JP2006272560A - Method and device for monitoring conditions of molding machines - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and exactly monitor the conditions of molding machines. <P>SOLUTION: A device comprises a drive part driven for operating the molding machine, a first detection part P1 detecting a first variable m1 simultaneously with the driving of the drive part, a second detection part P2 detecting a second variable m2, and a transmission characteristic judgement means judging transmission characteristics in a transmission route Rt between the first and second detection parts P1 and P2 based on the first and second variables m1 and m2. Since the transmission characteristics in the transmission route Rt between the first and second detection parts P1 and P2 are judged on the basis of the first and second variables m1 and m2, even when all the molding machines are different from each other and used in different conditions, the conditions of the molding machines can be monitored easily and exactly. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a molding machine state monitoring apparatus and a molding machine state monitoring method.

  Conventionally, in a molding machine, for example, an injection molding machine, a resin heated and melted in a heating cylinder is injected at a high pressure to fill a cavity space of a mold apparatus, and cooled and solidified in the cavity space. Then, the molded product is taken out.

  The injection molding machine includes a mold device, a mold clamping device, and an injection device. The mold device includes a mold including a fixed mold and a movable mold. The mold clamping device includes a fixed platen, a movable platen, and a mold. A mold clamping motor, a toggle mechanism, and the like are provided as a clamping drive unit. When the mold clamping motor is driven and the ball screw is actuated to advance and retract the cross head, the toggle mechanism is actuated to advance and retract the movable platen to perform mold closing, mold clamping and mold opening. The injection apparatus includes the heating cylinder that heats and melts the resin supplied from the hopper, and an injection nozzle that injects the molten resin, and a screw is rotatable in the heating cylinder, and It is arranged to be able to advance and retreat. Then, the metering motor is driven and the screw is rotated to accumulate resin in front of the screw, the injection motor is driven, and the screw is advanced to inject the resin from the injection nozzle.

  By the way, if the injection molding machine is continuously operated, elements such as a ball screw and a bearing may be damaged. Therefore, the state of the injection molding machine is monitored based on the number of molding shots after the use of the injection molding machine is started.

  However, the conventional injection molding machine not only has a difference for each injection molding machine, that is, a machine difference, but also the usage situation differs for each injection molding machine, so the state of the injection molding machine is accurately monitored. I can't.

  Therefore, the operation of the injection molding machine cannot be performed stably.

  The present invention provides a molding machine state monitoring apparatus and a molding machine state monitoring method capable of solving the problems of the conventional injection molding machine and easily and accurately monitoring the state of the molding machine. The purpose is to do.

  Therefore, in the molding machine state monitoring apparatus of the present invention, a drive unit that is driven to operate the molding machine, and a first detection unit that detects a first variable as the drive unit is driven, A transmission characteristic in a transmission path between the first detection unit and the second detection unit based on the second detection unit detecting the second variable and the first and second variables as the driving unit is driven. And transfer characteristic determination processing means for determining.

  According to the present invention, in the molding machine state monitoring apparatus, a drive unit that is driven to operate the molding machine, and a first detection unit that detects a first variable accompanying the drive of the drive unit, A transmission characteristic in a transmission path between the first detection unit and the second detection unit based on the second detection unit detecting the second variable and the first and second variables as the driving unit is driven. And transfer characteristic determination processing means for determining.

  In this case, since the transmission characteristic in the transmission path between the first and second detection units is determined based on the first and second variables, each molding machine can be used even if there is a machine difference between the molding machines. Even if the use situation differs for each, the state of the molding machine can be monitored easily and accurately.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, an injection molding machine as a molding machine will be described.

  FIG. 2 is a schematic view of an injection molding machine according to the first embodiment of the present invention.

  In the figure, 51 is an injection apparatus, 52 is a mold apparatus comprising a fixed mold 11 as a first mold and a movable mold 12 as a second mold, and 53 is arranged facing the injection apparatus 51. The mold clamping device provided, 54 is a plasticizing movement device that supports the injection device 51 so as to be able to advance and retreat, 55 is an ejector device, 60 is a mold thickness adjustment device that functions as a toggle adjustment device, fr1 is the injection device 51, and the mold A molding machine frame that supports the fastening device 53, the plasticizing moving device 54, and the like.

  The injection device 51 is attached to a heating cylinder 56 as a cylinder member, a screw 57 as an injection member disposed in the heating cylinder 56 so as to be rotatable and movable back and forth, and a front end of the heating cylinder 56. The injection nozzle 58, a hopper 59 disposed in the vicinity of the rear end of the heating cylinder 56, a screw shaft 61 formed to protrude from the rear end of the screw 57, and a load cell 70 as a load detection unit are connected. A front support 71 and a rear support 72, and a pressure plate 62 rotatably mounted on the screw shaft 61 and attached to the front support 71. Rotation transmission system (driving pulley as driving element, driven pulley as driven element, and driving pulley and driven pulley) And a timing belt as a transmission member stretched between the screw shaft 61 and a measuring motor 66 as a measuring drive unit connected to the screw shaft 61 through 65, and a pulley attached to the molding machine frame fr1. A belt-type rotation transmission system (consisting of a driving pulley as a driving element, a driven pulley as a driven element, and a timing belt as a transmission member stretched between the driving pulley and the driven pulley) 68 An injection motor 69 as an injection drive unit connected to a ball screw 75 as a movement direction conversion unit is provided. The ball screw 75 functions as a motion direction conversion unit that converts rotational motion into linear motion, and is attached to the ball screw shaft 73 as the first conversion element connected to the rotation transmission system 68 and the rear support portion 72. And a ball nut 74 as a second conversion element screwed with the ball screw shaft 73.

