JPH0635015B2 - Bending follow method and its device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a bending follow-up method for supporting a work outwardly projecting portion when bending a sheet-like work in a press brake, for example, and a device therefor.

[Prior Art] A conventional bending follow-up method is that a tip of a piston rod of a follow-up cylinder is pin-connected to a follow-up lever that supports an outwardly protruding portion of a sheet-like work (hereinafter simply referred to as a work) placed on a lower die. When the work is bent by lowering the upper die, the follow-up cylinder is driven to rotate the follow-up lever upward.

However, the work rotates about the lower die outer edge (V bending shoulder) as it bends, but the rotation center of the follower lever directly changes to V.
Since it is not provided on the bending shoulder, there is a gap in both centers.
Also, in order to prevent scratches on the surface of the work as much as possible by rubbing against the follower lever, the conventional follower cylinder is provided with an inclination, so that the work rotation angular velocity when the upper die descends at a constant speed and the follower lever. The device is designed to match the rotation speed of the.

[Problems to be Solved by the Invention] FIG. 4 is a diagram showing the relationship between the movement of the upper die and the work.
When the upper die 8 descends and bends the work 100 between the lower die 9 and the lower die 9, the lower limit of the upper die 8 is adjusted by NC control and the work is touched at the point D, and the point E in the V groove is further adjusted. , F, G, the work 100 rotates about the lower die outer edge (V bending shoulder) K as the center of rotation. If the work center d is e,
When moving to f and g, bending of 90 °, 60 ° and 30 ° is performed, and the work jumps up. The follower lever 81 is rotated via the follower cylinder 90, the piston rod 91 and a parallel link (not shown). The rebounding (up) motion is generally designed so that the cylinder 90 is set on the follower lever 91 and the locus of the arc defg is taken, but since it does not synchronize with the movement of the ram, it does not depend on this locus. The inside of the work center d (the lower V-bending shoulder K that is the center of rotation)
Vertical line D'-E'-F'-G 'at point D'
Need to consider the movement of.

The requirement for perfect follow-up is that, when the tip of the upper die 8 moves from D to E as described above, the point E'-F'-G 'on the vertical position set at the point D'inside the center d of the work 100 stands. The follower lever as follows, that is, the follower lever at the ratio of KD / KD '
It is necessary to rotate 91 up. In the conventional follow-up method, the work is made to follow to the extent that the work does not bend at the K point, and the lowering speed of the upper die 8 is slowed down to substantially match the rising speed of the follow-up lever. However, in the normal case,
There is a difference of KD '/ KD = 150 mm / 5 mm = 30 times, and when the work is 1 mm thick, the V width of the lower die 9 is 6 mm, so 1
Since it reaches 50/3 = 50 times, it is difficult to synchronize the movement of the follow-up lever with the descending speed of the upper mold 8, and therefore, a method of following completely cannot be realized.

Further, when the work is bent at a predetermined angle by V, lower dies having different V-groove widths (V widths) are selected depending on the work plate thickness. Position changes, even if the bending angle is the same, the descending distance (bending depth) of the upper die tip into the lower die V groove is different. The distance to the V-bend shoulder) also changes. Since the conventional bending follow-up system cannot cope with these variations, it is difficult to accurately follow and rotate the follower lever each time the plate thickness is changed.

It is an object of the present invention to provide a method and apparatus for completely following the upper die by controlling the lowering of the upper die by the movement of the following lever.

[Means for Solving the Problems] In order to achieve the above object, according to the present invention, after the bending depth in the lower die V groove is set according to the work plate thickness, the lower V width, and the bending angle. In the method of supporting the sheet-like work which descends the upper mold and jumps outward by the follower lever, and controls the descending speed of the upper mold while limiting the descending speed of the follower lever to perform V-bending, the sheet is placed on the lower mold. After touching the tip of the upper die on the work surface, the upward movement of the follower lever that rotates around the V-bending shoulder is converted into the rotation of the adjustment shaft behind the ram, and the main cylinder moves according to the rotation of the adjustment shaft. It is characterized in that the control valve for adjusting the descending speed of the upper die is opened to control the descending speed of the upper die in the lower V groove.

