WO2016091061A1

WO2016091061A1 - Hard alloy composite molding method

Info

Publication number: WO2016091061A1
Application number: PCT/CN2015/095438
Authority: WO
Inventors: 徐跃华; 王玉鹏
Original assignee: 西迪技术股份有限公司
Priority date: 2014-12-11
Filing date: 2015-11-24
Publication date: 2016-06-16
Also published as: CN104532040B; CN104532040A

Abstract

A hard alloy composite molding method comprises: mixture preparation; design of a modular mold; primary extrusion molding; secondary extrusion molding; and vacuum sintering molding. The advantages of mold pressing, warm pressing and induction heating are combined, so that a part having a complex shape and cavity and an internal multi-pore and multi-runner combination can be molded in a near-net way as a whole once.

Description

Cemented carbide composite forming method

The present application claims priority to Chinese Patent Application No. 201410765048., entitled "Carbide-Metal-Plastic Forming Method", filed on Dec. 11, 2014, the entire contents of which is incorporated herein by reference. in.

Technical field

The invention relates to the technical field of material forming, in particular to a cemented carbide composite forming method.

Background technique

Generally, cemented carbide has excellent properties such as wear resistance, heat resistance, corrosion resistance, high hardness, good strength and toughness, especially its high hardness and wear resistance make cemented carbide materials not only used in tools and tools. But expand to more modern high-tech fields, such as petrochemical, offshore engineering, aerospace engineering, high-speed rail transit engineering and other key components of the industry. These key components are often complex in shape and cavity, and the internal structure is porous and multi-channel combination. However, cemented carbide has difficulty in forming and processing due to its inherent high hardness characteristics. How to solve such complex cavity shaped parts Near-net forming of solid carbide, which is the key research and urgent problem in the entire cemented carbide industry.

The conventional cemented carbide conventional forming methods mainly include compression molding, isostatic pressing, warm pressing, powder casting, MIN powder injection molding, etc. Various molding methods have their own characteristics and limitations, and according to the existing molding methods, It is difficult to solve the near net shape problem of complex cavity shaped parts.

Therefore, in view of the above deficiencies, the present invention provides a cemented carbide composite molding method.

Summary of the invention

(1) Technical problems to be solved

In view of the above, an object of the present invention is to provide a cemented carbide composite molding method, and the method provided by the present invention solves the problem that it is difficult to form a near-net shape of a component having a complicated shape cavity, an internal porous body, and a multi-channel combination.

(2) Technical plan

In order to solve the above technical problems, the present invention provides a cemented carbide composite molding method comprising the following steps:

S1, preparation of the mixture: mixing the binder, the molding agent, and the cemented carbide raw material particles having different particle sizes to form a mixture;

S2, combined mold design: according to the product shrinkage coefficient, the mold design tool is used to design the combined mold, the combined mold includes a lower flow channel mold, a concave cavity mold, a cavity disappearing mold and an upper cladding mold;

S3, one-time extrusion molding: injecting the mixture into the cavity of the lower flow channel mold and the inner cavity mold, and inductively heating the mixture from bottom to top to be extruded to form a bottom flow channel and a concave cavity;

S4, secondary extrusion molding: after cooling and decompressing the lower flow channel mold and the inner cavity mold, the cavity disappearing mold and the upper cladding mold are loaded, and the cavity is formed in the cavity formed by the cavity disappearing mold and the upper cladding mold. The mixture forms a mold body, and the mold body is subjected to secondary induction heating from bottom to top, and then extruded, and then cooled down to form a green body;

S5. Vacuum sintering molding: The blank in step S4 is placed in a vacuum pressure sintering furnace, passed through a protective atmosphere, and then pressure-sintered, and then cooled and cooled out.

Wherein, in step S1, the volume fraction of the cemented carbide raw material particles in the mixture is 82-88 parts, and the volume fraction of the binder in the mixture is 8-10 parts; the molding agent The parts by volume in the mixture are 4 to 8 parts.

Wherein, in step S1, the cemented carbide raw material particles are tungsten carbide cemented carbide particles, which include coarse particles, medium particles and fine particles, and the coarse particles, medium particles and fine particles are in the cemented carbide raw material particles. The parts by volume are 5 to 15 parts, 60 to 80 parts, and 15 to 25 parts, respectively; the binder is cobalt.

