JPH0310823A - Monitoring device for injection molding machine - Google Patents

Abstract

PURPOSE:To enhance the discrimination properties of a molded form by equipping a setter for presetting a range of the molded form of the moldings, a comparator for discriminating whether each detected value is within the range of the desired form or not and an output device for outputting the result discrimination by the comparator for a reference profile. CONSTITUTION:A revolution indicator 19 for detecting r.p.m. of a screw 2, a detector 20 for detecting the velocity of the screw, a detector 21 for detecting the pressure in a hydraulic motor 3 and a detector 23 for detecting the position of the screw 2 are provided. These detectors 19, 20, 21, 23 are connected to a detected value memory device 30. The value continuously detected by the respective detectors is inputted to the device 30 and a reference profile is formed. On the other hand, an allowable range setter 32 connected to a profile indicator 31 sets a range of the desired form of the moldings for the reference profile. After molding is started, each detected value is detected at every shot. It is discriminated by a comparator 33 connected to the device 30 to determine whether the profile is within the range of the desired reference value or not. A discrimination signal is output by an output device 34 thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a monitoring device for an injection molding machine for determining whether a molded product is a good product or not.

(Prior art) Conventionally, injection molding involves injecting a molding material heated and fluidized in a heating cylinder into a mold under high pressure, cooling and solidifying or hardening the molding material, and then opening the mold to take out the molded product. There is a screw type machine that performs injection molding by moving the screw inside the heating cylinder back and forth.

When determining the quality of a molded product obtained by the above-mentioned injection molding machine, the injection pressure, screw position, etc. in a specific state or process are monitored, or the measuring or filling time is monitored.

FIG. 5 is a schematic diagram of a conventional injection molding machine.

In FIG. 5, a screw 2 is supported inside a heating cylinder 1 of an injection molding machine so as to be rotatable and movable back and forth, and is connected to a drive system consisting of a hydraulic cylinder 3 and a hydraulic motor 4, and is rotated by the drive system. and move forward and backward.

The state of the screw position shown in FIG. 5 is the state where the injection molding shot has been completed, but here, prior to the next shot, the work of melting and plasticizing the resin 5 and storing it at the tip of the head, that is, measurement is performed. In the measuring process, the screw 2 is driven by the hydraulic motor 4 and rotates, and at this time,
The resin 5 dropped and supplied from the material supply port 10 is melted and plasticized within the heating cylinder 1 while moving forward in the groove 6 by the rotation of the screw 2, and is stored at the front end of the screw 2.

The pressure of the resin 5 in the heating cylinder 1 generated during melting and plasticization becomes a reaction force against the screw 2, and the reaction force causes the screw 2 to retreat to a preset position.

In this way, the resin 5 stored at the front end of the screw 2 is
Subsequently, the screw 2 is pushed forward by the hydraulic cylinder 3, and is injected from the nozzle 7 into the cavity 9 of the mold 8.

By the way, after the filling process is completed, a constant injection hydraulic pressure is applied to compensate for the cooling and shrinkage of the resin 5 in the cavity 9. When this pressure holding step is completed, the screw 2 rotates again and measurement is performed.

Therefore, in the above-mentioned conventional injection molding machine, in order to perform various controls and monitoring of the injection molding machine, a screw tachometer 19 that detects the number of rotations of the screw 2, a speed detector 20 that detects the screw speed, a hydraulic motor 3 A pressure detector 21 for detecting the pressure inside the cavity 9, a pressure detector 22 for detecting the pressure inside the cavity 9, and a screw position detector 23 for detecting the position of the screw 2 are provided.

When determining the quality of each molded product molded by an injection molding machine, for example, the injection pressure during the filling process and pressure holding process is detected by the oil pressure in the hydraulic motor 3 or the resin pressure in the cavity 9, and The molded product is continuously sampled and compared with standard values to determine whether the molded product is good or bad.

