JP2000313038A - Injection molding apparatus and injection molding method - Google Patents

Abstract

(57) [Problem] To provide a vertical injection molding apparatus and an injection molding method which do not cause deterioration in product quality. SOLUTION: An oil discharge side of a hydraulic motor 5 is connected to a chamber 4B below a piston 41 in a hydraulic cylinder 4 by a pipe 53, and pressurization of oil after applying a driving force to the hydraulic motor 5 is performed. When an upward force is supplied to the piston 41 in the hydraulic cylinder 4 by using the above, the volume of the silicone resin for one discharge is measured in the measuring chamber 81, and the piston 41 is attached to the screw 8 and the shaft 51 of the hydraulic motor 5. The vertical force, such as the weight of the screw 8, was offset by the upward force so that the silicone resin in the measuring chamber was not pressurized during measurement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding apparatus, and more particularly, to a method of discharging a material vertically downward.
The present invention relates to a so-called vertical injection molding apparatus and its injection molding method.

[0002]

2. Description of the Related Art Conventionally, when injection molding is performed using a thermosetting liquid silicone resin, an injection molding apparatus for a more general resin other than a silicone resin such as a thermoplastic resin is often used as it is. . FIG. 2 shows a schematic configuration of a typical vertical injection molding apparatus 100.

In this injection molding apparatus 100, a pedestal 101
Two pillars 102 and 10 extending upward in a direction substantially parallel to the vertical direction
3, a cylinder holder 104 is provided over these columns 102, 103, and a hydraulic motor 120 for rotating the screw 110 is provided above the cylinder holder 104. The cylinder holder 104 is provided with a discharge cylinder 130 that contains a silicone resin and mixes and ejects the mixture. Discharge cylinder 1
A screw 110 is accommodated in the discharge cylinder 130, and the screw 110 rotates in the discharge cylinder 130 to mix a silicone resin containing a liquid silicone resin composed of the liquid A and the liquid B as a main component.
As the “0” moves substantially vertically downward, the mixed composition is discharged toward a mold (not shown) from the nozzle 134 disposed at the tip of the discharge cylinder 130.

In this injection molding apparatus 100, a support 10
A hydraulic cylinder 140 is provided at the uppermost part of the two cylinders 103. The hydraulic cylinder 140 is a piston 141 that can be moved up and down.
The piston 141 moves up and down by hydraulic pressure supplied from an externally provided hydraulic pump P to raise and lower the hydraulic motor 120 and the screw 110 thereunder. The hydraulic motor 120 located below the hydraulic cylinder 140 generates a rotational driving force by the hydraulic pressure supplied from the hydraulic pump P, and rotates the screw 110 attached to the shaft 121 of the hydraulic motor 120 about a substantially vertical axis. Let it.

[0005] In order to perform injection by the injection molding apparatus 100, first, the raw material supply pump 150 is operated and the liquid resin A is injected.
Then, the liquid resin B is introduced from an inlet 131 provided at the base of the discharge cylinder 130. At the same time, the hydraulic motor 12
0 is operated to rotate the screw 110. The silicone resin injected into the discharge cylinder 130 is conveyed vertically downward while being mixed by the rotation of the screw 110, and is eventually stored in a measuring chamber 133 formed between the inner end of the discharge cylinder 130 and the end of the screw 110. . Further, charging of silicone resin and screw 11
When the rotation of 0 is continued, the volume of the silicone resin accumulated in the measuring chamber 133 increases, and the screw 110 is pushed upward in the figure. When the pushing amount reaches a certain value, the sensor S
Is operated, it is recognized that a predetermined volume of material has accumulated in the measuring chamber 133. Then, the hydraulic cylinder 140 is operated to press the screw 110 downward, and discharge the material from the nozzle 134. That is, in this injection molding apparatus 100,
The amount of silicone resin supplied into the measuring chamber 133, that is, the amount of silicone resin for one discharge is measured by the screw 110.
This is done through a retreat. If the amount of the silicone resin for one discharge changes, the quality of the molded product obtained by curing after the discharge will vary, and the quality of the product will be degraded. Therefore, this measurement must be performed accurately.

