JPH0146201B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel continuous plastic working method and apparatus for tapered wire rods using rolls.

Recently, the elastic effect of nonlinear coil springs, whose spring constant changes with changes in load, has been attracting attention. As a kind of nonlinear coil spring, a wire rod having a predetermined length as shown in FIG. There are some that are molded into coils like this.

Traditionally, this type of tapered wire has been obtained by grinding a predetermined portion of a predetermined length of wire that has the same diameter over its entire length, or by processing it by swaging. Yields are poor, swaging has problems in terms of noise and workability, and both require complicated and inefficient work processes, leading to high material costs and impeding the spread of nonlinear coil springs made from tapered wire. It's hindering. Furthermore, with conventional methods, it is difficult to produce a tapered wire rod in which tapers are repeated and continuous. Therefore, regarding the latter method, the present inventor considered the following method in the process of completing the present invention.

Semi-circular arc-shaped grooves are formed on the circumferential surface of each of the pair of rolls, and the radius increases sequentially from the minimum to the maximum, extending 180 degrees, and the pair of rolls are arranged so that the same radius portions of the grooves are in opposing contact with each other. and a wire having a diameter larger than the maximum diameter is passed between the slots. However, in this method, the length of one cycle of repeating the taper is regulated by the circumference of the roll, so in order to increase the length of one cycle, the diameter of the roll must be increased. For example, one cycle length is
In order to achieve 3.14 m, the diameter of the roll must be approximately 1 m, and the longer the length of one cycle, the larger the equipment must be. Furthermore, since different rolls must be prepared for each different wire diameter, taper angle, cycle length, etc., there is a problem in that the number of rolls becomes large.

In order to solve the above-mentioned problems, the present invention has the following points:
This is a further development of the above idea, in which a pair of rolls configured as described above is forcibly driven, and the moving speed of the wire passing through the slot, specifically, when passing through the linear slot connecting the rotation axes of the pair of rolls. A speed ratio is maintained between the feeding speed of the wire rod and the rotational speed or circumferential speed of the roll rotated by forced drive, and the speed ratio of the circumferential speed of the groove bottom on the line connecting the rotational axes of the pair of rolls is kept constant. By controlling the diameter of the wire, it is possible to plastically process the wire diameter into a continuous repeating taper over a cycle of a desired length.

The present invention will be explained according to the embodiment shown in FIGS. 2a to 5.

In FIGS. 2a to 2c, 1a and 1b are a pair of rolls each having semicircular arc-shaped slots 2a and 2b formed in the center of the circumferential surface, and the slots 2a
and the radius of 2b is the minimum r ₁ between the positions separated by 180°
It changes sequentially from up to r ₂ . Rolls 1a and 1
b are arranged in close contact with each other, as shown in FIG. 2c, so that the slot portions having the same radius are in opposing contact with each other. Therefore, when the rolls 1a and 1b are synchronously forcedly rotated via a timing gear or the like, the grooves 2a and 2
The radius of the arcuate groove shaped by b is the minimum radius
It changes from r ₁ through the maximum radius r ₂ to the minimum radius r ₁ .
The wire rod W is passed through the grooves 2a and 2b of the rolls 1a and 1b, and plastic working is performed according to the radius of the grooves 2a and 2b.In the present invention, the rotational speed V _R of the roll 1 and the feed of the wire rod W are By setting a predetermined speed ratio between the speed V _W and the actual roll circumference, the wire diameter is repeatedly changed from the minimum radius r ₁ to the maximum radius r ₂ to the minimum radius r ₁ for each length different from the actual roll circumference. This is an attempt to perform plastic processing of change. Now, if V _W < V _R , the wire rod W is subjected to plastic working in which the maximum and minimum diameter of the wire rod changes repeatedly for each length shorter than the actual circumference of roll 1, and if V _W > V _R , the wire rod Plastic working is performed on W so that the maximum and minimum diameters thereof are repeatedly changed for each length longer than the actual circumference of the roll 1.

