JPS59156708A - Molding die for bowl-shaped article having undercut inside - Google Patents

Abstract

PURPOSE:To enable a molded piece A to be taken out easily from the molds although it is provided with an undercut part by a method wherein the 1st die and the 2nd die comprising a split male die for molding an inner wall are moved inward from the molded piece. CONSTITUTION:A closed cavity 41 is provided by a nut molding die 20, a female die 14, a slide core for a screw 29, an inner wall molding male die 34 and a bottom molding male die 32. Under a state where dies are closed, plastic material is injected from a runner groove 16 into the cavity 41 through a pin point gate 19, cooled, hardened and molded. Then, for the purpose of taking out the molded piece, the movable plate 25 of the die is moved to the left to open the space between a receiving plate 26 and a male die supporting plate 27. Thus, an expanding member 39 is pulled out from between the 1st die and the fixing part 33 of a bottom part molding male die 32 and the expanding member 40 of a nut molding die 20 is pulled out of a die piece 21a. The nut die 23 of the die piece 21a is released from the female screw of the molded nut 9.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a mold for injection molding for molding a bowl-shaped article having an undercutter (1 to 1) on the inner wall thereof, and particularly to a mold for molding a bowl-shaped article such as a magic bottle or the like. The purpose of this invention is to provide a mold suitable for molding the bottom of a liquid container.

In general, liquid containers such as magic bottles have a roughly disc-shaped bottom at the bottom end of a roughly cylindrical body, and due to its structure, a multi-M undercut is formed. However, in recent years, with the diversification of the design of liquid containers, many liquid containers with outer shells whose outer shape has changed and are close to spherical are now in use.Figure 1 shows a diagram of such a liquid container. As an example, this shows the structure of the bottom of a magic hob.The exterior body 1 consists of a body 2 and a bottom body 3, and an inner bottle 4, which is a vacuum double layer, is housed within the exterior body 1. , and is supported by a shoulder (not shown) on the upper part of the body 2 and a thin sill 5 screwed into the center of the bottom body 3.

By the way, in this type of liquid container 4, since it is necessary to store the inner bottle 4 inside the outer case 1, it is necessary to divide the outer case 1 into the body 2 and the bottom body 3 at its maximum diameter, and the position thereof is as follows. Since the exterior body will be heated to medium heat, the bottom body 3 must be approximately bowl-shaped. Since the joint between the body 2 and the bottom body 3 has a high joint strength and a simple structure,
It is preferable that a male thread 6 protruding from the upper end of the bottom body 3 and a female thread 7 formed on the inner surface of the lower end of the body 2 be screwed together. On the other hand, due to design constraints, the outer peripheral surface of the joint between the body 2 and the bottom body 3 is required to form a continuous curved surface.

In such a structure, conventionally, the inner surface of the bottom body 3 is shaped to be continuous with the inner surface of the male screw 6, as shown by the chain line in FIG. 1, and a shape is adopted that prevents undercutting. was. However, the thickness of the threaded part between the body 2 and the bottom body 3 is the sum of the thickness of the piece 2 and the thickness of the bottom body 3, so the inner surface of the bottom body 3 is connected to the inner circumference of the male thread 6. If the shape is continuous with the surface, the thickness of the bottom body 3 directly under the H1 screw 6 will become extremely large, causing unsightly sink marks on the outer peripheral surface of the bottom body 3, which will significantly reduce the commercial value of the liquid container. It was. In conventional general liquid containers, the bottom body constitutes the bottom of the liquid container, and
``Although it was unnoticeable in appearance and sink marks were rarely a problem,'' in a liquid container with a spherical appearance like the one shown in item 2, the bottom body 3; Moreover, the sink mark appears in a conspicuous central part of the exterior body 1, resulting in an extremely unsightly appearance. Therefore, in the bottom body 3 of a liquid container as shown in FIG. 1, it is necessary to form an undercut 8 at the bottom of the male thread 6 to make the thickness of the bottom body 3 uniform and to prevent sink marks. It will be done.

Furthermore, for a simple bowl-shaped article, it is not so difficult to form the undercoat 1 to 1, but for a liquid container such as a magic bottle, the thin clay rest 5 is formed in the center of the bottom body 3. A nut 9 for screwing is provided, and when molding the bottom body, the undercut of the thread of the nut 9 must also be molded. Therefore, the range of movement of the split mold for molding the undercut portion 8 is significantly limited.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide an injection molding die suitable for molding the bottom body 3 of a liquid container having a complicated shape as described above. It is something to do.

