JP2014240162A - Valve gate control device of injection molding machine - Google Patents

Valve gate control device of injection molding machine Download PDF

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JP2014240162A
JP2014240162A JP2013123544A JP2013123544A JP2014240162A JP 2014240162 A JP2014240162 A JP 2014240162A JP 2013123544 A JP2013123544 A JP 2013123544A JP 2013123544 A JP2013123544 A JP 2013123544A JP 2014240162 A JP2014240162 A JP 2014240162A
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valve gate
load torque
disturbance load
disturbance
limit value
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吉岡 光志
Mitsushi Yoshioka
光志 吉岡
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ファナック株式会社
Fanuc Ltd
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Abstract

PROBLEM TO BE SOLVED: To provide a valve gate control device of an injection molding machine in which an operator does not need to set a value that determines an abnormal load from estimation disturbance load torque, and can set it automatically.SOLUTION: A valve gate control device is that in a valve gate operation in which a servomotor 10 is made a driving source, a disturbance estimation observer that estimates disturbance torque added to the servomotor 10 is built in a control device 1, and disturbance load torque of each molding cycle at a valve gate operation time is estimated by the disturbance estimation observer. In addition, in memory means (for example, RAM24 for data storage), time or the estimation disturbance load torque to a valve gate position of the newest one time before the molding cycle or two or more times is memorized. Basis disturbance load torque is obtained from the memorized estimation disturbance load torque, an allowable ceiling value is obtained from the basis disturbance load torque, and further, when estimation disturbance load torque of a present valve gate operation time exceeds the allowable ceiling value, an abnormal signal is output.

Description

  The present invention relates to an injection molding machine, and more particularly to an injection molding machine capable of confirming an abnormality in valve gate operation.
There is a hot runner mold that eliminates unnecessary runners for injection molding. Some hot runners use a valve gate in the resin supply section (see Patent Documents 1 and 2). Pneumatic and hydraulic cylinders are used to open and close these valve gates. The features of hydraulic and pneumatic cylinder drive sources are as follows.
(Features of hydraulic cylinder): Maintenance is troublesome. Dirty. It takes time for the oil temperature to stabilize. High power consumption. More power than air pressure.
(Features of pneumatic cylinder): Maintenance is easier than hydraulic pressure. If it is not larger than the hydraulic pressure, the same force cannot be produced. Response time is slow. There is variation in response time.
For this reason, a servo motor is increasingly used as a drive source. The features of the servo motor drive source are as follows.
(Characteristics of servo motor): The opening / closing speed can be adjusted. Good repeatability. No piping required. Reduced initial sample preparation time. Good responsiveness. Clean and quiet. Energy efficient. The parts are expensive.
Japanese Patent No. 3759827 JP 2006-239863 A
  When driving the valve gate, the servo motor drive source is superior in various aspects to the hydraulic and pneumatic types. However, even if the drive source is changed, if metal pieces, stones, etc. are contained in the resin, it will be clogged in the valve gate, or the valve gate itself will be deteriorated and damaged. May break.
  Described below are the drawbacks of using a servo motor to improve these problems. In a method for detecting an abnormal load by comparing the estimated disturbance load torque obtained by the disturbance estimation observer with the set allowable value, the allowable value must be set. Since the allowable range of load differs depending on the mold, and the friction of the valve gate and the resin resistance differ, the set allowable value for determining a load abnormality also varies depending on the mold. Therefore, it is necessary to set an allowable value for judging this load abnormality every time the mold is replaced. When the maximum value within the optimum allowable range is not set as the allowable value, and a set value larger than the maximum value of the allowable range is set, the valve gate and the cavity may be damaged.
  Also, when an allowable value smaller than the maximum value within the allowable range is set, disturbance load torque that changes due to valve gate mechanism friction, resin resistance variation, etc. for each valve gate operation is set to this setting. In spite of the normal valve gate operation exceeding the allowable value, an alarm or the like is output as a load abnormality and the operation is stopped, resulting in a decrease in production efficiency. Therefore, it is necessary to set an optimum value for determining an abnormal load for each mold. However, as described above, since the allowable value varies depending on the mold, the operator who sets the allowable value needs knowledge and experience of the mold. Even if there is knowledge and experience, it is very difficult to set an optimum tolerance.
