JP2015083384A - Mold tightening device in injection molding machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold tightening device in an injection molding machine capable of adjusting the bearing balance of a mold and in-mold parallel accuracy at high precision.SOLUTION: The space between a platen and a mold is provided with an adapter plate, the adapter plate is divided into a plurality of regions, the temperature per divided region is measured, and the temperature is adjusted per region. The temperature adjustment can be performed at a point closer to the center of the mold compared with a tie bar. Further, by performing the temperature adjustment of the adapter plate provided between the platen and the mold, the adjustment of a tie bar balance and in-mold parallel accuracy can be performed at high precision even during molding.

Description

  The present invention relates to an injection molding machine, and more particularly to a mold clamping device for an injection molding machine in which an adapter plate is mounted between a platen mold mounting surface and a mold and the temperature of the adapter plate is controlled.

  In a mold clamping device of an injection molding machine, a fixed platen and a rear platen are generally connected by a plurality of tie bars. The fixed platen is fixed to the tie bar by a fixed platen nut provided on the tie bar side. Similarly, the rear platen is also fixed to the tie bar by a rear platen nut provided on the tie bar side. Here, the rear platen nut is attached so as to be rotatable around the center of the tie bar shaft, and by rotating the rear platen nut, the rear platen can be moved forward and backward with respect to the fixed platen, and the mold thickness can be adjusted.

  Most injection molding machines are made up of four tie bars. At this time, if the amount of elongation of individual tie bars is different, the length of each tie bar will be different or the parallelism in the mold will not match. May end up. In order to adjust the elongation amount and in-mold parallelism of these tie bars with high accuracy, it is generally performed by adjusting the tightening amount of the rear platen nut. However, the amount of tightening of the rear platen can be adjusted only before molding, and cannot be adjusted while molding.

  Patent Documents 1 and 2 disclose a technique for adjusting a tie bar balance by attaching a heater to each tie bar, changing the amount of expansion of each tie bar by thermal expansion. Patent Documents 3 to 5 disclose techniques for eliminating a temperature difference for each place of the platen and keeping the temperature constant over the entire area.

JP-A-2-75499 JP 2006-347078 A JP-A-62-264921 JP 2000-271981 A JP 2006-221980 A

The techniques disclosed in Patent Documents 1 and 2 can adjust the tie bar balance and the in-mold parallelism by adjusting the tie bar elongation by changing the temperature of the tie bar. Is uniformly distributed over the entire mold, and it is an indirect means and not direct to expand and contract the tie bar by changing the temperature. In addition, since the center of the mold and the tie bar are slightly apart, there is a problem that the mold surface pressure cannot be made uniform even if the extension amount of the tie bar is adjusted.
Since the techniques disclosed in Patent Documents 3 to 5 are techniques for making the temperature uniform across the entire platen, when the tie bar balance or the in-mold parallelism is shifted due to the difference in tie bar elongation, etc. Even so, there is a problem that the tie bar balance and the in-mold parallelism cannot be adjusted because the overall temperature is adjusted while there is a deviation in the balance and parallelism.

  Therefore, in view of the above-mentioned problems of the prior art, the object of the present invention is to provide an adapter plate between the platen and the mold and to use the temperature control device to cause a difference in the thermal expansion of the adapter plate. An object of the present invention is to provide a mold clamping device for an injection molding machine capable of adjusting the surface pressure balance and in-mold parallelism of a mold with high accuracy.

  In the present invention, compared to a tie bar, an adapter plate closer to the mold center is provided between the platen and the mold, and the temperature of the adapter plate is adjusted by a temperature control device from data on variations in tie bar balance and in-mold parallelism. Adjust. This makes it possible to adjust tie bar balance and in-mold parallelism even during molding.

  In the invention according to claim 1 of the present application, in the injection molding machine in which the movable platen holding the movable side mold is connected to the fixed platen holding the fixed side mold via a tie bar, the fixed platen and the fixed platen are fixed. An adapter plate provided between at least one of the side molds and between the movable platen and the movable side mold, and the adapter plate is divided into a plurality of regions, and the temperature for each of the divided regions Temperature measuring means for measuring temperature, temperature adjusting means for adjusting the temperature of each of the divided areas, and control means for adjusting the temperature of the temperature adjusting means for each of the plurality of areas, and the injection molding machine The reference value that serves as a reference for adjusting the pressure has a first reference value that is determined to be adjusted by the temperature adjustment by the control means, and a second reference value that is determined to be mechanically adjusted. That the mold clamping apparatus of an injection molding machine is provided.

