JP3581164B2 - Product quality judgment method and product quality judgment device for injection molding machine - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for determining the quality of a product of an injection molding machine.And product quality judgment deviceRegarding improvement.
[0002]
[Prior art]
Detects molding data that affects the product quality for each shot in the molding cycle, such as injection peak pressure, injection required time, injection holding pressure switching position, minimum cushion amount, and the like. Of an injection molding machine, which determines whether a product is good or not based on whether it is within a tolerance set for or whether or not values of several items are simultaneously included in each tolerance. A method for determining the quality of a product is already known.
[0003]
By the way, the plasticization state of the resin in the injection cylinder and the like vary to some extent due to a change in the temperature of the day and the state of the injection cylinder, but it fluctuates due to the passage of time and environmental changes like the plasticization state of the resin. Abnormal items can be dealt with to some extent by adaptive changes such as peak injection pressure, required injection time, injection holding pressure switching position, and minimum cushion amount. Therefore, the molding data such as the peak injection pressure, the required injection time, the injection holding pressure switching position, and the minimum cushion amount are slightly different from the molding data when the plasticization state of the resin is optimal. Unless it is significant, the product does not always have an abnormality.
[0004]
However, in the conventional method of determining the quality of a product, the optimum plasticization state of the resin is not required even for molding data that fluctuates in accordance with the passage of time and environmental changes such as the plasticization state of the resin. Since the quality of the product is determined by setting the allowable range based on the conditions, when the plasticization state of the resin changes, it is not possible to determine whether the product is actually molded. It was sometimes determined to be good.
[0005]
In order to solve such a problem, the present applicant plots the relationship between the detected values of the molding data of a plurality of items on a graph on a display screen of an injection molding machine, and displays a plurality of combinations by combining the values for each item. A non-defective product area is set arbitrarily, and if the combination of the detected values of the items detected in each molding cycle belongs to any of the above-mentioned areas, a product molded in the molding cycle is treated as a non-defective product. An information display device has already been proposed as Japanese Patent Application No. 4-335608. However, there is a certain inconvenience in that it is not possible to accurately judge the quality unless a plurality of non-defective areas are set, and the relationship between the detection values of molding data that fluctuates due to the passage of time and environmental changes is taken into consideration. In order to accurately determine the quality of the non-defective product, it is necessary to divide the non-defective product area finely and to set the non-defective product area, and the setting of the non-defective product area becomes extremely complicated.
[0006]
[Problems to be solved by the invention]
An object of the present invention is to eliminate the drawbacks of the prior art, and to accurately determine the quality of a product even when the plasticization state of the resin changes due to the passage of time or environmental changes. In addition, the method of determining the quality of a product of an injection molding machine can be easily realized by setting only one set of allowable range.And product quality judgment deviceIs to provide.
[0007]
[Means for Solving the Problems]
The invention according to claim 1 of the present application is a method for determining the quality of a product of an injection molding machine for automatically determining the quality of a product for each molding cycle,A plurality of function formulas configured with the value of the molding data as a variable are set, and molding data of items having different combinations are set in the variable,Each of the calculation results obtained from each of the functional expressions is displayed based on the value of the molding data corresponding to the variable obtained by executing a plurality of molding cycles, and the molding data items and the functional expressions used as the determination conditions Is selected in the subsequent molding cycle, and is determined to be non-defective only when the calculation result obtained from the selected determination condition is within the correspondingly set allowable range. Have
[0008]
The invention according to claim 2 of the present application is a product quality determination device for an injection molding machine that implements the product quality determination method according to the invention according to claim 1, wherein at least the quality of a product for each shot in a molding cycle is affected. Means for detecting values of the molding data of two or more items, means for setting a plurality of function formulas constituted by using the values of the molding data as variables, means for displaying respective calculation results obtained from the function formulas, There are means for selecting a combination of a molding data item and a function formula to be used as a determination condition, and means for setting an allowable range for determining the quality of a product with respect to a calculation result obtained from the selected determination condition. Then, the quality of the product is determined based on the calculation result obtained from the selected determination condition and the set allowable range.
[0010]
[Action]
Affects product quality for each shot in the molding cycleWith respect to the relational expression using the molding data of the item as a variable, various relational expressions in which the relational expression itself and the items constituting the variable of the relational expression are changed are obtained, and the calculation results are displayed. From the displayed calculation results, select and set molding data items and function expressions that are less affected by the passage of time, environmental changes, and the like, and set an allowable range for detecting the non-defective products with respect to the calculation results based on the relational expressions. . In the subsequent molding cycle, the quality of the product is determined based on whether or not the calculation result obtained by the function expression is within an allowable range. Selection of this molding data item and function formulaRegardless of the variation of each molding data, the calculation result when substituting the value of each molding data detected in the range where a good product is molded converges to a substantially constant value, and the molding detected at the time of molding a defective product It is desirable that the calculation result when the value of the data is substituted is considerably different from the substantially constant value. In a simple example, for example, the product of the molding data of each item always becomes a substantially constant value in the range in which a good product is molded, but the product of each item when molding a defective product is different from this. In the range where is molded, the value obtained by dividing the molding data of a certain item by the molding data of another item is a substantially constant value, but the value at the time of molding a defective product is different from this. The allowable range is a value range of a calculation result when a non-defective product is molded, and this value is set by a set of an upper limit and a lower limit.