According to the present invention, by making the rotational speed V _R of the roll by forced drive slower than the wire moving speed V _W , the cycle of wire diameter change can be applied to the wire W with a relatively small diameter roll. Not only can plastic working longer than the length be performed continuously, but by setting the speed ratio V _W / V _R as specified, one cycle length in which the wire diameter changes with the desired curvature can be achieved as desired. A wire rod as shown in Fig. 2 d changed as shown in
Continuous plastic working of W ₁ is possible.

The present invention further includes the method described below. In other words, in the case described above, the wire diameter is repeatedly increased and decreased so that the wire diameter has a desired curvature, whereas as shown in Figure 3 a and b, the wire diameter is The minimum diameter d ₁ to the maximum diameter d ₂
, and the repetition of linearly changing from the maximum diameter d ₂ to the minimum diameter d ₁ is continued.

That is, in the method described above, the wire is inserted into the slot 21 in which the center 0' of the circle formed by the groove bottoms of the grooves 2a and 2b is eccentric with respect to the roll rotation center 0, as shown in FIG. 2C. As the wire is passed through, the wire diameter increases or decreases with a desired curvature determined by the speed ratio V _W /V _R. However, in this method, the eccentricity of the upper curve of 0.0' is corrected, that is, the diameter of the wire is By keeping the circumferential velocity of the groove bottom constant on the line connecting the .

While forcing the forced drive roll 1 of diameter d shown in Fig. 2 to rotate at a circumferential speed V _R , the wire is moved at a speed V _W
It passes through the slots 2 of the rolls 1a and 1b. The material wire diameter is dx, which is defined as the diameter of the minimum diameter part of the wire d ₁ , the diameter of the maximum diameter part of the wire d ₂ , the distance l between the minimum diameter part and the maximum diameter part, and the taper angle α of the tapered part (= tan ^-1
d ₂ - _{d 1} /2l), the circumferential speed of the groove bottom on the line connecting the rotating axes of a pair of rolls.
When V _R is set constant, the minimum radius of groove depth r ₁ = d ₁ /2 and the maximum radius of groove depth r ₂ = d ₂ /2, so speed ratio γ = V _W /V _R = constant...(1 ) If V _R and V _W are both velocity on the line connecting 0.0', the time t required for the roll to make half a revolution is t = π/2d'/V _R where d' = D - (r ₁ + r ₂ )
= π/2V _R {D-(r ₁ + r ₂ )}...(2) Therefore l=Vw・t=πV _W /2V _R {D-(r ₁ + r ₂ )}=γ
・π/2 {D-(r ₁ + r ₂ )}...(3) By the way, the wire diameter dx at a point a distance x away from the minimum diameter part d ₁ of the wire in Fig. 3a is dx = d ₂ - _{d 1} / lx+d ₁ (4) In this case, since γ is constant, l is also uniquely determined, and since the rate of increase of dx is constant, the tapered portion becomes conical.

The cross-sectional area Sx changes by Sx=π/4(d ₂ − _{d 1} /lx+d ₁ ) ² ...(5), and the taper angle α is α=tan ^-1 d ₂ −d ₁ /2l=tan ^{- 1} r ₂ − r ₁ /l ...(6).

Therefore, when the wire W is fed at a speed V _W and the roll is forcibly rotated in the direction of the arrow from the position r ₁ where the groove depth is the minimum as shown in Fig. 2c, the wire W will be rotated as shown in (6) above. The wire diameter increases from wire diameter d ₁ to wire diameter d ₂ with a taper angle α determined by the formula, and by the next rotation of 180°, the wire diameter increases from wire diameter d 2 to wire diameter d ₂ with a taper angle α. d ₁
By continuously rotating the roll 1, the wire rod _W2 is subjected to plastic working in which tapers are continuously repeated as shown in FIG. 3a.

In order to keep the peripheral speed V _R of the groove bottom constant on the line connecting the rotational axes of the pair of rolls, it is necessary to control the rotational speed ω of the roll 1.