Wherein the molding agent comprises high density polyethylene, low temperature wax, polyethylene glycol, high temperature wax and acid, the volume of the high density polyethylene, low temperature wax, polyethylene glycol, high temperature wax and acid in the mixture The number of parts is 1 to 1.4 parts, 1.5 to 2 parts, 1.2 to 1.8 parts, 0.6 to 1 part, and 0.05 to 0.1 parts, respectively.

Wherein, step S6 between steps S1 and S2 is further included,

S6, smelting and crushing of the mixture: the mixture is heated to a viscous state, crushed, and then crushed.

Wherein, step S7 between steps S4 and S5 is further included,

S7. Removal of molding agent: The green body obtained in step S4 is subjected to degumming and degreasing treatment.

Wherein, the step S7 includes steps S71 and S72,

S71, low temperature degumming: the green body is immersed in gasoline for a certain period of time;

S72, high temperature degreasing: the body of the gasoline soaked in step S71 is placed in a vacuum degreasing furnace to be heated to melt the cavity lost mold and remove the molding agent.

In the step S71, the green body is immersed in gasoline at 70 to 90 ° C for 25 to 30 hours.

Wherein, in step S72, the vacuum degreasing furnace is first heated to above 400 ° C for heat preservation, so that the mold disappears, the mold disappears, and then the heating is continued to 800 ° C or more, and finally the temperature is lowered to achieve complete removal of the remaining molding agent in the body.

The green body in step S4 is heated to 1380 ° C to 1420 ° C in a vacuum pressure sintering furnace, and the protective atmosphere is hydrogen gas.

(3) Beneficial effects

In the cemented carbide composite molding method provided by the invention, by combining the components of the mixture, the bonding strength, the bending strength and the molding temperature point of the processed product can be improved, and the design is suitable for one-time extrusion molding and secondary Special lower flow channel mold, inner cavity mold, cavity disappearing mold and upper cladding mold required for extrusion molding, combined with induction heating and extrusion from bottom to top of the mixture, thereby integrating molding and warm pressing And the advantages of induction heating, the shape cavity is complex, the internal porous and the multi-flow channel combination parts can be integrally cleaned at one time, the subsequent machining allowance is small, the processing cost is low, especially the cavity disappearing mold is greatly facilitated. The molding of complex cavities. The experimental results show that the product prepared by the cemented carbide composite molding method has the density (g/cm ³ ) of 14.51, the hardness (HRA) of 89.1, the transverse rupture strength of (N/mm ² ) 2890, and the coercive force. (kA/m) 12.1, cobalt magnetic (Com%) 9.51; through the metallographic diagram, it can be found that the product density is uniform, the surface is smooth, the structure is dense, and there are no defects such as pores, bubbles and cracks.

DRAWINGS

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only It is an embodiment of the present invention, and those skilled in the art can obtain other drawings according to the provided drawings without any creative work.

1 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of the embodiment of the present invention under a microscope of 100 times;

2 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of the embodiment of the present invention under a microscope of 1500 times;

3 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of Example 4 of the present invention under a microscope of 100 times;

4 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of Example 4 of the present invention under a microscope of 1500 times;

Figure 5 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of Example 5 of the present invention under a microscope of 100 times;

6 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of Example 5 of the present invention under a 1500-fold microscope;

Figure 7 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of Example 6 of the present invention under a microscope of 100 times;

Figure 8 is a metallographic diagram of a product obtained by the method of synthesizing cemented carbide of Example 6 of the present invention under a microscope of 1500 times.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described below. It is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts are within the scope of the present invention.

Example 1

The cemented carbide composite molding method provided by the invention comprises the following steps:

S5. Vacuum sintering molding: The blank formed in step S4 is placed in a vacuum pressure sintering furnace, passed through a protective atmosphere, and then pressure-sintered, and then cooled and cooled out.

In the above embodiment 1, the mixture is mixed with cemented carbide raw materials of different sizes to improve the bonding strength of the processed product, the binder can be used to improve the bending strength of the processed product, and the molding agent is used to ensure the molding temperature point of the product; Design special lower flow channel molds, inner cavity molds, cavity disappearance molds and upper cladding molds for one-shot extrusion and secondary extrusion molding, and simultaneously inductively heat the mixture from bottom to top. And extrusion, which combines the advantages of molding, warming and induction heating, so that the parts with complex shape, internal porous and multi-flow channel can be integrally formed in one time.

