US3529461A - Roll forming method and machine - Google Patents

Description

Sept. 22, 19.70

G. A, KNuDsoN nLL Pomme METHOD AND MACHINE Filed Nov. 15, 1968` 3 SheeYtISLSheet 1 OOOM R. om TS WD vw mK A. Y R A G /m ATTORNEY Sept. 22, 1970 G. A; 'KNuosoN 73,529,461

` nou. romanze METHon nu mesma Filed Nov. 15. 1968 s sneetsfsneet 2 f i 1NvENToR- Y GARY AQKNUDSON MMMQ.

ATTORNEY Sept. 22, 1970 G. A. KNuDsoN ROLL FORMING muon AND MACHINE 3 Sheets-Sheet 5 Filed Nov. 15. 1968 l INVENTOR. GARY A. KNUDSON M Mgq.

- ATTORNEY United States Patent O 3,529,461 ROLL FORMING METHOD AND MACHINE Gary A. Knudson, 12820 Willow Lane, Golden, Colo. 80401 Filed Nov. 15, 1968, Ser. No. 776,131 Int. Cl. BZld 5/08 U.S. Cl. 72-181 16 Claims ABSTRACT OF THE DISCLOSURE A method and apparatus for forming shaped members such as U-shaped gutters wherein a flat strip of material is moved downwardly along a parabolic curve as it is being formed between contact surfaces of successive sets of shaping rollers to relieve stresses in the material. An upturned concave shape is rst formed in an intermediate portion of the material and maintained for a length of the travel by cooperative concave and convex peripheral contact surfaces on a series of sets of shaping rollers. Side portions of the material are sharply turned normal to the intermediate portion to shape the intermediate portion into a flat side and form sides adjacent and generally transverse to the flat side.

This invention relates to a novel and improved method and machine for making shaped members from a thin flat strip of material such as a metal strip.

Machines for forming stock material such as sheet metal into desired cross-sectional shapes using a series of roller sets, commonly referred to as roll forming machines, have heretofore been in common usage particularly in the building trade for producing selected lengths of shaped members such as gutters, downspouts, structural members, roofing, siding and the like. A preferred crosssectional shape particularly from the standpoint of strength is to have the sides of the shaped member disposed in a transverse or perpendicular relation to each other. For example, the U-shaped or box-shaped type gutter has an essentially deep channel-shaped cross-section and the usual downspouts have a box-shaped cross-section.

One of the problems in roll forming thin strips of sheet metal such as galvanized sheet metal, sheet aluminum or painted sheet metal which are in common use is that it may be stretched beyond elastic limits and rippled or buckled if the bending between each shaping roller stage is too radical or sharp in .the direction normal to its longitudinal course of travel. This usually presents no problem so long as the shaping rollers can be spaced a substantial distance away from each other. However, more recent trends in roll forming machines have been away from larger and heavier machines toward a compact, smaller and lighter portable machine which may be readily transported to the job site as on a pick-up truck or the like to produce a needed amount and length of shaped members required for a particular job. For portable applications it is desirable that the machine can be operated with no special training or skill and preferably by only one person with a minimum of maintenance and repair.

In the past, a common practice in many roll forming machines particularly those for forming gutters has been to align a series of top and bottom sets of rollers to dene a at contact plane for moving the material longitudinally along a common horizontal course of travel. Another common practice has been to employ a flat contact surface between the roller sets to engage the intermediate or bottom portion of a strip of material in bending a U-shaped gutter into shape. While this practice has been satisfactory for many applications, these practices have not been entirely satisfactory because of the required spacing between roller sets lengthwise of the machine 3,529,461 Patented Sept. 22, 1970 ice which Was necessary to avoid stretching or buckling of the stock material, thus making the machines unnecessarily long.

Accordingly it is an object of the present invention to provided a new and improved method and apparatus for making shaped members having one side essentially at right angles to another or of a U- or channel-shaped cross-section from a thin at strip of material which can be carried out over a shorter length of travel without stretching, rippling or buckling.

Another object of this invention is to provide an improved gutter machine which will form straight, ripplefree gutters with a minimum or virtually no chance of lateral slippage of the strip as it is being shaped.

It is a further object of this invention to provide a compact, lightweight and more trouble-free portable machine for forming U-shaped gutters and the like shaped members.

