US3102575A

US3102575A - Press brake having means to offset ram deflection

Info

Publication number: US3102575A
Application number: US852827A
Authority: US
Inventors: Charles F Engel
Original assignee: Engel Equipment Inc
Current assignee: Engel Equipment Inc
Priority date: 1959-11-13
Filing date: 1959-11-13
Publication date: 1963-09-03
Anticipated expiration: 1980-09-03

Description

Septr. 3,-

IPRESS'"BRAKE Filed Novnla, 1959 cQF. ENGEL 3,102,575

HAVING MEANS TO OFFSET RAM DEFLECTION i 5 Sheets-Sheet 1 IN V EN TOR.

CHARLES F. EN EL BY' j TTQBNEY Sept, 3, 1963 c. F. ENGEL 3,102,575

PREss BRAKE HAVING MEANS To OFFSET RAM DEFLEcTIoN Filed Nov. 1s, 1959 5 Sheets-Sheet 2 IN V EN TOR. CHARLES F. ENGEL BY E ' ATTORNEY Sept. 3, 1963 Y c. F. ENGEL 3,102,575

PRESS BRAKE HAVING MEANS To OFFSET RAM DEELECTION Filed Nov. 15, 1959 5 sheets-sheet s Ni v,-

INVENTOR. CHARLES F. ENGEL lax/M@ ATTORNEY Sept. 3, 1963 c. F. ENGEL 3,102,575

PRESS BRAKE HAVING MEANS TO OFFSET RAM DEFLECTION Filed Nov. 1s, 1959 5 sheets-sheet 4 FIG. 6

FIG. 7

INVENTOR.

CHARLES F. ENGEL BY y@ s ATTORNEY Sept. 3, 1963 v c. F. ENGEL 3,102,575

` PRESS BRAKE HAVING MEANS To oFFsEERAM DEFEEcTIoN Filed Nov. 15,1959 5 sheets-Sheet 5 INVENTOR.

Acr-LARLIES F. EN EL BY ATTORNEY 3,102,575 PRESS BRAKE HAVING MEANS TU @FFSET RAM DEFLECHQN Charles F. Engel, Columbia, ill., assigner to Engel Equipment, Inc., St. Louis, Mo., a corporation oli Missouri Filed Nov. 13, i959, Ser. No. 852,827 Claims. (Cl. 153-21) This .invention relates to powered press brakes such as are -used for making :bends in wide sheets of metal; and

more particularly to means for oisetting the deflection which the elongated ram blade of such press brake is likely to undergo under load.

When sheet metal stock is placed on the die supported by the bed of such a press brake, a downward movement of the ram bends the metal between the ram punch and the die. The degree of bend is determined in part by the distance which the punch enters the die; and using a straight die set, this will be uniform across the sheet width provided there is no substantial de ecticn as betweenvthe punch ,and the die. Normally the die bed is a part or' 'the highly rigid press frame; and it will not detlect greatly. However, the reciprocating ram blade is usually of lighter construction, and may deflect so much, in the region' midway between its ends, .as to make a lesser bend at the middle of the blade.

Various suggestions haveheretofore been made as to how this problem may be overcome. One of the early solutions, :which may be found in the patent to Dreisvogt No. 674,968, is to include truss rods which bridge the ram blade, to bow the blade 'center downward by la constantly-acting pre-set force applied by the truss-Work. This arrangement does not take account of the operating Iactuality ior a lesser degree of bend the punch enters the die to a lesser extent, and hencemeets less resistance. Nor does it take account of variations in the total force required to make the bend, which amount depends upon' such factors as the type oi metal, the gauge of the metal, and the width of the work piece.

A more recent attempt at solving this problem is disclosed in .the patent to Ernst No. 2,848,034, entitled Variable Pressure Flu-id Actuated Brake Beam Compensation. This device requires a complex hydraulic system to supply pressure to Aa jack which urges the ram blade downwardly `at its midpoint `during each down- Ward stroke.

The principal purpose of the present invention is to provide a simple mechanical device to achieve substantially the results sought by Ernst without the com-plexl ities of hydraulic mechanisms; and to augment the strength and offset the deection of the ram by purely mechanical means. A further purpose is to utilize the resistance of said mechanical means to prevent ram deection during that portion of the down stroke wherein the ram punch enters the die and to relax and relieve it on the upstroke, thereby to obtain easy adjustment between strokes.

