JP5256384B2 - Multilayer carbide chip and manufacturing method thereof - Google Patents

Description

  The present invention relates to a hard cutting body of a cutter bit, which is a tool for excavation in a shield machine, for example, a cemented carbide chip suitable for constituting a cutting blade, a die, and the like, and a method for manufacturing the same.

  For example, a cutter bit of a shield machine generally has a cemented carbide chip (hereinafter referred to as “carbide chip”), which is a hard blade, fixed to a steel shank. Since the shield machine is used for tunnel tunneling underground, the cutter bit not only has high cutting performance such as earth and sand, but also needs to use a high-strength machine that does not easily break during excavation. is there. This is because, if the cutting edge is lost during excavation, not only the cutting performance is remarkably lowered, but also other blades are damaged by the fragments, and the cutter bit cannot be exchanged during excavation in the basement. Therefore, the carbide chip constituting the blade body is particularly required to have particularly excellent impact resistance.

  The cemented carbide is obtained by dispersing high-hardness metal carbide particles in a binder metal matrix, and WC, TiC, TaC or the like is used as the metal carbide particles. In addition, Co, Ni, Fe, or the like is used as the metal forming the binder layer, and the WC-Co alloy is the most common as the composition of the cemented carbide tip for the cutter bit.

  In general, cemented carbide has finer particles of carbide (WC, etc.), and the smaller the binder layer (cobalt Co layer, etc.), the higher the hardness, the better the wear resistance, the coarser the particles of carbide, the more binder layer, There is a tendency that toughness (strength) is improved, impact resistance is excellent, and defects are hardly generated. That is, the hardness and strength of the cemented carbide are conceptually contradictory, and usually a cemented carbide chip according to the application is obtained by adjusting the carbide particle size and the amount of the binder layer.

  The cutting performance and wear resistance of the cutter bit are improved by increasing the hardness of the blade. However, as described above, a hard chip having a high hardness has a drawback of being easily damaged by an impact, and therefore various measures have been made to achieve both wear resistance and impact resistance. The following patent documents represent these examples.

JP 2006-241681 A Japanese Unexamined Patent Publication No. 7-3306 JP-A-9-78986 JP 2005-36281 A Japanese Utility Model Publication No. 5-16897 Japanese Utility Model Publication No. 4-53879

  The one described in Patent Document 1 is a cutter bit in which a soft tip made of a cemented carbide and a hard tip are brazed to a base material with a joining material interposed therebetween. A material similar to an alloy and made of a softer material than the soft tip is used. The cutter bit maintains wear resistance with a hard tip, and shocks are buffered with a soft tip, thereby achieving a long life.

  Moreover, the thing of the said patent document 2 is what the cemented carbide alloy and the cemented carbide alloy for joining were diffusion-bonded, and the ratio of the coupling layer in the said cemented carbide alloy for joining is the said high hardness. 10 to 45% by weight more than the proportion of the bonding layer in the cemented carbide.

  Further, the one described in Patent Document 3 is a cutter bit such as a shield machine, and is a multilayer chip formed by brazing a plurality of layers of carbide chip pieces having different materials such as hardness and toughness with a copper plate interposed therebetween. Is a blade body, which is brazed to a steel base metal.

  Patent Document 4 describes a technique in which cemented carbide members are brought into direct contact with each other at a joining surface and pulsed energization is performed while applying pressure between the two alloy members to integrate them. Patent Document 5 describes a cutter bit of a tunnel machine, in which hard chips and soft chips are alternately stacked and integrated by brazing and fixed to the cutter bit body. Further, Patent Document 6 describes that the cutting edge portion of the cutter bit chip is made of an ultrafine cemented carbide and the other portion is made of a medium or coarse cemented carbide.

  Although the thing of the said patent document 1 is what fixedly integrated the hard chip | tip, the soft chip | tip, and steel materials mutually by brazing, it needs a troublesome trouble to braze several layers simultaneously. Moreover, since the cemented carbide chip is vulnerable to thermal shock, there is a possibility that a minute crack will be formed by brazing and it may be lost during use. There is also a problem that peeling between the brazing filler metal layer and the cemented carbide tip tends to occur during use.

  In the above-mentioned Patent Document 2, a high-hardness cemented carbide chip and a low-hardness cemented carbide chip are joined by diffusing each other's binder layer. Since the binder layer on the low-hardness carbide tip side diffuses, there is a problem that the hardness of the high-hardness carbide tip is lowered and the toughness of the low-hardness carbide tip is lowered. Further, it is difficult to diffuse the binder layer well so that a desired bonding strength can be obtained, and peeling or damage is likely to occur under severe use conditions such as a cutter bit.

