Plasticization state diagnostic device for injection molding machines

Abstract

To achieve compactness while avoiding complexity by optimizing space utilization in limited installation areas, by reducing manufacturing man-hours and costs.SOLUTION: In constituting a plasticizing state diagnostic device 1 for an injection molding machine M, which diagnoses the plasticizing state of molding material R supplied from a material supply section 4 provided at the rear of a heating cylinder 2 heated by a heating section 3f and plasticized within said heating cylinder 2 by rotation of a screw 5, the device comprises an AE sensor 6 integrally provided with a temperature sensor 9 mounted on the heating cylinder 2 to detect the heating temperature of said heating cylinder 2, and a diagnostic processing unit 7 that diagnoses the plasticization state of the molding material R based on the detection results of the AE sensor 6.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a plasticization state diagnosis device for an injection molding machine suitable for use when plasticizing a molding material supplied into 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 into the heating cylinder from a material supply part provided at the rear part of the heating cylinder heated by a heating part by the rotation of a screw. Therefore, accurately grasping the plasticization state of the molding material in the heating cylinder is important from the viewpoint of avoiding the occurrence of molding defects and ensuring high molding quality, and various monitoring devices for grasping the plasticization state have also been proposed.

[0003] Conventionally, as this type of monitoring device, there is already known a material monitoring device for an injection molding machine described in Patent Document 1 proposed by the present applicant. The material monitoring device described in Patent Document 1 aims to quickly investigate the cause of a poor melting state and take countermeasures, and to avoid plasticization failure in advance and realize an ideal plasticization process. Specifically, it senses an acoustic emission wave generated when a molding material supplied into the heating cylinder from a material supply part provided at the rear part of the heating cylinder heated by a plurality of heating parts including a post-heating part for heating the rear part of the heating cylinder is deformed or sheared inside the heating cylinder by the rotation of a screw and converts it into an electrical signal, an acoustic emission detection part for detecting quantitative acoustic emission data related to the deformation or shearing of the molding material from the electrical signal, and a material countermeasure processing functional part for performing a predetermined material countermeasure process based on the use of this acoustic emission data.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] However, the material monitoring device described in Patent Document 1 mentioned above also had the following problems that needed to be solved.

[0006] In other words, by using an acoustic emission wave sensing sensor (AE sensor) that is placed at the rear of the heating cylinder, it is possible to detect acoustic emission waves generated when the molding material is deformed or sheared inside the heating cylinder and convert them into electrical signals. While this has the advantage of being able to detect quantitative acoustic emission data related to the deformation or shearing of the molding material from these electrical signals, it has the drawback that, because the detection is quantitative and localized, it is not necessarily sufficient from the standpoint of obtaining more specific and practical information, such as where in the heating cylinder the sound is being generated or what is causing the sound.

[0007] Therefore, there was room for further improvement in order to secure plasticization information from a planar (three-dimensional) and qualitative perspective regarding the heating cylinder, and to realize a more practical, convenient, and user-friendly monitoring device (plasticization state diagnostic device).

[0008] The present invention aims to provide a plasticization state diagnostic device for injection molding machines that solves the problems present in the background technology described above. [Means for solving the problem]

[0009] To solve the above-mentioned problems, the present invention provides a plasticization state diagnostic device 1 for an injection molding machine M that diagnoses the plasticization state of a molding material when the molding material R supplied to the inside of the heating cylinder 2 from a material supply unit 4 located at the rear of the heating cylinder 2, which is heated by a heating unit 3f..., is plasticized by the rotation of a screw 5. The device comprises a temperature sensor 9 that detects the heating temperature of the heating cylinder 2 by having a sensor mounting part 11 attached to the outer circumferential surface 2x of the heating cylinder 2; an AE sensor 6 that detects an AE wave We integrally provided with the temperature sensor 9 by inserting the tip 11ms of a waveguide rod 11m into an insertion hole 11h formed on the side surface of the sensor mounting part 11; and a diagnostic processing unit 7 that diagnoses the plasticization state of the molding material R based on the detection result of the AE sensor 6.

[0010] Furthermore, in a preferred embodiment of the present invention, the AE sensor 6 may be provided with a first AE sensor 6r and a second AE sensor 6f, the first AE sensor 6r being positioned at a first position Xr behind the heating cylinder 2, and the second AE sensor 6f being positioned at a second position Xf in front of the first position Xr. On the other hand, the diagnostic processing unit 7 may be provided with a data processing unit 7 having a position calculation processing unit Ex which calculates position data Dx related to the generation position of the AE wave We based on the arrival times tf and tr of the AE wave We obtained from each AE sensor 6f and 6r, an attack count calculation processing unit Ea which calculates the number of times the AE wave signals Sre and Sfe related to the AE wave We generated for each predetermined sampling period Tp and predetermined position data Dx... exceed a preset threshold L as attack count data Da..., and an event count calculation processing unit Ee which calculates the quantity of AE wave components Sp... that exceed a preset threshold L as event count data De.... Furthermore, the diagnostic processing unit 7 can be provided with a graphic display unit 8 that displays the occurrence patterns Ps of the attack count data Da... and event count data De... for the position data Dx... in graph format. [Effects of the Invention]

[0011] The plasticization state diagnostic device 1 for the injection molding machine M according to the present invention provides the following remarkable effects.

