JP2016112772A - Method for controlling heating cylinder temperature - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for controlling heating cylinder temperature, which enables a heating cylinder to be stably cooled, materializes high energy efficiency, and enables the heating cylinder to early reach target temperature.SOLUTION: An injection device (1) is configured in such a way that a heating cylinder (2) comprises in each of zones thereof: a band heater (7); a heat-insulating cover (9); and cooling means (16, 19, 21). The cooling means is configured to supply cooling air which is cooled by a heat pump (27) to inside of the heat-insulating cover (9). In such an injection device (1), the zones are each controlled in temperature. In the injection device (1), when the target temperature (M) is set to each of the zones and temperature is controlled, the band heater (7) is always controlled by PWM control. The cooling means (16, 19, 21) operate only when temperature (25) of respective zone exceed determination temperature (H) which is higher than the target temperature (M) by predetermined deviation temperature, and supply cooling liquid.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature control method for controlling the temperature for each zone of a heating cylinder of an injection molding machine.

  As is well known in the art, an injection device of an injection molding machine includes a heating cylinder, a screw that can be driven in the rotation direction and the axial direction in the heating cylinder, and the like. A plurality of band heaters are wound around the outer periphery of the heating cylinder so that it can be heated. The heating cylinder or the screw has different operations depending on the respective parts in the axial direction, for example, the supply zone where the resin pellets of the material are supplied near the rear of the heating cylinder, the melting zone where the resin pellets are melted in the middle, The front side is divided like a kneading zone where the molten resin is kneaded and compressed. The plurality of band heaters wound around the heating cylinder are independently turned ON / OFF in each zone, and each zone is controlled to have a desired target temperature.

JP 2010-247458 A Japanese Patent Laid-Open No. 10-180827

  Since the heating cylinder heated to 200 to 300 ° C. releases a large amount of heat to the outside air, it must be heated by the band heater correspondingly, resulting in a large energy loss. Therefore, an injection device covered with a heat insulating cover having a heat retaining effect from above the band heater wound around the outer peripheral surface of the heating cylinder is also well known. In such an injection device, since the heat insulating cover suppresses the release of heat to the outside air, it is excellent in energy efficiency. By the way, in an injection molding machine, there is a case where it is desired to lower the set temperature of the heating cylinder by changing the color of the resin. When the temperature of the heating cylinder before the color change is higher than the set temperature, the heat cylinder is cooled by natural heat radiation or blown by a blower or the like to wait for the target temperature to be reached. However, if a heat insulating cover is provided on the heating cylinder, it takes a long time for cooling, so that the operation rate of the injection molding machine is lowered and the productivity of the molded product is deteriorated, resulting in an increase in cost. End up. Therefore, Patent Document 1 describes an injection apparatus including a heat insulating cover that solves such a problem. The heat insulating cover described in Patent Document 1 is composed of a breathable sheet that allows air to pass through the inner side in contact with the band heater, and an airtight sheet that does not allow air to pass through the exposed outer side. It is filled with insulation. And the compressed air for cooling can be supplied from the outside. Accordingly, when it is desired to lower the temperature of the heating cylinder due to the need for color change or the like, compressed air is supplied to the heat insulating cover. The compressed air is then diffused in the insulation and is supplied from the breathable sheet to the heating cylinder. As a result, the heating cylinder can be cooled in a short time, and the operating rate of the injection molding machine can be increased.

  Patent Document 2 describes an injection apparatus including a heating unit and a cooling unit. In the heating cylinder described in this document, a spiral groove having a substantially U-shaped cross section is formed on the outer peripheral surface thereof. A metal tube for flowing a heat medium such as air is embedded in the spiral groove. A band heater is wound thereon. Therefore, when the band heater is energized, the heating cylinder can be heated, and when the air is passed through the metal tube, the heating cylinder can be cooled.

