JP2013224017A - Injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an injection molding machine that can manage a temperature of resin in a cylinder.SOLUTION: An injection molding machine 10 includes: a cylinder 41 from which a resin material is supplied; a plurality of heating sources 91-94 to heat the cylinder 41; a plurality of temperature sensors 21-24 that detect temperatures of different positions of the cylinder 41; a control device 80 that controls the plurality of heating sources 91-94 based on the differences of the measured temperatures of the temperature sensors 21-24 with the target temperatures in measurement positions of the temperature sensors 21-24. The target temperature distribution in the cylinder shaft direction of the cylinder inner wall is set beforehand. The control device 80 calculates target temperatures in the measurement positions of the temperature sensors 21-24 based on the target temperature distribution, and controls the plurality of heating sources 91-94 by using the calculated target temperatures.

Description

  The present invention relates to an injection molding machine.

  The injection molding machine includes an injection device that injects molten resin into a mold apparatus. The mold apparatus includes a fixed mold and a movable mold, and a cavity space is formed between the fixed mold and the movable mold when the mold is clamped. The injection device injects the resin melted in the cylinder from a nozzle provided at the tip of the cylinder and fills the cavity space in the mold device. The resin cooled and solidified in the cavity space is taken out as a molded product after the mold is opened.

  The injection device includes a screw that is rotatably disposed in the cylinder and is movable in the axial direction. Resin material is supplied from a hopper to one end of the screw. When the screw rotates, the flight (screw thread) of the screw moves, and the resin filled in the screw groove of the screw is sent from the hopper side to the nozzle side.

  The temperature on the nozzle side of the cylinder is maintained at the melting temperature of the resin. On the other hand, the temperature on the hopper side of the cylinder is maintained at a temperature at which the resin is not softened or melted so that the resin bridge (agglomeration) does not occur. Therefore, the hopper side of the cylinder is cooled by a cooling block having a refrigerant flow path inside.

  The cylinder includes a cylinder body that extends between the cooling block and the nozzle. The cylinder body is divided into a plurality of zones along the axial direction, and a heating source and a temperature sensor are provided for each zone. A plurality of heating sources are feedback controlled based on the difference between the measured temperature of each temperature sensor and the target temperature at the measurement position of each temperature sensor (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 11-227019

  Each temperature sensor pinpoints the temperature of each zone, and the measured temperature is managed as a representative temperature in each zone. Therefore, the temperature distribution in the radial direction and the axial direction of the cylinder is not managed, and the temperature distribution in the cylinder axial direction of the cylinder inner wall is not managed.

  FIG. 11 is a diagram showing a temperature distribution in the cylinder axial direction of a conventional cylinder inner wall. In FIG. 11, the solid line represents the target temperature distribution, the broken line represents an example of the possible temperature distribution, the alternate long and short dash line represents another example of the possible temperature distribution, and the black circle represents the measurement position of the temperature sensor in the cylinder axis direction.

  In the vicinity of the measurement position of the temperature sensor, the target temperature and the possible temperature (actual temperature) substantially coincide with each other because of feedback control. On the other hand, at a position away from the measurement position of the temperature sensor, the target temperature and the possible temperature (actual temperature) may be greatly shifted.

  Since the cylinder inner wall is in contact with the resin, if the temperature distribution of the cylinder inner wall deviates from the target temperature distribution, the temperature of the resin will be too high or too low. If the temperature of the resin is too high, the resin is altered by heat. On the other hand, if the temperature of the resin is too low, the fluidity of the resin is deteriorated and the load on the injection device is excessive.

  The present invention has been made in view of the above problems, and an object thereof is to provide an injection molding machine capable of managing the temperature of resin in a cylinder.

In order to solve the above problems, an injection molding machine according to an aspect of the present invention is provided.
A cylinder supplied with resin material;
A plurality of heating sources for heating the cylinder;
A plurality of temperature sensors for detecting temperatures at different positions of the cylinder;
A controller for controlling the plurality of heating sources based on a difference between a measured temperature of each temperature sensor and a target temperature at a measurement position of each temperature sensor;
The target temperature distribution in the cylinder axial direction of the cylinder inner wall is preset,
The control device calculates a target temperature at a measurement position of each temperature sensor based on the target temperature distribution, and controls the plurality of heating sources using the calculated target temperature.

  ADVANTAGE OF THE INVENTION According to this invention, the injection molding machine which can manage the temperature of the resin in a cylinder is provided.

It is a figure which shows the outline of the injection molding machine by 1st Embodiment of this invention. It is a figure which shows the principal part of the injection molding machine by 1st Embodiment. It is explanatory drawing of the setting of the target temperature by 1st Embodiment. It is a figure which shows the principal part of the injection molding machine by 2nd Embodiment of this invention. It is a figure which shows the 1st example of the position which sets target temperature previously in the cylinder of FIG. It is a figure which shows the 2nd example of the position which sets target temperature previously in the cylinder of FIG. It is a figure which shows the 3rd example of the position which sets the target temperature previously in the cylinder of FIG. It is explanatory drawing of the heat conduction equation of the cylinder by 2nd Embodiment of this invention. It is explanatory drawing of the heat conduction equation of the substance in the cylinder by 2nd Embodiment of this invention. It is explanatory drawing of the formula showing the inflow and outflow of the heat | fever in the heating source by 2nd Embodiment of this invention. It is a figure which shows the temperature distribution in the cylinder axial direction of the conventional cylinder inner wall.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In each of the drawings, the same or corresponding components are denoted by the same or corresponding reference numerals, and description thereof will be omitted. Further, the description will be made assuming that the injection direction of the resin by the injection device is the front and the direction opposite to the injection direction is the rear.

[First Embodiment]
FIG. 1 is a diagram showing an outline of an injection molding machine according to a first embodiment of the present invention. FIG. 1 shows a state of mold clamping.

  The injection molding machine 10 includes a frame 11, a fixed platen 12 fixed to the frame 11, and a plurality of (for example, four) tie bars 16 extending from the fixed platen 12. The injection molding machine 10 further includes a movable platen 13 that is disposed so as to face the fixed platen 12 and is movable along the tie bar 16 (movable in the left-right direction in the drawing). A movable mold 33 is attached to a surface of the movable platen 13 facing the fixed platen 12, and a fixed mold 32 is attached to a surface of the fixed platen 12 facing the movable platen 13. The fixed mold 32 and the movable mold 33 constitute a mold apparatus 30. The movable platen 13 is brought into contact with and separated from the fixed platen 12 to perform mold closing, mold clamping, and mold opening. A cavity space C is formed between the movable mold 33 and the fixed mold 32 in the clamped state.

