JP6404081B2 - Injection molding machine - Google Patents

Description

  The present invention relates to an injection molding machine.

  The injection molding machine includes a mold opening / closing device that performs mold closing and opening of the mold device, an injection device that fills a cavity space of the mold device with a molding material, a mold opening / closing device, a controller that controls the injection device, and the like. 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.

  According to Patent Document 1, the position of the movable mold is held so that the gap between the fixed mold and the movable mold is fixed at least during the filling process. Thereby, the degassing of the cavity space can be improved as compared with the case where the mold is closed without a gap between the fixed mold and the movable mold from the start of the filling process to the completion of the cooling process.

JP 2007-118349 A

  In recent years, it has been strongly desired to shorten the molding cycle time in order to improve productivity.

  This invention is made | formed in view of the said subject, Comprising: It aims at provision of the injection molding machine which can shorten a molding cycle time.

In order to solve the above problems, according to one aspect of the present invention,
A mold opening and closing device for opening and closing the fixed mold and the movable mold;
An injection device that fills a cavity space formed between the fixed mold and the movable mold with a molding material;
A controller for controlling the mold opening and closing device and the injection device,
The mold opening and closing device is
A platen part to which one of the fixed mold and the movable mold is attached;
A support portion coupled with the platen portion at an interval;
A toggle mechanism supported by the support;
A drive unit for moving the movable mold by operating the toggle mechanism unit;
A mold thickness adjusting unit that adjusts an interval between the platen unit and the support unit;
The controller is
In a state where the movable mold is in a position before the contact position with the fixed mold, the mold closing process by the mold opening and closing device and the pressure holding process by the injection apparatus are completed,
In the middle of the mold closing process, in a state where the movable mold is at a position further before the position at the completion of the mold closing process, the filling process by the injection device is started ,
An injection molding machine is provided that sets the bending / extending state of the arm of the toggle mechanism based on the load of the driving unit .

  According to one aspect of the present invention, an injection molding machine that can shorten the molding cycle time is provided.

It is a figure which shows the state at the time of mold opening completion of the injection molding machine by one Embodiment of this invention. It is a figure which shows the state at the time of the completion | finish of mold closing of the injection molding machine by one Embodiment of this invention. It is a figure which shows the position change of the crosshead by one Embodiment of this invention.

  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.

  FIG. 1 is a view showing a state at the completion of mold opening of an injection molding machine according to an embodiment of the present invention. FIG. 2 is a view showing a state at the completion of mold closing of the injection molding machine according to the embodiment of the present invention. The injection molding machine includes a frame Fr, a mold opening / closing device 10, an injection device 40, a controller 70, and an output device 80.

  The mold opening / closing device 10 performs mold closing and mold opening of the mold device 30. The mold apparatus 30 includes a fixed mold 32 and a movable mold 33.

  The mold opening / closing device 10 includes a fixed platen 12, a movable platen 13, a toggle support 15, a tie bar 16, a toggle mechanism 20, a mold opening / closing motor 21, and a mold thickness adjusting mechanism 23. In the description of the mold opening and closing device 10, the moving direction of the movable platen 13 when the mold is closed (right direction in FIGS. 1 and 2) is the front, and the moving direction of the movable platen 13 when the mold is opened (left in FIGS. 1 and 2). (Direction) will be described as the rear.

  The stationary platen 12 is fixed with respect to the frame Fr. A fixed mold 32 is attached to a surface of the fixed platen 12 facing the movable platen 13.

  The movable platen 13 is movable along a guide (for example, a guide rail) 17 laid on the frame Fr, and is movable forward and backward with respect to the fixed platen 12. A movable mold 33 is attached to the surface of the movable platen 13 facing the fixed platen 12.

  By moving the movable platen 13 back and forth with respect to the fixed platen 12, the mold apparatus 30 is closed and opened.

  The toggle support 15 is connected to the fixed platen 12 at an interval, and is placed on the frame Fr so as to be movable in the mold opening / closing direction. The toggle support 15 may be movable along a guide laid on the frame Fr. The guide of the toggle support 15 may be the same as the guide 17 of the movable platen 13.

