JPH028025A - Monitoring method for control state of injection molding machine - Google Patents

Abstract

PURPOSE:To accurately detect the generation of an improper product or an abnormal state of a molding operation by setting the upper and lower limit values of an allowable range on the basis of measured data at the time of generation of a satisfactory product stored in storage means. CONSTITUTION:A variation amount to be monitored is actually measured at a preset sampling interval in an injection molding operation for continuously obtaining molded pieces of satisfactory quality, and the values are stored corresponding to (sampling position):Sx in a predetermined memory area of an internal memory 42. The central position of the (sampling position):Sx is calculated, (numerical value):(DELTAA) set as a width to be monitored by a setter 52 is added or subtracted, and (the upper limit value of an allowable range):(Ax max) and (the lower limit value):(Ax min) are determined. When it is monitored according to the monitoring program of a CPU 38 with such allowable range as a reference, the generation of an improper product or the abnormal state of a molding operation can be accurately detected, the generation of the malfunction can be rapidly informed by an acoustic alarm 58 or the like, and the improper product and the satisfactory product can be automatically sorted by switching the position of a molded piece discharging chute.

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a method for monitoring the control status of an injection molding machine, and more particularly, the present invention relates to a method for monitoring the control status of an injection molding machine, and more specifically, the amount of fluctuation that varies depending on the control status of the injection molding machine is monitored at each control stage. The present invention relates to a control state monitoring method for monitoring whether an injection molding machine is normally controlled according to a predetermined control pattern by determining whether or not it falls within a predetermined tolerance range.

(Background technology) In order to stably mold a molded product of good quality with an injection molding machine, various control amounts during the molding operation are required. The rotational speed and back pressure of the injection screw during plasticizing and metering operations, as well as the injection speed and injection pressure during injection operations, are precisely controlled according to preset control patterns for each control amount. There is a need to. To this end, it has been proposed to apply closed-loop control or program control to these controls.

However, in such an injection molding machine, even when each controlled variable is controlled in a closed loop or by a program according to its own control pattern, as described above, disturbances and the mixing of crushed material into the molding material can occur. Due to various causes such as, the actual control 411 may vary greatly, resulting in defective products,
This may lead to problems such as abnormalities in the molding operation.

(Problem to be solved) The present invention was made against the background of the above-mentioned circumstances, and the problem to be solved is that the amount of variation that varies depending on the control state of the injection molding machine is By monitoring whether or not changes are normal depending on the condition, it is possible to immediately and accurately detect the occurrence of defects such as defective products or abnormal conditions in molding operation, and to take measures to prevent the occurrence of such defects. The aim is to ensure that the situation can be dealt with immediately.

(Solution Means) In order to achieve the above object, the present invention provides a method for determining the amount of variation that varies depending on the control state of the injection molding machine in an arbitrary control section of the injection molding machine during actual molding operations of the injection molding machine. According to 4, the measurement data obtained at a predetermined sampling interval is successively compared with the upper and lower limits of the tolerance range set in advance corresponding to each sampling position of the measurement data, and the injection in that control section is determined. When monitoring the control state of the molding machine, the measurement data during molding of a good product by actual molding operations regarding the amount of variation is stored in a storage means, and the above-mentioned fluctuation amount is The gist is that the upper and lower limits of the allowable range are set.

Furthermore, the present invention is capable of integrating measurement data obtained at predetermined sampling intervals according to the actual molding operation of the injection molding machine, with respect to the amount of fluctuation that varies depending on the control state of the injection molding machine in any control section of the injection molding machine. The control status of the injection molding machine in that control area is monitored by successively comparing the value and each integral value of the upper limit value and lower limit value of the tolerance range set in advance corresponding to each sampling position of the measurement data. At this time, the measurement data during molding of a non-defective product in the actual molding operation regarding the amount of variation is stored in a storage means, and the upper and lower limit values of the tolerance range are determined based on the measurement data during molding of a non-defective product stored in the storage means. The gist of this is also that it has been made possible to set the .

Here, the upper and lower limits of the allowable range are determined by, for example, storing measurement data for a plurality of molding operations in a storage means when molding a non-defective product, and averaging the measurement data for the plurality of molding operations at each sampling position. It is determined by finding a value or median value, and adding or subtracting a predetermined value to the average value or median value.

Furthermore, measurement data for a plurality of molding operations during molding of a non-defective product is stored in the storage means, and the maximum value and minimum value at each sampling position of the measurement data for the plurality of molding operations are determined, and the maximum value and the minimum value are determined. It is also possible to set the minimum value as the upper limit and lower limit of the allowable range, respectively, and set the values obtained by adding or subtracting a predetermined value to the maximum and minimum values, respectively, as the upper limit and lower limit of the allowable range. is also possible.

Furthermore, it is also possible to set the upper and lower limits of the allowable range based on the measurement data of the bone that has been subjected to one shaping operation, which is stored in the storage means. In this case, a value obtained by adding a predetermined value to the measurement data of each sampling position may be set as the upper limit value, while a value obtained by subtracting the predetermined value from the measurement data may be set as the lower limit value.

By the way, when setting the upper and lower limits of the allowable range, it is recommended to superimpose the measurement data when molding non-defective products on a flat display such as a CRT so that the degree of variation in the measurement data when molding non-defective products can be visually confirmed. is desirable,
In addition, when the measured data is displayed in a superimposed manner on a flat display, a linear cursor that can be moved in the time axis direction of the measured data is provided on the flat display on which the measured data is displayed in a superimposed manner. It is preferable to calculate and display the maximum deviation value from the median value of the measured data at the sampling position corresponding to the moving position.

