JPS633681B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tapered bar, in which a tapered portion is formed on a bar-shaped material using three or more rolling rolls.

When forming a tapered bar such as a wire for forming a tapered coil spring, cutting is poor in material yield, rotary swaging is accompanied by noise and vibration, and in any case, productivity is poor. In order to solve these problems, it is conceivable to provide a plurality of rolling rolls each having a conical rotating surface so as to be able to move toward and away from each other, and to form a tapered portion using these rolls.

On the other hand, in the case of tapered coil spring strands, the surface of the strands after tapering must be in good condition from the point of view of fatigue life, and the processing temperature is limited (mainly to avoid decarburization, For example, in the case of spring steel with a high Si content (below 800°C), the machining load must be increased, and the outer diameter is generally small (for example, the outer diameter of the material is 12 mm, the minimum diameter of the tapered part is 8 mm).

When using the above-mentioned rolling rolls, if two rolls 1 and 1 are used as shown in FIG. This is not desirable from a quality standpoint as there is a risk of Moreover, if the number of rolls is three, the adverse effects caused by the Mannesmann effect can be avoided, but if the axes of the rolls 2 are inclined with respect to the axis of the material a, as illustrated in FIG. Since the angle is relatively large, there is a large circumferential speed difference between the large diameter part and the small diameter part of the conical surface that is pressed against the material, which tends to cause defects such as twisting of the material and surface peeling. Furthermore, when the roll axis is set parallel to the material axis as illustrated in Fig. 3, the roll diameter of the rolls 3 must be made smaller than in the case shown in Fig. 2 in order to avoid mutual interference. (The roll diameter R and the material diameter r are R/r6.46), and the roll shaft diameter cannot be made large, resulting in a decrease in load carrying capacity. Therefore, any of the above methods is unsuitable for forming strands for tapered coil springs.

The present invention was made under the above circumstances, and its purpose is to have a good material yield, excellent productivity, a good processed surface, and to be applicable to small diameter materials, especially for taper coils. It is an object of the present invention to provide a method for manufacturing a tapered bar suitable for spring forming wire.

Hereinafter, the present invention will be explained with reference to the drawings. In Fig. 4, a rod-shaped member 1 having an approximately circular cross section
0 is supported so as to be rotatable around the axis and movable in the axial direction, and is provided with traction force in the axial direction. Three rolling rolls 11, 12, and 13 are arranged at intervals in the circumferential direction on the outer circumference of the bar-shaped material 10. These rolling rolls 11, 12, 13
is an axis 11a parallel to the axis 10a of the rod-shaped material 10,
It is supported so as to be rotatable around the rods 12a and 13a, respectively, and to be able to move toward and away from the rod-shaped member 10. Further, the rolling rolls 11, 12, 13 have conical rotating surfaces 11b, 12b, 1 formed on their respective outer peripheries.
3b, and these rotating surfaces 11
b, 12b, and 13b are pressed against the outer periphery of the rod-shaped material 10 so that each large diameter side is located on the front side in the direction of movement of the rod-shaped material 10. In the illustrated example, the first,
The second rolling rolls 11 and 12 have approximately the same outer diameter, and the third rolling roll 13, which is formed to have a smaller diameter than these rolls, is in rolling contact with a back-up roll 14 having a larger diameter.

By driving the first and second rolling rolls 11, 12 and the back-up roll 14 to rotate in the directions of the arrows, and moving them in a direction that separates them from each other in relation to the amount of axial movement of the rod-shaped material 10, A desired taper portion is formed in the rod-shaped material 10.

According to the above configuration, the rolling rolls 11, 12, 1
3 are arranged parallel to the axis of the rod-shaped member 10, each of the conical rotation surfaces 11b, 12b, 13
The apex angle of b may be relatively small, and the difference in circumferential speed between the large diameter part and the small diameter part at the pressure contact part with the bar 10 is small, so there is no possibility of twisting or surface peeling of the bar 10. A good machined surface can be obtained. Further, since the third rolling roll 13 is formed to have a small diameter and is brought into rolling contact with the back-up roll 14, the first and second rolling rolls 11,
12 and the backup roll 14 can be formed to have a large diameter without interfering with each other. Therefore, each of these rolls 11, 12, and 14 can have a large shaft diameter, so it can be driven with a large torque, and the load resistance can be improved, allowing efficient taper processing even at low processing temperatures. In combination with a good machined surface, the fatigue life of the tapered portion can be improved. Furthermore, by making the third roll 13 small in diameter, the gaps formed between the respective rolling rolls 11, 12, 13 can be made small, so that even small-diameter rod-shaped materials can be tapered. Moreover, since the first and second rolling rolls 11 and 12 have large diameters, the sizes of these rolls can be appropriately set according to the total number of rolling rolls, diameter ratio, shape, rolling amount, etc. Good biting can be achieved, and there is no possibility of failure of rolling due to poor biting, which would occur if all the rolling rolls 11, 12, 13 were made small in diameter.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, the rolling rolls 11, 12, 1
In addition to 3, a desired number of rolling rolls may be provided, and the number and arrangement of large-diameter rolls and small-diameter rolls can be set as appropriate. The number may be singular or plural. Also,
The rolling rolls may have mutually different outer diameters, and in cases where the reduction in area at the tapered portion is small and the machining torque may be small, a part of the rolling roll is driven to rotate relative to the rod-shaped material 10. You can do it like this. The back-up roll that comes into rolling contact with the driven rolling roll may have a small diameter. Furthermore, each rotational surface of the rolling rolls rolled into the bar-shaped material 10 may be an approximate conical surface instead of a correct conical surface, and the rotational axes 11a, 12
a and 13a may each be inclined at a slight angle with respect to the axis 10a of the rod-shaped member 10.

In the present invention, as described above, the rolling roll is composed of a large-diameter roll and a small-diameter roll, and the small-diameter roll is brought into rolling contact with a back-up roll, so that the material yield is significantly better than in the cutting method. In addition, it is superior in productivity compared to rotary swage methods and the like. In addition, some of the rolling rolls, back-up rolls, etc. can be made to have a large diameter, so that the rod-shaped material can be caught well, and even if the rotational axes of the rolling rolls are approximately parallel to each other, the load bearing capacity can be improved. Since the machining temperature can be low, and the peripheral speed difference of the rotating surface at the contact part with the bar material is small, a good machined surface can be obtained.Furthermore, it can be applied to small diameter bar materials. Suitable for tapering wires for tapered coil springs.

[Brief explanation of the drawing]

FIG. 1 is a perspective view for explaining two-roll rolling, FIGS. 2 and 3 are perspective views for explaining three-roll rolling, and FIG. 4 is a schematic illustration of an embodiment of an apparatus to which the present invention is applied. FIG. 10... Bar-shaped material, 11, 12, 13... Roll, 11a, 12a, 13a... Rotation axis, 1
1b, 12b, 13b... rotating surface, 14... back up roll.

Claims (1)

[Claims] 1 At least three rolling rolls having a conical rotating surface formed on the outer periphery, the rotational axes of which are substantially parallel to each other, and supported so as to be able to approach and separate from each other, a rod-shaped roll that is inserted into the gap between these rolls. When the tapered portion is formed by pressing the rotating surface onto the material, the rolling roll is composed of a large-diameter roll and a small-diameter roll, and the small-diameter roll is brought into rolling contact with a back-up roll. How to manufacture a taper bar.