  In this embodiment, the fixed platen 12 is fixed to the frame Fr, and the toggle support 15 is movable in the mold opening / closing direction with respect to the frame Fr. However, the toggle support 15 is fixed to the frame Fr. The fixed platen 12 may be movable in the mold opening / closing direction with respect to the frame Fr.

  The tie bar 16 connects the fixed platen 12 and the toggle support 15 with an interval. The tie bar 16 is parallel to the mold opening / closing direction. There may be a plurality of tie bars 16 (for example, four).

  The toggle mechanism 20 is disposed between the movable platen 13 and the toggle support 15 and is supported by the toggle support 15. The toggle mechanism 20 includes a cross head 20a and a plurality of links 20b and 20c. One link 20b is swingably attached to the movable platen 13, and the other link 20c is swingably attached to the toggle support 15. These links 20b and 20c are connected so as to be able to bend and stretch with pins or the like. By advancing and retracting the cross head 20 a, the arm composed of the plurality of links 20 b and 20 c is bent and extended, and the movable platen 13 is advanced and retracted with respect to the toggle support 15.

  The mold opening / closing motor 21 is attached to the toggle support 15 and moves the movable platen 13 forward and backward by moving the cross head 20a forward and backward. Between the mold opening / closing motor 21 and the cross head 20a, there is provided a motion conversion mechanism that converts the rotational movement of the mold opening / closing motor 21 into a linear motion and transmits it to the cross head 20a. The motion conversion mechanism is constituted by, for example, a ball screw mechanism. The mold opening / closing motor 21 has an encoder 21a. The encoder 21 a detects the rotation angle of the output shaft of the mold opening / closing motor 21 and outputs a signal indicating the rotation angle to the controller 70.

  The operation of the mold opening / closing device 10 is controlled by the controller 70. The controller 70 controls a mold closing process, a mold opening process, and the like.

  In the mold closing process, the mold opening / closing motor 21 is driven to move the movable platen 13 forward, so that the movable mold 33 approaches the fixed mold 32. When the mold closing process is completed, a predetermined gap 35 is formed between the fixed mold 32 and the movable mold 33. In this state, a cavity space 34 is formed between the movable mold 33 and the fixed mold 32, and the cavity space 34 is filled with a liquid molding material. The gas in the cavity space 34 passes through the gap 35, but the size of the gap 35 is set so that the molding material in the cavity space 34 does not leak from the gap 35 to the outside. The molding material in the cavity space 34 is solidified and becomes a molded product.

  In the mold opening process, the movable mold 33 is separated from the fixed mold 32 by driving the mold opening / closing motor 21 to retract the movable platen 13. After completion of the mold opening process, the molded product is ejected from the movable mold 33.

  The mold thickness adjusting mechanism 23 adjusts the distance between the fixed platen 12 and the toggle support 15. The mold thickness adjusting mechanism 23 includes a male screw 24, a female screw 25, and a mold thickness motor 26.

  The male screw 24 is formed at the rear end of each tie bar 16. The female screw 25 is screwed with the corresponding male screw 24 and is rotatably held by the toggle support 15.

  The mold thickness motor 26 adjusts the relative position between each tie bar 16 and the toggle support 15 by rotating each female screw 25 and adjusts the distance between the fixed platen 12 and the toggle support 15.

  The mold thickness motor 26 has an encoder 26a. The encoder 26 a detects the interval between the fixed platen 12 and the toggle support 15 by detecting the rotation angle of the output shaft of the mold thickness motor 26, and outputs a signal indicating the interval to the controller 70.

  The male screw 24 may be formed at the front end of each tie bar 16, and the female screw 25 may be rotatably held by the fixed platen 12. By rotating each female screw 25, the relative position between the fixed platen 12 and each tie bar 16 can be adjusted, and the distance between the fixed platen 12 and the toggle support 15 can be adjusted.

