JP2005288895A - Mold protecting method of mold clamping device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance stability and reliability in the protection of a mold by certainly discriminating whether foreign matter is held in a mold even with respect to a extremely thin sheetlike molded product and avoiding trouble bringing about erroneous detection or detection failure. <P>SOLUTION: A predetermined mold protecting section is set to the clossing section of the mold 1 and the abnormality caused by foreign matter or the like is detected on the basis of fluctuations of physical quantity in the mold protecting section to protect the mold 1. A mold clamping position Cs is preliminarily detected. The finish position Xf of a mold clamping montor, which detects that at least the molded product is held between the molds 1 on the basis of the thickness of the mold clamping position Cs and the thickness of the molded product, is set on this side of the mold clamping position Cs. The fluctuation quantity of physical quantity associated with the clamping of the mold 1 is detected at the time of production operation. If the fluctuation quantity reaches a preset value up to the finish position Xf, abnormality treatment for protecting the mold 1 is performed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a mold protection method for a mold clamping device that detects an abnormality such as a foreign substance based on a change in a physical quantity in a mold protection section set as a mold closed section for closing a mold and protects the mold.

  In general, a toggle type clamping device for clamping a mold provided in an injection molding machine is known from Japanese Patent Publication No. 6-61806. As disclosed in the same publication, the toggle type mold clamping device uses a toggle link mechanism to connect a movable plate that supports a movable mold and a crosshead that is advanced and retracted by a drive unit to increase the pressure applied to the crosshead. It has a function of transmitting to the movable platen, and a predetermined clamping force is generated based on the extension of the tie bar when the toggle link mechanism is almost extended. In the mold clamping operation, as shown in FIG. 9, normally, the high speed mold closing is performed from the mold opening position Xa, and when the low speed / low pressure switching position Xb set in advance is reached, the process shifts to the low speed / low pressure mold closing. This low-speed and low-pressure mold closing becomes a mold protection section, and when a molded product (foreign matter) that is not normally discharged is caught in the mold, an abnormal process is performed to avoid damage to the mold. When the preset high pressure switching position Xc is reached, the process shifts to high pressure mold clamping, and high pressure mold clamping is performed. Xd represents the mold clamping end position, and the change of the load torque T in the mold clamping operation is as shown in FIG.

Conventionally, a mold protection control method for an electric injection molding machine disclosed in Japanese Patent No. 2772587 is known as a mold protection method in the above-described mold protection section. This method performs mold closing with no foreign matter between the molds, stores loads applied to the movable mold for at least a plurality of movable mold positions set in the mold protection section, and closes the mold. Each time the operation is started, the position and load of the movable mold are detected, the detected load corresponding to the set position is compared with the stored load, and when the detected load is a predetermined value or more than the stored load In addition, the mold protection abnormality detecting means is operated to stop the operation.
JP 6-61806 Patent 2772587

  However, the conventional mold protection method in the mold clamping apparatus including the above-described mold protection control method has the following problems.

  First, since the setting of the length (end position) of the mold protection section is not regarded as important, especially in the case of an extremely thin sheet-shaped molded product, it is in a state of being sandwiched between the molds as foreign matter. It is difficult to determine whether or not there is, and it is easy to cause erroneous detection or undetection.

  Second, foreign matter detection uses a method of comparing the magnitude of a load that is an absolute value. However, since the magnitude of the load is easily affected by disturbances such as temperature drift, a threshold value for detecting foreign matter ( The (predetermined value) must be set to a large value with a margin. As a result, when a foreign object is detected, a large force (load) is applied to both the foreign object and the mold, which is insufficient from the viewpoint of protecting the mold.

  Thirdly, the mold protection section is usually set based on the numerical value set by the operator. However, in the case of the above-described extremely thin sheet-like molded product, a delicate position setting in an extremely short section is required. Therefore, the end position of the mold protection section cannot be set accurately (accurately) and easily.

  The object of the present invention is to provide a mold protecting method for a mold clamping device that solves the problems existing in the background art.

  In order to solve the above-described problems, the mold protection method for a mold clamping apparatus according to the present invention sets a predetermined mold protection section in a section in which the mold 1 is closed, and changes the physical quantity in the mold protection section. In detecting an abnormality such as a foreign substance based on this and protecting the mold 1, the mold closing position Cs is detected in advance, and at least the molded article is determined based on the mold closing position Cs and the thickness of the molded article to be molded. The end position Xf of the mold closing monitor that detects that the metal mold 1 is sandwiched between the mold 1 is set before the mold closing position Cs, and the amount of change in physical quantity associated with the closing of the mold 1 is set during production operation. If the amount of change reaches a preset value until the end position Xf is detected, an abnormality process for protecting the mold 1 is performed.

  In this case, according to a preferred aspect of the invention, the load torque T accompanying the closing of the mold 1 can be used as the physical quantity. Further, as the amount of change, the rate of change (including the amount of change) ΔT of the physical quantity with respect to the constant movement amount ΔX of the crosshead 3 in the movable platen 2 or the toggle type mold clamping device Mc when the mold 1 is closed can be used. Further, the end position Xf of the mold closing monitor is set in advance as the first mold protection section Zd1 in the section in which the mold 1 is closed, and after detecting the mold closing position Cs, Between the end position Xe of the protection section Zd1 and the mold closing position Cs, it can be set as the end position of the second mold protection section Zd2. On the other hand, on the display screen 5v of the display 5 attached to the molding machine controller 4, the position of the crosshead 3 is graduated on the horizontal axis and the physical quantity is graduated on the vertical axis, so that the physical quantity variation curve W with respect to the position of the crosshead 3 is obtained. The graphic display unit 6 for displaying the graphic is provided, and the end position Xf of the mold closing monitor can be displayed on the graphic display unit 6 by the cursor 7c. The graphic display unit 6 further includes a mold closing unit. The position Cs (Ds, Dd) can be displayed by the cursors 8c and 9c. Further, a numerical value display section 7 is provided on the display screen 5v, and the end position Xf of the mold closing monitor can be numerically displayed on the numerical value display section 7 by the position of the crosshead 3.

