JPH11270604A - Resin coil spring - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a form of a coil spring allow resin forming. SOLUTION: In this resin coil spring in this invension, unit coil elements having a first part 1a extending from a parting plane in the circumferential direction within a first orthogonal plane orthogonal to a coil axial line; a second part 1b extending from a parting plane in the circumferential direction opposing by holding the first part 1a and the coil axial line, within a second orthogonal plane separated a half pitch part in the axial direction from the first part 1a where the first part 1a extends; and the third part 1c extending within an inclined plane with a specific inclination to the orthogonal planes, and connecting both members at the circular arc of the diameter same as the first part 1a and the second part 1b; are connected in a spiral form.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a coil spring.
In particular, the present invention relates to a coil spring used as a component of a clutch and a torque limiter used in a copying machine, a printer for a personal computer, and the like.

[0002]

2. Description of the Related Art A clutch and a torque limiter are disposed in a power transmission path between a motor of a paper feeding device such as a copying machine and a printer for a personal computer and a paper feeding roller, and control the transmission of rotational torque. . As shown in FIG. 4, the clutch and the torque limiter are connected to the input side shaft member (11).
, A cover (12), a coil spring (13), and an output-side shaft member (14) as main components.

The input side shaft member (11) has a gear (1) at one end.
1a) is a resin hollow shaft member having a shaft portion (11b) formed at the other end. The cover (12) is a resin sleeve member having a slit (12a) at one end. The coil spring (13) is a metal spring member in which a coil wire is spirally wound in a fixed direction, and has an engagement piece (13a) formed at one end and projecting in an outer diameter direction, and an axial direction at the other end. An output piece (13b) protruding from the rim is formed. The output side shaft member (14) has a shaft portion (14a) at one end on which a coil spring (13) is interposed, and an output piece (13b) of the coil spring (13) is engaged at an intermediate portion. Groove (14
b) is formed, and a shaft member made of resin having an output end (14c) formed at the other end.

[0004] The clutch and the torque limiter include a cover (12), a coil spring (13), and an output shaft member (14).
The input side shaft member (11) is attached in order. The shaft portion (11b) of the input-side shaft member (11) and the shaft portion (14a) of the output-side shaft member (14) are in contact with each other, and the coil spring (13)
Are fitted into both input side and output side shaft portions (11b, 14a). The engagement piece (13a) of the coil spring (13) is inserted into the slit (12a) of the cover (12), and the output piece (13b) of the coil spring (13) is connected to the output shaft member (14).
Into the engaging groove (14b).

In the clutch and the torque limiter, a gear (11a) of a motor (not shown) is connected to a gear (11a) of an input shaft member (11), and an output end (14c) of an output shaft member (14) is connected to a gear (11c). A non-operating member (for example, a paper feed roller) is connected.

Hereinafter, the operation of the coil spring in the clutch and the torque limiter will be described.

First, when the rotational torque is in the direction of winding of the coil spring, the coil spring (13) is reduced in diameter to tighten both the input and output shafts (11b, 14a). The input shaft member (11) and the output shaft member (14) are coupled by the frictional force of the coil spring (13), and the rotational torque is transmitted to the output side shaft member (14) and the operating member. However, when the rotational torque is larger than the frictional force between the coil spring (13) and the shaft (11b) of the input shaft member (11), the shaft (11b) of the coil spring (13) and the input shaft member (11) is increased. ) Occurs, and a rotational torque exceeding this frictional force is not transmitted to the output side shaft member (14) and the operating member, and exhibits a function as a so-called torque limiter.

[0008] Second, the rotational torque is increased by a coil spring (13).
When the coil spring (13) has a direction opposite to the winding direction, a frictional force is applied in a direction in which the coil spring (13) expands, and the coil spring (13) and the input-side shaft member (11) slide relatively. The rotation torque is easily transmitted, and the rotation torque is hardly transmitted, so that a function as a so-called one-way clutch is exhibited.

That is, the clutch and the torque limiter convert the rotational torque input to the input side shaft member (11) into
The output shaft member (14) is converted into a rotational torque corresponding to the frictional force between the input shaft member (11) and the coil spring (13).
To communicate.