  Further, the plasticizing movement device 54 is attached to the guide unit fr2, the guide unit fr2, and disposed along the longitudinal direction of the plasticizing movement motor 77 as a plasticizing movement driving unit and the guide unit fr2. The first conversion element that is rotatably arranged with respect to the guide 78 and the guide unit fr 2 that guide the front support portion 71 and the rear support portion 72 and is rotated by driving the plasticizing movement motor 77. A ball screw shaft 81, a ball nut 82 as a second conversion element screwed to the ball screw shaft 81, a bracket 83 attached to the rear end of the heating cylinder 56, the ball nut 82 and the bracket 83, And a spring 84 as an urging member disposed between the two. The ball screw shaft 81 and the ball nut 82 constitute a ball screw 86, and the ball screw 86 functions as a motion direction conversion unit that converts rotational motion into linear motion.

  The mold clamping device 53 includes a fixed platen 91 as a first platen attached to the molding machine frame fr1, a toggle support 92 as a base plate, and a tie bar installed between the fixed platen 91 and the toggle support 92. 93, a movable platen 94 as a second platen that is disposed so as to face the fixed platen 91 and can be moved back and forth along the tie bar 93, and is disposed between the movable platen 94 and the toggle support 92. A toggle mechanism 95, a mold clamping motor 96 as a mold clamping drive unit, and a pulley / belt type rotation transmission system for transmitting the rotation generated by driving the mold clamping motor 96 to the toggle mechanism 95. (Drive pulley as drive element, driven pulley as driven element, and transmission stretched between drive pulley and driven pulley Consisting timing belt as wood.) 97 comprises the rotation transmission system 97 a ball screw 98 as a motion direction converting portion which is connected to the crosshead 99 or the like which is connected with the ball screw 98. The fixed mold 11 and the movable mold 12 are attached to the fixed platen 91 and the movable platen 94 so as to face each other.

  The ball screw 98 functions as a motion direction conversion unit that converts rotational motion into linear motion, and is attached to a ball screw shaft 101 as a first conversion element connected to the rotation transmission system 97, and a crosshead 99, A ball nut 102 is provided as a second conversion element screwed into the ball screw shaft 101.

  The toggle mechanism 95 is configured to swing with respect to a toggle lever 105 that is swingably supported with respect to the cross head 99, a toggle lever 106 that is swingably supported with respect to the toggle support 92, and a movable platen 94. A toggle arm 107 that is movably supported is provided, and the toggle levers 105 and 106 and between the toggle lever 106 and the toggle arm 107 are linked.

  The toggle mechanism 95 advances and retracts the movable platen 94 along the tie bar 93 by advancing and retracting the crosshead 99 between the toggle support 92 and the movable platen 94 by a servo motor (not shown), and the movable mold 12 is fixedly fixed. 11, the mold is closed, the mold is clamped and the mold is opened.

  The ejector device 55 is disposed on the rear end surface of the movable platen 94, and is arranged to be movable forward and backward with respect to the movable platen 94. The protrusion motor 112 as a drive unit for protrusion, the cross A ball screw shaft 113 as a first conversion element disposed rotatably with respect to the head 111, and a ball as a second conversion element attached to the cross head 111 and screwed to the ball screw shaft 113 A pulley-belt-type rotation transmission system (a driving pulley as a driving element, a driven pulley as a driven element, and (It comprises a timing belt as a transmission member stretched between a driving pulley and a driven pulley.) 116, Comprising an ejector rod and ejector pins (not shown) or the like is caused to advance and retreat along with the advance and retreat of Rosuheddo 111. A ball screw 115 is constituted by the ball screw shaft 113 and the ball nut 114, and the ball screw 115 functions as a motion direction conversion unit that converts a rotational motion into a straight motion.

  The mold thickness adjusting device 60 is screwed into a threaded portion formed at the rear end of each tie bar 93, and serves as an adjustment nut 121 as a toggle adjusting member and as a mold thickness adjusting member, and a toggle adjusting member. And a die thickness motor 122 as a die thickness adjusting drive unit, a timing belt 123 as a transmission member for transmitting rotation generated by driving the die thickness motor 122 to each adjusting nut 121, and the like. The mold support is adjusted by moving the toggle support 92 forward and backward with respect to the fixed platen 91.

  Next, the operation of the injection molding machine will be described.

