Method and device for diagnosing plasticization state of injection molding machine

Abstract

A plasticization state diagnosis method and apparatus for an injection molding machine are provided in which a plurality of AE sensors (6r, 6f) for detecting AE waves (We) are disposed at a plurality of different positions (Xr, Xf) in a front-rear direction (Fs) in a heating cylinder (2), and position data (Dx) relating to the generation position of the AE waves (We) is obtained from the arrival times (tr, tf) of the AE waves (We) obtained from the respective AE sensors (6r, 6f). The number of times that AE wave signals (Sfe...) related to AE waves (We) generated for each predetermined sampling period (Tp) and predetermined position data (Dx) exceed a preset threshold value (L) is determined as sound generation number data (Da), and the number of AE wave components (Sp) exceeding the preset threshold value (L) is determined as event count data (De). At least a generation pattern (Ps) of the sound number data (Da) and the event count data (De) with respect to the position data (Dx...) is graphically displayed.

Description

Technical Field

[0001] The present invention relates to a method and device for diagnosing the plasticization state of an injection molding machine, which are used and preferably used when plasticizing a molding material supplied to the inside of a heating cylinder by the rotation of a screw. Background Art

[0002] Generally, an injection device of an injection molding machine has a function of plasticizing a molding material (such as pellets) supplied to the inside of the heating cylinder from a material supply unit provided at the rear of the heating cylinder heated by a heating unit by the rotation of a screw. Therefore, from the viewpoint of avoiding the occurrence of molding defects and ensuring high molding quality, it is important to accurately grasp the plasticization state of the molding material in the heating cylinder, and various monitoring devices for grasping the plasticization state have also been proposed.

[0003] Conventionally, as such a monitoring device, a material monitoring device for an injection molding machine described in Patent Document 1 proposed by the present applicant has been known. The purpose of the material monitoring device described in Patent Document 1 is to quickly conduct a cause investigation and countermeasure for a poor melting state and to avoid plasticization defects in advance to achieve an ideal plasticization process. Specifically, the material monitoring device described in Patent Document 1 is configured to include: an acoustic emission wave sensing sensor that senses an acoustic emission wave and converts it into an electrical signal, the acoustic emission wave being generated when plasticizing a molding material supplied to the inside of the heating cylinder from a material supply unit provided at the rear of the heating cylinder by the rotation of a screw, causing the molding material to deform or shear inside the heating cylinder, and the heating cylinder being heated by a plurality of heating units including a rear heating unit that heats the rear of the heating cylinder; an acoustic emission detection unit that detects quantitative acoustic emission data related to the deformation or shear of the molding material based on the electrical signal; and a material corresponding processing functional unit that performs a prescribed material corresponding processing using the acoustic emission data.

[0004] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2012 - 111091A

[0005] However, the material monitoring device described in the above Patent Document 1 still has the following problems to be solved.

[0006] That is, an acoustic emission wave sensing sensor (AE sensor: acoustic emission wave sensing sensor) that senses an acoustic emission wave generated when a molding material deforms or shears inside the heating cylinder and is disposed at the rear of the heating cylinder and converts it into an electrical signal has the advantage of being able to detect quantitative acoustic emission data related to the deformation or shear of the molding material based on the electrical signal. However, since it is a quantitative and local detection, for example, from the viewpoint of obtaining more specific and practical information such as which part of the heating cylinder the sound is generated in or what the cause is, there are some difficulties that may not be considered sufficient.

[0007] Therefore, from the viewpoint of ensuring comprehensive (three-dimensional) and even qualitative plasticization information for the heating cylinder to achieve a more practical, convenient, and highly usable monitoring device (plasticization state diagnosis device), there is room for further improvement. Summary of the Invention

[0008] An object of the present invention is to provide a plasticization state diagnosis method and device for an injection molding machine that solve the problems existing in such a background art.

[0009] In order to solve the above problems, the plasticization state diagnosis method of the injection molding machine M of the present invention is characterized in that when diagnosing the plasticization state of the molding material R when the molding material R supplied from the material supply unit 4 provided at the rear of the heating cylinder 2 heated by the heating unit 3f... is plasticized by the rotation of the screw 5, a plurality of AE sensors 6r, 6f for detecting AE waves (acoustic emission waves: We) are arranged at different positions Xr, Xf in the front-rear direction Fs in the heating cylinder 2, and position data Dx related to the generation position of the AE wave We is obtained based on the arrival times tr, tf of the AE waves We obtained from each AE sensor 6r, 6f, and the number of occurrences of the AE wave signal Sfe... related to the AE wave We generated according to each specified sampling period Tp and the specified position data Dx exceeding a preset threshold L is obtained as attack number data Da, and the number of AE wave components Sp exceeding the preset threshold L is obtained as event count data De, and at least the generation pattern Ps of the attack number data Da and the event count data De with respect to the position data Dx... is graphically displayed.

