JP2010162845A - Injection-molding mold, temperature regulating unit, and injection-molding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection-molding mold, a temperature regulating unit and an injection-molding method by which a period of time required for the heating and cooling of the mold during the injection-molding cycle can be shortened, and the consumption energy can be saved. <P>SOLUTION: This injection-molding mold includes this temperature regulating unit 10 which is installed in response to a molding defective place. The temperature regulating unit 10 includes: an electric heating heater 11 which is installed in parallel with the mold surface in a vicinity of mold the surface; and a cooling circuit 12 which is installed in parallel with the mold surface and the electric heating heater 11 at a location farther than the electric heating heater 11 to the mold surface. The electric heating heater 11 and the cooling circuit 12 constitute the injection-molding mold wherein the surface of the electric heating heater 11 and the surface of the cooling circuit 12 are formed in a manner to be alternately face the mold surface. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an injection mold, a temperature control unit, and an injection molding method, and more particularly to an injection mold and an injection molding method capable of controlling the mold temperature and shortening the injection molding cycle time.

  Generally, in an injection molding machine that molds plastic products that require high quality, a series of cycles of heating the mold, injecting and holding the molding material, molding, cooling the mold, and taking out the molded product are repeated. Is going.

  In such a molding system, since temperature control becomes important for molding a high-quality product, there are a process for heating the mold and a process for cooling the mold.

In general, there are two reasons for heating a mold in such a molding system. One reason is to improve the fluidity of the resin used as the molded product and to finish the transfer of the mold surface to a mirror finish. Another reason is that the flow marks generated at positions A1 to A4 in FIG. This is to suppress molding defects such as weld lines that occur at positions B1 to B4.

  A medium such as a fluid or energy such as electricity is used as a means for heating the mold, and a medium such as a fluid for removing heat from the mold is used as a means for cooling.

  For example, in Patent Document 1, a circuit for passing a heating medium and a cooling medium is provided at a position close to the mold surface, and further, a cooling circuit is provided at a position farther from the mold surface than a circuit for passing the heating medium and the cooling medium. An injection mold having a circuit through which a medium passes is disclosed.

  Further, for example, Patent Document 2 proposes a method of increasing mold surface temperature with an electric heater to eliminate molding defects such as weld lines and flow marks.

  However, as described in Patent Document 1, for example, when two or more kinds of fluids are used while being switched in the same circuit, there is a problem that the circuit is easily corroded or contaminated and easily clogged.

In addition, complicated piping equipment and a fluid switching device using valves are required, and high-temperature and high-pressure fluids are often used for heating, and handling is complicated, and installation is troublesome for ensuring safety. It was.

  Further, for example, the method described in Patent Document 2 has a problem that excessive heat is accumulated in the mold and the heater, and cooling takes time.

Japanese Patent Laid-Open No. 11-348041 JP 51-22759

  As mentioned above, there are two reasons for heating the mold, but the temperature to improve the first fluidity and finish the transfer to a mirror finish and the temperature to suppress the second molding failure are as follows. Unlike usual, the temperature for suppressing molding defects is higher.

However, in order to obtain both effects, the entire mold has been heated to a temperature at which molding defects can be suppressed. In particular, in injection molding of a relatively large product, there are a plurality of locations where molding defects occur, and if heating is continued until each location reaches a desired temperature, an overheated location is created, and the cooling time becomes longer.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to shorten the time required for heating and cooling the mold during the injection molding cycle and to save energy consumption. Another object of the present invention is to provide a new and improved injection mold and injection molding method.

  In order to solve the above problems, according to one aspect of the present invention, a temperature control unit is provided in accordance with a molding defect location, and the temperature control unit is in the vicinity of the mold surface and in parallel with the mold surface. An electric heater installed; and a cooling circuit installed in parallel to the mold surface and the electric heater at a position farther than the electric heater with respect to the mold surface, the electric heater and the cooling circuit Is provided with an injection mold in which the surface of the electric heater and the surface of the cooling circuit are alternately opposed to the surface of the mold.

  With this configuration, the temperature control unit is arranged according to a molding defect location, so that only the location where the molding defect occurs can be efficiently adjusted in temperature.