[0010]

The coil spring has a complicated shape of a wound portion and is technically difficult to produce by, for example, injection molding. Therefore, it is difficult to form a resin molded product. , Made of metal.

Since the coil spring is composed of a member separate from the output side shaft member, as described above, the engagement piece is engaged with the slit of the cover, and the output piece is engaged with the engagement groove of the output side member. It must be assembled and the assembling work is complicated.

Accordingly, an object of the present invention is to make the coil spring resin-moldable by injection molding or the like so that the shape of the coil spring can be removed.

[0013]

The present invention has the following shapes as the shape of a coil spring made of resin that can be cut out. That is, the resin coil spring of the present invention is a resin coil spring integrally formed using a half mold, and is separated from a mold plane including an axis passing through the center of the inner space of the coil spring. A first part extending a predetermined length in the circumferential direction from the mold plane in an orthogonal plane perpendicular to the axis, and a first part extending in the axial direction from the first plane. At a half pitch of the coil spring, a second portion extending a predetermined length in the circumferential direction from the mold plane in an orthogonal plane orthogonal to the axis and a first portion and a second portion are spirally connected. It is composed of a third part.

The resin coil spring can be applied to a spring element of the clutch and the torque limiter by being continuously formed on one of the shaft members of the clutch and the torque limiter.

That is, a resin-made first shaft member that is continuously formed in the axial direction of the resin-made coil spring is fitted to the resin-made coil spring of the first shaft member, and coaxially butted with the first shaft member. And a second shaft member arranged between the first and second shaft members. The rotation torque input to one of the shaft members is transmitted between the first and second shaft members by a coil spring of the second shaft member and the first shaft member. A clutch and a torque limiter that convert the torque into a rotational torque corresponding to the frictional force and transmit the torque to the other shaft member.

When the present invention is applied to a clutch and a torque limiter, it is desirable that a non-slip is formed on the inner diameter surface in the distal end region of the coil spring of the first shaft member.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The coil spring of the present invention has a shape that can be easily removed from a molding die after resin molding (for example, injection molding).

An embodiment of a resin coil spring according to the present invention will be described below with reference to the drawings. The coil spring is 360
The distance that is wound and advances in the axial direction is defined as one pitch of the coil spring.

FIG. 1 shows a front view (a) and a plan view (b) of a coil spring according to the present invention.

This coil spring is a resin molded product and can be integrally formed by using a half mold. A dashed line (P) in FIG. 1B shows a half-split type mold plane for molding the coil spring of the present embodiment. The parting plane (P) is a plane including an axis passing through the center of the inner space of the coil spring (hereinafter, referred to as a coil axis). The semi-circular coil elements having a central angle of 180 ° and divided on both sides of the cutting plane (P) have the same shape.

The semicircular coil element has a central angle of 180 °.
Are arranged at right angles to the mold plane (P) at intervals of one pitch, and are molded so as to form a semi-cylindrical shape as a whole.

The unit coil element will be described with reference to FIG.

The unit coil element (1) has a predetermined length from one end as a first portion (1a), a predetermined length from the other end as a second portion (1b), and a first portion (1a) and a second portion (1b). ) Is defined as a third portion (1c). Further, the unit coil element (1) of the present embodiment has a rectangular cross section (1d). In the figure, XX indicates a boundary between the first part (1a) and the third part (1c), and YY indicates a boundary between the second part (1b) and the third part (1c). .

The first portion (1a) extends circumferentially from the mold plane in a first orthogonal plane (F1) orthogonal to the coil axis. The second portion (1b) is separated from the first orthogonal plane (F1) by which the first portion (1a) extends in a second orthogonal plane (F2) axially separated by a half pitch in the first orthogonal plane (F2). ) Extends in the circumferential direction from the mold cutting plane so as to face the coil axis. The third portion (1c) is formed by the orthogonal plane (F
1, F2) extends in an inclined plane having a fixed inclination angle, and connects the two parts with an arc having the same radius as the first part (1a) and the second part (1b).

The length of extension of the first portion (1a) and the third portion (1c) is set to a length that facilitates die cutting of the coil spring as described later.