The control valve is opened by the upward rotation of the follower lever, and the upper mold lowering speed is controlled by following the opening speed of the control valve.

Further, a folding follower, which is a related invention of the present invention, is a device for bending a sheet-like work by an upper die on the lower end of a ram and a lower die placed on a bed; with the V-groove shoulder of the lower die as the center of rotation. A follow-up lever that rotates upward; an adjusting shaft that is laid horizontally behind the ram; an adjusting lever that is supported by the adjusting shaft through an eccentric; and a ram that is installed in the hydraulic circuit of the main cylinder for raising and lowering the ram. A control valve that is closed by abutting the operating rod provided on the control lever against the adjustment lever and that is opened by relative lowering of the adjustment lever when the adjustment shaft rotates; A follow-up interlocking mechanism that converts upward movement into rotation of the adjustment shaft; Corresponds to the plate thickness that adjusts the angular rotation start position of the eccentric disc in the adjustment lever according to the work touch height of the upper die tip in the initial stage of bending Means and; depending on the thickness of the sheet-like work Means for adjusting the turning angle of the eccentric disc depending on the V-bending shoulder position of the lower die selected; and the V-bending by regulating the turning angle end of the eccentric disc of the adjusting lever according to the designation of the bending angle. Bending depth setting means for determining the lowering limit of the tip of the upper die in the lower V groove at the time.

The follow-up interlocking mechanism includes a rack bar extending in a direction orthogonal to the lower die, a pinion fixed to a support shaft of the follower lever and engaged with a front portion of the rack bar, an arm provided at an end of the adjustment shaft, and an arm. An angular axis that oscillates freely, a gear that is fixed to one end of a horizontal axis that is arranged in a direction orthogonal to the angular axis and that meshes with the rear portion of the rack bar, and that is fixed to the other end of the horizontal axis. It is composed of a horizontal frame connected to the middle part of the angular axis via a slider.

[Operation] The rising speed of the follower lever is mechanically taken out and converted into the rotation of the adjustment shaft, and the control valve is opened according to the rotation of the adjustment shaft to open the lower mold V.
Controls the lowering speed of the upper die in the groove. The ascending speed of the follower and the descending speed of the ram are perfectly synchronized with each other to allow accurate V-bending.

EXAMPLES Next, the present invention will be specifically described with reference to the drawings.

FIG. 1 shows the principle of the present invention, in which 1 is a hydraulic pump, 2 is an oil passage, 3 is an oil tank, 4 is a relief valve,
Reference numeral 5 is a frame of the folding machine, 6 is a main cylinder, 7 is a ram driven up and down by the main cylinder 6, 8 is an upper die attached to the lower end of the ram 7, 9 is a lower die placed on the bed 11, 1
Reference numeral 0 is a V groove of the lower mold 9.

A control valve 16 is attached to the beam 15 provided at the rear of the ram, while a bracket 21 is used at the tip of the beam 15 to rotatably support an adjustment shaft 20 having an eccentric disc 19 inserted therethrough. The adjustment shaft 20 is inserted in the eccentric position of the eccentric disc 19 in parallel with the beam longitudinal direction, and the adjustment lever 1 is attached to the outer periphery of the eccentric disc 19.
Support 8. The upper surface of the right side of the adjusting lever 18 faces the lower end of the plunger 17 of the control valve 16, and the upper surface of the left side faces the adjusting screw rod (operating rod) 13 screwed into the bracket 12 of the ram rear wall.

In the above apparatus, in order to bend the work 100 by the upper die 8 and the lower die 9, the oil from the pump 1 is sent to the main cylinder 6 via the lower limit valve 16 to pressurize the ram 7. When the pressure of the ram is lowered, the operating rod 13 with the adjusting screw attached to the bracket 12 is also lowered at the same time, and the tip of the rod 13 pushes down the left side action surface of the adjusting lever 18, so that the adjusting lever 18 is moved as shown by the arrow in FIG. Rotate counterclockwise. By this rotation, the right side action surface of the adjusting lever 18 touches the lower end of the plunger 17, and the plunger 17 is raised by continuing the rotation, so that the control valve 16 is closed and the lowering of the ram 7 is stopped.

