JP7121890B2 - Stroke measuring device for local pressure cylinder and its stroke measuring method - Google Patents

Description

The present invention relates to a stroke detector capable of accurately measuring the stroke of a local pressure cylinder of a casting apparatus.

Conventionally, as a countermeasure against shrinkage cavities in casting products in die casting, a local pressurization cylinder is known. In this method, a thin pin is inserted into the mold immediately before the molten metal is cast and almost solidified, and the volume displaced by the pin compensates for the shrinkage cavities. This is often used as a local pressure die casting method (squeeze pin). As for the stroke of the local pressure cylinder, it is important to press and balance the molten metal just before it solidifies. The longer the stroke, the greater the displacement volume, requiring full utilization of the operable stroke. Since it does not operate beyond the structural stroke end of the cylinder, it is best to stop just before the end in balance with coagulation, but delicate measurement control is essential. Also, the squeeze pin pressure at the time of pressing is as high as 150 to 300 MPa, as opposed to 50 to 80 MPa for normal casting pressure (metal pressure). This is to crush the semi-solidified molten metal that is about to solidify. In addition, during continuous casting, the temperature of the working oil in the mold and machine rises, and the stroke of the local pressurization cylinder becomes unstable due to the cooling inside the mold and the release agent.

Conventionally, as a method for detecting the stroke, there is known a method in which a position detection sensor is directly attached to a local pressure cylinder attached to the mold. However, this has the drawback that the life of the position detection sensor is short because the die casting mold is hot and vibrates a lot. Further, as shown in Patent Document 1, there is also known a device that measures the amount of oil coming out of a local pressurization cylinder with a precision flow meter. However, precision flowmeters have the problem that leaks can cause measurement errors, and they also have the drawback that the amount of leaks changes depending on the hydraulic oil temperature. Furthermore, there is also a type in which the amount of oil coming out of the local pressure cylinder is received by a measuring cylinder and this position is measured. However, there is a drawback that an error occurs due to the bubble ratio of the hydraulic oil (compression of air) and expansion of rubber hoses due to compression.

JP-A-09-225619

An object of the present invention is to accurately measure the stroke amount of a local pressurization cylinder by paying attention to the above conventional problems.

The amount of oil coming out of the local pressure cylinder is received by the measuring cylinder and the position is measured. The accumulated gas from the hydraulic circuit up to the cylinder is exhausted every shot or periodically from the drain port through the solenoid valve.

Specifically, the stroke detection device according to the present invention is a device for measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil coming out of the local pressurization cylinder. A cylinder body for measuring the amount of discharged oil is provided in the discharge path, a check valve and an orifice (throttle valve) are integrally provided in the piston of the measurement cylinder body, and a solenoid is installed in the path branching from the discharge path side of the local pressurization cylinder. Drainage is provided via a valve. Although the check valve and the orifice (throttle valve) are integrally provided in the above example, the orifice may be provided alone.

In addition, in the device for measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, the cylinder body for measuring the amount of discharged oil is installed in the discharge path of the hydraulic oil of the local pressurization cylinder. A check valve is provided in the path bypassing the measuring cylinder main body, and a drain is provided via a solenoid valve in the path branching from the discharge path side of the local pressurization cylinder.

Further, the stroke measurement method according to the present invention is a method for measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, wherein the piston of the cylinder body measuring the amount of discharged oil is measured. A check valve is integrally provided, and oil mixed with gas is returned to the tank via a solenoid valve by draining every shot or periodically.

Further, in the method of measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, a check valve is provided in a path bypassing the cylinder main body for measuring the amount of discharged oil, It is characterized in that the oil mixed with gas is returned to the tank through a solenoid valve by draining every shot or periodically.

As a result, the air bubbles contained in the hydraulic oil used for measurement can be eliminated each time or periodically, and the elimination effect increases cumulatively, and a state in which no air bubbles are contained can be maintained. A steel pipe hose is used instead of rubber between the local pressure cylinder and the measuring cylinder.

The stroke of the local pressure cylinder can be accurately measured.
It is possible to measure the position of cylinders without stroke measurement sensors of local pressure cylinders.
Stroke measurement of durable local pressurization cylinders is possible.

1 is a hydraulic system diagram of a stroke detection device according to an embodiment; FIG. FIG. 11 is a hydraulic system diagram of a stroke detection device according to a second embodiment;

An embodiment of a stroke detection device according to the present invention will be described in detail below with reference to the drawings. It should be noted that the following description is merely an example, and includes modifications that share the technical idea of the present invention.

