Material Support Apparatus For A Press Brake System

Abstract

This invention provides a workpiece supporting apparatus for a press brake or bending press of the type in which the punch or upper die is stationary and the lower die is movable upwardly towards said punch, said apparatus being so designed and constructed that the workpiece is raised at a rate of elevation equal to that of the lower die and, upon the start of the bending operation, the workpiece continues its upward movement, and the support base is tilted to follow the inclined position of the workpiece caused by the bending operation.

Parent Case Text

DESCRIPTION OF THE INVENTION

This application is a continuation-in-part of U.S. Pat. application Ser. No. 191,319 filed Oct. 21, 1971 now abandoned.

Description

In a press brake or bending press in which a punch or upper die is stationary and a lower die is movable upwardly to produce a bend in a workpiece positioned between the dies, the operator usually has to hold the free end of the workpiece and manipulate and support it as the lower die is brought near to the stationary upper die and the said end is raised as the bending operation proceeds. Such manual operation is not difficult if the workpiece is relatively small and light in weight, but such will not be the case when the workpiece is both heavy and larger in size. For instance, when a 90.degree. bend is performed in the workpiece, with its free end measureing one meter from the center of the bend, the free end of the workpiece is swung upwardly through an angle of 45.degree. and is raised to a height of nearly 0.7 meters above its original position. Thus, the operator's attention is distracted from the actual bending operation by the need to handle the swinging free end. Moreover, once the bending operation has been completed, the free end has a tendency to drop suddenly as the lower die is retracted or dropped, and this of itself can be dangerous, particularly with a heavy workpiece.

The present invention is so devised that the support and follow-up movement will proceed automatically and accurately and that the bending operation is performable by a single workman upon selecting the bending position of the work and depressing a foot-operated pedal.

These and other objects and advantages of the present invention will now be described further in connection with the following drawings, wherein:

FIG. 1 is a front elevational view of a press brake or bending press embodying the concepts of the present invention;

FIG. 2 is a side view of the apparatus shown in FIG. 1;

FIG. 3 is an enlarged side view of a portion of apparatus shown in FIG. 2;

FIG. 4 is a view similar to FIG. 3, showing parts of the apparatus adjusted to different positions in accordance with the operational sequence of the apparatus;

FIGS. 5 and 6 are sectional views taken along lines V--V and VI--VI respectively of FIG. 3;

FIG. 7 is a plan view showing a portion of hte tiltable table;

FIG. 8 is a schematic hydraulic circuit diagram; and

FIGS. 9a-9f are schematic illustrations depicting a typical bending sequence for an apparatus of the type disclosed in the preceding drawings.

The apparatus according to this invention comprises a base 1, a vertically movable frame 3 and a tiltable table 5. Base 1 is a rectangular structure secured on the same floor surface as the press brake or bending press, said base 1 accommodating therein a lift cylinder 7 and hydraulic devices 9 (pump, motor, etc.) and equipped with a level adjusting means 11 for levelling the vertically movable frame 3 at its free end. The frame 3 consists of a rectangular structure movable vertically and comprising an upper framing 3a and a lower framing 3b which are joined together substantially at a central position. The frame 3 is supported in the vicinity of the thus joined portion by the piston rod 7a of the lift cylinder 7. The vertically movable frame 3 is pivotally attached at its opposite end by means of a pin 17, the latter being carried by a yoke member 15 which has two arms 15a, 15b. The arms 15a, 15b are secured to and extend obliquely from a die support base 13. The yoke member 15 is adjustable vertically by means of an adjustment screw 19 and is movable integrally with a die 21 when thus adjusted. The vertically movable frame 3 is provided at its bottom end in the vicinity of the yoke member 15 with a block 23 and a bell crank means 25 is carried by the block 23, with its shorter arm 25a horizontally extending to the right as viewed in FIG. 3 and its longer arm 25b depending downwardly. The shorter arm 25a of the bell crank lever means 25 abuts through an adjusting bolt and nut 26 on the lower surface of the vertically movable frame 3, while the longer arm 25b abuts on the projecting end of a decelerating valve means 29 through the intermediary of a connecting rod 27. The numeral 31 denotes a spring which urges the bell crank lever means 25 in its entirety to rotate counterclockwise around its pivot shaft 24.

Two support blocks 33 are mounted on opposite sides of the frame 3 so as to be adjustable towards and away from the lower die, i.e., in the left and right hand directions as viewed in FIG. 3. To this end, elongated guide slots 35, 37 (See FIG. 5) on each support block 33 cooperate with bolts 36, 38 projecting upwardly from the frame 3. Adjustment of the support blocks 33 is accomplished by first loosening the bolts 36, 38, and thereafter rotating the handwheel 39 which is connected through a system of bevel gears and connecting shafts to shafts threaded through projections 33a, the latter extending laterally from the support blocks. Although only one support block 33 has been shown in FIG. 5, it will be understood that the other block is constructed and adjusted in the same manner by means of an extension of the shaft on which the handwheel 39 is mounted. The support blocks 33 are adjusted according to the width of a V-shaped groove 21v in the lower die 21 so that the distance between the right-hand shoulder 21s as viewed in FIG. 3 of the V-shaped groove 21v and the pitch circle of the internal gear 41a of a quadrant sector gear member 41 will be precisely equal to that between the said pitch circle and the pitch circle of the external gear 41b of the sector gear member 41 or, in other words, so that the distances "l" as shown in FIG. 3 will be equal.

