Extrusion molding device

Abstract

This extrusion molding device (100) discharges a molten resin from a lip opening (152) in which a movable lip (115) of a first block (111) and a fixed lip (116) of a second block (112) are formed so as to face each other, and molds the discharged molten resin into a film shape, the extrusion molding device comprising: a plurality of studs (121), the tips of which are fixed to the movable lip (115), and which are provided to the first block (111); a plurality of actuators (122) capable of advancing / retracting the studs (121) via the rotational motion of motors; a plurality of detection units that detect the operational status of the motors included in the respective actuators (122); and a control unit that causes the studs (121) corresponding to the respective actuators (122) to be advanced / retracted. When the control unit causes a specific first stud (121a) to be advanced / retracted, the control unit generates a correction control amount for a second stud (121b) adjacent to the specific first stud (121a) in accordance with the detection result of the detection unit, and causes the second stud (121b) to be advanced / retracted on the basis of the correction control amount.

Description

Extrusion molding equipment

[0001] The present invention relates to an extrusion molding apparatus.

[0002] An extrusion molding device using a T-die is known for molding heated molten resin into a film. The extrusion molding device extrudes molten resin supplied from an extruder through a lip opening of the T-die to form a resin film (see, for example, Patent Document 1). The extrusion molding device adjusts the width of the lip opening to ensure a uniform thickness of the resin film.

[0003] The width of the lip opening can be adjusted by heat bolts arranged in a row along the longitudinal direction of the lip opening. The heat bolts are metal rods with built-in heaters that expand thermally when heated by the heaters, thereby changing the width of the lip opening. The extrusion molding device can adjust the amount of expansion of each heat bolt by individually controlling the amount of current applied to each heater. This allows the width of the lip opening to be locally adjusted on a heat bolt-by-heat bolt basis. The width of the lip opening is adjusted by measuring the film thickness of the resin film extruded and molded through the lip opening and changing the amount of expansion of each heat bolt based on the measurement results.

[0004] Patent Publication No. 2013-052574

[0005] However, when adjusting the expansion amount of the heat bolt, in addition to changing the amount of current supplied to the heater, factors such as the temperature and viscosity of the molten resin, as well as the responsiveness of the heat bolt to reach the desired temperature after changing the amount of current supplied to the heater, must be considered. Therefore, the accuracy of the resin film thickness uniformity work is maintained by the experience and know-how of the technician, and even experienced technicians require time to achieve a uniform thickness. Therefore, there is a need for an extrusion molding device used in the T-die method that makes it easier to adjust the resin film thickness, shortens the work time for skilled technicians, and enables inexperienced technicians to perform the work.

[0006] The present invention has been made in consideration of these problems, and its object is to provide an extrusion molding apparatus that forms a resin film by the T-die method, and that can easily adjust the film thickness of the resin film.

[0007] In other words, the present invention is an extrusion molding device in which a flow path for extruded molten resin is formed by opposing a first block and a second block, and the molten resin is extruded from a lip opening formed by opposing the movable lip of the first block and the fixed lip of the second block to form a film, the device comprising: a plurality of studs whose tips are fixed to the movable lip and arranged in the length direction of the lip opening on the first block; a plurality of actuators connected to each stud, each equipped with a motor, and capable of advancing and retracting the studs by the rotational movement of the motor; a plurality of detection units that detect the operating status of the motor included in each actuator; and a control unit that controls each actuator and advances and retracts the stud corresponding to each actuator, wherein when a specific first stud is advanced or retracted by the actuator, the control unit generates a correction control amount for a second stud adjacent to the specific first stud in accordance with the detection result of the detection unit, and advances and retracts the second stud based on the correction control amount.

[0008] According to the extrusion molding device of the present invention, when a specific first stud is advanced or retracted by an actuator, a correction control amount for a second stud adjacent to the first stud can be generated based on feedback information from the detection. The control unit can then advance or retract the second stud based on this correction control amount. Therefore, the extrusion molding device 100 can advance or retract the second stud adjacent to the first stud by an appropriate amount depending on the operating status of the motor for the first stud. Therefore, even in an extrusion molding device with narrow spacing between studs 121, the first stud 121a can operate normally while reducing the load on the motor. Therefore, the extrusion molding device 100 can easily adjust the width of the lip opening 152, facilitating adjustment of the film thickness of the resin film.

