JP2000225417A - Press brake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a press brake for improving the accuracy in upper and lower positioning of a die by reducing the effects by the difference of bending length, change of oil temperature and deformation of a frame. SOLUTION: When bending work is executed to a plate by cooperation with a punch P and a die D, because a cutoff valve 17 is provided on one side of a lower table 7 or an upper table 9 and a critically positioning pin 21 for deciding a critical position on other side, the flow of hydraulic oil is interrupted by pushing a valve member with the critical positioning pin 21 through the pin 19 of the cutoff valve 17 when the table reaches the critical position. At this time, a cylinder which is integrally provided to the valve member is operated with the pressurized hydraulic oil and the hydraulic oil is interrupted by surely moving the valve member 45. When the supply of the hydraulic oil to hydraulic cylinders 5L, 5R is interrupted with the cutoff valve 17, the hydraulic oil which is fed from a pump is directly returned into a tank by the action of a relief valve.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press brake for bending a flat plate.

[0002]

2. Description of the Related Art In order to manufacture a three-dimensional product from a flat plate as a work, a bending process must be performed, and it is always required to bend to a predetermined angle with high precision. For example, a press brake 101 for bending a flat plate W by cooperation of a punch P and a die D as shown in FIG.
In the above, when the foot switch 107 is turned on, the hydraulic oil pumped up from the tank 105 by the pump 103 is pressed into the main cylinder 111 by the action of the distributor 109 to rapidly raise the die D.

When the die D rises rapidly to a predetermined position,
Hydraulic oil is pressed into the sub-cylinder 115 by the action of the speed switching valve 113, and the die D rises strongly at a low speed to bend the flat plate W. When the die D rises to the upper limit position where the bending is completed, the upper limit valve 117 is opened by the upper limit lever device (not shown), and the hydraulic oil is returned to the tank 105. A pressure sensor 119 is provided in front of the upper limit valve 117 to monitor the pressure.

[0004] Referring to FIG.
In this embodiment, a first oil passage 121 connected to the distributor 109 and a second oil passage 123 for returning the hydraulic oil to the tank 105 are provided.
5, the flow rate of the hydraulic oil is controlled. Since the positioning pin 125 is normally urged upward by the spring 127, the first oil passage 121 and the second oil passage 123 are shut off.
7, and is supplied to the main cylinder 111 and the sub-cylinder 115 to raise the die D.

On the other hand, when the die D reaches the upper limit position, an upper limit lever device (not shown) pushes down the positioning pin 125 to move the oil passage 121 and the oil passage 123 through the flow passage gap 129.
Through the upper limit valve 1
17 and is returned to the tank 105. Therefore, when hydraulic oil flows through the flow passage gap 129, the resistance and the force required for bending work are balanced, and the die D stops at the upper limit position.

Therefore, the accuracy of the bending angle of the flat plate W depends on the accuracy of the upper limit positioning of the die D determined by the operation of the upper limit valve 117 described above.

[0007]

However, in such a conventional technique, when the die D reaches the set position, the pin 125 of the upper limit valve 117 is pushed, and the die D is supplied to the main cylinder 111 and the sub-cylinder 115. The operating oil returns to the tank 105 via the upper limit valve 117. Then, the die D stops when the flow path resistance in the flow path gap portion 129 in the upper limit valve 117 shown in FIG. 6 and the force required for bending work are balanced. Hydraulic cylinders 111, 1 depending on the bending length
There is a problem that the positioning accuracy of the die D changes depending on the flow path resistance value of the upper limit valve 117 and the setting value of the upper limit valve 117, which is very troublesome.

A positioning pin 125 of the upper limit valve 117 for determining the limit position is fixed to the main frame. For this reason, there is a problem that the frame is bent by the bending pressure, which affects accuracy.

SUMMARY OF THE INVENTION An object of the present invention is to pay attention to the above-described conventional technology, and to reduce the influence of a difference in bending length, a change in oil temperature, and a deformation of a frame to reduce the influence of a die or punch. An object of the present invention is to provide a press brake capable of improving the vertical positioning accuracy of a press brake.