One of the features of the present invention is the alignment of the material contact surfaces of one group of a series of sets of top and bottom rollers along a particularly parabolic arc or geometrically curved course of travel which progressively decreases in slope and the alignment of a second group of roller sets having contact surfaces arranged along a flat plane or at course of travel for the material which allows the shortening of the space between sets of rollers without producing a stretching of the material. Another feature of the present invention involves the bending of a bowed-upward concave shape in the material inwardly of its side edges and holding or maintaining the material in this shape during succeeding shaping by rollers having curved rather than flat material engaging surfaces followed by the radically bending of the outer side portions inwardly in a normal or transverse relation to the intermediate portion which attens the intermediate portion to form a flat side and avoids buckling or rippling in the final product.

Other objects, advantages and capabilities of the present invention will become more apparent as the following description proceeds taken in conjunction with the accompanying drawings, in which:

FIG. l is a side elevation view showing the general arrangement of the parts of a portable gutter making machine embodying features of the present invention.

FIG. 2 is a top plan view of the gutter making machine of FIG. l with upper side members of the frame and the top rollers and their associated side support members as well as other upper structures above the lower rollers of group A removed to show the relation of the lower rollers of group A and other associated interior parts.

FIG. 3 is an enlarged fragmentary side elevation view of the first group of roller sets shown in FIG. 1.

FIG. 4 is a schematic side elevational view showing a prole arrangement of both groups of the sets of shaping rollers of the machine shown in FIGS. l, 2 and 3.

FIG. 5 is an elevation view of the first set of upper and lower shaping rollers.

FIG. 6 is an elevation view of the second set of upper and lower shaping rollers.

FIG. 7 is an elevation of the third set of upper and lower shaping rollers.

FIG. 8 is an elevation view of the fourth set of upper and lower shaping rollers.

FIG. 9 is an elevation view of the fifth set of upper and lower rollers with a portion of the support structure associated therewith shown.

FIG. l0 is a cross-sectional view showing the fiat shape of the stock material before it enters the first set of shaping rollers.

FIG. l1 is a cross-sectional view of the material as formed in the first set of rollers.

FIG. 12 is the shaped cross-sectional view of the material as formed in the second set of rollers.

FIG. 13 is a cross-sectional view of the material as it is formed in the third set of rollers.

FIG. 14 is a cross-sectional view of the material as it is formed in the fourth set of rollers.

FIG. 15 is a cross-sectional view of the material as it is formed in the fifth set of rollers; and

FIG. 16 is a cross-sectional view of a final gutter product as it is nally discharged by the machine.

Referring now to the drawings, a typical portable gutter forming machine as shown therein includes general support structure in the form of a skeletal rectangular main frame 10 having depending legs 11 at each corner mounted on wheels 12 for the mobility desired by a portable machine. This main frame 10 includes spaced upper side members 13 and spaced lower side members 14 on the sides and end members 15 and 16 at the intake and discharge ends arranged in an open box-shaped configuration. These members are shown preferably as I- shaped beams. The drive or motive power for the machine includes a motor 18 mounted on one side of the frame which is coupled in a driving relation to a main drive shaft 19 journaled at one side of the main frame. The main drive shaft 19 is coupled in a driving relation through a power transmission arrangement which it is understood may take a variety of forms but in the arrange.- ment shown positively drives all of the rollers in group A except the top roller of the first set and the lower rollers in group B in the direction indicated by arrows in FIG. 4.

A general description of the various parts, their location on the main frame and their operation will first be described proceeding from the intake end to the discharge end of the machine followed by a detailed description of the various parts. The sheet metal stock material 20 illustrated in FIGS. 1 and 10 is usually furnished as a strip in a rolled form and this strip of material is delivered between an upper arcuate guide plate 21 and associated lower'adjustable guide plates 22 before being passed through a first group of four sets of upper and lower shaping rollers generally designated by letter A. The material passing from the second of the sets of rollers of group A engages a back guide rail 23 and then as it leaves the sets of group A passes between an oppositely disposed converging back and front guide rails 23 and 24 as viewed in FIG. 1. The material is then moved through a second group of four sets of upper and lower rollers generally designated by letter B. A final bending and straightening is carried out in a box-shaped unit device 25 downstream of the rollers of group B which includes several idler rollers. A crimp is put in the rear edge by a crimper device 26; the latter two devices 25 and 26 are shown only generally but it is understood form no part of the present invention.