[0012] (1) The device includes an AE sensor 6 that detects AE waves We by being integrally provided with a temperature sensor 9 that detects the heating temperature of the heating cylinder 2 and is attached to the heating cylinder 2, and a diagnostic processing unit 7 that diagnoses the plasticization state of the molding material R based on the detection result of the AE sensor 6. As a result, the device can be miniaturized by saving space in the limited installation space by having multiple temperature sensors 9 arranged on the outer surface of the heating cylinder 2, and can also avoid complexity, as well as reduce manufacturing man-hours and manufacturing costs.

[0013] (2) The temperature sensor 9 is provided with a sensor mounting portion 11 that is attached to the outer surface 2x of the heating cylinder 2. An insertion hole portion 11h is formed on the side of the sensor mounting portion 11, and the tip 11ms of the waveguide rod 11m that supports the AE sensor 6 is inserted into this insertion hole portion 11h and attached. As a result, the sensor mounting portion 11 can be used as a single component that can be used for both attaching the AE sensor 6 and the temperature sensor 9. This ensures the integrity of the component and also contributes to improving positional accuracy.

[0014] (3) In a preferred embodiment, the AE sensor 6 is configured with a first AE sensor 6r and a second AE sensor 6f, with the first AE sensor 6r positioned at a first position Xr at the rear of the heating cylinder 2, and the second AE sensor 6f positioned at a second position Xf in the heating cylinder 2, which is in front of the first position Xr. This allows for the detection of precise positional information, such as where in the heating cylinder 2 the AE wave We was generated, and enables the detection of a series of states from a solid state such as pellets to a molten state after plasticization, thereby allowing for a sufficient and optimal understanding of the plasticization state inside the heating cylinder 2.

[0015] (4) In a preferred embodiment, when configuring the diagnostic processing unit 7, if a data processing unit 7 is provided that includes a position calculation processing unit Ex which calculates position data Dx related to the generation location of the AE wave We based on the arrival times tf and tr of the AE wave We obtained from each AE sensor 6f and 6r, an attack count calculation processing unit Ea which calculates the number of times the AE wave signals Sre and Sfe related to the AE wave We generated for each predetermined sampling period Tp and predetermined position data Dx... exceed a preset threshold L as attack count data Da..., and an event count calculation processing unit Ee which calculates the quantity of AE wave components Sp... that exceed a preset threshold L as event count data De..., then information from a planar (three-dimensional) perspective, as well as a qualitative perspective, regarding the heating cylinder 2, such as what caused the AE wave We, can be accurately obtained, making it possible to realize a more practical, convenient, and user-friendly plasticization state diagnostic device 1, and enabling accurate and reliable good / bad diagnosis and trouble determination of the plasticization state.

[0016] (5) In a preferred embodiment, if the diagnostic processing unit 7 is provided with a graphic display unit 8 that displays the occurrence patterns Ps of attack count data Da... and event count data De... for position data Dx... in graph format, then graphic display becomes possible using a combination of general-purpose graphs such as bar graphs and line graphs, and the plasticization state and trouble occurrence state can be easily and quickly grasped from the generated occurrence patterns Ps. [Brief explanation of the drawing]

[0017] [Figure 1] A cross-sectional diagram showing the mounting structure of an AE sensor and a temperature sensor included in a plasticization state diagnostic device according to a preferred embodiment of the present invention. [Figure 2] This is an external perspective view showing the AE sensor, which is part of the plasticization state diagnostic device, attached to the heating cylinder. [Figure 3] A functional block diagram showing the overall configuration (system) of the plasticization state diagnostic device. [Figure 4] A perspective view showing the AE sensor, which is part of the plasticization state diagnostic device, attached to the heating cylinder. [Figure 5] Perspective view showing the internal structure of the mounting mechanism of the AE sensor provided in the plasticization state diagnostic device by breaking, [Figure 6] Explanatory drawing of the mounting method of the AE sensor and the temperature sensor provided in the plasticization state diagnostic device, [Figure 7] Cross-sectional configuration diagram showing a modified example of the mounting structure of the AE sensor and the temperature sensor provided in the plasticization state diagnostic device. [Figure 8] Flowchart showing the processing procedure of the plasticization state diagnostic device using the plasticization state diagnostic device, [Figure 9] Signal waveform diagram for explaining the method of obtaining the generation position from the AE wave signal obtained from the plasticization state diagnostic device, [Figure 10] Signal waveform diagram for explaining the method of obtaining the attack number and the event count from the AE wave signal obtained from the plasticization state diagnostic device, [Figure 11] Display screen diagram of the graphic display unit provided in the plasticization state diagnostic device, [Figure 12] Display screen diagram showing an example of the generation pattern displayed by the graphic display unit, [Figure 13] Display screen diagram showing another example of the generation pattern displayed by the graphic display unit, [Figure 14] Display screen diagram showing another example of the generation pattern displayed by the graphic display unit, [Figure 15] Display screen diagram showing another example of the generation pattern displayed by the graphic display unit,

Mode for Carrying Out the Invention

[0018] Next, preferred embodiments according to the present invention will be given and described in detail based on the drawings.