[0010] In addition, to solve the above problems, the plasticizing state diagnosis device 1 of the injection molding machine M of the present invention diagnoses the plasticizing state of the molding material R when the molding material R supplied to the inside of the heating cylinder 2 from the material supply unit 4 provided at the rear of the heating cylinder 2 heated by the heating unit 3f... is plasticized by the rotation of the screw 5. It is characterized in that the plasticizing state diagnosis device 1 of the injection molding machine M has: a plurality of AE sensors 6r, 6f, which are arranged at different positions Xr, Xf in the front-rear direction Fs in the heating cylinder 2 to detect AE waves We; a data processing unit 7, which has a position operation processing unit Ex, a starting number operation processing unit Ea, and an event counting operation processing unit Ee. The position operation processing unit Ex obtains position data Dx related to the generation position of the AE wave We based on the arrival times tr, tf of the AE waves We obtained from each AE sensor 6r, 6f. The starting number operation processing unit Ea obtains the number of occurrences of the AE wave signals Sre, Sfe related to the AE waves We generated according to each specified sampling period Tp and specified position data Dx... exceeding a preset threshold L as starting number data Da... The event counting operation processing unit Ee obtains the number of AE wave components Sp... exceeding a preset threshold L as event counting data De...; and a graphic display unit 8, which graphically displays at least the generation pattern Ps of the starting number data Da... and the event counting data De... with respect to the position data Dx...

[0011] On the other hand, in a preferred embodiment of the present invention, when implementing the plasticizing state diagnosis method, the respective thresholds L for detecting the starting number data Da and the event counting data De can be set to be the same or different. In addition, for the detection signals obtained from the AE sensors 6r, 6f, signals mixed in addition to the signals generated by the heating cylinder 2 during the plasticizing process can be used as noise components Np... for noise removal processing, and for the detection signals obtained from the AE sensors 6r, 6f, filtering processing can be performed to allow only a set specific frequency (frequency) Bs or a set specific frequency band (frequency band) to pass through. On the other hand, when constructing the plasticizing state diagnosis device 1, the graphic display unit 8 can display the generation pattern Ps of the starting number data Da... and the event counting data De... with respect to the position data Dx... in a chart form. In addition, the AE sensors 6r, 6f can have a first AE sensor 6r and a second AE sensor 6f. The first AE sensor 6r can be arranged at the rear side of the heating cylinder 2, and the second AE sensor 6f can be arranged at the front side of the heating cylinder 2. In addition, the AE sensors 6r, 6f can be individually mounted relative to the heating cylinder 2.

[0012] The plasticizing state diagnosis method and device 1 of the injection molding machine M according to the present invention have the following remarkable effects.

[0013] (1) AE sensors 6r and 6f are respectively arranged at different positions Xr and Xf in the front-rear direction Fs in the heating cylinder 2. According to each AE sensor 6r and 6f, position data Dx, onset number data Da, and event count data De are obtained. At least the generation pattern Ps of the onset number data Da... and the event count data De... with respect to the position data Dx... is graphically displayed. Therefore, it is possible to accurately obtain information on which part of the heating cylinder 2 the AE wave We is generated and what causes the AE wave We, etc., from a comprehensive (stereoscopic) and even qualitative perspective of the heating cylinder 2. Thus, a more practical plasticizing state diagnosis device 1 with excellent convenience and usability can be realized, and accurate and highly reliable good / bad diagnosis and fault determination of the plasticizing state can be performed.

[0014] (2) According to a preferred method, when implementing the plasticizing state diagnosis method, the respective thresholds L for detecting the onset number data Da and the event count data De can be set to be the same or different. Therefore, flexible and optimal thresholds L corresponding to the onset number data Da and the event count data De can be set, and accurate onset number data Da and event count data De for the AE wave We can be obtained.

[0015] (3) According to a preferred method, when implementing the plasticizing state diagnosis method, for the detection signals obtained from the AE sensors 6r and 6f, if signals other than those generated by the heating cylinder 2 during the plasticizing process and mixed therein are treated as noise components Np... for noise removal processing, then ambient environmental noise, i.e., useless noise components Np... (interference) other than the AE wave signals Sre and Sfe accompanying the plasticization of the molding material R, can be excluded. Therefore, more accurate AE wave signals Sre and Sfe can be obtained.

[0016] (4) According to a preferred method, when implementing the plasticizing state diagnosis method, for the detection signals obtained from the AE sensors 6r and 6f, if filtering processing that only allows a set specific frequency Bs or a set specific frequency band to pass is performed, then the AE wave signals Sre and Sfe obtained along with the plasticization of the molding material R can be determined and detected. Specifically, the AE wave We when the molding material R is broken and the AE wave We when the molding material R collides with metal can be determined and detected. Therefore, the plasticizing state and the fault occurrence state can be diagnosed more accurately.

[0017] (5) According to a preferred mode, when constructing the graphic display unit 8, if the generation pattern Ps of the starting tone number data Da… and the event count data De… with respect to the position data Dx… is displayed in a chart form, the graphic display can be performed by combining general charts such as bar charts and line charts. Therefore, it is possible to easily and quickly grasp the plasticization state and the failure occurrence state based on the generated generation pattern Ps.

[0018] (6) According to a preferred mode, when arranging the AE sensors 6r, 6f, they are composed of the first AE sensor 6r and the second AE sensor 6f. Thus, if the first AE sensor 6r is arranged at the rear side of the heating cylinder 2 and the second AE sensor 6f is arranged at the front side of the heating cylinder 2, a series of states from the solid state such as particles near the material supply unit 4 to the plasticized molten state can be taken as the detection object. Therefore, it is possible to grasp the plasticization state in the heating cylinder 2 in a sufficient and optimal state.

