JPH07233813A - Rotation bearing device and its manufacture - Google Patents

Abstract

PURPOSE:To improve the roundness of a rotation bearing by removing a welding line to weaken strength between resins in the rotation bearing made by forming resin. CONSTITUTION:In a rotation bearing device composed of a rotation bearing part 12a consisting of a formed resin body having a circular hole 12c and a rotary shaft 1 held in the circular hole of the rotary bearing part, the orientation of resin near the circumferential face of the circular hole 12c of the rotary bearing part 12a is about parallel to the circumferential face of the circular hole 12c. In the manufacturing method of the rotation bearing device which is composed of the rotation bearing part 12a consisting of the formed resin body having a circular hole and the rotary shaft 1 held in the circular hole of the rotation bearing part, the rotation bearing part 12a is formed using a resin forming metal mold with the injection direction of an injecting gate provided in the resin forming metal mold shifted from the axis 1b of the circular hole 12c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary bearing device and its manufacturing method, and more particularly to a sensor, potentiometer,
The present invention relates to a rotary bearing unit used for an actuator and the like, a rotary bearing device including a rotary shaft, and a manufacturing method thereof.

[0002]

2. Description of the Related Art A rotary bearing device formed by insert molding will be described with reference to FIG. 3 by taking Japanese Patent Application No. 04-057645 proposed by the same applicant as an example.

The rotary bearing device comprises a rotary shaft 1 and a housing 2.
Composed of and. The rotary shaft 1 is made of, for example, metal having high mechanical strength such as rigidity, and has a groove 1a having a V-shaped cross section formed in the circumferential direction of the outer peripheral surface. The housing 2 is a resin having lubricity, for example, a resin in which a polyphenylene sulfide (PPS) resin, a carbon fiber (CF), and a tetrafluoroethylene (PTFE) resin are mixed, and is rotated from the injection gate 3. By injection into a resin molding die (not shown) in which the shaft 1 is loaded, insert molding is performed integrally with the rotating shaft 1, and a rotating bearing portion 2a for holding the rotating shaft 1 and a case portion 2b for accommodating members.
To form. At the time of this insert molding, a circular hole 2c for holding the rotary shaft 1 and a circular hole 2 are formed in the rotary bearing portion 2a.
A ridge 2d having a V-shaped cross section that fits in the groove 1a in the circumferential direction of the inner peripheral surface of c is formed corresponding to the rotary shaft 1.

In the rotary bearing device having such a structure, the rotary shaft 1 is rotatably held by the rotary bearing portion 2a.

[0005]

However, in the rotary bearing device having such a structure, the injection gate for resin-molding the housing 2 has the end of the rotary bearing portion 2a as shown at 3 (4) in FIG. It is located in the vicinity of the portion and outside the outer periphery, and its injection direction is from the outer periphery of the rotary bearing portion 2a toward the central axis 1b of the rotary shaft 1. When there is one injection gate 3 in the resin molding die and there are three injection gates 4.
The case where there is a portion is shown in FIGS. 4 and 5, and the problems at that time will be described below.

In FIG. 4A, the injection gate 3 is 1
The injection direction X exists at a location, and the injection direction X extends from the outer periphery of the rotary bearing portion 2a toward the central axis 1b of the rotary shaft 1. Therefore, the resin in the AA cross section of the rotary bearing portion 2a has a symmetry axis on a line connecting the injection gate 3 and the central axis 1b of the rotation shaft 1, and is indicated by an arrow Y in the drawing. From there, it flows and is filled while spreading symmetrically. Therefore, the orientation indicating the filling state of the resin appears as the direction of the fibers contained in the resin, and this fiber direction is a line connecting the injection gate 3 and the central axis 1b of the rotating shaft 1 as shown in FIG. Be symmetrical with respect to. Therefore, when the resin is filled, the resin that branches in the left-right symmetry and flows is the central axis 1b of the rotary shaft 1.
On the other side of the injection gate 3, the leading resin members collide with each other to form a weld line 5. Therefore, the resin in the vicinity of the circumferential surface of the circular hole 2c has a problem that the packing density becomes non-uniform and the shrinkage ratio is different, and the circular hole 2c has a poor roundness. Further, the weld line 5 has a problem that the strength between the resins is weak and the mechanical strength of the housing 2 is lowered.