A pair of rotatable parallel shafts 43, 45 extend between the support blocks 33 located on opposite sides of the frame 3. Each support block is further provided with lateral projections 33b, 33c which provide bearings for short rotatable shafts 47. Each of the shafts 47 is provided at opposite ends with bevel gears 47a, 47b, the former being in meshed relationship with a beveled gear 44 on one end of shaft 43 and the latter being in meshed relationship with a bevelled gear 46 on the other end of shaft 45. A pinion gear 49 on shaft 43 is in meshed relationship with the internal gear 41a of the sector gear member 41. Each time the pinion gear 49 performs a complete revolution, a pinion gear 51 which is on shaft 45 and which is in meshed relationship with the external gear 41b of the sector gear member 41 will perform two revolutions.

As shown in FIG. 3, each support block 33 is further provided with rollers 53, 55 positioned to run along an arcuate guide slot 41s on the sector gear member 41, the latter being secured at its upper end to the tiltable table 5. Thus, the sector gear member 41 will perform a circular motion smoothly with the shoulder 21s of the V-shaped groove 21v of the die 21 as the center of such circular motion. The vertically movable frame 3 is provided at its end with two adjustment bolts 57 which serve as a means for maintaining the tiltable table 5 in the horizontal position when the tiltable table is not in operation. The lower end of a tilting cylinder 61 is pivotally connected to a support means 60 which in turn is attached to the lower end of a support column 59 depending from substantially the central zone of the vertically movable frame 3.

The tiltable table 5 provides a lattice structure having on its upper surface a plurality of ball castors 63 and several electromagnets 65 for sliding and supporting the workpiece. The piston rod 62 of the tiltable cylinder 61 is pivotally connected to some suitable portion as at 67 on the tiltable table 5. When the piston rod 62 is extended, the tiltable table 5 and the vertically movable frame 3 will move apart from each other. On account of the function of the sector gear members 41 secured to the side of the tiltable table 5, the tiltable table will assume an inclined position such that a straight line connecting the uppermost points of the ball castors 63 will be situated in a radial line extending from the right-hand side shoulder 21s of the V-shaped groove 21v of the die 21.

An abutment bar 69 is secured to a mounting shaft 71 which is pivotally mounted on the end of the tiltable table 5 in the vicinity of the lower die 21. The abutment bar 69 is urged to rotate clockwise as viewed in FIG. 3 by resilient means (not shown). A bar 73 secured to shaft 71 and extending therefrom to the right as viewed in FIG. 3 is arranged to abut lightly on the head 75a of a decelerating valve means 75.

The apparatus described above operates in the following manner: in the circuit diagram shown in FIG. 8, a hydraulic pump and other hydraulic devices driven by motor M.sub.2 are adapted for imparting vertical movement to the frame 3 and the tiltable table 5, while those driven by motor M.sub.3 are adapted for tilting the table 5 in relation to the frame 3. Although the hydraulic circuits for vertically operating the lower die 21 of the bending press proper have been omitted from the drawing, the pump output for raising the frame 3 is so designed that the speed of upward movement of the piston 77 shown in FIG. 8 will always be greater than that of the die 21. On the other hand, the capacity of the hydraulic pump for driving the piston 79 for the tiltable table 5 is selected to a higher value so as to have displacement for the capacity of the cylinder 61. Also, the capacity of each decelerating valve means 29, 75 is selected so that the entire output from its corresponding hydraulic pump will be allowed to flow therethrough when the head of each valve means is pushed from its fully closed to the fully opened position.

When performing a bending operation, the workpiece M is placed on the ball casters on the tiltable table 5, and at this time the motors M.sub.2, M.sub.3 have been started, but the frame 3 will not be elevated, since the head of the decelerating valve means 29 is pressed by the longer arm 25b of the bell crank means 25 to make the entire flow of hydraulic fluid from the pump flow therepast. On the start of the upward movement of the lower die 21, the pin 17 supporting the vertically movable frame 3 will be raised therewith and accordingly the frame 3 will have a tendency to rotate around the pin 17 as its free end remains in the lowered position. Thus, the longer arm 25b of the bell crank means 25 will be rotated clockwise to release the head of the valve means 29 to close the valve so that the hydraulic fluid will be delivered into the cylinder 7 for elevating the frame 3. On the other hand, when the frame 3 is being elevated too quickly and the free end thereof is being raised to a higher position than the lower die 21, the lower arm 25b of the bell crank means 25 will be rotated counterclockwise into pressure contact with the head of the valve means 29 under the force of the spring 31 so as to make the hydraulic fluid flow therepast and slow down the upward movement of the vertically movable frame 3. The angles between the longer arm 25b of the bell crank means 25 and the vertically movable frame 3 can be adjusted by the adjusting bolt and nut 26 provided on the end portion of the shorter arm 25a of the bell crank means 25.

