A method for preparing a small-sized, complex, and irregular-shaped cavity polycrystalline drawing die

Abstract

The present invention discloses a preparation method of a polycrystal drawing die for a small-sized complex special-shaped cavity, comprising the following steps: S1, sintering a blank; S2, punching a wire hole; S3, primary cutting; S4, secondary cutting; S5, manual pre-polishing; S6, fluid polishing; S7, visual inspection with a microscope; S8, silicone two-dimensional projection inspection; S9, die sleeve inlaying; the present invention solves the problem that traditional special-shaped wire drawing dies can only process dies with simple geometric contours but cannot process dies with small-sized complex cavities. The processing route is reasonably decomposed according to the contour of the cavity, and ultra-high precision slow-wire cutting equipment is used to first process the through hole of the small-sized special-shaped cavity. Then, in view of the greatest technical difficulty of the irregularities of the compression zone and the outlet zone of the special-shaped cavity, the straight line part and the arc part are processed in sections to ensure that the length and angle of the compression zone and the outlet zone are consistent, thereby improving the product detection and inspection method and improving the first-time good rate and delivery qualified rate.

Description

Technical Field

[0001] The present invention relates to the technical field of mold processing methods, in particular to a method for preparing a small-sized, complex, and irregular-shaped cavity polycrystal drawing mold. Background Art

[0002] The wire drawing die is the most important tool in the metal wire processing process. Its main function is to force the metal wire through the die hole under the action of external force, so that the cross-sectional area of ​​the metal wire is compressed and deformed to the expected diameter or shape. The rationality of the wire drawing die design directly affects its service life and the quality of metal wire drawing. The existing pressure die needs to be improved in terms of wear resistance and service life.

[0003] Polycrystalline wire drawing dies are widely used due to their high hardness and good wear resistance. Although China is the world's largest producer of polycrystalline products and a major producer of polycrystalline wire drawing dies, it mainly produces circular wire drawing dies and polycrystalline wire drawing dies with simple geometric shapes. With the rapid development of my country's new energy industry, the market demand for small-sized special-shaped wires has grown rapidly, and the demand for small-sized complex special-shaped cavity polycrystalline drawing dies is also in an explosive stage. However, the unreasonable preparation process of domestic small-sized complex special-shaped cavity drawing dies makes it difficult to guarantee the quality accuracy of the final product. The existing preparation methods have low processing efficiency, high cost and low yield rate, and cannot achieve large-scale production. Summary of the Invention

[0004] To solve the above technical problems, the present invention relates to a method for preparing a small-sized, complex, and irregular-shaped polycrystalline drawing die. This method is simple and reliable, effectively solves the above technical problems, and is suitable for popularization and use. To achieve the above purpose, the present invention is implemented through the following technical solutions:

[0005] A method for preparing a small-sized, complex, and irregular-shaped polycrystalline drawing die comprises the following steps:

[0006] S1, sintering the blank to obtain a fine-grained polycrystalline mold core blank with a diameter of 10 mm and a thickness of 3 mm;

[0007] S2, punching the wire hole, fixing it on the enhanced pulse laser perforator through a special fixture adapted to the fine-grain polycrystalline mold core blank, passing nitrogen for protection, keeping the two end faces of the fine-grain polycrystalline mold core blank parallel, completing the clamping and setting the perforation depth and pre-perforation starting height, and then punching until the wire hole of the fine-grain polycrystalline mold core blank is punched through;

[0008] S3, one-time cutting, place the micro-grain polycrystalline mold core blank that has been laser perforated on the adjustable center and angle fixture of the slow-moving wire cutting machine, keep the two end faces of the micro-grain polycrystalline mold core blank parallel, and then pass the electrode wire of the slow-moving wire cutting machine through the wire hole of the micro-grain polycrystalline mold core blank and cut it at 10mm. 2 / min processing parameters are used to complete the cutting of small-sized special-shaped cavity through holes. The cutting process uses oil cooling and the processing accuracy is controlled within ±0.003mm and the roughness is Ra0.5um;

