JPH05138253A - Press brake - Google Patents

Abstract

PURPOSE:To carry out a high-precision bending by preparing a press brake driving a ram vertically by a vertically driving mechanism provided on the lower part of a side frame of a press body. CONSTITUTION:This device is a press brake to bend a plate work 20 between an upper die 18 mounted on a ram 5 which moves freely vertically and a lower die 19 fixed on a table 1c of a press body 1. A vertically driving mechanism 4 is provided on the lower part of the side frame 1b of this press body 1 and the ram 5 is moved vertically by this vertically driving mechanism. Further, the vertically driving mechanism 4 consists of a guide member moved vertically by a ball screw rotated by a servo motor 14 and a bracket to set both ends of the ram 5 to this guide member. High-precision bending without dispersion in bending angles of right and left ends can be conducted and the life of the ball screw is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a press brake with improved processing accuracy.

[0002]

2. Description of the Related Art Conventionally, press brakes of this type have been disclosed in, for example, JP-A-63-157722 and JP-A-63-29.
The one described in Japanese Patent No. 0623 is known. In each case, the relationship between the bending load and the bending amount of the frame is input to the control device for controlling the vertical movement of the ram,
During processing, the actual bending load is detected by the pressing force detection means, and if there is an error, the ram position is corrected accordingly.Therefore, even if the frame etc. bends due to bending load, proper bending is always performed. It is designed so that an angled product can be obtained.

[0003]

However, in the above-mentioned conventional press brake, when the data measured in advance is input to the control device as a correction value and an error occurs between the value measured during the actual bending and the correction value, the correction value is generated. Due to the expected control to compensate based on the above, if one side frame thermally expands due to the heat generated by the control panel attached to the side frame during processing, the ram tilts left and right due to the difference in expansion between the left and right side frames. Since the bending process is performed, the bending angle of the bent product will vary and a highly accurate product cannot be obtained, and an unbalanced load acts on the ball screw that moves the ram up and down. There were some problems such as early wear of the screw. The present invention has been made for the purpose of improving the above conventional problems, and an object of the present invention is to provide a press brake capable of highly accurate bending without being affected by thermal expansion of a side frame or the like.

[0004]

In order to achieve the above object, the present invention has a plate-like structure between an upper die mounted on a vertically movable ram and a lower die fixed on a table of a press body. In a press brake for bending a work, a vertical drive mechanism is provided below a side frame of the press body, and the vertical drive mechanism is used to vertically move the ram.

[0005]

[Operation] With the above configuration, the side frame does not bend due to a bending load, and even if the side frame expands or contracts due to thermal expansion, these effects are not affected, so that it is possible to perform highly accurate bending.

[0006]

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view of a press brake, and FIG. 2 is a side view of the press brake. In these figures, 1 is a press body, 2 is an operation panel, and 3 is a backstop. The press body 1
Is a structure in which box-shaped side frames 1b are arranged on both ends of the bed 1a, and a ram 5 which is vertically moved by a vertical drive mechanism 4 installed below the side frame 1b is provided above the bed 1a. ..

Both ends of the ram 5 have side frames 1b.
The upper part of the bracket 6 which is projected inside and is provided inside the side frame 1b is fixed to both ends of the ram 5. As shown in FIGS. 2 and 3, the bracket 6 is formed in a substantially U shape with the lower side open, and the upper side 6a is formed.
Is fixed to the front and rear surfaces of the ram 5 by a fixing tool 7, and the lower end is fixed to the upper surface of the guide member 8 by a fixing tool 9. The guide member 8 is also substantially U-shaped with its lower side open, and both side portions 8a are supported by guide posts 10 arranged in front of and behind the press body 1 so as to be vertically movable as shown in FIG.

A nut 13 screwed onto the ball screw 12 of the vertical drive mechanism 4 is fixed to the upper side 8b of the guide member 8. The vertical drive mechanism 4 is installed in the lower portion of each side frame 1b and has the ball screw 12 supported in the side frame 1b by a bearing 11. The lower end of the ball screw 12 has a servo motor 14 installed behind the side frame 1b and a power transmission means 15 such as a timing belt.
When the ball screw 12 is rotated by the servo motor 14 through the power transmission means 15 in a left-right synchronized manner, the guide member 8 is vertically moved along the guide post 10. Thus, the ram 5 attached to the guide member 8 via the bracket 6 also moves up and down.

