JPH02206523A - Mold, in which molded item is removed from its tip, and molding method therewith - Google Patents

Abstract

PURPOSE:To prevent flash from developing at injection process even when high speed and high pressure are applied thereon, by a method wherein an outer piece, which slides on an inner piece and is made of mateiral having a linear expansion coefficient smaller than that of the inner piece so as to perfectly fit the inner piece and the outer piece to each other at injection process and these pieces are made to be slidable one upon other at the extraction of a molded item. CONSTITUTION:In case of the molding of a molded item 1, at injection process, in which molten resin is injected in a mold, the mold is heated up to an elevated temperature and the mold of an inner piece 3 expands so as to bring the clearance between the sliding parts 4 of an outer piece 3 and of the inner piece 2 at the state before the early injection process to the completely closed state, resulting in preferably fitting the inner piece 2 to the outer piece 3. As a result, even when molten resin flows in the mold, no flowing of resin through the clearance between the pieces occurs at all. Next, at the extraction of the molded item 1 through the processing and cooling process after the finish of the injection process, the temperature of the mold is lowered to the temperature at the time of extraction of molding so as to enlarge the clearance in order to make the inner and outer pieces 2 and 3 slidable with each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a mold having light waves for molded products used in injection molding and the like, and a molding method using the mold.

[Prior Art] In a conventional mold device used for a mold having a light wave for molded products, as shown in the conventional mold device in FIG.
When the molded product is exposed to light waves using a stripper plate, etc., that is, when the inner piece 3 and the outer piece 2 slide against each other when taking out the molded product, the sliding inner piece 3 and the outer piece 2 fit together. A clearance is provided, such as in the sliding part 4.

[Problems to be Solved by the Invention] However, since the conventional mold device using a mold having light waves for molded products is configured as described above, if the clearance is small, the frictional resistance of the sliding part 4 will increase. Too large may cause malfunction.

Further, during molding, molding defects such as burrs may occur, and the burrs may get caught in sliding parts, resulting in problems such as malfunction of the mold.

Therefore, the mold having light waves for molded products of the present invention and the molding method using the mold have been made in view of these problems, and the purpose is to reduce the frictional resistance of the sliding part regardless of the size of the clearance. The object of the present invention is to provide a mold having a light wave of a molded product, which does not have much friction, has no malfunction of sliding parts due to moderate friction, and completely eliminates the occurrence of flashing during molding.

Furthermore, since the sliding parts fit together snugly during the injection process, molded products with various excellent effects such as no defective phenomena due to the generation of flakes even when high speeds and high pressures are applied during the injection process. The object of the present invention is to provide a mold having light waves and a molding method using the mold.

[Means for Solving the Problems and Effects] In order to solve the above problems and achieve the purpose, a mold having light waves for a molded article according to the present invention has the following configuration. In the mold, the sliding inner piece is made of a material with a large linear expansion coefficient, and the outer piece is made of a material whose linear expansion coefficient is smaller than that of the inner piece, so that the outer piece and the inner piece are They are constructed so that they fit completely and can be slid when the molded product is taken out.

In addition, the method of molding a molded product using a mold having light waves according to the present invention includes providing a sliding inner piece with a temperature-adjustable heating medium conduit in the mold having light waves, and molding the molded product during the injection process. The mold is heated to a high temperature, and after injection is completed, a pressurization and cooling process is performed, and the mold temperature is cooled to a low temperature when the molded product is taken out.

[Example] Hereinafter, an example will be described in detail according to the drawings. FIG. 1 is a sectional view of a main part of a mold having a light wave for a molded product according to an example. In FIG. 1, to explain the general configuration of a mold for obtaining a molded product l, a gate body 15 into which high-temperature and high-pressure resin is injected, a first mold body IO, and a second mold body 11 are connected to an injection molding machine. Provided on the fixed side.

On the other hand, on the movable side of the injection molding machine, there is a third mold body 12 holding the outer piece 2 and a fourth mold body 1 holding the inner piece 3.
3 and a fifth mold body 14 in which a heat medium pipe line 6 is provided are movably provided. Inside the outer piece 2, there is provided an inner piece 3, which forms a male mold of the inner peripheral surface of the molded product 1, as shown in the figure. As shown in the figure, an ejector turbine 17 is provided to be inserted through the interior of the inner piece 3.