[0019] (7) According to a preferred mode, when arranging the AE sensors 6r, 6f, if they are installed separately with respect to the heating cylinder 2, the installation positions can be flexibly selected. For example, they can be arranged without interfering with other temperature sensors or other functions, etc. Therefore, the degree of freedom of arrangement can be improved, the complexity around the heating cylinder 2 can be avoided, and the space occupancy efficiency can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a structural diagram of an injection device in an injection molding machine having a plasticization state diagnosis device according to a preferred embodiment of the present invention.

[0021] Figure 2 is a functional block diagram showing the overall structure (system) of the plasticization state diagnosis device.

[0022] Figure 3 is an external perspective view showing the state where the AE sensor included in the plasticization state diagnosis device is installed on the heating cylinder.

[0023] Figure 4 is a main sectional view showing the state where the AE sensor included in the plasticization state diagnosis device is installed on the heating cylinder.

[0024] Figure 5 is a perspective view showing the internal structure of the installation mechanism of the AE sensor included in the plasticization state diagnosis device by breaking.

[0025] Figure 6 is a flowchart showing the processing steps of the plasticization state diagnosis method according to a preferred embodiment of the present invention.

[0026] Figure 7It is a signal waveform diagram for explaining a method of obtaining a generation position from an AE wave signal obtained from the plasticizing state diagnosis device.

[0027] Figure 8 It is a signal waveform diagram for explaining a method of obtaining the onset number and event count from an AE wave signal obtained from the plasticizing state diagnosis device.

[0028] Figure 9 It is a display screen diagram of the graphic display unit included in the plasticizing state diagnosis device.

[0029] Figure 10 It is a display screen diagram showing an example of a generation pattern displayed by the graphic display unit.

[0030] Figure 11 It is a display screen diagram showing another example of a generation pattern displayed by the graphic display unit.

[0031] Figure 12 It is a display screen diagram showing yet another example of a generation pattern displayed by the graphic display unit.

[0032] Figure 13 It is a display screen diagram showing still another example of a generation pattern displayed by the graphic display unit.

[0033] Reference Numeral Explanation

[0034] 1: Plasticizing state diagnosis device; 2: Heating cylinder; 3f…: Heating unit; 4: Material supply unit; 5: Screw; 6r: AE sensor (first AE sensor); 6f: AE sensor (second AE sensor); 7: Data processing unit; 8: Graphic display unit; 9: Temperature sensor; M: Injection molding machine; R: Molding material; Fs: Front-rear direction; Xr: Position of heating cylinder; Xf: Position of heating cylinder; We: AE wave; tr: Arrival time; tf: Arrival time; Sre: AE wave signal; Sfe: AE wave signal; L: Threshold value; Ps: Generation pattern; Ex: Position calculation processing unit; Ea: Onset number calculation processing unit; Ee: Event count calculation processing unit. Detailed Description of the Preferred Embodiment

[0035] Next, preferred embodiments of the present invention will be listed and described in detail with reference to the drawings.

[0036] First, with reference to Figure 1 the overall schematic structure of the injection molding machine M having the plasticizing state diagnosis device 1 of the present embodiment will be described.

[0037] The injection molding machine M includes Figure 1The injection device Mi shown and the mold clamping device whose illustration is omitted. The injection device Mi is arranged on the upper surface of the movable table 21 that can be moved in the front-rear direction Fs by contacting the nozzle with the driving part. 22 is a front support disk part fixed to the upper surface of the front part of the movable table 21, 23 is a rear support disk part fixed to the upper surface of the rear part of the movable table 21, and four guide shafts 24 are erected between the front support disk part 22 and the rear support disk part 23…, and a sliding unit 25 is mounted on the guide shafts 24… in a slidable manner.

[0038] In addition, by installing the rear end of the heating cylinder 2 on the front surface of the front support disk part 22, the front side of the heating cylinder 2 protrudes forward. The heating cylinder 2 has an injection nozzle 2n at the front end and a hopper 2h at the upper end of the rear part. The lower end supply port of the hopper 2h communicates with the inside of the heating cylinder 2 via the material supply path 26 in the vertical direction, and the material supply part 4 is constituted by the material supply path 26 and the hopper 2h. Moreover, on the outer peripheral surface of the heating cylinder 2 including the injection nozzle 2n, a plurality of heating parts 3f, 3m, 3r using a belt heater for heating the heating cylinder 2 are attached in sequence from the front side to the rear side in the front-rear direction Fs. Each heating part 3f… is attached independently, and a plurality of temperature sensors 9… for detecting the heating temperature of each heating area are attached, and feedback control of the heating temperature is performed by the molding machine controller 41.

[0039] A screw 5 is inserted through the inside of the heating cylinder 2, and the rear end side of the screw 5 reaches the rear of the front support disk part 22 through the opening provided in the front support disk part 22. In addition, a driven pulley 27f is rotatably mounted on the front surface part of the sliding unit 25, and the rear end of the screw 5 is coupled to the center position of the driven pulley 27f. Further, a servo motor 28 for rotating the screw is fixed to the upper surface part of the sliding unit 25. Moreover, a driving pulley 27d is fixed to the rotating shaft of the servo motor 28, and a timing belt 27b is erected between the driving pulley 27d and the driven pulley 27f to constitute a rotation transmission mechanism. A rotary encoder 30 for detecting the rotation (rotation speed) of the servo motor 28 is attached to the servo motor 28.

