JPH0460419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection molding machine, and more particularly to a mold adjustment device that can adjust the amount of heat released from a mold.

[Conventional technology]

The schematic structure of the injection molding machine will be explained with reference to FIG. 3. A fixed mold 2 is fixed on one surface of the fixed platen 1, and a movable mold 4 is fixed on one surface of the movable platen 3. The movable platen 3 is movably attached to the diver 5. An injection molding cavity 6 is formed by the fixed mold 2 and the movable mold 4. A sprue 7 communicating with an injection molding cavity 6 is formed in the fixed platen 1 and the fixed mold 2.

The injection device 8 includes a popper 9 and an injection actuator 1.
0 and an injection cylinder 11, and the injection device 8 is driven in the horizontal direction in the figure by a drive mechanism (not shown).

When injecting molten resin, first the fixed mold 2 and the movable mold 4 are clamped, and the injection cylinder 11 is moved. The tip of the injection cylinder 11 and the fixed mold 2
When a detector such as a limit switch detects that the injection cylinder 11 has come into contact with the sprue 7 formed on the injection cylinder 11, the movement of the injection cylinder 11 is stopped. Immediately thereafter, molten resin is injected into the cavity 6 from the injection cylinder 11 to perform injection molding.

[Problem that the invention seeks to solve]

By the way, during injection molding work, heat is radiated from the fixed mold 2 and the movable mold 4, and if the ambient temperature is stable, the amount of heat radiated is almost constant and does not affect the molded product. However, at the start of injection molding work, not only the surface (hereinafter referred to as exposed surface) temperature of the mold but also the ambient temperature are unstable, and the amount of heat released from the mold fluctuates. This means that the mold temperature distribution fluctuates, and while the mold temperature distribution fluctuates, variations occur in the appearance, strength, and dimensional accuracy of the molded product.

As described above, conventional injection molding machines have had the problem that they cannot stably produce molded products with desired specifications for a certain period of time after the start of molding work.

In view of these problems, it is an object of the present invention to provide a mold temperature control device for an injection molding machine that can stably produce molded products that meet specifications within a short time after the start of injection molding work.

[Means for solving problems]

The mold temperature control device for an injection molding machine according to the present invention provides a heating element on the exposed surface of the mold, and also includes means for detecting the temperature of the exposed surface, and sets a radiation pattern of the amount of heat radiation from the mold. and means for controlling the amount of heat generated by the heating element in accordance with the output from the temperature detection means.

[Effect]

The mold temperature control device according to the present invention heats the mold with a heating element until the temperature of the exposed surface of the mold reaches a certain temperature at the start of injection molding work, so that the temperature of the exposed surface of the mold quickly reaches a constant temperature range. This increases the temperature of the exposed surface of the mold and also increases the ambient temperature.
Quickly bring the mold temperature distribution to a steady state. In addition,
Steady state refers to a state where there is almost no temperature change.

〔Example〕

FIG. 1 shows a mold to which the present invention is applied and its heat radiation amount adjustment system. In the figure, among the surfaces of the fixed mold 2 and the movable mold 4, the exposed surfaces excluding the mounting surface to the platen and the mutual butting surfaces, that is, the exposed surfaces parallel to the moving direction of the movable mold 4 (arrow in the figure) Planar electric heaters 12 and 13 are provided on the side surfaces, respectively, in a grounded state. Furthermore, detection ends of temperature detectors 14 and 15 are arranged at arbitrary positions on the exposed surfaces of the fixed mold 2 and the movable mold 4, here points P and Q, respectively.
The output signals of the temperature detectors 14 and 15 are sent to the arithmetic control section 1.
Enter 6.

In addition to the output signals from the temperature detectors 14 and 15, the calculation control unit 16 receives a signal from a heat radiation amount pattern setting device 17, which will be described later. Arithmetic control unit 16
performs a predetermined calculation based on the output signals from the temperature detectors 14 and 15, as described later, and uses the calculation result and the heat radiation amount pattern setting device 1.
7 and outputs a voltage signal according to the comparison result. The output of the calculation control unit 16 is connected to the electric heaters 12 and 13, thereby controlling the amount of heat generated by the electric heaters 12 and 13.

Figure 2 shows the amount of heat dissipated from the mold and the exposed surface temperature (1st
Points P and Q in the figure show time changes in the voltage applied to the electric heater.

When the injection molding operation starts, the heat radiation amount pattern setting device 17 outputs the target value of the heat radiation amount from the mold in a pattern as shown by the solid line 19 in FIG. 2a. The calculation control unit 16 calculates the current amount of heat radiation from the mold based on the temperature detection signals from the temperature detectors 14 and 15. The calculation control unit 16 also compares the heat radiation amount target value from the heat radiation amount pattern setter 17 and the current heat radiation amount based on the calculation result, and if the current heat radiation amount is larger, the electric heaters 12, 13
Reduce the amount of heat generated, and if it is less, increase the amount of heat generated. In this way, the amount of heat dissipated from the mold is adjusted to match the target value, as shown by the broken line 20 in FIG. The temperature increases to the steady state temperature, and the mold temperature distribution becomes steady state. In addition, the reason why the amount of heat radiation is made excessive before the amount of heat radiation is made constant in FIG. 2a is to quickly raise the ambient temperature of the mold to the temperature in the steady state. Moreover, the dashed-dotted line in FIG. 2a shows the change in the amount of heat dissipation in the conventional case. Time A indicates the start of the injection molding operation, and even if the temperature of the exposed surface of the mold or the ambient temperature changes during the injection molding operation, the temperature distribution of the mold will be in a steady state due to the above-mentioned operation. become.

In the embodiment, the electric heater is provided on the entire side surface of the mold, but it may be provided on only one of the four sides. In this case, one end is connected to the calculation control unit 16 and the other end is grounded. . In addition, as a heating element,
For example, the heat generating side of an electronic refrigeration element using the Peltier effect may be used.

〔Effect of the invention〕

As explained above, according to the present invention, by providing a heating element in the mold so that the amount of heat radiated from the mold can be adjusted, the temperature distribution of the mold can be quickly brought to a steady state at the start of injection molding work. At the same time, the ambient temperature can also be brought to a predetermined stable state. This makes it possible to produce molded products with little variation in appearance, strength, dimensional accuracy, etc. not only during steady operation but also at the start of work.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention with respect to a mold and its heat dissipation adjustment system. FIG. The figure shown in FIG. 3 is a diagram schematically showing the configuration of the main parts of a general injection molding machine. In the figure, 2 is a fixed mold, 4 is a movable mold, 12, 1
3 is an electric heater, 14 and 15 are temperature detectors, 16
17 is a calculation control unit, and 17 is a heat radiation amount pattern setting device.

Claims (1)

[Scope of Claims] 1. A heating element is provided on the exposed surface of the mold, and a means for detecting the temperature of the exposed surface is provided, a means for setting a heat radiation pattern of the amount of heat radiated from the mold, and the temperature detecting means. A mold temperature control device for an injection molding machine, comprising means for controlling the amount of heat generated by the heating element according to the output from the heating element. 2. The mold temperature control device for an injection molding machine according to claim 1, wherein the heating element is a planar electric heater. 3. The control means calculates the amount of heat released from the mold based on the output of the temperature detection means, and adjusts the amount of heat released from the heating element according to a comparison result between the calculation result and the output of the heat radiation pattern setting means. A mold temperature control device for an injection molding machine according to claim 1 or 2, characterized in that the device controls the temperature of a mold.