JPS63137816A - Mold for compression molding of thermosetting resin - Google Patents

Abstract

PURPOSE:To obtain a high-quality molded product whose surface is smooth by reliably removing air in a molding space and gas in a molding material, by a method wherein a cylindrical interrupting member for airtight interruption between a molding space and the outside is provided and effects press contact with either of a pair of molds in a contractable and expandable state according to a movement of the mold. CONSTITUTION:A molding space 6 is interrupted from the outside in an airtight state by performing press contacting of an interrupting member 16 provided on a top force 2 to a bottom force 3. Timing where this interruption is performed and timing where compression of a molding material A is begun can be set up independently of each other. Timing where ventilation of the molding space 6 is begun actually can be set up freely according to a form of a molded product B without being restricted by fitting between the top and bottom forces 2, 3. Therefore, the ventilation of the inside of the molding space 6 can be performed from early time before starting of compression of the molding material A. Air in the molding space 6 and gas contained in the molding material A can be removed reliably during a period until mold clamping is completed. Therefore, the high-quality molded product B whose surface is smooth can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mold for shrink-molding a thermosetting resin or a premix feed prepared by kneading the thermosetting resin and a reinforcing material.

[Prior art]

In this type of mold, when the molding space between the upper mold and the lower mold is filled with molding material and compression molding is performed, the air in the molding space and the gas contained in the molding material are released during mold clamping. Until completion, the flow of molding material forces it out of the molding space.

However, if this air or gas escapes poorly, compression molding will be completed with this gas still encapsulated inside the molding material, resulting in many small holes and bulges on the surface of the molded product. There was a problem that surface defects such as

For this reason, conventionally, for example,
As shown in Publication No. 75, from the start of compression to the final stage of compression, the molding space is airtightly isolated from the outside, and the inside of this molding space is exhausted by an air suction device, and the air inside the molding space is evacuated by an air suction device. Molds have been developed that prevent the occurrence of surface defects by forcibly expelling the gas in the molding material.

[Problem that the invention seeks to solve]

However, because this conventional mold has a structure in which the molding space is airtightly shut off by fitting the upper mold and the lower mold, it is extremely difficult to freely set the timing to start exhausting the molding space. Met.

Therefore, depending on the shape of the molded product, the air in the molding space and the gas in the molding material may not be completely removed during the final stage of compression, that is, until the molding material is densely packed into the molding space. However, there were still problems such as surface defects.

[Means for solving problems]

Therefore, in the present invention, a cylindrical barrier is provided in either one of the pair of molds, which is press-contacted with the other mold so that it can expand and contract as the mold moves, and airtightly isolates the molding space from the outside. It is characterized by the provision of a member.

[Effect]

According to this configuration, the blocking member is brought into airtight pressure contact with the other mold regardless of the timing at which the molds fit together, so that the timing at which the molding space is airtightly shut off and the timing at which compression of the molding + 4 materials is started can be adjusted. , can be set independently from each other, and the timing at which evacuation of the molding space actually starts can be freely set according to the shape of the molded product, etc.

Therefore, the molding space can be evacuated before the compression starts, and the air in the molding space and the gas contained in the molding material can be reliably removed until the compression is completed.

[Embodiments of the invention].

The present invention will be explained below based on an embodiment shown in the drawings.

The mold for compression molding indicated by the reference numeral 1 in the figure is composed of an upper mold 2 which is a female mold and a lower mold 3 which is a male mold. It is connected to the ram of the machine and is moved up and down in the direction toward and away from the lower mold 3.

A recess 4 is formed on the lower surface 2a of the upper mold 2, and a protrusion 5 that fits into the recess 4 is formed on the upper surface 3a of the lower mold 3.
The inner surface of the concave portion 4 and the outer surface of the convex portion 5 are finished into smooth mold surfaces 4a and 5a, respectively. Then, a thermosetting resin or a molding material A made by kneading the thermosetting resin and a reinforcing material and molding it into a sheet or a block is set on the top of the convex portion 5, and the concave portion 5 A molding space 6 for compression molding the molding material A is provided between and the convex portion 5 .

A fitting step 7 that fits into the lower end opening of the recess 4 is formed on the outer periphery of the lower end of the projection 5. Between the fitting step 7 and the recess 4, the projection 5 is inserted into the recess 4 and the mold l
When closed, for example, 0.1~
A minute gap 8 of about 0.4 mm is formed.

Further, a groove 10 surrounding the convex portion 5 is formed on the upper surface 3a of the lower mold 3, and this groove IO is continuous with the molding space 6. A plurality of exhaust ports 1 are provided on the bottom of the groove IO.
1... are opened, and these exhaust ports 11... are communicated with an exhaust passage 12 formed inside the lower mold 3, and this exhaust passage 12 is connected to a pipe 13 and an on-off valve 1.
4 to an exhaust pump 15 as an exhaust device.