The effective length of the operating rod 13 is such that the control valve 16 closes and stops when the tip of the upper die 8 and the upper surface of the lower die 9 have almost the same height (level A'in FIG. 1). It should be adjusted to the desired length. After adjusting in this way, the plate thickness corresponding means 30 in the controller 14, which will be described later, is activated to rotate the adjusting shaft 20 counterclockwise by an amount corresponding to the work plate thickness (t = A′−B ′). Since it is integrated with the eccentric disc 19, the adjustment lever 18 is raised to the position B. When the ram 7 is lowered in this state, the tip of the upper die 9 stops when the work is pressed. After that, if the adjusting shaft 20 is interlocked with the follow-up lever by the controller 14 and the adjusting shaft 20 is rotated clockwise to the lower limit setting position, the lever 18 moves to the position B.
To C, and the tip of the upper mold is lowered from B'to C '.

As described above, since the control valve 16 is opened and closed by changing the height position of the adjusting shaft 20 in conjunction with the rotation of the follow-up lever, the flip-up rotation of the work due to the lower limit of the ram and the movement of the follow-up lever are completed. Can be tuned to.

Based on the above-mentioned principle, the second embodiment of the implementation device is configured as a whole.
Shown in the figure. The figure shows only the vicinity of one corner of the ram. In the case of a press brake, the main cylinder 6 and the control valve 1 are shown.
6, the operating rod 13 with an adjusting screw, and the adjusting lever 18 are provided at symmetrical positions, but the other corner portion is omitted in the drawing.

The adjustment shaft 2 is provided between the adjustment shaft 20 and the follower lever 81.
The control valve 1 is changed by changing the eccentric position of the eccentric disc 19 with the rotation of 0.
A follow-up controller 14 for adjusting the flow rate of 6 is incorporated. The controller 14 adjusts the angular rotation starting position of the eccentric disc 19 in the adjusting lever in accordance with the work touch height of the tip of the upper die in the initial stage of bending; Means 50 for adjusting the turning angle of the eccentric disc 19 according to the V-bending shoulder position of the lower die selected by; and regulating the turning angle end of the eccentric disc 19 in the adjusting lever according to the designation of the bending angle. And a bending depth setting means 25 that determines the lower limit of the lower end of the upper die in the V groove of the lower die during V bending.

Next, each of these parts will be described.

As with the adjustment lever 18 shown in FIG. 1, an eccentric disc 19 is rotatably fitted in the lever center, and an adjustment shaft 20 is passed through the eccentric disc 19 at the eccentric position. One working surface of the lever 18 faces the operating rod 13, and the other working surface of the lever 18 faces the plunger 17 of the control valve 16. Control valve 16
A lower limit switch LS1 for detecting the contact with the lever and switching the switching valve 22 is attached to the lower part of the switch.

<Bending Depth Setting Means> This means 25 regulates the turning angle end of the eccentric disc in the bar to determine the lowering limit of the tip of the upper die in the V groove of the lower die during V bending. That is, the dog 26 fixed to the adjustment shaft 20, the screw rod 28 that determines the rotation end of the NC motor 27 and the dog 26, the converter 29 that converts the rotation of the NC motor 27 into the advance / retreat of the screw rod 28, and the lever It is composed of a second limit switch LS2 for detecting the rotation end. The bending angle is determined by the V width selected by the work plate thickness and the bending depth (falling depth from the upper surface of the upper die into the V groove). When the bending depth is small, the clockwise rotation of the dog 26 is minimized as shown by the arrow in FIG. 2, and when the bending depth is large, the screw rod 28 is retracted to retract the dog 26. Increase the rotation angle of.

