JPH0126762B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tapered bar for a coil spring having a circular cross section.

When forming a material to form a coil spring into a tapered shape with an almost circular cross section, conventionally the material was cut or rotary swaged, but in the former case, the yield of the material was low. Unfortunately, the latter had problems in terms of productivity, vibration, noise, etc. Further, as shown in Fig. 1, grooves 2, 2 each having an arcuate cross section with a curvature that gradually increases and decreases in the circumferential direction are formed on the outer periphery of a pair of rolls 1, 1 whose rotational axes are parallel to each other with a predetermined interval. Two or more pilger rolls are used, or lip-shaped grooves 4, 4 are formed on the outer periphery of a pair of rolls 3, 3 whose rotational axes are parallel and can move toward and away from each other, as shown in Fig. 2. A combination of a lip-shaped roll and the above-mentioned pilger roll has been considered, but these rolls are not versatile, require a lot of work to adjust, and the taper length depends on the roll diameter. Furthermore, the roll itself, especially a roll with a nonlinear taper, has many drawbacks, such as being difficult and expensive to manufacture.

Although it is not used for manufacturing taper bars, there is known a rolling device having four rolls 5 arranged in a cross shape as shown in FIG. 3. The distance between each roll 5 is kept constant. Furthermore, arcuate grooves 6 having a radius of curvature that matches the cross-sectional shape of the product to be rolled are provided on the outer periphery of each roll 5, and circular grooves 6 formed in mutually opposing parts of these grooves 6 By inserting a material into the opening 7 and rolling it, a molded product having substantially the same cross-sectional shape as the opening 7 can be obtained. However, in this case, the distance between the rolls is constant and the purpose is to obtain a product with a circular cross section with an outer circumference that matches the radius of curvature of the grooves 6, so it is used only for straight bar products. was. Further, when the rolls 5 are used, if the area reduction rate from the raw material to the product is large, burrs are likely to occur in the gaps 8 between the rolls. Therefore, it is impossible to form the material into a tapered shape.

The present invention was made under the above circumstances, and its objectives are to provide a good material yield, easy setup adjustment, the ability to freely set the taper length, and both linear and nonlinear It is an object of the present invention to provide a method for manufacturing a taper bar having a circular cross section, which can be simply and easily formed into a taper, and can also be easily manufactured into a rolling roll.

Hereinafter, the present invention will be explained with reference to the drawings. In FIGS. 4 and 5, a pair of upper and lower lip-shaped rolls 10 facing the moving path a of the material,
10 are provided. These rolls 10,10
The rotary shafts 10a, 10a are horizontally supported so as to be movable towards and away from each other. Further, on the lower side of the rolls 10, 10, a pair of left and right lip-shaped rolls 11, 1 are provided.
1 (only one shown) is provided. These rolls 11, 11 are supported so that rotating shafts 11a, 11a (only one is shown) are perpendicular to each other so as to be able to approach and separate. Each roll 10, 11 has lip-shaped grooves 10b, 11b formed on its outer periphery. The lip-shaped rolls 10 and 11 constitute a preliminary roll group.

Further, below the rolls 11, 11, a pair of upper and lower first rolls 12, 12 and a pair of left and right second rolls 13, 13 are provided. 1st
Rotating shafts 12a, 12a of the rolls 12, 12 are horizontally supported so as to be movable toward and away from each other. The center axes of the rotation shafts 13a, 13a of the second rolls 13, 13 are located substantially on the same plane and perpendicular to the center axes of the rotation shafts 12a, 12a, and are supported so as to be movable toward and away from each other. These first rolls 12,1
2 and the second rolls 13, 13 are provided with circumferential grooves 14 formed on their outer peripheries. These grooves 1
4... has an arcuate cross section with a predetermined curvature (1/R), and each roll 12, 12 and 13, 1
Openings 14a having a substantially circular cross section are formed at mutually opposing portions of the openings 14a. The radius of curvature R of the groove 14 is the desired radius r of the rolled tapered part, as shown in an enlarged view in FIG.
It is formed larger.

Each of the rolls 10, 11, 12 and 13 is
All or part of these may be rotationally driven by an appropriate drive mechanism (not shown), or may be driven to rotate as the material moves.

The movement path a is provided with a means 15 for detecting the amount of movement of the material by rolling it into contact with the material without slipping, for example. This detection means 15 is configured to be able to generate an analog or digital signal corresponding to the amount of longitudinal movement of the material. This signal is guided to appropriate control means (not shown). This control means includes opposing rolls 10, 10, 11, 1
1, 12, 12 and 13, 13 according to preset conditions and the detection means 1.
It is configured such that it can be variably controlled according to the output signal of No. 5.

In the apparatus configured as described above, the material introduced along the moving path a first passes through the rolls 10,
10 in the vertical direction, and lip-shaped rolls 11, 11 in the horizontal direction,
Further, since the distance between the rolls 10, 10 and 11, 11 is variably controlled in relation to the amount of movement of the material, the rolls 10, 10 and 11, 11 are pre-rolled into a tapered shape with a substantially circular cross section. Then, the pre-rolled material is transferred to the first rolls 12, 12 and the second roll 1.
The rolls 12, 12 and 13, 13 are simultaneously pressed in the vertical and lateral directions by the rollers 3 and 13, and the distance between each roll is variable in relation to the amount of longitudinal movement of the portion of the material to be formed into a tapered shape. Since the bar is controlled, the roundness is rolled into a tapered bar with a circular cross section.