  According to the mold protecting method of the mold clamping device according to the present invention by such a method, the following remarkable effects are obtained.

  (1) Since the end position Xf of the mold closing monitor is set before the mold closing position Cs based on the previously detected mold closing position Cs and the thickness of the molded product, in particular, an extremely thin sheet-shaped molding Whether or not the product is in a state of being held between the mold 1 as a foreign object can be reliably determined. As a result, it is possible to avoid problems that may cause false detection or detection failure, and to improve stability and reliability with respect to mold protection.

  (2) According to a preferred embodiment, the fluctuation amount of the physical quantity is included in the fluctuation amount of the physical quantity with respect to the constant movement amount ΔX of the crosshead 3 in the movable platen 2 or the toggle type mold clamping device Mc when the mold 1 is closed. ) If ΔT is used, the threshold can be set smaller (lower) than when the physical quantity itself (absolute value) is used, so that detection can be performed more quickly. As a result, it can be detected before a large force (load) is applied to both the foreign matter and the mold, and a problem that the mold protection is insufficient can be avoided.

  (3) According to a preferred embodiment, when the end position Xf of the mold closing monitor is set, the first mold protection section Zd1 is set in advance, and after detecting the mold closing position Cs, the first mold If the second mold protection section Zd2 is set between the end position Xe of the mold protection section Zd1 and the mold closing position Cs, the second mold protection section Zd2 detects the molded product as a foreign object, Since the mold protection section Zd1 can detect a foreign matter other than a molded product or an abnormality caused by another cause, more reliable and accurate mold protection can be achieved.

  (4) According to a preferred embodiment, the physical quantity variation curve W with respect to the position of the crosshead 3 is displayed graphically on the display screen 5v by calibrating the position of the crosshead 3 on the horizontal axis and the physical quantity on the vertical axis. At the same time, if the end position Xf of the mold closing monitor is displayed by the cursor 7c and further the mold closing position Cs (Ds, Dd) is displayed by the cursors 8c, 9c, it is used as an optimum tool for setting the end position Xf. Even when a fine position setting is required in an extremely short section like the setting of the end position Xf for an extremely thin sheet-like molded product, it can be set accurately (accurately) and easily.

  (5) According to a preferred embodiment, if the numerical display unit 7 provided on the display screen 5v displays the numerical value of the end position Xf of the mold closing monitor according to the position of the crosshead 3, it is combined with the graphic display by the graphic display unit 6, Even the end position Xf for an extremely thin sheet-like molded product can be set more accurately (accurately) and easily.

  Next, the best embodiment according to the present invention will be given and described in detail with reference to the drawings.

  First, the structure of the toggle type mold clamping device Mc capable of performing the mold protection method according to the present embodiment will be described with reference to FIGS. 1 to 4 (FIG. 8).

  FIG. 2 shows an injection molding machine M, which includes a toggle type mold clamping device Mc and an injection device Mi. The toggle type mold clamping device Mc includes a fixed platen 11 and a pressure receiving plate 12 that are spaced apart from each other. The fixed platen 11 is fixed on a machine base (not shown), and the pressure receiving plate 12 moves forward and backward on the machine base. Supported as possible. Further, four tie bars 13 are laid between the fixed platen 11 and the pressure platen 12. In this case, the front ends of the tie bars 13 are fixed to the stationary platen 11, and the rear ends of the tie bars 13 are inserted into the pressure receiving plate 12 and threaded portions 14 formed on the rear end side. The adjustment nuts 15 that also serve as stoppers for the pressure receiving plate 12 are screwed together.

  Each adjustment nut 15 constitutes a mold thickness adjusting mechanism 16 that adjusts the position of the pressure receiving platen 12. The mold thickness adjusting mechanism 16 further includes small gears 17 provided coaxially with the adjustment nuts 15, a large gear 18 meshing with the small gears 17, and meshing with the large gear 18. And a mold thickness adjusting motor 20 provided with the drive gear 19 on a rotating shaft, and a rotary encoder 21 for detecting the rotational speed of the mold thickness adjusting motor 20.

  In this case, the small gears 17 are arranged at the four corners of the square, and the large gears 18 are arranged at positions surrounded by the small gears 17. Mesh. Accordingly, when the mold thickness adjusting motor 20 is operated, the rotation of the drive gear 19 is transmitted to the large gear 18, and the small gears 17 are rotated simultaneously, and the adjusting nuts 15 that rotate integrally are Since the advancing and retreating movement along the screw portions 14 of the tie bars 13...

  On the other hand, the movable platen 2 is slidably loaded on the tie bars 13. The movable platen 2 supports the movable die 1m, the fixed platen 11 supports the fixed die 1c, and the movable die 1m and the fixed die 1c constitute the mold 1. A toggle link mechanism L is disposed between the pressure receiving plate 12 and the movable platen 2. The toggle link mechanism L includes a pair of first links La and La that are pivotally supported on the pressure receiving platen 12, a pair of output links Lc and Lc that are pivotally supported on the movable platen 2, and the first links La and La and the output links Lc, A pair of second links Lb and Lb coupled to the support shaft of Lc are provided, and the second links Lb and Lb are pivotally supported on the cross head 3.

  Further, a mold clamping drive unit 22 is disposed between the pressure receiving plate 12 and the crosshead 3. The mold clamping drive unit 22 includes a ball screw portion 23 s rotatably supported by the pressure receiving plate 12, and a ball nut portion 23 n that is screwed into the ball screw portion 23 s and provided integrally with the crosshead 3. In addition to the ball screw mechanism 23, a rotation drive mechanism portion 26 that rotates the ball screw portion 23s is provided. The rotation drive mechanism 26 includes a mold clamping servomotor 25, a rotary encoder 26 attached to the servomotor 25 for detecting the rotation speed of the servomotor 25, and a drive gear 27 attached to the shaft of the servomotor 25. A driven gear 28 attached to the ball screw portion 23 s and a timing belt 29 spanned between the drive gear 27 and the driven gear 28 are provided.

