JP2002181163A - Pinion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pinion capable of using a simple molding die, reducing the man-hour for molding, and realizing a substantially longitudinal pinion of high quality regardless of a length of a gear part to a run off. SOLUTION: This pinion 10 has at least two axially connected gear parts 2 and at least one run off part 3 mounted between the gear parts 2, and an end face part of the gear part 2 facing to the run off 3 has a tapered slant 4 expanded toward a bottom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pinion, and more particularly to a pinion having a long axial length.

[0002]

2. Description of the Related Art Pinions formed of a resin material are widely used in various fields. Normally, since it is difficult to open the molding die of this pinion after molding, after molding, the pinion is extruded in the axial direction without being opened, and is taken out of the molding die.

However, when molded by such a method,
In the case of the type having a long axial direction, molding is difficult, and there is a problem in molding accuracy. Therefore, as shown in FIGS. 6 and 7, for example, a pinion 100 having a gear that is long in the direction of the axis 101 and having a relief portion 103 between gear portions 102 has been developed.

Normally, in this type of pinion 100, molds 104 and 105 for forming a gear portion 102 and a relief portion 103 are separately formed as shown in FIG. 8, for example. Then, as shown in FIG. 2A, a resin monomer is injected and solidified into the cavity of the molding die. After forming the pinion 100 in this manner, FIG.
As shown in FIG.
Pull 5 and open. Thereafter, as shown in FIG. 4C, the pinion 100 is removed from the mold 104 so as to be pushed out in the axial direction.

However, in such a method, when the pinion 100 is pushed out in the axial direction and passes through the molding die 104 on the gear portion 102 side, the end face of the gear portion 102 may be damaged. That is, when the end face of each gear part 102 enters the molding die 104 on the side of the adjacent gear part 102 due to a displacement or the like at the time of extrusion, the end face of the molding die 104 comes into contact with and is damaged.

Therefore, for example, Japanese Patent Application Laid-Open No. Hei 6-147295
A method for manufacturing a pinion as described in Japanese Patent Application Laid-Open No. H10-209,837 has been proposed. That is, in this manufacturing method, as shown in FIG. 9, for example, a mold in which the molding die 106 on the gear portion 102 side and the molding die 107 on the escape portion 103 side are separated is used. And
As shown in FIG. 2A, after molding, first, only the molding die 107 on the escape portion 103 side is pulled out and opened (FIG. 2B). Thereafter, the pinion 100 is pushed out and moved by a certain amount in the axial direction so that the gear portion 102 of the pinion 100 temporarily comes to the place where the extracted mold 107 on the escape portion 103 side is located (FIG. )).
Next, in this state, the molding die 10
6 is also pulled out and opened (FIG. 4D), and finally, the pinion 100 is extruded in the axial direction and taken out of the mold.

[0007] However, this conventional method has a limitation that it is necessary to form the escape portion longer than the gear portion. In addition, since the mold must be pulled out in two stages, the number of molding steps is increased, which is troublesome.

[0008]

SUMMARY OF THE INVENTION In view of the above circumstances, the present invention can reduce the number of molding steps and the number of molding steps by simplifying the molding die, and is not restricted by the length of the gear portion with respect to the escape portion. The aim is to provide a high quality pinion with a long axis type.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a pinion having at least two gear portions connected in the axial direction and a small-diameter relief portion provided between the gear portions. In the cross section in the direction, a slope is formed to increase the tooth width as approaching the axis.

[0010] The inclined surface may be formed on at least one of the gear portions other than the gear portion at the most distal end in the extrusion direction when the gear portion is removed from the molding die after molding.

The inclined surface can be formed on at least the surface on the upstream side in the extrusion direction at the time of removal from the molding die after molding, of both end surfaces of the gear portion.

[0012] The slope of the end face of the gear portion facing the relief portion may be, for example, a part of a conical surface that is rotationally symmetric about the axis of the pinion.

