JPH02106315A - Automatic setting method for quality judgment reference value of molding - Google Patents

Abstract

PURPOSE:To set a reference value accurately and simply, and simplify the trouble by constituting such that the maximum value and the minimum value of variable data detected at each molding cycle is set automatically as the reference value of a variation at a reference value setting mode. CONSTITUTION:The maximum value, minimum value, and the average value of each variable date up to the present of the reference value setting mode are memorized in a register at each time of completion of molding cycle. The molding cycle is carried out in appropriate times at a reference value setting mode, and when it is returned to an ordinary molding mode, the value of the variable data detected at each time of completion of respective molding cycles is judged whether or not being in the range denoted by the register memorizing the maximum value and the minimum value of variable data within a common RAM 14. Should it be within the range, the next variable data is judged whether being in the maximum value and the minimum value, and if any one of the detected variable data may not be in the maximum value and the minimum value, the display of effects is performed on the CRT screen of CRT/MDI 17.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for automatically setting determination reference values for determining the quality of molded products molded by an injection molding machine.

Conventional technology As a method of determining the quality of molded products molded in each molding cycle of an injection molding machine, the amount of cushioning, that is, the screw position at the end of holding pressure, is within a set standard value that allows the molded product to be judged as a good product. There are known methods for determining whether or not the injection time and metering time are within set reference values. Furthermore, a method of determining the quality of a molded product based on peak injection pressure is also known.

Furthermore, a method has been proposed in which a molded product is determined to be of good quality based on whether or not the screw position after a predetermined period of time has elapsed from the start of injection (Japanese Patent Application No. 63
-153599).

Problems to be Solved by the Invention However, in all conventional methods, reference values for determining the quality of a molded product are set by manual input by an operator. In other words, from the variable data for determining the quality of the molded product obtained at that time and the molded product in the molding cycle after manufacturing a molded product several times, the upper and lower limits of the reference value of the variable data for obtaining a non-defective product are determined. The values were determined, and based on these values, the settings were manually set in the injection molding machine based on the operator's experience. For example, if the variable data for determining the quality of a molded product is cushion suspension, the upper and lower limits of the cushion that can yield a good product are determined by performing molding several times.
Based on the lower limit value, a reference value is set for determining the quality of molded products. However, this method has the disadvantage that the reference values vary due to individual differences among operators, and that it takes time and effort to determine the optimal reference value.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method in which the injection molding machine itself automatically determines and sets the reference value for determining the quality of the molded product.

Means for Solving the Problems In order to solve the above problems, the present invention provides an injection molding machine with the following features:
A reference value setting mode is provided, and the injection molding machine is operated in the reference value setting mode to perform molding several times. Then, the maximum and minimum values of the variable data (for example, cushion suspension, etc.) for determining the quality of the molded product detected in each molding cycle in the standard i setting mode are automatically set as the reference values for determining the quality of the molded product. .

Further, the average and standard deviation of the variable data detected in each molding cycle in the reference value setting mode are determined, and from the average and standard deviation, the maximum value as one value of the variable data for determining the quality of the molded product is determined.

Set the minimum value automatically.

The maximum and minimum values of the above variable data in each molding cycle obtained in the operation reference value setting mode are determined, and these maximum and minimum values are automatically set as the maximum and minimum values of the reference value. Therefore, it is possible to easily set the optimum reference value without having to perform troublesome operations such as variations in setting values due to individual differences among operators, judgments for setting the reference value, and setting procedures.

