JPH01141714A - Method and apparatus for monitoring dwell process of injection molder - Google Patents

Abstract

PURPOSE:To remarkably improve the detecting efficiency of molding abnormality by a method wherein deviations between integral values from the start to the finish of dwelling of the detected oil pressure, resin pressure and the like of an injection molder and predetermined values, which are set in advance, are compared with each other. CONSTITUTION:Final integral values from the start to the finish of dwelling of the oil pressure and resin pressure of an injection molder 10 are obtained by being calculated with an integrator 14. On the other hand, predetermined values are inputted in a setter 15 in advance. Next, the final integral values, which are obtained with the integrator 14, and the predetermined values, which are inputted in the setter 15, are compared with each other in a comparator 16. If the final integral value deviates from the predetermined value, an abnormality signal is issued to a control device 17.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is an injection molding machine that maintains pressure after filling a mold with molten resin to compensate for shrinkage caused by cooling and solidifying the molten resin. The present invention relates to a method and device for monitoring abnormalities in a pressure holding process.

(Prior Art) Conventionally, the pressure holding process has been monitored using information values obtained by detecting the state at one point in the pressure holding process, such as the most advanced position of the screw, the position of the screw at the completion of the pressure holding process, Alternatively, the maximum hydraulic pressure in the injection hydraulic cylinder, the maximum resin pressure in the mold cavity, etc. can be detected, and this detected value is compared with a predetermined value set in advance to determine whether the detected value is a deviation from the predetermined value. If this occurs, a signal will be issued to notify you of an abnormality.

In the above example, if the detected value is the most advanced position of the screw 1, -, the predetermined value is the value of the most advanced position of the screw in the holding pressure process in which a good molded product was obtained. If the detected value is the maximum value of the oil pressure in the injection hydraulic cylinder, it is the maximum oil pressure value in the injection hydraulic cylinder during the pressure holding step in which a good molded product was obtained.

(Problem to be Solved by the Invention) Conventional monitoring of the pressure holding process has been limited to monitoring during the pressure holding process, such as the most advanced position of the screw or the maximum hydraulic pressure in the injection hydraulic cylinder. Since it was used to monitor whether or not an abnormality occurred in the pressure holding process by simply comparing the instantaneous detected value at a point in time with a predetermined value determined in advance, it was possible to monitor whether an abnormality occurred during the pressure holding process other than at the point of detection. Even if an abnormality occurs, if the value at the time of detection matches the predetermined value to be compared, the abnormality cannot be discovered. Therefore, there is a risk that defective products due to molding abnormalities may be mixed in among the large number of molded products determined to be free of abnormalities.

- This is because even if the detected value at time point does not deviate from the predetermined value, it cannot be said that all of the processes at other time points are normal.

In order to eliminate defective products due to molding abnormalities, it is necessary to monitor the entire pressure-holding process from the start of the pressure-holding process to its completion, but if you try to monitor this using conventional methods, you will inevitably have to As the number of monitoring points increases and the number of monitoring points increases, the number of monitoring point settings also increases correspondingly, making the operation more complex and making the injection molding machine more expensive. There was a problem with putting it away.

The present invention aims to solve such problems.

The inventor has repeatedly conducted various experiments toward this purpose, and has discovered the following fact.

The point is that there is a strong correlation between the hydraulic pressure integral value in the injection hydraulic cylinder during the pressure holding process and the weight of the molded product, which is an important characteristic of molded product quality. Figure 1 is a diagram showing this correlation.The horizontal axis of Figure 0 shows the number of shots, the vertical axis shows the weight of the molded product, and the integral value of hydraulic pressure. It can be seen that there is an extremely strong correlation between this and the hydraulic pressure integral value.

The inventor further discovered that the value obtained by integrating the product of the hydraulic pressure in the injection hydraulic cylinder and the screw speed during the pressure holding process shows a strong correlation with the weight of the molded product. Figure 2 shows
It is a figure showing this correlation.

The horizontal axis of the figure is the number of shots, the vertical axis is the weight of the molded product, and from Figure 9, which shows the integral value of the multiplication value of oil pressure and speed, it is clear that the weight of the molded product and the integrated value of oil pressure x speed, which change from shot to shot, are very different. It can be seen that there is a strong correlation.

The present invention was made by paying attention to such experimental facts.