  The injection device 40 is installed on a slide base Sb that can move forward and backward with respect to the frame Fr, and can move forward and backward with respect to the mold device 30. The injection apparatus 40 is touched by the mold apparatus 30 and fills the mold apparatus 30 with a molding material.

  The injection device 40 includes, for example, a cylinder 41, a screw 43, a metering motor 45, an injection motor 46, and a pressure detector 47. In the description of the injection device 40, unlike the description of the mold opening / closing device 10, the moving direction of the screw 43 during filling (left direction in FIGS. 1 and 2) is the front, and the moving direction of the screw 43 during weighing (see FIGS. 1 and 2). In the following description, the right direction in FIG.

  The cylinder 41 heats the molding material supplied from the supply port 41a. The supply port 41 a is formed at the rear part of the cylinder 41. A heating source such as a heater is provided on the outer periphery of the cylinder 41.

  The screw 43 sends out the molding material in the cylinder 41. The screw 43 is disposed in the cylinder 41 so as to be rotatable and movable back and forth.

  The metering motor 45 rotates the screw 43 to feed the molding material forward along the spiral groove of the screw 43. The molding material is gradually melted by the heat from the cylinder 41 while being fed forward. As the liquid molding material is fed to the front of the screw 43 and accumulated in the front portion of the cylinder 41, the screw 43 is retracted.

  The injection motor 46 advances the screw 43 to fill the cavity space 34 of the mold apparatus 30 with the liquid molding material accumulated in front of the screw 43. Thereafter, the injection motor 46 pushes the screw 43 forward and applies pressure to the molding material in the cavity space 34. Insufficient molding material can be replenished. Between the injection motor 46 and the screw 43, a motion conversion mechanism that converts the rotational motion of the injection motor 46 into the linear motion of the screw 43 is provided.

  The pressure detector 47 is disposed between the injection motor 46 and the screw 43, for example, and detects the pressure acting on the screw 43 from the molding material, the back pressure on the screw 43, and the like. The pressure acting on the screw 43 from the molding material corresponds to the pressure acting on the molding material from the screw 43, as is apparent from the law of action and reaction.

  The operation of the injection device 40 is controlled by the controller 70. The controller 70 controls a filling process, a pressure holding process, a weighing process, and the like.

  In the filling process, the injection motor 46 is driven to advance the screw 43 at a set speed, and the liquid molding material accumulated in front of the screw 43 is filled into the mold apparatus 30. The set speed of the screw 43 may be changed stepwise according to the position of the screw 43. The position and speed of the screw 43 are detected by an encoder 46a of the injection motor 46, for example. When the screw 43 moves forward to the V / P switching position, the pressure holding process is started. Note that when the elapsed time after the screw 43 reaches the speed switching position reaches a predetermined time, the pressure holding process may be started. When the screw 43 reaches the speed switching position, the screw 43 may be advanced at a slow speed, stopped, or retracted at a slow speed.

  In the pressure holding process, the injection motor 46 is driven to push the screw 43 forward with a set pressure, and pressure is applied to the molding material in the mold apparatus 30. Insufficient molding material can be replenished. The pressure of the molding material is detected by a pressure detector 47, for example. After completion of the pressure holding process, the cooling process is started.

  In the cooling process, the molding material in the cavity space 34 is solidified. When the elapsed time from the completion of the pressure holding process reaches a predetermined time, the cooling process is completed. In order to shorten the molding cycle time, a metering step may be performed during the cooling step.

  In the metering step, the metering motor 45 is driven to rotate the screw 43 at a set rotational speed, and the molding material is fed forward along the spiral groove of the screw 43. Along with this, the molding material is gradually melted. As the liquid molding material is fed to the front of the screw 43 and accumulated in the front portion of the cylinder 41, the screw 43 is retracted. The number of rotations of the screw 43 is detected by, for example, the encoder 45a of the measuring motor 45.

  In the measuring step, the set back pressure may be applied to the screw 43 by driving the injection motor 46 in order to limit the rapid retreat of the screw 43. The back pressure with respect to the screw 43 is detected by a pressure detector 47, for example. When the screw 43 is retracted to a predetermined position and a predetermined amount of molding material is accumulated in front of the screw 43, the measuring step is finished.

