JPH0525645B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of an injection mold for molding a bowl-shaped article having a female thread in the center of the bottom, and particularly to a liquid container such as a magic bottle. The purpose of this invention is to provide a mold suitable for molding the bottom body of.

In a liquid container such as a magic bottle, as shown in FIG.
is stored, and the shoulder part (not shown) of the upper part of the torso 2,
It is supported by a tightening body 5 screwed into the center part of the bottom body 3. Therefore, in the center of the bottom of the bottom body 3,
A cylindrical female threaded portion 6 for screwing the tightening body 5 is provided, and a female threaded portion 7 is provided on the inner periphery of the female threaded portion 6.
is engraved. As shown in FIG. 2, this internal thread 7 is usually provided with ratchet protrusions 8 at several locations in order to prevent the tightening body 5 from loosening.

Generally, when molding an article with a female thread, a male thread is carved into the mold, the molded product is molded on the male thread surface, and after molding, the molded product is rotated and extracted from the mold to remove the molded product. Here and there is being done. However, as mentioned above, the female thread 7
If the ratchet protrusion 8 is formed on the mold, the ratchet protrusion 8 is undercut in the direction of rotation, so that it is not possible to rotate the molded product and remove it from the mold. Therefore, it is necessary to use a split mold for the part for molding the female thread 7.

Conventionally, the structure of such a split mold is that the mold for this part is divided into four pieces, and a pair of opposing mold pieces of the split mold is first moved inward, and then the other pair of pieces are moved inward. By moving the mold pieces inward,
The molded product was removed from the mold. However, with this structure, since the two pairs of mold pieces are moved separately, it takes time to open the mold, making it impossible to speed up the molding cycle.

However, it is not so difficult to do so if the bottom body is attached to the lower end of a cylindrical body, like conventional liquid containers. However, in recent years, with the diversification of liquid container designs, a large number of liquid containers whose external shapes are approximately spherical have come into use. What is shown in FIG. 1 is a magic bottle as an example of such a liquid container. In this type of liquid container, in order to store the inner bottle 4 inside the outer case 1, it is necessary to divide the outer case 1 into a body 2 and a bottom body 3 at its maximum diameter. Since the bottom body 3 is located almost in the center, the bottom body 3 has no choice but to be approximately bowl-shaped. Also, due to design constraints, the outer peripheral surface of the joint between the body 2 and the bottom body 3 is
It is required to form a continuous curved surface.

Since the body 2 and the bottom body 3 are screwed together with screws, an undercut portion 9 is formed below the male threaded portion on the outer periphery of the bottom body 3, and the wall thickness changes locally, causing unsightly sink marks. It is necessary to prevent
Therefore, when molding the bottom body of the liquid container as described above, it is necessary to operate the split mold also to mold this undercut portion 9, and the movement range of the split mold for molding the female thread is limited. is severely restricted.

The present invention has been made in consideration of such circumstances, and provides a structure of an injection mold for a bowl-shaped article, which is suitable for molding the bottom body 3 of a liquid container having a complicated shape as described above. The purpose is to provide

Accordingly, in the present invention, a female mold for molding the outer surface of the bowl-shaped article and a male mold for molding the inner surface are installed so as to be separable from each other, and the female mold molds the outer peripheral part of the bowl-shaped article. and a female thread mold for forming a female thread at the center of the bottom of the bowl-shaped article. It is a split mold in which molds and second molds are arranged alternately, and the first mold is wide at the rear and narrow at the front, and has sloping side surfaces, and the molds extend in the direction of separation from each other. The second mold is movable and always urged in the approaching direction, and is expanded by an expansion member penetrating the male mold and recessed between the first molds, and the second mold The first mold and the second mold are slidable diagonally forward along the side surface thereof, and a female thread mold is carved into the outer peripheral surfaces of the first mold and the second mold to form a female thread on the inner surface of the female thread portion of the bowl-shaped article. When the mold is opened, the expansion member comes out from between the first molds, the first molds approach each other, the female thread mold separates from the female thread, and then the molded product moves forward together with the male mold, thereby tightening the female thread of the molded product. The second die moves obliquely along the side surface of the first die together with the first die to reduce the distance therebetween, and the female threaded portion separates from the female thread.