Further purposes are to augment the bending strength of the ram blade by the bending resistance of a beam, and to bring the beam resistance into action only` during that portion of the stroke wherein ram blade deiiection is likely to occur.

An additional purpose is to provide readily `adjustable mechanical means which applies `a force to the blade between its ends, :adjustable to assure straightness of the punch at the lowennost part of any chosen stroke length and taking laccount of the bending resistance of a particular work piece.

A still further purpose is to provide a press brake with force-applying mechanism responsive of the extent to which the punch enters the die, so that the force to be hiateut 3'? Patented Sept. 3, l 963 e WQ@ applied is lessened with the lessening of the extent to to the ram bladepreferably centrally Vbetween its ends;

and the other beam end is mounted rockingly onto the fixed frame of the press brake. As the truss-work descends with the ram blade, a downward projecting point,

` adjustable as to length, contacts and presses downwardly upon the beam between its ends; and further downward movement of the blade bends the beam; so that the beam bending resistance exerts a downward force on the ram blade at the central pivot attachment. During the upstroke of the ram blade, the downward projecting point first Vlessens its force and then disengages from. the beam; so that at the top of theupstroke, the downward projection may be adjusted, -free from any pressure. This adjustment is conveniently made by turning .a deectioncorrecting adjusting nut, which will turn' freely when the ram is at the top of the upstroke, there being then no resistance.

The stroke length of the machine is not variable, but the stroke spacing relative to the die bed is adjustable. Before the stroke is made, a stroke-spacing mechanism, ,actuated by a motor-driven gear at each end of the brake, adjusts the position of the ram; either downwardly, so that its punch will bottom the sheet material in the die when the stroke is taken, or upwardly, to lessen the extent which the punch will enter the die. When the stroke-spacing adjustment positions the ram upwardly, it serves to lessen that portion of the actuation stroke during which the beam will exert pressure on the ram, much as if the deection-correcting adjusting nut had been' backed oli. This is a I`favorable result. Work pieces which are bent only slightly, oder less resistance to bending. For the smaller bend angles the ram will have a lesser tendency to deilect and will require a lesser deflection offsetting torce. it is highly advantageous that, in the present mechanism., the detlection-oisetting force is modied [automatically when the stroke-spacing adjustment is mede.

The operation of the present invention will be clearly apparent from the description of the preferred embodiment, illustrated in the accompanying drawings in which:

FIGURES 1a and 1b are the left and right portions respectively of an elevational view of a press brake ernbodying the present invention.

IGURE 2 is a left end View thereof.

FIG-URE 3 is -a sectional view taken along line 3 3 of FlGURE la, the blade being at the top of Stroke Whose spacing is so adjusted that the ram punch will bottom in the die. The phantom fragmentary View at the left illustrates the lower part of such a bottoming stroke. The phantom View at the right illustrates the ram blade at the top of a stroke whose spacing has been adjusted upwardly to prevent such bottoming FIGURE 4 is la sectional View taken along line 4 4 of FlGURE 1b.

FIGURE 5 is a sectional view taken along line 5 5 of FIGURE 1b and particulanly showing the provision for adjusting the spacing or positioning lof the blade stroke.

FIGURE 6 is a sectional view taken along line 6 6 of 'FGURE 5.

FIGURE 7 is a fragmentary view, somewhat simplied, showing in phantom lines the sideward displacement or swing of the ram support links as the blade spacing is adjusted vertically within them.

FIGURES is a right-end View of the machine shown in FIGURE 1.

FIGURE 9 is a fragmentary view corresponding to l -FIGURE la andshowing the deilection-offsetting action of the mechanism at the bottom of a stroke during which a work-piece is bent.

T lie Basic Press Brake 12 is rigidly supported in :a vertical plane by welding its ends in place on top of a pair of welded A-franies '13, which are spaced apart a distance equal to :the bed length. The securement of the die bed 12 to the A-frames 13 at each end of the die bed 12 is through a pair of parallelspaced, upright vertical end guides 14, whose lower ends are welded onto the Aapices of the .0i-frames 13. The