Further, in FIG. 5 (a), there are three injection gates 4 (4a-4c), and their injection directions X are
It extends from the outer periphery of the rotary bearing portion 2a toward the central axis 1b of the rotary shaft 1. Therefore, the resin in the AA cross section of the rotary bearing portion 2a is for injection as shown by an arrow Y in the drawing, with a line connecting the injection gates 4a to 4c and the central axis 1b of the rotary shaft 1 as a symmetry axis. Each of the gates 4a to 4c flows and is filled while being spread symmetrically. Therefore, the orientation indicating the filled state of the resin is symmetrical with respect to the line connecting the injection gates 4a to 4c and the central axis 1b of the rotary shaft 1, as shown in FIG. Therefore, at the time of resin filling, for example, the leading resin injected from the injection gates 4a and 4b collides with the resin that bifurcates in a left-right symmetrical manner and forms a weld line 6a. Similarly, weld lines 6b and 6c can be formed between the injection gates 4b and 4c and between the injection gates 4c and 4a. Therefore, similarly to the above, the circular hole 2c does not have a good roundness, and the weld lines 6a to 6c have weak resin strength,
There has been a problem that the mechanical strength of the housing 2 is lowered.

An object of the present invention is to solve the above problems, and to provide a rotary bearing device molded by resin, having no weld line, and having a good roundness, and a manufacturing method thereof. Especially.

[0009]

In order to achieve the above object, in a rotary bearing device of the present invention, a rotary bearing portion made of a resin molding having a circular hole and held in the circular hole of the rotary bearing portion. In the rotary bearing device including the rotary shaft, the orientation of the resin in the vicinity of the circumferential surface of the circular hole of the rotary bearing portion is substantially parallel to the circumferential surface of the circular hole.

Further, in a rotary bearing device in which at least a portion of the rotary shaft having grooves or projections formed in the circumferential direction of the outer peripheral surface is insert-molded with resin, the rotary shaft corresponds to the rotary shaft. The orientation of the resin of the rotary bearing portion is substantially parallel to the outer peripheral surface of the rotary shaft.

Further, in the method of manufacturing a rotary bearing device, the method of manufacturing a rotary bearing device comprising a rotary bearing portion made of a resin molding having a circular hole and a rotary shaft held in the circular hole of the rotary bearing portion. In the above, the rotary bearing portion is formed by using a resin molding die, and the injection direction of the injection gate of the resin molding die is shifted from the central axis of the circular hole.

Further, in the method of manufacturing a rotary bearing device, wherein at least a portion of the rotary shaft having a groove or a protrusion formed in the circumferential direction of the outer peripheral surface is insert-molded with a resin, the rotary bearing The part is formed by using a resin molding die, and the injection direction of the injection gate of the resin molding die is shifted from the central axis of the rotating shaft.

[0013]

According to the present invention, by shifting the injection direction of the resin by the injection gate from the central axis of the rotating shaft as described above, the orientation of the resin in the vicinity of the circular hole of the rotary bearing portion is substantially the same as the outer circumference of the rotating shaft. I made them parallel. As a result, the weld line is not formed in the rotary bearing, and the orientation is concentric with the circular hole, the packing density of the resin is uniform, the shrinkage ratio is uniform, and the circularity of the circular hole is It can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a rotary bearing device according to the present invention will be described with reference to FIGS. 1 and 2 by using an example in which a rotary shaft is insert-molded. In FIG. 1, the rotary bearing device includes a rotary shaft 1 and a housing 12.

The rotary shaft 1 is made of, for example, a metal having high mechanical strength such as rigidity, and has a groove 1a having a V-shaped cross section formed in the circumferential direction of the outer peripheral surface. The housing 12 has a lubricity, for example, PPS resin, CF,
A resin mixed with PTFE resin is used for injection gate 13a,
A rotary bearing portion 12 for holding the rotating shaft 1 by being insert-molded integrally with the rotating shaft 1 by injecting from 13b into a resin molding die (not shown) loaded with the rotating shaft 1.
A case portion 12b for accommodating a and the member is formed. At the time of this insert molding, the rotary bearing portion 12a has a circular hole 12c for holding the rotary shaft 1 and a ridge having a V-shaped cross section fitted in the groove 1a in the circumferential direction of the inner peripheral surface of the circular hole 12c. Part 12
d is formed corresponding to the rotating shaft 1.

Next, an injection gate 13a for injecting resin
And 13b will be described. In FIG. 2A, a resin molding die (not shown) for molding the housing 12 is
A cavity 1 that holds the rotating shaft 1 and that corresponds to the housing 12.
4 are formed. The injection gates 13a and 13b are provided outside the cavity portion 14.

