JPH04148913A - In-line screw type injection molder - Google Patents

Abstract

PURPOSE:To heighten the accuracy of sucking-back position after the metering of resin and consequently improve the molding stability of the injection molder concerned by providing a means for calculating the deviation between the command value of the position of a screw and its actual value, and a hydraulic driving source, which is controlled on the basis of the received deviation signal. CONSTITUTION:When sucking-back process is started by putting a variable capacity pump 14, a flow-controller 15 and the solenoid (b) of a solenoid directional control valve 11 into drive, the actual value x(t) of the position of a screw sent from a screw position detector 6 is brought through a signal converter 32 into a controller 30. The deviation signal, which is produced on the basis of the difference [XREF-x(t)] between the command value XREF=f(t) of the position of the screw calculating and setting on the basis of the actual value x(t=0) of the position of the screw at the start of controlling as the origin, is calculated and outputted through a control compensating operator 35 and a signal converter 37 so as to be inputted to the controller 15 in order to control the oil delivery of the pump 14 in response to the signal. As a result, the oil is sent to the oil chamber 5b of an injection cylinder 5 so as to retreat the screw 2 connected with the piston 5a of the cylinder 5, resulting in bringing the signal sent from the controller 30 to zero output so as to release the excitation of the solenoid (b) of the directional control valve 11 in order to bring the controlling of the sucking- back process to an end. Accordingly, the accuracy of sucking-back position is improved and its dispersion due to the resistance of resin is eliminated and overrunning is prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an in-line screw type injection molding machine.

(Prior art) Conventionally, resin is melted by a squirrel 7, stored in the front part of a heating cylinder, and then the screw is advanced.
An injection molding machine that injects molten resin from a nostle each time the material is melted and injected coaxially is called an in-line screw type injection molding machine.

In the type of in-line screw injection molding machine,
Each time the screw is rotated, the resin is transferred to the front of the heating cylinder while being melted, while the screw is pushed back by the pressure of the resin.

The amount of melted resin in the container is measured by the distance the screw is pushed back, and when it reaches a designated position, the rotation of the screw is stopped.

Here, before the injection stage begins, a sack pack process is performed. In the sack pack process, the screw is retracted to a predetermined position to reduce the resin pressure and remove the resin accumulated in front of the flask. Rub it to make sure it doesn't leak from the nozzle.

In this case, a position detector, proximity switch, etc.
The position of the injection cylinder is detected and the injection cylinder is moved back until it reaches the set position. The control for this purpose is performed by speed control that uses the screw speed as the control target.

(Problem to be Solved by the Invention) However, in the conventional inline screw type injection molding machine described above, when the screw is retracted to the jack-hack position, the resistance changes depending on the type of resin and the resin melting temperature, resulting in overrun. The position of the Zack hack varies.

As a result, not only will the injection start position vary and molding stability will be impaired, but if the overrun amount is too large, air will be sucked in from the nozzle tip, which will be drawn into the molten resin and molded. This may cause defects.

The present invention solves the problems of the conventional in-line screen type 4 injection molding machine, improves the accuracy of the sack bank position after resin measurement, improves molding stability, and eliminates molding defects. The purpose is to provide an in-line screw type injection molding machine that can be used in a variety of ways.

(Means for Solving the Problem) For this purpose, the inline screw injection molding machine of the present invention includes a screw position detector that detects the screw position and outputs the screw position actual value, and a screw position detector that detects the screw position and outputs the screw position actual value, and the screw position as a function of time. a screw position setting device that outputs a position command value, a means for determining the deviation between the screw position command value and the actual screw position value, a hydraulic drive source that is controlled in response to a signal of the deviation, and the hydraulic drive. The injection cylinder is supplied with oil discharged from a source.

The hydraulic drive source is configured with a variable displacement pump that controls the discharge pressure and discharge flow rate, or is configured with either a constant displacement pump or a load sensing type variable displacement pump and a flow rate adjustment valve.

(Function) According to the present invention, as described above, there is provided a suflip position detector that detects the screw position and outputs the actual screw position value, and a screw position setting device that outputs the sufflip position command value as a function of time. -1- Means for determining the deviation between the script 1 position command value and the actual slurry 1 position value, a hydraulic drive source that is controlled in response to the signal of the deviation, and a supply of oil discharged from the hydraulic drive source. Injection solid...da, 1
1: We'll have a joint meeting.)6. '', since there is a current C, in the case of 4F pricking ball, 1 is set in advance as a function of time, the screw position command value and the position actual value (
a=J: is compared, and the screen L is moved back by the deviation.

(Actual Examples) Hereinafter, detailed explanations will be given regarding the embodiments of the present invention without referring to page 1.

Figure η1 is a schematic diagram of the in-line screw type injection molding machine of the present invention.

In the figure, 1 is a heating cylinder, 2 is a screw supported so as to be movable forward and backward and rotatable inside the heating cylinder l, and 3 is a space in front of the heating cylinder.
When the heating cylinder is retracted, resin is collected in the space in front of the heating cylinder. Reference numeral 4 denotes a resin supply port, and the resin naturally falls into the heating cylinder 1 through the resin supply port 4 during the metering process.