Embodiment FIG. 3 is a block diagram of main parts of an NC device as a control device in an injection molding machine according to an embodiment of the present invention.
has a microprocessor (hereinafter referred to as CPLI) 2 for NC and a CPU 3 for programmable machine controller (hereinafter referred to as PMC), and the PMC CPU 3 includes a ROM 5 that stores sequence programs for the injection molding machine. , and a RAM 6 used for data storage calculations etc. are connected, and the NC CPU 2 is connected to a ROM 7. which stores a control program for controlling the injection molding machine as a whole.
For injection, clamping,
Servo circuits 10 to 13 that drive and control the servo motors of each axis for screw rotation and ejector are connected, and the servo circuits 10 to 13 have a detection circuit that detects the servo motor of each axis and the rotational position of each servo motor. The servo motor is connected to the servo motor and receives the torque limiter value output from the output circuit 16 (the connection relationship is omitted in FIG. 3), thereby controlling the position, speed, and torque of the servo motor. Also, 14 is a commercial
A nonvolatile shared RAM composed of an OS memory and a bubble memory, which stores NC programs that control each operation of the injection molding machine, various settings lia, etc. 1
7 is CR7 manual data input device with display device (hereinafter referred to as CR
T/MDI), the CRT/MD I 17 is
It is connected to the bus arbiter controller (hereinafter referred to as 8AC) 4 via the interface 18, and the 8A C4 NihaNG CPU 2 and PMC CPU 3 share RAM.
14. Input circuit 15. Each bus of the output circuit 16 is connected, and the bus to be used is controlled by the BAC 4. Various sensors attached to the injection molding machine are connected to the input circuit 15, and various actuators are connected to the output circuit 16. The above configuration is the same as the configuration of the NC device of an injection molding machine controlled by a conventional NC device.

Next, the reference value setting process for determining the quality of the molded product will be described below.

After adjusting various molding conditions and achieving a stable state in which a good molded product can be obtained, operate the CRT/MD I 17,
Operate the injection molding machine in reference value setting mode. Injection molding machines close the mold, clamp the mold, and inject.

A molded product is formed by repeating a molding cycle consisting of the steps of holding pressure, measuring, cooling, and opening the mold. Then, as in the past, during this molding cycle, variable data for determining the quality of the molded product, such as the cushion amount! 8. Detects exit time, metering time, peak injection pressure, metering completion position, etc.
It is stored in the shared RAM 14. Meanwhile, the mold opening is completed,
- When the molding cycle ends, the PMC CPU 3
The process of setting the reference value or determining the quality of the molded product shown in the figure is started.

When the mold opening completion signal is issued and the molding cycle ends, the PMC CPU 3 first determines whether or not it is in the reference value setting mode (step S1), and if it is set in the reference value setting mode, it changes to the reference f1 setting mode. The index j that counts the molding cycles in is incremented by "1". This index j is initially set at the start of operation of the injection molding machine, and
” is set), an index 11 for setting variables for determining the quality of the molded product, and each variable data 1(x) (i=o to (n-1)) provided in the shared RAM 14. Register RO(n+ax) to store the maximum and minimum values of
R(n-1) (wax), RO(sin)
~R(n-1) (win) and an addition register RO(su
m) ~R(n-1) (sum) is set to "0" (step 82). Next, data 1(x) of the variable specified by the index i (-0) of the molding cycle detected during the molding cycle and stored in the shared RAM 14
(for example, the amount of cushion), and read out the variable data i(x
), if the detected variable data 1(x) is larger than the register Ri (Ilax) that stores the maximum value of is large), this variable data i(X) is stored in the register Ri (a+ax) that stores the maximum value (step 84).

Note that the variable data 1 (×) is the register Ri (wax)
If the value is less than or equal to the value of , the process of step S4 is not performed.

Next, it is determined whether the index j for counting molding cycles in the reference value mode is "1" (step 85), and if it is "1", the detected variable data i(X) is stored in a register that stores the minimum value of the variable data. The data is stored in Ri (akin) (step 87). Furthermore, if the index j is not [1-1, the minimum value before the molding cycle is already stored in the register Ri (Win), so the detected variable data i(x) of the molding cycle and the register Rr (mtn) is compared (step S6), and only when the detected variable data i(x) is small, the value of the register Ri (sin) is rewritten to the detected variable data i(x) (step 87).

