JPH0564568B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a compression mold.

(Prior art) Compression molding involves supplying powdered molding material into a heated mold, melting the molding material, and applying pressure to mold the material.As a simple molding method, it is not often used in resin molding. There is.

Conventional compression molds include a flash type, a positive type, etc. depending on the structure of the mold.

The flash mold is configured to supply a slightly larger amount of molding material than necessary for molding, and allow the excess molding material to flow out of the cavity during molding. This type of mold has the advantage that there is no need to precisely weigh the molding material and that the mold is easy to manufacture. The disadvantage is that it is difficult to apply heat and the density of the molded product is low.

In addition, the positive mold has a piston structure in which the male and female molds fit together to prevent the molding material from flowing out of the cavity, so that no burrs appear during molding and sufficient pressure can be applied. Although the density of the molded product increases, the molding material must be accurately weighed and supplied in order to obtain a good product. When using this mold, if the amount of molding material supplied is not constant, the thickness of the molded product will vary and unfilled portions will appear.

(Problems to be Solved by the Invention) As mentioned above, conventional compression molding molds each have their own characteristics, but the basic problem is that the material used as the molding material is powder with irregular grain sizes.
Since it is a granular product, it is inherently difficult to accurately weigh it, and depending on the shape of the product, it may be extremely difficult to mold it without creating burrs using conventional molds. There is a problem that there is.

That is, in the case of a molding material containing a mixture of powder and granules, there is usually an error of about 3% in the amount of material supplied. This variation in supply amount leads to variations in product wall thickness, etc., and to the occurrence of unfilled areas.

In addition, when molding a product that has notches (unevenness) on the outer surface of the flange as shown in Figure 3, there is a problem in molding that if you try to mold it without creating burrs, it is difficult for conventional molds to A mold is used, but in order to perform compression molding to create an uneven outer surface, the sliding surfaces of the male and female molds that fit must be formed into an uneven surface that matches the external shape of the product. However, forming the sliding surface of the mold to have a complex uneven surface is difficult to manufacture, and is almost impossible in terms of manufacturing cost.

Therefore, it has not been possible to use conventional compression molding molds to compression mold products having complex external shapes as described above without producing burrs. (For example, JP-A-56-161137,
(Refer to Japanese Utility Model Publication No. 53-17351) Therefore, the present invention has been made to solve the above problems, and its purpose is to eliminate burrs even when the outer surface is a complex shape. A compression molding mold that has a new structure that can be easily molded without molding, increases the density of the molded product, prevents variations in wall thickness and unfilled areas, and facilitates mold production. It is in providing the mold.

(Means for Solving the Problems) The present invention has the following configuration to achieve the above object.

That is, the lower mold has a recessed cavity surface that regulates the outer shape of the molded product to be obtained, and a core that has a cavity surface formed at the tip that regulates the inner shape and outer peripheral end surface of the molded product to be obtained. In a compression molding mold comprising an upper mold that forms a molding cavity when the mold is closed, the core can be fitted between the lower mold and the upper mold. An intermediate plate with a transparent insertion hole is interposed so as to be movable in the mold opening/closing direction, and the surface around the core insertion hole of the intermediate plate facing the lower mold is all or part of the outer peripheral end surface of the molded product to be obtained. When closing the mold, the lower mold and intermediate plate are aligned, and the molding material is filled into the cavity surface, and then the upper mold is aligned and the mold is closed. The present invention is characterized in that, when opening the mold, a mold closing/opening mechanism is provided which first separates the lower mold from the intermediate plate and then separates the intermediate plate from the upper mold.

(Function) When closing the mold, first, the lower mold and the intermediate plate are matched, and after the molding material is supplied, the intermediate plate is interposed between the lower mold and the upper mold and the mold is closed. At this time, the core of the upper mold fits into the core insertion hole, and a molding cavity is formed between it and the cavity surface of the lower mold. This prevents molding material from leaking from the cavity surface and prevents burrs from appearing even when sufficient compressive force is applied when closing the mold. When opening the mold, first the lower mold is separated from the intermediate plate, and then the intermediate plate is separated from the upper mold. By forming the intermediate plate so that the peripheral surface of the core insertion hole regulates the outer peripheral end surface of the molded product, when the intermediate plate is separated, the molded product protrudes from the core and is released from the mold.

(Embodiments) Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Figures 1 and 2 are explanatory diagrams showing one embodiment of a compression molding mold according to the present invention, with Figure 1 showing the state of the mold when the mold is opened, and Figure 2 showing the state of the mold when the mold is closed. .

In the figure, 10 is a lower mold, an intermediate plate 20 is located above the lower mold, and an upper mold 30 is located further above the intermediate plate 20.

The lower mold 10 is fixed on a base 11, and the base 11 is connected to a drive unit that vertically moves the base up and down in response to mold opening and mold closing. 12 is a cavity surface recessed in the upper surface of the lower mold 10. A flat ridge (mold mating surface) 13 formed in the shape of a narrow protrusion is provided at the upper peripheral portion of the cavity surface 12 . This flash library 1
3 acts as a burr preventer by coming into contact with the lower surface of the intermediate plate 20 when the lower mold 10 is fitted to the intermediate plate 20. 14 is a guide pin fixed on the base 11.

