JPH07328B2 - Thermosetting resin molding method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting resin molding method capable of omitting a surface finishing process and a cleaning operation for a molded product released from a mold.

[0002]

2. Description of the Related Art As shown in FIG. 6, in a molded product A which is mainly composed of a thermosetting resin and which has been molded by a conventional method and which has just been released from the mold, a burr a is formed at a portion corresponding to a mold matching surface.
In addition, a gate port runner b facing the cavity of the mold is integrally provided in the molded body A, and a trace c of the core pin or the like is present at a contact position with the core pin used for mold release. Therefore, in any case, it is not only necessary to secondarily perform surface finishing processing such as barrel processing, deflasher processing, short blast processing after mold release, and resin powder adhered to the product surface by secondary processing, It was usually necessary to perform several washing operations in order to remove the minute dust that inevitably adheres to the product surface due to the electrostatic phenomenon accompanying the secondary processing.

[0003]

However, according to the conventional method in which a molded product after release is subjected to secondary processing and cleaning work to obtain a product, the number of steps is increased and the production efficiency is reduced and the production cost is reduced. There was a problem of leading to soaring prices. In addition, not only toxic gas is generated in the cleaning work after secondary processing, but also in the removal process of polluted accumulated soil and the process process of scattered dust and cleaning waste liquid, various environmental factors such as air and water quality There was a concern that it could not be ignored. In particular, it has been extremely difficult to deal with CFC-based substances used as cleaning agents, for which the movement of prohibition of use has become remarkable recently.

The present invention has been made in view of the above circumstances, and by improving the molding method of the above-mentioned molded body, the above-mentioned secondary processing and cleaning work are unnecessary, and the improvement of the production efficiency and the production due to the labor saving are achieved. An object of the present invention is to provide a molding method of a thermosetting resin which enables cost reduction and has no room for producing various adverse effects such as environmental pollution that cannot be ignored.

[0005]

The method for molding a thermosetting resin according to the present invention is a method of molding a mold clamped at a low pressure with a low injection pressure,
In the first molding step, the first molding step of injecting the molding material mainly composed of thermosetting resin under the low speed condition and the runner of the gate opening facing the cavity of the mold at the end of the first molding step are molded in the first molding step. A method of including a runner cutting step of cutting the primary molded body that has been cut, and a second molding step of compressing the primary molded body inside the cavity by switching the mold clamping pressure to a high pressure at the end of the runner cutting step. is there.

[0006]

In the present invention, the mold clamping pressure of the mold is switched from the low pressure to the high pressure after the runner is cut from the primary molded body molded by the mold clamped at the low pressure. As a result, with respect to the molded body immediately after release from the mold, burrs are eliminated at a portion corresponding to the mold matching surface, and traces of the gate opening and core pins are not left. Therefore, the above-mentioned secondary processing for removing traces of the burr, the gate opening, and the core pin becomes unnecessary, and at the same time, the cleaning work becomes unnecessary.

[0007]

EXAMPLE A thermosetting resin molding method according to the present invention includes a first molding step, a runner cutting step, and a second molding step, and is obtained by a first molding step using a mold clamped at a low pressure. The second molding step is performed using the above-mentioned mold clamped at high pressure without performing mold release after performing runner cutting on the primary molded body without performing mold release.

Next, an embodiment of the present invention will be described.

In the first molding step, the mold clamping pressure is set to a low pressure of 0 to 45 kg / cm ^{2 as} a gauge pressure, and the injection pressure is set to be lower than the normal injection pressure which is generally used conventionally. Also, the injection speed of the molding material is set to be lower than the normal speed which has been generally used conventionally. Then, as shown in FIG. 5, after the mold is clamped, the injection device is advanced so that the nozzle faces the injection port of the mold, and injection is performed under the above-mentioned conditions. In this case, when injecting the molding material supplied from the nozzle of one injection device into a plurality of molds, it is desired to keep the flow balance of the molding material.

FIG. 1 is an explanatory view showing a primary molded body A1 obtained in the first molding step and a core pin 10 attached to a mold. As can be seen in this figure, the primary molded product A
In No. 1, since it is molded with a low mold clamping pressure, the thickness t is 0.1 to 0.4 mm (the size of the primary molded body or the molding material is less than the contact point between the core pin 10 and the primary molded body A1). The built-up portion 11 having a different numerical value depending on the type etc. is formed.

