JPH06328538A - Heat cycle system for injection molding - Google Patents

Abstract

PURPOSE:To perform heating and cooling with high efficiency even though a simple installation is used by constituting the system of a heating apparatus energizing a heater and a controller controlling a cooling apparatus and the heating apparatus based on the detected temp. of a temp. sensor. CONSTITUTION:An insert 3 is made of a material with high thermal conductivity and is made into a shape being fittable in a recessed part of a fixed side mold plate 12 and is fixed with a bolt 7. The lower face of the insert 3 is to be a cavity face 3a and a temp. sensor 4 is buried in this neighborhood. On the other hand, between the upper face of the insert 3, namely the opposite side of the cavity face and the fixed side mold plate 12, a space to be a path for a cooling medium is formed and the cooling medium is fed thereinto from a cooling apparatus 8 through a pipeline 5a. A heater 6 is provided in a cooling medium path 5 to heat the cooling medium in the cooling medium path by energizing it from the outside heating apparatus 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a temperature control device for an injection molding die, particularly for injection molding, which is suitable for molding an optical molded product and which can perform highly accurate injection molding with a high resin packing density. Regarding heat cycle system.

[0002]

2. Description of the Related Art Conventionally, in the injection molding of high precision moldings and thick-walled moldings of this type, the resin temperature is raised above the glass transition point to improve the resin fluidity and then the resin is injected. ,
After injection, the mold is forcibly cooled to shorten the molding cycle and the molded product is taken out.

Here, as the heating / cooling means of the die,
For example, as disclosed in Japanese Examined Patent Publication No. 61-43169, a water pipe is provided around the cavity to selectively flow high-pressure steam and cold water to heat and cool the mold, and Japanese Patent Laid-Open No. 1-200925. As described above, it is known that a cooling water pipe is provided in the mold and a heater is also provided for heating and cooling.

[0004]

However, the above-mentioned conventional device has the following problems. Japanese Patent Publication 61-
In the apparatus of Japanese Patent No. 43169, high-pressure steam and cold water are alternately flowed through a single water pipe, so that there is a problem in that it is difficult to shorten the molding cycle due to the time lag of temperature conversion involved in the switching. It was In addition, there is a problem that a large-scale boiler is required because high-pressure steam is instantaneously supplied.

In the apparatus disclosed in Japanese Patent Laid-Open No. 1-200925, heating is performed by a heater so that the equipment can be downsized. However, since the heater is directly embedded in the mold, only the periphery of the heater is rapidly heated. As a result, the temperature distribution becomes uneven, and the quality of the molded product deteriorates (such as sink marks). If the heater is placed away from the cavity in order to solve such a problem, the heating efficiency is deteriorated and the molding cycle becomes long.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an injection molding heat cycle system capable of heating and cooling with high efficiency while using simple equipment.

[0007]

In order to achieve the above object, the heat cycle system for injection molding of the present invention comprises a mold having a cavity surface fitted with a nest, and a mold provided near the cavity surface of the nest. A temperature sensor, a refrigerant liquid passage provided on the anti-cavity surface of the nest, a heater arranged in the refrigerant liquid passage, a cooling device for supplying a refrigerant to the refrigerant liquid passage, and the heater is energized. A heating device,
The control device controls the cooling device and the heating device according to the temperature detected by the temperature sensor.

[0008]

In the heat cycle system for injection molding of the present invention having the above-mentioned structure, the heating device is energized prior to the injection molding. Then, the insert is indirectly heated via the refrigerant, and the cavity surface is uniformly heated. When the temperature of the cavity surface reaches the required temperature, the resin is injected, and after the injection, the refrigerant flows from the cooling device into the refrigerant liquid passage to cool the mold.

[0009]

Embodiments of the heat cycle system for injection molding according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a heat cycle system for injection molding. As shown in the figure, in this apparatus, a mold 3 is fitted with a nest 3, and a cavity 2 is formed on a lower surface of the nest 3, while an upper surface of the nest 3 is configured as a refrigerant liquid passage 5.

In the mold 1, the upper portion of the PL line in the figure is a fixed portion and the lower portion is a movable portion. That is, the fixed side mounting plate 11
The fixed-side mold plate 12 is fastened and fixed with bolts 13, and the spacer block 17 and the movable-side mold plate 18 are fastened and fixed with bolts 19 to the movable-side mounting plate 16. Further, the spool bush 14 is fixed to the fixed-side mold plate 12 with a bolt 15, and the ejector pin 20 is attached by being sandwiched between the projecting plate 21 and the projecting plate 22.

The insert 3 is made of a material having a high thermal conductivity (for example, a material having a thermal conductivity of 150 kcal / mh ° C. or higher such as brass or aluminum) and is housed in the recess of the fixed-side mold plate 12. It is formed in a shape and is attached with bolts 7. The lower surface of the nest 3 is a cavity surface 3a, and a temperature sensor 4 (a thermocouple in this embodiment) is embedded near the cavity surface 3a. On the other hand, the upper surface of the nest 3, that is, the anti-cavity surface 3b
And a fixed-side mold plate 12 form a space forming the refrigerant liquid path 5 so that a refrigerant (specifically, water or oil) is supplied from the cooling device 8 via the pipe 5a. Has become. Further, a heater 6 is installed in the refrigerant liquid passage 5 so as to heat the refrigerant in the refrigerant liquid passage 5 by energization from an external heating device 9.

