JP5800750B2 - Method for detecting deterioration of movable part of injection molding machine and control device for injection molding machine having function of detecting deterioration of movable part - Google Patents

Description

  The present invention relates to a technique for performing an inspection of a movable part of an injection molding machine so as not to be a burden on an inspection operator, and notifying when it is determined to be abnormal. The present invention also relates to a control device for an injection molding machine having a function of detecting deterioration of movable parts.

Conventionally, it has been necessary to periodically inspect the movable part of the injection molding machine, and there has been a problem that the inspection work becomes a burden on the operator or the necessary inspection is not performed. In view of such a problem, a technique for inspecting a movable part of an injection molding machine or monitoring a state of the movable part has been proposed.
For example, in Patent Document 1, a frequency characteristic of a machine component in an electric injection molding machine is measured, and a repair notice is issued when a deviation from the initial setting of the resonance frequency of the machine component exceeds a preset value. Techniques for doing so are disclosed. Moreover, in patent document 2, with the drive of the drive part of a molding machine, the 1st variable of a 1st detection part and the 2nd variable of a 2nd detection part are detected, and the said 1st detection part and 1st A technique for determining a transfer characteristic in a transfer path between two detection units and monitoring a state of a molding machine is disclosed.

JP 2007-90477 A JP 2006-272560 A

  However, the techniques disclosed in Patent Documents 1 and 2 described in the background art have the following problems. In the technique disclosed in Patent Document 1, the repair notice is made based on the resonance frequency of the machine component. However, depending on the type and state of the machine component, the resonance does not appear remarkably, and therefore the resonance frequency is accurately detected. There were cases where it was difficult. For example, when the mechanical component is in a normal state, the resonance frequency is higher than the control band, so that the resonance does not appear remarkably. However, when the machine component deteriorates, the resonance frequency enters the control band, so that resonance appears. is there. In addition, the technique disclosed in Patent Document 2 may require a special device or detector for determining transfer characteristics in addition to a detector provided in advance in a general injection molding machine. There was a risk of increasing the cost of the molding machine.

  Therefore, the present invention has been devised to solve the above problems, and does not depend on the presence or absence of resonance of the movable part, and requires a special device for determining the state of the movable part. To provide a method for detecting deterioration of a movable part of an injection molding machine and a control device for an injection molding machine having a function for detecting deterioration of a movable part capable of accurately determining and inspecting the state of the movable part without any trouble. Objective.

The invention according to claim 1 of the present application is the control device for an injection molding machine comprising: a servo motor that drives a movable part of the injection molding machine; and a frequency characteristic measurement unit that measures a closed loop frequency characteristic of the servo motor. A reference gain value storage unit that stores a gain value at a first frequency as a reference gain value in a reference frequency characteristic when the unit is in a normal state, and a closed loop frequency characteristic that includes at least the first frequency of the servo motor at an arbitrary timing A current frequency characteristic measuring unit that measures the current frequency characteristic; a gain deviation value calculating unit that calculates a deviation between a gain value at a first frequency and a reference gain value in the current frequency characteristic; and the calculated gain deviation value And a deterioration determining unit that determines that the movable unit has deteriorated when the absolute value of exceeds a threshold value. That is a control apparatus for an injection molding machine.
According to a second aspect of the present invention, there is provided a control apparatus for an injection molding machine comprising: a servo motor that drives a movable part of an injection molding machine; and a frequency characteristic measuring unit that measures a closed loop frequency characteristic of the servo motor. In a reference frequency characteristic in a normal state, a reference gain value storage unit that stores an average value of gain values from the second frequency to the third frequency as a reference gain value, and at least a second of the servo motor at an arbitrary timing A current frequency characteristic measurement unit that measures a closed loop frequency characteristic including a frequency from a frequency to a third frequency as a current frequency characteristic; and an average of gain values from the second frequency to the third frequency in the current frequency characteristic A gain deviation value calculation unit for calculating a deviation between the value and the reference gain value, and when the absolute value of the calculated gain deviation value exceeds a threshold value A control device for an injection molding machine and having a degradation determiner portion and the movable portion is deteriorated.
According to a third aspect of the present invention, there is provided a control apparatus for an injection molding machine comprising: a servo motor that drives a movable part of an injection molding machine; and a frequency characteristic measuring unit that measures a closed loop frequency characteristic of the servo motor. A reference frequency characteristic storage unit that stores a reference frequency characteristic in a normal state as an array of gain values for each predetermined frequency, and a current frequency characteristic measurement that measures the closed loop frequency characteristic of the servo motor as a current frequency characteristic at an arbitrary timing And the frequency at which the gain value changes from increase to decrease from the low frequency side to the high frequency side in the current frequency characteristic is set as a fourth frequency, and the frequency at which the gain value changes from decrease to increase from the fourth frequency to the high frequency side. A frequency range calculation unit for a fifth frequency, and a gay from the fourth frequency to the fifth frequency in the current frequency characteristic; A gain deviation value calculation unit for calculating a deviation between an average value of the values and an average value of gain values from the fourth frequency to the fifth frequency in the reference frequency characteristic, and an absolute value of the calculated gain deviation value is a threshold value A control unit for an injection molding machine, comprising: a deterioration determination unit that determines that the movable part has deteriorated when the value exceeds the upper limit.