[0009] 1 is a perspective view of an extrusion molding apparatus according to one embodiment of the present invention; FIG. 2 is a cross-sectional view of an extrusion molding apparatus according to one embodiment of the present invention when observed from the side; FIG. 3 is a block diagram showing a control system of an extrusion molding apparatus according to one embodiment of the present invention; FIG. 4 is an enlarged perspective view of a portion of an extrusion molding apparatus according to one embodiment of the present invention;

[0010] The extrusion molding apparatus of the present invention will be described in detail below with reference to the accompanying drawings.

[0011] FIG. 1 is a perspective view of an extrusion molding apparatus 100 according to one embodiment of the present invention. The extrusion molding apparatus 100 is used to extrude molten resin to form a resin film or the like. The extrusion molding apparatus 100 includes a die 110 that discharges molten resin from a lip opening 152, multiple opening adjustment units 120 that adjust the opening width of the lip opening 152, multiple detection units (not shown) that detect the operating status of a motor, a control unit (not shown) that controls the opening adjustment units 120, and a film thickness meter that measures the film thickness of the resin film discharged from the die 110 and molded. The resin film discharged from the lip opening 152 is wound into a roll by a winding device. The film thickness of the resin film discharged from the lip opening 152 is measured by the film thickness meter, and a digital signal generated as a result of this measurement is input to the control unit. Note that, in this specification, the term "resin film" is used to refer to a resin sheet as well.

[0012] 2 is a cross-sectional view of an extrusion molding apparatus 100 according to one embodiment of the present invention, as viewed from the side. The die 110 has a first block 111 and a second block 112. The first block 111 and the second block 112 are arranged opposite each other. A flow path 150 for molten resin supplied to the die 110 from an extruder 140 provided at one end 130 of the first block 111 and the second block 112 is formed on the opposing surface between the first block 111 and the second block 112. The flow path 150 has an inlet 151 at one end for receiving the molten resin extruded from the extruder 140 and a lip opening 152 at the other end for discharging the molten resin that has flowed through the flow path 150.

[0013] The flow path 150 has an inlet flow path 153 extending from the receiving port 151 toward the lip opening 152, a manifold 154 communicating with the inlet flow path 153, and a discharge flow path 155 communicating from the manifold 154 toward the lip opening 152. The molten resin supplied from the extruder 140 to the receiving port 151 is introduced into the inlet flow path 153.

[0014] The manifold 154 is for spreading the molten resin introduced into the inlet flow path 153 along the width direction of the die 110, and extends toward the width direction of the die 110. Here, the width direction of the die 110 is the front-to-rear direction on the paper surface in Figure 2, which is the same direction as the longitudinal direction of the lip opening 152. As a result, the molten resin that has flowed into the manifold 154 is spread toward the width direction of the die 110.

[0015] A discharge flow path 155 is formed between the manifold 154 and the lip opening 152. The discharge flow path 155 extends in the width direction of the die 110, similar to the manifold 154. The discharge flow path 155 is formed as a passage smaller than the manifold 154. The molten resin that has passed through the discharge flow path 155 is discharged from the lip opening 152.

[0016] The first block 111 has an inclined surface 113 at the other end 131, and the second block 112 has an inclined surface 114 at the other end 131. The inclined surface 113 has a recess 118 for connection with a stud 121, which will be described later. The inclined surface 113 of the first block 111 and the inclined surface 114 of the second block 112 are inclined toward the lip opening 152, so that the die 110 has a shape that narrows toward the other end 131. A movable lip 115 is provided at the tip of the inclined surface 113, while a fixed lip 116 is provided at the tip of the inclined surface 114. The lip opening 152 is composed of the movable lip 115 and the fixed lip 116, and the opening width of the lip opening 152 is determined by the distance between the movable lip 115 and the fixed lip 116.

[0017] The other end 131 of the first block 111 is provided with a hole 117 penetrating in the width direction of the die 110. The hole 117 is located near the movable lip 115 and closer to the one end 130 than the movable lip 115. The hole 117 is formed continuously with the movable lip 115. As a result, a thin-walled portion 156 is formed between the hole 117 and the discharge flow path 155, and the movable lip 115 is elastically deformable with the thin-walled portion 156 as a fulcrum. The first block 111 is also provided with a fixing member 119 formed continuously in the width direction of the die 110. The fixing member 119 has a holder portion 126 that rotatably holds a rod 123 (described later) and a convex guide portion 127. The guide portion 127 extends in the direction in which a stud 121 (described later) advances and retreats.