[0014]
If the calculation result is within the allowable range, the product molded in the molding cycle is determined to be good, while if the calculation result is not within the allowable range, it is determined to be defective..
[0015]
【Example】
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a main part of an injection molding machine according to an embodiment to which a method of determining the quality of a product according to the present invention is applied. Reference numeral 1 denotes an injection cylinder of the injection molding machine, and reference numeral 2 denotes a screw. The screw 2 is driven in the injection axis direction by an injection servomotor M1 via a drive converter 5 for converting the shaft rotation of the drive source into a linear motion in the injection axis direction. The metering rotation is performed by the rotation servomotor M2. A pressure detector 4 is provided at the base of the screw 2, and detects the resin pressure acting in the axial direction of the screw 2, that is, the injection holding pressure in the injection holding pressure step and the screw back pressure in the measuring step. The injection servomotor M1 is provided with a pulse coder P1 for detecting the position and the movement 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. Has been deployed.
[0016]
The control device 10 also serving as a product quality judgment device of the injection molding machine includes a CNC CPU 25 which is a microprocessor for numerical control, a CPU 18 for a PMC which is a microprocessor for a programmable machine controller, and a servo CPU 20 which is a microprocessor for servo control. And a pressure monitor CPU 17 for performing sampling processing of the injection holding pressure and the screw back pressure, so that information can be transmitted between the microprocessors by selecting mutual input / output via the bus 22. Has become.
[0017]
A ROM 13 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, and a RAM 14 used for temporary storage of operation data are connected to the PMC CPU 18. Further, display data (see FIG. 10) and the like related to a setting screen required for performing a setting operation related to product quality determination are stored. The CNC CPU 25 is connected to a ROM 27 storing a program for controlling the entire injection molding machine and the like, and a RAM 28 used for temporarily storing calculation data.
[0018]
Each of the servo CPU 20 and the pressure monitoring CPU 17 includes a ROM 21 storing a control program dedicated to servo control, a RAM 19 used for temporary storage of data, a ROM 11 storing a control program related to molding data sampling processing, and the like. A RAM 12 used for temporary storage is connected. Further, the servo CPU 20 is connected to a servo amplifier 15 for driving servomotors of respective axes for mold clamping, ejector (not shown), injection, screw rotation, etc., based on commands from the CPU 20, Each of the outputs from the pulse coder P1 provided for the injection servomotor M1 and the pulse coder P2 provided for the screw rotation servomotor 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. 2 and the rotational speed of the screw 2 detected by the speed detector P2 are stored in a current position storage register and a current speed storage register of the RAM 19, respectively.
[0019]
The non-volatile memory 24 is a memory for storing molding data (injection holding pressure conditions, measurement conditions, etc.) and various set values, parameters, macro variables, etc., in the same manner as in the prior art. In this embodiment, a file for storing molding data used for determining the quality of a product, setting data for specifying a function formula, an allowable range for each function formula, and the like (see FIG. 9), A file (see FIG. 11) for storing the calculation result of each molding cycle by the formula is provided.
[0020]
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 transmitting various commands to peripheral devices of the injection molding machine.
[0021]
Then, the CNC CPU 25 distributes pulses to the servomotors of the respective axes based on the control program in the ROM 27, and the servo CPU 20 determines the movement commands and the pulse coder P1, the speed detector P2, etc. Based on the position feedback signal and the speed feedback signal detected by the detector, servo control such as position loop control, speed loop control, and current loop control is performed in the same manner as in the related art, and so-called digital servo processing is executed.
[0022]
The manual data input device with display 29 is connected to the bus 22 via the CRT display circuit 26, and displays various setting screens, data input operation, and the like, for example, a setting screen (see FIG. 8) related to product quality judgment. In the displayed state, the operation of selecting molding data items, the operation of specifying a function formula, and the operation of inputting upper and lower limits constituting an allowable range are performed by various function keys, numeric keys, cursor movement keys, and the like. ing.
[0023]
In this embodiment, as at least two or more items of molding data that affect the quality of the product, the measurement completion position, the injection peak pressure, the injection holding pressure switching position, the injection holding pressure switching pressure, the injection required time, the minimum cushion amount, Arbitrary two items are selected from the eight items of the cushion amount and the time required for weighing. Multiplication and division are used as the function expressions for determining the quality using the molding data of these two items as variables. Are stored in the ROM 13 in advance, and an arbitrary function formula can be selected from them. Therefore, the combination of molding data items used for pass / fail determination and the corresponding function formula used for pass / fail determination need to be selected from the eight items of molding data and a finite number of function formulas stored in the ROM 13. There is.
[0024]
Therefore, the operator conducts an experiment in advance, and the calculation result when substituting the value of each molding data detected in the range in which a non-defective product is molded becomes a substantially constant value irrespective of the fluctuation of the molding data. The combination of the two molding data items such that the calculation result when substituting the molding data value at the time of non-defective molding is substantially different from the substantially constant value, and the function formula applicable to this are described in the eight items. From the molding data and a finite number of function formulas, and the range of the operation result that can be regarded as a non-defective product, that is, the upper limit value and the lower limit value corresponding to the allowable range are obtained in advance for each product. deep.
