US2960140A - Deformable forming elements for shaping metal sheets drawn over the elements - Google Patents

Description

Nov. 15, 1960 F. ANDERSON 2,960,140 DEFORMABLE FORMING ELEMENTS FOR SHAPING METAL SHEETS DRAWN OVER THE ELEMENTS Original Filed Feb. a, 1955 3 Sheets-Sheet 1 Nov. 15, 1960 F. ANDERSON 2,960,140

DEFORMABLE FORMING ELEMENTS FOR SHAPING METAL SHEETS DRAWN OVER THE ELEMENTS 3 Sheets-She t 2 Original Filed Feb. 8, 1955 9 v //v I/E/VTOR FPO/ MAN ANDERSON ,q TTOR/VE Y Nov. 15, 1960.

F. ANDERSON 2,960,140 UEFORMABLE FORMING ELEMENTS FOR SHAPING METAL SHEETS DRAWN OVER THE ELEMENTS 3 Sheets-Sheet 3 Original Filed Feb. 8, 1955 FIFO/INA A/VOFEJON ATTORNEY United States Patent DEFORMAELE FORMING ELEMENTS FOR SHAPING METAL SHEETS DRAWN OVER THE ELEMENTS Frohman Anderson, 3320 S. 5th St., Las Vegas, Nev.

Original application Feb. 8, 19'55, Ser. No. 486,773. Divided and this application Oct. 10, 1957, Ser. No. 689,437

4 Claims. (Cl. 153-42 This application is a division of pending application Serial No. 486,773, filed February 8, 1955, now Patent No. 2,851,080, which relates to apparatus for forming metal sheets with compound curvature by drawing or pulling the sheets over forming elements. Such machines are known as forming-by-drawing machines, the principle being illustrated in United States Patent No. 2,480,826, issued September 6, 1949.

In accordance with this principle, the sheet is drawn over stepped forming elements which provide contact lines where the sheet changes direction differing in g'eo' metrical shape and the sheet is subjected to a tensile stress beyond its elastic limit. Consequently there are progressively introduced into the sheet longitudinal increments determined by the difference in geometrical shape of the forming elements and by the length of the material between the forming elements, that is, by the separation between the elements.

Forming-by-drawing involves three stages of operation upon a sheet being drawn through the machine, the first two stages coacting to impart the differential longitudinal stretch to the sheet, and the third stage acting to proportion the relative surface longitudinal dimensions to the inherent longitudinal curvature of the sheet introduced by the differential longitudinal stretching.

A restraining force is applied to the sheets as they are drawn over the forming elements, sufficient to subject the sheets to tensile strength beyond their yield point. The first stage provides the restraining or hold-back force and it is therefore known as the hold-back stage. For this purpose it is composed of two opposing members which may be caused to impose more or less of a drag on the sheet.

This first stage determines the general path of movement of the sheet and provides a slot through which the sheet is drawn. From thefirst stage the sheet is drawn over the second stage forming element having a different geometrical shape from that of the first stage and being disposed at a different level from that of the first stage. For simplicity, the first stage may be thought of as providing a straight work face and the second or drawover stage having a curved work face.

The third stage controls the tendency of the sheet to coil up which is produced by the movement of the sheet over the work face of the second stage. It corresponds in shape to that of the second stage but is vertically offset therefrom, being at a level between that of the first and second stages with its work face opposed to that of the second stage. The three stages are therefore in stepped relation to each other.

As above stated, the curvature imparted to a sheet depends in part upon the difference in geometrical shape of the forming elements. Therefore, with a given set of.

inflexible forming elements having unalterable shapes, variations in sheet profiles which can be drawn are con fined to such relative adjustments of position of the forming elements as the machine may provide. Consequently with such inflexible forming elements a great number of the usual commercial needs.

It is an object of this invention to provide a flexible forming element which is susceptible of easy adjustment so as to change its contour and which is, nevertheless, sufliciently rigid to withstand the forces to which it will be subjected in use without deformation.

For this purpose, the invention comprehends structural features of forming elements which will now be described by reference to the accompanying drawings which illustrate one embodiment of the invention. 7

Fig. l is a front elevation, partially in section, of the forming portion of a sheet-forming device of the forming-by-drawing type, showing the exit side of the second and third stage mechanisms, with a sheet in section be tween the forming elements and a portion of the draw bench mechanism partially in section. 1

Fig. 2 is a central section on enlarged scale of the forming elements and their immediately associated parts.

Fig. 3 is a transverse vertical section on two planes, the left portion being on line 3X3X of Fig. 2, and the right portion being on line 33 in Figs. 2 and 4.

Fig. 4 is a vertical section on line 44 of Fig. 3.