  As described in Patent Document 3 and Patent Document 5, a plurality of cemented carbide chips are integrated by brazing similarly to Patent Document 1, and these are also the same problems as those described in Patent Document 1. have. Furthermore, although the thing of the said patent document 4 joins different carbide | carbonized_metal chip | tips by welding by pressurization and pulse electricity supply, it is difficult to obtain sufficient intensity | strength by this method.

  Moreover, the thing of the said patent document 6 is comprised by the ultra-fine-particle cemented carbide alloy with high hardness, and the other part was comprised by the medium grain or coarse grain cemented carbide, However, if it is intended to be manufactured, the movement of particles and the growth of crystal grains may occur during sintering, and the composition may change, and it is extremely difficult to obtain an ideal hardness gradient state.

  Therefore, the present invention provides a cemented carbide tip having both wear resistance and impact resistance by improving the above-mentioned conventionally known technique and adopting a joining method having strength superior to brazing. It is an issue.

In order to solve the above problems, the present invention has the following configuration. That is, the manufacturing method of the laminated carbide inserts according to the present invention, the cemented carbide chips consisting of the junction plane Migaku Ken the WC-Co cemented carbide, cobalt, thin plate made of nickel or high-cobalt cemented carbide By superposing the bonding material on the top and bottom and heating to a temperature of 1300 to 1400 ° C. in a non-oxidizing atmosphere, a liquid phase is generated in the bonding material and penetrated into the cemented carbide chip. It is characterized in that hard chips are integrated with each other through a bonding material.

The heating is preferably performed in a vacuum of 3 to 10 torr.

The laminated carbide chip according to the present invention is a laminated carbide chip manufactured by the manufacturing method according to claim 1 or 2.

  A multilayer cemented carbide tip according to the present invention, in which a plurality of different types of cemented carbide tips, for example, a hard cemented carbide tip excellent in wear resistance and a tough, soft cemented carbide tip are laminated. However, it is possible to achieve both wear resistance and impact resistance with a single tip, and it is excellent for a long time even when used as a cutter bit blade body. In addition to maintaining high cutting performance, the blade is less likely to be damaged. Since the bonding material diffuses and penetrates into the cemented carbide chips on both sides, a higher bonding strength can be obtained than brazing or the like. Moreover, according to the method for manufacturing a laminated carbide chip according to the present invention, it is possible to relatively easily produce the above-described excellent performance laminated carbide chip, and it is possible to maintain stable quality. . It is also possible to manufacture a large-sized carbide chip or a complex-shaped carbide chip by joining and integrating the same type of carbide chips together.

  Hereinafter, embodiments of the present invention will be specifically described. FIG. 1 schematically shows the structure of a laminated carbide tip according to the present invention that can be used as a blade of a cutter bit. The laminated carbide tip 1 shown in FIG. A chip having a two-layer structure in which a cemented carbide chip A and a cemented carbide chip B having a lower hardness than the cemented carbide chip B are bonded and integrated with each other through a bonding material S. The laminated chip 1 shown in FIG. This is an example of a chip having a three-layer structure in which a cemented carbide chip A, a cemented carbide chip B, a cemented carbide chip B, and a cemented carbide chip C are joined together by a joining material S. In some cases, four or more types of cemented carbide tips can be joined and integrated.

  In this way, it is possible to achieve both wear resistance and impact resistance by laminating and integrating multiple types of cemented carbide tips of different materials, and at the edge of the cutter bit where wear resistance is required. Uses a high-hardness tip A to maintain good cutting performance, and impact resistance decreases with a high-hardness tip alone. Therefore, a high-toughness tip B with a relatively low hardness is used on the base side of the cutter bit. To ensure impact resistance.

  As disclosed in the above-mentioned patent document, in order to achieve both wear resistance and impact resistance of a cemented carbide tip, a method of joining and integrating a plurality of types of cemented carbide tips of different materials has been conventionally employed. However, the present invention is characterized in that this joining and integration is performed using a joining material. That is, conventionally known methods include brazing of multiple types of carbide tips, mutual diffusion, welding by pressurization and pulse energization, etc., but as described above, each of these methods has its own problems and is severely used. It was not satisfactory as a cemented carbide tip for a cutter bit exposed to the conditions. The present invention is an improvement of these conventional bonding methods, and by interposing a bonding material that diffuses and penetrates into a plurality of types of cemented carbide chips, different types of chips can be bonded and integrated with high strength. It is.

