JPH03320Y2 - - Google Patents

Description

[Detailed description of the invention] The invention relates to a cylinder stroke regulating device in a hydraulic press, and more specifically, in a hydraulic press in which the upper die and the lower die approach and separate from each other to perform bending processing, the upper die and the material This invention relates to a device for preventing the so-called bottoming out condition in which the lower mold is in close contact with the bottom mold.

First, the background behind the invention of the present invention will be explained with reference to FIG.

Figure 1 shows an example of a hydraulic press brake 1, which is a type of hydraulic press.
A crown 9 is attached above the left and right side plates 7, and a left fluid pressure cylinder 11 and a right fluid pressure cylinder 13 are provided as fluid pressure cylinder devices on the front surface of the crown 9.

The piston rods 15 and 17 of the left and right hydraulic cylinders 11 and 13 are respectively connected near both left and right ends of the upper beam 19, and an upper mold 23 is attached below the upper beam 19 via an intermediate plate 21. There is.

The press brake 1 described above sends pressure oil from a hydraulic pump 25 (see FIG. 4) to the left and right hydraulic cylinders 11 and 13 to raise and lower the beam 19,
This is a press machine that bends a material between an upper die 23 and a lower die 5.

Conventionally, the above-mentioned hydraulic press was equipped with a device to prevent troubles such as bottoming, but a relief valve 27 (see Fig. 4) was installed near the discharge port of the hydraulic pump 25 to prevent abnormally high pressure. The hydraulic pressure was detected and the hydraulic pressure was returned to the oil tank 29 (see FIG. 4).

The above-mentioned device using the conventional relief valve 27 operates even if the oil passage is clogged even if bottoming does not actually occur, and when the relief valve 27 operates correctly, it can be used for example in an expensive upper and lower type. In some cases, damage occurred even after excessive strain had occurred.

The present invention has been made to solve the above-mentioned disadvantages of the conventional apparatus, and preferred embodiments will be described in detail below based on the drawings.

The first embodiment of the present invention is similar to the second, third, fifth, and sixth embodiments of the present invention.
It is configured as shown in the figure.

Since the left and right fluid pressure cylinders 11 and 13 are symmetrical objects having the same size and shape, the right fluid pressure cylinder 13 is shown as an example in FIG.

The right fluid pressure cylinder 13 is also fixed to the crown 9 via a bracket 31, and if the part that slides on the inner wall of the cylinder is defined as a piston, then the piston 33 is provided with a length that is not much different from the length of the cylinder. be.

The piston 33 also has a deep hole 37 that engages with a tube 35 hanging from the center of the ceiling of the cylinder 13, and the bottom of the deep hole 37 forms a small-diameter hydraulic chamber 39.

Therefore, the upper surface of the piston 33 constitutes an annular large-diameter hydraulic chamber 41, and a third hydraulic chamber 45 is formed between the cylinder 13, the long piston 33, and a seal ring 43 provided at the lower end of the cylinder 13. There is an oil room named after it.

In addition, in FIG. 2, the oil passage communicating with the small diameter hydraulic chamber 39 provided in the piston rod 33 is designated as A oil passage 47, and the oil passage communicating with the annular large diameter hydraulic chamber 41 is designated as B oil passage 49. The oil passage communicating with the counterbalance valve 51 (see Fig. 3) is connected to the C oil passage 5.
Named 3.

The oil passage provided in the middle of the seal ring 43 is a leak drain oil passage 55.

A moving member 57 is provided on a portion of the piston 33, and an opening/closing valve 61 is provided which is operated by an operating rod 59 that engages with the moving member 57 and is moved laterally.

Next, the operation of the hydraulic press brake 1 will be explained with reference to the hydraulic piping diagram in FIG.

The upper beam 19 of the press brake 1 is
The piston rod 15 of the left hydraulic cylinder 11
It is swingably attached to the lower end of the piston rod 17 of the right hydraulic cylinder 13 via a swing mechanism 63.

Pressure oil from the hydraulic pump 25 flows through the flow divider 67 when the solenoid switching valve 65 is placed in the center position at position 3.
The upper beam 19 starts to descend as it reaches the upper beam 19 and is divided into left and right parts and flows into the small diameter hydraulic chambers 39 of the left and right hydraulic cylinders 11 and 13.

In this case, two pulleys 6 placed apart in a horizontal position
9, 69, a balance device 73 constituted by a wire 71 run diagonally around these pulleys, and a drain switching valve 75 driven by the wire 71, the balance relationship of the upper beam 19 with respect to the lower die 5 is maintained. be done.

In this way, the upper beam 19 descends at a high speed, but when the material is clamped between the upper and lower molds 23 and 5 and bending begins, a pressure detection device (not shown) is activated, and a sequence valve is activated. 77
, the pressure oil from the flow divider 67 is switched to the large-diameter hydraulic chamber 41, and the pressure changes to a low-speed, large-pressure drop.

While the low speed is descending due to pressure, the counterbalance valve 51 maintains the oil pressure balanced with the biasing force of the spring 79 and continues to drain oil from the C oil path 53 to the oil tank 29.

As shown in FIG. 6, just before the upper die 23 comes into contact with the lower die 5 (so-called bottoming), the moving member 57 comes into contact with one end of the operating rod 59, and the steel ball 81 in the on-off valve 61 is moved by the spring 83. Since the valve is moved away from the valve seat against the pressure, the pressure oil in the B oil passage 49 is drained.

