JPH08127053A - Injection device of injection molding machine - Google Patents

Abstract

PURPOSE: To provide the injection device of an injection molding machine at relatively simple in structure and capable of being produced at low cost capable of easily mounting an injection speed altering device and a weighing pressure high precise setting device on a standard injection molding machine during operation. CONSTITUTION: A pressure oil quantity/oil pressure conversion cylinder 50 internally provided with a piston 50c having different pressure receiving surfaces S1, S2 on both sides thereof (in other words, consisting of oil chambers 50a, 50b having large and small pressure receiving areas) and an operation pressure oil quantity/oil pressure conversion device 56 containing oil passage changeover solenoid valves 52, 54 are provided in an oil pressure circuit 14. The oil quantity/oil pressure conversion cylinder 50 is adapted not only as a speed increasing cylinder (in this case, pressure is reduced) but also as a pressure raising cylinder (in this case, speed is decelerated) by changing over oil passages and pref. formed from one single stage cylinder and, if necessary, the whole of this cylinder 50 or the piston 50c thereof can be constituted so as to be replaced with one having a separate speed increasing rate (pressure raising ratio).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synthetic resin injection molding machine, and more particularly to improvement of an injection device of the injection molding machine.

[0002]

2. Description of the Related Art Generally, an injection device of an injection molding machine is shown in FIG.
As shown in FIG. 3, the hydraulic circuit 14 includes a pressure oil switching solenoid valve 10 and a pressure adjusting valve (relief valve) 12 that works in conjunction with the pressure oil switching electromagnetic valve 10. Then, during the injection process, by exciting one solenoid 10a of the pressure oil switching electromagnetic valve 10, the hydraulic pump 1 is driven through the electromagnetic valve 10 (P → B).
The pressure oil discharged from 6 is used as the working pressure oil and is supplied to one oil chamber 22a of the injection cylinder 22 of the injection molding machine 20,
Thereby, the screw 20a is advanced to the left in the drawing via the piston 22c, and the molten resin in the heating cylinder 20b is injected and filled into the cavity 28a of the mold 28. At this time, the pressure oil in the oil chamber 22b is
It passes through the solenoid valve 10 (A → T) and is discharged to the tank 30.

On the other hand, during the metering and kneading process, the screw 20a is rotated by a motor (not shown) to melt the raw material resin 24 in the hopper 20c at its tip portion 26, and both of the solenoid valves 10 are turned on. Since the solenoid is de-energized, the pressure of the return oil from the oil chamber 22a is
Through the relief pressure of the pressure regulating valve 12, it is set so as to have a predetermined measuring pressure. The oil to the oil chamber 22b is supplied from the tank 30 through the electromagnetic valve 10 (T → A).

FIG. 5 shows a modified example (double cylinder type) of the injection cylinder 22.
The oil chambers 22a and 22b of 2B are connected by a common piston 22c.

However, in such an injection device,
In order to improve the quality of molded products, simplify the structure of the molding machine, and reduce the operating cost, the screw resistance in the injection pressure holding process is particularly high in the injection pressure holding process compared to the latter pressure holding process. Due to the small
It has been proposed to change the injection speed, and in the metering and kneading step, it has been proposed to set the metering pressure with high accuracy, particularly for quality improvement.

That is, as shown in FIG. 2 (corresponding to FIG. 4 described above), the injection speed changing device generally applies the original injection cylinder 22 (FIG. 4) to the injection cylinder portion 34 with oil. The hydraulic cylinder 14 is formed as a composite cylinder 32 provided with an amount / hydraulic pressure conversion cylinder portion 36, and the hydraulic circuit 14 (FIG. 4) is provided with operating pressure oil in each oil chamber 38 of the composite cylinder 32.
The circuit switching device 40 that selectively supplies a to a, 38b, and 38c is provided. Therefore, according to such a configuration, the pressure receiving area ratio of the oil chambers 38b and 38c is set to s1.
When / s2 = n, it is clear that the high-speed injection speed of the screw 20a is n times that in the normal case (pump discharge flow rate), while the injection pressure is 1 / n times the reverse. In this case, as shown by the chain line, if the oil chamber of the oil amount / hydraulic pressure conversion cylinder 36 is formed in multiple stages, the injection speed (and injection pressure) can also be changed in multiple stages.

FIG. 3 (corresponding to FIG. 4 described above)
Shows a modified example (double cylinder type) of the composite cylinder 32, in which both cylinder portions 32A and 32B have a common piston 3
Although connected by 2C, the operation is the same. In addition, the high precision setting of the metering pressure is usually performed by the pressure adjusting valve 12
This can be achieved by attaching certain additional devices to (FIG. 4) that improve its resolution.

