JPH04200919A - Hot extruding perforated die - Google Patents

Abstract

PURPOSE:To make a die thin in thickness, light in weight and low in cost by fixing the periphery of the die with cushioning material larger in linear expansion coefficient than a die case. CONSTITUTION:The cushioning material 3 between the outer periphery of each die body 1 and the die case 2 is formed by material large in linear expansion coefficient thickly in the circumferential direction of a die case 2. The cushioning material 3 is of copper alloy having a linear expansion coefficient 12-30X10<-6>/ deg.C. Further, the cushioning material 3 has an elliptical outer periphery and forms a doughnut-shaped shrinkage fitted part 3a to fix the die body 1 in the central part and when the cushioning material 3 is raised up to the extrusion temperature in an extruding time, the inside diameter 3a is set to be nearly the same dimension as the outside diameter of the die body 1. In this way, the ununiform compression stress acting on the die body 1 is dispersed to prevent the die from cracking and breaking.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a die used, for example, in hot extrusion processing of aluminum alloy, and in particular, a plurality of dies made of ceramic or cemented carbide in one die case. This invention relates to a multi-hole die for hot extrusion having a die body.

[Prior Art] For example, when extruding AQ-Cu-based high-strength aluminum alloy, etc., it is necessary to prevent surface defects on the extruded material while
In order to increase the extrusion speed, conventionally, a die is used in which the die body forming the bearing portion is made of fine ceramics or cemented carbide.

Conventionally, in this die, as shown in FIG.
A die body 5 constituting a bearing portion 6 is directly shrink-fitted and fixed to a die case 4 made of tool steel such as KD62 or 5KD61. In addition, in Fig. 3, the reference numeral 7
is a billet of aluminum alloy or the like that is hot extruded.

[Problems to be Solved by the Invention] However, the conventional multi-hole die for hot extrusion has the following problems because the die body 5 is shrink-fitted directly to the die case 4 as described above. Ta.

That is, during extrusion, the die is elastically deformed in an arc shape in the extrusion direction by the extrusion pressure applied via the billet 7, as shown in FIG. In the case of a multi-hole die, since the shrink-fit holes of the die body 5 are arranged circumferentially in the die case 4, the bending moment acting in the radial direction is greater than the bending moment acting in the circumferential direction of the die case 4. becomes larger. Therefore, the shrink-fit hole provided in the die case 4 is deformed from a circular shape to an oval shape that is elongated in the circumferential direction of the die case 4, as shown in FIG.
In FIG. 4, the broken line shows the shape of the shrink fit hole in the die case when the extrusion pressure is not applied, and the solid line shows the shape of the shrink fit hole in the die case when the extrusion pressure is applied.

Therefore, compressive stress acts on the die body 5, which is generally made of ceramic or carbide and has low bending strength, in the radial direction and tensile stress acts in the circumferential direction.
There was a problem in that the die body 5 was easily cracked or destroyed.

In addition, in order to prevent this, it is necessary to set the die body 5 to be quite thick (see Figure 3), approximately 1/2 or more of the extrusion diameter, to ensure sufficient strength.
There was also a problem that the weight of the die body 5 increased, leading to increased costs.

The present invention aims to solve such problems,
The purpose of the present invention is to provide a multi-hole die for hot extrusion that eliminates the risk of breakage of the die body due to extrusion pressure, allows the die body to be made thinner, and achieves weight reduction and cost reduction.

[Means for Solving the Problems] In order to achieve the object described above, the multi-hole die for hot extrusion of the present invention has a structure in which each die is The main body is attached to the die case, and the cushioning material is formed within the thickness in the circumferential direction of the die case.

[Function] In the multi-hole die for hot extrusion of the present invention described above, the cushioning material that fixes the periphery of each die body is formed so as to be within the thickness in the circumferential direction of the die case, and moreover, It has a coefficient of linear expansion larger than that of the case, so when it is heated to the extrusion temperature, it expands in the circumferential direction of the die case, alleviates the oval deformation of the shrink-fit hole, and acts on the die body. Since the stress caused by the bending is equalized and reduced, it is possible to prevent the die body, which has low bending strength, from breaking.

[Embodiments of the Invention] Hereinafter, a multi-hole die for hot extrusion as an embodiment of the present invention will be explained with reference to the drawings. Fig. 1 is a plan view thereof;
FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1. In addition,
In this example, a case will be described in which the present invention is applied to a multi-hole die for extruding aluminum alloy.

