JPS59104213A - Method for cold drawing - Google Patents

Abstract

PURPOSE:To reduce a bend of drawn material and a burden to be form in the succeeding straightening stage by supporting a die so that its die hole is freely tiltable with respect to the drawing direction. CONSTITUTION:An annular supporting member 6 is attached concentrically with the axial center (a) to the rear face of the die 3. A bearing member 9 having an annular recess 10 is fitted to the inside of a die holder 2. The member 6 is fitted to the recess 10, and an incompressible fluid 11 is filled in a space sealed by an O-ring 8. The drawing is performed by pulling the pointing part 1a of a drawing material 1 with the aid of a chuck 4. An ununiformity of resistance in the circumferential direction due to a bend, etc. of the material 1 is relaxed by the tilting of die 3 which is supported freely by the fluid 11 in the recess 10, to reduce remarkably a bend of drawing material 1. Accordingly, a straightening operation in the succeeding stage is made easy, and the life of die is extended.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cold drawing method for various metal tubes, rods, and wire rods, and more specifically, the present invention relates to a cold drawing method for various metal tubes, rods, and wire rods, and more specifically,
The present invention relates to a method for obtaining drawn material that is easy to straighten.

For such cold drawing, for example, in the case of a pipe, a die holder <2) vc die (3) is installed on the drawing fin as shown in Fig. 1, and the mouth of the pipe (1) is inserted through the die (3). However, in this type of cold drawing, bending of the drawn material is practically unavoidable.

This bending occurs even when the most common manufacturing process involves heat treatment to obtain the desired properties after cold drawing. A serious problem arises when the bend is directly sent to straightener processing without heat treatment after cold drawing. In other words, if the heat treatment after cold drawing is omitted, the degree of bending after drawing will be directly related to the processing load in the 9-way process.

Therefore, the music after drawing must be made as small as possible.

Conventionally, as a countermeasure against such bending of the drawn material, a support mechanism using bolts was adopted as a means for attaching the die holder (2) to the die stand (not shown), and the die holder (2) was appropriately tilted δ. Generally, drawing is carried out using However, this can be obtained by repeatedly carrying out the drawing process, visually measuring the 9 amounts and 9 directions of the curvature of the drawing material, and adjusting the inclination of the die holder based on that. The method of making the curve 9 of the drawn material closer to a straight shape relies heavily on the intuition of the worker's experience and skill, so it is not possible to always expect a stable effect due to the influence of the skill level of the worker. do not have.

The present invention aims to provide a drawing method that is not dependent on the skill level of the worker and can always produce a stable effect as a countermeasure against curves. The purpose is to reduce the force exerted on the die from the material during cold drawing by supporting it so that it can tilt freely, and to prevent bending as much as possible.

FIG. 2 is a vertical cross-sectional side view (8) showing a specific example of the die support mechanism of an apparatus for carrying out the drawing method of the present invention. In the figure, a support device (5) is interposed between the die (3) and the die holder (2) to prevent tilting of the die. The support device (5) has a ring-shaped support member (6) in contact with the die back surface (3a) and a ring-shaped receiver corresponding to the support member held in contact with the die holder (2) side.
9). The annular support member (6) has concave grooves (7) (7) on its inner and outer peripheral surfaces, each of which has an O-ring (or V-ring, U-ring, etc.) (8) ( 8) is fitted. This annular support member (6) I'i has a certain amount of space 1' at the opening height α0 which is continuous in the circumferential direction on the front side of the member (9). At the same time, the O rings (8) and (3) are in close contact with the inner surface of the recess, thereby defining a sealed space within the recess. This closed space contains, for example, hydraulic fluid, etc.
It is filled with a so-called incompressible fluid αη.

The die (3) equipped with such a support device (its central axis) can be tilted in any direction δ with respect to the drawing direction (A)vc. In other words, when a circumferentially uniform and axially symmetrical force (in the drawing direction) is applied to the die, the die does not tilt in the vt- direction, but maintains its normal posture (the drawing direction (8) and the die center axis (a) coincide). However, when an asymmetrical force acts on the axis, the die tilts. The non-pressure m-fluid αυ that is rarely present on the side where the force is twisted escapes around it, and the fluid on the axially symmetric side increases by that amount and pushes the die toward the front side, and as a result, force is applied to the die (3). The lopsided side will tilt in the direction of retreat.