[0008]

However, the above-mentioned conventional injection apparatus of the injection molding machine has the following drawbacks.

That is, first, in the injection speed changing device, conventionally, the oil amount / hydraulic pressure converting cylinder portion 36 is conventionally used.
(FIG. 2), but generally as described above, the injection molding machine 20
Since it is attached to the injection cylinder portion 34 of the injection molding machine 20 and is formed as the composite cylinder 32, first of all, the injection molding machine 20
There was a basic difficulty in having to modify the body of the. This difficulty (remodeling work) requires a large amount of cost and construction period (pause period) due to the large number of replacement parts, and this is required every time the injection speed is changed. Incidentally, these difficulties are remarkable in the case of the double cylinder type injection speed changing device (FIG. 3). Secondly, in the case of the single cylinder type injection speed changing device (FIG. 2), the entire length of the injection molding machine 20 becomes long (particularly in the case of multistage speed changing), while the double cylinder type In the case of the injection speed changing device (FIG. 3), there are other problems such as inconvenience of operation. Further, as to the high-accuracy setting of the metering pressure, conventionally, a specific additional device is attached as described above, which causes a problem that the manufacturing cost is increased.

Therefore, an object of the present invention is to operate and / or
Alternatively, the injection speed changing device and the metering pressure high precision setting device can be easily attached to the standard injection molding machine, and the injection molding machine can be manufactured at a relatively low cost with a relatively simple structure. It is to provide an injection device.

[0011]

In order to achieve the above object, an injection device of an injection molding machine according to the present invention has a hydraulic circuit including a pressure oil switching solenoid valve and a pressure adjusting valve interlocked therewith. During the injection process, the pressure oil discharged from the hydraulic pump is supplied as working pressure oil to the injection cylinder through the pressure oil switching solenoid valve, and during the metering and kneading process, the return oil from the injection cylinder is returned through the pressure adjustment valve. In an injection device of an injection molding machine that sets a pressure to a predetermined measurement pressure, in the hydraulic circuit, the pressure oil amount / the pressure oil amount on both sides of the piston are different from each other.
An operating pressure oil / oil amount / hydraulic pressure converting device including a hydraulic pressure converting cylinder and an oil passage switching solenoid valve is provided to increase the operating pressure oil supply amount to the injection cylinder during the injection process from the pump discharge flow rate, and to increase the pressure during the measuring process. It is characterized in that the metering pressure with respect to the regulating valve is configured to be amplified and raised from the actual pressure.

In this case, the conversion cylinder of the hydraulic oil / hydraulic pressure conversion device is formed of one or a plurality of single-stage cylinders, and the entire cylinders and / or their pistons are configured to be interchangeable. You can

[0013]

According to the present invention, by incorporating an oil pressure / oil pressure oil pressure / oil pressure oil pressure / hydraulic pressure conversion device including an oil amount / hydraulic pressure conversion cylinder and an oil passage switching solenoid valve in the injection device hydraulic circuit of the injection molding machine, the injection speed can be improved. Changes and metering pressure high precision settings can be easily achieved. Moreover, the oil amount / hydraulic pressure converting device can be manufactured at a low cost with a simple structure by forming the oil amount / hydraulic pressure converting cylinder in a single-stage and replaceable manner. In other words, the injection device of the injection molding machine of the present invention can easily mount the injection speed changing device and the metering pressure high precision setting device on the operating and / or standard injection molding machine. It is possible to provide these configurations relatively easily and to provide them at low cost.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of an injection device of an injection molding machine according to the present invention will be described in detail below with reference to the accompanying drawings. For convenience of explanation, the same components as those of the conventional structure shown in FIGS. 2 to 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

First, the basic construction of the injection device of the injection molding machine of the present invention is the same as that of the conventional one (FIG. 4). Therefore, although overlapping description will be made simply, in FIG. 1 (in this embodiment, the injection cylinder is formed as a double cylinder type), the injection device is the pressure oil switching solenoid valve 1.
0 and a hydraulic circuit 14 including a pressure adjusting valve 12 that works together therewith, and the pressure oil switching solenoid valve 10 is used during the injection pressure maintaining process.
The pressure oil discharged from the hydraulic pump 16 is supplied as working pressure oil to the injection cylinder 22 of the injection molding machine 20 via the pressure control valve 12, and the pressure of the return oil from the injection cylinder 22 is controlled via the pressure adjusting valve 12 during the metering and kneading process. Are configured to be set to predetermined metering pressures. Reference numerals 20a and 20b in the drawing denote the screw and the heating cylinder of the injection molding machine 20, and 22a and 22b.
Reference numerals 22c and 22c denote the first and second oil chambers and pistons of the injection cylinder 22, and 28 and 30 denote molds and tanks, respectively.

