JPH0813484B2 - Injection molding machine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a hydraulic mechanism that supplies pressure oil to an injection cylinder of an in-line screw type injection molding machine.

Conventional technology Conventionally, the injection speed when injecting the molten resin stored in the tip of the heating cylinder of the in-line screw injection molding machine from the tip nozzle is the amount of oil sent to the injection cylinder, which is the servo valve or the electromagnetic proportional flow control valve. It is general to control by etc.

Problems to be Solved by the Invention The repeatability of the servo valve or the electromagnetic proportional flow valve described in the prior art has a variation of about 0.5 to 1% of the maximum allowable flow rate. For example, in a valve with a rated flow rate of 200 l / min. Since an error of about 1 to 2 l / min occurs, it is almost impossible to smoothly control from the allowable flow rate to zero flow rate. Therefore, the lower limit of the stable control width is 5 to 10% of the maximum flow rate.
Up to that point, variations in the flow rate will be large and the repeatability of injection speed will be poor, which will adversely affect the quality of the molded product. Therefore, low speeds of 5 to 10% or less are not used as much as possible. The current situation.

However, for some thick-walled products such as lenses, for example,
Some users require extremely slow injection speeds of about 0.5 mm / sec, and users who want to mold general molded products on the same machine due to the machine operation rate are aware of instability and use the low-speed region to produce products. Do you endure that the dead end worsens
Do you endure inefficiency using a low speed injection molding machine,
There was a problem that either one had to be selected.

The present invention has been made in view of the above problems of the conventional technique, and an object of the present invention is to provide an injection molding machine capable of smoothly controlling an injection speed from a high speed to an extremely low speed. It is what

Means for Solving the Problems In order to achieve the above object, in an injection hydraulic mechanism of an in-line screw type injection molding machine according to the present invention, two throttles are provided in a circuit for supplying pressure oil to a screw pushing side airtight chamber of an injection cylinder. A flow control valve for simultaneous control is provided, a bypass passage for the flow control valve is provided, a first opening / closing valve member that opens the bypass passage at a high injection speed is provided, and two throttles of the flow control valve are connected in parallel. And a second opening / closing valve member for opening one throttle circuit of the double pass circuit at a low injection speed is provided, and at the time of high injection speed, the adjusted original pressure is directly supplied to the injection cylinder via the bypass passage. At the low speed, the pressure oil whose flow rate is adjusted by the double-pass circuit and the flow control valve's two throttles is supplied to the injection cylinder, and at the very low speed, the other throttle of the flow control valve is supplied. It is possible to switch to three ranges for supplying pressure oil whose flow rate is adjusted only by the circuit to the injection cylinder.

In addition, in the injection hydraulic mechanism of the inline screw type injection molding machine, a first flow rate control valve having a large capacity and a second flow rate control valve having a small capacity are provided in a circuit that supplies pressure oil to the screw pushing side airtight chamber of the injection cylinder. Arranged in series,
A bypass passage for the second flow control valve is provided, and an opening / closing valve member for opening the bypass passage is provided. At a high injection speed, the pressure oil whose flow rate is adjusted by the first flow control valve is directly injected through the bypass passage. To the first and second at extremely low speed
It is possible to switch between two ranges in which the pressure oil whose flow rate is adjusted by the flow rate control valve is supplied to the injection cylinder.

According to the injection molding machine of the present invention, the first opening / closing valve member opens the bypass passage, the flow rate is adjusted by the flow control valve having a large capacity to create a high speed range, and the second opening / closing valve member forms a double path having two throttles. By switching to single-pass, a low flow rate range is created by adjusting the combined flow rate by two throttles connected in parallel, and an ultra-low speed range by adjusting the flow rate by only one throttle.

The injection molding machine according to claim 2, wherein the opening / closing valve member opens and closes the bypass passage of the second flow control valve (one throttle) to adjust the flow rate by the first flow control valve to provide a high speed range, and the second flow control valve. Create an extremely low speed range by adjusting the flow rate.

First Embodiment A first embodiment will be described with reference to FIGS. 1 and 2.