All of the rollers of groups A and B are shaft mounted and each is arranged for rotation about a generally horizontal axis in a suitable arrangement such as bearings carried by oppositely disposed side support members which are in turn mounted on the main frame 10. It is understood that the mounting of these rollers may be made on a variety of support structures and different bearing and shaft arrangements. Only one of two side support -members 28 for the upper rollers of group A can be seen in FIG. 1 but it is understood that a pair of side support members are arranged on the opposite sides of the upper rollers of group A to support them in the position as shown. In turn, the lower rollers of group A are each suitably mounted for rotation on a pair of oppositely disposed side support members 29 and 30` located between the upper and lower side members 13 and 14 on each side of the main frame. These support members are arranged to incline downwardly and rearwardly from their forward ends at the intake end of the machine and are removably mounted in relation to the other structure on the frame at their rear ends. More specifically, the rear ends of the side support members 29 and 30 are arranged outwardly of and in an overlapping relation to the front ends of the adjacent lower side support members 39 and 40 and a hollow shaft 33 is disposed between the front ends of the support members. A removable rod 31, threaded on each end extends through this shaft 33 and apertures in the overlapping ends of these support members and has suitable washers and nuts 32 on each end to secure their associated lower support members firmly in place. This downwardly inclined mounting arrangement of the lower rollers of group A allows the centering of the lower rollers along the parabolic curve hereafter described while allowing the bearings which support the rollers to be essentially centrally located on the support members 29 and 30.

In general, the upper rollers of group B are supported from a vertically adjustable support assembly to be described which is carried by the upper side members 13 of the main frame 10, so that the pressure of the top rollers against the bottom rollers of group B may be adjusted. The bottom rollers of group B are mounted for rotation on oppositely disposed support members 39 and 40. In the machine shown there are four sets of upper and lower shaping rollers in group A which, proceeding from the front or intake end along the machine, are designated as a first set 41 and 42, a second set 43 and 44, a third set 45 and 46 and a fourth set 47 and 48. Group B has four sets of upper and lower rollers, a first set being designated by numerals 51 and 52, a second set 53 and 54, a third set 55 and 56 and a fourth set 57 and 58.

The particular arrangement and relationship of the series of sets of rollers in groups A and B are best described with reference to the general schematic diagram of FIG. 4. In general the peripheral material contact surfaces between each successive set of upper and lower rollers in group A is on or arranged along a parabolic curve or parabolic contact plane designated 59 which progressively decreases in slope and the peripheral material contact surfaces between each successive set of upper and lower rollers of group B are on or arranged along a generally horizontal, flat plane or at contact plane designated `60. The term contact plane as used herein refers to a plane including points at which the material is contracted or gripped by the upper and lower roller sets both to shape it along its width and to move it generally longitudinally along a particular course of travel.

The arrangement of the sets of rollers in both groups A and B may be expressed in terms of a rectangular coordinate system using an x-axis which corresponds with flat contact plane 60` and a y-axis perpendicular to the x-axis. By way of explanation, the general equation for a parabolic curve having its focus on the positive y-axis is x2=2py which simply stated means that a change in vertical distance from a reference point is proportioned to the square of the change of a horizontal distance from the reference point. For the purposes of explaining the parabolic curve 59 which locates the peripheral contact surfaces of the sets of rollers of group A, the general equation is x2=hy where h is a selected maximum distance of elevation on the curve above the x-axis. As related to the above general equation for a parabola the parabolic curve 59 has its origin at the centers of the first set of rollers of group B or the fifth set of rollers for the entire machine and is in the second quadrant from the standpoint of a rectangular coordinate system using x2=hy. However, for the purposes of explaining the arrangement of the roller sets along this curve in a logical order progressing from the intake end to the discharge end of the roll forming machine the origin designated O of the coordinate system is located at the centers of the rst roller set of group A and the equation with the origin transposed is where h is a selected maximum height of the curve above the xaaxis, xt being the total distance of the curve from the origin O to the center of the rst set of rollers in the group B.