[0025]
FIG. 12 shows the peak injection pressure (Kg / cm) for a certain product.²) And a minimum cushion amount (mm) are selected as a combination of two items of molding data that affect the quality, and a graph showing an experimental example when division is selected as a function formula for quality judgment, and is a continuous molding. It shows 400 shots after the start of the work. As can be seen from the relationship between the peak pressure of injection and the minimum cushion amount corresponding to the same shot shown in FIG. 12, the larger the peak pressure of injection, the larger the minimum cushion amount, and the smaller the peak pressure of injection, Since the minimum cushion amount is also smaller, it is clear that the injection peak pressure and the minimum cushion amount are interrelated and fluctuate. The injection peak pressure and the minimum cushion amount each have a variation for each shot, but as the molding operation is continued, the injection peak pressure gradually increases as a whole, and the minimum cushion amount also increases. It tends to increase.
[0026]
On the other hand, the calculation result obtained by dividing the injection peak pressure by the minimum cushion amount is substantially constant at 123 (anonymous number). FIG. 13 shows the results of measuring the product weight of each shot in order to determine the quality of the product for each shot formed in this experiment, together with a graph of the operation results enlarged vertically, and shows a short shot. The actual failures related to the lack of specific gravity, such as sink marks, sink marks, etc., are caused by the fact that the timing of P, Q, R, S in FIG. It also occurs when it becomes quite small. In this case, it is appropriate to set the lower limit of the allowable range to about 120 in view of the results in FIG. Further, in this experiment, since no problems such as mold release failure and generation of burrs due to overfilling have occurred at all, the upper limit value as an allowable range is, for example, more positive than the maximum value of the calculation result in FIG. Is set to about 125 by adding a certain clearance.
[0027]
Even if the injection peak pressure graph and the minimum cushion amount graph shown in FIG. 12 are individually observed, shots corresponding to the failure occurrence timings P, Q, R, and S in FIG. 13 cannot be found. The timing P, Q, R, and S of the occurrence of a defect can be easily known by looking at the fluctuation of the calculation result obtained by dividing the peak pressure of the above by the minimum cushion amount. Further, since the injection peak pressure and the minimum cushion amount in FIG. 12 gradually increase as a whole as the molding operation is continued, a good product is obtained for each of the injection peak pressure and the minimum cushion amount as in the related art. Is set individually, the peak pressure of injection and the minimum cushion amount corresponding to the failure timings P, Q, R, and S are all included in the allowable range. Even if the logical product of the pass / fail judgment of each item is obtained, the defective product generated in P, Q, R, and S cannot be determined as a defective product. This is because even if the peak pressure and the minimum cushion amount of the injection gradually increase as a whole and swell occurs in the entire data, a good product may be formed regardless of the swell, As a result, if the allowable range for determining a non-defective product as a non-defective product is individually set, the injection peak pressure and the minimum cushion amount corresponding to the failure occurrence timings P, Q, R, and S are all included in the allowable range. In addition, conversely, if an allowable range for determining a defective product as a defective product is individually set, a non-defective product may be determined as a defective product.
[0028]
However, as described above, if the determination is made based on the calculation result obtained by dividing the peak injection pressure by the minimum cushion amount, it is possible to use the logical product of the pass / fail determination based on the individual molding data such as the injection peak pressure and the minimum cushion amount. It is possible to perform an appropriate pass / fail determination without making an error such as a pass / fail determination without regard to the swell of the entire data such as a gradual increase or decrease in the injection peak pressure or the minimum cushion amount.
[0029]
FIG. 14 shows the peak injection pressure (Kg / cm).²) And the time required for weighing (sec.) Are selected as a combination of two items of molding data that affect the quality, and the result of the case where multiplication is selected as a function formula for quality judgment is summarized from the above-mentioned continuous molding operation. It is a thing. As can be seen from the relationship between the peak injection pressure and the required weighing time corresponding to the same shot shown in FIG. 14, the required weighing time is reduced if the peak injection pressure is high, while the weighing is reduced if the peak injection pressure is small. Obviously, because of the longer duration, the peak pressure of the injection and the duration of the metering are interrelated and fluctuate. The peak pressure of injection and the required time of weighing vary depending on each shot, but as the molding operation is continued, the peak pressure of the injection gradually increases as a whole, and the required time of weighing also increases. It tends to decrease. On the other hand, the calculation result obtained by multiplying the peak pressure of the injection by the time required for the measurement is substantially constant at 3250 (anonymous number). Therefore, the quality can be determined accurately regardless of the swell of the entire data, such as an increase in the peak pressure of the injection and a decrease in the time required for metering.
[0030]
The two examples relating to division and multiplication have been described above. However, if there are other function expressions that can accurately judge pass / fail regardless of the undulation of the entire data, those function expressions are represented by f3 and f4. ,... Are stored in the ROM 14 in advance.
[0031]
FIG. 2 shows an injection molding machine which selects a combination of molding data items used for pass / fail determination and a corresponding function formula used for pass / fail determination from the eight items of molding data and a function formula stored in the ROM 14 in advance. 3 to 7 are flowcharts showing an outline of a process for setting in the control device 10, and FIGS. 3 to 7 show an outline of a pass / fail determination process performed based on the selected molding data and the function formula.
