JPH01156808A - Cooling system for metallic mold - Google Patents

Abstract

PURPOSE:To keep plural cooling objects at each proper temperature with use of a single cooling unit by switching the flow of brine to the bypass side in response to the detection signal received from a temperature sensor which detects the temperature of an object to be cooled. CONSTITUTION:When a cooling system is started, a cooling unit 10 and pumps P1-P3 are actuated so that the brine flows. The brine cooled by the unit 10 passes through the heat exchangers 11-13 respectively. Thus the objects of the metallic molds 1-3, etc., are cooled. When these objects reach the prescribed temperatures respectively, the flow of brine is switched to bypasses 31-33 by the switch means 21-23. Thus the brine finished temporarily its cooling jobs of those objects to be cooled circulates between bypasses 31-33 and the means 11-13 so that the cooling function is relaxed to the object to be cooled. Meanwhile the flow rate of the brine passing through the means 11-13 is kept approximately at a fixed level and only the heat exchange value is changed between the brine and the objects to be cooled down. Thus the control of temperature is carried out in the cooling system.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cooling system for molds, etc., and particularly to a cooling system for maintaining a plurality of molds for resin molding at a predetermined temperature.

[Prior art] Resin molding molds become hot during injection molding due to the heat of the molten resin, so they require cooling, and usually water or brine cooled by a cooling unit is introduced into the inside and outside of the mold. ing. Additionally, when there are multiple molds of this type, the appropriate temperature for each mold will differ depending on the resin material, etc., and in a system that supplies cold water to each mold from a single cooling unit, it is difficult to obtain the appropriate temperature for each mold. It becomes difficult.

For this reason, in the past, a flow rate adjustment valve was installed on the cold water inlet side of each mold to adjust the flow rate of cold water according to the mold temperature, or a cooling unit was connected to each mold to adjust the mold temperature individually. It's in control.

[Problems to be solved by the invention] However, in a cooling system using a flow rate regulating valve,
When the amount of cold water flowing through the mold decreases, the temperature difference between the cold water inlet side and the outlet side of the mold increases, resulting in non-uniform mold temperature. Furthermore, if a cooling unit is installed for each mold, temperature control becomes easier, but there is a drawback that costs increase.

The present invention has been made in view of the above circumstances, and its purpose is to be able to maintain each object to be cooled, such as a mold, at an appropriate temperature with one cooling unit, and to maintain the brine inlet and outlet of the object to be cooled. The object of the present invention is to provide a cooling system for molds, etc., which does not cause much temperature difference.

[Means for Solving the Problems] In order to achieve the above object, the cooling system for molds, etc. in the present invention includes heat exchange means attached to each of a plurality of objects to be cooled, such as molds, and each heat exchanger. a brine circuit connecting the means in parallel; a cooling unit for cooling the brine;
A pump that circulates brine to each heat exchange means through a brine circuit, a bypass connected from the brine outlet side to the brine inlet side of each heat exchange means, a temperature sensor that detects the temperature of the object to be cooled, and a temperature sensor that detects the temperature of the object to be cooled. and switching means for switching the flow of brine to the bypass side in response to the detection signal.

[Function] With these configurations, when the cooling system starts,
The cooling unit and the pump operate to cause brine to flow through the brine circuit, and the brine cooled by the cooling unit passes through each heat exchange means, thereby cooling objects to be cooled, such as molds.

Next, when the object to be cooled reaches a predetermined temperature, the switching means switches the brine flow to the bypass based on a detection signal from the temperature sensor. The brine that has once finished cooling the object to be cooled is circulated between the bypass and the heat exchange means, and the cooling effect on the object to be cooled is relaxed.

During this time, the flow rate of brine passing through each heat exchange means is almost constant, and temperature control is performed by changing only the amount of heat exchange between the brine and the object to be cooled. When the temperature of the objects to be cooled rises above the appropriate value while the brine is circulating through the bypass, the switching means again switches the flow of brine to the main brine circuit, and low temperature brine is introduced to each object to be cooled.

[Example] FIG. 1 shows a circuit diagram of a mold cooling system to which the present invention is applied, and this system includes a cooling unit 1.
0, brine circuit 20, expansion tank 30, brine tank 40, pump PI, P2゜P3, heat exchange vibe 11,
12.13, three-way valve 21.22.23, bypass 31,
32, 33, temperature sensor Sl, S2. S3 and heater H
It is composed of 1, H2°H3.

The cooling unit 10 sequentially cools brine such as water flowing through the brine circuit 20, and has an expansion tank 30 connected to its inlet side and a brine tank 40 connected to its outlet side. The expansion tank 30 absorbs the amount of brine that expands and contracts depending on the temperature, and the brine tank 40 temporarily stores the brine.

The heat exchange pipes 11, 12, and 13 are connected to the mold 1 which is the object to be cooled.
, 2.3, and are connected to the brine circuit 20 in parallel. Each heat exchange vibrator 11', 12.1
On the inlet side of 3, there is a check valve 41゜42.43 and a pump PL.
, P2. P3 is connected so that the cooled brine flows in the direction of the solid arrow.

The molds 1, 2.3 are provided with temperature sensors 81.3 for detecting their temperatures. S2. S3 is installed, temperature sensors Sl, S
2. S3 can be set individually depending on the appropriate temperature of the molds 1, 2, and 3.

The appropriate temperature of the mold 1.2.3 is determined by the molten resin material used for molding.

A three-way valve 21.22.23 is installed on the outlet side of each heat exchange pipe 11.12.13.
from pump Pi, P2. Bypass 31 on the inlet side of P3,
32.33 are connected.

The three-way valves 21, 22, and 23 allow the brine flow to bypass 31, 22, and 33 as indicated by dotted arrows depending on the mold temperature.
Switch to the side.