  Accordingly, when the servo motor 25 is operated, the drive gear 27 is rotated, and the rotation of the drive gear 27 is transmitted to the driven gear 28 via the timing belt 29, and the ball screw portion 23s is rotated to thereby rotate the ball nut. Part 23n moves forward and backward. As a result, the cross head 3 integrated with the ball nut portion 23n moves forward and backward, the toggle link mechanism L shortens or expands, and the movable platen 2 advances and retracts in the mold opening direction (retracting direction) or the mold closing direction (forward movement direction). Moving. A molding machine controller 4 connects the mold clamping servo motor 25, the rotary encoder 26, the mold thickness adjusting motor 20, and the rotary encoder 21.

  On the other hand, FIG. 3 shows a servo circuit 31 which is a part of the molding machine controller 4. The servo circuit 31 includes deviation calculation units 32 and 33, adders 34 and 35, a position loop gain setting unit 36, a feed forward gain setting unit 37, a speed limiter 38, a speed converter (differentiator) 39, and a speed loop gain setting unit. 40, a torque limiter 41, a driver 42, a disturbance monitoring unit 43, and an acceleration converter (differentiator) 44, and a servo control system (servo circuit 31) is constituted by the system shown in FIG. The above-described mold clamping servomotor 25 is connected to the output side of the driver 42, and the rotary encoder 26 attached to the servomotor 25 is connected to the speed converter 39 and the inverting input section of the deviation calculating section 32, respectively. Connecting. Further, the non-inverting input unit of the deviation calculation unit 32 is connected to a sequence controller (not shown).

  Further, in the figure, Pt is a signal capturing terminal used for detecting the load torque T accompanying the closing of the mold 1, and Pv is a signal capturing terminal used for detecting the speed V of the movable platen 2 when the mold 1 is closed. , Pa is a signal capturing terminal used for detecting the acceleration A of the movable platen 2 when the mold 1 is closed, Pe is a signal capturing terminal used for detecting the estimated torque E generated due to disturbance due to the closing of the mold 1, Px indicates a signal take-in terminal used for detecting the positional deviation Xr of the movable platen 2 when the mold 1 is closed. In addition, operation | movement (function) of each part is demonstrated by the whole operation | movement of toggle type mold clamping apparatus Mc mentioned later.

  FIG. 4 shows a display screen 5v of the display 5 attached to a side panel or the like provided in the injection molding machine M. The display screen 5v is provided with a touch panel, and various settings and the like can be performed using the touch panel. A display screen 5v shown in FIG. 4 is a setting screen for mold opening / closing, and has a graphic display section 6 for graphically displaying a variation curve W of the load torque T, and a numerical display section 7 for the end position of the mold closing monitor. A numerical display unit 8 related to the mold closing position reference, a numerical display unit 9 related to the mold closing position, and a numerical display unit 10 related to the mold protection end position are provided.

  In this case, in the graphic display unit 6, the horizontal axis (X axis) is the position [mm] of the crosshead 3, and the vertical axis (Y axis) is the load torque T [%]. The load torque T [%] is displayed with the maximum torque being 100 [%]. As a result, the magnitude of the load torque T corresponding to the position [mm] of the crosshead 3 is graphically displayed on the graphic display unit 6 as the fluctuation curve W. Further, the graphic display unit 6 includes a cursor 7c (green) indicating the end position Xf of the mold closing monitor to be the second mold protection section Zd2, and a cursor 8c (blue) indicating the reference value Ds of the mold closing position Cs. ), A cursor 9c (red) indicating the detection value Dd of the mold closing position Cs and a cursor 10c (pink) indicating the end position Xe of the mold protection zone Zd1 are displayed by color-coded vertical lines. By displaying the color-coded cursors 7c, 8c, 9c and 10c corresponding to each item, the operator can easily and accurately (reliably) know the position corresponding to each item.

  On the other hand, the numerical value display section 7 displays the numerical value of the end position Xf of the mold closing monitor that becomes the second mold protection section Zd2 according to the position of the crosshead 3, and sets the end position Xf. The numerical display unit 8 has an ON key 7s, and a numerical display unit 8 displays a reference value Ds of the mold closing position Cs numerically according to the position of the crosshead 3, and the position of the crosshead 3 on the movable platen 2. It has the 2nd display part 8x which converts into a position and displays a numerical value. Further, the numerical display unit 9 converts the detected value Dd of the mold closing position Cs into a numerical value based on the position of the crosshead 3 and converts the position of the crosshead 3 into the position of the movable platen 2. The numerical display unit 10 includes a first display unit 10 h that displays numerical values of the end position Xe (see FIG. 1) of the mold protection zone Zd 1 according to the position of the crosshead 3. A second display portion 10x that converts the position of the crosshead 3 into the position of the movable platen 2 and displays numerical values is provided. Furthermore, the upper positions of the respective numerical display sections 7, 8, 9 and 10 are “Mold closing monitor”, “Mold closing position reference”, “Mold closing position” and “Mold protection end position”, respectively. In addition to displaying the items, color-coded color frame portions 7k (green), 8k (blue), 9k (red), and 10k (pink) are displayed around each item. The colors of the color frame portions 7k (green), 8k (blue), 9k (red), and 10k (pink) are the same as those of the cursors 7c (green), 8c (blue), 9c (red), and 10c (pink). It corresponds to the color. Thereby, the operator can easily know which item each cursor 7c, 8c, 9c and 10c corresponds to. Note that the position of the crosshead 3 can be easily converted to the position of the movable platen 2 by using a known conversion formula. The graphic display unit 6 shown in FIG. 1 is a display mode when the scale range of the horizontal axis (X axis) and the vertical axis (Y axis) is changed.