Furthermore, monitoring of the control state does not necessarily have to be carried out over the entire variation range of the amount of variation to be monitored, but it is also possible to monitor the control state only in a specific range of the variation range. In this case, a flat display is provided to display the permissible range, and two linear cursors that can be moved arbitrarily in the time axis direction are provided on the flat display to display the range defined by these two cursors. It is preferable to allow monitoring to take place.

In addition, the tolerance range does not necessarily have to be limited to just one set of upper and lower limit values; instead, the tolerance range can be set at multiple stages with multiple sets of upper and lower limits, and the measurement data can be set at multiple stages. It is also possible for the injection molding machine to take different countermeasures depending on the stage of deviation from the set tolerance range.

(Example) Hereinafter, in order to clarify the present invention more specifically,
The embodiment will be described in detail based on the drawings. Although an example in which the present invention is applied to an in-line screw type injection molding machine will be described below, it is of course possible to apply the present invention to a plunger type injection molding machine in which the injection operation is performed by a plunger.

First, FIG. 1 shows an example of an in-line screw injection molding machine to which the method of the present invention can be applied. There, reference numeral 10 denotes an injection screw inserted into a heating cylinder 12, which is rotated by a hydraulic motor 14 and moved in the axial direction by an injection cylinder 16. There is. As is well known, the injection screw 10 is rotated by the hydraulic motor 14 to plasticize and meter the resin material, and after the plasticization and metering operation, A predetermined injection operation is performed by moving the injection screw 10 forward with the injection cylinder 16. Injection cylinder 16
When the injection screw 10 is moved forward, resin material is injected into the cavity 22 of the mold 20 from the nozzle at the tip of the heating cylinder 12 as the injection screw 10 moves forward.

Here, the hydraulic motor 14 is connected to the switching valve 26 from the pump 24.
The injection screw 10 is rotated by hydraulic oil supplied through the injection screw 10, and its rotation speed, and thus the rotation speed of the injection screw 10, is controlled by an electromagnetic proportional flow control valve 28. In addition, the injection cylinder 16 is connected to the pump 24 by an electromagnetic proportional flow control valve 28 and a switching valve 26.
The hydraulic pressure control valve 3 is driven by hydraulic oil supplied through the electromagnetic proportional pressure control valve 3.
It is adjusted by 0, and as a result,
The forward speed (injection speed) of the injection screw 10 during injection operation can be adjusted based on the adjustment of the inflow amount of hydraulic oil by the electromagnetic proportional flow control valve 28, and the operation by the electromagnetic proportional pressure control valve 30 can be adjusted. Based on the adjustment of the oil pressure, the injection pressure during the injection operation can be adjusted. Note that the back pressure during the plasticizing and metering operations is also controlled based on the control of the set pressure of the electromagnetic proportional pressure control valve 30.

The hydraulic motor 14 that rotationally drives the injection screw 10 is provided with a rotation sensor 48 for detecting the rotational speed of the hydraulic motor 14 and, by extension, the injection screw 10. A signal representing the rotational speed of the injection screw 10 is supplied from the rotation sensor 48 to the CPU 38 of the controller 36 via the interface circuit 34. In addition, an oil passage leading the hydraulic oil to the hydraulic motor 14 is provided for detecting the oil pressure of the hydraulic oil supplied to the hydraulic motor 14, and further, the rotational torque of the injection screw 10 during plasticizing and metering operations of the resin material. A hydraulic sensor 50 is connected, and a signal representing the rotational torque of the injection screw 10 during plasticizing and metering operations of the resin material is transmitted from the hydraulic sensor 50 to the interface circuit 34.
It is designed to be supplied to CPU3B via.

Furthermore, an oil pressure sensor 40 is connected to the injection cylinder 16, and a signal representing the working oil pressure of the injection cylinder, the back pressure during plasticizing and metering operations of the resin material, and the injection pressure during the injection operation is sent to the injection cylinder 16. Oil pressure sensor 40
The signal is supplied to the CPU 38 from the interface circuit 34.

Further, the injection screw 10 includes the injection screw 10.
A position sensor 3 detects the moving position of the screw, the so-called screw position.
2 is attached, and signals representing the screw position of the injection screw 10 and, by extension, the forward and backward speeds of the injection screw 10 are supplied from this position sensor 32 to the CPU 38.

The CPU 38 reads each detection signal from the sensors 32, 40.4850 during the plasticizing/metering operation of the resin material according to the sampling interval set for the plasticizing/metering operation section, and also reads the detection signals from the sensors 32, 40. , the detection signals from the sensors 32 and 40 are read in accordance with the sampling interval set for the injection operation section, and each detection value represented by these signals is stored in each corresponding memory area of the internal memory 42. ing.

Note that the detection signal from the position sensor 32 is stored in the internal memory 42 as a moving speed value of the injection screw 10. Further, each of the detected values described above is also stored in an external memory 46 such as a floppy disk, IC card 1, or RAM pack via the interface circuit 44, if necessary.

Further, the sampling interval is set based on either time or screw position.