  That is, in the invention according to claim 1, an adapter plate is provided between a platen such as a fixed platen or a movable platen and a mold, the adapter plate is divided into a plurality of regions, and the temperature for each of the divided regions is adjusted. Thus, the temperature can be adjusted at a point closer to the mold center than the tie bar. Further, by adjusting the temperature of the adapter plate provided between the platen and the mold, tie bar balance and in-mold parallelism can be adjusted with high accuracy even during molding.

In the invention according to claim 2 of the present application, the sensor for measuring the distance between the fixed platen and the movable platen includes a vicinity of the four corners of the mold, and a vicinity of a point where the center line of the mold intersects the outer periphery of the mold. The control means adjusts the temperature of each region of the adapter plate so that the distance between the fixed platen and the movable platen measured by the respective distance sensors is equal at the time of lock-up. 2. The mold clamping apparatus for an injection molding machine according to claim 1, wherein the temperature adjusting means is controlled.
That is, in the invention according to claim 2, the distance between the fixed platen and the movable platen is measured by the sensor, and the temperature of each region of the adapter plate is adjusted according to the measurement result. It is possible to adjust the degree.

In the invention according to claim 3 of the present application, each of the plurality of tie bars is provided with a tie bar sensor for measuring an extension amount of the tie bar, and the control device has an extension amount of each of the plurality of tie bars measured by the tie bar sensor. 2. The mold clamping apparatus for an injection molding machine according to claim 1, wherein the temperature adjusting means for adjusting the temperature of each region of the adapter plate is controlled to be equal.
That is, in the invention according to claim 3, the tie bar sensor provided on the tie bar measures the amount of tie bar elongation, and adjusts the temperature of each region of the adapter plate according to the measurement result. Adjustments can be made.

In the invention according to claim 4 of the present application, the temperature adjusting means is any one of an electric heater, an electrothermal cooling element, and a fluid temperature controller. A mold clamping device for an injection molding machine is provided.
The invention according to claim 5 of the present application further comprises target temperature setting means for setting a target temperature for each of the plurality of regions of the temperature adjusting means. A mold clamping device for an injection molding machine as described in 1) is provided.

  According to the present invention, it is possible to adjust the surface pressure balance and in-mold parallelism of a mold with high accuracy, and to provide a mold clamping device for an injection molding machine that can be adjusted even during molding.

It is a figure which shows the whole structure of an injection molding machine. It is a figure which shows the example of the temperature control using a water pipe of an adapter plate. It is a figure which shows the example which has arrange | positioned the distance sensor of the adapter plate in the vicinity of the point which cross | intersects the metal mold centerline and metal mold | die outer periphery. It is a figure which shows the example which has arrange | positioned the distance sensor of the adapter plate to the four corner vicinity of a metal mold | die. It is a figure which shows the example of the temperature control using a heater of an adapter plate. It is sectional drawing of thermocouple attachment. It is a flowchart explaining the control by the tie bar balance reference | standard which concerns on this invention (the 1). It is a flowchart explaining the control by the tie bar balance reference | standard which concerns on this invention (the 2). It is a flowchart explaining the control by the in-mold parallelism standard which concerns on this invention (the 1). It is a flowchart explaining the control by the in-mold parallelism standard which concerns on this invention (the 2).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an overall configuration of an injection molding machine and a state in which a mold clamping force is generated. The injection molding machine M includes a mold clamping part Mc and an injection part Mi on the machine base 2. The injection part Mi heats and melts a resin material (pellet), and injects the molten resin into the cavity of the mold 40. The mold clamping portion Mc mainly opens and closes the mold 40 (40a, 40b).

  First, the injection part Mi will be described. A nozzle 12 is attached to the tip of the cylinder 11, and a screw 13 is inserted into the cylinder 11. The screw 13 is rotated by the servo motor M2, and is moved in the axial direction of the screw 13 by the servo motor M1. Reference numeral 14 denotes a hopper that supplies resin to the injection cylinder 11.

