US2804905A - Sheet metal flanger of the roller type - Google Patents

Description

Sept. 3, 1957 C. F. ENGEL SHEET METAL FLANGER OF THE ROLLER TYPE Filed March 19, 1954 nvwzzvrox. CHARLES F. ENGEL ATTORNEY SHEET METAL FLAN GER OF THE ROLLER TYPE Charles F. Engel, Randolph County, Eli.

Application March 19, 1954, Serial No. 417,283

16 Claims. (Cl. 153-29) This invention relates to sheet metal flanging machines, and is of particular value for turning flanges on pieces of sheet metal ducts such as are used in heating and airconditioning installations.

Duct work includes many so-called transition sections, as are used, for example, to continue ceiling ducts down under beams. In such sections the duct is usually lowered, broadened and flattened. This requires cheek pieces of reversed curvatures, which must be flanged for attachment to the other duct portions. No tools have heretofore been available by which such pieces could be flanged by even semi-skilled workmen.

A principal object of the present invention is to provide a new method of employing flanging rolls to turn flanges on sheet metal work pieces without guiding, regardless of edge curvature, thus rendering the flanging operation atcnt simple enough to be performed by unskilled help. Other objects include: providing a flanging machine from which work pieces may be readily withdrawn, and one which adapts itself to substantial variations in material thickness and rigidity; eliminating the need for fixed follower rolls; and if any following pressure is to be mechanically applied, then changing the point of application and the amount of follower pressure automatically according to the curvature of the edge of the work piece.

The present invention should be distinguished from flanging machines heretofore in use employing fixed guides on both the inlet and outlet sides of the hanging rolls. In such machines a heavy pressure is exerted against the guide at the outlet side of the rolls as well as the guide at the inlet side. Such machines cannot flange edges of varying or reversing curvature. If such fixed guides are removed, a piece to be flanged must be guided shillfully through the flanging rolls, or else a uniform flange will not be formed.

Utilizing the present invention, however, the sheet material passing through the flanging rolls is guided by the very contour of the sheet edge. ment illustrated, this is accomplished by rolls having margins overlapping substantially in a plane perpendicular to the axes of rotation, the overlapping surfaces being spring-urged toward each other, one surface having a greater coeflicient of friction than the other. A sheet metal work piece pressed between such surfaces will tend to rotate with the roll whose surface has the greater coefiicient of friction, such rotation being opposed by contact of its edge against a fixed wiper guide at the inlet side of the rolls.

While this construction eliminates the need for guiding a work piece, a steadying follower force, to be exerted at the outlet side of the rolls, is usually necessary. Such required force is greater for convex edge curvature than for concave curvature. This phenomenon may be explained, at least in part, as follows:

When a flange is formed on an edge of concave curvature, its outer edge is elongated and permanently set in tension. In contrast, a flange formed on an edge of In the embodiice in which case there appears to be a greater spring-bac tendency to be overcome.

Since follower pressure is to be applied to the edge of the work piece, any change in curvature of the edge will change the necessary point of application of such follower pressure. The total amount of follower pressure to be exerted is usually so little that a semi-skilled operator may exert it merely with his finger. However, the machine herein described includes a follower roll which positions itself automatically and varies its pressure responsive to changes in contour of the piece being flanged. Thus a workman may start the piece to be flanged in the machine and release his hold on it at once, to pick up the next piece.

In the accompanying drawings:

Figure 1 is a plan view of a flanging machine embodying the present invention, showing the work table thereof partly cut away and the follower roll mechanism in one extreme position, the other extreme position being shown in phantom lines.

Figure 2 is an elevational view of the flanging machine shown in Figure 1.

Figure 3 is a fragmentary elevation of the side of the machine opposite that shown in Figure 2.

Figure 4 is a fragmentary vertical section taken along line 4-4 of Figure 2.

Figure 5 is an enlarged fragmentary view taken along line 5-5 of Figure 2.

. Figure 6 is a still further enlarged fragmentary view of the region indicated by line 6-6 of Figure 2.

