JPH0476767B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an injection molding machine, and particularly to a method and apparatus for setting a metering stroke adapted to the volume of a molded product in a mold.

[Conventional technology]

In conventional injection molding machines, the metering stroke after a mold change is set manually by an operator while observing the condition of the molded product in the previous shot at the start of molding, or manually in advance to set the metering stroke according to the volume of the molded product. The metering stroke was automatically changed for each shot by feeding back the screw position after the injection process was completed, and searching for an injection stroke suitable for the volume of the molded product.

[Problem to be solved by the invention]

In the conventional injection molding machine described above, the operator manually sets the metering stroke each time to find the optimal stroke, taking into account the volume of the molded product in the mold and the amount of resin shrinkage, so the expected setting of the metering stroke is difficult. This method has the disadvantage that it requires unnecessary molding production.

The present invention has been made in view of the drawbacks of the conventional techniques described above, and an object of the present invention is to provide an automatic injection metering stroke setting method and apparatus for automatically setting an optimum metering stroke.

[Means to solve the problem]

The injection metering stroke automatic setting method of the present invention is as follows:
When starting up the automatic injection process after replacing the mold, speed control injection is started with the metering stroke set to the maximum stroke, and as the mold is filled with resin, the moving speed of the screw decreases, and the moving speed is set in advance. When the speed reaches the first set speed or less, the speed control injection shifts to pressure control injection, and the pressure control injection further progresses the filling of resin into the mold, reducing the moving speed of the screw. The injection process is completed when the movement speed reaches a preset second setting speed or less, and the sum is calculated by adding the movement stroke of the screw in the injection process and the desired remaining amount stroke of the resin in the cylinder. is automatically set as the optimum metering stroke in the stroke setting controller.

Further, the injection molding machine of the present invention includes a speed setting device 1 in which the first set speed is set.
3, an injection completion speed setting device 16 for setting the second set speed, a remaining amount setting device 17 for setting the desired remaining amount stroke, and detecting the position of the screw 3 within the cylinder 1. , a screw stroke conversion mechanism and detector 7 that limit the screw stroke, a speed converter 11 that calculates the moving speed of the screw 3 from the position of the screw 3 detected by the screw stroke conversion mechanism and the detector 7, and a speed converter. The moving speed of the screw 3 determined by the device 11 is compared with the first set speed set in the speed setting device 13, and when the moving speed reaches the first set speed or less, the speed control injection is started. A first comparator 12 that outputs a pressure control command signal 12' instructing transition to pressure control injection; and a pressure control section 23 that receives the pressure control command signal 12' and performs pressure control in pressure control injection.
The moving speed of the screw 3 determined by the speed converter 11 is compared with the second setting speed set in the injection completion speed setting device 16, and the moving speed is determined to be the second.
a second comparator 15 that outputs an injection process completion signal 15' indicating completion of the injection process when the speed reaches a set speed or less; and a screw stroke conversion mechanism and Receiving the position information of the screw 3 at that point from the detector 7, the movement stroke of the screw 3 in the injection process is determined, and the movement stroke and the desired remaining amount stroke set in the remaining amount setting device 17 are calculated. A metering stroke setter 14 that adds the sum and determines the optimum metering stroke, and a maximum metering stroke is set at the time of startup of the automatic injection process after replacing the mold, and the subsequent injection process in that mold is It has a stroke setting controller that controls the metering stroke conversion mechanism and the detector 7 in accordance with the metering stroke determined by the metering stroke setter 14.

[Effect]

When starting up the automatic injection process after replacing the mold, the injection process is started at the maximum metering stroke, and during that injection process, the resin is filled into the mold and the injection speed is reduced, and the speed reaches the predetermined set speed. When the pressure decreases below, speed control injection shifts to pressure control injection.
After transitioning to pressure control injection, injection is continued while maintaining a predetermined injection pressure, and when the moving speed of the screw decreases to the arbitrarily set injection completion speed, the injection process is terminated as filling with resin at a constant pressure is completed. The screw movement stroke during the injection process and the specified
Since the desired residual amount stroke of resin is added and the sum is set as the optimum metering stroke in the stroke setting controller, the subsequent injection process can perform constant metering according to the set optimum metering stroke.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the automatic metering stroke setting method for an injection molding machine according to the present invention, and FIG.
The figure is a block diagram showing an example of a hydraulic circuit related to the injection molding machine of the present invention.