(Means for solving the problem) The first invention, a method for monitoring the pressure holding process of an injection molding machine, adjusts the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle from the start of pressure holding to the completion of pressure holding. The detected pressure value is time-integrated from the start of pressure holding to the time of completion of pressure holding to obtain an r-shaped component value, and the refined value is compared with a predetermined value R determined in advance.1. The purpose of this is to issue a signal when a deviation occurs between the two values.

The pressure holding process monitoring device for an injection molding machine, which is the second invention, includes a pressure detection means that continuously detects the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle, and an integrating means for time-integrating the detected pressure value from the start of pressure holding to the end of pressure holding; a setting means for presetting a predetermined value; and an integral obtained by the predetermined value set in the setting means and the integrating means. and a comparison means that compares the J' value with the J' value and issues a signal when a deviation occurs between the two values.

The third invention, a method for monitoring the pressure holding process of an injection molding machine, is @
The hydraulic pressure in the output hydraulic cylinder or the resin pressure in the injection nozzle and the moving speed of the screw are continuously detected from the start of pressure holding to the completion of pressure holding, and the detected pressure value and speed detection value are multiplied. , calculate the integral value by time-integrating the multiplication value from the start of pressure holding to the time of completion of pressure holding, compare the integrated value with a predetermined value set in advance, and if there is a deviation between the two values, @ The content is to issue a number.

The pressure holding process monitoring device for an injection molding machine, which is the fourth invention, is a pressure detection means that continuously detects the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle from the start of holding pressure to the completion of holding pressure Y. , a speed detection means for continuously detecting the moving speed of the screws and the screws from the start of pressure holding to the completion of pressure holding, a pressure detection value obtained by the pressure detection means and a speed detection value obtained by the speed detection means. a multiplication means for multiplying the multiplication value obtained by the multiplication means, an integration means for time-integrating the multiplied value obtained by the multiplication means from the start of pressure holding to the time of completion of pressure holding, a setting means for presetting a predetermined value, and a setting means for setting a predetermined value in advance; The integrated value obtained by the integrating means is compared with the predetermined value obtained by the integrating means, and a comparing means generates a signal when a deviation occurs between the two values.

(Effect) 1st. In the second invention, the integral value obtained by time-integrating the detected pressure value of either the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle from the time of starting pressure holding to the time of completion, It is compared with the integral value (predetermined value) obtained in advance when molding a good product, and if a deviation occurs, a signal is issued indicating that the pressure holding process is abnormal.

In the third and fourth inventions, the pressure detection value of either the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle at the holding pressure 1jJI start to completion value and the screw pressure from the start of holding pressure to the completion This multiplication value is then time-integrated from the start of holding pressure to the completion of holding pressure to obtain an integral value. If a deviation occurs, a signal is issued indicating that the pressure holding process is abnormal.

(Example) First, the first and second inventions will be explained based on the example shown in FIG.

In FIG. 3, 10 is a heating cylinder of an injection molding machine, 11 is a screw fitted into the heating cylinder, and 12 is an injection hydraulic cylinder that moves the screw forward and backward.

A pressure detector 13 is attached to the injection hydraulic cylinder 12 as a pressure detection means for detecting the hydraulic pressure within the hydraulic cylinder 12.

The hydraulic pressure inside the hydraulic cylinder 12 from the start of the pressure holding process to the completion of the pressure holding process is detected by this pressure! 113 , and the detected value is converted into an electrical quantity, for example, a voltage via a converter 22 and input to an integrator (integrating means) 14 .

The integrator 14 continuously integrates the continuously inputted detection values over time from the start of the pressure-holding process to the time of completion of the pressure-holding process, and when the pressure-holding process is completed. Find the final integral value of time.

On the other hand, a predetermined value is input into the setting device (setting means) 15 in advance.
- The above final integral value (reference value) obtained in step 1, or a reference range value that defines a numerical range that is acceptable for molding a non-defective product, centered around the final integral value.

Then, the final integrated value obtained by the integrator 14 and a predetermined value inputted to the setting device 15 are compared by a comparator (comparing means) 16.