' spaced end `guides 14 clamp the ldie bed 12 between them,

utilizing la plurality of vertically aligned horizontal bol-ts 15. The guides 14 :further project vertically up above the die bed, 12 so as to provide structure to `guide `the ram blade 61, to hold support bearings, and to serve other conventional functions, some of which iare `apparent from the drawings and some of which will be described hereinafter. Diagonal truss members A16 adjacent to the vert-ical plane of the die bed 12, connect one side of it to thek bases of the A-fiames 13. Horizontal power shaft bushings 17, projecting beneath the die bed in its vertical plane, yalign .a rotatable power shaft 18 which extends across the machine and projects at each end beyond the A-frames 13, passing through the spaces between `the end guides .14 and immediately above the apices of the A-frames 13. At its right end, the power shaft 118 is engaged to a geared speed reducer 19 bolted to ya speed reducer support bracket Ztl. Power is supplied to the speed reducer 19 through V-belts 21 `and sheaves 22, 23 on the speed reducer 19 and on -an electric driving motor 24, respectively. A source of current, not shown, supplied to the machine at ajunction box 25, powers the motor 24 when the operator presses the foot switch 26, which is operatively connected through suitable wiring.

The speed reducer 19 may itself include a latching disconnect or braking7 element which will stop the shaft rotation `at the close of each cycle. The embodiment shown, however, uses a separate friction brake. Securedly mounted on the ileft end of the shaft 1S projecting beyond the A-frames 13 is a cylindrical brake drum 27, mounted concentrically on the shaft 18. On one side of the vertical end guide structure 14 is bolted, above the brake drum 27, ya brake band fixed end fitting 28. A springsupport bracket 29 is secured to the splicing portion S4 of the connecting link or rod member generally designated 51, `and hereinafter described. The connecting member 51 imparts a generally vertical reciprocating movement to the bracket 29, drawing it upward iat the close of each return stroke of the ram. The bracket 29 supports the lower coil lof `a compression brake spring 30, coiled about a brake rod 31 which passes through an aperture in and extends downwardly beneath the bracket 29. The rod 31 has `a lower end ball fitting 32 which is urged upwardly by the force in the compression spring 30, actingl against the :lower side of the brake Iadjusting nut 33 on the upward end of the rod 31.

A friction brake band 34 `around the cylindrical drum 27 is secured at ione end by the fixed end fitting 28; its other end terminates in a brake-band end reinforcement bracket 35, which has an aperture through which the brake rod 31 passes. Against the lower face of the end reinforcement bracket 35 bears the end fitting 32 at the lower end of the brake rod 31. By adjusting the nut 33, tension on the brake band 34 is varied.

When the bracket 29 lifts with the ram 61, it tightens the lbrake band 34 around the `drum 27, `stopping the ram i 61 whenever the power is shut off and the ram reaches the top of its stroke, that is, its Aupper position illustrated in FIGURES 1, 3 and 4.

Further describing the structure: the vertical end guides 14 are spaced somewhat outwardly from the fixed die bed 12, by spacing plates 36 which are drilled correspondingly with the end `guides `lid to receive the clamp- -ing structural bolts 15. Typical horizontal Work support members vmay be provided on one or both sides lof the die bed 12; illustrated in FIGURE 8 are a horizontal table'fi and horizontal work support brackets 38,

both ot which are supported by the die bed 12 or the p spacer plates 3e or both, `at a level established by the `upper surface of a press die 41 which is supported by the upper margin of the die `bed 12. The die 41 is removable and interchangeable. It extends nearly the full length between the vertical end guides 14, as shown in FIGURES la, lb, and includes an upper central die notch 42.

Flanking the power shaft 113 where it passes between the vertical end guides 14, are a pair of heavy support angles 433, which are welded between the apex of the A-frames 13 and the lower portions of the vertical end guides 14. The .bushing 17 next inwardly adjacent is fairly closely spaced, so that the power shaft 1d will undergo .little deilection at this point. On the shaft iinmediately adjacent the lbushing 33 there is mounted an eccentric cam 44, shown in FIGURES lb and 4 with its lobe portion `extending generally upward. As the shaft 1S rotates, the cam 44 engages the -microswitch 45 which is wired in parallel with (or in such manner as to function in parallelism to) the foot switch 26. Thus the foot switch may be engaged only ylong enough toV begin the rotation; and though it be then opened, the microswitch 45 lwill lcontinue to maintain the circuit with the electric motor 211 until shaft revolution is made; at which time the cam 44 returns to its upper position shown,

vopening the microswitch 415 and permitting the brake band 34 to bring the machine to a complete stop.

