JPH056490B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a mold temperature controller used to keep the temperature of a mold constant during plastic molding processing and to stabilize molding conditions and quality of molded products. It is related to.

[Prior art and its problems] Recently, plastic molding using a mold has become popular, and the mold temperature during molding has a very large effect on the quality of the molded product and the molding efficiency. Therefore, it is extremely important that the mold is well-adjusted to the predetermined temperature.

For this reason, a mold temperature controller is used that can adjust the mold temperature by forcibly circulating a liquid adjusted to an appropriate temperature through cooling holes in the mold.

As shown in Fig. 4, the structure of this mold temperature controller consists of a heat medium circulation pump 1 and an electric wire heater 2 that heats the circulating liquid. As shown in the direction, it is configured to circulate in the order from the pump 1 to the heater 2, from the heater 2 to the mold 4, and from the mold 4 to the pump 1.
An inflow pipe 5 for supplying cooling liquid and a discharge pipe 6 for circulating liquid are connected to the pipe 3a between the mold 4 and the pump 1, and the inflow pipe 5 is arranged on the side closer to the pump 1. There is.

When the mold temperature is set to X°C using such a mold temperature controller, the temperature of the lubricating liquid is not constant on the X°C line, but fluctuates up and down, creating a wave shape, as shown in Figure 5. becomes.

This is done by heating the circulating liquid passing through the piping 3 with the heater 2 or by supplying cooling liquid from the inflow pipe 5, thereby adjusting the temperature of the circulating liquid and keeping the mold temperature constant. This is because they are doing so.

That is, when the temperature controller 7 provided in the pipe 3b between the heater 2 and the mold 4 senses the liquid temperature X°C, the heater 2 is turned off, but at this time, the heater 2 is in an overshot state as shown in the figure. When the liquid temperature exceeds a predetermined temperature of X°C, cooling liquid is supplied into the pipe 3 from the inflow pipe 5 to lower the liquid temperature, and the temperature controller 7 senses the temperature at X°C, and the supply of cooling liquid is stopped. It will be done. Then, the temperature of the circulating liquid falls below the X°C line, and the temperature controller 7 senses this and turns on the heater 2. By repeating this process, the liquid temperature fluctuates as shown in a wave-shaped curve as shown in FIG.

In addition, when lowering the set temperature from the mold temperature set at X°C to Y°C, as shown in Figure 6, it drops rapidly from the X°C line and fluctuates with a considerable amplitude at the Y°C line. It becomes a wavy curve similar to the above-mentioned X°C line.

This is because the cooling liquid is sucked into the pipe 3 from the inflow pipe 5 when the liquid temperature is approximately X°C, and at this time, there is a large temperature difference between the cooling liquid and the circulating liquid.
When the temperature of the liquid in the tank suddenly drops and the temperature controller 7 detects a liquid temperature of Y° C., the supply of cooling liquid is stopped, but as shown in the figure, the state is considerably overshot.
In this way, when the liquid temperature approaches Y°C, the amplitude is quite large, and as described above, the circulating liquid in the pipe 3 is heated by the heater 2, or the cooling liquid is supplied from the inflow pipe 5. By doing so, a wavy curve similar to the above-mentioned X°C line is obtained.

The purpose of the present invention is to reduce fluctuations in mold temperature, that is, to reduce the amplitude of the temperature shown in the drawings and to bring it as close to the set temperature straight line as possible. Another purpose is to lower the temperature of the circulating liquid discharged from the pipes of this mold temperature controller. This is because when supplying cooling liquid from the inflow pipe 5 to lower the temperature of the liquid in the pipe 3, it is necessary to supply circulating liquid from the pipe 3 by the amount that has been supplied, and this circulating liquid has a considerably high temperature. Therefore, it is dangerous to discharge the circulating liquid as it is, and there are also disadvantages such as having an adverse effect on the cooling liquid system machines.For this reason, it is preferable to lower the temperature of the circulating liquid before discharging it.

