JP3061089U - Injection mold structure - Google Patents

Abstract

(57) [Technical Problem] [Technical Problem] In an injection molding in which a guide rib is formed integrally with a part of a synthetic resin mechanical component, an injection molding die capable of forming a top surface of the guide rib into a smooth surface is obtained. SOLUTION: In an injection mold, a guide rib 1 is provided.
1 is formed so that the nesting of the nests is performed at a position other than the top surface 12 of the guide rib 11.

Description

[Detailed description of the invention]

[0001]

[Industrial applications]

 The present invention relates to an injection molding die used for injection molding of a synthetic resin molded product used for a copying machine, a printer, or the like.More specifically, a plurality of ribs are provided in a part of the synthetic resin molded product, and the top of the rib is provided. The present invention relates to an injection molding die for molding a synthetic resin molded article having a guide rib for moving a printing sheet while sliding a surface portion in a rib extension direction.

[0002]

[Prior art]

 In structures such as copiers and printers, several ribs are provided alongside some mechanical parts to reduce frictional resistance where printing paper moves. By using this as a guide rib, the contact area is reduced by sliding the top surface of the guide rib, and as a result, the frictional resistance is reduced and the printing paper can be moved smoothly.

When the above-mentioned mechanical parts are molded by an injection molding method, injection is performed according to the height of a guide rib in a space (hereinafter referred to as “cavity”) generated when the fixed mold and the movable mold are closed. The relevant part of the mold must be carved with a narrow and deep groove. There is an electric discharge machining method as such a method, but much time is required for machining time. Also, at the top surface of the guide ribs, that is, at the bottom of the groove of the injection mold, the gas generated during the injection molding is driven into the molten resin, which may cause a molded product to have a poor shape or cause burns. is there.

In order to improve the above, it has been considered to use a nest which is divided at the top surface 12 of the guide rib as shown in FIG. The division enables cutting, and the processing time can be shortened simply by forming one side of the guide ribs in a nested manner. Therefore, when assembling into an injection mold, a cavity with a deep groove can be obtained by abutting the nests of each other. In addition, a slight gap through which the molten resin does not pass was provided on the abutment surface between the nests so that the gas could escape from this gap.

However, in the cross-sectional view of the mechanical component 10 shown in FIG. 7 which is injection-molded by using the above-described method, at the abutting position of the nest of each other, a parting line as a butting mark is formed on the top surface 12 of the guide rib. Or a so-called burr 13 may be generated from the butted surface.

[0006] If any parting line or burr is formed on the top surface of the guide rib as described above, printing paper that slides on the top surface of the guide rib will be caught and cause trouble. Therefore, after the injection molding, the molding state of the guide rib portion must be checked each time, and secondary processing such as removing burrs is required. At the time of injection molding, injection conditions that must be managed, such as finer injection molding pressure, are added.

[0007]

[Problems to be solved by the invention]

 An object of the present invention is to provide a structure of an injection molding die that can form a smooth rib top surface without performing secondary processing for removing burrs generated on the top surface of the rib after injection molding. is there.

[0008]

[Means for Solving the Problems]

 In order to achieve the above object, in the structure of the injection molding die, in the invention according to claim 1, a projecting guide rib for a paper feed used in a paper feed unit of a copying machine, a printer, or the like. An injection molding die for injection-molding a synthetic resin molded product provided with a guide rib, wherein the nesting of the nests forming the guide ribs is performed at a position other than the top surface portion of the guide ribs. .

Further, in the invention according to claim 2, in the invention according to claim 1, the nesting part of the nests forming one of the guide ribs is one side surface of the guide rib, and further, It is characterized by a structure in which a curved portion of a curved surface forming a top surface portion and a straight line portion linearly extending from the curved surface to the bottom of the guide rib intersect.

Further, in the invention according to claim 3, in the invention according to claim 1 and claim 2, the thickness of the guide rib at the butting portion of the nest is such that the thickness of the top surface of the guide rib is reduced. It is characterized by a structure that is set equal to or smaller than the thickness of the guide rib body.