[0019] First, the overall schematic configuration of the injection molding machine M provided with the plasticization state diagnostic device 1 according to the present embodiment will be described with reference to FIG. 2.

[0020] The injection molding machine M includes an injection device Mi shown in Figure 2 and a mold clamping device (not shown). The injection device Mi is mounted on the upper surface of a movable table 21 that can move in the front-rear direction Fs by a nozzle touch drive unit. 22 is a front support plate fixed to the front upper surface of the movable table 21, and 23 is a rear support plate fixed to the rear upper surface of the movable table 21. Four guide shafts 24... are installed between the front support plate 22 and the rear support plate 23, and slide units 25 are slidably mounted on these guide shafts 24....

[0021] Furthermore, the front of the heating cylinder 2 is made to protrude forward by attaching the rear end of the heating cylinder 2 to the front surface of the front support plate 22. The heating cylinder 2 is equipped with an injection nozzle 2n at its front end and a hopper 2h at its rear upper end. The lower supply port of the hopper 2h communicates with the inside of the heating cylinder 2 via a vertical material supply passage 26, and this material supply passage 26 and the hopper 2h constitute a material supply section 4. In addition, multiple heating sections 3f, 3m, and 3r, which use band heaters to heat the heating cylinder 2, are sequentially attached to the outer circumferential surface of the heating cylinder 2, from the front to the rear in the front-to-back direction Fs. Each heating section 3f... is attached independently, and multiple temperature sensors 9... are attached to detect the heating temperature of each heating zone, and feedback control of the heating temperature is performed by the molding machine controller 41.

[0022] A screw 5 is inserted inside the heating cylinder 2, and the rear end of the screw 5 extends to the rear of the front support plate 22 through an opening provided in the front support plate 22. A driven pulley 27f is rotatably mounted on the front of the slide unit 25, and the rear end of the screw 5 is coupled to the center of the driven pulley 27f. Furthermore, a servo motor 28 for rotating the screw is fixed to the upper surface of the slide unit 25. A drive pulley 27d is fixed to the rotating shaft of the servo motor 28, and a timing belt 27b is stretched between the drive pulley 27d and the driven pulley 27f to form a rotation transmission mechanism. The servo motor 28 is equipped with a rotary encoder 30 for detecting the rotation (speed) of the servo motor 28.

[0023] Meanwhile, a servo motor 31 for screw advancement and retraction is fixed to the rear surface of the rear support plate 23. The rear end of the threaded portion 32s constituting the ball screw mechanism 32 is rotatably attached to the front surface of the rear support plate 23, and the rotating shaft of the servo motor 31 is coupled to the rear end of the threaded portion 32s. The servo motor 31 is equipped with a rotary encoder 33 for detecting the rotation (speed) of the servo motor 31. Furthermore, the front end of the nut portion 32n constituting the ball screw mechanism 32 is fixed to the rear surface of the slide unit 25, and the front end of the threaded portion 32s is screwed into the nut portion 32n.

[0024] On the other hand, 41 is a molding machine controller that controls the entire injection molding machine M. It has hardware such as a CPU and memory, as well as computer functions that have processing programs (software) to execute various control processes, including various calculation processes and sequence control. Therefore, the output ports of the molding machine controller 41 are connected to the servo motors 28 and 31 and each heating unit 3f... as described above, and the input ports of the molding machine controller 41 are connected to the rotary encoders 30 and 33 as described above, as well as temperature sensors 9... attached to each heating unit 3f... as described above. The above constitutes the basic configuration of the injection device Mi.

[0025] Next, the configuration of the plasticization state diagnostic device 1 according to this embodiment will be specifically described with reference to Figures 1-6.

[0026] As shown in Figures 1-6, the plasticization state diagnostic device 1 is equipped with multiple AE sensors (acoustic emission wave sensing sensors) 6r, 6f, which are piezoelectric ceramic elements or the like, that detect AE (acoustic emission) waves We, and are arranged at multiple (two in example) positions Xr, Xf with different front-to-back directions Fs in the heating cylinder 2.

[0027] The example includes two AE sensors 6r and 6f, a first AE sensor 6r and a second AE sensor 6f, which are located at two positions, namely, a first position Xr and a second position Xf. In this case, as shown in Figure 4, the first AE sensor 6r is located at the first position Xr, near the rear end of the rear heating section 3r, which is on the rear side of the heating cylinder 2, while the second AE sensor 6f is located at the second position Xf in the heating cylinder 2, which is in front of the first position Xr, namely, at the second position Xf near the front of the middle heating section 3m in the heating cylinder 2.

[0028] In this case, the first position Xr, which is closer to the rear end, is the position where a temperature sensor 9 is located to detect the heating temperature from the heating section 3r at the rear of the heating cylinder 2, while the position Xf, which is closer to the front, is the position where a temperature sensor 9 is located to detect the heating temperature from the heating section 3m in the middle of the heating cylinder 2.

