Injection molding machine and method for adjusting amount of change in mold clamping force of injection molding machine

Abstract

The invention provides an injection molding machine which is low in possibility of causing other molding defects even if the mold clamping force is adjusted, can immediately cope with the change of the mold clamping force, and is not easy to cause human-caused differences even if the setter of the injection molding machine changes. An injection molding machine (10) is provided with: a mold clamping device (12) having a fixed mold (30) and a movable mold (33) that constitute a mold (28), and a mold clamping force sensor (27) that detects the mold clamping force of the movable mold (33) with respect to the fixed mold (30); an injection device (14) having an injection nozzle (46) and a screw (48) for filling the mold (28) with a molten resin via the injection nozzle (46); and a control device (15). The control device (15) monitors the amount of change in the mold clamping force from the mold clamping force sensor (27), increases the micro-speed advance time at the VP switching time when the amount of change exceeds a predetermined upper limit, and reduces the micro-speed advance time at the VP switching time when the amount of change is lower than a predetermined lower limit.

Description

Technical Field

[0001] The present invention relates to an injection molding machine having an adjusting device for clamping force and a method for adjusting the change amount of the clamping force of an injection molding machine. Background Art

[0002] Conventionally, a method for adjusting the clamping force in an injection molding machine has been developed (for example, Patent Document 1).

[0003] Patent Document 1 discloses the following: When molding by clamping a mold in an injection molding machine, the clamping force of the mold is adjusted based on the mold displacement of the mold detected by using a mold gap detection sensor, the injection peak pressure on the injection molding machine side, and the injection most advanced position, and molding is performed with an appropriate clamping force that does not cause burr defects and can reduce the energy required for clamping.

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-45938 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] However, in the case of the injection molding machine disclosed in Patent Document 1, the clamping force is adjusted by changing the basic conditions such as the injection peak pressure and the injection most advanced position, which are the basis of injection molding. Therefore, the degree of influence on the entire injection molding is large, and even if burr defects can be avoided, other problems may occur.

[0009] The present invention has been made in view of such problems, and an object thereof is to provide an injection molding machine and a method for adjusting the change amount of the clamping force of an injection molding machine, which have a low possibility of causing other molding defects even when the clamping force is adjusted, can immediately respond to changes in the clamping force, and are not likely to show human-induced differences even when the setter of the injection molding machine changes.

[0010] Means for Solving the Problems

[0011] According to one aspect of the present invention, there is provided an injection molding machine including:

[0012] A clamping device having a fixed mold and a movable mold constituting a mold, and a clamping force sensor for detecting the clamping force of the movable mold relative to the fixed mold;

[0013] An injection device having an injection nozzle and a screw, the screw filling molten resin into the mold through the injection nozzle; and

[0014] A control device

[0015] The control device monitors the amount of change in the clamping force from the clamping force sensor.

[0016] When the amount of change exceeds a specified upper limit, the creep advance time at the VP switching point is increased.

[0017] When the amount of change is lower than a specified lower limit, the creep advance time at the VP switching point is decreased.

[0018] According to another aspect of the present invention, an injection molding machine is provided, including:

[0019] A clamping device having a fixed mold and a movable mold constituting a mold, and a clamping force sensor for detecting the clamping force of the movable mold relative to the fixed mold;

[0020] An injection device having an injection nozzle and a screw, and the screw fills molten resin into the mold through the injection nozzle; and

[0021] A control device

[0022] The control device monitors the amount of change in the clamping force from the clamping force sensor.

[0023] When the amount of change exceeds a specified upper limit, the holding pressure screw speed is decreased.

[0024] When the amount of change is lower than a specified lower limit, the holding pressure screw speed is increased.

[0025] According to another aspect of the present invention, an injection molding machine is provided, including:

[0026] A clamping device having a fixed mold and a movable mold constituting a mold, and a clamping force sensor for detecting the clamping force of the movable mold relative to the fixed mold;

[0027] An injection device having an injection nozzle and a screw, and the screw fills molten resin into the mold through the injection nozzle; and

[0028] A control device

[0029] The control device monitors the amount of change in the clamping force from the clamping force sensor.

