JPH0448526B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention provides wire rods and rods made of metals and alloys,
This invention relates to a die for drawing a pipe material or the like as a material to be drawn. FIG. 1 is a schematic cross-sectional view of a general drawing die (hereinafter simply referred to as a die). That is, in the figure, 1 is a case, and the die body 2 is integrally fitted inside the case 1. A drawing hole 3 is bored in the center of the die body 2 in the axial direction, through which the material to be drawn is reduced in diameter and passed through. On the inner surface of the extraction hole 3,
a tapered approach portion 3a whose inner diameter is gradually reduced from the input side to the output side of the material to be drawn;
Bearing part 3a with the smallest inner diameter and parallel to the axis
A bearing part 3b having a minimum inner diameter and parallel to the axis, and a tapered relief part 3c having an inner diameter enlarged toward the exit side are formed. In addition, the approach part 3a, the bearing part 3b, and the relief part 3c
Some of them form a continuous cross-sectional curve.
In addition, in the explanation of the drawings below, symbols are omitted in the drawings for the pull-out hole 3, the approach part 3a, the bearing part 3b, and the relief part 3c. This is to avoid complication. The die having the above-mentioned structure is attached to the stand of a drawing device (not shown), and a material to be drawn whose tip is drawn is inserted into the drawing hole 3 of the attached die. By grasping and pulling out the mouth constricted portion that emerges from the exit side, the material to be drawn becomes an elongated material having an outer diameter corresponding to the inner diameter of the bearing portion 3b. Conventionally, tool steel and cemented carbide have been used as the material for the die body, but recently ceramics such as silicon nitride or silicon carbide have also been used. Although tool steel and cemented carbide have excellent strength, they have a problem with lubricity during drawing, and as shown in Fig. 2, if the lubricant film formed on the surface of the material 10 to be drawn breaks, the approach Bearing part 3 from near the boundary between part 3a and bearing part 3b
Scratches x due to seizure and wear occur over b.
This has the disadvantage that the surface quality of the material 10 to be drawn is deteriorated. On the other hand, ceramic has excellent seizure resistance and abrasion resistance, but has excellent impact resistance, but has drawbacks in impact resistance, strength, etc., and as shown in FIG. There was a drawback that a crack y occurred near the contact point with the drawn material 10, and this crack y damaged the surface of the drawn material 10. In view of the above-mentioned conventional circumstances, it is an object of the present invention to provide a drawing die that selects the advantages and disadvantages of a die body made of tool steel and cemented carbide and a die body made of ceramic. . The gist of the present invention, which is such a technical concept, is that the die body is divided into an entry half and an exit half at a position slightly before the material to be drawn enters and reaches the bearing part of the die body. The material of the input half body is tool steel or cemented carbide, the material of the output half body is ceramic, and the input half body and the output half body are integrally fitted into the case. It is characterized by the fact that According to the inventor's investigation, the reason why seizure/wear scratches x occur from the vicinity of the boundary between the approach part 3a and the bearing part 3b to the bearing part 3b is due to the lubricant film forming as the drawing process progresses from the entry side. This is because the lubricating film is torn due to the thinning of the lubricant film and the accumulation of frictional heat, machining heat, etc. from the entry side, and cracks y occur near the contact portion of the approach portion 3a with the material to be drawn 10. It was found that this is because this portion comes into contact with the material to be drawn 10 first, and thus receives strong die surface pressure and impact force. Therefore, the idea of the present invention is to apply tool steel or cemented carbide with excellent strength to the parts that receive strong die surface pressure and impact force, and apply ceramics with excellent lubricity to the parts where large frictional resistance acts. In this way, we have attempted to solve the above-mentioned conventional problems by making good use of the characteristics of tool steel, cemented carbide, and ceramic. Next, examples of the present invention will be described. FIG. 4 is a sectional view of the die according to the first embodiment of the present invention. In the figure, 5 is the entry half of the die main body 4, and 6 is the exit half of the die main body 4. The entry half 5 and the exit half 6 are perpendicular to the axis at a position slightly before the material to be drawn 10 enters and reaches the bearing part 3b of the die body 4 (position near the bearing part 3b of the approach part 3a). They are butted together at a bonding surface 7. Note that this joint portion corresponds to just before the entry side of the position where ring wear, known as die flaws, occurs. The material of the entry half 5 is tool steel or cemented carbide. In the case of the entry half 5 made of tool steel, the inner surface of the pull-out hole 3 is preferably chrome plated or the like. As the cemented carbide forming the entry half 5, WC-Co type cemented carbide is often used. The material of the output half body 6 is ceramic. As ceramics, silicon nitride-based and silicon carbide-based ones are often used. The entry half 5 and the exit half 6 are
At the same time, it is shrink-fitted into the case 1 or integrated with a strong adhesive and press-fitted into the case 1 to form a die. FIG. 5 is a sectional view of a die according to a second embodiment of the present invention. The die body 4' of the second embodiment differs from the die body 4 of the first embodiment in that the joining surface 7' between the entry half 5' and the exit half 6' is tapered. . Preferably, the angle formed by the tapered coupling surface 7' with respect to the axis is 70 to 85 degrees. If the angle is less than 70°, the strength of the entry half 5' may become difficult to withstand the pulling force. By making the joining surface 7' between the entry half 5' and the exit half 6' into a tapered shape, the joining between the two becomes stable and there is no risk of misalignment between them.
Further, the propagation of the impact force acting on the inlet half 5' to the outlet half 6' at the time of withdrawal is alleviated. FIG. 6 is a sectional view of a die according to a third embodiment of the present invention. The die body 4'' of the third embodiment differs from the die body 4' of the second embodiment in that the tapered joining surface 7'' between the entry half 5" and the exit half 6" is along the outer periphery. , a ring 8 made of fake synthetic resin or synthetic rubber is inserted. In this way, most of the impact force acting on the entry half body 5'' when pulled out is absorbed by the ring 8, and the propagation of the impact force to the exit side half body 6'' is further alleviated. The die according to the present invention has the above-described configuration, and the inventor applied it to drawing wire and tested its effectiveness.The results will be explained in comparison with a conventional die. Conditions for wire rod drawing] Test material: Cu plated steel wire (TS80Kg/mm ^2nd class) Drawing method: Single pot wire drawing Drawing speed: 100m/min Lubrication method: Oil lubrication Processing rate: Conditions 4.2〓mm→3.9〓 mm (section reduction rate≒
14%) Drawing force: 360Kgf The results of drawing the wire rod under the above conditions were as shown in Table 1.