[0029] In this embodiment, the two AE sensors 6r and 6f are integrally provided with a temperature sensor 9 attached to the heating cylinder 2, which detects the heating temperature of the heating cylinder 2. By configuring the AE sensor 6 with a first AE sensor 6r and a second AE sensor 6f, and arranging the first AE sensor 6r at a first position Xr at the rear of the heating cylinder 2, and arranging the second AE sensor 6f at a second position Xf in the heating cylinder 2 that is in front of the first position Xr, it is possible to detect accurate positional information such as where in the heating cylinder 2 the AE wave We was generated, and to detect a series of states from a solid state such as pellets to a molten state after plasticization, thereby enabling a sufficient and optimal understanding of the plasticization state inside the heating cylinder 2.

[0030] Figure 5 shows an AE sensor unit 6u housing the sensor body 6rm in the first AE sensor 6r (the same applies to the second AE sensor 6f). This AE sensor unit 6u is equipped with a cylindrical sensor holder 52, and a cylindrical sensor body 6rm is disposed on the lower side inside the sensor holder 52. The connecting lead 6rc of the sensor body 6rm is led out from the circumferential surface of the sensor holder 52 to the outside. The sensing surface 6rms, which is the lower end surface of the sensor body 6rm, faces outward from the lower end of the sensor holder 52. On the other hand, a plunger 53 is disposed on the upper side inside the sensor holder 52 so as to be displaceable in the axial direction, and a coil spring 51 is attached to bias the plunger 53 downward (towards the sensor body 6rm). As a result, the sensor body 6rm is fixed by the pressure of the tip of the plunger 53, and stable measurement can be performed. Furthermore, an alumina sheet 54 is interposed between the tip of the plunger 53 and the upper end surface of the sensor body 6rm, and an alumina sheet 55 is attached to the lower end surface of the sensor body 6rm. This reduces electrical noise.

[0031] Furthermore, the first AE sensor 6r (and the second AE sensor 6f) can be attached to the heating cylinder 2 as shown in Figures 1, 4-6.

[0032] Specifically, as shown in Figure 6, a mounting hole 56 having a predetermined depth is formed on the outer circumferential surface 2x of the first position Xr in the heating cylinder 2. Then, a block-shaped sensor mounting part 11 is fixed coaxially to this mounting hole 56. After this, the rod-shaped sensor body 9s of the temperature sensor 9 is inserted in the direction of arrow F1, that is, it is housed in the mounting hole 56 through the inner hole of the sensor mounting part 11, and the sensor body 9s of the temperature sensor 9 is fixed to the sensor mounting part 11.

[0033] As shown in Figure 1, the temperature sensor 9 comprises a housing portion 61 that constitutes the sensor body portion 9s having a hollow portion Sp inside, and a thermocouple 62 housed in the hollow portion Sp, with the tip of the thermocouple 62 exposed to the outside from the tip of the housing portion 61. The middle portion of the housing portion 61 to the tip constitutes the sensor body portion 9s, and the sensor mounting portion 11 is fixed to the middle portion of the housing portion 61. In addition, in the temperature sensor 9, 63 indicates a cap-shaped cover that covers the upper end opening of the housing portion 61, 64 indicates a spring that biases the thermocouple 62 downward, and 65 indicates the lead cable of the thermocouple 62.

[0034] On the other hand, the first AE sensor 6r, as shown in Figure 1, is composed of the aforementioned AE sensor unit 6u and waveguide unit 66. The waveguide unit 66 comprises a single round waveguide 11m and a disc-shaped mounting plate 11c integrally fixed to the upper end (rear end) of the waveguide 11m, and the lower surface 52d of the sensor holder 52 of the AE sensor unit 6u is fixed to the upper surface of the mounting plate 11c. As a result, the sensing surface 6rms, which is the lower end surface of the sensor body 6rm, comes into contact with the upper surface of the mounting plate 11c via the aforementioned alumina sheet 55.

[0035] Then, as shown in Figure 6, an insertion hole 11h at a predetermined angle is formed on the side surface (outer surface) of the sensor mounting portion 11, and the tip 11ms of the waveguide rod 11m is inserted into this insertion hole 11h, that is, inserted in the direction of arrow F2 and fixed in place. In this way, the temperature sensor 9 is provided with a sensor mounting portion 11 that is attached to the outer surface 2x of the heating cylinder 2, an insertion hole 11h is formed in this sensor mounting portion 11, and the tip 11ms of the waveguide rod 11m that supports the AE sensor 6 is inserted into this insertion hole 11h and attached, so that the sensor mounting portion 11 can be used as a single part that is used for both the AE sensor 6 and the temperature sensor 9, thus easily ensuring the unity of the part and contributing to improved positional accuracy.