<Plate Thickness Corresponding Means> This means 30 adjusts the angular rotation starting position of the eccentric disc in the adjusting lever according to the work touch height of the tip of the upper die in the initial stage of bending, and the bending angle is the same. In the case of, the adjustment shaft 20 is slightly rotated right when the plate thickness is small, and the bending depth is shallow when the plate thickness is large, that is, the adjustment shaft 20 is rotated counterclockwise.

The plate thickness handling means 30 includes an arm 31 fixed to the adjustment shaft 20, a pin 32 and a yoke 33 in the middle of the arm 31.
Left and right reverse screw screw rod 34 erected using
The screw rod expansion / contraction NC motor 35 and an angular shaft 38 vertically provided at the lower end of the screw rod 34 are the main parts.

A worm wheel 37 provided at the center of the screw rod 34 and fixed to the output shaft of the NC motor 35
It is engaged. The lower part of the angular axis 38 has a pin 32
The slider 43 and the pair of rollers 4 that can move in the direction orthogonal to the angular axis 38 so as to be able to swing and move up and down.
It is supported by 4,44. A vertical groove 39 is provided in the center of the square shaft 38, and a horizontal frame 65, which is a part of the structure of a follow-up interlocking mechanism described later, is inserted into the vertical groove 39, and a slider 41 inside the horizontal frame 65 is fixed with a pin 40. ing. An air cylinder 47, which operates according to the bending angle, is hung on the tip of the arm 31 using a pin 45 and a yoke 46, and the lower end of the cylinder 47 is pinned to a bracket 49 protruding from a fixing member 48. . This air cylinder 47 is
At the time of bending at ゜, return the arm 31 to the original position in advance,
When bending at 60 ° and 90 °, make arm 31 free.
It acts so as not to restrain the rotation of the.

<Eccentric Disc Rotation Angle Adjustment Means> This means 50 is for adjusting the eccentric disc rotation angle according to the V-shaped bending shoulder position of the lower die determined by the plate thickness and the bending angle of the sheet-like work. is there. That is, the position of the pair of rollers 44, 44 supporting the lower portion of the square shaft 38 is moved in the horizontal direction by the V width of the lower die 9 selected by the work plate thickness, and the driven gear of the interlocking means 60 described later is moved. The distance 1 between the center and the bin 40 of the angular axis is determined. When this distance 1 is determined, the vertical movement distance of the square shaft 38 at the time of bending, that is, the rotation angle of the arm 31 is restricted.

The means 50 includes a motor 51, a gear 52 fixed to a motor output shaft, a screw 53 screwed to a slider 43 arranged in a lower portion of the angular shaft 38 in an orthogonal direction, and a screw 5.
3 and a gear 54 which is wedged and meshes with the gear 52. By rotating the motor 51 in the forward or reverse direction, the guide 4 is moved through the gear and the screw.
The slider 43 supported by 2 is moved to the left and right.

<Following lever mechanism> A following lever mechanism 80 including several levers that rotate synchronously is attached to the front part of the folding machine. FIG. 2 shows the follower lever mechanism on the right side when viewed from the front of the machine,
Similar mechanisms arranged in the center and on the left side are not shown.

The mechanism 80 includes a bracket 71 fixed to the front surface of the front plate 70 of the folding machine, a pantograph supported by the bracket 71, and a follow-up cylinder 90 that drives the paragraph. The bracket 71 is fixed to the front plate 70 using several bolts 72, and has vertical support shafts 86 and 87. The vantagraph includes a follow-up lever 81, vertical links 82 and 83 pinned to the lower part of the follow-up lever 81, a drive link 84 supported by the first support shaft 86, and a second link.
It is made with a link 85 supported by a support shaft 87. The lower part of the follow-up cylinder 90 is pin-supported by a bracket 73 fixed to the front plate 70, and the yoke 92 at the tip of the pston rod 91 is pinned to the driving link 84.
When the follow-up cylinder 90 is driven, the follow-up lever 81 in the pantograph rotates about the V-bending angle of the lower die 9 at a desired angle and follows the work-bending angle. In addition,
A pinion 62 of a follow-up interlocking device 60 is fixed to the side of the first support shaft 86 opposite to the link mounting portion.