  The controller 70 includes a central processing unit (CPU) 71 and a storage medium 72 such as a memory. The controller 70 controls the mold opening / closing device 10 and the injection device 40 by causing the CPU 71 to execute a program stored in the storage medium 72.

  FIG. 3 is a diagram showing a change in the position of the crosshead according to the embodiment of the present invention. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the position of the crosshead. The position of the cross head 20 a represents the position of the movable platen 13 and the position of the movable mold 33. Therefore, in the description of FIG. 3, the position of the cross head 20 a may be read as the position of the movable platen 13 or the position of the movable mold 33.

Controller 70, at time _{t 0,} and starts the mold closing step. After the mold closing process is started, the cross head 20a is advanced at a set speed. The set speed may be changed in stages according to the position of the crosshead 20a and the like. The controller 70 monitors the speed and position of the crosshead 20a during the mold closing process. The monitoring, for example in type encoder 21a of the opening and closing motor 21 type closing process as in the middle used time t _1, when the position of the crosshead 20a reaches a predetermined position, the controller 70 initiates the filling process. After the start of the filling process, the screw 43 is advanced at a set speed. The set speed may be changed stepwise according to the position of the screw 43 or the like. The controller 70 monitors the speed and position of the screw 43 during the filling process. For this monitoring, for example, an encoder 46a of the injection motor 46 is used.

  The controller 70 of the present embodiment monitors the position of the cross head 20a in order to measure the start timing of the filling process, but may monitor the position of the movable platen 13 or the position of the movable mold 33. The position of the movable mold 33 can be monitored using, for example, a gap sensor. The gap sensor is attached to the mold apparatus 30 and detects the size of the gap between the movable mold 33 and the fixed mold 32.

In the course of time t ₂ of about mold closing step, the screw 43 reaches the V / P changeover position, the controller 70 performs the switching as filling process and pressure holding process, and starts the pressure holding process. The switching between the filling step and the pressure holding step may be performed when the elapsed time after the screw 43 reaches the speed switching position reaches a predetermined time as described above.

At time t _3, the position of the crosshead 20a reaches the mold closing completion position, the controller 70 completes the mold closing process. When the mold closing process is completed, the movable mold 33 is in a position before the contact position with the fixed mold 32, and a predetermined gap 35 is formed between the movable mold 33 and the fixed mold 32.

  The controller 70 performs a position holding process for holding the movable mold 33 at a position before the contact position with the fixed mold 32 at least until the pressure holding process is completed after the mold closing process is completed. The position holding step is performed at least until the completion of the pressure holding step, and may be performed until the completion of the cooling step as shown in FIG. 3, for example.

At time t _4, when the pressure holding step is completed, the cooling step is started. Then, at time t _5, the cooling process is completed, the controller 70 starts the mold opening process. After completion of the mold opening process, the molded product is ejected from the mold apparatus 30.

  As described above, the controller 70 completes the mold closing process and the pressure holding process in a state where the movable mold 33 is in a position before the contact position with the fixed mold 32. As compared with the case where there is no gap between the movable mold 33 and the fixed mold 32 at the completion of the mold closing process and the pressure holding process, the gas venting of the cavity space 34 can be improved. Further, the life of the mold opening / closing device 10 can be postponed, and the energy consumption of the mold opening / closing device 10 can be reduced. The position of the movable mold 33 at the completion of the mold closing process and the pressure holding process is set so that the molding material does not leak from the gap 35 between the movable mold 33 and the fixed mold 32.

  Further, the controller 70 starts the filling process during the mold closing process in a state where the movable mold 33 is located at a position before the completion of the mold closing process. By starting the filling process in the middle of the mold closing process, the molding cycle time can be shortened compared to the case of starting the filling process after the mold closing process is completed. The position of the movable mold 33 at the start of the filling process is set so that the molding material does not leak from the gap 35.

