JPS5925599Y2 - Pressure device - Google Patents

Description

[Detailed description of the invention] This invention relates to a pressurizing device such as a press machine.

A press machine shown in FIG. 1 is known.

This press machine consists of a support column 2 provided on a machine frame 1.
A movable platen 3 is attached to the machine frame 1 so as to be able to move up and down, and a hydraulic cylinder 4 is provided between the machine frame 1 and the movable platen 3 to move the movable platen 3 up and down with respect to the machine frame 1.
A first conduit 8 and a second conduit 9 are provided on the head side H and rod side R of the above-mentioned system to connect them to the hydraulic pump 6 and the oil tank 7 via the 4-point 3-position directional switching valve 5. The first pipe line 8 is provided with an on-off valve 10 for opening and closing it, and the second pipe line 9 is provided with a drain oil pipe line 12 equipped with an on-off valve 11.
A surge tank 14 is connected to the head side H of the hydraulic cylinder 4 via an on-off valve 13. When the on-off valve 11.13 is opened from the state shown in FIG. When the on-off valve 10 is opened from the state shown in Fig. 1 and the directional control valve 5 is moved to the left, the movable platen 3 is lowered at high pressure and low speed by the action of the hydraulic pump 6, and the on-off valve 13 is opened again from the state shown in Fig. 1. When the directional control valve 5 is moved to the right, the movable platen 3 moves to the hydraulic pump 6.
It is designed to rise rapidly due to the action of

The hydraulic circuit of the press machine mentioned above is called a dead weight drop circuit, and it is possible to make effective use of the weight of the movable platen 3 and the mold attached to it to lower them at high speed. 6 and the main valves have the advantage of being economical because they only require a small amount of oil for the high-pressure, low-speed descent at the final stage of the stroke and the high-speed rise using the rod-side pressure-receiving surface. There are drawbacks to the opposite method.

(a) Since the hydraulic cylinder 4 is attached to the upper part of the machine frame and has a surge tank 14, the machine height is high.

(b) In order to maintain the amount of oil in the surge tank 14, a monitoring device and an oil refilling and draining device are required, making the structure complicated;
It's also expensive.

(c) Since it has a surge tank 14, it is difficult to make the machine tiltable, and it cannot meet the requirements of a mold clamping machine of a liquid reaction molding machine.

(b) In the upward direction, it is not possible to easily combine high-pressure, low-speed upward movement and high-speed upward movement.

This idea was constructed so that the weight of the movable platen was applied to the rod side of the hydraulic cylinder in the past, but it is now configured so that the weight of the movable platen is applied to the head side of the hydraulic cylinder. The conduit and the second conduit are connected to each other by a bypass conduit equipped with an on-off valve, and an on-off valve is provided between the bypass conduit and the directional control valve of the second conduit. By providing an oil drain pipe having an on-off valve in at least one portion of the first pipe, the second pipe, and the bypass pipe, which are hydraulically connected through the bypass pipe when the on-off valve is opened,
It is an object of the present invention to provide a pressurizing device which fundamentally solves the above conventional problems, does not require a surge tank, has a low height, has a simple structure, and has good performance.

This invention will be explained in detail below with reference to the drawings.

FIG. 2 shows an embodiment of this invention, in which 21 is a fixing member (machine frame).

A pair of left and right hydraulic cylinders 24 are attached to the fixing member 21 with their piston rods 24a facing upward and their cylinder bodies 24b fixed to the fixing member 21,
Further, a movable member (movable plate) 23 is supported above the fixed member 21 by the piston rod 24a of the pair of left and right hydraulic cylinders 24, and the weight of the movable member 23 is applied to the head side H of the hydraulic cylinder 24. It is configured as follows.

A first pipe connects the head side H and rod side R of the hydraulic cylinder 24 to the hydraulic pump 26 and oil tank 27 via a 4-point 3-position directional switching valve 25. A conduit 28 and a second conduit 29 are provided, respectively.
When the directional control valve 25 is moved to the right from the neutral position shown in Fig. 2,
The hydraulic pump 26 is connected to the head side H of the hydraulic cylinder 24, and the rod side R of the hydraulic cylinder 24 is connected to the oil tank 27, and when the directional control valve 25 is moved to the left in FIG. is connected to the rod side R of the hydraulic cylinder 24, and the head side H is connected to the oil tank 2.
7 will be contacted.

On the other hand, the first pipe line 28 and the second pipe line 29 are connected to an on-off valve 35.
In addition, an on-off valve 30 is provided between the bypass pipe 36 of the second pipe line 29 and the directional control valve 25, and the bypass pipe of the first pipe line 28 Drain oil pipe line 3 having an on-off valve 31 in a portion of line 36
2 is provided.

Next, the operation of the pressurizing device according to the invention constructed as described above will be explained.

