JPH0514820Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to the punching pin structure of a forming die.
In particular, the present invention relates to an improvement in the punching pin structure of a molding die, which is suitable for resin molding using a full mold casting method.

[Conventional technology]

Conventionally, a mold 50 for forming a foamed thermoplastic resin part 52 having a casting hole 58 as shown in FIGS. 8 and 9 has been installed in molding frames 501 and 503 as shown in FIG. It consisted of a cavity mold 502, a core mold 504, and a punching pin 506.

Then, the cavity mold 502 and the core mold 5
04, a cavity 505 is formed, and a cavity mold 502 and a core mold 50 are formed.
4 had a large number of core vents 508 buried therein for introducing steam to remove air during filling of raw materials and improve heat-fusion properties.

By the way, the uses of foamed thermoplastic resin parts have recently expanded, and among these, their use as disappearing models for full mold casting is increasing.

The full mold casting method is a method in which a foamed thermoplastic resin model (generally foamed polystyrene) is buried in fireproof sand, and then molten metal is poured directly onto the resin model to replace the metal and resin to produce a casting. It is.

A major feature of the full mold casting method is that it has good transfer accuracy of the foamed thermoplastic resin model shape.

For this reason, many parts manufactured using the full mold casting method have a defined surface quality (surface roughness) for functionality and product design, and the surface quality of foamed thermoplastic resin molded products that are used as fugitive models It was hoped that improvements would be made.

For example, covers for automobile parts are tightened and integrated with other parts using bolts, so the surface roughness of the bearing surface of the bolt attachment part should be 50 μ or less to prevent the bolt from loosening when the bolt is tightened. It is stipulated that

For this reason, vents have been installed at necessary locations within the mold to improve the filling and fusion properties of raw materials.
On the contrary, there was a problem in that the unevenness of the vent was transferred to the molded product, deteriorating the surface quality.

Further, in the molding of boss-shaped parts having cast holes for attaching bolts, there was also the problem that vents could not be provided for the same reason as above.

And since it is not possible to install a vent,
There was a problem in that the flow of air during filling of raw materials was obstructed, and air back pressure caused incomplete filling of raw materials, resulting in defective shapes.

In addition, there was a problem that the packing density of the raw material was lower than that of other parts, and that the material contracted after heat-sealing, resulting in molding defects.

On the other hand, there has been a gas venting structure for the foaming mold in which the foaming mold is provided with a valve mechanism having a float valve, and the valve mechanism is provided with a gas venting hole.

In other words, this has a structure in which the foaming gas generated from the foamed resin and the air in the cavity are exhausted by a float valve installed in the foaming mold, and the float valve is closed using the expansion force of the foamed resin. It is designed to make people speak.

For example, such technology was developed in 1983.
-Disclosed in Publication No. 138626.

[The problem that the idea aims to solve]

However, since the conventional gas venting structure uses a method of filling the raw material resin with air pressure, there is a risk that the float valve may close when the raw material is filled, making it difficult to guarantee reliable operation. It was hot.

In addition, the pressure of heated steam supplied from the back of the mold (0.8 to 1.2 kg/
cm ² ), the float valve was pushed out, and the shape of the float valve was conversely transferred to the surface of the molded product, creating a depression, resulting in a problem in which product quality was degraded.

Therefore, an object of the present invention is to ensure degassing with a simple structure and to improve product quality.

[Means to solve the problem]

For this reason, the casting pin structure of the molding die according to the present invention will be described with reference to the numbers attached to the drawings.
and the cavity 9 formed by the core mold 14.
This is characterized by a structure in which the mold and the outside of the mold are communicated through the hollow part 6 of the casting pin 1.

Specifically, it is a casting pin structure of a forming die used for manufacturing a molded product having a casting hole, and the casting pin 1 is used for positioning and attaching the casting pin 1 to the mold. Fitting part 3 and mounting screw part 4
has a hollow structure 6, and the fitting part 3 is formed with a plurality of outer circumferential slits 32 and a communication hole 8 that communicates the hollow part 6 of the fitting part 3 with the outer circumferential slit 32. A plurality of slit grooves 2 are formed on the outer periphery of the bottom portion 22 of the cast-out pin 1 to communicate with the hollow portion 6 through the outer periphery slit 32 of the fitting portion 3.
4 is formed radially.