<Following interlocking mechanism> The follower interlocking mechanism 60 controls the movement of the follower lever 81 to the angular axis 38.
The vertical movement of the control valve 16 is changed to the vertical movement of the control valve 16 through the arm 31, the adjustment shaft 20, the eccentric disc 19 and the adjustment lever 18.

The follow-up interlocking mechanism 60 includes a rack bar 61 extending in a direction orthogonal to the lower mold, a pinion 62 fixed to a support shaft 86 of a follow-up lever 81 and engaged with a front portion of the rack bar,
The rack 31 is fixed to one end of an arm 31 provided at the end of the adjustment shaft 20, an angular shaft 38 swingably hung on the arm 31, and a horizontal shaft 63 arranged in a direction orthogonal to the angular shaft 38. The bar 61 includes a gear meshing with a rear portion of the bar 61, and a horizontal frame 65 fixed to the other end of the horizontal shaft 63 and connected to an intermediate portion of the angular shaft 38 via a slider 41.

The rack bar 61 is normally mounted on a guide 66 which is provided on the rear portion of the front plate so as to be floatable and retractable. The rack bar 61 is advanced in the direction of the arrow by the rotation of the pinion 62 when the follow-up cylinder 90 is extended, and the pinion is reversely rotated when it is reduced. To return to the original position. The horizontal frame 65 at the end of the horizontal shaft 63 is inserted into the vertical groove 39 of the square shaft 38, and the slider 41 is inserted into the long hole 67 provided in the horizontal frame 65 to support the slider 41. It is connected so that it can slide and rotate about 40.

At the rear end of the follow-up interlocking rack bar 61, a follow-up canceling unit 55 for canceling the engagement between the follow-up gear 64 and the rack bar 61 when the follow-up operation is unnecessary is attached. That is, the means 55 is configured to project the bar 56 at the rear end of the rack bar 61, and insert and support the yoke member 59 by using the pin 58 at the piston rod end of the cylinder 57 provided in the fixing member 48. When the follow-up is cancelled, the cylinder 57 is operated to extend the piston rod to push down the rack bar 61 and cut the engagement with the gear 64.

<Operation> Next, the operation of the apparatus shown in FIG. 2 will be described. First, the ram 7 is lowered without placing a work on the lower mold, and the level at which the tip of the upper mold coincides with the upper surface of the lower mold is set as the origin. Actuating rod with adjusting screw 1 when the ram 7 descends near the level
3 is operated to rotate the lever 18 counterclockwise. This rotation raises the plunger 17 of the control valve 16,
Close the circuit of the valve and stop the ram. The eccentric position of the eccentric disc 19 at this time is A (FIG. 1).

Next, the bending start position is set according to the work plate thickness. That is, the small motor 35 for control rotates the gear 37, and the screw rod 34 with left and right reverse screws is expanded and contracted to slightly rotate the arm 31 counterclockwise or clockwise. When the arm 31 is rotated counterclockwise, the eccentric disc 1
The position A of 9 becomes the position B and the center of rotation of the adjusting shaft 20 becomes higher, and when it is rotated clockwise, it moves to the position C and the center of rotation of the adjusting shaft 20 becomes lower (FIG. 1). The change in the vertical direction is set to the designated plate thickness t.

Furthermore, V of the lower die 9 determined by the work plate thickness and the bending angle
The position of the eccentric disc 19 is set according to the width.