In Figures 1 and 2, 1 is a die body having a die hole 1b and constitutes a bearing part 1a, and 2 is a die body 1 with a 9
Four die cases are arranged on the circumference at 0° intervals, and 3 is a buffer material interposed between the outer periphery of each die body 1 and the die case 2; It is made of a material having a larger coefficient of linear expansion than the other material, and is formed within the thickness in the circumferential direction of the die case 2, as shown in FIG.

Here, the die body 1 is made of Si-, N-based ceramics or WC-based cemented carbide, and is formed into a cylindrical shape with a predetermined thickness, and the inner periphery of the central die hole 1b. A bearing portion 1a is formed on the surface.

In addition, tool steel such as 5KD62 is used for the die case 2, and a shrink fit hole for curing the buffer material 3 to which the die body 1 is fixed is placed on the circumference at a certain distance from the center. Four pieces 2a are formed at 90° intervals. This shrink fit hole 2a has the same oval shape as the outer shape of the cushioning material 3, and is designed to have approximately the same external dimensions as the cushioning material 3 when the die case 2 rises to the extrusion temperature. is formed.

Further, as the material of the buffer material 3, a copper alloy is used. When the die body 1 is made of ceramics, the linear expansion coefficient of the buffer material 3 is specified between 12 and 30×10'/'C, while when the die body 1 is made of carbide, the buffer The coefficient of linear expansion of the material 3 is defined to be between 9 and 30 x 10''/'C. Also, as mentioned above, the shape of the cushioning material 3 has an oval outer periphery, and a die body 1 in the center. It has a donut shape with a shrink fit part 3a for fixing it, and the inner diameter of the shrink fit part 3a is such that the cushioning material 3 reaches the extrusion temperature during extrusion.
It is set to have approximately the same dimension as the outer diameter of the die body 1 when raised.

Due to the double configuration, in the multi-hole die of this embodiment, the shrink-fit hole 2a of the die case 2 is further lengthened by the extrusion pressure applied through the billet 7 (see Fig. 3) during extrusion processing. Although it deforms into a circular shape, a copper alloy buffer material 3 having a coefficient of linear expansion larger than that of the die case 2 is expanded by the extrusion temperature, and is formed so as to be thicker on the circumferential side of the die case 2. Therefore, the amount of expansion in the circumferential direction is larger than that in the radial direction, the deformation of the die case 2 due to extrusion pressure is absorbed, and the uneven compressive stress distribution acting on the die body 1 is made uniform, and the compressive stress is reduced. This can reliably prevent cracking or destruction of the die body, which has low cracking strength.

In addition, although the said Example demonstrated the multi-hole die provided with four die bodies 1, this invention is not limited to this.

[Effects of the Invention] As detailed above, according to the multi-hole die for hot extrusion of the present invention, the cushioning material having a coefficient of linear expansion larger than that of the die case is arranged so as to be within the thickness in the circumferential direction of the die case. Since the periphery of each die body is fixed by this cushioning material, the deformation of the die case is selectively absorbed by the cushioning material, reducing the compressive stress acting on the die body by uniformly distributing it. This prevents the die body from cracking or breaking.

Therefore, it is no longer necessary to take measures to improve the strength of the die body in design, and a thin die body can be used, which has the effect of reducing the weight and cost of the multi-hole die.

[Brief explanation of the drawing]

Figures 1 and 2 show a multi-hole die for hot extrusion as an embodiment of the present invention. Figure 1 is a plan view thereof, and Figure 2 is a sectional view taken along the line ■-H in Figure 1. Fig. 3 is a sectional view showing the main parts of a conventional multi-hole die for hot extrusion and the state of elastic deformation during extrusion processing, and Fig. 4 shows the shrink fit of the die case during extrusion processing. It is a figure which shows the deformation state of. In the figure, 1 - die body, la - bearing part,]
b-Die hole, 2-Die case, 2a,-Shrink fit hole, 3
- Cushioning material, 3a - Shrink fit part. Patent applicant: Kobe Steel, Ltd.

Claims (1)

[Claims] In a multi-hole die for hot extrusion in which a plurality of die bodies constituting a bearing part are arranged circumferentially in a die case, each die body has a coefficient of linear expansion larger than that of the material of the die case. A multi-hole die for hot extrusion, characterized in that the die case is attached to the die case via a cushioning material, and the cushioning material is formed thickly in the circumferential direction of the die case.