[0009] S4, secondary cutting, using a precision slide with a special adjustable center and angle fixture to adjust the fine grain polycrystalline mold core blank and cut the compression area of ​​its small-sized special-shaped cavity, cut each straight line segment and R angle arc in the compression area separately, control the compression angle of the compression area to 11.5°, keep a 0.8mm length of the sizing area and a 0.3mm exit area from the reference surface, and the rest of the height is the compression area cutting part. When cutting the compression area, the exit area is cut diagonally at the same time. The processing parameters are set to 10mm 2 / min, the machining process uses oil cooling and the machining accuracy is controlled within ±0.003mm, angle ±25°, and roughness Ra0.5um;

[0010] S5, manual pre-polishing, using a micro manual polishing machine to pre-polish the compression area, exit area, and front and rear transition areas of the fine-grain polycrystalline die core after slow-wire precision cutting. This ensures that there are no cutting marks in the compression area, the arc and the straight line are close to the tangent transition, and the contour lines of the front and rear transition areas are complete and smoothly transitioned, without any residual cross-cutting line transition phenomenon.

[0011] S6, fluid polishing, the fine grain polycrystalline mold core after manual polishing is used in a capillary inner wall magnetic composite fluid polishing machine to form a Bingham fluid, and the shear force generated by the Bingham fluid is used to polish the irregular inner wall of the workpiece. The polishing time is 30 minutes and the roughness is made to meet Ra0.3um, thus achieving the mirror surface requirement;

[0012] S7, use a microscope to visually inspect the mirror effect of the compression area, sizing area, outlet area and front and rear transition areas of the small-sized special-shaped cavity of the fine-grain polycrystalline mold core that has completed fluid polishing to confirm that there are no polishing dead corners.

[0013] On the basis of the above scheme and as a preferred scheme of the above scheme: in step S2, the wire hole of the fine-grain polycrystalline mold core blank is punched in three stages, wherein the frequency of the first stage is set to 2800 Hz, focus -5, the second stage is set to frequency 1900 Hz, focus -3, and the third stage frequency is set to 1500 Hz, focus 0.

[0014] On the basis of the above scheme and as a preferred scheme of the above scheme: the microscope is a 400x microscope.

[0015] On the basis of the above scheme and as the preferred scheme of the above scheme: it also includes step S8, silicone two-dimensional projection detection, filling the special-shaped cavity with medical silicone and compacting it to ensure that the silicone is fully filled in the small-sized special-shaped cavity in the center of the fine-grain polycrystalline mold without air holes. After the silicone is solidified, the solidified silicone is picked out with a needle-shaped object, and the compression zone angle, sizing zone length and cavity geometric dimensions of the small-sized special-shaped cavity are detected with a two-dimensional projector. Products that meet the length and angle requirements are qualified products, otherwise they are scrapped.

[0016] On the basis of the above scheme and as a preferred scheme of the above scheme: it also includes step S9, mold sleeve inlaying, in which the fine-grain polycrystalline mold core that has passed the inspection is mold sleeve inlaid.

[0017] Compared with the prior art, the present invention has the following outstanding and beneficial technical effects: the present invention solves the problem that traditional special-shaped wire drawing dies can only process simple geometric contours but cannot process molds with small-sized complex cavities. The processing route is reasonably decomposed according to the contour of the cavity, and ultra-high precision slow-wire wire cutting equipment is used to first process small-sized special-shaped cavity through holes. Then, in view of the biggest technical difficulty of the irregularities in the compression zone and outlet zone of the special-shaped cavity, a precision slide is used with a special adjustable center and angle clamp to process the straight part and the arc part in sections to ensure that the length and angle of the compression zone and the outlet zone are consistent. The new process and technology of manual pre-polishing and thin tube inner wall magnetic composite fluid polishing machine are adopted to improve the product inspection and testing method, and the microscopic visual inspection and filler cavity molding method are adopted to improve the product inspection means and improve the first-time yield and delivery qualification rate.