[0010]

According to a first aspect of the present invention, there is provided a press brake, wherein a punch mounted on an upper table and a die mounted on a lower table are relatively moved by a hydraulic cylinder. A press brake for performing bending work in cooperation with each other by approaching / separating and supplying hydraulic oil to the hydraulic cylinder at the time of processing, and the hydraulic oil is supplied when a movable side of the punch and die reaches a predetermined limit position. A cut-off valve that stops the supply of oil and stops the flow of hydraulic oil in the hydraulic cylinder,
A first oil passage for supplying hydraulic oil from a pump, a second oil passage for supplying hydraulic oil to the cylinder, and a first oil passage and a second oil passage. , A valve member capable of shutting off the flow of hydraulic oil in the connection oil path, an urging member for normally urging the valve member to flow the hydraulic oil, and an urging member of the urging member. A pin attached to the valve member for moving the valve member against the force to cut off the flow of hydraulic oil, and the pin member provided on the opposite side of the pin to the valve member and approaching the limit position; And a cylinder that is operated by hydraulic oil when the connection oil passage is shut off, and is provided to reliably shut off the connection oil passage by the valve member.

Therefore, when the upper table on which the punch is attached and the lower table on which the die is attached are relatively approached / separated by a hydraulic cylinder to bend a flat plate by the cooperation of both, a cut-off valve is used. At the time of machining, hydraulic oil is supplied to the hydraulic cylinder, and when the movable side of the punch or die reaches a predetermined limit position, the valve member is moved by the pin against the urging force of the urging member, so the hydraulic oil is supplied. The valve member attempts to shut off the connecting oil passage between the first oil passage and the second oil passage that supplies hydraulic oil to the hydraulic cylinder and connects the two oil passages. At this time, hydraulic oil flows into the cylinder from the first oil passage narrowed by the valve member, moves the valve member, and reliably shuts off the connection oil passage.

The press brake of the invention according to claim 2 is
The press brake according to claim 1, wherein the cut-off valve is provided on one side of the lower table or the upper table, and a pin of the cut-off valve is turned when the lower table or the upper table reaches a limit position. A limit locating pin for pressing and shutting off hydraulic oil is provided on the other side of the lower table or the upper table.

Therefore, since the cut-off valve is provided on one of the lower table and the upper table and the limit positioning pin for determining the limit position of the lower table or the upper table is provided on the other, the lower table or the upper table is at the limit position. Once reached, the limit locating pin pushes the cutoff valve pin to stop the flow of hydraulic oil.

[0014] The press brake of the invention according to claim 3 is:
3. The press brake according to claim 1, further comprising a relief valve that returns the hydraulic oil directly to the tank when the cutoff valve shuts off the hydraulic oil.

Therefore, when the supply of hydraulic oil to the hydraulic cylinder is cut off by the cutoff valve, the hydraulic oil sent from the pump is returned directly to the tank by the action of the relief valve.

The press brake of the invention according to claim 4 is
In the press brake according to claim 2, when an excessive force acts on the limit positioning pin in a direction exceeding the limit, a safety device that detects the force and stops supply of the hydraulic oil is provided. It is a feature.

Therefore, if the cutoff valve does not operate normally due to clogging of dust and excessive force acts on the limit positioning pin, the excessive force is detected and the safety device is activated. And the supply of hydraulic oil is stopped.

The press brake of the invention according to claim 5 is
5. The press brake according to claim 2, wherein the limit positioning pin is fixed to a central portion on the other side of the lower table or the upper table via a rigid support member, and is vertically moved integrally with the other side. Moving.

Therefore, since the limit positioning pin is fixed to the center of the lower table or the upper table by the rigid support member, the limit positioning pin moves integrally with the lower table or the upper table, and when reaching the limit position, the cutoff valve. To shut off the hydraulic oil.

[0020]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 shows the whole of a press brake 1 of a fixed position flow cutoff type having an angle maintaining device structure according to the present invention. Since the structure of the main body of the press brake 1 is better known than before, a detailed description of the structure that is not different from that of the conventional press brake 1 will be omitted, and only the outline will be described.

That is, the press brake 1 has left and right side plates 3L, 3R having a C-shape.
Hydraulic cylinders 5L and 5R are provided at the lower front portions of the L and 3R, and a lower table 7 is provided on the hydraulic cylinders 5L and 5R so as to be able to move up and down. Also, the side plate 3L,
An upper table 9 is fixedly provided on the upper front surface of the 3R.

A die D is provided on the upper end of the lower table 7, and a punch P is mounted on the lower end of the upper table 9 via a number of intermediate plates 11 so as to face the die D. .