Near each end Iof the power shaft 1S, land located immediately outward of the vertical end guides 14, is secured yan eccentric disc 48, which serves as a crank throw by which the power is 'applied to the lower horizontalbore 49 in each lower end portion 50 of the two relatively at connecting rod or link members, each .generally designated 51. Preferably the eccentric disc 4S is flanged so that it will seat on its router periphery a bushing 52 ias shown in FIGURE 6. Secure aflixation of each disc 48 to the shaft 18 is obtained by a key and keyway provision 53, as shown.

In order to obtain precise alignment, each connecting rod or link member 51 is composed of three parts: its lower end portion 50, a middle or splicing portion 54, and an upper end portion 55, as shown in FIGURE 6. The upper end portion 55 has a large cylindrical horizontal bore 56, thus parallel to the bore 49 in the lower end portion Sil. The middle or splicing portion is welded t-o the outer side of the upper yend portion 5S so that it overlaps outwardly of the lower end portion 50, to which it is connected by a plurality of splice bolts 57, screwed into the lower end portion 50 through enlarged bores 58, which permit aligning adjustment.

'llhe ram 61 itself is a heavy metal blade extending the full distance between the vertical end guides 14 at the opposite ends of the machine, so that it will be reciprocable vertically within the guide structure so provided. Vertical spacer bars 62, whose combined thickness is less than the clearance between the sides of the rain 61 and the guides 14, have rounded indentations or dimples 63 in their inner surfaces. lFlush adjusting screws 64, having inwardly pointed ends, engage within the dimples 63 so as to press the vertical spacer bars 62 with greater or less pressure against smooth side surfaces of the rain 61, exerting sucient pressure to steady the blade without binding it.

In a recess in the bottom ofthe ram 61, in conventional fashion, is mounted a ram punch 65, which extends nearly the full length of the ram 61. The punch 65 terminates downwardly in a punch edge 66 which is4 so shaped as to enter into and mate with the die notch 42.

T he Stroke-Spacing M echansm The description which -:follows relates to the spacing of the fixed-length stroke with respect to the position of the `die bed 12.

The eccentric discs 48 serve as cranks on the power shaft 18; and that they draw the connecting rod or link members 51 downwand and return them upward through a fixed length of stroke shown in FIGURE 5. The positioning or spacing of the stroke, however, is determined by mechanism which mounts and supports the ram blade 61 between the link upper end portions 55, together with the associated stroke spacing mechanism.

Within each of the upper end portion horizontal bores 56, supported there Lby a friction-reducing bushing 67 is a rotatable eccentric disc member 66 similar in these respects to the eccentric discs 48 which serve as crank throws on the power shaft 18. These upper rotatable eccentric `disc members 68, however, are eccentric with reference to a horizontal support bore 69 which supports the ram journals 70. These are aligned with each other on a horizontal axis extending the length of the ram blade 61. Fixed connection between each journal 70 and the ram blade 61 is obtained by heavy ram support screws 71.

The axis of the ram journal 7d is denominated in FIG- URE 6 `as a; it is displaced from the central axis designated a, of the rotatable eccentric disc members 68. If the eccentric disc members 68 are rotate-d within the link upper end bores 56, the axis a will move vertically upward with respect to the axis a to achieve a maxi-mum upper posit-ion 'designated a. Because the ram journals 70 are v incapable of sideward movement, during such upward adjustment of the blade, the connecting rod or link member 51 swings through a slight angle (as shown in FIG. 7) with reference to its lower end bore 4?; so that its upper end portion S moves sideward and back through the swing distance s as the blade 61 is raised through its entire blade adjustment distance shown in FIGURE 5. The maxim-um sideward swing distance s will coincide with raising the blade 61 through only half of the blade adjustment.

The mechanism for driving this .stroke spacing adjustment may be any means to turn the eccentric discs 68 which mount the ram 61. I prefer to use a motor supported on the link 51 at the right-hand end of the machine. A lgear head Imotor 75 is mounted on a welded support bracket assembly -generally designated 76. This assembly includes two short horizontal channels '77 welded to the upper sides of the middle or splicing portion 54- of the right hand connecting link member 51. Between the outer ends of the channels 77 is an upright support 78, to which is mounted a motor support shelf 79k which `actually bears the gear head motor 75.