5 is an injection cylinder for moving the screw 2 back and forth, and has oil chambers 5b and 5c before and after the screw 5a. a screw position detector that detects the position of the screw 2 moved by the 6ε auto-recording injection cylinder 5;
7 is a screwdriver, and an oil motor 1 for rotating j-2.
．． 8 is a U-rotation speed detector for detecting the rotational speed of the oil motor, and 9 is a nozzle for injecting resin.

Reference numeral 11 denotes an electromagnetic force directional switching valve connected to the oil chamber 5h of the injection cylinder 5, which in the position (3) is directed to the oil tank 12 in the oil chamber 5h, and in the opening position is a variable displacement type valve. Oil from the pump 14 is supplied to the oil chamber 5b. The variable displacement pump 14 can control pressure and flow rate, and is equipped with a flow rate controller 15.

Reference numeral 17 denotes an electromagnetic directional control valve, which injects oil from the variable displacement pump 14 into the oil chamber 5 of the cylinder 5 in the position ①.
At the position ■, the oil in the oil chamber 5c is supplied to the oil chamber 5c, and at the position ■, the oil from the variable displacement pump 14 is supplied to the oil motor and at the same time, the oil in the oil chamber 5c is diverted.

20 is a relief valve, and 21 is a proportional electromagnetic relief valve.

In the inline screw type injection molding machine with the above configuration,
The resin supplied from the resin supply port 4 to the rear end of the heating cylinder 1 is sent forward by the rotation of the screw 2 and the heat from the heating cylinder 1, and is heated and compressed to be plasticized, and the molten resin is It is stored in the space 3 in front of the screw 2.

At this time, the screw 2 is rotated by the oil motor 7, and the rotation speed detector 8 detects the rotation of the screw 2. Meanwhile, the injection cylinder 5 allows the screw 2 to rotate and moves in the axial direction.

The proportional electromagnetic relief valve 21 is for generating back pressure when the screw 2 retreats. In addition, after the electromagnetic directional control valve 11 has completed metering, the screen 12 is forcibly retracted to prevent the resin from leaking from the nozzle 9 and to lower the resin pressure in the front space 3. Do a hack.

FIG. 2 shows the control valve 1-ζ of the in-line screw injection molding machine of the present invention.

In the figure, 6 is a screw position detector, and a signal detected by the screw position detector 6 is sent to a control device 30. The control device 30 is composed of a device having an arithmetic function, such as a microcomputer.

In the control device 30, the screw position detected by the screw position detector 6 is converted into a signal by the signal converter 32, and the actual position value x (t)
The signal is sent to the subtracter 34 as a feedback signal.

On the other hand, the reflux position setting device 31 calculates and sets the screw position command value as a time function XREF =f (t) based on x (t=0) at the start of the buckback control.

In the multiplication calculator 34, ζ is calculated as a deviation sign between the position command value X REF of the step 911 and the actual screw position value x(t). Then, the deviation symbol is the control compensation calculator 3
5, the output value thereof is converted into a driving signal by a signal converter 37, and is input to the flow rate controller 15.

In the in-line screw injection molding machine having the configuration described in 1- above, when the variable displacement pump 14, the flow rate controller 15, and the solenoid b of the electromagnetic directional control valve 17 are driven, the oil discharged from the variable displacement pump 14 is moved to the m position. The oil is sent to the oil motor via a certain electromagnetic directional switching valve 17, and the oil motor 7 rotates.

When the oil motor 7 rotates, the screw 2 is rotated accordingly, and the resin that has entered from the resin supply port 4 is sent out in the AiT direction while being subjected to mechanical shearing and being moved by the filter wound around the heating cylinder 2. Heated from outside. As a result, the resin is plasticized and melted and stored in the front space 3 of the heating cylinder 1, and the screw 2 is retracted.

When the screw 2 retreats to the preset metering position, the variable displacement pump 14, the flow rate controller 15, and the electromagnetic directional control valve 17 are deactivated, and the flow rate process is completed.

Here, a suck-huck position is started so that the resin stored in the front space 3 of the heating cylinder 1 does not leak from the nozzle 9.

By driving the variable displacement pump 14, the flow rate controller 15, and the b solenoid of the electromagnetic directional control valve 11, the oil discharged by the variable displacement pump 14 is transferred through the electromagnetic directional control valve 11 located at the position ■. Oil chamber 5b of injection cylinder '5
supply to. Part 1. +1 result, the scree j, 2 is forcibly retreated (zuck-huck) to a preset suck-huck position, and the pressure of the resin in the front space 3 is lowered by controlling as follows.

iiJ transformation transformation wooden pump 14 star controller 15, electromagnetic direction cut (☆ Drives the b solenoid l of valve 11 j-7, Sanokuha,
When the process starts, the actual screw position value x(t) sent from the screw position detector 6 is taken into the control device 30 via the signal converter 32. Then, based on the screw actual value x(t-0) at the start of control, the difference (X REFx( t)) is calculated.