[0040] On the other hand, a servo motor 31 for advancing and retreating the screw is fixed to the rear surface of the rear support disk part 23. In addition, the rear end of the threaded part 32s constituting the ball screw mechanism 32 is rotatably mounted on the front surface of the rear support disk part 23, and the rotating shaft of the servo motor 31 is coupled to the rear end of the threaded part 32s. A rotary encoder 33 for detecting the rotation (rotation speed) of the servo motor 31 is attached to the servo motor 31. Moreover, the front end of the nut part 32n constituting the ball screw mechanism 32 is fixed to the rear surface part of the sliding unit 25, and the front end side of the threaded part 32s is screwed with the nut part 32n.

[0041] On the other hand, 41 is a molding machine controller that controls the overall operation of the injection molding machine M. It has hardware such as a CPU and a memory, and has a computer function that includes a processing program (software) for executing various control processes including various arithmetic processes and timing control. Therefore, the above-mentioned servo motors 28 and 31 and each heating unit 3f... are connected to the output side ports of the molding machine controller 41, and the above-mentioned rotary encoders 30 and 33 and the temperature sensors 9... attached corresponding to each heating unit 3f... are connected to the input side ports of the molding machine controller 41. The above is the basic structure of the injection device Mi.

[0042] Next, with reference to Figures 1-5 and Figure 9 the structure of the plasticizing state diagnosis device 1 of the present embodiment will be specifically described.

[0043] As Figure 3 ( Figures 1-2 ) shows, the plasticizing state diagnosis device 1 has a plurality of AE sensors (acoustic emission wave sensing sensors) 6r... using piezoelectric ceramic elements, etc. The plurality of AE sensors 6r... are arranged at different positions Xr... in the front-rear direction Fs of the heating cylinder 2 and detect AE (acoustic emission) waves We.

[0044] As an example, two AE sensors 6r... including a first AE sensor 6r arranged at two positions Xr and Xf and a second AE sensor 6f are exemplified. In this case, as Figure 3 shown, the first AE sensor 6r is arranged at a position Xr at the rear end of the heating unit 3r near the rear side of the heating cylinder 2, and the second AE sensor 6f is arranged at a position Xf in front of the heating unit 3m near the middle of the front side of the heating cylinder 2.

[0045] In this way, when arranging the AE sensors 6r and 6f, if the first AE sensor 6r is arranged at the rear side of the heating cylinder 2 and the second AE sensor 6f is arranged at the front side of the heating cylinder 2, a series of states from the solid state such as particles near the material supply unit 4 to the molten state after plasticization can be used as the detection object. Therefore, the plasticizing state in the heating cylinder 2 can be grasped in a sufficient and optimal state.

[0046] Figure 5The AE sensor unit 6u that houses the sensor body 6rm in the AE sensor 6r (the same applies to the AE sensor 6f) is shown. This AE sensor unit 6u has a sensor holder 52 configured in a cylindrical shape. Inside the sensor holder 52, a cylindrical sensor body 6rm is disposed on the lower side. The connection lead 6rc of the sensor body 6rm is led out from the circumferential surface of the sensor holder 52 to the outside. Additionally, the sensing surface 6rms, which is the lower end surface of the sensor body 6rm, faces the outside from the lower end surface of the sensor holder 52. On the other hand, a plunger 53 is disposed inside the sensor holder 52 on the upper side so as to be displaceable in the axial direction, and a helical spring 54 that applies a downward force (towards the sensor body 6rm side) to the plunger 53 is attached. Thus, the sensor body 6rm is fixed by the pressing of the front end of the plunger 53, enabling stable measurement. Also, an alumina sheet 55u is sandwiched between the front end of the plunger 53 and the upper end surface of the sensor body 6rm, and an alumina sheet 55d is attached to the lower end surface of the sensor body 6rm. Thereby, reduction of electrical noise is achieved.

[0047] In addition, the installation of the AE sensor 6r (the same applies to the AE sensor 6f) with respect to the heating cylinder 2 can be performed as Figure 4 and Figure 6 shown. In this case, as Figure 4 shown, mounting threaded holes 56 are formed in the radial direction of the heating cylinder 2 at specified positions in the empty space on the circumferential surface of the heating cylinder 2, and a waveguide rod 57 is screwed and fixed in the mounting threaded holes 56. Moreover, the front end, that is, the inner end surface 57i of the waveguide rod 57 is made to coincide with the inner wall surface of the heating cylinder 2, and the lower end surface of the above-mentioned AE sensor unit 6u is mounted and fixed to the rear end surface of the waveguide rod 57. At this time, the above-mentioned alumina sheet 55d is interposed between the lower end surface of the sensor body 6rm and the outer end surface of the waveguide rod 57.

[0048] In this way, as long as it is installed separately with respect to the heating cylinder 2, the installation position can be flexibly selected. For example, it can be installed without interfering with other temperature sensors or other functions, etc. Therefore, the installation degree of freedom can be improved, the complexity around the heating cylinder 2 can be avoided, and the space occupancy efficiency can be improved.

[0049] Moreover, as Figure 2 shown, the first AE sensor 6r and the second AE sensor 6f are respectively connected to the sensor ports of the controller body 42 in the molding machine controller 41 via preamplifiers 43r, 43f, and the above-mentioned respective temperature sensors 9... are also respectively connected to the sensor ports of the controller body 42. The controller body 42 incorporates hardware such as a CPU and functions as the main part of a computer system that performs various arithmetic processes and various control processes, etc.

[0050] In addition, although the case where the molding machine controller 41 is used is illustrated, another high-speed processing computer may be prepared, and the outputs of the first AE sensor 6r and the second AE sensor 6f may be given to the high-speed processing computer, whereby necessary analysis processing is performed using another processing system.

