A double-sided reversible drawing single crystal diamond die for drawing 10 mu m high-strength stainless steel micro-wire and a method of using the same

Abstract

The application discloses a double-face reversible drawing single-crystal diamond die for drawing 10 mu m high-strength stainless steel micro-wire and a use method thereof, and belongs to the technical field of metal micro-wire precision machining. The die comprises a die sleeve and a single-crystal diamond die core, the die core is internally provided with an axial through drawing die hole, and both end faces of the die can be used as wire feeding working ends. The die hole is sequentially provided with a compression zone, a sizing zone and an outlet zone along a drawing direction. In use, one end face is used first, and after being worn, the die is turned over to use the other end face. The application solves the problems of existing single-side die, such as concentrated wear, low material utilization rate, short service life and high production cost, effectively prolongs the service life of the die, improves the utilization rate of the diamond material, reduces the wire breakage rate and product size fluctuation, does not need to reform the existing equipment, is suitable for 10 mu m high-strength stainless steel micro-wire finished product and finishing drawing processes, and has a wide industrial application prospect.

Description

Technical Field

[0001] This invention relates to the field of precision plastic processing technology for metal micro-wires, specifically to a double-sided reversible drawing single-crystal diamond mold for drawing 10μm high-strength stainless steel microwires and its method of use. Background Technology

[0002] With the rapid development of industries such as precision electronic components, medical guidewires, micro-elastic elements, microprobes, ultrafine filter materials, and high-end braided components, the market application scope of 10μm-grade high-strength stainless steel microwires continues to expand. These microwires are characterized by their small size, high tensile strength, significant work hardening effect, and stringent requirements for drawing process stability. Therefore, extremely high standards are placed on the hole shape processing accuracy, surface wear resistance, overall service life, and operational stability of the drawing die.

[0003] Currently, single-crystal diamond dies are commonly used for 10μm-level microwire drawing. These dies have high hardness, excellent wear resistance, and good surface finish, making them the preferred dies for finishing ultrafine metal microwires and drawing multiple passes. However, existing single-crystal diamond dies are all single-sided working structures. After the die is installed on the machine, only one end face is fixed as the wire inlet working end, while the other end face does not participate in the drawing operation at all.

[0004] During the drawing process of high-strength stainless steel microwires, the die entrance area is continuously subjected to compression and intense friction from the microwires. Localized concentrated wear is prone to occur in the die compression zone and the sizing zone entrance. When the wear on one side of the working end reaches a critical value, it will directly cause problems such as increased fluctuations in drawing force, deterioration of microwire surface quality, a significant increase in wire breakage rate, and expansion of finished wire diameter deviation. At this point, the only solution is to replace the die or rework the die.

[0005] Existing technologies have several drawbacks: First, the mold is only used on one side, resulting in extremely low utilization of single-crystal diamond material. Second, mold failure is mainly caused by localized wear in the single-sided entry area, leading to a short overall service life. Third, 10μm high-strength stainless steel microwires are highly sensitive to minute wear in the mold holes, easily causing quality problems in batch products. Fourth, the raw materials and processing costs of single-crystal diamond are high, and the single-sided usage mode significantly increases the overall cost of microwire production. Therefore, the industry urgently needs a new type of single-crystal diamond mold that can operate on both sides alternately, which can improve material utilization, extend mold life, and reduce production costs while ensuring drawing accuracy and stability. Summary of the Invention

[0006] This invention aims to overcome the technical defects of existing single-sided working single-crystal diamond molds, such as concentrated wear, low material utilization, short service life, high production cost, and poor stability of microwire drawing. It solves the industry pain points of premature failure of one side of the mold, micro-wear of the mold hole affecting product quality, and frequent mold replacement during the drawing of 10μm high-strength stainless steel microwires. At the same time, it takes into account the compatibility with existing drawing equipment and can be put into use without large-scale modification of the equipment.

[0007] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0008] A double-sided reversible drawing single-crystal diamond die for drawing 10μm high-strength stainless steel microwires includes a cemented carbide die sleeve and a single-crystal diamond die core embedded in the center of the die sleeve. The single-crystal diamond die core has a drawing die hole that is completely through along the axial direction.

[0009] The core improvement of this invention lies in the fact that the drawing die hole is formed with a standard working hole shape on both opposite end faces of the die, and both end faces of the die can be used as the wire inlet working end to independently complete the drawing operation, realizing double-sided reversible use.