[0006]

In the injection molding apparatus 100 shown in FIG. 2, the hydraulic motor 120 and the piston 141 of the hydraulic cylinder 140 are mounted on the screw 110.
Is disposed right above, so that the screw 110 is considerably heavily weighted downward during operation of the apparatus. Therefore, unless the pressure applied when the raw material is supplied by the raw material supply pump 150 is increased to be equal to or more than these weights, the measuring chamber 1
33 Cannot feed material. Also, the discharge cylinder 130
The pressure of the silicone resin inside and in the measuring chamber 133 becomes high. In order to maintain a constant volume of the silicone resin for one discharge stored in the measuring chamber 133 under such a high pressure, it is assumed that the material itself has a property that the fluctuation of the volume due to the pressure is zero or equal thereto. Become. That point,
The injection molding apparatus 100 is designed for a thermoplastic resin, and there is no practical problem because these thermoplastic resins hardly change in volume due to pressure.

However, a problem arises when the injection molding apparatus 100 is used for molding a silicone resin. This is because the silicone resin has the property of changing its volume depending on the pressure. For example, when a pressure of 100 kg acts, there is an example in which the volume shrinks by about 3% with respect to the volume when the pressure is zero.

Therefore, when the injection molding apparatus 100 as shown in FIG. 2 is used as it is for molding a silicone resin, there is a problem that the injection amount at the time of molding is not stable and the quality of a molded product is deteriorated. .

The present invention has been made to solve the above-mentioned conventional problems. That is, an object of the present invention is to provide a vertical injection molding apparatus and an injection molding method that do not cause deterioration in the quality of a molded product.

[0010]

According to the present invention, there is provided an injection molding apparatus comprising: a discharge cylinder accommodating a screw having a substantially vertical rotating shaft so as to be rotatable and vertically movable; a hydraulic motor for rotating the screw; A hydraulic cylinder for raising and lowering, a hydraulic pump for supplying hydraulic pressure for driving to the hydraulic motor, and load reducing means for reducing a downward load acting on the screw using hydraulic pressure supplied from the hydraulic pump. I do.

In the above-mentioned injection molding apparatus, the load reducing means may be a pipe connecting the oil discharge side of the hydraulic motor to a lower chamber of the piston of the hydraulic cylinder. The pipe as the load reducing means may be a pipe that directly connects the lower chamber of the piston of the hydraulic cylinder to the hydraulic pump.

[0012] Further, the pipe as the load reducing means,
A pressure control valve and a check valve may be provided.

Further, as a material to be mixed and injected in the discharge cylinder, there is a liquid silicone resin composition.

Further, as an injection molding method using the above apparatus, a discharge cylinder accommodating a screw having a substantially vertical rotating shaft so as to be rotatable and vertically movable, a hydraulic motor for rotating the screw, and a mechanism for vertically moving the screw A method for performing injection molding using an injection molding apparatus including a hydraulic cylinder and a hydraulic pump that supplies a hydraulic pressure for driving to the hydraulic motor, wherein the hydraulic pressure supplied from the hydraulic pump is set below a piston of the hydraulic cylinder. It is characterized in that the downward load acting on the screw is reduced by supplying the screw to the side room.

In the injection molding apparatus and method according to the present invention, the hydraulic cylinder is given a force for pushing up the piston by using the exhaust pressure of the oil after driving the hydraulic motor.
The downward load on the screw can be reduced, and the material can be accurately measured.
As a result, the amount of the silicone resin discharged in one discharge becomes uniform, and the quality of the molded product is stabilized.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An injection molding apparatus according to an embodiment of the present invention will be described below. FIG. 1 is a diagram showing a schematic configuration of an injection molding apparatus 10 according to the present embodiment.

As shown in FIG. 1, in an injection molding apparatus 10 according to this embodiment, two columns 2 and 3 extending substantially parallel to a vertical direction are arranged on a base 1. A hydraulic cylinder 4, a hydraulic motor 5, and a cylinder holder 6 are arranged in this order from the top over the columns 2, 3.