It is preferable that the diameter of the relief portion is smaller than the diameter of the gear root circle of the gear of the gear portion.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2
Indicates a pinion 10 according to the present invention. The pinion 10 is of a type that is long in the direction of the shaft 1, and has at least two gear portions 2 in the axial direction, and a small-diameter relief portion 3 is provided between the gear portions 2. .

The gear portion 2 is formed so that the diameter D1 of the root circle is slightly larger than the diameter D2 of the escape portion 3, and a clearance S exists between the two (D1-D2 = S). On both end surfaces of the portion 2, inclined surfaces 4 are formed in the axial cross section to increase the tooth width as approaching the axis.

The inclined surface 4 of this embodiment is formed by a part of a rotationally symmetric conical surface centered on the axis of the pinion for each tooth 2A of each gear portion 2, and is extruded from the molding die 6. At the time of removal, even if the inclined surface 4 (tooth bottom 4A side) of the gear portion 2 comes into contact with the inner peripheral surface 62A (see FIG. 5) of the second molding die 62 for molding the gear portion 2 described later, Shift and guide smoothly.

The slope 4 is formed on at least one of the gear portions 2 other than the tip portion 21 in the extrusion direction at the time of removal from the molding die 6 after molding. The portion 2 is formed at least on the upstream side surface in the extrusion direction. In addition to the shape of the slope 4, in addition to the shape as in this embodiment,
In the axial cross section, the tooth width may be increased as approaching the axis.

The relief portion 3 corresponds to a missing portion of the gear portion 2. For example, when this portion meshes with a helicoid screw as a meshing partner, the clearance with the helicoid screw must be considered. No. According to the present pinion 10, while maintaining the clearance,
The strength of the gear portion can be increased. That is, in the case where the tooth tip portion has the required meshing length L while maintaining the clearance with the preceding helicoid screw, in the gear portion 2 of this embodiment, the tooth width of each gear portion 2 is reduced. Since it is expanded toward the tooth bottom, the average tooth width of each gear portion 2 is smaller than that of the conventional gear having the same meshing length and the same dimension (rectangular cross section) from the tooth tip to the tooth bottom. Can be increased.
Therefore, the strength of each tooth can be increased. In addition, there is no limitation on the taper angle of each gear portion 2 as compared with the conventional gear having the same strength as described above, and the strength of the gear portion is more marginal than that of the conventional gear (rectangular cross section). Therefore, it is also possible to increase the taper angle and reduce the strength to the extent that it does not compete with the design value. This increases the degree of freedom in designing the shape of the gear portion.

Therefore, the pinion 10 according to this embodiment is
According to the above, even when the gear portion 2 comes into contact with the second molding die 62 and is scratched (turned) when being pushed out from the second molding die 62 for molding the gear portion 2 and the like, FIG.
As shown in (1), the tooth bottom 4A of the slope 4 which first comes into contact is damaged. That is, in actual use, the gear 5A (see FIG. 3) of the mating gear 5 does not mesh with the tooth bottom 4A, so that there is a possibility that the meshing operation may be inconvenient at the time of meshing. Absent. As a result, it is possible to realize a product of good quality with respect to the type that is long in the direction of the axis 1 and to increase the degree of freedom in design and the versatility.

Next, a method of manufacturing the pinion 10 according to this embodiment will be described with reference to FIG. The molding die 6 used in this manufacturing method includes a rod-shaped first molding die 61 for molding the hollow shaft 1 and a second molding die 61 for molding the gear portion 2.
A molding die 62 and a third molding die 6 for molding the relief 3
3 is provided.

The second molding die 62 is formed in a shape in which the tip end facing the cavity is widened forward. In addition,
When the pinion 10 is extruded and formed after being molded, the second molding die 62 is moved in the direction of retreating from the pinion 10 (X direction in FIG. 4A) and is not opened without being moved. Pinion 1 through the mold
Remove 0.