Accordingly, the lower table 7 is raised by the hydraulic cylinders 5L and 5R, and the flat plate W is bent by the cooperation of the punch P and the die D.

A bracket 13 is mounted on the right side of the lower table 7 in FIG.
A cut-off valve 17 in a hydraulic circuit 15 (see FIG. 2), which will be described in detail later, for operating the hydraulic cylinders 5L and 5R is attached to 3. Above the cutoff valve 17, a pin 19 is attached upward.

On the other hand, a bracket 18 is fixed to the center of the back surface of the upper table 9 so as not to be affected by the opening of the frame and the bending of the upper table 9 which occur at the time of bending. A support member 20 having high rigidity is provided integrally to the outside, and this support member 2
A limit positioning pin 21 for setting the upper limit position of the lower table 7 is attached to the leading end of the zero. The limit positioning pin 21 can be adjusted vertically by a handle 23.

Therefore, when the lower table 7 is raised, the pin 19 of the cutoff valve 17 is
The lower table 7 is pushed down and switches the operation of the cutoff valve 17 to stop the flow of hydraulic oil, stop the lower table 7 from rising, and stop at that position.

Next, based on FIG.
The hydraulic circuit 15 will be described. In this hydraulic circuit 15, the hydraulic oil pumped from the tank 27 by the pump 25 is first pressed into the main cylinder 33 constituting the hydraulic cylinders 5L, 5R from the distributor 31 via the cutoff valve 17 when the foot switch 29 is turned on. The die D is raised rapidly.

When the die D rises rapidly to a predetermined position,
Hydraulic oil is pressed into the sub-cylinder 37 by the action of the speed switching valve 35, and the die D rises slowly and strongly to perform the bending of the flat plate W. When the die D rises to the upper limit position where the bending is completed, the cutoff valve 1
The pin 19 provided on the upper table 9 contacts the limit positioning pin 21 for setting the upper limit position provided on the upper table 9 and is pushed downward.

Referring to FIG. 3, the cutoff valve 17
In this configuration, a first oil passage 39 connected to the pump 25 via the distributor 31 and a second oil passage 41 for sending hydraulic oil to the main cylinder 33 or the sub cylinder 37 are provided. , 41 are provided in the vertical direction.

A valve member 45 is provided above the connecting oil passage 43.
Is provided movably up and down, and a pin 1 is provided above the valve member 45 via a seal portion 47 which movably seals.
9 are provided integrally. A cylinder 50 is provided below the valve member 45 via a support member 49, and a spring 51 as an urging member is provided below the cylinder 50. It is biased upward.

Therefore, since the valve member 45 is normally moved upward by the spring 51, the first oil passage 39 and the second oil passage 41 are connected via the connecting oil passage 43, and the pump The hydraulic oil from 25 flows from the first oil passage 39 to the second oil passage 41 through the connecting oil passage 43, and is supplied to the hydraulic cylinders 5L and 5R.

When the lower table 7 is raised, the upper end of the pin 19 comes into contact with the limit positioning pin 21 of the upper table 9, and when the cutoff valve 17 is raised together with the lower table 7, the pin 19 moves relatively downward. When pushed down, the valve member 45 descends, closing the connecting oil passage 43 and stopping the flow of the hydraulic oil. At this time, when the connecting oil passage 43 is closed, the pressure of the first oil passage 41 increases, and pressure is applied to the cylinder 50 attached to the lower part of the pin 19,
Since the pin 19 is pushed down more strongly, the flow of the hydraulic oil is more reliably shut off.

The limit positioning pin 21 is mounted on the upper table 9 and can be positioned vertically by a gear mechanism 53 operated by a handle 23.
The limit position of the lower table 7 is set according to the processing.

Further, in order to avoid a danger that the cut-off valve 17 does not operate normally due to dust or the like being caught above the limit positioning pin 21 and the lower table 7 is raised too much. , A safety device 54 are provided. In this safety device 54, a dog 54A that allows a certain amount of upward force by an elastic member such as a spring is provided on the upper side of the limit positioning pin 21 so as to be vertically movable, and the upper end of the dog 54A exerts excessive force. A limit switch 54B is provided as a sensor for detecting.

Accordingly, the valve member 4 of the cutoff valve 17
5 does not work properly and pin 19 is the limit positioning pin 21
Is pushed up with excessive force, this limit positioning pin 21
Pushes up the dog 54A, turns on the limit switch 54B, and stops the supply of the hydraulic oil.