  SUMMARY OF THE INVENTION An object of the present invention is to provide a valve gate control device for an injection molding machine that can automatically set a value for determining an abnormal load from an estimated disturbance load torque without requiring an operator to set the value.
  According to the first aspect of the present invention, in a valve gate operation using a servo motor as a drive source, a disturbance estimation observer for estimating a disturbance torque applied to the servo motor is incorporated into a control device, and the valve for each molding cycle is incorporated by the disturbance estimation observer. Estimate the disturbance load torque during gate operation. Then, the estimated disturbance load torque with respect to the valve gate operation time or valve gate position for the latest one time or a plurality of times before the molding cycle is stored in the storage means. Means for obtaining a reference disturbance load torque from the stored estimated disturbance load torque and means for obtaining an allowable upper limit value from the reference disturbance load torque are provided, and the estimated disturbance load torque during the current valve gate operation is greater than the allowable upper limit value. A valve gate control device including a determination unit that outputs an abnormal signal when the value is large.
  According to the first aspect of the present invention, the allowable range for determining an abnormal load in the valve gate operation is changed from the estimated disturbance load torque obtained during the previous one or more normal valve gate operations to the reference disturbance load torque. Since the abnormal load is determined based on the reference disturbance load torque, the operator does not need to set a reference value for determining the abnormal load.
  In the invention according to claim 2, in particular, when an abnormal signal is output, the estimated disturbance load torque during the valve gate operation is not included in the reference disturbance load torque.
  In the invention according to claim 2, the reference disturbance load torque is obtained based on the data obtained by the normal valve gate operation, and the abnormal load is determined by the allowable range obtained from the reference disturbance load torque. The abnormal load is more accurately determined optimally.
  In the invention according to claim 3, the allowable upper limit value can be arbitrarily set on the screen, and the estimated disturbance load torque, the reference disturbance load torque and the upper limit value during the current valve gate operation are displayed on the screen. The deviation between the reference disturbance load torque and the estimated disturbance load torque at the time of the current valve gate operation is displayed as a graph with respect to time or valve gate (valve pin) position.
  In the invention according to claim 3, since the allowable range obtained by the reference disturbance load torque is not a uniform value but a waveform between valve gate strokes, the optimum range according to the position of the valve gate (valve pin) is obtained. It is within the allowable range, and the abnormal load can be determined more accurately.
  In the invention according to claim 4, the means for obtaining the allowable upper limit value also obtains the allowable lower limit value from the reference disturbance load torque, and the discriminating means determines the estimated disturbance load torque during the current valve gate operation as the allowable lower limit value. An abnormal signal is also output when the value is exceeded.
  In the invention according to claim 5, particularly, in a predetermined cycle after the start of fully automatic molding, the estimated disturbance load torque of the cycle is not included in the data for obtaining the reference disturbance load torque. A predetermined number of cycles can be set on the screen of the display means after the start of fully automatic molding which is not included in the data for obtaining the reference disturbance load torque.
  In the invention according to claim 7, the reference disturbance load torque is an average value of estimated disturbance load torques during valve gate operation in a plurality of molding cycles before the molding cycle.
  According to the present invention, it is possible to provide a valve gate control device for an injection molding machine that can automatically set a value for determining an abnormal load from an estimated disturbance load torque without requiring an operator to set the value.
It is a principal part block diagram of the control apparatus of the injection molding machine which comprises the valve gate control apparatus of one Embodiment of this invention. It is a flowchart of the valve gate abnormal load detection control process in the same embodiment of the present invention. It is a continuation of the flowchart of the valve gate abnormal load detection control processing in the same embodiment of the present invention of FIG. It is explanatory drawing of the table provided in RAM for data storage in the embodiment. It is an example of the valve gate abnormal load detection control setting display screen in the display apparatus of the embodiment. It is a figure explaining operation | movement of a valve gate.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 6 shows an example of opening and closing the valve pin 2 of the hot runner valve gate. The valve gate includes a valve pin 2 that moves linearly and a valve gate that rotates and reciprocates. Since both the valve pin 2 and the valve gate have the same function, a description will be given here of a linear reciprocating movement. The valve pin 2 is driven by a servo motor directly or through a mechanism.
