JPH0780905A - Discriminating method of quality of product of injection molding machine - Google Patents

Abstract

PURPOSE:To eliminate discrepancy in timing between output of a defective signal of a product and actual generation of a defective product, by a method wherein an injection number of times until measured resin is injected afresh within an injection cylinder is obtained, after detection of disorder in measurement, the defective signal of the product is output to a molding cycle wherein injection actions of a set up injection number of times are performed. CONSTITUTION:A number of injection times m until a measured resin is injected first within an injection cylinder 1 and the number of injection times n until the resin is discharged completely are obtained and their values are set up beforehand in a nonvolatile memory 24. When disorder in measurement is detected, a control device 10 watches and waits output of a defective signal of a product until a molding cycle of set up number of injection times is performed, that is, until injection of the measured resin is started afresh within the infection cylinder 1. Then when the molding cycle of the set up number of the injection times is performed and injection of the measured resin within the injection cylinder is started afresh, the defective signal of the product is output by corresponding to the molding cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a product quality determination method for an injection molding machine, and more particularly to an improvement of a product quality determination method for an injection molding machine that determines quality of a product based on an abnormality of a variable detected in a weighing process.

[0002]

2. Description of the Prior Art Abnormality of plasticization of resin and mixing of foreign substances in the weighing process have a great influence on the molding of a product, and in order to reliably and automatically judge the quality of the molded product, these abnormalities must be properly identified. It is desired to detect it. Therefore, in order to meet such demands, variables that change due to abnormal plasticization, mixing of foreign matter, and the like, such as required time for measurement, measurement completion position, driving torque of screw rotation servo motor, injection cylinder temperature, injection cylinder ON / OFF of heater
A product of an injection molding machine that detects the condition, screw retreat speed, etc., and compares these values with preset reference values to detect the presence or absence of measurement abnormality and automatically determine the quality of the product. The method for determining the quality is already in Japanese Patent Application No. 5-9.
No. 0525 and Japanese Patent Application No. 5-110072 have been proposed by the present applicants.

[0003]

According to these product quality determination methods, it is possible to accurately detect the presence or absence of a measurement abnormality occurring in each molding cycle, and in particular, the product to be molded is relatively large. In this case, that is, in the molding work in which the volume of the mold cavity is large due to the ratio of the cushion amount and the volume of the mold cavity, and most of the resin measured in the measuring step is discharged in the next one injection operation. The quality of the product can be accurately determined by immediately determining the occurrence of the molding abnormality upon the occurrence of the measurement abnormality.

However, when the product to be molded is a small item,
In other words, if the cushion amount is relatively large in terms of the ratio between the cushion amount and the mold cavity volume, there is no guarantee that most of the resin measured in the measuring process will be discharged in the next injection operation. 1 The resin required for the injection operation may be covered by the residual amount of the resin measured in the previous measurement process, so that the abnormality in the measurement process is not always detected in the next injection process. Abnormality does not always occur in the molded product. In other words, the resin supplied from the hopper and kneaded in the flight part of the screw is not immediately supplied to the screw tip, but reaches the screw tip while passing through the flight part of the screw by repeating the measurement several times. However, there is a delay before the measured resin is actually injected. Hereinafter, this point will be described with some examples.

FIG. 7 is a sectional view showing an example of the state inside the injection cylinder in the weighing process. For example, when a new weighing operation is performed with a cushion amount equal to or more than the amount of resin discharged in one injection operation, the weighing completed state as shown in FIG. 7 is reached, and the weighing process is performed in this weighing process. It is assumed that an abnormality is detected. That is, this is an example of the case where the measurement abnormality is detected when the cushion amount is relatively large in terms of the ratio between the cushion amount and the volume of the mold cavity. In the above-mentioned prior art, since the molding abnormality is immediately treated as the occurrence of the molding abnormality, the product defect signal is output for the next injection operation. However, the injection is actually performed in the next injection operation. The resin is the cushion amount part, that is, the part where the kneading has already been completed by the previous weighing operation, so if there is no weighing abnormality at the previous weighing stage, it will be normal by the next injection operation. Various products can be molded. Therefore, in this case, there is a problem that a defective product signal is output even though the normal molding operation is performed, and a non-defective product is determined as a defective product. That is, in the example of FIG. 8, the product defect signal is output to the product molded at the timing B of the injection operation that comes after the time A when the occurrence of the measurement abnormality is detected. Since the product molded at the timing B is normal, this misjudgment deteriorates the yield of the resin used as the product. Such a problem is that in the above-mentioned conventional technology, it is possible to detect only the measurement abnormality that occurs in the flight part of the screw, and based on this abnormality detection,
This is because the product defect signal is output regardless of what kind of resin remains at the screw tip as the cushion amount.