Here, a setting device 52 consisting of various setting devices is connected to the CPU 3B via an interface circuit 44, and a CRT 54 as a display is also connected. Based on the setting operations of various setting devices provided in the setting device 52, the rotational speed control pattern and back pressure control pattern of the injection squeegee 10 in the plasticizing/metering process, the injection speed control pattern in the injection process, and the injection Various molding conditions such as pressure control patterns are set. The interface circuit 56 is controlled by the CPU 38 according to the rotation speed control pattern and the back pressure control pattern during the plasticizing and metering operations of the resin material, and according to the injection speed control pattern and the injection pressure control pattern during the subsequent injection operation. Through the electromagnetic proportional flow control valve 28 and the electromagnetic proportional pressure control valve 30
A control signal is supplied to the injection screw lO and the operation of the injection cylinder 16 according to the rotation speed control pattern and the back pressure control pattern during plasticizing and metering operations of the resin material. While the oil pressure is controlled respectively, during injection operation, the forward speed of the injection screw 10 is controlled according to the injection speed control pattern, or the working oil pressure of the injection cylinder 16 is controlled according to the injection pressure control pattern. .

In other words, unless there are special circumstances, the molding machine is operated with high accuracy according to a preset control pattern, and molded products of good quality can be stably obtained.

Although not detailed here, the control patterns for each of the above-mentioned controlled variables and the actual measured trends for these controlled variables can be displayed superimposed, simultaneously, or selectively in any combination on the CRT 54. It looks like this.

By the way, in such an injection molding machine, as mentioned above, unless there are special circumstances, such as the influence of external noise or the mixing of crushed material into the resin material, plasticizing and metering operations cannot be performed. Each control amount at the time and during the injection operation is precisely controlled according to each control pattern, and as a result, molded products of good quality are always stably molded. However, if special circumstances such as those mentioned above occur, each control will be controlled according to each control pattern. The amount of IIl may not be precisely controlled and may vary widely, resulting in problems such as defective products being molded or abnormalities in the molding operation.

Therefore, here, the variation amounts of the rotational speed, retraction speed, torque, and back pressure of the injection screw 10, which vary depending on the control state of the injection molding machine during the plasticizing/metering operation, are set in advance. The CPU 3B is provided with a monitoring program for determining whether the injection molding machine is performing the molding operation normally by determining whether the injection molding machine is within the permissible range. If the monitoring program detects that an abnormality has occurred in the control state of the injection molding machine, an audible alarm 58 or the like will notify you of the abnormality, and the position of the molded product discharge chute (not shown) of the injection molding machine will be changed. The molded product molded under the abnormal condition is guided to the defective product storage container.

Hereinafter, the monitoring operation of the CPU 38 will be explained according to the flowchart of the monitoring program shown in FIG. Note that the monitoring operation of the CPU 38 for each fluctuation amount of the rotational speed, retraction speed, torque, and back pressure of the injection screw 10 is the same for each fluctuation amount, so here, the rotational speed of the injection screw IO is monitored. The monitoring operation of the CPU 38 will be described in detail only for the example. Further, here, the monitoring operation of the CPU 38 will be described on the assumption that the sampling interval for detecting the rotational speed of the injection screw lO is set with the screw position of the injection screw 10 as a reference.

That is, in the flowchart of Fig. 2, plasticization and
When a metering operation command is issued and a plasticizing/metering operation is started based on the supply of control signals from the CPO 38 to the electromagnetic proportional flow control valve 28 and the electromagnetic proportional pressure control valve 30,
First, step S1 is executed, and a sampling counter for counting the number of samplings: X of the measurement data of the screw rotational speed to be monitored is reset. Then, in the following step S2, the upper limit value of the tolerance range preset corresponding to the sampling position: SX represented by the count value of the sampling counter: AX3. X and the lower limit 'Axmi□ are read out.

In addition, in step S2 immediately after the execution of step S1 in which the count value of the sampling counter: X indicates the reset value, the upper limit value of the tolerance range corresponding to the first sampling position: 81: Al Read out.

In step S2, the upper limit value of the tolerance range corresponding to the sampling position: 88: Ax□9 and the lower limit value: Axm
When i is read out, step S3 is subsequently executed, and it is determined whether the measurement data DX corresponding to the sampling position SX represented by the count value X of the sampling counter has been read. As a result of that judgment, when it is confirmed that the measurement data: DX corresponding to the sampling position f:sx has been read, in the following step S4, the measurement data = DX is set to the upper limit '
It is determined whether or not the value is within the permissible range defined by AXFARX and the lower limit value: AXFARX.

As a result of the judgment in step S4, if it is found that the measured data: DX is within the allowable range, step S5 is subsequently executed, but conversely, if the measured data: DX is within the allowable range. If it is determined that there is no
6. S7 is subsequently executed. Then, in step S6, which is executed when it is determined that the measured data: DX is not within the allowable range, an alarm signal is output to the audible alarm 58 etc. via the interface circuit 56, and the audible alarm is activated. An alarm is issued by the device 58 etc.
In the subsequent step S7, the position of the molded product discharge chute is switched so that the molded products in that molding cycle are guided to the defective product storage container side. Note that once step S7 is completed, step S5 is subsequently executed.

In step S5, the count value of the sampling counter: X is compared with a preset final sampling count value: n. If it is determined that the count value X has already reached the final sampling count value n, the monitoring program ends, but if it is determined that the count value X has not yet reached the final sampling count value n. Then, step S8 is subsequently executed, and the sampling counter is incremented. After completion of this step S8, the steps from step 82 onward are repeated.

That is, the measured data of the screw rotation speed at each sampling position: SX: Dx is the upper limit value set in advance for each sampling position: SX: AX +
It is compared with the tolerance range defined by HiX and the lower limit value: AXY8, and if it is determined that the rotation speed is out of the tolerance range, an audible alarm 58 or the like will notify you of this. On the other hand, by changing the position of the molded product discharge chute, the molded products molded in that molding cycle are stored in the defective product storage container.