The cylinder holder 6 is provided with a discharge cylinder 7 which contains a silicone resin and mixes and ejects the mixture. An input port 72 for inputting the silicone resin is provided above the discharge cylinder 7.
2 is connected to a pipe 9 for supplying a raw material.
An on-off valve 91 is provided in the middle of the pipe 9,
The other end of 2 is divided into two branches of a pipe 73 and a pipe 74, and the ends of the pipes 73 and 74 are connected to raw material supply pumps 11 and 12, respectively. In the raw material supply pumps 11 and 12, for example, the main components A and B of liquid silicone resin are respectively provided.
Are accommodated, and the pistons 11a, 12
When “a” is pressed, the main agent A and the main agent B are extruded at a fixed ratio, and are injected into the discharge cylinder 7 through the pipes 73, 74 and the pipe 72.

A screw 8 is accommodated in the discharge cylinder 7, and the screw 8 is rotated in the discharge cylinder 7 to mix a silicone resin mainly composed of a liquid silicone resin composed of a main ingredient A and a main ingredient B. Then, the inside of the discharge cylinder 7 is sent downward. In this injection molding apparatus, a hydraulic cylinder 4 is disposed at the top of the columns 2 and 3.

The hydraulic cylinder 4 has a piston 41 which can be moved up and down.
The piston 41 moves up and down by a hydraulic pressure supplied from a hydraulic pump P provided outside to raise and lower the hydraulic motor 5 and the screw 8 thereunder.

That is, an oil introduction pipe 43 and an oil discharge pipe 44 are connected to the upper portion of the hydraulic cylinder 4 so that oil can be taken in and out of the chamber 4A above the piston 41 in the hydraulic cylinder 4. It has become.
The pipe 43 is connected to the hydraulic pump P
The oil pressurized in the above flows into the room 4A. Piping 44
Is guided to the oil discharge tank 46 side, circulated by a circulation mechanism (not shown), and provided for reuse.

In the injection molding apparatus of this embodiment, a pipe 53 and a pipe 54 are also connected to a lower portion of the hydraulic cylinder 4, and oil is taken in and out of the chamber 4 B below the piston 41 in the hydraulic cylinder 4 and is put into the piston 41. Hydraulic pressure is applied. That is, the pipe 53 is connected to the hydraulic motor 5 described later.
The oil after driving the hydraulic motor 5 is supplied into the lower chamber 4B by exhaust pressure, and the pipe 54 discharges the oil from the lower chamber 4B. An on-off valve 58 is provided in the pipe 54, and the oil pressure is controlled by opening and closing the on-off valve 58.

The hydraulic motor 5 located below the hydraulic cylinder 4 gives a rotary motion by the hydraulic pressure supplied from the hydraulic pump P, and rotates the screw 8 attached to the shaft 51 of the hydraulic motor 5 around a substantially vertical axis. Rotate. That is, the pipe 52 and the pipe 53 are connected to the hydraulic motor 5,
Is connected to the hydraulic pump P and introduces oil pressurized by the hydraulic pump into the hydraulic motor 5. In the hydraulic motor 5, a mechanism for rotating the rotating shaft 51 by a mechanism (not shown) for generating a rotational driving force using hydraulic pressure is provided, and the oil supplied from the pipe 52 is rotated by the rotating shaft. 51 rotation.

On the other hand, the pipe 53 is connected to the oil discharge side of the hydraulic motor 5 to discharge the oil used to generate the rotational driving force in the hydraulic motor 5, and to discharge the oil as described above. 4 to supply oil.

A check valve 55, a pressure regulating valve 56 and a pressure gauge 57 are provided in the middle of the pipe 53.

The check valve 55 is provided with a hydraulic cylinder 4
The pressure control valve 56 is a valve for preventing the back flow from the hydraulic motor 5 side to the hydraulic motor 5 side.
This is a valve for adjusting the hydraulic pressure applied to the lower chamber 4B of the first unit 1. The valve is adjusted to an appropriate pressure while checking the pressure value of the pressure gauge 57 thereabove.