[0030] When the amount of change exceeds a specified upper limit, the VP switching position is moved away from the injection nozzle.

[0031] When the amount of change is lower than a specified lower limit, the VP switching position is moved closer to the injection nozzle.

[0032] According to another aspect of the present invention, there is provided a method for adjusting the change amount of the clamping force of an injection molding machine, the injection molding machine including:

[0033] A clamping device having a fixed mold and a movable mold constituting a mold, and a clamping force sensor for detecting the clamping force of the movable mold relative to the fixed mold,

[0034] An injection device having an injection nozzle and a screw, the screw filling molten resin into the mold through the injection nozzle; and

[0035] A control device,

[0036] The control device monitors the change amount of the clamping force from the clamping force sensor,

[0037] When the change amount exceeds a specified upper limit, the micro-speed forward time at the VP switching moment is increased,

[0038] When the change amount is lower than a specified lower limit, the micro-speed forward time at the VP switching moment is decreased.

[0039] According to another aspect of the present invention, there is provided a method for adjusting the change amount of the clamping force of an injection molding machine, the injection molding machine including:

[0040] A clamping device having a fixed mold and a movable mold constituting a mold, and a clamping force sensor for detecting the clamping force of the movable mold relative to the fixed mold,

[0041] An injection device having an injection nozzle and a screw, the screw filling molten resin into the mold through the injection nozzle; and

[0042] A control device,

[0043] The control device monitors the change amount of the clamping force from the clamping force sensor,

[0044] When the change amount exceeds a specified upper limit, the holding pressure screw speed is decreased,

[0045] When the change amount is lower than a specified lower limit, the holding pressure screw speed is increased

[0046] According to another aspect of the present invention, there is provided a method for adjusting the change amount of the clamping force of an injection molding machine, the injection molding machine including:

[0047] A clamping device having a fixed mold and a movable mold constituting a mold, and a clamping force sensor for detecting the clamping force of the movable mold relative to the fixed mold;

[0048] An injection device having an injection nozzle and a screw, the screw filling molten resin into the mold through the injection nozzle; and

[0049] Control device

[0050] The control device monitors the change amount of the clamping force from the clamping force sensor.

[0051] When the change amount exceeds a specified upper limit, the VP switching position is moved away from the injection nozzle.

[0052] When the change amount is lower than a specified lower limit, the VP switching position is moved closer to the injection nozzle.

[0053] Advantages of the Invention

[0054] According to the injection molding machine and the method for adjusting the change amount of the clamping force of the injection molding machine of the present invention, by adjusting the time of "slow forward", the "holding pressure screw speed", and the "VP switching position", the change amount of the clamping force is within a specified range. Therefore, the possibility of causing other molding defects is low, as in the case of directly adjusting the clamping force, and it is possible to immediately respond to the change of the clamping force. Moreover, even if the setter of the injection molding machine changes, it is not easily affected by individual differences. Description of the Drawings

[0055] Figure 1 It is a diagram showing an example of the injection molding machine 10 according to the embodiment.

[0056] Figure 2 It is a first corresponding flowchart showing the control device 15 of the injection molding machine 10 according to the embodiment.

[0057] Figure 3 It is a second corresponding flowchart showing the control device 15 of the injection molding machine 10 according to the embodiment.

[0058] Figure 4 It is a third corresponding flowchart showing the control device 15 of the injection molding machine 10 according to the embodiment. Detailed Embodiment

[0059] (Structure of the injection molding machine 10)

[0060] The injection molding machine 10 of the present embodiment is a machine that repeatedly performs a molding cycle of mold closing, clamping, injection filling of molten resin, metering, mold opening, and taking out of the molded part to manufacture the molded part. As Figure 1 shown, it generally includes a clamping device 12, an injection device 14, and a control device 15.

