JPH0513543Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a mold temperature controller for detecting the temperature of a mold and controlling heating and cooling of the mold within a predetermined temperature range.

[Prior Art] This type of mold temperature regulator is generally constructed as shown in FIG. 3. That is, first, the mold 1 whose temperature is controlled will be explained.
As shown in FIGS. 4a and 4b, it is composed of a fixed mold part 3 and a movable mold part 4. Each mold part 3, 4 is provided with temperature control pipes 6, 7 for circulating the temperature control medium from the base temperature control source 5,
The temperatures of both mold parts 3 and 4 are controlled to be constant via a mold base temperature sensor 8 disposed within the fixed mold part 3.

Each mold part 3, 4 is equipped with inserts 9, 10, and the fixed mold part 3 is provided with a temperature control tube 11 that is separate from the base temperature control tube 6. Adjustment 1
1 communicates with the base portion of the fixed mold portion 3 and the insert 9.

A temperature sensor 12 for the insert is disposed inside the insert 9, and the temperature sensor 12 for the insert is configured to be connected to the mold temperature controller 2. The mold temperature controller 2 is composed of a temperature controller 13, a sequence control circuit section 14, and a temperature control section 15, and controls the mold temperature through the mold temperature signal 16 sent from the insert temperature sensor 12. The mold 1 is constructed so that the temperature can be adjusted between an upper limit temperature setting value and a lower limit setting temperature value, as shown in the graph of FIG. 6a. That is, the mold temperature signal 16 detected by the temperature sensor 12 is input to the temperature controller 13, and the mold temperature signal 16 from the temperature sensor 12 is set at a predetermined upper limit setting value or a predetermined upper limit value shown in FIG. 6a. When the signal is the lower limit setting value, a changeover switch (not shown) in the temperature controller 13 is activated, and the temperature control pipe 11 of the mold 1 is activated via the temperature control section 15.
Low temperature oil (cooling medium) or high temperature oil (heating medium) inside
are now being switched and distributed.

The temperature control unit 15 includes a low temperature oil supply unit 17 for supplying and circulating low temperature oil into the temperature control pipe 11 of the mold 1;
It is comprised of a high temperature oil supply section 18 for supplying and circulating high temperature oil into the temperature control tube 11 of the mold 1, and an electromagnetic valve section 19 for switching the oil flow path. The low-temperature oil supply section 17 includes a cooling tank (low-temperature oil tank) 21 containing low-temperature oil 20 and a cooling tank pump 22 for supplying the low-temperature oil 20 into the mold 1. Low temperature oil from 20
is a low-temperature oil feed solenoid valve 23 whose opening is controlled.
It is designed to be sent into the mold 1 through the following steps.
Further, the return oil that has cooled the mold 1 is drained into the cooling tank 21 via a low-temperature oil return electromagnetic valve 24. The high-temperature oil supply section 18 includes a heating tank (high-temperature oil tank) 2 containing high-temperature oil 25.
6 and a heating tank pump 27 for supplying high-temperature oil 25 into the mold 1. The high-temperature oil 25 from the pump 27 passes through a high-temperature oil feed solenoid valve 28 whose opening is controlled. After that, it is fed into the mold 1. Further, the return oil that has heated the mold 1 is drained into the heating tank 26 via a high-temperature oil return electromagnetic valve 29.

FIG. 5 shows a schematic diagram of the sequence control circuit section 14. In the figure, 30 indicates an a contact operated by the temperature controller 13, and 31 and 32 indicate an a contact operated by a relay 33.
It is a contact point and a b contact point. In this circuit, when the temperature detected by the temperature sensor 12 in the mold 1 reaches the lower limit set value shown in FIG.
A current flows through the relay 33, and the excitation of the relay 33 causes the high-temperature oil feed solenoid valve 28 and the heating tank pump 2 to be activated.
A voltage is applied to 7. By applying this voltage, the high-temperature oil feeding electromagnetic valve 28 is opened and the heating tank pump 27 is started, so that the high-temperature oil 25 is supplied into the mold 1 and heating is started. Further, when the temperature detected by the temperature sensor 12 in the mold 1 reaches the upper limit set value shown in FIG. 6a, the changeover switch in the temperature controller 13 is reset, and the relay 33 is also reset. When the relay 33 returns, the low-temperature oil feeding electromagnetic valve 23 opens and the cooling tank pump 22 starts to start cooling the mold 1. 34 is a molding machine.

According to the mold temperature controller 2 having the above configuration, the mold temperature of the mold 1, which is controlled to a constant temperature via the base temperature control source 5, is periodically changed between the upper limit setting value and the lower limit setting value. It can be adjusted up and down.
That is, when the temperature detected by the temperature sensor 12 in the mold 1 reaches the upper limit set value, the electromagnetic valve 23 is activated via the temperature controller 13 and the sequence control circuit section 14.
When the valve opens, the pump 22 starts, and the mold 1
Low-temperature oil 20 is supplied into the tank to start cooling.
At the same time, a signal is output to the molding machine 34 and injection is performed. Further, when the mold temperature of the mold 1 whose cooling has started reaches the lower limit set value, the temperature controller 13,
The electromagnetic valve 2 via the sequence control circuit section 14
When the valve 8 opens, the pump 27 starts, and high temperature oil 25 is supplied into the mold 1 to start heating. At the same time, a signal is output to the molding machine 34 to open the mold.

