JPH0115461Y2 - - Google Patents

Description

[Detailed description of the invention] a. Industrial application field This invention is based on a hydraulic press brake or shearing machine, in which the ram is long in the left-right direction, and both left and right ends of the ram are pressed by hydraulic cylinders. The present invention relates to a type of hydraulic press, and more particularly, to a hydraulic press in which the inclination of the ram can be corrected near the upper limit of the ram.

b. Prior Art First, the prior art will be explained based on FIG. 4.

FIG. 4 is an explanatory diagram illustrating the relationship between the driving hydraulic cylinders of the hydraulic shearing machine 1, which is one of the conventional hydraulic presses.

The right side of the lower surface of the ram 5 with the movable upper blade 3 attached is shown at a high position because a constant rake angle θ (rake angle, shear angle) is given depending on the thickness and material of the plate to be cut. Because there is.

The one on the left among the drive hydraulic cylinders is the large-diameter hydraulic cylinder 7, and the lower oil chamber 11 of its piston 9 communicates via a conduit 13 with the upper oil chamber 19 of the piston 17 of the small-diameter hydraulic cylinder 15 on the right side of the ram 5. It has been done.

Since the effective cross-sectional area of the lower piston oil chamber 11 of the large-diameter hydraulic cylinder 7 is set to be exactly the same as the effective cross-sectional area of the upper piston oil chamber 19 of the small-diameter hydraulic cylinder 15, oil leaks between both hydraulic chambers and the conduit 13. Unless otherwise specified, the movable upper blade 3 moves up and down while keeping the scooping angle θ.

That is, the conventional hydraulic shearing machine 1 has a large diameter hydraulic cylinder 7.
A series drive system was adopted in which the small-diameter hydraulic cylinder 15 and the small-diameter hydraulic cylinder 15 were connected.

However, if there is an oil leak between the lower hydraulic chambers and the conduit 13, the rake angle changes, so a parallel oil passage 25 is provided between the oil pressure source conduit 21 and the conduit 13 by an electromagnetic switching valve 23, and this is necessary. The rake angle was corrected by replenishing leaked oil accordingly.

c. Problems to be solved by the invention The conventional hydraulic press mentioned above cannot be operated without constantly checking that the shear angle θ is maintained at a predetermined angle during the operation, otherwise the cutter may be damaged. There is the inconvenience of frequent emergency stops,
There was an inconvenience that it took time and effort to correct the shear angle θ.

d. Means for solving the problem In view of the conventional problems as described above, this invention is based on a piston that can move up and down in a large diameter hydraulic cylinder attached to one side of the upper frame and is supported so that it can move up and down in the upper frame. In addition, a vertically movable piston in a small-diameter hydraulic cylinder mounted on the other side of the upper frame is connected to the other side of the ram, and a piston lower oil chamber of the large-diameter hydraulic cylinder is connected to one side of the ram. and an upper oil chamber of a small-diameter hydraulic cylinder are connected via a conduit, and an upper chamber of the large-diameter hydraulic cylinder is connected to a hydraulic pump, and a parallel oil passage is connected between the upper chamber and the conduit. A movable valve body that can freely connect and disconnect the parallel oil passage is slidably provided on the on-off valve disposed in the parallel oil passage, and is biased in a direction to disconnect the parallel oil passage. , when the piston in the large-diameter hydraulic cylinder reaches near its upper limit, the movable valve is pushed against the urging force by the piston or a part of the ram. .

e Effect In the above configuration, when pressure oil is supplied from the hydraulic pump to the upper chamber of the large-diameter hydraulic cylinder, the pressure oil in the lower oil chamber of the large-diameter cylinder is supplied to the upper oil chamber of the small-diameter hydraulic cylinder. The ram is lowered in the same manner as in a standard hydraulic press. Furthermore, when pressure oil is supplied to the lower oil chamber of the small-diameter hydraulic cylinder, the ram is raised and returned to its original position.

When the ram is lifted back up and the piston of the large-diameter hydraulic cylinder reaches near its lifting limit, the movable valve body of the on-off valve is pushed against the force by this piston or a part of the ram, and the parallel oil path is closed. When starting the descent of the ram, supply pressure oil to the upper chamber of the large-diameter hydraulic cylinder as described above. Pressure oil flows into the lower oil chamber of the large-diameter oil chamber cylinder and the small-diameter oil The oil is also supplied to the upper oil chamber of the chamber cylinder, and the inclination of the ram is corrected to its initial state.

f Example FIG. 1 and FIG. 2 show a hydraulic shearing machine 1 which is an example of a hydraulic press embodying the present invention.