  In addition, since the mold surface alternately has a surface facing the cooling circuit and a surface facing the electric heater, the electric heater does not block the cooling effect from the cooling circuit on the mold. The temperature control on the mold surface can be performed efficiently.

  Further, for example, the electric heater and the cooling circuit may be installed so as to repeat a shape alternately arranged at the apex of the W shape in a cross section perpendicular to the mold surface.

  Such an arrangement is an example of a configuration in which the above-described mold surface alternately has a surface facing the electric heater and a surface facing the cooling circuit, and can transmit heat to the mold surface efficiently. If there is, it is not restricted to the above.

Further, the injection mold may further include a heat retention circuit installed at a place other than the temperature control unit arrangement portion.

  With this configuration, it is possible to maintain a temperature at which the surface of the molded product can be mirror-finished at a portion other than a molding defect location, and a constant temperature at which the resin can be solidified and taken out from the mold. Stable molding can be performed.

  The injection mold may be one in which the cooling circuit is disposed at the left and right ends of the temperature control unit among the electric heater and the cooling circuit.

  With such a configuration, there is an effect that heat of the temperature control unit can be reduced from being transmitted to other portions when the temperature control unit installation portion is heated.

  The injection mold may further include a heat insulating layer installed at the boundary between the temperature control unit and other portions.

  With this configuration, it is possible to more effectively prevent the heat of the temperature control unit from being conducted to other portions when the temperature control unit installation portion is heated as described above.

  The heat insulating layer may be realized by providing a space, or may be realized by embedding a material having a heat insulating effect.

  The temperature control unit may further include a temperature sensor for measuring the mold surface temperature.

  With this configuration, the temperature near the mold surface of the temperature control unit can be measured. Thus, accurate temperature control can be performed by controlling the ON / OFF timing of the electric heater in the temperature control unit.

  In order to solve the above problems, according to another aspect of the present invention, an electric heater installed in parallel to the mold surface in the vicinity of the mold surface, and the mold surface is more A cooling circuit installed in parallel with the surface of the mold and the electric heater at a distant position; the electric heater and the cooling circuit have the surface of the electric heater and the surface of the cooling circuit alternately There is provided a temperature control unit that is formed so as to face the mold surface and is used for the injection mold according to the location where a molding defect occurs in the injection mold.

In order to solve the above-mentioned problems, according to another aspect of the present invention, an injection molding apparatus comprising a cooling circuit, an electric heater, and a temperature sensor, and a temperature control unit that is installed at a molding defect location and controls temperature. An injection molding method using a metal mold, wherein a step of constantly passing a refrigerant through a cooling circuit, a step of energizing an electric heater, and an electric heater when the temperature of the temperature sensor exceeds a first threshold value A step of stopping energization, a step of energizing the electric heater when the temperature of the temperature sensor is equal to or lower than a second threshold, and a power source of the electric heater when all of the temperature sensor values are equal to or higher than a predetermined temperature. And an injection molding method including a step of starting resin injection.

  As described above, according to the present invention, a new and improved injection mold, temperature control, which can shorten the time required for heating and cooling the mold during the injection molding cycle and can save energy consumption. Units and injection molding methods can be provided.

1 is an overall view of an injection molding apparatus using an injection mold according to an embodiment of the present invention. It is 1-1 sectional drawing to which a part of injection die of FIG. 1 was expanded. It is 2-2 sectional drawing of the metal mold | die for injection molding of FIG. FIG. 3 is a 3-3 cross-sectional view of the injection mold of FIG. 2. It is a flowchart which shows the injection molding method using the metal mold | die for injection molding which concerns on the same embodiment. It is explanatory drawing explaining the timing of the injection molding method of FIG. It is explanatory drawing which shows the temperature change of a temperature sensor in the injection molding method of FIG. It is explanatory drawing which shows the change of a fluid flow rate in the injection molding method of FIG. It is explanatory drawing which shows the problem of the molding defect in the conventional injection mold.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the present specification and drawings, components having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

The description will be given in the following order.
1. Injection molding and molding defects (conventional example)
2. 2. Overall configuration of an injection molding apparatus using an injection mold according to an embodiment of the present invention. 3. Configuration of injection mold according to the embodiment Injection molding method using injection mold according to the embodiment

<1. About injection molding and molding defects (conventional example)>
First, molding defects in conventional injection molding will be described with reference to FIG. FIG. 9 is an explanatory view showing a problem of molding failure in a conventional injection mold.