The invention according to claim 4 is the control device for an injection molding machine according to claim 1, wherein the first frequency is a zero cross frequency in the closed loop frequency characteristic.
In the invention according to claim 5, the second frequency is a frequency at which a gain value changes from increasing to decreasing from the low frequency side to the high frequency side in the closed loop frequency characteristic, and the third frequency is the frequency in the closed loop frequency characteristic. 3. The control apparatus for an injection molding machine according to claim 2, wherein the gain value is a frequency at which the gain value changes from decreasing to increasing from the second frequency to the high frequency side.
The invention according to claim 6 is characterized in that the movable portion is a timing belt, and the deterioration determining portion is a tension belt tension lowering determining portion. It is a control device of a molding machine.

The invention according to claim 7 is a deterioration determination method of a movable part that determines deterioration of the movable part based on a closed loop frequency characteristic of a servo motor that drives the movable part of an injection molding machine, and the movable part is normal. In the reference frequency characteristic in the state, the gain value at the first frequency is stored as the reference gain value, and the closed loop frequency characteristic including at least the first frequency of the servo motor is measured as the current frequency characteristic at an arbitrary timing, and the current An injection molding machine that calculates a deviation between a gain value at a first frequency and a reference gain value in the frequency characteristic of the first and determines that the movable part has deteriorated when the absolute value of the calculated gain deviation value exceeds a threshold value This is a method for determining deterioration of a movable part.
The invention according to claim 8 is a method for determining deterioration of a movable part based on a closed loop frequency characteristic of a servo motor that drives the movable part of an injection molding machine, wherein the movable part is normal. In the reference frequency characteristics in the state, an average value of gain values from the second frequency to the third frequency is stored as a reference gain value, and at least from the second frequency to the third frequency of the servo motor at an arbitrary timing A closed loop frequency characteristic including a frequency is measured as a current frequency characteristic, and a deviation between an average value of gain values from a second frequency to a third frequency in the current frequency characteristic and a reference gain value is calculated, and the calculation is performed. When the absolute value of the gain deviation value exceeds a threshold value, the deterioration determination method for the movable part of the injection molding machine determines that the movable part has deteriorated.
The invention according to claim 9 is a deterioration determination method for a movable part that determines deterioration of the movable part based on a closed-loop frequency characteristic of a servo motor that drives the movable part of an injection molding machine, wherein the movable part is normal. The reference frequency characteristic in the state is stored as an array of gain values for each predetermined frequency, the closed-loop frequency characteristic of the servo motor is measured as the current frequency characteristic at an arbitrary timing, and the high frequency is measured from the low frequency side of the current frequency characteristic. The frequency at which the gain value shifts from increase to decrease toward the fourth side is the fourth frequency, the frequency at which the gain value shifts from decrease to increase from the fourth frequency to the high frequency side is defined as the fifth frequency, and the fourth frequency in the current frequency characteristic Between the average value of the gain values from the fourth frequency to the fifth frequency and the average value of the gain values from the fourth frequency to the fifth frequency in the reference frequency characteristic. It calculates, when the absolute value of the calculated gain deviation value exceeds a threshold value, a deterioration determination process of the movable portion of determining an injection molding machine and the movable portion is deteriorated.
The invention according to claim 10 is the injection according to any one of claims 7 to 9, wherein the movable part is a timing belt, and the deterioration determination method is a tension belt tension decrease determination method. This is a method for determining deterioration of a movable part of a molding machine.

  According to the present invention, the state of the movable part is accurately determined and inspected without being affected by the presence or absence of resonance of the movable part and without requiring a special device for determining the state of the movable part. It is possible to provide a method for determining deterioration of a movable part of an injection molding machine and a control device for an injection molding machine having a function of detecting deterioration of the movable part.