According to the above configuration, the material is rolled into a tapered shape by plastic working, so the material yield is substantially 100%. In addition, each roll 10, 11, 1
2 and 13 are grooves 10b and 11 formed on the outer periphery.
Since the cross-sectional shapes of b, 14, and 14 are constant, manufacturing is easy, and the length and slope of the tapered part can be set arbitrarily because the spacing between the rolls is variably controlled during taper forming. , both linear and nonlinear tapers can be easily formed, and setup adjustments can be easily performed. Furthermore, the first roll 1
2, 12 and each groove 14 of the second roll 13, 13
Since the radius of curvature R of ... is formed larger than the desired radius r of the formed taper part, the material does not protrude into the gap 16 between the rolls and cause burrs, and within the range of r<R. It can respond to changes in r and perform taper rolling. The tapered part formed in this way is a tapered bar A for coil springs shown in FIGS. 7 and 8.
Strictly speaking, the cross section is not a perfect circle, but the rolled tapered part b has a polygonal cross section that approximates a circle with each side bulging out in an arc shape. In this case, the radius at the part facing the gap 16 is slightly larger than the radius at the part facing the lower part of the groove 14, but the deviation is about 5% or less, and it is suitable for use as a wire for coil springs etc. There is no problem whatsoever.

Note that the present invention is not limited to the above embodiments. For example, the lip-shaped roll 1
Any one pair of rolls 0, 10 and 11, 11 may be omitted, or a well-known oval roll or flat roll may be used instead.

Further, the material inserted into the first rolls 12, 12 and the second rolls 13, 13 should preferably have a polygonal shape with a cross section approximated to a circle.
A plurality of sets of other roll mechanisms having the same configuration as the second rolls 2, 12 and the second rolls 13, 13 may be provided. Further, the first rolls 12, 12 and the second rolls 13, 13 are connected to rotating shafts 12a, 12a and 13.
a and 13a may be arranged so as to be located on different parallel planes. It goes without saying that various other changes and applications can be made within the scope of the gist of the present invention.

As described above, when rolling a rod-shaped material for a coil spring into a tapered shape, the present invention performs preliminary rolling by pressing the material in the radial direction with a group of preliminary rolls having circumferential grooves, and
A pair of first rolls having circumferential grooves having an arcuate cross section with a radius of curvature R larger than the desired outer diameter r of the tapered bar to be rolled on the outer periphery and whose rotational axes are parallel to each other; A pair of second rolls each having a circumferential groove having an arc-shaped cross section with a radius of curvature R larger than the desired outer diameter r of the tapered bar to be rolled, and whose rotational axes are perpendicular to both rotational axes of the first roll. Using rolls, the opposing roll spacing of the pair of first rolls and the rolling spacing of the pair of second rolls are determined in the longitudinal direction of the tapered portion of the material inserted into the mutually opposing portions of the groove, respectively. By variable control related to the amount of movement,
Pressing the first roll pair and the second roll pair simultaneously from both directions while changing the roll facing interval so that the cross-sectional shape of the tapered portion after rolling has a cross-sectional shape that approximates a circle with each side bulging in an arc shape. The tapered part is rolled at the same time. Therefore, the raw material is tapered by plastic working, and a good yield can be obtained, and the roll itself can be manufactured and set up easily.

The cross section of the tapered part formed by the first roll and the second roll is not a perfect circle but resembles a polygon, but when used as a wire for a coil spring, the tapered part is shaped like this. Regardless of the shape, it can exhibit substantially the same performance as a wire with a perfect circular cross section. Since the length and slope of the tapered portion of such irregular cross-sectional shape can be set arbitrarily, both linear and non-linear tapers can be easily formed. Furthermore, by appropriately setting the curvature of the groove, the occurrence of burrs can be effectively prevented.

[Brief explanation of drawings]

Figures 1, 2 and 3 are explanatory diagrams showing a conventional device, Figures 4 and 5 are schematic side views and front views showing an embodiment of the present invention, and Figure 6 is an enlarged view of the main parts. 7 is a plan view of the rolled taper bar, and FIG. 8 is a sectional view taken along the line - in FIG. 7. 12...first roll, 13...second roll, 14...
Groove, 15...detection means.

Claims (1)

[Claims] 1 When rolling a rod-shaped material for a coil spring into a tapered shape, the material is pre-rolled by pressing it in the radial direction with a group of preliminary rolls having circumferential grooves, and a tapered bar to be rolled on the outer periphery. A pair of first rolls having a circumferential groove having an arcuate cross-section with a radius of curvature R larger than the desired outer diameter r of A pair of second rolls each having a circumferential groove having an arcuate cross-sectional shape with a radius of curvature R larger than the radius r and whose rotational axes are perpendicular to both rotational axes of the first roll, The opposing roll spacing of the first roll and the opposing roll spacing of the pair of second rolls are each variably controlled in relation to the amount of longitudinal movement of the tapered portion of the material inserted into the mutually opposing portions of the groove. By doing so, the first roll pair and the second roll pair are arranged so that the cross-sectional shape of the tapered part after rolling becomes a circular shape resembling a polygon with each side bulging out in an arc shape.
A method for manufacturing a tapered bar for a coil spring having a circular cross section, which comprises rolling a tapered part while pressing a pair of rolls from both directions at the same time and changing the opposing distance between the rolls.