In this embodiment, the upper limit value of the allowable range read out in step S2 of the monitoring program is
By setting AX ms* and the lower limit value: Ax min as follows, when a defective product is molded or an abnormal condition occurs in the molding operation, an alarm is issued by the audible alarm 58, etc., and the Defective products molded in the molding cycle are stored in a defective product storage container, and defective products are automatically sorted from non-defective products.

That is, in this embodiment, the upper limit of the allowable range is Ai. and lower limit value: Axm! . When setting with
First, an actual injection molding operation is repeatedly performed according to a control pattern set in advance for each controlled variable. Then, under injection molding operations in which molded products of good quality are continuously obtained, a variable engineer to be monitored performs actual measurements at preset sampling intervals for as many molding operations as possible or a preset number of times. , the actual measured values are stored in a predetermined memory area of the internal memory 42 corresponding to each sampling position: SX. and,
Based on the measurement data (actual measurement values) of the bones that have been subjected to a plurality of molding operations stored in the internal memory 42, the CPU 3
By B, the median value at each sampling position 1tsX (the average value of the maximum value and minimum value of the measurement data at the sampling position: SX) is calculated, and then the setting The device 52 adds or subtracts the numerical value ΔA set as the monitoring width to determine the upper limit value: AX+n++x and the lower limit value: Axmin of the permissible range (see FIG. 4).

In addition, the upper limit of the tolerance range obtained in this way: A
X□8 and the lower limit value: AXmin are stored in the external memory 46 as a set with the control pattern of each control amount, etc., and can be set together with the molding conditions by replacing the external memory 46. becomes.

Here, in this example, the measurement and
In parallel with the storage operation and the median calculation operation, the measurement data for a plurality of molding operation strokes stored in the internal memory 42 are displayed on the screen of the CRT 54 selected by the setting device 52 as shown in FIG. As shown in Figure 3, the horizontal axis is superimposed on the time axis (screw position; sampling position), and on this screen, the settings can be changed as shown in Figure 3. Device 5
A linear cursor K that can be moved in the time axis direction by the setting operation of the setting device 52 is provided, and measurement data at the sampling position: SX corresponding to the movement position of the cursor is provided by a calculation command based on the setting operation of the setting device 52. Maximum deviation value (DEV) from the median value: ΔD is calculated,
It is now displayed.

In other words, here, the operator can easily recognize the appropriate monitoring width based on the degree of variation in the measurement data displayed on the screen of the CRT 54 and the displayed numerical value of the maximum deviation value: ΔD at the cursor position. It has become,
Based on this recognition, the monitoring width: ΔA can be set.

Therefore, based on the monitoring width set in this way: ΔA, the upper limit of the allowable range: A6- and the lower limit: Axm
Determine rn, such upper limit value: AX□, and lower limit value:
If monitoring is performed according to the monitoring program of the CPU 3 B based on the tolerance defined by AX mi, , the occurrence of defective products or abnormal conditions in the molding operation can be detected with high accuracy, and these defects can be corrected. The occurrence of molding can be immediately notified by an alarm such as the audible alarm 58, and by switching the position of the molded product discharge chute, defective products and non-defective products can be automatically separated with high precision.

In addition, the upper limit value of the above tolerance range: AX□8 and the lower limit value:
A command to calculate the median value when setting A ll 111' is normally issued based on the setting operation of the setting device 52, but measurement data for a preset number of molding operations are stored. It is also possible to have it emitted automatically at a certain point in time.

Further, the monitoring width: ΔA is normally set to a value slightly larger than the maximum deviation value: ΔD, but the ratio between the monitoring width: ΔA and the maximum deviation value: ΔD is set in advance. By doing so, it is also possible to automatically obtain the monitoring width: ΔA from the maximum deviation value: ΔD.

Furthermore, in this embodiment, the upper limit of the allowable range for the screw rotation speed: AX□9 and the lower limit: AxMin
Setting operations similar to those described above are also performed for the rotational torque, retraction speed, and back pressure of the injection screw 10, based on the upper and lower limit values of the allowable range set for each of these fluctuation amounts. As described above, monitoring operations similar to those for the rotational speed of the injection screw 10 are performed for each of these variations. Incidentally, FIGS. 5 to 7 show diagrams corresponding to FIG. 3 of the screw rotational speed with respect to each variation amount of the back pressure, retraction speed, and rotational torque of the injection screw IO.

As explained above, in this embodiment, during the plasticizing and metering operations of the resin material, the rotational speed, retraction speed, torque, and back pressure of the injection screw 10, which vary depending on the control state of the injection molding machine, are The upper limit (A, , , The system is constantly compared with the tolerance range set in this way to determine whether or not defective products or abnormal conditions in the molding operation occur. The occurrence of this can be detected quickly and accurately and notified. As soon as these defects occur, the position of the molded product ejection chute is changed and the defective products are stored in the defective product storage container, so that defective products can be separated from non-defective products with high precision. This can be done automatically, which has the advantage of eliminating the need for sorting of molded products.