The drawings illustrate a steel work table, generally designated 11, having a heavy sheet steel table surface 12 and supporting legs 13. Beneath such table surface is mounted a source of rotary power, preferably an electric motor 14 and a V-belt 15, which drives a driven wheel 16 secured on one end of a horizontal shaft 17, the assembly being supported by a shaft support bearing 18 horizontally mounted beneath the table surface 12 on a rigid steel support frame 19. At the end of the shaft 17 opposite the driven wheel 16 is a worm gear 20 which meshes with a worm-driven sprocket 21 secured to the lower end of a principal vertical shaft 22. The general relationship of the parts is shown in Figures 1 and 2, while the principal shaft 22 and the working parts coupled thereto, are shown in section in Figure 4.

Secured to the principal shaft 22 above the sprocket 21 is a driving spur gear 23, which meshes with a driven spur convex curvature is shortened and ?set in compression,

gear 24 of the same pitch and diameter. The latter is secured to and drives a supplementary shaft 25 which is mounted substantially vertically and parallel to the principal shaft 22. The principal shaft 22 is mounted for rotation and supported by the support frame 19 by means of a principal vertical bushing 26 grasped within a principal outer cylinder 27. The cylinder 27 is maintained in place in aligned bores of the upper and lower support blocks 28, 28', which also support the supplementary shaft 25 in a second pair of aligned bores by means of a supplementary outer cylinder 29 and supplementary support bushing 30. The supplementary outer cylinder 29 is supported in the upper and lower support blocks 28, 28 with a limited amount of clearance, and its alignment is adjustable by means of two sets of alignment bolts 31 and stop nuts 32 arranged at ninety degrees from each other.

The upper end of the principal shaft 22 extends through and terminates immediately above the table surface 12 within a principal flanging roll generally designated 33 securely mounted thereon. This roll 33 has a knurled or coined perimeter roll surface 34 which, in the embodiment shown, is substantially cylindrical. The upper end surface 35 of the roll 33 has a similarly tooled outer margin 36.

Secured to the principal shaft 22 immediately beneath the principal flanging roll 33, is a subjacent collar 37 having a collar rim 38 which extends radially outward im mediately subjacent the perimeter roll surface 34 of the principal flanging roll 33. This portion of the collar rim 38 is smooth, in contrast to the perimeter roll surface 34 of the principal flangingroll 33, for which reason it is more readily made as a separate collar rather than integral with the roll 33'.

The upper end of the supplementary shaft 25' likewise extends through a bore in the table surface 12, and to it is secured a supplemental flanging roll 39,. having asmooth perimeter surface 40 normally held immediately above the surface 12. The smooth perimeter surface 40 is substantially cylindrical. Its radius is substantially the same as that of the coined perimeter roll surface 34 of the principal flanging roll 33. As shown in Figure 4, its lower edge is normally adjacent the upper surface of the collar rim 39 on the principal shaft 22. At its upper edge protrudes a radially-enlarged superjacent portion 41, which presents downward a substantially horizontal, smoothly machined, overlapping rim'surface 42. This overlaps the upper surface 35 of the principal flanging roll 33 a distance less than the latters radius, and is normally held closely adjacent it, separated by the thickness of the sheet material to be flanged.

The supplementary shaft 25 is so mounted in the supplementary support bushing 30 as to permit not only rotation but also axial sliding movement therein. In this description, the phrase normally held refers to the position during the flanging operation, which is its most downward position. The supplementary shaft 25 is held in this downward position by a compression spring 43, which is positioned coiled around the supplementary shaft 25 and maintained in compression between the upper side surface of the driven spur gear 24 and the lower end of the supplementary outer cylinder 29. Clearance between the overlapping rim surface 42 of the supplemental flanging roll 39 and the upper end surface 35 of the principal hanging roll 33 is adjustable by means of the shaftbottoming bolt and set screw 44, 44 which are mounted on a portion of the support frame 19 extending therebeneath, as shown in Figure 3. The lower end of the supplementary shaft 25 is reduced in diameter so as to penetrate and be supported by a lift bearing 45, as shown in Figure 4, which in turn is mounted in a support yoke 46. This yoke 46 is pinned between the tines of a lift fork 47 having a fulcrum pivot 48 through the forward portion of the support frame 19, as shown in Figure 3.