  As shown in the above example, the cemented carbide tip A used for the cutting edge portion of the cutter bit is a cemented carbide with a relatively high hardness. Specifically, the average particle size of carbide (WC) is 2 to 5 microns. Thus, a WC-Co cemented carbide having a binder (Co) amount of about 7 to 10% (% by weight, hereinafter the same) is preferable. Further, the material of the impact resistant carbide tip B that supports the carbide tip of the blade edge part is a WC-Co-based super-carbide carbide having an average particle size of 2 to 6 microns and a cobalt content of 11 to 20%. Hard alloys are preferred.

  As a joining material for joining the different types of chips, metals used as cemented carbide binders, such as cobalt and nickel, can be used, but usually the same kind as the cemented carbide binder layer to be joined is used. Is preferred. Since the temperature at which the liquid phase appears is higher than that of cobalt, nickel tends to cause carbide grain growth of cemented carbide. For this reason, it is preferable to use cobalt as the bonding material. These bonding materials can be plate-shaped or foil-shaped. In some cases, a high-cobalt cemented carbide with a very large amount of Co (for example, a Co amount of 20% or more) can be used as a bonding material. In this case, cobalt, which is a binder layer of a high cobalt alloy, permeates the cemented carbide chips on both sides and is joined.

  The manufacturing method of the laminated cemented carbide chip according to the present invention is as follows. First, carbide chips having a plurality of types of compositions are manufactured. The cemented carbide chip can be manufactured by a known powder metallurgy method in which carbide powder and binder metal powder are mixed, pressed into a predetermined shape and size, and sintered. The bonded surfaces of the obtained multiple types of cemented carbide chips are polished and heated to a predetermined temperature in a non-oxidizing atmosphere, preferably in a vacuum, with the plate-shaped bonding material sandwiched therebetween. When cobalt or nickel is used as the bonding material, the thickness is preferably 1 mm or less, and preferably 0.5 mm or less. Moreover, when using a high cobalt cemented carbide as a bonding material, the thickness is preferably about 1 to 3 mm, and more preferably 2 mm or less. The finer the surface roughness of the joint surface, the better the bondability, but usually it is preferably 25 microns or less, more preferably 20 microns or less.

  FIG. 2 shows this heating state. As shown in the figure, when heating, an appropriate weight P (a tungsten block having a high specific gravity and excellent heat resistance is used on the upper carbide chip. (Preferably) is preferably placed. The heating temperature is equal to or higher than the temperature at which the liquid phase appears in the bonding material, and is usually 1300 to 1400 ° C., which is about the same as the sintering temperature. If the heating temperature is too low, sufficient penetration is not performed and the bonding strength is insufficient. On the other hand, if the heating temperature is too high, grain growth occurs and the performance of the cemented carbide tip may be deteriorated. Heating for bonding is preferably performed using a vacuum furnace. In this case, the degree of vacuum is preferably a low degree of vacuum (3 to 10 torr) that can prevent evaporation of the bonding material. The heating time for joining is usually 30 to 60 minutes.

  FIG. 2 schematically shows a state in which only a plurality of cemented carbide chips are joined. To attach a cemented carbide chip laminated to a steel shank (base metal) such as a cutter bit, What is necessary is just to adhere by brazing. In some cases, the cemented carbide chip and the shank are overlapped with a bonding material such as nickel sandwiched between the lower surface of the lowermost cemented carbide chip and the shank when bonding the laminated carbide chips. It is also possible to perform bonding between the carbide chips and bonding to the shank at the same time. However, if the steel shank is heated to a high temperature, the structure may change and the strength may be lowered. Therefore, it is preferable to braze the laminated carbide tip 1 to the shank.

  [Example 1] Carbide tip A with carbide average particle size of 3.0 microns and cobalt content of 8% and carbide tip B with carbide average particle size of 3.5 microns and cobalt content of 13% (all WC-Co alloy). As a bonding material S, a cobalt plate (thickness: 0.1 mm) was sandwiched therebetween, 200 g of tungsten block P was placed on the upper cemented carbide chip A, and heated in a vacuum furnace. The shapes and dimensions of the cemented carbide chips A and B were 30 × 12.5 × 10 mm square, and the bonding side surface was polished to a surface roughness of 10 microns. The degree of vacuum during heating was 5 torr, the heating temperature was 1400 ° C., and the heating time was 60 minutes.

As a result, a laminated cemented carbide chip having a two-layer structure shown in FIG. 4 was obtained in which the upper and lower cemented carbide chips A and B were joined and integrated with an extremely thin bonding material S layer interposed therebetween. A structural photograph of this joint is shown in FIG. 3A is 100 times, and FIG. 3B is 1000 times. In addition, the hardness (HRA) at each measurement point in FIG. 4 of the obtained laminated carbide chip is 88.1 at the point a and 86.8 at the point b, and three points of the test piece cut out at the position of the broken line The folding force according to a bending test (a bonding layer exists in the center) was 3023 N / mm ² .