Then, an actual defective product will be generated in the injection process further than B, for example, at the timing of C-D, etc. However, the product defect signal will be output unless a measurement abnormality is detected in the immediately preceding measurement process. Since it is not output, there is no guarantee that a product defect signal will be output at the timing such as C-D when a defect actually occurs, and a misidentification of a defective product as a non-defective product occurs, so that the defective product is mixed into the non-defective product. There is also a fear. In such a case, the reason why the measurement abnormality is not detected despite the fact that the resin having the plasticization abnormality remains at the tip of the injection cylinder is because the phenomenon opposite to the above occurs. For example, a normal measurement and kneading operation of a new resin is newly started from the state of FIG. 7 while leaving a resin having abnormal plasticization, which is equal to the amount of resin discharged in one injection operation, as a cushion amount at the tip of the injection cylinder. And Then, in this case, only the newly supplied normal resin comes into contact with the flight part of the screw having the kneading action, and the abnormally plasticized resin remaining at the tip of the injection cylinder comes into contact with the screw tip. Only. That is, even if the resin with abnormal plasticization is in contact only with the tip of the screw, the influence of the resin is not so large as to affect the driving torque of the screw rotation servomotor or the like. Therefore, it is extremely difficult to detect this as a measurement abnormality. In short, the means for detecting the measurement abnormality reacts only to the measurement abnormality occurring in the flight part of the screw, and therefore the abnormality of the resin remaining at the tip of the screw cannot be detected. In other words, it is difficult to detect the local plasticization abnormality of the resin in the injection cylinder by the conventional technique.

Therefore, when molding a small product having a relatively large cushion amount in view of the ratio between the cushion amount and the volume of the mold cavity, that is, the resin remaining on the flight part of the screw and the tip of the injection cylinder remains. When the volume of the product is several times and the once kneaded resin is injected in several times, it is very difficult to detect the abnormality of the product only by the conventional technique. Actually, even when the injection operation for each shot is performed using the same abnormal resin, as the ratio of the normal resin in the injection cylinder increases, that is, by the new measurement operation. As the proportion of injected normal resin increases, there is a problem that it becomes more difficult to detect an abnormality in the injection cylinder.

That is, such a problem is that the resin to be injected, which has been accumulated at the tip of the screw due to the measurement before the previous time, and the resin of the new measurement amount which is kneaded at the flight part of the screw, are caused in the injection cylinder. Yes, despite the fact that the resin actually injected is the resin stored at the tip of the screw, the product failure signal is output based on the error that occurs in the flight part of the screw, resulting in the detection of the error and the actual This is because there is a time lag between the occurrence of defects and the product defect signal is output earlier than the actual occurrence of defects.

Therefore, an object of the present invention is to eliminate the timing deviation between the output of the product defect signal and the actual occurrence of the product defect, and to accurately output the product defect signal according to the product defect. In addition, even if the plasticization abnormality of the resin locally occurs in the injection cylinder, it is possible to accurately predict the abnormality of the product caused by the resin having the plasticization abnormality and determine the quality of the product. An object of the present invention is to provide a product quality determination method for an injection molding machine.

[0010]

According to the method for determining product quality of an injection molding machine according to the present invention, the presence or absence of measurement abnormality is detected by comparing a variable detected in a weighing process with a preset reference value. In the product quality determination method of the injection molding machine described above, the number of injections until the newly measured resin is injected into the injection cylinder is obtained and set in advance in the control device of the injection molding machine, and the measurement abnormality is detected. Then, after the measurement abnormality is detected, the product defect signal is output for the molding cycle in which the injection operation of the set number of injections is executed, so that the timing of the output of the product defect signal and the occurrence of the actual product defect. By eliminating the deviation, the erroneous discrimination regarding the quality of the product is eliminated.

Further, when the number of injections until the resin newly measured in the injection cylinder is completely discharged by the injection is obtained and set in advance in the control device of the injection molding machine, and the measurement abnormality is detected. After the measurement abnormality is detected, the product defect signal is output until the number of injections exceeds the set number of injections, so that all the products that may contain a small amount of resin measured in the measurement process in which the abnormality occurs are not detected. Treated as good product,
Improved the sorting accuracy of defective products.

Further, the first number of injections until the resin newly measured in the injection cylinder is first injected and the second number of injections until the resin is completely discharged by the injection are obtained. If the measurement abnormality is detected by setting in the control device of the injection molding machine in advance, a product defect occurs after the measurement abnormality is detected and the number of injections is counted from the first injection number to the second injection number. Due to the configuration that outputs a signal, only the products molded with the resin newly kneaded in the abnormal measuring process are treated as defective products, improving the sorting accuracy of defective products and improving the resin yield.

[0013]

The number of injections until a new measured resin is injected into the injection cylinder is obtained in advance by an experimental method and set in the controller of the injection molding machine. The injection molding machine is continuously operated, and the required time for measurement, the measurement completion position, the driving torque of the screw rotation servo motor, the temperature of the injection cylinder, the ON / OFF state of the injection cylinder heater, and the screw retreat speed in the measurement process of each molding cycle. The presence or absence of the measurement abnormality is detected in the same manner as in the conventional method by detecting the above and comparing the same with the reference value. When the measurement abnormality is detected, the control device of the injection molding machine causes a product defect until the molding cycle for the number of injections is executed, that is, until the injection of the resin newly measured in the injection cylinder is started. When the signal output is awaited and the molding cycle for the number of injections is executed to newly start the injection of the resin measured in the injection cylinder, a product defect signal is output corresponding to the molding cycle.

Further, the number of injections until the resin newly measured in the injection cylinder is completely discharged by injection is obtained in advance by an experimental method and set in the controller of the injection molding machine. In this case, the control device of the injection molding machine, which has detected the occurrence of the measurement abnormality in the same manner as described above, starts the output of the product defect signal from the injection step subsequent to the measurement step in which the generation of the measurement abnormality is detected, and the number of injections is Until the set number of shots is exceeded,
In other words, the product defect signal is output until the resin newly measured in the injection cylinder is completely discharged, and all the products that may contain a small amount of the resin measured in the measuring process in which an abnormality has occurred are rejected. Treat as good product.

