JPS606415A - Mold apparatus for producing item with constricted section such as teat and the like - Google Patents

Abstract

PURPOSE:To obtain a mold for injection molding a teat or the like, by making the mold of a male mold in conformity with the inner shape of the intended item and a female mold in conformity with the outer shape of the intended item, and making the male mold of a tapered or straight rodlike matal core that can pass into the constricted section of the female mold and a rubber cover that covers the metal core. CONSTITUTION:A male mold 4 has a shape in conformity with the inner shape an item 8 to be molded that is thin wall and hollow and has a constricted intermediate section such as teat, and a female mold 3 has a shape in conformity with the outer shape of the item. The male mold 4 consists of a tapered or rodlike metal core 21 that can pass into the constricted section of the female mold and a rubber cover 7 that covers the core 21 to form the male mold surface, and is flexible and heat resistant. Rubber is injected into the cavity 9 to obtain the intended item such as a teat. Thus, by using rubber for an injection mold, the release can be facilitated.

Description

[Detailed Description of the Invention] The present invention relates to a hollow, thin-walled rubber molded product such as a nipple or a beetroot, which has a constriction that is υ narrower than the tip between the tip and the bottom. (hereinafter referred to as a product with a constricted part).

Generally, in order to mold a hollow product with a constricted part using a so-called mold, the mold corresponding to the outer surface of the product (called a female mold because it has essentially four parts) is divided at at least one place. Or a mold corresponding to the inner surface (
The male type (called the male type because it essentially has a convex part) must be divided into many pieces. This is because the large tip of the male mold hits the constriction of the female mold, making insertion and withdrawal physically impossible.

However, when the female mold is divided, traces of the stepped pattern remain on the outer surface of the product along the mold seams (parting lines), which may cause defects in appearance and functionality depending on the product. turn into. Similarly, when dividing the male type, -'! - In addition to leaving traces of tinting lines, the mold structure becomes extremely complex, which is often practically impossible for small products.

For this reason, conventional products with this type of constriction have had to be manufactured using a male mold by a dipping method using latex or rubber solution.

The present invention is an apparatus for manufacturing this type of nipple or pacifier with a constricted part (hereinafter referred to as nipples) by molding, and is particularly suitable for injection molding of liquid rubber with low molding pressure. This is what we provide. That is, when molding a molded product with a constriction as described above, the present inventor believes that if it is possible to use a material that is easily deformable into a male shape, such as rubber, as a temporary material, the deformability of the material can be improved. It is possible to insert and extract the female mold,
.

In addition, even though the molding is performed using a relatively low molding pressure, it is desirable that the male mold is not easily deformable during molding.Only during molding, the rubber material used as the male mold is The double-layer molding is supported by supporting it with a rigid body to restrain its deformation, and the rigid body of the lining is removed when inserting and extracting from the female mold, so that the easily deformable property can be fully utilized. We decided to solve this problem through structure. Therefore, the gist of the present invention is to provide an injection mold device for manufacturing a thin-walled hollow object having a constriction in the middle, in which a male mold has a shape matching the inner surface shape of the object, and a female mold has a shape that matches the inner surface shape of the object. The mold is provided to have a shape that matches the external shape of the object, and the male mold has a metal core material in the shape of a tapered or straight bar that passes through the constriction of the female mold, and the core material is covered to cover the surface of the male mold. The mold device is characterized by being provided with a two-layer structure consisting of a rubber cover with high flexibility and heat resistance.

The mold according to the present invention will be explained below with reference to the figures, with reference to an example of a nipple.

Reference numeral 1 is a mounting plate for mounting the female mold on the movable plate of the injection molding machine, and reference numeral 2 is a mounting plate for mounting the male mold on the fixed plate of the injection molding machine. 3 is a female-shaped body having a cavity 9 shaped to match the outer surface of the product. Reference numeral 4 designates a male core material portion, which is designed to form a protrusion corresponding to the inner surface of the product using a protrusion 21 combined with a rubber mold 7. Reference numeral 5 denotes an intermediate plate which is firmly fixed to the rubber mold 7 and its bottom. The surface facing the female mold still has the design required for the bottom of the product.