[Effect]

To explain the operation of the present invention according to the above configuration, the core is Mold 14
The cavity 9 formed by the cavity mold 15 and the outside of the mold can communicate with each other so that the pressure is equal.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 1 is an enlarged partial sectional view showing the schematic configuration of the casting pin structure of the molding die according to the present invention together with the attachment part to the mold, and FIG. 2 is a front view of the casting pin, and FIG. Figure 3 is a cross-sectional view taken along the - line in Figure 2, Figure 4 is a partial cross-sectional view schematically showing the system configuration of the mold, and Figure 6 is a mold manufactured using the casting pin according to the present invention. FIG. 7 is a graph showing the results of measuring the surface roughness of a molded product produced using a conventional casting pin.

As shown in FIG. 4, the molding die 10 includes a fixed die plate 11, a movable die plate 12, and a cylinder device 13 driven by hydraulic pressure.

The cylinder device 13 is for opening and closing the molding die 10 and clamping the mold.

The cavity mold 15, which is a fixed type, is attached to the fixed die plate 11 and is configured to match the cavity mold 15.

Further, a casting pin 1 for forming a casting hole in a molded product 16 is fixed to the cavity mold 15 by tightening with a nut 18, as shown in FIG.

The cast-out pin 1 includes a cast-out part 2 for forming a cast-out hole, a fitting part 3, and a mounting screw part 4.

The fitting part 3 inserts the casting pin 1 into a cavity mold 15.
This is the part that is positioned and fitted. In addition, the mounting screw part 4 connects the casting pin 1 to the cavity mold 15.
This is the part that is fixed to.

The fitting part 3 and the mounting screw part 4 are connected to the third
As shown in the figure, it has a hollow structure 6. Also,
The bottom part 22 of the cast-out part 2 has radial slit grooves 2.
4 is formed in four places.

Furthermore, the fitting portion 3 is also formed with outer circumferential slits 32 at four locations in the vertical direction. The outer circumferential slit 32 and the hollow portion 6 are communicated with each other through a horizontal communication hole 8.

That is, the cast pin 1 having such a structure
By attaching it to the cavity mold 15,
Inside the cavity 9 are a slit groove 24, a communication hole 8,
The cavity chamber 92 can communicate through the outer peripheral slit 32 and the hollow portion 6.

Note that, in order to supply steam to the cavity chamber 92, a steam valve 152 and a cooling water valve 154 are attached to the cavity mold 15, as well as an air valve 156 and a drain valve 158.

The core mold 14 also includes a core chamber 14.
2, a steam valve 143 and a cooling water valve 144 are installed, as well as an air valve 146 and a drain valve 148.
is installed.

Further, 162 is a raw material filling device connected to a raw material hopper (not shown), and has a structure capable of filling the cavity 9 with foamed thermoplastic resin.

In addition to foamed polystyrene, the raw materials for the foamed thermoplastic resin include polyethylene, polypropylene, polyvinyl chloride, copolymers mainly composed of these, and the like.

Furthermore, a large number of core vents 19 are embedded in both the cavity mold 15 and the core mold 14, each having a slit that allows air and steam to pass therethrough, but not the foamed thermoplastic resin that is the raw material.

To explain the operation of the embodiment according to the above configuration, first, the cylinder device 13 causes the mold 10 to
After the mold is clamped, the foamed thermoplastic resin is supplied from the raw material filler 162 into the cavity 9 using compressed air.

At this time, the compressed air (filling air) fed into the cavity 9 passes through the slit groove 24 formed in the cast pin 1, the communication hole 8, the outer periphery slit 32, and the hollow part 6, and then flows into the cavity chamber 92. Exit to.

For this reason, the filling performance of the foamed thermoplastic resin into the cavity 9 is improved.