[0061] The clamping device 12 includes: a machine base 16, a fixed platen 18, a movable platen 20, a pressure-bearing platen 22, tie rods 24, a toggle mechanism 26, and a clamping force sensor 27.

[0062] The machine base 16 is a component that constitutes other parts of the mold clamping device 12 and serves as the base of the injection device 14.

[0063] The fixed platen 18 is fixed to the machine base 16 and has a fixed mold 30 that constitutes the mold 28 mounted thereon.

[0064] The movable platen 20 is a component that slides on the machine base 16 in a manner of approaching / separating from the fixed platen 18, and has a movable mold 33 that constitutes the mold 28 mounted thereon. By bringing the movable mold 33 into contact with the fixed mold 30, a cavity for filling molten resin is formed.

[0065] The pressure-receiving platen 22 is a component fixed to the machine base 16 on the side opposite to the fixed platen 18 when viewed from the movable platen 20.

[0066] The tie bar 24 is a rod-shaped component with one end fixed to the fixed platen 18 and the other end fixed to the pressure-receiving platen 22. In addition, the tie bar 24 is inserted through a tie bar insertion hole 31 formed in the movable platen 20, and the movable platen 20 is disposed between the fixed platen 18 and the pressure-receiving platen 22. Thus, the movable platen 20 can slide along the tie bar 24 in the machine base 16 in the left-right direction in the figure. In addition, multiple (for example, 4) tie bars 24 are used.

[0067] The toggle mechanism 26 is a mechanism for causing the movable platen 20 to approach / separate from the fixed platen 18, and the mold clamping drive device 32 is installed on the pressure-receiving platen 22.

[0068] By transmitting the driving force of the mold clamping drive device 32 via the toggle mechanism 26, the movable platen 20 moves along the tie bar 24 (moves in the left-right direction in the figure). If the movable platen 20 moves to the left, the fixed mold 30 and the movable mold 33 separate. On the other hand, if the movable platen 20 moves to the right, the fixed mold 30 and the movable mold 33 abut against each other, and a cavity (internal space) is formed inside the mold 28. Moreover, if further pressure is applied in the direction of causing the movable platen 20 to move to the right, the fixed mold 30 and the movable mold 33 are clamped.

[0069] The mold clamping force sensor 27 is a sensor that measures the mold clamping force of the movable mold 33 relative to the fixed mold 30, and is installed on at least one tie bar 24. Specifically, the deformation of the tie bar 24 during mold clamping is measured, and in the control device 15, the mold clamping force is calculated based on this deformation amount.

[0070] The injection device 14 is a device that injects and fills molten resin into the mold (cavity) 28 formed by bringing the movable mold 33 into contact with the fixed mold 30, and has a heating cylinder 44 surrounded by heaters and an injection nozzle 46 whose front end abuts against the mold 28. A screw 48 for conveying the molten resin to the injection nozzle 46 is accommodated in the heating cylinder 44.

[0071] (Characteristic control of the control device 15)

[0072] The control device 15 is a device that controls all molding cycles of the injection molding machine 10. Only the characteristic control of the injection molding machine 10 involved in this embodiment will be described below (refer to Figure 2 ).

[0073] When repeatedly performing the molding cycle of the injection molding machine 10, in the control device 15, from "clamping" to "injection filling of molten resin" in the previous molding cycle, the change amount of the clamping force calculated based on the deformation amount signal from the clamping force sensor 27 is always monitored.

[0074] If the monitored change amount of the clamping force is within a specified range (for example, when the set clamping force is 1000 kN, after clamping with 1000 kN, the change in the clamping force accompanying the increase in the internal pressure of the mold during the filling of molten resin is in the range of 10 kN or more and 50 kN or less), the control device 15 does not perform any special actions and repeats the same molding cycle as the previous time. In addition, the monitoring of the change amount of the clamping force can be performed not only during the injection filling of molten resin, but also during clamping, or in either one.

[0075] When the monitored change amount of the clamping force exceeds the specified range, the control device 15 performs a first corresponding action.