  Conventionally, injection molding has been widely used as a method of molding a resin such as plastic. Injection molding repeats a series of cycles in which the resin is heated to a fluid level, poured into a mold, cooled, and taken out after the molded product has solidified.

  Among these, the weld line and the flow mark, which are molding defects that appear when the resin is poured into the mold and cooled, will be described with reference to FIG.

  For example, when injection molding is performed using a mold as shown in FIG. 9, the resin is injected from the injection device 200 through the injection port 710 of the mold 700. Gates 721 to 724 are provided in the mold 700, and the resin injected from the injection port 710 flows toward the gates 721 to 724.

  The resin flowing in from the gates 721 to 724 flows in different directions along the flow path in the mold at locations A1 to A4, and the resin flowing from A1 and the resin flowing from A2 merge at the location B1. Similarly, the resin flowing in from the two paths joins at B2 to B4.

  When the resin is poured through such a path, the flow pattern of the resin generated at locations A1 to A4 is a flow mark. It is often an annual ring-shaped striped pattern centering on the gate.

  Moreover, the line which generate | occur | produces in the location where resin joins like B1-B4 is a weld line. The point at which the resin joins is because the temperature of the resin drops before reaching the point because it is away from the gate, and the joined resins do not completely fuse together.

  The flow mark deteriorates the surface quality, and the weld line not only deteriorates the surface quality but also becomes a discontinuous portion of the resin, leading to a decrease in strength of the molded product. Therefore, it is important to suppress these molding defects in order to maintain the quality of the molded product.

  Both the flow mark and the weld line are likely to occur when the resin viscosity increases due to a decrease in the resin temperature, and can be suppressed by increasing the resin temperature.

However, especially in the case of a thermoplastic resin, the molecular chain starts to decompose when a predetermined temperature is exceeded. Therefore, it is important to adjust the temperature so that it is higher than the temperature at which molding defects can be suppressed and lower than the molecular chain decomposition temperature.

  As described above, in injection molding, it is important to control the state of the resin by controlling the temperature of the mold in order to obtain a high-quality molded product. In general, the relationship between temperatures for resin molding is as follows.

(Temperature required to finish the surface of the resin in a mirror state) <(Temperature required for suppressing molding defects) <(Resin molecular chain decomposition temperature)

  At the time of designing the mold, it is possible to predict to some extent where molding defects occur in the mold. Therefore, it is possible to control to keep only the part where molding defects occur above the temperature necessary for suppressing molding defects, and keep the other parts at the temperature necessary to finish the surface of the molded product into a mirror surface. is there.

As described above, when the temperature is controlled to be optimum at each location, it is possible to shorten the time required for heating and cooling in the injection molding cycle.

An injection mold according to an embodiment of the present invention is such that the temperature control is separately performed at a molding defect occurrence location and other locations, and optimal temperature control is realized at each location and each timing. .

<2. Overall Configuration Example of Injection Molding Apparatus Using Injection Molding Mold According to One Embodiment of the Present Invention>
Next, an example of the entire configuration of the injection molding apparatus according to the present embodiment will be described with reference to FIG. FIG. 1 is an explanatory diagram showing the overall configuration of an injection molding apparatus according to the present embodiment.

  The injection molding apparatus according to the present embodiment includes a mold 100, an injection apparatus 200, a flow medium apparatus 300, and a controller 400.

  The mold 100 is a mold having a cavity for forming a molded product therein. A molded product is formed by injecting resin into the cavity from the injection device 200 and solidifying the resin while adjusting the temperature.

  In the present embodiment, the mold 100 includes the temperature control unit 10, the heat retaining circuit 20, and the heat insulating layer 30. Since the detailed structure of the mold will be described later, it is omitted here.

  The injection device 200 is a device that injects and pressurizes resin into a mold. The injection device 200 is connected to a cavity portion in the mold 100 and injects resin into the cavity in the mold 100. Thereafter, the injection device 200 pressurizes the resin in order to reliably fill the mold.

In the present embodiment, the injection device 200 has a function of injecting resin into the mold 100 in response to a timing instruction from the controller 400 and starting pressurization when the injection is completed.

