JPH02142665A - Apparatus for controlling filling-up of accumulator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to filling control of a seven-accumulator when supplying hydraulic oil to an accumulator provided for high-speed injection every injection cycle in an injection circuit of a die-casting machine or the like. This is related to tli.

Conventionally, when a piston type accumulator and a gas accumulator are used in combination as an accumulator provided in an injection circuit of a die casting machine or an extrusion press, a circuit as shown in FIG. 1, for example, has been known.

In FIG. 1, l is a pump, 2 is a motor, 3 is an injection cylinder, 4 is a cut-off valve for moving the injection cylinder forward and backward, 5 is a piston-type accumulator with a slidably built-in piston 5a, 6 is a gas accumulator, 7 is a valve for high-speed injection, 8
is a switching valve installed in the circuit that supplies hydraulic oil to the lower part of the gas accumulator 6, 9 is a pressure switch, lO is a pressure gauge, l
1 is a relief pulp, 12 to 16 are on-off valves, 17 is a check valve, and 1B is a tank.

However, 1. In the conventional device shown in FIG. 1, when setting the gas pressure when the gas accumulator 6 is initially filled with gas, or when changing the set pressure of the gas, the on-off valve 14 is opened and the switch is switched. In some cases, the valve 8 is switched to supply hydraulic oil into the gas accumulator 6, but normally the on-off valve 14 is closed and the switching valve 8 also shuts off the hydraulic oil.

Hydraulic oil is supplied to the accumulator for each injection cycle only to the piston type accumulator 5 with the on-off valve 12 kept open.

In these conventional devices,
As described in Publication No. 9405 and Japanese Patent Publication No. 54-30373, it is possible to reduce the volume of a piston type accumulator and shorten the filling time when filling a gas accumulator with nitrogen gas from a commercially available gas bottle. However, no consideration was given to changes in gas temperature.

That is, if the pressure of the gas such as nitrogen gas filled in the gas accumulator 6 is kept constant,
Changes in proportion to temperature changes. That is, when PO is the pressure at absolute temperature To and PI is the pressure at absolute temperature TI, I T.

becomes.

However, die-casting machines generally start work at temperatures around 10 degrees Celsius in the winter.

The ambient temperature in steady state is about 50°C. and,
The pressure increases in accordance with this temperature change, and the amount of pressure change due to this temperature difference is about 1.14 times, and the influence on the die-cast product is a value that cannot be ignored. Moreover, this change does not stabilize rapidly.

It changes over 30 to 60 shots from the start of work,
In some cases, it changes over about half a day.

Therefore, this causes a decrease in product yield.

Of course, in the conventional device, it is also conceivable to open and close the on-off valves 14 and 15 each time depending on the temperature rise of the hydraulic oil and gas, and manually adjust the amount of oil in the gas accumulator 6 each time. It is virtually impossible to manually perform the adjustment every cycle, and it cannot be performed accurately.

Furthermore, in the conventional device, a mechanical stopper for regulating the upper limit of the rise of the piston 5a is simply attached to the top of the piston type accumulator 5 with an adjustment screw, and the upper limit position of the piston 5a is adjusted to the top of the piston type accumulator 5 for each shot. There was also one that set the piston 5a to a fixed position in the middle of the gas accumulator 6, but this did not include the idea of adjusting the position of the piston 5a according to the temperature of the gas in the gas accumulator 6. Even if the position of the mechanical stopper is manually adjusted every cycle to regulate the stop position of the piston 5a according to the gas temperature,
It is virtually impossible and cannot be done accurately.

The present invention eliminates these drawbacks and automatically adjusts the gas pressure to enable injection under stable injection conditions from the start of one operation, thereby making it possible to improve product quality.

The present invention is equipped with an accumulator that is a combination of a piston type accumulator and a gas accumulator, and a piston stop device that can stop the piston is provided on the gas chamber side of the piston type accumulator so that the position can be adjusted freely, and the pressure of the gas in the gas accumulator is adjusted. Equipped with a pressure sensing device that detects the pressure directly or indirectly, and equipped with a control device that can control the operating position of the piston stop device based on an output signal from the pressure sensing device when the piston of the piston type accumulator hits the piston stop device. .

Next, the present invention will be explained in detail with reference to one embodiment shown in the drawings. In FIG. 2, the same parts as those shown in FIG. 1 are designated by the same reference numerals as shown in FIG. 1, and the explanation thereof will be omitted.

In the embodiment shown in FIG. 2, the top of the piston type accumulator 5 and the top of the gas accumulator 6 are connected to each other, and the top of the piston type accumulator 5 or the middle thereof has a minimum amount necessary for injection into the piston type accumulator 5. A piston stop device 919 is provided which can be vertically adjusted to stop the upward movement of the piston 5a at a position where an amount of hydraulic oil equal to or greater than the required amount is secured. 20 is the piston stop device 1
9 is a position control device for moving the movable part,
As the piston stop device 19, a device such as a magnetic switch that also serves as a position detection device may be used, or a simple movable mechanical stopper may be used, but in any case.

The vertical position of the piston stop device 1914 can be controlled by signals from the control device 22, which will be described later.

