JP7079480B2 - Mold temperature control device and mold temperature control method - Google Patents

Description

The present invention relates to a mold temperature control device and a mold temperature control method.

A mold is used in an injection molding machine that injects a molded product using a synthetic resin such as plastic. The injection molding mold has a cavity, which is a space portion filled with the molten plastic, and a flow path through which a medium for cooling and solidifying the molten plastic flows. In order to improve the accuracy of the molded product, a mold temperature adjusting device that accurately adjusts the temperature of the medium (mold) to the required temperature is used.

Patent Document 1 includes a heater in which a heat generating portion of a heater is immersed in a tank through which a medium passes, and the medium is heated by a heater at the time of heating, and cold water is put in from a water supply port at the time of cooling and cooled by heat exchange. , A mold temperature control device for controlling the temperature of a medium is disclosed.

Japanese Unexamined Patent Publication No. 2007-7950

However, since the medium (generally water) contains inorganic salt compounds such as calcium, magnesium, and silica, scale adheres to the surface of the heater when the heater is immersed in the medium. Since the attached scale is very hard and difficult to dissolve in water, once it adheres to the surface of the heater, the heat transfer coefficient decreases, and the heater may overheat and fail. In addition, since the heat transfer coefficient is lowered, the medium may not be sufficiently heated, which may hinder the temperature adjustment of the medium.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a mold temperature control device and a mold temperature control method capable of suppressing the generation of scale and preventing overheating of a heater.

The temperature control device according to the present invention is a temperature control device that controls the temperature of a medium circulated to an object through a pipeline, and energizes a heater pipe provided on the outer periphery of a flow path pipe through which the medium flows. The medium temperature control unit that repeatedly turns on / off to control the temperature of the medium and the total time of the energization off time for each predetermined cycle or the energization off time for a period of multiple times of the predetermined cycle are adjusted. It is provided with a temperature control unit for the heater pipe that controls the temperature of the heater pipe.

The temperature control method according to the present invention is a temperature control method for controlling the temperature of a medium circulated to an object through a pipeline, and energizes a heater pipe provided on the outer periphery of a flow path pipe through which the medium flows. The temperature of the medium is controlled by repeating on / off, and the temperature of the heater pipe is adjusted by adjusting the energization off time for each predetermined cycle or the total energization off time for a period of multiple times of the predetermined cycle. Control.

According to the present invention, it is possible to suppress the generation of scale and prevent the heater from overheating.

It is explanatory drawing which shows an example of the structure of the mold temperature controller as the temperature control device of this embodiment. It is an external perspective view which shows an example of the structure of the heater device of this embodiment. It is an exploded perspective view which shows an example of the structure of the heater device of this embodiment. It is a front view which shows an example of the structure of the heater device of this embodiment. It is a schematic diagram which shows the main part of the heater pipe wound around the outer circumference of a flow path pipe. It is a front view which shows the other example of the structure of the heater device of this embodiment. It is explanatory drawing which shows an example of the operation mode of a heater device. It is a schematic diagram which shows an example of the relationship between the heater temperature and the total time of energization off time. It is a schematic diagram which shows an example of the fluctuation of a heater temperature when the total time of energization off time is changed. It is a schematic diagram which shows the 1st example of the temperature control method by the mold temperature controller of this embodiment. It is a schematic diagram which shows the relationship between the medium set temperature and the total time of energization off time. It is a schematic diagram which shows an example of the transition of the temperature of a medium. It is a schematic diagram which shows the 2nd example of the temperature control method by the mold temperature controller of this embodiment. It is a schematic diagram which shows the relationship between the flow rate and the medium temperature difference between the inlet and outlet of a heater device. It is a schematic diagram which shows the relationship between a flow rate and a heater temperature. It is a schematic diagram which shows the relationship between the medium temperature difference between the inlet and outlet of a heater device, and a heater temperature. It is a schematic diagram which shows the relationship between the medium temperature difference between the inlet and outlet of a heater device, and the total time of energization off time. It is a flowchart which shows an example of the processing procedure of the temperature control method of the mold temperature controller of this embodiment.

Hereinafter, the present invention will be described with reference to the drawings showing the embodiments thereof. FIG. 1 is an explanatory diagram showing an example of the configuration of the mold temperature controller 100 as the temperature control device of the present embodiment. In the present embodiment, the mold temperature controller 100 will be described as an example of the temperature control device, but the temperature control device is not limited to the mold temperature controller. The mold temperature controller 100 adjusts (controls) the temperature of the mold 200 as an object, more specifically, the temperature of the medium supplied to the mold 200.

As shown in FIG. 1, in the mold temperature controller 100, a pipe line 11 (feeding pipe line) is connected between the outlet side (OUT) of the pump 31 and the inlet side of the mold 200, and the mold 200 is connected. A pipe line 12 (return pipe line) is connected between the outlet side of the pump 31 and the inlet side (IN) of the pump 31, and the medium (for example, water) is moved into the pipe lines 11 and 12 and the bypass pipe line 16 by the pump 31. Is designed to circulate. That is, for example, the pump 31 rotates the impeller at high speed by the rotation of the motor in the casing and utilizes the centrifugal force acting on the medium, so that the medium circulates in the pipelines 11 and 12 and the bypass pipeline 16.

A pressure sensor 62 is provided near the outlet side of the pump 31 in the pipeline 11, and the pressure of the medium near the outlet side of the pump 31 can be measured. A heater device 80 is interposed in the middle of the pipeline 11, and the medium can be heated to raise the temperature of the medium. The thermostat 801 stops heating by the heater device 80 when the heater pipe (not shown) of the heater device 80 exceeds a predetermined temperature. Details of the heater device 80 will be described later.

A temperature sensor 71 is provided in the pipeline 11 on the upstream side of the heater device 80, and a temperature sensor 72 is provided in the pipeline 11 on the downstream side of the heater device 80. The temperature sensor 71 can detect the medium temperature on the upstream side of the heater device 80, and the temperature sensor 72 can detect the medium temperature on the downstream side of the heater device 80. The temperature sensor 73 can detect the surface temperature of the heater pipe of the heater device 80. In the present specification, the surface temperature of the heater pipe is also referred to as a heater temperature.

The pipeline 11 is branched into two systems on the way, and each of the branched pipelines 11 is connected to the inlet side of the mold 200. A transmission valve 21 is interposed in each of the branched pipelines 11, and the flow rate of the medium for each of the branched pipelines 11 can be adjusted. Similarly, the pipeline 12 is also branched into two systems on the outlet side of the mold 200, and the pipeline 12 branched in the middle is integrated into one pipeline 12. A return valve 22 is interposed in each of the branched pipelines 12, and the flow rate of the medium for each of the branched pipelines 12 can be adjusted.

A heat exchanger 40 is interposed in the middle of the pipeline 12, and a cooling solenoid valve 23 is interposed in the pipeline 12 on the outlet side of the heat exchanger 40. Further, a required location of the pipeline 12 on the inlet side of the heat exchanger 40 (a location indicated by reference numeral A in FIG. 1, also referred to as a branch point A) and a required location of the pipeline 12 on the outlet side of the cooling solenoid valve 23 (FIG. A bypass pipeline 16 is provided between the portion indicated by the reference numeral B of 1 and the branch point B).

The heat exchanger 40 has a cooling flow path 13a through which cooling water flows on the primary side, and a medium flow path 12a on which a medium flows on the secondary side. Both ends of the cooling flow path 13a communicate with a cooling pipeline 13 for supplying cooling water. Both ends of the medium flow path 12a communicate with the pipeline 12. The heat exchanger 40 exchanges heat between the cooling water flowing through the cooling flow path 13a and the medium flowing through the medium flow path 12a, and cools the medium flowing through the medium flow path 12a to adjust the temperature. In addition, in FIG. 1, the mold temperature controller 100 is configured to include a heat exchanger 40, but the mold temperature controller 100 is not limited to the example of FIG. 1, and the heat exchanger 40 is not limited to the example. The medium may be cooled by supplying water directly to the pipelines 11 and 12 from the water supply port without providing the above.

A pressure sensor 63 and an open relief valve are provided near the inlet side of the pump 31 in the pipeline 12. The pressure sensor 63 measures the pressure of the medium near the inlet side of the pump 31. Further, a strainer is provided in the pipeline 12 (upstream side from the branch point A) on the inlet side of the heat exchanger 40. The strainer removes the solid component contained in the medium.

A pipeline 14 is provided between the water supply port and the branch point B of the pipeline 12. A strainer and a pressure sensor 61 are provided on the water supply port side of the pipeline 14. The pressure sensor 61 measures the water supply pressure. A check valve 26 is interposed in the middle of the pipeline 14, and branch pipes 14a interposed with the pressurizing pump 32 are connected to both sides of the check valve 26.

The pressurizing pump 32 pressurizes the medium (for example, water) in the pipelines 11 and 12 and the bypass pipeline 16 so that the pressure is higher than the saturated vapor pressure.