Further, the first injection number until the first injection of the resin newly measured in the injection cylinder and the second injection number until the resin is completely discharged by the injection are experimentally determined. It is obtained in advance by various methods and set in the control device of the injection molding machine. In this case, the control device of the injection molding machine, which has detected the occurrence of the measurement abnormality, outputs a product defect signal between the first injection number and the second injection number after the measurement abnormality is detected, Only the products directly molded from the newly kneaded resin in the abnormal measurement process are treated as defective products.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a main part of an injection molding machine of an embodiment to which a product quality determination method of the present invention is applied. Reference numeral 1 is an injection cylinder of the injection molding machine, and reference numeral 2 is a screw. The screw 2 is driven in the injection axis direction by the injection servomotor M1 via a drive converter 5 for converting the axial rotation of the drive source into a linear motion in the injection axis direction, and also the screw 2 via the gear mechanism 3. It is adapted to be metered by a rotation servomotor M2. A pressure detector 4 is provided at the base of the screw 2, and the resin pressure acting in the axial direction of the screw 2, that is, the injection holding pressure in the injection holding process and the screw back pressure in the measuring process are detected. The injection servomotor M1 is provided with a pulse coder P1 for detecting the position and moving speed of the screw 2, and the screw rotation servomotor M2 is provided with a speed detector P2 for detecting the rotation speed of the screw 2. It has been deployed. Reference numeral 6 denotes a hopper detachably attached to the injection cylinder 1, which communicates with the inside of the injection cylinder 1 and supplies a pellet of resin as a molding material to the injection cylinder 1. A slide opening / closing shutter is provided at the base of the hopper 6, and the supply of pellets to the injection cylinder 1 can be arbitrarily stopped.

The control device 10, which also serves as a product quality determination device of the injection molding machine, includes a CNC CPU 25 which is a numerical control microprocessor, a PMC CPU 18 which is a programmable machine controller microprocessor,
Servo CPU, which is a microprocessor for servo control
20 and a pressure monitoring CPU 17 for performing sampling processing of injection holding pressure and screw back pressure, and information can be transmitted between the microprocessors by selecting mutual input / output via the bus 22. It has become.

The PMC CPU 18 has a ROM storing a sequence program for controlling the sequence operation of the injection molding machine, a control program for determining the quality of the product, and the like.
13 and RAM used for temporary storage of operation data
14 is connected to the RAM 14 by the initialization process of the PMC CPU 18 at the time of power-on, which corresponds to the output value of the product defect signal corresponding to the address value i representing the number of executions of the molding cycle. Or 1
A file (see FIG. 6) for storing up to N 1-bit binary data of is set. On the other hand, C for CNC
Connected to the PU 25 are a ROM 27 that stores a program for controlling the injection molding machine as a whole and a RAM 28 that is used for temporary storage of calculation data.

Further, each of the servo CPU 20 and the pressure monitoring CPU 17 stores a ROM 21 storing a control program dedicated to servo control, a RAM 19 used for temporary storage of data, and a control program relating to sampling processing of molding data and the like. The ROM 11 and the RAM 12 used for temporary storage of data are connected. Further, the servo CPU 20 is connected to a servo amplifier 15 for driving a servo motor of each axis for mold clamping, ejector (not shown) and injection, screw rotation, etc. based on a command from the CPU 20. Each of the outputs from the pulse coder P1 provided in the injection servo motor M1 and the pulse coder P2 provided in the screw rotation servo motor M2 is fed back to the servo CPU 20, and the screw calculated by the servo CPU 20 based on the feedback pulse from the pulse coder P1. The current position 2 and the rotation speed of the screw 2 detected by the speed detector P2 are stored in the current position storage register and the current speed storage register of the memory 19, respectively.

The non-volatile memory 24 stores molding conditions (injection pressure maintaining condition, measuring condition, etc.) related to the injection molding work, various set values, parameters, macro variables and setting data for determining quality, for example, an upper limit allowance of the measuring completion position. It is a memory for storing molding data that stores the value SH, the lower limit allowable value SL, the upper limit allowable value RH of the required measuring time, the lower limit allowable value RL, etc. in the same manner as in the conventional case. Further, in the present embodiment, the injection cylinder 1 Values such as the number of injections m until the first measured amount of the resin weighed therein and the number of injections n until the resin is completely discharged are displayed.
The setting and input is made by the operator's hand by using the function keys 9 and ten keys.

Therefore, the operator mounts the mold to be molded into the injection molding machine and experimentally performs injection molding work in advance according to predetermined molding conditions, whereby the resin measured in the injection cylinder 1 is measured. Of the number of injections until the resin is first ejected, the number of injections n until the resin is completely ejected, etc.
These values are set in advance in the non-volatile memory 24 by using the function keys, numeric keys, etc.

An experiment for obtaining the number of injections m and the number of injections n can be performed as follows.