On the other hand, an upper die 18 is attached to the lower portion of the ram 5, and a plate-like shape is provided between the upper die 18 and a lower die 19 fixed on a table 1c provided on the upper portion of the bed 1a. The work 20 can be bent. Reference numeral 21 in the figure is a position detector, which is an endless timing belt 2
2 has an absolute encoder 23 connected to it. The position detectors 21 are provided at both ends of the ram 5, respectively, and are picked up by the pickup 24 fixed to the ram 5.
The timing belt 22 is connected to both ends of the ram 5 via the timing belt 23 as the ram 5 moves up and down.
Is rotated, the absolute encoder 23
Thus, the positions of both ends of the ram 5 are detected. The position data of both ends of the ram 5 detected by the position detector 21 is fed back to the control device 25 that controls the vertical movement of the ram 5. Incidentally, reference numeral 26 in the figure is a brake device, which is adapted to prevent the ram 5 from dropping spontaneously by braking the ball screw 12.

The operation will now be described. When data such as the size of the work 20 to be bent is input to the control device in advance, the backstop 3 is moved based on this data and stopped at a predetermined position. Therefore, first, the bending position is positioned by abutting the tip of the work 20 against the back stop 3. Next, when bending is started in this state, the left and right servo motors 14 rotate in synchronization with each other, and the ball screw 12 is rotated via the timing belt 15. As a result, the guide member 8 in the side frame 1b is lowered along the guide post 10 and the guide member 8
The ram 5 attached to the ram 5 via the bracket 6 is also lowered to start bending the work 20 between the upper die 18 attached to the ram 5 and the lower die 19 fixed on the table 1c. The lowered positions of the left and right ends of the ram 5 are detected by the position detector 21 and fed back to the control device 25. Then, the target value input in advance and the position data input from the position detector 21 are compared, and when the position data reaches the target value, the descent of the ram 5 is stopped. After that, the ball screw 12 is reversed by the servo motor 14 to raise the ram 5 to the top dead center, and the bending work is finished. Although the absolute encoder 23 is used as the position detector 21 in the above embodiment, a linear encoder or other position detecting means may be used.

[0011]

As described in detail above, according to the present invention, the vertical drive mechanism is installed under the side frame of the press main body,
Since the ram is moved up and down by these vertical drive mechanisms, the positional accuracy of the ram affects the amount of bending of the side frame due to bending load, etc., compared to the conventional side frame with the vertical drive mechanism installed above. Never be done. As a result, it is not necessary to perform control such as correction of the ram position by detecting the deflection of the side frame that occurs during bending from the bending load as in the past, so simplification of the control system and the accompanying The price can be reduced. In addition, even if the side frame expands and contracts due to thermal expansion, it does not affect the ram's position accuracy, so it is possible to perform high-precision bending with no variation in the bending angles of the left and right ends, and to move the ram up and down. Since the eccentric load due to the inclination of the ram is not applied to the ball screw of the mechanism, the life of the ball screw can be improved. Moreover, since the heavy vertical drive mechanism is located below the side frame, the machine itself can be stabilized.

[Brief description of drawings]

FIG. 1 is a front view of a press brake according to an embodiment of the present invention.

FIG. 2 is a side view of a press brake according to an embodiment of the present invention.

FIG. 3 is a detailed view of the vertical drive mechanism of the press brake according to the embodiment of the present invention.

FIG. 4 is a detailed view of the vertical drive mechanism of the press brake according to the embodiment of the present invention.

[Explanation of symbols]

1 ... Press body, 1b ... Side frame, 1c ... Table, 4 ... Vertical drive mechanism, 5 ... Ram, 18 ... Upper mold, 19 ...
Lower mold, 20 ... Work.

Claims (3)

[Claims] 1. A press brake for bending a plate-shaped work 20 between an upper die 18 attached to a vertically movable ram 5 and a lower die 19 fixed on a table 1c of a press body 1, Side frame 1 of the press body 1
A press brake in which a vertical drive mechanism 4 is provided in the lower part of b, and the ram 5 is vertically moved by the vertical drive mechanism 4. 2. The vertical drive mechanism 4 comprises a guide member 8 vertically moved by a ball screw 12 rotated by a servo motor 14, and a bracket 6 for mounting both ends of the ram 5 on the guide member 8. The press brake described in 1. 3. The press brake according to claim 1, further comprising position detectors 21 for detecting the positions of both ends of the ram 5, and controlling the position of the ram 5 according to the position signals detected by these position detectors 21. ..