Further, a cooling pipeline 13 for branching the cooling water and flowing it to the heat exchanger 40 is connected to the upstream side of the portion where the branch pipe 14a of the pipeline 14 is connected. The cooling pipeline 13 is connected to one end of the cooling flow path 13a on the inlet side of the heat exchanger 40. The cooling pipeline 13 connected to the other end of the cooling flow path 13a on the outlet side of the heat exchanger 40 is connected to the drain port. A cooling water solenoid valve 25 is interposed in the middle of the cooling pipeline 13 connected to the drain port.

A drainage pipe line 15 connected to a drainage port is connected to the pipe line 12 between the heat exchanger 40 and the cooling solenoid valve 23. A drainage solenoid valve 24 is interposed in the middle of the drainage pipe line 15.

Further, the mold temperature controller 100 includes a control unit 50, and the control unit 50 includes a valve opening / closing control unit 51, a heater pipe temperature control unit 52, and a medium temperature control unit 53. In the example of FIG. 1, the heater pipe temperature control unit 52 and the medium temperature control unit 53 are separately provided, but the present invention is not limited to this, and the heater pipe temperature control unit 52 and the medium temperature are not limited thereto. The control unit 53 may be collectively configured as one temperature control unit. The temperature control unit 52 for the heater pipe and the medium temperature control unit 53 can acquire the temperature detected by the temperature sensors 71, 72, and 73.

The valve opening / closing control unit 51 controls the opening / closing of the cooling solenoid valve 23, the drainage solenoid valve 24, and the cooling water solenoid valve 25. Further, the medium temperature control unit 53 controls to raise the temperature of the medium in the heating step and controls to lower the temperature of the medium in the cooling step.

The outline of the operation of the mold temperature controller 100 is as follows. When the drainage solenoid valve 24, the cooling solenoid valve 23, the medium transmission valve 21, and the return medium valve 22 are opened to supply water as a medium from the water supply port, the circulation passages such as the pipelines 11 and 12 and the bypass pipeline 16 are supplied. The air is completely discharged, and then the drainage solenoid valve 24 is closed to fill the circulation passages such as the pipes 11 and 12 and the bypass pipe 16 with a medium. Further, the pressure of the medium in the circulation passages such as the pipelines 11 and 12 and the bypass pipeline 16 is maintained above the saturated vapor pressure corresponding to the temperature of the medium by the pressurizing pump 32. At the time of heating control, the temperature of the medium in the circulation passage such as the pipes 11 and 12 and the bypass pipe 16 is heated by the heater device 80 and raised to a required set temperature. Further, at the time of cooling control, the temperature of the medium in the circulation passage such as the bypass pipe 16 becomes a required set temperature by supplying water into the circulation passage directly from the heat exchanger 40 or the water supply port. To be cooled. By the heating operation and cooling operation by the heater device 80, the temperature of the medium in the circulation passage such as the pipes 11 and 12, the bypass pipe 16, that is, the temperature of the medium in the mold 200 is adjusted (controlled) to the required set temperature. Be done (when stable).

Next, the heater device 80 will be described in detail. The heater device 80 is composed of one or a plurality of heating units.

FIG. 2 is an external perspective view showing an example of the configuration of the heater device 80 of the present embodiment, FIG. 3 is an exploded perspective view showing an example of the configuration of the heater device 80 of the present embodiment, and FIG. 4 is an exploded perspective view. It is a front view which shows an example of the structure of the heater device 80 of an embodiment. The examples of FIGS. 2, 3 and 4 show a case where the heater device 80 is composed of one heating unit. Further, in FIG. 4, for convenience, the internal structure is shown so as to be understood.

The heater device 80 (heating unit) includes a flow path pipe 811 (first flow path pipe), a flow path pipe 812 (second flow path pipe), and a flow path pipe 813 arranged in parallel through a required gap. (Third flow path tube) and manifolds 84, 85 provided at both ends of each flow path tube 811, 812, 813 form a flow path of the medium. Two heater pipes 815 and 815 are wound around the outer periphery of the flow path pipe 811 along the flow path direction of the flow path pipe 811 with an appropriate length of separation. Two heater pipes 816 and 816 are wound around the outer periphery of the flow path pipe 812 along the flow path direction of the flow path pipe 812 with an appropriate length of separation. Two heater pipes 817 and 817 are wound around the outer periphery of the flow path pipe 813 along the flow path direction of the flow path pipe 813 with an appropriate length of separation.

The heater pipes 815, 816, and 817 have a structure in which a heating element such as a nichrome wire is wrapped with a metal pipe via an insulator, and is also referred to as a sheathed heater.

The manifold 84 is formed with an inlet / outlet pipe 841 that functions as an inlet or outlet of the medium to the heating unit or an outlet of the medium from the heating unit, and a communication pipe 842 that communicates the ends of the two flow passage pipes. Further, the manifold 85 is formed with an inlet / outlet pipe 851 that functions as an inlet / outlet of the medium to the heating unit or an outlet of the medium from the heating unit, and a communication pipe 852 that communicates the ends of the two flow path pipes. be.

That is, an inflow port (inlet / output pipe 851) is provided at one end 811a of the flow path pipe 811, and the other end 811b of the flow path pipe 811 and one end 812b of the flow path pipe 812 are connected to each other as a communication pipe 842 (first communication pipe). The other end 812a of the flow path pipe 812 and the one end 813a of the flow path pipe 813 are communicated with each other by a communication pipe 852 (second communication pipe), and the outlet (inlet / out) is connected to the other end 813b of the flow path pipe 813. A pipe 841) is provided. The medium flows in from the inflow port (inlet / out pipe 851), flows in the flow path pipes 811, 812, and 813, and flows out from the outflow port (inlet / out pipe 841). The medium flowing in the flow path pipes 811, 812, 813 is heated by the heater pipes 815, 816, 817.

Two lead wires are drawn from both ends of the heater pipe 815, and the two lead wires are connected to, for example, a three-phase alternating current U terminal and a V terminal. Two lead wires are drawn from both ends of the heater pipe 816, and the two lead wires are connected to, for example, a three-phase alternating current V terminal and a W terminal. Two lead wires are drawn from both ends of the heater pipe 817, and the two lead wires are connected to, for example, a three-phase alternating current W terminal and a U terminal. Thereby, each phase of the three-phase AC can be associated with any one of the three sets of heater pipes 815, 816, and 817 to apply the power supply, and the three-phase AC power supply can be supported.

A cover 81 is attached to the back side and covers 82, 83 are attached to the front side so that the heater pipes 815, 816, and 817 cover the flow path pipes 811, 812, and 813, respectively. .. A gap is provided between the cover 82 and the cover 83, between the cover 82 and the manifold 84, and between the cover 83 and the manifold 85 so that the lead wires of the heater pipes 815, 816, and 817 can be drawn out. A heat insulating material (not shown) is provided between the heater pipes 815, 816, 817 and the inner surfaces of the covers 81, 82, 83. The heat insulating material can prevent the heat of the heater pipes 815, 816, and 817 from being dissipated to the outside, and can be transmitted to the flow path pipes 811, 812, and 813.

Further, the three flow path pipes 811, the flow path pipe 812, and the flow path pipe 813 are arranged in parallel along the flow path direction, and the manifolds 84, 85 provided at both ends of the flow path pipes 811, 812, 813 are provided. By forming the flow path of the medium, the effective length of the heater pipes 815, 816, and 817 in the flow path direction can be lengthened without increasing the outer diameter of the heating unit, and the heating unit can be downsized. Contribute.

FIG. 5 is a schematic view showing a main part of the heater pipe 817 wound around the outer periphery of the flow path pipe 813. Since the same applies to the other heater pipes 815 and 816, the description thereof will be omitted. As shown in FIG. 5, when the outer diameter of the heater pipe 817 is φ and the pitch of the adjacent heater pipes 817 on the outer circumference of the flow path pipe 813 is p, the outer diameter φ of the heater pipe 817 is the heater pipe 817. It is smaller than the pitch p (φ <p). That is, the heater pipes 817 are not in close contact with each other, and the heater pipes 817 adjacent to each other on the outer periphery of the flow path pipe 813 are wound around the outer periphery of the flow path pipe 813 with a gap between them. By providing a gap, overheating of the heater pipe 817 can be prevented.

The outer diameter φ of the heater pipes 815, 816, and 817 can be 5 mm or less. As a result, the number of windings of the heater pipes 815, 816, and 817 wound around the outer circumferences of the flow path pipes 811, 812, and 813 having a predetermined length can be relatively increased, and the outer circumferences of the flow path pipes 811, 812, and 813 can be wound. The contact area of the heater pipes 815, 816 and 817 can be increased, and the heat of the heater pipes 815, 816 and 817 can be efficiently transferred to the medium through the flow path pipes 811, 812 and 813.