  First, when the plasticizing movement motor 77 is driven in the injection device 51, the rotation of the plasticizing movement motor 77 is transmitted to the ball screw shaft 81, and the ball nut 82 is moved forward and backward. Then, the thrust of the ball nut 82 is transmitted to the bracket 83 via the spring 84, and the injection device 51 is advanced and retracted.

  Next, when the measuring motor 66 is driven in the measuring step, the rotation of the measuring motor 66 is transmitted to the screw shaft 61 via the rotation transmission system 65 and the screw 57 is rotated. The resin as the molding material supplied from the hopper 59 is heated and melted in the heating cylinder 56, moves forward, and is stored in front of the screw 57. Along with this, the screw 57 is retracted to a predetermined position.

  In the injection process, when the injection nozzle 58 is pressed against the fixed mold 11 and the injection motor 69 is driven, the rotation of the injection motor 69 is transmitted to the ball screw shaft 73 via the rotation transmission system 68, and the ball The screw shaft 73 is rotated. At this time, the load cell 70 moves with the rotation of the ball screw shaft 73 and advances the screw 57. Therefore, the resin accumulated in front of the screw 57 is injected from the injection nozzle 58, and the fixed mold 11 and the movable mold 11 are moved. The cavity space formed between the mold 12 is filled. The reaction force at that time is received by the load cell 70 and detected as a load.

  Next, when the mold clamping motor 96 is driven in the mold clamping device 53 and the ejector device 55, the rotation of the mold clamping motor 96 is transmitted to the ball screw shaft 101 via the rotation transmission system 97, and the ball nut 102 is advanced and retracted, and the crosshead 99 is also advanced and retracted. As the cross head 99 advances, the toggle mechanism 95 is extended, the movable platen 94 is advanced to close the mold, and the movable mold 12 is brought into contact with the fixed mold 11. Subsequently, when the mold clamping motor 96 is further driven, a mold clamping force is generated in the toggle mechanism 95, and the movable mold 12 is pressed against the fixed mold 11 by the mold clamping force. A cavity space is formed between the mold 12. Further, when the toggle mechanism 95 is bent along with the retraction of the cross head 99, the movable platen 94 is retracted and the mold is opened.

  Subsequently, when the protrusion motor 112 is driven, the rotation of the protrusion motor 112 is transmitted to the ball screw shaft 113 via the rotation transmission system 116, the cross head 111 is advanced and retracted, and the ejector rod is advanced and retracted. . As the mold is opened, when the cross motor 111 is further moved forward by driving the protruding motor 112, the ejector pin is moved forward and the molded product is ejected.

  Next, when the mold thickness motor 122 is driven in the mold thickness adjusting device 60, the rotation of the mold thickness motor 122 is transmitted to each adjusting nut 121 via the timing belt 123, and each adjusting nut 121 is rotated. As it is moved, the tie bar 93 is advanced and retracted, and the toggle support 92 is advanced and retracted. As a result, the mold thickness is adjusted, and the reference position of the toggle mechanism 95 is adjusted.

  Next, a control circuit of the injection molding machine having the above configuration will be described.

  FIG. 3 is a block diagram showing a control circuit of the injection molding machine according to the first embodiment of the present invention.

  In the figure, 201 is a control unit, 66 is a weighing motor, 69 is an injection motor, 77 is a plasticizing movement motor, 96 is a mold clamping motor, 112 is a protrusion motor, and 122 is a mold thickness motor. Encoders 211 to 216 as rotation angle detectors are disposed on the motor 66, the injection motor 69, the plasticizing movement motor 77, the mold clamping motor 96, the protruding motor 112, and the mold thickness motor 122, respectively. A rotation angle is detected by each encoder 211-216. In addition, current sensors 221 to 226 as current detection units are disposed on the weighing motor 66, the injection motor 69, the plasticizing movement motor 77, the mold clamping motor 96, the protruding motor 112, and the mold thickness motor 122, respectively. The current is detected by each of the current sensors 221 to 226. The metering motor 66, the injection motor 69, the plasticizing movement motor 77, the mold clamping motor 96, the protruding motor 112, and the mold thickness motor 122 were set at predetermined positions of the injection molding machine. A signal input unit is configured, and a driving current is input to each motor coil as a signal.

  Further, gi (i = 1, 2,..., N) is a strain gauge as a strain detector disposed in a bearing that supports a predetermined rotating body, and each strain gauge gi is generated in each bearing. Detect distortion. In addition, h1 to h4 are strain gauges as strain detectors disposed on the ball screw shafts 73 (FIG. 2), 81, 101, and 113, and the strain gauges h1 to h4 are the ball screw shafts 73. , 81, 101, 113 are detected. In addition, h5 to h8 are strain gauges as strain detection units disposed on the ball nuts 74, 82, 102, and 114, and the strain gauges h5 to h8 are respectively ball nuts 74, 82, 102, and 114. Detects the distortion generated in