[Means for Solving the Problems] The present invention provides a mold temperature controller configured such that a circulating liquid circulates in piping in the order from the pump to the heater, from the heater to the mold, and from the mold to the pump. An inflow pipe for cooling liquid and a discharge pipe for circulating liquid are connected to the pipe between the mold and the pump, the inflow pipe is arranged on the side closer to the pump, and the inflow pipe and the discharge pipe are connected to a heat exchanger, respectively. By arranging it so that it passes through the inside, the above problem is solved.

[Function] In the mold temperature controller according to the present invention, the inflow pipe and the discharge pipe are arranged so as to pass through the inside of the heat exchanger, so that the cooling liquid is circulated within the heat exchanger to be discharged. The circulating liquid is heated by the heat of the cooling liquid, approaches the temperature of the circulating liquid, and is supplied, and conversely, the circulating liquid that is discharged is cooled by the cooling liquid, and is discharged after being lowered to a temperature close to that of the cooling liquid. The temperature difference becomes smaller.

[Example] An example of the present invention will be described below based on FIGS. 1 to 3.

In this mold temperature controller 10, a liquid circulates in a pipe 12 from a pump 14 to a heater 16, from the heater 16 to a mold 18, as shown in the arrow direction in FIG.
It is configured to circulate in the order from the mold 18 to the pump 14, and a pipe 12a between the mold and the pump,
The cooling liquid inflow pipe 20 and the circulating liquid discharge pipe 22 are connected, and the inflow pipe 20 is connected to the side near the pump 14.
The inflow pipe 20 and the discharge pipe 22 are arranged so as to pass through the inside of the heat exchanger 24, respectively.

To explain how this mold temperature controller 10 is used, when the mold temperature is set at X°C, when the temperature controller 26 installed in the pipe 12b between the heater and the mold detects the liquid temperature X°C, the heater 16 is cut off, and at this time, an overshot state occurs as shown in FIG.

When the liquid temperature slightly exceeds X°C, cooling liquid is supplied into the pipe 12 from the inflow pipe 20 passing through the heat exchanger 24 to lower the liquid temperature, and the temperature controller 26 detects X°C and cools the liquid. Liquid supply is stopped. At this time,
It is necessary to discharge the circulating liquid in the piping 12 by the amount of cooling liquid put into the piping 12, and the circulating liquid in the piping 12 discharged from the discharge pipe 22 passes through the heat exchanger 24 to adjust the mold temperature. It is discharged to the outside of the machine 10.

In this heat exchanger 24, the cooling liquid and the circulating liquid to be discharged communicate with each other, so that the cooling liquid is heated by the heat of the circulating liquid to be discharged, and conversely, the circulating liquid to be discharged is cooled by the cooling liquid, and the circulating liquid to be discharged is cooled. The temperature difference between the liquid and the circulating liquid in the pipe 12 is reduced, and the temperature of the circulating liquid to be discharged is lowered.

Then, the temperature of the circulating liquid falls below the X°C line, and the temperature controller 26 senses this, and the heater 16
Put in. By repeating this process, the temperature of the mold 18 is adjusted. In this case, since the temperature difference between the cooling liquid and the circulating liquid in the pipe 12 is small due to the heat exchanger 24, the liquid temperature fluctuates as shown in the gentle wave-shaped curve as shown in FIG. , the amplitude is small, and the temperature of the mold 18 can be suitably controlled.

Next, when lowering the set temperature from the mold temperature set at X°C to Y°C, a considerable amount of cooling liquid is supplied from the inlet pipe 20 into the pipe 12 where the liquid temperature is approximately X°C. Then, the temperature of the liquid in the pipe 12 is lowered, and when the temperature controller 26 senses the liquid temperature Y°C, the supply of cooling liquid is stopped. At this time, as shown in FIG. 3, the temperature drops from the X°C line to the Y°C line, resulting in a slight overshoot state. Then, it becomes a gentle wavy curve similar to the above-mentioned X°C line.