As a result, when the final integral value deviates from the predetermined value, that is,
When the final integral value does not match the reference value or is not within the reference range value, the comparator 16 informs the control device 17 of the injection molding machine that there is an abnormality in the holding pressure process, that is, the shot is abnormal. Outputs an abnormal signal indicating that

When this abnormal signal is received, the control device 17 may immediately issue a warning of the abnormality with a patrol light or a buzzer, or may reject the molded product produced by the shot as a molding defect, or the shot for which the abnormal signal was issued may be The molding operation may be stopped when a predetermined number is reached;
11-7 may be output using a printer or the like and used as production monitoring information.

In the above embodiment, the detected value of the hydraulic pressure in the hydraulic cylinder 12 is input to the integrator 14, but instead of this detected value of hydraulic pressure, the resin pressure in the injection nozzle 24 is input as the detected value. This is because the resin pressure within the injection nozzle 24 is directly proportional to the hydraulic pressure within the injection hydraulic cylinder 12.

In addition, in this embodiment, the detected value of the hydraulic pressure in the cylinder, which is continuously detected from the start of the pressure holding process to the time when the pressure holding is completed, is immediately inputted to the integrator 14 as is. The detected value of the hydraulic pressure is temporarily stored in a storage device (not shown) by sampling from the time until the completion of pressure holding, and is integrated at once after the completion of pressure holding, regardless of the passage of time, until the next shot. The presence or absence of an abnormality may be monitored by comparing with a predetermined value.

Next, the third and fourth inventions will be explained based on the embodiment shown in FIG.

In FIG. 4, IO is a heating cylinder of an injection molding machine, 11 is a screw, and 12 is an injection hydraulic cylinder for moving the screw forward and backward.

The screw 11 is equipped with a speed detector (speed detection means) 20 for detecting the moving speed of the screw, and the injection hydraulic cylinder 12 is equipped with a pressure detection means for detecting the hydraulic pressure inside the hydraulic cylinder lz. A pressure detector 13 is attached.

The hydraulic pressure within the hydraulic cylinder 12 and the moving speed of the screw from the start of the pressure holding process to the completion of the pressure holding process are continuously detected by the pressure detector 13 and the speed detector 20.

And the hydraulic cylinder 12 obtained from the pressure detector 13
The detected value of the hydraulic pressure in the screw is converted into an electrical quantity, for example, a voltage via a converter 2z, and is applied to one input terminal of a multiplier (multiplying means) 21, and on the other hand, the detected value of the hydraulic pressure in the screw The detected value of the moving speed of be done.

The multiplied value obtained by the multiplier 21 is further input to an integrator 14 as a means for time integration.

The integrator 14 continuously integrates the continuously inputted multiplication values over time from the start of the pressure-holding process to the time of completion of the pressure-holding process, and calculates the holding pressure in the pressure-holding process. Find the final integral value upon completion.

On the other hand, a predetermined value is input into the setting device (setting means) 15 in advance. , is a reference range value that defines a numerical range that is acceptable for molding a good product, centered on the final integrated value.

Then, the final integrated value obtained by the integrator 14 and a predetermined value inputted to the setting device 15 are compared by a comparator (comparing means) 16.

As a result, when the final integral value deviates from the predetermined value, the comparator 16 informs the control device 17 of the injection molding machine that there is an abnormality in the pressure holding process, that is, that the seal is abnormal. Outputs an abnormal signal indicating. Abnormal signal is the control device! 117
When inputted to , processing can be performed in the same manner as in the above embodiment.

In this embodiment, the detected value of the hydraulic pressure in the hydraulic sill Iz is used as one of the values input to the 1 multiplier 2, but this detected value of the hydraulic pressure may be used instead.

Therefore, the resin pressure inside the injection nozzle 24 may be input as the detected value, because the resin pressure inside the injection nozzle 24 is directly proportional to the hydraulic pressure inside the injection hydraulic cylinder 12, as indicated by L.

In addition, in this embodiment, the re-detected values of the hydraulic pressure in the hydraulic cylinder 12 and the moving speed of the screw, which are continuously detected from the start of the pressure holding process to the completion of the pressure holding process, are immediately multiplied by the multiplier 21. Furthermore, the multiplied value is integrated with the time elapsed from the start of the pressure holding process, but the re-detected values of the hydraulic pressure and movement speed are temporarily stored in the storage device (Fig. (not shown), integrate it all together after the completion of holding pressure regardless of the passage of time, and compare it with the reference value by the second shot.
The presence or absence of an abnormality may be monitored.