  Next, the operation (function) of the toggle type mold clamping device Mc including the mold protection method according to the present embodiment will be described with reference to FIGS.

  First, the molding machine controller 4 has a closed position detection mode for detecting the mold closed position Cs. The mold closing position Cs is a position where the movable mold 1m and the fixed mold 1c touch. In the closed position detection mode, the movement amount (displacement amount) of the crosshead 3 accompanying the closing of the mold 1 and the variation amount of the physical quantity accompanying the closing of the mold 1 are sequentially detected, and the constant movement amount ΔX of the crosshead 3 is detected. By sequentially obtaining the fluctuation rate ΔT of the physical quantity, it has a function of detecting the position when the fluctuation rate ΔT reaches a preset setting rate Ts as the mold closing position Cs.

  In this case, the fluctuation rate ΔT may be a fluctuation amount. That is, the fluctuation rate ΔT may be obtained as a fluctuation amount ΔT corresponding to the constant movement amount ΔX, or may be a fluctuation rate obtained from ΔT / ΔX. Moreover, the load torque T is used as a physical quantity. A signal related to the load torque T is obtained from the signal take-in terminal Pt described above, and a signal obtained from the signal take-in terminal Pt is given to the molding machine controller 4. Further, the amount of movement of the crosshead 3 is detected using an encoder pulse of a rotary encoder 26 that detects the number of rotations of the servo motor 25.

  On the other hand, a setting rate Ts is set in the molding machine controller 4. As shown in FIG. 1, the set rate Ts is obtained when the variation rate (increase rate) ΔT of the load torque T with respect to the constant movement amount ΔX of the crosshead 3 accompanying the closing of the mold 1 reaches the set rate Ts. Is used as a mold closing position Cs. Therefore, the magnitude of the setting rate Ts can be set as appropriate through experiments and adjustments. For example, since the load torque T is displayed as a percentage with the maximum torque being 100 [%], the constant movement amount ΔX of the crosshead 3 is set to several millimeters, and the rate of increase (increase amount) ΔT of the load torque T at this time Is obtained, the set rate Ts for the rate of increase ΔT can be set to around 1%.

  Next, a specific processing procedure will be described. First, the mold closing position Cs is detected in the closing position detection mode. The processing procedure in the closed position detection mode will be described with reference to the flowchart shown in FIG.

  Now, it is assumed that the mold 1 is in the mold open position (fully open position). Therefore, the crosshead 3 in the toggle link mechanism L is in the mold opening position Xa shown in FIG. When the mold clamping operation is started, the mold clamping servomotor 25 is operated, the crosshead 3 moves forward, and the movable platen 2 moves forward from the mold opening position to the mold closing direction. At this time, first, high-speed mold closing is performed in which the movable platen 2 moves forward at high speed.

  In this case, the servo circuit 31 performs speed control and position control for the movable platen 2 (crosshead 3). That is, a position command value is given from the sequence controller to the deviation calculation unit 32 of the servo circuit 31 and compared with a position detection value obtained based on the encoder pulse of the rotary encoder 26. Thereby, since the position deviation Xr is obtained from the deviation calculating section 32, position feedback control is performed based on the position deviation Xr.

  The position deviation Xr is compensated by the position loop gain setting unit 36 and applied to the input unit of the adder 34, and the position command value is compensated by the feedforward gain setting unit 37 and input to the adder 34. To be granted. Then, the output of the adder 34 is given to the non-inverting input unit of the deviation calculating unit 33 via the speed limiter 38. On the other hand, the position detection value is differentiated by the speed conversion unit 39 and converted into a speed (speed detection value) V, and the speed V is given to the inverting input unit of the deviation calculation unit 33. As a result, a speed deviation is obtained from the deviation calculator 33, and speed feedback control is performed based on this speed deviation. In this case, the speed V is limited by the speed limiter 38.

  Further, the speed deviation is compensated by the speed loop gain setting unit 40 and is given to the input unit of the adder 35. On the other hand, the velocity V is differentiated by the acceleration conversion unit 44 and converted into acceleration (acceleration detection value) A, and this acceleration A is given to the input unit of the disturbance monitoring unit 43. The disturbance monitoring unit 43 monitors the acceleration A and, for example, outputs an estimated torque (torque value) E that speeds recovery when the acceleration A abnormally changes due to some cause (disturbance). The estimated torque E is given as a correction value to the input unit of the adder 35. As a result, a torque command (command value) is obtained from the adder 35, and this torque command is given to the driver 42 via the torque limiter 41. Thereby, the servo motor 25 is driven and controlled, and the position control and speed control for the movable platen 2 (cross head 3) are performed. The torque command output from the torque limiter 41 is fed back to the input unit of the disturbance monitoring unit 43.

  On the other hand, when the movable platen 2 moves forward in the mold closing direction and the crosshead 3 reaches the preset low-speed / low-pressure switching point Xb, the process shifts to low-speed / low-pressure mold closing (step S1). In this low-speed and low-pressure mold closing, as shown in FIG. 8, a mold protection process such as foreign object detection is performed in the mold protection section Zd1 set in the previous stage. That is, in the mold protection section Zd1, the magnitude of the load torque T is monitored, and if a preset threshold value is exceeded, it is determined that there is a foreign object and abnormal processing such as mold opening control is performed.