It is a figure explaining an injection molding machine main body and a control device. It is explanatory drawing of a frequency characteristic. 3 is a flowchart illustrating the first embodiment. 10 is a flowchart for explaining the second embodiment. 10 is a flowchart for explaining the third embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a principal block diagram of an embodiment of an injection molding machine having a function of detecting deterioration of a movable part according to the present invention. A mold clamping unit including a fixed platen 1, a rear platen 2, a movable platen 3, a toggle link mechanism 6 and the like on a machine base 15, and an injection unit including an injection cylinder 20, an injection screw 22, an injection servo motor 25, and the like. The main body of the injection molding machine is configured.

  First, the mold clamping unit will be described. The stationary platen 1 and the rear platen 2 are connected by a plurality of tie bars 4. A movable platen 3 is movably disposed along the tie bar 4 between the fixed platen 1 and the rear platen 2. In addition, the fixed mold 5 a of the mold 5 is attached to the fixed platen 1, and the movable mold 5 b is attached to the movable platen 3.

  A toggle link mechanism 6 is disposed between the rear platen 2 and the movable platen 3, and a nut provided on a cross head 6 a of the toggle link mechanism 6 is attached to the rear platen 2 so as to be rotatable and immovable in the axial direction. Are screwed together. A belt (timing belt) 9 is placed between a pulley 10 provided on the ball screw 7 and a pulley 11 provided on the output shaft of the mold clamping servomotor 8.

  By driving the mold clamping servo motor 8, the ball screw 7 is driven through the power transmission means of the pulley 11, the belt 9, and the pulley 10, and the crosshead 6 a of the toggle link mechanism 6 moves forward and backward (rightward in FIG. 1, The toggle link mechanism 6 is driven to move the movable platen 3 forward and backward in the direction of the fixed platen 1 to close and clamp the molds 5a and 5b and open the mold.

  A position / speed detector 12 such as a pulse coder for detecting the rotational position / speed of the mold clamping servomotor 8 is attached to the mold clamping servomotor 8. Based on the position feedback signal from the position / velocity detector 12, the position of the cross head 6a and the position of the movable platen 3 (movable side mold 5b) are detected.

  Reference numeral 13 denotes an ejector device, and the ejector device 13 is a device for projecting a molded product from a mold (movable side mold 5b) provided on the movable platen 3. The ejector device 13 transmits the rotational force of the servo motor for ejector 13a to an eject pin (not shown) via a power transmission means 13c comprising a pulley and a belt (timing belt) and a ball screw / nut mechanism 13d. The molded product is protruded from the mold (movable side mold 5b) by protruding into the mold (movable side mold 5b). Reference numeral 13b denotes a position / speed detector attached to the ejector servomotor 13a, which detects the position and speed of the eject pin by detecting the rotational position / speed of the ejector servomotor 13a. is there.

  Reference numeral 14 denotes a mold clamping force adjustment mechanism provided on the rear platen 2, which drives a mold clamping force adjustment motor 14 a and rotates a nut (not shown) that is screwed into a screw provided on the tie bar 4 via the transmission mechanism. The mold clamping force is adjusted by changing the position of the rear platen 2 with respect to the tie bar 4 (that is, changing the position of the rear platen 1 with respect to the fixed platen 1 on the machine base 15). The above-described mold clamping device, ejector mechanism, and the like are known ones conventionally provided in injection molding machines.

  Next, the injection unit will be described. In order to supply the resin material into the injection cylinder 20, a hopper 27 is provided on the upper part of the injection cylinder 20. A nozzle portion 21 is attached to the tip of the injection cylinder 20, and an injection screw 22 is inserted into the injection cylinder 20. The injection unit is provided with a pressure sensor (not shown) such as a load cell that detects the pressure of the molten resin in the injection cylinder 20.

  The injection screw 22 is rotated in the forward and reverse directions by a screw rotating servo motor 23 via a transmission means 24 constituted by a pulley, a timing belt, and the like. The injection screw 22 is driven by a servo motor 25 for injection through a transmission means 26 including a mechanism for converting a rotational motion such as a pulley, belt, ball screw / nut mechanism, etc. into a linear motion. It moves in the axial direction of the injection cylinder 20. A screw coder (not shown) is attached to the screw rotation servomotor 23 to detect the rotation position and rotation speed of the injection screw 22. A pulse coder (not shown) is attached to the injection servo motor 25, and detects the position and speed of the injection screw 22 in the axial direction.