  The heat insulating cover described in Patent Document 1 can improve the energy efficiency of the injection molding machine, and can cool the heating cylinder in a relatively short time even when the set temperature of the heating cylinder is changed by color change or the like. The operation rate is excellent and can be maintained high. The injection apparatus described in Patent Document 2 also includes a heating unit and a cooling unit, so that the degree of freedom of temperature control is high and excellent. However, with regard to cooling, there is no guarantee that it can be appropriately performed depending on conditions. The heating cylinder is divided into a plurality of zones from the front to the rear, and each zone is controlled to a predetermined temperature. For a specific zone, the amount of shear heat generated by the rotation of the screw even when the band heater is turned off. In some cases, only the cooling means must be operated. Therefore, in such a specific zone, only the cooling means is operated and cooled. However, when the room temperature is high, cooling by the cooling means described in Patent Document 2 is insufficient and the temperature control is performed. Is not stable.

  There seems to be a problem to consider other than the problem of cooling capacity. Specifically, neither the heat insulating cover described in Patent Document 1 nor the heating / cooling means described in Patent Document 2 has any particular problem in itself, but in the heating cylinder provided with these, how There is room for consideration as to whether temperature control should be performed. Therefore, a general heating cylinder provided with a band heater is considered as an example. In such a heating cylinder, when PID control is performed so as to achieve a desired target temperature M1, generally, the gain is reduced so as not to overshoot as in the graph of reference numeral 51 shown in FIG. I have control. This is because the target temperature M1 can be smoothly reached. However, when the gain is small, the time constant becomes large, and there is a disadvantage that the time for reaching the target temperature M1 is long as indicated by reference numeral 52. For example, if the gain is increased, the temperature rapidly increases. However, as shown in the graph of reference numeral 53, overshoot exceeds the target temperature M1, and it takes time to cool down, so that the target temperature M1 is eventually delayed as indicated by reference numeral 54. When a conventional heat insulating cover without a cooling means is covered, it takes time to cool down, so the time to reach the target temperature M1 is delayed. The heat insulating cover described in Patent Document 1 is not intended for temperature control to cool in such a case, but can be cooled by compressed air, so that the temperature of the heating cylinder exceeds the target temperature M1. It seems that it can be controlled to forcibly cool when it is shot. Similarly, the cooling means described in Patent Document 2 is likely to be controlled to be forcibly cooled during such an overshoot. However, there is a problem if the temperature is controlled simply using these cooling means. Specifically, it is a problem that energy efficiency is lowered. If the target temperature M1 is exceeded, cooling is performed by the cooling means, and if the temperature falls below the target temperature M1, heating is performed by the heating means, but it is possible to reach the desired target temperature M1 early, but frequent heating and cooling are performed. Repeatedly, energy loss occurs. If it does so, even if it provides the heat insulation cover, energy efficiency cannot be raised and it does not have the meaning which is heat-insulating. In the first place, the heater is controlled by PWM control that adjusts the duty ratio, which is the ratio of the energization time. If the temperature becomes stable in the vicinity of the target temperature M1, the duty ratio becomes stable. Then, the temperature control should be stable originally. However, if the cooling means operates in such a state, the forced decrease in temperature becomes a disturbance and the heater control is disturbed.

  An object of the present invention is to provide a heating cylinder temperature control method that solves the above-described problems. Specifically, a heating cylinder is easily desired for each zone without being affected by room temperature. The purpose of this invention is to provide such a heating cylinder temperature control method that can be adjusted to the temperature of the heating cylinder, and that is energy efficient, reaches the target temperature early, improves the operating rate, and stabilizes the temperature control. Yes.

