JPS5848109Y2 - Mold device for box molding with an undercut on the inside - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a mold for plastic molding.

More specifically, this invention relates to a plastic mold for manufacturing a box having an undercut portion on the inside.

Prior Art In order to manufacture a block-like molded product having an undercut portion on the outside, protrusions for forming the undercut portion are temporarily attached to the inner wall of the mold in advance. There is a known method in which plastic is molded using a molded product, the molded product is extracted from the mold along with the protrusions, and the protrusions are further extracted from the molded product.

This method can be applied with some modification when manufacturing a box-shaped molded product that has an undercut on the inside, but it may be necessary to temporarily attach the protrusions to the mold in advance or This is a very inefficient method as it requires removing the protrusions from the surface.

Furthermore, Japanese Patent Application Laid-Open No. 52-14672 discloses a molding method in which a movable mold that moves perpendicularly or diagonally to the moving direction of the movable mold is disposed, and the movable mold is moved into and out of a cavity by a piston. The equipment is described.

According to the molding apparatus described in this publication, it is possible to efficiently form an undercut on the outer surface of the molded product in a direction different from the movement direction of the movable mold, but it is possible to efficiently form an undercut on the outer surface of the molded product in a direction different from the moving direction of the movable mold. As a molding apparatus for simultaneously molding a large number of boxes which cannot form cut portions and which have undercut portions, the one shown in FIG. 1 is known.

The mold apparatus shown in FIG. 1 consists of an upper mold plate C having a plurality of upwardly opening recesses, and a steam chamber d above the upper mold plate C, and a lower mold e as shown in FIG. It consists of a mold plate g having a recess f corresponding to and larger than the recess f opening upward, and a steam chamber below the mold plate g, and these upper mold a and lower mold e are closed together. Sometimes, a plurality of cavities i are formed between the two mold plates C9g, and a movable undercut mold j that appears and retracts into each of these cavities i.
A drive cylinder k is provided on the side wall of each recess f, projecting into the steam chamber.

Both the device described in Japanese Patent Application Laid-Open No. 52-14672 and the device shown in FIG. Therefore, in the case of a mold in which a large number of molds are to be made at once, the steam chamber occupies a considerably large space, making the mold equipment large and requiring a considerably large amount of steam. Therefore, it has the drawbacks of poor space utilization efficiency and thermal uneconomical.

Purpose of the invention In view of the above-mentioned current situation, the inventor aimed to develop a molding device that can efficiently mold a box body having an undercut portion on the inside and does not require a large steam chamber. As a result of research, I was able to achieve a distant relative of the above objective with this invention.

Structure of the Device The structure of the device will be explained with reference to FIG. 2 showing an embodiment of the device. In addition, the lower mold 2 is composed of a lower mold plate 7 having a recess 6 that corresponds to the recess 3 and is larger than the recess 6 and opens upward, and a steam chamber 8 below the mold plate 7. However, in the case where a plurality of cavities 9 are formed between the mold plates 4 and 7 when the upper mold 1 and the lower mold 2 are closed together, the underside that appears and retracts into each of these cavities 9 is The drive cylinder 11 of the movable cutting mold 10 is connected to the four parts 3
It is located inside the building.

In the embodiment shown in FIG. 2, the upper mold 1 has an upper lid plate 12 and the upper mold plate 4 connected to each other at their peripheries to form the steam chamber 5 inside. Connect the pipes and cooling water pipes.

Further, the lower mold 2 connects the lower lid plate 13 and the lower mold plate 7 at their periphery to form the steam chamber 8 therein,
Although not shown, a steam pipe and a cooling water pipe are connected to this pipe.

The driving cylinder 11 is a suitable cylinder such as a hydraulic cylinder or a pneumatic cylinder, and is provided on the side wall of each recess 3 of the upper mold plate 4 so as to project inwardly. The movable mold 10 is connected to the tip.

15 indicates piping connected to these drive cylinders 11.

Actions and Effects After the upper mold 1 and the lower mold 2 are closed together to form the cavity 9 between the upper mold plate 4 and the lower mold plate 7, the driving cylinder 11 is driven to move the movable mold 10. It is made to protrude into the cavity 9.

Next, the foamable synthetic resin particles are charged into the container 9 through a synthetic resin charging port (not shown) provided in the recess 3 of the upper mold plate 4 or the recess 6 of the lower mold plate 7, and the charging port is closed. After that, steam is sent to the upper and lower steam chambers 5 and 8 to heat and foam the synthetic resin particles.

After the foaming process, cooling water is sent to the steam chambers 5 and 8 to cool and harden the synthetic resin, then the drive cylinder 11 is driven in reverse to immerse the movable mold 10, and then the upper mold 1 is moved into the lower mold 2. The box molded product having the undercut portion is extruded by the extrusion action of an extrusion rod (not shown).

In this way, the drive cylinder 11 of the movable undercut mold 10 that appears and retracts inside the catty 9 is provided within the four parts 3 of the upper template 4 for forming the inner peripheral surface of the box molded product, so that the space can be reduced. For effective utilization, the steam chambers 5 and 8 are smaller than conventional ones, and therefore, when making many molds at once, the mold equipment becomes smaller, and the amount of steam used is small, so the space can be used more efficiently. It has the effect of being highly efficient and thermally economical.

The synthetic resin molded by the mold device of this invention may be any expandable thermoplastic synthetic resin particles, but from a practical standpoint, expandable polystyrene particles or expandable polyethylene particles are suitable. be.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing an example of a conventional device, and FIG. 2 is a cross-sectional view showing one of the embodiments of this invention. 1...Upper mold, 2...Lower mold, 3
, 6... recess, 4... upper template, 5,
8...Steam chamber, 7...Lower template, 9.
...Cavity, 10...Movable type, 11
・・・・・・Drive cylinder

Claims (1)

[Scope of utility model registration request] The upper mold 1 is composed of an upper mold plate 4 having a plurality of upwardly opening recesses 3 and a steam chamber 5 above the upper mold plate 4.
The lower mold 2 is constituted by a lower mold plate 7 having a recess 6 corresponding to and larger than the recess 3 and opening upward, and a steam chamber 8 below the mold plate 7. In the case where a plurality of cavities 9 are formed between the two mold plates 4 and 7 when the side mold 2 is closed, the drive cylinder 11 of the movable undercut mold 10 that retracts and retracts into each of these cavities 9 is as described above. A box-forming mold device provided in the recess 3.