  Next, the control device for the injection molding machine will be described. Reference numeral 30 is a control device for controlling the injection molding machine. The control device 30 includes a processor (CPU) 35, a memory 34 including a RAM 34a, a ROM 34b, and the like, a bus 33, and a display device interface 36. These elements are connected by the bus 33. The ROM 34b stores software for controlling the injection molding machine as a whole, such as software for controlling the operation of the movable platen 3 and ejection control software for controlling the ejector device 13. In the embodiment of the present invention, the ROM 34b of the memory 34 stores various software for determining the deterioration state of the movable part of the injection molding machine according to the present invention.

  An LCD (Liquid Crystal Display) 37 is connected to the display device interface 36. The servo interface 32 is connected to a servo amplifier 31 that drives each movable part of the injection molding machine and controls the position and speed of the servo motor. A position / speed detector attached to a servomotor that drives each movable part is connected to the servo amplifier 31. The display device interface 36 is connected to input means by manual input (not shown).

  In the injection molding machine, a plurality of servo motors are used to drive a plurality of movable parts, but FIG. 1 shows only the servo amplifiers 31 for the mold clamping servo motor 8 and the ejector servo motor 13a. ing. The servo amplifier 31 is connected to the position / speed detectors 12 and 13b of the servo motors 8 and 13a, and the position / speed detection signals are fed back to the servo amplifiers 31. The illustrations of the servo amplifiers of the screw rotation servomotor 23 and the injection servomotor 25 and the position / speed detectors attached to the servomotors 23 and 25 are omitted.

  The processor (CPU) 35 executes a program stored in advance in the ROM 34 b of the memory 34 based on molding conditions and the like, and sends a movement command to each movable part of the injection molding machine via the servo interface 32. Output to. Each servo amplifier 31 performs position / speed feedback control based on this movement command, position from each position / speed detector (12, 13b), speed feedback signal, and current from a current detector (not shown). Based on the feedback signal, current feedback control is performed to drive and control each servo motor (8, 13a). Each servo amplifier 31 includes a processor and a memory as in the prior art, and executes processing such as position and speed feedback control by software processing. Note that PMC is a programmable machine controller and is a device for controlling the injection molding machine main body by sequence control.

Hereinafter, each embodiment of the present invention that realizes the function of detecting the deterioration of the movable part in the above-described injection molding machine will be described. The first to fifth frequencies and the types of movable parts will be described after the description of each embodiment.
<Embodiment 1>
When the movable part of the injection molding machine is properly adjusted, the closed loop frequency characteristic of the servo motor that drives the movable part is measured, and the gain value at the first frequency of the frequency characteristic is used as the reference gain value in the appropriate state. Store in advance. Then, after the machine is operated, frequency characteristics including at least the first frequency are measured at an arbitrary timing such as during maintenance, and a deviation between the gain value and the reference gain value is obtained. When the characteristic of the movable part changes from a state in which it is properly adjusted, the absolute value of the deviation increases. Therefore, the absolute value of the deviation is compared with a predetermined value, and when the absolute value of the deviation becomes larger than the predetermined value, it is determined that the movable part has deteriorated.

<Embodiment 2>
In the first embodiment, the state of the movable part is determined based on the gain value at the first frequency. However, the first frequency appropriate for determining the state of the movable part varies depending on individual differences of the members of the movable part. There is a case. In such a case, an average value of gain values from the second frequency to the third frequency may be obtained, and the state of the movable part may be determined based on the average value of the gain values. For example, in a state where the movable part of the injection molding machine is properly adjusted, the closed loop frequency characteristic of the servo motor that drives the movable part is measured, and the gain value from the second frequency to the third frequency of the frequency characteristic is measured. Is previously stored as a reference gain value.
And after the operation of the injection molding machine, the frequency characteristic including at least the frequency from the second frequency to the third frequency is measured, the average value of the gain values from the second frequency to the third frequency is calculated, The deviation between the average gain value and the reference gain value is obtained. The absolute value of the deviation is compared with a predetermined value, and if the absolute value of the deviation becomes larger than the predetermined value, it is determined that the movable part has deteriorated.