The control device 10 controls the cooling device 8 and the heating device 9 according to the temperature detected by the temperature sensor 4, as will be described later in detail.

Next, the operation of this embodiment will be described. FIG. 2 is a time chart showing a temperature change during the operation of the embodiment. When the mold 1 is closed, a mold closing signal is output from the molding machine main body (not shown) to the control device 10. Receiving this, the control device 10 issues a heating signal to the heating device 9, and the heater 6 is energized to heat the refrigerant in the refrigerant liquid passage 5. Then, the nest 3 is indirectly heated by the heat conduction of the refrigerant, so that the temperature rises uniformly. Here, the temperature of the nest 3 is managed by the temperature sensor 4.

When the temperature of the insert 3 becomes higher than the glass transition point of the resin, the controller 10 outputs a heating completion signal to the heater 9 and the heater 6 is turned off. At the same time, a heating completion signal is also sent to the molding machine body, and the molding machine injects resin into the mold. At this time, since the cavity surface 3a of the insert 3 is heated to a temperature higher than the glass transition point of the resin, the generation of the skin layer due to the temperature difference between the mold surface and the resin fluidized bed is suppressed, A high filling property can be obtained with respect to the mold surface shape.

After the injection is completed, the injection completion signal is output from the molding machine body to the control device 10. In response to this, the control device 10 issues a cooling signal to the cooling device 8 to allow the refrigerant to flow through the refrigerant liquid path to cool the nest 3 and thus the cavity 2. When the cavity surface 3a is cooled to a predetermined cooling completion temperature, the mold 1 is opened and the molded product is taken out by the ejector pin 20. At the same time, the control device 10 receiving the mold opening signal from the molding machine body commands the cooling device 8 to stop the supply of the refrigerant.

By repeating the above molding cycle, high precision molded products such as optical products and thick wall molded products can be injection molded in an extremely short molding cycle.

The present invention is not limited to the above embodiment, but may be carried out, for example, as follows. (1) As shown in FIG. 3, a heater 6 having a ring shape is used. Accordingly, the recess of the insert 3 should be formed in a ring shape. By doing so, the refrigerant in the refrigerant liquid path is heated radially, so that the insert 3 can be heated more uniformly.

(2) As shown in FIG. 4, the cavity surface 3a of the insert 3 is formed in a convex shape. For example, this is a case where the molded product is a lens with a large uneven thickness. In this case, the temperature sensor 4 may be arranged on the side surface of the insert 3. This example also has the following effects. That is, at the time of injection, the cavity surface 3a has a temperature higher than the glass transition point, so that the generation of the skin layer is suppressed as described above, but at this time, the movable side mold plate 18 has a lower temperature, Cooling has started. Therefore, the internal temperature of the molded product has a uniform temperature distribution with a temperature gradient as shown in FIG. This temperature gradient does not change even with the progress of cooling, and a uniform molded product with stable and good shape accuracy can be obtained by such uniform cooling.

[0019]

As described above, according to the heat cycle system for injection molding of the present invention, it is possible to perform heating / cooling with high efficiency while using simple equipment.
There is an advantage that a precision molded product having a highly accurate optical mirror surface can be easily manufactured.

[Brief description of drawings]

FIG. 1 is a partially cutaway view showing a heat cycle system for injection molding of the present invention.

FIG. 2 is a diagram showing an operation of a heat cycle system for injection molding.

FIG. 3 is a view showing a main part of another embodiment of a heat cycle system for injection molding.

FIG. 4 is a view showing a main part of still another embodiment of a heat cycle system for injection molding.

FIG. 5 is a diagram showing a temperature distribution of a molded product.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mold 2 Cavity 3 Nest 3a Cavity surface 3b Anti-cavity surface 4 Temperature sensor 5 Refrigerant liquid path 5a Piping 6 Heating heater 7 Bolts 8 Cooling device 9 Heating device 10 Control device 11 Fixed side mounting plate 12 Fixed side mold plate 13 Bolts 14 Spool Bushings 15 Bolts 16 Movable Side Mounting Plates 17 Spacer Blocks 18 Movable Side Mold Plates 19 Bolts 20 Ejector Pins 21 Projection Plates 22 Projection Plates

Claims (1)

[Claims] 1. A mold having a cavity fitted in a cavity surface, a temperature sensor provided in the vicinity of the cavity surface of the nest, a refrigerant liquid passage provided in an anti-cavity surface of the nest, and the refrigerant liquid. A heating heater disposed in the passage, a cooling device that supplies a refrigerant to the refrigerant liquid passage, a heating device that energizes the heating heater, and the cooling device and the heating device are controlled according to the temperature detected by the temperature sensor. A heat cycle system for injection molding, comprising a control device.