  FIG. 1 is a block diagram of an embodiment of a control device 1 for an injection molding machine constituting a valve gate control device of the present invention. The control device 1 is an injection molding machine via a CNC CPU 25 which is a numerical control microprocessor, a PMC CPU 21 which is a microprocessor for a programmable machine controller, a servo CPU 22 which is a servo control microprocessor, and an A / D converter 12. A pressure monitor CPU 20 that performs sampling processing and stores a signal from a sensor that detects various pressures such as injection pressure provided on the main body side and stores it in the RAM 14, and selects mutual input / output via the bus 30. Therefore, information can be transmitted between the microprocessors.
  The PMCCPU 21 is connected to a ROM 15 that stores a sequence program for controlling the sequence operation of the injection molding machine and a RAM 16 that is used for temporary storage of calculation data. The CNC CPU 25 is an automatic operation program that controls the entire injection molding machine. Are connected to a ROM 27 storing RAM and the like and a RAM 28 used for temporary storage of calculation data.
  The servo CPU 22 is connected to a ROM 17 that stores a control program dedicated to servo control that performs processing of a position loop, a speed loop, and a current loop, and a RAM 18 that is used for temporary storage of data. Connected to the pressure monitor CPU 20 are a ROM 13 that records a control program for control performed by the pressure monitor CPU 20 and a RAM 14 that records the pressures detected by the various sensors described above. Further, a servo amplifier 19 that drives the servo motor 10 for each axis such as mold clamping, injection, screw rotation, ejector, and valve gate is connected to the servo CPU 22 based on a command from the CPU 22. The output from the position / speed detector 11 attached to each axis servo motor 10 is fed back to the servo CPU 22. The current position of each axis is calculated by the servo CPU 22 based on the position feedback signal from the position / velocity detector 11, and is updated in the current position storage register of each axis.
  FIG. 1 shows only a servo motor 10 that drives a valve gate and a position / speed detector 11 that is attached to the servo motor 10 and detects the position of the valve gate (valve pin 2) by the rotational position of the servo motor. However, the configurations of the axes for clamping, injection, ejector, etc. are all the same.
  The interface 23 is an input / output interface for receiving signals from limit switches and operation panels provided in each part of the injection molding machine body and transmitting various commands to peripheral devices of the injection molding machine. A manual data input device 29 with an LCD (Liquid Crystal Display) is connected to the bus 30 via the LCD display circuit 26 so that a graph display screen and a function menu can be selected and various data can be input. A numeric keypad for inputting numeric data and various function keys are provided.
  A data storage RAM 24 composed of a non-volatile memory is a molding data storage memory for storing molding conditions relating to injection molding work, various set values, parameters, macro variables, and the like. In relation to the present invention, a table for storing data of estimated disturbance load torque values described later is provided in the data storage RAM 24.
  With the above configuration, the PMC CPU 21 controls the sequence operation of the entire injection molding machine, and the CNC CPU 25 issues a movement command to the servo motors of the respective axes based on the operating program in the ROM 27 and the molding conditions stored in the data storage RAM 24. Servo CPU 22 performs position loop control and speed loop control as in the prior art based on the movement command distributed to each axis and the position and speed feedback signals detected by position / speed detector 11. Further, servo control such as current loop control is performed, and so-called digital servo processing is executed.
  The above-described configuration is the same as the control device of the conventional electric injection molding machine, and the valve gate control device of the present invention is configured by this control device 1. The difference from the conventional control device is that the data storage RAM 24 composed of a non-volatile memory has the disturbance load torque value data estimated by the disturbance estimation observer for each predetermined sampling period, and the reference disturbance load torque. Tables TA, TB, TC, TD, TE for storing the average value, the upper limit value of the allowable range obtained from the average value, the lower limit value, and the deviation between the estimated disturbance load torque value and the average value are provided, and the servo CPU 22 Based on the disturbance estimation observer program for estimating the disturbance torque applied to the servo motor 10 in the ROM 17 connected to the speed loop and the estimated disturbance load torque obtained by the processing of the disturbance estimation observer, the valve Processing program to detect abnormal loads in the gate (valve pin) stroke section In that it is stored, it is different from the conventional control system.