FIG. 2 is a central longitudinal cross-sectional view of the injection mold 10 of the present invention. Reference numeral 11 denotes a fixing plate in which a sprue bush 1 mating hole 12 is formed. Reference numeral 13 denotes a female mold holding block, which is installed so as to be able to move toward and away from the fixing plate 11. Inside the solid holding block 13, there is a female mold 14 for molding the outer peripheral surface and bottom surface of the molded product. However, this female type holding block 1
It is held together with 3. A runner plate 15 is fixed to the back surface of the female mold, and a runner groove 1G is carved on the back surface. Also, a runner hole 17 is bored through the female mold 14 from the tip of the runner groove 16, and a molding surface 18 is formed.
It opens to form a 'C bottle point cage 19.

A female thread mold 20 is provided in the center of the female mold 14 to form a female thread on the inner surface of the pull nut 9. ζ A pair of mold pieces 218 facing each other in the front and rear directions with respect to the plane of the paper in FIG.
'r 2 l b can be slid obliquely along a guide 22 formed on the inclined side surface of the mold piece 2'la. The front outer periphery of the mold pieces 21a and 21b forms a molding surface, and a female thread mold 23 for molding the l-thread on the inner surface of the nut 9 is carved therein. 24 is an angular pin fixed to the female holding block 13.

On the other hand, 25 is a movable plate. The movable plate 25 has a receiver [
A plate 26 is fixed to the front part of the plate 26.
The receiver is provided with a plate 26 and a die holding plate 27 that can be moved into and out of contact with the female die holding block 13. A holding member 28 is fixed to the front surface of the male holding plate 27,
Further, on the front surface thereof, a two-piece male screw slide core 29 is slidably held with respect to the holding member 28.A slanted through hole 30 is bored in the male screw slide core 29. The inner periphery of the male screw slide core 29 forms a molding surface, and a male screw mold 31 is carved therein to form the threads of the male screw 6 of the molded product. There is.

32 is a bottom molding kF type for molding the inner bottom part of a 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 die holding plate 27. There is. 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. This inner wall molding male mold 34 is made up of two different shaped mold pieces, as shown in FIG. No. 34, which is one mold piece. The inner circumference of a is wider than the second outer circumference, and the second mold 311, which is the other mold piece, has an outer circumference wider than the inner circumference. The first mold 34a and the second mold 34b are arranged alternately and slidably in close contact with each other on both sides thereof, and their outer peripheral surfaces form a continuous curved surface, and the molding The inner wall surface of the product is molded. Thus, the inner peripheral wall of the molded product to be molded by the inner wall acid mold 34 includes the portion 8 to the undercut 1. Also, each type 34a
The second mold 34b has an oval-shaped cross section, and has an outwardly projecting projecting portion 35 extending from its rear portion, and a bottle 36 is planted on 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 rotary ring 37, and each groove 38 has a plurality of grooves 38 formed therein.
are fitted. In addition, the groove 38 may be replaced with the sulin 1~.

As shown in FIG. 4, the grooves 38 are alternately provided with grooves 38a having a small angle α with the radial direction of the rotary ring 37 and grooves 38b having a large angle α.
a has the above-mentioned type 34. The bottle 36 planted in the groove a and the bottle 36 planted in the second mold 34b are fitted in the groove 38b so as to be slidable along the grooves 38a and '38b, respectively.

The overhanging portion 35 of the second mold 34a1 and the second mold 34b
The male die holding plate 27 and the holding member 28 allow the rotating ring 37 to
8 and is held so that it can move back and forth.

Reference numeral 39 denotes a substantially wedge-shaped expansion member, which is fitted between the second mold 34a and the fixing portion 33 of the male bottom molding mold 32, and its rear end is fixed to the front surface of the plate 26. .

Further, 40 is an expansion member of the screw mold 20,
The tip is approximately wedge-shaped and is fitted between the mold pieces 218.

Figure 2 shows the mold closed. The state is shown, and the above-mentioned part thread molding mold 20, 111 mold 14, male thread slide core 29
A sealed cavity 41 is formed by the male inner wall mold 34 and the male bottom mold 32 . With the mold closed, plastic material is injected from the runner groove 16 through the runner hole 17 and through the bin point gate 19 into the cavity 41 to fill the cavity 41. The rustic material is cooled and solidified to form a molded product.

Next, when taking out the molded product, first the movable plate 25 of the mold
is moved to the right as shown in FIG. 2, and the receiver opens between the plate 26 and the male holding plate 27. As a result, the expansion member 39
is the fixing part 33 of the second mold 34a and the bottom molding male mold 32.
The expansion member 40 of the female thread mold 20 is also pulled out from between the mold pieces 21a. Then, the mold pieces 21a are brought close to each other, and the female thread type 23 of the mold pieces 21a is separated from the female thread of the nut 9 of the molded product.

Next, move the male retaining plate 27 to the right in FIG. The fixed plate 11 and the female mold holding block 13 are opened by moving in the same direction at a speed lower than that of the fixed plate 11 and the female mold holding block 13. At this point, the gap between the fixing plate 11 and the female mold holding block 13 is opened, so that the plastic material is cut at the bin point gate 19 and the sprue and runner are taken out.