The detected temperatures of the insert temperature sensor 12 and the mold base temperature sensor 8 in the mold 1 are plotted with time on the horizontal axis;
A graph showing the molding process and plotting the mold temperature on the vertical axis is as shown in FIG. 6a. That is,
In the figure, 40 indicates a graph of the temperature detected by the nesting temperature sensor 12.
1 is a graph of the temperature detected by the mold base temperature sensor 8. The reason why the detected temperature of the mold base temperature sensor 8, which is controlled to a constant temperature via the base temperature control source 5, fluctuates slightly is because of the temperature control for periodically controlling the temperature of the insert 9. This is because the tube 11 passes through the mold base and is therefore affected by it.

[Problems to be solved by the invention] However, the above-mentioned prior art has the following problems.

That is, if there is variation in temperature distribution between the fixed mold part 3 and the movable mold part 4 of the mold 1 during injection, "warp" or internal stress is likely to occur in the molded product, so it is difficult to maintain stable quality. To obtain molded products,
It is desirable that there be no variation in temperature distribution between both mold parts during injection for each molding shot.

However, in the above-mentioned prior art, there was a major problem in that the temperature distribution varied between the two mold parts for the reason explained below, and therefore a molded product of stable quality could not be molded.
That is, in the above-mentioned conventional technology, when the temperature of the mold 1 reaches the lower limit set value after the start of cooling, cooling is simply switched to heating, and the cooling time is not managed at all. In this case, it is normal for the cooling time to vary somewhat depending on the performance of the cooling tank pump 22, the flow rate of the low-temperature oil 20, fluctuations in temperature, and the like. This time shift is shown enlarged in FIG. 6b. In the figure, Δt indicates the amount of time difference, and ΔT indicates the amount of shift between the time differences Δt.

During cooling, low-temperature oil 20 is passed through the temperature control pipe 11 of the fixed mold section 3, and this low-temperature oil 20 passes through the inside of the insert 9 and also through the mold base.
As shown in , the temperature detected by the mold base temperature sensor 8 also decreases to some extent. Also, while the insert 9 is being cooled, heat transfers from the insert 9 to the mold base, and from the mold base to the insert 9 (i.e., heat transfer between the insert 9 and the mold base). movement), the mold base temperature of the fixed mold part 3 decreases.

The amount of heat transfer between the insert 9 and the mold base is largely related to the cooling time, and the longer the cooling time, the greater the amount of heat transfer. In the conventional technology in which there is no control over the cooling time, as mentioned above, the cooling time varies, so the insert 9
The amount of heat transfer between the mold base and the mold base also fluctuates, resulting in variations in the mold base temperature at the start of heating. Here, let us consider the time difference Δt and the temperature deviation amount ΔT shown in FIG. 6b. As shown in FIG. 6a, when the temperature of the insert 9 reaches around the lower limit set value, the temperature difference between it and the low-temperature oil that is the heat medium decreases, so the temperature curve becomes gentle. Therefore,
As shown in FIG. 6b, even if a temperature difference of ΔT occurs due to a slight deviation in the temperature detection value or the temperature control of the medium oil, the time difference Δt becomes so long that it cannot be ignored. Furthermore, at the time when this time lag of Δt occurs, as shown in FIG. 6a, the slope of the temperature curve of the mold base is large, resulting in a large temperature change of the mold base.

Therefore, in the conventional technology that does not control the cooling time at all, variations in the cooling time occur,
Due to this variation in cooling time, the temperature variation in the fixed mold part 3 increases, and therefore, during injection, the temperature distribution inside the mold (temperature difference between the fixed mold part 3 and the movable mold part 4) ), which caused sink marks and internal distortion. In addition, this phenomenon has become an extremely serious problem because it is multiplied and magnified each time the molding shots are repeated.

The present invention was devised in view of the above-mentioned problems of the conventional technology. By eliminating variations in the cooling time, the present invention eliminates variations in the temperature distribution inside the mold from one molding shot to another during injection, resulting in stable quality molding. The purpose of the present invention is to provide a mold temperature controller that enables the submission of products.

[Means and effects for solving the problem] The present invention detects the temperature of the mold and starts cooling the mold in a mold temperature controller that heats and cools the mold within a predetermined temperature range. By equipping it with a sequence control circuit that outputs a signal to switch from cooling to heating and a mold opening permission signal at the same time the set time is completed.
This eliminates variations in the cooling time of the mold and eliminates variations in temperature distribution at the mold base caused by variations in the cooling time.

[Example] Hereinafter, one example of the present invention will be described in detail using the drawings. In addition, in the following explanation,
Only the configuration of the main parts of the present invention will be explained, and since the other configurations are the same as the configuration shown in FIG. 3, illustration and explanation thereof will be omitted.

FIG. 1 shows a cooling time setting device 50 for setting a cooling time to a constant time when cooling a mold (member designated by reference numeral 1 in FIG. 3). is installed in the sequence control circuit section 14 of the mold temperature controller 2 shown in FIG.