If drawing is performed using the die (3) that is tiltably supported in this way, the direction of the die will be automatically adjusted by the force from the material during the drawing process, so the unbalanced force from the material will be effective. The reaction force from the die to the material is also significantly reduced, and as a result, the occurrence of 9 is effectively suppressed. It is. The reason why reducing the reaction force of the biased force on the material leads to prevention of bending has not yet been fully clarified, but it is probably due to the uniformity of the strain distribution in the drawing direction of the drawn material. This is thought to be due to the improvement in

In addition to the structure shown in FIG. 2, an example of a die support structure suitable for carrying out the method of the present invention is as shown in FIG. I can think of things. That is, there are guide rods (6) installed at appropriate intervals in the circumferential direction of the die support surface (2a) of the die holder (2), one guide hole α on the die (3) side through which the guide rods (6) are inserted, and each of the guide rods (i). ) is fitted onto the outside of the die (3) and the die holder (2) to bias the die (3) and the die holder (2) in the direction of separating δ from each other. The die (3) is automatically tilted in the same way as the one shown in FIG. 3, depending on the balance with the applied external force.

In the above structure, a cylindrical guide frame and a circumferential groove continuous in the circumferential direction may be used in place of the guide rod (6) and the guide hole α. Furthermore, if it is undesirable to directly drill the guide hole α3 in the die (3) due to reasons such as strength, an annular body as shown by the symbol (6) in FIG. What is necessary is to attach it and provide a guide hole therein.

Next, the implementation effects of the present invention will be explained by quantitative comparison.

5US816 steel 14fl$X1.4 Dragon tX40001
1jlt's w4 tube is used as the material, and this is 12 to fX 1
．． 2 snwt, and at this time, drawing was carried out using a die apparatus having the structure shown in FIG. 3 based on the method of the present invention, or using a conventional fixed die. Drawing was carried out for 20 pieces for each method.

FIG. 4 shows the results of measuring the curve length for each of the obtained drawn tubes, and shows the frequency of occurrence of each amount of curve for each of the 20 tubes. The amount of bending was measured by placing the pipe on a surface plate (G) as shown in FIG. 5, measuring the maximum amount of the gap, and using this as the maximum amount of bending.

According to Figure 4, the maximum amount in the conventional method is ! The average value of the amount of lll (illustration: 30.89, standard deviation): 5.14.
871+11, σ: 2.11111, which clearly shows a significant reduction.

In addition, the present inventor has realized that the method of the present invention can be applied not only to pipes, but also to pipes.
It has been confirmed that it is equally effective for rods and wires.

As stated above, although the cold drawing method of the present invention is extremely simple to implement, it is always stable and highly effective in preventing bending due to drawing.
This is particularly effective in reducing the burden of stripping when the strip is subjected to a manufacturing procedure in which it is subjected to stripping without heat treatment after cold drawing.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram schematically showing general cold drawing, Fig. 2 is a longitudinal cross-sectional side view showing the main structure of an apparatus suitable for implementing the drawing process of the present invention, and Fig. 3 is an explanatory diagram showing the drawing process of the present invention. Fig. 4 shows the results of investigating the bending of the drawn tube obtained by the method of the present invention and the conventional method. It is a figure explaining how to check the gap. In the figure, ■ = tube, 2: dice holder, 3: dice, 4:
Chuck, 5: Support device, 6: Annular support member, 7: Concave groove, 8: O-ring, 9: Receiver is member, 10: Mouth height, 11: Incompressible fluid, 12: Guide rod, 13: Guide hole , 14: Suppression spring applicant Sumitomo Metal Industries, Ltd. Figure 2 Figure 3 Figure 4 - Final bending force Figure 5

Claims (1)

[Claims] (1) A cold drawing method characterized in that cold drawing is carried out by supporting a die so that the die is tiltable with respect to the direction of the drawing head.