The heater pipes 815, 816, and 817 are coiled with an inner diameter slightly smaller than the outer diameter of the flow path pipes 811, 812, and 813, and the flow path pipes are inside the coiled heater pipe 815. Insert 811. The heater pipe 815 into which the flow path pipe 811 is inserted exerts a force to shrink toward the center of the diameter due to its elasticity, and the heater pipe 815 can be crimped to the flow path pipe 811 to heat the heater pipe 815. Can be transmitted to the flow path pipes 811, 812, and 813. The same applies to the other heater pipes 816 and 817.

Further, the heater pipes 815, 816 and 817 may be brazed to the flow path pipes 811, 812 and 813. As a result, the heat of the heater pipes 815, 816, and 817 can be further transferred to the flow path pipes 811, 812, and 813.

The power density of the heating unit can be 10 W or less per square cm. The power density is the power load (W) per unit area (1 square cm) of the heater pipes 815, 816, and 817. For example, if the outer diameters of the heater pipes 815, 816, and 817 are φ, the effective length of the wound heater pipes 815, 816, and 817 in the flow path direction is L, and the electric power is W, the power density is W / It can be expressed as (φ × π × L). By setting the power density to 10 W or less per square cm, overheating of the heater pipes 815, 816, and 817 can be prevented.

FIG. 6 is a front view showing another example of the configuration of the heater device 80 of the present embodiment. In the example of FIG. 6, the heater device 80 is composed of two heating units. As shown in FIG. 6, the manifold 84 of one heating unit and the manifold 85 of the other heating unit are connected by a connecting pipe 86.

A plurality of heating units can be connected. As a result, the temperature of the medium can be adjusted to the set temperature simply by connecting the required number of heating units according to the size of the heating capacity of the heater device 80, and the heating units can be shared. The cost can be reduced without increasing the types of parts according to the heating capacity.

Further, as shown in FIG. 6, when connecting two heating units, the heater is arranged by arranging the two heating units in the direction orthogonal to the flow path direction instead of the flow path direction having a relatively long dimension. It is possible to suppress the increase in the outer diameter of the device 80 and reduce the size. The number of heating units that can be connected is not limited to two. For example, there may be three or more. When connecting three or four heating units, for example, they can be arranged on the back side of the two heating units. In this case, a U-shaped connecting pipe can be used.

Next, the operation of the heater device 80 will be described. Specifically, the temperature control unit 52 for the heater pipe and the medium temperature control unit 53 control the operation of the heater device 80.

The medium temperature control unit 53 repeatedly turns on / off the energization of the heater pipes 815, 816, and 817 provided on the outer periphery of the flow path pipes 811, 812, and 813 (for example, at a predetermined cycle) to control the temperature of the medium. do. Since the heater pipes 815, 816, 817 are provided on the outer periphery of the flow path pipes 811, 812, 813, the medium does not touch the heater pipes 815, 816, 817 and is on the surface of the heater pipes 815, 816, 817. The scale does not adhere. This makes it possible to prevent a decrease in the heat transfer coefficient of the heater device 80.

The predetermined cycle is also referred to as a proportional cycle. In the following description, the term proportional period is used. The proportional period can be, for example, 1 second, 2 seconds, or the like. The medium temperature control unit 53 adjusts so that when the temperature of the medium becomes higher than the set temperature, the cooling medium energization on time, which is the time for turning on the cooling medium in the proportional cycle of the cooling process, becomes longer (for example, 5 to 8 seconds). And control to lower the temperature of the medium. Further, the medium temperature control unit 53 adjusts the medium so that the energization off time in the proportional cycle of the heating step becomes short (for example, 0.1 seconds to 0.05 seconds) when the temperature of the medium becomes lower than the set temperature. Control to raise the temperature of. The energization off time is adjusted every proportional cycle. Further, the required temperature range including the set temperature of the medium is also referred to as a proportional band, and the proportional band can be, for example, a set temperature ± 10 ° C. or a set temperature ± 5 ° C.

When the temperature of the medium is higher than the set temperature, the heat exchanger 40 performs a cooling operation. For example, by opening and closing the cooling solenoid valve 23, the medium maintained at a relatively low temperature in the medium flow path 12a of the heat exchanger 40 is piped while the cooling solenoid valve 23 is open for a required time. The temperature of the medium can be lowered by flowing through the paths 12, 11 and the bypass pipeline 16. Further, by opening the cooling water electromagnetic valve 25 at the required timing for the required time, the cooling water from the water supply port flows into the cooling flow path 13a of the heat exchanger 40, and the temperature of the medium flow path 12a of the heat exchanger 40 is adjusted. It can be maintained at the required temperature (eg 80 ° C.).

The temperature control unit 52 for the heater pipe also controls the temperature (surface temperature) of the heater pipes 815, 816, and 817 of the heater device 80. Specifically, the temperature control unit 52 for the heater pipe adjusts the energization off time for each proportional cycle or the total energization off time over a plurality of proportional cycles to adjust the energization off time of the heater pipes 815, 816, and 817. Control the temperature. A period spanning multiple proportional cycles is also referred to as a control cycle.

More specifically, the temperature control unit 52 for the heater pipe adjusts the total time of the energization off time in a period over a plurality of proportional cycles of PID control (Proportional-Integral-Differential Controller) to adjust the heater pipe 815. The temperature of 816 and 817 can be controlled. The PID control is the control of the temperature of the medium by the medium temperature control unit 53, and controls the energization off time as a linear function of the deviation between the actual temperature of the medium and the target temperature. As a result, it is possible to prevent the temperature of the heater pipes 815, 816 and 817 from exceeding the upper limit temperature, and prevent the heater pipes 815, 816 and 817 from overheating.

FIG. 7 is an explanatory diagram showing an example of the operation mode of the heater device 80. Assuming that the proportional cycle is T and the number of proportional cycles (also referred to as the number of cycles) is n, the control cycle can be represented by n × T. The number of cycles n can be, for example, 15, but is not limited to this, and may be 10 cycles, 20 cycles, or 30 cycles. In the following description, the proportional cycle T is 1 second and the number of cycles n is 15. The control cycle is 15 seconds.

As shown in FIG. 7, assuming that the energization off times of cycles 1, 2, ..., N are d1, d2, ..., Dn, respectively, the total energization off time Dn in the control cycle is expressed by the equation (1). Can be done.

Further, instead of the equation (1), the total time Dn of the energization off time in the control cycle can be expressed by the equation (2). Here, di is an energization off time that satisfies the equation (3). In the formula (3), dm in is the minimum energization off time. That is, the total energization off time Dn in the control cycle can be set to the total energization off time of the minimum energization off time dm or more among the energization off times in each proportional cycle. In other words, the total time is calculated by excluding the energization off time less than the minimum energization off time dm.

When the temperature of the heater pipes 815, 816, and 817 becomes high, the temperature control unit 52 for the heater pipe targets the temperature of the heater pipes 815, 816, and 817 by adjusting so that the total time Dn becomes long. It can approach the temperature. As a result, it is possible to prevent the temperature of the heater pipes 815, 816 and 817 from exceeding the upper limit temperature, and prevent the heater pipes 815, 816 and 817 from overheating.

Further, as shown in FIG. 7, the medium temperature control unit 53 can operate the heater device 80 in the continuous energization mode (first control mode) and the on / off energization mode (second control mode). The continuous energization mode is a mode in which the energization off time for each proportional cycle is set to 0 and the heater pipes 815, 816, and 817 are continuously energized. The on / off energization mode is a mode in which the on / off of energization of the heater pipes 815, 816, and 817 is repeated in a proportional cycle. In this specification, even when the energization time becomes 0 in one or a plurality of proportional cycles in the control cycle, it is included in the on / off energization mode.

When raising the temperature of the medium from the heating start temperature (for example, 20 ° C.) to the set temperature (for example, 180 ° C.), the medium temperature control unit 53 can use the continuous energization mode. Further, when the temperature of the medium is maintained at the set temperature, the medium temperature control unit 53 can use the on / off energization mode. Even when the temperature of the medium is raised from the heating start temperature to the set temperature, the medium temperature control unit 53 can use the on / off energization mode.

Next, a method of setting the total time Dn of the energization off time in the control cycle (n × T) will be described. For convenience, in the following description, the temperatures of the heater pipes 815, 816, and 817 are referred to as heater temperatures.

FIG. 8 is a schematic diagram showing an example of the relationship between the heater temperature and the total time Dn of the energization off time. In FIG. 8, the vertical axis represents temperature and the horizontal axis represents time. The minimum flow rate of the medium by the mold temperature controller 100 is 10 l / min, and the maximum flow rate is 65 l / min. Since the amount of heat transfer from the heater pipes 815, 816, and 817 to the medium is small when the flow rate of the medium is the minimum flow rate, the heater temperature becomes the highest, which affects the total time Dn of the control cycle or the energization off time. Cheap. Therefore, in the example of FIG. 8, the flow rate is set to the minimum flow rate of 10 l / min. The set temperature of the medium is 180 ° C. The proportional cycle T is 1 second, the number of cycles is 15, and the control cycle is 15 seconds. In the chart of FIG. 8, after the heater temperature is set to the initial temperature (for example, the target temperature is set to 290 ° C.), the heater is continuously energized (energization off time = 0), and the total energization off time of the control cycle is totaled. The transition of the heater temperature is shown when the time Dn is 0.25 seconds, 0.5 seconds, and 1.0 seconds, respectively. In FIG. 8, for convenience, the maximum heater temperature is plotted when the energization off time is provided.

