JPH06170852A - Production of molded internal threaded body and mold therefor - Google Patents

Abstract

PURPOSE:To obtain an internal thread production method for easily molding an internal threaded body and a mold therefor. CONSTITUTION:In the molding of a molded internal threaded body 10 having an internal thread part wherein a helical part is formed on the inner wall surface thereof, a core 12 is inserted to a cavity formed by closing molds for molding the molded internal threaded body 10. The core 12 is formed by mounting a cylindrical part 16 on a core main body 14. On the outer peripheral side face of the cylindrical part 16, a helically projected and recessed part made of an elastic body which can be elastically deformed is formed for molding the helical part. Next, after a resin charged into the cavity is set, the fitted state of the helical part forming the internal threaded part with the helically projected and recessed part of the cylindrical part is released. The molds are opened while the cylindrical part 16 is so deformed that the core 12 can be extracted from the molded internal threaded body 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an internal thread molded body and a molding die therefor, and more specifically to a method for molding an internal thread molded body having an inner threaded portion with a spiral portion formed on the inner wall surface. The present invention relates to a method for manufacturing a screw molded body and a molding die therefor.

[0002]

2. Description of the Related Art In recent years, various bottles have been molded by injection molding. Therefore, a cap that seals the mouth of the bottle is also being formed by injection molding. Since such a cap is an internally-threaded molded product having an internally-threaded part with a helical part formed inside the cap, a spiral concavo-convex part that forms the helical part is formed on the outer peripheral surface during cap molding. After the core portion is inserted into the cavity of the molding die, the cavity is filled with resin. However, when the mold is opened, in order to take out the molded body from the molding die, it is necessary to first pull out the core portion from the molded body. However, since the spiral concavo-convex part formed on the outer peripheral surface of the core part and the spiral part of the inner screw part are in a fitted state, even if a tensile force is simply applied in the axial direction of the core part, It cannot be pulled out easily from the department.
For this reason, conventionally, when molding an inner screw molded body, a ball screw that rotates with the back-and-forth movement of the movable plate is provided, and when the mold is opened, the ball screw is rotated in order to rotate the core portion in the pulling direction from the inner screw portion. A molding die formed by connecting a core part and a core part is used (for example, Japanese Utility Model Laid-Open No. 2-59907 and Japanese Utility Model Laid-Open No. 3-1018).

[0003]

According to the molding die using the ball screw, a spiral portion having a sharp and accurate pitch is formed on the inner wall surface, and an inner thread molded body having a high sealing property can be molded. However, the use of ball screws is
In addition to complicating the structure of the molding die to reduce the handleability, the cost of the molding die is increased. In addition, some of the inner thread molded products are used for applications that do not require a high degree of sealing performance. Therefore, using a molding die for inner thread molded products that has a simple structure and is easy to handle, It has been desired to propose a simple manufacturing method for a screw molded body. Therefore, an object of the present invention is to provide a method for manufacturing an inner thread molded body that can easily mold the inner thread molded body, and a molding die thereof.

[0004]

In order to achieve the above-mentioned object, the inventor of the present invention is able to pull out from the inner screw portion of the molded body without rotating the core portion at the time of mold opening, The present invention has been achieved as a result of an examination considering that it is advantageous to make the core portion deformable. That is, according to the present invention, when molding an inner thread molded body having an inner threaded portion in which a spiral portion is formed on the inner wall surface, the inside of the cavity formed by closing the molding die for molding the inner threaded molded body. Into the core body, insert a core portion, which is made of an elastically deformable elastic body, and has a cylindrical portion formed on the outer peripheral side surface of the spiral concave-convex portion for molding the spiral portion. After solidifying the resin filled in, the fitting state between the spiral portion forming the inner screw portion and the spiral uneven portion of the cylindrical portion is canceled so that the core portion can be extracted from the inner screw molded body, A method for manufacturing an inner screw molded body is characterized in that the cylindrical portion is deformed and the mold is opened.

Further, according to the present invention, in a molding die for molding an inner screw molded body having an inner threaded portion in which a spiral portion is formed on the inner wall surface, a movable mold and a fixed mold for molding the inner screw molded body are formed. A spiral concavo-convex portion formed of an elastic body that is elastically deformable and forms the spiral portion at the tip of a core body that is inserted into a cavity formed by mold closing and is slidable in the mold opening / closing direction. A core part having a cylindrical part formed on the outer peripheral side surface, a spiral part forming the inner screw part and a spiral irregular part of the cylindrical part when the movable mold and the fixed mold are opened. And a tubular portion deforming means for deforming the tubular portion so that the fitted state can be eliminated and the core portion can be pulled out.