First, the resin pellets are loaded into the hopper 6 with the mold to be subjected to the molding operation mounted on the injection molding machine, and the screw rotation speed, the cushion amount, the back pressure, the measurement completion position, and the temperature of the injection cylinder. Various molding conditions such as measurement conditions are set under the same conditions as in mass production. Then, the injection molding machine is allowed to continuously perform automatic operation until the molding operation becomes stable, and the injection molding machine is stopped at the time before the start of weighing after the completion of the holding pressure in any molding cycle after the molding operation has stabilized, Remove all pellets in hopper 6. However, it is actually difficult to remove all the pellets in the hopper 6 in a short time. Therefore, as a practical means, the hopper 6 can be completely removed in advance and another method, for example, by hand. The injection molding operation is performed so that the pellets can be stably supplied to the injection cylinder 1, and the pellet supply is immediately stopped when the injection molding machine is stopped when the above-described conditions are satisfied. Excess pellets are removed from the connection with the hopper 6, and pellets are removed from the base of the injection cylinder 1 as much as possible. In this state, the injection cylinder 1
The resin and screw 2 corresponding to the cushion amount.
The resin that is present between the flight part and the inner peripheral surface of the injection cylinder 1, that is, the resin that has not been discharged in the previous injection operation, for example, the resin of the volume M remains.

Next, the pellets can be stably supplied to the injection cylinder 1 again, pellets of a color different from that in the first automatic operation are supplied, and the injection molding machine is made to perform one weighing operation. In this state, the injection cylinder 1 is newly filled with the resin (volume M) that has not been discharged in the previous injection operation, in addition to the resin corresponding to one metering operation, for example, the resin of the volume N, and as a whole. , M + N volume of resin will be filled.

Then, the excess pellets are completely removed again in the same manner as described above, the stable continuous supply of the pellets having a color different from the excess pellets is started, and the injection molding machine is again brought into the automatic operation state.

Then, the number of executions of the molding cycle which is repeated continuously is counted, and the molding color of the product ejected from the mold is monitored every execution of each molding cycle, and the color is the pellet in the first automatic operation. The number of executions of the molding cycle when the color of the pellet changes to the color of the pellets supplied for the one-time weighing operation, that is, the number of executions of the molding cycle when the discharge of the resin corresponding to the volume M is completed. Obtained and recorded as the number of injections m.

Next, the next molding cycle is started with an initial value of 1.
Counting is restarted, and the number of executions of the molding cycle when the molding color of the product ejected from the mold changes from the color of the pellets supplied for the one-time weighing operation to another color, that is, the volume N The number of executions of the molding cycle from the start of the discharge of the resin corresponding to
Record as the number of injections n.

In this case, the number of injections m is the number of injections after the completion of one metering operation until the resin newly metered by the metering operation is injected for the first time, and the number of injections n is 1 This is the number of injections required from the start of the injection of a newly measured resin by one measurement operation to the complete discharge of this resin.

In addition, by intentionally making some of the weighing conditions unsuitable during the automatic operation, and monitoring the number of molding cycles after which the actual product failure occurs, the residual volume M It is possible to obtain the number of injections at the time when the discharge of the resin corresponding to the above is completed, that is, the value of the number of injections m until the discharge of the resin for the new measurement is started. In this case, after the weighing operation under the intentionally unsuitable weighing conditions is completed and before the next weighing operation is started, the weighing conditions are optimized again, and the product defect is eliminated and then solved. By measuring the number of executions of the molding cycle up to, it is possible to obtain the value of the number of injections n until the discharge of the resin for the new measurement corresponding to the volume N is completed. The items of the measurement conditions to be unsuitable include the screw rotation speed, the cushion amount, the back pressure, the measurement completion position and the temperature of the injection cylinder 1, etc., but the cushion amount and the measurement completion position are items directly related to the measurement volume. Yes, again
The temperature of the injection cylinder 1 takes time to change and recover,
Moreover, regardless of whether it is a residual amount or a new measured amount, all the resins in the injection cylinder 1 are adversely affected when the temperature changes, which is not desirable as an unsuitable element. It is desirable to select items that do not directly affect the measurement volume, such as screw rotation speed and back pressure, and that are easy to fluctuate and recover, as targets for immobilization.

Further, instead of making the measuring conditions themselves unsuitable, the molding material is made unsuitable to detect abnormalities such as the required time for measurement, the measurement completion position, the driving torque of the screw rotation servomotor, and the screw retreat speed, and the abnormality is detected. The number of injections m until the discharge of the resin corresponding to the residual volume M is completed is also monitored by monitoring the number of injection operations after which the actual product failure occurs. You can However, in order to obtain the value of the number of injections n until the discharge of the resin for the new measurement corresponding to the volume N is completed, the once-unsuitable condition is set to 1 as in the method by the unsuitable measuring condition. Since it is necessary to optimize immediately after the completion of the metering operation, the switching operation of the supplied resin is required as in the case of the experiment utilizing the change of the molding color described above. In this case, the supplied resin is switched in the order of good material such as virgin pellets, poor quality material such as recycled material of poor grade, and good material.

The interface 23 is an input / output interface for receiving signals from limit switches and operation panels provided in various parts of the injection molding machine and for transmitting various commands to peripheral equipment of the injection molding machine.

Then, the CNC CPU 25 uses the ROM 27
Based on the control program described above, pulses are distributed to the servo motors of the respective axes, and the servo CPU 20 moves the pulses distributed to the respective axes and the positions detected by the detectors such as the pulse coder P1 and the speed detector P2. Based on the feedback signal and the speed feedback signal, servo control such as position loop control, speed loop control and current loop control is performed as in the conventional case, and so-called digital servo processing is executed.