  The flow medium device 300 is a device for passing a flow medium for cooling and heating through a flow path in the mold. In the present embodiment, the flow medium device 300 has flow rates of temperatures set in the heat retaining circuit 20 and the cooling circuit 12 (not shown in FIG. 1 and described in FIG. 2) installed in the mold 100, respectively. Pass the medium.

  The flow medium device 300 is connected to the controller 400 so as to receive a control instruction from the controller 400.

  In the present embodiment, the flow medium device 300 is of an integral control type in which the flow medium is passed through both the heat retaining circuit 20 and the cooling circuit 12, but is not limited thereto. For example, another fluid medium device may be used for the heat retaining circuit 20 and the cooling circuit 12.

By using a separate configuration, for example, in the case of a usage mode in which the cooling medium and the temperature control medium are always flown at the same flow without controlling the flow rates of the cooling medium and the temperature control medium, an inexpensive device that can control only the temperature should be used. Is preferable. In this case, the flow medium device 300 does not need to be connected to the controller 400 and perform timing control as shown in FIG.

  The controller 400 is a device that controls the entire injection molding apparatus. In the present embodiment, an interface connected to the temperature sensor 13, the electric heater 11, the injection device 200, and the flow medium device 300 installed in the mold 100, ROM, RAM, and CPU are included.

The controller 400 determines the timing of each process of injection molding based on the value of the temperature sensor 13 or a preset timer, and controls the entire injection molding apparatus.

  Specifically, in the present embodiment, the controller 400 instructs the injection device 200 about the timing of injection or pressurization, or instructs the flow medium device 300 to pass the flow medium. Further, when controlling the flow rate of the flow medium, the timing for changing the flow rate may be instructed.

The controller 400 controls ON / OFF of the electric heater 11 (not shown in FIG. 1 and described in FIG. 2) in the temperature control unit 10 of the mold 100.

  As described above, the temperature control unit 10 has a function of heating the location where molding failure occurs to a temperature at which molding failure can be suppressed at the time of resin injection and cooling after injection, and the heat retaining circuit is used to finish the surface of the molded product to a mirror finish. Has the function of maintaining the temperature at which the resin cures above the temperature.

  The heat retaining circuit 20 may be omitted if it is not necessary depending on the type of resin, the temperature control condition, etc. (when the necessary temperature can be maintained without the heat retaining circuit).

<3. Configuration of injection mold according to the embodiment>
Next, the configuration of the injection mold according to the present embodiment will be described with reference to FIGS. 2 is a cross-sectional view taken along the line 1-1 of FIG. 1 and FIG. 3 is a cross-sectional view taken along the line 2-2 in FIG. FIG.

  The injection mold 100 according to the present embodiment mainly includes a temperature control unit 10, a heat retaining circuit 20, and a heat insulating layer 30.

  The temperature control unit 10 is a unit that is installed at a location where molding defects occur in the mold 100 and adjusts the temperature of the mold. The temperature control unit 10 has a rectangular shape, and has a shape in which concave portions are provided on both side walls in close contact with the mold body.

  The temperature control unit 10 may be manufactured as a separate member from the mold body as shown in FIG. 2 and may be joined to the mold body or may be manufactured by being fitted into the mold body. The temperature control unit 10 mainly includes an electric heater 11, a cooling circuit 12, and a temperature sensor 13.

  The electric heater 11 is an apparatus for heating a molding defect location. The electric heater 11 has a structure having a plurality of rod-shaped portions, and a plurality of rod-shaped portions are arranged in parallel at a position close to the mold surface at a plurality of intervals.

The electric heater 11 is controlled by the controller 400 so as to reach a desired temperature during resin injection while repeating ON / OFF switching. Switching on / off of the electric heater 11 is realized by switching between energization and deenergization.

  Compared with the case where a conventional heating medium is passed through the circuit, the heating using the electric heater 11 is preferable because the temperature control response is good. This is because ON / OFF can be easily switched by switching between energization and deenergization under the control of the controller 400.

  Further, for example, even when a plurality of electric heaters 11 are installed in a mold for processing a relatively large molded product, the plurality of electric heaters 11 are simultaneously ON / OFF-controlled, or each electric heater 11 is desired. ON / OFF control can be performed at timing.