[0006]

According to the present invention, since the cylindrical portion on which the spiral concave and convex portions forming the spiral portion are formed on the outer peripheral surface is made of the elastically deformable elastic body such as rubber, It can be deformed to such an extent that the fitting state between the spiral concavo-convex portion of the tubular portion and the spiral portion forming the inner screw portion can be eliminated. Therefore, the core portion including the tubular portion can be easily pulled out from the inner screw portion of the molded body without rotating, and the structure of the molding die can be simplified without the need for a rotating member that rotates the core portion. The operation of the molding die can also be simplified. Further, the once deformed tubular portion easily returns to its original shape by releasing the deforming force applied to the tubular portion, so that it can be immediately used for the next molding. Thus, according to the present invention,
In combination with facilitating the handling of the molding die, the inner screw molded body can be easily molded.

[0007]

The present invention will be described in more detail with reference to the drawings. FIG. 1 is a partial sectional view showing a molding die according to an embodiment of the present invention. In the molding die shown in FIG. 1, a core portion 12 that protrudes from a movable die parting line and protrudes into a cavity formed by a movable die and a fixed die (not shown) is attached to the movable die. This core portion 12 is
A core portion main body 14 that is slidably attached to the movable die in the die opening and closing direction, and a tubular portion 16 that is attached to the tip of the core portion body 14 that protrudes from the movable die parting line into the cavity. Consists of. The cylindrical portion 16 has one end fixed to the vicinity of the tip of the core portion main body 14 and the other end fixed to a movable type, and a spiral uneven portion forming a spiral portion of an inner screw portion is formed on the outer peripheral side surface. ing. Furthermore, since the tubular portion 16 is formed of an elastically deformable elastic body such as silicone rubber, the cylindrical portion 16 expands and contracts as the core body 14 slides in the mold opening and closing direction, and is formed on the outer peripheral side surface. Shape changes. That is, when the protruding length of the core portion main body 14 protruding from the movable parting line is shortened, the overall length of the tubular portion 16 is shortened, and the unevenness difference between the convex peaks of the spiral concave and convex portion and the concave bottom surface becomes large, On the other hand, when the protruding length of the core portion main body 14 becomes long, the entire length of the tubular portion 16 is extended, and the unevenness difference of the spiral uneven portion becomes small.

The molding die used in this embodiment has a cylindrical portion 16
It is possible to mold the inner screw molded body by utilizing the expansion and contraction of
The molding state is shown in FIGS. First, the tubular portion 16 is shortened by shortening the protruding length of the core portion main body 14 protruding from the movable parting line.
The unevenness difference of the spiral uneven portion formed on the outer peripheral side surface of No. 4 is made equal to the unevenness difference of the spiral portion of the inner screw portion to be formed. afterwards,
The cavity is formed by closing the movable die and the fixed die, and the core portion 12 is projected and filled with resin to be solidified [FIG. 1 (a)]. Next, when the movable die moves in the die opening direction to open the die, the core portion main body 14 stops at the position when the die is closed, that is, in the inner screw portion of the molded body 10.
Therefore, the cylindrical portion 16 having one end fixed to the vicinity of the tip of the core portion main body 14 and the other end fixed to the movable mold is extended as the movable mold moves. Therefore, the spiral concave-convex portion formed on the outer peripheral side surface of the tubular portion 16 is gradually extended and flattened along the circumferential surface of the core portion main body 14 as the tubular portion 16 is extended, and the spiral of the tubular portion 16 is formed. The fitting state between the concave-convex portion and the spiral portion of the inner screw portion is gradually eliminated (FIGS. 1B and 1C).

When the spiral irregularities of the tubular portion 16 are flattened over the entire length of the tubular portion 16, the core portion 12 can be easily pulled out from the inner screw portion of the molded body 10 [FIG. d)]. Since the tubular portion 16 deformed into the shape shown in FIG. 1D is made of an elastically deformable elastic body, the tubular portion 1
When the tension applied to 6 is released, it contracts, and as shown in FIG. 1 (a), a spiral uneven portion is formed on the outer peripheral side surface, so that the next molding can be performed immediately.
The cylindrical portion 16 used in this embodiment can be molded by injection molding an elastic resin such as silicone rubber using a mold molded into the shape of the inner screw portion to be formed.