The unit coil element (1) has a cutting plane (P)
The boundary is a staircase, and as a whole, FIG.
A spiral coil spring as shown in FIG.

The molding die used for molding the coil spring according to the present embodiment is a half mold having a core.

The core is a cylindrical body having the same outer diameter as the inner diameter of the coil spring.

The half mold has a cylindrical hole into which a core is inserted, and is formed by a mold plane including an axis of the core (the axis of the core coincides with the coil axis). It is divided into a mold and a lower mold.

The upper die has a semi-cylindrical hole formed with a semi-arc shaped coil element forming surface.

The lower die has a semi-circular coil element forming surface formed such that the upper and lower mold surfaces are continuous with the upper and lower molds fitted in the semi-cylindrical hole.

In this molding die, the upper die is fitted to the lower die while the core is disposed in the hole of the lower die. Thereby, a forming surface corresponding to the shape of the coil spring that winds the outer periphery of the core in one direction is formed in the forming die. The coil spring is molded by filling the molding surface of such a mold with a molten resin by injection molding.

The cutting of the coil spring is performed by cutting the upper and lower dies straight in a direction perpendicular to the cutting plane.

The first part (1a) and the second part (1b) near the parting plane (P) of the unit coil element (1) are in an orthogonal plane (F1, F2) orthogonal to the parting plane (P). Therefore, there is no interference with the molding surface when the mold is removed. The third portion (1c) of the unit coil element (1)
Is an orthogonal plane (F1, F2) orthogonal to the parting plane (P)
Is formed in the inclined plane (P) having a predetermined inclination angle, so that it interferes with the molding surface during die cutting. However, as shown in FIG. 1 (b), the third portion (1c) is formed in a region near the central angle of 90 ° of the arc-shaped coil element having the central angle of 180 °, and the width in the die-cutting direction is small. The influence of the interference with the mold on the die cutting is negligible. The first portion (1a) of the unit coil element (1) and the second portion (1a)
The length of the part (1b) is the third part (1c) at the time of die-cutting.
The resistance caused by the interference between the mold and the molding surface is set so as to be within the molding allowable range.

The coil spring according to the present embodiment is constituted by the unit coil elements (1), and thus can be die-cut as a whole.

The unit coil element (1) of the present embodiment
Adopts a rectangular cross-sectional shape, but in the present invention, in order to enable die-cutting from a half mold, the cross-sectional shape of the unit coil element (1) is the same as that of the outer diameter side or the inner diameter side. Any shape may be used as long as the diameter is smaller than the inner diameter side.

The coil spring of the present invention has a shape that allows resin molding as described above.

[0038] For this reason, it is possible to form another member element with resin following the coil spring. Hereinafter, a second embodiment in which the coil spring of the above embodiment is applied to a clutch and a torque limiter will be described.

FIG. 3 is an exploded view of the clutch and the torque limiter.

This clutch and torque limiter include an input-side shaft member (11), a cover (12), and an output-side shaft member (21). The input-side shaft member (11) and the cover (12) are members having the same configuration as those used for the clutch and the torque limiter described as the related art, and thus redundant description will be omitted.

In the output shaft member (21) of this embodiment, the output end (21a) formed at the output end and the input shaft member (11) formed at the input end are in contact with each other. It is a resin member having a shaft portion (21b) and a coil spring portion (21c) formed continuously from the shaft portion (21b) to the input side.

The coil spring portion (21c) has an engagement piece (21c1) formed at an end thereof, which protrudes in the outer diameter direction, and has an inside diameter into which the shaft portion (11b) of the input side shaft member (11) can be inserted.

The clutch and the torque limiter are provided on the output side shaft member (21) with the cover (12) and the input side shaft member (1).
1) are attached in order. The cover (12) is externally inserted into the coil spring portion (21c) of the output side shaft member, and the cover (1).
The engagement piece (21c1) of the coil spring portion (21c) is inserted into the slit (12a) of 2). Input side shaft member (1
1) The input shaft member (11) in which the shaft portion (11b) is inserted into the coil spring portion (21c) of the output shaft member (21).
(11b) and the shaft (21) of the output side shaft member (21).
b) are configured to abut each other.