The peripheral material contact surfaces of each of the successive sets of rollers in group A and the rst set in group B are located on the curve 60` using five equal increments of distance along the x-axis in accordance with the following tabulation using 1 as the total horizontal distance xt:

Point numeral The slope of this curve 60- decreases progressively from the points 61 to 66. By way of example for apparatus shown of the type which is suitable for making ive U- shaped gutters the total distance xt is thirty yinches so there is six-inch increments between the centers of the rollers of group A and twelve inches between the center of the last roller of group A and the first roller of group B and twelve inches between the centers of each of the sets of rollers of group B. The maximum height h is one inch. The parabolic equation for the curve with the center of the roller at point 66 is x2=900y. Applying the above formula with the origin O at the rst roller set the location of the roller sets of group A is:

Thus by selecting a value h for height and total length xt the peripheral material contact surfaces of the sets of rollers may be located along this curve. Such a curvature during shaping has been found to prevent stretching in the edges of the strip of material as it progresses through the machine and is 'being roll formed into the shape of a U-shaped or similar member.

Referring now particularly to FIGS. 6 through 15 and FIG. 1, each of the lower rollers 42, 44, 46 and 48 has a similar intermediate convex shaped portion C of the same width formed along a radius of curvature indicated by R1 and the associated and oppositely disposed upper rollers 41, 43, 45 and 47 have a similar concave portion D of the same width having a radius indicated :by R2. These concave and convex portions of each set are -in alignment with one another lengthwise or longitudinally of the machine as shown in FIG. 1. The curved portion C of the first roller set initially shapes the intermediate portion 71 of the strip of material which is the bottom wall or the bottom side of the gutter into an upturned bowed or concave shape. As shown in FIGS. l0, 1l, 12 and 13, the three succeeding roller sets maintain this shape through the three succeeding sets of rollers. It is preferred that the radius R2 of the portion of upper roller is slightly less than the radius of the lower portion C which will form a thin cresent-shaped space between portions C and D with the closest points being at P1 and P2. A typical radius of curvature would be 12.0 inches for R1 and 11% inches for R2. In this manner rollers can be spaced apart so that the Contact surfaces tightly grip the material particularly at points P1 and P2 as it is passed through the first four successive sets of concave and convex roller surfaces. It has been found that holding of the sheet metal or the like in this concave conguration helps to prevent rippling and buckling of the bottom side while radically bending the ogee curvature of the upper square corners and the hem or hook return to be described. It has also been found that the machine tracks better because the material will follow this concave and convex curvature from roller set to roller set with no chance to slip from side to side.

Each of the lower rollers of group A has a similar essentially flat portion F on one side of the intermediate portion C. The strip of material as shown in FIG. l has a side portion 72 outwardly of the intermediate concave portion 71 contacted by roller portion F which corresponds to the inner side wall of the gutter. The rst lower roller 42 has a portion H on the other side of the intermediate portion C which cooperates with a portion I on the upper roller 41 to shape the other side wall B of the gutter. Portions H and I are shaped to begin the initial forming of the ogee and hem in the outer side wall 73 as shown in FIG. ll. The second upper and lower rollers 43 and 44 have portions generally similar to and in alignment with surface portions H and I which are somewhat sharper in profile to further form the ogee and hem portions in side wall 73 and turn this side upwardly at an inclined angle to the horizontal as shown in FIG. l2. All of the a-bove-described portions of the first two roller sets are integral and are arranged to rotate conjointly with each other.

The roller portion of third lower roller 46 which aligns with portion H of the rst lower roller 42 has a portion K integral and conjointly rotatable with its associated portion C and a bulb-shaped portion L arranged as an idler roller for independent rotation with respect to portion C. This independent rotation is carried out by a shaft 75 suitably secured at its inner end to the driven roller being provided with portions C and K and journaled at its other end in the side support structure. This idler roller L is mounted on a pair of spaced bearings 76 carried by shaft 75. The upper roller 45 has a bulbshaped portion M arranged for conjoint rotation with concave shaped portion D and another narrow idler roller N on a shaft extension secured to portions D and M 'which cooperate with idler portion L of the lower roller assembly. Portions K, L, M and N above-described are shaped to further turn the outer side 73 of the material inwardly in a transverse relation to the bottom side 71 while the concave shape is retained in the bottom side 71. The other side 72 of the strip of material is also being gradually turned in an upwardly and inwardly transverse relation to the side 71 by the rear guide rail 23 as it is passed between the second and third roller sets and is turned up substantially as it passes through the third roller set as shown in FIG. 12.