In the case of continuous energization, the heater temperature starts to rise from the initial temperature and continues to rise to a considerably high temperature. When the total time Dn = 0.25 seconds, the heater temperature starts to gradually rise from the initial temperature, and when the temperature rises to a relatively high temperature, the heater temperature becomes stable thereafter. When the total time Dn = 0.5 seconds, the heater temperature is stable while maintaining almost the initial temperature. When the total time Dn = 1.0 second, the heater temperature starts to gradually decrease from the initial temperature, and when the temperature decreases to a slightly lower temperature, the heater temperature stabilizes thereafter.

FIG. 9 is a schematic diagram showing an example of fluctuations in the heater temperature when the total time Dn of the energization off time is changed. In FIG. 9, the vertical axis represents temperature and the horizontal axis represents time. FIG. 9A shows the state of fluctuation of the heater temperature when the total time Dn = 0.5 seconds. When the total time Dn = 0.5 seconds, the total time of the ON time in the control cycle is 14.5 seconds, and the total time of the OFF time is 0.5 seconds. When the total time Dn = 0.5 seconds, the heater temperature at the beginning (start point) and the heater temperature at the end (end point) of the control cycle are about the same, and the heater temperature is stable without showing an upward tendency or a downward tendency. It can be seen that the temperature changes.

FIG. 9B shows the state of fluctuation of the heater temperature when the total time Dn = 0.25 seconds. When the total time Dn = 0.25 seconds, the total time of the ON time in the control cycle is 14.75 seconds, and the total time of the OFF time is 0.25 seconds. It can be seen that when the total time Dn = 0.25 seconds, the heater temperature at the end (end point) becomes higher than the heater temperature at the beginning (start point) of the control cycle, and the heater temperature gradually rises and then becomes constant. ..

FIG. 9C shows the state of fluctuation of the heater temperature when the total time Dn = 1.0 second. When the total time Dn = 1.0 second, the total time of the ON time in the control cycle is 14.0 seconds, and the total time of the OFF time is 1.0 second. It can be seen that when the total time Dn = 1.0 second, the heater temperature at the end (end point) is lower than the heater temperature at the beginning (start point) of the control cycle, and the heater temperature gradually decreases and then becomes constant. ..

In order to prevent overheating of the heater pipes 815, 816, and 817, it is necessary for the heater temperature to maintain the target temperature in the on / off energization mode, and the heater temperature may change stably or in a downward trend. desirable. Further, if the heater temperature can be maintained at the target temperature under the condition where the heater temperature is the highest, for example, when the flow rate of the medium is the minimum flow rate, the heater temperature exceeds the target temperature even if the flow rate of the medium fluctuates. It does not rise. Therefore, the total time Dn of the energization off time in the control cycle is preferably 0.5 seconds or more as an example.

Similar results can be obtained by changing the proportional period T and the number of cycles n.

The temperature control unit 52 for the heater pipe can set the total energization off time of the control cycle over a predetermined number of proportional cycles (number of cycles) to be one half or more of the proportional cycle. Assuming that the proportional cycle is T and the number of cycles is n, the total time Dn of the energization off time of the control cycle (n × T) can satisfy the equation (4).

For example, as described above, when the proportional cycle T is 1 second and the number of cycles is 15 seconds, the total time Dn of the energization off time can be 0.5 seconds or more. Even when the number of cycles is, for example, 10 or 20, the total time Dn of the energization off time can be 0.5 seconds or more. Further, when the proportional period T is, for example, 2 seconds, the total time Dn of the energization off time can be a time longer than 0.5 seconds, for example, 1 second or more.

With the above configuration, when the temperature of the medium is maintained at the set temperature, the temperatures of the heater pipes 815, 816, and 817 can be maintained at a target temperature higher than the set temperature of the medium or a temperature close to the target temperature, and the heater pipe can be maintained. The temperatures of 815, 816 and 817 can be set to the optimum temperature.

Further, the temperature control unit 52 for the heater pipe can set the total time Dn of the energization off time in which the energization off time of the control cycle is 10% or more of the proportional cycle to half or more of the proportional cycle. For example, assuming that the proportional cycle T is 1 second, when the energization off time is less than 10% of the proportional cycle T, that is, when the energization off time is less than 0.1 second, the temperature of the heater pipes 815, 816, and 817 can be controlled. It is too short to obtain the effect of lowering the temperature of the heater pipes 815, 816 and 817. The energization off time corresponding to 10% of the proportional period T is the minimum energization off time dm in the equation (3).

Therefore, by setting the total time Dn of the energization off time, which is 10% or more of the proportional cycle, to half or more of the proportional cycle, the temperature of the heater pipes 815, 816, and 817 can be surely set to the target temperature or the target temperature. It can be maintained at a temperature close to the target temperature.

The temperature control unit 52 for the heater pipe has a function as an output unit, and the energization off time of the control cycle is 10% or more of the proportional cycle. The total time Dn of the energization off time is less than half of the proportional cycle. If so, a warning can be output. The output of the warning may be voice, characters, figures, etc. may be displayed, and the indicator lamp may be turned on or blinked.

The energization off time is 10% or more of the proportional cycle. When the total energization off time Dn is less than half of the proportional cycle, the temperature control unit 52 for the heater pipe determines the temperature of the heater pipes 815, 816, and 817. It is considered that the energization off time is adjusted to an extremely short time or continuous energization is performed in order to bring the temperature close to the target temperature. In such a state, the heating by the heater pipes 815, 816, and 817 is not sufficient, and there is a possibility that stable temperature control cannot be performed. Therefore, by outputting a warning, it is possible to notify that the heating control by the heater pipes 815, 816, and 817 is hindered.

As described above, by setting the total time Dn of the energization off time of the control cycle to one half or more of the proportional cycle, even if the temperature of the medium is being raised toward the set temperature (during heating control). The heater temperature follows the temperature of the medium even when the temperature is maintained at the set temperature (when stable).

That is, the temperature control unit 52 for the heater pipe can control the temperature of the heater pipes 815, 816, and 817 based on the set temperature of the medium. Utilizing the fact that the temperature of the heater pipes 815, 816, 817 changes at a temperature higher than the temperature of the medium, for example, the temperature of the heater pipes 815, 816, 817 is higher than the set temperature of the medium by a required temperature. The total time Dn of the energization off time of the control cycle is adjusted so as to be the temperature. Thereby, the temperature of the heater pipes 815, 816, and 817 can be set to the optimum temperature according to the set temperature of the medium.

FIG. 10 is a schematic diagram showing a first example of a temperature control method using the mold temperature controller 100 of the present embodiment. In FIG. 10, the vertical axis represents temperature and the horizontal axis represents time. The period from time 0 to time ts is during heating control (during temperature rise), and after time ts, it indicates stable time. At the time of heating control, the medium temperature control unit 53 heats the medium from the heating start temperature (for example, 20 ° C.) to the set temperature (for example, 180 ° C.) by using the continuous energization mode. At this time, the heater temperature rises following the temperature of the medium.

When the temperature of the medium reaches the set temperature at the time ts, the medium temperature control unit 53 adjusts the energization off time for each proportional cycle so that the temperature of the medium maintains the set temperature by using the on / off energization mode. After the time ts, the cooling solenoid valve 23 and the cooling water solenoid valve 25 are opened for a required time at a required timing to cool the medium.

The temperature control unit 52 for the heater pipe can control the heater temperature based on the set temperature of the medium by setting the total time Dn of the energization off time of the control cycle to one half or more of the proportional cycle. In the example of FIG. 10, for example, the heater temperature when the flow rate of the medium is 30 l / min is shown. When the flow rate of the medium reaches the minimum flow rate, the heater temperature rises toward the upper limit of the heater temperature, and when the flow rate of the medium reaches the maximum flow rate, the heater temperature decreases toward the lower limit of the heater temperature.

In the heater pipe temperature control unit 52, the heater temperature is equal to or higher than the lower limit of the heater temperature (lower limit temperature), which is higher than the set temperature of the medium by the first temperature T1, and the heater temperature is higher by the second temperature T2 than the set temperature. The total time Dn of the energization off time of the control cycle can be adjusted so as to be equal to or less than the upper limit value (upper limit temperature).

As a result, the heater temperature can be set to a temperature between the lower limit of the heater temperature and the upper limit of the heater temperature. For example, by setting the upper limit of the heater temperature to a temperature lower than a temperature that can affect the life of the heater pipes 815, 816, 817 (for example, 400 ° C.), the expectation of the heater pipes 815, 816, 817 is set. It is possible to prevent the life from being shortened. In addition, by setting the lower limit of the heater temperature to a temperature higher than the temperature that can affect the temperature rise time to the set temperature of the medium, it is possible to prevent the temperature rise time of the medium from becoming longer than the expected time. can.