By the way, in the above embodiment, the upper limit value (A, □X) and lower limit value (A, □,
When setting 1), first, based on the actual measurement value (measurement data) during molding of a good product stored in the internal memory 42,
The median value of the measurement data at each sampling position (SX) is calculated, and for the calculated median value,
The numerical value (ΔA) set as the monitoring width is added or subtracted,
The upper limit value (A, □,) and lower limit value (A, 1fi) are set, but instead of the above median value, the average value of the measurement data at each sampling position (S,) is calculated, A predetermined appropriate value for each average value,
For example, by adding or subtracting ΔA in the above example, the upper limit value (A,, □) and the lower limit value (A, □) of the allowable range are obtained.
), and it is also possible to determine the maximum and minimum values of the measurement data at each sampling position (S, ) based on the measurement data stored in the internal memory 42, and set those maximum and minimum values. Leave the minimum value unchanged as the upper limit value (A, □X) and lower limit value (AX□
4. , ) (see Figure 8), and furthermore, it is also possible to set a predetermined appropriate value for these maximum and minimum values, for example, the difference between ΔA and ΔD (maximum deviation value) in the above embodiment. Degree value: The value obtained by adding or subtracting ΔB is the upper limit value (AX□X) and lower limit value (A, ,
, , ) (see No. 9). In addition, predetermined appropriate values are added and subtracted to the measurement data of the bone that has been subjected to one molding operation stored in the internal memory 42, and the upper limit value (AX, , X) and lower limit value (AXmi, , ) may also be set (see FIG. 10).

In addition, in the above embodiment, the four fluctuation amounts of the injection screw 10 rotational speed, retraction speed, torque, and back pressure during plasticizing and metering operations of the resin material are monitored, and the The monitoring operation monitors the control status during plasticizing and metering operations, but it is also possible to arbitrarily select only one of these variables as the subject of monitoring. be.

Further, the present invention can be applied to the case where the injection speed and injection pressure during the injection operation, as well as the amount of variation in the heating cylinder temperature, mold temperature, etc., are to be monitored.

Furthermore, in the above embodiment, in the monitoring program in the CPU 38, the actual measurement data (D,) of the amount of variation to be monitored is directly connected to the upper limit value (A, , , ) and lower limit value (A, min ) of the allowable range. If the measured data (DX) deviates even slightly from the allowable range, it is determined that an abnormality has occurred in the control state of the injection molding machine under the monitoring of the amount of variation. D,) is out of the allowable range continuously for a certain period of time, and only when the number of times is greater than a preset number, it is determined that an abnormality has occurred in the control state. Therefore, it is possible to avoid falsely detecting a temporary deviation of the measured data (D,) from the allowable range as the occurrence of an abnormal condition.
Compare the integral value of DX) with the integral values of the upper limit value (A, , , ) and lower limit value (A, , , i,) of the tolerance range,
It is also possible to determine whether an abnormal control state has occurred based on the comparison results.

Further, in the above embodiment, for each variation amount to be monitored, a set of upper limit values (A) is set in the allowable range.

, 1X) and the lower limit (AX, i,),
The measured data (D,) is simply a set of upper limits (A.

When an abnormal condition is detected,
Regardless of the degree of the abnormal condition, the same countermeasures are always taken, but the tolerance range for the amount of variation to be monitored is defined in multiple stages with multiple sets of upper and lower limit values, and the measurement It is also possible to take different countermeasures depending on the stage at which the data (D,) deviates from the permissible range defined in the plurality of stages.

Incidentally, Fig. 11 shows the integral value of the measurement data (D) and the upper limit of the allowable range (A) for the fluctuation amount to be monitored.
An example of a monitoring program that compares the integrated values of the lower limit values (A, , i, ) and determines whether an abnormal control state has occurred based on the comparison results is shown below. In addition, Fig. 13 shows that the tolerance range is set in multiple stages with multiple sets of upper and lower limit values, and the measurement data (D,) is determined according to the stage in which the measurement data (D,) deviates from the tolerance range specified in the multiple stages. This shows an example of a monitoring program in which different countermeasures are taken depending on the situation. In the following, other embodiments of the present invention will be described based on the flowcharts of the monitoring program shown in FIGS. 11 and 13. Let me explain.

However, similar to the embodiments described above, a case will be described here in which the rotational operation of the injection screw 10 is to be monitored. In addition, here, an example will first be described in which a monitoring operation is performed according to the monitoring program shown in FIG. 11, and then an example will be described in which a monitoring operation is performed according to the monitoring program shown in FIG. 13. In an injection molding machine in which the monitoring operation is performed according to the following, the control state is monitored only within the period that is preset based on the setting operation of the setting device 52 among the full rotation operation period (variation period) of the injection screw 10. A case in which this is done will be explained.

That is, in an injection molding machine whose monitoring operation is performed according to the monitoring program shown in FIG. 11, when the monitoring program is started by a plasticizing/metering operation command,
First, step S1 is executed and the sampling counter is reset as in the previous embodiment. Then, in the subsequent step S2, the count value of the sampling counter, that is, the number of actual measurements of the screw rotation speed:
Monitoring start position of monitoring section (monitoring start sampling position)
:S, it is determined whether or not the preset measurement number of times:X5 has been reached.

In step S2, the actual measurement number of the screw rotation speed represented by the count value of the sampling counter:
If it is determined that this has not been reached, step S continues.
3 is executed, and the measurement data of the sampling position: S, I corresponding to the counting contents of the sampling counter: X: DX
A determination is made as to whether or not it has been read. Then, in step S3, when it is confirmed that the measurement data: DX has been read, in the following step S4,
After the sampling counter is counted up, step S2 is executed again.