Referring again to FIG. 2, when the flow of the hydraulic oil is cut off by the cutoff valve 17, the pump 25
Due to the hydraulic oil sent from the tank, the hydraulic pressure for the relief valve 55 increases, and the hydraulic oil is directly returned to the tank 27 via the relief valve 55. A pressure sensor 57 is provided in front of the cutoff valve 17 to monitor the pressure of the hydraulic oil from the cutoff valve 17.

From the above results, the flow of the hydraulic oil supplied to the main cylinder 33 and the sub-cylinder 37 for raising the lower table 7 is mechanically directly controlled by the cut-off valve 1.
Since it shuts off at 7, there is no need to circulate the hydraulic oil to stop the lower table 7 as in the prior art, and to prevent a shift of the upper limit position of the lower table 7 due to a change in the oil temperature or viscosity of the hydraulic oil. And high-precision bending can be performed.

Further, since the cutoff valve 17 is directly operated, the response of the valve is quick and the lower table 7 can be stopped quickly, so that the safety of work can be improved.

Further, when performing bending work with different bending lengths, it is not necessary to change the limit position of the punch P or the die D by determining either the long or short bending angle, and to shorten the setup time. Efficiency can be improved.

If the cut-off valve 17 does not operate normally and the lower table 7 further rises, the safety device 54 operates to stop the supply of the hydraulic oil, so that the lower table 7 rises too much. Can be avoided and work safety can be ensured.

FIG. 4 shows a hydraulic circuit 59 of a press brake according to another embodiment. Note that portions common to the above-described embodiment are denoted by common reference numerals, and redundant description will be omitted.

In this hydraulic circuit 59, the hydraulic oil pumped up from the tank 27 by the pump 25 stops the flow of the hydraulic oil by the switching valve 61 when the foot switch 29 is depressed. To the main cylinder 33 to rapidly raise the die D. When the die D reaches a predetermined height, the switching oil is switched by the switching valve 63 to supply hydraulic oil to the sub-cylinder 37 and the second hydraulic cylinders 65 and 67 (two in FIG. 4). It is raised strongly and performs bending.

When the lower table 7 is raised, the pins 19 of the cutoff valve 17 abut against the limit positioning pins 21 of the upper table 9, and when the lower table 7 is further raised, the pins 19 are relatively pushed down and cut. The flow of the hydraulic oil is stopped by the off valve 17. Therefore, the hydraulic oil sent from the pump 25 is supplied to the relief valve 55
Through the main cylinder 3
3. The sub-cylinder 37, the second hydraulic cylinders 65 and 67, etc. stop, and the lower table 7 stops at that position.

Thus, an effect similar to that of the hydraulic circuit 59 described above can be obtained.

It should be noted that the present invention is not limited to the above-described embodiment of the present invention, but by making appropriate changes,
It can be implemented in other aspects. That is, in the above-described two embodiments, the press brake 1 in which the lower table 7 on which the die D is mounted is raised to perform the bending in cooperation with the punch P has been described. It can also be applied to press brakes that perform bending. In this case, it is necessary to adjust the position of the limit positioning pin 21 so that the lower limit position of the upper table 9 is set.

[0047]

As described above, in the press brake according to the first aspect of the present invention, the upper table on which the punch is mounted and the lower table on which the die is mounted are relatively moved toward and away from each other by the hydraulic cylinder, and the two are cooperated. When bending a flat plate by operation, the cut-off valve supplies hydraulic oil to the hydraulic cylinder at the time of processing, and when the movable side of the punch or die reaches a predetermined limit position, the urging force of the urging member is Move the valve member against
The valve member attempts to shut off a connection oil passage between the first oil passage through which the hydraulic oil is supplied and the second oil passage through which the hydraulic oil is supplied to the hydraulic cylinder and connecting the two oil passages. At this time, the operating oil flows into the cylinder from the first oil passage narrowed by the valve member, moves the valve member, and reliably shuts off the connection oil passage, so that it can be reliably stopped at the limit position, Not only can the bending accuracy be improved, but also the safety of the operation can be ensured.

In the press brake according to the second aspect of the present invention, the cut-off valve is provided on one of the lower table and the upper table, and the limit positioning pin for determining the limit position of the lower table or the upper table is provided on the other. When the table or upper table reaches the limit position, the limit locating pin pushes the pin of the cutoff valve to stop the flow of hydraulic oil, so it can be stopped at the desired position reliably and if only improving bending accuracy And work safety can be ensured.