For example, the first temperature T1 can be 50 ° C. and the second temperature T2 can be 120 ° C. When the first temperature T1 is less than 50 ° C., the temperature rise time of the medium becomes longer than the expected time. Further, when the second temperature T2 is set to a temperature higher than 120 ° C., the expected life of the heater pipes 815, 816, and 817 is shortened. With the above configuration, it is possible to prevent the expected life of the heater pipes 815, 816, and 817 from being shortened and the temperature rise time of the medium from being longer than the expected time, regardless of the set temperature of the medium.

FIG. 11 is a schematic diagram showing the relationship between the medium set temperature and the total time Dn of the energization off time. In FIG. 11, the vertical axis represents temperature and the horizontal axis represents time. As shown in FIG. 11, when the set temperature of the medium is 180 ° C. and the total time Dn of the energization off time of the control cycle is set to 0.5 seconds, the set temperature of the medium is 200 ° C. and 250 ° C. If the temperature rises as shown above, the temperature of the heater pipes 815, 816, and 817 may also rise and exceed the upper limit of the heater temperature. Therefore, the total time Dn of the energization off time is longer than 0.5 seconds ( For example, the temperature of the heater pipes 815, 816, and 817 can be set to be equal to or lower than the upper limit of the heater temperature by adjusting the temperature to 0.6 seconds, 0.7 seconds, 1.0 seconds, and the like.

As described above, the temperature control unit 52 for the heater pipe can set the total time Dn of the energization off time of the control cycle to one half or more of the proportional cycle T according to the set temperature of the medium. Specifically, as the set temperature of the medium increases, the total time Dn of the energization off time can be adjusted to be longer.

With the above configuration, the temperature of the heater pipes 815, 816, 817 can be maintained at a target temperature higher than the set temperature of the medium or a temperature close to the target temperature, depending on the set temperature of the medium, and the heater pipes 815, 816 can be maintained. , 817 can be set to the optimum temperature.

Next, the operation mode of the heater device 80 during heating (during temperature rise) will be described.

FIG. 12 is a schematic diagram showing an example of changes in the temperature of the medium. In FIG. 12, the vertical axis represents temperature and the horizontal axis represents time. In FIG. 12, the chart (dashed line) indicated by reference numeral A uses a continuous energization mode while the medium is heated from the temperature before the start of heating (for example, 20 ° C.) to the set temperature (180 ° C. in the example of FIG. 12). , The case where the on / off energization mode is used after the temperature of the medium reaches the set temperature is shown. On the other hand, the chart (solid line) indicated by reference numeral B uses a continuous energization mode while the medium is heated from the temperature before the start of heating (for example, 20 ° C.) to a predetermined temperature (120 ° C. in the example of FIG. 12), and then. Indicates the case where the on / off energization mode is used.

As shown in FIG. 12, in the chart indicated by reference numeral B, the time required for the temperature of the medium to reach the set temperature is ts1, and in the chart indicated by reference numeral A, the time required for the temperature of the medium to reach the set temperature. Is ts2, and ts1 = ts2 + Δts. The time difference Δts changes according to a predetermined temperature, and is, for example, about 5 seconds to 10 seconds. That is, when the predetermined temperature is high, the time difference Δts becomes small, and when the predetermined temperature is low, the time difference Δts becomes large.

In applications where the temperature rise time for raising the temperature of the medium to the set temperature is desired to be as short as possible (for example, when the time difference Δts is acceptable), the medium is raised from the temperature before the start of heating to the set temperature as indicated by reference numeral A. The continuous energization mode can be used during heating, and the on / off energization mode can be used after the temperature of the medium reaches the set temperature. Further, in an application in which the temperature of the medium is raised to a set temperature with a margin, not only the operation mode indicated by reference numeral A but also the temperature before starting heating of the medium is set to a predetermined temperature as indicated by reference numeral B. A continuous energization mode can be used while the temperature is raised to, and then an on / off energization mode can be used.

FIG. 13 is a schematic view showing a second example of the temperature control method by the mold temperature controller 100 of the present embodiment. In FIG. 13, the vertical axis represents temperature and the horizontal axis represents time. From time 0 to time ts is the heating control time (during temperature rise) to raise the temperature of the medium to the set temperature, and after time ts, the stable time is shown. In the example of FIG. 13, the set temperature of the medium is higher than that of the example of FIG. 10 (for example, 250 ° C.).

The medium temperature control unit 53 can shift to the on / off energization mode when the heater temperature rises to a predetermined temperature in the continuous energization mode. In the example of FIG. 13, the medium temperature control unit 53 shifts from the continuous energization mode to the on / off energization mode at the time t1 when the heater temperature reaches a predetermined temperature (the time when the temperature rise time to the set temperature of the medium is shorter than ts). is doing.

As shown in FIG. 13, since the heater temperature changes at a temperature higher than the temperature of the medium, when the set temperature of the medium is relatively high (for example, 250 ° C.), the heater temperature also becomes higher and the time point is reached. If the continuous energization mode is continued after t1, the heater temperature may exceed the heater allowable temperature (heater temperature upper limit value).

Therefore, when a predetermined temperature (for example, the target temperature of the heater pipes 815, 816, 817 or the lower limit temperature may be used) is provided and the temperature of the heater pipes 815, 816, 817 is raised to the predetermined temperature, the continuous energization mode is started. By shifting to the on / off energization mode, it is possible to prevent overheating of the heater pipes 815, 816, and 817 while shortening the temperature rising time to the set temperature of the medium. The predetermined temperature can be appropriately set according to the set temperature of the medium, the allowable temperature of the heater, and the like.

Next, the flow rate of the medium is estimated based on the medium temperature on the upstream side of the heater pipes 815, 816 and 817 and the medium temperature on the downstream side of the heater pipes 815, 816 and 817, and the heater pipes 815 and 816 are estimated based on the estimated flow rate. A method of controlling the temperature of 817 will be described.

FIG. 14 is a schematic diagram showing the relationship between the flow rate and the medium temperature difference between the inlet and outlet of the heater device 80. In FIG. 14, the vertical axis shows the temperature and the horizontal axis shows the flow rate. The chart shown in FIG. 14 shows a case where the set temperature of the medium is 180 ° C. and the total time Dn of the energization off time of the control cycle is 0.5 seconds.

In the circulation path of the medium including the flow path in the mold 200, the place where the temperature gradient is remarkable is between the inlet and the outlet of the mold 200, and the upstream side and the downstream side of the heater pipes 815, 816, 817. Therefore, the medium temperature on the upstream side of the heater pipes 815, 816 and 817 corresponds to the outlet temperature (return medium side) of the mold 200, and the medium temperature on the downstream side of the heater pipes 815, 816 and 817 is. It corresponds to the inlet temperature (feeding side) of the mold 200. As shown in FIG. 14, when the flow rate of the medium decreases, the temperature of the medium heat-exchanged by the mold 200 increases, so that the temperature gradient between the inlet and the outlet of the mold 200 increases, and the temperature sensor 71 , 72 increases the temperature difference detected. Further, when the flow rate of the medium increases, the temperature of the medium heat exchanged by the mold 200 becomes low, so that the temperature gradient between the inlet and the outlet of the mold 200 becomes small, and the temperature sensors 71 and 72 detect it. The temperature difference becomes smaller.

FIG. 15 is a schematic diagram showing the relationship between the flow rate and the heater temperature. In FIG. 15, the vertical axis represents temperature and the horizontal axis represents flow rate. The chart shown in FIG. 15 shows a case where the set temperature of the medium is 180 ° C. and the total time Dn of the energization off time of the control cycle is 0.5 seconds.

As shown in FIG. 15, when the flow rate of the medium is low, the amount of heat for heating the medium may be small, so that heat exchange is poor and the heater temperature is high. Further, when the flow rate of the medium is increased, a large amount of heat is required to heat the medium, heat exchange is improved, and the heater temperature rise is suppressed.

FIG. 16 is a schematic diagram showing the relationship between the medium temperature difference between the inlet and the outlet of the heater device 80 and the heater temperature. In FIG. 16, the vertical axis represents temperature and the horizontal axis represents flow rate. The chart shown in FIG. 16 shows a case where the set temperature of the medium is 180 ° C. and the total time Dn of the energization off time of the control cycle is 0.5 seconds. The chart shown in FIG. 16 is a rewrite of the charts shown in FIGS. 14 and 15.

As shown in FIG. 16, when the temperature difference between the medium temperature on the downstream side of the heater pipes 815, 816, and 817 and the medium temperature on the upstream side is relatively large, the flow rate of the medium is small and the heater temperature may rise. I understand. Further, it can be seen that when the temperature difference between the medium temperature on the downstream side and the medium temperature on the upstream side of the heater pipes 815, 816, and 817 is relatively small, the flow rate of the medium is large and the heater temperature is relatively low.