In Figure 3b, the equation of the roll outer diameter: x ² + y ² = (D/2) ² ...(7) The equation of the groove bottom circle: (x-δ) ² + y ² = (d'/2) ² ...(8) The eccentricity δ of the center 0' of the circle formed by the groove bottom with respect to the rotation center 0 of the roll is δ=D/2- _r1 -d'/2=D/2- _r1- 1/2 {D-
(r ₁ + r ₂ )} = 1/2 (r ₂ − r ₁ ) ...(9) Equation (8) can be expressed as follows using polar coordinates.
Let the rotation angle of the roll be θ, and in equation (8), x=r cosθ,
Substituting y=r sinθ, we get Since r≧0 here Since the root is positive or zero, d′≧r ₂ −r ₁ From equation (10), it is a function of rθ.

Since V _R = ω・r(θ), in order to keep V _R constant, The roll may be rotated at a rotational angular velocity ω(θ) that satisfies the following.

In the present invention, the rotational angular velocity ω(θ) of the rolls is controlled using equation (11) so that the circumferential velocity V _R of the groove bottom on the line connecting the rotational axes of a pair of rolls is constant. is the roll rotation angle θ
is detected, and ω(θ) is calculated using equation (11) by an arithmetic device.
The roll driving device may be controlled so that the rotational angular velocity of the roll is ω(θ).

An actual concrete example is shown below.

The minimum wire diameter d ₁ of the wire rod is 8 mmφ and the maximum wire diameter d ₂ is 12 mmφ using a forced drive roll with the specifications set as below.
When plastic working a tapered wire rod in which one taper cycle 2l is 3 m repeatedly, roll outer diameter 200 mmφ minimum groove depth radius r ₁ 4 mm maximum radius difference r ₂ 6 mm wire rod movement speed V _W 40 m/min (0.666 m /sec) The eccentricity δ of the center 0' of the circle formed by the groove bottom with respect to the rotation center 0 of the roll is given by equation (9), δ = 1/2 (r ₂ - r ₁ ) = 1/ 2 (6-4) = 1 mm The diameter d' of the circle formed by the groove bottom is d ₁ = D - (r ₁ - r ₂ ) = 200 - (4 + 6) = 190 mm Time required for the roll to rotate half a revolution t is (3) formula l=
_VW

Claims (1)

[Scope of Claims] 1. A pair of rolls each having a semicircular arc-shaped slot whose radius increases sequentially from the minimum radius to the maximum radius at an interval of 180° along the wire feed path, is placed in the slot. Arranged in close contact so that parts of the same radius are in opposing contact,
A predetermined speed ratio is provided between the rotational speed of the pair of rolls due to synchronous forced rotational drive and the feeding speed of the wire rod when passing through the slot on a line connecting the rotational axes of the rolls, and By controlling the circumferential speed of the groove bottom on the line connecting the rotational axes of the rollers to be constant, the diameter of the wire rod has a linear predetermined taper angle over a length different from the circumferential length of the roll. A continuous plastic working method for a tapered wire rod, which is characterized by performing plastic working so as to repeatedly change the wire rod. 2. A pair of rolls each having a semicircular arc-shaped slot whose radius increases sequentially from the minimum radius to the maximum radius at an interval of 180° along the wire feed path, is placed in opposing contact with the same radius portion of the slot. Place them close together so that
A predetermined speed ratio is provided between the rotational speed of the pair of rolls due to synchronous forced rotational drive and the feeding speed of the wire rod when passing through the slot on a line connecting the rotational axes of the rolls, and The circumferential speed of the rolls is controlled so that the circumferential speed of the groove bottom on the line connecting the rotation axes of the pair of rolls is constant, and the circumferential speed of the rolls is controlled so that the circumferential speed of the groove bottom is constant, and the circumferential speed of the rolls is controlled to By controlling the wire diameter to be 0 for a desired time from the point of contact with the part, the wire diameter increases or decreases at a predetermined taper angle over a length different from the circumferential length of the roll. 1. A continuous plastic working method for a tapered wire rod, comprising repeatedly and continuously plastic working a tapered part and a parallel part having the same diameter as the maximum or minimum diameter.