The injection gates 13a and 13b are provided at two locations outside the outer periphery corresponding to the rotary bearing portion (12a) of the cavity portion 14 of the molding die and at symmetrical positions with respect to the rotary shaft 1, and these injection gates are provided. Direction X of the gates 13a and 13b for use
Are in the same direction and at the same angle with respect to the line connecting the injection gates 13a and 13b and the central axis 1b of the rotary shaft 1, for example, 30 degrees as shown in the figure.

The injection gates 13a and 13 having the above structure
An example of insert-molding the housing 12 integrally with the rotary shaft 1 using a resin molding die having b will be described.

The rotary shaft 1 is loaded in a predetermined position of the resin molding die. Then, the resin molding die is clamped to form the cavity 1
Inject resin into 4. At this time, the cavity 1 of the resin molding die
The resin injected into No. 4 is the injection gates 13a and 13b.
Is injected at an angle of 30 degrees with respect to a line connecting the central axis 1b of the rotary shaft 1 and is filled in the cavity portion 14 while rotating around the rotary shaft 1 in the clockwise direction (arrow Y in the figure). , The housing 12 is formed. Therefore, as shown in FIG. 2 (b), the orientation showing the filling state of the resin is determined by the rotation bearing (1
Between the outer circumference 14a and the circular hole 14b of 2a), a convex shape is formed in the resin flow direction and a rotational symmetry having a large number of symmetry axes. Therefore, it is difficult to form a weld line, and in the vicinity of the rotation axis 1, the orientation of the resin is substantially parallel to the circumference of the circular hole 12c.

In the rotary bearing device integrally formed with the rotary shaft 1 in this manner, the rotary shaft 1 made of a metal having a V-shaped groove 1a is made of a resin excellent in slidability. Since it is rotatably held by the portion 12a, the outer circumferential surface of the rotary shaft 1 and the circular hole 12c are securely fitted to each other to reliably remove the radial radial play, and the V-shaped groove 1a of the rotary shaft 1 is also removed.
Is surely brought into close contact with the ridge portion 12d on the inner peripheral surface of the rotary bearing portion 12a, and the axial thrust play is reliably removed. Therefore, the rotating shaft 1 smoothly rotates in a state of being held by the housing 12 without causing blurring or the like.

As the rotating shaft 1, it is possible to use a shaft made of a resin having high mechanical strength such as rigidity and excellent heat resistance, but in practical use, the rigidity and the like are higher than those of ordinary resins. It is preferable to use a rotating shaft made of metal, which has a large mechanical strength and heat resistance.

According to the present invention, since the injection direction of the resin is deviated from the central axis direction of the rotary shaft 1, the direct action of the injection pressure on the rotary shaft 1 is alleviated, and the outer shape of the rotary shaft 1 is reduced. Since the damage can be reduced, the applicability to the non-metallic rotating shaft 1 is enhanced.

Further, in the above embodiment, the case where the metal rotary shaft 1 in which the groove 1a having a V-shaped cross section is formed has been described, but the shape is not limited to the V-shaped cross section.
It is possible to use a rotary shaft in which grooves having various shapes such as a U shape, a semicircle shape, and a square shape are formed.

Further, the rotary shaft 1 is not limited to one having a groove formed therein, but a rotary shaft having a protrusion can be used. In this case, the rotary bearing portion 12a is formed with a groove corresponding to the protrusion of the rotary shaft 1.

Further, it is possible to use the rotary shaft 1 in which both the groove and the projection are formed. In this case, the rotary bearing portion 12a is provided with protrusions and grooves corresponding to the grooves and protrusions of the rotary shaft 1, respectively.

Further, the resin having lubricity is not limited to the resin used in the above-mentioned conventional example, but as the base material, for example, PPS resin, polyacetal resin, polybutyl terephthalate resin (PBT), nylon or the like is used. Materials for imparting lubricity, for example, PTFE resin, silicone resin, carbon fiber, molybdenum disulfide, etc., to materials for imparting mechanical strength, for example, glass fiber (GF), carbon fiber (lubricant (For example, PPS resin + GF)
+ PTFE resin + silicone resin) or the like can be used. Further, an appropriate amount of a mold release material may be kneaded with the molding resin.

Further, the injection direction of the injection gate is 3 in the present embodiment with respect to the line connecting the central axis 1b of the rotary shaft 1.
The angle is not limited to 0 degrees, and it may be displaced from the central axis 1b of the rotary shaft 1.