FIG. 17 is a schematic diagram showing the relationship between the medium temperature difference between the inlet and the outlet of the heater device 80 and the total time Dn of the energization off time. In FIG. 17, the vertical axis represents temperature and the horizontal axis represents time. As shown in FIG. 17, when the temperature difference between the medium temperature on the downstream side of the heater pipes 815, 816 and 817 and the medium temperature on the upstream side is relatively large, the flow rate of the medium is small and the heater pipes 815, 816 and 817 are used. Since the temperature of the power rises, the total time of energization off time can be lengthened. Further, when the temperature difference between the medium temperature on the downstream side of the heater pipes 815, 816 and 817 and the medium temperature on the upstream side is relatively small, the flow rate of the medium is large and the temperature of the heater pipes 815, 816 and 817 is relatively small. Since it becomes low, the total time of energization off time can be shortened. Thereby, the flow rate of the medium can be estimated from the medium temperature difference, and the temperature of the heater pipes 815, 816, and 817 can be surely maintained at the target temperature or a temperature close to the target temperature.

FIG. 18 is a flowchart showing an example of a processing procedure of the temperature control method of the mold temperature controller 100 of the present embodiment. Hereinafter, for convenience, the temperature control unit 52 for the heater pipe and the medium temperature control unit 53 will be collectively described as the main body as the temperature control unit. The temperature control unit starts heating the medium in the continuous energization mode (S11), and determines whether or not the heater temperature has reached a predetermined temperature (S12). When the heater temperature has not reached the predetermined temperature (NO in S12), the temperature control unit determines whether or not the temperature of the medium has reached the set temperature (S13).

When the temperature of the medium has not reached the set temperature (NO in S13), the temperature control unit continues the processing after step S12, and when the temperature of the medium reaches the set temperature (YES in S13), the step described later. The process of S14 is performed. When the heater temperature reaches a predetermined temperature (YES in S12), the temperature control unit sets the total time of the energization off time of the control cycle to a predetermined value (S14). For example, when the proportional cycle T is 1 second, the number of cycles is 15, the set temperature of the medium is 180 ° C., and the flow rate of the medium is the minimum flow rate, the total time Dn of the energization off time can be 0.5 seconds.

The temperature control unit shifts from the continuous energization mode to the on / off energization mode (S15), and determines whether or not the temperature difference between the heater temperature and the temperature of the medium is within a predetermined range (S16). The predetermined range can be, for example, a first temperature T1 or more and a second temperature T2 or less. When the temperature difference is not within the predetermined range (NO in S16), the temperature control unit adjusts the total time of the energization off time (S17), and performs the process of step S18 described later. For example, when the temperature difference exceeds the second temperature T2, the total energization off time is lengthened.

When the temperature difference between the heater temperature and the temperature of the medium is within a predetermined range (YES in S16), the temperature control unit determines whether or not the temperature of the medium has reached the set temperature (S18). If the temperature of the medium has not reached the set temperature (NO in S18), the temperature control unit continues the processing after step S16, and if the temperature of the medium reaches the set temperature (YES in S18), the control ends. It is determined whether or not to do so (S19). If the control is not terminated (NO in S19), the temperature control unit continues the processing after step S16, and if the control is terminated (YES in S19), the processing is terminated.

According to this embodiment, it is possible to prevent problems due to scale adhesion to the heater surface. In addition, even when the heater protection interlock does not work (for example, dry heating, deadline without convection of the medium, etc.), the heater surface temperature does not exceed the upper limit temperature, which prevents damage to the heater and shortens its life. It can be prevented from becoming.

In the above-described embodiment, water can be used as the medium, but oil can also be used instead of water.

In the above-described embodiment, the mold temperature controller has been described as an example of the temperature control device, but the temperature control device is not limited to the mold temperature controller, and any device provided with a heater device can be used. The present embodiment can be applied.

The temperature control device of the present embodiment is a temperature control device that controls the temperature of the medium circulated to the object through the pipeline, and is attached to a heater pipe provided on the outer periphery of the flow path pipe through which the medium flows. Adjust the total time of the energization off time for each predetermined cycle or the energization off time for a period of multiple times of the predetermined cycle with the medium temperature control unit that controls the temperature of the medium by repeatedly turning on / off the energization. It is provided with a temperature control unit for a heater pipe that controls the temperature of the heater pipe.

The temperature control method of the present embodiment is a temperature control method for controlling the temperature of a medium circulated to an object through a pipeline, and is applied to a heater pipe provided on the outer periphery of a flow path pipe through which the medium flows. The temperature of the medium is controlled by repeatedly turning on / off the energization, and the temperature of the heater pipe is adjusted by adjusting the energization off time for each predetermined cycle or the total energization off time for a period of multiple times of the predetermined cycle. To control.

The medium temperature control unit repeatedly turns on / off the energization of the heater pipe provided on the outer periphery of the flow path tube through which the medium flows (for example, at a predetermined cycle) to control the temperature of the medium. The heater pipe has a structure in which a heating element such as a nichrome wire is wrapped with a metal pipe via an insulator, and is also called a sheathed heater. Since the heater pipe is provided on the outer periphery of the flow path pipe, the medium does not touch the heater pipe and the scale does not adhere to the surface of the heater pipe. This makes it possible to prevent a decrease in the heat transfer coefficient of the heater.

The predetermined cycle is also referred to as a proportional cycle. The predetermined cycle can be, for example, 1 second, 2 seconds, or the like. The medium temperature control unit adjusts so that when the temperature of the medium becomes higher than the set temperature, the cooling medium energization on time, which is the time for turning on the cooling medium in a predetermined cycle of the cooling process, becomes longer (for example, 5 to 8 seconds). The temperature of the medium is controlled to be lowered. Further, the medium temperature control unit adjusts the energization off time in a predetermined cycle of the heating step to be short (for example, from 0.1 second to 0.05 second) when the temperature of the medium becomes lower than the set temperature. Control to raise the temperature. The energization off time can be adjusted at predetermined intervals.

The temperature control unit for the heater pipe controls the temperature of the heater pipe by adjusting the energization off time in each predetermined cycle or the total energization off time in a period over a plurality of predetermined cycles. A period spanning multiple times of a predetermined cycle is also referred to as a control cycle. That is, assuming that the predetermined cycle is T and the number of times is n, the control cycle is n × T. The number of times n is also referred to as the number of cycles. The number of cycles can be, for example, 15, but is not limited to this, and may be 10 cycles, 20 cycles, or 30 cycles.

Assuming that the energization off times of cycles 1, 2, ..., N are d1, d2, ..., Dn, respectively, the total energization off time Dn can be expressed by Dn = d1 + d2 + ... + dn. When the temperature of the heater pipe becomes high, the temperature control unit can bring the temperature of the heater pipe closer to the target temperature by adjusting so that the total time Dn becomes longer. As a result, it is possible to prevent the temperature of the heater pipe from exceeding the upper limit temperature and prevent the heater pipe from overheating.

In the temperature control device of the present embodiment, the temperature control unit for the heater pipe controls the temperature of the heater pipe by adjusting the total time of the energization off time in a period over a plurality of proportional cycles of PID control. ..

The temperature control unit for the heater pipe can control the temperature of the heater pipe by adjusting the total time of the energization off time in a period of a plurality of proportional cycles of PID control (Proportional-Integral-Differential Controller). The PID control is the control of the temperature of the medium by the medium temperature control unit, and controls the energization off time as a linear function of the deviation between the actual temperature of the medium and the target temperature. As a result, it is possible to prevent the temperature of the heater pipe from exceeding the upper limit temperature and prevent the heater pipe from overheating.

In the temperature control device of the present embodiment, the medium temperature control unit has a first control mode in which the energization off time at each predetermined cycle is set to 0 to continuously energize the heater pipe, and energization of the heater pipe. A second control mode is used in which the on / off of is repeated in the predetermined cycle.

The first control mode is a continuous energization mode in which the energization off time for each predetermined cycle is set to 0 and the heater pipe is continuously energized. The second control mode is an on / off energization mode in which the energization of the heater pipe is repeatedly turned on / off at a predetermined cycle. In addition, in this specification, even when the energization time becomes 0 in one or a plurality of proportional cycles in a control cycle, it is assumed to be an on / off energization mode. When raising the temperature of the medium from the heating start temperature (for example, 20 ° C.) to the set temperature (for example, 180 ° C.), the medium temperature control unit can use the first control mode. Further, when the temperature of the medium is maintained at the set temperature, the medium temperature control unit can use the second control mode. Even when the temperature of the medium is raised from the heating start temperature to the set temperature, the medium temperature control unit can use the second control mode.

In the temperature control device of the present embodiment, the medium temperature control unit shifts to the second control mode when the temperature of the heater pipe rises to a predetermined temperature in the first control mode.