[0051] In addition, the internal memory 42m includes a program area 42mp that stores various processing programs (software) for performing various arithmetic processes and various control processes (sequential control), and a data area 42md that can store various data (database) types. In particular, the program area 42mp includes a diagnostic processing program for implementing the plasticizing state diagnosis method of the present embodiment.

[0052] Thus, the molding machine controller 41 including the internal memory 42m and the controller main body 42 functions as the main part of the plasticizing state diagnosis device 1. That is, as Figure 2 shown, it functions as a data processing unit 7 that performs data processing on the AE wave signals Sre and Sfe obtained from the respective AE sensors 6r and 6f. That is, through the diagnostic processing program, it functions as a data processing unit 7 having a position arithmetic processing unit Ex, a starting number arithmetic processing unit Ea, and an event counting arithmetic processing unit Ee. The position arithmetic processing unit Ex obtains position data Dx related to the generation position of the AE wave We based on the arrival time of the AE wave We obtained from the respective AE sensors 6r and 6f. The starting number arithmetic processing unit Ea obtains the starting number data Da... as the number of times the AE wave signals Sre and Sfe related to the AE wave We generated according to each specified sampling period Tp and specified position data Dx... exceed a preset threshold value L. The event counting arithmetic processing unit Ee obtains the event counting data De... as the number of AE wave components Sp... that exceed a preset threshold value L.

[0053] Moreover, a display 42d is attached to the controller main body 42. The display 42d has a display main body 42dm and a touch panel 42dt attached to the display main body 42dm. Therefore, various setting operations and selection operations can be performed through the touch panel 42dt. The display 42d constitutes a graphic display unit 8 that graphically displays at least the generation pattern Ps of the starting number data Da... and the event counting data De... with respect to the position data Dx....

[0054] Figure 9 An example of the display screen 61 of the display 42d including the graphic display unit 8 is shown. The display screen 61 has a screen structure in which a setting unit 8s is displayed on the upper side of the screen and the graphic display unit 8 is displayed on the lower side of the screen.

[0055] In this case, the setting unit 8s includes a threshold setting unit 62 that sets a threshold L, a total range setting unit 63 that sets a total range, a data display unit 64 that displays various data values, etc., a switching key 65, etc. In the threshold setting unit 62, it is possible to set respective thresholds L for each AE wave signal Sre, Sfe obtained from the AE sensors 6r, 6f (refer to Figure 8 ). At this time, the respective thresholds L can be set to be the same or different. Thus, since the respective thresholds L can be set to be the same or different, it is possible to perform highly flexible and reliable detection of the AE wave We corresponding to different installation positions of the respective AE sensors 6r, 6f.

[0056] In addition, in the threshold setting unit 62, it is possible to set respective thresholds L for the detection start sound number data Da and the event count data De. During setting, display switching can be performed by the switching key 65. In this case, the respective thresholds L can be set to be the same or different. Thus, since the respective thresholds L can be set to be the same or different, it is possible to set flexible and optimal thresholds L corresponding to the start sound number data Da and the event count data De respectively, and accurate start sound number data Da and event count data De for the AE wave We can be obtained.

[0057] Furthermore, in the total range setting unit 63, for example, the sampling period Tp can be set by "0" to "10" (10 [seconds] time), etc. In addition, in the data display unit 64, set values and operation values such as the band-pass frequency (frequency band) during filtering processing, the event count value, and the start sound value can be displayed, and various display functions and various setting functions can be switched by using the switching key 65.

[0058] On the other hand, the graphic display unit 8 has at least a function of graphically displaying the generation pattern Ps of the start sound number data Da and the event count data De with respect to the position data Dx. The exemplified graphic display unit 8 has the position data Dx in the front-back direction Fs in the heating cylinder 2 as a scale on the horizontal axis, and the event count data De and the start sound number data Da as scales on the vertical axis, and thus can be displayed in the form of a graph. Specifically, the start sound number data Da is displayed by a bar graph Ga..., and the event count data De is displayed by a line graph Gs....

[0059] Thus, when constructing the graphic display unit 8, if the generation pattern Ps of the start sound number data Da... and the event count data De... with respect to the position data Dx... is displayed in the form of a graph, graphic display can be performed by a combination of general graphs such as a bar graph and a line graph, and thus it is possible to easily and quickly grasp the plasticization state and the fault occurrence state based on the generated generation pattern Ps.

[0060] In addition, the methods for obtaining the exemplified position data Dx, the attack count data Da, and the event count data De will be specifically described together with the processing steps of the plasticizing state diagnosis method described later.

[0061] On the other hand, the output port of the controller main body 42 is connected to the above-mentioned screw rotation servo motor 28 via a motor driver (servo amplifier) 45, and the rotation speed (rotational speed) of the screw rotation servo motor 28 is detected by a rotary encoder 30, and the detected rotation speed signal is given to the motor driver 45 and the controller main body 42. In addition, each belt heater in the above-mentioned heating units 3f, 3m, and 3r is connected to the output port of the controller main body 42 via a heater driver 46.

[0062] Next, with reference to Figures 1-5 and Figures 7-13 , according to Figure 6 The operation (function) of the plasticizing state diagnosis device 1 of the present embodiment including the operation of the injection device Mi in the injection molding machine M, that is, the plasticizing state diagnosis method, will be described with reference to the flowchart shown.