Here, the value of the hydraulic pressure applied to the lower chamber 4B is a value obtained by adding the weight from the piston 41 to the screw 8, or when the so-called silicone resin is measured in the measuring chamber 81 on the distal end side of the piston 8. The hydraulic pressure is such that the downward load such as the weight of the screw 8 and the weight of the shaft 5 and the piston 41 of the hydraulic motor 5 can be offset to make this downward load zero.

The value of the oil pressure is a design matter, and a value calculated from the weight of each part or actually measured is used. The pressure control valve 56 is adjusted while checking the oil pressure in the pipe 53 with the pressure gauge 57 so as to have this value.

Further, a safety valve or a bypass passage (both not shown) for automatically releasing a part of the oil to reduce the pressure when a hydraulic pressure of a certain value or more is applied to the pipe 53.
May be further provided.

Next, the operation for performing injection molding of silicone resin using the injection molding apparatus of the present embodiment will be described.

When the injection molding apparatus 10 is started in a state where the main ingredients A and B of the liquid silicone resin are filled in the raw material supply pumps 11 and 12, respectively, the driving apparatus 13 starts operating and presses the pistons 11a and 12a. , Main ingredients A and B flow through pipes 73, 74 and 9 and
From the discharge cylinder 7 as silicone resin.

On the other hand, the valve 59 is opened simultaneously with the activation of the apparatus,
The operation of the hydraulic pump P is started to rotate the hydraulic motor 5. When the screw 8 is rotated by the rotation of the hydraulic motor 5, the silicone resin pressure-fed from the raw material pumps 11 and 12 and fed from the charging port 72 is conveyed downward in the discharge cylinder 7 by rotation of the blades of the screw 8, and finally, Is stored in the measuring chamber 81 between the tip inside the discharge cylinder 7 and the tip of the screw 8.

On the other hand, the oil used to rotate the hydraulic motor 5 passes through the pipe 53 and is supplied to the lower chamber 4 B of the piston 41 in the hydraulic cylinder 4. At this time,
When the valve 58 and the valve 46 are closed and the valve 45 is opened, the oil flows into the chamber 4B and the outlet is closed, so that an upward force acts on the piston 41. On the other hand, the oil is not supplied from the hydraulic pump P into the room 4A because the valve 46 is closed, and the oil in the room 4A can flow out into the pipe 44 because the valve 45 is open. Therefore, when oil is supplied into the room 4B, the piston 41 rises, and the hydraulic motor 5
Is applied in the direction of lifting the shaft 51 and the screw 8 disposed thereunder. At this time, the hydraulic pressure applied to the pipe 53 has been adjusted to an appropriate value in advance, and the piston 4
The upward force acting on the screw 1 is adjusted so as to have a strength obtained by adding the screw 8 and the load applied to the screw 8. Therefore, while the hydraulic motor 5 is operating, the downward force applied to the screw 8 is offset by the upward force applied to the piston 41, and becomes almost zero.

When the rotation of the hydraulic motor 5 and the charging of the silicone resin are continued in this state, the amount of the silicone resin stored in the measuring chamber 81 increases with the passage of time, and the volume of the silicone resin stored in the measuring chamber 81 increases. Increase. This increase in volume becomes a force for pushing up the screw 8, and the screw 8 rises. As the screw 8 rises, the hydraulic motor 5 also rises, and when the amount of rise of the hydraulic motor 5 reaches a constant value, the sensor S is activated, the hydraulic motor 5 rises a predetermined amount, and a predetermined volume The control device (not shown) recognizes that the silicone resin, specifically, the volume of the silicone resin for one discharge is stored.