In the well-known in-line screw type injection molding machine,
The rear end of the heating cylinder 2 is fitted in the concentric hole 1b formed in the frame 1a of the injection cylinder 1, and a plurality of band heaters 3 are attached to the outer periphery of the heating cylinder 2 in groups. Each heating zone is formed. A plurality of thermocouples 4 are attached to each zone in order to maintain the temperature suitable for the material used. Heating cylinder 2
A screw 5 formed such that the root diameter of the bottom of the screw groove gradually increases toward the front is inserted into the center hole of the so as to be rotatable and axially movable. The screw 5 is directly connected to the piston 6 fitted in the injection cylinder 1, and is driven by a rotation drive device (not shown) and is axially moved by the pressure oil supplied to the injection cylinder 1. A cylinder cap 7 is screwed onto the tip of the heating cylinder 2, and a nozzle (not shown) is screwed onto the tip of the cylinder cap 7. Further, the frame 1a has a discharge port 8a that opens at a rear position where the root diameter of the screw 5 is small.
The material supplying popper 8 having the above is attached.

The pressure oil mechanism that supplies pressure oil to the injection cylinder 1 is a pump.
An electromagnetic proportional pressure control valve 13 for setting the required maximum pressure in each process is provided in parallel to the discharge port of 11 through a pipe line 12, and the discharge port of the pump 11 is further described below via a pipe line 14. The electromagnetic proportional flow control valve 15 is also connected to the a port of the two-position solenoid switching valve 17 for speed range switching and the d-port of the two-position solenoid switching valve 18 for single-pass / double-pass switching via the pipe 16. . The flow rate control valve 15 is for controlling the amount of oil on the high speed side by moving the control valve according to a command from the controller of the machine (not shown), and has a large capacity that can set the maximum discharge amount of the pump 11 as 100%. Is used. The outlet of the flow control valve 15 is a line 19 for injection / suckback switching 3
It is connected to the port g of the position solenoid switching valve 21, and the switching valve
21's j port is connected to the drain circuit. The h port of the switching valve 21 is communicated with the front chamber of the injection cylinder 1 through a pipe line 22, and the i port is connected with one throttle 24a of a low speed electromagnetic proportional flow control double valve 24 described later through a pipe line 23. In addition to being communicated with each other, they are also communicated with the k port of the cartridge check valve 26 and the m port of the cartridge check valve 27 through the conduit 25. The outlet of one throttle 24a of the double valve 24 is connected to the rear chamber of the injection cylinder 1 via a pipe 28, and the rear chamber of the injection cylinder is further connected via a pipe 29 to the other throttle 24b of the double valve 24. The cartridge check valve is connected to the outlet of the
It communicates with 27 n ports. Further, the inlet of the other throttle 24b of the double valve 24 and the l of the cartridge check valve 26
The ports are communicated with each other by a pipe 32. The n port of the cartridge check valve 27 is connected to the O port of the two-position electromagnetic switching valve 34 via the pipe 33, and the p port of the switching valve 34 is connected to the drain circuit. ing. The proportional flow control double valve 24
The two diaphragms 24a and 24b are controlled at the same amount by one solenoid at the same time. For example, 0811-40 manufactured by Bosch, West Germany.
No. 3-001 or the like can be used. In this embodiment, the one having a relatively small allowable maximum flow rate is used because it is used for low speed. Two throttles 24a and 24b are connected in parallel. In the case of the double-pass circuit described above, for example, 1/5 of the maximum allowable flow rate of the proportional flow control valve 15 and 1/10 of the maximum maximum flow rate of the single-pass throttle circuit having only one throttle are used. Further, the flow rate control valve 15 and the flow rate control double valve 24 each have a valve pressure difference compensation circuit.

Further, the Q port of the cartridge check valve 26 is in communication with the e port of the electromagnetic switching valve 18 by the pipe 35, and the r port of the cartridge check valve 27 is in communication with the b port of the electromagnetic switching valve 17 by the pipe 36. , C port and f port are both connected to the drain circuit by a conduit 37.