[0011]

[Action]

 The present invention is a guide rib that moves printing paper while sliding a plurality of ribs in a part of a synthetic resin mechanical part used for the structure of a copier, printer, etc., and sliding the top surface of the rib in the rib extension direction. This is a structure of an injection mold capable of forming a top surface of a guide rib on a smooth surface when injection molding a synthetic resin mechanism component having the following.

In the invention according to the first aspect, the nesting of the guide ribs, which has been conventionally performed at the top surface of the guide rib, is performed at a position other than the top surface of the guide rib, so that a parting line generated at the butted portion is formed. Even if traces or burrs occur, there is no effect on the slide of the printing paper, and secondary processing such as surface treatment and extra injection molding condition management can be omitted.

In the invention according to the second aspect, the contact surface of the nest is formed at a position where a curved surface forming the top surface of the guide rib and a side surface linearly extending from the curved surface to the bottom surface of the guide rib intersect. Such troubles may be located at other than the top surface of the guide ribs, and the processing becomes easier, so that the processing time for nesting can be reduced.

In the invention according to claim 3, the thickness of the butt portion of the nest is set to be equal to or smaller than the thickness of the guide rib body portion on the guide rib top surface side. It is possible to prevent the side surface of the guide rib from being undercut and hindering product removal after injection molding.

[0015]

[Embodiment of the invention]

 In an injection molding die in which a guide rib is formed integrally with a part of a synthetic resin mechanical part, the top surface of the guide rib can be formed into a smooth surface by using the injection molding die structure of the present invention. The embodiment will be described in detail with reference to the drawings.

[0016]

First Embodiment First, an embodiment according to claims 1 and 2 will be introduced. FIG. 1 shows a state in which a printing paper 20 moves while sliding on a top surface 12 of a guide rib 11 of a mechanical component 10 incorporated in a copying machine. It is a perspective view showing. A guide rib 11 is integrally formed on one surface of the mechanical component 10.

On the surface of the mechanical component 10, six guide ribs A11a. . . Guide ribs G11f are juxtaposed at approximately equal intervals, and the top surface portion 12 of each guide rib 11 has a curved surface shape in order to reduce friction with the printing paper 20. During printing, the printing paper 20 moves while sliding on the top surface 12 of the guide rib 11. The direction of the guide rib 11 is generally extended in the direction in which the printing paper 20 moves, but the mold structure of the present invention is effective in other directions.

FIG. 2 is a sectional view of the injection mold 30 of the present invention. The movable board side mold plate 31 incorporates a movable board side insert 32 forming the product surface of the mechanical member 10. One fixed platen side mold plate 33 incorporates a combination fixed platen side insert 34 for forming the shape of the back surface. The space formed by the movable side insert 32 and the combination fixed side insert 34 is a cavity 35, and the molten resin is filled to form the mechanical component 10. The configuration of the combination fixed board side insert 34 will be described. The nest A34a forms the left side shape of the mechanical component 10 in FIG. 2, and further forms a cavity for forming the guide rib A11a by abutting with the nest B34b.

Similarly, the guide rib B11b abuts the nest B34b and the nest C34c, and the guide rib C11c abuts the nest C34c and the nest D34b. You. Further, the right side shape of the mechanical component 10 is formed by the nest G34g.

A typical example of the butting of the combination fixed side inserts 34 will be described with reference to FIG. 3, which is an enlarged view of the guide rib A34a forming portion in FIG. The guide rib A11a formation portion is formed by abutting a nest A34a and a nest B34b. The nest A34a forms a left side surface 41, which is a straight portion of the guide rib A11a forming portion, and further forms a curved surface 42 of the top surface portion 12, and the nest B34b forms a right side surface 43, which is a straight portion. Therefore, since the curved portion and the linear portion are separated at the butting portion 44, the nesting can be easily performed, and the processing time can be reduced. As described above, other guide rib forming portions are similarly formed by combining the nests.