[0076] (First corresponding action)

[0077] Normally, when filling molten resin into the mold 28 through the injection device 14, the screw 48 of the injection device 14 advances a specified length, thereby filling a specified amount of molten resin into the mold 28. After this advancement, the screw 48 is operated to maintain the pressure so that the pressure value in the mold 28 becomes a specified value. In addition, the switching position and time of the advancement action and the pressure maintaining action of the screw 48 are referred to as "VP switching".

[0078] Here, when the monitored change amount of the clamping force exceeds the specified upper limit, the control device 15 makes the final "slow advance" of this advancement action, for example: increase the period by 0.05 seconds, and then perform the pressure maintaining action (for example, when the slow advance time of the screw 48 is 0 s, set the slow advance time to 0.5 s). In addition, the speed of the advancement action of the screw 48 is, for example, 10 mm / s to 300 mm / s, and the speed during slow advance is, for example, 0.1 mm / s.

[0079] In this way, the control device 15 confirms the change amount of the clamping force when performing the first corresponding action. If this change amount is within the specified range, the control device 15 continues to implement the next molding cycle at the time of the previous "slow advance".

[0080] If the amount of change exceeds the specified upper limit, the control device 15 further increases the time of "very slow forward movement" (for example, set to 1.0 second) to implement the next molding cycle. Even if the time of "very slow forward movement" is increased, if the amount of change in the clamping force still exceeds the specified upper limit, the control device 15 continues to further increase the time of "very slow forward movement". Then, when the "very slow forward movement" reaches the specified time (for example, 2.0 seconds), the control device 15 performs the second correspondence (refer to Figure 3 ).

[0081] (Second correspondence)

[0082] As described above, after the VP switch, the screw 48 is operated to make the pressure value in the mold 28 a specified value to perform the pressure holding operation. However, in the first correspondence, when the "very slow forward movement" reaches the specified time (for example, 2.0 seconds), as the second correspondence, the control device 15 then reduces the forward speed of the screw 48 ("pressure holding screw speed") during the pressure holding operation following the above first correspondence. For example, the forward speed of the screw 48 during the normal pressure holding operation is reduced from 20 mm / s to 15 mm / s.

[0083] In this way, the control device 15 confirms the amount of change in the clamping force when the second correspondence is performed. If the amount of change is within the specified range, the control device 15 continues to implement the next molding cycle at the previous "pressure holding screw speed".

[0084] If the amount of change exceeds the specified upper limit, the control device 15 further reduces the "pressure holding screw speed" (for example, set to 10 mm / s) to implement the next molding cycle. If even when the "pressure holding screw speed" is reduced, the amount of change in the clamping force still exceeds the specified upper limit, the control device 15 continues to further reduce the "pressure holding screw speed". Moreover, when the "pressure holding screw speed" reaches the specified value (for example, 1 mm / s), the control device 15 performs the third correspondence (refer to Figure 4 ).

[0085] (Third correspondence)

[0086] When the "pressure holding screw speed" reaches the specified value (for example, 1 mm / s) in the second correspondence, as the third correspondence, the control device 15 then changes the position of the screw 48 ("VP switching position") when performing the VP switch following the above second correspondence. For example, when the normal VP switching position is set to 10 mm, it is changed to +1 mm (the position where the screw 48 is 1 mm away from the injection nozzle 46). As a result, the amount of molten resin entering the mold 28 changes.

[0087] In this way, the control device 15 confirms the amount of change in the clamping force when the third correspondence is performed. If the amount of change is within the specified range, the control device 15 continues to implement the next molding cycle at the previous "VP switching position".

[0088] If the amount of change exceeds the specified upper limit, the control device 15 moves the "VP switching position" to a position further away from the injection nozzle 46 (for example, set to +2 mm), and implements the next molding cycle. If the amount of change in the clamping force still exceeds the specified upper limit even when the "VP switching position" is further changed, the control device 15 continues to move the "VP switching position" to a position further away from the injection nozzle 46. Then, when the moving amount of the "VP switching position" reaches the specified value (for example, +5 mm), the control device 15 ends the response.