The mold with the above configuration is the bartending line PL.

and PL2, and after dividing by the dividing plane of the bartending line PL, the dividing plane is divided by the dividing plane of the bartending line PL.

FIG. 2 is a sectional view for explaining the operation, and shows that the sliding inner piece 3 is made of a material with a larger coefficient of linear expansion than the outer piece 2, such as copper.
This represents the case where copper alloy etc. are used. In FIG. 2, the outer piece 2 is made of a material having a smaller coefficient of linear expansion than the inner piece 3, such as stainless steel. Inner piece 3 like this
By using materials with different linear expansion coefficients for the inner piece 3 and the outer piece 2, a clearance 5 is designed based on temperature changes and expansion coefficients at the sliding part 4 between the inner piece 3 and the outer piece 2, as shown in Fig. 2. Set it up to a certain size.

As a result, when molding the molded product 1, the mold temperature is heated to a high temperature during the injection process in which molten resin is injected into the mold, and the mold of the inner piece 3 expands, causing the mold to expand before the first injection process. In this state, the clearance part becomes completely sealed and they fit together.

As a result, even if the molten resin flows into the mold, it will never flow out from the gaps between the pieces. After the injection process is completed, the molded product is taken out after the pressurization and cooling process.
The mold temperature is the molded product removal temperature, and at the same time the inner piece 3
The temperature is lowered until the clearance 5 of the sliding part 4 between the outer piece 2 and the outer piece 2 becomes the set value.

As a result, the inner piece 3 has a larger coefficient of linear expansion than the outer piece 2, so the thermal contraction is large, and as shown in FIG. 2, the clearance 5 between the outer piece and the inner piece is again large. Sliding becomes extremely easy.

Furthermore, in the second invention, a temperature-adjustable heat medium pipe 6 is provided in the sliding inner piece, and a heating medium such as steam or a cooling medium such as water is passed through the heat medium pipe to complete the injection process. The temperature can be adjusted by heating at the time of molding or cooling with water at the time of taking out the molded product. In this way, during the injection process, the inner piece 3 is heated by passing heating steam etc. through the heat medium circuit, and after the injection is completed, by changing to water cooling in the pressurization and cooling process, the inner piece 3 is cooled, and then the molded product is When the molded product is taken out in this way, a clearance 5 is created between the outer piece and the inner piece, and the operation of the sliding part can be made extremely easy.

Inner piece: Copper alloy (HR-75
0), when the outside piece was made of stainless steel (HPM-38), the following temperature changes and 9 dimensional changes were shown.

Room temperature (25℃) 100℃ 150℃ Inner piece, outer diameter dimension φ67, 960mm 68.046m
m 68.104 outer piece, inner diameter dimension φ68.000mm
68.061 mm 68.101 Therefore, the molding process was performed at a mold temperature of 150° C. during injection and a mold temperature of 100° C. when taking out the molded product. As a result, a clearance was created due to the difference in expansion coefficients, and the sliding parts worked well, and no defects caused by flashing during molding occurred.

[Effects of the invention] As mentioned above, there is not much frictional resistance in the sliding parts, and due to the moderate friction, there is no malfunction of the sliding parts, and the occurrence of flash during the injection process and molding process is completely eliminated. Resolved. Furthermore, since the sliding parts can be tightly fitted during the injection process, there are various excellent effects such as no defective phenomenon due to the occurrence of flakes even if high speeds and high pressures are applied during the injection process.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main part of the embodiment, FIG. 2 is an explanatory diagram of the operation of the embodiment, and FIG. 3 is a sectional view of the conventional method. In the figure, 1...molded product, 2...outer piece, 3...inner piece,
4...Sliding part, 5...Clearance, 6...Heat medium pipe line.

Claims (2)

[Claims] (1) In a mold having a tip for the molded product, the sliding inner piece is made of a material with a large linear expansion coefficient, and the outer piece is made of a material whose linear expansion coefficient is smaller than that of the inner piece. This ensures that the outer piece and inner piece fit together completely during the injection process.
A mold having a tip for removing a molded product, characterized in that it is slidable when the molded product is taken out. (2) In a mold with a tip for molded products, a temperature-adjustable heating medium pipe is provided in the sliding inner piece, the mold temperature is heated to a high temperature during the injection process, and after injection is completed, pressure is applied and cooled. A molding method characterized by cooling the mold at a low temperature during the process and when taking out the molded product.