  Reference numeral 231 denotes an acceleration sensor as an acceleration detection unit disposed in a coupling (not shown) that connects the screw 57 and the screw shaft 61. The acceleration sensor 231 detects the acceleration of the coupling. Reference numeral 232 denotes a resin pressure sensor as a pressure detector disposed at the front end in the heating cylinder 56, and the resin pressure sensor 232 detects the pressure of the resin in the heating cylinder 56, that is, the resin pressure. . Further, h11 is a strain gauge as a strain detector disposed on the guide 78, and each strain gauge h11 detects the strain of the guide 78. Reference numeral 70 denotes a load cell, 235 denotes a display unit, and 236 denotes an alarm device. Reference numerals 241 to 244 denote rotational speed sensors serving as rotational speed detectors arranged facing the screw shaft 61 and the ball screw shafts 73, 101, and 113. The rotational speed sensors 241 to 244 correspond to the screw shaft 61. The rotational speed of the ball screw shafts 73, 101, 113 is detected.

  In operating the injection molding machine having the above-described configuration, when each of the metering motor 66, the injection motor 69, the plasticizing movement motor 77, the mold clamping motor 96, the protruding motor 112, and the mold thickness motor 122 is driven, The screw 57 is rotated, and the screw 57, the injection device 51, the movable platen 94, the toggle support 92, the ejector pin, and the like are advanced and retracted.

  When each motor, for example, the injection motor 69 is driven, frictional force and contact force are generated between various portions of the injection molding machine, for example, the ball screw shaft 73 and the ball nut 74 in the ball screw 75. In addition, frictional force and contact force are generated between other elements such as the cylinder part and the casing part.

  Therefore, when the state changes at a predetermined location of the injection molding machine, for example, when the ball screw 75 is damaged, the friction characteristic and the contact characteristic change, and the vibration component in the friction force and the contact force changes.

  Therefore, in the present embodiment, changes in the friction characteristics and contact characteristics are detected, and the state of the injection molding machine is monitored based on changes in the friction characteristics and contact characteristics.

  FIG. 1 is a conceptual diagram of a state monitoring apparatus according to the first embodiment of the present invention, FIG. 4 is a waveform diagram of input signals and output signals according to the first embodiment of the present invention, and FIG. It is a figure which shows the Bode diagram phase curve in the embodiment. In FIG. 4, the horizontal axis represents time, the vertical axis represents the input signal ip and the output signal op, and in FIG. 5, the horizontal axis represents the frequency, and the vertical axis represents the phase difference.

  In this case, sensors arranged at two preselected sites are set as the first and second detection units P1 and P2, and the first and second detection units P1 and P2 are mechanically connected. , And at least one of electrical connections. A transmission path Rt that mechanically or electrically connects the first and second detection units P1 and P2 is set between the first and second detection units P1 and P2. The variable detected by the first detection unit P1 is set as the first variable m1, the variable detected by the second detection unit P2 is set as the second variable m2, and the first and second variables. Changes in the friction characteristics and the contact characteristics are detected based on m1 and m2.

  As the first and second detection units P1 and P2, any sensor whose sensor output changes as a predetermined motor is driven can be selected and set. That is, a predetermined one of encoders 211 (FIG. 3) to 216, current sensors 221 to 226, strain gauges gi, h1 to h8 and h11, acceleration sensor 231, resin pressure sensor 232, load cell 70, and rotational speed sensors 241 to 244. Two sensors are set as the first and second detection units P1 and P2, and the rotation angles detected by the encoders 211 to 216, the currents detected by the current sensors 221 to 226, the strain gauges gi, h5 to h8. , The amount of strain detected by h11, the torque detected by the strain gauges h1 to h4, the acceleration detected by the acceleration sensor 231, the resin pressure detected by the resin pressure sensor 232, the load detected by the load cell 70, and the rotation Of the rotational speeds detected by the speed sensors 241 to 244, the first detection is performed. The variable detected by the parts P1 as a first variable m1, it is possible to set the variables which are detected by the second detecting portion P2 as a second variable m @ 2.

  By the way, when the location for monitoring the state (hereinafter referred to as “monitoring location”) and the content for monitoring the state (hereinafter referred to as “monitoring content”) are determined in the injection molding machine, depending on the monitoring location and the monitoring content, the friction characteristics. In addition, there are variables that are likely to change in contact characteristics and variables that are less likely to occur. Therefore, in the present embodiment, the first and second detection units P1 and P2 are set according to the monitoring location and the monitoring content, and the variables of the first and second detection units P1 and P2 are set to the first, The second variables m1 and m2 are set.

  That is, in this embodiment, when monitoring the performance of the metering motor 66, the current sensor 221 is in the first detection unit P1, the encoder 211 is in the second detection unit P2, and the current is in the first variable m1. In addition, the rotation angle is set to the second variable m2. Similarly, when monitoring the performance of the injection motor 69, the plasticizing movement motor 77, the mold clamping motor 96, the protruding motor 112, and the mold thickness motor 122, the current sensors 222 to 226 are connected to the first detection unit P1. The encoders 212 to 216 are set to the second detection unit P2, the current is set to the first variable m1, and the rotation angle is set to the second variable m2.