Further, although the present embodiment has been described by using the example in which the injection gates are provided at two places, it is also possible to provide the injection gates at one place or a plurality of places at three or more places. And if there are three or more injection gates,
All of the injection gates are located in the resin molding die at positions corresponding to the vicinity of the outer periphery of the rotary bearing portion 12a.
It is preferable that the injection directions of the injection gates are substantially equal to each other in the circumferential direction of the outer periphery and the same direction and the same direction are formed with respect to a line connecting the injection gate and the central axis 1b of the rotary shaft 1.

In this embodiment, the rotary shaft having a groove is insert-molded to form the rotary bearing portion integrally with the rotary shaft. However, the rotary bearing used for the rotary shaft having no groove or protrusion is described. The device is not limited to insert molding, but a housing having a cylindrical circular hole is molded using a resin molding die, and then a rotary shaft is fitted into the circular hole of the housing to form a rotary bearing device ( It is also possible to configure (not shown).

[0030]

As described above, according to the rotary bearing device of the present invention, the orientation of the resin in the vicinity of the circular hole in contact with the rotary shaft of the rotary bearing portion made of resin is set in the circumferential direction of the circular hole. It was formed substantially parallel. That is, the orientation of the resin was formed substantially parallel to the outer circumference of the rotation axis. Therefore, the circular hole of the bearing portion maintains a good roundness, and the rotation shaft can obtain smooth rotation.

Further, in the method of manufacturing the rotary bearing device according to the present invention, at the time of resin injection molding, the injection direction of the injection gate for injecting the resin into the resin molding die is shifted from the central axis of the rotating shaft, Since the direction of the resin flowing in the resin molding die is one direction along the outer circumference of the rotating shaft, and no weld line is formed in the rotary bearing part of the housing that holds the rotating shaft, the mechanical strength of the housing is improved. It has the effect of preventing deterioration. Furthermore, since the longitudinal direction of the fibers added to the resin and the rotation direction of the rotary shaft coincide with each other, the durability of the bearing portion can be further improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a cross section of an embodiment of a rotary bearing device according to the present invention and a position of an injection gate.

2 (a) is an explanatory view showing the position and injection direction of the injection gate corresponding to the BB cross section of FIG. 1, and the flow direction of the resin. (B) It is explanatory drawing which shows the orientation of resin in a BB cross section of FIG. 1 with a broken line.

FIG. 3 is an explanatory view showing a cross section of a conventional rotary bearing device and a position of an injection gate.

4 (a) is an explanatory view showing the position and injection direction of the injection gate and the resin flow direction in the case of one injection gate in the AA cross section of FIG. 3; (B)
It is explanatory drawing which shows the orientation of resin in FIG.

5 (a) is an explanatory diagram showing the position and injection direction of the injection gate and the resin flow direction when there are three injection gates in the AA cross section of FIG. 3; (B)
It is explanatory drawing which shows the orientation of resin in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotary shaft 1a protrusion (groove) 1b central shaft 12a rotary bearing part 12c circular holes 13a, 13b injection gate

Claims (4)

[Claims] 1. A rotary bearing device comprising a rotary bearing part made of a resin molded body having a circular hole and a rotary shaft held in the circular hole of the rotary bearing part. A rotary bearing device, wherein the orientation of the resin near the surface is substantially parallel to the circumferential surface of the circular hole. 2. A method for manufacturing a rotary bearing device comprising a rotary bearing part made of a resin molded body having a circular hole and a rotary shaft held in the circular hole of the rotary bearing part, wherein the rotary bearing part is made of a resin. A method of manufacturing a rotary bearing device, comprising: using a molding die, and shifting the injection direction of an injection gate of the resin molding die from the central axis of the circular hole. 3. A rotary bearing device, wherein at least a portion of a rotary shaft having a groove or a projection formed in a circumferential direction of an outer peripheral surface thereof is insert-molded with a resin, which corresponds to the rotary shaft. A rotary bearing device, wherein the orientation of the resin of the rotary bearing portion is substantially parallel to the outer peripheral surface of the rotary shaft. 4. A method of manufacturing a rotary bearing device, wherein at least a portion of the rotary shaft having a groove or a protrusion formed on the outer peripheral surface in the circumferential direction is insert-molded with a resin. A method of manufacturing a rotary bearing device, wherein the part is formed by using a resin molding die and shifting an injection direction of an injection gate of the resin molding die from a central axis of the rotating shaft.