<Embodiment 3>
In the second embodiment, it is desirable that there is no resonance in the frequency range in which the average value of gain values is calculated. However, although there is no resonance in a normal state depending on the type of the movable part, there is a case where resonance appears due to deterioration, or there is resonance originally in a normal state, and the resonance frequency may fluctuate due to deterioration. In this case, since the resonance frequency fluctuates between a normal state and a deteriorated state, there is a problem that it is difficult to determine a frequency range for calculating an average value of gain values by avoiding the resonance frequency in advance. Therefore, in a state where the movable part is properly adjusted, the reference frequency characteristic is stored as an array of gain values for each predetermined frequency.
In the frequency characteristics obtained after the operation of the injection molding machine, the frequency value at which the gain value starts from increasing to decreasing from the low frequency side to the high frequency side is set as the fourth frequency, and the gain value decreases from the fourth frequency to the high frequency side. The frequency value that starts to increase is calculated as the fifth frequency.
Then, an average value of gain values from the fourth frequency to the fifth frequency of the reference frequency characteristic is set as a reference gain value, and a deviation from the gain values from the fourth frequency to the fifth frequency of the current frequency characteristic is calculated. Determine the deterioration of the movable part. Since the maximum value of the gain occurs at the resonance point of the frequency characteristic, the fifth frequency determined in this way is on the lower frequency side than the resonance point. Therefore, in this case, even when the resonance frequency changes due to the deterioration of the movable part, the fourth to fifth frequency ranges can be made a range that avoids the resonance point of the movable part. It is possible to accurately determine the deterioration of the movable part without being performed.

<About the types of moving parts>
The kind of movable part is demonstrated. The movable parts of the injection molding machine are an injection shaft, a screw rotation shaft, an ejector shaft, a mold opening / closing shaft, and the like, such as the injection screw 22, the ejector device 13, and the movable platen 3. A motor is used as means for driving the movable part. A timing belt, a coupling, a ball screw, a toggle link, or the like is used as a power transmission device for a movable part that transmits power from a drive unit such as a motor to the movable part. In the embodiment of the present invention, it is possible to detect deterioration of the power transmission device of these movable parts. Further, when the movable part is an injection shaft, it is possible to detect deterioration of the pressure detection device in addition to the power transmission device. In particular, in the case of a timing belt, the tension of the timing belt decreases due to deterioration over time, and therefore, the decrease in tension is detected as deterioration of the movable part.

<About frequency characteristics>
Next, frequency characteristics will be described.
As frequency characteristics of servo motors, devices and methods for measuring frequency characteristics such as speed loop, position loop, and current loop are well known. In addition, each frequency characteristic can be measured by sweeping the frequency while superimposing a sinusoidal disturbance signal on each loop command value and obtaining a response to the superimposed disturbance, A method of superposing white noise and obtaining a response to the superimposed white noise is well known.

  In the embodiment of the present invention, characteristics of a plurality of frequencies may be measured by sweeping the frequency of a disturbance signal or superposing white noise including a large number of frequencies, or only a single frequency may be included. A characteristic of a single frequency may be measured by superimposing a disturbance signal.

  In the embodiment of the present invention, the closed loop frequency characteristics such as the velocity loop, the position loop, and the current loop are measured to detect the deterioration of the movable part. When the movable part is an injection shaft, the closed loop frequency characteristic of the pressure loop can be measured to detect the deterioration of the pressure detection device.

  FIG. 2 is an explanatory diagram of frequency characteristics. By measuring the frequency characteristic of a certain movable part, the relationship between the frequency and the gain value is obtained as shown in FIG. 2 as the frequency characteristic. In the waveform example shown in FIG. 2, the gain value waveform has a frequency at which the gain value changes from increasing to decreasing, a zero cross frequency, and a frequency at which the gain value changes from decreasing to increasing.

<About the first to fifth frequencies>
Next, the first to fifth frequencies used in the embodiment will be described.
(About the first frequency)
In determining the first frequency, a frequency at which the gain value greatly changes due to deterioration of the movable part may be obtained in advance by experiments, and the frequency may be set as the first frequency. Alternatively, the first frequency may be a zero cross frequency in a reference frequency characteristic (see FIG. 2). It is well known that the zero cross frequency is a frequency whose gain value crosses 0 dB in the frequency characteristics.

(About 2nd frequency and 3rd frequency)
In determining the second frequency and the third frequency, a frequency range in which the gain value greatly changes due to deterioration of the movable part is obtained in advance by experiment, and the lower limit of the frequency range is set as the second frequency, and the frequency The upper limit of the range may be the third frequency. The second frequency is a frequency at which the gain value starts from increasing to decreasing from the low frequency side to the high frequency side in the reference closed loop frequency characteristic, and the third frequency is from the second frequency in the reference closed loop frequency characteristic. The gain value may be a frequency at which the gain value is increased from decreasing to increasing toward the high frequency side.