  In order to achieve the object of the present invention, the present invention provides a band heater in which a heating cylinder is divided into a plurality of zones in the axial direction, and each zone is wound around the outer peripheral surface of the heating cylinder, The present invention is directed to an injection device including a heat insulating cover provided outside and a cooling means for supplying a cooling fluid from the outside into the heat insulating cover, and each zone is independently temperature-controlled. Is configured as a temperature control method. In such an injection device, when temperature control is performed according to the target temperature set for each zone, the band heater is controlled by PWM control, and the cooling means is configured such that the temperature of the zone is a predetermined deviation temperature from the target temperature. The cooling fluid is supplied by operating when the judgment temperature exceeds a high temperature, and the cooling fluid is composed of cooling air cooled by a heat pump.

Thus, in order to achieve the above object, the invention according to claim 1 is a band heater in which the heating cylinder is divided into a plurality of zones in the axial direction, and each zone is wound around the outer peripheral surface of the heating cylinder. An injection device comprising a heat insulating cover provided outside the band heater, and a cooling means for supplying a cooling fluid from the outside into the heat insulating cover, and the temperature of each zone is controlled independently. When the temperature control is performed according to the target temperature set for each zone, the band heater is controlled by PWM control, and the cooling means has a zone temperature higher than the target temperature by a predetermined deviation temperature. A cooling fluid is supplied by operating when a judgment temperature is exceeded, and the cooling fluid is composed of cooling air cooled by a heat pump. That is configured as a temperature control method of the heating cylinder.
According to a second aspect of the present invention, in the method according to the first aspect, the cooling fluid is obtained by cooling the air supplied from the flow amplifying device by the heat pump, and the flow amplifying device is arranged in the axial direction. Amplifying pipe having a predetermined length with a main pipe having a predetermined diameter passing therethrough and an air compressor for supplying compressed air to the amplifying pipe, and the amplifying pipe is connected to the main pipe from the side. A path is provided, and one end of the main pipe line is exposed to the outside air, and the other end is connected to the heat pump. When compressed air is supplied from the air compressor to the compressed air supply path, Temperature control of a heating cylinder, wherein air is sucked from the one end of the main pipe and air is supplied to the heat pump from the other end Configured as a law.
According to a third aspect of the present invention, in the method according to the first or second aspect, when the temperature of the zone exceeds the judgment temperature and the supply of the cooling fluid is started by the cooling means, the temperature of the zone becomes the target. The cooling fluid is supplied until the temperature drops to a temperature, and is configured as a temperature control method for a heating cylinder.
According to a fourth aspect of the present invention, in the method of the first aspect, when the temperature of the zone exceeds the determination temperature and supply of the cooling fluid is started by the cooling means, the temperature of the zone becomes the determination temperature. If it falls, it will be comprised as a temperature control method of the heating cylinder characterized by stopping the supply of the cooling fluid.

  In the present invention, the heating cylinder is divided into a plurality of zones in the axial direction, and each zone is wound on the outer peripheral surface of the heating cylinder, and a heat insulating cover provided outside the band heater, The present invention is directed to an injection device that includes a cooling fluid supply means for supplying a cooling fluid from the outside in the heat insulating cover, and in which the temperature of each zone is independently controlled. That is, it is intended for an injection device in which the release of heat to the outside is suppressed by a heat insulating cover. The present invention is a method for controlling the temperature of each zone independently in such an injection apparatus. When temperature control is performed according to a target temperature set for each zone, the band heater is controlled by PWM control. The cooling means operates when the temperature of the zone exceeds a determination temperature that is higher than the target temperature by a predetermined deviation temperature to supply the cooling fluid, and the cooling fluid is cooled air cooled by a heat pump. Consists of. That is, since the cooling fluid is composed of cooling air cooled by a heat pump, the heating cylinder can be stably cooled regardless of the room temperature. That is, it is possible to easily control the heating cylinder to a desired temperature. According to the present invention, when the target temperature is set for each zone and temperature control is performed, the band heater is controlled by PWM control. That is, the band heater is a subject of constant operation so as to achieve the target temperature, and can be smoothly controlled by PWM control. According to the present invention, the cooling supply means is configured to operate and supply the cooling fluid when the temperature of the zone exceeds the determination temperature that is higher than the target temperature by a predetermined deviation temperature. That is, the supply of the cooling fluid is limited only when the determination temperature is exceeded. However, the supply method is not limited, and simple ON / OFF control may be used. Since this invention is comprised in this way, a gain can be set large in control of a band heater. That is, the zone temperature may positively overshoot the target temperature. In the present invention, even if overshooting occurs, the temperature of the zone converges to a certain range because it can be quickly cooled by the cooling means when the determination temperature is exceeded. As a result, the zone temperature quickly reaches the target temperature, so that the operating rate is improved. Further, since the band heater is controlled by PWM control, when the temperature of the zone converges within a certain range, the temperature change becomes gradual, and it is not necessary to operate the cooling means that causes energy loss. As described above, the heat loss to the outside is also small due to the heat insulating cover. That is, the effect that energy efficiency is high is acquired.