[0018] 1 , the plurality of opening adjustment units 120 are arranged side by side on a fixed member 119 of the first block 111. The opening adjustment units 120 are used to adjust the opening width of the lip opening 152, and include studs 121 for pushing and pulling the movable lip 115, and actuators 122 for moving the studs 121 back and forth. That is, the extrusion molding device 100 includes a plurality of studs 121 arranged side by side in the length direction of the lip opening 152 and provided on the first block 111, and a plurality of actuators 122 connected to each stud 121.

[0019] One end of the stud 121 is fixed to the movable lip 115, and the other end is connected to the actuator 122. The other end of the stud 121 is formed with a female thread portion 132 for connecting the stud 121 to the actuator 122. The stud 121 is arranged with its axis facing the lip opening 152. One end of the stud 121 is provided with a recess 124 for fixing the stud 121 to the movable lip 115. A U-shaped connecting member 125 is fitted into the recess 124 and the recess 118 of the inclined surface 113. In this way, the movable lip 115 and the stud 121 are connected.

[0020] A linear guide 128 is provided on the other end of the stud 121, and the stud 121 is connected to a fixed part 119 via the linear guide 128. The linear guide 128 guides the stud 121 in the axial direction. This allows the stud 121 to move freely in the axial direction in response to the input from the actuator 122.

[0021] The actuator 122 includes a motor and a rod 123 to which rotation of the motor is applied. The rod 123 is rotatably held in a holder portion 126 of the fixing member 119. A male thread portion 129 is formed at the tip of the rod 123. The male thread portion 129 is threaded into a female thread portion 132 provided at the other end of the stud 121, connecting the actuator 122 and the stud 121. As a result, when rotation of the motor is applied to the rod 123, the rod 123 rotates, and the stud 121 can move along the axial direction of the stud 121 by a distance corresponding to the amount of rotation of the rod.

[0022] In this way, by rotating the motor, the actuator 122 can move the stud 121 in the axial direction of the stud 121 according to the rotation amount of the motor. This axial movement of the stud 121 is transmitted to the movable lip 115 connected to the stud 121. As a result, the actuator 122 can push or pull the movable lip 115 by any amount, and the extrusion molding device 100 can locally adjust the width of the lip opening 152 for each actuator 122. In this case, the movable lip 115 moves around the thin-walled portion 156 as a fulcrum. Note that, although the actuators 122 of the extrusion molding device 100 shown in FIG. 1 are arranged in parallel along the length of the lip opening 152, this is not limiting and the actuators 122 may be arranged in a staggered pattern. By arranging the actuators 122 in a staggered pattern, the arrangement pitch of the actuators 122 can be reduced.

[0023] A detection unit is built into each actuator 122 and can detect the operating status of the motor. The operating status is the state of the motor when it is rotated, such as the torque and rotation amount of the motor. The extrusion molding device 100 of this embodiment has, as a detection unit, a rotary encoder that measures the rotation amount of the motor and a torque sensor that measures the torque applied to the motor. Therefore, the extrusion molding device 100 can detect the operating status of the motor using the rotary encoder and torque sensor. Digital signals generated by the rotary encoder and torque sensor are output to the control unit. Note that the detection unit is not limited to a rotary encoder and a torque sensor.

[0024] The control unit is realized by a microcontroller with built-in RAM and ROM, and can take in digital signals from the detection unit and digital signals from the film thickness gauge. The control unit executes a control program stored in the ROM to generate drive signals for controlling the amount of rotation of the motors of each actuator 122, and outputs the drive signals to a driver circuit. This allows the control unit to control the motors of each actuator 122 and adjust the amount of advance and retreat of the stud 121.

[0025] FIG. 3 is a block diagram showing the control system of the extrusion molding apparatus 100 of this embodiment. The control unit can operate a specific actuator 122 based on the measurement results from the film thickness meter, thereby moving a specific stud 121 connected to the specific actuator 122 forward and backward. The film thickness meter can measure the film thickness of the resin film extruded from the lip opening 152 at any interval along its width, allowing the film thickness distribution of the entire resin film to be grasped. If the film thickness distribution measured as a result of the measurement is uneven beyond the allowable range, the width of the lip opening 152 can be locally adjusted for each stud 121 by moving the specific stud 121 forward and backward. The control unit can also change the control amount for the motor of the actuator 122 based on the viscosity of the resin material of the resin film to be molded. This allows the control unit to achieve uniformity in the resin film to be molded.