  When monitoring the performance of the bearing, the motor driven to rotate the rotating body among the motors is specified. If the weighing motor 66 is driven and the strain gauge disposed on the bearing is g1, the current sensor 221 is the first detection unit P1, and the strain gauge g1 is the second detection unit. In P2, the current is set to the first variable m1, and the distortion is set to the second variable m2.

  When monitoring the torque transmission level generated in the ball screw shafts 73, 81, 101, 113, the current sensors 222 to 223 are the first detection unit P1, and the strain gauges h1 to h4 are the second detection unit P2. In addition, the current is set to the first variable m1, and the distortion is set to the second variable m2. When the wear generated in the ball screws 75, 86, 98, and 115 is monitored, the current sensors 222 to 223 are connected to the first detector P1, the strain gauges h5 to h8 are connected to the second detector P2, Is the first variable m1, and the distortion is the second variable m2.

  When the state of the resin in the heating cylinder 56 is monitored, the acceleration sensor 231 is the first detection unit P1, the resin pressure sensor 232 is the second detection unit P2, and the acceleration is the first variable m1. The pressure is set to the second variable m2. When the state of the heating cylinder 56 is monitored, the resin pressure sensor 232 is in the first detection unit P1, the strain gauge h11 is in the second detection unit P2, the resin pressure is in the first variable m1, and the strain amount is The second variable m2. Further, when monitoring the detection value of the load cell 70, the strain gauge h11 is in the first detection unit P1, the load cell 70 is in the second detection unit P2, the strain amount is in the first variable m1, and the load is in the second range. The variable is m2.

  When monitoring the state of the rotation transmission systems 65, 68, 97, and 116, the encoders 211, 212, 214, and 215 are in the first detection unit P1, and the rotation speed sensors 241 to 244 are in the second detection unit P2. The rotation angle is set to the first variable m1, and the rotation speed is set to the second variable m2. When the molding state is monitored, the current sensor 222 is set to the first detection unit P1, the load cell 70 is set to the second detection unit P2, the current is set to the first variable m1, and the load is set to the second variable m2. The

  When the first and second detection units P1 and P2 and the first and second variables m1 and m2 are set in this way, a vibration variable acquisition processing unit (vibration variable acquisition processing unit) (not shown) of the control unit 201 is set. Performs a vibration variable acquisition process, and reads and acquires the first and second variables m1 and m2 in time series. The first and second variables m1 and m2 are composed of time series data as shown in FIG. 4, and the input signal ip and the output signal op in the transmission path Rt between the first and second detectors P1 and P2. Configure.

  In the present embodiment, when sensors other than the acceleration sensor 231 and the rotation speed sensors 241 to 244 are used, the input signal ip and the output signal op are the first and second variables m1, which represent the displacement of the vibration component. m2 itself, but the acceleration of the vibration component, such as the vibration speed representing the speed of the vibration component, such as the rotation speed detected by the rotation speed sensors 241 to 244, or the acceleration detected by the acceleration sensor 231. Can be used as the input signal ip and the output signal op.

  In that case, a vibration speed calculation processing means (vibration speed calculation processing section) (not shown) of the control unit 201 performs vibration speed calculation processing, reads the first and second variables m1 and m2, and differentiates the vibration. The speed is calculated and acquired as the input signal ip and the output signal op. Alternatively, a vibration acceleration calculation processing unit (vibration acceleration calculation processing unit) (not shown) of the control unit 201 performs vibration acceleration calculation processing, reads the first and second variables m1 and m2, and differentiates twice to thereby generate vibration. The acceleration is calculated and acquired as the input signal ip and the output signal op.

  A time / frequency domain conversion processing unit (time / frequency domain conversion processing unit) (not shown) of the control unit 201 performs time / frequency domain conversion processing to convert the time-series data of FIG. 4 from the time domain to the frequency domain. Then, Bode diagram phase curves L1 and L2 as shown in FIG. 5 are obtained. The Bode diagram phase curves L1 and L2 represent transfer characteristics in the transfer path Rt, and can be obtained by Fourier transforming the input signal ip and the output signal op by a calculation method such as FFT or DFT. That is, when the input signal ip and the output signal op are Fourier transformed, and the phase difference between the input signal ip and the output signal op for each frequency is calculated, the frequency represented by the Bode diagram phase curves L1 and L2 is obtained. A relationship with the phase difference is obtained.

  By the way, the Bode diagram phase curve obtained based on the input signal ip and the output signal op when the injection molding machine can be operated normally as in the initial operation when the operation is started after the injection molding machine is installed. Is L1, and then the operation is continued, and the Bode diagram phase curve obtained based on the input signal ip and the output signal op after starting the monitoring of the state of the injection molding machine is L2, as shown in FIG. Thus, the Bode diagram phase curves L1 and L2 are deviated. The Bode diagram phase curve L1 represents the reference value of the transfer characteristic, and the Bode diagram phase curve L2 represents the actual value of the transfer characteristic.