A vulcanized rubber mold 7 constitutes the main part of the present invention, covers the protrusion 21 of the male core portion 4, and is integrated with the mold 7 to have a shape corresponding to the inner surface of the product. In this case, the protrusion 21 is straight, has a heel shape, or has a slightly tapered column shape that is easy to remove. The internal shape of the rubber mold 7 is equal to or slightly smaller than the protrusion 21, so that when the protrusion 21 is inserted, the two parts are surely brought into close contact. Further, it is firmly fixed to the intermediate plate 5 at the end of the bottom opening. Fixing methods include a simple incision method, a method of embedding a metal insert in the bottom of a rubber mold, and a method of fixing this insert and the intermediate plate 5 with a delt, and a method of gluing. 8 is a product molded by this mold. 6 is a push gourd for forming a groove (mold material injection port) 11 through which material is injected through the male core part 4 and the intermediate plate 5; It has a nozzle receiver recess 10 for contacting the injection nozzle to close the mold. Further, an undercut 12 is provided in the female mold portion corresponding to the other end of the pusher for taking out the material remaining in the stripe after vulcanization molding. 13 is a runner that does not humiliate the material from sujiru 11 to cavity 9, and 1
Reference numeral 4 indicates an r-t through which material is injected from the runner 13 into the cavity 9. Reference numeral 15 denotes an air hole provided in the protrusion 21 of the male core portion 4, which communicates with the outside of the mold and is used to adjust the air pressure between the protrusion 21- and the inner surface of the rubber mold 7. It is connected to vacuum, normal pressure, and pressurized air piping. Reference numerals 16 and 17 denote O-rings attached to the side surfaces of the male core part 4 and the intermediate grate 5, which ensure airtightness between the male core part 4 and the rubber mold 7 and between the rubber mold 7 and the female mold 3, respectively. Performs a holding function. Reference numeral 18 is a vent hole used to maintain the inside of the cavity 9 in a vacuum as necessary before injecting the material, and connects the surface of the female mold 3 with the side of the female mold 3 to maintain the vacuum through the pipe. It is connected to. This does not fulfill an essential requirement for the mold of the present invention.

The mold according to the present invention is formed from the above-mentioned parts 1 to 18, but the most important point among them is the rubber mold 7. In particular, the dimensional relationship with the protrusion 21 is an important structural point. It is. That is, the size, thickness, and bulk of the tip 22 of the rubber mold 7 after the protrusion 21 is removed is such that it can easily pass through the inner surface 23 of the largest constriction of the product. On the other hand, the maximum constriction part 23
The wall thickness 24 of the rubber mold 7 corresponding to It must be designed to have sufficient strength to withstand any damage. In addition, the inner surface of the rubber mold 7 is made so small that it also covers the outer surface of the protrusion 21.
1 is slightly stretched at the stage of insertion to expand its external shape, making it easier to handle later when demolding.

However, if the remaining dimensions are small, the expansion during molding will be large, and there is a risk that the durability will be significantly impaired, so there is a practical limit. Considering the durability of the rubber mold 7, it is preferable to use a material that can substantially withstand repeated use at vulcanization temperatures (usually 120 to 200 C). , 7-layer rubber, silicone rubber, EPDM, etc. are preferable.

On the other hand, the rubber mold 7 is required to have little deformation (volume shrinkage) due to molding pressure during molding in order to increase the dimension N degree of the product, and is desired to have a bulk modulus as large as possible. Since it is necessary that the material be easily responsive to elongation and deformation, a material having a hardness of s 5 (JIS hardness scale) or less, preferably 55 to 7° (JIS hardness scale) is suitable for practical use. Of course, materials that require low molding pressure (e.g. liquid rubber)
In the case of
(approximately 0) is also available.

Although not a requirement for the mold of this belief invention, for heating and temperature control of the mold, there is a method of attaching a band heater or a bar-shaped sheathed heater, which is usually used in the injection molding method of rubber, and a method of inserting a heating plate between the mold and the mounting plate. Alternatively, methods such as providing a special pipe for circulating the heat medium in the mold or directly inserting an electric heater can be taken, and it is also possible to provide the necessary structure in the mold together with the mounting part of the temperature center. It's not a hindrance in any way. In addition, the position detection of each mold element required in the vulcanization molding operation described below, and the installation of equipment for product demolding, can be achieved by combining and utilizing technologies conventionally used in ordinary injection molding equipment. It goes without saying that this will be achieved.

Next, an example of the vulcanization molding method using the mold according to the present invention will be explained using an example of a nipple.

Once the mold is maintained at a predetermined temperature and the injection molding machine is ready for work, the movable plate of the molding machine is moved to open the mold. At this time, the mold is first divided between the male core portion 4 and the intermediate plate 5, and the intermediate plate 5 and the female mold 3 are kept in close contact with each other. The tip of the protrusion 21 of the male core part 4 is the largest constriction part 2 of the cavity 9.
If you move at position 1 passing through 3, the distance between 4 and 5 is
The mold is divided between the female mold 3 and the intermediate plate 5 by keeping it as it is by attaching stones 1 and -.

At this time, if the air hole 15 provided in the protrusion 21 is kept in a vacuum, the tip 25 of the rubber mold 7 will be sucked into the space from which the protrusion 21 has been removed and will be crushed, making the narrowest part of the largest constriction 23 particularly difficult. You can pass without any problems.