As shown in the figure, the cooling time setting device 50 is constituted by a timer circuit. That is, the cooling time setting device 50 includes a mold temperature upper limit relay 51 connected to a mold temperature upper limit output terminal of a temperature controller (component indicated by reference numeral 13 in FIG. 6), which is not shown; Holding relay (auxiliary relay) 52
, an output signal switching relay 53 that outputs a signal for switching from cooling to heating and a mold opening signal upon completion of the set time, a cooling time setting timer (cooling operation timer relay) 54, and a self-holding timer (auxiliary timer relay) 55. It is structured as follows. 56 indicates the a contact of the mold temperature upper limit relay 51;
7 and 57 indicate the a contacts of the output switching relay 53, 58a and 58b indicate the a and b contacts operated by the cooling time setting timer 54, and 59 and 60
1. Denoted by 61 are the a and b contacts of the output switching relay 53, and 61 is the changeover switch.

Next, the operation based on the above configuration will be explained.

When the mold is heated and the temperature detected by the temperature sensor in the mold reaches the upper limit setting, a signal to that effect is input to the temperature controller. Then, the mold temperature upper limit relay 51 of the cooling time setting device 50 is activated by a signal current from the temperature controller, and the cooling operation timer relay 54 is activated via the auxiliary relay 52. A predetermined cooling time for the mold is set in the cooling operation timer relay 54, and when this set time is completed, the auxiliary timer relay 55 is activated, the output signal switching relay 53 is activated, and the sequence control circuit ( A heating operation start signal and a mold opening permission signal are output to the component indicated by reference numeral 14 in FIG. At this time, the sequence control circuit section switches to the heating circuit, and even after the auxiliary timer relay times up and is reset,
The heating circuit is held until the mold temperature upper limit set value signal from the temperature controller is input. The auxiliary timer relay 55 is an auxiliary timer for preventing circuit malfunction. When the set time of the auxiliary timer relay 55 is completed, the auxiliary relay 52, the output signal switching relay 53, and the cooling operation timer relay 54 are reset, and the auxiliary timer is activated. Relay 55 also returns.

As described above, according to the configuration of this embodiment, when cooling the mold using the mold upper limit set value signal, the cooling operation signal is sent from the sequence control circuit only for the set time of the cooling operation timer relay 54. Since this is output, there is no variation in the mold cooling time from shot to shot, and it is possible to prevent variation in the mold temperature distribution from shot to shot before injection. As a result, there is no variation in the temperature distribution of the mold base from shot to shot upon completion of heating, and a molded product of stable quality can be obtained.

In addition, in the above structure, as shown in FIG. 2, a changeover switch 70 between the output from the timer circuit and the output from the temperature controller may be added.

According to the above configuration, by switching the changeover switch 70 to the timer circuit side, cooling of the mold can be time-controlled via the timer circuit of the first embodiment, and also by switching the changeover switch 70 to the temperature controller side. By switching from cooling to heating, the switching from cooling to heating can be controlled by the detected temperature of the mold. Therefore, by switching the changeover switch 70 to the temperature controller side, the switching from cooling to heating can be controlled from the start of cooling until the mold temperature reaches the lower limit target temperature. This is very convenient because it allows time to be measured and the optimum setting time for the cooling operation timer relay 54 to be easily determined.

[Effects of the invention] As described above, according to the invention, since the cooling time of the mold is managed and controlled, variations in the cooling time from shot to shot are eliminated, and variations in the temperature distribution at the mold base upon completion of cooling are reduced. disappears. the result,
This eliminates shot-to-shot variation in the temperature distribution of the mold base upon completion of heating, and has the effect of obtaining molded products of stable quality.

[Brief explanation of the drawing]

FIG. 1 is a sequence control circuit diagram showing one embodiment of the main part of the present invention, FIG. 2 is a sequence control circuit diagram showing another example of the configuration of FIG. 1, and FIG. Explanatory diagrams of the mold temperature controller, Figures 4a and b are
FIG. 5 is an explanatory diagram of the mold, FIG. 5 is an explanatory diagram of the sequence control circuit section in FIG. 3, and FIGS. 6a and 6b are graph diagrams for explaining the problems of the prior art. 1...Mold, 12...Temperature detection sensor, 51
... Mold temperature upper limit relay, 52 ... Auxiliary relay, 53 ... Output signal switching relay, 54 ...
Cooling operation timer relay, 55...Auxiliary timer relay.

Claims (1)

[Scope of claim for utility model registration] (1) In a mold temperature controller that detects the temperature of a mold and heats and cools the mold within a predetermined temperature range, A mold temperature controller characterized by being equipped with a sequence control circuit that performs cooling for a set time and outputs a signal to switch from cooling to heating and a mold opening permission signal at the same time as the set time is completed. (2) The sequence control circuit section is characterized in that it has a changeover switch between a circuit section that switches from cooling to heating based on the detected temperature of the mold and a circuit section that switches switching from cooling to heating based on the completion of the set time. A mold temperature controller according to claim 1 of the utility model registration claim.