  According to another invention, the cooling fluid is obtained by cooling the air supplied from the flow amplifying device by a heat pump, and the flow amplifying device has a predetermined length with a main pipe having a predetermined diameter penetrating in the axial direction. The amplifying tube is composed of an air compressor for supplying compressed air to the amplifying tube, the amplifying tube is provided with a compressed air supply passage communicating from the side to the main conduit, and one end of the main conduit is open to the outside air. The other end is exposed and connected to the heat pump, and when compressed air is supplied from the air compressor to the compressed air supply passage, air is sucked from one end of the main pipeline and the heat pump from the other end. Is configured to be supplied with air. Therefore, since the cooling air cooled by the flow rate being amplified by the flow rate amplifying device can be used, the cooling capacity is further increased. This facilitates temperature control of the heating cylinder.

It is front sectional drawing which shows the injection device which concerns on embodiment of this invention. It is a figure which shows the heating cylinder of the injection device which concerns on embodiment of this invention in a cross section perpendicular | vertical to an axis | shaft, The (a) (b) is a side cross section of the heating cylinder which concerns on 1st, 2nd embodiment, respectively. FIG. It is a front sectional view of an amplification tube of a flow rate amplification device concerning an embodiment of the invention. It is a graph explaining the temperature control method of the heating cylinder which concerns on the actual form of this invention, (a) (b) is a heating cylinder when the temperature control method which concerns on 1st, 2nd embodiment, respectively is implemented. It is a graph which shows the temperature change of. It is a graph which shows the temperature change of a heating cylinder, when the temperature control method of the conventional heating cylinder is implemented.

  The temperature control method according to the present embodiment targets the injection device 1 according to the present embodiment having a predetermined structure. The injection device 1 according to the present embodiment is also configured in the same manner as the conventional injection device, and is driven in the axial direction and the rotational direction in the heating cylinder 2 and the heating cylinder 2 as shown in FIG. The screw 3, the injection nozzle 5 provided at the tip of the heating cylinder 2, the hopper 6 provided behind the heating cylinder 2, and the like. The heating cylinder 2 is divided into a plurality of zones in the axial direction, and in this embodiment, four zones, and band heaters 7, 7,... Are wound around the outer periphery of the heating cylinder 2 in each zone.

  In the injection apparatus 1 according to the present embodiment, these band heaters 7, 7,... Are covered with heat insulating covers 9, 9,. As shown in FIG. 2A, the heat insulating cover 9 according to the present embodiment includes an outer sheet 11 that covers the outer side, and an inner sheet 12 that is located on the inner side and is in contact with the band heater 7. The heat insulating material 14 is filled between the outer sheet 11 and the inner sheet 12. The outer sheet 11 is a woven fabric made of glass fiber and is coated with silicon to provide airtightness. That is, it is an airtight sheet without air permeability. On the other hand, the inner sheet 12 is a sheet having a coarse mesh made of silica and has air permeability. That is, it is a breathable sheet. The heat insulating material 14 is made of batting such as glass fiber or silica, and the cooling refrigerant made of cooled air easily penetrates and diffuses inside. In such a heat insulating cover 9, a fluid supply port 16 is provided in the outer sheet 11, and a cooling fluid, that is, cooling air supplied from a cooling fluid supply device 19 described below, enters the heat insulating cover 9 from the fluid supply port 16. It comes to be supplied. The cooling air supplied to the heat insulating cover 9 leaks from the inner sheet 12 to the heating cylinder 2 side and is discharged from the side of the heat insulating cover 9. The cooling air supply pipes from the cooling fluid supply device 19 to the respective heat insulating covers 9, 9,... Are provided with electromagnetic valves 21, 21,. It is supposed to be. In other words, the cooling fluid supply device 19, the electromagnetic valves 21, 21,... And the fluid supply port 16 constitute a cooling means, and supply cooling air as a cooling fluid to the heat insulating covers 9, 9,. ing.