  Therefore, a transfer characteristic determination processing unit (transfer characteristic determination processing unit) (not shown) of the control unit 201 performs transfer characteristic determination processing, determines the transfer characteristic by comparing the Bode diagram phase curves L1 and L2, and determines the frequency. Based on this change, the divergence amount of the Bode diagram phase curves L1 and L2 is calculated, and when the divergence amount becomes larger than the threshold, it is determined that an abnormality has occurred in the injection molding machine.

In each of the Bode diagram phase curves L1 and L2, fp1 and fp2 are frequencies at which the transfer function becomes a peak value when the input signal ip and the output signal op are respectively Fourier transformed, that is, a peak value frequency. Therefore, for example, the change in frequency is represented by the change amount Δfp of the peak value frequencies fp1 and fp2.
Δfp = fp2−fp1
The change amount Δfp can be used as the deviation amount. As a result, when the change amount Δfp is greater than the threshold value Δfpth, the transfer characteristic determination processing unit determines that the deviation amount is greater than the threshold value, and determines that an abnormality has occurred in the injection molding machine.

  Then, a notifying processing means (notifying processing unit) (not shown) of the control unit 201 performs a notifying process, displays that the abnormality has occurred on the display unit 235, operates the alarm device 236, sounds an alarm, and operates Informs the person that an abnormality has occurred. Furthermore, a stop processing unit (stop processing unit) (not shown) of the control unit 201 performs a stop process, and can stop the operation of the injection molding machine when an abnormality occurs in the display unit 235.

  In addition, the operator of the injection molding machine can be notified of the occurrence of an abnormality. In this case, a plurality of threshold values are set in advance, and when the change amount Δfp reaches a lower threshold value among the threshold values, an abnormality occurrence notice processing unit (not shown) of the control unit 201 performs an abnormality occurrence notice process, and the operator Announce the occurrence of abnormalities. Therefore, the operator can grasp the parts that are likely to be damaged before damaging them, so that the parts can be stocked in advance, and when an abnormality occurs, without greatly affecting the production process, Parts can be replaced.

  In addition, an injection molding machine and an external device are connected via a communication line such as a LAN, a telephone line, or a wireless communication line, and an abnormality occurs in a person involved in maintenance and management of the injection molding machine such as a parts manufacturer or an injection molding machine manufacturer. It is possible to notify that it has been done. In this case as well, parts can be exchanged without significantly affecting the production process.

Note that the change in frequency is the change rate γp of the peak value frequencies fp1 and fp2.
γp = fp2 / fp1
The rate of change γp can be used as the deviation amount. In this case, when the rate of change γp is greater than the threshold value γpth, the transfer characteristic determination processing unit determines that the deviation amount is greater than the threshold value and determines that an abnormality has occurred in the injection molding machine.

  In the present embodiment, the divergence amount between the Bode diagram phase curves L1 and L2 is calculated based on the change in the frequency, but the Bode diagram phase curves L1 and L2 are calculated based on the change in the phase difference. The amount of deviation can also be calculated.

That is, a predetermined frequency fu between the peak value frequencies fp1 and fp2 is set in advance, and the amount of change Δφ in the phase differences φ1 and φ2 at the frequency fu.
Δφ = φ2-φ1
When the change amount Δφ is larger than the threshold value Δφth, it is determined that the deviation amount is larger than the threshold value, and it can be determined that an abnormality has occurred in the injection molding machine.

Further, the change rate γφ of the phase differences φ1 and φ2 at the frequency fu
γφ = φ2 / φ1
When the change rate γφ is larger than the threshold value γφth, it is determined that the deviation amount is larger than the threshold value, and it can be determined that an abnormality has occurred in the injection molding machine.

  In the present embodiment, the amount of change Δφ in the phase differences φ1 and φ2 at one frequency fu is calculated, but the amount of change in the phase difference at two or more frequencies is added, and the added change When the amount is larger than the threshold, it can be determined that the deviation amount is larger than the threshold.

  Thus, since the state of the injection molding machine is monitored based on the first and second variables m1 and m2 in the first and second detection units P1 and P2, the machine for each injection molding machine is used. Even if there is a difference, even if the usage situation differs for each injection molding machine, the state of the injection molding machine can be monitored easily and accurately.

  In the present embodiment, it is preferable to read the first and second variables m1 and m2 at the timing when the vibration components of the first and second variables m1 and m2 become large. Immediately after the start of metering, the injection motor 69 starts to be driven. Immediately after the injection is started, the mold clamping motor 96 starts to be driven and the mold closing or mold opening is started. Immediately after, the first and second variables m1 and m2 are read.

  Next, a second embodiment of the present invention will be described.

  FIG. 6 is a waveform diagram showing a frequency response in the second embodiment of the present invention, and FIG. 7 is a diagram showing a Bode diagram gain curve in the second embodiment of the present invention. In FIG. 6, the horizontal axis represents frequency, the vertical axis represents amplitude, the horizontal axis represents frequency, and the vertical axis represents gain.