In the bypasses 31, 32 and 33, there are heaters H1 and H, respectively.
2 and H3 are arranged, and when the molds 1, 2.3 do not reach the appropriate temperature as at the time of startup, when the heaters H1, H2, and H3 are activated, each mold 1, 2.3 is warmed up in a short time. Ru.

The cooling system of this embodiment configured as described above operates as follows.

First, the appropriate temperature for each mold 1.2.3 is determined according to the molding resin material, and each temperature sensor Sl, S2. Set S3 to this value. When the cooling system is started here, the cooling unit 10 and pumps P1, P2. P3 is activated and brine flows in the direction of the solid line arrow in FIG.

At this time, if the mold 1.2.3 is cold and has not reached the appropriate temperature for resin molding, the temperature sensor S1. The three-way valves 21, 22 and 23 are opened by the detection signals S2 and S3, and the heaters H1, H2, H3 are energized, and the brine is diverted to the bypass 3.
It flows to the 1, 32, and 33 side. Therefore, while the brine is heated by the heaters H1, H2°H3, the bypass 31.32
．． 33 and the heat exchange pipes 11.12.13 in the direction of the dotted arrow, and the mold 1.2.3 is warmed up in a short time. The flow rate relationship between the main brine circuit 20 and the brine flowing through the bypass 31, 32, 33 is
A comparison is shown in the figure, where the horizontal axis is time and the vertical axis is brine flow rate.

Next, when the molds 1, 2.3 reach the appropriate temperature, the temperature sensors Sl, S2. The detection signal from S3 causes the three-way valves 31, 32 .
33 is switched to the main brine circuit 20, and the heaters H1, 2. H3 is stopped. Therefore, the brine cooled by the cooling unit 10 is stored in the brine tank 30.
, check valve 41°42.43, pump P1. P2. P3,
Heat exchange pipes 11, 12.13, three-way valves 21, 22.2
3 and returns to the cooling unit 10 through the mold 1
．． Step 2.3 continues while resin molding is being performed.

Next, when the mold temperature drops to an appropriate value by cooling the brine, temperature sensors Sl, S2. The detection signal from S3 operates the three-way valves 21, 22.23, and the flow of brine is switched to the bypass 31, 32.33 side. Now, the brine that has finished cooling the mold once circulates between the bypass 31, 32.33 and the heat exchange pipe 11.12.13, and the mold 1
, 2°3 cooling effect is suppressed.

Therefore, in this mold temperature control, only the amount of heat exchange between the molds 1, 2, 3 and the brine changes, and the heat exchange pipes 11, 12
．． As can be seen from FIG. 2, the flow rate of brine flowing through 13 is constant. As a result, compared to the conventional system that reduces the brine flow rate, in the case of this embodiment, the mold 1
, 2.3, the temperature difference between the inlet side and the outlet side becomes smaller, and the non-uniformity of temperature distribution is improved.

When the mold temperature returns to the proper value, the three-way valves 21, 22, 23 close the bypass 31, 32, 33 side, and the brine again flows through the original brine circuit 20 in the direction of the solid line arrow.

In addition, in the above-mentioned embodiment, each temperature sensor Sl, S2.83
Although the operations of the three-way valves 21, 22, and 23 are explained collectively, the melting material of each mold 1.2.3 is different, and the temperature sensor S1. S2. If the set values of S3 are also different, the three-way valves 21, 22, 23 are activated individually.

[Effects of the Invention] As detailed above, the cooling system for molds, etc. of the present invention connects the heat exchange means in parallel with the heat exchange means attached to each of a plurality of objects to be cooled, such as molds. A brine circuit, one cooling unit that cools the brine, a pump that circulates the brine to each heat exchange means through the brine circuit, a bypass connected from the brine outlet side to the brine inlet side of each heat exchange means, and a It consists of a temperature sensor that detects the temperature of the cooled object and a switching means that switches the brine flow to the bypass side in response to the detection signal from the temperature sensor, so it is possible to handle each cooled object with one cooling unit. Can be maintained at an appropriate temperature.

In addition, during temperature control, only the amount of heat exchange between the brine and the object to be cooled changes, but the flow rate is constant, so the temperature difference between the brine inlet and outlet sides of the object to be cooled is small, resulting in uneven temperature of the object to be cooled. It has the effect of improving

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a mold cooling system to which the present invention is applied, and FIG. 2 is a graph comparing the flow rates of brine flowing through the main brine circuit and the bypass. 1.2.3... Mold, 10... Cooling unit, 11
．． 12.13...Heat exchange vibrator, 21,22゜23・
...Three-way valve, 31.32.33...Bypass, Pi,
P2. P3...Pump, Sl, S2. S3. -・Temperature sensor. Patent applicant Sanden Co., Ltd. agent
Patent Attorney Yoshi 1) Sei Takashi o. t1r” 'X78 votes m; Written amendment to system procedure (voluntary) February 2, 1986

Claims (3)

[Claims] (1) Heat exchange means attached to multiple objects to be cooled such as molds, a brine circuit that connects each heat exchange means in parallel, one cooling unit that cools the brine, and A pump that circulates brine through the heat exchange means, a bypass connected from the brine outlet side to the brine inlet side of each heat exchange means, a temperature sensor that detects the temperature of the object to be cooled, and a detection signal from the temperature sensor. A cooling system for molds, etc., consisting of switching means for switching the flow of brine to the bypass side according to the requirements. (2) Claim No. (2) wherein the switching means is a three-way valve.
Cooling system for molds, etc. described in item 1). (3) The cooling system for molds and the like according to claim (1), wherein the bypass is provided with a heater.