The manual data input device 29 with a display is connected to the bus 22 via the CRT display circuit 26 so that a monitor display screen, a function menu can be selected and various data can be input. A numeric keypad and various function keys are provided.

2 to 5 are flow charts showing the outline of the sequence control executed by the PMC CPU 18, and the quality judgment of the product in this embodiment will be described below with reference to these flow charts.

The PMC CPU 18 first sets the file shown in FIG. 6 in the RAM 14 in the initialization process when the power is turned on, initializes all the output data of the product defect signal in the file to 0, and the address search index i
After initializing the values of the required measurement time storage register Rt (step S1), a standby state waiting for the input of the cycle start signal is entered (step S2).

The cycle start signal referred to here is an operation signal from a semi-automatic operation switch of an operation panel provided in the injection molding machine body in the case of semi-automatic operation, and a mold from the CNC CPU 25 during automatic operation. This is an opening completion signal. That is, when the semi-automatic operation switch is operated, the PMC CPU 18 sets the step S
The operation of the injection molding machine is stopped (semi-automatic operation) when the mold opening operation is completed by performing the processing of 3 to step S31 once (automatic operation of the operation panel while the semi-automatic operation is performed). When the switch is operated, continuous operation is automatically started, and the PMC CPU 18 detects the mold opening completion signal from the CNC CPU 25 in the process of step S2, and the processes of steps S3 to S31 are repeatedly executed. (Automatic operation).

In order to start the continuous operation, it is essential to operate the automatic operation switch during the execution of the semi-automatic operation, and in order to start the semi-automatic operation,
By manually outputting a command to the screw rotation servomotor M2 to cause the screw 2 to perform a metering rotation operation, the screw 2 is retracted at least to the rear of the metering completion position set as the molding condition, and injection is performed. The resin required for operation must be filled in the injection cylinder 1.

Below, the outline of the sequence control and the product quality judgment will be explained assuming that the continuous operation of the injection molding machine has already started.

Therefore, the PMC CPU 18, which has detected the input of the cycle start signal, firstly sends the CNC CPU 2
5, a mold closing command is output to the CPU 5 (step S3), and the CPU 2
5 and the servo CPU 20 drive-control the mold clamping servomotor in the same manner as in the conventional case, thereby causing the mold clamping servomotor at the mold opening completion position to perform the mold closing and mold clamping processes, and the CNC CPU 25 A standby state waiting for the input of the mold clamping completion signal is entered (step S4).
When the input of the mold clamping completion signal is detected, the PMC
The CPU 18 reads the screw current position Sn from the screw current position storage register of the RAM 19 (step S5), and stores this value in the measurement completion position storage register Smax. As the measurement completion position (step S6).

The screw rotation servomotor M2
Has already been completed by the processing of steps S27 to S29 in the immediately preceding molding cycle, and the value of the required measurement time required for the weighing processing at this time is also in step S25 in the immediately preceding molding cycle.
And it is stored in the required measurement time storage register Rt by the processing of step S30. In the processing of step S6 in the current molding cycle, the measurement completion position storage register S
It is desirable that the value stored in max. is the same value as the set measurement completion position SB, which is the target position for screw retreat in the process of steps S27 to S29 in the immediately preceding molding cycle, Since a certain amount of time elapses from the completion of weighing in to the completion of mold clamping in the current molding cycle, if plasticization of the resin progresses during this period and the volume of the resin decreases, the set weighing is completed. There may be a difference between the position SB and the value of the weighing completed position storage register Smax. This is a kind of weighing error.

The PMC CPU 18 having the screw present position Sn stored in the measurement completion position storage register Smax., Then outputs an injection start command to the CNC CPU 25 and outputs C
By driving and controlling the injection servomotor M1 by the PU 25 and the servo CPU 20 in the same manner as in the conventional case,
The pressure holding process is completed by performing the respective processes of the injection and the pressure holding process (step S7).

Next, the PMC CPU 18 allows the upper limit allowable value SH and the lower limit allowance SH set in the non-volatile memory 24 to determine whether the value of the weighing completion position stored in the weighing completion position storage register Smax. It is determined whether or not the value is within the value SL (step S8), and if this condition is satisfied, the value of the required measurement time stored in the required measurement time storage register Rt is further used to determine whether the measurement operation is good or bad. Therefore, it is determined whether or not it is between the upper limit allowable value RH and the lower limit allowable value RL set in the nonvolatile memory 24 (step S).
9).

That is, only when both the determination conditions of step S8 and the determination condition of step S9 are satisfied, the plasticity abnormality is newly detected in the resin newly measured by the processing of steps S27 to S29 in the immediately preceding molding cycle. Means that there is no plasticization abnormality in the resin newly measured in the immediately preceding molding cycle unless either the determination condition of step S8 or the determination condition of step S9 is satisfied. To do. Here, only the measurement completion position and the time required for weighing are explained as the detection items for the measurement abnormality, but as already explained, other items for detecting the presence or absence of the measurement abnormality include screw rotation. There are drive torque of the servo motor M2 for injection, the temperature of the injection cylinder 1, the ON / OFF state of the heater in the injection cylinder 1, the retreat speed of the screw 2, etc., and some of these items in addition to the determination conditions of step S8 and step S9. Or adding, and
It is free to arbitrarily select the number and combination of items to be the discrimination conditions and substitute them for the discrimination conditions of step S8 and step S9.