  The cooling circuit 12 is a device for cooling a molding defect portion. The cooling circuit 12 has a structure branched into a plurality of tubular members, and a plurality of tubular portions are arranged side by side at a position farther from the mold surface than the electric heater 11, and a refrigerant is always flowed. After the electric heater 11 is turned off, the mold surface is cooled.

  The arrangement of the cooling circuit 12 and the electric heater 11 is such that the electric heater efficiently heats the mold surface until the resin is injected, and the cooling circuit is effective after the electric heater 11 is stopped after the resin is injected. It is devised so that the mold surface can be cooled. Specifically, the mold surface alternately has a surface facing the electric heater 11 and a surface facing the cooling circuit 12. With this configuration, the electric heater 11 can efficiently conduct heat without interrupting the cooling effect from the cooling circuit 12.

  For example, the electric heater 11 and the cooling circuit 12 are installed substantially parallel to each other as described above. Then, when the cross section perpendicular to the mold surface is viewed, the electric heater 11 and the cooling circuit 12 are alternately arranged at the apex of the W shape so as to be repeated.

  Moreover, it is desirable that the cooling circuit 12 is disposed at the left and right ends of the temperature control unit 10 among the electric heater 11 and the cooling circuit 12. This is because if the heat of the temperature control unit 10 when it is heated is conducted to the left and right, it takes extra time for cooling.

  The temperature sensor 13 is a sensor that measures the mold surface temperature at the location where the temperature control unit 10 is installed. The measured temperature is sent to the controller 400 and used for determining the timing of resin injection and the timing of taking out a molded product.

  The heat retaining circuit 20 is a circuit through which a flow medium for keeping the temperature of the mold 100 constant is passed. It is provided at a place other than the place where the temperature control unit 10 is installed, and keeps the temperature of the mold 100 constant. The temperature of the flow medium passing through the heat retaining circuit 20 is set to a temperature equal to or higher than the temperature for finishing the surface of the molded product in a mirror state and the temperature at which the resin is cured.

  In the present embodiment, the shape of the heat retaining circuit 20 is a shape in which a three-branch flow path is provided at a place other than the temperature control unit 10 installed, but is not limited thereto.

  The heat insulating layer 30 is a layer for blocking the conduction of temperature. In the present embodiment, it is a hollow layer formed by combining a recess provided on the side wall of the temperature control unit 10 and a recess provided on the side wall of the mold body 100. It is possible to prevent the heat generated by the heating of the temperature control unit 10 from being transmitted to other than the mold surface.

By providing the heat insulating layer 30, the heat generated by the heating of the temperature control unit 10 can be efficiently transmitted to the mold surface, so that the cooling time can be shortened by efficiently heating only the necessary portions. I can do it.

  The heat insulating layer 30 is not limited to a method realized by providing a space as shown in the present embodiment, and may be realized by embedding a material having a heat insulating effect.

  The width in the height direction of the heat insulating layer 30 is installed so as to cover the entire region from a position closer to the mold surface than the lower end of the electric heater 11 to a position farther from the mold surface than the upper end of the cooling circuit 12. It is preferable. With this configuration, the heat of the temperature control unit can be blocked more effectively.

  As described above, the injection mold 100 according to an embodiment of the present invention can realize different temperature control at a molding defect occurrence location and other locations. Further, the mold 100 is configured so that heat conduction in the injection mold 100 is efficient.

  Next, an injection molding method for controlling the temperature of each location to be optimal at each timing in the configuration of the mold 100 will be described.

<4. Injection Molding Method Using Injection Molding Mold According to Embodiment>
Next, an injection molding method using the injection mold 100 according to the embodiment will be described with reference to FIGS. 5, 6, and 7.

  FIG. 5 is a flowchart showing an injection molding method using an injection mold according to an embodiment of the present invention. FIG. 6 is an explanatory diagram for explaining the timing of the injection molding method of FIG.

  In FIG. 6, the operation timings of the four temperature control units 10 of the temperature control units 1 to 4, the heat retaining circuit 20, and the injection device 200 are shown. Here, although eight temperature control units 10 are installed in FIG. 1, there are four patterns for the main control method of the temperature control unit 10, and therefore, four temperature control units 10 are illustrated here.