Next, the variable data i(x) is added to the addition register Ri (Suit) that stores the sum of the variable data i(x) of each molding cycle (Step S8), and the variable data is added to the index j1, that is, the addition register Ri (Sum). Data 1 (×)
(the number of molding cycles) is added to the addition register Ri.
(Sulm) and writes the average value of the variable data i(x) to the register R1 that stores it (step 89).
. Then, the index i is incremented by "1" (step 510), and it is determined whether the index i is greater than or equal to the number n of variables used for quality determination (step 511), and if it is smaller, the processes from step 83 onwards are performed again.

That is, if quality determination is performed using one variable data, for example, the amount of cushioning, n=1, and in step 311, i
=n=1, and this process ends. the result,
Maximum and minimum values of cushion amount.

The average value is the register RO(wax), RO(sin)
, 'F(0). Also, variables for determining quality are, for example, cushion M and injection time.

If there are three measurement times, n=3 and the maximum value, minimum value, and average value of each variable are in registers RO(n+ax) to R2(-a
x), RO(1n) ~R2(akin)
, RO to R2.

Thereafter, each time the molding cycle ends, steps 81 to S11
Repeat the process to obtain the maximum and minimum values of each variable data up to now in the reference value setting mode.

The average value is the register Ri (n+ax), Ri (w
in), r'(.

The molding cycle is performed an appropriate number of times in the reference value setting mode, and when the operator turns off the reference gri setting mode and enters the normal molding mode, the process moves from step S1 to step S12 after each molding cycle is completed. , the variable data index 1 is set to "0", and the value of the variable data i(x) indicated by the index i detected in the relevant molding cycle is the maximum value and minimum value of the relevant direction change data in the shared RAM 14. A register Ri (n+in) that stores Ri
(max), that is, Ri
It is determined whether (1n)≦i(x)≦Ri (max) (step 513), and if it is within the range, the index 1
is incremented by "1", and the next change data is also the maximum value Ri (wax) and the R minimum value Ri of the change data.
(sin), and until the index i reaches the number n of variables (step 515), steps 813 to 3
15 processes are performed, during which at least one detected variable data i
When (x) is not within the maximum and minimum values (Ri (1n
)≦i(x)≦Rt (+max)), C
A message indicating that the product is defective is displayed on the CRT screen of the RT/MD 117 (step 816).

Thereafter, each time the molding cycle ends, step S1.8
Processes 12 to 816 are performed to determine whether the molded product is good or bad.

In addition, in step S9, the average value R1 of the variable data 1 (X)
was calculated, but this is to be displayed as the average value of the variable data i(x), and is not used to determine the quality of the molded product. Therefore, the processes of steps S8 and S9 are not directly required in the present invention.

In the above example, the maximum and minimum values of the variable data within all molding cycles in the reference value setting mode were determined and used as the reference value for the variable data. However, considering that the variable data is normally distributed, each variable The average value and standard deviation may be determined for each data item, and thereby the maximum value and minimum value of the reference value of each variable data may be determined. That is, one type of variable data x 1 For example, if three pieces of data are obtained for the amount of cushioning, the average or -x/j is obtained, and the standard deviation σ is obtained using the following equation.

Then, Equation (4) is as follows: If the data X detected in each molding cycle is sequentially added to register R1, and the square of the data x 2 is added to register R2, then, Therefore, in the normal distribution, 99.7% of the data is included between (also -3σ) and Kumata +3σ), so let this (also -3σ) and (also +3σ) be the minimum value of the relevant variable data, It may be set to the maximum value.

In contrast to the above first embodiment, in which the molding conditions are set and stable molding is obtained, the maximum value and minimum value are determined by setting the standard value setting mode. A method for setting a value as a reference value is to immediately enter the reference value setting mode after setting the molding conditions, and to increase the number of molding cycles in the reference value setting mode than in the first embodiment.

The second standard 1itI setting method using this average and standard deviation
An example of this is shown in FIG.