[0010] Furthermore, when any end face is used as the inlet, the drawing die orifice is sequentially divided into a compression zone, a sizing zone, and an outlet zone along the microwire drawing direction; the finished orifice diameter is fixed at 10μm. The compression angle in the compression zone is set to 11°, and the outlet angle in the outlet zone is set to 20°; the length of the sizing zone is 50% of the finished orifice diameter, i.e., 5μm. These orifice parameters are specific parameters optimized for 10μm high-strength stainless steel microwires, adaptable to the plastic deformation characteristics of this microwire specification, and reducing friction and the probability of wire breakage.

[0011] Another aspect of the present invention provides a method for using the aforementioned mold, the specific steps of which are as follows: First, the first end face of the mold is installed as the wire inlet end on the drawing equipment, and normal drawing production is carried out; when the side die hole of the first end face experiences process abnormalities and product quality degradation due to wear, the mold is removed and flipped over, and the second end face is used as the new wire inlet end for reinstallation and continued drawing operation. After the mold is flipped over, there is no need to adjust the equipment parameters, and it can be directly matched with the original production process.

[0012] This invention does not simply change the mold installation direction, but rather, from the mold hole structure design level, it enables both ends of the mold to have complete drawing functions and standard hole parameters, forming a dual-sided alternating working mode, fundamentally changing the problem of single-sided wear failure of traditional molds.

[0013] Compared with the prior art, the beneficial effects of the present invention are:

[0014] (1) The present invention adopts a double-sided reversible structure, so the service life of the mold is no longer determined by the local wear of a single working end. After one side is worn, the mold can be flipped over to use the other side, which significantly improves the cumulative effective working time of the mold. According to actual measurement, the cumulative drawing length of a traditional single-sided mold is about 30,000 meters, while the cumulative drawing length of the mold of the present invention can reach 50,000 meters after flipping over, which shows a significant improvement in service life.

[0015] (2) Single crystal diamond is expensive. Traditional molds only utilize the structure on one side, leaving the other side completely idle. This invention makes full use of the structure at both ends of the mold core to maximize the value of diamond material and reduce material waste.

[0016] (3) The mold service life is extended, effectively reducing the frequency of mold procurement and repair, and reducing the downtime of equipment caused by mold replacement. This reduces the mold consumption cost per unit length of microfilament and improves the continuous operation efficiency of the production line.

[0017] (4) The present invention is configured with exclusive optimized hole parameters (11° compression angle, 5μm sizing band, 20° exit angle) to adapt to the deformation characteristics of 10μm high-strength stainless steel microwires, which can effectively reduce wire diameter fluctuation, reduce microwire surface defects and wire breakage rate, and ensure the consistency of finished product quality.

[0018] (5) This invention only improves the structure and usage of the mold body, without requiring structural modification or parameter reconstruction of the existing micro-wire drawing equipment. It can be directly promoted and applied on the existing production line, with low implementation cost and easy popularization. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of the mold provided in an embodiment of the present invention.

[0020] Figure 2 This is a schematic diagram of the cross-sectional structure of the drawing die hole provided in an embodiment of the present invention.

[0021] Figure 3 This is a usage state diagram with the first end face as the working end provided in an embodiment of the present invention.

[0022] Figure 4 This is a usage state diagram with the second end face as the working end provided in an embodiment of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1

[0025] This embodiment provides a double-sided reversible drawing single-crystal diamond mold adapted for drawing 10μm high-strength stainless steel microwires. The mold includes a cemented carbide mold sleeve (e.g., WC-Co cemented carbide) and a single-crystal diamond core that is precisely embedded in the center of the mold sleeve by hot pressing or cold pressing.

[0026] The cemented carbide mold sleeve serves as an external support structure, possessing high strength and good impact resistance. It is used to fix the internal mold core and adapt to the installation position of the drawing equipment. The single-crystal diamond mold core is coaxially embedded and fixed in the central cavity of the cemented carbide mold sleeve, ensuring a firm connection without relative displacement.

[0027] The single-crystal diamond mold core has an axially continuous drawing die hole inside, and the finished die hole diameter is strictly controlled to 10μm. The mold is divided into a first end face and a second end face that are set opposite to each other. The die holes at both end faces are machined into complete working hole shapes, and the structure and hole shape parameters at both ends are completely consistent.

[0028] The core improvement of this invention lies in the fact that the drawing die orifice is machined into an optimized working hole shape at both the first and second end faces of the die, which are arranged opposite to each other, so that it can be used as the wire inlet end. This means that no matter which end face the operator selects as the wire inlet end, that end face can provide effective compression, sizing, and outlet functions, thereby enabling both end faces of the die to be used as actual drawing working ends.