(Effects of the Invention) According to the present invention, the pressure control process can be carried out in a rapid manner throughout the entire pressure holding process.
・Detect the pressure such as the oil pressure in the ring or the resin pressure in the injection nozzle, or the moving speed of the screws 1 and -, and integrate the detected values of
The obtained integral value is compared with the integral value (predetermined value) obtained in advance for molding a good product, and if a deviation occurs, a signal is issued indicating that the pressure holding process is abnormal. So, the results and 1, 7 are completed from the start of holding pressure t, T! It is possible to monitor the occurrence of abnormalities throughout the pressure holding process.

Therefore, compared to the conventional method of monitoring only one point in time during the pressure holding process, molding abnormalities can be detected more reliably.
Therefore, it is possible to eliminate the mixing of defective products into molded products that are considered to be good products.

Furthermore, if the entire pressure holding process was to be monitored using conventional monitoring methods, the number of monitoring points would have to be increased, which would make the structure and operation of the injection molding machine even more complex. According to the company, there are no such inconveniences.

Furthermore, since the present invention is constructed using simple means, it is possible to provide an injection molding machine at a price not much different from conventional ones, and it can be applied relatively easily to injection molding machines that are currently in operation. can be significantly improved.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram of the first and second inventions, Figure 2 is a basic configuration diagram of the third and fourth inventions, and Figure 3 is a diagram showing the correlation between hydraulic pressure integral value and molded product weight. , FIG. 4 is a diagram showing the correlation between the integral value of the product of hydraulic pressure and screw speed and the weight of the molded product. 10...Heating cylinder 11...Screw 1
2... Hydraulic cylinder for injection 13... Pressure detector (pressure detection means) 14... Integrator (integrating means) 15... Setting device (setting means) 16... Comparator (comparing means) 17... Control device 20... Speed detector (speed detection means) zl... Multiplier (multiplying means) z2. 23... Converter z4... Injection nozzle patent applicant Japan Steel Works, Ltd. Figure 2

Claims (1)

[Claims] 1. Continuously detects the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle in an injection molding machine from the start of pressure holding to the completion of pressure holding, and uses the detected pressure value as the start of pressure holding. The integrated value is obtained by time-integrating from the time point to the time point when the pressure holding is completed, and the integrated value is compared with a predetermined value set in advance, and if a deviation occurs between the two values, a signal is generated. A method for monitoring the pressure holding process of an injection molding machine. 2. A pressure detection means that continuously detects the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle in the injection molding machine, and the pressure detection value obtained by the pressure detection means is maintained from the time when pressure holding starts. an integrating means for time-integrating until the pressure is completed, a setting means for presetting a predetermined value, and a comparison between the predetermined value set in the setting means and the integral value obtained by the integrating means, and a deviation occurs between the two values. 1. A pressure holding process monitoring device for an injection molding machine, comprising a comparison means that issues a signal when the pressure is exceeded. 3. Continuously detect the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle and the moving speed of the screw from the start of pressure holding to the completion of pressure holding in the injection molding machine, and detect the detected pressure value and speed. The multiplied value is time-integrated from the start of holding pressure to the completion of holding pressure to obtain an integral value, and the integrated value is compared with a predetermined value set in advance to determine if there is a deviation between the two values. A method for monitoring the pressure holding process of an injection molding machine, which is characterized by emitting a signal when a pressure holding process occurs. 4. A pressure detection means that continuously detects the hydraulic pressure in the injection hydraulic cylinder or the resin pressure in the injection nozzle in an injection molding machine from the start of pressure holding to the completion of pressure holding, and a pressure detection means that maintains the moving speed of the screw from the start of pressure holding to the completion of pressure holding. speed detection means for continuously detecting the pressure until the pressure is completed; multiplication means for multiplying the pressure detection value obtained by the pressure detection means by the speed detection value obtained by the speed detection means; an integrating means for time-integrating the multiplied value from the time when the pressure holding starts to the time when the pressure holding is completed; a setting means for presetting a predetermined value; and an integrated value obtained by the predetermined value set in the setting means and the integrating means. 1. A pressure holding process monitoring device for an injection molding machine, comprising a comparison means for comparing the values and emitting a signal when a deviation occurs between the two values.