Next, steam valves 143 and 152 are opened to supply steam as a heating medium to cavity chamber 92 and core chamber 142 to raise the temperature of cavity mold 15 and core mold 14.

After completing heat fusion, steam valves 143 and 152 are closed, and drain valves 148 and 1 are closed.
58 and cooling water valves 144 and 1.
54 is opened to allow cooling water to flow into chambers 92 and 142 to cool the mold.

Furthermore, after cooling is completed, drain valves 148 and 158 are closed, air valve 156 is opened, and while supplying mold release air from core vent 19 into cavity 9, cylinder device 13 is driven to open the mold.

As a result, the molded product remains in the core mold 14, so the air valve 146 is opened and the molded product is removed while supplying the release core from the core mold 14 side.

In this way, a series of foam molding steps can be completed.

Note that FIGS. 6 and 7 are graphs showing the surface roughness of molded products manufactured using the present invention and conventional casting pins, respectively.

As is clear from the figure, it can be seen that the molded product according to the present invention has reduced surface roughness and improved quality compared to conventional molded products.

Although specific embodiments of the present invention have been described above, the present invention is not limited thereto, and various other embodiments can be considered by those skilled in the art within the scope of the claims for utility model registration.

For example, in the above embodiment, the cylinder device is driven by hydraulic pressure, but it may be driven by air instead of hydraulic pressure.

(Effects of the invention) As explained above, the casting pin structure of the molding die according to the present invention is such that the cavity formed by the cavity mold and the core mold constituting the molding mold is connected to the outside of the mold. Since the structure is such that communication occurs through the hollow part of the casting pin, degassing can be performed reliably with a simple structure.

In addition, the air flow during filling of raw materials is improved, eliminating defects in foamed resin shrinkage caused by incomplete or insufficient filling of raw materials, improving product quality and reducing manufacturing costs. .

Furthermore, in the heating step for molding, the above-mentioned material permeates between the particles of the foamed thermoplastic resin from the cavity chamber, so that the interior of the foamed thermoplastic resin can be sufficiently heated.

Therefore, the fusion properties of the molded product are improved, the gap between the foamed particles is reduced, and the strength and surface properties of the product can be improved.

Furthermore, by improving the quality of molded products, the range of applications of full-mold casting parts can be expanded, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is an enlarged partial sectional view showing the schematic configuration of the casting pin structure of the molding die according to the present invention together with the attachment part to the mold, and FIG. 2 is a front view of the casting pin, and FIG. Figure 3 is a sectional view taken along the - line in Figure 2, Figure 4 is a partial sectional view schematically showing the system configuration of the mold, and Figure 5 is a conventional mold for molding foamed thermoplastic resin. A cross-sectional view showing the schematic configuration of
Figure 6 is a graph showing the results of measuring the surface roughness of a molded product manufactured using the cast-out pin according to the present invention, and Figure 7 is a graph showing the surface roughness of a molded product manufactured using a conventional cast-out pin. A graph showing the results of measuring roughness,
FIG. 8 is a perspective view showing a schematic structure of a molded product having a casting hole, and FIG. 9 is a sectional view taken along the line - in FIG. 8. 1... Casting pin structure of the molding die, 3... Fitting part, 4... Mounting screw part, 6... Hollow structure (hollow part), 8... Communication hole, 22... Bottom part (casting pin bottom), 24... slit groove, 32... outer periphery slit.

Claims (1)

[Claims for Utility Model Registration] A casting pin structure of a forming die used for manufacturing a molded product having a casting hole, comprising a casting pin structure for positioning and attaching the casting pin to the mold. The fitting part and the mounting screw part of the casting pin have a hollow structure, and the fitting part is formed with a plurality of outer circumferential slits and a communication hole that communicates the hollow part of the fitting part with the outer circumferential slit,
Furthermore, through the outer periphery slit of the fitting part, the outer periphery of the bottom of the casting pin that becomes the attachment part to the mold,
A casting pin structure for a forming die, characterized in that a plurality of slit grooves communicating with the hollow portion are formed radially.