[0018] The following problems are solved: 1. The cavity size error is large and the scrap rate is high during rough processing; 2. The angles of the compression zone and the exit zone are inconsistent, and the angle error is large, resulting in inconsistent extrusion deformation trends of the materials in various parts during the drawing process of the special-shaped wire, unstable speed during the drawing process of the special-shaped wire, unstable state entering the sizing zone, manifested as deflection and twisting, deformation of small-sized special-shaped wires, out-of-tolerance geometric dimensions, and unstable consistency; 3. The straight line segment and the arc segment in the transition zone between the compression zone and the sizing belt cannot be accurately connected, and the small-sized special-shaped wires have axial protrusions or depressions, resulting in poor appearance of the finished special-shaped wires; 4. The space of the small-sized special-shaped cavity is extremely limited, and the manual polishing process cannot accurately polish, the roughness cannot reach the desired area, the friction is too large, the lubricity deteriorates, and it is easy to cause sticking of the compression zone and the sizing belt, product scratches, scratches, surface copper powder peeling and other undesirable phenomena; 5. The existing detection means are single and it is difficult to ensure detection accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1It is a schematic diagram of the overall process of the preparation method. DETAILED DESCRIPTION

[0020] In order to make the objectives, technical solutions and advantages of this application clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments. However, the specific implementation methods and embodiments described below are only for illustrative purposes and are not intended to limit the present invention.

[0021] In the description of the present invention, it should be understood that the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate directions or positional relationships based on the attached Figure 1 The directions or positional relationships shown are only for the convenience of describing the present invention, and do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, they should not be understood as limiting the present invention.

[0022] In the description of this application, the terms "first", "second", etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features.

[0023] In order to solve the above technical problems, the present invention designs a method for preparing a small-sized complex special-shaped cavity polycrystalline drawing die, which includes the following steps:

[0024] S1, sintering the blank to obtain a micro-grained polycrystalline mold core blank with a diameter of 10mm and a thickness of 3mm. S2, punching the wire holes, fixing it on the enhanced pulse laser perforator through a special fixture adapted for the micro-grained polycrystalline mold core blank, and introducing nitrogen for protection. Nitrogen protection can isolate the oxygen in the air to prevent oxidation and the formation of pores, keep the two end faces of the micro-grained polycrystalline mold core blank parallel, avoid tilting, loosening and other undesirable phenomena, complete the clamping and set the perforation depth and pre-perforation starting height, and then punch the micro-grained polycrystalline mold core blank through the wire holes in three stages, of which the frequency of the first stage is set to 280 0hz, focus -5, the second stage is set to frequency 1900hz, focus -3, the third stage frequency is set to 1500hz, focus 0. Since the perforation has a certain height in the first and second stages, the perforation adopts negative focus, which can ensure that the spot size at the perforation position is the smallest and the energy density is the largest. The deeper the perforation position, the larger the negative focus. When cutting with negative focus, the cutting surface texture is uniform and the cross-section is better. When cutting with zero focus, the cutting surface close to the focus will be smoother, further improving the surface quality.

[0025] S3, one-time cutting, using UPJ-2 ultra-precision wire cutting machine, the fine grain polycrystalline core blank that has been laser perforated is placed on the adjustable center and angle fixture of the wire cutting machine, keeping the two ends of the fine grain polycrystalline core blank parallel to avoid tilting, loosening and other undesirable phenomena, and then passing the electrode wire of the wire cutting machine through the wire hole of the fine grain polycrystalline core blank and cutting it with a 10mm 2 / min processing parameters are used to cut small-sized special-shaped cavity through holes. The cutting process uses oil cooling and the processing accuracy is controlled at ±0.003mm and the roughness is Ra0.5um.

[0026] S4, secondary cutting, using a precision slide with a special adjustable center and angle fixture to adjust the fine grain polycrystalline mold core blank and cut the compression area of ​​its small-sized special-shaped cavity, cut each straight line segment and R angle arc in the compression area separately, control the compression angle of the compression area to 11.5°, keep a 0.8mm length of the sizing area and a 0.3mm exit area from the reference surface, and the rest of the height is the compression area cutting part. When cutting the compression area, the exit area is cut diagonally at the same time. The processing parameters are set to 10mm 2 / min, the machining process uses oil cooling and the machining accuracy is controlled at ±0.003mm, angle ±25°, and roughness Ra0.5um.

[0027] S5, manual pre-polishing, using a micro manual polishing machine to pre-polish the compression area, exit area and front and rear transition areas of the fine-grain polycrystalline die core after slow-wire precision cutting, so that there are no cutting marks in the compression area, the arc and the straight line are close to the tangent transition, the contour lines of the front and rear transition areas are complete and the arc transition is smooth, without any residual cutting line cross transition phenomenon.