[0036] The mounting example in Figure 6 is just one example, and other configurations are also possible as shown in Figure 7. In Figure 7, the AE sensor 6 is integrally provided with the temperature sensor 9 attached to the heating cylinder 2, which is the same as in Figure 1. However, in Figure 7, a cylindrical fixing cylinder 11e is attached to the sensor body 9s of the temperature sensor 9, covering the outer surface of the sensor body 9s, and a waveguide rod 11m is provided integrally extending from this fixing cylinder 11e. The lower surface 52d of the sensor holder 52 of the AE sensor unit 6u shown in Figure 5 is fixed to the upper end surface of this waveguide rod 11m.

[0037] On the other hand, as shown in Figure 3, the first AE sensor 6r and the second AE sensor 6f are connected to the controller of the molding machine controller 41 via preamplifiers 43r and 43f, respectively, and the aforementioned temperature sensors 9... are also connected to the sensor support of the controller body 42 via preamplifiers 44..., respectively. The controller body 42 incorporates hardware such as a CPU and functions as the main part of a computer system that performs various calculation and control processing.

[0038] Although the example shows the use of the molding machine controller 41, a separate high-speed processing computer may be prepared, and the outputs of the first AE sensor 6r and the second AE sensor 6f may be supplied to the high-speed processing computer to perform the necessary analysis processing using a separate processing system.

[0039] Furthermore, the internal memory 42m includes a program area 42mp for storing various processing programs (software) to execute various arithmetic and control processes (sequence control), and a data area 42md capable of storing various data (databases). In particular, the program area 42mp includes a diagnostic processing program for implementing the plasticization state diagnostic device according to this embodiment.

[0040] As a result, the molding machine controller 41, including the internal memory 42m and the controller body 42, functions as the main part of the plasticization state diagnostic device 1, that is, as shown in Figure 3, a data processing unit 7 that processes the AE wave signals Sre and Sfe obtained from each AE sensor 6r and 6f. Specifically, the diagnostic processing program determines the position calculation processing unit Ex, which determines position data Dx related to the generation position of the AE wave We based on the arrival times tr and tf of the AE wave We obtained from each AE sensor 6r and 6f; the attack count calculation processing unit Ea, which determines the number of times the AE wave signals Sre and Sfe related to the AE wave We generated for each predetermined sampling period Tp and predetermined position data Dx... exceeds a preset threshold L, as attack count data Da...; and the event count calculation processing unit Ee, which determines the quantity of AE wave components Sp... that exceed a preset threshold L, as event count data De....

[0041] Furthermore, the controller unit 42 is equipped with a display 42d. The display 42d comprises a display unit 42dm and a touch panel 42dt attached to the display unit 42dm. Therefore, various setting operations and selection operations can be performed using this touch panel 42dt. The display 42d constitutes a graphic display unit 8 that graphically displays at least the occurrence patterns Ps of attack count data Da... and event count data De... for position data Dx....

[0042] Figure 11 shows an example of the display screen 71 of the display 42d, which includes the graphic display unit 8. This display screen 71 has a screen configuration in which the setting unit 8s is displayed on the upper part of the screen and the graphic display unit 8 is displayed on the lower part of the screen.

[0043] In this case, the setting unit 8s includes a threshold setting unit 72 for setting a threshold L, an aggregation interval setting unit 73 for setting an aggregation interval, a data display unit 74 for displaying various data values, a switching key 75, etc. The threshold setting unit 72 can set threshold L for each AE wave signal Sre and Sfe obtained from AE sensors 6r and 6f (see Figure 10). In this case, each threshold L may be set to be the same or to be different. In this way, each threshold L can be set to be the same or to be different, so that the detection of the AE wave We can be performed with flexibility and reliability corresponding to the different installation positions of each AE sensor 6r and 6f.

[0044] Furthermore, the threshold setting unit 72 allows setting thresholds L for detecting attack count data Da and event count data De. When setting, the display can be switched using the switching key 75. In this case as well, each threshold L may be set to the same value or to different values. In this way, each threshold L can be set to the same value or to different values, making it possible to set flexible and optimal thresholds L corresponding to the attack count data Da and event count data De, respectively, and to obtain accurate attack count data Da and event count data De for AE waves We.

[0045] Furthermore, the aggregation interval setting unit 73 allows the sampling period Tp to be set, for example, by specifying "0" to "10" (10 seconds). The data display unit 74 displays setting values ​​and calculated values ​​such as the bandpass frequency (frequency band), event count value, and attack value used during filtering, and various display functions and setting functions can be switched using the switching key 75.

[0046] On the other hand, the graphic display unit 8 has the function of graphically displaying at least the occurrence pattern Ps of attack count data Da and event count data De in relation to position data Dx. The graphic display unit 8 shown as an example is configured to display in graph format by using the position data Dx in the front-to-back direction Fs of the heating cylinder 2 as a scale on the horizontal axis, and the event count data De and attack count data Da as scales on the vertical axis. Specifically, the attack count data Da is displayed as a bar graph Ga... and the event count data De is displayed as a line graph Gs...