  In this case, first, the vibration variable acquisition processing means of the control unit 201 (FIG. 1) reads and acquires the first and second variables m1 and m2 in time series. The first and second variables m1 and m2 are composed of time series data as shown in FIG. 4, and the input signal ip and the output signal op in the transmission path Rt between the first and second detectors P1 and P2. Configure.

  Then, the time / frequency domain conversion processing means converts the time-series data of FIG. 4 from the time domain to the frequency domain, and obtains frequency response curves Lip and Loop as shown in FIG.

  The frequency response curves Lip and Loop can be obtained by Fourier transforming the input signal ip and the output signal op by a calculation method such as FFT or DFT. That is, when the input signal ip and the output signal op are Fourier-transformed and the amplitudes of the input signal ip and the output signal op for each frequency are calculated, the relationship between the frequency and the amplitude as represented by the frequency response curves Lip and Loop. Is obtained.

  Subsequently, a transfer function calculation processing unit (transfer function calculation processing unit) (not shown) of the control unit 201 performs a transfer function calculation process, and for each frequency, divides the amplitude of the output signal op by the amplitude of the input signal ip, The gain of the transfer path Rt is calculated as a transfer function. As a result, as shown in FIG. 7, Bode diagram gain curves L11 and L12 can be obtained. The Bode diagram phase curves L11 and L12 represent transfer characteristics in the transfer path Rt.

  By the way, as described above, the Bode diagram gain curve obtained based on the input signal ip and the output signal op when the injection molding machine can be operated normally is set to L11, and then the operation is continued. Assuming that the Bode diagram gain curve obtained based on the input signal ip and the output signal op after starting the monitoring of the state of the molding machine is L12, the Bode diagram phase curves L11 and L12 are as shown in FIG. Deviation.

  Therefore, the transfer characteristic determination processing means determines the transfer characteristic by comparing the Bode diagram gain curves L11 and L12, calculates the divergence amount of the Bode diagram gain curves L11 and L12 based on the change in frequency, When the deviation amount becomes larger than the threshold value, it is determined that an abnormality has occurred in the injection molding machine.

In each Bode diagram gain curve L11, L12, fp1 and fp2 are peak value frequencies. Accordingly, the change in frequency is represented by the change amount Δfp of the peak value frequencies fp1 and fp2.
Δfp = fp2−fp1
The change amount Δfp can be used as the deviation amount. As a result, when the change amount Δfp is greater than the threshold value Δfpth, the transfer characteristic determination processing unit determines that the deviation amount is greater than the threshold value, and determines that an abnormality has occurred in the injection molding machine.

  The notification processing means displays on the display unit 235 (FIG. 3) that an abnormality has occurred, operates the alarm device 236, sounds an alarm, and notifies the operator that an abnormality has occurred.

Note that the change in frequency is the change rate γp of the peak value frequencies fp1 and fp2.
γp = fp2 / fp1
The rate of change γp can be used as the deviation amount. In this case, when the rate of change γp is greater than the threshold value γpth, the transfer characteristic determination processing unit determines that the deviation amount is greater than the threshold value and determines that an abnormality has occurred in the injection molding machine.

  In the present embodiment, the divergence amount between the Bode diagram gain curves L11 and L12 is calculated based on the change in the frequency, but the divergence between the Bode diagram gain curves L11 and L12 is calculated based on the change in the gain. The amount can also be calculated.

That is, a predetermined frequency fv of the peak value frequency fp2 between the peak value frequencies fp1 and fp2 is set in advance, and a change amount Δg of the gains g1 and g2 at the frequency fv.
Δg = g2−g1
When the change amount Δg is larger than the threshold value Δgth, it is determined that the deviation amount is larger than the threshold value, and it can be determined that an abnormality has occurred in the injection molding machine.

The rate of change γg of the gains g1 and g2 at the frequency fv
γg = g2 / g1
When the change rate γg is larger than the threshold value γgth, it is determined that the deviation amount is larger than the threshold value, and it can be determined that an abnormality has occurred in the injection molding machine.

  In the present embodiment, the amount of change Δg of the gains g1 and g2 at one frequency fv is calculated, but the amount of gain change at two or more frequencies is added, and the added amount of change is When larger than the threshold, it can be determined that the amount of deviation is larger than the threshold.

  Further, the transfer characteristic can be expressed by a gain for each time in addition to a gain for each frequency. In this case, a time delay between the input signal input to each drive unit and the output signal output from the driven unit is a target for determining whether or not an abnormality has occurred in the injection molding machine.

  Further, when it is determined whether or not an abnormality has occurred in the injection molding machine based on fluctuations in the first and second variables m1 and m2 over a long time, the transfer characteristic can be expressed by a gain for each molding shot. .

  In each of the above embodiments, in order to make the detection conditions of the first and second variables m1 and m2 constant, the injection molding machine is operated in a preset pattern during the initial operation, When time series data is collected and thereafter the same operation is periodically performed at predetermined intervals, the injection molding machine is operated in the same pattern, and the time series data is collected each time, the first and second The detection accuracy of the variables m1 and m2 can be increased.