This deviation signal is inputted to the control compensation calculator 35, and the control compensation calculator 35 performs a plurality of calculations including gain adjustment.

The control signal outputted via the control compensation calculator 35 and the flash converter 37 is input to the flow rate controller 15, and the amount of oil discharged from the variable displacement pump 14 is controlled in accordance with the control signal. Then, oil is sent to the oil chamber 5b of the injection cylinder 5, and the screw 2 fastened to the piston 5a of the injection cylinder 5 is retracted.

Here, the screw position setting device 31 calculates and sets a continuous signal from the current position of the screw 2 to the position where the back bank process is completed. When the screw 2 reaches the hack completion position or reaches the vicinity, the deviation signal (
XohF-x(t)] becomes less than or equal to a preset setting reference value.

χIIEF x(t) l≦ULJ: Setting reference value Then, the control signal sent from the control device 30 becomes 0 output, and at the same time, the excitation of the b solenoid of the electromagnetic directional control valve 11 is released, and the control of the zip bank process is completed. becomes.

Note that the present invention can also be applied to the control of the lower culm of the seventh culm when it is performed before weighing.

The above embodiment describes the case where a proportional electromagnetic variable displacement pump that performs pressure/meteor control is used.
It can also be applied when a fixed displacement pump or a variable displacement pump with rotary sensing is used as the hydraulic drive source.

FIG. 3 is a hydraulic circuit diagram of an in-line screw type injection molding machine showing a second embodiment of the present invention.

In the figure, 5 is an injection cylinder provided for forward and backward movement of the screw 2, and is connected to an electromagnetic flow control valve or servo valve 39 for suckback. Oil is sent to the servo valve 39 from a constant displacement pump or a rotary sensing variable displacement pump 40.

In this case as well, a control device similar to the control device shown in FIG. 2 is provided, and in this control device a position command value The actual screw position value xQ) converted by the device 32 is fed to the feedbank, and a deviation signal is calculated.

Then, the deviation signal is sent to the control compensation calculator 35, and the output value is inputted to the proportional electromagnetic flow rate adjustment valve or servo valve 39 via the signal converter 37, and the screw position control in the sack bank process is performed. It looks like this.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention - TJ: G
``+, excluding these from the scope of the present invention (Z is ``Zui'').

(Effects of the Invention) As described in detail above, according to the present invention, there is provided a screw position detector that detects the screw position and outputs the actual screw position value, and a screw position detector that outputs the screw position command value as a function of time. A position setting device, means for determining the deviation between the actual screw position value and the screw position command value, a hydraulic drive source that is controlled in response to a signal of the deviation, and oil discharged from the hydraulic drive source is supplied. Since the injection cylinder is designed to have an injection cylinder, in the zip bank process, the screw position set in advance due to the change in time is compared with the actual screw position value, and the screw is retracted so that there is no deviation.

Therefore, the suck-huck position accuracy is improved, and variations due to resin resistance values affected by the type of resin and melting temperature are eliminated, and overrun oozing can be prevented.

And 1. Since the screw retraction speed is smoothly reduced from the start of suckback to the time when the shark hook is completed, the stability can be improved to the same degree as the sack hack.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram of an in-line screw type injection molding machine of the present invention, Fig. 2 is a control block diagram of an in-line screw type injection molding machine of the present invention, and Fig. 3 is an in-line diagram showing a second embodiment of the present invention. It is a hydraulic circuit diagram in a screw type injection molding machine. DESCRIPTION OF SYMBOLS 1... Heating cylinder, 2... Screw, 5... Creation cylinder, 6... Screw position detector, 7... Oil motor, 1.1. , 1.7... Solenoid directional valve, 14...
...Variable displacement pump, 1,5...Flow rate controller, 3]
・・・Suflip, i device setting device, 39... 勺-bo valve. Patent applicant Sumitomo Heavy Industries, Ltd. Sub-agent Patent attorney Makoto Kawagoi (1 other person) Fig.

Claims (3)

[Claims] (1) (a) A screw position detector that detects the screw position and outputs an actual screw position value; (b) A screw position setting device that outputs a screw position command value as a function of time; (c) The screw position detector that outputs a screw position command value as a function of time; means for determining the deviation between the position command value and the actual screw position value; (d) a hydraulic drive source that is controlled in response to a signal of the deviation; and (e) an injection source to which oil discharged from the hydraulic drive source is supplied. An in-line screw type injection molding machine characterized by having a cylinder. (2) The in-line screw injection molding machine according to claim 1, wherein the hydraulic drive source is a variable displacement pump that controls discharge pressure and discharge flow rate. (3) The in-line screw injection molding machine according to claim 1, wherein the hydraulic drive source comprises either a constant displacement pump or a load sensing variable displacement pump and a flow rate adjustment valve.