[0047] In this way, when configuring the graphic display unit 8, if the occurrence patterns Ps of the attack count data Da... and event count data De... for the position data Dx... are displayed in graph format, graphic display becomes possible by combining general-purpose graphs such as bar graphs and line graphs. Therefore, the plasticization state and trouble occurrence state can be easily and quickly grasped from the generated occurrence patterns Ps.

[0048] The methods for obtaining the example location data Dx, attack count data Da, and event count data De will be explained in detail along with the processing procedure of the plasticization state diagnostic device 1, which will be described later.

[0049] On the other hand, the screw rotation servo motor 28 is connected to the output port of the controller body 42 via a motor driver (servo amplifier) ​​45. The rotation speed of the screw rotation servo motor 28 is detected by the rotary encoder 30, and the detected rotation speed signal is supplied to the motor driver 45 and the controller body 42. In addition, each band heater in the heating sections 3f, 3m, and 3r is connected to the output port of the controller body 42 via a heater driver 46.

[0050] Next, the operation (function) of the plasticization state diagnostic device 1 according to this embodiment, including the operation of the injection device Mi in the injection molding machine M, will be explained in accordance with the flowchart shown in Figure 8, with reference to Figures 1-5 and 9-15.

[0051] First, various setting processes necessary for the plasticization state diagnostic device 1 are performed using the setting unit 8s on the display screen 71 of the display 42d shown in Figure 11 (Step S1).

[0052] Specifically, the threshold setting unit 72 is used to set a threshold L for the AE wave signal Sre obtained from the first AE sensor 6r displayed on CH1, and a threshold L for the AE wave signal Sfe obtained from the second AE sensor 6f displayed on CH2. Each threshold L may be the same or different. It is also possible to set a threshold L for only one of CH1 or CH2. In the example shown in Figure 10, it is set to around 0.2 [V].

[0053] Furthermore, the sampling period Ts is set using the aggregation interval setting unit 73. In the example, it is set to approximately 10 seconds. In addition, by selecting and displaying the setting screen using the switching key 75, various setting values ​​such as the bandpass frequency of the bandpass filter (for example, 20-80 kHz (plastic breakage), etc.) and the ON / OFF status of the noise cancellation waveform (for example, a registered waveform measured in advance) can be set.

[0054] Once the setup process is complete, the injection molding machine M is started, i.e., the molding process is initiated (step S2). The molding machine controller 41 monitors the molding process during the operation of the injection molding machine M, and when the plasticization process begins, the controller unit 42 processes the detection signals based on the AE waves We obtained from each AE sensor 6r, 6f (steps S3, S4). In this case, the detection signals obtained from each AE sensor 6r, 6f are amplified by preamplifiers 43r, 43f, respectively, before being supplied to the controller unit 42 (step S5).

[0055] In the controller unit 42, noise reduction processing is performed on the amplified detection signal (step S6). The noise reduction processing removes noise components Np that are unrelated to the plasticization state inside the heating cylinder 2. In this case, pre-set noise frequency components may be removed, or the operating sound of the injection molding machine M may be measured in advance and registered as noise components Np..., thereby performing noise component cancellation processing. If necessary, the type of noise component Np can be selected or switched ON / OFF.

[0056] In this way, by applying noise reduction processing to the detection signals obtained from AE sensors 6r and 6f, treating any mixed signals other than those generated by the plasticization process by the heating cylinder 2 as noise components Np…, it is possible to eliminate ambient noise, i.e., unnecessary noise components Np… (disturbances) other than the AE wave signals Sre and Sfe generated by the plasticization of the molding material R, thereby obtaining more accurate AE wave signals Sre and Sfe.

[0057] The detection signal after noise reduction processing is filtered to allow only the set bandpass frequency Bs to pass through (step S7). This makes it possible to extract detection signals related to specific frequencies Bs, such as the frequency band in which the molding material R breaks (20-80 kHz) or the frequency band in which metals collide (200-350 kHz). In the example, it was set by the bandpass frequency Bs, but it may also be set as a bandpass frequency band with a predetermined bandwidth.

[0058] In this way, by applying a filtering process to the detection signals obtained from AE sensors 6r and 6f, which allows only a set specific frequency Bs or a set specific frequency band to pass through, it becomes possible to identify and detect AE wave signals Sre and Sfe obtained in conjunction with the plasticization of the molding material R, specifically the AE wave We when the molding material R breaks and the AE wave We when the molding material R collides with metal. This allows for a more accurate diagnosis of the plasticization state and the occurrence of problems.

[0059] Figures 9 and 10 show the signal waveforms of the AE wave signals Sre and Sfe after noise reduction and filtering. These signal waveforms can be displayed on a separate screen by switching the aforementioned switching key 75 (steps S8, S9).

[0060] Furthermore, the detection signal after filtering functions as AE wave signals Sre and Sfe, and the data processing unit 7 shown in Figure 3 performs calculation processing related to diagnostic data processing (step S10). In this case, the processing is performed over the sampling period Ts set by the aggregation interval setting unit 73, which in this example is 10 seconds.