[0063] First, various setting processes (step S1) required for implementing the plasticizing state diagnosis method are performed using the setting unit 8s in the display screen 61 of the display 42d shown in Figure 9 .

[0064] Specifically, the threshold setting unit 62 sets a threshold L for the AE wave signal Sre obtained from the first AE sensor 6r displayed on CH1, and sets a threshold L for the AE wave signal Sfe obtained from the second AE sensor 6f displayed on CH2. Each threshold L... can be the same or different. In addition, a threshold L can be set only for either CH1 or CH2. In the exemplified Figure 8 case, it is set to about 0.2 [V].

[0065] In addition, the sampling period Ts is set by the total interval setting unit 63. In the exemplified case, it is set to about 10 [seconds]. Next, by selecting the display setting screen using the switching key 65, setting processes for various set values such as the band-pass frequency of the band-pass filter (for example, 20 - 80 [kHz] (plastic destruction), etc.) and the on / off of the noise cancellation waveform (for example, a registered waveform measured in advance) can be performed.

[0066] If the setting process ends, the operation of the injection molding machine M, i.e., the molding process, starts (step S2). The molding machine controller 41 monitors the molding process during the operation of the injection molding machine M. If the plasticizing process starts, the controller main body 42 performs an acquisition process of detection signals based on the AE waves We obtained from each of the AE sensors 6r, 6f (steps S3, S4). In this case, the detection signals obtained from each of the AE sensors 6r, 6f are given to the controller main body 42 after being amplified by the preamplifiers 43r, 43f respectively (step S5).

[0067] In the controller main body 42, noise removal processing is performed on the amplified detection signals (step S6). The noise removal processing removes the noise component Np that has no relevance to the plasticizing state in the heating cylinder 2. In this case, the preset noise frequency components can be removed, or the operation sound of the injection molding machine M can be measured in advance and registered as the noise component Np... to perform noise component elimination processing. Additionally, as needed, selection of the category related to the noise component Np or on / off switching can be performed.

[0068] In this way, for the detection signals obtained from the AE sensors 6r, 6f, if the signals mixed in other than the signals generated by the heating cylinder 2 during the plasticizing process are regarded as the noise component Np... and noise removal processing is performed, the surrounding environmental noise, i.e., the useless noise components Np... (interference) other than the AE wave signals Sre, Sfe accompanying the plasticizing of the molding material R, can be excluded, and thus more accurate AE wave signals Sre, Sfe can be obtained.

[0069] For the detection signals after the noise removal processing, filtering processing that allows only the set band-pass frequency Bs to pass is performed (step S7). Thereby, the detection signals related to specific frequencies Bs such as the frequency band (20 - 80 [kHz]) of the molding material R breaking and the frequency band (200 - 350 [kHz]) of metal collision can be extracted. In the illustrated case, it is set by the band-pass frequency Bs, but it can also be set as a band-pass frequency band having a specified bandwidth.

[0070] In this way, if filtering processing that allows only the set specific frequency Bs or the set specific frequency band to pass is performed on the detection signals obtained from the AE sensors 6r, 6f, the AE wave signals Sre, Sfe obtained along with the plasticizing of the molding material R can be determined and detected. Specifically, the AE wave We when the molding material R breaks and the AE wave We when the molding material R collides with metal can be determined and detected, and thus the plasticizing state and the failure occurrence state can be diagnosed more accurately.

[0071] Figure 7 and Figure 8The signal waveforms of the AE wave signals Sre and Sfe that have undergone noise removal processing and filtering processing are shown. By switching the above-described switching key 65, the signal waveforms can be displayed on other screens (Steps S8 and S9).

[0072] In addition, since the detection signal after the filtering processing functions as the AE wave signals Sre and Sfe, Figure 2 the arithmetic processing related to the diagnostic data processing is performed by the data processing unit 7 shown (Step S10). In this case, it is performed within the sampling period Ts (10 [seconds] period in the illustrated case) set by the total interval setting unit 63.

[0073] Currently, assume a case where an AE wave We with a relatively large amplitude exceeding the threshold L is generated during the sampling period Ts. Figure 8 In this case, first, the onset number arithmetic processing unit Ea performs onset number arithmetic processing (Step S11). That is, the magnitude of the amplitude of the AE wave signal Sre (Sfe) is determined by the threshold L, and when it exceeds the threshold L, it is determined that an onset has occurred, and it becomes the onset number data Da of "1" time.

[0074] Next, the event counting arithmetic processing unit Ee counts the number of waveform components Sp... that exceed the threshold L, and performs event counting arithmetic processing to obtain the event counting data De (Step S12). Then, the counted number becomes the event counting data De.

[0075] Next, based on the obtained AE wave signals Sre and Sfe, the position data Dx is calculated by the position arithmetic processing unit Ex (Step S13). In the position arithmetic processing unit Ex, the position data Dx related to the generation position of the AE wave We is obtained based on the arrival times tr and tf of the AE wave We obtained from each AE sensor 6r and 6f. That is, as Figure 7 shown, between the AE wave signals Sre and Sfe obtained from each AE sensor 6r and 6f, a time difference Δt based on the delay occurs in the arrival times tr and tf. Therefore, based on the installation positions Xr and Xf of each AE sensor 6r and 6f, the time difference Δt, and the sound velocity, the generation position of the AE wave We is obtained as the position data Dx. In addition, the longitudinal frequency of iron is used as the sound velocity.

