Wire drawing dies

Abstract

This wire drawing die comprises: a blank that serves as an abrasion resistant member provided with a die hole for drawing a wire material; and a die case for holding the blank. The blank has a higher thermal conductivity than the die case. The blank has, in the drawing direction, an upstream-side end surface and a downstream-side end surface. The die hole is provided between the upstream-side end surface and the downstream-side end surface. The downstream-side end surface is exposed from the die case.

Description

[Technical Field]

[0001] The present disclosure relates to a wire drawing die. This application claims priority to Japanese Patent Application No. 2021-080723, filed on May 12, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0002] A conventional wire drawing die is disclosed, for example, in Japanese Patent Laid-Open Publication No. 9-108726 (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-108726 Summary of the Invention

[0004] The wire drawing die of the present disclosure comprises a wear-resistant member having a die hole for drawing wire material, and a die case supporting the wear-resistant member, wherein the wear-resistant member has a higher thermal conductivity than the die case, the wear-resistant member has an upstream end face and a downstream end face in the wire drawing direction, the die hole is provided between the upstream end face and the downstream end face, and the downstream end face is exposed from the die case. [Brief explanation of the drawings]

[0005] [Figure 1] FIG. 1 is a plan view of a wire drawing die 100 according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the wire drawing die 100 taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing in detail the inner shape of the die hole 103 formed in the blank 120 in FIG. [Figure 4] FIG. 4 is a plan view of a lid 200 attached to the wire drawing die 100 according to an embodiment. [Figure 5] FIG. 5 is a cross-sectional view of the lid 200 taken along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view showing the wire drawing die 100 with the lid 200 attached thereto and a wire drawing method using the same. [Figure 7] FIG. 7 is a cross-sectional view showing the path of heat diffusion in the wire drawing die 100 with the lid 200 attached. [Figure 8] FIG. 8 is a cross-sectional view of a conventional wire drawing die 100. DETAILED DESCRIPTION OF THE INVENTION

[0006] [Problem to be solved by this disclosure] With conventional wire drawing dies, it has been difficult to sufficiently dissipate the heat generated during the wire drawing process.

[0007] [Description of the embodiments of the present disclosure] First, embodiments of the present disclosure will be listed and described.

[0008] The wire drawing die of the present disclosure comprises a wear-resistant member having a die hole for drawing wire material, and a die case supporting the wear-resistant member, wherein the wear-resistant member has a higher thermal conductivity than the die case, the wear-resistant member has an upstream end face and a downstream end face in the wire drawing direction, the die hole is provided between the upstream end face and the downstream end face, and the downstream end face is exposed from the die case.

[0009] In a wire drawing die configured in this manner, the thermal conductivity of the wear-resistant member is higher than that of the die case, and the downstream end face of the wear-resistant member is exposed from the die case, allowing heat to be diffused from the downstream end face, thereby enabling sufficient dissipation of heat generated during the wire drawing process.

[0010] Preferably, the wire drawing die further includes a lid having a through hole through which the wire can pass, the lid having a heat dissipation member having a through hole and in contact with the wear-resistant member, and a support member supporting the heat dissipation member, the heat dissipation member having a higher thermal conductivity than the support member.

[0011] In this case, the heat dissipating member is in contact with the wear resistant member, so that the heat of the wear resistant member can be efficiently transferred to the heat dissipating member.

[0012] Preferably, the heat dissipation member contains at least one material selected from the group consisting of diamond, CBN, and composite materials containing diamond or CBN.

[0013] In this case, the heat dissipation member has a particularly high thermal conductivity, and therefore the heat dissipation member can dissipate heat efficiently.

[0014] Preferably, the support member is made of at least one element selected from the group consisting of copper, silver, tungsten and molybdenum, or an alloy containing such an element, or a ceramic material or a composite of the ceramic material and a metal.

[0015] In this case, the strength of the support member is increased. Preferably, the heat dissipation member and the support member are joined together by brazing or by screwing.

[0016] In this case, the heat dissipating member and the supporting member are firmly joined by brazing or screws, which prevents the heat dissipating member from falling off the supporting member.

[0017] Preferably, a plating layer is provided on the joint surface between the heat dissipation member and the support member. In this case, the heat dissipating member and the support member are firmly joined at the joint surfaces between the heat dissipating member and the support member.

[0018] Heat generated in the processing area of a typical wire drawing die is transferred and dissipated in the following order: blank (diamond), mounting material (NiCu or Cu-based alloy), SUS case, and exterior (lubricant, etc.).