(About 4th frequency and 5th frequency)
The frequency at which the gain value changes from increase to decrease from the low frequency side to the high frequency side of the current frequency characteristic is the fourth frequency, and the frequency at which the gain value changes from decrease to increase from the fourth frequency to the high frequency side is the fifth frequency. And At this time, in the case where there is no resonance in the current frequency characteristic, there is no point in time when the gain value changes from decreasing to increasing from the fourth frequency to the high frequency side, and it may be monotonously decreasing. In such a case, for example, the frequency at which the phase delay of the current frequency characteristic is 180 degrees may be set as the fifth frequency.

  The second frequency and the third frequency are determined in advance in a state where the movable part of the injection molding machine is appropriately adjusted. On the other hand, the fourth frequency and the fifth frequency are determined when the current frequency characteristic is measured.

<Current frequency characteristics measurement timing>
Next, the current frequency characteristic measurement timing will be described.
The current frequency characteristic measurement unit measures the frequency characteristic of the movable part at an arbitrary timing. For example, the operation time or the number of operation shots of the injection molding machine may be counted, and the frequency characteristics may be measured when the operation time or the number of operation shots reaches a predetermined maintenance time or the number of maintenance shots. .
Alternatively, a frequency characteristic measurement command input unit may be provided, and measurement of the frequency characteristic may be executed when a command is input from the frequency characteristic measurement command input unit. At this time, the frequency characteristic measurement command input unit can not only command the measurement of the frequency characteristic by the operator's operation, but also, for example, a device outside the injection molding machine can be configured to issue a command signal, It is also possible to input a frequency characteristic measurement command signal issued by the apparatus to the frequency characteristic measurement command input unit.

<Calculation of gain deviation value>
In the present invention, the gain value of the frequency characteristic is treated as a logarithm such as decibel (dB). For example, when the reference gain value is 3 dB and the gain value after operation of the machine is −2 dB, the gain deviation value is −5 dB. This means that the gain value after operation of the machine is 10 ^ (-0.5) times the reference gain value.

<About the notification method of the deterioration of the moving part>
A method for notifying the deterioration of the movable part will be described. When it is determined that the movable part has deteriorated, a message may be displayed on the screen or a warning lamp may be turned on to notify the operator. Further, the molding machine may be put in an alarm state until the maintenance of the movable part is performed, or the molded product may be determined as defective by the quality determination.

  Hereinafter, processing executed in each embodiment will be described with reference to flowcharts. Note that as described in <Current Frequency Characteristic Measurement Timing>, the number of shots may be used instead of the operation time in the processing shown in each flowchart.

FIG. 3 is a flowchart for explaining the first embodiment.
[Step SA01] The frequency characteristic of the movable part is measured in the reference state.
[Step SA02] The gain value at the first frequency is stored as a reference gain value. [Step SA03] It is determined whether or not the operation time has exceeded the maintenance time. If it has exceeded (YES), the process proceeds to Step SA05, and if not (NO), the process proceeds to Step SA04.
[Step SA04] The operating time of the machine is integrated, and the process returns to Step SA03.
[Step SA05] The frequency characteristic of the movable part is measured.
[Step SA06] The deviation between the gain value at the first frequency and the reference gain value is obtained.
[Step SA07] It is determined whether or not the absolute value of the gain deviation value exceeds the threshold value. If the threshold value is exceeded (YES), the process proceeds to Step SA08. If not (NO), the process proceeds to Step SA09. To do.
[Step SA08] It is determined that the movable part has deteriorated, and the process ends.
[Step SA09] It is determined that the movable part is normal, and the process ends.

FIG. 4 is a flowchart for explaining the second embodiment.
[Step SB01] The frequency characteristic of the movable part is measured in the reference state.
[Step SB02] An average value of gain values from the second frequency to the third frequency is stored as a reference gain value.
[Step SB03] It is determined whether or not the operating time exceeds the maintenance time. If it exceeds (YES), the process proceeds to Step SB05, and if not (NO), the process proceeds to Step SB04.
[Step SB04] The machine operating time is accumulated.
[Step SB05] The frequency characteristic of the movable part is measured.
[Step SB06] A deviation between the average value of the gain values from the second frequency to the third frequency and the reference gain value is obtained.
[Step SB07] It is determined whether or not the absolute value of the gain deviation value exceeds the threshold value. If it exceeds (YES), the process proceeds to Step SB08. If not (NO), the process proceeds to Step SB09.
[Step SB08] It is determined that the movable part has deteriorated, and the process ends.
[Step SB09] It is determined that the movable part is normal, and the process ends.