[0032]
Therefore, the operator first operates the function keys of the manual data input device with display 29 to cause the PMC CPU 18 to start the processing of the setting mode related to the quality judgment of the product. Upon detecting the operation of the function key and starting the processing in the setting mode, the PMC CPU 18 first displays the setting dialogue screen S having a framework corresponding to the data storage file as shown in FIG. 29, and is selected with reference to a molding data item storage table as shown in FIG. 10A and a calculation method storage table as shown in FIG. 10B. A list of possible molding data item names and selectable function formula contents is displayed in the list display areas B and C of the manual data input device 29 with a display corresponding to the address values Xk and Yk of each table, respectively, and set. After displaying the cursor at the position of the one-column one-line spot in the framework of the dialogue screen S for use (step a1, see FIG. 8), the operator According numeric input operation enters a standby state to wait for the (step a2) or the cursor keys of the operation (step a3) or the end key operation (step a4).
[0033]
The setting dialogue screen S is used to select a combination of two molding data used as determination conditions for quality determination as first and second molding data items, or to select a combination of the first and second molding data items. The pass / fail judgment is made by selecting a function formula to be applied to the combination as an operation method, and further inputting an allowable range for the operation result of the function expression performed on these combinations as an upper limit value and a lower limit value. It is a screen used for setting conditions for the user.
[0034]
Therefore, the operator operates the cursor movement key to select a combination of two molding data items used as a determination condition for pass / fail and a function formula to be applied to the combination based on the result of a previously performed experiment. Then, the upper limit value and the lower limit value of the permissible range are input numerically, and a set of determination conditions for quality determination is set.
[0035]
The PMC CPU 18 that has detected the operation of the cursor movement key by the operator (step a3) performs a cursor operation in accordance with the type of the operated cursor movement key, for example, the type of the up movement key, the down movement key, the left movement key, or the right movement key. The values of the designated position storage registers x and y are updated, and a cursor is displayed at a spot on the x-column and y-row of the setting dialogue screen S corresponding to the current values of the registers x and y, and the data setting items are set. Is shown to the operator (step a5). For example, if the cursor right movement key is operated once, the value of the register x is incremented, and the cursor moves to the square next to the right on the setting dialogue screen S, and if the cursor left movement key is operated once, the register x is moved. The value of x is decremented, and the cursor moves to the square on the left of the setting interactive screen S. The possible value of the register x is an integer of 1 ≦ x ≦ 5. If the cursor down key is operated once, the value of the register y is incremented, the cursor is moved to the next lower square in the setting dialogue screen S, and the value of the determination condition setting number N is incremented. If the cursor up key is operated once, the value of the register y is decremented, and the cursor moves to the upper square on the setting dialogue screen S.
[0036]
Then, the operator moves the cursor to the position of one column and one line of the setting dialogue screen S, and the item corresponding to the first molding data item (indicated as item a in FIG. 8) serving as a determination condition for quality determination. When the number is entered with the numeric keypad with reference to the list display area B, the PMC CPU 18 detects this operation in the determination processing of step a2, and temporarily stores the value input with the numeric keypad in the register k (step a6). In this case, since the value of the cursor designated position storage register x is 1 (step a7 is true), the PMC CPU 18 stores the current value of the register k at the spot position of one column and one row in the data storage file of FIG. (Step a11) The display data corresponding to the molding data item k is read from the address Xk = k of the molding data item storage table, and displayed at the position of one column and one line of the setting dialogue screen S to notify the operator (Step a12). ). The example of FIG. 8 shows a case where the peak pressure of item number 2 in the list display area B is selected as the first determination condition, that is, the first molding data item in the determination condition 1.
[0037]
Further, the user moves the cursor to the position of the third column and the first row of the setting dialogue screen S, and changes the item number corresponding to the second molding data item (displayed as item b in FIG. 8) which is a determination condition for the quality determination. When the ten keys are input with reference to the list display area B, the PMC CPU 18 detects this operation in the determination process of step a2 in the same manner as described above, and updates and stores the value input by the ten keys in the register k (step a6). In this case, since the value of the cursor designated position storage register x is 3 (step a9 is true), the PMC CPU 18 stores the current value of the register k at the spot position of the third column and the first row of the data storage file of FIG. (Step a15) The display data corresponding to the molding data item k is read from the address Xk = k of the molding data item storage table, and displayed at the position of the third column and one row of the setting dialogue screen S to notify the operator (Step a16). ). The example of FIG. 8 shows a case where the required measuring time of the item number 8 in the list display area B is selected as the second molding data item in the determination condition 1.
[0038]
Then, the user moves the cursor to the position of the second column and the first row of the setting dialogue screen S, and sets the item number corresponding to the function formula to be applied to the combination of the first molding data item and the second molding data item. When input is made with the numeric keypad with reference to the list display area C, the PMC CPU 18 detects this operation in the determination process of step a2 in the same manner as described above, and temporarily stores the value input with the numeric keypad in the register k (step a6). . In this case, since the value of the cursor designation position storage register x is 2 (step a8 is true), the PMC CPU 18 stores the current value of the register k at the spot position of the second column and the first row of the data storage file of FIG. (Step a13) The display data corresponding to the calculation method k is read from the address Yk = k of the calculation method storage table, and displayed at the position of the second column and the first row of the setting dialogue screen S to notify the operator (Step a14). The example of FIG. 8 shows a case where the multiplication of the item number 1 in the list display area C is selected as the function expression in the determination condition 1.