[0026] The control unit generates a control amount for each actuator 122 based on the film thickness distribution, and can advance and retract each stud 121 corresponding to each actuator 122 based on this control amount. In this case, when operating a specific stud 121, the control amount for the actuator 122 applied to a stud 121 adjacent to the specific stud 121 can be generated based on the control amount for the specific stud 121. The relationship between the control amount for the first actuator 122a and the control amount for the second actuator 122b can be determined by setting the respective control amounts to the same or approximately the same value, or by increasing or decreasing the value of one of the control amounts. This allows the control unit to operate the studs 121 adjacent to the specific stud 121 together with the specific stud 121, thereby optimizing the amount of advance and retraction between the adjacent studs 121.

[0027] For example, as shown in Figure 4, when the control amount of the first actuator 122a is large, the control amount of the second actuator 122b adjacent to the first actuator 122a can be set to approximately the same value as the control amount of the first actuator 122a or to a value smaller than the control amount of the first actuator 122a. Because the lip opening 152 is continuous and extends in the width direction of the die 110, adjusting only a specific stud may make it difficult to adjust the resin film thickness or may place excessive strain on the actuator 122. However, by controlling in this manner, it becomes easier to adjust the resin film thickness and the load on the machine can be reduced. In particular, when the spacing between the studs 121 is narrowed to improve the molding accuracy of the resin film, reducing the load on the motor of the actuator 122 can prevent damage to the actuator 122.

[0028] The control unit can also set the amount of advancement and retraction of the second stud 121b to be smaller than the amount of advancement and retraction of the first stud 121a. For example, the amount of advancement and retraction of the second stud 121b can be set to half the amount of advancement and retraction of the first stud 121a. This facilitates more appropriate width adjustment of the lip opening 152. The second studs 121b are located on both sides of the first stud 121a, and both studs may be operated, or only one of them may be operated.

[0029] Furthermore, the control unit can generate a control amount for the third actuator 122c adjacent to the second actuator 122b based on the control amount for the first actuator 122a and the control amount for the second actuator 122b. Therefore, the control unit can operate the third actuator 122c adjacent to the second actuator 122b in conjunction with the operation of the first actuator 122a and the second actuator 122b. As a result, when the first stud 121a and the second stud 121b are advanced or retracted, the third stud 121c adjacent to the second stud 121b can be advanced or retracted in conjunction with the advancement or retraction of the first stud 121a and the second stud 121b. The amount of advancement or retraction of the third stud 121c can be smaller than that of the second stud 121b.

[0030] When advancing or retracting a specific first stud 121a based on the film thickness distribution measured by the film thickness meter, the control unit can generate a correction control amount for the second actuator 122b adjacent to the first actuator 122a in accordance with the detection result of the detection unit. The correction control amount is a value obtained by correcting the control amount for the second actuator 122b generated based on the measurement result of the film thickness meter based on the operating status of the motor applied to the first actuator 122a. The control unit can advance or retract the second stud 121b corresponding to the actuator 122b based on the correction control amount. In other words, the control unit can recognize the operating status of the motor through feedback information from the detection unit and operate the stud adjacent to the specific stud accordingly.

[0031] When the torque sensor detects the torque applied to the motor of the first actuator 122a, the detection result is input to the control unit. The control unit compares the detected torque value with a preset torque threshold and, if the detected torque value exceeds the threshold, generates a correction control amount for the second actuator 122b. That is, if the torque sensor detects that the motor of the first actuator 122a connected to the first stud 121a is generating torque exceeding a reference value, the control unit can advance and retract the second stud 121b adjacent to the first stud 121a by an amount corresponding to the correction control amount. In this way, when the extrusion molding device 100 controls the first actuator 122a based on a digital signal from a film thickness gauge, it can correct the control amount of the second actuator 122b based on a digital signal from the torque sensor. This allows the first stud 121a to operate normally while reducing the load on the motor, even in an extrusion molding device with narrow stud-to-stud spacing, and makes it easy to adjust the width of the lip opening 152.

[0032] Even if the rotary encoder detects that the motor of the first actuator 122a connected to the first stud 121a is not receiving the rotation amount input from the control unit, a corrective control amount can be generated for the second actuator 122b adjacent to the first actuator 122a. This allows the second stud 121b adjacent to the first stud 121a to advance and retreat, and the amount of motor rotation applied to the first stud 121a to approach the rotation amount input from the control unit as closely as possible. This allows the first stud 121a to operate normally, and the width of the lip opening 152 can be easily adjusted.