Therefore, step S8 or step S
When the determination result of 9 is false, that is, when it is determined that the resin newly measured by the processing of steps S27 to S29 in the immediately preceding molding cycle has a plasticization abnormality, the PMC CPU 18 determines Step S
A file for processing as a defective product by shifting to the process of 10 and only the product molded by the resin directly kneaded in the measuring step of the immediately preceding molding cycle among the resins currently filled in the injection cylinder 1 Setting operation (in short, setting operation when only the product molded in the molding cycle from C to D in the example of FIG. 8 is defective, that is, the setting operation corresponding to claim 3), or injection at the present time File setting operation for treating all products molded by the resin filled in the cylinder 1 as defective products (in short, considering the adverse effect of the new measuring resin on the residual resin, molding from B to D in the example of FIG. 8). The setting operation for making all the molded products defective in the cycle, that is, the setting operation corresponding to claim 2, is started.

Note that the processing itself of the PMC CPU 18 is exactly the same regardless of which file setting operation is performed, and which file setting operation is performed is determined by the above-mentioned experiment or calculation. It depends on how the number of times m and the number of times of injection n are set in the nonvolatile memory 24.

That is, if the values of the number of injections m and the number of injections n obtained by the experiment are directly registered in the non-volatile memory 24, the resin filled in the injection cylinder 1 at the present time is measured in the last measuring step of the molding cycle. A file setting operation is performed to treat only the product molded by the directly kneaded resin as a defective product, and the value of m is set regardless of the values of the injection number m and the injection number n obtained by the experiment. While registering 0 in the non-volatile memory 24, the sum of the number of injections m and the number of injections n obtained by the experiment is registered in the non-volatile memory 24 as the value of n. A file setting operation is performed to treat all the molded products as defective products. Hereinafter, the values of m and n registered in the non-volatile memory 24 will be referred to as the registered value m and the registered value n, and will be used separately from the injection number m and the injection number n obtained by the experiment. In short, the registered value m is a value indicating how many cycles ahead the product defect signal is output based on the molding cycle in which the measurement abnormality has occurred, and the sum of the registered value m and the registered value n is the measured value. It is a value indicating how many cycles ahead the output of the product defect signal is continued based on the molding cycle in which the abnormality has occurred.

Therefore, the PMC 18 first adds the current value of the address search index i representing the current injection execution count to the registered value m and the registered value n, and stores the value in the abnormal output continuation limit storage register P. While storing (step S1
0), the current value of the address search index i and the registered value m are added, and the value is stored in the abnormal output start cycle storage register k as an initial value (step S11).

The value of the address search index i is determined in step S1.
By the processing shown in steps S22 to S24, the minimum value 1 is obtained every time one molding cycle is executed.
To the maximum value N in a cyclic manner, and the present value represents the number of executions of the molding cycle. Its maximum value N
Is equal to the data storage capacity N of the file of FIG. 6 which stores 1-bit binary data of 0 or 1 corresponding to the output timing of the product defect signal corresponding to the address value i representing the number of executions of the molding cycle. Therefore, if the value of N is infinite, a value requesting output of a product defect signal from the kth address to the Pth address of the file of FIG. 6 according to the value calculated in the processing of steps S10 and S11. 1 is set, and in the subsequent molding cycle, the current value of the address search index i is detected for each molding cycle,
Whether or not to execute the output of the product defect signal may be determined depending on whether 1 is set in the i-th address of the file in FIG. However, in reality, since the value of N in the file of FIG. 6 is finite, it is impossible to store execution / non-execution of the output of the product defect signal for all the molding cycles that can be executed. It becomes necessary to cyclically use the above files.

Therefore, P in which the initial value is set in the register k
The MC CPU 18 determines whether or not the current value of the register k has reached the value of the abnormal output continuation limit storage register P (step S12), but at the present stage immediately after the completion of the initial setting operation for the register k. Then, the current value [i + registered value m] of the register k is obviously the value [i + of the register P]
Registration value m + registration value n] is not satisfied. Therefore, C for PMC
The PU 18 will determine whether or not the value of the register k exceeds the maximum value N of the data storage numbers in the file of FIG. 6 (step S13). Here, if the current value of the abnormal output start cycle storage register k does not exceed the maximum value N of the data storage numbers in the file of FIG. 6, it represents the number of executions of the molding cycle for starting the output of the product defect signal. The value of the register k can be stored as the value as it is. Therefore, when the determination result of step S13 is false, the PMC CPU 18 sets 1 in the data storage area of the kth address in the file of FIG. 6, and the number of injection executions represented by the kth address of the file. The molding cycle corresponding to is stored as the timing at which the product defect signal is first output (step S1).
5). That is, the file of FIG. 6 is set so that the product defect signal is output when the injection operation is performed m times, which is the registered value, counted from the current molding cycle.

On the other hand, when the determination result of step S13 is true, that is, when the current value of the abnormal output start cycle storage register k exceeds the maximum value N of the data storage numbers in the file of FIG. 6, It is impossible to store the value k representing the number of executions of the molding cycle for starting the output of the product defect signal as it is in the file of FIG.