By the way, on the lower surface 2a of the upper mold 2, which is the movable side, there is a cylindrical blocking member 1, such as a bellows, that can be expanded and contracted in the vertical direction.
6 is installed airtight. This blocking member 16 is provided to surround the outside of the recess 4, and when the upper mold 2 descends, it comes into pressure contact with the upper surface 2a of the lower mold 2, thereby airtightly blocking the molding space 6 from the outside. In the case of this embodiment, the blocking member 16 is brought into pressure contact with the lower mold 3 before the mold surface 4a of the upper mold 2 comes into contact with the material A of the mold 1.

Note that inside the upper mold 2 and the lower mold 3, there is a mold surface 4a.

A flow path 17 is formed for a heating medium such as steam to heat 5a.

Next, the process of compression molding the molding material A will be explained.

First, the upper mold 2 is raised to open the molding space 6, and the convex portion 5 is
Set molding material A on top of.

Next, the press machine is operated to lower the upper mold 2. Then, as shown in FIG. 1, before the mold surface 4a of the upper mold 2 comes into contact with the molding material A, the lower end of the blocking member 1G comes into pressure contact with the lower mold 3, airtightly blocking the molding space 6 from the outside. At the same time,
This blocking member 1G contracts in response to the lowering of the upper die 2 while keeping the molding space 6 airtight. Further, in parallel with the lowering of the upper mold 2, the exhaust pump 15 is driven, and the above-mentioned blocking member 1G
From the stage where the airtightness of the molding space 6 is ensured, the air in the molding space 6 is exhausted through the exhaust ports 11, and the molding space 6 shifts to a low-pressure space.

After that, when the mold surface 4a of the upper mold 2 contacts the molding material A on the convex portion 5, the molding material A is transferred to the mold surfaces 4a and 5 of both molds 2 and 3.
a and flows in all directions of the molding space 6. At this time, the molding material A flows downward in the molding space 6 together with the air at the back of the molding space G and the gas mixed in the molding material A, and this air and gas are removed by the exhaust pump 1.
Coupled with the suction action by 5, it is pushed out at once into the groove 10, from where it is discharged to the outside of the molding space 6 through the exhaust ports 1].

As the molding material A is pressurized, the molding material A is filled into every corner of the molding space 6, and the excess material in the molding space 6 is disposed of in the gap between the concave portion 4 and the convex portion 5. Flows into 8. In this case, since the gap 8 is as small as 0.1 to 0.4 mm, the excess molding material A becomes flaky and protrudes into the groove 10, and is eaten away by the gap 8.

When the upper mold 2 is completely lowered and the mold clamping is completed, the molding material A is densely filled in the molding space G and becomes pressurized.
Accordingly, the exhaust pump 15 is also stopped.

The molding material A pressurized in this way is heated by the heating medium flowing through the flow passage 17 in each mold 2゜3, and is heated in the molding space G.
A polymerization reaction occurs inside the material and hardens it. The molded product B obtained by this curing is taken out by opening the mold 1 after a certain curing time has elapsed, thereby completing a series of wire forming.

According to this embodiment of the present invention, the molding space 6 is airtightly isolated from the outside by the blocking member 1G provided on the upper mold 2 coming into pressure contact with the lower mold 3. The timing at which the molding material A is airtightly shut off and the timing at which compression of the molding material A is started can be set independently from each other,
The timing when the evacuation of the molding space 6 actually starts,
1. For fitting of the second mold 2 and the lower mold 3. Molded product B without being sold
It can be freely set depending on the shape etc.

Therefore, the air in the molding space G can be evacuated from an early stage before the compression of the molding material A starts, and the air in the molding space 6 and the molding material A can be exhausted until the mold clamping is completed. The gas contained therein can be reliably removed.

Therefore, the inclusion of air bubbles that cause small pores and swelling can be suppressed, and a high-quality molded product B with a smooth surface can be obtained.

In the above-described embodiment, the upper die is moved up and down, but the present invention is not limited to this, and the lower die may be moved up and down, or a blocking member may be attached to the lower die.

〔Effect of the invention〕

According to the present invention described in detail above, the timing at which the molding space is airtightly shut off and the exhaust is actually started is determined according to the shape of the molded product, etc., without being restricted by the compression start timing of the molding material. It can be set freely, and air in the molding space and gas contained in the molding material can be reliably eliminated until the mold clamping is completed. Therefore, during compression molding, air bubbles that cause small pores and bulges are not trapped in the molding material, and a high-quality molded product with a smooth surface can be obtained.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a sectional view of the molding space in a state where the molding space is hermetically sealed, and FIG. 2 is a sectional view of the mold after mold clamping is completed.

Claims (1)

[Claims] A pair of molds that can be moved toward and away from each other is provided, a molding space is formed between the mold surfaces of these two molds in which a thermosetting resin molding material is compression molded, and this molding space is evacuated by an exhaust device. , characterized in that one of the molds is provided with a cylindrical blocking member that is expandably and contractibly pressed against the other mold as the mold moves, and airtightly blocks the molding space from the outside. A mold for compression molding thermosetting resin.