As shown in FIG. 2, the injection molding machine of this embodiment applies pressure to the injection cylinder 2 by a hydraulic circuit consisting of the injection cylinder 2, the hydraulic pump 6, and the electromagnetic proportional pressure servo valve 8, and the inside of the cylinder 1 is heated. The moving screw 3 is moved forward or backward to inject the molten resin in the cylinder 1 from the nozzle 4 into the mold 5. Furthermore, the screw stroke conversion mechanism and detector 7 shown in FIG.
The stroke setting controller 24 limits the movement stroke of the screw 3 within the cylinder 1, detects the position of the screw 3 at regular intervals, and uses the position information as shown in FIG.
It is transferred to the speed converter 11 via the amplifier 10.
Further, the pressure detector 9 is included in the pressure control section 23 shown in FIG.
The signal is transferred to the closed loop amplifier 19 via.

Next, explanation will be given with reference to FIG.

First, the position information detected by the screw stroke conversion mechanism and the detector 7 is transferred to the speed converter 11 via the amplifier 10 as described above. This speed converter 11 determines the moving speed of the screw 3 from the transferred position information and transfers the screw speed to the comparator 12. Comparator 12 is speed converter 1
Comparing the screw speed from 1 with the preset speed set in the speed setting device 13, when the screw speed decreases below the set speed, the switch 22 in the pressure control section 23 switches from speed control injection to pressure control injection. A pressure control command signal 12' instructing the transition to is output. Further, the screw speed is transferred to the comparator 15, and the comparator 15 compares the screw speed with the injection completion speed, which is preset in the injection completion speed setting device 16 and indicates the completion of the injection process, and determines the screw speed when the injection is completed. When the speed has decreased below the speed, an injection process completion signal 15' is output to the switch 21. The amplifier 10 described above is connected to the speed converter 11 and also to the switch 21, and the switch 21 receives the injection process completion signal 15' from the comparator 15.
When electrical conduction occurs, the position information of the screw 3 is transferred to the metering stroke setting device 14 via the switch 21. The metering stroke setting device 14 determines the movement stroke of the screw 3 in the injection process from the transferred position information, and calculates the movement stroke and the desired remaining amount of molten resin in the cylinder 1 preset in the remaining amount setting device 17. The stroke setting controller 24 is notified of the sum as the optimum metering stroke. The stroke setting controller 24 sets the maximum metering stroke in the injection process immediately after mold replacement, and the metering stroke setting controller 14 sets the maximum metering stroke in the injection process immediately after the mold is replaced.
The screw stroke conversion mechanism and the detector 7 are controlled according to the metering stroke set by. In addition, in the pressure control unit 23, when the pressure control command signal 12' is output from the comparator 12, the switch 22 is turned on and the setting to be applied to the injection cylinder 2, which is preset in the pressure setting device 18, is set. The pressure value is input to a closed loop amplifier 19. Further, the pressure value actually applied to the injection cylinder 2 detected by the pressure detector 9 is input to the closed loop amplifier 19 via the amplifier 20 . This closed loop amplifier 19
controls the electromagnetic proportional pressure servo valve 8 so that the pressure applied to the injection cylinder 2 becomes the set pressure value based on the difference between the set pressure value and the actually applied pressure value. Note that the above-mentioned comparator 12,
In step 15, the comparator 12 performs a comparison to determine the transition from speed control injection to pressure control injection in the injection process based on the speed set in the speed setting device 13, so the comparator 12 compares the speed set in the speed setting device 13 to determine the transition from speed control injection to pressure control injection in the injection process. The moving speed is the speed in speed controlled injection, and the comparator 15 compares the speed set in the injection completion speed setter 16 to determine the completion of the injection process. The moving speed in No. 3 is the speed in pressure-controlled injection.

Next, the operation of this embodiment will be explained.

Here, the set speed of the injection completion speed setter 16 is V ₀ , the set speed of the speed setter 13 is V ₁ , the set pressure of the pressure setter 18 is P ₀ , and the desired remaining amount stroke of the remaining amount setter 17 Let l ₁ be the set stroke of the screw 3 in the first injection process as the maximum stroke.