Projecting inwardly `from the head of the Kgear head motor 75 is a stub reducer ldrive shaft 80 hav-ing a coupling S1 through which it `drivesy a stroke spacing adjustment shaft S2 which extends horizontally across the upper part of the machine. The shaft 82 is supported near each end in bushings 83 which penetrate the extreme upper end of the connecting rod members 51. Note from FGURE 7 that this adjustment shaft 82 therefore swings sideward durin-g the adjustment cycle. The spacing between the vertical end guides 14 is therefore more than sufficient to permit this required degree of swing s to either side of the central plane which the shaft occupies during either the maximum up or maximum down stroke-spacing position.

Rotation tof the horizontal stroke-spacing adjustment shaft 82 is transferred as follows. Secured to the shaft 82 outwardly of the bushings 83 are spur gears 84, which engage ring gears bolted securely to and concentric withlthe rotatable eccentric disc members 68, or formed integral therewith. Access to the ram support screws 71 is provided through the central apertures of the ring gears l85; but at the. right end only, a short cylindrical dial 86, bearing` gage markings on its outer cylindrical surface, is secured over the aperture of the ring gear 85. Since the dial `86 rotates with the eccentric disc 68 when the shaft -82 is turned, the position in which it stops may of used as an indication of the blade spacing adjustment. The dial blade markings are read against the dial index or finger 87 which is secured to the upright shelf support member 78.

The gear head motor 75 is reversible, and the gear reduction is so great that the angular rotation of the adjustment shaft 82 can be readily controlled. The motor 75 is operated, and control is exerted, by swinging the handle of the reversing electric switch 88 to either side of the central olf position. The electrical connections` to the switch 88 are obvious. l

'Ihe purpose of spacing the stroke, by the mechanism which has just been described, is to affect the extent to which the ram punch edge 66 enters the die notch 42. As is well known, the same punch and die set may be utilized to `form different degrees of bend, ranging upward from zero degrees to -say ninety degrees, by carefully controlling the brake operation in this respect. Thus FIGURE 3, center, shows the parts with the ram 61 poised at the top of a stroke which, when completed, would be a bottoming stroke, creasing the metal work-piece w in the very bottom of the die notch 42 as shown in the phantom line drawing to the left. In order to position or space the stroke so that the punch edge 66 will not bottom within the die, the ram 61 is adjusted upwardly, between strokes, to such extent as is desired, up to an elevated position shown by the phantom line gure to the right in FIGURE 3.

Mechanism T0 Overcome Ram Blade Deflection Press brakes of the general type shown are used for sheet metal of Various widths and thicknesses of materials of different alloys. Any of these factors may to some extent affect the amount of resistance which the ram blade 61 meets when it presses a work piece between the ram punch 65' and the die notch 42.

if the blade 61 is to exert a large force, its deflection midway between its supported ends may be too great to achieve a uniform bend. vLackhof uniformity would result in the sheet metal work piece being creased less near the center of the blade than farther out. Such undesirable deflection of the middle of the blade 61 will be greater for the heavier bottoming strokes than for strokes wherein the ram punch edge 66 enters within the die notch 42 onlyslightly, such as if the work piece w were to be only slightly creased.

In the present invention, the tendency of the ram 61 to deiiect at its center is overcome by a force which increases depending in part upon how deeply the punch edge 66 will enter the die notch 42 when the stroke is made. This action is achieved by the mechanism now to be described.

At mid-span, a yoke is formed by welding; a pair of attachment plates 90 on each side of the ram blade 61, to extend vertically somewhat above the upper edge of the ram blade 61. A fore-and-aft pivot pin 91 extends through the yoke so formed. The pivot pin 91 mounts one end of a rockable beam 92, as shown in FGURES la and 3, which extends to the xed vertical guide structure 14 at the left end, where it rests with freedom to rock on` top of a short cross-bar 94 supported by the guide structure 14 of the machine. The cross-bar 94 establishes a left end rocking axis parallel to the axis of the pivot pin 91, both axes being perpendicular to the vertical plane of ram reciprocation established by the guide structure 14.

At a point which may be chosen empirically but is preferably between 30% and 40% of the span of the machine, there is welded upon the upper surface of the beam 92 a short uprightl steel tube 95., made of heavy walled steel and terminating upwardly in a centerless,

`spherically concave socket 96. The concave socket 96 receives the enlarged convex base 97 of an adjusting nut 98 which may be screwed upward or downward on the vertical threaded pin 99, formed of heat-treated steel, whose lower end is of lesser diameter than, and is accommodated within the socket 96 and the thick-walled tube 95 which supports the socket 96 on the beam 92.