  Next, an abnormal load detection process performed by the valve gate control apparatus constituted by the control apparatus 1 will be described together with a flowchart of the abnormal load detection process executed by the servo CPU 22 shown in FIGS. First, the conditions for this valve gate operation are set together with the molding conditions.
  FIG. 5 is a diagram showing an abnormal load detection condition setting display screen in the valve gate operation called by operating the manual data input device 29 with LCD. This abnormal load detection condition display screen is called to set whether or not to perform an abnormal load detection control operation applied to the valve gate. FIG. 5 shows an example in which an abnormal load detection control operation applied to the valve gate is executed as “valve gate abnormal load detection control ON”. Further, when “valve gate abnormal load detection control ON” is set, the cycle number T after the start of the automatic molding cycle in which the abnormal load detection control operation is not executed is set. This is because immediately after the start of automatic molding, the frictional force at the valve gate or the like is not stabilized due to temperature changes, etc., and as a result, the estimated disturbance load torque also fluctuates, so the torque when normal valve gate operation is performed In order to wait for the motor to stabilize, the number of cycles is set such that the output torque of the servo motor 10 is stabilized. In the example of FIG. 5, “twice” is set. Further, according to the present invention, an average value of the estimated disturbance load torque estimated by the disturbance estimation observer is set as a reference disturbance load torque, and added to the reference disturbance load torque, and a shift amount ± K that determines an upper limit value and a lower limit value of an allowable range. Is set.
  In the embodiment shown in FIG. 5, both the upper limit value and the lower limit value are set to ± K as the same amount of shift, but the shift amounts for determining the upper limit value and the lower limit value may be different values. The upper limit value may be an appropriate value within a range that does not damage the mold. Further, the lower limit value is for detecting a resin filling failure or the like, and an optimal shift amount may be set for this detection. Initially, an appropriate shift amount is set.
  As will be described later, when fully automatic molding is performed, the average (waveform) of the estimated disturbance load torque during the valve gate operation is obtained as the reference disturbance load torque, and this average is displayed as a graph as shown in FIG. Based on this average waveform, the maximum allowable range that does not damage the mold is reset as the upper limit shift amount + K, and the lower limit is smaller than the average as the reference disturbance load torque, and there is no molded product. The shift amount −K is set so as to be slightly larger than the valve gate operation.
  Therefore, when the fully automatic molding cycle is started, the servo CPU 22 starts the processing shown in the flowcharts in FIGS. In the initial setting when the automatic molding cycle is commanded, the servo CPU 22 sets a shot counter SC that counts the number of injections to be described later to “1”, and the estimated disturbance load torque in the sampling period in the stroke section of the valve gate operation. The pointer a indicating the storage position of the table TA provided in the data storage RAM 24 for storing the data DA is set to “0”, and the flag F is set to “0”. Further, all the stored data in the tables TA, TB, TC, TD, and TE for storing the estimated disturbance load torque and the like are cleared.
  First, the servo CPU 22 determines whether or not the shot counter SC has exceeded the set cycle number T at which the valve gate abnormal load detection control is not executed (step S1), and if not, the valve gate abnormal load detection control process ends. The shot counter SC is incremented by “1” every time one molding cycle is completed, and is incremented in a processing cycle other than the valve gate abnormal load detection control processing.
  Thereafter, the process waits until the shot counter SC exceeds the set cycle number T. After the set cycle number T is exceeded and the valve gate operation is considered to be stable, the process proceeds from step S1 to step S2 to start the valve gate operation. Judge. This determination is made based on the position of the movable mold as in the conventional case.