When the rubber mold 7 is completely separated from the female mold 3 and the distance between 3 and 5 is far enough to allow the vulcanized molded product to be taken out, the movable plate opens, the movement is completed, and it stops. After opening the simold using this method, inspect the interior to make sure there are no foreign objects, dirt, or other objects that could interfere with the subsequent molding process. Furthermore, even when the product is actually vulcanized and molded, the mold is opened in substantially the same order, so the materials remaining in the mold, such as the product 8 and sprue 11, are removed from the mold at this stage.

If necessary, spray a release agent on the mold. Next, the movable plate is moved to close the mold.

In this case, the various parts of the mold approach each other in almost the reverse order of when the mold was opened. That is, the female mold 3 moves in the closing direction, the tip 25 of the rubber mold 7 is inserted into the cavity 9, and the female mold 3 comes into contact with the intermediate route 5. Subsequently, the intermediate plate 5 is integrated with the female mold 3 and approaches the male core part 4 to close the mold, but at this time the protrusion 2
The tip of the rubber mold 7 will push the tip 25 of the rubber mold 7 and pass through the narrowest part 23 of the cavity, so by keeping the air hole 15 empty at this point, the rubber mold 7 can be inserted. becomes easier. Even after the tip of the tip 21 of the protrusion 21 passes through the narrowest part 23, the vacuum is continued to be maintained to improve the contact with the comb mold 7. After tightening the mold, attach the nozzle of the injection molding machine to the nozzle holder part 10 of the mold.
contact with.

Next, the material is injected, but if it is necessary to keep the inside of the cavity 9 in a vacuum before injecting the material, open the space between the female mold 3 and the intermediate plate 5 slightly (for example, by one stroke) to vent the cavity. The hole 18 is kept under vacuum to completely eliminate the air in the cavity 9, and then the mold is closed again and the material is injected.

When the injection of the material is completed, the penthole 18 and air hole 15 are returned to normal pressure. After heating for a predetermined period of time to complete vulcanization, the mold is opened in the aforementioned order and the molded product is taken out.

During the vulcanization period, a degassing operation may be performed under vacuum or normal pressure as necessary. Thereafter, the same process is repeated.

The molding method using the vulcanized rubber according to the present invention as a part of the mold has been explained above, but as can be seen from this, nipples with constrictions, which could only be manufactured by dipping with latex or rubber solution, It can now be manufactured using injection molding.

In addition, when extracting the rubber mold 7, it is preferable to apply negative pressure inside as described above, but depending on the shape, the extracting operation may be performed under normal pressure or pressurization.

In the present invention, by appropriately selecting the dimensions, hardness, etc. of the rubber mold 7, molding is possible up to the size ratio of the tip part and the constriction part of 2: process level. A mold that can be removed from the mold itself during molding can be used as the rubber mold 7 of the present invention, so it has sufficient practical effects on nipples with constrictions, reduces manufacturing costs, and enables mass production. The effect is demonstrated. It is considered to be a suitable method for products using liquid polymers that require low injection pressure and molding pressure, and also has better dimensional accuracy than dipping products for thin-walled products.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of one embodiment of the mold of the present invention (nipple), Figure 2 is an enlarged view of the part of the mold that forms the constriction of the product, and Figure 3 is the tip of the rubber mold when removing the male mold. It is a figure showing the state of deformation. l...Female type mounting plate 2...Male type mounting plate 3.
... Female type body 4 ... Male core part 5 ... Intermediate plate 6 ... Bushing for part of the sprue 7 ... Rubber mold 8 ... Product 9 ... Product outer surface Cavity 10 for nozzle holder 11 Sugeru 12 Undercut for sprue removal 13.
...Runner 14...Dart 15...Air hole for pressure regulation inside the rubber mold 16.17...0-ring 18...Vent hole (used as necessary) 21.
...Male mold protrusion 22...The thickest part 23 of the tip of the rubber mold...
・Minimum constriction part (product) 24...Thickness of the rubber mold at the minimum constriction part 25...Tip of rubber mold 7" Positive P'-・1) ・Paj 21st" 1st 3rd Plot 7

Claims (1)

[Claims] In an injection mold device for manufacturing a thin-walled hollow object having a constriction in the middle, the male mold has a shape that matches the inner surface shape of the object, and the female mold has a shape that matches the outer surface shape of the object. The male mold is provided with a metal core material in the form of a tapered or straight bar that passes through the constriction of the female mold, and a flexible and heat-resistant core material that covers the core material to provide a male surface. This mold device is characterized by having a two-layer structure consisting of a highly flexible rubber cover and a rubber cover.