Therefore, the above-mentioned counterbalance valve 5
The downward movement of the upper beam 19 is immediately stopped by the balance pressure caused by the spring 79 maintained in the pressure oil between the first and third hydraulic chambers 45.

In order to separate the upper die 23 and the lower die 5, by switching the position 1 of the solenoid switching valve 65 to the center, the pressure oil passing through the C oil passage 53 is transferred to the third hydraulic pressure via the check valve 85 of the counterbalance valve 51. There is no need to specifically explain that it can be carried out by sending it into the chamber 45.

The oil passage 87 shown in FIG. 3 corresponds to the oil passage 87 in FIG.
The same numbers are attached to the piping diagram in the figure.

FIG. 7 shows a second embodiment of the present invention, which differs from the first embodiment in that a spool shaft 93 is provided on the upper surface of the piston 33, and a spool 95 is provided above the spool shaft. The main feature is that the pressure oil in the large diameter hydraulic chamber 41 is drained into the oil tank 29 via an oil passage 91.

The apparatus according to the embodiment of the present invention described in detail above directly mechanically moves the bottoms of the upper mold 23 and the lower mold 5 by moving and occupying the positions occupied by the pistons 33 of the hydraulic cylinders 11 and 13 that move up and down the upper beam 19. Because it is configured to stop the approach just before the bottoming point, unlike conventional stopping devices that utilize abnormally high pressure generation when bottoming occurs, it is possible to reliably prevent trouble before bottoming occurs. This enabled us to eliminate malfunctions caused by clogging of hydraulic pipes.

As can be understood from the above description of the embodiments, the present invention can be summarized as follows. piston rod 33 in the fluid pressure cylinders 11, 13.
An on-off valve 61 connected to a large-diameter hydraulic chamber 41 for projecting and operating is provided connected to the oil tank 29,
The moving member 57 that operates the operating rod 59 for opening the on-off valve 61 is connected to the piston rod 3.
3, a counter balance valve 51 is connected to a hydraulic chamber 45 for returning the piston rod 33 in the hydraulic cylinders 11, 13, which communicates only when the hydraulic chamber 45 has a predetermined pressure or higher. be.

As is clear from the above configuration, in the present invention, the large diameter hydraulic chamber 41 for causing the piston rod 33 of the fluid pressure cylinders 11 and 13 to operate in a protruding manner has an on-off valve 6 connected to the oil tank 29.
1 is connected, and this on-off valve 61 is connected to the actuating rod 5 by a moving member 57 provided on the piston rod 33.
It is operated to open via 9. Therefore, from the hydraulic cylinder 11 to the piston rod 33
When the piston rod 33 is protruded and reaches a predetermined position, the on-off valve 61 is always opened, and the pressure oil in the large diameter hydraulic chamber 41 is discharged to the oil tank 29, so that the piston rod 33 is further protruded. For example, it is possible to reliably prevent bottoming out, thereby ensuring safety.

In addition, a hydraulic chamber 45 for returning the piston rod 33 in the fluid pressure cylinder 11 includes:
Since it is connected to the counterbalance valve 51 that communicates when the pressure is above a predetermined pressure, when the on-off valve 61 is opened as described above, the counterbalance valve 51 is closed, and the piston rod 33 in the fluid pressure cylinder 11 and It is possible to prevent the upper beam 19 of the hydraulic press from descending under its own weight, and safety is maintained even against falling under its own weight.

[Brief explanation of the drawing]

Fig. 1 is a front view of a hydraulic press to explain the implementation background of the present invention, Fig. 2 is a cross-sectional view of the hydraulic cylinder that drives the upper and lower molds, Fig. 3 is a cross-sectional view taken in the direction of the - sectional arrow in Fig. 2, 4 is a hydraulic piping diagram, FIG. 5 is a sectional view taken in the direction of the arrow in FIG. 3, FIG. 6 is a sectional view taken in the direction of the arrow in FIG. It is a 2nd Example figure corresponded to. Explanation of symbols representing main parts of the drawings: 1...Press brake, 13...Right fluid pressure cylinder, 33...
...Piston, 39...Small diameter hydraulic chamber, 41...Large diameter hydraulic chamber, 51...Counter balance valve, 57
...Moving member, 61...Opening/closing valve, 95...Spool.

Claims (1)

[Scope of utility model registration request] The hydraulic cylinders 11, 13 are used as a cylinder stroke regulating device in a hydraulic press in which the upper beam 19 is moved up and down by the hydraulic cylinders 11, 13 attached to the upper parts of the left and right side plates 7, 7.
An on-off valve 61 connected to a large-diameter hydraulic chamber 41 for protruding the piston rod 33 is provided connected to the oil tank 29, and a moving member 5 operates an actuating rod 59 for opening the on-off valve 61.
7 is provided on the piston rod 33, and the piston rod 3 is provided in the fluid pressure cylinders 11, 13.
3. A cylinder stroke regulating device for a hydraulic press, characterized in that a counterbalance valve 51 is connected to a hydraulic chamber 45 for returning the cylinder 3 to a counterbalance valve 51 that communicates only when the pressure in the hydraulic chamber 45 is higher than a predetermined pressure.