The table surface 12 has a comma-shaped cutout 49, as shown in Figure 5. Of the cutout 49, the circular portion 50 is of sufficient diameter to accommodate the collar rim 38 beneath the principal fianging roll 33. Slotted outward therefrom, and extending any distance from say forty-five degrees to one hundred twenty degrees in an arcuate path centered about the supplementary shaft 25, is the comma-tail cutout portion 51, adapted topermit the swinging about the supplementary shaft 25 of a follower roll 52 hereinafter described.

Beneath the supplemental flanging roll 39 and the table surface 12, a follower control sector 53 (preferably made of two thicknesses of sheet-metal spot welded together) is mounted for limited rotary movement with reference to the supplementary shaft 25. At the same radial distance from said shaft as the center of the path of the comma-shaped cutout 49, there is mounted in the control sector53 an upstanding vertical follower pivot 54, which stantially this position when flanging sheet metal work pieces having convex curvature of radius nearly as small as the radius of the principal flanging roll 33.

The control sector 53 has a grooved .arcuate edge 56 which guidingly accommodates a control cable 57 pinned to the control sector 53 at that end of the arcuate edge 56 farthest removed from the principal flanging roll 33. The positions of the follower roll 52, control sector 53 and the control cable 57 for forming a flange on a convex curved edge of small radius, are shown in solid lines in Figure 1; their positions for hanging edges having concave curvature of small radius are shown in Figure l in phantom lines. For larger curvatures and straight edges, the position assumed by these elements will be somewhat between the two extremes shown in Figure l.

The control cable 57 leads in a path nearly tangential to the sectors arcuate edge 56, over a pulley 58, located beneath the table surface 12 adjacent its edge, as shown in Figure l, downward to the middle of a downward-e tending trolley clevis 59 mounting a trolley Wheel 60, which rolls along a control bar 61. One of the ends of the control bar 61 is mounted on a horizontal pivot 62 secured to one of the table legs 13 at a height somewhat between the down position of the control bar 61, as shown in Figure 2 in solid lines, and its up position, as shown in phantom lines. These positions correspond to the two extreme positions of the control sector 53, shown in solid and phantom lines, respectively, in Figure 1. An adjustable stop collar 63 on the control bar 61 limits the permissible movement of the trolley clevis 59 toward the pivot 62, and a movable weight 64 having a set screw 65 is positioned at a selected distance along the control bar 61 on the other side of the trolley clevis S9, limiting its permissible movement away from the pivot 62.

The directions of movement of the principal flanging roll 33 and supplemental hanging roll 39 are shown by the arrows in Figure 5, from which it is evident that the follower roll 52 lies at the outlet side of the flanging rolls mentioned. Positioned at the inlet side thereof, and extending partly under the superjacent rim portion 41 of the supplemental fiangiug roll 39, is a wiper guide abut; meat 66 securely mounted to the upper side of the table surface 12 and having a somewhat concave wiper edge 67 which extends from said table surface 12 upward to a point approximately as high as the upper end surface 35 of the. principal flanging roll 33. While the precise posi tioning of the wiper guide 66 is partly a matter of choice and experience, its wiper edge 67 leads inward to the flanging rolls 33, 39 fairly near the line of common tan gency thereof.