Therefore, the PMC CPU 18 executes the process of step S14 before executing the process of step S15, and sets the value k representative of the number of executions of the molding cycle in which the product defect signal is first output as shown in FIG. Will be newly obtained in correspondence with the allowable range of the number of data in the file. As already described, the address search index i corresponding to k is reset to 1 again when its value exceeds N, so that when k> N, it corresponds to the kth molding cycle counted from the beginning. If you want to know the value of the index i
It is sufficient to find the value of -N. The value of the index i thus obtained is exactly the value k representing the number of executions of the molding cycle for starting the output of the product defect signal in the file of FIG.
Sets the value of k−N in the abnormal output start cycle storage register k (step S14). Correspondingly, the value of the abnormal output continuation limit storage register P is P
It is corrected to -N (step S14). Strictly speaking
In this process, the value of P obtained in step S10 and the value of k obtained in step S11 are 2N ≧ P> N, 2.
Although it is applied only in the range of N ≧ k> N, the upper limit value of i is restricted to N, and the value of N itself is smaller than the registered value m and the registered value n set in the nonvolatile memory 24. Since it is set to a sufficiently large value, k> 2N or P> 2N
And no inconvenience will occur.

Then, the PMC CPU 18 which has completed the processing of step S14 carries out step S1 in the same manner as described above.
5 is executed, 1 is set in the data storage area of the kth address in the file of FIG. 6, and the kth address of the file is set.
The molding cycle corresponding to the number of injection executions represented by the address is stored as the timing at which the product defect signal is first output (step S15). That is, for the file in FIG. 6, counting from the current molding cycle i (N−i) +
(K−N) = k−i = settings are set so that a product defect signal is output when the injection operation is performed m times for the registered value. The value of k used in the above equation is a value before being corrected in the process of step S14.

The PMC CPU 18 which has completed the processing of step S15 increments the value of the abnormal output start cycle storage register k (step S16), and thereafter, the current value of the abnormal output start cycle storage register k is changed to the abnormal output continuation limit storage register. Until the value of P is reached or the maximum value N of the number of stored data in the file of FIG. 6 is reached, the processes of steps S12 to S16 except the process of step S14 are repeatedly executed in the same manner as described above. 1 is sequentially set in the data storage area of the address of the file in FIG. 6 representing the molding cycle in which the product defect signal should be output. Further, if the value of the register k incremented during this time exceeds the maximum value N of the number of data storage in the file of FIG. 6, the correction work shown in step S14 will be performed as already described. , The registered value m set in the non-volatile memory 24
Since the value of N itself is set to a sufficiently large value as compared with the value of the registered value n, steps S12 to S16.
No matter how many times the loop process of step S1 is repeated, step S1
The process of 4 is executed at most once.

Then, the current value of the abnormal output start cycle storage register k exceeds the value of the abnormal output continuation limit storage register P, the determination result in step S12 becomes false, and the figure represents a molding cycle in which a product defect signal should be output. When it is confirmed that 1 is set in all the data storage areas of the addresses of the files of 6, the PMC CPU 18 completes the processing relating to the file setting operation, and the weighing abnormality is detected in the determination processing of steps S8 and S9. Similar to the case where it is not detected, the process proceeds to step S17.

Then, the PMC CPU 18 accesses the data storage area at the i-th address of the file in FIG. 6 based on the current value of the address search index i, and whether 1 is set in the storage area, that is, It is determined whether or not the product molded in the current molding cycle i is treated as a defective product due to a past measurement abnormality (step S1).
7). Then, if 1 is set in the data storage area of the i-th address of the file, the data in the data storage area is initialized to the numerical value 0 for handling non-defective products (step S18), and then molded in the molding cycle. A defective product signal is output to treat the defective product as a defective product (step S1).
9). As described above, the file of FIG. 6 is used cyclically because it is necessary to store a predetermined number of good / bad determination data in synchronization with the value of the address search index i, but a product failure signal is once output. Since the data storage area of the address corresponding to this is immediately initialized, the product defect signal will not be erroneously output when the same data storage area is detected again.

The product defect signal output in the process of step S18 is transferred to the CRT display circuit 26 for displaying an abnormal message on the display of the manual data input device 29, or at the product release timing. It is also transferred to the sorting device as a distribution preparation signal to drive the sorting device at the same time.

Further, when the determination result of step S17 is false, that is, when it is determined that the product molded in the current molding cycle does not need to be treated as a defective product due to the measurement abnormality, The PMC CPU 18 immediately confirms whether or not there is an abnormality in another monitoring item such as the maximum injection pressure or the injection speed that causes a problem in the molding of the product regardless of the measurement abnormality (step). S20). Then, if any abnormality is detected, a product defect signal is output to treat the product molded in the molding cycle as a defective product as described above (step S1).
9). If no abnormality is detected, a non-defective signal is output to treat the product molded in the molding cycle as non-defective (step S21).

Since the abnormality detection related to the maximum injection pressure, the injection speed, etc. in the injection pressure holding step is already known, it will not be described here.

P that outputs a non-defective signal or a defective product signal
Next, the MC CPU 18 increments the value of the address search index i representing the number of executions of the molding cycle (step S22), and the value of the index i exceeds the maximum value N of the data storage numbers in the file of FIG. It is determined whether or not (step S23), if the value of i does not exceed the value of N, the current value of the index i is held as it is, and if it exceeds, the value of the index i is initialized to 1. Yes (step S24).