  As shown in FIG. 1 (FIG. 4), the end position Xe of the mold protection section Zd1 is set in advance by the numerical value display unit 10 that also functions as a setting function. Since this end position Xe is set in a preliminary manner before detecting the normal mold closing position Cs (reference value Ds), it is set with some margin before the assumed mold closing position. can do. In setting, a numerical value is set in the first display section 10h according to the position of the crosshead 3. In this case, for example, a known setting method of inputting numerical values by touching the first display unit 10h and displaying a numeric key window can be used. By setting the end position Xe, the graphic display unit 6 displays the cursor 10c corresponding to the set end position Xe. Since the color (pink) of the cursor 10c matches the color (pink) of the color frame portion 10k displayed on the numerical value display portion 10 as described above, the operator uses the cursor 10c to determine the end position Xe. Can be easily and accurately known, and the end position Xe corresponding to the mold protection section Zd1 can be easily and reliably known.

  Then, when the mold protection section Zd1 is completed, the mold closing position Cs for the mold 1 is detected. That is, an increase rate monitoring process for monitoring the magnitude of the increase rate ΔT for detecting the mold closing position Cs is performed (step SP). In FIG. 1 and FIG. 8, Zd2 indicates a second mold protection section for performing mold closing monitoring, but at this point, it has not been set yet. In the increase rate monitoring process, first, the molding machine controller 4 detects the position of the crosshead 3 (step S2). The position of the crosshead 3 is detected by using an encoder pulse of a rotary encoder 26 that detects the rotation speed of the mold clamping servomotor 25. In this case, the rotary encoder 26 is an incremental encoder and detects the absolute position based on the number of encoder pulses generated with respect to the reference position. By using such a rotary encoder 26, a separate position detecting means for detecting the position of the crosshead 3 is not required. As described above, by using the displacement amount (movement amount) of the crosshead 3 having a relatively large movement amount with respect to the movement amount of the movable platen 2, it is possible to detect the mold closing position Cs with high accuracy. it can. As a result, the amount of fluctuation of the mold clamping force Fm, which will be described later, can be detected accurately, so that the mold clamping force Fm can be accurately corrected.

  Further, the molding machine controller 4 sequentially takes in the load torque T, for example, at a sampling period of every 500 [μsec], and obtains a moving average of N times by averaging processing (steps S3 and S4). As a result, the obtained load torque T is graphically displayed as a fluctuation curve W on the graphic display unit 6 as shown in FIG. 4 (FIG. 1), corresponding to the detected position of the crosshead 3.

  Further, by obtaining the displacement amount (movement amount) of the crosshead 3 and the fluctuation amount of the load torque T, an increase amount (increase rate) ΔT of the load torque T with respect to the constant movement amount ΔX of the crosshead 3 is obtained (step S5). ). In this case, for example, when the constant movement amount ΔX of the crosshead 3 is set to several millimeters, a corresponding increase amount (increase rate) ΔT [%] of the load torque T is obtained. Then, it is monitored whether or not the rate of increase ΔT has reached a preset set rate Ts. If the rate of increase ΔT reaches the set rate Ts, the position of the crosshead 3 at that time is determined as the mold closing position Cs. (Steps S6 and S7). The taken-in mold closing position Cs is set as a reference value Ds (step S8).

  On the other hand, the reference value Ds is displayed by the cursor 8c on the graphic display unit 6 on the display screen 5v. Since the color (blue) of the cursor 8c matches the color (blue) of the color frame portion 8k displayed on the numerical value display portion 8 as described above, the operator uses the cursor 8c to measure the reference value Ds. As well as the reference value Ds of the mold closing position Cs can be easily and reliably known. The reference value Ds is numerically displayed on the first display portion 8h, converted to the position of the movable platen 2, and displayed on the second display portion 8x. The above description is a basic mode of the closed position detection mode, and the actual reference value Ds (and the detected value Dd) is obtained by executing the closed position detection mode a plurality of times and obtaining a plurality of closed positions obtained as described later. It can be obtained from the average.

  Furthermore, when the reference value Ds is set, the operator displays a numerical value that also serves as a setting function for the end position Xf of the mold closing monitor that becomes the second mold protection zone Zd2 with reference to the reference value Ds. Manual setting is performed using the unit 7 (step S9). That is, the operator displays the end position Xf of the second mold protection zone Zd2 with reference to the cursor 8c related to the reference value Ds displayed on the graphic display unit 6 and the numerical display of the first display unit 8h. A numerical value is set in the section 7h. In this case, the end position Xf is set according to the position of the crosshead 3. The end position Xf is set in consideration of the thickness of the molded product. For example, when the thickness of the molded product is 0.1 [mm], the end position Xf can be set between the mold closing position Cs and the front 0.1 [mm]. In the present embodiment, since the end position Xf is set by the position of the crosshead 3 having a relatively large displacement amount with respect to the movement amount of the movable platen 2, a thin sheet having a thickness of about 0.1 [mm]. The end position Xf can be set easily and with high accuracy even in the case of the molded product.

  When the end position Xf is set on the display unit 7h, the end position Xf of the mold closing monitor that becomes the second mold protection zone Zd2 is displayed on the graphic display unit 6 by touching the ON key 7s. Is displayed. Since the color (green) of the cursor 7c matches the color (green) of the color frame portion 7k displayed on the mold closing monitor setting unit 7 as described above, the operator uses the cursor 7c to move the end position. The degree of Xf can be easily and accurately known, and the end position Xf of the mold closing monitor that becomes the second mold protection zone Zd2 can be easily and reliably known.

  Next, the operation during production operation will be described according to the flowchart shown in FIG. 6 (FIG. 7).

  Assume that the production operation is performed by automatic molding (step S11). In this case, the reference value Ds described above is set in advance. During production operation, when the preset closed position detection time or the number of closed position detection shots is reached, the closed position detection mode is automatically executed (steps S12 and S13). The execution interval of the closed position detection mode may be performed every time a shot is performed, or may be performed every fixed shot (or a fixed time), and is set in consideration of the variation degree of the mold clamping force Fm in the actual machine. Can do.