[0089] (When the amount of change in the clamping force is lower than the specified lower limit)

[0090] Contrary to the description so far, when the monitored amount of change in the clamping force is lower than the specified lower limit, the control device 15 reduces the time of "slow advance" (for example, from 0.5 seconds to 0.4 seconds) and implements the next molding cycle (the first response). If the amount of change in the clamping force is still lower than the specified lower limit even when the time of "slow advance" is reduced, the control device 15 continues to reduce the time of "slow advance". Then, when the "slow advance" reaches the specified time (for example, 0 seconds), the control device 15 makes the second response.

[0091] When the amount of change in the clamping force is still lower than the specified lower limit even when the time of "slow advance" is reduced, the control device 15 increases the "holding pressure screw speed" (for example, from 15 mm / s to 17 mm / s) and implements the next molding cycle (the second response). When the amount of change in the clamping force is still lower than the specified lower limit even when the "holding pressure screw speed" is increased, the control device 15 continues to increase the "holding pressure screw speed". Moreover, when the "holding pressure screw speed" reaches the specified speed (for example, 40 mm / s), the control device 15 makes the third response.

[0092] When the "holding pressure screw speed" reaches the specified speed (for example, 40 mm / s) in the second response, as the third response, the control device 15 changes the position of the screw 48 ("VP switching position") when performing VP switching following the above second response. For example, when the normal VP switching position is set to 10 mm, it is changed to -1 mm (the position where the screw 48 approaches the injection nozzle 46 by 1 mm).

[0093] However, when the amount of change is still lower than the specified lower limit, the control device 15 changes the "VP switching position" further to a position closer to the injection nozzle 46 (for example, set to a position closer to -2 mm) to perform the next molding cycle. When the amount of change in the clamping force is still lower than the specified lower limit even if the "VP switching position" is further changed, the control device 15 continues to change the "VP switching position". Then, when the amount of change in the "VP switching position" reaches a specified value (for example, -5 mm), the control device 15 ends the response.

[0094] Thus, in the injection molding machine 10 of the present embodiment, by adjusting the time of "slow forward", the "holding pressure screw speed", and the "VP switching position", the amount of change in the clamping force is within a specified range. Therefore, the possibility of causing other molding defects is low as in the case of directly adjusting the clamping force, the change in the clamping force can be immediately responded to, and even if the setter of the injection molding machine changes, human differences are not likely to occur.

[0095] (Modification 1)

[0096] If the amount of change in the clamping force is still outside the specified range even after performing the above "third response", the clamping force can also be changed. For example, the mounting position of the movable platen 20 relative to the toggle mechanism 26 is moved so that the movable platen 20 is closer to the fixed platen 18 (the clamping force increases), or conversely, the movable platen 20 is slightly moved away from the fixed platen 18 (the clamping force decreases).

[0097] (Modification 2)

[0098] In the injection molding machine 10 according to the above embodiment, the clamping force sensor 27 is mounted on the tie bar 24, but as long as the clamping force can be measured, the clamping force sensor 27 can also be mounted at other positions.

[0099] (Modification 3)

[0100] In the injection molding machine 10 according to the above embodiment, the first response, the second response, and the third response are applied in sequence, but the responses can also be applied in a different order, and any one of the responses can also be applied alone, or any two of the responses can be applied.

[0101] The embodiments disclosed herein should be considered illustrative in all respects and not restrictive. The scope of the present invention is represented not by the above description but by the claims, and is intended to include meanings equivalent to the claims and all modifications within the scope.