On the other hand, when it is confirmed in step S2 that the count value of the sampling counter: X has reached the set value 2x5 set corresponding to the monitoring start position: S, step S5 is subsequently executed, Sampling counter count value: Sampling position according to χ: Upper limit value at SX: AX□, and each integral value of lower limit value AXmin: Lm
ax and Ixmfr+ are calculated. In addition, these upper limit values: AX, □ and lower limit values: A1, 1, each integral value:
Although IX□8 and Iwmin can be obtained as integral values from the beginning of the monitoring program, here they are obtained as integral values from the monitoring start position: 35.

In step S5, the integral value ' IX 1% IIX+
Iyo,. Once obtained, in the following step S6, similarly to step S3, it is determined whether or not the measurement data DX at the sampling position S corresponding to the count value X of the sampling counter has been read.

Then, when it is confirmed that the measurement data: DX has been read, in the following step S7, the measurement data at the sampling position: S i = integral value of DK: I
is calculated.

In addition, this integral value: I, the above-mentioned upper limit jlti: A
x m□, and each integral value lXf of the lower limit value 'Axmin
Similar to f1aX and Ixmi, it is obtained as an integral value from three monitoring start positions.

When step S7 is completed, step S8 is subsequently executed, and the measurement data calculated in step S7: DX
The integral value of IX is the upper limit value calculated in step S5, the upper limit value of two people
It is determined whether or not it falls within the range defined by TRmX and IX□8.

As a result of the judgment in step S8, the integral value: ■ 8 is the integral value'
1. Ill! If it is determined that it is within the range defined by LX + IX 1li11, then step S9 is executed, but on the other hand, if it is determined that it is not within that range, step S10゜Sll is executed.
will continue to be executed. Then, in step SIO, which is executed when it is determined that the integral value: IX is not within the range defined by the integral values: Ixm□, Ixmtn, the signal is sent to the acoustic alarm 58 etc. An alarm signal is output and the audible alarm 58
etc., it is notified that an abnormality has occurred in the control state, and in the following step Sll, the position of the molded product ejection chute is switched. In other words, the molded products in that molding cycle are guided to the defective product storage container. Note that upon completion of this step S11, step S9 is subsequently executed.

In step S9, the count value of the sampling counter:
It is determined whether x has been reached. As a result of this determination, if it is determined that the count value of the sampling counter: is counted up, and then steps 85 and subsequent steps are repeated.

That is, in the monitoring interval defined by the monitoring start position: S and the monitoring end position: 38, each sampling position 1. s
Measured data at X = D integral values: IX is the upper limit of the allowable range: AX□8 and lower limit: A y m t
It is compared with the integral values of n: Ixmm, +lXll111, and the integral value of the measurement data = D: ■8 is the upper limit of the allowable range: AX□, and the lower limit: AX+++in: ■X□ If the temperature exceeds the range defined by X+ IXII This is how it is supposed to be done.

In addition, in step S9, the count value of the sampling counter: X has already reached its monitoring end position: S.

When it is determined that the set value set corresponding to . Then, in step S13', the count value: X is still the final sampling count value:
If it is determined that the number has not reached n, step S14. S15 is executed and the sampling counter is counted up, but when it is confirmed in this step S13 that the count value of the sampling counter: X has reached the final sampling count value: n, the monitoring program ends.

In this way, even if the integral value of measurement data=DX: IX is compared with each integral value 'IXII□X+lXll111 of the upper limit value of the allowable range, AX, - and lower limit value: AX6.7, the above-mentioned implementation The same monitoring effect as in the example can be obtained. Moreover, the measured data like this:
DX and upper limit of allowable range: AX□8 and lower limit: Ax
By comparing the integral values of DX and mi, erroneous judgments due to instantaneous or temporary deviations from the allowable range of measurement data = DX can be avoided. This will also improve the reliability of the monitoring results.

Note that, as in this embodiment, within the variation interval of the amount of variation to be monitored, the monitoring start position: 38 and the monitoring end position:
When monitoring only a specific section defined by 30, as shown in Fig. 12,
The upper limit value of the allowable range: AX□8 and the lower limit value 'Axm+n are displayed as a trend (pattern display) on the CRT54. Two linear cursors Xi and X2 that can be moved independently are displayed, and the movement position of one cursor X1 is monitored as the starting position:
It is desirable to make the movement position of the other cursor X2 correspond to the monitoring end position: S, . In this case, by setting numerical values for the monitoring start position: Ss and the monitoring end position; can be,
It is also possible to automatically read the sampling position: SX corresponding to the movement position of the cursor X1°X2 on the screen as the monitoring start position: 85 and the monitoring end position: S, respectively.

In addition, as mentioned above, the measurement data: DX is converted into the integral value 2IX
When comparing, as shown in Figure 12, on the screen that displays the trend of the upper limit value of the tolerance range: AXl, It is desirable to display a pattern indicating that there is a certain condition. In addition, FIG. 12 shows an integral operation and its integral operation in an area surrounded by two cursors XI and X2 that are movable in the horizontal axis direction and two cursors Yl and Y2 that are movable in the vertical axis direction. This indicates that monitoring will be carried out based on the following.

Next, an example in which the monitoring operation is performed according to the monitoring program shown in FIG. 13 will be described.

That is, in the flowchart of the monitoring program shown in FIG. 13, when the plasticizing/metering operation is started, first, in step S1, the sampling counter is reset, and in the subsequent step S2, the upper limit of a preset narrow range is set: Ax, X and the lower limit value: Axmin are read. Then, in the subsequent step S3, when it is confirmed that the measurement data: DX at the sampling position: 38 has been sampled, in the subsequent step S4, the measurement data: DX is set to the value preset in the upper limit value: AXsaw: Upper limit of wide range with α added =
(AX□.+α) and the lower limit value of a wide range where α is subtracted from the lower limit value: AX, , , which is preset:
It is determined whether or not it falls within the range defined by (AX□8, -α).