[0029] Specifically, when any end face is used as the infeed working end, the die hole is divided into a compression zone, a sizing zone, and an exit zone along the drawing direction:

[0030] Compression Zone: The compression angle α of the compression zone is precisely machined to 11°. This angle effectively reduces the shear band of metal flow and lowers the drawing force while ensuring sufficient deformation efficiency. This angle allows the 10μm high-strength stainless steel microwire to smoothly complete plastic deformation, avoiding local stress concentration that could lead to wire breakage.

[0031] Sizing belt: The length L of the sizing belt is 50% of the finished aperture D. For a finished aperture of 10μm, the length L of the sizing belt is 5μm. This length ensures that the microfilament obtains a stable final size, avoids excessive friction due to an excessively long sizing belt, and ensures accurate dimensions and qualified roundness of the microfilament after drawing.

[0032] Exit zone: The exit angle β of the exit zone is 20°. This angle is conducive to the smooth exit of the microfilament after leaving the sizing zone, reduces the frictional resistance when the microfilament exits the mold, and protects the surface of the microfilament from being scratched.

[0033] The hole parameters at both ends of this mold are completely uniform, ensuring that the process state is completely consistent after flipping and use, and will not affect the quality of the microfilament products.

[0034] Example 2

[0035] Please combine Figure 3 and Figure 4 This embodiment details the method of using the aforementioned mold for drawing 10μm high-strength stainless steel microwires (e.g., 316LVM or 304 series stainless steel microwires with a tensile strength of over 2000MPa). The specific operating steps are as follows:

[0036] Step 1: First Stage Pulling

[0037] Assemble this mold onto a 10μm high-strength stainless steel microwire drawing machine, ensuring the first end face of the mold faces the microwire inlet direction. Fix the mold position and start the drawing machine for continuous production. This stage relies on the compression zone, sizing zone, and exit zone on the first end face to complete the microwire drawing process.

[0038] Step 2: Wear Monitoring and Reversal Judgment

[0039] As the drawing length increases, normal annular wear will gradually occur at the compression zone inlet and the sizing zone starting area corresponding to the first end face. Regularly monitor the operating parameters of the drawing equipment and the quality of the finished microfilaments: focus on monitoring the fluctuation range of the drawing force, the deviation of the microfilament outer diameter, the frequency of wire breakage, and the surface finish of the microfilaments. When phenomena such as increased drawing force fluctuation, wire diameter deviation, increased wire breakage rate, and increased surface scratches occur, it is determined that wear has occurred in the compression zone of the first end face side die hole and the sizing zone inlet area, and the equipment should be stopped.

[0040] Step 3: Die flipping and second-stage drawing

[0041] After confirming the failure of the first end face, stop the machine and remove the old mold. At this time, the second end face of the mold and its corresponding compression zone and sizing zone are still in a brand new or slightly worn state. Figure 4 As shown, the die is rotated 180° around its axis in the horizontal plane, so that the second end face, which was originally facing the wire exit direction, now faces the wire inlet direction. The rotated die is then reinstalled onto the wire drawing machine. Since the hole structure and parameters at both ends of the die are completely identical, there is no need to adjust any process parameters such as drawing speed, tension, or lubrication; the drawing operation can be continued simply by restarting the equipment.

[0042] The mold should be used in a cyclical manner until both working ends of the mold reach their wear limit, at which point a new mold should be replaced.

[0043] Example 3

[0044] To verify the effectiveness of the present invention, a comparative experiment was conducted.

[0045] Using the same batch of raw materials, 10μm high-strength stainless steel microwires of the same specification, and the same set of drawing equipment, comparative tests were conducted using a traditional single-sided monocrystalline diamond mold and the double-sided reversible mold of this invention:

[0046] Control group: 10μm high-strength stainless steel microwires were drawn using a conventional single-sided working end single-crystal diamond mold (other hole parameters were the same as those of this invention).

[0047] Experimental group: The mold described in Example 1 of this invention was used, and the method described in Example 2 was used for double-sided alternating drawing.

[0048] Experimental results:

[0049] Lifespan comparison: In the control group, the die experienced a sharp increase in wire breakage rate after a cumulative drawing length of approximately 28,000 meters, indicating failure. In the experimental group, the die wore out after drawing approximately 29,000 meters on the first end face, and after being flipped over, continued drawing on the second end face for approximately 27,000 meters, achieving a cumulative effective drawing length of 56,000 meters. Overall, the lifespan was improved.