  In addition, when the injection molding machine is operated repeatedly several times during the initial operation and periodically, the time series data is collected a plurality of times, and then the averaging process is performed, the first and second variables m1 and m2 are detected. The accuracy can be further increased.

  In the sensors other than the acceleration sensor 231 and the rotational speed sensors 241 to 244, the first and second variables m1 and m2 representing the displacement of the vibration component are generated. Sensors that generate the first and second variables m1 and m2 that represent the velocity of the vibration component such as 241 to 244 are used, or the first and second that represent the acceleration of the vibration component such as the acceleration sensor 231. Sensors that generate two variables m1 and m2 can be used.

  Sensors for generating the first and second variables m1 and m2 representing the displacement of the vibration component include piezoelectric type, capacitance type, servo type, strain gauge type, laser Doppler type, ultrasonic type, laser A displacement meter such as an interference type, an electromagnetic induction type, or an encoder type can be used. As sensors for generating the first and second variables m1 and m2 representing the speed of the vibration component, piezoelectric type, capacitance type, servo type, strain gauge type, laser Doppler type speedometer, etc. are used. As the sensors for generating the first and second variables m1 and m2 representing the acceleration, an accelerometer of a piezoelectric type, a capacitance type, a servo type, a strain gauge type or the like can be used.

  Thus, various sensors can be used to generate the first and second variables m1 and m2. For this purpose, various measurement methods such as a mechanical measurement method, an electrical measurement method, a magnetic measurement method, an optical measurement method, and a sonic measurement method are used.

  Further, in the present embodiment, the first and second variables m1 and m2 are generated while the drive unit is driven. However, the injection is performed by a hammer or the like while the injection molding machine is stopped. The first and second detectors can generate the first and second variables when an impact is applied to a predetermined portion of the molding machine. In this case, based on the first and second variables. Thus, the transfer characteristic can be determined. As a result, unnecessary disturbance can be minimized, so that transfer characteristics can be determined with the highest accuracy. In this case, the signal input unit is configured by the location where the impact is applied, and the signal is configured by the impact.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

It is a conceptual diagram of the state monitoring apparatus in the 1st Embodiment of this invention. It is the schematic of the injection molding machine in the 1st Embodiment of this invention. It is a block diagram which shows the control circuit of the injection molding machine in the 1st Embodiment of this invention. It is a wave form chart of an input signal and an output signal in a 1st embodiment of the present invention. It is a figure which shows the Bode diagram phase curve in the 1st Embodiment of this invention. It is a wave form diagram which shows the frequency response in the 2nd Embodiment of this invention. It is a figure which shows the Bode diagram gain curve in the 2nd Embodiment of this invention.

Explanation of symbols

69 Motor for injection 77 Motor for plasticization 96 Mold clamping motor 112 Projecting motor 122 Mold thickness motor 201 Controllers m1, m2 First and second variables P1, P2 First and second detectors Rt Transmission path

Claims (9)

(A) a drive unit that is driven to operate the molding machine;
(B) a first detection unit that detects a first variable as the driving unit is driven;
(C) a second detection unit that detects a second variable as the driving unit is driven;
(D) a state of a molding machine comprising: a transmission characteristic determination processing unit that determines a transmission characteristic in a transmission path between the first and second detection units based on the first and second variables. Monitoring device. (A) a signal input unit that is set in advance in a predetermined portion of the molding machine and receives a signal;
(B) a first detection unit that detects a first variable in accordance with the input of a signal to the signal input unit;
(C) a second detection unit that detects a second variable in accordance with the input of the signal to the signal input unit;
(D) a state of a molding machine comprising: a transmission characteristic determination processing unit that determines a transmission characteristic in a transmission path between the first and second detection units based on the first and second variables. Monitoring device.   The state monitoring apparatus for a molding machine according to claim 1 or 2, wherein the first and second detection units are connected to each other in at least one of a mechanical connection and an electrical connection.   The state monitoring apparatus for a molding machine according to claim 1 or 2, wherein the transfer characteristic is represented by a phase difference for each frequency.   The state monitoring device for a molding machine according to claim 1 or 2, wherein the transfer characteristic is represented by a gain for each frequency, for each time, or for each molding shot.   The first and second detection units use the measurement method of at least one of a mechanical measurement method, an electrical measurement method, a magnetic measurement method, an optical measurement method, and a sonic measurement method, thereby The state monitoring device for a molding machine according to claim 1 or 2, wherein the first and second variables are detected.   The molding machine state monitoring apparatus according to claim 1, further comprising an abnormality monitoring processing unit configured to determine whether or not an abnormality has occurred in the molding machine based on the reference value and the actual value of the transfer characteristic.   The state monitoring device for a molding machine according to claim 1 or 2, wherein the transfer characteristic is determined by performing the same operation at every predetermined interval. (A) driving the drive unit to drive the molding machine;
(B) detecting the first variable as the driving unit is driven;
(C) detecting the second variable as the driving unit is driven;
(D) A state monitoring method for a molding machine, wherein transmission characteristics in a transmission path between the first and second detection units are determined based on the first and second variables.

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