  In addition, the controller 70 starts the pressure holding process in the state where the movable mold 33 is in a position further before the position at the completion of the mold closing process during the mold closing process. By starting the pressure holding process in the middle of the mold closing process, the molding cycle time can be shortened compared to the case where the filling process and the pressure holding process are started after the mold closing process is completed. The position of the movable mold 33 at the start of the pressure holding process is set so that the molding material does not leak from the gap 35.

  In this embodiment, the pressure holding process is started in the middle of the mold closing process, but the pressure holding process may be started after the mold closing process is completed.

  By the way, in the position holding step, when the pressure acting on the movable mold 33 from the molding material is the same, the load (for example, torque) of the mold opening / closing motor 21 for holding the position of the movable mold 33 depends on the posture of the toggle mechanism 20. It will be a response. The load on the mold opening / closing motor 21 can be reduced as the arm of the toggle mechanism 20 approaches a state where the arm is bent straight. Since there is a correspondence between the load and the current, the load may be represented by a current.

  Therefore, the controller 70 may set the posture of the toggle mechanism 20 based on the load of the mold opening / closing motor 21. For example, the controller 70 sets the posture of the toggle mechanism 20 so that the load of the mold opening / closing motor 21 does not exceed the allowable load.

  Here, the load of the mold opening / closing motor 21 may be an effective value, and the allowable load may be a rated value. The load of the mold opening / closing motor 21 changes periodically and is expressed by a function f (t) of time. The effective value is a square root of a value obtained by integrating a value obtained by squaring the function f (t) with a period T and dividing the integrated value F by the period T. Period T is a molding cycle time. The rated value is an upper limit value at which the temperature of the mold opening / closing motor 21 becomes equal to or lower than the allowable temperature when the mold opening / closing motor 21 is continuously used. The rated value may be an upper limit value at which the inverter temperature becomes equal to or lower than the allowable temperature when the mold opening / closing motor 21 is continuously used. By comparing the effective value with the rated value, it is possible to avoid a stop due to abnormality detection during cycle operation.

  By the way, in the position holding process, the load on the mold opening / closing motor 21 can be reduced as the arm state of the toggle mechanism approaches a straightly extended state from the bent state, but the time of the mold closing process becomes longer and the molding cycle time becomes longer. become longer.

  Therefore, the controller 70 may set the posture of the toggle mechanism 20 based on the load of the mold opening / closing motor 21 and the molding cycle time. For example, the controller 70 sets the posture of the toggle mechanism 20 so that the load of the mold opening / closing motor 21 does not exceed the allowable load and the molding cycle is performed a predetermined number of times or more within a predetermined time.

  The controller 70 may adjust the interval between the fixed platen 12 and the toggle support 15 by the mold thickness adjusting mechanism 23 so that the posture of the toggle mechanism 20 becomes a set posture. This adjustment may be performed according to the operation status of the operation unit that receives the input operation of the operator. For example, this adjustment is performed when a predetermined input operation by the operator is performed, and may not be performed when the predetermined input operation is not performed.

  When the load of the mold opening / closing motor 21 exceeds the allowable load, the controller 70 may activate the output device 80 that outputs an alarm. As the output device 80, for example, an image display device, an audio output device, or the like is used.

  The embodiments of the injection molding machine have been described above, but the present invention is not limited to the above embodiments and the like, and various modifications are possible within the scope of the gist of the present invention described in the claims. Improvements are possible.

  For example, in the mold closing process of the above-described embodiment, the movable mold 33 is continuously advanced and stopped at a position before the contact position with the fixed mold 32, but is once advanced to the contact position with the fixed mold 32. You may make it retreat after making it. Also in this case, during the mold closing process, the filling process is started in a state where the movable mold 33 is in a position further forward than the position when the mold closing process is completed.

  Moreover, although the position holding process of the said embodiment is cancelled | released when the cooling process is completed, you may cancel | release during the cooling process. The mold opening process may be started in the middle of the cooling process.