However, according to the present invention, in the above-described structure, the pressure receiving areas S1 and S2 on both sides of the piston 50c are different in the hydraulic circuit 14 (in other words, the oil chambers 50a and 50b having large and small pressure receiving areas are formed). An operating pressure oil / oil amount / hydraulic pressure converting device 56 including a pressure oil / oil amount / hydraulic pressure conversion cylinder 50 and oil passage switching solenoid valves 52, 54 is provided. The oil amount / hydraulic pressure conversion cylinder 50 will be further described here.
It is applied both as a speed-up cylinder (where the pressure is reduced in this case) and as a pressure-up cylinder (where the speed is reduced in this case).

In the present invention, a general injection device has a speed-up rate (including a step-up rate) N in the present invention.
= S1 / S2 can be applied in a relatively narrow range of 1.4 to 2 times, the cylinder 50 is usually formed of one single-stage cylinder as shown in the drawing, and if necessary, this Entire cylinder 50 or its piston 50c
Is configured to be exchanged for another speed increasing rate (pressurizing rate). Note that reference numerals 58a and 58b in the drawing respectively denote replacement joints.

Therefore, according to the present invention, as will be sequentially described below, the working pressure oil supply amount to the injection cylinder 22 in the injection process (injection filling process) is increased more than the pump discharge flow rate, and in the metering process. The measured pressure for the pressure control valve 12 can be increased and increased from the actual pressure.

That is, in the injection process, first in the injection filling process of the preceding stage, one of the solenoid 10a of the pressure oil switching electromagnetic valve 10 and the oil passage switching electromagnetic valve 54 are excited to discharge the pressure oil discharged from the hydraulic pump 16. Is supplied to the oil chamber 50b of the small pressure receiving area of the oil amount / hydraulic pressure conversion cylinder 50 through both solenoid valves 10 (P → B) and 54 (P → B), and is discharged from the oil chamber 50a of the large pressure receiving area. The oil passage switching solenoid valve 52 using the pressure oil increased by N times as the working pressure oil.
One of the oil chambers 22 of the injection cylinder 22 via (P → A)
supply to a. Therefore, the injection speed of the screw 20a can be increased N times.

Next, during the pressure-holding process in the latter stage, the solenoid valve 5
4 is released and the solenoid valve 52 is newly excited to discharge the pressure oil discharged from the hydraulic pump 16 to both solenoid valves 10.
Supply directly to the oil chamber 22a (without passing through the conversion cylinder 50) via (P → B) and 54 (P → A). That is, the holding pressure of the screw 20a can be returned (decelerated) to a regular value. During this period, the pressure oil from the other oil chamber 22b of the injection cylinder 22 is discharged to the tank 30 via the electromagnetic valve 10 (A → T) as described above.

On the other hand, during the measuring and kneading step (while the screw 20a is rotated by the motor as described above,
Only the solenoid valve 54 is excited in the hydraulic circuit 14 to melt the raw material resin and at the same time retreat by itself, and the return oil from the oil chamber 22a of the injection cylinder (the pressure of the return oil is the same as that described above). Is set into the oil chamber 50a of one of the large pressure receiving areas of the conversion cylinder 50 via the solenoid valve 52 (A → P), so that the pressure regulating valve 12 has the other small pressure. The pressure oil pressure obtained by increasing the measured pressure N times from the oil chamber 50b of the pressure receiving area is the solenoid valve 54 (B →
Loaded via P). That is, the pressure control valve 12
Since the resolution is improved by this pressure increase, it is possible to set the metering pressure with high accuracy. Incidentally, the pressure control valve 12
In this case, the drain port is connected to the tank port of the solenoid valve 10 and operates as a relief valve to release the return oil to the tank 30 after setting the increased pressure and the measured pressure. Further, this return oil causes the piston 50c to return to the reference position before the injection process when it flows into the oil chamber 50a, but when this return is insufficient, each solenoid valve 10 (10
b), 52, 54 are excited to supply the pressure oil from the pump 16 to the oil chamber 50a, and the pressure oil in the oil chamber 50b is returned to the tank 30, so that the above-mentioned return can be easily completed. .