  The processing procedure in the closed position detection mode during production operation will be described with reference to the flowchart shown in FIG. Now, it is assumed that the mold 1 is in the mold open position (fully open position). Therefore, the crosshead 3 in the toggle link mechanism L is in the mold opening position Xa shown in FIG. When the mold clamping operation is started, the mold clamping servomotor 25 is operated, and the movable platen 2 moves forward in the mold closing direction from the mold opening position. At this time, the movable platen 2 is first subjected to high-speed mold closing that moves forward at high speed (step S21). Then, when the movable platen 2 moves forward in the mold closing direction and the crosshead 3 reaches a preset low speed / low pressure switching point Xb, the process shifts to low speed / low pressure mold closing (step S22). In this low-speed low-pressure mold closing, as shown in FIG. 8, first, a detection process for abnormalities such as foreign matters is performed in the first mold protection zone Zd1. As described above, in the detection process in the mold protection zone Zd1, the magnitude of the load torque T is monitored, and if a predetermined threshold value is exceeded, it is determined that there is a foreign object and abnormal processes such as mold opening control are performed. Done. Therefore, in the first mold protection zone Zd1, it is possible to detect a foreign matter other than the molded product or an abnormality caused by another cause.

  Further, when the mold protection section Zd1 is completed, a monitoring process is performed to determine whether or not the molded product has been sandwiched between the mold 1 as a foreign object by the mold closing monitor that becomes the second mold protection section Zd2. (Steps S23, S24, S25). In this case, the monitoring process is performed under the same conditions as the case where the mold closing position Cs is detected by monitoring the rate of increase (variation rate) ΔT of the load torque T with respect to the constant movement amount ΔX of the crosshead 3. . Therefore, in a specific process, when the first mold protection section Zd1 is completed, the same process as step SP of the flowchart shown in FIG. 5 which is a process for detecting the mold closing position Cs is executed. If the rate of increase ΔT reaches the set rate Ts by the end position Xf of the second mold protection section Zd2, it is determined that the molded product is sandwiched between the mold 1 as foreign matter. When the abnormality rate is increased and the rate of increase ΔT reaches the set rate Ts after passing through the mold protection zone Zd2, it is determined as a mold closing position Cs described later. Further, as the abnormality processing, processing for protecting the mold 1 such as mold opening control and alarm notification is immediately executed.

  In such a second mold protection section Zd2 (mold closure monitor), as described above, for example, when the thickness of the molded product is 0.1 [mm], it is 0. Since the end position Xf is set between 1 mm, it is possible to detect a thin sheet-like molded product remaining in the mold 1 without being discharged when the mold is opened. Even a sheet-like molded product of about 09 mm can be reliably detected. In particular, since it is used together with the first mold protection zone Zd1, the first mold protection zone Zd1 can detect foreign matter other than the molded product or an abnormality caused by other causes, and the second mold protection zone Zd2 can detect the molded product. Can be detected as a foreign substance, and more reliable and accurate mold protection can be achieved. In addition, since monitoring is performed using the variation rate (including variation amount) ΔT of the load torque T with respect to the constant movement amount ΔX of the crosshead 3, the threshold value (setting rate Ts) is compared with the case where the load torque T itself (absolute value) is used. ) Can be set low, so that detection can be performed more quickly. As a result, it can be detected before a large force (load) is applied to both the foreign matter and the mold 1, and a problem that the mold protection is insufficient can be avoided.

  On the other hand, if the mold closing monitor (mold protection section Zd2) is completed, the mold closing position Cs for the mold 1 is detected by the closing position detection section Zc (step S25, SP). As described above, in this detection process, the same detection process as that in the second mold protection section Zd2 is continued. Then, if the increase rate ΔT detected after passing the end position Xf of the mold protection zone Zd2 reaches the preset set rate Ts, it is determined as the mold closing position Cs, and the process proceeds to high pressure mold clamping. High pressure mold clamping is performed (step S26). At the same time, the position of the crosshead 3 when the increase rate Ts reaches the set rate Ts is detected, and this position is taken as the detection value Dd of the mold closing position Cs (steps S27 and S28). As described above, by setting the mold protection sections Zd1 and Zd2 and the closing position detection section Zc, the mold closing position Cs is detected after the mold protection sections Zd1 and Zd2 are completed. The protection process for the mold 1 and the detection process of the mold closing position Cs can be performed stably and reliably without causing interference.

  Then, the detected detection value Dd is numerically displayed on the first display portion 9h and the second display portion 9x of the numerical value display portion 9 on the display screen 5v, and is displayed on the graphic display portion 6 by the cursor 9c. Since the color (red) of the cursor 9c matches the color (red) of the color frame portion 9k displayed on the numerical value display unit 9 as described above, the operator uses the cursor 9c to determine the extent of the detected value Dd. Can be easily and accurately known, and the detected value Dd of the mold closing position Cs can be easily and reliably known.

  Further, the closed position detection mode is executed a plurality of times set in advance, and the detection value Dd is obtained from the average of the plurality of mold closing positions Cs... Obtained (steps S13, S14, S15). As a result, a highly reliable detection value Dd from which noise components have been removed is obtained. When the detection value Dd is obtained, a deviation Ke from the preset reference value Ds, that is, Ke = Ds−Dd is obtained (step S16). If the deviation Ke is obtained, the correction for the end position Xe of the mold closing section Zd1 and the end position Xf of the mold closing monitor that becomes the second mold protection section Zd2 is corrected based on the deviation Ke. Do. Correction for the end positions Xe and Xf is performed as follows. Load torques Tf and Tr indicated by phantom lines in FIG. 8 indicate cases where the mold clamping force Fm varies. The load torque Tr is a fluctuation curve when the mold 1 is heated and thermally expanded, and is detected as the mold closing position Cr before the normal mold closing position Cs. In this case, the mold clamping force Fm increases. Therefore, if the mold opening position is the starting point (0) of the distance, the end position Xf (Xe) is corrected to be decreased by the deviation Ke. That is, in FIG. 8, Zc indicates the above-described closing position detection section between the end position Xf (Xe) and the mold closing position Cs, but when the mold closing position Cs is displaced, this closing position detection section Zc. The end position Xf (Xe) is corrected so that the distance is always constant.