[0102] Description of reference numerals:

[0103] 10... Injection molding machine

[0104] 12... Clamping device

[0105] 14... Injection device

[0106] 15... Control device

[0107] 16... Machine base

[0108] 18... Fixed platen

[0109] 20... Movable platen

[0110] 22... Pressure-bearing platen

[0111] 24... Tie rod

[0112] 26... Toggle mechanism

[0113] 27... Clamping force sensor

[0114] 28... Mold

[0115] 30... Fixed mold

[0116] 31... Tie rod insertion through-hole

[0117] 32... Clamping drive device

[0118] 33... Movable mold

[0119] 44... Heating cylinder

[0120] 46... Injection nozzle

[0121] 48... Screw

Claims

1. An injection molding machine, comprising: A mold clamping device having a fixed mold and a movable mold constituting a mold, and a mold clamping force sensor for detecting the mold clamping force of the movable mold relative to the fixed mold; An injection device having an injection nozzle and a screw, and the screw fills molten resin into the mold through the injection nozzle; And A control device, The control device monitors the change amount of the mold clamping force from the mold clamping force sensor, When the change amount exceeds a specified upper limit, the micro-speed forward time at the VP switching moment is increased, When the change amount is lower than a specified lower limit, the micro-speed forward time at the VP switching moment is decreased.

2. An injection molding machine, comprising: A mold clamping device having a fixed mold and a movable mold constituting a mold, and a mold clamping force sensor for detecting the mold clamping force of the movable mold relative to the fixed mold; An injection device having an injection nozzle and a screw, and the screw fills molten resin into the mold through the injection nozzle; And A control device, The control device monitors the change amount of the mold clamping force from the mold clamping force sensor, When the change amount exceeds a specified upper limit, the holding pressure screw speed is decreased, When the change amount is lower than a specified lower limit, the holding pressure screw speed is increased.

3. An injection molding machine, comprising: A mold clamping device having a fixed mold and a movable mold constituting a mold, and a mold clamping force sensor for detecting the mold clamping force of the movable mold relative to the fixed mold; An injection device having an injection nozzle and a screw, and the screw fills molten resin into the mold through the injection nozzle; And A control device, The control device monitors the change amount of the mold clamping force from the mold clamping force sensor, When the change amount exceeds a specified upper limit, the VP switching position is moved to a position away from the injection nozzle, When the change amount is lower than a specified lower limit, the VP switching position is moved to a position closer to the injection nozzle.

4. A method for adjusting the change amount of the mold clamping force of an injection molding machine, the injection molding machine comprising: A mold clamping device having a fixed mold and a movable mold constituting a mold, and a mold clamping force sensor for detecting the mold clamping force of the movable mold relative to the fixed mold; An injection device having an injection nozzle and a screw, and the screw fills molten resin into the mold through the injection nozzle; And A control device, The control device monitors the change amount of the mold clamping force from the mold clamping force sensor, When the change amount exceeds a specified upper limit, the micro-speed forward time at the VP switching moment is increased, When the change amount is lower than a specified lower limit, the micro-speed forward time at the VP switching moment is decreased.

5. A method for adjusting the change amount of the mold clamping force of an injection molding machine, the injection molding machine comprising: A mold clamping device having a fixed mold and a movable mold constituting a mold, and a mold clamping force sensor for detecting the mold clamping force of the movable mold relative to the fixed mold; An injection device having an injection nozzle and a screw, and the screw fills molten resin into the mold through the injection nozzle; And A control device, The control device monitors the change amount of the mold clamping force from the mold clamping force sensor, When the change amount exceeds a specified upper limit, the holding pressure screw speed is decreased, When the change amount is lower than the specified lower limit, increase the holding pressure screw speed.

6. A method for adjusting the clamping force change amount of an injection molding machine, the injection molding machine comprising: A clamping device having a fixed mold and a movable mold constituting a mold, and a clamping force sensor for detecting the clamping force of the movable mold relative to the fixed mold; An injection device having an injection nozzle and a screw, the screw filling molten resin into the mold through the injection nozzle; And A control device, The control device monitors the change amount of the clamping force from the clamping force sensor, When the change amount exceeds the specified upper limit, move the VP switching position away from the injection nozzle, When the change amount is lower than the specified lower limit, move the VP switching position closer to the injection nozzle.

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