  When the start of the valve gate operation is detected, the sampling index n is set to “0” (step S3), the estimation is incorporated by the velocity estimation loop and is estimated by the disturbance estimation observer processing executed together with the velocity loop processing. Disturbance load torque Y (n) is read (step S4). Note that the processing of the disturbance estimation observer is already well known in, for example, Japanese Patent Laid-Open No. 10-119107, and therefore specific processing is omitted.
  Next, it is determined whether the flag F is “1” (step S5). If it is not “1”, the process proceeds to step S8. This flag F is set to “1” when all the data for obtaining the average value as the reference disturbance load torque is obtained as will be described later. Initially, the flag F is all for obtaining the average of the set number of valve gate operations. Since no data is obtained, it is “0”, and the process proceeds to step S8. In step S8, the obtained estimated disturbance load torque Y (n) is stored in the table TA as data DA (a, n). That is, based on the index a indicating the number of valve gate operations (molding cycles) and the index n indicating the number of samplings in the valve gate operation, the estimated disturbance load obtained at the address corresponding to the indexes a and n of the table TA. Torque Y (n) is stored as data DA (a, n).
  Then, it is determined whether the stroke end is a valve gate (valve pin) (step S9). If it is not the stroke end, the index n is incremented by "1" (step S10), and the process returns to step S4. Whether or not the valve gate (valve pin) stroke end is determined by the position of the servo motor 10 detected by the position / speed detector 11 attached to the servo motor that drives the valve gate and stored in the current position storage register. to decide. The valve gate mechanism moves the valve gate (valve pin) linearly by changing the rotation of the servo motor into a linear motion by a mechanism that converts the rotational motion of a ball screw or the like into a linear motion, etc. It has a one-to-one relationship with the position of the gate (valve pin), and if the rotational position of the servo motor is known, the position of the valve gate (valve pin) can be known.
  Thereafter, the processing of steps S4, S5, S8, S9, and S10 is repeatedly executed every predetermined sampling period (every speed loop processing period), and when the valve gate (valve pin) stroke end is reached, the process proceeds from step S9 to step S11. The value of the index n is stored in the register as the total sampling number j of the stroke of the valve gate operation.
  Thus, the estimated disturbance load torque Y (n) during the valve gate operation obtained by the disturbance estimation observer is stored in the table TA as data DA (a, n). Initially, since a = 0, data DA (0,0) to DA (0, j) is stored in the table TA shown in FIG.
  Next, the index n is cleared again to “0” (step S12), the average value DB (n) of the estimated disturbance load torque as the reference disturbance load torque, the upper limit value DC (n) of the allowable range, and the lower limit value DD (n ) To obtain processing steps S13, S14, and S15. That is, the estimated disturbance value data for each nth sampling of the valve gate operation (molding cycle) 0 to i stored in the table TA is added and divided by the number (i + 1) of the valve gate operation (molding cycle). The average value DB (n) is obtained and stored in the table TB as shown in FIG. 4 (step S13). Further, the set shift amount + K is added to the average value DB (n) to obtain the upper limit value DC (n) of the allowable range and stored in the table TC as shown in FIG. 4 (step S14).
  Further, the set shift amount −K is added to the average value DB (n) to obtain the lower limit value DD (n) of the allowable range, and stored in the table TD as shown in FIG. 4 (step S15). Until the index n reaches the total sampling number j (step S16), the index n is incremented by “1” (step S17), the averaging process (step S13), and the upper limit value and the lower limit value of the allowable range are obtained. (Steps S14 and S15) are performed. At first, since all data is not stored in the table TA, the average value DB (n), the upper limit value DC (n), and the lower limit value DD (n) obtained in steps S13, S14, and S15 are Although accurate data cannot be obtained, this is until data of the total number (i + 1) times of valve gate operation (molding cycle) in which data is embedded in the table TA is obtained, and thereafter accurate data is obtained.
  When the index n reaches the total number j of sampling, the process proceeds from step S16 to step S18, the index a is incremented by “1”, and the index a is the last corresponding to the number of valve gate operations (molding cycles) stored in the table TA. It is determined whether the value of address i has been exceeded (step S19). That is, it is determined whether or not the estimated disturbance load torque data is written in the final address i of the table TA by the valve gate operation. If the value of the index a does not exceed the value of the final address i, the abnormality detection process in the valve gate operation ends.