Secured to the edge of the work table 11 and having its upper margin in the plane of surface 12, is a flange starter block 68 having a vertical notch 69 extending downward from the table surface 12 a depth equal to the depth of the flange to be formed. Before inserting a piece of sheet metal into the flanging machine, its cornet is inserted into the notch 69 and the body of the sheet metal piece is then bent over onto the table surface 12. After a flange has been so started on the work piece, it is ready for feeding into the flanging machine. I

With the power engaged to drive the driven wheel 16; and the hanging rolls 33, 39 turning in the directions indicated in Figure 5, the work piece with such started flange is fed into the machine in the following manner: the work piece is inserted so that its started flange is aligned for entrance between the perimeter roll surfaces 34, 40 of the said fianging rolls 33, 39; and the side of the body portion of the work piece toward which the started flange has been bent is laid superjacent the upper end surface 35 of the principal flanging roll 33. The started flange on the work piece is brought adjacent the concave wiper edge 67 of the wiper guide 66. Even before its started flange enters between the said perimeter roll surfaces 34,

40, its body portion is engaged and guided by and between the tooled outer margin 36 of the principal flanging roll ,33. and the. smoothly machined overlapping rim surface 42 of the superjacent portion 41 of the supplemental flanging roll 39. The started flange of the sheet metal work piece is then drawn between the perimeter roll surface 34 of the principal flanging roll 33 and the perimeter surface 40 of the supplemental flanging roll 39.

One novel feature is the overlapping smooth rim surface 42, urged by the spring 43, to press the work piece tightly against the tooled outer margin 36 of the principal flanging roll 33. The tooled margin 36 has a substantially greater coeflicient of friction in rotation than does the smooth rim surface 42. As a result, a tendency to rotate with the principal shaft 22 will be imparted to such work piece; and this is resisted by the wiper edge 67. The tendency to rotate steers the work piece so that, regardless of changes in edge curvature, it is pressed securely against the wiper guide 66. The reacting force, exerted by the wiper edge 67 against the edge of the work piece, bends it as it passes between the said perimeter roll surfaces 34, 40, where the flanging operation is completed.

The shaft-bottoming bolt and set screw 44, 44 at the base of the supplementary shaft 25, permit adjustment of the flanging rolls 33, 39 for material thickness.

The alignment bolts 31 and stop nuts 32 may be used to make slight adjustments in the alignment of the supplementary shaft 25. This alignment serves two purposes: to provide spacing between the perimeter roll surfaces 34, 40, and also to effect a slight degree of sideward tilt to bring the overlapping rim surface 42 on the inlet side of the flanging rolls 33, 39 slightly closer to the upper end surface 35 than on the outlet side. Both these adjustments affect the feed of sheet metal work pieces into the flanging machine.

As was indicated in the general discussion preceding this detailed description, the mechanism so far described eliminates any need for guiding a work piece. With some of the lighter gauge metals, the operator should be cautioned to remove his hands from the work piece as soon as it is engaged between the flanging rolls 33, 39, otherwise the operator may inadvertently restrain the free self-steering movement of the work piece through the flanging machine and interfere with its accurate flanging.

At the outlet side of the flanging rolls 33, 39, a follower force is exerted against the outer side of the formed flange. I have indicated that the force required is greater for edges of convex curvature, and decreases as the radius increases. If the edge curvature is concave, the required follower force is lessened. For straight pieces, some intermediate amount of force is required.

Follower force is exerted by the follower roll 52, which is held against the formed flange of a work piece as it emerges from the flanging rolls 33, 39. The force is derived from the weighted control bar 61, and varies in magnitude as the bar 61 responds to the position of the follower roll 52. With the follower roll 52 pressing against a flanged convex edge having a small radius, its perimeter will be close to the principal flanging roll 33, as in Figure 5, and the control bar 61 will be in the downward position, as shown in Figure 2. In such position the trolley 59 at the lower end of the cable 57 will have rolled toward the pivot 62, against the adjustable stop collar 63. Being relatively close to the horizontal pivot 62, the trolley 59 will be subjected to a relatively large force in order to balance the weighted control bar 61. In this manner, a relatively large force is exerted by the follower roll when in position near the principal flanging roll, which position it will assume automatically when ever the edge against which it bears is convex.