[0039]
Further, when the cursor is moved to the position of 4 columns and 1 row of the setting dialogue screen S and the value of the upper limit value for the discrimination condition 1 is input by using the ten keys, the PMC CPU 18 performs the discrimination processing in step a2 in the same manner as described above. The operation is detected, and the value input from the numeric keypad is temporarily stored in the register k (step a6). In this case, since the value of the cursor designation position storage register x is 4 (step a10 is true), the PMC CPU 18 stores the current value of the register k at the spot position of 4 columns and 1 row in the data storage file of FIG. (Step a17) The value k of the upper limit value input through the numeric keypad is displayed at the position of four columns and one line on the setting dialogue screen S to notify the operator (Step a18). When the cursor is moved to the position of the fifth column and the first row of the setting dialogue screen S and the lower limit value is input by the ten keys, the PMC CPU 18 performs this operation in the determination processing of step a2 in the same manner as described above. The value input from the numeric keypad is detected and temporarily stored in the register k (step a6). In this case, the value of the cursor designated position storage register x is 5 (step a10 is false). The current value of the register k is stored at the spot position of the 5th column and 1st row of the data storage file (step a19), and the lower limit value k input by the ten keys is displayed at the position of the 5th column and the 1st row of the setting dialogue screen S. To inform the operator (step a20). FIG. 8 shows an example in which 3300 is input as the upper limit and 3000 is input as the lower limit.
[0040]
Then, the operator who has completed the first determination condition, that is, the operation of selecting the first and second molding data items and the function formula serving as the calculation method and the operation of setting and inputting the upper limit value and the lower limit value in the determination condition 1, are further performed. If necessary, the user moves the cursor down key to increase the value of the set number N of determination conditions, and performs the same setting operation as described above for the determination conditions 2, determination conditions 3,... If an operation related to selection of a molding data item or a function formula or an operation for inputting a numerical value is erroneous, the cursor is moved to a display position of an item to be corrected on the setting dialogue screen S, and the same setting operation as described above is repeated. To modify the contents of the data storage file.
[0041]
When all necessary setting actions have been completed, the operator operates the end key of the manual data input device with display 29 to end the setting mode processing by the PMC CPU 18.
[0042]
When the processing in the setting mode is completed, the PMC CPU 18 enters a standby state waiting for the input of a cycle start signal for starting the injection molding operation (step b1). The cycle start signal here is an operation signal from a semi-automatic operation switch of an operation panel provided on the injection molding machine main body in the case of semi-automatic operation, and a mold opening completion signal from the CNC CPU 25 during automatic operation. It is. In other words, when the semi-automatic operation switch is operated, the operation of the injection molding machine is stopped when the PMC CPU 18 executes the processing of step b1 to step b50 once and the mold opening operation is completed (semi-automatic operation). If the automatic operation switch of the operation panel is operated while the semi-automatic operation is being performed, the continuous operation is automatically started, and the mold opening completion signal from the CNC CPU 25 is sent to the PMC in the process of step b1. The processing of step b1 to step b50 is repeatedly executed by the detection by the CPU 18 (automatic operation).
[0043]
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 to start the semi-automatic operation, the screw rotation servomotor M2 must be manually operated. To the screw 2 to perform the metering rotation operation, thereby at least retracting the screw 2 backward from the metering completion position set as the molding condition to inject the resin required for the injection operation. The cylinder 1 must be filled.
[0044]
Hereinafter, a description will be given of the product quality determination processing in this embodiment assuming that the continuous operation of the injection molding machine has already been started.
[0045]
Upon detecting the input of the cycle start signal, the PMC CPU 18 first increments the value of the shot number counter n for integrating and storing the number of production shots (step b2), and outputs a mold closing command to the CNC CPU 25 (step b3). The CPU 25 and the servo CPU 20 control the driving of the mold clamping servomotor in the same manner as in the prior art, so that the mold clamping servomotor at the mold opening completion position performs the mold closing and mold clamping processes, The process enters a standby state waiting for the input of a mold completion signal from the CPU 25 (step b4). When the input of the mold closing completion signal is detected, the PMC CPU 18 reads the screw current position Sn from the screw current position storage register of the RAM 19 (step b5), and stores this value in the metering completion position storage register B (1). The value is stored as the weighing completion position, and 0 and Sn are initially set in the peak pressure storage register B (2) and the minimum cushion amount storage register B (6) (step b6). The measuring process of the screw rotation servomotor M2 required for the injection in this molding cycle has already been completed by the processes of Steps b43 to b45 in the immediately preceding molding cycle. Is stored in the required metering time storage register B (8) by the processing of Steps b42 and b46 in the immediately preceding molding cycle.