Specifically, in step S1, the volume fraction of the cemented carbide raw material particles in the mixture is 82-88 parts, and the volume fraction of the binder in the mixture is 8-10 parts; The volume fraction of the agent in the mixture is 4 to 8 parts. Preferably, the volume fraction of the cemented carbide raw material particles, the binder and the molding agent in the mixture are 82 parts, 10 parts and 8 parts, respectively, or the volume fraction of the three in the mixture is 88 respectively. Parts, 8 parts and 4 parts, of course, the volume fraction of the three in the mixture may also preferably be 85 parts, 9 parts and 6 parts, respectively.

Specifically, the cemented carbide raw material particles are tungsten carbide cemented carbide particles, and the cemented carbide raw material particles include coarse particles, medium particles and fine particles. In the present invention, the coarse particles preferably have a particle diameter of 4 to 4 6 μm; the particle diameter of the medium particles is preferably 2 to 2.5 μm; the particle diameter of the fine particles is preferably 0.8 to 1.0 μm; the volume fraction of the coarse particles, medium particles and fine particles in the cemented carbide raw material particles The number is 5-15 parts, 60-80 parts and 15-25 parts respectively, so that the coarse and fine grain mixing not only improves the bonding strength of the cemented carbide parts, but also improves the fluidity of the mixture injection and the solid density of the filling. Preferably, the volume fraction of the coarse particles, medium particles and fine particles in the cemented carbide raw material particles may be 5 parts, 80 parts and 25 parts, respectively, or the volume fraction of the three in the cemented carbide raw material particles. The number is 15 parts, 60 parts, and 15 parts, respectively. Of course, the volume fraction of the three in the cemented carbide raw material particles may also be preferably 10 parts, 70 parts, and 20 parts, respectively.

Specifically, the binder is cobalt, and the magnetic force and bending strength of the product after molding are ensured; the molding agent includes high density polyethylene, low temperature wax, polyethylene glycol, high temperature wax and acid; the high density polyethylene, low temperature wax The volume fraction of polyethylene glycol, high temperature wax and acid in the mixture is 1 to 1.4 parts, 1.5 to 2 parts, 1.2 to 1.8 parts, 0.6 to 1 part and 0.05 to 0.1 parts, respectively, to ensure the molding temperature point. The molding agent and the raw material can be uniformly mixed without being infiltrated, and the molding agent is easily taken out; preferably, the volume fraction of the high density polyethylene, the low temperature wax, the polyethylene glycol, the high temperature wax and the acid in the mixture can be respectively 1 part, 2 parts, 1.8 parts, 1 part and 0.1 part, or the parts of the high density polyethylene, low temperature wax, polyethylene glycol, high temperature wax and acid in the mixture may be 1.4 parts, 1.5, respectively. Parts, 1.2 parts, 0.6 parts and 0.05 parts, of course, the volume fraction of the high density polyethylene, low temperature wax, polyethylene glycol, high temperature wax and acid in the mixture may preferably be 1.2 parts, 1.7 parts, 1.6, respectively. Parts, 0.8 parts and 0.08 parts.

Of course, other conventional types of molding agents may be added to the above molding agent; the hard alloy used may be other than the tungsten carbide, and other binders may be used, and the binder is not limited to cobalt; The volume fraction of each component in the above mixture is preferably a volume percentage.

Example 2

Preferably, the above embodiment 1 of the present invention may further comprise the step S6 between the steps S1 and S2, the smelting and crushing of the mixture: crushing the mixture into a viscous shape, crushing, and then breaking Broken, specifically, the mixture is heated in stages, the heating temperature is 120 ° C ~ 160 ° C, the mixture is heated to become viscous, the viscous mixture is compacted to a thickness of 0.15 ~ 0.2 mm, repeated 2 to 4 times, and then broken. This can eliminate the bubbles caused by the expansion of the forming agent during mixing, improve the solid density of the mixture, ensure a more uniform subsequent injection of the mixture, and make the filling more dense and firm.

Specifically, in the above Embodiment 1, in step S2, the three-dimensional software is used to perform the combined mold design, and the design scheme and the optimal mold positioning of the optimal parting surface and the pouring port are found through the analog analysis and the finite element analysis. According to the scheme, the optimum volume ratio of the mold (the shrinkage coefficient of the product) is 1:1.19, which means that the volume of the mold is 1.19 times the volume of the final product after sintering shrinkage. The cavity is made of imported high-strength cavity-disappearing mold to meet the needs of the secondary composite extrusion-coated cavity.