The threadedl pin 99 projects downward from a truss spacer block 100, welded at the apex juncture of the upper ends of a pair of left-hand diagonal truss members 191 with the upper ends of a pair of right-hand diagonal truss members 102. The lower ends of each of these pairs of truss members is welded to a side surface of the ram blade 61 opposite the other member of the pair. The ram blade 61 and truss members 101, 162 thus form 'a triangular. truss-work with the threaded pin 99`at its apex and serving as its force-applying member. Neglecting the slight effect of elongation of the truss members 101, 162 when under load, the off-center pin 99 must move Vup and dow'n precisely the same distance as the mid-span pivot .pin 91. The

truss members

101, 102 are of unequallength, so as to position the pin 99 directly above the centerless concave member 96.

As the ram blade 61 moves downwardly, the truss work brings the pin 99 into force-applying relationship with the beam 92, at the level at which the nut base 97 contacts the socket 96. This level is determined by screwing the adjusting nut 98 upward or downwardly on the threaded pin 99. Once contact has been made-preferably about thelevel at which the punch edge 66 enters the die notch ft2-the bending resistance of the beam 92 is brought into use, to offset the tendency of the center of the ram blade 61 to deect upward. i

Thus, as the blade 61 is brought downward to a point where the punch edge 66 engages a work-piece w and vstarts to force it into the die notch 42, the convex nut base 97 will have engaged the concave socket 96; and further lowering of the ram yblade 61 will so press on the beam 92 that its right end will exert an increasing downward force on the pivot pin 91. The rectangular beam 92 has symmetrical bending properties in a plane perpendicular to the working axis at its left end and the axis of the pivot pin 91 at its left end; so that its reaction to the downward force on it will exert no side thrust on the ram 61.

lFIGURE 9 illustrates how the bending resistance of the beam 92 is utilized at the lower part of the stroke. Comparison with FIGURE la shows the rocking motion of the beam 92 as the ram 61 lowers; and how the bending resistance of the beam 92 is brought into action after the adjusting nut base 97 bottoms inthe cap 96. With proper adjustment, any tendency of the mid-portion of the ram 61 to bend upward due to the bending resistance of the work-piece w is overcome by the force which the bending resistance of the beam imposes downwardly on the pin 91.

A unique advantage of the present invention is that whentheram 61 is at the top of the stroke, there is no contact between the spherical faces of the

parts

96, 97. Hence the adjusting nut 9S can be turned freely by hand.

In ordinary productive use when material of a chosen alloy, width and thickness is being bent to various angles, it is often unnecessary to make any changes in adjustment of the nut 9S. To bend less than 90, the eccen- V tric discs 63 are rotated to adjust the position of the ram blade 61 so that it will not bottom on the downstroke. ee FIGURE 4, phantom view of raised position to right of center. As this adjustment is made, the spacing between the concave socket 96 and the convex nut base 97 increases without rotating the adjusting nut 98. If the stroke is `spaced to the uppermost position as in fla FIGURE 4 right, so that the punch edge 66 will barely crease the metal when it descends, no deflection-oisetting force whatsoever may be necessary and none will be applied; whereas, without further adjustment of the nut 93, a substantial corrective for-ceV will be applied if the blade stroke spacing is returned to bottoming position, as shown in the center and left illustrations in FEGURE 3. The inter-action of these two features minimizes the amount of adjustment necessary; and the few necessary adjustments lare so easy that the appa` ratus has great utility in practical operation.

With the pin 91 located at mid-span of the ram 61, favorable results are obtained if the truss apex is spaced at 30% to 40% of span. Nevertheless, other-arrangements are possible, such as utilizing two pivot pins such as the pin 91, at span stations one-third or so across the ram, together with a pair of rocking beams such as the beam 92, one extending to each side of the machine, and a pair of truss structures having projecting pins which engage the beams. Other changes in structure and operation may be evolved carrying out the basic teachings of the present invention. Accordingly the present invention should not be considered narrowly, but instead as fully coextensive with the claims which follow.