The structure of the mold of the present invention will be explained in detail below with reference to the drawings.

FIG. 3 is a central vertical sectional view of the injection molding die 10 of the present invention. 11 is a fixing plate in which a sprue bush fitting hole 12 is formed. Reference numeral 13 denotes a female holding block, which is provided so as to be able to move toward and away from the fixed plate 11. Inside the female mold holding block 13, a female mold main body 14 for molding the outer peripheral surface and bottom surface of the molded product is held integrally with the female mold holding block 13. The front surface of the female mold body 14 is engraved with a molding surface for molding the outer peripheral surface of the bottom body. Further, a runner plate 15 is fixed to the back surface of the female mold main body 14, and a runner groove 16 is carved in the back surface of the runner plate 15. Further, a runner hole 17 is bored through the female mold body 14 from the tip of the runner groove 16, and the molding surface 1
8 to form a pinpoint gate 19.

A female thread mold 20 is fitted into the center of the female mold main body 14 to form a female thread 7 on the inner surface of the female thread portion 6 in the molded product. The female thread mold 20 is made of a quarter mold, and a first mold 21a, which is a pair of opposing mold pieces, is connected to the runner plate 1.
It is possible to move toward and away from each other with respect to 5.
Each of the first molds 21a has a generally trapezoidal shape with a wide rear end and a narrow front end, and its side surfaces form inclined surfaces. The second mold 21b, which is the other pair of opposing mold pieces, is connected to the first mold 21.
It is designed to be able to slide obliquely back and forth along a guide 22 formed on the slanted side surface of a.
The front outer circumferences of the first mold 21a and the second mold 21b form molding surfaces, and a female thread mold 23 for molding the female thread 7 on the inner surface of the female thread portion 6 is carved therein. 2
4 is an angular pin fixed to the female holding block 13.

On the other hand, 25 is a movable plate. A receiving plate 26 is fixed to the front surface of the movable plate 25.
A male mold holding plate 27 which can be moved into and out of contact with the receiving plate 26 and the female mold holding block 13 is provided at the front part of the housing. A holding member 28 is fixed to the front surface of the male holding plate 27, and a two-piece slide core 29 is fixed to the front surface of the male holding plate 27.
It is held slidably against the An inclined through hole 30 is bored in the slide core 29, and the angular pin 24 is inserted therethrough. Further, the inner periphery of the slide core 29 forms a molding surface, and is engraved with a male thread mold 31 that forms the thread of the male thread of the molded product.

Reference numeral 32 denotes a bottom molding male mold for molding the inner bottom part of the molded product, and a fixing part 33 is erected on the back of the central part thereof, and the rear end of the fixing part 33 is fixed to the male mold holding plate 27. ing. Reference numeral 34 denotes an inner wall molding male mold for molding the inner peripheral wall portion of the molded product, and in this embodiment, it is an eight-split mold. As shown in FIG. 6, this inner wall molding male mold 34 is made up of two different shaped mold pieces. One mold piece 34a has an inner circumference wider than an outer circumference,
Conversely, the outer circumference of the other mold piece 34b is wider than the inner circumference. The mold pieces 34a and 34b are arranged alternately and slidably close to each other on both sides thereof, and their outer peripheral surfaces form a continuous curved molding surface, It is designed to mold the inner wall surface of the molded product. The undercut portion 9 is included in the inner peripheral wall of the molded product to be molded by the inner wall molding male mold 34. Each of the mold pieces 34a and 34b has a substantially L-shaped cross section, and has an outwardly extending projecting portion 35 at the rear thereof, and a pin 36 is implanted in the back surface of the projecting portion 35. .