Specifically, in the above embodiment 1, in step S3, the dried mixture is filled into the cavity through the uniformly distributed pouring port, and the whole mold is heated by induction heating to 150 to 170 ° C, and the molding agent in the mixture is molten. The filling density of the mixture can be increased, and the pressure of 15Pa is used to form the bottom flow channel and the concave cavity. Among them, the induction heating adopts a bottom-up manner, which can conveniently discharge the pores in the mixture, so that the final product is more dense.

Specifically, in the above-mentioned Embodiment 1, in step S4, after one extrusion molding, the mold temperature is cooled to 80 to 100 ° C, and then decompressed, and the cavity disappearing mold and the upper cladding mold are loaded, and after the mixture is injected again, the mold body is molded. After two times of induction heating 150-170 ° C, with a molding pressure of 20 Pa, the second extrusion molding the upper cover and the cavity, the secondary composite extrusion needs to be cooled and cooled to form a blank body, this During the process, the inner cavity needs high-strength cavity to disappear from the mold support, and the complex cavity is formed. Among them, the induction heating also adopts the bottom-up mode to facilitate the discharge of the pores in the mixture.

Example 3

Preferably, the foregoing Embodiment 1 or Embodiment 2 of the present invention further includes Step S7 between Steps S4 and S5,

S7, the removal of the molding agent: the green body obtained in step S4 is degummed and degreased to take off The mold is removed from the body and the cavity in the body disappears.

Specifically, the step S7 includes steps S71 and S72,

S71, low temperature degumming: take 70~90 °C gasoline soaking the body, soaking time 28 hours, of course, the soaking time can be between 25 hours and 30 hours, this low temperature soaking method can remove 2% of the total amount of molding agent~ 2.5%;

S72, high temperature degreasing: the body soaked in gasoline is placed in a vacuum degreasing furnace, the first interval is heated to above 400 °C, and the temperature is kept for 15 minutes. At this time, the inner cavity disappears and the mold melts, and the temperature is further increased to 800 ° C for 10 minutes. After the temperature is lowered, the remaining forming agent in the product form is completely removed.

Preferably, in step S5, the green body is heated to 1380 ° C to 1420 ° C in a vacuum pressure sintering furnace, and the protective atmosphere is preferably hydrogen gas, although other protective atmospheres may of course be used.

By testing the products obtained in the above examples, the following test results were obtained: product density (g/cm ³ ) 14.51, hardness (HRA) 89.1, transverse rupture strength (N/mm ² ) 2890, coercive force (kA/) m) 12.1, cobalt magnet (Com%) 9.51, the results of these tests show that the obtained product has excellent indicators. 1 and FIG. 2, FIG. 1 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of the embodiment of the present invention under a 100-fold microscope; FIG. 2 is a cemented carbide composite molding method using the embodiment of the present invention. Obtain the metallographic diagram of the product under a microscope of 1500 times; observe the porosity of the product under the microscope of 100 times as A02, B00, 1500 times the average grain size of the product under the microscope is 2.0, the product density can be found to be uniform, the surface is smooth, and the tissue Dense, free of defects such as voids, bubbles and cracks.

Example 4

Preparation of S1 mixture:

10 parts by volume of cobalt, 10 parts by volume of a molding agent, and 82 parts by volume of tungsten carbide cemented carbide particles having different particle sizes are mixed to form a mixture comprising 1 part by volume of high density polyethylene and 2 parts by volume of low temperature. Wax, 1.8 parts by volume of polyethylene glycol, 1 part by volume of high temperature wax and 0.1 part by volume of acid; the tungsten carbide cemented carbide particles comprise 5 parts of tungsten carbide (coarse particles) having a particle diameter of 5.0 μm, and 80 parts of particle diameter 2.0 μm of tungsten carbide (medium particles) and 25 parts of tungsten carbide (fine particles) having a particle diameter of 1.0 μm;

S2, combined mold design: According to the product shrinkage coefficient, the three-dimensional software is used to design the combined mold. The combined mold includes the lower flow channel mold, the inner cavity mold, the cavity disappearing mold and the upper cladding mold, through the analog analysis and limited Meta-analysis, find out the optimal parting surface and pouring port design scheme and the optimal mold clamping positioning scheme, and the shrinkage coefficient of the product designed according to the mixture ratio is 1:1.19;