[0061] Now, let's assume that during the sampling period Ts, a relatively large amplitude AE ​​wave We occurs, exceeding the threshold L as shown in Figure 10. In this case, first, the attack count calculation processing unit Ea performs the attack count calculation (step S11). That is, the amplitude of the AE wave signal Sre(Sfe) is determined by the threshold L, and if it exceeds the threshold L, it is determined that an attack has occurred, and the attack count data Da is "1".

[0062] Next, the event counting calculation unit Ee counts the quantity of waveform components Sp... that exceed the threshold L and performs event counting calculation processing to obtain the event count data De (step S12). The quantity obtained by the count becomes the event count data De.

[0063] Furthermore, based on the obtained AE wave signals Sre and Sfe, the position calculation processing unit Ex performs calculation processing for position data Dx (step S13). The position calculation processing unit Ex determines the position data Dx related to the generation location of the AE wave We based on the arrival times tr and tf of the AE wave We obtained from each AE sensor 6r and 6f. That is, as shown in Figure 9, a time difference Δt occurs between the arrival times tr and tf of the AE wave signals Sre and Sfe obtained from each AE sensor 6r and 6f. Therefore, the generation location of the AE wave We is determined as position data Dx based on the installation positions Xr and Xf of each AE sensor 6r and 6f, the time difference Δt, and the speed of sound. The longitudinal frequency of iron was used for the speed of sound.

[0064] Through this series of data processing, the attack count data Da, event count data De, and location data Dx are linked to each other, and are temporarily registered in this linked state. This completes the data processing when one attack occurs. Subsequently, if the next attack occurs during the sampling period Ts, the same processing procedure is used to obtain the attack count data Da, event count data De, and location data Dx (steps S14, S10…). This series of data processing is carried out until the set sampling period Ts ends.

[0065] Then, once the sampling period Ts has ended, the linked attack count data Da…, event count data De…, and location data Dx… from the sampling period Ts are aggregated (step S15). The aggregated attack count data Da…, event count data De…, and location data Dx… are then graphically displayed by the graphic display unit 8, as shown in Figure 11 (step S16).

[0066] The example graphic display is in graph format, with the horizontal axis representing the position Fs in the front-to-back direction of the heating cylinder 2. For example, position ranges are set sequentially at 20 mm intervals. If position data Dx exists within this position range, the aggregated value of the attack count data Da... corresponding to that position data Dx is displayed as a bar graph Ga, and the aggregated value of the event count data De... is displayed as a line graph Gs.

[0067] This displays the occurrence pattern Ps using a bar graph Ga and a line graph Gs. Based on this display of the occurrence pattern Ps, an operator or AI (artificial intelligence) can perform predetermined diagnostic processing, including determining the quality of the plasticization state (step S17).

[0068] Figures 12-15 show examples of various generation patterns Ps. In this case, Figures 12 and 13 show the generation patterns Ps when "GPPS (general-purpose polystyrene) resin" is used as the molding material R and the bandpass frequency Bs is set to 50-60 [kHz]. Figure 12 shows the case when the heating temperature is set to "low temperature 170 [°C]", while Figure 13 shows the case when the heating temperature is set to "optimal temperature 200 [°C]".

[0069] The bandpass frequency Bs set to 50-60 kHz is the frequency at which plastic fracture is expected. As is clear from the occurrence patterns Ps shown in Figures 12 and 13, Figure 13 shows a normal plasticization state with a temporary increase in attack count data Da and event count data De in the initial stages of plasticization, whereas Figure 12 shows an increase in the number of occurrences of attack count data Da and event count data De, and moreover, it occurs over a wide area Fs in the front-to-back direction of the heating cylinder 2, especially near the front end of the heating cylinder 2, confirming a state of insufficient plasticization.

[0070] Furthermore, in the case of Figure 14, the basic conditions are the same as in Figure 13, but the generation pattern Ps when the heating temperature is set to "high temperature 240 [°C]" is shown. As is clear from Figure 14, it can be confirmed that the plasticization state is not significantly different compared to the case of "optimal temperature 200 [°C]" shown in Figure 13.

[0071] Furthermore, in the case of Figure 15, the basic conditions are the same as in Figure 14, but the case where the bandpass frequency Bs is set to 220 kHz is shown. The set frequency range of 200-350 kHz is the frequency at which generation due to metal contact is expected. As is clear from Figure 15, although the unmelted molding material R comes into contact with the screw 5 at the rear of the heating cylinder 2, generating attack count data Da and event count data De, it can be confirmed that almost no further data is generated thereafter, thus confirming that it is in a normal plasticizing state.

[0072] Thus, it can be confirmed that the occurrence pattern Ps graphically displayed by the graphic display unit 8 reflects the plasticization state as a pattern. Therefore, an operator or AI can perform diagnostic processing such as determining the quality of the plasticization state or whether a problem has occurred based on the occurrence of abnormal sounds. Furthermore, by accumulating the occurrence pattern Ps... as big data and using it for learning, the diagnostic accuracy can be further improved.

[0073] The diagnostic results can be displayed on the display screen of the display 42d as a diagnosis of the quality of the plasticization state or as a result of an abnormality, or they can be output as control commands for necessary stop control or operation control (step S18).