I claim:

1. A press brake of the type including a xed frame having means adjacent one end thereof to establish a rocking axis, an elongated die bed supported by :said frame, a die borne thereby, an elongated ram having a pivot point nter-mediate its ends, end guides for said ram mounted on said frame whereby to permit reciprocating movement of said ram, a punch borne .by vsaid ram, means adjacent to the ends of the ram to draw the ram reciprocatingly toward and iavvay from the die, Vtogether with a beam mounted onto and extending between the said rocking axis means of the fixed fr-ame :and the pivot point on said elongated` ram, and means mounted on said ram to apply a bending force lto said beam as the ram is drawn toward said Ibed and to relieve said force as the ram is withdrawn `away from said bed. s

2. A press brake of the type including a fixed frame having means adjacent one end thereof to establish a rocking axis, an elongated xed die bed supported by said frame, an elongated movable ram blade having a pivot point between i=ts ends, means mounted on the frame to guide-the ram in vertically reciprocating movements, means adjacent to the ram ends to draw said ram reciprocatingly within said guide means ltowards and away from the die bed, together with a beam mounted onto the fixed frame mounting axis and fthe ram blade pivot point so as to extend therebetween, and means mounted to the ram blade ends and .extending 'thereover which means lmakes contact 'with the beam, at a point between the points at which it is so mounted, on the downstroke of the ram blade and disengages such contact on the upstroke.

3. A press brdce including an elongated die bed, guide structure projecting vertically upward at the ends thereof, an elongated ram reciprocable vertically within said guide structure, power means imparting a reciprocating stroke to said ram, and mechanism for overcoming bending deiiection of the ram at its center, said mechanism comprising a ram center attachment pivot, a beam extending from said pivot to the vertically-projecting structure and there mounted rockably upon said guide structure, ram truss members of unequal length connecting the ram ends, said truss members joining each other at an obtuse angle presented over the beam at a point to one side of the ram center, and adjustable-length means secured to the obtuse angle to contact and press downward on the beam on the downward ram stroke and to relieve such contact on its upward stroke.

4. For luse with a press brake or the like having an elongated ram blade and a fixed frame projecting upward above the blade at one end, mechanism for overcoming deection of such ram blade, comprising a ram center attachment pivot, a beam having one end secured rto said pivot and having means at its other end to mount said end rockably on such upward projection of the frame, ram blade truss members Iof unequal length having lower ends mounted to the blade near its ends and having upper ends joined at a downwardlyquresented angle over a point on the beam intermediate the pivot and the rockable mounting means, and adjustable-length means to apply iiorce between the joint of said truss members and said beam joint therebeneath on lthe downward ram blade stroke and t0 relieve such force on its upward stroke.

5. The mechanism for overcoming ram blade deflection as defined in claim 4, each of the ram blade truss members comprising a pair of tension bars secured to opposite sides of the ram blade near its ends, the adjustable-length means being secured within the obtuse angle and including an adjusting nut.

References Cited in the le of this patent UNITED STATES PATENTS 1,299,501 Nawrath Apr. 8, 1919 2,133,477 Schade Oct. 18, 1938 2,689,487 Krueger Sept. 21, 1954 2,709,924 Castelli June 7, 1955 2,848,034 Ernst Aug. 19, 1958 FOREIGN PATENTS 114,607 Germany Nov. 10, 1900

Claims

1. A PRESS BRAKE OF THE TYPE INCLUDING A FIXED FRAME HAVING MEANS ADJACENT ONE END THEREOF TO ESTABLISH A ROCKING AXIS, AN ELONGATED DIE BED SUPPORTED BY SAID FRAME, A DIE BORNE THEREBY, AN ELONGATED RAM HAVING A PIVOT POINT INTERMEDIATE ITS ENDS, END GUIDES FOR SAID RAM MOUNTED ON SAID FRAME WHEREBY TO PERMIT RECIPROCATING MOVEMENT OF SAID RAM, A PUNCH BORNE BY SAID RAM, MEANS ADJACENT TO THE ENDS OF THE RAM TO DRAW THE RAM RECIPROCATINGLY TOWARD AND AWAY FROM THE DIE, TOGETHER WITH A BEAM MOUNTED ONTO AND EXTENDING BETWEEN THE SAID ROCKING AXIS MEANS OF THE FIXED FRAME AND THE PIVOT POINT ON SAID ELONGATED RAM, AND MEANS MOUNTED ON SAID RAM TO APPLY A BENDING FORCE TO SAID BEAM AS THE RAM IS DRAWN TOWARD SAID BED AND TO RELIEVE SAID FORCE AS THE RAM IS WITHDRAWN AWAY FROM SAID BED.