FIG. 1 shows an example in which a stroke detection device is provided in a discharge oil system of a local pressure cylinder. First, the local pressurization cylinder 10 has a cylinder body 12 and a built-in piston 14. A piston rod 16 integrated with the piston 14 is protruded from the cylinder body 12 and inserted into a cavity of a casting apparatus (not shown). 16 in and out. The piston rod 16 of the local pressurization cylinder 10 is inserted into the cavity just before the molten metal cast into the cavity is almost solidified, and the volume displaced by the piston rod 16 compensates for shrinkage cavities. Therefore, hydraulic oil is supplied to the oil supply passage on the cylinder head side via the pump 18, the direction switching valve 20, and the throttle valve 22, and the hydraulic oil on the cylinder rod side passes through the direction switching valve 20. and return to the tank 24.

In the oil discharge system of the local pressurization cylinder 10, a stroke detector is provided between the hydraulic oil outlet of the local pressurization cylinder 10 and the direction switching valve 20 in order to measure the pushing stroke of the local pressurization cylinder 10. 26 is arranged to measure the amount of hydraulic oil discharged from the room on the cylinder rod side of the local pressurization cylinder 10 .

The stroke detection device 26 is composed of a cylinder-piston structure, which is composed of a cylinder body 28 and a piston 30 that can slide inside. One chamber partitioned by the piston 30 of the cylinder body 28 is connected to the hydraulic fluid outlet of the local pressure cylinder 10 and the other chamber is connected to the directional switching valve 20 . As a result, the hydraulic oil discharged from the local pressurization cylinder 10 enters the stroke detection device 26 by the amount discharged, and the piston 30 is moved. A piston rod 32 is integrally provided with the piston 30 and projects from one end of the cylinder body 28 and is connected to a linear potentiometer 34 . The operation starting point of the piston rod 32 is one end of the cylinder body 28 (the left end in FIG. 1), which coincides with the pressurization starting point of the piston 14 of the local pressure cylinder 10 (upper end in FIG. 1). . Therefore, when the local pressurizing cylinder 10 is at the starting position of the pressurizing operation, the piston 30 of the stroke detecting device 26 is positioned at the operation starting point, and together with the pressurizing operation of the local pressurizing cylinder 10, the stroke detecting device 26 The piston 30 is moved by the injection of hydraulic oil, and moves proportionally.

A linear potentiometer 34 is arranged parallel to the piston rod 32 and moves with the piston rod 32 to determine its travel distance. Movement of the piston rod 32 thus appears as the output of the linear potentiometer 34 . A limit switch 36 is arranged at the starting point of the operation of the piston rod 32 . The limit switch 36 is turned on when the piston rod 32 is at the starting point of operation, that is, when the piston 30 is positioned at the left end of the cylinder body 28, thereby detecting the stroke detection starting position.

In such a stroke detection device 26, the piston 30 is provided with a through-hole communicating with the chambers partitioned by the piston 30, and a check valve 38 and an orifice (throttle valve) 39 are attached to the through-hole. ing. This check valve 38 is a one-way valve that blocks the flow of hydraulic fluid pushed out from the chamber containing the hydraulic fluid of the local pressure cylinder 10 to the chamber on the side of the direction switching valve 20 and allows the flow in the opposite direction. be done. As a result, the stroke detection device 26 detects the total amount of hydraulic oil when the local pressure cylinder 10 performs the pressurization operation, and when the stroke detection device 26 returns to the origin position, that is, the operation start point, or when the local pressure cylinder 10 When returning to the operation starting point, if the amount of oil from the local pressurization cylinder 10 to the stroke detection device 26 is insufficient for some reason such as hydraulic oil leakage, the pump 18 is used to replenish the oil. An orifice (throttle valve) 39 regulates the flow rate of the check valve 38 . Also, if the cracking pressure (spring force) of the check valve 38 is weak, the piston will flow through the check valve in a stopped state. This orifice (throttle valve) 39 may be a variable throttle, or may be a fixed throttle, if desired.

A branch path 40 leading to the tank 24 is provided in the path leading to the discharge oil outlet of the local pressure cylinder 10 and the stroke detecting device 26, and a check valve 42 and a solenoid valve 44 are interposed in the branch path 40. When the piston rod 32 of the stroke detection device 26 does not press the limit switch 36, the branch path 40 is assumed to contain gas in the hydraulic oil in the path, and the limit switch 36 is turned on. The solenoid valve 44 is actuated every shot or periodically until the gas is released.

In such a stroke detection device 26, when the pressurization work by the local pressurization cylinder 10 is started, the piston 14 is pushed down in FIG. enters the room and pushes the piston 30 toward the direction switching valve 20 side. At this time, the check valve 38 provided on the piston 30 is in a closed state, and therefore the amount of movement of the piston 30 is proportional to the amount of movement of the local pressure cylinder 10 . A potentiometer 34 is connected to the piston 30 so that reading the potentiometer 34 provides an accurate reading of the amount of movement of the actuating piston 14 of the local pressure cylinder 10 .