[0028] S6, fluid polishing, the fine grain polycrystalline mold core after manual polishing is used to form a Bingham fluid using a capillary inner wall magnetic composite fluid polishing machine. The irregular inner wall of the workpiece is polished by the shear force generated by the Bingham fluid. The polishing time is 30 minutes and the roughness is made to meet Ra0.3um to achieve the mirror surface requirement.

[0029] S7, visual inspection using a microscope with a magnification of 400 to ensure observation accuracy, inspect the mirror effect of the compression area, sizing area, outlet area and front and rear transition areas of the small-sized special-shaped cavity of the fine-grain polycrystalline mold core that has completed fluid polishing to confirm that there are no polishing dead angles.

[0030] Step S8, silicone two-dimensional projection inspection, fill the special-shaped cavity with medical silicone and compact it to ensure that the silicone is fully filled in the small-sized special-shaped cavity of the micro-grain polycrystalline mold core and there are no pores. After the silicone solidifies, use a needle to pick out the solidified silicone. Use a two-dimensional projector to inspect the angle of the compression zone, the length of the sizing zone, and the geometric dimensions of the cavity. Products that meet the length and angle requirements are qualified products, otherwise they are scrapped. Step S9, mold sleeve inlaying, the qualified micro-grain polycrystalline small-sized special-shaped cavity mold core flows into the mold sleeve inlaying process, and the mold sleeve is inlaid with the outer circle of the end face. During inlaying, focus on controlling the geometric center of the special-shaped cavity of the micro-grain polycrystalline small-sized special-shaped cavity mold core to be consistent with the center of the mold sleeve. The mold sleeve outer circle diameter is φ30mm±0.05, the height is 20mm±0.03, and the perpendicularity between the end face of the mold sleeve and the outer circle meets the requirements.

[0031] Step S10: performing laser marking.

[0032] The above scheme mainly solves the following problems: 1. The error in cavity size is large and the scrap rate is high during rough processing; 2. The angles of the compression zone and the exit zone are inconsistent, and the angle error is large, resulting in inconsistent extrusion deformation trends of the materials in various parts during the drawing process of the special-shaped wire, unstable speed during the drawing process of the special-shaped wire, unstable state entering the sizing zone, manifested as deflection and twisting, deformation of small-sized special-shaped wire, out-of-tolerance geometric dimensions, and unstable consistency; 3. The straight line segment and the arc segment in the transition zone between the compression zone and the sizing belt cannot be accurately connected, and the small-sized special-shaped wire has axial protrusions or depressions, resulting in poor appearance of the finished special-shaped wire; 4. The space of the small-sized special-shaped cavity is extremely limited, and the manual polishing process cannot accurately polish it. The roughness cannot reach the desired area, the friction is too large, and the lubricity deteriorates, which is prone to sticking to the mold in the compression zone and the sizing belt, product scratches, scratches, surface copper powder peeling and other undesirable phenomena; 5. The existing detection means are single and it is difficult to ensure detection accuracy.

[0033] The present invention solves the problem that traditional special-shaped wire drawing dies can only process simple geometric contours but cannot process small-sized complex cavity molds. The processing route is reasonably decomposed according to the contour of the cavity, and ultra-high precision slow-feed wire cutting equipment is used to first process small-sized special-shaped cavity through holes. Then, in view of the biggest technical difficulty of the irregularities in the compression zone and outlet zone of the special-shaped cavity, a precision slide is used with a special adjustable center and angle clamp to process the straight part and the arc part in sections to ensure that the length and angle of the compression zone and the outlet zone are consistent. The new process and technology of manual pre-polishing and thin tube inner wall magnetic composite fluid polishing machine are adopted to improve the product inspection and testing method, and the microscopic visual inspection and filler cavity molding method are adopted to improve the product inspection means and improve the first-time yield and delivery qualification rate. The present invention has achieved new breakthroughs mainly in processing technology and detection means, which can realize that the geometric dimensions of small-sized special-shaped cavity polycrystalline wire drawing dies meet ±0.002mm, and the sizing zone and compression zone can both reach a roughness of Ra0.2um. The internationally accepted small-sized cavity polycrystalline wire drawing die detection means are adopted to accurately identify the product quality of small-sized special-shaped cavity polycrystalline wire drawing dies.