  The injection molding machine 10 further includes an injection device 40 that injects the resin melted in the cylinder 41 from the nozzle 42 and fills the cavity space C in the mold device 30. The injection device 40 includes an injection motor 43. The rotation of the injection motor 43 is transmitted to the ball screw shaft 44. A ball screw nut 45 that moves forward and backward by the rotation of the ball screw shaft 44 is fixed to a pressure plate 46. The pressure plate 46 is movable along guide bars 47 and 48 fixed to a base frame (not shown). The forward / backward movement of the pressure plate 46 is transmitted to the screw 52 via the bearing 49, the load cell 50, and the injection shaft 51. The screw 52 is disposed in the cylinder 41 so as to be rotatable and movable in the axial direction. Resin pellets (resin material) are supplied from the hopper 53 to the rear end portion of the screw 52. The rotation movement of the metering motor 55 is transmitted to the injection shaft 51 via a connecting member 54 such as a belt or a pulley. That is, when the injection shaft 51 is rotationally driven by the metering motor 55, the screw 52 rotates.

  In the weighing step, the weighing motor 55 is driven to rotate the screw 52, and the resin pellet supplied to the rear end portion of the screw 52 is sent to the front of the screw 52. In this process, the resin pellets are softened and melted. Since the resin is stored in front of the screw 52, the screw 52 moves backward. In the injection process, the injection motor 43 is driven, the screw 52 is advanced, the resin is pressed, and the nozzle 42 is injected. The resin is pushed into the cavity space C formed between the fixed mold 32 and the movable mold 33 through the sprue S formed in the fixed mold 32. The force pushing the resin is detected as a reaction force by the load cell 50. That is, the injection pressure of the resin from the nozzle 42 is detected. The detected injection pressure is input to the control device 80. Further, since the resin is thermally contracted by cooling in the cavity space C, the resin injection pressure is maintained at a predetermined pressure in the pressure-holding step in order to supplement the resin for the heat shrinkage.

  A position detector 57 for detecting the amount of movement of the screw 52 is attached to the pressure plate 46. A detection signal from the position detector 57 is input to the control device 80. The detection signal of the position detector 57 may also be used to detect the moving speed of the screw 52.

  Each of the injection motor 43 and the metering motor 55 may be a servo motor, and includes encoders 43a and 55a for detecting the rotation speed. The rotation speeds detected by the encoders 43a and 55a are respectively input to the control device 80. The control device 80 feedback-controls the injection motor 43 and the metering motor 55 based on the detection results of the encoders 43a and 55a.

  The control device 80 controls various operations of the injection molding machine 10. The control device 80 is configured by a microcomputer or the like, and includes, for example, a CPU, a memory, a timer, a counter, an input interface, and an output interface.

  FIG. 2 is a view showing a main part of the injection molding machine according to the first embodiment.

  A rear portion 41 b of the cylinder 41 is inserted into a cooling block (cooling portion) 61 and is cooled by the cooling block 61. A resin supply port 62 is formed in the cooling block 61 and the cylinder 41. Resin pellets supplied from the hopper 53 into the cylinder 41 through the resin supply port 62 are filled in the screw grooves of the screw 52. When the screw 52 rotates, the flight (screw thread) 52a of the screw 52 moves, and the resin pellet is fed forward through the screw groove of the screw 52.

  The rear portion 41b of the cylinder 41 is cooled to a temperature at which the resin is not softened or melted. A coolant such as cooling water is supplied to the coolant channel 63 formed in the cooling block 61, and the cylinder 41 is cooled by the coolant. The tip of the temperature sensor 25 is embedded in the cooling block 61, and a detection signal from the temperature sensor 25 is input to the control device 80.

  The cylinder 41 includes a cylinder body 41 a that extends between the cooling block 61 and the nozzle 42. A plurality of heating sources (for example, heaters) 91 to 94 are provided on the outer wall 41c of the cylinder body 41a to heat the cylinder body 41a to a predetermined temperature. The resin that moves forward in the cylinder body 41a is heated by heat from the heating sources 91-94. The resin enters a molten state as it goes forward of the cylinder body 41a. The resin is completely melted at the tip of the cylinder body 41a. As the molten resin accumulates in front of the screw 52, the screw 52 moves backward. When the screw 52 moves backward by a predetermined distance and a predetermined amount of resin is accumulated in front of the screw 52, the rotation of the screw 52 is stopped. Then, when the rotation of the screw 52 is stopped, the screw 52 moves forward, whereby the molten resin is injected from the nozzle 42 into the mold apparatus 30.

  The screw 52 is distinguished from the rear (resin supply side) to the front (nozzle side) along the axial direction as a supply unit 52Z1, a compression unit 52Z2, and a measuring unit 52Z3. The supply part 52Z1 is a part to which resin is supplied and conveyed forward. The compression part 52Z2 is a part that melts while compressing the supplied resin. The measuring unit 52Z3 is a part that measures a certain amount of molten resin. The depth of the screw groove of the screw 52 is deeper at the supply part 52Z1, shallower at the measuring part 52Z3, and shallower toward the front in the compression part 52Z2.

  The cylinder body 41a is divided into a plurality of (for example, four) zones Z1 to Z4 along the axial direction, and heating sources 91 to 94 are provided for each of the zones Z1 to Z4. Supply currents to the heating sources 91 to 94 are individually controlled, and the cylinder body 41a is heated for each of the zones Z1 to Z4. Each heating source 91-94 is provided so that the outer periphery of the cylinder main-body part 41a may be enclosed. Although not shown, a heating source may also be provided on the outer periphery of the nozzle 42.

  Temperature sensors (for example, thermocouples) 21 to 24 are provided for each of the zones Z1 to Z4. The tips of the temperature sensors 21 to 24 are embedded in the cylinder body 41a, and the temperature sensors 21 to 24 measure the temperature pinpointly. Detection signals from the temperature sensors 21 to 24 are input to the control device 80.

  The control device 80 controls the plurality of heating sources 91 to 94 based on the difference between the measured temperature of each temperature sensor 21 to 24 and the target temperature. The supply current to each heating source 91 to 94 is controlled so that the difference between the measured temperature of the temperature sensors 21 to 24 in the same zone Z1 to Z4 as that of each heating source 91 to 94 and the target temperature is small. PID controlled.

  In addition, the supply current to each heating source 91-94 may be controlled based on the measured temperature of the temperature sensor of the zone adjacent to the zones Z1-Z4 of each heating source 91-94. Considering the heat flux in the cylinder axial direction, the temperature at the measurement position of each temperature sensor can be quickly converged to the target temperature. Moreover, although one temperature sensor 21-24 is provided in each zone Z1-Z4, multiple may be provided. The plurality of temperature sensors provided in one zone may be provided at different positions in the cylinder axial direction, or may be provided at different positions in the cylinder radial direction.