As described above, according to the present invention, the injection speed is changed by incorporating the working pressure oil / oil amount / hydraulic pressure converting device including the oil amount / hydraulic pressure converting cylinder into the hydraulic circuit of the injection device of the injection molding machine. Both high precision setting of metering pressure can be easily achieved. Moreover, by forming the oil amount / hydraulic pressure conversion cylinder in a single stage and replaceable, the device can be configured easily and at low cost. Therefore, the injection device of the injection molding machine of the present invention can easily mount the injection speed changing device and the metering pressure high precision setting device to the operating and / or standard injection molding machine and is simple. It has the advantage that it can be manufactured at low cost with a simple structure.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and many design changes can be made without departing from the spirit of the present invention. For example, the hydraulic circuit of the injection device can be additionally equipped with modified or modified circuit components as needed.

[0024]

As described above, the injection device of the injection molding machine according to the present invention has the hydraulic circuit including the pressure oil switching solenoid valve and the pressure adjusting valve interlocked therewith, and the pressure oil is used during the injection process. The pressure oil discharged from the hydraulic pump is supplied to the injection cylinder as working pressure oil via the switching solenoid valve, and the return oil pressure from the injection cylinder is adjusted to a predetermined metering pressure via the pressure adjusting valve during the metering and kneading process. In an injection device of an injection molding machine to be set, an operating pressure oil / oil amount / hydraulic pressure converting device including a pressure oil / oil amount / hydraulic pressure converting cylinder and an oil passage switching solenoid valve having different pressure receiving areas on both sides of a piston is provided in the hydraulic circuit. A configuration in which the working pressure oil supply amount to the injection cylinder during the injection process is increased from the pump discharge flow rate and the measurement pressure for the pressure adjustment valve during the measurement process is amplified and increased from the actual pressure. By incorporating the oil pressure / oil pressure / hydraulic pressure conversion device consisting of the oil amount / hydraulic pressure conversion cylinder into the injection device hydraulic circuit of the injection molding machine, both injection speed change and metering pressure high precision setting can be performed easily. Can be achieved,
The injection speed changing device and the metering pressure high-accuracy setting device can be easily mounted on the operating and / or standard injection molding machine.

The injection device of the injection molding machine of the present invention is
Since the oil quantity / hydraulic pressure conversion cylinder can be formed in a single stage and exchangeable, it has an advantage that it can be manufactured at a low cost with a relatively simple structure.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram showing an embodiment of an injection device of an injection molding machine according to the present invention.

FIG. 2 is a sectional view showing an injection speed increasing device in an injection device of a conventional injection molding machine.

FIG. 3 is a cross-sectional view showing another configuration example of the injection speed increasing device.

FIG. 4 is a hydraulic circuit diagram showing a general injection device that does not include an injection speed increasing device of a conventional injection molding machine.

FIG. 5 is a cross-sectional view showing another configuration example of an injection device (injection cylinder).

[Explanation of symbols]

 10 Pressure Oil Switching Solenoid Valve 10a, 10b Solenoid 12 Pressure Control Valve 14 Hydraulic Circuit 16 Hydraulic Pump 20 Injection Molding Machine 20a Screw 20b Heating Cylinder 22 Injection Cylinder 22a, 22b Oil Chamber 22c Piston 26 Tip 28 Mold 30 Tank 50 Oil Quantity / Hydraulic pressure conversion cylinders 50a, 50b Oil chamber 50c Pistons 52, 54 Oil passage switching solenoid valve 56 Oil amount / Hydraulic pressure conversion device 58a, 58b Joint

Claims (2)

[Claims] 1. A hydraulic circuit including a pressure oil switching solenoid valve and a pressure adjusting valve interlocked with the pressure oil switching solenoid valve, wherein pressure oil discharged from a hydraulic pump is used as working pressure oil via the pressure oil switching solenoid valve during an injection process. In the injection device of the injection molding machine, which supplies the oil to the injection cylinder and sets the return oil pressure from the injection cylinder to a predetermined metering pressure via the pressure adjusting valve during the metering and kneading process, An operating pressure oil / oil amount / hydraulic pressure converting device including a pressure oil / oil amount / hydraulic pressure converting cylinder and an oil passage switching solenoid valve with different pressure receiving areas on both sides is provided, and the operating pressure oil supply amount to the injection cylinder during the injection process is the pump discharge flow rate. An injection apparatus of an injection molding machine, characterized in that the injection pressure is further increased and the measured pressure to the pressure control valve in the measuring step is amplified and increased from the actual pressure. 2. The working pressure oil / oil amount / hydraulic pressure converting device includes a conversion cylinder which is composed of one or a plurality of single-stage cylinders, and the whole cylinder and / or its piston can be exchanged with each other. The injection device of the injection molding machine according to 1.