  The mold opening / closing device 10 of the above embodiment is a horizontal type whose mold opening / closing direction is a horizontal direction. The vertical mold opening / closing device includes a lower platen as a fixed platen, an upper platen as a movable platen, a toggle support, a toggle mechanism, a mold thickness adjusting mechanism, and the like. A lower mold is attached to the lower platen, and an upper mold is attached to the upper platen. The lower die and the upper die constitute a mold apparatus. The lower mold may be attached to the lower platen via a rotary table. The toggle support is disposed below the lower platen and moves up and down together with the upper platen. The toggle mechanism is disposed between the toggle support and the lower platen. The mold thickness adjusting mechanism includes a male screw, a female screw, a mold thickness motor, and the like. The male screw is formed on the tie bar, and the tie bar connects the toggle support and the upper platen. The female screw is rotatably held on the toggle support or the upper platen. The mold thickness motor adjusts the relative positions of the toggle support and the upper platen by rotating a female screw that is screwed with the male screw.

  The mold opening / closing device 10 of the above embodiment includes the mold opening / closing motor 21 as a drive unit, but may include a hydraulic cylinder instead of the mold opening / closing motor 21. The mold opening / closing motor 21 is a rotary motor, but may be a linear motor.

  The injection device 40 of the above embodiment is an inline screw system, but may be a pre-plastic system. A pre-plastic injection device supplies a molding material melted in a plasticizing cylinder to the injection cylinder, and injects the molding material from the injection cylinder into a mold device. In the plasticizing cylinder, a screw is rotatably or rotatably and reciprocally disposed, and in the injection cylinder, a plunger is reciprocally disposed.

10 mold opening / closing device 12 fixed platen 13 movable platen 15 toggle support 16 tie bar 20 toggle mechanism 20a cross head 20b link 20c link 21 mold opening / closing motor 21a encoder 23 mold thickness adjusting mechanism 30 mold device 32 fixed mold 33 movable mold 34 cavity Space 35 Clearance 40 Injection device 41 Cylinder 43 Screw 45 Metering motor 46 Injection motor 47 Pressure detector 70 Controller 80 Output device

Claims (6)

A mold opening and closing device for opening and closing the fixed mold and the movable mold;
An injection device that fills a cavity space formed between the fixed mold and the movable mold with a molding material;
A controller for controlling the mold opening and closing device and the injection device,
The mold opening and closing device is
A platen part to which one of the fixed mold and the movable mold is attached;
A support portion coupled with the platen portion at an interval;
A toggle mechanism supported by the support;
A drive unit for moving the movable mold by operating the toggle mechanism unit;
A mold thickness adjusting unit that adjusts an interval between the platen unit and the support unit;
The controller is
In a state where the movable mold is in a position before the contact position with the fixed mold, the mold closing process by the mold opening and closing device and the pressure holding process by the injection apparatus are completed,
In the middle of the mold closing process, in a state where the movable mold is at a position further before the position at the completion of the mold closing process, the filling process by the injection device is started,
An injection molding machine that sets a bending / extending state of an arm of the toggle mechanism based on a load of the driving unit.   2. The controller according to claim 1, wherein the controller starts the pressure-holding step in a state where the movable mold is further in front of the position when the mold closing step is completed during the mold closing step. Injection molding machine.   The controller performs a position holding process of holding the movable mold at a position before a contact position with the fixed mold at least until the pressure holding process is completed after the mold closing process is completed. Item 3. The injection molding machine according to Item 1 or 2.   The injection controller according to any one of claims 1 to 3, wherein the controller sets a bending / extending state of an arm of the toggle mechanism unit based on a load of the driving unit and a molding cycle time.   5. The controller according to claim 1, wherein the controller adjusts an interval between the platen portion and the support portion by the mold thickness adjusting portion so that the bending / extending state of the arm of the toggle mechanism portion becomes the set bending / extending state. The injection molding machine according to any one of claims. It has an output device that outputs an alarm,
The injection controller according to any one of claims 1 to 5, wherein the controller activates the output device when a load of the driving unit exceeds a predetermined allowable load.

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