When the horizontal frame 65 rotates during the operation of the follow-up interlocking mechanism 60,
The square shaft 38 moves up and down, but the lower part thereof is guided by the rollers 44, 44 and its lateral movement is restricted. This roller 44,
The angular shaft 38 is laterally moved by sliding the position of 44 to adjust the vertical movement stroke of the angular shaft 38, and the eccentric position is changed via the arm 31. That is, when the control small motor 51 rotates the gears 52 and 54, the slider 53 slides in the front-rear direction by the screw 53, and the two rollers 44 and 4 provided on the slider 43.
4, the angular axis 38 moves laterally, so the distance 1 between the lateral axis 63 and the pin 40 is increased or decreased. This movement is due to the fact that the follower shaft 86 and the horizontal frame 65 have the same rotation angle,
5 and the angular axis 38 have a distance of 1 by adjusting the gear 54.
By changing the value, the dimension (DE, DF, DG in FIG. 4) in which the upper tip enters into the V groove of the lower mold 9 in accordance with the rotation angle of the follower lever 81 in FIG. Can be set. The bending depth is set in advance by adjusting the clearance between the tip of the screw rod 28 and the dog 26 with the NC motor 27.

After adjusting the plate thickness, adjusting the eccentric disc turning angle and setting the bending depth as described above, the work 100 is placed on the lower die 9 and the follower lever 81, and the drive pedal (not shown) is pushed down to switch. By switching the valve 22, the ram 7 and the upper die 8 are lowered and touch the work. At this time the operating rod 1
3 pushes the lever 18, the rise of the plunger 17 cuts the circuit of the control valve 16 and the ram 7 stops.

At this time, the limit switch LS1 is turned on, the tracking cylinder 90 is actuated by the detection signal, and the tracking lever 81 starts to move up. At the same time, the cylinder 47 performs a return operation to rotate the arm 31 clockwise in FIG. Since the center of the lever 18 moves from the position A to the position C by the rotation of the arm 31, the circuit of the lower limit setting valve 16 is opened, the ram 7 is driven, and the upper die 8 continues to descend to continue bending. This movement follows the relationship shown in FIG. 1 by the lateral frame 65, the angular axis 38, and the slider 41, and becomes a perfectly synchronized operation.

Since the arm 81 is rotated, the operating speed v of the cylinder 47 is faster than the ascending speed V of the following cylinder 90 (V <
v), the bending speed extending from the position A to the position C is lowered while being limited by the follow-up shaft 86 that meshes with the rack bar 61. Final lower limit of upper die 8 (bending angle)
The dog 26 hits the tip of the screw rod 28, the control valve 16 closes, and the ram stops. At the same time, the limit switch LS2 also stops the following cylinder 90 at the upper limit. Then, the ram 7 is raised by the switching of the switching valve 22, and the following cylinder 90 also returns.

When the follow-up operation is not performed, the cylinder 57 is operated and the rack bar 61 is pushed down to release the engagement between the pinion 64 and the rack bar 61 and cut the synchronization.

Although the dog 26 and the arm 31 are separate bodies in the illustrated example, they may be integrated as a crank lever type.
Further, the means for adjusting the plate thickness, adjusting the eccentric rotation, and setting the bending depth are not limited to those shown in the drawings. Further, the tip end of the follow-up lever 81 may be directly supported on both outer ends of the lower mold. In that case, as shown in FIG. 3, the support shafts 75 are attached to both ends of the lower mold at a position corresponding to the rotation center K point of the follower lever, and the pinion 89 fixed to the arm 88 extended forward of the follower lever 81. Is supported by the support shaft 75, and the pinion 89 is directly rotated by the movement of the follower lever 81 to move the rack bar 6
It is possible to operate the follow-up interlocking mechanism of 1 or less more accurately.

[Effects of the Invention] As described above, according to the present invention, the ascending speed of the follow-up lever is mechanically taken out and converted into the rotation of the adjustment shaft without using the electrical control method, and the rotation speed of the adjustment shaft is changed. By opening the control valve and controlling the lowering speed of the upper die in the lower die V groove,
Accurate V-bending can be achieved by perfectly synchronizing the ascending speed of the follower and the descending speed of the ram.