Hereinafter, each step of the injection molding method will be described with reference to FIGS. In parentheses, the step number in FIG. 5 and the time in FIG. 6 are shown.

  Each step of FIG. 5 is achieved by the CPU of the controller 400 reading the control program from a storage medium such as a ROM or RAM that stores the control program describing these processing procedures, and interpreting and executing the program. .

  For example, the CPU may operate using the RAM as a work area based on a program stored in the ROM.

  First, a cooling medium is passed through the cooling circuit 12 of the temperature control unit 10 installed in the mold 100 (S100, t0). The temperature of the cooling medium is constant, and the cooling medium is constantly flowed in the injection molding cycle.

  Next, the heat retaining medium is passed through the heat retaining circuit 20 installed in the mold 100 (S102, t0). The temperature of the heat retaining medium is also constant as in the case of the cooling medium, and the heat retaining medium is constantly flowed in the injection molding cycle.

  The step of passing the heat retaining medium may be started at the time t0 at the same time as the cooling medium as shown in FIG. 6, or may be performed after the cooling medium is passed, and the starting order is not limited.

  Next, the temperature of the mold 100 is controlled by controlling ON / OFF of the electric heater 11 based on the mold surface temperature information acquired using the temperature sensor 13 (S104, t0 to t5). Details of the control of the electric heater 11 will be described later with reference to FIGS. 6 and 7.

  Simultaneously with the control of the electric heater 11, it is determined whether or not the temperature of all the temperature sensors 13 has reached a predetermined temperature (S106). Control of the electric heater 11 continues until all the temperature sensors 13 reach a predetermined temperature.

  During this time, the injection device 200 is heated until the mold 100 is heated by the temperature control unit 10, the controller 400 detects that the temperature of the temperature sensor 13 has reached a desired temperature, and the controller 400 instructs to inject resin. Wait (t0 to t5).

  When all the temperature sensors 13 reach a predetermined temperature, all the electric heaters 11 are turned off (S108, t5). Next, the molten resin is injected by the injection device 200 (S110, t5 to t6).

  The electric heaters 11 are all turned off before resin injection, but depending on the type of resin, the state of the injection molding device, etc., electric heater control may be performed until resin injection is completed.

  Although it is necessary to maintain the temperature of the mold 100 at a desired temperature at the time of resin injection, in this embodiment, even if the electric heater 11 is turned off, the desired temperature can be maintained until the resin injection is completed. Therefore, the electric heater 11 was turned off before the resin was injected.

  Following the resin injection, a pressurizing process is started (S112, t6 to t7). Pressure is applied to push the resin firmly into the mold. When the resin is pushed into the mold, it is left as it is and waits for cooling by the cooling circuit 12 and the heat retaining circuit 20 of the temperature control unit (S114, t7 to t8).

  Based on the value of the temperature sensor 13, it is determined whether or not the resin in the mold 100 can be taken out (S 116). The molded product inside is taken out (S118, t8 to t9).

  Next, the control timing of the electric heater 11 in the temperature control unit 10 will be described with reference to FIGS. 6 and 7. FIG. 7 is an explanatory view showing a temperature change of the temperature sensor 13 in the temperature control units 1 to 4 in the injection molding method of FIG.

  Until all the temperature sensors 13 reach a desired temperature (t0 to t5), the electric heater 11 is repeatedly controlled to be turned on / off based on the value of the temperature sensor 13.

  In the present embodiment, a case will be described in which a threshold is set so that resin injection is started when the temperature of the mold 100 reaches Th2 to Th1 at all measurement points.

  Referring to FIG. 7, the temperatures at the points of the temperature control units 1 to 4 are changed, and the temperatures at all points of the temperature control units 1 to 4 become values between Th2 and Th1 for the first time at the time point t5. Therefore, all the electric heaters are turned off at t5.

  The temperature change of the temperature control units 1 to 4 during this time and the control contents of the electric heater will be examined. First, the electric heaters 1 to 3 are turned on at t0. Since a timer is set for the electric heater 4, the electric heater 4 is kept off until the set time elapses.

  At t1, since the set time has elapsed, the electric heater 4 is turned on. For those whose temperature rise is known in advance, extra heating can be avoided by using a timer to start energization after a predetermined time.