[0019] To improve heat dissipation, there are wire drawing dies that have holes in the stainless steel case or the like through which coolant passes, and through which cooling water or coolant flows to dissipate heat.

[0020] In typical wire drawing dies, the mounting material has a thermal conductivity of several hundred watts, which is inferior to the diamond blank material, which has a thermal conductivity of 1,500 watts, making it less heat-dissipating. This causes the temperature of the mounting material to rise, making it difficult for the blank to dissipate heat.

[0021] Furthermore, the mounting material is surrounded by a stainless steel case, which has a thermal conductivity of just over 10 W and poor heat dissipation performance, so the temperature of the mounting material is also likely to rise.

[0022] This can cause wire drawing problems such as high temperatures near the die holes, heat reaction wear, and the loss of the lubricant film.

[0023] Preferably, the diameter D of the bearing portion of the die hole is 10 μm or more and 1.0 mm or less, since this range is expected to maximize the life of the wire drawing die.

[0024] The length L of the bearing portion of the die hole is between 20% D and 100% D. This range is expected to maximize the life of the wire drawing die. 20% D means 20% of D.

[0025] [Details of the embodiments of the present disclosure] Fig. 1 is a plan view of a wire drawing die 100 according to an embodiment. As shown in Fig. 1, the wire drawing die 100 has a die case 110 and a blank 120 as a wear-resistant member supported by the die case 110. A die hole 103 is formed in the blank 120 located at the center. In this embodiment, the die hole 103 is round, but the die hole 103 may also be rectangular.

[0026] The blank 120 is made of a material having high wear resistance, such as diamond, CBN, cemented carbide, etc. A mount material such as a Ni alloy or Cu alloy is provided between the blank 120 and the die case 110.

[0027] Fig. 2 is a cross-sectional view of the wire drawing die 100 taken along line II-II in Fig. 1. As shown in Fig. 2, a blank 120 is embedded in the center of a die case 110 having a rectangular cross section.

[0028] A wire rod is inserted into a die hole 103 formed in a blank 120 in the direction indicated by arrow 100a. The wire rod comes into contact with the inner surface of the die hole 103 and is subjected to diameter reduction processing by the blank 120. The blank 120 has an upstream end face 121 located upstream of the wire drawing direction indicated by the arrow and a downstream end face 122 located downstream.

[0029] The die case 110 has a first surface 101 located upstream in the wire insertion direction indicated by arrow 100a, and a second surface 102 opposite to the first surface 101. A blank 120 is positioned between the first surface 101 and the second surface 102.

[0030] Figure 3 is a cross-sectional view showing in detail the inner shape of the die hole 103 formed in the blank 120 in Figure 2. As shown in Figure 3, the die hole 103 has, from the upstream side, a bell portion 1a, an approach portion 1b, a reduction portion 1c, a bearing portion 1d, a back relief portion 1e, and an exit portion 1f.

[0031] The diameter of the die hole 103 is smallest at the bearing portion 1d. The wire is plastically processed by the bearing portion 1d. The inner diameter of the bearing portion 1d is determined based on the diameter of the wire after processing.

[0032] The wire drawing die 100 includes a blank 120 as a wear-resistant member having a die hole 103 for drawing a wire rod, and a die case 110 that supports the blank 120. The blank 120 has a higher thermal conductivity than the die case 110.

[0033] The blank 120 has an upstream end face 121 and a downstream end face 122 in the wire drawing direction, and a die hole 103 is provided between the upstream end face 121 and the downstream end face 122, with the downstream end face 122 exposed from the die case 110.

[0034] 4 is a plan view of a lid 200 attached to a wire drawing die 100 according to an embodiment. The wire drawing die 100 further includes a lid 200 having a through hole 203 through which a wire can pass. The lid 200 has a heat dissipation member 220 that contacts the blank 120 and has the through hole 203 formed therein, and a support member 210 that supports the heat dissipation member 220, and the heat dissipation member 220 has a higher thermal conductivity than the support member 210.

[0035] The heat dissipation member 220 includes at least one selected from the group consisting of diamond, CBN, and composite materials containing diamond or CBN. The support member 210 is made of, for example, at least one element selected from the group consisting of copper, silver, tungsten, and molybdenum, or an alloy containing said element, or a ceramic material, or a composite of said ceramic material and a metal.

[0036] Fig. 5 is a cross-sectional view of the lid 200 taken along line VV in Fig. 4. As shown in Fig. 5, the lid 200 has a first surface 201 located upstream in the wiredrawing direction and a second surface 202 located downstream in the wiredrawing direction.