In other injection molding machines, the screw position 23 and the time of each measuring and filling process in a specific state are monitored items.

In other words, by monitoring both the limit values of the screw position when switching between the filling process and the pressure holding process, changes in fluidity due to changes in mold conditions can be detected, and molded product quality such as sink marks and overback can be monitored. By monitoring the upper and lower limits of the screw position when the holding pressure is completed, the stability and reproducibility of the molded product can be determined by whether the amount of resin filled in the cavity 9 is the same for each shot. Ru.

By monitoring the upper and lower limits of the metering time in the metering step, it is determined whether the quality of the molded product has deteriorated due to problems such as clogging, changes in resin viscosity, or the like.

(Problem to be Solved by the Invention) However, in the monitoring device for an injection molding machine having the above configuration, only the pressure in a specific process during molding, such as the filling process, pressure holding process, or metering process, is continuously monitored. It monitors the screw position in a specific state of each process and the time required for each process, but does not detect changes in the molding state during all processes, so it is difficult to improve the discrimination performance of molded products. As a result, defective products may be mixed in with good products.

The present invention solves the problems of the conventional injection molding machine monitoring device described above, and provides an injection molding machine monitoring device that can improve the discrimination of molded products by monitoring the molding status of all processes. The purpose is to provide.

(Means for Solving the Problems) To this end, the present invention provides a detector that continuously detects the screw position, injection pressure, screw speed, and screw rotation speed during the entire process including filling, holding pressure, and metering, and the screw rotation speed during the metering process. a storage device for storing each of the detected values, a display device for displaying a standard profile of the detected values stored in the storage device, a setting device for setting a non-defective range of the molded product with respect to the standard profile; It has a comparator that determines whether the detected value falls within the non-defective range, and an output device that outputs the determination result of the comparator.

(Function) According to the present invention, there is provided a detector that continuously detects the screw position, injection pressure, screw speed, and screw rotation speed during the metering process in all processes including filling, pressure holding, and metering, and each of the above detected values. a display device for displaying a standard profile of detected values stored in the storage device; a setting device for setting a non-defective range of a molded product with respect to the standard profile; Since it has a comparator that determines whether or not it is inserted, and an output device that outputs the determination result by the comparator, it is possible to improve the molded product determination performance.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a control system diagram of a monitoring device for an injection molding machine showing an embodiment of the present invention, Fig. 2 is a diagram showing a reference profile when monitoring the screw position, and Fig. 3 is a diagram showing the reference profile when monitoring the screw position. FIG. 4 is a diagram showing a profile outside the non-defective range when the screw position is monitored.

In the figure, a screw 2 is supported inside a heating cylinder 1 of an injection molding machine so as to be freely rotatable and move forward and backward, and is connected to a drive system consisting of a hydraulic cylinder 3 and a hydraulic motor 4. be made to proceed.

After the injection molding shot, ie, the filling process, is completed, the resin 5 is melted, plasticized, and stored at the tip of the head, ie, weighed. In the metering step, the screw 2 is driven by the hydraulic motor 4 and rotates, and at this time, the resin 5 that is dropped and supplied from the material supply port IO moves forward in the groove 6 due to the rotation of the screw 2. While doing so, it is melted and plasticized in the heating cylinder 1 and stored at the front end of the screw 2.

5. Resin inside heating cylinder 1 generated due to melting and plasticization.
The pressure acts as a reaction force against the screw 2, and the reaction force causes the screw 2 to retreat to a preset position.

In this way, the resin 5 stored at the front end of the screw 2 is
Subsequently, the screw 2 is pushed forward by the hydraulic cylinder 3, and is injected from the nozzle 7 into the cavity 9 of the mold 8.

After the filling process is completed, a constant injection hydraulic pressure is applied to compensate for the cooling and shrinkage of the resin 5 in the cavity 9. When this pressure holding step is completed, the screw 2 is rotated again and measurement is performed.