On the other hand, the third molding die 63 is
In order to make up for the gap, the front end portion facing the cavity is formed in a shape narrowing toward the front. This third molding die 63
When extruding the pinion 10 by extrusion after molding,
The direction of retreating from the pinion 10 as before (see FIG.
(See FIG. 2) to open the gear unit 2 so that the gear unit 2 can pass therethrough.

The pinion 10 is formed as follows using the above-described mold. A predetermined molding die 6 is prepared, and a synthetic resin monomer is injected into the cavity and solidified (see FIG. 4A). After solidification, the third molding die 63 for molding the relief portion 3 is opened (see FIG. 4B). An extrusion sleeve (not shown) is prepared and one end of the solidified pinion is extruded (see FIG. 4C).
At this time, the second mold 62 is not opened, but the pinion 10 is kept in a constant posture so as not to fluctuate in the circumferential direction, so that the gear portion 2 of the pinion 10 is moved in the cavity of the second mold 62. Let through. Normally, the solidified molding material does not come into contact with the molding die 6 due to shrinkage after molding, and thus can be easily passed.

[0024]

According to the present invention, there is provided a pinion having at least two gear portions connected in the axial direction and a small-diameter relief portion provided between the gear portions, and the end face of the gear portion facing the relief portion. In the section, in the axial cross section, a slope that widens the tooth width as approaching the shaft is formed, so it is a simple molding die, and without increasing the molding man-hour, it is substantially a long shaft type and high quality. Pinions can be obtained at low cost. In addition, since it can be formed without being restricted by the length of the gear portion with respect to the escape portion, the degree of freedom in design is increased, the versatility is improved, and the strength can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a pinion according to the present invention.

FIG. 2 is a sectional view of the pinion shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a state in which the pinion shown in FIG. 1 is meshed with a mating gear.

FIGS. 4A to 4C are process diagrams showing a method for forming the pinion shown in FIG. 1;

FIG. 5 is an explanatory view showing the operation of the pinion according to the present invention.

FIG. 6 is a perspective view showing a conventional pinion.

FIG. 7 is a sectional view of the pinion shown in FIG. 6;

FIGS. 8A to 8C are process diagrams showing a conventional molding method.

FIGS. 9A to 9D are process diagrams showing another conventional molding method.

[Explanation of symbols]

 Reference Signs List 1 shaft 10 pinion 2 gear part 2A each tooth 21 one at the foremost end of gear part 2 in the pushing direction 3 relief part 4 slope 4A tooth bottom 5 mating gear 6 molding die 62 (for gear part molding) second molding die 62A Inner peripheral surface 63 (for molding relief part) Third mold

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Norio Sato 2-36-9 Maenocho, Itabashi-ku, Tokyo Asahi Gaku Kogyo Co., Ltd. F-term (reference) 3J030 BA01 BB09 BC01 BC10 4F202 AH12 CA01 CB01 CK13 CK43 CK54

Claims (5)

[Claims] 1. A pinion having at least two gear portions connected in the axial direction and a small-diameter relief portion provided between the gear portions, wherein an end face of the gear portion facing the relief portion has an axial direction. A pinion having a cross section formed with a slope that increases the tooth width as approaching the axis. 2. The pinion according to claim 1, wherein the inclined surface is formed on at least one of the gear portions other than the one on the most extruded side in the extrusion direction when the gear portion is removed from the molding die after molding. . 3. The method according to claim 1, wherein the inclined surface is formed on at least an upstream surface of an end surface of the gear portion in an extrusion direction when the gear portion is removed from the molding die after molding. The described pinion. 4. The device according to claim 1, wherein the slope of the end face of the gear portion facing the relief portion is a part of a conical surface that is rotationally symmetric about a pinion axis. Item 2. The pinion according to item 1. 5. The pinion according to claim 1, wherein the diameter of the relief portion is smaller than the diameter of the gear root circle of the gear portion.