[0037] The heat dissipation member 220 is exposed from the first surface 201. The through-hole 203 of the heat dissipation member 220 and the through-hole 204 of the support member 210 are in communication with each other.

[0038] The heat dissipation member 220 and the support member 210 may be joined together by brazing or by screwing.

[0039] A plating layer may be provided on the bonding surface between the heat dissipation member 220 and the support member 210. In this case, the bonding strength between the heat dissipation member 220 and the support member 210 increases.

[0040] 6 is a cross-sectional view showing the wire drawing die 100 with the lid 200 attached and a wire drawing method using the same. As shown in Fig. 6, the first surface 201 of the lid 200 is attached to the second surface 102 of the wire drawing die 100. The center of the die hole 103 and the centers of the through holes 203 and 204 are aligned.

[0041] During the wire drawing process, the wire 1 flows in the direction indicated by the arrow 100a. At this time, the wire 1 comes into contact with the bearing portion 1d, and the diameter of the wire 1 is reduced.

[0042] 7 is a cross-sectional view showing the path of heat diffusion in the wire drawing die 100 to which the lid 200 is attached. As shown in FIG. 7, heat is generated when the bearing portion 1d comes into contact with the wire 1. This heat is transferred from the blank 120 to the heat dissipation member 220 as shown by arrow 10. This makes it possible to prevent heat from accumulating in the blank 120.

[0043] A plate-shaped heat dissipation member 220 made of a material with high thermal conductivity is provided below the diamond blank 120 so as to be in contact with the blank 120. A support member 210 serving as a second member with high thermal conductivity is provided below and around the heat dissipation member 220 so as to be in contact with the heat dissipation member 220. A die case 110 serving as a third member with high thermal conductivity is provided above the support member 210. The blank 120 and heat dissipation member 220 are sandwiched and surrounded by the die case 110 and support member 210.

[0044] For example, the thermal conductivity can be improved by using diamond for the first member and a material such as CuW for the second and third members, which allows heat to be dissipated to the outside via the blank 120, the diamond (heat dissipation member 220), and the CuW (support member 210).

[0045] By using diamond for the heat dissipation member 220 on the lower side of the blank 120, which becomes the hottest, the support member 210 functions as a heat sink, making it possible to quickly dissipate heat.

[0046] Furthermore, using CuW for the heat dissipation member 220, the support member 210 around the blank 120, and the die case 110 provides excellent heat dissipation to the outside. The first to third members are reusable, which is also advantageous in terms of cost.

[0047] Diamond is a material with the best thermal conductivity. By using diamond as the heat dissipation member 220 (heat sink) to directly cool the blank 120, it is possible to quickly dissipate the heat generated during wire drawing to the outside. Furthermore, by using CuW for the support member 210 that supports the heat dissipation member 220, heat dissipation performance is further improved.

[0048] Although the embodiment has been described above, the embodiment shown here can be modified in various ways. For example, in the embodiment, the blank 120 and the heat dissipation member 220 are in contact with each other, but the blank 120 may be in contact with the refrigerant without providing the lid 200 and the heat dissipation member 220.

[0049] In the embodiment, the lid 200 is configured to be detachable from the wire drawing die 100, but the lid 200 may be configured to be fixed to the wire drawing die 100.

[0050] Example 1 [Heat sink die performance evaluation] To confirm the performance of the heat sink die, a die with the following specifications was prepared and evaluated.

[0051] (Dice specifications) A. Heat sink die (see Figures 1 to 7) B. Normal die (having the shape of FIG. 8. No lid 200 is provided. The blank 120 is not exposed from the second surface 102.) Die shape (both Die A and Die B are the same) Reduction: 13 degrees Diameter D of the die bearing part 1d: 80.00 μm (reduction rate set to 16%) 30% of the axial length L:D of the bearing part 1d The axial length of the bearing portion 1d was determined by defining the area of the bearing portion 1d within 1.022D of the minimum diameter D of the bearing portion 1d.

[0052] (Wire drawing conditions) Wire rod: SUS316L Linear speed: 500m / min Lubrication: oil-based Wire drawing distance: 30km (Lifespan judgment criteria) The wire is judged to have reached the end of its life when its surface roughness after processing is Ra = 40 nm or more (the point at which glare appears on the wire). Glitter (wire scratch) is also called shining wire. When light hits a scratch on the wire surface or the edge of the wire (a point where the roundness has deteriorated), the light is diffusely reflected, causing the wire to glare, hence the name glitter.