Using the injection molding die configured as above, using a polystyrene resin (Asahi Kasei VS712NHM2282) as the resin to be used, and using an injection molding machine (IS-550EN manufactured by Toshiba Machine Co., Ltd.) And injection molded. As a result, as shown in FIG. 6, the top surface portion 12 of the guide rib A11a is formed into a smooth surface, and the parting line 14 generated at the butt portion 44 of the nest is formed on the side surface of the guide rib A34a. A mechanical component 10 having no influence was obtained.

[0022]

Embodiment 2 Next, an embodiment according to claims 1 and 3 will be introduced. FIG. 4 shows the same guide rib A11a forming portion as FIG. In the thickness dimension of the guide rib A34a at the abutting portion 44 of the nest A34a and the nest B34b, a guide rib A34a is formed where the thickness m of the top surface of the guide rib is set smaller than the thickness n of the guide rib body. Other nest forming portions have the same dimensional relationship.

Injection molding was carried out in the same manner as in Example 1 except that the injection molding die configured as described above was used. As a result, undercutting does not occur at the butting portion of the nest, so that after the injection molding is completed, it is possible to easily remove the mechanical component from the injection molding die. Furthermore, the top surface of the guide rib was formed into a smooth surface, and the parting line generated at the butting portion of the nest was formed on the side surface of the guide rib, and a mechanical component having no effect on the slide of the printing paper was obtained.

[0024]

COMPARATIVE EXAMPLE 1 As shown in FIG. 5, the conventional nesting method of nesting was carried out except that an injection mold having a structure in which nesting A34a and nesting B34b were butted on the top surface 12 of the guide rib A11a was used. Injection molding was performed in the same manner as in Example 1. As a result, for example, parting lines and burrs 13 are formed on the top surface 12 of the guide rib 11a as shown in FIG. 7, and secondary processing such as removal with a cutter is required.

[0025]

[Effect of the invention]

 As described above, by using the injection mold having the structure according to the present invention, a mechanical component having a protruding guide rib for paper feed used in a paper feed unit of a copying machine, a printer, or the like can be obtained. The following effects can be obtained by injection molding. No parting line or burrs are formed on the top surface of the guide rib, so there is no need for secondary processing. b. Even if burrs occur, they will occur in places that do not affect the function, making it easier to manage injection molding conditions and the like during injection molding.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state in which printing paper moves on a top surface of a guide rib.

FIG. 2 is a cross-sectional view of an injection mold according to the present invention.

FIG. 3 is an enlarged view of a guide rib A forming portion in the first embodiment.

FIG. 4 is an enlarged view of a guide rib A forming portion in a second embodiment.

FIG. 5 shows a nested butting structure in a conventional method.

FIG. 6 is a cross-sectional view of a guide rib formed by the injection mold according to the first embodiment.

FIG. 7 is a cross-sectional view of a guide rib formed by an injection mold according to Comparative Example 1.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Mechanical components 11 Guide rib 12 Top surface part 13 Burr 20 Printing paper 30 Injection molding die 34 Combination fixed board insert 35 Cavity

Claims (3)

[Utility model registration claims] An injection molding die for injection molding a synthetic resin molded product having a protruding paper feeding guide rib used in a paper feeding section of a copying machine, a printer, or the like.
A mold for injection molding, wherein a structure in which nests of cavities forming guide ribs are mutually butted is set at a position other than a top surface of the guide ribs. 2. The nesting part of the nests forming the guide ribs is one side surface of the guide ribs.
2. The injection molding die according to claim 1, wherein the curved portion of the curved surface forming the top surface portion of the guide rib and the linear portion linearly extending from the curved surface to the bottom of the guide rib intersect. 3. The structure according to claim 1, wherein the thickness of the guide rib at the butting portion of the nest is equal to or smaller than the thickness of the guide rib in the direction of the top surface of the guide rib. The injection mold according to claim 2.