Hereinafter, every time the molding cycle is started, steps S1 to S3 and steps S4, S5, S8, S9 and S10 are repeated, steps S11, S12 and S13 to S17 are repeated, and steps S18 and S19 are repeated. When the index a is “i”, the estimated disturbance load torque Y (n) is stored in the column of the address i of the table TA in step S8 at the time point at the data DA (i, 0) to DA (i , J). Further, since all the data corresponding to the number (i + 1) of valve gate operations (molding cycles) stored in the table TA are stored in the table TA, the average value DB (n) obtained by the processing in steps S13 to S16, The upper limit value DC (n) and the lower limit value DD (n) of the allowable range are accurate. That is, the average value DB (n) is obtained as follows by the process of step S13.
DB (0) = {DA (0,0) + DA (1,0) +... + DA (i, 0)} / (i + 1)
DB (1) = {DA (0,1) + DA (1,1) +... + DA (i, 1)} / (i + 1)

DB (n) = {DA (0, n) + DA (1, n) +... + DA (i, n)} / (i + 1)

DB (j) = {DA (0, j) + DA (1, j) +... + DA (i, j)} / (i + 1)
  Further, the upper limit value and the lower limit value of the allowable range in steps S14 and S15 are obtained by adding the shift amounts + K and -K to the obtained average values DB (0) to DB (j). In step S18, the index a is incremented, and when the value of the index a exceeds the value i, the process proceeds from step S19 to step S20, the flag F is set to “1”, and the index a is cleared to “0”. (Step S20). That is, when the data is stored up to the last address i for storing the data of the valve gate operation process of the table TA, it returns to the beginning at the valve gate operation of the next molding cycle, and stores the data again from the address “0”. The index a is cleared to “0”. As a result, the table TA always stores the data of the valve gate operations of (i + 1) latest molding cycles before (past) the valve gate operations of the current molding cycle.
  Since the flag F is set to “1” from the valve gate operation process of the next molding cycle, the process proceeds from step S5 to step S6, and the estimated disturbance load torque Y (n) obtained by the disturbance estimation observer. Further, the average value DB (n) stored in the table TB is subtracted to obtain the deviation DE (n) between the obtained estimated disturbance load torque Y (n) and the average value DB (n), as shown in FIG. Store in TE. Then, the estimated disturbance load torque Y (n) exceeds the upper limit value DC (n) and the lower limit value DD (n) of the allowable range stored in the tables TC and TD, and it is determined whether it is out of the allowable range (step S7). If not, the process proceeds to step S8, and if exceeded, the process proceeds to step S22 to output a load abnormality signal indicating that a load outside the allowable range has been applied to the valve gate and stop the operation of the servo motor 10. An alarm process is performed, and the abnormal load detection process of the valve gate operation is terminated.
  Thus, the average value as the reference disturbance load torque is obtained from the estimated disturbance load torque during the valve gate operation of the newest (i + 1) molding cycles, and the upper limit value and the lower limit value of the allowable range are also the average value. Since it is determined whether it is within the range of the lower limit value (waveform) that is smaller than the average value by the set shift amount -K and the upper limit value (waveform) that is larger by the set value + K than the average value, Even if it fluctuates, the optimum allowable range can be maintained. Even if the mold is replaced, the upper and lower limits of the allowable range, that is, the allowable range for judging abnormal load during valve gate operation is automatically determined by the average value of the estimated disturbance load torque in normal valve gate operation. Therefore, it is not necessary to set the allowable range for judging this abnormal load based on experience and intuition, and the optimum allowable range is always automatically selected. Can be set automatically.
  When the mold is replaced, it is necessary to collect data at least for the molding cycle (i + 1) stored in the table TA while monitoring whether there is an error in the valve gate (valve pin) setting. There is. Once the estimated disturbance load torque data DA (0,0) to DA (i, j) of normal valve gate operation is obtained, as shown in FIG. 2, the estimated disturbance load torque is obtained. When Y (n) exceeds the upper limit value DC (n) and the lower limit value DD (n) of the allowable range, the estimated disturbance load torque Y (n) is not stored in the table TA. That is, since only the estimated disturbance load torque Y (n) only during normal valve gate operation is stored in the table TA, the average is obtained from the data stored in this table TA, and the upper limit value and lower limit value of the allowable range are obtained. Since it is required, an accurate tolerance is always required.