S3, one-time extrusion molding: the mixture described in the above step S1 is injected into the cavity of the lower flow channel mold and the inner cavity mold through the uniformly distributed pouring port, and the mixture is heated by induction heating from bottom to top to 150 ° C. After °C, it is pressed at a pressure of 15 Pa to form a bottom flow path and a concave cavity;

S4, secondary extrusion molding: the lower flow channel mold and the inner cavity mold are cooled to 80-100 ° C and then decompressed, and the cavity disappearing mold and the upper cladding mold are loaded, and the cavity disappearing mold and the upper cladding mold are formed. The mold cavity is re-injected into the mold cavity to form a mold body, and the mold body is heated by the second induction heating from bottom to top to 170 ° C, and then extruded at a molding pressure of 20 Pa, and then the mold body is cooled and cooled to form a green body;

S5. Vacuum sintering molding: The green body formed in the step S4 is placed in a vacuum pressure sintering furnace, hydrogen gas is introduced, and then pressure-sintered to 1380 ° C to 1420 ° C, and then cooled and cooled out.

By detecting the product obtained in the above Example 4, the following test results were obtained: product density (g/cm ³ ) was 14.35, hardness (HRA) was 89.0, and transverse rupture strength (N/mm ² ) was 3,300. The test results show that the obtained product has excellent indicators. 3 and FIG. 4, FIG. 3 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of the fourth embodiment of the present invention under a microscope of 100 times; FIG. 4 is a composite of cemented carbide of the fourth embodiment of the present invention. The metallographic diagram of the product obtained by the molding method under a microscope of 1500 times; the porosity of the product observed under a microscope of 100 times is A02, B00, and the average grain size of the product under the microscope of 1500 times is 2.0, and the product density can be found to be uniform and the surface is smooth. , dense structure, no porosity, bubbles and cracks and other defects.

Example 5

Preparation of S1 mixture:

8 parts by volume of cobalt, 4 parts by volume of molding agent, 88 parts by volume of carbon having different particle sizes The tungsten carbide cement particles are mixed to form a mixture, and the molding agent comprises 1.4 parts by volume of high density polyethylene, 1.5 parts by volume of low temperature wax, 1.2 parts by volume of polyethylene glycol, 0.6 parts by volume of high temperature wax, and 0.05 parts by volume of acid; The tungsten carbide cemented carbide particles include 15 parts of tungsten carbide (coarse particles) having a particle diameter of 5.0 μm, 60 parts of tungsten carbide (medium particles) having a particle diameter of 2.0 μm, and 15 parts of tungsten carbide having a particle diameter of 1.0 μm (fine Granule)

S6, smelting and crushing of the mixture

The mixture prepared in the step S1 is heated to a viscous state at a temperature of 120 ° C to 160 ° C, and the viscous mixture is rolled to a thickness of 0.15 to 0.2 mm, repeated 2 to 4 times, and then crushed to obtain a broken. Mixture

S3, one-time extrusion molding: the mixture described in the above step S1 is injected into the cavity of the lower flow channel mold and the inner cavity mold through the uniformly distributed pouring port, and the mixture is heated by induction heating from bottom to top to 170 ° C. Thereafter, pressing at a pressure of 15 Pa to form a bottom flow path and a concave cavity;

S4, secondary extrusion molding: the lower flow channel mold and the inner cavity mold are cooled to 80-100 ° C and then decompressed, and the cavity disappearing mold and the upper cladding mold are loaded, and the cavity disappearing mold and the upper cladding mold are formed. The mold cavity is injected into the mold cavity again to form a mold body, and the mold body is heated by the second induction heating from bottom to top to 150 ° C, and then extruded at a molding pressure of 20 Pa, and then the mold body is cooled and cooled to form a green body;

S5. Vacuum sintering molding: The green body formed in the step S4 is placed in a vacuum pressure sintering furnace, and hydrogen gas is introduced into the furnace to be pressurized and sintered to 1400 ° C, then cooled and cooled out, and then cooled and discharged.

By testing the product obtained in the above Example 5, the following test results were obtained: product density (g/cm ³ ) was 14.21, hardness (HRA) was 89.6, and transverse rupture strength (N/mm ² ) was 3,400. The test results show that the obtained product has excellent indicators. 5 and FIG. 6, FIG. 5 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of the fifth embodiment of the present invention under a microscope of 100 times; FIG. 6 is a cemented carbide composite of the fifth embodiment of the present invention. The metallographic diagram of the product obtained by the molding method under a microscope of 1500 times; the porosity of the product observed under a microscope of 100 times is A02, B00, and the average grain size of the product under the microscope of 1500 times is 2.0, and the product density can be found to be uniform and the surface is smooth. , dense structure, no porosity, bubbles and cracks and other defects.