The intermediate plate 20 is horizontally supported with one end fixed to a piston rod 22 which is connected to a hydraulic cylinder 21 and moves up and down in the vertical direction. When the mold is opened, the intermediate plate 20 is located approximately midway between the lower mold 10 and the upper mold 30.

Reference numeral 23 denotes a core insertion hole into which the core of the upper mold is inserted, and is provided so as to penetrate through the intermediate plate 20 at a position corresponding to the cavity surface 12 . 14a
is the guide pin bushing.

The upper mold 30 is fixedly supported by the frame, and the upper mold 30
is provided with a protruding core 31 that fits into the core insertion hole 23 and fits into the cavity surface 12. This core 31 forms a molding cavity with the cavity surface 12 when the mold is closed, and a cavity surface is provided at the tip of the core 31 to regulate the inner mold and outer peripheral end surface of the molded product.

Note that 32 is a push pin formed in the shape of a long thin rod, and is slid into a through hole provided vertically through the upper mold 30 from the lower surface of the core 31. The upper end of the push pin 32 is fixed to the lower surface of a support plate 33 that is movably housed in the upper mold 30 in the vertical direction. A rod 34 that pushes downward is arranged. 35 is a guide fixed to the lower surface of the support plate 33, and the lower part of the guide 35 is slid into the guide hole 36. The support plate 33 is always biased vertically upward and supported by a coil spring fitted onto the guide 35.

37 is a guide pin, and 37a and 37b are guide pin bushes provided on the intermediate plate 20 and the lower mold 10, respectively.

Next, the operation of the compression molding mold of the above embodiment and the compression molding method using this mold will be explained.

First, from the mold open state shown in Figure 1, base 1
The lower mold 10 is raised together with the intermediate plate 2.
0 and the lower mold 10 are matched. This connects the cavity surface 12 and the core insertion hole 23.

A predetermined amount of molding material is supplied into the cavity surface 12 while the cavity surface 12 and the core insertion hole 23 are connected. The supplied molding material will not leak out because the lower mold 10 and the intermediate plate 20 are perfectly matched. The lower mold 10 is preheated to a temperature that melts the molding material.

Next, the intermediate plate 20 containing the molding material
The upper mold 30 is raised toward the upper mold 30 while the lower mold 10 is still connected, and the molds are matched with the upper mold 30. At this time, the core 31 gradually enters the core insertion hole 23, forms a molding cavity with the cavity surface 12 as shown in FIG. 2, and molds the molten molding material into a predetermined shape. . In this manner, when closing the mold, first, the upper mold 30 is not matched, but the lower mold 10 and the intermediate plate 20 are matched, and a predetermined amount of molding material is applied to the cavity surface 12 of the lower mold 10. In this way, when the cavity surface 12 of the lower mold 10 is filled with the molding material, the cavity surface 12 of the lower mold 10 is connected to the core insertion hole of the intermediate plate 20.
This intermediate plate 20 prevents the molding material from leaking to the outside of the cavity surface 12 even if it is a fluid. Therefore, even if the upper mold 30 is closed and a sufficient compressive force is applied as described below, the intermediate plate 2
0 prevents burrs from appearing during molding, and at the same time, sufficient compressive force can increase the density of the molded product.

After the molding is completed, the lower mold 10 is first separated from the intermediate plate 20 and lowered. Since the molded product shrinks after molding, the molded product remains attached to the core 31.
Next, the intermediate plate 20 is separated from the upper mold 30 and lowered. Since the outer peripheral end surface of the molded product is in contact with the periphery of the lower surface of the core insertion hole 23 of the intermediate plate 20, the molded product is separated from the core 31 by being pushed out by the intermediate plate 20.

With the above steps, the steps from supplying the molding material to molding the molding material and releasing the molded product are completed.

According to the molding die of this embodiment, since the core 31 is fitted in a piston-like manner during molding as described above, it is possible to completely prevent burrs from appearing during molding. In addition, when closing the mold, back pressure is applied from the intermediate plate 20 to the lower mold 10 to prevent burrs from appearing.

In the above embodiment, a box-shaped product with an open top as shown in FIG. 3 is molded. This product has a flange 4 with unevenness on the upper outer peripheral surface.
0 is placed around it. Products with complex irregularities on the outer surface cannot be easily molded using conventional compression molds. However, in the mold of the embodiment, the outer surface forming portion below the flange 40 is composed of the cavity surface 12 portion of the lower mold 10, and the core insertion hole 23 has a simple rectangular shape as shown by the two-dot chain line A in FIG. It can be easily molded by setting the area to . The core 31 is manufactured into a predetermined shape depending on the internal structure and wall thickness of the product. Reference numeral 41 denotes a preformed portion formed by a molding material filled in the through hole.

Thus, with the mold of the above embodiment, the complicated shape of the outer surface of the product can be processed using only the shape of the lower mold 10, and the shape of the core 31 is also the same as that of conventional molds. Therefore, when manufacturing a mold, there is no need to create a sliding surface according to a complicated external shape, and the difficulty in manufacturing the mold can be solved and the mold can be manufactured at a sufficient cost.