[0076] Through these series of data processes, the onset number data Da, event count data De, and position data Dx are correlated with each other, and thus are temporarily registered in the correlated state. The above is the data process in the case where one onset has occurred. After that, in the case where the next onset occurs during the sampling period Ts, the onset number data Da, event count data De, and position data Dx are also obtained through the same processing steps (steps S14, S10...). These series of data processes are performed until the set sampling period Ts ends.

[0077] Then, if the sampling period Ts ends, total processing of the correlated onset number data Da..., event count data De..., and position data Dx... during the sampling period Ts is performed (step S15). In addition, as Figure 9 shown, the onset number data Da..., event count data De..., and position data Dx... after the total processing are graphically displayed by the graphic display unit 8 (step S16).

[0078] The illustrated graphic display is shown in the form of a chart. On the horizontal axis, position ranges are sequentially set at intervals of, for example, 20 [mm] in the front-rear direction Fs of the heating cylinder 2. In the case where there is position data Dx included in the position range, the total value of the onset number data Da... corresponding to the position data Dx is displayed using the bar graph Ga, and the total value of the event count data De... is displayed using the line graph Gs.

[0079] Thereby, the generated pattern Ps based on the bar graph Ga and the line graph Gs is displayed. The display of the generated pattern Ps can be subjected to prescribed diagnostic processing including the quality of the plasticization state and the like by the operator or AI (artificial intelligence) (step S17).

[0080] Figures 10-13 Examples of various generated patterns Ps are shown. In this case, Figure 10 and Figure 11 show the generated pattern Ps in the case where "GPPS (general purpose polystyrene) resin" is used in the molding material R and the band-pass frequency Bs is set to 50 - 60 [kHz], Figure 10 shows the case where the heating temperature is set to "low temperature 170 [°C]", on the other hand, Figure 11 shows the case where the heating temperature is set to "appropriate temperature 200 [°C]".

[0081] The 50 - 60 [kHz] set as the band-pass frequency Bs becomes the frequency at which plastic destruction is envisaged. From the generated patterns Ps shown in Figure 10 and Figure 11 it can be seen that in Figure 11Among them, at the initial stage of plasticization, the start number data Da and the event count data De temporarily increase, indicating a normal plasticization state. In contrast, Figure 10 it can be confirmed that the generation numbers of the start number data Da and the event count data De increase, and it also occurs in a large range in the front-rear direction Fs of the heating cylinder 2, especially near the front end of the heating cylinder 2, etc., and it is in a state of insufficient plasticization.

[0082] In addition, in Figure 12 the case of, the basic conditions are the same as those in Figure 11 the case of, but it shows the generation pattern Ps when the heating temperature is set to "high temperature 240 [°C]". It can be known from Figure 12 that compared with the case of "appropriate temperature 200 [°C]" shown in Figure 11 , it can be confirmed that the plasticization state is not much different.

[0083] Next, in Figure 13 the case of, the basic conditions are the same as those in Figure 11 the case of, but it shows the case where the band-pass frequency Bs is set to 220 [kHz]. The frequency range of 200 - 350 [kHz] of the set frequency is the frequency assumed to be generated due to metal contact. It can be known from Figure 13 that although the unmolten molding material R contacts the screw 5 at the rear of the heating cylinder 2 to generate the start number data Da and the event count data De, it can be confirmed that almost no generation occurs thereafter, so it can be confirmed that the plasticization state is normal.

[0084] In this way, it can be confirmed that the generation pattern Ps graphically displayed by the graphic display unit 8 can reflect the plasticization state as a pattern. Therefore, the operator or AI can perform diagnostic processing such as whether a failure occurs based on the quality of the plasticization state and the generation of abnormal sounds, and by further accumulating and learning the generation pattern Ps... as big data, the diagnostic accuracy can be further improved.

[0085] This diagnostic result can be displayed on the display screen of the display 42d as a diagnostic result of the quality of the plasticization state or an abnormal generation result, etc., or output as a control instruction for required stop control and operation control (step S18).

[0086] Therefore, the plasticizing state diagnosis device 1 (plasticizing state diagnosis method) of the injection molding machine M according to the present embodiment basically includes: a plurality of AE sensors 6r, 6f disposed at different positions Xr, Xf in the front-back direction Fs in the heating cylinder 2 and detecting AE waves We; a data processing unit 7 having a position arithmetic processing unit Ex, a starting number arithmetic processing unit Ea, and an event counting arithmetic processing unit Ee. The position arithmetic processing unit Ex obtains position data Dx related to the generation position of the AE wave We based on the arrival times tr, tf of the AE waves We obtained from the respective AE sensors 6r, 6f. The starting number arithmetic processing unit Ea obtains the starting number data Da... by taking the number of occurrences of the AE wave signals Sre, Sfe related to the AE waves We generated according to each specified sampling period Tp and specified position data Dx... that exceed a preset threshold L. The event counting arithmetic processing unit Ee obtains the event counting data De... by taking the number of AE wave components Sp... that exceed a preset threshold L. And a graphic display unit 8 that graphically displays at least the generation pattern Ps of the starting number data Da... and the event counting data De... with respect to the position data Dx.... Therefore, it is possible to accurately obtain information on which part of the heating cylinder 2 the AE wave We is generated, what causes the AE wave We, etc., from a comprehensive (stereoscopic) and even qualitative perspective of the heating cylinder 2. Thus, a more practical plasticizing state diagnosis device 1 with excellent convenience and usability can be realized, and accurate and highly reliable good / bad diagnosis and fault determination of the plasticizing state can be performed.