[0033] Furthermore, when advancing and retracting the first stud 121a and the second stud 121b in response to the detection results of the detection unit, the control unit can set a correction control amount for the second actuator 122b smaller than that for the first actuator 122a. That is, the amount of advancement and retraction of the second stud 121b can be set smaller than that of the first stud 121a. This may result in smoother movement of the movable lip 152. The second studs 121b are located on both sides of the first stud 121a, and both second studs 121b may be operated, or only one of them may be operated. Furthermore, when generating a correction control amount for the second actuator 122b, the control unit can also generate a correction control amount for the third actuator 122c adjacent to the second actuator 122b. As a result, when the control unit advances and retreats the first stud 121a and the second stud 121b, it can also advance and retreat the third stud 121c adjacent to the second stud 121b in conjunction with the advance and retreat of the first stud 121a and the second stud 121b. The amount of advance and retreat of the third stud 121c can be made smaller than that of the second stud 121b. By operating the third stud 121c in addition to the second stud 121b in conjunction with the advance and retreat of the first stud 121a, it is possible to adjust the thickness of the resin film more precisely.

[0034] As described above, when the extrusion molding device 100 operates a specific first actuator 122a based on the measurement results of the film thickness meter, it can generate a correction control amount for the second actuator 122b adjacent to the first actuator 122a or the third actuator 122c adjacent to the second actuator 122b based on feedback information from the detection unit. The control unit of the extrusion molding device 100 controls the second actuator 122b or the third actuator 122c based on the correction control amount, thereby advancing or retracting the second stud 121b or the third stud 121c. This allows the extrusion molding device 100 to advance or retract the stud adjacent to the first stud by an appropriate amount depending on the operating status of the motor applied to the first stud. Even in an extrusion molding device with narrow spacing between the studs 121, the first stud 121a can be operated normally while reducing the load on the motor, making it easy to adjust the width of the lip opening 152.

[0035] Furthermore, when the spacing between the actuators 122 arranged along the width of the lip opening 152 is narrow, forcibly moving only a specific stud 121a forward or backward can easily generate torque on the motor acting on that specific stud 121, potentially resulting in problems such as the motor not being able to achieve the rotational speed required by the control unit. The extrusion molding device 100 according to one embodiment of the present invention moves the second stud 121b adjacent to the first stud 121a and the third stud 121c adjacent to the second stud 121b forward or backward in conjunction with a specific first stud 121a, thereby enabling smoother movement of the movable lip 152 compared to when only the first stud 121a is forcibly moved forward or backward. Therefore, the extrusion molding device 100 can easily adjust the width of the lip opening 152 even when the arrangement pitch of the actuators 122 is small.

Claims

1. An extrusion molding device (100) in which a flow path (150) for extruded molten resin is formed by opposing a first block (111) and a second block (112), and the molten resin is extruded from a lip opening (152) formed by opposing a movable lip (115) of the first block (111) and a fixed lip (116) of the second block (112) to form a film, the extrusion molding device comprising: a plurality of studs (121) whose tips are fixed to the movable lip (115) and arranged in the longitudinal direction of the lip opening (152) and provided on the first block (111); a plurality of actuators (122) connected to each stud (121), each actuator having a motor and capable of advancing and retracting the studs (121) by the rotational motion of the motor; a plurality of detectors for detecting the operating status of the motor included in each actuator (122); and a control unit for controlling each actuator (122), advancing and retracting the stud (121) corresponding to each actuator (122), and receiving the operating status from the detector. wherein, when a specific first stud (121a) is advanced or retreated by the actuator (122), the control unit generates a correction control amount for a second stud (121b) adjacent to the specific first stud (121a) in accordance with the operating status of the specific first stud (121a), and advances or retreats the second stud (121b) based on the correction control amount.

2. The extrusion molding device (100) according to claim 1, wherein the operating condition is the torque of the motor.

3. The extrusion molding device (100) of claim 2, characterized in that the control unit receives the value of the motor torque applied to the specific first stud (121a) from the detection unit, generates the corrective control amount based on the result of comparing the torque value with a predetermined torque threshold, and then advances and retreats the second stud (121b).

4. The extrusion molding device (100) according to claim 1 or 2, characterized in that the operating condition is the amount of rotation of the motor.

5. The extrusion molding apparatus (100) according to claim 1, characterized in that the amount of movement of the second stud (121b) is less than the amount of movement of the first stud (121a).

6. The extrusion molding device (100) of claim 1, characterized in that the control unit generates a correction control amount for a third stud (121c) adjacent to the second stud (121b) in conjunction with the generation of a correction control amount for the second stud (121b), and moves the third stud (121c) forward and backward based on the correction control amount.

7. The extrusion molding device (100) according to claim 1, characterized in that the control unit changes the amount of control over the motor in accordance with the viscosity of the molten resin.

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