[Table] As shown in Table 1, the die of the present invention was able to maintain a life approximately 3 to 7 times longer than the conventional die when drawing wire rods. The die according to the present invention takes into account the advantages and disadvantages of tool steel, cemented carbide, and ceramic, and uses tool steel with excellent strength or super The die body is made of hard metal and ceramic is used in the areas where large frictional resistance is applied, which dramatically increases the useful life of the die and improves the efficiency of drawing operations. It has great effects, such as reducing the number of units and producing products with excellent surface properties.

[Brief explanation of drawings]

Figures 1 to 3 explain conventional drawing dies, with Figure 1 being a schematic cross-sectional view of a general die, and Figure 2 being a die body made of tool steel or cemented carbide. FIG. 3 is a cross-sectional view of the drawing process using a die using a die body made of ceramic, and FIGS. 4 to 6 illustrate the drawing die according to the present invention. FIG. 4 is a sectional view of the drawing process using the die of the first embodiment, FIG. 5 is a sectional view of the drawing process using the die of the second embodiment, and FIG. 6 is a sectional view of the die of the third embodiment. It is a schematic cross-sectional view. 1...Case, 2...Die body, 3...Drawing hole,
4, 4', 4''...Dice body for the die of the present invention,
5, 5', 5''...Inlet half body, 6,6', 6''...Output half body, 10...Material to be drawn.

Claims (1)

[Claims] 1 The die body is divided into an entry half and an exit half at a position slightly before the material to be drawn enters and reaches the bearing part of the die body, and the material of the input half is A drawing die characterized in that the die is made of steel or cemented carbide, the material of the exit half is ceramic, and the input half and exit half are integrally fitted into a case.