  Next, a method for setting the target temperature at the measurement position of each temperature sensor will be described with reference to FIG. FIG. 3 is an explanatory diagram of a target temperature setting method according to the first embodiment. 3A shows the actual shape of the cylinder body, FIG. 3B shows the shape of the cylinder body for the heat transfer model, and FIG. 3C shows the temperature distribution on the inner wall of the cylinder body. In FIG.3 (c), a continuous line represents the target temperature distribution set by the user, and a dashed-dotted line represents the optimal temperature distribution calculated by a heat transfer model.

  In the present embodiment, first, the user operates the input device (for example, keyboard) 82 of the injection molding machine 10 to target the cylinder inner wall in the cylinder axial direction, not the target temperature at the measurement position of each temperature sensor 21 to 24. Set the temperature distribution. Note that the target temperature distribution may be set by reading out the target temperature distribution recorded in advance in a recording medium such as a memory of the control device 80.

  The setting of the target temperature distribution is performed for the cylinder main body 41a and may be omitted for the cylinder rear portion 41b in order to simplify the calculation described later. Since the outer periphery of the cylinder rear portion 41b is surrounded by the cooling block 61, the temperature of the cylinder rear portion 41b can be considered to be substantially constant. An operation signal indicating a user operation at the input device 82 is input to the control device 80 and recorded in a recording medium such as a memory.

  The target temperature distribution is set by dividing the cylinder body inner wall 41d into a plurality of sections in the cylinder axis direction and inputting the temperature for each section. An image associating the position of each section with the set temperature of each section may be displayed on the display device 84 so that the user can set the temperature of each section while checking the position of the section where the temperature is set.

  The number of compartments (that is, the number of positions where the user sets the temperature) is larger than the number of temperature sensors 21 to 24 arranged at intervals in the cylinder axis direction (four in FIG. 3). Instead of the temperature of each section, a function representing the target temperature distribution may be input. The number of compartments increases substantially.

  Among the plurality of compartments, in the compartment within a predetermined distance forward from the rear end (end on the cooling block 61 side) of the cylinder main body 41a, the resin does not have to be softened or melted. The value is set, and the lower temperature limit is not set. That is, a target temperature distribution in which the temperature of the cylinder inner wall is equal to or lower than the set temperature may be set at a position within the predetermined distance MZ forward from the rear end of the cylinder body 41a.

  Subsequently, the control device 80 calculates the target temperature at the measurement position of each of the temperature sensors 21 to 24 based on the target temperature distribution recorded on the recording medium. For the calculation of the target temperature, a heat transfer model capable of calculating the temperature distribution of the cylinder body 41a based on the temperature of each of the heating sources 91 to 94 is used. A heat transfer model that can calculate the temperature distribution of the cylinder body 41a based on the temperature of each of the heating sources 91 to 94 and the temperature of the cooling block 61 may be used.

  The shape of the cylinder body portion 41a for the heat transfer model is approximately cylindrical as shown in FIG. Since the temperature of the cylinder body 41a is substantially uniform around the center line of the cylinder body 41a, a heat transfer model is created based on a two-dimensional heat diffusion equation expressed by the following equation (1).

上記式（１）中、ｚはシリンダ軸方向における位置座標、ｒはシリンダ径方向における位置座標、Ｔは座標（ｚ，ｒ）での温度、ｔは時刻を表す。ｚ座標の原点はシリンダ本体部４１ａの前端面、ｒ座標の原点はシリンダ本体部４１ａの中心線である。シリンダ本体部４１ａの寸法（内径、外径、軸方向長さ）、熱拡散率α［ｍ^２／ｓ］は予め測定され、制御装置８０のメモリ等に格納されている。シリンダ本体部４１ａの寸法等の温度依存性は十分に小さく、室温（２５℃）で測定したデータが用いられてよい。

In the above formula (1), z represents position coordinates in the cylinder axis direction, r represents position coordinates in the cylinder radial direction, T represents temperature at the coordinates (z, r), and t represents time. The origin of the z coordinate is the front end face of the cylinder body 41a, and the origin of the r coordinate is the center line of the cylinder body 41a. The dimensions (inner diameter, outer diameter, axial direction length) and thermal diffusivity α [m ² / s] of the cylinder body 41a are measured in advance and stored in a memory or the like of the control device 80. Temperature dependency such as dimensions of the cylinder body 41a is sufficiently small, and data measured at room temperature (25 ° C.) may be used.

As shown in the equation (1), the thermal diffusivity α is determined by the thermal conductivity λ [J / (s · m · ° C.)], the density ρ [kg / m ³ ], and the constant pressure specific heat Cp [J / ( kg · ° C.)]. Therefore, instead of the thermal diffusivity α, the thermal conductivity λ, the density ρ, and the constant pressure specific heat Cp may be stored in the memory of the control device 80. The constant pressure specific heat Cp [J / (kg · ° C.)] can be calculated by the ratio [Cp = C / W] of the heat capacity C [J / ° C.] and the mass W (kg). Therefore, the heat capacity C and the mass W may be stored in the memory of the control device 80 instead of the constant pressure specific heat Cp.

  In order to solve equation (1) above, boundary conditions are given. For example, the boundaries B1 to B4 between the cylinder body 41a and the heating sources 91 to 94, the boundary B5 between the cylinder body 41a and the outside air, and the boundary B6 between the cylinder body 41a and the resin Heat transfer boundary conditions apply. A temperature fixing condition is applied to the rear end B7 of the cylinder body 41a. Note that a heat flux boundary condition may be used as the boundary condition, and the type of boundary condition may be general.

Data used in the boundary condition is determined by the type of boundary condition. For example, in the case of the above boundary conditions, (1) the heat transfer coefficient [W / (m ² · ° C.)] between the cylinder body 41a and each of the heating sources 91 to 94, (2) the heating sources 91 to 94 Temperature, (3) heat transfer coefficient between cylinder body 41a and outside air [W / (m ² · ° C.)], (4) temperature of outside air, (5) heat between cylinder body 41a and resin The transmission rate [W / (m ² · ° C.)], (6) the temperature of the resin, and (7) the temperature at the rear end of the cylinder body 41a (the temperature of the cooling block 61) are used. These data may be input by the user, or may be stored in advance in the memory of the control device 80 or the like. However, when solving the convex optimization problem described later, (2) the temperatures of the heating sources 91 to 94 are treated as variables to be solved. As a variable to be solved, (7) the temperature of the rear end B7 of the cylinder body 41a (the temperature of the cooling block 61) may be added.