Reference numeral 37 denotes a rotary ring provided on the back surface of the male mold 34 for molding the inner wall, and is rotatably provided around the central axis of the mold as a rotary axis. A plurality of grooves 38 are formed on the front surface of the rotating ring 37, and the pin 36 is fitted into each groove 38. Note that a slit may be formed instead of the groove 38.
As shown in FIG. 6, the groove 38 has a small angle α with the radial direction of the rotating ring 37.
a and 38b with a large angle α are provided alternately, the pins 36 implanted in the mold piece 34a are placed in the groove 38a, and the pins 36 implanted in the mold piece 34a are placed in the groove 38b.
The pins 36 implanted in b are respectively connected to the grooves 38.
a and 38b so as to be slidable.
The overhanging portions 35 and rotating ring 37 of the mold pieces 34a, 34b are integrally formed with the male mold holding plate 27 and the holding member 28, and can be moved forward and backward. It is maintained so that it can be moved.

Reference numeral 39 denotes an expansion member for the inner wall molding male mold, which is approximately wedge-shaped, and is connected to the mold piece 34a and the bottom molding male mold 3.
2, and its rear end is fixed to the front surface of the receiving plate 26. Reference numeral 40 denotes an expanding member of the female screw mold 20, the tip of which is approximately wedge-shaped.
a, passes through the center of the fixing portion 33 of the male bottom molding die 32, and its rear end is fixed to the front surface of the receiving plate 26.

FIG. 3 shows the mold in a closed state, and the cavity 41 is sealed by the female thread mold 20, the female mold main body 14, the slide core 29, the inner wall molding male mold 34, and the bottom molding male mold 32. is formed. With the mold closed, plastic material is injected from the runner groove 16 through the runner hole 17 and into the cavity 41 through the pinpoint gate 19, filling the cavity 41, and cooling the plastic material. Let it solidify and form a molded product.

Next, to take out the molded product, first move the movable plate 25 of the mold to the right in FIG. 3 to open the space between the receiving plate 26 and the male mold holding plate 27. As a result, the expansion member 40 of the female thread mold 20 is pulled out from between the first mold 21a, and the expansion member 39 of the inner wall molding male mold is also moved between the mold piece 34a and the fixing part 3 of the bottom molding male mold 32. It is pulled out from between. The first molds 21a are moved toward each other by the elasticity of the spring 43, and the female thread mold 23 of the first mold 21a is connected to the female thread 7 of the female thread portion 6 of the molded product.
be forced to leave.

Next, the male mold holding plate 27 is moved to the right in FIG.
3 is also moved in the same direction at a speed lower than that of the male die holding plate 27 to open the space between the fixed plate 11 and the female die holding block 13. Here, by opening the space between the fixed plate 11 and the female holding block 13,
The plastic material is cut at the pinpoint gate 19 and the sprue, runner B, is removed.

By opening the space between the slide core 29 and the female mold holding block 13, the molded product A is held in a male mold by the male screw and the undercut portion 9,
Moves with the male type. On the other hand, since the female mold main body 14 is held by the female mold holding block 13,
The space between the molded product A and the female mold body 14 opens, and the molded product A
is separated from the female mold body 14 and moves along with the inner wall molding male mold 34 and the bottom molding male mold 32. As the molded product A moves, the undercut of the female thread 7 on the inner surface of the female thread portion 6 causes the second mold 2 to
1b moves to the right in FIG. 3 along with the molded product A, but since the direction of movement is diagonal along the guide on the side of the first mold 21a, the interval becomes smaller as it moves. , the female thread die 23 of the second die 21b is separated from the female thread 7.

On the other hand, by opening the space between the slide core 29 and the female holding block 13, the through hole 30 of the slide core 29 slides along the angular pin 24, the two split molds open, and the male thread mold 31 opens. It separates from the outer peripheral surface of the male thread of the molded product. When the mold is fully opened, the rotary ring 37 is rotated about the central axis of the mold by means of a rack 44 and a pinion 45 shown in FIG. As a result, the pin 36 slides along the groove 38, but since the direction of the groove 38 is inclined with respect to the radial direction of the rotation ring 37, the mold piece 34a and the mold piece 34
b are each moved inward of the inner wall molding male mold 34. At this time, since the angle formed by the groove 38a with the radial direction of the rotary ring 37 is smaller than that of the groove 38b, the moving speed of the mold piece 34a is lower than that of the mold piece 34.
The moving speed of the mold piece 34a is higher than the moving speed of the mold piece 34a, and the inner circumference of the mold piece 34a is wider than the outer circumference.
4a precedes the mold piece 34b, and the expansion member 39
The mold piece 34b moves slowly toward the gap formed between the mold piece 34a and the mold piece 34b. As a result, each mold piece 34a, mold piece 3
4b separates from the undercut portion 9 of the inner wall of the molded product.