Located on the hydraulic oil supply side of the piston type accumulator 5,
A check valve 17a or an electromagnetic switching valve was provided on the pump l side of the on-off valve 12, which is always open during operation. Furthermore, a pressure detector 21 was attached to the gas accumulator 6 to directly detect the pressure of the gas within the gas accumulator 6. However, in order to indirectly detect the pressure of the gas in the gas accumulator 6, the pressure detector 21 may be installed at a position where it can detect the pressure of the hydraulic oil in the gas accumulator 6. 22 is a control device. Yes, it receives an electrical input according to the pressure detected by the pressure sensor 21, and accordingly
The position of the piston stop device 19 can be appropriately controlled via the control device 20 before the next cycle.

In addition, in the piston type accumulator 5, in order to ensure the minimum amount of hydraulic oil required for injection every time, the piston stop device 19 is set not to go lower than a pre-instructed position. is a switching valve 23 for unloading the pump 1.

Next, the operation of the accumulator filling control device shown in diagram rtS2 will be explained.

During the injection operation, the on-off valves 12.13 are always kept open, and the on-off valves 14, 15.16 are always closed.

When the pump 1 is rotated and the on-off valve 12 is opened to start work, the piston 5a in the piston type accumulator 5 approaches its upper limit and is stopped by the action of the piston stop device 19. Therefore, when starting the machine, the pump 1 must be turned on. Before opening the on-off valve 12 by rotating it to a certain extent, and at the time of each injection, the pressure detection device 21 detects the gas The pressure is detected and the vertical position of the piston position stop device 19 is adjusted accordingly by the action of the control device 229 and the control device 20.

Of course, the volume of gas that needs to be in order to obtain a predetermined gas pressure can be set in advance.

Based on this, when the pressure detected by the pressure detector 21 does not reach the specified pressure, the piston stop device 19 is raised to reduce the gas volume, and conversely, when the pressure is higher than the specified pressure, the piston stop device 19 is raised. , the position of the piston stop device 19 is lowered to increase the volume of gas as appropriate. Then, the gas pressure in the gas accumulator 6 is set to a predetermined pressure.

In this way, in the embodiment shown in FIG. 2, the pressure detector fa21 that directly or indirectly detects the pressure of the gas in the gas accumulator 6 is used.

The pressure detection device 21 detects when the piston 5a of the piston type accumulator 5 hits the piston stop device 19.
The output signal from the piston stop device 119 controls the position of the piston stop device 119. However, if the pressure is low and it is necessary to raise the piston stop device 19, it can be done immediately, but conversely, if the pressure is high and it is necessary to lower the piston stop device 19.

Since high pressure is acting under the piston 5a, this cannot be done immediately, in which case it should be done before the first cycle.

The piston type accumulator 5 can be installed upside down or in other conditions by connecting the hydraulic oil supply side to the pump 1 or injection cylinder 3 and the gas working side to the gas accumulator 6. You can leave it there.

In this way, in the present invention, the configuration as described in the claims is adopted.1 The gas pressure of the accumulator is automatically adjusted in response to pressure changes without ignoring pressure changes of hydraulic oil or gas. Moreover, since this adjustment can be made in accordance with the gas pressure for each injection cycle, it is possible to
After starting work 1 Even when the pressure of hydraulic oil or gas is still relatively low, by controlling it, it is possible to easily obtain not only the specified amount of oil in the piston type accumulator, but also the specified gas pressure every time. As a result, it is possible to quickly start obtaining high-quality products, and it is also possible to respond to the so-called billboard method, in which injection is performed in response to requests from the downstream process and the product is promptly sent to the downstream process. . Even when the pressure of hydraulic oil, gas, etc. becomes relatively high, a predetermined gas pressure and oil amount can be automatically and reliably and easily obtained through control, and high-quality products can always be obtained. Note that the gas pressure is high when the hydraulic oil is completely filled and low after injection, and changes during one cycle, but when controlling based on gas pressure, the specified amount of hydraulic oil is in the piston type accumulator. The volume of gas is set using the point of supply as a reference point, and the volume of gas in the gas accumulator can be adjusted based on the pressure when the piston of the piston-type accumulator hits the piston stop device. , gas pressure and oil volume can be controlled reliably. Of course, it is also possible to easily save energy by unloading the pump when the gas volume or gas pressure in the gas accumulator reaches a specified amount or pressure.

[Brief explanation of the drawing]

FIG. 1 is a hydraulic circuit diagram showing an example of a conventional device, and FIG. 2 is a hydraulic circuit diagram showing an embodiment of the present invention. 1...Pump, 3...Injection cylinder, 4.23...Switching valve, 5...Piston type accumulator, 5a...
Piston, 6...Gas accumulator, 7...Valve, 12-16...Opening/closing valve, 19...Piston stop device, 20...Position control Device, 21...Pressure detector, 22...Control device. Patent applicant: Ube Industries, Ltd.

Claims (1)

[Claims] A pressure detection device that is equipped with an accumulator that is a combination of a piston type accumulator and a gas accumulator, has a piston stop device that can stop the piston on the gas chamber side of the piston type accumulator in a position adjustable manner, and detects the pressure of the gas in the gas accumulator. A filling control device for an accumulator, comprising: a control device capable of controlling an operating position of a piston stop device based on an output signal from a pressure sensing device when a piston of the piston-type accumulator hits the piston stop device.