As a result of the determination in step S4, the measurement data =
If it is determined that DX is not between the upper limit value and the lower limit value of the wide range, step S5 is subsequently executed, the molding operation of the injection molding machine is stopped in step S5, and the monitoring program shall be terminated immediately. However, as a result of the judgment, if it is recognized that the measured data: DX is between the upper limit value and the lower limit value of the wide range, step S6 is subsequently executed, and the measured data: DX is the upper limit value of the narrow range. Value: It is determined whether the value is between Ax max and lower limit 'Ax min. Then, if it is recognized that the measurement data: DX is also between the upper limit value of the narrow range: Ax mix and the lower limit value: AX, %, fi, step S7
is executed immediately, and conversely, if it is determined that it is not
Prior to execution of step S7, step S8. S9 is executed and those steps S8. In S9, an alarm signal is output to the acoustic alarm 58, etc., and the molded product discharge chute is moved to a position where the molded product is stored in the defective product storage container, and then step S7 is executed.

In step S7, the count value of the sampling counter:
is compared with the final sampling count: n, and the count:
If is still smaller than the final sampling count value: n, step 310 is executed and the sampling counter is counted up, and then steps 32 and subsequent steps are repeated again, but in this step S7, the count value:
When it is recognized that X matches the final sampling count value: n, the monitoring program ends.

In such a monitoring program, for example, the maximum value and minimum value of the actual measurement value (measurement data) at each sampling position: SX during molding of a non-defective product are set as the upper limit value of the narrow range ' AX ff1llX and the lower limit value: AX Mi
On the other hand, to the extent that normal temporary molding defects occur, the measurement data D is the upper limit of a wide range.
(Ax wax ten α) and the lower limit' (Ax m*
If the value α is set to a value that does not fall outside the range defined by (=n−α) (see FIG. 14), the same monitoring effect as in the embodiment described above can be obtained, and In cases where defective products are continuously molded, the molding operation of the injection molding machine can be automatically stopped, and problems caused by the injection molding machine continuously molding defective products, For example, problems such as wasteful consumption of resin materials, etc.
This can be prevented.

In step S5, instead of immediately stopping the molding operation of the injection molding machine, a command to stop the molding operation is simply issued, and after the molding operation of the molding cycle is completed, the molding operation of the injection molding machine is stopped. It is also possible to do so. In addition, by combining three or more sets of upper and lower limit values, the tolerance range is set in three or more stages, and the injection molding machine takes a different response method each time it falls outside of the tolerance range at each stage. Of course, it is also possible to do so.

The embodiments of the present invention have been described in detail above, but the present invention
It goes without saying that the present invention is not limited to the above-mentioned specific examples, and can be implemented with various changes and modifications based on the knowledge of those skilled in the art without departing from the spirit thereof.

(Effects of the Invention) As is clear from the above description, the present invention provides an upper limit and a lower limit of an allowable range based on measurement data during molding of a non-defective product with respect to the amount of variation that varies depending on the control state of an injection molding machine. is set, and the upper and lower limits of the tolerance range set based on the measurement data when molding a good product are compared with the measurement data of the amount of variation, or their integral value, to determine if the molding operation of the injection molding machine is normal. Therefore, by applying the present invention, it is possible to immediately and accurately detect defects such as the occurrence of defective products or abnormal conditions in the molding operation. Therefore, it becomes possible to immediately deal with the occurrence of such problems.

When setting the upper and lower limits of the allowable range from the measurement data during molding of a non-defective product, a predetermined value is added or subtracted from the median or average value at each sampling position of the measurement data for multiple molding operations. , a method of determining the lower limit value and the lower limit value, a method of setting the maximum value and minimum value at each sampling position of measurement data for a plurality of molding operations as the upper limit value and the lower limit value,
Furthermore, there is a method in which the upper and lower limit values are determined by adding and subtracting predetermined values to the maximum and minimum values at each sampling position of measurement data for multiple molding operations, and measurement data for one molding operation. A method of determining the upper limit value and the lower limit value by adding or subtracting a predetermined value to the above can be suitably employed.

In addition, when setting the upper and lower limits of the allowable range from the measurement data during molding of non-defective products, if the measurement data during molding of non-defective products is superimposed on a predetermined display, it is possible to visually check the degree of variation in the measurement data. Therefore, it is possible to easily set the upper and lower limits of the allowable range to appropriate values, and also to set a linear cursor that can be moved in the time axis direction on the screen. By calculating and displaying the maximum deviation value of the sampling position corresponding to the movement position of the cursor, it becomes easier to set the upper and lower limits of these allowable ranges to appropriate values.

Also, if a display is provided to display the tolerance range, two linear cursors that can be moved in the time axis direction are provided on the display, and monitoring is performed in the control section defined by these cursors. , when monitoring only a specific section, it becomes possible to set the monitoring section extremely easily, and furthermore, it is possible to set the tolerance range in multiple stages and the measurement data is set in the multiple stages. By using different countermeasures depending on the stage of deviation from the tolerance range, it is possible to take the most appropriate countermeasure depending on the degree of the abnormal condition that has occurred, and improve the molding efficiency of the injection molding machine. .