  In particular, the load torque Tr shown in FIG. 8 is a fluctuation curve when the mold 1 is further heated, and the state in which the movable mold 1m starts to contact the fixed mold 1c before the end position Xf (Xe). Show. In this case, unless the end position Xf (Xe) is corrected, it is difficult to determine whether the variation of the load torque Tr is due to the contact between the movable mold 1m and the fixed mold 1c based on normal operation or due to the detection of foreign matter. As a result, erroneous detection occurs. However, by correcting the end position Xf (Xe), it is possible to stably and reliably perform both the detection process of foreign matter and the detection process of the mold closing position Cs according to the present embodiment without interfering with each other. .

  Similarly, the load torque Tf is a variation curve when the tie bars 13 are heated and thermally expanded, and is detected as the mold closing position Cf at a position past the normal mold closing position Cs. In this case, the mold clamping force Fm is reduced. Therefore, the end position Xf (Xe) is corrected to increase by the deviation Ke. In FIG. 8, Xd indicates a mold clamping end position. Even the mold closing positions Cs, Cf, Cr related to the fluctuation of the mold clamping force Fm can be accurately detected by the above-described closing position detection mode.

  On the other hand, since the allowable range Re for the deviation Ke is set in the molding machine controller 4 in advance, the allowable range Re is compared with the obtained deviation Ke to determine whether the deviation Ke exceeds the allowable range Re. judge. As a result, when the deviation Ke is within the allowable range Re, the mold clamping force Fm is not corrected. Therefore, the production operation is continued as it is (steps S17 and S11).

  On the other hand, when the deviation Ke exceeds the allowable range Re, the detection value Dd is detected again (steps S17, S18, S11). That is, in the illustrated example, the detection value Dd is continuously detected a plurality of times, and if the obtained deviation Ke continuously exceeds the allowable range Re, the mold clamping force Fm is corrected (steps S19 and S20). For example, when the detected value Dd is detected twice in succession and the obtained deviation Ke... Exceeds the allowable range Re twice, the mold clamping force Fm is corrected. Therefore, when the allowable range Re is exceeded only once, it is determined that the cause is a temporary factor due to disturbance or the like, and correction is not performed. Thereby, stability and reliability when performing correction can be enhanced.

  On the other hand, the correction processing procedure for the mold clamping force Fm is as follows. The illustration shows an example in which the correction is performed when the deviation Ke exceeds the allowable range Re continuously a plurality of times, and thus a plurality of deviations Ke are obtained. Therefore, in this example, a plurality of deviations Ke are averaged to obtain an average value. In the case of a plurality of deviations Ke, the average value may be used, or the latest deviation Ke may be used. Since the deviation Ke is a deviation with respect to the position of the crosshead 3, the deviation Ke is converted into a deviation with respect to the position of the movable platen 2 by a known conversion formula. Thereby, since the correction amount Ks for the movable platen 2 is obtained, the pressure receiving platen 12 is corrected to be displaced by this correction amount Ks. Thereby, the deviation Ke is canceled out.

  In this case, the correction process is performed at a specific timing set in advance without interrupting the molding cycle. As a specific timing without interrupting the molding cycle, a period other than the high-pressure mold clamping period, specifically, a mold opening period, a protruding period, an intermediate period, or the like can be used. Therefore, for example, if the protruding period is set as a period for performing the correction process, a correction command is output at the start timing of the protruding period, and the correction process is executed based on the correction command.

  In the correction process, first, the mold thickness adjusting motor 20 is driven and controlled based on the correction amount Ks, and the pressure receiving platen 12 is displaced in a direction in which the deviation Ke is eliminated. At this time, the pressure receiving platen 12 is moved at a lower speed than the normal speed. Further, the position of the pressure receiving platen 12 is detected by using an encoder pulse of a rotary encoder 21 attached to the mold thickness adjusting motor 20 to perform feedback control on the position. The rotary encoder 21 is an incremental encoder and detects an absolute position based on the number of encoder pulses generated with respect to a reference position. When the pressure receiving platen 12 is moved to the target position corresponding to the correction amount Ks (deviation Ke), the mold thickness adjusting motor 20 is controlled to stop. Such automatic correction processing enables timely and quick correction. On the other hand, the correction process can also be performed using the existing automatic mold clamping force setting function (automatic mold thickness adjusting function) in the toggle type mold clamping device Mc as it is. The automatic mold clamping force setting function is a function in which the mold clamping force is automatically set by setting a target value of the mold clamping force at an initial stage, for example, at the time of mold replacement. If such an existing automatic mold clamping force setting function is used, there is an advantage that more accurate correction can be performed and the cost is advantageous.

  Note that manual correction by an operator is also possible for such automatic correction. In manual correction, an allowable range Re with respect to the deviation Ke is set in advance, and if the deviation Ke exceeds the allowable range Re, it is only necessary to be notified by an alarm or the like, and based on this, the operator performs correction manually. be able to. This makes it possible to make corrections that take into account the experience and know-how of the operator, and if necessary, depending on the type of molded product, it can be determined that correction is not necessary, and production can be prioritized. Therefore, the production operation (automatic molding) is continued as it is until the operator performs an operation for correction. Such manual correction and automatic correction may be used alone or in combination. Such a correction processing method can be selected in advance by the selection key 51 on the display screen 5v of the display 5.