The cartridge check valve 27 is used because a large amount of oil at high speed flows from the m port to the n port when the solenoid of the electromagnetic switching valve 17 is energized (ON) and switched to the A position. However, other valves can be used as long as the flow rate can be secured.

 Next, the description of the first embodiment will be described.

When setting the injection speed to the high speed range side first,
As shown in the figure, the solenoid SOL2 of the solenoid operated directional control valve 17 is turned off and switched to the A position regardless of whether the solenoid control valve 18 is electrically energized (ON) or not energized (OFF). In the plasticizing step, the screw 5 is rotated by a rotation drive device (not shown), and as the molten resin is stored at the tip of the heating cylinder, the molten resin is retracted by the reaction force of the molten resin, and the stored molten resin reaches a predetermined injection amount. Then, the solenoid SOL5 of the electromagnetic switching valve 21 is turned on and switched to the G position. As a result, the pressure oil that has left the pump 11 and has the maximum pressure required for each process by the pressure control valve 13 has a large maximum allowable flow rate through the pipe line 14, for example, 200 l / min of the electromagnetic proportional flow control valve 15 To a stable control range of 10 depending on the shape material of the molded product.
The flow rate is adjusted to 0% to 5%, that is, in the range of 200 to 10 l / min.
It is sent to the cartridge check valve 27 through 5.
Since the r port of the cartridge check valve 27 is communicated with the drain circuit, the cartridge check valve 27 passes between the m port and the n port
A bypass passage for passing to the rear chamber of the injection cylinder 1 through 31 is opened, and the screw 5 is pushed out at a speed corresponding to the flow rate of the sent pressure oil, for example, a speed range of 100 to 5 mm / sec. Then, a back flooring (not shown) at the tip of the screw 5 closes to serve as an injection plunger, and the molten resin stored in the tip of the heating cylinder is injected under high pressure from a tip nozzle into a die (not shown).

Next, when the low speed range is set, the solenoid SOL2 of the solenoid operated directional control valve 17 is turned on and switched to the B position, and the solenoid SOL1 of the solenoid operated directional control valve 18 is turned off and switched to the C position. When the solenoid SOL5 of the electromagnetic switching valve 21 is turned on and switched to the G position to start the injection process, the electromagnetic switching valve 17 opens between the ports a and b and the original pressure is applied to the port r of the cartridge check valve 27. Therefore, the m port and the n port are closed, and the bypass lines 25 and 31 of the flow rate control double valve 24 are closed. Therefore, the pressure oil sent from the i-port of the electromagnetic switching valve 21 passes through the pipe line 23 and one throttle 24 of the double valve.
At the same time, it is sent to the cartridge check valve 26 through the conduit 25 and the k port of the cartridge check valve 26. Since the Q port of the cartridge check valve 26 is connected to the drain circuit, it passes between the k and l ports with almost no resistance, and the pressure oil flows through the conduit 3
It is sent to the other diaphragm 24b through 2. Flow control double valve
For 24, the maximum allowable flow rate of one throttle is, for example, 20 l / min, and in this case it is 40 l / min because it is a parallel double-pass circuit, which is a stable control range of 100 to 5 %, That is, the flow rate can be adjusted stably in the range of 40 to 2 l / min. Therefore, if the electromagnetic control valve 15 and the current control double valve 24 are controlled by the same amplifier (controller), the current control valve 15 will always have a flow rate of 5 times, so it will be completely ignored and the double pass of the double valve 24 will be ignored. The pressure oil whose flow rate is adjusted by the circuit is sent to the rear chamber of the injection cylinder 1 through the conduits 28 and 29, and the screw 5 is pushed out in the speed range of 20 to 1 mm / sec.

Next, when switching to the extremely low speed range, the solenoid switching valves 17, 18
The solenoids SOL1 and 2 of are turned on to switch between B position and D position. As a result, the bypass pipes 25 and 31 are closed, the d port and the c port of the switching valve 18 are communicated with each other, and the source pressure is applied to the Q port of the cartridge check valve 26, whereby the k and l ports are closed. Conduit 25,
The pressure oil sent from the i port of the electromagnetic switching valve 21 when the valve 32 is closed passes through the pipe 23 and one throttle 24 of the flow control double valve 24.
At a, the current is adjusted within the stable control range of 20 to 1 l / min. This pressure oil is sent to the rear chamber of the injection cylinder 1 via the pipe 28, and the screw 5 is pushed out at a speed of 10 to 0.5 mm / sec.