  Next, the mold clamping part Mc will be described. The mold clamping portion Mc includes a movable platen 30, a rear platen 31, a toggle 32, a fixed platen 33, a cross head 34, a servo motor M3 for moving the movable platen 30 back and forth, and a servo motor for ejecting an ejector pin that pushes a molded product out of a mold. M4 and a ball screw shaft 38 driven by a servo motor M3. The rear platen 31 and the fixed platen 33 are connected by a plurality of toggles 32, and the movable platen 30 is disposed so as to be guided by the toggles 32.

  A mold 40 (movable side mold 40a, fixed side mold 40b) is attached to the movable platen 30 and the fixed platen 33, respectively. The position of the movable platen 30 can be changed by moving the cross head 34 attached to the ball screw shaft 38 driven by the servo motor M3 forward and backward. In this case, when the cross head 34 is moved forward (moved in the right direction in the figure), the movable platen 30 is moved forward to perform mold closing. Then, a mold clamping force obtained by multiplying the propulsive force by the servo motor M3 by the toggle magnification is generated, and the mold clamping is performed by the mold clamping force.

  A molding operation using the injection molding machine M will be described. When the servo motor M3 is rotated in the forward direction, the ball screw shaft 38 is rotated in the forward direction, the crosshead 34 screwed to the ball screw shaft 38 is moved forward (rightward in FIG. 1), and the toggle 32 is operated. When moved, the movable platen 30 is advanced.

  When the movable mold 40a attached to the movable platen 30 comes into contact with the fixed mold 40b (mold closed state), the mold clamping process is started. In the mold clamping process, a mold clamping force is generated in the mold 40 by further driving the servo motor M3 in the forward direction. Then, the servo motor M1 provided in the injection part Mi is driven to advance in the axial direction of the screw 13, whereby the cavity space formed in the mold 40 is filled with the molten resin. When opening the mold, when the servo motor M3 is driven in the reverse direction, the ball screw shaft 38 is rotated in the reverse direction. Along with this, the cross head 34 moves backward, and the movable platen 30 moves backward in the direction of the rear platen 31. When the mold opening process is completed, the servo motor M4 for ejecting the ejector pin that pushes out the molded product from the movable mold 40a is operated. Thereby, an ejector pin (not shown) is protruded from the inner surface of the movable mold 40a, and a molded product in the movable mold 40a is protruded from the movable mold 40a.

  In the present invention, the adapter plate 44 is provided between the fixed platen 33 and the fixed side mold 40b, and the adapter plate 43 is provided between the movable platen 30 and the movable side mold 40a. By adjusting the temperature, the tie bar balance and in-mold parallelism are adjusted. These adapter plates 43 and 44 can be exchanged according to the mold.

As a first embodiment of the present invention, an extension amount of the tie bar 41 is measured by a tie bar sensor 42 provided at an intermediate point of each tie bar 41, and the temperature of the adapter plates 43 and 44 is adjusted based on the result. Thus, there is an embodiment for adjusting the tie bar balance.
As another embodiment of the present invention, the in-mold parallelism is measured from the measurement of the distance between the fixed platen 33 and the movable platen 30, and the temperature adjustment of the adapter plates 43 and 44 is performed based on the result. There is an embodiment in which the in-mold parallelism is adjusted by performing.
Hereinafter, each embodiment will be described.

<First Embodiment>
As shown in FIG. 1, a tie bar sensor 42 that measures the extension amount of the tie bar is provided at each intermediate point of the plurality of tie bars 41, and the extension amount of each tie bar 41 is measured. As the tie bar sensor 42, a commonly used sensor such as a strain sensor for measuring strain of a material can be used.

Hereinafter, the description will be made based on the adapter plate 43 provided on the movable platen 30, but the adapter plate 44 provided on the fixed platen 33 may have the same configuration.
The adapter plate 43 is provided with means for adjusting the temperature. Specific examples are shown in FIGS. FIG. 2 is a diagram showing an example in which a water pipe 53 through which water passes is provided in each adapter zone in the adapter plate 43 as a configuration for temperature control. The temperature of each region of the adapter plate 43 is controlled by adjusting the temperature of the water flowing through the water pipe 53 by the temperature adjusting device. FIG. 5 is a diagram showing an example in which a heater 56 is arranged in place of the water pipe of FIG.