[0050] Quality comparison: Throughout the entire effective lifespan, the 10μm microfilaments drawn from the experimental group showed better performance in terms of diameter fluctuation range (±0.2μm) and surface defect density than the control group in the later stages of wear (e.g., after 20,000 meters).

[0051] Economic comparison: The total output of a single mold increases, and the mold procurement cost and maintenance cost per unit length of microfilament decreases significantly; at the same time, the frequency of mold changes decreases, the effective production time of the equipment increases, and the overall production capacity of the production line is improved.

[0052] Example 4

[0053] The mold of this invention is preferably used in the finished drawing and finishing drawing processes of 10μm high-strength stainless steel microwires. These processes have the highest requirements for mold precision and stability, and are also the processes with the fastest wear of traditional single-sided molds.

[0054] Furthermore, this invention is not limited to 10μm high-strength stainless steel microwires. Its "double-sided reversible" design concept and optimized hole shape parameter ratios can also serve as a reference for precision drawing of other similar specifications (such as 5-20μm range) of high-strength metal microwires (such as high-carbon steel, titanium alloys, nickel-titanium alloys, etc.). For different materials and sizes, parameters such as compression angle and sizing band ratio can be adaptively adjusted according to actual needs, but the core idea that "both sides can be used as working ends" has broad applicability.

[0055] In summary, this invention, when drawing high-strength stainless steel microwires, first involves the microwire entering the compression zone to undergo radial compression plastic deformation, then being shaped to a standard 10μm size by the sizing zone, and finally exiting the die smoothly through the exit zone. Traditional dies only bear friction and compression at one end for extended periods, leading to continuous wear accumulation. This invention utilizes an equivalent working structure at both ends, distributing wear across both working ends. Wear at one end is switched to the other, slowing down the wear rate at one end and fully utilizing the overall die structure. Optimized parameters, including an 11° compression angle, a 5μm sizing zone, and a 20° exit angle, are matched to the deformation mechanical properties of the ultrafine, high-strength microwires, extending die life while ensuring stable drawing processes.

[0056] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0057] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A double-sided reversible drawing single-crystal diamond die for drawing 10μm high-strength stainless steel microwires, comprising a die sleeve and a single-crystal diamond die core embedded inside the die sleeve, wherein the single-crystal diamond die core has a drawing die hole that extends along the axial direction, characterized in that: The drawing die has working holes formed on both opposite end faces of the die, which can be used as wire feed ends. Both end faces of the die can be used independently as drawing working ends.

2. The double-sided reversible drawing single-crystal diamond mold according to claim 1, characterized in that: When any one end face is taken as the inlet working end, the drawing die hole is provided with a compression zone, a sizing zone and an outlet zone in sequence along the microwire drawing direction.

3. The double-sided reversible drawing single-crystal diamond mold according to claim 2, characterized in that: The compression angle of the compression zone is 11°, the length of the sizing zone is 50% of the finished diameter of the drawing die hole, and the exit angle of the exit zone is 20°.

4. The double-sided reversible drawing single-crystal diamond mold according to claim 2, characterized in that: The finished diameter of the drawing die hole is 10 μm, and the length of the sizing strip is 5 μm.

5. The double-sided reversible drawing single-crystal diamond mold according to claim 1, characterized in that: The mold sleeve is a cemented carbide mold sleeve, and the single-crystal diamond mold core is coaxially fixed at the center position of the cemented carbide mold sleeve.

6. A method of using the double-sided reversible drawing single-crystal diamond mold according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Assemble the mold onto the microwire drawing equipment, so that the first end face of the mold faces the direction of the microwire inlet, and use the first end face as the inlet working end to carry out the 10μm high-strength stainless steel microwire drawing operation. S2. Real-time monitoring of the drawing process. When wear occurs in the compression zone or sizing zone entrance area corresponding to the first end face, causing fluctuations in drawing force, increased wire size deviation, increased wire breakage rate, or decreased wire surface quality, the drawing operation is stopped. S3. Remove the mold from the equipment and flip it over so that the second end face of the mold faces the direction of the microfilament inlet. After reassembly, use the second end face as the inlet working end and continue the microfilament drawing operation.

7. The method of use according to claim 6, characterized in that: After a single mold flip, the compression zone, sizing zone and exit zone corresponding to the second end face are perfectly adapted to the drawing process requirements of 10μm high-strength stainless steel microwires, without the need to adjust the drawing equipment and process parameters.

8. The method of use according to claim 6, characterized in that: The mold is used for the finished drawing or finishing drawing of 10μm high-strength stainless steel microwires, and is also suitable for the drawing of high-strength metal microwires of the same specifications.

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