FIG. 5 is a flowchart for explaining the third embodiment.
[Step SC01] The frequency characteristic of the movable part is measured in the reference state.
[Step SC02] The frequency characteristics are stored as an array of gain values.
[Step SC03] It is determined whether or not the operation time has exceeded the maintenance time. If it has exceeded (YES), the process proceeds to Step SC05, and if not (NO), the process proceeds to Step SC04.
[Step SC04] The operating time of the machine is accumulated, and the process returns to Step SC03.
[Step SC05] The frequency characteristic of the movable part is measured.
[Step SC06] The fourth frequency is extracted as the frequency at which the gain value of the frequency characteristic turns from increasing to decreasing.
[Step SC07] The fifth frequency is extracted as the frequency at which the gain value of the frequency characteristic turns from decreasing to increasing.
[Step SC08] The average value of the gain values from the fourth frequency to the fifth frequency is obtained for the reference frequency characteristic and the current frequency characteristic.
[Step SC09] It is determined whether or not the absolute value of the gain deviation value exceeds the threshold value. If it exceeds (YES), the process proceeds to Step SC10. If not (NO), the process proceeds to Step SC11.
[Step SC10] It is determined that the movable part has deteriorated, and the process ends.
[Step SC11] It is determined that the movable part is normal, and the process ends.

The process for detecting the deterioration of the movable part in the embodiment of the present invention described above may be performed by the control device of the injection molding machine, the management device of the injection molding machine, or by an operator or a service person. You may do it.
For example, an operator, a serviceman, or the like may perform the part that determines that the movable part has deteriorated when the absolute value of the gain deviation value exceeds the threshold value. Also, a management device that manages the injection molding machine is provided, the injection molding machine is connected to the management device, the reference gain value of the injection molding machine is stored in the management device, and the injection molding machine measures the current frequency characteristics. Alternatively, the management device may acquire the measured current frequency characteristic, and the management device may calculate the deviation between the acquired current frequency characteristic and the reference gain value to determine the deterioration of the movable part.

1 fixed platen 2 rear platen 3 movable platen 4 tie bar 5 die 5a fixed die 5b movable die 6 toggle link mechanism 7 ball screw 8 mold clamping servo motor 9 belt 10 pulley 11 pulley 12 position / speed detector 13 ejector device 13a Ejector Servo Motor 13b Position / Speed Detector 13c Power Transmission Means 13d Ball Screw / Nut Mechanism 14 Mold Clamping Force Adjustment Mechanism 14a Mold Clamping Force Adjustment Motor 15 Machine Base

DESCRIPTION OF SYMBOLS 20 Injection cylinder 21 Nozzle part 22 Injection screw 23 Servo motor for screw rotation 24 Transmission means 25 Injection servo motor 26 Transmission means 27 Hopper

30 Control Device 31 Servo Amplifier 32 Servo Interface 33 Bus 34 Memory 34a RAM
34b ROM
35 Processor (CPU)
36 Display Device Interface 37 LCD (Liquid Crystal Display)
38 PMC (Programmable Machine Controller)

Claims (10)