  2 and 5, a temperature sensor 54 for measuring the temperature of the adapter plate 43 is provided. A thermocouple can be used as the temperature sensor 54. FIG. 6 is a cross-sectional view of thermocouple attachment. A hole for attaching a thermocouple is provided in the adapter plate, and the thermocouple fitted in the socket 58 is fixed by fixing means such as screwing. The socket 58 is provided with a signal line (not shown), and a detection signal from the thermocouple is input to the control device 51 of the injection molding machine M.

Next, a method for measuring the amount of elongation of the tie bar 41 and adjusting the temperature according to the present embodiment will be described step by step with reference to FIGS.
(Step SA1) As a tie bar balance reference value, a first reference value (%) determined to be adjusted by temperature control and a second reference value (%) determined to be machine adjusted are read. The first reference value (%) and the second reference value (%) are stored as setting data in the storage device of the control device 51 in advance.
(Step SA2) The extension amount of each tie bar 41 at the time of mold clamping is measured by the tie bar sensor 42.
(Step SA3) The extension amount of the tie bar 41 is converted into the mold clamping force value of each tie bar 41. The obtained value is used as the converted clamping force value.
(Step SA4) From the converted mold clamping force value of each tie bar 41, an average value of the converted mold clamping force value is calculated, and a difference between the converted mold clamping force value of each tie bar 41 and the average value is calculated. Find the maximum and minimum values.

(Step SA5) It is determined whether or not the tie bar balance is within the first reference value (%). If the tie bar balance is within the first reference value (YES), the process returns to Step SA2 to continue the process, and is larger than the first reference value In the case (NO), the process proceeds to Step SA6. Here, the tie bar balance uses the maximum value, the minimum value, and the average value of the converted clamping force values obtained in step SA4, and the tie bar balance (%) = (maximum value−minimum value) / average value × 100. calculate.
(Step SA6) It is determined whether or not the tie bar balance is greater than or equal to the second reference value (%). If the tie bar balance is greater than or equal to the second reference value (YES), the process proceeds to Step SA7, and if less than the second reference value (NO) Advances to step SA8.
(Step SA7) In temperature control, the tie bar balance cannot be adjusted, and mechanical adjustment of the mechanism section is necessary. Therefore, the fact that mechanical adjustment is necessary is notified by an alarm display, and the process is terminated.
(Step SA8) The temperature of each zone of the adapter plate 43 is measured.
(Step SA9) The minimum unit of adjustment at the time of temperature rise and the minimum unit of adjustment at the time of temperature fall stored in advance in the storage device of the control device 51 as the setting data are read. A target value for the mold temperature is also set.

(Step SA10) It is determined whether the zone of the adapter plate 43 near the tie bar 41 other than the tie bar 41 corresponding to the minimum value obtained in step SA4 is equal to or higher than the mold temperature. When the temperature is higher than the mold temperature (YES), the process proceeds to Step SA11, and when the temperature is lower than the mold temperature (NO), the process proceeds to Step SA16.
(Step SA11) It is determined whether or not the mold clamping force of the tie bar 41 near the heating part of the adapter plate 43 is equal to or greater than the average value obtained in the process of Step SA4. If it is equal to or greater than the average value (YES), the process proceeds to step SA12, and if it is less than the average value (NO), the process proceeds to step SA16.
(Step SA12) A target temperature in the case of a temperature drop is determined.
(Step SA13) Stop the heating of the zone of the adapter plate 43 corresponding to the tie bar 41 that is equal to or greater than the average value.
(Step SA14) The temperature of each zone of the adapter plate 43 is measured.
(Step SA15) It is determined whether or not the temperature has decreased to the target temperature. If the temperature has decreased (YES), the processing returns to Step SA2 and the processing is continued. If not (NO), the processing returns to Step SA13.

(Step SA16) A target temperature in the case of a temperature rise is determined.
(Step SA17) The zone of the adapter plate 43 corresponding to the minimum tie bar 41 is heated.
(Step SA18) The temperature of each zone of the adapter plate 43 is measured.
(Step SA19) It is determined whether or not the temperature has risen to the target temperature. If the temperature has risen (YES), the process returns to Step SA2 and the process is continued. If not (NO), the process returns to Step SA17.

