage and rotation of the device. After 15-20 minutes, the chamber is opened and the coated tool is removed.

Durable tests of the cutting tool were carried out with symmetrical face milling of 5XNM steel blanks on a 6P12 machine. Tested carbide inserts grade MK8, processed according to the known and proposed methods. The cutting conditions were as follows: cutting speed V = 247 m / min, feed S = 0.4 mm / tooth, cutting depth t = 1.5 mm, milling width B = 20 mm. For the wear criterion, the value of the chamfer of wear on the rear surface h ₃ = 0.4 mm was taken.

As can be seen from the data in table 1, the resistance of the plates processed by the proposed method is higher than the wear resistance of the plates processed by the prototype method by 1.9-2.5 times.

Table 1
Coated Cutting Tool Test Results No pp Coating material The thickness of the coating layers, microns Resistance, min Note 1 layer 2 layer 3 layer one 2 3 four 5 6 7 The processed material is 5XNM, V = 247 m / min, S = 0.4 mm / tooth, t = 1.5 mm, B = 20 mm. one Tin 6 - - 45 Analogue 2 TiCN-TiN 2 four 110 Prototype 3 TiSiCr-TiSiCrN-TiSiN 2 2 2 242 - four TiSiCr-TiSiCrCN-TiSiCN 2 2 2 270 - 5 TiCrCr-TiMoCrN-TiMoN 2 2 2 211 - 6 TiCrCr-TiMoCrCN-TiMoCN 2 2 2 228 - 7 TiAICr-TiAICrN-TiAIN 2 2 2 243 - 8 TiAICr-TiAICrCN-TiAICN 2 2 2 259 - 9 TiZrCr-TiZrCrN-TiZrN 2 2 2 244 - 10 TiZrCr-TiZrCrCN-TiZrCN 2 2 2 266 - 1. Tool material - MK8.

Claims (4)

1. A method of obtaining a multilayer coating for a cutting tool, including vacuum-plasma deposition of coating layers, characterized in that the lower layer is applied from a compound of titanium and silicon doped with chromium, the upper layer is made of titanium nitride or carbonitride and silicon and the intermediate layer is made from the material of the upper layer doped with chromium, while the deposition of coating layers is carried out horizontally in the same plane by three cathodes, two of which are oppositely made and made of titanium and cre opinion, and the third is made of titanium and chromium. 2. A method of obtaining a multilayer coating for a cutting tool, including vacuum-plasma deposition of coating layers, characterized in that the lower layer is applied from a compound of titanium and molybdenum alloyed with chromium, the upper layer is made of titanium nitride or carbonitride and molybdenum and the intermediate layer is made from the material of the upper layer doped with chromium, while the deposition of coating layers is carried out horizontally in the same plane by three cathodes, two of which are located opposite and are made of titanium molybdenum, and operates the third composite of titanium and chromium. 3. A method of obtaining a multilayer coating for a cutting tool, including vacuum-plasma deposition of coating layers, characterized in that the lower layer is applied from a compound of titanium and zirconium doped with chromium, the upper layer is made of titanium nitride or carbonitride of titanium and zirconium, and the intermediate layer is made from the material of the upper layer doped with chromium, while applying the coating layers is carried out horizontally in the same plane by three cathodes, two of which are located opposite and are made of titanium and c irkonium, and the third is made of titanium and chromium. 4. A method of obtaining a multilayer coating for a cutting tool, including vacuum-plasma deposition of coating layers, characterized in that the lower layer is applied from a compound of titanium and aluminum alloyed with chromium, the upper layer is from nitride or carbonitride of titanium and aluminum, and the intermediate is from the material of the upper layer doped with chromium, while the deposition of coating layers is carried out horizontally in the same plane by three cathodes, two of which are opposite and are made of titanium and luminium, and the third is made of titanium and chromium.