JPH01108430A - Noncircular cross-sectional shape compression coil spring - Google Patents

Abstract

PURPOSE:To enable a noncircular cross-sectional shape compression coil spring to exhibit its design performance to a maximum degree by twisting a part of a spring wire material so that the major diameter side inner peripheral surface of the spring wire material is deflected toward the free end of the compression spring in a no load condition. CONSTITUTION:An inclined angle of a supply roller groove is suitably selected in accordance with coil pitches and a spring constant so as to twist a spring wire material by a desired twist angle before a noncircular cross-sectional compression coil spring 2 is formed. In this compression spring 2, the major diameter side inner peripheral surface of the spring wire material is deflected toward the free end side of the spring on the basis of an expansion criterion. Accordingly, when an axial load is applied to the compression coil spring, a twisting force is exerted to the spring wire material in a direction as indicated by the arrow B so that the twist angle of the spring wire material becomes a value equal to or substantially equal to zero. That is, the spring wire material is twisted in a direction in which the twist thereof is eliminated, it is possible to exhibit the design performance of the noncircular cross-sectional shape compression coil spring to a maximum degree.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a compression coil spring formed by spirally winding a spring wire having a non-circular cross section.

and p - The commonly used compression coil spring 01 (Fig. 1) is
A spring wire 02 having a circular cross section is spirally wound. When the axial direction ff1P acts on the coil spring 01, torsional shear stress in the direction shown by arrow A is generated in the spring wire 02. This torsional shear stress is maximum at the inner periphery of the coil because the spring wire 02 is curved, and is larger than that at the outer periphery. In addition, the maximum shear stress (τm
ax) is expressed by the following formula.

However, D...Coil center diameter, d...Spring wire diameter,
C (spring index)=D/d.

Since this maximum shear stress (τa+aX) is generated at the inner circumference of the coil, when an excessively repetitive load is applied to the compression coil spring 01, the spring wire 02 tends to crack at the inner circumference of the coil. To avoid this drawback, spring wire 0
The cross section of 4 is oval, and the major axis 05 side is the spring center iL.
A coil spring 03 (a second
Figure) was proposed (publication of Utility Model Publication No. 27-3261). In this coil spring 03, inside the coil under the action of the shaft cylinder IP,
The shear stress on the outer periphery is smaller on the inner periphery and larger on the outer periphery than that of a coil spring formed of a wire with a circular cross section having the same diameter as the short diameter 06 of the spring wire 04, and the difference in shear stress between the inner and outer peripheries. is getting smaller. Therefore, the energy efficiency of the spring is improved and the range of use is expanded (due to the reduction of the maximum shear stress (τWaX) at the inner circumference of the coil).

However, since the spring wire 04 of the coil spring 03 has a small radius of curvature at the inner circumferential portion of the coil, the stress distribution on the circumferential surface of the spring wire is uneven, and the spring wire 94 is damaged during winding work. It is said that it is difficult to wind the wire so that the extended line of the major diameter 05 is perpendicular to the spring center line, and in order to avoid this drawback, the spring element wire 04 with an oval cross section is used as shown in FIG.
A coil spring 03A was proposed in which the side with the smaller radius of curvature of A is directed toward the outer periphery of the coil (Japanese Patent Laid-Open No. 60-69337).

Even when using the spring wire 04A with such an oval cross section, if the winding work is simply performed as usual, the spring wire 04A is
4^ will naturally twist and the extended line of major axis 05A will not be perpendicular to the spring center line, but if now the major axis is 0
Assume that a coil spring 03A shown in FIG. 3 is obtained in which the extension line of 5A is perpendicular to the spring center line. in this case,
If an axial load in the compression direction is applied to the coil spring 03A, a torsional force in the direction shown by arrow B acts on the spring wire 04^, see FIG. 4. In the figure, S indicates the expansion/contraction M table surface), and the spring wire 04A is twisted according to the magnitude of the acting force, and the maximum shear stress (τ01
aX) results in an increase.

In reality, if winding is simply performed as described above, both compression coil springs 03.03A tend to naturally twist in the same direction as arrow B. FIG. 5 shows the effect of the naturally occurring torsion on the maximum shear stress for the compression coil spring 03. Above the graph in FIG. 5, the spring wire 04 of the compression coil spring 03 is angled (α ) is shown with a broken line (a state in which twist occurs naturally in a normal winding). As this torsion angle (α) increases, the compression coil spring 03
The maximum shear stress (τa+aX) generated at the inner periphery increases (graph in Figure 4). Therefore, due to the effect of torsion occurring in the same direction as the torsion angle (α) when a load is applied, a large tA1g is generated on the inner circumference of the compression coil spring 03.
i stress will occur.