<Second Embodiment>
In the present embodiment, instead of measuring the extension amount of the tie bar 41 by the tie bar sensor 42 in the first embodiment, the in-mold parallelism is obtained by measuring the distance between the fixed platen 33 and the movable platen 30. In this embodiment, the in-mold parallelism is adjusted by adjusting the temperature of the adapter plate 43 based on the measurement result.

  A distance sensor 60 that measures the distance between the fixed platen 33 and the movable platen 30 is provided on the adapter plate 43. As the distance sensor 60, an eddy current meter or a laser displacement meter can be used. As shown in FIG. 3, the position where the distance sensor 60 is provided can be provided in the vicinity of a point intersecting the center line 45 of the mold 40 and the outer periphery of the mold, or as shown in FIG. It can also be provided near the four corners of the mold 40. The control device 51 of the injection molding machine M adjusts the temperature of the member provided with the temperature sensor 54 so that the distance between the fixed platen 33 and the movable platen 30 measured by the distance sensors 60 at the time of lock-up becomes equal. The device 52 is controlled.

Next, the method of measuring the parallelism in the mold and adjusting the temperature according to the present embodiment will be described step by step based on FIGS.
(Step SB1) The third reference value (mm) determined to be adjusted by temperature control and the fourth reference value (mm) determined to be machine adjusted are read as the reference value of the in-mold parallelism. The third reference value (mm) and the fourth reference value (mm) are stored in advance as setting data in the storage device of the control device.
(Step SB2) The distance between the fixed platen 33 and the movable platen 30 at the time of mold clamping is measured by the distance sensor 60 for each zone of the adapter plate 43.
(Step SB3) From the measurement result of the distance sensor 60, the maximum value, the minimum value, and the average value of the distance between the fixed platen 33 and the movable platen 30 are obtained.
(Step SB4) It is determined whether or not the in-mold parallelism is within the third reference value (mm). If it is within the third reference value (YES), the process returns to Step SB2 to continue the processing, and the third reference value If larger (NO), the process proceeds to step SB5. Here, the in-mold parallelism is calculated by the difference between the maximum value and the minimum value obtained in step SB3.

(Step SB5) It is determined whether the in-mold parallelism is greater than or equal to the fourth reference value (mm). If the in-mold parallelism is greater than or equal to the fourth reference value (YES), the process proceeds to Step SB6, and less than the fourth reference value ( If NO, the process proceeds to step SB7.
(Step SB6) Since the in-mold parallelism cannot be adjusted in the temperature control and the mechanical adjustment of the mechanism portion is necessary, the fact that the mechanical adjustment is necessary is notified by an alarm display, and the process is terminated.
(Step SB7) The temperature of each zone of the adapter plate 43 is measured.
(Step SB8) The minimum unit of adjustment at the time of temperature rise and the minimum unit of adjustment at the time of temperature fall stored in advance in the storage device of the control device as setting data are read. A target value for the mold temperature is also set.

(Step SB9) It is determined whether the zone of the adapter plate near the in-mold parallelism measurement point other than the minimum value obtained in Step SB3 is equal to or higher than the mold temperature. When the temperature is higher than the mold temperature (YES), the process proceeds to step SB10, and when the temperature is lower than the mold temperature (NO), the process proceeds to step SB15.
(Step SB10) It is determined whether the in-mold parallelism near the heating part of the adapter plate 43 is equal to or less than the average value obtained in the process of Step SB3. If it is equal to or less than the average value (YES), the process proceeds to step SB11. If it is greater than the average value (NO), the process proceeds to step SB15.
(Step SB11) A target temperature in the case of a temperature drop is determined.
(Step SB12) The heating of the zone of the adapter plate 43 corresponding to the in-mold parallelism measurement point below the average value is stopped.
(Step SB13) The temperature of each zone of the adapter plate 43 is measured.
(Step SB14) It is determined whether or not the temperature has decreased to the target temperature. If the temperature has decreased (YES), the process returns to Step SB2 and the process is continued. If not (NO), the process returns to Step SB12.