  Further, by operating a function key (soft key) etc. provided on the manual data input device 29 with LCD, the waveform of the latest estimated disturbance load torque stored in the table TA during the valve gate operation, the table TB , TC, TD, TE can be displayed as a graph on a display screen as a display screen as shown in FIG. In FIG. 5, the most recent estimated disturbance load torque waveform stored in the table TA during the valve gate operation, the reference disturbance load torque average value waveform stored in the table TB, and the tables TC and TD are displayed. The example which displayed the waveform of the upper limit of the stored tolerance | permissible_range and a lower limit is shown.
  In this way, since the waveform of the average value and the upper limit value and lower limit value waveform of the allowable range are displayed, the operator refers to the displayed waveform and the shift amount for determining the upper limit value and lower limit value of the allowable range. + K and -K can be reset to optimum values. The data stored in the table TE may be displayed in a graph instead of or in addition to the waveform of the first latest estimated disturbance load torque during the valve gate operation based on the data stored in the table TA. . Since the data stored in this table TE stores the average value as the reference disturbance load torque and the deviation of the estimated disturbance load torque during the most recent valve gate operation, the waveform of the deviation from the average value is displayed. As a result, the deviation from the average value can be directly observed, and the current state can be grasped more clearly.
  In addition, the present invention does not use a uniform value for the entire stroke of the stroke of the valve gate operation as a reference for determining the abnormal load, but according to the position of the valve gate (valve pin) in the stroke, The upper limit value and the lower limit value of the allowable range serving as a reference for determining the abnormal load are changed, and the abnormal load can be determined more accurately. For example, if one set value is uniformly set for the stroke of the valve gate operation, the set value is too large at a certain position and cannot be detected even though an abnormal load is generated. On the other hand, if the set value is too small, there is a phenomenon that, at a certain position, it is determined that the load is abnormal even though the valve valve operation is normal.
  On the other hand, in the present invention, since an allowable range serving as a reference for determining an abnormal load varies depending on the position of the valve gate (valve pin) in the stroke of the valve gate operation, the constant value is used as a determination reference. An abnormal load can be detected accurately, and the mold can be protected accurately.
  In the above-described embodiment, the most recent estimated disturbance load torque, average value, upper limit value and lower limit value of the allowable range, etc. are displayed as a function of time. Instead of time, it may be displayed as a function of the position of the valve gate (valve pin) and the rotational position of the servo motor that drives the valve gate. That is, the rotational position of the servo motor 10 detected by the position / speed detector 11 attached to the servo motor 10 has a one-to-one correspondence with the position of the valve gate (valve pin) driven by the servo motor 10. Therefore, the average value of the reference disturbance load torque and the upper limit value of the allowable range may be displayed as a function of the rotational position of the servo motor 10 detected by the position / speed detector 11. In this case, the estimated disturbance load torque obtained by the disturbance estimation observer each time the servo motor 10 moves by a predetermined amount is stored, and the average value, the upper limit value of the allowable range, and the lower limit value are stored based on the stored data. Can be obtained and displayed in a graph. In addition, whether or not the load is abnormal may be determined corresponding to this position.
  The estimated disturbance load torque is sampled in the same manner as in this embodiment, is collected every predetermined period, and the rotational position of the servo motor 10 at that time is also stored, and the estimated disturbance load torque is displayed based on this position. . The average value is interpolated to obtain the estimated disturbance load torque at a predetermined position based on the obtained estimated disturbance load torque and the position at that time, or the estimated disturbance load torque at the position closest to the predetermined position is calculated as the predetermined value. As the estimated disturbance load torque at the position, an average value may be obtained from the estimated disturbance load torque at each predetermined position and displayed as a graph.