FIG. 2 shows the pressurization preparation state, and when the on-off valve 31.35 is opened in this state, the movable member 23 descends at high speed due to its own weight.

In this case, oil on the head side H of the hydraulic cylinder 24 is sucked into the rod side R through the bypass pipe 36, and excess oil caused by the difference in area between the rod side and the head side of the cylinder passes through the oil drain pipe 32. The oil is then returned to the oil tank 27.

When the movable member 23 has finished descending to the predetermined position in this way, the on-off valves 31 and 35 are closed and the on-off valve 30 is opened.
Furthermore, push the directional control valve 25 to the left to switch the hydraulic pump 26 to the second position.
Connect to conduit 29.

By this operation, the movable member 23 moves downward at high pressure and low speed to perform work such as pressing or mold clamping.

When the work of the press or the like is completed by lowering the movable member 23 under high pressure and at low speed, the directional control valve 25 is moved to the right in this state to connect the hydraulic pump 26 to the first pipe line 28.

This operation causes the piston rod 24a to move upward, causing the movable member 23 to rise.

In this case, the movable member 23 is raised at a high pressure and low speed, but if it is to be raised at a higher speed, the on-off valve 30 is closed and the on-off valve 35 is opened, and the hydraulic pump 26 is moved to the hydraulic cylinder 2.
The head side H and the rod side R of 4 are connected to form a so-called differential circuit.

In this case, is the same pressure applied to the head side H and rod side R of the hydraulic cylinder 24?The difference in area (corresponding to the rod area) is greater on the head side than on the rod side.
The force increases, generating a rising force, and the amount of oil from the pump is equal to the rod area multiplied by the speed.
This causes the movable member 23 to rise at high speed.

FIG. 3 shows another embodiment of this invention, and this pressurizing device has the following features except that the cylinder body 24b is fixed to the movable member 23 and the lower end of the piston rod 24a is fixed to the fixed member 21. Since it is basically the same as the pressurizing device shown in FIG. 2, it will be given the same reference numerals and detailed explanation thereof will be omitted.

Although the symbols of the on-off valves in the explanatory drawings are those of electromagnetic valves, it goes without saying that the invention is not limited to this, and that the present invention can be realized using various types of valves that satisfy the above-mentioned functions and their combinations.

Furthermore, since the oil drain line 32 is for draining excess oil in the line when the movable member 23 falls flat due to its own weight, it is hydraulically connected when the first on-off valve 35 is opened. It may be provided anywhere in the first conduit 8, second conduit 9, and bypass conduit 36, and is not limited to the connection position in the above embodiment.

As explained above, the pressurizing device according to this invention does not have a surge tank unlike conventional pressurizing devices, and since the cylinder is not located on the top of the machine frame, the height is reduced accordingly, and the surge tank does not have a cylinder. It simplifies the structure by eliminating the need for essential oil level monitoring devices, oil replenishment and discharge devices, and can be tilted to meet the requirements of mold clamping machines for liquid reaction molding machines. There are advantages.

Furthermore, since the movable member can be raised at high pressure and low speed and/or high speed, it is ideal for applications that require both mold closing force and striking force.

[Brief explanation of drawings]

FIG. 1 is a front view of a conventional pressurizing device, FIG. 2 is a front view of a pressurizing device showing one embodiment of this invention, and FIG. 3 is a front view of another embodiment. 21... Fixed member, 23... Movable member, 24... Hydraulic cylinder, 25... Directional switching valve, 26... Hydraulic pump , 27...
...Oil tank, 28...First pipe line, 29...
...Second pipe line, 30...Second on-off valve, 31.
...Third on-off valve, 32...Drain oil pipe, 3
5...First on-off valve, 36...Bypass pipe line, H...Head side, R...Rod side.

Claims (1)

[Scope of utility model registration request] In a pressurizing device configured such that a fixed member and a movable member are connected vertically by a hydraulic cylinder, and the movable member is moved up and down with respect to the fixed member by expansion and contraction of the hydraulic cylinder, the weight of the movable member is The relationship between a fixed member, a movable member, and a hydraulic cylinder is determined so as to work on the head side of the cylinder, and a hydraulic pump is connected to the head side and rod side of the hydraulic cylinder via a directional control valve. A first pipe line and a second pipe line are respectively provided which communicate with the oil tank, and a bypass pipe line provided with a first on-off valve is connected to the first pipe line and the second pipe line. A second on-off valve is provided between the bypass pipe branch point of the second pipe line and the directional switching valve, and a second on-off valve is provided between the bypass pipe branch point of the second pipe line and the directional switching valve. An oil drain pipe having a third on-off valve is provided leading to the oil tank from any part of the bypass pipe, between the switching valve, between the hydraulic cylinder of the second pipe and the second on-off valve, and from any part of the bypass pipe. A pressurizing device characterized by comprising: