Preparation process of diamond wire-drawing die

Abstract

The invention belongs to the technical field of metal material forming and manufacturing, and particularly relates to a preparation process of a diamond wire-drawing die. The preparation process of the diamond wire-drawing die comprises the steps of powder preparation, base powder pre-pressing, diamond inlaying, flour pre-pressing, sintering and the like. By improving the powder raw material ratio and the preparation process, the strength after sintering is obviously enhanced compared with that in the prior art, the hardness HRC of the powder can reach 65-70, and the binding force, wrapping force and the like of the powder are remarkably improved, so that the impact resistance of a metal wire drawing die manufactured from the powder is enhanced, and the service life of the metal wire drawing die is prolonged. Cracking and bursting caused by insufficient strength of a sintered filler mixture and the like of the metal wire drawing die in the hard wire drawing process can be effectively avoided, the service life of the metal wire drawing die is greatly prolonged, meanwhile, the sintering speed is effectively increased, and the yield is increased.

Description

Technical Field

[0001] This invention belongs to the field of metal material forming and manufacturing technology, and specifically relates to a diamond wire drawing die preparation process. Background Technology

[0002] In the field of wire drawing, the requirements for the strength and surface roughness of drawn wires are becoming increasingly stringent. Polycrystalline diamond dies are gradually failing to meet the needs of high-end customers regarding die life and wire surface condition. Furthermore, natural diamonds suffer from limitations such as scarcity, high price, inconsistent quality, and difficulty in processing. Single-crystal diamonds, with properties similar to natural diamonds, are gradually replacing natural diamonds as the primary material for metal wire drawing die manufacturing due to their advantages in quality consistency and price.

[0003] However, single-crystal diamond is inherently brittle and anisotropic, making it prone to fracture under the high stress of wire drawing. Therefore, it is typically embedded in a high-strength metal collar to apply prestress and improve its fracture resistance. Traditional inserting processes often employ mechanical cold pressing or low-temperature brazing, which suffers from low bonding strength, thermal conductivity mismatch, and susceptibility to microcracks, leading to premature die failure during high-speed, high-load hard wire drawing.

[0004] Powder metallurgy insert sintering process is an improved method, but the following problems are common in the existing technology: 1) The powder formula is unreasonable, resulting in insufficient bonding force with diamond, or the thermal expansion coefficient is mismatched, causing excessive internal stress; 2) The sintering process is rough, which can easily lead to diamond graphitization or non-dense binder, affecting the overall performance and service life of the mold.

[0005] Based on this, the present invention provides a diamond wire drawing die manufacturing process to improve its mechanical properties and increase its service life. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a single-crystal diamond wire drawing die insert sintering preparation process with high bonding strength, reasonable stress distribution, and long service life.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A process for preparing a diamond wire drawing die, wherein the diamond wire drawing die undergoes pressing, sintering and other steps during the preparation process, and the wire drawing die insert used in the pressing process includes components such as a die cover and a die shell.

[0008] The mold shell has a central groove. The opening at the top of the central groove is the outlet end of the top of the mold shell, and the bottom of the central groove has an inlet end, which is the inlet end of the bottom of the mold shell. During use, the mold shell is first placed on the workbench with the inlet end facing down and the outlet end facing up. After the inlet end is sealed, the following preparation process is carried out.

[0009] Specifically, the preparation process includes the following steps: 1) Powder preparation: Mix and combine nickel, iron, aluminum, chromium, tungsten, titanium, and silicon powders in a certain ratio to obtain mixed powder; 2) Pre-pressed base powder: The mixed powder from step 1) is evenly filled into the mold shell and pre-pressed under a certain pressure to obtain base powder I; 3) Diamond setting: The single-crystal diamond is fixed in the middle of the base powder I with adhesive; 4) Pre-pressed flour: The mixed powder from step 1) is evenly filled into the mold shell. At this time, the mixed powder added in step 4) covers the upper surface of the base powder I, single crystal diamond and binder. The mold cover is placed in and pre-pressed with a certain pressure to obtain flour I and diamond mold core. The base powder I, diamond mold core and flour I constitute the mold blank. 5) Sintering: The mold blank is placed in a hot press sintering machine for sintering. After sintering, the diamond wire drawing mold is obtained.

[0010] Specifically, in step 1), the mass percentage of each powder raw material is as follows: nickel 40-50%, iron 5-15%, aluminum 5-10%, chromium 5-10%, tungsten 3-15%, titanium 25-40%, and silicon 1-2%.

[0011] Specifically, in step 2), the mixed powder from step 1) is evenly filled into the central groove of the mold shell, and a pressure head is inserted into the central groove from top to bottom to perform pre-compression under a certain pressure.

[0012] Specifically, in step 2), the amount of mixed powder used is 0.1-0.5g.

[0013] Specifically, in step 2), the pressure is 10-20 MPa and the pre-compression time is 3-5 seconds.

[0014] Specifically, in step 3), the adhesive is epoxy resin glue.

[0015] Specifically, in step 3), the single-crystal diamond involved in this invention is a standard specification product, such as a single-crystal diamond with a thickness of 0.4mm to 2mm, and the epoxy resin adhesive is a liquid.

[0016] Specifically, in step 4), the amount of mixed powder used is 0.8-1.2g.

[0017] Specifically, in step 4), the pressure is 5-10 MPa and the pre-compression time is 3-5 seconds.

[0018] Specifically, in step 4), after pressing, the distance from the bottom of the diamond mold core to the bottom entrance of the mold shell is H1; after pressing, the distance from the top of the diamond mold core to the top exit of the mold shell is H2, and H2 is greater than H1.

[0019] Specifically, the sintering process in step 5) is as follows: First stage: heat from room temperature to 600-750℃ at a rate of 60-80℃ / min, and apply an axial pressure of 20-40 MPa, holding for 5-15 min; Second stage: heat to 800-900℃ at a rate of 80-100℃ / min, and after reaching the sintering temperature, increase the axial pressure to 60-100 MPa, holding for 1-3 min; Third stage: adjust the sintering temperature to 750-900℃, and cycle the axial pressure between 50-100 MPa for 6-8 cycles; Fourth stage: cool with the furnace, and when the temperature drops below 500℃, release all pressure and continue cooling to room temperature.

[0020] Furthermore, the present invention also provides a diamond wire drawing die prepared by the above method.

[0021] The diamond wire drawing die of the present invention is mainly used for drawing high carbon steel wire, tungsten wire, stainless steel wire, alloy wire, bonding wire and other wires.

[0022] This invention employs a multi-component composite system of tungsten-nickel-iron-aluminum-titanium-chromium-silicon, achieving a hardness of HRC65 or higher. Tungsten forms a high-melting-point framework, providing high-temperature strength and a thermal expansion coefficient close to that of diamond. Nickel and iron act as the main binder phases, activating sintering and promoting densification. Aluminum and titanium preferentially react with the diamond surface during sintering, forming a carbide transition layer that significantly improves the interfacial bonding strength between the metal binder and diamond. Chromium and silicon form a stable, dispersed oxide distribution during sintering, enhancing the binder's oxidation resistance and high-temperature stability.

[0023] This invention employs a fully encapsulated + asymmetric prestressed structure, with the entire mold core coated in powder, ensuring sufficient encapsulation force. Simultaneously, the mold core's inlet end is designed to be shallower than its outlet end, so that after sintering, the inlet end (the area bearing the greatest tensile stress and wear) is enveloped by a stronger compressive stress zone. This structure more effectively counteracts working stress, significantly improving the mold core's resistance to breakage and extending mold life. It also effectively increases sintering speed and improves yield.

[0024] This invention employs a sintering process of "gradient heating and pressurization + oscillating heat and pressure holding," which shortens the sintering time by 30% and increases the yield to over 95%. Gradient heating and pressurization ensures the stable volatilization of organic matter in the powder and homogenization of the composition, avoiding powder spraying or deformation caused by rapid heating and pressurization. It also effectively inhibits diamond graphitization, controls grain growth, and obtains a uniform, fine-grained structure. The micro-relative motion between particles generated by oscillating heat and pressure holding disrupts the oxide film on the powder particle surface, enhances plastic deformation capacity, increases the densification rate, and facilitates pore closure and gas expulsion, reducing residual porosity.

[0025] Compared with the prior art, the advantages of the present invention are: This invention improves the powder raw material ratio and preparation process, resulting in a significantly enhanced strength after sintering compared to existing technologies. The hardness reaches HRC 65-70, and the powder's bonding and encapsulation forces are significantly improved. This strengthens the impact resistance of the metal wire drawing die, effectively preventing cracking and bursting caused by insufficient strength of the sintered filler mixture during the drawing of hard wires. This greatly increases the service life of the metal wire drawing die, saving production costs for wire manufacturers and improving product quality. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of the present invention before sintering; Wherein, 1 is the mold cover, 2 is the mold shell, 3 is the sintered flour, 4 is the diamond mold core, and 5 is the sintered base powder, with 3 and 5 using the same powder; H1 is the distance from the lower end face of the mold core to the inlet end face of the mold shell, and H2 is the distance from the upper end face of the mold core to the outlet end face of the mold shell. Detailed Implementation

[0027] The technical solutions of this application will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0028] The structures, proportions, and sizes illustrated in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art in understanding and reading the invention. They are not intended to limit the scope of the invention and therefore have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effectiveness and purpose of the invention, should still fall within the scope of the technical content disclosed herein. Furthermore, the terms "upper," "lower," "left," "right," "middle," and "one" used in this specification are merely for clarity and not intended to limit the scope of the invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention.

[0029] The process methods not specifically described in the following embodiments all adopt conventional technical means in the prior art.

[0030] In the following examples, room temperature or normal temperature refers to 25±5℃.

[0031] The purity of the following examples is: nickel 99.99%, iron 99.99%, chromium 99.99%, aluminum 99.8%, tungsten 99.99%, titanium 99%, and silicon 99.99%, with a particle size of 10-50 μm.

[0032] Example 1 Example 1 provides a sintering process for preparing single-crystal diamond wire drawing die inserts. The preparation process includes pressing and sintering steps. The process is implemented according to... Figure 1 The structure shown is pressed before sintering. The wire drawing die insert used in the pressing process includes components such as die cover 1 and die shell 2. Specifically, the wire drawing die insert and the press head used in the following embodiments are conventional equipment in the prior art. Their structure is not the inventive point of this invention, so it will not be described in detail. like Figure 1 As shown, the mold shell 2 has a central groove inside. The groove opening at the top of the central groove is the outlet end of the top of the mold shell 2. The bottom of the central groove has an inlet, which is the inlet end of the bottom of the mold shell 2. During use, the mold shell 2 is first placed on the workbench with the inlet end facing down and the outlet end facing up. After the inlet end is sealed, the following preparation process is carried out. The preparation process includes the following specific steps: 1) Powder preparation: Mix and blend the various powder raw materials according to a certain ratio to obtain a mixed powder; wherein, the mass percentage of each powder raw material is: nickel 40%, iron 9%, aluminum 8%, chromium 8%, tungsten 5%, titanium 30%, and silicon 1%; 2) Pre-pressing the base powder: Evenly fill 0.2g of the mixed powder from step 1) into the central groove of the mold shell 2, and use a press head to extend from top to bottom into the central groove, pre-pressing for 3-5 seconds under a pressure of 10MPa to obtain base powder I (i.e., Figure 1 Medium sintered base powder 5); 3) Diamond setting: The single crystal diamond is fixed in the middle of the base powder I with epoxy resin adhesive. The single crystal diamond involved in this invention is a standard specification product, such as a single crystal diamond with a thickness of 0.4mm to 2mm. The epoxy resin adhesive is liquid, and one drop is added when using it, about 0.04mL to 0.1mL. 4) Pre-pressed flour: Evenly fill 1g of the mixed powder from step 1) into mold shell 2. At this time, the mixed powder added in step 4) covers the upper surface of base powder I, single crystal diamond, and binder (epoxy resin). Insert mold cover 1 into the central groove and pre-press with 10MPa pressure for 3-5 seconds. The structure after pressing is as follows. Figure 1 As shown, flour I (i.e., Figure 1 Sintered flour 3) and diamond mold core 4; the base powder I, diamond mold core 4, and flour I constitute the mold blank; The distance (H1) between the bottom end of the diamond mold core 4 and the bottom inlet end of the mold shell 2 is 3.8; the distance (H2) between the top end of the diamond mold core 4 and the top outlet end of the mold shell 2 is 4.2. 5) Sintering: The mold blank is placed in a hot press sintering machine for sintering. The process is as follows: First stage: The temperature is increased from room temperature to 700℃ at a rate of 60℃ / min, and an axial pressure of 20 MPa is applied and held for 12 min; Second stage: The temperature is increased to 850℃ at a rate of 80℃ / min, and after reaching the sintering temperature, the axial pressure is increased to 60 MPa and held for 2 min; Third stage: The sintering temperature is adjusted between 750-900℃, and the axial pressure is cyclically adjusted between 50-100 MPa for 6 cycles; Fourth stage: The mold blank is cooled in the furnace. When it cools to below 500℃, all pressure is released, and it continues to cool to room temperature to obtain the diamond wire drawing mold (single crystal diamond wire drawing mold insert).

[0033] According to the preparation process of Example 1, the parts were processed as a batch. 100 pieces were sintered in this batch. The hardness was tested by sampling according to the GB / T2828.1-2012 sampling inspection procedure. The hardness was HRC65-68. After the workpieces were machined, the yield rate was calculated. The yield rate was 99%.

[0034] Example 2 Example 2 provides a process for preparing diamond wire drawing dies. The difference between Example 2 and Example 1 is that: In step 1), the mass percentage of each powder raw material is as follows: nickel 45%, iron 6%, aluminum 5%, chromium 5%, tungsten 10%, titanium 27%, and silicon 2%.

[0035] In step 2), the amount of mixed powder is 0.4g; the pressure during pre-compression is 15MPa.

[0036] In step 4), the amount of mixed powder used is 0.8g; the pressure during pre-compression is 8MPa. The distance (H1) between the bottom end of the diamond mold core 4 and the bottom inlet end of the mold shell 2 is 3.9, and the distance (H2) between the top end of the diamond mold core 4 and the top outlet end of the mold shell 2 is 4.1.

[0037] In step 5), the sintering process is as follows: First stage: the temperature is increased from room temperature to 750℃ at a rate of 80℃ / min, and an axial pressure of 40 MPa is applied and held for 10 min; Second stage: the temperature is increased to 900℃ at a rate of 100℃ / min, and after reaching the sintering temperature, the axial pressure is increased to 80 MPa and held for 1.5 min; Third stage: the sintering temperature is adjusted between 750-900℃, and the axial pressure is cyclically adjusted between 50-100 MPa, for a total of 8 cycles; Fourth stage: the furnace is cooled, and when it cools to below 500℃, all pressure is released, and the furnace continues to cool to room temperature.

[0038] According to the preparation process of Example 2, the workpieces were processed as a batch. 100 pieces were sintered in this batch. The hardness was tested by sampling according to the GB / T2828.1-2012 sampling inspection procedure. The hardness was HRC67-70. After the workpieces were machined, the yield rate was calculated. The yield rate was 100%.

[0039] The above embodiments are illustrative examples of the implementation of the present invention. The implementation of the present invention is not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and are included within the protection scope of the present invention.

Claims

1. A process for preparing diamond wire drawing dies, characterized in that, The diamond wire drawing die is prepared by pressing and sintering, and the wire drawing die insert used in the pressing process includes components such as die cover and die shell. The preparation process includes the following steps: 1) Powder preparation: Mix and combine nickel, iron, aluminum, chromium, tungsten, titanium, and silicon powders in a certain ratio to obtain mixed powder; 2) Pre-pressed base powder: The mixed powder from step 1) is evenly filled into the mold shell and pre-pressed under a certain pressure to obtain base powder I; 3) Diamond setting: The single crystal diamond is fixed in the middle of the base powder I with adhesive; 4) Pre-pressed flour: The mixed powder from step 1) is evenly filled into the mold shell. At this time, the mixed powder added in step 4) covers the upper surface of the base powder I, single crystal diamond and binder. The mold cover is placed in and pre-pressed with a certain pressure to obtain flour I and diamond mold core. The base powder I, diamond mold core and flour I constitute the mold blank. 5) Sintering: The mold blank is sintered, and after sintering, the diamond wire drawing mold is obtained.

2. The process as described in claim 1, characterized in that, In step 1), the mass percentage of each powder raw material is as follows: nickel 40-50%, iron 5-15%, aluminum 5-10%, chromium 5-10%, tungsten 3-15%, titanium 25-40%, and silicon 1-2%.

3. The process as described in claim 1, characterized in that, In step 2), the pressure is 10-20 MPa and the pre-compression time is 3-5 seconds.

4. The process as described in claim 1, characterized in that, In step 3), the adhesive is epoxy resin glue.

5. The process as described in claim 1, characterized in that, In step 4), the pressure is 5-10 MPa and the pre-compression time is 3-5 seconds.

6. The process as described in claim 1, characterized in that, In step 4), after pressing, the distance from the bottom of the diamond mold core to the bottom entrance of the mold shell is H1; after pressing, the distance from the top of the diamond mold core to the top exit of the mold shell is H2, and H2 is greater than H1.

7. The process as described in claim 1, characterized in that, The sintering process in step 5) is as follows: First stage: heat from room temperature to 600-750℃ at a rate of 60-80℃ / min, and apply an axial pressure of 20-40 MPa, holding for 5-10 min; Second stage: heat to 800-900℃ at a rate of 80-100℃ / min, and after reaching the sintering temperature, increase the axial pressure to 60-100 MPa, holding for 1-3 min; Third stage: adjust the sintering temperature to 750-900℃, and cycle the axial pressure between 50-100 MPa for 6-8 cycles; Fourth stage: cool with the furnace, and when the temperature drops below 500℃, release all pressure and continue cooling to room temperature.

8. A diamond wire drawing die prepared using any one of the processes described in claims 1 to 7.

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