First, as in the first embodiment, the process shown in FIG. 2 is performed every time a molding cycle ends, and if it is in the reference value setting mode (step 521), the number of molding cycles in the reference If1 setting mode is counted. Increment the index j by "1", the initial value is "0" as in the first embodiment), the index i indicating the variable, and the variable m data i (x
) and the square of the variable data i(x) 2 addition n
A register Ri1. that stores a value. Ri2 (i=1~(n
-1)) is set to rOJ (step 522). Then, the variable data i(x
) and its square i(x) 2 are respectively stored in registers Rt1.
Steps 323 and 824) to add it to Rt2, step 525 to judge whether index j is "1" or not, and step 525) to determine whether the index j is "1".
30, if it is not "1", perform the calculation shown in equation (4) on the variable 11i, and calculate the standard deviation σ of the variable li.
Find i (step 826). Next, the average Ril/j=f7i of the variable i is calculated, and the value obtained by adding three times the standard deviation σi to the calculated average Ri is written in the register Ri (wax) as the maximum value of the variable li (step 828 )
, and writes the value obtained by subtracting three times the standard deviation σi from the average Rj into the register Ri (lain) as the minimum value (step 529). Then, the index i is incremented by 1°1'' (step 530), and if the index i does not reach the number n of variables (step 531), step 8 until the index i reaches the number n of variables.
The processes from 23 to 831 are repeated, and the process ends when i=n. Thereafter, steps 821 to 831 are performed every time each molding cycle ends, and the maximum and minimum values of each variable i are stored in registers Ri (saX) and Ri (sin
).

Then, when the molding cycle is performed an appropriate number of times in the reference value setting mode and switched to the normal molding mode, the PMC C;
Step 3 moves from step 821 to step S32, where it is determined whether the molded product is good or bad. This acceptability judgment process (step 532) is the same as in the first embodiment, and is the process of steps 812 to 816 in FIG. 1, so the explanation will be omitted.

In addition, in the above-mentioned second example, the maximum value and the minimum value were determined by adding or subtracting three times the standard deviation σ to the average R.
Considering the stability of the molding state, etc., the average R is set to 2 standard deviations σ.
It may also be obtained by adding or subtracting the times (Ri (n+ax
) =Fr i + 20. Ri (+++in=minus 1-2σ).

In addition, in this case, assuming that the data is normally distributed,
95% of the data will be included between this maximum value and the R minimum value.

Effects of the Invention In the present invention, the injection molding machine itself automatically determines and sets the reference values for determining the quality of the molded product, which is more accurate and effective than the conventional method of setting by humans. Easy to set up.

In addition, since the injection molding machine judges only molded products molded under approximately the same conditions as the molded product obtained in the reference value setting mode to be good products, and other products are judged to be defective, All you need to do is inspect the product. Therefore, when humans set standard values as in the past, even if you set - degrees,
It is necessary to consider again whether it is optimal or not, but in the present invention, there is no need to consider it again, and the effort of setting the reference value becomes extremely simple.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is an operation processing flowchart of the first embodiment of the present invention, FIG. 2 is an operation processing flowchart of the second embodiment, and FIG. 3 is a flowchart of the operation processing of the second embodiment. FIG. 2 is a block diagram of the main parts of the control section of the injection molding machine that implements the process. 1... Injection molding machine. Diagram

Claims (2)

[Claims] (1) During each molding cycle, variable data for determining the quality of the molded product is detected, and the detected variable data and the reference value for the variable are compared to determine the quality of the molded product. In the setting method, the maximum and minimum values of the variable data detected in each molding cycle of the injection molding machine operated in the reference value setting mode are automatically set as the reference value of the variable. How to automatically set pass/fail judgment standard values. (2) The above reference values in an injection molding machine that detects variable data for determining the quality of a molded product during each molding cycle, and compares the detected variable data with a reference value for the variable to determine the quality of the molded product. In the setting method, the average value and standard deviation of the above variable data detected in each molding cycle of the injection molding machine operated in the reference value setting mode are determined, and the maximum value as the reference value of the variable is determined from the average value and standard deviation. A method for automatically setting standard values for determining the quality of molded products by automatically setting values and minimum values.