0 ' This invention was devised based on such technical considerations, and is designed so that when a load is applied, the extended line of the major diameter of the spring wire is perpendicular to, or almost perpendicular to, the center line of the spring. The object is to provide a compression coil spring with a non-circular cross section.

The purpose of this is to create a non-circular shape in which a spring wire with a non-circular cross-section is wound in such a way that its long diameter side is oriented in a direction intersecting the spring center line, and its short diameter side is oriented in a direction along the spring center line. In a cross-sectional compression coil spring, the inner peripheral surface on the long diameter side of the spring wire is
The spring wire is characterized in that at least a portion of the spring wire is sloped in advance so that it is deflected toward the free end side of the compression coil spring in an unloaded state, using the expansion/contraction reference plane of the compression coil spring as a reference □. This is achieved by providing a non-circular cross-section compression coil spring.

When an axial load is applied to the coil spring, as shown in Fig. 4 (arrow B
) is applied to the spring wire and the spring wire is twisted, so the spring wire is twisted in the opposite direction (twisting in the opposite direction to the twisting that occurs in normal winding (Figure 5)).
By applying this to at least a portion of the spring wire, it becomes possible to make the torsion angle zero or close to zero when applying an axial load.

The twist that occurs in the spring wire of a compression coil spring when a load is applied varies depending on the magnitude of the load (large load → large twist) and the size of the pitch (large pitch → large twist), and the pitch in the height direction of the same spring varies. If they are different, a larger twist occurs at the large pitch location compared to the small pitch location. In this specification, the meaning of giving twist to at least a part of the spring wire means: ■ When the same spring has different pitches in the height direction, at least the large pitch part (or at least the least part in the height direction of the large pitch part) (part of the coil) is given a twist in the opposite direction to the twist caused by normal winding; The purpose is to provide a twist in the opposite direction to the twist caused by the winding.

Hereinafter, a method for manufacturing a non-circular cross-section compression coil spring of the present invention will be explained (FIGS. 6 to 11).

FIG. 6 shows that the wire material 1 is supplied to a plurality of supply roller pairs 3 (3
A, 3B), 4 (4A, 4B), 5 (
5A, 5B), the wire is sent to the winding roll 9.10 via the wire guide mold 6 and the guide roller 7.8, where it is given a predetermined curved shape, and given a predetermined pitch by the pitch defining device 11, forming a compression coil spring. 2 shows the state that is done (
In the figure, reference numeral 12 indicates a cutter for cutting the coil spring into regular lengths). The cross-sectional shape of the wire material 1 is shown in FIG. 9, with the D portion being formed on the inner circumferential surface of the coil and the E portion being formed on the outer circumferential surface of the coil. In addition, corresponding to the cross-sectional shape of the wire material 1, a groove of 3°4.5 for each supply roller pair, a mold hole of the wire guide mold 6,
The grooves of the guide roller 7.8 and the grooves of the winding roll 9.10 also have the same shape (FIGS. 7 and 8).

The grooves of each supply roller pair 3.4.5 are as shown in FIG.
The wire material 1 is formed so that its major axis is inclined by an angle (θ) from a plane F perpendicular to the center line of the compression coil spring 2 in the winding process. If the angle (θ) is set to zero as shown in FIG. 10, the spring wire of the compression coil spring 2 to be formed will be twisted greatly as shown in FIG. As shown in Figure 11, the twist angle of the spring wire is approximately 21°/rn! become.

According to FIG. 11, as the inclination angle (θ) of the supply roller groove becomes larger, the twist angle of the spring wire of the coil spring 2 becomes smaller. In other words, when winding the wire, the inclination angle (θ
) by appropriately setting the torsion angle shown in FIGS. 4 and 11 (the torsion angle that occurs in normal winding) to the wire material 1 in the opposite direction to the spring wire of the compression coil spring 2. The torsion angle of can be made negative (decreased $!i) in FIG.

Therefore, the inclination angle (θ) of the supply roller groove is appropriately selected according to the coil pitch and the spring index (C=D/d), and the spring wire is pre-coated with the desired torsion angle (the torsion angle that occurs in normal winding wires). It is possible to obtain the compression coil spring 2 of the present invention which is twisted with a twist angle in the opposite direction.

