JP2003033947A - Tubular resin molding, its manufacturing method and mold for it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To widely improve a molding accuracy of a gear part by preventing a progression of local solidification of a resin in a mold cavity and enabling sufficiently transmission of a filling pressure over the whole of a mold cavity. SOLUTION: A gear part 2 of one end portion and an inward flange 3 and a tubular part 1 are integrally formed, the inward flange 3 is formed in an outer end part of the gear part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tubular resin molding having a gear portion and an inward flange on at least one end portion, and a tubular portion which is integral with the gear portion, a method for molding the same, and a method for using the same. With regard to a molding die, in particular, the molding precision of the gear portion is greatly improved.

[0002]

2. Description of the Related Art For example, an outer peripheral surface of a cylindrical base portion is formed by molding a conductive resin material into a substantially cylindrical shape and has a gear portion and an inward flange at one end portion and an inward flange at the other end portion. A photosensitive layer is formed on the surface,
In a tubular resin molded body applied as a photoconductor drum for electrophotography or the like, integration of a cylindrical substrate portion and a gear portion is usually performed by separately molding those, welding in a subsequent assembly,
It is performed by adhesion or the like, or by integral molding in the molding cavity.

[0003]

However, in the former case in which a separate molded article is post-assembled, the equipment cost, the assembly cost, etc. are increased as compared with the latter case in which they are integrally molded. Inevitably, the cost of the tubular resin molded body itself increases, and there is a problem that the dimensional accuracy of the tubular resin molded body varies depending on the assembly accuracy.

On the other hand, in the latter case where integral molding is performed, the molding accuracy of the cylindrical base body such as the diametrical dimension and cylindricity is balanced with the molding accuracy such as the gear engagement ratio and the pitch. There was a problem that it was difficult to take.

That is, in the first place, the conventional tubular resin molded body formed by integral molding has a gear portion 31 at the end and a cylindrical base portion 32 continuous to the gear portion 31 as shown in the sectional view of FIG. And a structure in which an inward flange 33 having a boss is provided at a position closer to the cylindrical base portion than the gear portion 31, a resin molded body having such a structure is formed into a molten resin into a molding cavity. In forming the material by injection molding, as shown in FIG. 5, the gate 3 is connected to the inward flange forming portion 35 of the molding cavity 34.
When injecting the molten resin material through 6, the injected resin branches from the inward flange forming portion 35 to the gear portion forming portion 37 and the cylindrical base portion forming portion 38 and flows, For this reason, if the gear portion forming portion 37 having a small volume is filled with the resin material early and the resin material cannot flow into the gear portion forming portion 37 thereafter, the resin material flows into the cylindrical base portion forming portion side. The resin solidification in the gear portion forming portion 37 progresses even though the above is still continuing.

Therefore, the filling pressure as shown by the arrow in FIG. 6, which acts on the resin material only when the entire molding cavity 34 is completely filled with the molten resin material, promotes early solidification of the resin. It is not sufficiently transmitted to the gear portion forming portion 37, which results in that the molding precision of the gear portion is greatly reduced as compared with that of the cylindrical base portion in which the filling pressure acts sufficiently.

Therefore, the present invention prevents the progress of local solidification of the resin in the molding cavity and enables sufficient transmission of the filling pressure over the entire molding cavity, thereby molding accuracy of the gear portion. (EN) Provided are a cylindrical resin molded product capable of greatly improving the temperature, a molding method thereof, and a molding die used therefor.

[0008]

A tubular resin molded body according to the present invention is formed by integrally forming a gear portion and an inward flange of at least one end portion and a tubular portion, and a boss portion. Is formed at the outer end portion of the gear portion, that is, at the outer end portion in the axial direction of the gear portion or in the vicinity thereof.

Further, according to the present invention, there is provided a method for molding a tubular resin molded product, which has a gear portion and an inward flange at least at one end portion thereof, and a tubular resin molding which is integral with them. In molding the body in the molding cavity, the molten resin material injected through the gate into the inward flange forming portion of the molding cavity is made to flow down to the tubular portion forming portion via the gear portion forming portion.

According to the above-mentioned structure of the tubular resin molding, the molten resin material can be flowed down from the inward flange forming portion to the gear portion forming portion of the molding cavity to the tubular portion forming portion according to the invention of this method. As a result, the resin material is prevented from prematurely accumulating in the gear part forming part of the molding cavity, and the resin is made to flow to the gear part forming part while the tubular part forming part is sufficiently filled with the resin material. Therefore, the filling pressure after the entire molding cavity is completely filled with the molten resin material can be reliably transmitted to the gear part forming portion, and the molding accuracy of the gear part can be greatly improved.