This hydraulic shearing machine 1 includes a table 29 in front of a lower frame 27 (left side in FIG. 2), and a fixed lower blade 31 is attached to the rear upper end of the table 29.

Further, a hydraulic pump 35 driven by an electric motor 33 is provided below the table 29, and a hydraulic power source circuit 21 is connected to the large diameter hydraulic cylinder 7 via an oil passage switching valve 37.

A large diameter hydraulic cylinder 7 and a small diameter cylinder 15 are fixed to the upper frame 39 of the hydraulic shearing machine 1.
A ram 5, a ram frame 43, and a swing arm 45 that swing around a swing shaft 41 are provided below each piston rod 9 and 17.

Although not shown, the ram 5 is urged clockwise around the swing shaft 41 in FIG. 2 by, for example, a bullet.

A front plate 47 is provided in front of the upper frame 39, and a plate holder 49 is provided below it so as to be movable up and down.

The large diameter hydraulic cylinder 7 is constructed as shown in FIG.

The hydraulic pressure source conduit 21 is led to the upper chamber 51 of the large-diameter hydraulic cylinder 7, and initially pressurizes only the center portion of the upper surface of the piston 9. Check valve 53 installed later in the center of the top surface
The ball 55 is under pressure and reaches the upper oil chamber annular portion 57 of the piston 9.

A conduit 13 connecting the lower oil chamber 11 of the large-diameter hydraulic cylinder 7 and the upper oil chamber 19 of the piston 17 of the small-diameter hydraulic cylinder 15 and the parallel oil passage 25 that communicates with the above-mentioned upper oil chamber annular portion 57 include parallel oil. An on-off valve that can freely connect and disconnect the passage 25 is provided, and this on-off valve is provided with a movable valve body 59 biased downward by a bullet 6.

As is clear from the figure, the movable valve body 59 plays the same role as the ball of a type of check valve.
The valve seat part 6 of the outer cylinder 63 that guides and slides the valve 9 up and down.
When the movable body 59 is seated on the parallel oil passage 25, the parallel oil passage 25 is closed.

In the embodiment shown in FIG. 3, the length of the leg is set so that when the movable valve body 59 is lowered by 5 mm from the illustrated state, it seats on the valve seat 65 of the outer cylinder 63.

Therefore, as shown in FIG. 6, when the hydraulic pressure from the oil pressure source pipe 21 is introduced into the upper chamber 51 of the large diameter cylinder 7 for the ram 5 which is stopped at the upper limit point, the piston of the large diameter cylinder 7 9 is lowered by 5 mm, the movable valve body 59 separates from the valve seat 65 of the outer cylinder 63 and hydraulic pressure also flows into the parallel oil passage 25.

When the piston 9 descends 5 mm from the upper limit point, the movable valve body 59, which is urged downward by the bullet 61, seats on the valve seat 65 and closes the parallel oil passage 25.

Thereafter, the large-diameter cylinder 7 and the small-diameter cylinder 15 are connected in series and simultaneously descend by the same length.

Thus, in the hydraulic press of this embodiment, a parallel circuit is established every time from before the large-diameter hydraulic cylinder reaches the upper limit point by the set distance until the time when the large-diameter hydraulic cylinder is next started and moves away from the upper limit point by the set distance.

Now, let us consider a case where the large-diameter hydraulic cylinder has hit a predetermined upper limit and has not stopped due to oil leakage during the previous press operation or afterward, and then is started next time.

In this case, the pressure oil led to the upper chamber 51 of the large-diameter hydraulic cylinder 7 only applies downward pressure to the narrow circular part at the upper center of the piston 9, but does not push down the piston 9, but rather pushes up the ball 55 of the check valve 53. The movable valve body 59 passes over the valve seat 65 and reaches the conduit 13.