Example 6

Preparation of S1 mixture:

9 parts by volume of cobalt, 6 parts by volume of a molding agent, and 85 parts by volume of tungsten carbide cemented carbide particles having different particle sizes were mixed to form a mixture including 1.2 parts by volume of high density polyethylene and 1.7 parts by volume of low temperature. Wax, 1.6 parts by volume of polyethylene glycol, 0.8 parts by volume of high temperature wax and 0.08 parts by volume of acid; the tungsten carbide cemented carbide particles include 10 parts of tungsten carbide (coarse particles) having a particle diameter of 5.0 μm, and 70 parts of particle diameter 2.0 μm of tungsten carbide (medium particles) and 20 parts of tungsten carbide (fine particles) having a particle diameter of 1.0 μm;

S6, smelting and crushing of the mixture

S3, one-time extrusion molding: the mixture described in the above step S1 is injected into the cavity of the lower flow channel mold and the inner cavity mold through the uniformly distributed pouring port, and the mixture is heated by induction heating from bottom to top to 160 ° C. Thereafter, pressing at a pressure of 15 Pa to form a bottom flow path and a concave cavity;

S4, secondary extrusion molding: cooling the lower flow channel mold and the inner cavity mold to 80-100 ° C After decompression, the cavity disappears into the mold and the upper cladding mold, and the mixture is injected into the cavity formed by the cavity disappearing mold and the upper cladding mold to form a mold body, and the mold body is heated by secondary induction heating from bottom to top. After being heated to 160 ° C, it is extruded at a molding pressure of 20 Pa, and then the mold body is cooled and cooled to release the mold to form a green body;

S7, molding agent removal:

S71, low temperature degumming: the green body is immersed in 90 ° C gasoline for 25 hours;

S72, high temperature degreasing: the body of the gasoline soaked in step S71 is placed in a vacuum degreasing furnace preheated to 400 ° C to heat the cavity to disappear, then continue to heat to 800 ° C to keep warm, and finally cool to reach the billet The remaining molding agent in the body is completely removed;

S5, vacuum sintering molding: the blank formed in step S4 is placed in a vacuum pressure sintering furnace, hydrogen is introduced, and then pressure-sintered to 1420 ° C, and then cooled and cooled, and then cooled and discharged.

By testing the product obtained in the above Example 6, the following test results were obtained: product density (g/cm ³ ) was 14.10, hardness (HRA) was 89.2, and transverse rupture strength (N/mm ² ) was 3100. The test results show that the obtained product has excellent indicators. 7 and FIG. 8, FIG. 7 is a metallographic diagram of a product obtained by the cemented carbide composite molding method of Example 6 of the present invention under a microscope of 100 times; FIG. 8 is a composite of cemented carbide of Example 6 of the present invention. The metallographic diagram of the product obtained by the molding method under a microscope of 1500 times; the porosity of the product observed under a microscope of 100 times is A02, B00, and the average grain size of the product under the microscope of 1500 times is 2.0, and the product density can be found to be uniform and the surface is smooth. , dense structure, no porosity, bubbles and cracks and other defects.

It can be seen from the above embodiments that in the cemented carbide composite molding method provided by the present invention, by combining the components of the mixture, the bonding strength, the bending strength and the molding temperature point of the processed product can be improved, and the design is suitable for once. The special lower flow path mold, the inner cavity mold, the cavity disappearing mold and the upper cladding mold required for extrusion molding and secondary extrusion molding, and simultaneously inductively heating and squeezing the mixture from bottom to top, thereby Combining the advantages of molding, warm pressing and induction heating, the components with complex shape, internal porous and multi-channel combination can be integrally formed in one time, with small processing margin and low processing cost, especially adopting type. The cavity disappearing mold greatly facilitates the molding of the complex cavity; the smelting and crushing of the mixture eliminates the bubbles caused by the expansion of the forming agent during mixing, improves the solid density of the mixture, and combines the green body Degumming and degreasing treatment and sintering under vacuum protective atmosphere can make the sintered parts have uniform density, smooth surface and compact structure. No voids, bubbles and cracks appear, and the product quality is high. The experimental results show that the product prepared by the cemented carbide composite molding method has the density (g/cm ³ ) of 14.51, the hardness (HRA) of 89.1, the transverse rupture strength of (N/mm ² ) 2890, and the coercive force. (kA/m) 12.1, cobalt magnetic (Com%) 9.51; through the metallographic diagram, it can be found that the product density is uniform, the surface is smooth, the structure is dense, and there are no defects such as pores, bubbles and cracks.