When the supply of the molding material from the nozzle of the injection device in the first molding step is completed, the nozzle is retracted together with the injection device at the same time (see FIG. 5), and the next time the injection device is operated. Weigh the molding material.

FIG. 2 is an explanatory view showing the primary molding A1 at the end of the first molding step, the gate opening 20 of the mold, and the molding material supply passage 21 communicating with the gate opening 20. As shown in the figure, at this time, the gate opening 20 naturally faces the cavity 22 of the mold at this point.

FIG. 3 is an explanatory view of the runner cutting process. In this runner cutting step, the runner cut described in FIG. 5 is performed by activating a dedicated ejecting mechanism with good timing and moving the gate port 20 as shown in FIG. By doing so, the runner 12 molded of the resin inside the gate port 20 is removed from the primary molded body A1.

Next, in the second molding step, the mold clamping pressure is switched to a high pressure of 100 to 140 kg / cm ² in gauge pressure immediately after cutting the runner 12 without releasing the primary molded body A1 (see FIG. 5), the injection pressure is set to be the same as the normal injection pressure that has been conventionally used in general, and the injection speed of the molding material is also the same as the normal speed that is generally used in the past. Set. By performing this second molding step, the primary molded body A1 is compressed, and the above-mentioned built-up portion 11 (see FIG. 1) is compressed and disappears as shown in FIG. At the same time, the burrs and the gate opening 2 formed at a position corresponding to the mold matching surface of the primary molded body A1.
The trace of 0 (neither is shown) disappears. Since the appropriate holding time of the mold clamping pressure in the second molding step varies depending on the molding target, it is desirable to appropriately change the set time according to the molding target.

After the holding pressure in the second molding step has elapsed, the mold is opened, and then the core pin 10 is projected to release the molded body A from the mold. Then, the molded body A is taken out from the mold by using a robot or the like. In this case, when a plurality of molded bodies A are molded at the same time, they are carefully taken out while preventing mutual contact between the molded bodies A.

The molded product A finally released from the mold through the first molding process, the runner cutting process, and the second molding process described above does not have burrs at a portion corresponding to the mold matching surface, and the core < traces of br /> over pin 10 and the gate opening even be those which do not have. For this reason, it is not necessary to perform secondary processing or cleaning work for surface finishing after the mold release. Therefore, the molded body A taken out of the mold can be immediately packaged as a product.

Typical thermosetting resins that are the main constituents of the molding material include urea resins, phenol resins, epoxy resins, polyester resins, and other resins widely used in electrical parts. Therefore, it is possible to use a thermosetting resin which has been widely known in the art, for carrying out the present invention.

[0018]

EFFECTS OF THE INVENTION According to the present invention, since there is no burr on the molded body immediately after releasing from the mold and the traces of the gate port and the core pin are not left, surface finishing and cleaning by the complicated secondary processing explained at the beginning. It becomes unnecessary to carry out the work, so that the number of steps can be reduced, the production efficiency can be improved, and the production cost can be reduced.

Further, since the secondary processing and cleaning work are not required, it becomes possible to package the molded body immediately after releasing from the mold as a product as it is, and at the same time, generate toxic gas associated with cleaning and release air into the atmosphere. There is no room for environmental pollution such as water pollution. Especially, since cleaning work is unnecessary,
It will not be necessary to use CFC-based substances prior to the implementation of the ban on the use of CFC-based substances.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a primary molded body and a core pin obtained in a first molding step.

FIG. 2 is an explanatory diagram showing a primary molded body, a gate port, and a molding material supply passage at the end of the first molding step.

FIG. 3 is an explanatory diagram of a runner cutting process.

FIG. 4 is an explanatory diagram showing a molded body and a core pin at the end of the second molding step.

FIG. 5 is a flow chart showing an embodiment of the present invention.

FIG. 6 is a schematic perspective view of a molded body molded by a conventional method.

[Explanation of symbols]

 12 Runner 20 Gate opening 22 Cavity A Molded body A1 Primary molded body

Claims (1)

[Claims] 1. A first molding step of injecting a molding material mainly composed of a thermosetting resin under a low injection pressure and a low speed into a mold clamped at a low pressure, and the end of the first molding step. Occasionally, the runner at the gate opening, which faces the mold cavity, is cut from the primary molded product molded in the first molding process, and at the end of the runner cutting process, the mold clamping pressure is switched to high pressure and the cavity And a second molding step of compressing the primary molded body inside, a method of molding a thermosetting resin.