[0053] (Surface roughness measurement conditions) Measuring device: Olympus MEASURING LASER MICROCOPE OLS4000 Image size (pixels): 1024 x 1024 Image size: 258×258μm Scanning mode: XYZ high precision + color Objective lens: MPLAPONLEXT x 100 DIC: Off Zoom: x1 Measurement range: 40 μm Measurement direction: Circumferential direction of the wire (rotated 90 degrees from the wire drawing direction) Measurement locations: 10 locations within a range of ±20 μm from the top of the wire Cutoff: 8 μm The evaluation results are shown in Table 1.

[0054] [Table 1]

[0055] For sample B, which uses a standard die, the wire diameter decreases as the drawing distance increases, and at the 30 km mark, the wire diameter is 0.09 μm smaller than the initial diameter. This is thought to be due to ring wear progressing on the inner surface of the die, causing the worn edges to cut the wire. Additionally, the drawing force increased from an initial value of 154 cN to 200 cN at the 30 km mark. This is thought to be due to the die cutting the wire due to ring wear. As a result, the wire surface roughness also deteriorated, and at the 20 km mark, a glare appeared on the wire, indicating the end of its life. Ultimately, the surface roughness deteriorated to 44 nm at the 30 km mark.

[0056] The heat sink die for sample A improved heat dissipation and suppressed thermal reaction wear, reducing the increase in drawing force to about one-third of that of a standard die and minimizing the impact of increased drawing force due to ring wear. As a result, wire diameter change also increased by 0.09 μm with the standard die, but with the heat sink die it increased by one-third to 0.03 μm. Furthermore, wire surface roughness was improved, and while the standard die showed signs of glazing at the 20 km mark, the heat sink die reached the 30 km mark, achieving a lifespan 1.5 times longer.

[0057] Furthermore, dies with sample numbers 1A to 5B were prepared in which the diameter D and length L of the bearing portion 1d were varied.

[0058] [Table 2]

[0059] Samples with a sample number ending in "A" have the shapes shown in FIGS. 1 to 7, and sample numbers with a sample number ending in "B" have the shape shown in FIG.

[0060] These were tested under the same conditions as samples A and B to determine their lifespan. The area reduction rate was set to 15% for all samples. The results are shown in Table 2.

[0061] From Tables 1 and 2, it is clear that the structures shown in FIGS. 1 to 7 have a longer lifespan than the structure shown in FIG.

[0062] The embodiments and examples disclosed herein are illustrative in all respects and should not be considered limiting. The scope of the present invention is defined by the claims, not by the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope thereof. [Explanation of symbols]

[0063] 1 wire rod, 1a bell portion, 1b approach portion, 1c reduction portion, 1d bearing portion, 1e back relief portion, 1f exit portion, 10,100a arrow, 100 wire drawing die, 101,201 first surface, 102,202 second surface, 103 die hole, 110 die case, 120 blank, 121 upstream end surface, 122 downstream end surface, 200 lid, 203,204 through hole, 210 support member, 220 heat dissipation member.

Claims

1. a wear-resistant member provided with a die hole for drawing the wire; a die case supporting the wear-resistant member, the wear-resistant member has a higher thermal conductivity than the die case; the wear-resistant member has an upstream end face and a downstream end face in a wiredrawing direction, the die hole is provided between the upstream end face and the downstream end face, and the downstream end face is a wiredrawing die exposed from the die case, the wire drawing die further includes a lid having a through hole through which a wire can pass, the lid having a heat dissipation member provided with the through hole and in contact with the wear-resistant member, and a support member supporting the heat dissipation member, the heat dissipation member having a higher thermal conductivity than the support member, The heat dissipation member of the wire drawing die comprises at least one material selected from the group consisting of diamond, CBN, and composite materials containing diamond or CBN.

2. The support member is 2. The wire drawing die according to claim 1, comprising at least one element selected from the group consisting of copper, silver, tungsten, and molybdenum, or an alloy containing said element, or a ceramic material or a composite of said ceramic material and a metal.

3. 3. The wire drawing die according to claim 1, wherein the heat dissipation member and the support member are joined together by brazing or by screws.

4. The wire drawing die according to claim 1 , wherein a plating layer is provided on a joint surface between the heat dissipation member and the support member.

5. 5. The wire drawing die according to claim 1, wherein a diameter D of the bearing portion of the die hole is 10 μm or more and 1.0 mm or less.

6. 6. The wire drawing die according to claim 1, wherein the length L of the bearing portion of the die hole is not less than 20% D and not more than 100% D.

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