Now, if the automatic injection process is started under the above conditions, first, speed controlled injection is performed.
As the resin injection into the mold 5 progresses and the mold 5 is filled with resin, the moving speed of the screw 3 decreases, and when the moving speed reaches the aforementioned set speed V ₁ or less, the comparator 12 outputs a pressure control command signal 12'. This causes the injection process to shift from speed controlled injection to pressure controlled injection. When pressure control injection begins, the electromagnetic proportional pressure servo valve 8 is controlled by the closed loop amplifier 19 so that the pressure applied to the injection cylinder 2 becomes the set pressure P ₀ . This pressure causes the screw 3 to move, but as the mold 5 is further filled, the moving speed similarly decreases. Then, when the moving speed becomes equal to or less than the aforementioned set speed _V0 , it is determined that the injection process is completed, and the comparator 15 outputs an injection process completion signal 15'. The switch 21 is turned on by this injection process completion signal 15', and the position information of the screw 3 at that time is inputted to the metering stroke setting device 14. The metering stroke setting device 14 calculates the movement stroke of the screw 3 from the input position information and sets the remaining amount setting device 1.
Add it to the desired remaining stroke _l1 set to 7. The movement stroke of screw 3 at this time is l ₂
Then, the sum of the desired remaining stroke l ₁ (l ₁ + l ₂ )
The metering stroke setter 17 notifies the stroke setting controller 24 of the optimal metering stroke. As a result, the metering stroke (l ₁ +l ₂ ) is instructed to the screw stroke converting mechanism and the detector 7, and thereafter constant metering is performed according to the metering stroke (l ₁ +l ₂ ).

〔Effect of the invention〕

Since the present invention is configured as described above, it produces the effects described below.

The metering stroke setting parameters are set as the screw moving speed and pressure during resin injection, and the desired amount of resin remaining in the cylinder, so the metering stroke setting value is reproducible, and after replacing the mold,
Since the optimal metering stroke is automatically set for one molding production, it is possible to prevent wasted molding and mold damage due to incorrect metering stroke settings.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the automatic metering stroke setting method for an injection molding machine according to the present invention, and FIG.
The figure is a block diagram showing an example of a hydraulic circuit related to the injection molding machine of the present invention. 1...Cylinder, 2...Injection cylinder, 3...
Screw, 4... Nozzle, 5... Mold, 6... Hydraulic pump, 7... Screw stroke conversion mechanism and detector, 8... Electromagnetic proportional pressure servo valve, 9
...Pressure detector, 10, 20...Amplifier, 11...
...Speed converter, 12, 15...Comparator, 13...
Speed setting device, 14... Metering stroke setting device, 1
6... Injection completion speed setting device, 17... Remaining amount setting device, 18... Pressure setting device, 19... Close loop amplifier, 21, 22... Switch, 23... Pressure control section, 24... Stroke setting Controller, 15'...Injection process completion signal, 12'...Pressure control command signal.

Claims (1)

[Scope of Claims] 1. At the start of the automatic injection process after replacing the mold, speed control injection is started with the metering stroke set to the maximum stroke, and as the mold is filled with resin, the moving speed of the screw decreases. When the moving speed reaches a preset first setting speed or less, the speed control injection shifts to the pressure control injection, and the pressure control injection further progresses the filling of the resin into the mold, and the screw The injection process is completed when the movement speed of the screw decreases and the movement speed reaches a preset second set speed or less, and the movement stroke of the screw in the injection process and the desired remaining amount of resin in the cylinder are determined. A metering stroke automatic setting method for an injection molding machine that adds the stroke and automatically sets the sum as the optimum metering stroke in a stroke setting controller. 2. A speed setter 13 where the first set speed is set, an injection completion speed setter 16 where the second set speed is set, and a remaining amount setter 17 where the desired remaining amount stroke is set. , a screw stroke conversion mechanism and a detector 7 that detect the position of the screw 3 in the cylinder 1 and limit the screw stroke; The speed converter 11 calculates the moving speed of the screw 3, and compares the moving speed of the screw 3 calculated by the speed converter 11 with the first set speed set in the speed setting device 13, and determines whether the moving speed is the first. a first comparator 12 that outputs a pressure control command signal 12' instructing a transition from speed control injection to pressure control injection when the speed reaches a set speed of 1 or lower; , a pressure control section 23 that performs pressure control in pressure control injection.
The moving speed of the screw 3 determined by the speed converter 11 is compared with the second setting speed set in the injection completion speed setting device 16, and the moving speed is determined to be the second.
a second comparator 15 that outputs an injection process completion signal 15' indicating completion of the injection process when the speed reaches a set speed or less; and a screw stroke conversion mechanism and Receiving the position information of the screw 3 at that point from the detector 7, the movement stroke of the screw 3 in the injection process is determined, and the movement stroke and the desired remaining amount stroke set in the remaining amount setting device 17 are calculated. A metering stroke setter 14 that adds the sum and determines the optimum metering stroke, and a maximum metering stroke is set at the time of startup of the automatic injection process after replacing the mold, and the subsequent injection process in that mold is An injection molding machine comprising a stroke setting controller that controls the metering stroke conversion mechanism and the detector 7 according to the metering stroke determined by the metering stroke setter 14.