The upper and lower rollers 47 and 48 comprising the fourth roller set have portions generally similar to portions K, L, M and N above-described on the third roller set but are arranged to further turn the outer side 73 inwardly and at the same time the rear guide rail 23 also further turns the inner side 72 inwardly as shown in FIG. 13. After the strip of material leaves the fourth roller set 47 and 48 it passes between both guide rails 23 and 24 which bends both sides of the strip of material radically toward each other and removes the upturned bow in portion 7 and straightens it to a flat side or bottom of a gutter as shown in FIG. 15 so that as it is passed through the fifth roller set the bottom is at.

In connection with the particular drive arrangement shown, the shaft extension on the right of the lower fourth roller 48 which directly is coupled to the main drive shaft 19 has a gear 77 disposed in a meshing relation with a larger gear 78 on the upper roller 47. Each of the lower rollers has a sprocket 79 on the left side with an idler 81 between the second and third rollers over which a transmission member 82 is trained to positively rotate each of the lower rollers in group A. The second and third and fourth upper rollers are provided with a sprocket 83 on the right side over which a transmission member 84 is trained so that they are positively driven through gears 77 and 78. It is noted that the first upper roller 41 is not positively driven and is an idler roller.

With particuar reference to FIGS. l, 2 and 9 the adjustable support assembly for the upper rollers of ygroup B includes a pair of longitudinally extending roller support bars 85 and 86 located centrally of the machine. These bars are held in a depending manner from an upright guide support 87 located at each end and between thc support bars 85 and 86, each having a cross member 88 which overlaps the lower leg of the upper side support 13. Each of the upper ends of the transverse members has a bolt 89 which threads into the support 13 to lock the assembly and a pair of bolts 91 on each side of bolt 89 which bear against the top of the support 13 to change the elevation of the assembly and thus the pressure of the upper rollers against the lower rollers. Each of the upper rollers of group B are similar and as shown in more detail in FIG. 9 are four individual idler rollers; the upper roller 51 comprising separate rollers 51a and 5111 between bars 85 and 86 and rollers 51e and 51d on each side of these bars which are of a total width to engage the upper surface of the flattened bottom 71 of the gutter.

Each of the lower rollers of group B are generally similar and as shown in more detail in FIG. 9 have a at intermediate portion 52a over which the iiat bottom 71 of the material is moved and an inclined flange-like portion 52h in an oppositely disposed relation to roller 51C which contacts the lower portion of side 72 and an inclined llange-like portion 52C in an oppositely disposed relation to roller 51d which contacts the lower portion of side 73.

In connection with the drive arrangement shown for the lower rollers of group B there is provided a sprocket 92 on the fourth lower roller 48 which is in an aligned relation with sprocket 93 on each of the lower rollers of group B and each sprocket 92 has an idler sprocket 94 and a transmission member 95 is trained over each sprocket 92 and between sprocket 93 and its associated idler sprocket 94 to positively drive the lower rollers of group B from the main shaft 19.

The above-described roller structure and arrangement allows a substantial reduction in the spacing between roller sets. For example, previous machines incorporating features above-described in the prior art produced a machine of generally eleven feet in overall length and weighing about 1,400 lbs. However a machine embodying features of the present invention for forming gutters of the type shown need only be about seven feet long and 600 lbs. in weight. This portable machine will produce a straight ripple-free product.

Although the present invention has been described with a certain degree of particularity, it is understood that the present disclosure has been made only by Way of example and that changes in details of structure and system components may be made without departing from the spirit thereof.

What is claimed is:

1. In a roll forming machine for forming generally U-shaped gutters having a flat bottom and sides convergent thereto with an ogee curve in one side thereof from a strip of sheet material, the combination comprising a support structure, a first set of coacting upper and lower shaping rollers mounted for rotation on the support structure, said upper roller having a peripheral concave section and said lower roller having a peripheral convex section disposed in close proximity to and coacting with said concave section to crease the sheet material along spaced parallel lines to form corners between the bottom and sides convergent to the bottom of the gutter and forming an upturned concave shape in an intermediate portion of the sheet material between the parallel crease lines corresponding to the bottom of the gutter as the sheet material is passed therethrough, a plurality of succeeding sets of upper and lower shaping rollers mounted for rotation on the support structure and disposed at spaced intervals therealong, the upper roller of each succeeding set having a peripheral concave section and the lower roller of each succeeding set having a peripheral convex section coacting with an associated concave section, said first and succeeding concave and convex sections being aligned longitudinally in the direction of travel of the sheet material to maintain the upturned concave shape in the sheet material during its progressive movement therebetween, said peripheral concave and convex sections of said first and succeeding rollers arranged successively along a parabolic curve decreasing in elevation above the lowest point on the curve toward the lowest point in proportion to the square of the fraction of the total longitudinal distance along the curve from the lowest point, and convergent guide means in a receiving relation to the material proceeding from the last of said succeeding sets of upper and lower rollers to engage the side portions of the sheet material passing therethrough and turn the side portions inwardly toward one another' to essentially flatten said intermediate portion.