If the edge curvature should change to concave, the follower roll 52 will be forced farther away from the principal flanging roll 33 to approach the extreme position shown in phantom lines in Figure 1. In such extreme position the flanging machine will flange edges having concave curvature of as small radius as the radius of the supptementary flanging roll 39.

Referring to Figure 2, the position of the weighted control bar 61 for forming such small concave-curved edges is shown in phantom lines. The trolley 59 is shown to have moved along the control bar 61 outward from the pivot 62 to a point adjacent the weight 64 (whose position is adjustable for variations in material strength and gauge). In the position shown in phantom lines, a much smaller force in the control cable 57 will balance the moment of the weighted bar 61 about its pivot 62. Hence, in following a flanged edge having concave curvature, the follower roll 52 will press against such edge with a sub" stantially lesser force than in following a convex edge.

I have previously mentioned that the entire follower mechanism, whose operation has just been described, may be dispensed with by a workman possessing a degree of skill, who may exert a follower pressure with his fingers against the piece as it emerges on the outlet side of the flanging rolls 33, 39. To vary such force with edge curvature, in an attempt to duplicate the results of the follower mechanism hereof, might seem to call for unusual effort. In practice, it has proved to be not difficult; far less exacting, for example, than the skill which was formerly required to guide a work piece through flanging rolls. This is because the guiding function is handled entirely mechanically, and therefore follower pressure is of secondary importance.

The depth of flanging is controlled by the collar rim 38; as the metal edge is flanged over sufliciently to contact this rim, its reaction against such bent edge prevents overflanging. Should the flange formed be uneven, or should the work piece be accidentally dislodged from the machine, the piece may be reinserted, and a second or third pass through the machine will re-work the flanged edge to correct the initial error.

If it is desired to remove the work piece from the flanger at any time during the flanging operation, this may be done by pressing downward the handle of the lift fork 47. The support yoke 46 and lift bearing 45 therein will thereby raise the supplementary shaft 25; and the supplementary flanging roll 39 will be thrust upward, as shown in Figure 3, separating its surfaces sufficiently from the principal flanging roll to permit easy removal of such work piece.

The mechanism described represents a substantial advance, not only insofar as it accommodates pieces of reversing curvature, but so completely takes charge of the operation that the operator has nothing to do other than start the piece into the machine. While a relatively long work piece is progressing through the machine, the operator may leave it to pick up another work piece to be flanged.

Other embodiments of the inventive principles herein disclosed will be apparent to those skilled in the art. Accordingly, the present invention is to be considered as fully co-extensive with the inventive principles herein disclosed.

I claim:

1. A flanging machine for sheet metal work pieces, comprising a principal flanging roll mounted on the end of a first shaft, its end surface opposite the shaft being substantially perpendicular to the shaft axis, the said roll further having a perimeter roll surface at a flanging angle to the said end surface, further comprising a supplementary flanging roll, rotatably mounted adjacent the principal roll and having a perimeter roll surface adapted for flanging sheet metal in cooperation with the said perimeter surface of the principal roll, the said supplementary roll further having a rim overlapping the said end surface of the principal roll and having a lesser coeflicient of friction, means for exerting pressure between the said rim and the said end surface whereby to grasp a sheet metal piece, means for driving the principal roll rotatively whereby to propel such sheet metal piece through the flanging rolls, the principal roll being by said means rotated in one sense by which is established an inlet side and an outlet side, a tendency to rotate in the same sense being imparted to such. sheet metal work piece by the greater coeflicient of friction of the principal roll, and an edge guide abutment adjacent the inlet side of the said fianging rolls and adapted to oppose such rotative tendency and thereby guide such sheet metal piece through the rolls regardless of variation in curvature of its edge.