[0046]
Next, the PMC CPU 18 outputs an injection start command to the CNC CPU 25, and controls the drive of the injection servomotor M1 by the CPU 25 and the servo CPU 20 in the same manner as in the related art to start the injection operation of the screw 2 (step b7). ), The elapsed time measuring timer T is restarted to start measuring the injection required time (step b8). Next, the PMC CPU 18 reads the screw current position Sn from the screw current position storage register of the RAM 19 and also reads the injection pressure current value Pn from the RAM 12 via the pressure monitoring CPU 17 (step b9). Then, the PMC CPU 18 determines whether or not the screw current position Sn is smaller than the current value of the minimum cushion amount stored in the minimum cushion amount storage register B (6) (step b10). If the current screw position Sn is smaller than the current value, the screw current position Sn is updated and stored in the minimum cushion amount storage register B (6) (step b11), while if the current screw position Sn is larger, the process proceeds to step b11. The processing is not executed, and the value of the minimum cushion amount storage register B (6) is held as it is. Further, the PMC CPU 18 determines whether or not the present value Pn of the injection pressure is greater than the current value of the peak pressure stored in the peak pressure storage register B (2) (step b12). If the current value Pn of the injection pressure is larger than the current value, the current value Pn of the injection pressure is updated and stored in the peak pressure storage register B (2) (step b13), while the current value Pn of the injection pressure is smaller. For example, the process of step b13 is not executed, and the value of the peak pressure storage register B (2) is held as it is.
[0047]
Next, the PMC CPU 18 determines whether the transition condition from the injection process to the pressure holding process is set by the screw position or the injection pressure (step b14). Until the value of the screw current position Sn reaches the injection holding pressure switching position VPss stored in the nonvolatile memory 24 as the molding condition (step b15), and if the injection pressure is set, the injection pressure Until the current value Pn reaches the injection holding pressure switching pressure VPps stored in the non-volatile memory 24 as the molding condition (step b17), the same processing as described above is repeatedly executed, and the minimum cushion amount in the injection process is performed. And the peak pressure to the minimum cushion amount storage register B (6) and the peak pressure storage register B (2). The new store.
[0048]
When the end of the injection process is confirmed in the determination process of step b15 or step b17, the PMC CPU 18 determines that the transition condition from the injection process to the pressure holding process is set by the screw position. Then, the value of the present value Pn of the injection pressure when the injection is completed after the value of the screw current position Sn reaches the injection holding pressure switching position VPss is stored in the injection holding pressure switching pressure storage register B (4) (step b16). If the transition condition from the injection step to the pressure-holding step is set by the injection pressure, the current injection pressure value Pn reaches the injection-hold pressure switching pressure VPps, and the injection ends. The value of the current screw position Sn at this time is stored in the injection holding pressure switching position storage register B (3) (step b18).
[0049]
Next, the PMC CPU 18 reads the current value of the elapsed time measurement timer T, stores it in the required injection time storage register B (5) as the required injection time, and restarts the elapsed time measurement timer T again to maintain the pressure. Time measurement is started (step b19), a pressure-holding start command is output to the CNC CPU 25, and the drive of the injection servomotor M1 is controlled by the CPU 25 and the servo CPU 20 in the same manner as in the prior art, thereby forming a nonvolatile memory as a molding condition. The holding pressure operation of the screw 2 is started with the holding pressure set to 24 (step b20). Thereafter, the PMC CPU 18 operates in the same manner as the above-described steps b9 to b11 until the current value of the elapsed time measurement timer T reaches the pressure holding time set in the nonvolatile memory 24 as the molding condition (step b24). The process is repeatedly executed, and if a screw current position Sn smaller than the current value of the minimum cushion amount stored in the minimum cushion amount storage register B (6) is detected, the value Sn is stored in the minimum cushion amount storage register B (6). ) (Step b21 to step b23).
[0050]
Then, when it is confirmed in the determination processing in step b24 that the current value of the elapsed time measurement timer T has reached the pressure holding time set in the nonvolatile memory 24 as the molding condition, the PMC CPU 18 determines the current screw position Sn. After the cushion amount is stored in the cushion amount storage register B (7) (step b25), a value 0 for storing the molding of a non-defective product is initially set in the defect determination flag b (step b26), and 1 is initialized in the address search index j. After setting (step b27), a process for determining the quality of the product molded in the current molding cycle is started.
[0051]
The PMC CPU 18 that has started the process for quality determination reads the item number of the function formula stored in the spot on the 2nd row and jth row of the data file in FIG. 9 and determines the value (step b28 to step b30). Then, if the value of the item number is the value 1 indicating the function expression of the multiplication, the PMC CPU 18 determines that the first molding data item corresponding to the item number stored in the spot in column 1 and row j of the data file in FIG. And the register B (A (A (1, j)) storing the current value of the second molding data item corresponding to the value of the register B (A (1, j)) storing the current value of 3, j)) are detected, the function expression is executed by multiplying these values, and the operation result is stored in the operation result storage register C (step b31). For example, if the value of the 2nd column and jth row in the data file of FIG. 9 is 1, the value of the 1st and jth row is 2 and the value of the 3rd and jth row is 8, the value of the peak pressure storage register B (2) And the value of the weighing required time storage register B (8). If the value of the item number stored in the spot on the second row and the j-th row is the value 2 indicating the function of division, the PMC CPU 18 stores the value of the register B (A (1, j)) in the register B (A The function expression is executed by dividing by the value of (3, j)), and the operation result is stored in the operation result storage register C (step b32). For example, if the value of the 2nd column and jth row in the data file of FIG. 9 is 2, the value of the 1st and jth row is 2 and the value of the 3rd and jth row is 6, the minimum cushion amount storage register B (6) The value of the peak pressure storage register B (2) is divided by the value.