[0074] Therefore, according to the plasticization state diagnostic device 1 of the injection molding machine M according to this embodiment, the basic configuration includes an AE sensor 6 that detects AE waves We by being integrally provided with a temperature sensor 9 that detects the heating temperature of the heating cylinder 2 attached to the heating cylinder 2, and a diagnostic processing unit 7 that diagnoses the plasticization state of the molding material R based on the detection result of the AE sensor 6. As a result, the AE sensor 6 can be provided integrally with the temperature sensor 9. By arranging multiple temperature sensors 9 on the outer surface of the heating cylinder 2, it is possible to reduce the size by saving space in the limited installation space, avoid complexity, and reduce manufacturing man-hours and manufacturing costs.

[0075] Furthermore, the plasticization state diagnostic device 1 according to this embodiment can accurately obtain information from a planar (three-dimensional) perspective, as well as a qualitative perspective, such as where in the heating cylinder 2 the AE wave We is generated and what caused the AE wave We. This makes it possible to realize a more practical, convenient, and user-friendly plasticization state diagnostic device 1, enabling accurate and reliable quality diagnosis and trouble detection of the plasticization state.

[0076] Although preferred embodiments have been described in detail above, the present invention is not limited to these embodiments, and the details of the configuration, shape, quantity, etc., can be arbitrarily changed, added, or deleted without departing from the spirit of the present invention.

[0077] For example, the case where AE sensors are placed at two locations, the rear and front of the heating cylinder 2, is shown, but generally, AE sensors 6r… can be placed at two or more different locations. Furthermore, the rear and front of the heating cylinder 2 where the AE sensors 6r and 6f are placed indicate a relative position, not an absolute position. Therefore, the front position means that it is located in front of the rear position, and does not mean that it is located at the front of the heating cylinder 2 as an absolute position; it may be located in the middle or rear of the heating cylinder 2. On the other hand, noise reduction processing and filtering processing are desirable, but are not essential configuration requirements. Furthermore, it is desirable for the graphic display unit 8 to display the occurrence patterns Ps of the attack count data Da… and event count data De… for the position data Dx… in graph format, but it is possible to implement this using various graphic formats other than graph format as long as the occurrence patterns Ps can be grasped through graphic display. [Industrial applicability]

[0078] The plasticization state diagnostic device according to the present invention can be used in various injection molding machines that plasticize the molding material supplied inside a heating cylinder by the rotation of a screw. [Explanation of symbols]

[0079] 1: Plasticization state diagnostic device, 2: Heating cylinder, 2x: Outer surface of heating cylinder, 3f…: Heating section, 4: Material supply section, 5: Screw, 6: AE sensor, 6r: First AE sensor, 6f: Second AE sensor, 7: Diagnostic processing unit, 8: Graphic display unit, 9: Temperature sensor, 11: Sensor mounting section, 11h: Insertion hole section, 11m: Waveguide rod, 11ms: Tip of the waveguide rod, R: Molding material, M: Injection molding machine, We: AE wave, Xr: First position, Xf: Second position, tr: Arrival time, tf: Arrival time, Ex: Position calculation processing unit, Sre: AE wave signal, Sfe: AE wave signal, L: Threshold, Ea: Attack count calculation processing unit, Ee: Event count calculation processing unit, Ps: Occurrence pattern

Claims

1. A plasticization state diagnostic device for an injection molding machine, which diagnoses the plasticization state of a molding material when the molding material supplied to the inside of a heating cylinder from a material supply unit located at the rear of the heating cylinder, which is heated by a heating unit, is plasticized by the rotation of a screw, the device comprising: a temperature sensor that detects the heating temperature of the heating cylinder by having a sensor mounting portion attached to the outer surface of the heating cylinder; an AE sensor that detects an AE wave integrally provided with the temperature sensor by inserting the tip of a waveguide rod into an insertion hole formed on the side surface of the sensor mounting portion; and a diagnostic processing unit that diagnoses the plasticization state of the molding material based on the detection result of the AE sensor.

2. The plasticization state diagnostic device for an injection molding machine according to claim 1, wherein the AE sensor comprises a first AE sensor and a second AE sensor, the first AE sensor being disposed at a first position on the rear side of the heating cylinder, and the second AE sensor being disposed at a second position on the heating cylinder which is forward of the first position.

3. The diagnostic processing unit comprises a data processing unit that includes a position calculation processing unit that obtains position data relating to the generation position of an AE wave based on the arrival time of the AE wave obtained from each AE sensor, an attack count calculation processing unit that obtains as attack count data the number of times the AE wave signal relating to the AE wave generated for a predetermined sampling period and for each predetermined position data exceeds a preset threshold, and an event count calculation processing unit that obtains as event count data the quantity of the AE wave component that exceeds a preset threshold, thereby providing a plasticization state diagnostic device for an injection molding machine according to claim 2.

4. The plasticization state diagnostic device for an injection molding machine according to claim 3, characterized in that the diagnostic processing unit includes a graphic display unit that displays the occurrence patterns of the attack count data and the event count data in relation to the position data in a graph format.

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