In this way, the piston 9 is pushed upward to recover the height which did not reach the upper limit due to the oil leak mentioned above.

g. Effects of the invention As can be understood from the explanation of the embodiments above, this invention basically consists of a vertically movable piston in a large-diameter hydraulic cylinder attached to one side of the upper frame, and a vertically movable piston supported by the upper frame. In addition, a vertically movable piston in a small-diameter hydraulic cylinder mounted on the other side of the upper frame is connected to the other side of the ram, and the lower oil of the piston of the large-diameter hydraulic cylinder is connected to the other side of the ram. The upper chamber and the upper oil chamber of the small-diameter hydraulic cylinder are connected to each other via a conduit, and the upper chamber of the large-diameter hydraulic cylinder is connected to a hydraulic pump, and the upper chamber and the conduit are connected to each other through a parallel oil passage. A movable valve body capable of freely connecting and disconnecting the parallel oil passage is slidably provided on the on-off valve disposed in the parallel oil passage, and is biased in a direction to disconnect the parallel oil passage. and configured such that when the piston in the large diameter hydraulic cylinder reaches near its upper limit, the piston or a portion of the ram presses the movable valve against the urging force. Therefore, in this idea,
When pressure oil is supplied from the hydraulic pump to the upper chamber of the large-diameter hydraulic cylinder, the pressure oil in the lower oil chamber of the large-diameter cylinder is supplied to the upper oil chamber of the small-diameter hydraulic cylinder, similar to a general hydraulic press. The ram is lowered. Furthermore, when pressure oil is supplied to the lower oil chamber of the small-diameter hydraulic cylinder, the ram is raised and returned to its original position.

When the ram is lifted back up and the piston of the large-diameter hydraulic cylinder reaches near its lifting limit, the movable valve body of the on-off valve is pushed against the force by this piston or a part of the ram, and the parallel oil path is closed. When starting the descent of the ram, supply pressure oil to the upper chamber of the large-diameter hydraulic cylinder as described above. Pressure oil flows into the lower oil chamber of the large-diameter oil chamber cylinder and the small-diameter oil The oil is also supplied to the upper oil chamber of the chamber cylinder, and the inclination of the ram is corrected to its initial state.

That is, according to this invention, the inclination of the ram is corrected when the ram is returned to the upward position and then begins to descend. Therefore, even if the slope of the ram is different from the initial one due to, for example, leakage of pressure oil at the seal part of the hydraulic circuit, etc., the slope will be corrected to the initial slope when the ram starts to descend. It is something.

Note that this invention is not limited to the above-mentioned embodiments, but can be implemented in other embodiments by making appropriate changes.

[Brief explanation of the drawing]

Fig. 1 is a front view of a hydraulic shearing machine as an embodiment of the present invention, Fig. 2 is a sectional view taken along the - sectional arrow in Fig. 1, Fig. 3 is a sectional view of a large-diameter hydraulic cylinder, and Fig. 4 is a conventional FIG. 5 is an explanatory diagram of the hydraulic circuit of the present invention, and FIG. 6 is a time chart of the apparatus shown in FIG. 5. Symbols representing main parts of the drawing: 1...Hydraulic shearing machine, 3...Movable upper blade, 5...Ram, 7...Large diameter hydraulic cylinder, 15...Small diameter hydraulic cylinder, 25...
... Parallel oil passage, 59 ... Movable valve body, 63 ... Outer cylinder,
65...Valve seat part.

Claims (1)

[Scope of utility model registration request] A vertically movable piston 9 in a large diameter hydraulic cylinder 7 mounted on one side of the upper frame 39 is connected to one side of a ram 5 supported vertically movably on the upper frame 39, and the other side of the upper frame 39 is connected. The vertically movable piston 17 of the small-diameter hydraulic cylinder 15 attached to the ram 5 is connected to the other side of the ram 5, and the lower piston oil chamber 11 of the large-diameter hydraulic cylinder 7 and the upper oil chamber 19 of the small-diameter hydraulic cylinder 15 are connected. of,
The upper chamber 51 of the large diameter hydraulic cylinder 15 is connected to the hydraulic pump 35, and the upper chamber 51 and the conduit 1 are connected to each other via a conduit 13.
3 are connected to each other via a parallel oil passage 25, and the parallel oil passage 25 is connected to the on-off valve disposed in the parallel oil passage 25.
A movable valve body 59 that can be freely connected and disconnected is slidably provided and is biased in a direction to disconnect the parallel oil passage 25, so that when the piston 9 in the large diameter hydraulic cylinder 7 reaches near the upper limit, This piston 9
Alternatively, the movable valve body 59 may be moved by a portion of the ram 5.
A hydraulic press characterized in that it is configured to press against an urging force.