[0034] The above embodiments are only preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made by technicians in the relevant technical field based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a small-sized, complex, and irregular-shaped polycrystalline drawing die, characterized by: The following steps are included: S1, sintering the blank to obtain a fine-grained polycrystalline mold core blank with a diameter of 10 mm and a thickness of 3 mm; S2, punching the wire hole, fixing it on the enhanced pulse laser perforator through a special fixture adapted to the fine-grain polycrystalline mold core blank, passing nitrogen for protection, keeping the two end faces of the fine-grain polycrystalline mold core blank parallel, completing the clamping and setting the perforation depth and pre-perforation starting height, and then punching until the wire hole of the fine-grain polycrystalline mold core blank is punched through; S3, one-time cutting, place the micro-grain polycrystalline mold core blank that has been laser perforated on the adjustable center and angle fixture of the slow-moving wire cutting machine, keep the two end faces of the micro-grain polycrystalline mold core blank parallel, and then pass the electrode wire of the slow-moving wire cutting machine through the wire hole of the micro-grain polycrystalline mold core blank and cut it. 10mm 2 / min processing parameters are used to complete the cutting of small-sized special-shaped cavity through holes. The cutting process uses oil cooling and the processing accuracy is controlled within ±0.003mm and the roughness is Ra0.5um; S4, secondary cutting, using a precision slide with a special adjustable center and angle fixture to adjust the fine grain polycrystalline mold core blank and cut the compression area of ​​its small-sized special-shaped cavity, cut each straight line segment and R angle arc in the compression area separately, control the compression angle of the compression area to 11.5°, keep a 0.8mm length of the sizing area and a 0.3mm exit area from the reference surface, and the rest of the height is the compression area cutting part. When cutting the compression area, the exit area is cut diagonally at the same time. The processing parameters are set to 10mm 2 / min, the machining process uses oil cooling and the machining accuracy is controlled within ±0.003mm, angle ±25°, and roughness Ra0.5um; S5, manual pre-polishing, using a micro manual polishing machine to pre-polish the compression area, exit area, and front and rear transition areas of the fine-grain polycrystalline die core after slow-wire precision cutting. This ensures that there are no cutting marks in the compression area, the arc and the straight line are close to the tangent transition, and the contour lines of the front and rear transition areas are complete and smoothly transitioned, without any residual cross-cutting line transition phenomenon. S6, fluid polishing, the fine grain polycrystalline mold core after manual polishing is used in a capillary inner wall magnetic composite fluid polishing machine to form a Bingham fluid, and the shear force generated by the Bingham fluid is used to polish the irregular inner wall of the workpiece. The polishing time is 30 minutes and the roughness is made to meet Ra0.3um, thus achieving the mirror surface requirement; S7, use a microscope to visually inspect the mirror effect of the compression area, sizing area, outlet area and front and rear transition areas of the small-sized special-shaped cavity of the fine-grain polycrystalline mold core that has completed fluid polishing to confirm that there are no polishing dead corners.

2. The method for preparing a small-sized, complex, and irregular-shaped polycrystalline drawing die according to claim 1, characterized in that: In step S2, the wire hole of the fine-grain polycrystalline mold core blank is punched in three stages, wherein the frequency of the first stage is set to 2800 Hz, focus -5, the second stage is set to 1900 Hz, focus -3, and the third stage is set to 1500 Hz, focus 0.

3. The method for preparing a small-sized, complex, and irregular-shaped polycrystalline drawing die according to claim 2, characterized in that: The microscope is a 400-fold microscope.

4. The method for preparing a small-sized, complex, and irregular-shaped polycrystalline drawing die according to claim 3, characterized in that: It also includes step S8, silicone two-dimensional projection detection, filling the special-shaped cavity with medical silicone and compacting it to ensure that the silicone is fully filled in the small-sized special-shaped cavity in the center of the fine-grain polycrystalline mold without air holes. After the silicone is solidified, the solidified silicone is picked out with a needle-shaped object, and the two-dimensional projector is used to detect the angle of the compression zone, the length of the sizing zone and the geometric dimensions of the cavity of the small-sized special-shaped cavity. Products that meet the length and angle requirements are qualified products, otherwise they are scrapped.

5. The method for preparing a small-sized, complex, and irregular-shaped polycrystalline drawing die according to claim 4, characterized in that: The process also includes step S9, mold sleeve inlaying, in which the fine-grain polycrystalline mold core that has passed the inspection is mold sleeve inlaid.

Images