This state is shown in FIG. That is, the molded product A is separated from the female thread mold 20, the female mold main body 14, the slide core 29, and the inner wall mold male mold 34, and is supported only by the bottom mold male mold 32.
In addition, since the male die of the molded product A is tightened by contraction during molding, the molded product A will not fall off even if the engagement at the male thread and undercut 9 is released, and will not adhere to the bottom molded male die 32. There is. Here, the molded product A is ejected by the ejecting pin 42 shown in FIG. 6 and separated from the bottom molding male mold 32, so that the molded product A can be taken out from the mold.
The sprue and runner B are also removed and prepared for the next molding cycle.

In the present invention, the female thread forming die 20 is a split die, and the individual first die 21a and second die 21b constituting the split die move inward from the female thread 7 of the molded product A. Even if the product A has a female thread 7 that becomes an undercut, the molded product A can be easily removed from the mold. Further, in the present invention, the first mold 21 of the female thread molding mold 20
Only the operation of moving a is required, and the second type 2
1b automatically moves inward when the mold is opened and detaches from the female thread 7, so the mold opening operation is easy and can be done in a short time, improving the molding cycle. . In addition, the structure of the mold is simple, and as in the embodiment described above, most of the male mold is occupied by the mechanism for molding the undercut portion 9, and the female thread molding mold 20 must be accessed from the fixed plate side. Even if the mold has a structure that makes it impossible to operate, it can be operated in a small space, which is extremely convenient.

[Brief explanation of the drawing]

FIG. 1 is a central longitudinal cross-sectional view of the bottom of a magic bottle, which is an example of the use of a molded product according to the present invention. FIG. 2 is a central vertical sectional view of the female threaded portion 6 of the bottom body in FIG. 1. Figures 3 to 7 show one embodiment of the mold of the present invention.
4 and 4 are cross-sectional views, respectively, of FIG. 6, and FIGS. 5 and 6 are cross-sectional views, respectively, of FIG. 3. FIG. 7 is a drawing similar to FIG. 3, showing the mold in an open state. A...Molded product, 6...Female thread part, 7...Female thread, 14...Female mold body, 20...Female thread mold,
21a...first type, 21b...second type, 23...
Female thread type.

Claims (1)

[Claims] 1 A female mold for molding the outer surface of the bowl-shaped article and a male mold for molding the inner surface are installed so as to be separable from each other, and the female mold is connected to a female mold main body 14 for molding the outer periphery of the bowl-shaped article. , female threaded part 6 at the center of the bottom of the bowl-shaped article
The female thread mold 20 is fitted into the center of the female mold main body 14, and a plurality of first molds 21a and second molds 21b are arranged alternately. The first mold 21a is wide at the rear, narrow at the front, and has slanted side surfaces, and is movable in the directions of moving away from each other and always moving toward each other. The second mold 21b is urged along the side surface of the first mold 21a and is expanded by an expanding member 40 that penetrates the male mold and is recessed between the first molds 21a. The first die 21a and the second die 21b are capable of sliding diagonally forward, and have a female thread die 23 carved on the outer circumferential surfaces of the first die 21a and the second die 21b for forming the female thread 7 on the inner surface of the female thread portion 6 of the bowl-shaped article. When the mold is opened, the expanding member 40 comes out from between the first molds 21a, so that the first molds 21a approach each other and the female screw mold 23
is detached from the female thread 7, and then the molded product A moves forward together with the male mold, so that the second mold 21b advances diagonally along the side surface of the first mold 21a together with the female threaded portion 6 of the molded product A. A mold for forming a bowl-shaped article having a female threaded portion at the center of the bottom, characterized in that the female threaded portion 23 separates from the female threaded portion 7 by reducing the distance therebetween.