In the clutch and the torque limiter, a gear (11a) of an input side shaft member (11) is connected to a gear of a main shaft of a motor (not shown), and an operating member is connected to an output end (21a) of the output side shaft member (21). (For example, a paper feed roller).

With this configuration, the clutch and the torque limiter of the present embodiment, like the above-described clutch and torque limiter, transmit the rotational torque input to the input side shaft member (11) to the input side shaft member (11) and the coil. Spring part (21
c) is converted into a rotational torque corresponding to the frictional force, and transmitted to the output end (21c) of the output side shaft member (21).

The clutch and the torque limiter according to the present embodiment are designed to make the input shaft member (11) made of resin and the coil spring portion (21c) of the output shaft member (21) made of resin easy to bite. In addition, it is preferable to form a non-slip at the tip of the coil spring portion (21c) of the output side shaft member (21).

Although the embodiments of the present invention have been described above, the shapes and the like of each member can be variously changed. For example, in the above-described clutch and torque limiter, the embodiment in which the coil spring is integrally formed with the output-side shaft member has been described, but the coil spring may be integrally formed with the shaft portion of the input-side shaft member.

The shape of the coil spring is such that one coil element of the coil spring is formed by a first portion extending circumferentially at a predetermined position from a mold plane in an orthogonal plane perpendicular to the coil axis, and a first portion. A third portion extending in a circumferential direction from the mold cutting surface by a predetermined length in an orthogonal plane separated by one pitch in the direction of the coil axis from the first portion, and a third portion spirally connecting the first portion and the second portion. And the other coil element is
It is also possible to configure a fourth part extending in the same orthogonal plane as the part.

[0049]

As described above, the coil spring of the present invention has a shape capable of being die-cut, so that a resin molded product that can be molded by injection molding or the like can be obtained.

By applying the coil spring of the present invention to the spring element of the clutch and the torque limiter, all the components of the clutch and the torque limiter can be made of resin molded products, so that the weight of the clutch and the torque limiter can be reduced. be able to.

Further, since the spring element of the clutch and the torque limiter can be integrally formed with the shaft member of the resin clutch and the torque limiter, the work of mounting the clutch and the torque limiter can be simplified, In the clutch and torque limiter described above, it is possible to eliminate troubles such as an attachment error and a detachment of an engagement portion, which are caused by separate spring elements.

[Brief description of the drawings]

FIG. 1A is a front view of a coil spring according to the present invention, and FIG.
1 is a plan view of a coil spring according to the present invention.

FIG. 2 is a front view of a unit coil element.

FIG. 3 is an exploded perspective view of a clutch and a torque limiter.

FIG. 4 is an exploded perspective view of a conventional clutch and torque limiter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Unit coil element 1a 1st part 1b 2nd part 1c 3rd part 11 Input side shaft member 12 Cover 21 Output side shaft member

Claims (3)

[Claims] 1. A resin coil spring integrally molded using a half mold, wherein one half mold is bounded by a mold plane including an axis passing through the center of the inner space of the coil spring. An arc-shaped coil element having a central angle of 180 °, a first part extending a predetermined length in a circumferential direction from the mold plane in an orthogonal plane orthogonal to the axis, and a first part extending in the axial direction from the first part. A second portion which is separated by a half pitch of the coil spring and extends a predetermined length in a circumferential direction from the mold cutting plane in an orthogonal plane perpendicular to the axis, and the first portion and the second portion are spirally formed. A resin coil spring comprising a third portion to be connected. 2. A resin-made first shaft member continuously formed in the axial direction with respect to the resin-made coil spring of claim 1, and said resin-made coil spring of said first shaft member is fitted to said resin-made coil spring. A second shaft member coaxially butted with the first shaft member, wherein a rotational torque input to one shaft member between the first and second shaft members is transmitted to the second shaft member and the second shaft member. A clutch and a torque limiter that convert a rotational torque corresponding to a frictional force between one shaft member and a coil spring and transmit the rotational torque to the other shaft member. 3. The clutch and torque limiter according to claim 2, wherein a non-slip is formed on an inner diameter surface of the first shaft member in a distal end region of the coil spring.