Further, the molding die according to the present invention has a molding cavity of a tubular resin molding having a gear portion and an inward flange at least at one end portion and having a tubular portion integral with the gear portion and the inward flange. The gear cavity forming portion is continuously provided at the end of the tubular portion forming portion of the molding cavity, and the inward flange forming portion is communicated with the outer end portion of the gear portion forming portion or in the vicinity thereof. It is a thing. According to this molding die, the tubular resin molding according to the present invention can be manufactured by reliably implementing the above method.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of a tubular resin molding according to the present invention, in which a gear portion 2 and an inward flange 3 with a boss are provided at one end of a tubular portion 1.
FIG. 5 is a perspective view showing a case in which an inward flange 4 with a boss is provided at the other end, respectively, and this molded body 5 which can be entirely formed of a conductive resin material.
2, an inward flange 3 is formed at the outer end in the axial direction of the gear portion 2 provided continuously to one end of the tubular portion 1 or in the vicinity thereof, as shown in the axial sectional view of FIG. It has a structure that consists of

Here, although the inward flange 3 shown in the drawing is joined to the outer end of the gear part 2, the boss part 3 thereof is formed.
Between a and the gear part 2, there is an annular recess 3b that is somewhat recessed inward in the axial direction.

A molding die which can be used for molding the tubular resin molded body 5 having such a structure has a molding corresponding to the shape of the resin molded body 5 as shown in the sectional view of FIG. In addition to having a cavity 11, for defining the molding cavity 11, a core mold 12 for specifying the inner surface shape of the molded body 5, a cavity mold 13 for specifying the outer peripheral surface shape of the tubular portion 1, and a gear portion. 2, which specifies the outer surface shape of 2 and the outer surface shape of the inward flange 3,
A gate mold 16 having a resin injection gate 15.

Each of these molds 12, 13, 14,
Mold cavity 1 here defined by 16
1 is a gear portion forming portion 22 which is formed continuously from an end portion of a tubular portion forming portion 21 sandwiched between a core die 12 and a cavity die 13 and whose outer surface is specified by a gear die 14.
And has an inward flange forming portion 23 which is sandwiched between the core die 12 and the gate die 16 and extends radially inward from the outer end portion of the gear portion forming portion 22, and the other inward flange 4 of For forming, it has an inward flange forming portion (not shown) extending inward in the radial direction from the other end of the tubular portion forming portion 21.

According to such a molding die 17, the molten resin material injected from the resin injection gate 15 into the inward flange forming portion 23, as shown by the arrow in the figure, extends from the inward flange forming portion 23 to the gear portion forming portion 22. And flows down to the tubular portion forming portion 21 to gradually fill the molding cavity 11 from the downstream side thereof.
Before the above condition is satisfied, the resin does not stay in the gear part forming portion 22, and therefore the early solidification of the resin does not proceed.

Therefore, the filling pressure after the molding cavity 11 is completely filled is sufficiently transmitted to the gear portion forming portion 22, and the resin of the portion 22 is large on the molding surface of the gear mold 14. Since it is pressed by force, the gear part 2 can be molded with high accuracy.

[0018]

As described above, according to the present invention, the local solidification of the molten resin material in the molding cavity is prevented, and the sufficient filling pressure is transmitted to the entire molding cavity. In particular, the molding accuracy of the gear part can be greatly improved.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a tubular resin molded body.

FIG. 2 is a cross-sectional view of a main part of FIG.

FIG. 3 is a cross-sectional view of essential parts showing an embodiment of a molding die.

FIG. 4 is a partial cross-sectional view of a conventional resin molded body.

FIG. 5 is a cross-sectional view of a molding cavity showing a resin flow state.

FIG. 6 is a cross-sectional view showing a working state of a filling internal pressure.

[Explanation of symbols]

1 tubular part 2 gears 3,4 Inward flange 3a Boss 3b annular recess 5 molded body 11 Molding cavity 12 core type 13 cavity type 14 Ga type 15 Resin injection gate 16 gate type 17 Mold 21 Cylindrical part forming part 22 Gear part forming part 23 Inward flange forming part

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 3J030 BA01 BB18 BC01 BC08 BD02                       BD06                 3J103 AA02 AA74 EA02 FA18 GA02                       HA41                 4F202 AG09 AG24 AH12 CA11 CB01                       CK02 CK06 CK11                 4F206 AG09 AG24 AH12 JA07 JL02                       JM04 JN11 JQ81

Claims (3)

[Claims] 1. A tubular resin molded body formed by integrally forming a gear portion and an inward flange of at least one end portion and a tubular portion, wherein the inward flange is provided at or near an outer end portion of the gear portion. A tubular resin molded body formed. 2. In molding a tubular resin molded body having a gear portion and an inward flange at least at one end portion and having a tubular portion that is integral with the gear portion and the inward flange in the molding cavity, A method for molding a tubular resin molded body, in which a molten resin material injected into an inward flange forming portion is caused to flow down to a tubular portion forming portion via a gear portion forming portion. 3. A molding die having a molding cavity of a tubular resin molding having a gear portion and an inward flange on at least one end portion, and a tubular portion integral with the gear portion, the molding die comprising: A molding die in which a gear portion forming portion is continuously provided at an end portion of a cylindrical portion forming portion of a cavity, and an inward flange forming portion communicates with an outer end portion of the gear portion forming portion or in the vicinity thereof.