When the temperature of the heater pipe rises to a predetermined temperature in the first control mode, the medium temperature control unit can shift to the second control mode. When raising the temperature of the medium from the heating start temperature, the medium temperature control unit uses the first control mode, so that the temperature rise rate of the medium is faster than when the second control mode is used, for example, the set temperature. It is possible to shorten the time to reach. On the other hand, since the temperature of the heater pipe changes at a temperature higher than the temperature of the medium, when the set temperature of the medium is relatively high (for example, 250 ° C.), the temperature of the heater pipe also becomes higher.

Therefore, a predetermined temperature (for example, the target temperature of the heater pipe or the lower limit temperature may be used) is provided, and when the temperature of the heater pipe rises to the predetermined temperature, the first control mode is shifted to the second control mode. It is possible to prevent the heater pipe from overheating while shortening the temperature rise time to the set temperature of the medium.

In the temperature control device of the present embodiment, the temperature control unit for the heater pipe controls the temperature of the heater pipe based on the set temperature of the medium.

The temperature control unit for the heater pipe can control the temperature of the heater pipe based on the set temperature of the medium. Utilizing the fact that the temperature of the heater pipe changes at a temperature higher than the temperature of the medium, for example, the total energization off time is set so that the temperature of the heater pipe is higher than the set temperature of the medium by the required temperature. Adjust the time. Thereby, the temperature of the heater pipe can be set to the optimum temperature according to the set temperature of the medium.

In the temperature control device of the present embodiment, the temperature control unit for the heater pipe has the temperature of the heater pipe equal to or higher than the lower limit temperature which is higher than the set temperature of the medium by the first temperature and is higher than the set temperature. The energization off time or the total time of the energization off time for each predetermined cycle is adjusted so as to be equal to or lower than the upper limit temperature which is higher by the second temperature.

The temperature control unit for the heater pipe has a predetermined cycle so that the temperature of the heater pipe is equal to or higher than the lower limit temperature which is higher than the set temperature of the medium by the first temperature and is equal to or lower than the upper limit temperature which is higher than the set temperature by the second temperature. Adjust the energization off time or the total energization off time for each. As a result, the temperature of the heater pipe can be set to a temperature between the lower limit temperature and the upper limit temperature. For example, by setting the upper limit temperature to a temperature lower than a temperature that can affect the life of the heater pipe, it is possible to prevent the expected life of the heater pipe from being shortened. Further, by setting the lower limit temperature to a temperature higher than the temperature that can affect the temperature rise time to the set temperature of the medium, it is possible to prevent the temperature rise time of the medium from becoming longer than the expected time.

In the temperature control device of the present embodiment, the first temperature is 50 ° C. and the second temperature is 120 ° C.

The first temperature is 50 ° C. and the second temperature is 120 ° C. When the first temperature is less than 50 ° C., the temperature rise time of the medium becomes longer than the expected time. Further, when the second temperature is set to a temperature higher than 120 ° C., the expected life of the heater pipe is shortened. With the above configuration, it is possible to prevent the expected life of the heater pipe from being shortened and the temperature rise time of the medium being longer than the expected time depending on the set temperature of the medium.

In the temperature control device of the present embodiment, the temperature control unit for the heater pipe sets the total time of the energization off time during the predetermined number of times of the predetermined cycle to one half or more of the predetermined cycle.

The temperature control unit for the heater pipe can set the total time of the energization off time for a predetermined number of times in a predetermined cycle to one half or more of the predetermined cycle. Assuming that the predetermined cycle (proportional cycle) is T and the predetermined number of times (number of cycles) is n, the total time Dn of the energization off time of the control cycle (n × T) can be Dn ≧ T / 2. For example, when the proportional cycle T is 1 second and the number of cycles is 15 seconds, the total time Dn of the energization off time can be 0.5 seconds or more. Even when the number of cycles is, for example, 10 or 20, the total time Dn of the energization off time can be 0.5 seconds or more. Further, when the proportional period T is, for example, 2 seconds, the total time Dn of the energization off time can be a time longer than 0.5 seconds, for example, 1 second or more.

With the above configuration, when the temperature of the medium is maintained at the set temperature, the temperature of the heater pipe can be maintained at a target temperature higher than the set temperature of the medium or a temperature close to the target temperature, and the temperature of the heater pipe is optimal. Can be temperature.

In the temperature control device of the present embodiment, the temperature control unit for the heater pipe sets the total energization off time during which the energization off time is 10% or more of the predetermined cycle for a predetermined number of times in the predetermined cycle. It shall be more than half of the predetermined cycle.

The temperature control unit for the heater pipe can set the total time of the energization off time, which is 10% or more of the energization off time of the predetermined number of times of the predetermined cycle, to be half or more of the predetermined cycle. For example, if the predetermined cycle (proportional cycle) T is 1 second, the energization off time is less than 10% of the predetermined cycle, that is, the energization off time is less than 0.1 second, which is too short to control the temperature of the heater pipe. The effect of lowering the temperature of the heater pipe cannot be obtained.

Therefore, by setting the total energization off time, which is 10% or more of the predetermined cycle, to half or more of the predetermined cycle, the temperature of the heater pipe is surely set to the target temperature or a temperature close to the target temperature. Can be maintained.

In the temperature control device of the present embodiment, the temperature control unit for the heater pipe has a total energization off time in which the energization off time is 10% or more of the predetermined cycle for a predetermined number of times in the predetermined cycle. If it is less than half of the predetermined cycle, an output unit for outputting a warning is provided.

The output unit outputs a warning when the total energization off time for a period over a predetermined number of times in a predetermined cycle is 10% or more of the predetermined cycle and the total energization off time is less than half of the predetermined cycle. When the energization off time is 10% or more of the predetermined cycle and the total energization off time is less than half of the predetermined cycle, the temperature control unit for the heater pipe brings the temperature of the heater pipe to a temperature close to the target temperature. Therefore, it is considered that the energization off time is adjusted to an extremely short time, or continuous energization is performed. In such a state, the heating by the heater pipe is not sufficient, and there is a possibility that stable temperature control cannot be performed. Therefore, by outputting a warning, it is possible to notify that the heating control by the heater pipe is hindered.

The temperature control device of the present embodiment includes a temperature sensor that detects the medium temperature on the upstream side of the heater pipe and the medium temperature on the downstream side of the heater pipe, and the temperature control unit for the heater pipe is on the downstream side. The energization off time or the total time of the energization off time for each predetermined cycle is adjusted based on the temperature difference between the medium temperature and the medium temperature on the upstream side.

The temperature sensor detects the medium temperature on the upstream side of the heater pipe and the medium temperature on the downstream side of the heater pipe. The temperature control unit adjusts the energization off time or the total energization off time for each predetermined cycle based on the temperature difference between the medium temperature on the downstream side and the medium temperature on the upstream side.

In the circulation path of the medium including the flow path in the mold, the place where the temperature gradient is remarkable is between the inlet and the outlet of the mold and between the upstream side and the downstream side of the heater pipe. The medium temperature on the upstream side corresponds to the outlet temperature of the mold (return side), and the medium temperature on the downstream side of the heater pipe corresponds to the inlet temperature of the mold (feeding side). When the flow rate of the medium decreases, the temperature of the medium heat-exchanged by the mold becomes high, so that the temperature gradient between the inlet and the outlet of the mold becomes large, and the temperature difference detected by the temperature sensor becomes large. Further, when the flow rate of the medium increases, the temperature of the medium heat exchanged by the mold becomes low, so that the temperature gradient between the inlet and the outlet of the mold becomes small, and the temperature difference detected by the temperature sensor becomes small. .. On the other hand, when the flow rate of the medium is small, the amount of heat for heating the medium may be small, so that the temperature of the heater pipe becomes high. Further, when the flow rate of the medium is increased, a large amount of heat is required to heat the medium, and the temperature rise of the heater pipe is suppressed.

Therefore, when the temperature difference between the medium temperature on the downstream side and the medium temperature on the upstream side of the heater pipe is relatively large, the flow rate of the medium is small and the temperature of the heater pipe rises. Increase the total power-off time. Further, when the temperature difference between the medium temperature on the downstream side and the medium temperature on the upstream side of the heater pipe is relatively small, the flow rate of the medium is large and the temperature of the heater pipe is relatively low. Shorten the total time or energization off time. Thereby, the temperature of the heater pipe can be reliably maintained at the target temperature or a temperature close to the target temperature depending on the flow rate of the medium.

The temperature control device of the present embodiment includes a heating unit having a flow path pipe through which the medium flows and a heater pipe wound a plurality of times around the outer circumference of the flow path pipe, and the outer diameter of the heater pipe is set. It is smaller than the pitch of adjacent heater pipes on the outer circumference of the flow path pipe.

The heating unit has a flow path pipe through which the medium flows and a heater pipe wound around the outer circumference of the flow path pipe a plurality of times. The outer diameter of the heater pipe is smaller than the pitch of the adjacent heater pipes on the outer circumference of the flow path pipe. That is, the heater pipes are not in close contact with each other, and the heater pipes adjacent to each other on the outer circumference of the flow path pipe are wound around the outer circumference of the flow path pipe with a gap between them. By providing a gap, overheating of the heater pipe can be prevented.