In the injection molding machine having the above configuration, in order to determine the quality of the molded product, a screw tachometer 19 detects the number of revolutions of the screw 2, a speed detector 20 detects the screw speed, and a pressure inside the hydraulic motor 3 is detected. A pressure detector 21 and a screw position detector 23 for detecting the position of the screw 2 are provided.

These detectors 19, 20, 21, and 23 are connected to a detection value storage device 30, and the detection values continuously detected by each detector 19, 20, 21, and 23 are stored in the detection value storage device 30. input and form a reference profile. For example, in the case of screw position, the reference profile is
As shown in FIG. 2, the relationship between screw position S and time is stored.

The detected value storage device 30 includes a profile display device 31
is connected to and the stored reference profile is displayed.

On the other hand, an allowable range setting device 32 connected to the profile display device 31 sets the non-defective range of the molded product with respect to the reference profile, as shown in FIG.

After molding starts, each detection value is detected for each shot,
A comparator 33 connected to the detected value storage device 30 determines whether the profile falls within the above-mentioned non-defective range. Then, as shown in FIG. 4, if the detected profile is outside the non-defective range, a discrimination signal output device connected to the comparator 33 outputs a discrimination signal indicating that the product is defective.

As mentioned above, the comparison between the standard profile and the profile for each shot is achieved by continuously detecting the screw position, injection pressure, screw speed, and screw rotation speed during the entire process including filling, holding pressure, and metering, as well as the screw rotation speed during the metering process. However, if any one of the monitoring items exceeds the non-defective range, the product will be determined to be defective even if the other items are within the non-defective range, or a specific detection Defective products are determined based on value only.

Note that the present invention is not limited to the above embodiments,
For example, various modifications can be made based on the spirit of the present invention, such as a drive system using an electric motor instead of hydraulic pressure, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As explained above, according to the present invention, the screw position, injection pressure, screw speed, and screw rotation speed during the metering process are continuously detected in all processes including filling, pressure holding, and metering. a detector, a storage device that stores each of the detected values, a display that displays a reference profile of the detected values stored in the storage device, and a display device that displays a reference profile of the detected values stored in the storage device;
It has a setting device that sets the non-defective range of the molded product, a comparator that determines whether each detection value falls within the non-defective range, and an output device that outputs the judgment results of the comparator. This makes it possible to improve the discrimination performance of molded products compared to the case where only the state of the product or specific monitoring items are monitored.

[Brief explanation of drawings]

Fig. 1 is a control system diagram of a monitoring device for an injection molding machine showing an embodiment of the present invention, Fig. 2 is a diagram showing a reference profile when monitoring the screw position, and Fig. 3 is a diagram showing the reference profile when monitoring the screw position. FIG. 4 is a diagram showing a profile outside the non-defective range when screw position is monitored, and FIG. 5 is a schematic diagram of a conventional injection molding machine. DESCRIPTION OF SYMBOLS 1... Heating cylinder, 2... Screw, 3... Hydraulic cylinder, 4... Hydraulic motor, 5... Resin, 6...
... Groove, 7... Nozzle, 8... Mold, 9... Cavity, 19... Screw rotation speed, 20... Screw speed detector, 21... Pressure detector, 23... ...Screw position detector, 30...Detected value storage device, 31...
- Profile display device, 32...Tolerance range setting device, 33...Comparator, 34...Discrimination signal output device.

Claims (1)

[Scope of Claims] (a) A detector that continuously detects the screw position, injection pressure, screw speed, and screw rotation speed during the entire process including filling, holding pressure, and metering, and (b) the above-mentioned a storage device that stores each detected value; (c) a display device that displays a standard profile of the detected values stored in the storage device; and (d) a setting device that sets a non-defective range of molded products with respect to the standard profile. (e) a comparator that determines whether each detected value falls within a non-defective range; and (f) an output device that outputs a determination result by the comparator. .