The push pin 32 is used to solve the problem of product variations due to weighing errors in the supplied molding material, and is preferably used to prevent defects even if protrusions or the like are formed on the structure of the product. Through-holes are opened in places where there are no molding materials, and variations are eliminated by adjusting the amount of molding material filled into the through-holes by the amount of thrust of the push pin. In FIG. 2, the states before and after the push pin 32 is pushed in are shown for explanatory purposes.

If the molding material supplied is a little small, the push pin 32 will be pushed in close to the bottom of the cavity surface 12, and if the molding material supplied is a little large, the push pin 32 will be pushed in only a little. If the molding material remains in the through hole, a preformed portion 41 as shown in FIG. 3 is formed. There is no problem if the preformed part 41 is provided in a part that will not cause defects in the product, and even if it is not, it can be created in a specific part and removed only in the post process to make it into a product without problems. can do.

If the push pin 32 is provided in this way, the amount of thrust of the push pin 32 can be adjusted, and when there is excess molding material, it acts as an escape for the molding material to prevent burrs from appearing, and also prevents the molding material from forming. If the amount is a little low, it is possible to avoid leaving unfilled areas by supplementing with the material filled in the through holes. This makes it possible to absorb variations in the amount of molding material supplied and eliminate product variations.

In addition, the push pin 32 can be used to finely adjust the molding pressure when molding between the core 31 and the cavity surface 12 by providing a series of control mechanisms that control the pushing pressure of the push pin 32. It can be used for more reliable molding.

In addition, in the above embodiment, an example was shown in which two push pins 32 were arranged, but of course the number and size of the push pins 32 are not limited.

Further, in the above embodiment, the hydraulic cylinder 21 for moving the intermediate plate 20 is attached to the upper mold 30 side, but this hydraulic cylinder 21 may be installed to the base 11 on the lower mold 10 side, and it can also be used to support the molding machine. It may be provided on the frame, etc., and the installation position is not particularly limited.

The present invention has been variously explained above with reference to preferred embodiments, but the present invention is not limited to these embodiments. The structure of the lower mold, intermediate plate, upper mold, etc. can be modified in various ways, and it can be used for molding various products.

(Effects of the Invention) As described above, the compression molding mold of the present invention has the following features:
An intermediate plate is interposed between the upper mold and the lower mold, the lower mold, the intermediate plate, and the upper mold are combined, and at the beginning of mold closing, the intermediate plate 20 is aligned with the lower mold, and the upper mold is By separating the mold from the intermediate plate, filling the cavity surface with molding material, and then closing the mold, the following remarkable effects can be obtained.

Since the core is inserted into the core insertion hole of the intermediate plate and the mold is closed, molding can be performed without generating burrs. Furthermore, since the molding material can be supplied while the intermediate plate and the lower mold are matched, burrs do not appear on the mold matching surface.

Since the shape of the molded product is determined only by the shape of the cavity surface of the lower mold and the cavity surface of the upper mold core, molds can be easily manufactured even for products with complex external shapes, which were previously impossible to mold. Even if the product has a specific shape, it can be molded.

By applying pressure to the lower mold from the intermediate plate, it is possible to prevent burrs from forming on the mold mating surfaces.

The intermediate plate can also serve as an ejector to separate the molded product from the core, simplifying the structure of the mold.

Even if sufficient compressive force is applied when closing the mold, the intermediate plate prevents burrs from forming, which increases the density of the molded product and prevents variations in wall thickness and unfilled areas. You can prevent it from happening.

[Brief explanation of drawings]

FIGS. 1 and 2 are explanatory diagrams showing states of the compression molding mold according to the present invention when the mold is opened and closed, and FIGS. 3a and 3b are plan views and side views showing examples of molded products. It is. 10... Lower mold, 12... Cavity surface, 20
...Intermediate plate, 21...Hydraulic cylinder, 23
... Core insertion hole, 30 ... Upper mold, 31 ... Core, 32 ... Push pin, 35 ... Guide, 40 ...
...flange, 41...preformed part.

Claims (1)

[Claims] 1. A lower mold having a recessed cavity surface that regulates the outer shape of the molded product to be obtained, and a core having a cavity surface formed at the tip that regulates the inner shape and outer peripheral end surface of the molded product to be obtained, In a compression molding mold comprising an upper mold that forms a molding cavity when the mold is closed, a core fitting between the lower mold and the upper mold allows the core to fit into the mold. An intermediate plate with a transparent hole is provided so as to be movable in the mold opening/closing direction, and the surface around the core insertion hole of the intermediate plate facing the lower mold covers all or part of the outer peripheral end surface of the molded product to be obtained. When closing the mold, the lower mold and the intermediate plate are aligned, the molding material is filled into the cavity surface, the upper mold is aligned, and the mold is closed. A mold for compression molding, characterized in that, when the mold is opened, a mold closing/opening mechanism is provided which first separates the lower mold from the intermediate plate and then separates the intermediate plate from the upper mold.