In the temperature control device of this embodiment, the outer diameter of the heater pipe is 5 mm or less.

The outer diameter of the heater pipe is 5 mm or less. As a result, the number of times the heater pipe wound around the outer circumference of the flow path pipe having a predetermined length can be relatively increased, and the contact area of the heater pipe on the outer circumference of the flow path pipe can be increased. The heat of the heater pipe can be efficiently transferred to the medium through the pipe.

In the temperature control device of the present embodiment, the power density of the heating unit is 10 W or less per square cm.

The power density of the heating unit is 10 W or less per square cm. The power density is the power load (W) per unit area (1 square cm) of the heater pipe. For example, if the outer diameter of the heater pipe is φ, the effective length of the wound heater pipe is L, and the electric power is W, the power density can be expressed as W / (φ × π × L). This makes it possible to prevent the heater pipe from overheating.

In the temperature control device of the present embodiment, the heating unit includes a first flow path pipe, a second flow path pipe, a third flow path pipe, and one end of the first flow path pipe through which the medium flows. The first communication pipe that communicates the inflow port provided in the above, the other end of the first flow path pipe, and one end of the second flow path pipe, and the other end of the second flow path pipe. A second communication pipe that communicates with one end of the third flow path pipe, an outlet provided at the other end of the third flow path pipe, and winding around the outer periphery of the first flow path pipe. One or more first heater pipes, one or more second heater pipes wound around the outer circumference of the second flow path pipe, and one or more second heater pipes wound around the outer circumference of the third flow path pipe. The first heater pipe, the second heater pipe, and the third heater pipe are provided with one or more third heater pipes, and a different one of the three-phase ACs is applied to each of the first heater pipes, the second heater pipe, and the third heater pipe. There is.

The heating unit includes a first flow path tube, a second flow path tube, and a third flow path tube through which the medium flows. An inflow port is provided at one end of the first flow path pipe, and the other end of the first flow path pipe and one end of the second flow path pipe are communicated with each other by a first communication pipe, and the second flow path is provided. The other end of the pipe and one end of the third flow path pipe are communicated with each other by a second communication pipe, and an outlet is provided at the other end of the third flow path pipe. One or a plurality of first heater pipes are wound around the outer circumference of the first flow path pipe, and one or a plurality of second heater pipes are wound around the outer circumference of the second flow path pipe. One or a plurality of third heater pipes are wound around the outer circumference of the flow path pipe. A different one of the three-phase alternating currents is applied to each of the first heater pipe, the second heater pipe, and the third heater pipe. The medium is heated as it flows through the first channel tube, the second channel tube and the third channel tube.

Thereby, each phase of the three-phase AC can be associated with any one of the three sets of heater pipes to apply the power supply, and the three-phase AC power supply can be supported.

In the temperature control device of the present embodiment, a plurality of the heating units can be connected.

A plurality of heating units can be connected. As a result, the temperature of the medium can be adjusted to the set temperature simply by connecting the required number of heating units according to the size of the heating capacity, and since the heating units are common, the types of parts can be changed according to the heating capacity. The cost can be reduced without increasing.

It should be noted that at least a part of the above-described embodiments can be arbitrarily combined.

11, 12, 14 Pipeline 13 Cooling pipe line 15 Drainage pipe line 16 Bypass line line 21 Transmission valve 22 Return medium valve 23 Cooling electromagnetic valve 24 Drainage electromagnetic valve 25 Cooling water electromagnetic valve 31 Pump 40 Heat exchanger 50 Control unit 51 Valve open / close control unit 52 Heater pipe temperature control unit 53 Medium temperature control unit 71, 72, 73 Temperature sensor 80 Heater device 811, 812, 813 Flow pipe 815, 816, 817 Heater pipe 851 Inlet 841 Outlet 842, 852 Communication pipe 100 Mold temperature controller (temperature control device)
200 mold (object)

Claims (17)

A mold temperature control device that controls the temperature of a medium that circulates in a mold via a pipeline.
A medium temperature control unit that controls the temperature of the medium circulated in the mold by repeatedly turning on / off the energization of the heater pipe provided on the outer periphery of the flow path pipe through which the medium flows.
Mold temperature control provided with a heater pipe temperature control unit that controls the temperature of the heater pipe by adjusting the energization off time for each predetermined cycle or the total time of the energization off time for a period of a plurality of times of the predetermined cycle. Device. The temperature control unit for the heater pipe is
The mold temperature control device according to claim 1, wherein the temperature of the heater pipe is controlled by adjusting the total time of the energization off time in a period of a plurality of proportional cycles of PID control. The medium temperature control unit is
The first control mode in which the energization off time for each predetermined cycle is set to 0 and the heater pipe is continuously energized.
The mold temperature control device according to claim 1 or 2, which uses a second control mode in which the on / off of energization of the heater pipe is repeated in the predetermined cycle. The medium temperature control unit is
The mold temperature control device according to claim 3, wherein when the temperature of the heater pipe rises to a predetermined temperature in the first control mode, the process shifts to the second control mode. The temperature control unit for the heater pipe is
The mold temperature control device according to any one of claims 1 to 4, wherein the temperature of the heater pipe is controlled based on the set temperature of the medium circulated in the mold. The temperature control unit for the heater pipe is
The predetermined temperature of the heater pipe is equal to or higher than the lower limit temperature which is higher than the set temperature of the medium circulated in the mold by the first temperature, and is equal to or lower than the upper limit temperature which is higher than the set temperature by the second temperature. The mold temperature control device according to any one of claims 1 to 5, wherein the energization off time for each cycle or the total time of the energization off time is adjusted. The mold temperature control device according to claim 6, wherein the first temperature is 50 ° C. and the second temperature is 120 ° C. The temperature control unit for the heater pipe is
The mold temperature control device according to any one of claims 1 to 7, wherein the total time of the energization off time during a predetermined number of times of the predetermined cycle is halved or more of the predetermined cycle. The temperature control unit for the heater pipe is
Claims 1 to 8 wherein the total time of the energization off time during which the energization off time for a predetermined number of times of the predetermined cycle is 10% or more of the predetermined cycle is halved or more of the predetermined cycle. The mold temperature control device according to any one of the items. The temperature control unit for the heater pipe is
An output unit that outputs a warning when the total time of the energization off time is 10% or more of the predetermined cycle and the total time of the energization off time during the predetermined number of times of the predetermined cycle is less than half of the predetermined cycle. The mold temperature control device according to any one of claims 1 to 9. A temperature sensor for detecting the medium temperature on the upstream side of the heater pipe and the medium temperature on the downstream side of the heater pipe is provided.
The temperature control unit for the heater pipe is
Any one of claims 1 to 10 for adjusting the energization off time for each predetermined cycle or the total time of the energization off time based on the temperature difference between the medium temperature on the downstream side and the medium temperature on the upstream side. The mold temperature control device according to the section. The flow path tube through which the medium to be circulated in the mold flows, and
A heating unit having a heater pipe wound a plurality of times around the outer circumference of the flow path pipe is provided.
The mold temperature control device according to any one of claims 1 to 11, wherein the outer diameter of the heater pipe is smaller than the pitch of adjacent heater pipes on the outer circumference of the flow path pipe. The mold temperature control device according to claim 12, wherein the outer diameter of the heater pipe is 5 mm or less. The mold temperature control device according to claim 12 or 13, wherein the power density of the heating unit is 10 W or less per square cm. The heating unit is
A first flow path pipe, a second flow path pipe, and a third flow path pipe through which the medium to be circulated in the mold flows.
An inflow port provided at one end of the first flow path pipe and
A first communication pipe that communicates the other end of the first communication pipe and one end of the second communication pipe,
A second communication pipe that communicates the other end of the second communication pipe with one end of the third communication pipe,
The outlet provided at the other end of the third flow path pipe and
One or a plurality of first heater pipes wound around the outer circumference of the first flow path pipe, and
With one or more second heater pipes wound around the outer circumference of the second flow path pipe,
It is provided with one or a plurality of third heater pipes wound around the outer circumference of the third flow path pipe.
The invention according to any one of claims 12 to 14, wherein a different one phase of the three-phase alternating current is applied to each of the first heater pipe, the second heater pipe, and the third heater pipe. The mold temperature control device described. The mold temperature control device according to any one of claims 12 to 15, wherein a plurality of heating units can be connected to each other. It is a mold temperature control method that controls the temperature of the medium circulated in the mold through the pipeline.
By repeatedly turning on / off the energization of the heater pipe provided on the outer periphery of the flow path pipe through which the medium flows, the temperature of the medium circulated in the mold is controlled.
A mold temperature control method for controlling the temperature of the heater pipe by adjusting the energization off time for each predetermined cycle or the total energization off time for a period of a plurality of times of the predetermined cycle.

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