[Example 2] The same conditions as in Example 1 except that two types of carbide tips A and B similar to Example 1 were used and a nickel plate having a thickness of 0.1 mm was used as the bonding material S. A laminated carbide chip having a two-layer structure as shown in FIG. In this case, the hardness at point a (HRA) was 88.0, the hardness at point b was 87.0, and the bending strength was 2725 N / mm ² .

[Example 3] Two types of carbide tips A and B similar to those in Example 1 were used, and a high cobalt alloy (WC-20% Co) having a thickness of 2 mm was used as the bonding material S under the same conditions. A laminated carbide chip having a two-layer structure as shown in FIG. In this case, the hardness (HRA) at point a was 88.2, the hardness at point b was 86.9, and the bending strength was 2221 N / mm ² .

  [Example 4] As shown in FIG. 5, three types of carbide tips A, B, and C (all of which are WC-Co alloys) having different material types were made as prototypes, and their hardness and bending strength were measured. The manufacturing method of the cemented carbide chip is the same as that in each of the above embodiments. In this case, the composition of the cemented carbide chip was as follows: the cemented carbide chip A was WC-8% Co, B was WC-11% Co, C was WC-13% Co, and the bonding material S was pure cobalt. Regarding the hardness (HRA) of each part of the obtained laminated carbide chip, the point a in the carbide chip A is 88.0 (89.4 before bonding), and the point b in the chip B is 87.4 (before bonding). 87.8), and c in the chip C was 87.1 (86.7 before bonding).

Example 5 A laminated carbide chip having a three-layer structure as shown in FIG. 5 was produced in the same manner as described above. The material of each part was WC-13% Co for the carbide chip A, WC-8% Co for the chip B, and WC-13% Co for the chip C, and the bonding material was pure cobalt. The dimensions of each part in FIG. 5 were a height H of 36 mm (height of each chip h = 12 mm) and a width W of 20 mm. As for the hardness of each part of the obtained laminated carbide chip, the point a is 87.0 (86.7 before joining), the point b is 88.2 (89.4 before joining), and the point c is 86.7 ( The bending strength of the test pieces T1 and T2 cut out at the position of the broken line in FIG. 5 is T13 (the upper joint is located at the center), 2913 N / mm ² , and T2 ( The lower joint was located at the center) and was 3007 N / mm ² .

  As described above, the laminated cemented carbide chip according to the present invention can be compatible with different properties in one chip, and since it is joined and integrated by diffusion and penetration into the binder layer of the joining material, High bonding strength can be obtained. In the above description, an example of joining a plurality of different types of cemented carbide chips mainly of different materials has been described, but if necessary, the same kind of chips of the same composition can be joined and integrated in the same manner. By this joining, for example, it is possible to join small-sized chips to make a large-sized carbide chip, or to manufacture a cemented carbide chip having a complicated shape. Needless to say, the present invention can be effectively applied not only to a cutter bit chip but also to a cutting tool such as a cutting blade, a die, and the like.

  The laminated cemented carbide tip according to the present invention is capable of joining and integrating a cemented carbide tip excellent in wear resistance and a cemented carbide tip excellent in impact resistance with high strength. For example, a cutter for tunnel excavation It can be effectively used as a bit blade or the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an external view schematically showing the structure of a two-layer type (a) and three-layer type (b) laminated carbide chip according to the present invention. It is explanatory drawing of a manufacturing method. It is a microscope picture showing the structure of a joined part. It is a microscope picture showing the structure of a joined part. It is a figure showing a property measuring point. It is a figure showing a property measuring point.

Explanation of symbols

1 Stacked carbide tip A Carbide tip B Carbide tip S Bonding material

Claims (3)

Carbide chips consisting of the junction plane Migaku Ken the WC-Co cemented carbide, cobalt, in a state superimposed vertically sandwich the thin plate-like bonding material made of nickel or high-cobalt cemented carbide, non-oxidizing The cemented carbide chips are integrated with each other through the bonding material by heating to a temperature of 1300 to 1400 ° C. in a neutral atmosphere, causing a liquid phase in the bonding material to penetrate into the cemented carbide chip. A method for manufacturing a laminated carbide chip. The method for producing a laminated cemented carbide chip according to claim 1, wherein the heating is performed in a vacuum of 3 to 10 torr. A laminated carbide chip produced by the production method according to claim 1 or 2.

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