In the press brake according to the third aspect of the invention, when the supply of the hydraulic oil to the hydraulic cylinder is cut off by the cutoff valve, the hydraulic oil sent from the pump by the action of the relief valve is directly returned to the tank. But,
Since the operation time of the relief valve is short, which is the final step of the bending, it is possible to prevent the temperature of the hydraulic oil from rising.

In the press brake according to the fourth aspect of the present invention, if excessive force acts on the limit positioning pin in the event that the cut-off valve does not operate normally due to clogging of dust, the excessive force is applied. Is detected and the safety device operates,
Since the supply of the hydraulic oil is stopped, the safety of work can be ensured.

In the press brake according to the fifth aspect of the present invention, since the positioning pins are fixed to the center of the lower table or the upper table by the rigid support member, they move integrally with the center of the lower table or the upper table. . As a result, when the center reaches the limit position, the hydraulic oil is shut off by the cut-off valve, so that the cut-off valve is not affected by the opening of the frame and the bending of the table generated at the time of processing, and the cut-off valve is controlled by the limit position at the bending position. Can be operated, and highly accurate bending can be performed. Further, if the plate thickness is the same, the pressing force is different between the long bending and the short bending. However, since the place where the limit position is detected is the center part used for the normal processing, the constant bending processing can be performed.

[Brief description of the drawings]

FIG. 1 is a front view showing an entire press brake according to the present invention.

FIG. 2 is a circuit diagram showing a hydraulic circuit of a press brake according to the present invention.

FIG. 3 is an enlarged sectional view of a cutoff valve.

FIG. 4 is a hydraulic circuit diagram in another embodiment.

FIG. 5 is a hydraulic circuit diagram of a conventional press brake.

FIG. 6 is a conventional upper limit valve.

[Description of Signs] 1 press brake 5 hydraulic cylinder 7 lower table 9 upper table 17 cut-off valve 19 pin 21 limit positioning pin 25 pump 27 tank 39 first oil path 41 second oil path 43 connecting oil path 45 valve member 50 Cylinder 51 Spring (biasing member) 54 Safety device P Punch D Die

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E063 AA01 BA07 FA02 FA06 FA09 4E089 EA01 EB01 EC02 ED03 EE04 EE05 FA01 FB01 FC03

Claims (5)

[Claims] 1. A press brake for performing a bending process by cooperatively moving a punch mounted on an upper table and a die mounted on a lower table relatively close to and away from each other by a hydraulic cylinder. A cut-off valve for supplying hydraulic oil to the punch and the die and stopping the supply of the hydraulic oil when the movable side of the punch and the die reaches a predetermined limit position and stopping the flow of the hydraulic oil in the hydraulic cylinder. The cut-off valve is
A first oil path to which hydraulic oil is supplied from a pump, a second oil path to supply hydraulic oil to the cylinder, a connection oil path to connect the first oil path and the second oil path, A valve member capable of shutting off the flow of hydraulic oil in the connecting oil passage, an urging member for urging the valve member to always flow the hydraulic oil, and the valve member against the urging force of the urging member A pin attached to the valve member to move the hydraulic fluid to shut off the flow of hydraulic oil,
The valve member is provided on a side opposite to the pin and is operated by hydraulic oil flowing into the connection oil passage blocked by the valve member at the limit position and provided to surely block the connection oil passage by the valve member. And a pressurized cylinder. 2. The cutoff valve is provided on one side of the lower table or the upper table, and when the lower table or the upper table reaches a limit position, a pin of the cutoff valve is pressed to shut off hydraulic oil. 2. A limit positioning pin, which is provided, is provided on the other side of the lower table or the upper table.
Press brake as described. 3. The press brake according to claim 1, further comprising a relief valve that returns the hydraulic oil directly to the tank when the cutoff valve shuts off the hydraulic oil. 4. A safety device which detects an excessive force acting on the limit positioning pin in a direction exceeding the limit and detects the force to stop supply of hydraulic oil. Item 2. The press brake according to item 2. 5. The apparatus according to claim 1, wherein the limit positioning pin is fixed to a movable side central portion of the lower table or the upper table via a rigid support member, and moves up and down integrally with the movable side. The press brake according to claim 2.