  The cooling fluid supply device 19 according to the present embodiment will be described. The cooling fluid supply device 19 includes a heat pump 27 and a flow rate amplifying device 28. The heat pump 27 is well known in the art and will be briefly described. The compressor 29 compresses the refrigerant, the condenser 30 that liquefies or condenses the refrigerant to discharge latent heat to the outside, and the pressure reducing valve that depressurizes the refrigerant by a throttling action. 31, an evaporator 32 that evaporates the refrigerant and takes latent heat from the outside, and a refrigerant pipe that circulates these components. In the present embodiment, air is passed through the evaporator 32 of the heat pump 27. This takes latent heat from the air and cools it to obtain cooling air. The cooling air is supplied as a cooling fluid to the heat insulating covers 9, 9,.

  The diverting amplification device 28 includes an amplification tube 34 having a predetermined structure, and a compressor 35 that supplies compressed air to the amplification tube 34. When the compressed air is supplied to the amplifying tube 34, the amount of air several times that of the compressed air is sucked from one end and can be supplied from the other end. The structure is well known, as a similar amplification tube is proposed in Japanese Patent No. 291941. As shown in FIG. 3, the amplification tube 34 according to the present embodiment also has a main pipe passage 37 having a predetermined diameter formed therein, and a compressed air supply hole 38 through which compressed air is supplied to the side. Is provided. An air reservoir 39 is formed concentrically with the main conduit 37 inside the thick portion formed at the center of the amplification tube 34, and the compressed air supply hole 38 communicates with the air reservoir 39. A compressed air supply path 40 communicating with the main pipe line 37 is formed from the air reservoir 39. The compressed air supply path 40 has a conical shape, and is a nozzle portion that injects compressed air into the main pipe line 37 in a conical shape. In the present embodiment, one end 41 of the main pipeline 37 is open to the outside air, but the other end 42 is connected to the air supply pipe 43 as shown in FIG. Air is supplied to the evaporator 32. With this configuration, when compressed air is supplied from the compressor 35, the compressed air is injected in a conical shape within the amplifying tube 34, and a negative pressure is generated behind this cone. A large amount of air is sucked from 41. The compressed air and the sucked air injected in a conical shape are ejected from the other end portion 42 and sent to the evaporator 32 by the air supply pipe 43. That is, a large amount of air is sent to the evaporator 32. As a result, the flow rate amplifying device 28 according to the present embodiment can generate a large amount of cooling air, and can thereby stably supply the cooling air to the heat insulating covers 9, 9.

  In the present embodiment, the heating cylinder 2 is provided with temperature sensors 22, 22,... Corresponding to each zone, and these temperature sensors 22, 22,... Are also connected to a controller (not shown). Also, a power supply device that supplies power to the band heaters 7, 7,... By PWM control is not shown in the figure, but is connected to a controller and controlled by the controller.