Then, by switching the direction switching valve 20, the local pressurization cylinder 10 enters the return operation, the pressure of the pump 18 is applied to the piston 30 of the stroke detection device 26, and the operation used for pressurization by the local pressurization cylinder 10 is applied. The entire amount of oil is pushed back. The amount of pushing back oil moves the piston 30 of the stroke detector 26 to the origin position and pushes the piston 14 of the local pressure cylinder 10 back to the origin position. The stop position is detected by the limit switch 36, and the pump 18 stops and ends.

Here, since the piston 30 of the stroke detection device 26 is provided with the check valve 38, the amount of oil from the piston discharge path of the local pressure cylinder 10 to the stroke detection device 26 decreases due to oil leakage or the like. If so, it is replenished through the check valve 38, and the piston 30 of the stroke detector 26 and the piston 14 of the local pressure cylinder 10 are returned to their original positions.

Conversely, when the amount of oil from the piston discharge path of the local pressurization cylinder 10 to the stroke detection device 26 increases due to internal gas expansion or the like, the solenoid valve 44 provided in the branch path 40 is turned on every shot or periodically. By opening, the piston 30 of the stroke detection device 26 and the piston 14 of the local pressure cylinder 10 are returned to their original positions.

In this way, the piston 30 of the stroke detection device 26 is provided with a check valve 38 and an orifice (throttle valve) 39, and a branch path 40 is provided between the piston discharge path of the local pressure cylinder 10 and the stroke detection device 26, Since the amount of hydraulic oil to be metered is always kept accurate, stroke detection is performed accurately in this embodiment, and the correct stroke of the local pressurization cylinder 10 can be measured. The measurement data can be displayed in analog and digital form on the color liquid crystal touch panel, and the data can be saved.

In the above example, the piston 30 is provided with the check valve 38 and the orifice (throttle valve) 39, but this can also be realized with the orifice (throttle valve) 39 alone.
Next, FIG. 2 shows a second embodiment. In the first embodiment, the piston 30 is provided with the check valve 38, but in the second embodiment, the cylinder body 28 is provided with the bypass passage 46, in which the check valve 38A and the orifice (throttle valve) 39A are provided. The difference is that the Even in this way, the same effects as in the first embodiment can be obtained. That is, when the amount of oil from the piston discharge path of the local pressurization cylinder 10 to the stroke detection device 26 is low due to oil leakage or the like, it is replenished through the check valve 38A, and the piston 30 of the stroke detection device 26 or the The return of the piston 14 of the local pressure cylinder 10 to the original position is achieved.

DESCRIPTION OF SYMBOLS 10... Local pressure cylinder, 12... Cylinder body, 14... Piston, 16... Piston rod, 18... Pump, 20... Direction switching valve, 22... Throttle valve, 24... Tank, 26... Stroke detector 28 Cylinder body 30 Piston 32 Piston rod 34 Potentiometer 36 Limit switch 38 Check valve 39 Orifice (throttle valve) 40 ... branch route, 42 ... check valve, 44 ... solenoid valve, 46 ... bypass route.

Claims (6)

In a device for measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, a cylinder body for measuring the amount of discharged oil is provided in the discharge path of the hydraulic oil of the local pressurization cylinder, A check valve and an orifice (throttle valve) are provided integrally with the piston of the measuring cylinder body, and a drain is provided via a solenoid valve in a path branching from the discharge path side of the local pressurization cylinder. Stroke detector. In a device for measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, a cylinder body for measuring the amount of discharged oil is provided in the discharge path of the hydraulic oil of the local pressurization cylinder, A check valve and an orifice (throttle valve) are provided in the path bypassing the measuring cylinder main body, and a drain is provided via a solenoid valve in the path branching from the discharge path side of the local pressure cylinder. Stroke detector. In a device for measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, a cylinder body for measuring the amount of discharged oil is provided in the discharge path of the hydraulic oil of the local pressurization cylinder, A stroke detection device characterized in that an orifice (throttle valve) is provided integrally with the piston of the measuring cylinder main body, and a drain is provided via a solenoid valve in a path branching from the discharge path side of the local pressurization cylinder. In the method of measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, a check valve and an orifice (throttle valve) are integrated with the piston of the cylinder body for measuring the amount of discharged oil. wherein the oil mixed with gas is returned to the tank via the solenoid valve by draining every shot or periodically. In the method of measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, a check valve and an orifice (throttle valve ) is provided, and oil mixed with gas is returned to the tank via a solenoid valve every shot or periodically by draining. In the method of measuring the stroke amount of the piston of the local pressurization cylinder based on the amount of oil discharged from the local pressurization cylinder, an orifice (throttle valve) is provided integrally with the piston of the cylinder body for measuring the amount of discharged oil, and gas A stroke measuring method characterized in that the oil mixed with the oil is returned to the tank through a solenoid valve by draining every shot or periodically.

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