An example of the compression coil spring 2 of the present invention thus obtained is shown in FIG. 12 (unloaded state B). In this compression coil spring 2, the inner circumferential surface on the long diameter side of the spring wire is located on the expansion/contraction reference plane S (
It is deflected toward the free end of the spring (torsion angle = β/pitch) with reference to a virtual plane (which indicates a position where the spring wire does not twist when an axial load is applied). When an axial load is applied to the compression coil spring 2, a twisting force in the direction shown by arrow B acts on the spring wire, and the twist angle (β/pitch) of the spring wire becomes zero or almost zero. Therefore, the compression coil spring 2 has a flat, non-circular cross-sectional shape, and the contact height is reduced.

The compression coil spring 2 is suitable for use in a compressed state rather than in a free height where no load is applied, such as a vehicle suspension spring (wheel suspension spring).

FIG. 13 shows an example in which a compression coil spring according to the present invention is formed using a spring wire 12 as a modification of the spring wire 04 shown in FIG. The spring wire 12 has an oval basic shape consisting of a semicircle and a semiellipse, similar to the spring wire 04.
It has a recess 13.13 in the semicircular part. Spring wire 1
2 to form the compression coil spring of the present invention is that during the winding operation, the wire material is rolled between supply rollers that have grooves of the same shape (grooves on the right side of the protrusions that match the recesses 13). It is possible to securely hold the spring wire 1 so that it does not rotate.
It is possible to easily give a desired angle of twist (twist in the opposite direction to the twist caused by normal winding) to the wire. Such effects can be obtained even if the recess 13 is a single one, or even if a flat cut surface is provided in place of the recess 13.

It should be noted that a compression coil spring made of a spring wire 12 having a cross-sectional shape having a recess 13 has a smaller contact height than a compression coil spring formed from a spring wire having an oval cross-section without a recess.
It is known that i is also reduced (Japanese Patent Laid-Open No. 1986-10
Publication No. 5317).

In addition, the device shown in Fig. 6 is an example in which the wire material 1 is twisted using tools such as supply rollers 3, 4, 5, etc., but the twist is in the opposite direction to the twist caused by normal winding. is given to the wire material in advance, and θ= in Fig. 9
The compression coil spring of the present invention can also be obtained by simply winding the wire in the zero state, that is, the state shown in FIG.

1 to 11 As is clear from the above explanation, the inner circumferential surface on the longer diameter side of the spring wire is deflected toward the free end of the compression coil spring in the no-load state with reference to the expansion/contraction reference plane of the compression coil spring. A compression coil spring with a non-circular cross section in which at least a portion of the spring wire is pre-twisted was proposed.

Since the spring wire of this compression coil spring is twisted toward the free end side of the compression coil spring with respect to the expansion/contraction reference plane, the twist disappears when an axial load is applied to the compression coil spring. The spring strands are twisted in the direction shown, maximizing the design performance of the non-circular cross-section compression coil spring.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional view of a known compression coil spring using a spring wire with a circular cross section, and Figs. 2 and 3 respectively show a known compression coil spring using a spring wire with an oval cross section. Fig. 4 is a diagram showing the direction of torsional force acting on the spring wire when an axial load is applied to the compression coil spring, and Fig. 5 is a diagram showing the direction of the torsional force acting on the spring wire during winding. Torsion angle (α)
FIG. 6 is a schematic diagram showing a manufacturing apparatus for a non-circular cross-section compression coil spring according to the present invention, and FIGS. 7 and 8 show the main parts thereof, respectively. 9 and 10 are explanatory diagrams respectively showing the relationship between the groove shape of the pair of supply rollers and the wire material in the manufacturing apparatus, and FIG. 11 shows the relationship between the inclination angle (θ) of the supply roller groove and the wire material. Graph showing the relationship with the twist angle of the spring wire, 12th
13 is a vertical sectional view of a main part of a compression coil spring according to an embodiment of the present invention, and FIG. 13 is a sectional view of a main part of a compression coil spring according to another embodiment. 1...Wire material, 2...Compression coil spring, 3.4.5
... Supply roller, 6 ... Wire guide type, 7.8 ... Guide roller, 9.10 ... Winding roll, 11 ... Pitch regulating device, 12: ... Spring wire, 13 ···dent.

Claims (1)

[Claims] A spring element wire with a non-circular cross-sectional shape is wound in such a manner that its longer diameter side is oriented in a direction intersecting the spring center line, and its shorter diameter side is oriented in a direction along the spring center line. In a compression coil spring with a non-circular cross section, the spring wire is arranged such that the inner circumferential surface on the longer diameter side of the spring wire is deflected toward the free end side of the compression coil spring in a no-load state with reference to the expansion/contraction reference plane of the compression coil spring. A non-circular cross-section compression coil spring, characterized in that at least a portion of the spring is pre-twisted.