  Subsequently, at t2, the value of the temperature sensor 13 of the temperature control unit 2 is equal to or greater than Th1, and exceeds the temperature range of Th2 to Th1. Therefore, the electric heater 11 of the temperature control unit 2 is turned off.

  Next, at t3, the temperature of the temperature control unit 2 that was turned off at t2 fell below Th2. Accordingly, the electric heater 11 of the temperature control unit 2 is turned on again.

  Subsequently, at t4, the temperature of the temperature control unit 3 exceeded Th1. Therefore, the power source of the electric heater 11 of the temperature control unit 3 is turned off.

  At t5, all the temperatures of the temperature control units 1 to 4 become temperatures in the range of Th2 to Th1. Therefore, all the electric heaters 11 of the temperature control units 1 to 4 are turned off at t5.

  As above, the temperature control units 1 to 4 have been exemplified and the four control patterns have been described. However, these control methods are merely examples, and it is naturally possible to combine, for example, control by a timer and control by ON / OFF of the electric heater 11.

  Even when the same equipment is used, the mold temperature is affected by the climate of the land where the equipment is used, the temperature of the day, and how the equipment is used. Therefore, by controlling according to the temperature measured as described above, for example, even when a sudden temperature change occurs as shown in the temperature control unit 2, the temperature can be kept within a predetermined temperature range.

  In the present embodiment, an electric heater is used as the heating means. For example, as compared with a case where a heating medium is passed through a circuit, heating and heating stop can be switched only by energizing and stopping energization of the electric heater, which is preferable in the case of this embodiment in which temperature control is performed.

  In addition, the configuration in which the heating medium and the cooling medium are passed through the same circuit requires complicated piping equipment and a fluid switching device using valves, and the handling of the high-temperature and high-pressure heating medium is complicated and takes time to ensure safety. However, these problems can be solved by using an electric heater.

  As described above, when the temperature of the mold is kept within a predetermined range at the time of injecting the resin, molding defects can be suppressed and the extension of the cooling time due to overheating can be suppressed. Therefore, the time required for heating and cooling the mold during the injection molding cycle can be shortened, and energy consumption can be saved.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. These are naturally understood to belong to the technical scope of the present invention.

  For example, in the said embodiment, although it was set as the structure which installs the heat retention circuit 20 in parts other than the installation location of the temperature control unit 10, this invention is not limited to this example. If the required temperature can be maintained without installing the heat retaining circuit 20, the configuration may be omitted.

  For example, in the said embodiment, although the temperature control unit 10 was set as the structure joined by the metal mold | die main body and a side surface, this invention is not limited to this example. For example, the temperature control unit may be embedded in the mold body, or the temperature control unit may be inserted.

  Further, for example, in the above-described embodiment, four electric heaters and cooling circuit 12 are divided and installed in one temperature control unit 10, but the number of each is not limited to this.

  For example, three electric heaters 11 and four cooling circuits 12 may be configured. For example, four electric heaters 11 and seven cooling circuits 12 may be configured.

  Further, for example, in the above embodiment, the flow rate of the cooling medium is constant, but the present invention is not limited to this, and the flow rate of the cooling medium may be controlled. For example, the flow rate may be controlled as shown in FIG. FIG. 8 is a diagram showing a change in the flow rate of the cooling medium passing through the cooling circuit 12 in the injection molding cycle.

  The time t in FIG. 8 corresponds to the time of the injection molding cycle shown in FIG. For example, during the heating control from t0 to t5, the flow rate of the cooling medium passed through the cooling circuit 12 of the temperature control unit 10 is decreased to increase the heating effect of the electric heater 11, and for example, at t5 to t8, the cooling effect is increased. Alternatively, the flow rate of the cooling medium passing through the cooling circuit 12 may be increased. Furthermore, the flow rate of the cooling medium may be reduced again in preparation for the next cycle during the removal of the molded product from t8 to t9.

  Such flow rate control can be realized by a flow rate control mechanism in the flow medium device of the cooling circuit 12 and timing control from the controller 400. Thus, the temperature control can be performed more accurately by controlling the flow rate of the cooling medium.