In a control apparatus for an injection molding machine having a servo motor that drives a movable part of an injection molding machine and a frequency characteristic measurement unit that measures a closed loop frequency characteristic of the servo motor.
A reference gain value storage unit that stores a gain value at a first frequency as a reference gain value in a reference frequency characteristic when the movable unit is in a normal state;
A current frequency characteristic measurement unit that measures a closed loop frequency characteristic including at least the first frequency of the servomotor as a current frequency characteristic at an arbitrary timing;
A gain deviation value calculation unit for calculating a deviation between a gain value at a first frequency and a reference gain value in the current frequency characteristic;
A control apparatus for an injection molding machine, comprising: a deterioration determination unit that determines that the movable part has deteriorated when the absolute value of the calculated gain deviation value exceeds a threshold value. In a control apparatus for an injection molding machine having a servo motor that drives a movable part of an injection molding machine and a frequency characteristic measurement unit that measures a closed loop frequency characteristic of the servo motor.
A reference gain value storage unit that stores, as a reference gain value, an average value of gain values from the second frequency to the third frequency in the reference frequency characteristics when the movable unit is in a normal state;
A current frequency characteristic measuring unit that measures a closed loop frequency characteristic including a frequency from at least a second frequency to a third frequency of the servo motor at an arbitrary timing as a current frequency characteristic;
A gain deviation value calculation unit for calculating a deviation between an average value of gain values from the second frequency to the third frequency in the current frequency characteristic and a reference gain value;
A control apparatus for an injection molding machine, comprising: a deterioration determination unit that determines that the movable part has deteriorated when the absolute value of the calculated gain deviation value exceeds a threshold value. In a control apparatus for an injection molding machine having a servo motor that drives a movable part of an injection molding machine and a frequency characteristic measurement unit that measures a closed loop frequency characteristic of the servo motor.
A reference frequency characteristic storage unit that stores a reference frequency characteristic in a normal state of the movable part as an array of gain values for each predetermined frequency;
A current frequency characteristic measurement unit that measures the closed loop frequency characteristic of the servo motor as a current frequency characteristic at an arbitrary timing;
In the current frequency characteristic, the frequency at which the gain value changes from increase to decrease from the low frequency side to the high frequency side is set as the fourth frequency, and the frequency at which the gain value changes from decrease to increase from the fourth frequency to the high frequency side is set as the fifth frequency. A frequency range calculation unit for frequency; and
A deviation between an average value of gain values from the fourth frequency to the fifth frequency in the current frequency characteristic and an average value of gain values from the fourth frequency to the fifth frequency in the reference frequency characteristic is calculated. A gain deviation value calculation unit;
A control apparatus for an injection molding machine, comprising: a deterioration determination unit that determines that the movable part has deteriorated when the absolute value of the calculated gain deviation value exceeds a threshold value.   The control apparatus for an injection molding machine according to claim 1, wherein the first frequency is a zero cross frequency in the closed loop frequency characteristic.   The second frequency is a frequency at which the gain value changes from increasing to decreasing from the low frequency side to the high frequency side in the closed loop frequency characteristic, and the third frequency is from the second frequency to the high frequency side in the closed loop frequency characteristic. The control apparatus for an injection molding machine according to claim 2, wherein the gain value is a frequency at which the gain value changes from a decrease to an increase.   6. The control apparatus for an injection molding machine according to claim 1, wherein the movable portion is a timing belt, and the deterioration determining portion is a timing belt tension decrease determining portion. A deterioration determination method for a movable part that determines deterioration of the movable part based on a closed loop frequency characteristic of a servo motor that drives the movable part of an injection molding machine,
Storing a gain value at a first frequency as a reference gain value in a reference frequency characteristic in a normal state of the movable part;
Measuring a closed-loop frequency characteristic including at least the first frequency of the servo motor at an arbitrary timing as a current frequency characteristic;
The deviation between the gain value at the first frequency and the reference gain value in the current frequency characteristic is calculated, and when the absolute value of the calculated gain deviation value exceeds a threshold value, it is determined that the movable part has deteriorated A method for determining deterioration of a movable part of a molding machine. A deterioration determination method for a movable part that determines deterioration of the movable part based on a closed loop frequency characteristic of a servo motor that drives the movable part of an injection molding machine,
An average value of gain values from the second frequency to the third frequency is stored as a reference gain value in a reference frequency characteristic in a state where the movable part is normal.
A closed loop frequency characteristic including a frequency from at least a second frequency to a third frequency of the servo motor at an arbitrary timing is measured as a current frequency characteristic;
Calculating a deviation between an average value of gain values from the second frequency to the third frequency in the current frequency characteristic and a reference gain value;
A method for determining deterioration of a movable part of an injection molding machine that determines that the movable part has deteriorated when an absolute value of the calculated gain deviation value exceeds a threshold value. A deterioration determination method for a movable part that determines deterioration of the movable part based on a closed loop frequency characteristic of a servo motor that drives the movable part of an injection molding machine,
Storing the reference frequency characteristics in a normal state of the movable part as an array of gain values for each predetermined frequency;
The closed loop frequency characteristic of the servo motor is measured as the current frequency characteristic at an arbitrary timing, and the frequency at which the gain value changes from increasing to decreasing from the low frequency side to the high frequency side of the current frequency characteristic is set as a fourth frequency.
The frequency at which the gain value starts from decreasing to increasing from the fourth frequency to the high frequency side is defined as the fifth frequency, and the average value of the gain values from the fourth frequency to the fifth frequency in the current frequency characteristics and the reference frequency Calculate the deviation from the average value of the gain values from the fourth frequency to the fifth frequency in the characteristics,
A method for determining deterioration of a movable part of an injection molding machine that determines that the movable part has deteriorated when an absolute value of the calculated gain deviation value exceeds a threshold value.   The determination of deterioration of a movable part of an injection molding machine according to any one of claims 7 to 9, wherein the movable part is a timing belt, and the deterioration determination method is a timing belt tension decrease determination method. Method.

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