  As described above, according to the mold protecting method for the mold clamping device according to the present embodiment, the mold closing is performed before the mold closing position Cs based on the mold closing position Cs and the thickness of the molded product detected in advance. Since the monitor end position Xf is set, it is possible to reliably determine whether or not an extremely thin sheet-like molded product is sandwiched between the molds 1 as foreign matter. As a result, it is possible to avoid problems that may cause false detection or detection failure, and to improve stability and reliability with respect to mold protection. In particular, when setting the end position Xf of the mold closing monitor that becomes the second mold protection zone Zd2, the horizontal axis indicates the position of the crosshead 3 and the vertical axis indicates the physical quantity on the display screen 5v. Thus, the physical quantity variation curve W with respect to the position of the crosshead 3 is displayed graphically, the end position Xf of the mold closing monitor is displayed by the cursor 7c, and the mold closing position Cs (Ds, Dd) is further displayed by the cursor 8c, Since it is displayed by 9c, it can be used as an optimum tool for setting the end position Xf, and it is a case where delicate position setting is required in an extremely short section, such as setting the end position Xf for an extremely thin sheet-like molded product. However, it can be set accurately (accurately) and easily. Moreover, if the end position Xf of the mold closing monitor is numerically displayed by the position of the crosshead 3 on the numerical display 7 provided on the display screen 5v, it is combined with the graphic display by the graphic display 6 to form an extremely thin sheet. Even the end position Xf for the product can be set more accurately (accurately) and easily.

  As described above, the best embodiment has been described in detail, but the present invention is not limited to such an embodiment, and the details, methods, configurations, numerical values, and the like are within the scope not departing from the gist of the present invention. It can be changed, added, or deleted arbitrarily.

  For example, an abnormality such as a foreign object is a concept including not only a case where a molded product is sandwiched between molds 1 but also various abnormalities such as a failure or partial breakage of the mold 1 or the like. Further, although the output (torque monitor) of the driver 42 is used as the load torque T, a torque command that is an input of the torque limiter 41 may be used. On the other hand, the load torque T associated with the closing of the mold 1 is used as a physical quantity in the detection of the mold closing position Cs. However, as other physical quantities, the speed V of the crosshead 3 associated with the closing of the mold 1 and the mold 1 The acceleration A of the crosshead 3 accompanying the closing, the estimated torque E generated by the disturbance accompanying the closing of the mold 1, the position deviation Xr of the crosshead 3 accompanying the closing of the mold 1, etc. can also be used. These physical quantities including the load torque T may be used alone or in combination. By combining them, the reliability can be further improved. Furthermore, although the movement amount (displacement amount) of the crosshead 3 is used as the movement amount, the movement amount of the movable platen 2 can be directly used as necessary. Further, if necessary, it is possible to use only the second mold protection section Zd2 without using the first mold protection section Zd1.

The display screen figure which extracted a part of display for explaining the metallic mold protection method concerning the best embodiment of the present invention, Configuration diagram of a toggle type mold clamping device suitable for use in the implementation of the mold protection method, A block circuit diagram showing a part of a molding machine controller provided in the toggle type mold clamping device, A display screen diagram of a display used to implement the mold protection method, The flowchart which shows the processing procedure of closed position detection mode at the time of initial setting relevant to the mold protection method, A flowchart showing a processing procedure of a mold clamping force correction method related to the mold protection method, The flowchart which shows the processing procedure of closed position detection mode at the time of production operation relevant to the mold protection method, Variation curve diagram of load torque with respect to the position of the crosshead for explaining the mold protection method, Variation curve diagram of load torque with respect to the position of the crosshead for explaining the background art,

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Movable board 3 Crosshead 4 Molding machine controller 5 Display 5v Display screen 6 Graphic display part 7 Numerical display part 7c ... Cursor Mc Toggle type clamping device Cs Mold closing position Xf Mold closing monitor (second mold End position of mold protection section Xe End position of first mold protection section Zd1 First mold protection section Zd2 Second mold protection section (mold closing monitor)
W Fluctuation curve T Load torque ΔT Physical quantity fluctuation rate (variation quantity)
ΔX Constant travel

Claims (7)

  In a mold protection method for a mold clamping device, in which a predetermined mold protection section is set in a section for closing a mold and an abnormality such as a foreign object is detected based on a change in physical quantity in the mold protection section to protect the mold. Detecting the mold closing position in advance and ending the mold closing monitor for detecting at least that the molded product is sandwiched between the molds based on the mold closing position and the thickness of the molded product to be molded The position is set before the mold closing position, and the fluctuation amount of the physical quantity accompanying the mold closing is detected during production operation, and the fluctuation amount reaches a preset set value by the end position. Then, a mold protecting method for a mold clamping device, wherein an abnormal process for protecting the mold is performed.   2. The mold protection method for a mold clamping apparatus according to claim 1, wherein a load torque associated with mold closing is used as the physical quantity.   The fluctuation amount (including fluctuation amount) of the physical quantity with respect to a constant movement amount of a crosshead in a movable platen or a toggle type mold clamping device that accompanies closing of the mold is used as the fluctuation amount of the physical quantity. 2. A mold protecting method for a mold clamping apparatus according to 1.   The end position of the mold closing monitor is set in advance in the first mold protection section in the section for closing the mold, and after detecting the mold closing position, the end position of the first mold protection section 2. The mold protection method for a mold clamping device according to claim 1, wherein the mold protection device is set as an end position of a second mold protection section between an end position and the mold closing position.   A graphic for graphically displaying the variation curve of the physical quantity with respect to the position of the crosshead by marking the position of the crosshead on the horizontal axis and the physical quantity on the vertical axis on the display screen of the display attached to the molding machine controller. 2. The mold protection method for a mold clamping apparatus according to claim 1, wherein a display unit is provided, and an end position of the mold closing monitor is displayed on the graphic display unit with a cursor.   6. The mold protection method for a mold clamping apparatus according to claim 5, wherein the mold closing position is displayed on the graphic display unit with a cursor.   6. The mold clamping device according to claim 5, wherein a numerical value display portion is provided on the display screen, and an end position of the mold closing monitor is numerically displayed on the numerical value display portion according to a position of the crosshead. Mold protection method.

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