In addition, the slide core 29 for male screw and the side mold holding 10 pieces 13
By opening the space between them, the space between the molded product and the female mold 14 opens, the molded product comes out of the female mold, and the inner wall molded male mold 3
4 and the bottom male mold 32. As the molded product moves, the mold piece 21b can move along with the molded product due to the undercut of the thread on the inner surface of the nut 9, but since the direction of the movement is diagonal, the interval becomes smaller as it moves. becomes smaller, and the female screw mold 23 of the mold piece 21b separates from the female screw. Also, slide core 2 for male thread
By opening the space between 9 and the female mold holding block 13,
The through hole 30 of the male screw slide core 29 slides along the angular pin 24, the two-split mold opens, and the male screw mold 31 separates from the outer peripheral surface of the male screw 6 of the molded product.

Once the mold has been fully assembled, the rotary ring 37 is removed by means of the rack 43 and pinion 44 shown in FIGS. 4 and 6.
is rotated using the center axis of the mold as the rotation axis. Due to this &thus, the bottle 36 slides along the groove 38 or the groove 3
Since the direction 8 is inclined with respect to the radial direction of the rotation ring 37, the first mold 34a and the second mold 34b are each moved inward of the inner wall molding male mold 34.

At this time, since the angle that the groove 38a makes with the radial direction of the rotary ring 37 is smaller than the groove 37b, the first mold 34a
Since the moving speed of the second die 34b is faster than that of the second die 34b, and the inner circumference of the first die 34a is wider than the outer circumference, the first die 34a expands before the second die 34b. As the opening member 39 moves toward the empty space left after being pulled out and the second mold 34a moves, the second mold 34a moves toward the gap created between the first mold 34a and the second mold 34b. Type 34b
will begin to move slowly. As a result, each of the first molds 34a1 and the second molds 34b is separated from the undercut portion 8 of the inner wall of the molded product.

This state is shown in FIGS. 5 and 6.

That is, the molded product A is separated from the female thread mold 2OS female mold 14, the male thread slide core 29, and the inner wall mold male mold 34, and is supported only by the bottom mold male mold 32. Here, the molded product A can be ejected using the ejector pin 4°2 shown in FIG. 3 and taken out from the mold.

The sprue and runner B are also removed and prepared for the next molding process.

In the present invention, the inner wall molding male mold 34 is a split mold,
Individual first mold 34a and second mold 34b that constitute the split mold
moves inward from the molded product A, so even if the molded product A has an undercut portion 8, the molded product A can be easily removed.
can be removed from the mold. Further, in the present invention, the first mold 34a and the second mold 34b are operated by a rotary ring 37, and the rotary ring 37 can be easily operated from outside the mold. As in the embodiment, the center part of the male mold is occupied by the fixing part 33 of the bottom molding male mold 32 and the expansion part 40 of the cervix screw molding mold 20, and the first mold 3
Even in a mold structure in which the mold 4a and the second mold 34b cannot be operated from the inside, they can be operated in a small space, which is extremely convenient.

[Brief explanation of the drawing]

FIG. 1 is a central vertical cross-sectional view of the bottom of a magic bottle, which is an example of the use of a molded product molded according to the present invention. 2 to 6 show one embodiment of the mold of the present invention, and FIG. 2 is a sectional view taken along the line ■-■ in FIG. 4, and FIG. 3 is a cross-sectional view taken along Figure 4 shows the
It is a sectional view taken along IV-IV in the figure. Figures 5 and 6
The figures show the open state of the mold, Figures 2 and 4, respectively.
It is a drawing similar to the figure. A...Molded product 8...Undercut portion 32...Bottom molding male mold 34...
...Inner wall molding male mold 34, a...first mold 34
b... Second type 36... Bin 37.
... Rotating ring 38 ... Concave groove

Claims (1)

[Scope of Claims] 1. A male mold for molding the inner surface of the bowl-shaped article includes a bottom molding male mold for molding the bottom of the bowl-shaped article, and an inner wall molding male mold for molding the inner side walls, and the inner wall acid- Type male. The molds include a plurality of first molds whose inner peripheries are wider than their outer peripheries;
A split mold in which a plurality of second molds are alternately arranged and are slidably in close contact with the side surface of the mold and whose outer periphery forms a molding curved surface continuous with the outer periphery of the first mold. A rotary ring is disposed on the back surface of the mold and the second mold so as to be rotatable about the central axis of the mold, and the rotary ring has a small angle with respect to the E44 radial direction. Two types of grooves or slits are formed alternately, pins protruding from the back surfaces of the first and second molds are slidably fitted into the grooves or slits, and the rotating ring is By rotating, the first mold and the second mold are moved in the radial direction of the mold, and the moving speed is faster than the second mold due to the difference in the angle of the groove or slit. A mold for forming a bowl-shaped article having an undercut on the inside.