  The temperature control of the heating cylinder of the injection apparatus 1 according to the present embodiment will be described. In the temperature control according to the present embodiment, the control of the band heater 7 and the control of the cooling means, that is, the electromagnetic valve 21 are combined. The band heater 7 is controlled by so-called PWM control that turns on / off the current according to the duty ratio, but the duty ratio is controlled by PID control. That is, the deviation from the measured temperature obtained from the temperature sensor 22 with respect to the target temperature M is obtained, and the duty ratio is calculated as the manipulated variable by PID control. In the present embodiment, the PID control is adjusted to increase the gain. That is, when the target temperature M is given and controlled, the band heater 7 is adjusted so that overshoot is allowed when the deviation between the target temperature M and the measured temperature is large. On the other hand, the solenoid valve 21 is controlled by simple ON / OFF control. That is, when the electromagnetic valve 21 is turned on and opened, compressed air, which is a cooling fluid, is supplied into the heat insulating cover 9, and when it is turned off and closed, the supply of compressed air is stopped.

  In the injection apparatus 1 according to the present embodiment, a temperature control method performed by the controller when the operator sets a target temperature M for each zone of the heating cylinder 2 will be described. Since the controller performs the same control in any zone, only the predetermined zone will be described. When the target temperature M is set, the controller first calculates a determination temperature H that is higher than the target temperature M by a predetermined deviation temperature. This deviation temperature is a temperature set in advance in the controller, and a different temperature can be set for each zone. However, in this embodiment, a temperature common to each zone, for example, 1 ° C. is set. Therefore, for example, if the target temperature M is 200 ° C., the determination temperature H is calculated as 201 ° C. Such a determination temperature H is a temperature at which it is determined whether or not to operate the cooling means, but the control of the band heater 7 is performed regardless of the determination temperature H. The target temperature M and the determination temperature H are shown in the graph of FIG. The controller controls the band heater 7 by PID control. When the zone temperature 25 is much lower than the target temperature M, the PID control gain is large, so the duty ratio for energizing the band heater 7 is 1.0 or a high ratio close to 1.0. Then, as indicated by reference numeral 26, the zone temperature 25 rises with a high slope. Since the temperature rises with such an inclination, the zone temperature 25 overshoots as indicated by reference numeral 27 even when the energization to the band heater 7 becomes zero when the target temperature M is reached. When the controller detects that the zone temperature 25 exceeds the determination temperature H, the controller drives the cooling means. That is, the electromagnetic valve 21 is turned on to supply cooling air to the heat insulating cover 9. The timing for driving the cooling means is indicated by reference numeral 28. When the cooling air is supplied to the heat insulating cover 9, the cooling air permeates and diffuses into the heat insulating material 14 and leaks inward from the inner sheet 12. Then, the band heater 7 and the heating cylinder 2 can be cooled. Immediately after driving the cooling means, the temperature 25 of the zone slightly increases, but eventually decreases due to cooling. In the present embodiment, the cooling means is driven until the zone temperature 25 decreases to the target temperature M, and when the target temperature M is reached, the driving is stopped. The timing of stopping the cooling means, that is, the timing of closing the electromagnetic valve 21 by turning it off is indicated by reference numeral 29. Even if the cooling means is stopped, the zone temperature 25 falls below the target temperature M as indicated by reference numeral 31, but when the temperature falls below the target temperature M, the band heater 7 is driven. At this time, since the deviation between the target temperature M and the zone temperature 25 is relatively small, the duty ratio is small. As a result, the gradient of temperature rise is relatively small. Therefore, the peak of overshoot in which the zone temperature 25 exceeds the target temperature M is smaller than the previous time. As shown in the graph, when the determination temperature H is exceeded again, the cooling means is driven, but since the overshoot peak is small, the time during which the cooling means is driven, that is, indicated by reference numeral 32. The time from the current timing to the timing indicated by reference numeral 33 is short. When such control is repeated, the zone temperature 25 does not exceed the determination temperature H and gradually changes as indicated by reference numeral 35. The controller controls the temperature only by the band heater 7, the duty ratio is stabilized, and the zone temperature 25 smoothly reaches the target temperature M. That is, the temperature is controlled so as to reach the target temperature M.