[Brief description of drawings]

FIG. 1 is a principle view of the method of the present invention, FIG. 2 is a perspective view showing an outline of an apparatus for carrying out the present invention, FIG. 3 is a partial side view showing a modification of a follower lever, and FIG. It is explanatory drawing which shows the workpiece | work and the movement of a following lever at the time. 1 ... hydraulic pump, 2 ... oil passage, 6 ... main cylinder, 7
...... Ram, 8 ...... Upper mold, 9 ...... Lower mold, 13 ...... Operating rod with adjusting screw, 14 ...... Controller, 16 ...... Control valve,
17 ... Plunger, 18 ... Adjusting lever, 19 ... Eccentric disc, 20 ... Adjusting shaft, 22 ... Switching valve, 25 ...
Bending depth setting means, 26 ... Dog, 30 ... Plate thickness coping means, 31 ... Arm, 34 ... Left / right reverse screw type screw rod, 38 ... Square shaft, 43 ... Slider, 44 ...
... Roller, 47 ... Air cylinder, 50 ... Eccentric disc rotation adjusting means, 51 ... Motor, 55 ... Follow-up canceling means, 57 ... Cylinder, 60 ... Follow-up interlocking mechanism, 61 ...
… Rack bar, 62… Pinion, 63… Horizontal axis, 64
...... Gear, 70 …… Front plate, 80 …… Following lever mechanism, 8
1 ... Following lever, 90 ... Following cylinder, 100 ...
work.

Claims (4)

[Claims] 1. A sheet-like work which descends from an upper mold and jumps outward after setting a bending depth in a lower V groove according to a work plate thickness, a lower V width and a bending angle. In the method of V-bending supported by the follower lever and controlling the descending speed of the upper die while being limited to the ascending speed of the follower lever, touch the upper die tip to the upper surface of the work placed on the lower die, and then bend the V-shoulder shoulder. The upward movement of the follower lever that rotates around the center is converted into the rotation of the adjustment shaft behind the ram, and the lower valve V groove is opened by opening the control valve that adjusts the lowering speed of the main cylinder according to the rotation of the adjustment shaft. Bending follow-up method characterized by controlling the lowering speed of the upper die in the chamber. 2. The bending follow-up method according to claim 1, wherein the control valve is opened by upward movement of the follow-up lever, and the lowering speed of the upper die is controlled by following the speed of the control valve. 3. An apparatus for bending a sheet-like work by an upper die on a lower end of a ram and a lower die placed on a bed, wherein: a, a follower lever for ascending rotation about a V groove bending shoulder of the lower die as a center of rotation; The adjustment shaft that is laid behind it, c the adjustment lever that is supported by the adjustment shaft through the eccentric disc, and d that adjusts the operating rod that is installed in the hydraulic circuit of the main cylinder for raising and lowering the ram. A control valve that is closed by abutting against the lever and that is opened by relative lowering of the adjustment lever accompanying the rotation of the adjustment shaft, e A follow-up interlocking mechanism that converts the upward movement of the follower lever into rotation of the adjustment shaft, and f-folding. According to the work touch height of the tip of the upper die in the initial stage of bending, the plate thickness corresponding means for adjusting the angular rotation starting position of the eccentric disc in the adjusting lever, and the lower die selected by the plate thickness of the g-sheet work. The angle of rotation of the eccentric disc depends on the V-bending shoulder position. Folding means for adjusting and adjusting the turning angle end of the eccentric disc in the adjusting lever according to the designation of the bending angle to determine the lowering limit of the upper die tip in the lower die V groove during V bending. A bending follow-up device comprising: a bending depth setting means. 4. The follow-up interlocking mechanism is provided at a rack bar extending in a direction orthogonal to the lower die, a pinion fixed to a support shaft of the follow-up lever and engaged with a front portion of the rack bar, and an adjustment shaft end. An arm, an angular axis swingably hung on the arm, a gear fixed to an end of a horizontal axis arranged in a direction orthogonal to the angular axis and engaged with a rear portion of the rack bar, and the other end of the horizontal axis. The bending follow-up device according to claim 3, wherein the bending follower is fixed to the frame and is connected to a middle portion of the angular axis via a slider.