  The above equation (1) is discretized in order to divide the cylinder body 41a into a plurality of finite elements, and a linear system (simultaneous linear differential equation) is created. By solving the steady solution of the created linear system, a steady solution of the temperature distribution of the cylinder body 41a is obtained, and a steady solution of the temperature distribution on the cylinder body inner wall 41d is obtained. The discretization method may be a general one.

  The control device 80 creates an evaluation function whose value becomes better (smaller) as the difference between the steady solution of the temperature distribution in the cylinder body inner wall 41d and the target temperature distribution becomes smaller. The evaluation function may be a general one used in the convex optimization problem. A temperature upper limit value set by the user is used as a constraint condition in the convex optimization problem. That is, a constraint condition that the temperature of the cylinder body inner wall 41d is equal to or lower than the set temperature is applied to the convex optimization problem at a position within the predetermined distance MZ forward from the rear end B7 of the cylinder body 41.

  The controller 80 solves the optimum solution of the evaluation function (the optimum solution of the temperature in the steady state of each heating source 91 to 94) by the quadratic programming method. Next, the control device 80 solves the stationary solution of the linear system again using the obtained optimum solution as a boundary condition. Thereby, the optimal steady solution of the temperature distribution of the cylinder main-body part 41a is obtained. The optimum temperature at the measurement position of each temperature sensor 21 to 24 is obtained by referring to the data (r coordinate, z coordinate) indicating the measurement position of each temperature sensor 21 to 24 recorded in advance on the recording medium. It is done. This optimum temperature is adopted as the target temperature. The control device 80 controls the plurality of heating sources 91 to 94 using a target temperature that is an optimum temperature. Therefore, the actual temperature distribution of the cylinder body inner wall 41d can be as close as possible to the target temperature distribution.

  Since the actual temperature distribution of the cylinder body inner wall 41d cannot be measured, an optimal steady solution of the temperature distribution of the cylinder body inner wall 41d may be displayed on the display device 84 instead. For comparison, the target temperature distribution may be displayed on the display device 84 at the same time. For example, information as shown in FIG. 3C is displayed on the display device 84 as an image. The user can compare and visually check.

  As described above, according to the present embodiment, the target temperature at the measurement position of each temperature sensor 21 to 24 is calculated based on the target temperature distribution of the cylinder inner wall set by the user. Therefore, the temperature of the resin in the cylinder 41 can be managed. In addition, the number of positions where the user sets the temperature is larger than the number of temperature sensors 21 to 24 (four in FIG. 3). Since the target temperature at the measurement position of each temperature sensor is determined in consideration of the temperature at the position between the temperature sensors, the difference between the actual temperature distribution and the target temperature distribution is small, and the resin in the cylinder 41 Can be accurately controlled.

  Further, at the position within the predetermined distance MZ forward from the rear end (end on the cooling block 61 side) B7 of the cylinder body 41a, the upper limit value of the temperature is set as the target temperature distribution, and the lower limit value of the temperature is not set. There is a range in the set temperature. This is because, in the region close to the cooling block 61, if the resin is not softened or melted, there is no adverse effect on the transport of the resin. Since the condition of the target temperature distribution is gentle in the region close to the cooling block 61, the difference between the actual temperature distribution in the region where the resin melts and the target temperature distribution can be reduced accordingly, and the molten resin The fluidity of the can be optimized.

[Second Embodiment]
In the first embodiment, the target temperature distribution in the cylinder axial direction of the cylinder inner wall is set in advance.

  In the present embodiment, a target temperature at a predetermined position in the cylinder and / or the cylinder is set in advance.

FIG. 4 is a view showing a main part of an injection molding machine according to the second embodiment of the present invention. The injection molding machine includes a cylinder 141, a screw 152 that sends resin in the cylinder 141, a plurality of heating sources H _{1 to} H ₄ that heat the cylinder 141, and a cooling block 161 that cools the rear part of the cylinder 141.

  The screw 152 is disposed in the cylinder 141 so as to be rotatable and movable in the axial direction. As the screw 152 rotates, the resin pellets are fed forward along a spiral groove formed in the screw 152.

The heating sources H _{1 to} H ₄ heat the cylinder 141 to melt the resin in the cylinder 141. As the heating sources H _{1 to} H ₄ , for example, a heater that heats the cylinder 141 from the outside is used. The heater is provided so as to surround the outer periphery of the cylinder 141.

The plurality of heating sources H _{1 to} H ₄ are arranged along the axial direction of the cylinder 141, and the cylinder 141 is divided into a plurality of zones (four zones Z _{1 to} Z _{4 in} FIG. ₄ ) and heated individually. To do. The plurality of heating sources H _{1 to} H ₄ are feedback-controlled by the controller 180 so that the temperatures of the zones Z _{1 to} Z ₄ become the set temperatures. Temperature of each zone _Z 1 to Z ₄ is measured by the temperature sensor _S 1 to S _4. The nozzle 142 may also be provided with a heating source.

The control device 180 controls the plurality of heating sources H _{1 to} H ₄ based on the temperature deviation between the measured temperature and the target temperature at the measurement positions of the temperature sensors S _{1 to} S ₄ . The supply current to each of the heating sources H _{1 to} H ₄ is controlled so that the temperature deviation becomes small, for example, PID control.

The control device 180 calculates a target temperature at the measurement position of each of the temperature sensors S _{1 to} S ₄ based on the target temperature at a predetermined position inside the cylinder and / or the cylinder, and uses the calculated target temperature to perform a plurality of heating operations. Control of the sources H _{1 to} H ₄ is performed. A heat transfer model is used to calculate the target temperature.

  FIG. 5 shows a first example of a position where the target temperature is set in advance in the cylinder of FIG. FIG. 6 shows a second example of the position where the target temperature is set in advance in the cylinder of FIG. FIG. 7 shows a third example of the position where the target temperature is set in advance in the cylinder of FIG. 5 to 7, black circles represent positions where the target temperature is set in advance.

As in the first embodiment, the position where the target temperature shown in FIG. 5 is set in advance is the cylinder inner wall and is arranged at intervals along the cylinder axial direction. The target temperature at the measurement position of each of the temperature sensors S _{1 to} S ₄ can be calculated so that the temperature of the cylinder inner wall becomes a desired temperature. Therefore, the temperature of the resin near the cylinder inner wall can be managed.

The position where the target temperature shown in FIG. 6 is set in advance is a position where the depth from the cylinder outer wall is the same as the measurement position of each of the temperature sensors S _{1 to} S ₄ , and is spaced along the cylinder axis direction. line up. Therefore, the temperature between the measurement positions of the temperature sensors S _{1 to} S ₄ can be managed.