2. In a roll-forming machine as set forth in claim 1 wherein each of said lower rollers has a divergent peripheral section extending axially from its associated convex section and each said upper roller has a convergent peripheral section extending axially from is concave peripheral section to turn the sheet material at an angle to form the corner along the crease line on the ogee side of the gutter.

3. In a roll-forming machine as set forth in claim 2 wherein the upper and lower rollers of the first and one successive set have generally S-shaped peripheral sections extending axially of their associated convergent and divergent peripheral sections for forming the ogee shape in one side of the gutter.

4. In a roll-forming machine as set forth in claim 2 wherein the upper and lower rollers of the third and fourth successive sets have facing bulb-shaped peripheral sections extending axially of their associated convergent and divergent peripheral sections for turning the ogee shape transversely of the intermediate portion forming the bottom of the gutter, said lower bulb-shaped peripheral sections being idlers with respect to an associated convex peripheral section.

S. In a roll-forming machine as set forth in claim 1 wherein said shaping rollers with concave and convex surfaces are succeeded by a series of generally flat upper and lower idler rollers associated with said convergent guide means to assist in further turning the sides of the gutter toward one another to the kfinal shape.

6. In a roll forming machine for forming generally U-shaped gutters having a Hat bottom and sides convergent thereto with an ogee curve and hem in one side thereof from a strip of sheet material, the combination comprising a support structure, a first set of coacting upper and lower shaping rollers mounted for rotation on the support structure, said upper roller having a peripheral concave section and said lower roller having a peripheral convex section disposed in close proximity to and coacting with said concave section, said concave and convex sections being of approximately equal length to crease the sheet material along spaced parallel lines to form corners between the bottom and sides convergent to the bottom of the gutter and forming an upturned concave shape in an intermediate portion of the sheet material between the parallel crease lines corresponding to the bottom of the gutter as the sheet material is passed therethrough, a plurality of succeeding sets of upper and lower shaping rollers mounted for rotation on the support structure and disposed at equally spaced intervals therealong, the upper roller of each succeeding set having a peripheral concave section generally corresponding on length and shape with said first concave section and the lower roller of each succeeding set having a peripheral convex section coacting with an associated concave section and generally corresponding in length and shape to said first convex section, said first and succeeding concave and convex sections being aligned longitudinally in the direction of travel of the sheet material to maintain the upturned concave shape in the sheet material during its progressive movement therebetween, each said set of coacting upper and lower shaping rollers including a shaping section adjacent its section forming the concave shape to simultaneously form a portion of the ogee curve and hem, and convergent guide means in a receiving relation to the material proceeding from the last of said succeeding sets of upper and lower rollers whereby the side portions of the sheet material passing therethrough are turned inwardly toward one another to essentially atten said intermediate portion.

7. In apparatus for roll forming shaped members having at least one corner from a strip of material including support structure, a series of sets of upper and lower shaping rollers arranged successively along a parabolic curve decreasing in elevation from a selected elevation above the lowest point on the curve in proportion to the square of a fraction of the total longitudinal distance along the curve from the lowest point, said rollers being mounted for rotation on the support structure and including means imparting a crease to said strip.

8. In apparatus for roll forming shaped members having at least one corner from a strip of material including support structure, a series of sets of upper and lower shaping rollers mounted for rotation on the support structure and including means imparting a crease to said strip, a first group of said series of spaced sets of peripheral material contact surfaces being arranged successively along a parabolic curve which progressively decreases in slope, and a second group of said series having sets of peripheral material contact surfaces being arranged successively along a flat plane, said parabolic curve following the equation :Ut-x 2 y h xc in a rectangular coordinate system having the origin at the centers of the iirst set of rollers in said first group, h being the maximum height of the curve above the x-axis and, xt being the total longitudinal distance of the curve from origin to the centers ofthe first set of roller sets in said second group.