  The temperature control method according to the present embodiment can be variously modified. FIG. 4A shows a change in the temperature of the zone when controlled by the temperature control method according to the second embodiment. In the temperature control method according to the second embodiment, the condition for stopping the cooling means is different from the temperature control method according to the first embodiment, and the temperature 25 ′ of the zone is lower than the determination temperature H. When to stop. That is, the cooling means is stopped at reference numerals 29 'and 33'. Then, since the temperature change gradually changes after the cooling means is stopped, it becomes difficult to fall below the target temperature M. Further, as indicated by reference numeral 36, even if the temperature falls below the target temperature M, the temperature does not drop greatly, and as a result, the target temperature M is reached early.

  The injection device 1 according to the present embodiment can also be modified. FIG. 2 (a) shows an injection apparatus 1 ′ according to the second embodiment, but the heat insulating cover 9 ′ is provided with a predetermined gap from the band heater 7, and in this gap Cooling air can be blown. Thus, since the cooling air which is a cooling fluid is blown, in this embodiment, it is not necessary for the heat insulating material 14 'to penetrate and diffuse the cooling air. The heat insulating cover 9 ′ is provided with a fluid discharge port 17, and cooling air supplied to the heat insulating cover 9 ′ is discharged from the fluid discharge port 17.

DESCRIPTION OF SYMBOLS 1 Injection device 2 Heating cylinder 3 Screw 5 Injection nozzle 7 Band heater 9 Heat insulation cover 11 Outer sheet 12 Inner sheet 14 Heat insulation material 16 Fluid supply port 17 Fluid discharge port 19 Cooling fluid supply device 21 Solenoid valve 22 Temperature sensor 25 Zone temperature 27 Heat pump 28 Flow rate amplifying device 32 Evaporator 34 Amplifying pipe 35 Compressor 37 Main line 40 Compressed air supply path M Target temperature H Determination temperature

Claims (4)

The heating cylinder is divided into a plurality of zones in the axial direction, and each zone is wound with a band heater wound around the outer peripheral surface of the heating cylinder, a heat insulating cover provided outside the band heater, An injection device comprising a cooling means for supplying a cooling fluid from the outside to each zone, and the temperature of each zone is controlled independently.
When temperature control is performed according to the target temperature set for each zone, the band heater is controlled by PWM control, and the cooling means is a determination temperature at which the temperature of the zone is higher than the target temperature by a predetermined deviation temperature. A method for controlling the temperature of a heating cylinder, wherein the cooling fluid is supplied by supplying a cooling fluid when the pressure exceeds the cooling air, and the cooling fluid comprises cooling air cooled by a heat pump. The method according to claim 1, wherein the cooling fluid is obtained by cooling air supplied from a flow rate amplifying device by the heat pump.
The flow rate amplifying device includes an amplifying tube having a predetermined length provided with a main pipe having a predetermined diameter penetrating in the axial direction, and an air compressor for supplying compressed air to the amplifying tube, and the amplifying tube is formed from a side portion. A compressed air supply passage communicating with the main pipeline is provided, and one end of the main pipeline is exposed to the outside air, and the other end is connected to the heat pump. A heating cylinder characterized in that when compressed air is supplied to an air supply passage, air is sucked from the one end portion of the main pipeline and air is supplied to the heat pump from the other end portion. Temperature control method.   3. The method according to claim 1, wherein when the temperature of the zone exceeds the determination temperature and supply of the cooling fluid is started by the cooling means, the cooling fluid is added until the temperature of the zone decreases to the target temperature. A method for controlling the temperature of a heating cylinder, characterized by comprising:   2. The method according to claim 1, wherein when the temperature of the zone exceeds the determination temperature and the cooling means starts supplying the cooling fluid, the supply of the cooling fluid is stopped when the temperature of the zone decreases to the determination temperature. A method for controlling the temperature of a heating cylinder.

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