The position where the target temperature is set in advance shown in FIG. 7 is inside the cylinder, and is arranged at intervals along the cylinder axial direction. The target temperature at the measurement position of each of the temperature sensors S _{1 to} S ₄ can be calculated so that the temperature of the resin inside the cylinder becomes a desired temperature, and the temperature of the resin inside the cylinder can be managed.

  Note that the position where the target temperature is set in advance may be anywhere in the cylinder or in the cylinder. For example, the position where the target temperature is set in advance may be a position where the depth from the cylinder outer wall is closer to the cylinder inner wall than the measurement position of the temperature sensor. Further, the positions at which the target temperature is set in advance may not be arranged at intervals in the cylinder axis direction, but may be arranged at intervals in the cylinder radial direction. Further, the position where the target temperature is set in advance may be both in the cylinder and in the cylinder, for example, both the position indicated by a black circle in FIG. 6 and the position indicated by a black circle in FIG. The position where the target temperature is set in advance may be determined in advance, or may be selectable by the user.

The heat transfer model based on the temperature of each heating source _H 1 to H _4, (including cylinder body portion 141a) cylinder 141 and an equation temperature distribution in the cylinder 141 can be calculated.

For example, the heat transfer model includes a heat transfer equation of the cylinder 141, a heat transfer equation of a substance in the cylinder 141 (hereinafter also referred to as “in-cylinder substance”), and each heating source H _k (k = 1, 2 in FIG. 4). , 3, 4) is an equation based on the equation representing heat inflow and outflow. Hereinafter, each formula will be described with reference to FIGS. In each formula, the same symbol has the same meaning.

  FIG. 8 is an explanatory diagram of the heat conduction equation of the cylinder according to the second embodiment of the present invention. The heat conduction equation of the cylinder is expressed by the following equation (2), for example. In the equation (2), for simplification of the equation, the temperature of the cylinder 141 is approximated to be substantially uniform around the center line of the cylinder 141 and is two-dimensionalized. In addition, in the later-described formulas (3) and (4), they are similarly two-dimensional.

上記式（２）中、ｘはシリンダ軸方向（前後方向）における位置座標、ｙはシリンダ径方向における位置座標、Ｒ_ｏｕｔはシリンダ１４１の外周面の半径、Ｔ（ｔ）は時刻ｔにおける座標（ｘ，ｙ）での温度、αはシリンダ１４１の熱拡散率［ｍ^２／ｓ］を表す。ｘ座標の原点はシリンダ１４１の前端面であり、前端面から後端面に向かうほどｘが大きくなる。また、ｙ座標の原点はシリンダ１４１の外周面であり、外周面から内周面に向かうほどｙが大きくなる。

In the above formula (2), x is a position coordinate in the cylinder axial direction (front-rear direction), y is a position coordinate in the cylinder radial direction, R _out is a radius of the outer peripheral surface of the cylinder 141, and T (t) is a coordinate at time t ( The temperature at x, y), α, represents the thermal diffusivity [m ² / s] of the cylinder 141. The origin of the x coordinate is the front end surface of the cylinder 141, and x increases from the front end surface toward the rear end surface. The origin of the y coordinate is the outer peripheral surface of the cylinder 141, and y increases from the outer peripheral surface toward the inner peripheral surface.

The above equation (2) is discretized, and the region (that is, the cylinder 141) in which the above equation (2) is defined is divided into a plurality of minute regions (elements). Let T _{i, j} (t) be the temperature at the time t of the minute region at the coordinates (i × Δx, j × Δy). i is an integer of 0 to m, and j is an integer of 0 to n. When the length of the cylinder 141 in the axial direction is L, an equation of L = m × Δx is established. Further, assuming that the radius of the inner peripheral surface of the cylinder 141 is R _in and the radius R _out of the outer peripheral surface of the cylinder 141, an equation of R _out −R _in = n × Δy is established. The number (m + 1) × (n + 1) of minute regions in the cylinder 141 is set so that the temperature at an arbitrary position in the cylinder 141 can be solved.

The temperature rise rate (one-time differentiation of the temperature T _{i, j} (t)) of the micro area is determined by the flow of heat into and out of the micro area, and the temperature T _{i, j} (t) of the micro area and the micro area It is determined by the temperature difference from the temperature of the minute region adjacent to the. Therefore, the one-time differentiation of the temperature T _{i, j} (t) of the micro area is the temperature T _{i, j} (t) of the micro area and the temperatures T _{i−1, j} (t), T _{i + 1 of the} adjacent micro area. _{, j} (t), T _{i, j-1} (t), and T _{i, j + 1} (t) (where i is an integer from 1 to m-1 and j is an integer from 1 to n-1). .

Cylinder rear end (coordinate x = m × Δx) the temperature T _m of a micro area _in, j (t) is maintained at substantially the same temperature as the outside air temperature _{T a} by the cooling block 161. Therefore, a temperature fixing condition is given as a boundary condition between the cylinder rear end and the outside air. _That, T m, the expression of j (t) = _{T a} is established. Note that the temperature T _{m, j} (t) at the rear end of the cylinder may be maintained at _a predetermined temperature T _c (T _c > T _a ) that is higher than the temperature T _{a of} the outside air.

On the other hand, boundary conditions between the cylinder front end (coordinate x = 0) and outside air, boundary conditions between the cylinder outer periphery (coordinate y = 0) and outside air, boundary conditions between the cylinder outer periphery (coordinate y = 0) and the heating source H _k , As a boundary condition between the cylinder inner circumference (coordinate y = n × Δy) and the substance in the cylinder, a heat flux boundary condition is given.

Accordingly, the temperature increase rate (one-time differentiation of the temperature T _{0, j} (t)) at the front end of the cylinder (coordinate x = 0) is the temperature of the minute region, the temperature of the minute region adjacent to the minute region, It is determined by the temperature T _{a of} the outside air, the heat transfer coefficient [W / (m ² · ° C.)] between the cylinder 141 and the outside air, and the like.

Similarly, in the cylinder outer periphery (coordinate y = 0), the temperature increase rate (one-time differentiation of the temperature T _{i, 0} (t)) in contact with the outside air is adjacent to the temperature of the minute region and the minute region. The temperature is determined by the temperature of the minute region to be heated, the temperature T _{a of} the outside air, the heat transfer coefficient [W / (m ² · ° C.)] between the cylinder 141 and the outside air, and the like.

In addition, the temperature increase rate (one-time differentiation of the temperature T _{i, 0} (t)) of the minute region in contact with the heating source H _k in the cylinder outer periphery (coordinate y = 0) is the temperature of the minute region, the minute region and the temperature of the adjacent micro areas, the temperature _T hk of the heating source _{H k} (t), the heat transfer coefficient between the cylinder 141 and the heating source ^{_{H k [W / (m 2}} · ℃)] determined by such.