[0052]
When the value of the item number stored in the spot on the second row and the j-th row is the value 3 or 4 indicating another function formula, the PMC CPU 18 stores the current value of the first molding data item. The function formula of f3 or f4 is executed based on the value of the register B (A (1, j)) and the value of the register B (A (3, j) storing the current value of the second molding data item, and the operation result Is stored in the operation result storage register C (step b33, step b34).
[0053]
Then, the PMC CPU 18 accesses the spot in the n-th column and the j-th row of the calculation result storage file in FIG. 11 in accordance with the address search index j and the current value of the shot number counter n, and performs any one of the processes in steps b31 to b34. Is written (step b35), and the value C of the calculation result is stored in the 4th row, jth row spot of the data file in FIG. ) And the lower limit A (5, j) are determined (step b36).
[0054]
When the value of the calculation result is between the upper limit value and the lower limit value, that is, the data detected in the current molding cycle (however, the weighing time B (8) is the value detected in the previous molding cycle. If the result of the calculation for the determination condition j performed based on the given condition) is determined as a non-defective product (step b36), until the current value of the address search index j exceeds the set number N of the determination conditions (step b39). The value of the address search index j is sequentially incremented (step b38), and the same processing as described above is repeatedly executed based on the current value of the index j, and the calculation result for the determination condition j is set for the determination condition j. It is determined whether or not the calculated value is between the upper limit value and the lower limit value, and the value of the calculation result is stored in the C column j row spot of the calculation result storage file in FIG. 11 according to the current value of the address search index j. Yuku crowded come. If the result of the determination in step b36 is false during this time, the PMC CPU 18 sets 1 to the failure determination flag b (step b37), and repeatedly executes the same processing as described above.
[0055]
Until the current value of the address search index j in step b39 exceeds the set number N of determination conditions, if all the calculation results for the determination condition j are determined to be non-defective, they are initialized to 0 in the processing of step b26. The defective discrimination flag b retains 0 as it is, and the product molded in this molding cycle is recognized as a non-defective product. Further, if the determination result of step b36 is false even once, it means that at least one of the determination conditions from 1 to N is not satisfied, and 1 is set in the failure determination flag b. When set, a product molded in this molding cycle is recognized as a defective product.
[0056]
When the result of the determination at step b39 is false and it is confirmed that the above-described processing has been completed for each of the set N determination conditions, the PMC CPU 18 sets the failure determination flag b to 1 Is determined (step b40), and only when the failure determination flag b is set to 1, a product failure signal indicating the occurrence of defective molding is output (step b41). This product failure signal is transferred to the CRT display circuit 26 to display an error message on the display of the manual data input device 29 with a display, or to drive the product selection device in synchronization with the product release timing. Or transmitted to a product sorting device as a sorting preparation signal.
[0057]
In this way, the PMC CPU 18 that has completed the process for determining the quality of the product restarts the elapsed time measurement timer T to start measuring the weighing time (step b42). A back pressure setting command and a screw rotation command are output to the CNC CPU 25 based on the data set as the weighing conditions, and the weighing operation similar to the conventional one is started by the injection servomotor M1 and the screw rotation servomotor M2 (step b43). 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 b44), and until the screw current position Sn retreats to the set weighing completion position Sb (step b45). The weighing operation similar to the conventional one is continuously performed. Then, when it is confirmed in the determination processing of step b45 that the screw 2 has retreated to the set weighing completion position Sb, the PMC CPU 18 stores the time measured by the elapsed time measurement timer T in the required weighing time storage register B (8). Is stored as the required measuring time (step b46).
[0058]
Next, the PMC CPU 18 outputs a mold opening start command to the CNC CPU 25 to start the mold opening operation by the mold clamping servomotor (step b47), and the movable platen of the injection molding machine reaches the set mold opening completion position. Until the movable platen reaches the set eject start position (step b49), an eject start command is output to the CNC CPU 25 so that the ejector rod protrudes and retracts by the ejector servo motor. The product is controlled (step b50), and the product is released from the mold.
[0059]
When the series of product ejection and mold opening operations is completed, the PMC CPU 18 returns to the process of step b2, enters a standby state, receives a mold opening completion signal from the CNC CPU 25, and performs the same sequence control as described above. Is repeatedly executed.
[0060]
As described above, as an embodiment, one for each row of the data storage file in FIG. 9 is provided by a combination of two molding data items, a function formula applied thereto, and an upper limit value and a lower limit value permitting the operation result of the function formula. The case where the determination conditions are set has been described. However, when the value of the molding data detected in the range where the non-defective product is molded is substituted, the calculation result becomes a substantially constant value, and furthermore, the value of the molding data at the time of defective product molding. If the result of the calculation is a combination of molding data items that is considerably different from the above-mentioned substantially constant value, the number of combinations of molding data items and the contents of the function formula for quality judgment are not limited. Absent.