That is, the address search index i is a value representing the number of executions of the injection operation by the remainder when the integrated value of the number of executions of the injection operation is divided by N. In addition, the above-mentioned file setting operation performed when a weighing abnormality is detected is
Since the current value of the address search index i is always read, the output of the product defect signal is always started at the time of execution of the molding cycle after the registered value m times, based on the molding cycle in which the measurement abnormality is detected. Further, the output of the product defect signal is stopped when the molding cycle of the registered value n times has elapsed.

The PMC CPU 18, which has completed the processing of step S23 or step S24, then starts the operation of the timer for measuring the required time (step S23).
25), the back pressure setting command and the screw rotation command are output to the CNC CPU 25 based on the data set as the measurement condition in the non-volatile memory 24, and the injection servo motor M1 and the screw rotation servo motor M2 are used as in the conventional case. The weighing operation of is started (steps S26 and S27). Then, the PMC CPU 18 sequentially reads the current position Sn of the screw 2 from the screw current position storage register of the RAM 19 (step S2
8), the current screw position Sn is the set measurement completion position SB
Until the screw 2 moves back to the set weighing completion position SB, the time measured by the timer is measured. The measurement required time Rt is stored in the register (step S30).

Hereinafter, the PMC CPU 18 is the CNC C
A mold opening start command is output to the PU 25 to cause the CNC CPU 25 to drive and control the mold clamping and ejector servomotors, and the mold opening and product release processing are performed in the same manner as in the past, and sequence control of one molding cycle is performed. Is completed (step S31), the process returns to the process of step S2 to enter the standby state, the mold opening completion signal from the CPU 25 for CNC is received, and the same sequence control as described above is repeatedly executed.

That is, if 1 is set in the i-th address of the file of FIG. 6 corresponding to the address search index i representing the number of executions of the molding cycle, the resin injected in the molding cycle is abnormal. As a product failure signal is output, and when a new weighing abnormality is detected, the file setting operation described above is performed again to newly or additionally set the data required for determining the quality of the product.
The quality of the product molded in each molding cycle is determined with reference to the file of FIG. 6 that is rewritten cyclically.

[0064]

According to the product quality determination method of the present invention, the quality of a product is determined based on whether or not an abnormality is detected when the resin injected at the present time is measured. If the measured resin is not immediately injected in the next injection process or if it is injected over multiple molding cycles, that is, there is a delay between the measurement and injection of the resin to be injected. Even in such cases,
The quality of the product can be accurately determined. Further, even when normal resin or abnormal resin remains only at the tip of the injection cylinder, the quality of the product can be accurately determined. As a result, it is possible to prevent the mixing of defective products and the handling of non-defective products, and it is possible to improve the yield of the resin as the molding material.

[Brief description of drawings]

FIG. 1 is a block diagram showing a main part of an injection molding machine of an embodiment to which a product quality determination method of the present invention is applied.

FIG. 2 is a flow chart showing an outline of sequence control by a control device of the injection molding machine of the embodiment and a main part of processing required for quality judgment.

FIG. 3 is a flowchart showing a main part of processing required for quality judgment.

FIG. 4 is a continuation of the flowchart showing the main part of the processing required for quality determination.

FIG. 5 is a continuation of the flowchart showing the main part of the processing required for quality determination.

FIG. 6 is a conceptual diagram exemplifying a file of an embodiment required for quality judgment.

FIG. 7 is an explanatory diagram illustrating the state of a measured resin.

FIG. 8 is an explanatory diagram illustrating a correspondence relationship between detection of measurement abnormality and occurrence of product defect.

[Explanation of symbols]

 1 Injection Cylinder 2 Screw 4 Pressure Detector 6 Hopper 10 Control Device 18 PMC CPU 20 Servo CPU 22 Bus 24 Non-volatile Memory 29 Manual Data Input Device with Display M1 Injection Servo Motor M2 Screw Rotation Servo Motor

Claims (3)

[Claims] 1. A product quality determination method for an injection molding machine, wherein a presence / absence of a measurement abnormality is detected by comparing a variable detected in a measurement process with a preset reference value. The number of injections until the measured resin is injected is determined and set in advance in the control device of the injection molding machine. When a measurement abnormality is detected, after the measurement abnormality is detected, the injection operation of the set number of injections is performed. A product quality determination method for an injection molding machine, which is characterized in that a product defect signal is output for a molding cycle in which 2. A product quality determination method for an injection molding machine, wherein the presence or absence of a measurement abnormality is detected by comparing a variable detected in a measurement process with a preset reference value, and a new injection cylinder The number of injections until the measured resin is completely discharged is set in advance in the controller of the injection molding machine, and if a measurement abnormality is detected, the number of injections will be changed after the measurement abnormality is detected. A product quality determination method for an injection molding machine, comprising outputting a product defect signal until the set number of injections is exceeded. 3. A product quality determination method for an injection molding machine, wherein the presence or absence of a measurement abnormality is detected by comparing a variable detected in a measurement process with a preset reference value. The first number of injections until the first metered resin is measured and the second number of injections until the resin is completely discharged by injection are obtained and set in advance in the controller of the injection molding machine. In addition, when a measurement abnormality is detected, a product defect signal is output after the measurement abnormality is detected and the number of injections is output from the first injection number to the second injection number. How to judge the quality of the molding machine product.