2. A fianging machine for sheet metal. work' pieces, comprising a principal fianging roll mounted on the end of a first shaft, its end surface opposite the shaft being substantially perpendicular to the shaft axis, the said roll further having a perimeter roll surface at a fianging angle tothe said end surface, further comprising a supplementary fianging roll, rotatably mounted and having a perimeter roll surface adapted for fianging sheet metal in cooperation with the said perimeter surface of the principal roll, the said supplementary roll further having a rim overlapping the said end surface of the principal roll, the surface of said rim having a lower frictional coeflicient than the said principal roll end surface, means for exerting pressure between the said rim and the said end surface whereby to grasp a sheet metal piece and impart to it a tendency to adhere frictionally to and rotate with the principal roll, means for driving the principal roll ,rotatively in one sense, and a guide abutment adjacent a line substantially tangential to the said flanging rolls and adapted to stop the edge of such sheet metal piece from rotation and thereby guide such piece through the fianging rolls.

3. A fianging machine as defined in claim 1, together with means for separating the fianging rolls to permit the insertion of such a sheet metal piece between the rim of the supplementary fianging roll and the said end surface of the principal fianging roll with the edge margin of such sheet metal piece engaged between the perimeter roll surfaces of the said fianging rolls.

4. A fianging machine as defined in claim 1, together with a self-positioning follower at the outlet side of said fianging rolls, the said follower being pressure-urged against the outer side of the flange so formed.

5. A fianging machine as defined in claim 4, together wtih means to increase the pressure of said follower as it nears the side of the principal fianging roll and to decrease such pressure as it is held farther therefrom.

6. A flanging machine for sheet metal work pieces, comprising a principal fianging roll mounted on the end of a first shaft, the surface of its end opposite the shaft being tooled for increased surface friction in a rotary direction, said roll further having a perimeter roll surface at an angle to the tooled surface, a supplementary fianging roll mounted on a second shaft, the axes of said shafts lying substantially in a plane, said supplementary roll having a perimeter roll surface adapted for fianging sheet metal in cooperation with the perimeter surface of the principal roll, the supplementary roll further having 7 a rim overlapping the tooled end surface of the principal roll, means for separating the said rolls to permit the insertion of a sheet metal piece between the said rim and the said tooled end surface, in such manner that the edge margin of such sheet metal piecelmay be engaged between the perimeter roll surfaces of said principal and supplementary rolls, means for exerting pressure between the said rim and the said tooled end surface whereby to grasp such sheet metal piece and impart to it a tendency to rotate with the principal roll, means for driving the principal and supplementary rolls rotatively in opposite senses by which is established an inlet side and an outlet side for the fianging rolls, and a guide abutment having a flange-starting side leading to the inlet side of said rolls and adapted to stop the edge of such sheet metal piece from rotation and thereby guide such piece through the rolls.

7. A flanging machine as defined in claim 6, together with a follower adapted to exert pressure against the outer side of a flange formed on a work piece passing through the said fianging rolls, and arcuate followerpositioning means adjacent the perimeter roll surface of the supplementary fianging roll at the outlet side of said fianging rolls.

8. A fianging machine according to claim 6, the said driving means including a source of rotary power and power-transmission means driving the said shafts simultaneously.

'9. A fianging machine according to claim 6, the said driving means being so coupled to the said fianging rolls as to drive them at the same perimeter speed.

10. A fianging machine according to claim 1, together with a follower roll at the outlet side of the said fianging rolls, mechanism establishing a follower roll path from -a point adiacent the perimeter roll surface of the principal fianging roll outwardly a greater radial distance therefrom, and mechanism for exerting a force on the follower roll urging it along said follower roll path toward the perimeter roll surface of the principal fianging roll, against the outer side of a flange formed by said fianging rolls on such a work piece.

11. A fianging machine according to claim 10, together with means for lessening such urging force on the follower roll as its radial distance from the principal fianging roll is increased.

1 2. A fianging machine according to claim 6, together with mechanism exerting a force on said follower roll urging it along an arcuate path toward the outer side of a flange formed of such a work piece, and mechanism whereby such force is lessened as the position of said follower roll along the said path is removed increasingly farther from said principal fianging roll and whereby such force is increased as the position of said follower roll along said path approaches closer to said principal fianging roll.