9. In apparatus for roll forming shaped members as defined in claim 7 wherein said series of sets has second, third and fourth roller sets succeeding a first roller set arranged with their centers located in equal increments of one-fifth the total longitudinal distance of the curve.

10. In apparatus for roll forming shaped members as defined in claim 7 wherein the lower rollers of said series of sets are rotatably journaled in a pair of oppositely disposed elongated support structures arranged on a downward incline and removably secured to adjacent support structures at one end of the apparatus.

11, In apparatus for roll forming shaped members from a strip of material including support structure, a series of upper and lower shaping rollers, said rollers being mounted for rotation on said support structure and adapted to pass a strip of material therebetween, each set having cooperative convex and concave peripheral material contact surfaces, said surfaces being of a substantially uniform width and in alignment successively along the machine for forming -an upturned concave shape in an intermediate portion of the material and moving said shape in an aligned course of travel, convergent guide means succeeding said series of rollers bearing against the side portions of the material for turning said side portions inwardly toward each other to essentially flatten said intermediate portion.

12. In apparatus for roll forming shaped members as defined in claim 11 wherein the radius of curvature of said concave peripheral contact surface is less than said convex contact surface of each set to provide greater gripping of the material at the outer edges of the upper and lower adjacent contact surfaces.

13. In apparatus for roll forming shaped members from a strip of material including support structure, a series of spaced sets of upper and lower shaping rollers having peripheral material contact surfaces of each set arranged successively along a parabolic curve decreasing in elevation above the lowest point on the curve toward the lowest point in proportion to the square of a fraction of the total longitudinal distance from the lowest point, said rollers being mounted for rotation on the support structure and adapted to receive and move a strip of material therebetween, each set having cooperative convex and concave peripheral material contact surfaces, said surfaces being of a substantially uniform width and in alignment successively along the machine for forming and moving an upturned concave shape in an intermediate portion of the material between its side edges, means succeeding said rst group for turning the sides of the material outwardly of the intermediate portion toward each other in a transverse relation to the intermediate portion to essentially flatten said intermediate portion into a ilat bottom and sides at right angles to the bottom.

14. In a method of roll forming shaped members having at least one corner from a flat strip of material, the steps of moving the material downwardly along a parabolic curve decreasing in elevation from a selected elevation above the lowest point on the curve toward the lowest point in proportion to the square of a fraction of the total longitudinal distance along the curve from the lowest point while being shaped and while so doing forming and holding at least one crease in said strip, and then moving the material along a longitudinal course of travel after such curved course reaches the horizontal as it is further being shaped.

15. A method of making metal shapes from a flat strip of material as it is moved along a preselected course of travel comprising the steps of forming an upturned concave shape in an intermediate portion of the material, maintaining said concave shape in the material as at least one side portion of the material between the side edge and the intermediate portion of the material is further being shaped, and turning said one side portion of the material outwardly of said intermediate portion in a direction transversely of the intermediate portion to flatten said intermediate portion.

16. A method of making metal shapes from a dat strip of sheet metal material as it is moved along a preselected course of travel comprising the steps of initially forming a concave shape in an intermediate portion of the strip of material, between its side edges, moving the concave shaped strip downwardly along a parabolic curve decreasing in elevation from a selected elevation above the lowest point on the curve toward the lowest point in proportion to the square of the fraction of the total longitudinal distance along the curve from the lowest point to provide a course of travel which progressively decreased in slope while maintaining said concave shape, flattening said intermediate portion by sharply bending a portion of the material on each side of said intermediate portion toward one another to a position at essentially right angles to said intermediate portion to form a multi-sided shaped member while moving the intermediate portion of the material `al1-ong a at course of travel after said curved course reaches the horizontal.

References Cited UNITED STATES PATENTS Neuman 72-181 X -Ellis et al. 72-181 Gossett et al. 72-181 X Watkins 72-181 X Kane 72--179 Navin 72-181 X Gudmestad 72-181 X Vitense.

FOREIGN PATENTS `Great Britain.

Hunker 72-181 10 MILTON S. MEHR, Primary Examiner

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