When the sensor S is activated, the valves 59, 91, 45
Is closed to stop the rotation of the hydraulic motor 5 and the charging of the silicone resin, and the valves 46 and 58 are opened. Then, the rotation of the screw 8 is stopped, and the upper chamber 4A of the hydraulic cylinder 4 is stopped.
The oil from the hydraulic pump P flows into the inside. Since oil flows into the upper chamber 4A and oil flows out from the lower chamber 4B to the pipe 54, a downward force acts on the piston 41, and the screw 8 passes through the shaft 51 of the hydraulic motor 5. A downward force acts on. At this time, when the tip of the nozzle 71 ahead of the discharge cylinder 7 is opened, the nozzle 71
Weighing chamber 8 toward a mold (not shown)
The silicone resin stored in 1 is discharged.

As described above, in the injection molding apparatus of the present embodiment, the oil discharged from the hydraulic motor 5 is sent to the lower chamber 4B of the hydraulic cylinder 4 below the piston 41,
Using the oil pressure of the oil, an upward force acts on the screw 8 when the hydraulic motor is turned five times, that is, while the silicone resin is supplied into the measuring chamber 81 and the amount of the silicone resin for one discharge is measured. Then, the downward load applied to the screw 8 is reduced to zero. Therefore, since the force for compressing the silicone resin in the measuring chamber 81 does not act at the time of weighing, the silicone resin does not shrink due to pressurization, and high-precision weighing becomes possible.

Further, in this injection molding apparatus, the oil discharge side of the hydraulic motor 5 and the chamber 4B below the piston 41 in the hydraulic cylinder 4 are connected by a pipe 53 or a pipe 54 or a valve 58 is added. Since it has a relatively simple structure that requires only minor modifications, it does not cause a significant increase in manufacturing cost or complicated maintenance.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the oil discharge side of the hydraulic motor and the room below the piston of the hydraulic cylinder are connected by piping, but the hydraulic pump and the room below the piston of the hydraulic cylinder are directly connected. You may.

[0039]

According to the injection molding apparatus and method of the present invention,
Since the force for pushing up the piston is given to the hydraulic cylinder by using the exhaust pressure of the hydraulic motor, the load applied to the screw can be reduced, whereby the silicone resin can be accurately measured. As a result, the amount of the silicone resin discharged in one discharge becomes uniform, and the effect of stabilizing the quality of the molded product is obtained.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view schematically showing a schematic configuration of an injection molding apparatus according to the present invention.

FIG. 2 is a vertical sectional view schematically showing a schematic configuration of a conventional injection molding apparatus.

[Explanation of symbols]

 8: Screw, 7: Discharge cylinder, 5: Hydraulic motor, 4: Hydraulic cylinder, P: Hydraulic pump, 41: Piston, 4B: Lower chamber.

Claims (5)

[Claims] 1. A discharge cylinder accommodating a screw having a substantially vertical rotating shaft so as to be rotatable and vertically movable, a hydraulic motor for rotating the screw, a hydraulic cylinder for vertically moving the screw, and a drive for driving the hydraulic motor. An injection molding apparatus, comprising: a hydraulic pump that supplies the hydraulic pressure of claim 1; and a load reducing unit that reduces a downward load acting on the screw by using a hydraulic pressure supplied from the hydraulic pump. 2. The injection molding apparatus according to claim 1, wherein
The injection molding apparatus, wherein the load reducing means is a pipe connecting an oil discharge side of the hydraulic motor and a lower chamber of a piston of the hydraulic cylinder. 3. The injection molding apparatus according to claim 2, wherein:
An injection molding apparatus, wherein the pipe includes a pressure control valve and a check valve. 4. The injection molding apparatus according to claim 1, wherein the material mixed and injected in the discharge cylinder is a liquid silicone resin composition. apparatus. 5. A discharge cylinder accommodating a screw having a substantially vertical rotation axis so as to be rotatable and vertically movable, a hydraulic motor for rotating the screw, a hydraulic cylinder for vertically moving the screw, and a drive for driving the hydraulic motor. A hydraulic pump that supplies a hydraulic pressure, and a method for injection molding using an injection molding apparatus having
An injection molding method, wherein the hydraulic pressure supplied from the hydraulic pump is supplied to a lower chamber of a piston of the hydraulic cylinder to reduce a downward load acting on the screw.