[Brief explanation of the drawing]

FIG. 1 is a system diagram showing an example of an injection molding machine to which the method of the present invention is applied, and FIG. 2 is a flowchart showing a monitoring program in the injection molding machine of FIG. Third
The figure is a diagram showing an example of a CRT screen on which measurement data during molding of a non-defective product is superimposed and displayed when setting the upper and lower limits of the allowable range for the screw rotation speed of the injection molding machine of FIG. FIG. 4 is a diagram for explaining an example of setting an upper limit value and a lower limit value of the allowable range for the screw rotation speed in the injection molding machine of FIG. 1. 5, 6, and 7 are diagrams corresponding to FIG. 3 regarding the back pressure, retraction speed, and rotational torque of the injection screw in the injection molding machine of FIG. 1, respectively. FIG. 8, FIG. 9, and FIG. 10 are diagrams corresponding to FIG. 4 for explaining other setting examples of the upper limit value and lower limit value of the allowable range, respectively. FIG. 11 shows a second embodiment for explaining another embodiment of the present invention.
FIG. 12 is a diagram showing a display example of a cursor for defining a monitoring section on a CRT screen. FIG. 13 is a diagram corresponding to FIG. 2 of still another embodiment of the present invention, and FIG. 14 illustrates an example of setting the upper and lower limits of the allowable range in the embodiment of FIG. 13. FIG. 4 is a diagram corresponding to FIG. 10: Injection screw 14: Hydraulic motor 16: Injection cylinder 28: Electromagnetic proportional flow control valve 30: Electromagnetic proportional pressure control valve 32: Position sensor 38: CPU 40.50: Oil pressure sensor

Claims (10)

[Claims] (1) Measured data obtained at predetermined sampling intervals according to the actual molding operation of the injection molding machine, and the measured data regarding the amount of fluctuation that varies depending on the control state of the injection molding machine in any control section of the injection molding machine. When monitoring the control state of the injection molding machine in the control interval by successively comparing the upper and lower limits of the tolerance range set in advance corresponding to each sampling position, The storage means is configured to store measurement data during molding of a good product, and the upper and lower limits of the allowable range are set based on the measurement data during molding of a non-defective product stored in the storage means. A method for monitoring the control status of an injection molding machine. (2) An integral value of measurement data obtained at a predetermined sampling interval according to the actual molding operation of the injection molding machine, regarding the amount of variation that varies depending on the control state of the injection molding machine in any control section of the injection molding machine; When monitoring the control state of the injection molding machine in the control section by successively comparing the integral values of the upper limit value and lower limit value of the tolerance range preset corresponding to each sampling position of the measurement data, Regarding the amount of variation, measurement data during molding of a good product through actual molding operations is stored in a storage means, and upper and lower limit values of the allowable range are set based on the measurement data during molding of a non-defective product stored in the storage means. A method for monitoring the control status of an injection molding machine, characterized in that: (3) The measurement data during molding of a non-defective product regarding the amount of variation is stored in the storage means for a plurality of molding operations, and the average value or median value at each sampling position of the measurement data for the plurality of molding operations is calculated. The value obtained by adding a predetermined value to the average value or median value is set as the upper limit value of the tolerance range, and the value obtained by subtracting the predetermined value from the average value or median value is set as the lower limit value of the tolerance range. 3. The monitoring method according to claim 1, wherein the monitoring method is configured to cause the setting to be made. (4) The measurement data during molding of a non-defective product regarding the amount of variation is stored in the storage means for a plurality of molding operations, and the maximum and minimum values at each sampling position of the measurement data for the plurality of molding operations are stored. 3. The monitor according to claim 1, wherein the maximum value thereof is set as the upper limit value of the permissible range, and the minimum value thereof is set as the lower limit value of the permissible range. Method. (5) The measurement data during molding of a non-defective product regarding the amount of variation is stored in the storage means for a plurality of molding operations, and the maximum and minimum values at each sampling position of the measurement data for the plurality of molding operations are stored. A value obtained by adding a predetermined value to the maximum value is set as the upper limit of the tolerance range, and a value obtained by subtracting a predetermined value from the minimum value is set as the lower limit of the tolerance range. The monitoring method according to claim 1 or 2, characterized in that: (6) A value obtained by adding a predetermined value to the measurement data for one molding operation during molding of a non-defective product stored in the storage means is set as the upper limit of the tolerance range, and a predetermined value is set from the measurement data. 3. The monitoring method according to claim 1, wherein a value obtained by subtracting the value is set as the lower limit value of the allowable range. (7) The upper and lower limits of the allowable range can be set while the measurement data during molding of non-defective products stored in the storage means are displayed superimposed on a predetermined display. A monitoring method according to any one of claims 1 to 6. (8) A linear cursor that can be moved arbitrarily in the time axis direction of the measured data is provided on the display on which the measured data is superimposed, and the median value of the measured data at the sampling position corresponding to the moving position of the cursor is provided. 8. The monitoring method according to claim 7, further comprising the step of calculating and displaying a maximum deviation value with respect to the maximum deviation value. (9) A display is provided for displaying the permissible range, and two linear cursors that can be moved arbitrarily in the time axis direction are provided on the display, and the control is performed in the control section defined by these cursors. 9. A monitoring method according to any one of claims 1 to 8, characterized in that a state is monitored. (10) The tolerance range is set in multiple stages, and the injection molding machine takes appropriate action according to the stage in which the measurement data obtained in accordance with the actual molding operation regarding the amount of variation deviates from the tolerance range set in the multiple stages. A monitoring method according to any one of claims 1 to 9, characterized in that the methods are different.