(Step SB15) A target temperature in the case of a temperature rise is determined.
(Step SB16) The zone of the adapter plate corresponding to the maximum in-mold parallelism measurement point is heated.
(Step SB17) The temperature of each zone of the adapter plate 43 is measured.
(Step SB18) It is determined whether or not the temperature has risen to the target temperature. If the temperature has risen (YES), the process returns to Step SB2, and the process is continued. If not (NO), the process returns to Step SB16.

In these embodiments, adapter plates 43 and 44 are provided on both the fixed platen 33 and the movable platen 30 to adjust the temperature of both adapter plates 43 and 44. However, only one of the platens can be adjusted. An adapter plate can also be provided.
In these embodiments, the temperature adjusting device 52 is individually provided for each zone of the adapter plates 43 and 44. However, the temperature adjusting device 52 is not necessarily limited to being provided individually. If the temperature can be adjusted, the temperature adjusting device 52 itself can take the form of controlling the temperature of each zone individually with one temperature adjusting device 52, for example.

In these embodiments, a thermocouple is used as the temperature sensor 54, but the present invention is not limited to this, and other types of temperature sensors can be used.
Furthermore, in the second embodiment, the distance sensor 60 that measures the distance between the fixed platen 33 and the movable platen 30 is disposed in the vicinity of the point where the center line 45 of the mold 40 intersects the outer periphery of the mold. In some cases, each location is one, and in the vicinity of the four corners, each location is two. However, the position and number of the distance sensors 60 can be changed as appropriate.

<Third Embodiment>
In the case of a control method in which a molded product is measured and the target temperature is set according to the measurement result, the target temperature is set so that the measurer can take a good product while evaluating the measurement result. As an application example, if the thickness of the molded product varies, the measurer increases the set value of the target temperature of each zone of the adapter plate corresponding to the thick part of the molded product. The temperature of the adapter plate is controlled so that the thickness of the molded product is uniform.

M Injection molding machine Mi Injection part Mc Mold clamping part M1, M2, M3, M4 Servo motor 2 Machine stand 11 Cylinder 12 Nozzle 13 Screw 14 Hopper 30 Movable platen 31 Rear platen 32 Toggle 33 Fixed platen 34 Crosshead 38 Ball screw shaft 40 Gold Mold 40a Movable mold 40b Fixed mold 41 Tie bar 42 Tie bar sensor 43, 44 Adapter plate 45 Mold center line 51 Controller 52 Temperature controller 53 Water pipe 54 Temperature sensor 56 Heater 58 Socket 60 Distance sensor

Claims (5)

In an injection molding machine in which a movable platen holding a movable side mold is connected to a fixed platen holding a fixed side mold via a tie bar,
An adapter plate provided between at least one of the fixed platen and the fixed mold, and between the movable platen and the movable mold;
Temperature measuring means for dividing the adapter plate into a plurality of regions and measuring the temperature of each of the divided regions;
Temperature adjusting means for adjusting the temperature of each of the divided areas;
Control means for performing temperature adjustment of the temperature adjustment means for each of the plurality of regions,
The reference value serving as a reference for adjusting the injection molding machine has a first reference value determined to be adjusted by the temperature adjustment by the control means, and a second reference value determined to be mechanically adjusted. Clamping device for injection molding machine. Sensors for measuring the distance between the fixed platen and the movable platen are provided in at least one of the vicinity of the four corners of the mold and the vicinity of the point where the center line of the mold intersects the outer periphery of the mold,
The control means controls the temperature adjusting means for adjusting the temperature of each region of the adapter plate so that the distance between the fixed platen and the movable platen measured by the respective distance sensors at the time of lock-up becomes equal. The mold clamping device for an injection molding machine according to claim 1. Each of the plurality of tie bars is provided with a tie bar sensor for measuring an extension amount of the tie bar,
The control device controls the temperature adjusting means for adjusting the temperature of each region of the adapter plate so that the extension amounts of the plurality of tie bars measured by the tie bar sensor are equal to each other. A mold clamping device for an injection molding machine as described in 1.   The mold clamping apparatus for an injection molding machine according to any one of claims 1 to 3, wherein the temperature adjusting means is any one of an electric heater, an electrothermal cooling element, and a fluid temperature controller.   The mold clamping device for an injection molding machine according to any one of claims 1 to 4, further comprising target temperature setting means for setting a target temperature for each of the plurality of regions of the temperature adjusting means.