  In FIG. 8, although embodiment which changes a flow volume in t5 and t8 was demonstrated, it is not restricted to this. Further, the flow rate change timing may be realized based on the value of the temperature sensor, or may be changed according to a predetermined timer.

  Moreover, in the said embodiment, although the same value as Th1-Th2 was used for all the temperature threshold values of several temperature control units, this invention is not limited to this example. For example, different values may be set for each temperature control unit, and it may be determined whether or not each desired temperature has been reached.

  The temperature at which the molding defect can be eliminated at each molding defect occurrence location of the mold 100 is different. For example, when the thickness of the molded product is different or the distance from the gate is different, the temperature at which the resin reaches the weld portion is different, and the ease with which the weld comes out varies depending on the angle at which the resin meets.

  If the temperature control unit 10 according to the embodiment of the present invention is used, different temperature control can be performed at each molding defect occurrence location. Therefore, the thickness of the molded product, the distance from the gate, and the resin association as described above. It is possible to cope with the difference in the optimum temperature depending on the angle.

  In this specification, the steps described in the flowcharts are executed in parallel or individually even if they are not necessarily processed in time series, as well as processes performed in time series in the described order. Processing to be performed. Also, it goes without saying that the order of steps processed in time series can be appropriately changed depending on circumstances.

DESCRIPTION OF SYMBOLS 10 Temperature control unit 11 Electric heater 12 Cooling circuit 13 Temperature sensor 20 Thermal insulation circuit 30 Heat insulation layer 100 Mold 200 Injection apparatus 300 Fluid medium apparatus 400 Controller

Claims (13)

It is equipped with a temperature control unit that is installed according to molding defects.
The temperature control unit is
An electric heater installed in parallel with the mold surface in the vicinity of the mold surface;
A cooling circuit installed in parallel to the mold surface and the electric heater at a position farther than the electric heater with respect to the mold surface;
The electric heater and the cooling circuit are injection molds formed such that the surface of the electric heater and the surface of the cooling circuit are alternately opposed to the surface of the mold. The injection mold according to claim 1, further comprising a heat retention circuit installed in a mold main body adjacent to the temperature control unit. In the cross section perpendicular to the mold surface, the electric heater and the cooling circuit are installed so as to repeat a shape alternately arranged at the apex of the W-shape,
The injection mold according to claim 1 or 2.   The injection mold according to any one of claims 1 to 3, wherein among the electric heater and the cooling circuit, the cooling circuit is disposed at left and right ends in the temperature control unit. The injection mold according to any one of claims 1 to 4, wherein the temperature control unit further includes a temperature sensor that measures the mold surface temperature. The injection mold according to any one of claims 1 to 5, further comprising a heat insulating layer installed on a boundary surface between the temperature control unit and the mold body. The mold for injection molding according to claim 6, wherein the heat insulating layer is formed by providing a recess in a side wall of the temperature control unit. The heat insulating layer is installed from a position closer to the mold surface than the lower end of the electric heater to a position farther from the mold surface than the upper end of the cooling circuit.
The injection mold according to claim 6 or 7. An electric heater installed in parallel with the mold surface in the vicinity of the mold surface;
A cooling circuit installed in parallel to the mold surface and the electric heater at a position farther than the electric heater with respect to the mold surface;
The electric heater and the cooling circuit are formed such that the surface of the electric heater and the surface of the cooling circuit are alternately opposed to the mold surface, and the electric heater and the cooling circuit are arranged in accordance with a molding defect occurrence location of the injection mold. Temperature control unit used for injection molds. Passing a refrigerant through a cooling circuit of at least one temperature control unit installed at a molding defect occurrence location in the injection mold,
Switching between energization and de-energization of the electric heater in the temperature control unit according to the value of the temperature sensor in the temperature control unit, and controlling the temperature;
An injection molding method including a step of stopping energization of the electric heater and injecting resin when a value of the temperature sensor becomes equal to or higher than a predetermined temperature.   The injection molding method according to claim 10, further comprising a step of controlling a flow rate of the refrigerant passing through the cooling circuit.   The injection molding method according to claim 11, wherein the flow rate of the refrigerant is greater during the resin injection than during the temperature control step. The injection molding method according to claim 10, wherein the predetermined temperature is set to a different value for each temperature control unit.

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