Note that the boundary conditions between the cylinder periphery and the cooling block 161 may be similar to the boundary conditions of the heat source H _k and the cylinder periphery.

The temperature rise rate (one-time differentiation of the temperature T _{i, n} (t)) of the minute region at the cylinder inner circumference (coordinate y = n × Δy) is the temperature of the minute region, the temperature of the minute region adjacent to the minute region. , The temperature T ^fl _i (t) of the substance in the cylinder, the heat transfer coefficient [W / (m ² · ° C.)] between the substance in the cylinder and the cylinder 141, and the like. The temperature T ^fl _i (t) of the substance in the cylinder will be described later.

  The in-cylinder material may be air when the temperature of the cylinder 141 is raised before the start of molding, resin, or may be changed during the molding.

  FIG. 9 is an explanatory diagram of the heat conduction equation of the material in the cylinder according to the second embodiment of the present invention. The heat conduction equation of the in-cylinder material is expressed by, for example, the following formula (3) (where i is an integer from 1 to m−1). In the formula (3), the temperature distribution of the substance in the cylinder is uniform in the radial direction of the cylinder 141 in order to simplify the formula.

上記式（３）中、Ｔ^ｆｌ _ｉ（ｔ）は座標ｘ＝ｉ×Δｘにおける微小空間の時刻ｔの温度［℃］、ρ_ｉｎはシリンダ内物質の密度［ｋｇ／ｍ^３］、ｃ_ｉｎはシリンダ内物質の定圧比熱［Ｊ／ｋｇ］を表す。
ｑ_１は、座標ｘ（ｘ＝ｉ×Δｘ）における微小領域に、前方（図９中左側）の微小領域から流れ込む単位時間当たりの流入熱量［Ｗ］を表す。流入熱量ｑ_１は、微小領域間の温度差（Ｔ^ｆｌ _ｉ−１（ｔ）−Ｔ^ｆｌ _ｉ（ｔ））の関数となっている。その温度差が大きくなるほど、流入熱量ｑ_１が増える。流入熱量ｑ_１の算出には、シリンダ内物質の熱伝導率［Ｗ／（ｍ・℃）］などが用いられる。
ｑ_２は、座標ｘ（ｘ＝ｉ×Δｘ）における微小領域から、後方（図９中右側）の微小領域に流れ出す単位時間当たりの流出熱量［Ｗ］を表す。流出熱量ｑ_２は、微小領域間の温度差（Ｔ^ｆｌ _ｉ（ｔ）−Ｔ^ｆｌ _ｉ＋１（ｔ））の関数となっている。その温度差が大きくなるほど、流出熱量ｑ_２が増える。流出熱量ｑ_２の算出には、シリンダ内物質の熱伝導率［Ｗ／（ｍ・℃）］などが用いられる。
ｑ_３は、座標ｘ（ｘ＝ｉ×Δｘ）における微小領域に、シリンダ１４１から単位時間当たりに流れ込む熱量［Ｗ］を表す。この熱量ｑ_３は、シリンダ内物質とシリンダ１４１との温度差（Ｔ_ｉ,ｎ（ｔ）−Ｔ^ｆｌ _ｉ（ｔ））の関数となっている。その温度差が大きくなるほど、熱量ｑ_３が増える。熱量ｑ_３の算出には、シリンダ内物質とシリンダ１４１との間の熱伝達係数［Ｗ／（ｍ^２・℃）］などが用いられる。

In the above equation (3), T ^fl _i (t) is the temperature [° C.] at time t in the minute space at the coordinate x = i × Δx, ρ _in is the density of the substance _in the cylinder [kg / m ³ ], and c _in is It represents the constant pressure specific heat [J / kg] of the substance in the cylinder.
q ₁ represents an inflow heat amount [W] per unit time flowing from the front (left side in FIG. 9) minute region into the minute region at the coordinate x (x = i × Δx). The inflow heat quantity q ₁ is a function of the temperature difference (T ^fl _i−1 (t) −T ^fl _i (t)) between the minute regions. The temperature difference increases, the inflow amount of heat q ₁ increases. For the calculation of the inflow heat quantity q ₁ , the thermal conductivity [W / (m · ° C.)] of the substance in the cylinder is used.
q ₂ represents the amount of heat [W] per unit time flowing out from the minute region at the coordinate x (x = i × Δx) to the minute region on the rear (right side in FIG. 9). Outlet heat _{q 2} is a function of the temperature difference between the micro areas _{^{(T fl i (t) -T}} fl i + 1 (t)). The temperature difference increases, the outflow amount of heat q ₂ is increased. For the calculation of the amount of heat released q ₂ , the thermal conductivity [W / (m · ° C.)] of the substance in the cylinder is used.
q ₃ represents the amount of heat [W] flowing from the cylinder 141 per unit time into a minute region at the coordinate x (x = i × Δx). This amount of heat q ₃ is a function of the temperature difference (T _{i, n} (t) −T ^fl _i (t)) between the cylinder internal substance and the cylinder 141. The temperature difference increases, increases the amount of heat q _3. For the calculation of the amount of heat q ₃ , a heat transfer coefficient [W / (m ² · ° C.)] between the substance in the cylinder and the cylinder 141 is used.

The rear end of the cylinder material (coordinate x = m × Δx) temperature ^T _fl m (t) of is kept substantially the same temperature as the outside air temperature _{T a} by the cooling block 161. Therefore, a temperature fixing condition is given as a boundary condition between the rear end of the cylinder material and the outside air. That is, the equation T ^fl _m (t) = T _a is established. The temperature ^T _fl m of the rear end of the cylinder material (t) may be maintained at a higher predetermined temperature _{T c (T c> T a} ) than the outside air temperature _{T a.}

On the other hand, a heat flux boundary condition is given as a boundary condition between the front end (coordinate x = 0) of the substance in the cylinder and the outside air. Therefore, the rate of temperature rise (one-time differentiation of temperature T ^fl ₀ (t)) at the front end (coordinate x = 0) of the substance in the cylinder is the temperature of the minute region, the temperature of the minute region adjacent to the minute region, the outside air heat transfer coefficient between the temperature T _a, cylinder material and the ambient air of ^{[W / (m 2 · ℃} )], the heat transfer coefficient between the cylinder material and cylinder ^{[W / (m 2 · ℃} )] It is determined by.

FIG. 10 is an explanatory diagram of a formula representing heat inflow / outflow in the heating source according to the second embodiment of the present invention. Expression for the inflow and outflow of heat in the heat source H _k, for example the following formula (4) are represented by like. In the equation (4), the temperature distribution is assumed to be uniform in each heating source H _k for simplification of the equation.