1 Control Device 2 Valve Pin 10 Servo Motor 11 Position / Speed Detector 12 A / D Converter 13 ROM
14 RAM
15 ROM
16 RAM
17 ROM
18 RAM
19 Servo amplifier 20 Pressure monitor CPU
21 PMCCPU
22 Servo CPU
23 Interface 24 Data storage RAM
25 CNCCPU
26 LCD display circuit 27 ROM
28 RAM
29 LCD / MDI

TA Data table of estimated disturbance load torque value TB Data table of average value of reference disturbance load torque TC Data table of upper limit value of allowable range TD Data table of lower limit value of allowable range TE Estimated disturbance load torque value and reference disturbance load torque Average deviation data table

Claims (7)

  1. A valve gate control device in an injection molding machine that drives and controls a servo motor to drive a valve gate,
    A disturbance estimation observer for estimating a disturbance torque applied to the servo motor;
    A disturbance load torque at the time of valve gate operation of each molding cycle is estimated by the disturbance estimation observer, and the estimated disturbance load torque with respect to the latest one or a plurality of valve gate operation times or valve gate positions before the molding cycle. Means for storing
    Means for obtaining a reference disturbance load torque from the stored estimated disturbance load torque;
    Means for obtaining an allowable upper limit value from the reference disturbance load torque;
    A valve gate control device for an injection molding machine, comprising: a determination unit that outputs an abnormality signal when an estimated disturbance load torque during a current valve gate operation is greater than the allowable upper limit value.
  2.   The valve gate control device for an injection molding machine according to claim 1, wherein when an abnormal signal is output, the estimated disturbance load torque during the valve gate operation is not included in the reference disturbance load torque.
  3. Furthermore, setting means for arbitrarily setting the allowable upper limit value on the screen;
    The screen shows the estimated disturbance load torque, reference disturbance load torque, upper limit value or reference disturbance load torque during the current valve gate operation and the deviation between the estimated disturbance load torque during the current valve gate operation and the time or valve gate position. 3. The valve gate control device for an injection molding machine according to claim 1, further comprising display means for displaying a graph.
  4.   The means for obtaining the permissible upper limit value also obtains a permissible lower limit value from the reference disturbance load torque, and the determination means outputs an abnormal signal even when the estimated disturbance load torque during the current valve gate operation is smaller than the permissible lower limit value. The valve gate control device for an injection molding machine according to any one of claims 1 to 3, which outputs the valve gate control device.
  5.   The valve gate control device for an injection molding machine according to any one of claims 1 to 4, wherein the estimated disturbance load torque of a predetermined cycle after the start of full automatic molding is not included in the data for obtaining the reference disturbance load torque.
  6.   6. The valve gate control device for an injection molding machine according to claim 5, wherein a predetermined number of cycles after the start of fully automatic molding that is not included in the data for obtaining the reference disturbance load torque can be set on the screen of the display means.
  7.   The valve gate of the injection molding machine according to any one of claims 1 to 6, wherein the reference disturbance load torque is an average value of estimated disturbance load torques during valve gate operation in a plurality of molding cycles before the molding cycle. Control device.
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EP3546176A1 (en) 2018-03-30 2019-10-02 Sumitomo Heavy Industries, Ltd. Injection molding machine
JP2021043714A (en) * 2019-09-11 2021-03-18 富士電機株式会社 Servo amplifier and servo system

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JP2001030326A (en) * 1999-07-19 2001-02-06 Fanuc Ltd Mold protecting device for injection molding machine
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JPH10119107A (en) * 1996-10-22 1998-05-12 Fanuc Ltd Device for detecting collision of movable member in motor-driven injection molding machine
JP2001030326A (en) * 1999-07-19 2001-02-06 Fanuc Ltd Mold protecting device for injection molding machine
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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3546176A1 (en) 2018-03-30 2019-10-02 Sumitomo Heavy Industries, Ltd. Injection molding machine
CN110315694A (en) * 2018-03-30 2019-10-11 住友重机械工业株式会社 Injection (mo(u)lding) machine
JP2021043714A (en) * 2019-09-11 2021-03-18 富士電機株式会社 Servo amplifier and servo system

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