The above description of the embodiments is merely to assist in understanding the method of the present invention and its core idea. It should be noted that those skilled in the art can make various modifications and changes to the present invention without departing from the spirit and scope of the invention. The above description of the disclosed embodiments will enable those skilled in the art to make or use the invention, and various modifications of these embodiments will be apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein.

Claims

A cemented carbide composite forming method comprising the following steps:

S1, preparation of the mixture: mixing the binder, the molding agent, and the cemented carbide raw material particles having different particle sizes to form a mixture;

S2, combined mold design: according to the product shrinkage coefficient, the mold design tool is used to design the combined mold, the combined mold includes a lower flow channel mold, a concave cavity mold, a cavity disappearing mold and an upper cladding mold;

S3, one-time extrusion molding: injecting the mixture into the cavity of the lower flow channel mold and the inner cavity mold, and inductively heating the mixture from bottom to top to be extruded to form a bottom flow channel and a concave cavity;

S4, secondary extrusion molding: after cooling and decompressing the lower flow channel mold and the inner cavity mold, the cavity disappearing mold and the upper cladding mold are loaded, and the cavity is formed in the cavity formed by the cavity disappearing mold and the upper cladding mold. The mixture forms a mold body, and the mold body is subjected to secondary induction heating from bottom to top, and then extruded, and then cooled down to form a green body;

S5. Vacuum sintering molding: The blank in step S4 is placed in a vacuum pressure sintering furnace, passed through a protective atmosphere, and then pressure-sintered, and then cooled and cooled out.
The cemented carbide composite molding method according to claim 1, wherein in the step S1, the volume fraction of the cemented carbide raw material particles in the mixture is 82 to 88 parts, and the binder The parts by volume in the mixture are 8 to 10 parts; the volume fraction of the molding agent in the mixture is 4 to 8 parts.
The cemented carbide composite molding method according to claim 2, wherein in the step S1, the cemented carbide raw material particles are selected from the group consisting of tungsten carbide cemented carbide particles, and the cemented carbide raw material particles include coarse particles and medium. Particles and fine particles, the coarse particles, medium particles and fine particles in the cemented carbide raw material particles are respectively 5 to 15 parts, 60 to 80 parts, and 15 to 25 parts by volume; the binder is cobalt .
The cemented carbide composite molding method according to claim 3, wherein the molding agent comprises high density polyethylene, low temperature wax, polyethylene glycol, high temperature wax and acid, the high density polyethylene, low temperature wax The volume fraction of polyethylene glycol, high temperature wax and acid in the mixture is 1 to 1.4 parts, 1.5 to 2 parts, 1.2 to 1.8 parts, 0.6 to 1 part, and 0.05 to 0.1 parts.
The cemented carbide composite molding method according to claim 1, further comprising a step S6 between S1 and S2,

S6, smelting and crushing of the mixture: the mixture is heated to a viscous state, crushed, and then crushed.
The cemented carbide composite molding method according to claim 1, further comprising a step S7 between the steps S4 and S5,

S7. Removal of molding agent: The green body obtained in step S4 is subjected to degumming and degreasing treatment.
The cemented carbide composite molding method according to claim 6, wherein the step S7 comprises steps S71 and S72,

S71, low temperature degumming: the green body is immersed in gasoline;

S72, high temperature degreasing: the body of the gasoline soaked in step S71 is placed in a vacuum degreasing furnace to be heated to melt the cavity lost mold and remove the molding agent.
The cemented carbide composite molding method according to claim 1, wherein the green body is immersed in gasoline at 70 to 90 ° C for 25 to 30 hours in step S71.
The cemented carbide composite molding method according to claim 1, wherein in step S72, the vacuum degreasing furnace is first heated to a temperature above 400 ° C for heat preservation, and then further heated to 800 ° C or higher to be kept warm, and finally cooled to achieve the remaining in the body. The molding agent is completely removed.
The cemented carbide composite molding method according to claim 1, wherein the green body in the step S5 is heated to 1380 ° C to 1420 ° C in a vacuum pressure sintering furnace, and the protective atmosphere is hydrogen gas.