Although the tubular portion 16 shown in FIG. 1 is a tubular body, as shown in FIG. 2, the tubular portion of the bag body 26 can be used to form the inner thread molded body 20. The core part 22 constituting the molding die shown in FIG. 2 includes a core part body 24 slidably provided in the mold opening / closing direction with respect to the movable mold, and a tip part of the core part body 24 protruding into the cavity. A bag body 26 in which the peripheral portion of the mouth is fixed to the movable type so that it can be freely moved in and out.
It consists of and. The bag body 26 is made of an elastically deformable elastic body such as silicone rubber, and on the outer peripheral side surface of the cylindrical portion thereof, a spiral concave-convex portion that forms a spiral portion of the inner screw portion of the molded body 20 is formed. . Further, an air discharge hole 28 is formed in the core body 24, and a suction port of the air discharge hole 28 is opened in the tip surface of the core body.

Inner screw molded body 2 using such a molding die
When molding 0, the tip of the core portion main body 24 is inserted into the bag body 26 so that the bag body 26 is not deformed by the resin pressure filling the cavity. Then, the core portion 22 is inserted into the cavity, and the resin is filled into the cavity and solidified [FIG. 2 (a)]. Next, after moving the core main body 24 in the mold opening direction in the mold closed state to form a space in the bag 26 [FIG. 2 (b)], air in the space is provided in the core main body 24. The air is discharged through the air discharge hole 24 to reduce the pressure in the space. For this reason, the side surface of the bag body 26 is deformed inward in a concave shape. Due to the deformation of the bag body 26, the spiral concave-convex portion formed on the outer peripheral side surface of the bag body 26 is separated from the spiral portion of the inner screw portion of the molded body 20, and the fitting state between them is eliminated [FIG. (C)]. When the movable die is moved and the die is opened while maintaining the state of the bag body 26 thus deformed, the core portion 22 can be pulled out from the inner screw portion of the molded body 20. When the depressurized state in the bag body 26 is returned to the normal pressure state after the core portion 22 is pulled out from the inner thread portion of the molded body 20, the shape of the bag body 26 is easily restored to the original shape [FIG. )]. Therefore, the next molding can be immediately performed. The bag body 26 shown in FIG. 2 can be easily formed by injection molding an elastic resin such as silicone rubber, using a mold molded into the shape of the inner screw portion to be formed.

[0012]

According to the present invention, an inner thread molded body having an inner threaded portion can be molded without rotating the core portion, and the structure of the molding die can be simplified. Therefore, the handling of the molding die becomes easy, and the inner screw molded body can be easily molded.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating an operation of a molding die according to an embodiment of the present invention.

FIG. 2 is an explanatory view illustrating an operation of a molding die according to another embodiment of the present invention.

[Explanation of symbols]

 10, 20 Inner screw molded body 12, 22 Core portion 14, 24 Core portion main body 16 Cylindrical portion 26 Bag body 28 Air exhaust hole

Claims (2)

[Claims] 1. When molding an inner screw molded body having an inner threaded portion having a spiral portion formed on an inner wall surface, the cavity is formed in a cavity formed by closing a molding die for molding the inner threaded molded body. A core portion formed by mounting a tubular portion, which is made of an elastically deformable elastic body and has a spiral concave-convex portion formed on the outer peripheral side surface to form the spiral portion, on a core portion main body, and then inserts the core portion into the cavity. After the filled resin is solidified, the fitting state between the spiral portion forming the inner screw portion and the spiral uneven portion of the tubular portion is canceled so that the core portion can be extracted from the inner screw molded body. A method for manufacturing an inner screw molded body, which comprises opening the mold while deforming the tubular portion. 2. A molding die for molding an inner screw molded body having an inner threaded portion having a spiral portion formed on an inner wall surface, which is formed by closing a movable mold and a fixed mold for molding the inner screw molded body. The spiral concave and convex portion formed of an elastically deformable elastic body and forming the spiral portion is formed on the outer peripheral side surface at the tip end of the core portion main body that is inserted into the cavity and is slidable in the mold opening and closing direction. With the core portion to which the formed tubular portion is attached, and when the movable die and the fixed die are opened, the fitting state of the spiral portion forming the inner screw portion and the spiral concavo-convex portion of the tubular portion is shown. A molding die for an inner screw molded body, comprising: a tubular portion deforming means for deforming the tubular portion so that the core portion can be pulled out.