13. A fianging machine for sheet metal work pieces, comprising a frame, a rotatively powered fianging roll mounted thereon having a perimeter surface adapted for fianging and an end surface adjacent which one face of a sheet metal work piece may be pressed, yieldable means for exerting force against the opposite face of such a sheet metal work piece whereby its first-named face is pressed into frictional engagement with the end surface of the fianging roll, the said end surface having a higher coeflicient of friction than that of said force-exerting means whereby to propel such work piece and impart to it a rotative tendency, together with complementary fianging means positioned spacedly adjacent the perimeter surface of the powered fianging roll for admitting and flangingtherebetween the edge of a sheet metal work piece so pressed, and an edge guide mounted to the frame outwardly adjacent a line substantially tangent to the fianging roll at the side thereof from which such a work piece may be admitted, the said edge guide being adapted to abut the work piece edge to be flanged and to oppose the said rotative tendency.

14. The combination with a sheet-fianging mechanism, which comprises a pair of rotatably mounted cylindrical elements arranged and constructed to grip and feed the flange formed on the sheet, means for guiding the adjacent portion of the sheet including a flat end surface on one of said cylindrical elements and a second flat surface located in substantial parallelism to said first named surface and cooperating therewith in guiding the sheet, and a guide abutment having a flange-bending side leading to the inlet of the cylindrical elements, ofa follower mechanism comprising a follower roll located at the outlet of the cylindrical elements and arranged to engage the same side of the flange as the flange-bending side of the guide abutment, a mounting axis for the follower roll, supporting means for said mounting axis maintaining the fol-lower roll at the level of the flange, said supporting means being movable in a plane perpendicular to said axis, and yieldable variable force-exerting means urging said supporting means toward the flange with decreasing force as the follower roll is moved outwardly away from the cylindrical element which has the first named flat end surface and maintaining the follower roll in pressure engagement against such flange.

15. A sheet-flanging mechanism as defined in claim 14, said force-exerting means including a weighted bar hinged at a fulcrum, a trolley wheel movable therealong, and mechanism connecting said trolley wheel and the follower roll supporting means in operating relationship whereby the trolley wheel will be drawn further from the fulcrum as the flange directs the follower roll away from said cylindrical element which has the first-named flat end surface.

16. The combination with a sheet-flanging mechanism, which comprises a pair of rotatably mounted cylindrical elements arranged and constructed to grip and feed the flange formed on the sheet, means for guiding the adjacent portion of the sheet including a flat end surface on one of said cylindrical elements and a second flat surface located in substantial parallelism to said first named surface and cooperating therewith in guiding the sheet, and a guide abutment having a flange-bending side leading to the inlet of the cylindrical elements, of a follower mechanism comprising a follower located at the outlet of the cylindrical elements and arranged to engage the same side of the flange as the flange-bending side of the guide abutment, supporting means for the follower, said supporting means being pivoted swingably about the axis of the other of said cylindrical elements and defining an arcuate path for the follower in a plane substantially at the level of the flange, said arcuate path having a portion nearer the cylindrical element which has the first named flat end surface, in which nearer path portion the follower is accommodated in following flanges of convex curvature, and having a path portion farther therefrom in which the follower is accommodated in the following flanges of concave curvature, and yieldable variable force-exerting means urging the follower toward and maintaining it pressed against the flange with a greater amount of force when the follower is in the nearer path portion and a lesser amount of force when the follower is in the farther path portion.

References Cited in the file of this patent UNITED STATES PATENTS 711.471 Chamber et a1 Oct. 21, 1902 1,359,197 Ray Nov. 16, 1920 1,426,253 Bremer Aug. 15, 1922 1,613,307 Bittner Jan. 4, 1927 1,691,032 Bittner Nov. 13, 1928 1,733,199 Meyers Oct. 29, 1929 2,084,395 Heller June 22, 1937 2,194,114 Embree Mar. 19, 1940 2,308,432 Johnson Ian. 12, 1943 FOREIGN PATENTS 19,847 Great Britain of 1904

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