Next, the second embodiment will be described with reference to FIG.

The second embodiment differs from the first embodiment in that the proportional current control double valve 24 is replaced with a small allowable maximum flow rate, for example.
A 20 l / min proportional flow rate control valve 41 is used, and further, the cartridge check valve 26, the electromagnetic switching valve 18, and the pipe lines 29, 32, and 35 around them are omitted. The same reference numerals are given and the description is omitted.

Further, the operation of the second embodiment is the same as that of the operation of the first embodiment in the high speed range and the extremely low speed range (single pass), and the description thereof will be omitted.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects.

According to a first aspect of the present invention, a flow valve having a large capacity and a flow control valve having two small capacities are arranged in series, and a first opening / closing valve member opens and closes a bypass circuit of the flow control valve having two throttles. In addition, since the two throttles of the flow control valve are switched to the single-pass circuit and the double-pass circuit by the second opening / closing valve member, the defense range of each range is overlapped and expanded to an extremely low speed. By selecting a range with higher stability, a stable injection speed can be obtained from high speed to extremely low speed.

In a second aspect, a first flow rate control valve having a large capacity and a second flow rate control valve having a small capacity are arranged in series, and an on-off valve member for opening and closing a bypass passage of the second flow rate control valve is provided, Since a simple circuit is used only by switching between two ranges, a high speed side and an extremely low speed side, it is possible to inexpensively provide a machine that can handle a wide range of injection speeds with one unit.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram including a structural diagram around a partial injection cylinder of the first embodiment, FIG. 2 is a diagram showing a relationship between flow rate and injection speed by range switching of the first embodiment, and FIG. FIG. 6 is a hydraulic circuit diagram including a structural diagram around a partial injection cylinder of a second embodiment. 1 …… Injection cylinder, 5 …… Screw 15,41 …… Electromagnetic proportional flow control valve 17,18 …… Electromagnetic switching valve 24 …… Electromagnetic proportional flow control double valve 26,27 …… Cartridge check valve

Claims (2)

[Claims] 1. In a hydraulic mechanism for injection of an in-line screw type injection molding machine, a flow rate control valve for simultaneously controlling two throttles is arranged in a circuit for supplying pressure oil to a screw pushing side airtight chamber of an injection cylinder. A bypass passage for the flow control valve is provided, a first opening / closing valve member for opening the bypass passage at a high injection speed is provided, and a double pass circuit for connecting two throttles of the flow control valve in parallel is provided. A second on-off valve member that opens the throttle circuit when the injection speed is low is provided. When the injection speed is high, the regulated source pressure is directly supplied to the injection cylinder through the bypass passage, and when the injection speed is low, the double-pass circuit and the flow control valve Pressure oil whose flow rate is adjusted by two throttles is supplied to the injection cylinder, and pressure oil whose flow rate is adjusted only by the other throttle circuit of the flow control valve is supplied to the injection cylinder at extremely low speed. Injection molding machine, characterized in that the switchable into three ranges. 2. In a hydraulic mechanism for injection of an in-line screw type injection molding machine, a first flow rate control valve having a large capacity and a second flow rate control having a small capacity are provided in a circuit for supplying pressure oil to a screw pushing side airtight chamber of an injection cylinder. Valve is provided in series, a bypass passage for the second flow control valve is provided, and an opening / closing valve member for opening the bypass passage is provided. When the injection speed is high, the pressure adjusted by the first flow control valve is used. Oil is directly supplied to the injection cylinder through the bypass passage, and when the speed is extremely low,
An injection molding machine characterized in that it can be switched between two ranges for supplying pressure oil whose flow rate is adjusted by a second flow rate control valve to an injection cylinder.