In this way, the overshot state is small, the amplitude is small, and the waveform curve is gentle because the cooling liquid and the circulating liquid to be discharged are connected to the heat exchanger 24.
This is because the temperature difference between the cooling liquid and the circulating liquid in the pipe 12 is reduced by heat exchange within the pipe 12.

The most suitable circulating liquid is water, which is ubiquitous and easy to manage.
Heating above ℃ will cause cavitation,
The pump 14 runs idly, which adversely affects the pump 14. In particular, when the specifications of the mold temperature controller 10 of the present invention are such that the mold temperature can be set above 100°C using water, the inside of the pipe 12 is pressurized to prevent cavitation. It is necessary to For this reason, as shown in FIG.
is installed to control the pressure inside the pipe 12.

A valve 32 is attached to the discharge pipe 22,
At the same time as the circulating liquid is discharged, the amount of cooling liquid that has been discharged is sucked in from the inlet pipe 20. Furthermore, piping 1 between the mold and the pump
A bypass pipe 36 having a relief valve 34 is attached to the pipe 12b between the heater and the mold 2a, so that when the flow rate of the circulating liquid in the mold 18 becomes slow, the pressure on the discharge side of the pump 14 becomes high. This has an adverse effect on the pump 14, so the relief valve 34 is opened to allow the circulating liquid to circulate without passing through the mold 18.

Note that the pump 14, heater 16, and heat exchanger 24 are not particularly limited in type or size, and any convenient ones may be used.

[Effects of the Invention] As is clear from the above description, the mold temperature controller according to the present invention has a circulation system in which the inflow pipe and the discharge pipe each pass through a heat exchanger, and the cooling liquid is discharged inside the heat exchanger. The circulating liquid that is heated by the heat of the liquid and conversely discharged is cooled by the cooling liquid, so that the temperature difference between the cooling liquid and the circulating liquid becomes smaller. As shown in FIG. 3, the liquid temperature has a gentle waveform curve with a small amplitude, and the amplitude in an overshot state is also small.

Therefore, fluctuations in mold temperature are small, the temperature of the circulating liquid discharged from the mold temperature controller can be lowered, and the mold temperature can be suitably controlled.

In this way, the mold can be sufficiently adjusted to a predetermined temperature, so that the quality of the molded product and the molding efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of the mold temperature controller according to the present invention, and FIG. 2 is a diagram showing the circulating liquid in the mold temperature controller according to the present invention with the mold temperature set at X°C. A graph showing temperature changes. Figure 3 is a graph similar to the previous figure when the mold temperature has been lowered from X°C to Y°C. Figure 4 is a schematic diagram showing the configuration of a conventional mold temperature controller. , Fig. 5 is a graph showing the temperature change of the circulating liquid in a conventional mold temperature controller when the mold temperature is set to
This is a graph similar to the previous figure when the temperature was lowered from 0 to Y°C. Explanation of symbols, 10... Mold temperature controller, 12...
...Piping, 12a...Piping between the mold and the pump, 1
2b... Piping between the heater and the mold, 14... Pump, 16... Heater, 18... Mold, 20... Inflow pipe, 22... Outlet pipe, 24... Heat exchanger, 26
... Temperature controller, 28 ... Pressure detector, 32 ... Valve, 34 ... Relief valve, 36 ... Bypass pipe.

Claims (1)

[Claims] 1 In a mold temperature controller configured so that a circulating liquid circulates in the piping in the order of pump to heater, heater to mold, and mold to pump, cooling liquid is supplied to the piping between the mold and the pump. An inflow pipe and a discharge pipe for the circulating liquid are connected, the inflow pipe is arranged on the side closer to the pump, and the inflow pipe and the discharge pipe are respectively arranged to pass inside the heat exchanger. mold temperature controller.