上記式（４）中、Ｔ_ｈｋ（ｔ）は加熱源Ｈ_ｋの時刻ｔの温度［℃］、Ｔ_ａは外気の温度［℃］、Ｃ_ｋは加熱源Ｈ_ｋの熱容量［Ｊ／℃］、Ｚ_ｋは加熱源Ｈ_ｋの電気抵抗［Ω］、Ａ_ｋは加熱源Ｈ_ｋの外気との接触面積、ｈ_ｋは加熱源Ｈ_ｋと外気との間の熱伝達係数［Ｗ／（ｍ^２・℃）］、Ｖ_ｋ（ｔ）は時刻ｔにおける加熱源Ｈ_ｋの電圧［Ｖ］を表す。
Ｖ_ｋ（ｔ）^２／Ｚ_ｋは加熱源Ｈ_ｋの出力（単位時間当たりの発熱量）［Ｗ］、ｈ_ｋ×Ａ_ｋ×（Ｔ_ｈｋ−Ｔ_ａ）は加熱源Ｈ_ｋから外気に逃げる単位時間当たりの放熱量［Ｗ］、Ｑ_ｋは加熱源Ｈ_ｋからシリンダ１４１に流れ込む単位時間当たりの入熱量［Ｗ］を表す。
熱伝達係数ｈ_ｋは、加熱源Ｈ_ｋと外気との温度差（Ｔ_ｈｋ（ｔ）−Ｔ_ａ）の関数であってよい。その温度差が大きくなるほど、熱伝達係数_ｈｋが大きくなる。
入熱量Ｑ_ｋは、加熱源Ｈ_ｋと、シリンダ１４１との温度差（Ｔ_ｈｋ（ｔ）−Ｔ_ｉ,０（ｔ））の関数となっている。その温度差が大きくなるほど、入熱量Ｑ_ｋが増える。但し、ｉは、シリンダ１４１の複数の微少領域のうち、加熱源Ｈ_ｋと接する微少領域の座標を表す整数である。

In the above formula (4), T _hk (t) is the temperature [° C.] of the heating source H _k at time t, T _a is the outside air temperature [° C.], and C _k is the heat capacity of the heating source H _k [J / ° C.]. , _{Z k} is the electrical resistance of the heating source _{H k [Ω], a k} is the area of contact with the outside air of the heating source _{H k, h k} is the heat source _{H k} the heat transfer coefficient between the outside air [W / (m ² · ° C.)], V _k (t) represents the voltage [V] of the heating source H _k at time t.
^{_{V k (t) 2 / Z}} k is the output of the heat source _{H k} (the amount of heat generated per unit _{time) [W], h k ×} A k × (T hk -T a) escapes to the outside air from the heating source _{H k} The amount of heat released per unit time [W], Q _k represents the amount of heat input [W] per unit time flowing into the cylinder 141 from the heating source H _k .
The heat transfer coefficient h _k may be a function of _a temperature difference (T _hk (t) −T _a ) between the heating source H _k and the outside air. As the temperature difference increases, the heat transfer coefficient _hk increases.
The amount of heat input Q _k is a function of the temperature difference (T _hk (t) −T _{i, 0} (t)) between the heating source H _k and the cylinder 141. The temperature difference increases, the heat input Q _k increases. Where, i, of the plurality of small regions of the cylinder 141, which is an integer representing the coordinates of the small area in contact with the heat source H _k.

Thus, the heat conduction equation of the cylinder 141 (Equation (2)), the heat conduction equation of the substance in the cylinder (Equation (3)), and the equation (Equation (4)) representing the inflow and outflow of heat in each heating source _Hk . ) Etc., a heat transfer model is created.

The heat transfer model may be reduced in order to reduce calculation time. For example, the heat conduction equation of the cylinder 141 (Equation (2)) and the heat conduction equation of the material in the cylinder (Equation (3)) are linear equations. Can reduce the dimensions. Meanwhile, expression for the inflow and outflow of heat in the heat source H _k (Equation (4)), so is a non-linear equation, and because originally is a low-dimensional, it is not necessary to dimension reduction.

The control device 180 can calculate the temperature T _{i, j} (t) at an arbitrary position of the cylinder 141 at the predetermined time by inputting the output [W] of each heating source H _{k at} the predetermined time to the heat transfer model. Since the number (m + 1) × (n + 1) of the minute regions in the cylinder 141 is significantly larger than the number of temperature sensors S _k (k = 1, 2, 3, 4 in FIG. 4) (four in FIG. 4), the cylinder 141 The detailed temperature distribution at. The output of each heating source H _k may be input to the heat transfer model as an output waveform from the initial time (t = 0) to a predetermined time.

In addition, the control device 180 inputs the output [W] of each heating source H _{k at} a predetermined time to the heat transfer model, whereby the temperature T ^fl _i (t) of the minute region of the substance in the cylinder at the predetermined time, the predetermined time The temperature T _hk (t) of each heating source H _k can also be calculated. Therefore, the detailed temperature distribution inside the cylinder 141 and the temperature of each heating source _Hk are also known. The output of each heating source H _k may be input to the heat transfer model as an output waveform from the initial time (t = 0) to a predetermined time.

Since the heat transfer model is a differential equation, by giving initial values T _{i, j} (t = 0), T ^fl _i (t = 0), T _hk (t = 0), T _{i, j} (t ), T ^fl _i (t), T _hk (t). The initial time (t = 0) may be, for example, the temperature rise start time of the cylinder 141, and the initial values T _{i, j} (t = 0), T ^fl _i (t = 0), and T _hk (t = 0) it may be the same as the temperature _{T a.}

Incidentally, the initial value ^{_{T i, j (t = 0}} ), T fl i (t = 0), T hk (t = 0) may be any known, not be the same as the outside air temperature _{T a} Good. That is, the initial time (t = 0) may not be the temperature increase start time of the cylinder 141.

In this embodiment, since the steady solution of T _{i, j} (t), T ^fl _i (t), and T _hk (t) is solved using the evaluation function, the initial value T _{i, j} (t = 0), T ^fl _i (t = 0) and T _hk (t = 0) may not be known.

Controller 180, the output of the heating source _{H k} to be input to the heat transfer model [W], may be detected due to power meter _{P k} of the heating source _{H k} (see FIG. 4). Based on the actual output waveform of the heating source H _k, so to estimate the temperature, estimation accuracy is good.