[0087] As described above, the preferred embodiments have been described in detail, but the present invention is not limited to such embodiments, and can be arbitrarily changed, added, or deleted within the scope not departing from the gist of the present invention in terms of the structure, shape, quantity, etc. of the detailed parts.

[0088] For example, the case where the AE sensors 6r, 6f are disposed at two positions, the rear side and the front side of the heating cylinder 2, is shown. Generally, however, the AE sensors 6r... can be disposed at two or more different positions respectively. In addition, the rear side and the front side of the heating cylinder 2 where the AE sensors 6r, 6f are disposed represent a relative positional relationship and do not represent an absolute position. Therefore, the position on the front side means that it exists on the front side relative to the position on the rear side, and as an absolute position, it does not mean that it exists in the front part of the heating cylinder 2, and it can also exist in the middle part or the rear part of the heating cylinder 2. On the other hand, noise removal processing and filtering processing are preferably performed, but they are not essential components. In addition, the graphic display unit 8 preferably displays the generation pattern Ps of the starting number data Da... and the event counting data De... with respect to the position data Dx... in the form of a chart, but as long as the generation pattern Ps can be grasped by graphic display, it can be implemented in various graphic forms other than the chart form.

[0089] Industrial Applicability

[0090] The plasticization state diagnosis method and apparatus of the present invention can be used for various injection molding machines that plasticize a molding material supplied into the interior of a heating cylinder by the rotation of a screw.

Claims

1. A method for diagnosing the plasticizing state of an injection molding machine, which diagnoses the plasticizing state of a molding material when the molding material supplied from a material supply unit provided at the rear of a heating cylinder heated by a heating unit is plasticized by the rotation of a screw, characterized in that a plurality of acoustic emission wave sensing sensors for detecting acoustic emission waves are arranged at different positions in the front-rear direction in the heating cylinder, position data related to the generation position of the acoustic emission wave is obtained based on the arrival time of the acoustic emission waves obtained from each acoustic emission wave sensing sensor, and the number of occurrences where the acoustic emission wave signal related to the acoustic emission wave generated during each specified sampling period and the specified position data exceeds a preset threshold is obtained as the onset number data, and the number of the acoustic emission wave components exceeding the preset threshold is obtained as the event count data, and at least the generation patterns of the onset number data and the event count data with respect to the position data are graphically displayed.

2. The method for diagnosing the plasticizing state of an injection molding machine according to claim 1, characterized in that the thresholds for detecting the onset number data and the event count data are set to be the same.

3. The method for diagnosing the plasticizing state of an injection molding machine according to claim 1, characterized in that the thresholds for detecting the onset number data and the event count data are set to be different.

4. The method for diagnosing the plasticizing state of an injection molding machine according to claim 1, characterized in that for the detection signal obtained from the acoustic emission wave sensing sensor, noise removal processing is performed on the signals mixed and existing other than the signals generated by the heating cylinder during the plasticizing process as noise components.

5. The method for diagnosing the plasticizing state of an injection molding machine according to claim 1, characterized in that filtering processing that allows only a set specific frequency to pass is performed on the detection signal from the acoustic emission wave sensing sensor.

6. The method for diagnosing the plasticizing state of an injection molding machine according to claim 1, characterized in that filtering processing that allows only a set specific frequency band to pass is performed on the detection signal from the acoustic emission wave sensing sensor.

7. A device for diagnosing the plasticizing state of an injection molding machine, which diagnoses the plasticizing state of a molding material when the molding material supplied from a material supply unit provided at the rear of a heating cylinder heated by a heating unit is plasticized by the rotation of a screw, characterized in that the device for diagnosing the plasticizing state of the injection molding machine has: a plurality of acoustic emission wave sensing sensors, which are arranged at different positions in the front-rear direction in the heating cylinder and detect acoustic emission waves; A data processing unit, which has a position operation processing unit, a starting number operation processing unit, and an event count operation processing unit. The position operation processing unit calculates position data related to the generation position of the acoustic emission wave based on the arrival time of the acoustic emission wave obtained from each acoustic emission wave sensing sensor. The starting number operation processing unit calculates the number of times the acoustic emission wave signal related to the acoustic emission wave generated according to each specified sampling period and the specified position data exceeds a preset threshold as starting number data. The event count operation processing unit calculates the number of the acoustic emission wave components exceeding a preset threshold as event count data; and A graphic display unit, which at least graphically displays the generation patterns of the starting number data and the event count data with respect to the position data.

8. The plasticizing state diagnosis device of an injection molding machine according to claim 7, characterized in that the graphic display unit displays the generation patterns of the starting number data and the event count data with respect to the position data in the form of a chart.

9. The plasticizing state diagnosis device of an injection molding machine according to claim 7, characterized in that the acoustic emission wave sensing sensor has a first acoustic emission wave sensing sensor and a second acoustic emission wave sensing sensor. The first acoustic emission wave sensing sensor is disposed at the rear side of the heating cylinder, and the second acoustic emission wave sensing sensor is disposed at the front side of the heating cylinder.

10. The plasticizing state diagnosis device of an injection molding machine according to claim 9, characterized in that the acoustic emission wave sensing sensor is separately installed with respect to the heating cylinder.

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