Thus, when the lowered die 21 is being raised, the frame 3 is being raised in unison therewith under operation of the piston 77 of the cylinder 7 and therefor, the vertically movable frame 3 and accordingly the workpiece M placed on the table 5 will be maintained horizontal. This operative phase is shown in FIG. 9b. When the bending operation is initiated, the oil pressure in the hydraulic system adapted for upward movement of the lower die 21 will be increased. At this time, solenoids SOL.sub.1 and SOL.sub.3 will be energized under the action of pressure responsive switches (not shown). Thus, the oil is allowed to flow into the cylinder 61 and the tiltable table 5 starts to assume its inclined position. The abutment bar 69 as already described with reference to FIG. 7 will act thereafter so that the tiltable table 5 will follow precisely the inclined position of the workpiece M.

In case the workpiece M is bent too quickly by the upper die P and lower die 21 and the tiltable table 5 can thus not follow the upward movement of the workpiece, the workpiece will not press the abutment bar 69 and accordingly the abutment bar 69 will be rotated with the mounting shaft 71 as an axis clockwise from the position shown in FIG. 3, under the action of the resilient urging means mounted on the abutment bar 69, so that simultaneously the bar 73 will be rotated clockwise to push the head 75a of the decelerating valve 75, and thus the decelerating valve means 75 will be closed to prevent the hydraulic fluid from flowing therethrough and the piston 79 accommodated within cylinder 61 for elevating the tiltable table 5 will be elevated in its position under the action of oil pressure from the hydraulic pump driven by motor M.sub.3 which acts thereon in its entirety. Consequently, the tiltable table 5 will be raised quickly to follow the workpiece M. When the tiltable table 5 is following precisely the inclined position of the workpiece M in contact therewith, the abutment bar 69 keeps its upper surface flush with that of the tiltable table 5, and therefor the bar 73 is kept in its raised position so that the head part 75a of the decelerating valve means 75 is free from the pressure of the bar 73 and is extended outwards. Thus, the hydraulic fluid from the pump is made to flow through the decelerating valve means 75 and is prevented from flowing too much into the cylinder 61, with the result that the table 5 will follow up precisely the workpiece M.

In the operative phase shown in FIG. 9c, the inclination of the table 5 will proceed simultaneously with upward movement of the lower die 21. Because of the controlling action of the decelerating valve means, the table 5 will follow the movement of the workpiece M and keep it in position for the optimun bending operation. Upon completion of the bending operation, electromagnets 75 mounted on the tiltable table 5 will be energized and thus the workpiece M is held on the upper surface of the tiltable table 5. The holding action of the electromagnets 65 will continue until the workpiece M is brought to its horizontal position as shown in FIG. 9e. After completion of the bending operation, the lower die 21 and the vertically movable frame 3 will first be lowered, and then the table 5 will resume its horizontal position as shown in FIG. 9e. The operating cycle is then completed when the workpiece M is removed, as shown in FIG. 9f.

In light of the foregoing, it will now be appreciated by those skilled in the art that by employing the present invention, a heavier workpiece of considerable breadth and length can be processed without the necessity of manually supporting and following a free pivoting end during the bending operation and without any risk of injury or damage being caused by an erratic upward or downward pivotal movement of the said free end. Thus the bending operation can be closely monitored by operating personnel. In effect, by controlling the upward and downward movement of the lower die, the bending operation will proceed fully automatically in such a way that the free pivoting end of the workpiece will be continually and automatically supported during its elevation and descent. Moreover, regardless of the various die configurations, both the tilting and follow up movement will always take place with the right-hand side shoulder 21s of the V-shaped groove 21v of the lower die 21 as their center, thus enabling an accurate bending operation.

It is my intention to cover all changes and modifications of the embodiment herein chosen for purposes of disclosure which do not depart from the spirit and scope of the invention.

Claims

I claim:

1. For use with a press brake or bending press of the type having an upper stationary die cooperating with a lower vertically movable die to bend a workpiece positioned therebetween, a workpiece support apparatus comprising in combination: a base fixed in relation to the press brake or bending press; a frame supported on and movable vertically in relation to said base; a table carried on and pivotally movable relative to said frame, said table being positioned to support a workpiece having a portion thereof located between the upper and lower dies; first operating means for imparting vertical motion to said frame; second operating means for imparting pivotal motion to said table; first control means responsive to vertical movement of the lower die, said first control means being associated with said first operating means and being operative in conjunction therewith to move said frame vertically in unison with the lower die; and second control means responsive to pivotal movement of a workpiece supported on said table during a bending operation, said second control means being associated with said second operating means and being operative in conjunction therewith to pivotally move said table in unison with the workpiece supported thereon.

2. The apparatus as claimed in claim 1 further characterized by means for adjusting said table laterally on said frame in opposite directions relative to the path of vertical movement of the lower die.

3. The apparatus as claimed in claim 1 wherein said table is pivotally supported on said frame by means including an arcuate gear member having inner and outer gears in meshed relationship with pinion gears carried on adjustment means, the latter being supported on said frame for movement in opposite directions relative to the path of vertical movement of the lower die.