Further, the control unit 180, the output of the heating source H _k to be input to the heat transfer model, the control constant of the feedback control model of the heating source H _k (e.g. PID control model) (e.g. proportional gain, integral gain, differential gain) to You may calculate based on. First, the control device 180 determines the temperature of the heating source H _k at a time t + Δt slightly later than the time t from the deviation between the temperature T _{i, j} (t) at the measurement position of the temperature sensor S _k and the set temperature and the control constant. Predict output. Then, the control unit 180, the output of the heating source H _k predicted entered the heat transfer model predicts the temperature of the measurement position of the temperature sensor S _k at time t + Delta] t. Thus, by repeating the prediction of the output of the heating source H _k, the predicted temperature, the controller 180, not just the current temperature and a past temperature, you are possible to predict the future temperature.

Note that the output of the heating source H _k up to now may be detected by the wattmeter P _k , and the future output of the heating source H _k may be predicted using the control constant of the feedback control model.

  The control device 180 creates an evaluation function whose value is improved (decreased) as the difference between the temperature calculated using the heat transfer model at a predetermined position for setting the target temperature in advance and the target temperature set in advance becomes smaller. To do. The evaluation function may be a general one used in the convex optimization problem. The convex optimization problem is that the preset target temperature is below the set temperature at a position within a predetermined distance MZ (see FIG. 2) forward from the rear end (end on the cooling block 161 side) of the cylinder body 141a. Restrictions may be attached. Further, as a constraint condition, a constraint condition that a preset target temperature is equal to or lower than the set temperature at a position behind the rear end of the cylinder body 141a may be added.

The control device 180 solves the optimum solution of the evaluation function (the optimum solution of the temperature in the steady state of each of the heating sources H _{1 to} H ₄ ) by quadratic programming. Next, the control device 180 solves the steady solution of the heat transfer model again using the obtained optimum solution as a boundary condition. Thereby, the optimal steady solution of the temperature distribution inside a cylinder or a cylinder is obtained. Then, with reference to data (x coordinate, y coordinate) indicating the measurement positions of the temperature sensors S _{1 to} S ₄ recorded in advance on the recording medium, the optimum at the measurement positions of the temperature sensors S _{1 to} S ₄ Temperature is required. This optimum temperature is adopted as the target temperature. The control device 180 controls the plurality of heating sources H _{1 to} H ₄ using a target temperature that is an optimum temperature. Therefore, the actual temperature at the predetermined position can be as close as possible to the preset target temperature.

  The control device 180 may display an image of the optimum steady solution of the temperature distribution calculated by the heat transfer model on the display device. The control device 180 may cause the display device to display an image of a preset target temperature distribution.

  As mentioned above, although embodiment of this invention and its modification were demonstrated, this invention is not limited to the said embodiment etc., In the range of the summary of this invention described in the claim, it is various. Modification and replacement are possible.

  For example, in the first embodiment, the thermal diffusion equation for the stationary problem is solved. However, the thermal diffusion equation for the unsteady problem may be solved. In this case, the initial condition may be given in addition to the boundary condition. Good.

  In the first embodiment and the second embodiment, the lower limit value of the temperature is not set at a position within a predetermined distance forward from the rear end (end on the cooling block side) of the cylinder body. As long as there is a range in temperature, a lower limit value of temperature may be set. The lower limit of temperature may be room temperature (25 ° C.), for example.

  In the first embodiment and the second embodiment, since the convex optimization problem with constraints is solved, quadratic programming is used. However, when there is no constraint, the least squares method is used. Good.

  Moreover, in the said 1st Embodiment and the said 2nd Embodiment, although the depth of the groove | channel formed in a screw changes with places, it may be constant.

DESCRIPTION OF SYMBOLS 10 Injection molding machines 21-24 Temperature sensor 30 Mold apparatus 32 Fixed mold 33 Movable mold 40 Injection apparatus 41 Cylinder 41a Cylinder main body 42 Nozzle 61 Cooling block (cooling part)
80 Controllers 91-94 Heater (heating source)

Claims (8)

A cylinder supplied with resin material;
A plurality of heating sources for heating the cylinder;
A plurality of temperature sensors for detecting temperatures at different positions of the cylinder;
A controller for controlling the plurality of heating sources based on a difference between a measured temperature of each temperature sensor and a target temperature at a measurement position of each temperature sensor;
The target temperature distribution in the cylinder axial direction of the cylinder inner wall is preset,
The control device calculates a target temperature at a measurement position of each temperature sensor based on the target temperature distribution, and controls the plurality of heating sources using the calculated target temperature. Molding machine. A cylinder supplied with resin material;
A plurality of heating sources for heating the cylinder;
A plurality of temperature sensors for detecting temperatures at different positions of the cylinder;
A controller for controlling the plurality of heating sources based on a difference between a measured temperature of each temperature sensor and a target temperature at a measurement position of each temperature sensor;
A target temperature at a predetermined position in the cylinder and / or the cylinder is preset,
The control device calculates a target temperature at a measurement position of each temperature sensor based on the preset target temperature, and controls the plurality of heating sources using the calculated target temperature. And injection molding machine.   The injection molding machine according to claim 1 or 2, wherein the number of positions where the target temperature is set in advance is larger than the number of the temperature sensors arranged at intervals in the cylinder axis direction. A cooling section for cooling one end of the cylinder;
A nozzle provided at the other end of the cylinder,
The cylinder includes a cylinder main body extending between the cooling unit and the nozzle, and the cylinder main body is provided with the plurality of heating sources and the plurality of temperature sensors.
4. The upper limit value of the temperature is set as the preset target temperature at a position within a predetermined distance from the end of the cylinder main body on the cooling unit side to the nozzle side. The injection molding machine described in 1.   5. The injection molding machine according to claim 4, wherein the target temperature at the measurement position of each temperature sensor is calculated using a heat transfer model capable of calculating the temperature distribution of the cylinder body based on the temperature of each heating source. .   The injection molding machine according to claim 5, wherein the size of the cylinder body and the thermal diffusivity are used for calculating the target temperature at the measurement position of each temperature sensor.   For calculation of the target temperature at the measurement position of each temperature sensor, the heat transfer coefficient between the cylinder body and each heating source, the heat transfer coefficient between the cylinder body and the outside air, the outside air The heat transfer coefficient between the cylinder main body and the resin in the cylinder main body, the temperature of the resin in the cylinder main body, and the temperature of the end of the cylinder main body on the cooling unit side are used. The injection molding machine described in 1.   The control device obtains an optimal solution of an evaluation function that improves as the difference between the temperature calculated using the heat transfer model at the position where the target temperature is set in advance and the preset target temperature is smaller. The injection molding machine according to any one of claims 5 to 7, wherein a target temperature at a measurement position of each temperature sensor is calculated by solving by a quadratic programming method.

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