[0061]
Further, as for the function formulas used for pass / fail determination, those created by the user can be freely registered in the non-volatile memory 24 corresponding to the item numbers, and the non-volatile functions corresponding to the item numbers are determined in steps b31 to b34. Alternatively, a function formula may be read from the sex memory 24 to perform the arithmetic processing. In this case, a calculation method storage table as shown in FIG. 10B is provided in the nonvolatile memory 24 so as to be rewritable, or the contents of the calculation method itself are stored as display data in a table provided in the ROM 13. Instead, an abstract heading such as calculation method A, calculation method B,...
[0062]
In an experiment for determining the upper limit value and the lower limit value of a range in which a non-defective product can be considered to be molded, a first molding data item, a second molding data item, and a functional expression are determined and a set of determination conditions is set. Only, and the continuous molding operation is performed by the processing of the above-mentioned steps b1 to b50, and the relationship between the number of shots and the calculation result is recorded in a data file as shown in FIG. If the results are displayed as a graph on the screen and the quality of the product formed in each shot is visually determined, the data detection operation for setting the upper limit and the lower limit can be performed more easily. Further, when it is desired to newly obtain an appropriate combination of the first molding data item, the second molding data item, and a function expression (which may be created by a user) to be used as the determination condition, A plurality of appropriate combinations of the first molding data item, the second molding data item, and the function formula are set in advance in a data file as shown in FIG. In step b1 to step b50, the continuous molding operation is performed, the relationship between the number of shots and the calculation result is recorded in a data file as shown in FIG. 9, the result is displayed in a graph, and the calculation result for each determination condition is displayed. By observing the variation, it is also possible to obtain a combination of the first molding data item, the second molding data item, and the function expression that is appropriate as a determination condition. Naturally, in these cases, the product failure signal output from the PMC CPU 18 is ignored, and the quality of the product is determined by visual confirmation and weight measurement.
[0063]
【The invention's effect】
Product quality judgment method of the present inventionIs the timeWhether the values of a single molding data item or several molding data items fall within the permissible range for each item, even if the molding data values fluctuate due to changes over time or environmental changes. Thus, the quality of the product can be determined more reliably than the conventional quality determination method of determining the quality of the product.In addition, since the calculation result can be selected from a large number of combinations of the molding data items and the function formulas and whose calculation result is less affected by the passage of time and environmental changes, the quality can be determined more accurately. be able to.Also, only one set of allowable range may be set for the combination of molding data used for the calculation and the discriminant condition constituted by the function formula applied to the combination regardless of the number of molding data items used. Since there is no need to individually set an acceptable value for pass / fail determination for such molding data items, the input operation of setting data becomes easy.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a main part of an injection molding machine according to one embodiment to which the present invention is applied.
FIG. 2 is a flowchart illustrating an outline of a data setting process performed by a control device provided in the injection molding machine of the present embodiment.
FIG. 3 is a flowchart illustrating an outline of a pass / fail determination process performed by a control device provided in the injection molding machine of the present embodiment.
FIG. 4 is a continuation of the flowchart showing the outline of the pass / fail determination processing.
FIG. 5 is a continuation of the flowchart showing the outline of the pass / fail determination processing;
FIG. 6 is a continuation of the flowchart showing the outline of the pass / fail determination processing;
FIG. 7 is a continuation of the flowchart showing the outline of the pass / fail determination processing;
FIG. 8 is a diagram illustrating an example of an interactive screen used for data setting processing.
FIG. 9 is a conceptual diagram showing a data storage file adopted in the embodiment.
FIG. 10 is a conceptual diagram showing a display data storage table adopted in the embodiment.
FIG. 11 is a conceptual diagram showing a calculation result storage file adopted in the embodiment.
FIG. 12 is a graph of one experimental result showing a correlation between a peak pressure and a minimum cushion amount.
FIG. 13 is a graph showing an enlarged part of the diagram of FIG. 12 together with the measurement result of the product weight.
FIG. 14 is a graph of one experimental result showing a correlation between a peak pressure and a weighing time.
[Explanation of symbols]
1 Injection cylinder
2 Screw
4 Pressure detector
10 Control device
18 CPU for PMC
20 Servo CPU
22 bus
24 Non-volatile memory
29 Manual data input device with display
M1 Injection servo motor
Servo motor for M2 screw rotation

Claims (2)

In a method of automatically determining the quality of a product for each molding cycle, in a method of determining the quality of a product of an injection molding machine, a plurality of function formulas each including a variable of molding data as a variable are set. The molding data is set, and the results of the calculations obtained from the respective function formulas are displayed based on the molding data values corresponding to the variables obtained by executing a plurality of molding cycles, and are used as discrimination conditions. The combination of the molding data item and the function formula to be performed is selected, and in the subsequent molding cycle, it is determined as a non-defective product only when the calculation result obtained from the selected determination condition is within the correspondingly set allowable range. A method for determining the quality of a product of an injection molding machine. Means for detecting at least two or more items of molding data values that affect the quality of a product for each shot in a molding cycle , means for setting a plurality of function formulas using the molding data values as variables, Means for displaying each of the calculation results obtained from the function formula, means for selecting a combination of the molding data item and the function formula to be used as the discrimination condition, and a product for the calculation result obtained from the selected discrimination condition. Means for setting a permissible range for determining whether or not the product is good or not, and determining whether the product is good or bad based on the calculation result obtained from the selected determination condition and the set permissible range. Product quality judgment device for injection molding machines.

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