It is practical to employ a straight line first stage work'- engaging element and to adjust the second and third stage work-engaging elements to desired curvatures or contours relative to the straight line first stage. Therefore, in practice, only the second and third stage forming elements are flexible and adjustable and the three stages will be so shown and described, although it will be understood that the first stage elements may also be made deformable.

Fig. 1 illustrates the general assembly of the second and third stage mechanisms, the forming elements themselves being only generally shown in this figure, the detailed construction in embodiment of the invention being illustrated in the other figures.

Fig. 2 shows the general relation of the three stages, a sheet S being shown as passing through the .forrning elements. The first or hold-back stage is on the right and the second and third stages are on the left in that figure, the sheet passing from right to left. I

The first stage mechanism consists of an upper assembly U1 and a lower assembly L1 between which the sheet is drawn with provision to raise and lower the upper assembly. At their exit side these assemblies have interengaging convolute work-engaging members to impose the'desired restraint upon the sheet, with smoothing plates im mediately behind the convolute members. These members determine the path of movement of the sheet and, being straight line members, the sheet emerges from them in a horizontal plane.

From the first stage the sheet is drawn downwardly over the work face of the second stage forming element which is carried by the second stage assembly shown in front elevation in Fig. 1 and indicated by the reference character 2nd in Fig. 2. After passing over the second stage forming element the sheet is drawn upwardly over the third stage forming element which is carried by the third stage assembly also shown in front elevation in Fig. 1 and indicated by the reference character 3rd in Fig. 2.

The forming mechanism consisting of the three stages is contained between two upright plates 10 and 11 shown in front edge view in Fig. l. Spanning these uprights in fixed relationship at the top is bar 12 and supported thereby through toggles is a two-part ram which carries the second stage forming element and is raised and lowered by means of the toggles which are operated by a hydraulic cylinder and piston, being guided by gibs on the uprights. The two parts of the ram are upper bar 13 and lower element carrying bar 14 which are connected by turnbuckles 15, one near each end. Toggles 16 connect the fixed bar 12 and bar 13 of the ram, the toggle joints being connected by bar 17. The toggles are operated by hydraulic cylinder 18 supported on brackets 19 on uprightll. .The piston of the cylinder is connected to the end of toggle-operating bar 17 by piston rod 20. The weight of the two-part ram is counterbalanced by a weight 21 which is connected to bar 13 by a link and a lever pivoted on fixed bar 12.

, The lower ram bar 14 is shaped with its intermediate portion above its ends 14a to provide admission for jaws between the depending ends to grip and pull the leading edge of the sheet. The ends of the lower bar 14 are rounded to allow for tilting which may result from unequal adjustment of the turnbuckles 15. The lower edge portionvof'the ram bar 14 is thinner than the main portion ofthe bar and a forming element designated generally by the numeral 22 is fastened to its rear face.

The body member of the third stage is T-shape, having a cross head portion 23 of a length somewhat less than the space between the uprights and for appearance sake havingits ends covered by plates 24 which occupy the space between the ends of the cross head and the respective upright, and, as shown, provide connections for the pistons of hydraulic motors which have no part in the present invention. Underneath the cross head 23 is a second cross head 25 which is attached to and supports the cross head 23 and has a rearwardly extending leg portion 26. Power means, not shown, are connected to the leg portion 26 to move the third stage assembly horizontally forward and back relative to the second stage. The top cross head 23 of the third stage has the third stage forming element, which is designated generally by the numeral 27, fastened to its rear face.

, It is the second and the third stage forming elements which are made deformable and reference is made to Figs. 2, 3 and 4 for the details of the construction chosen for illustration. The second and third stage elements are complementary in shape, the working face of the second stage element being, in the adjustment shown, convexly curved to a constant radius from end to end, and the working face of the third stage element being concavely curved to the same radius.

I The improved forming element has a hardened steel work face comprising a strip of suitable alloy which is backed by a body of soft steel to which it is secured and which istransversely slotted at close intervals, together with means to applylocal pressures to open or close the slots and flex the unslotted portion of the soft steel body which Serves as a backing for the hardened steel face,

:with the result that the work face flexes with the softer steel backing.

Both of the second and third stage elements are of two parts, a fixed abutment member which has a dovetail connection with the holder member, and a slotted work engaging member possessing the hardened work face and clamped to the abutment member "and having adjusting means carried by the abutment member and acting upon the slotted member to exert deforming force thereon.

, The second stage forming element will first be 'described. The abutment member 28 of the two-part element is a full length channel-shape member having a dovetail tongue on its back face which is received in a complementary groove along the inner face of the thinned bottom edge portion of ram 14 and is secured by wedge member 29. The work engaging member 30 of the twopart element is also a full length channel-shape member that has its channel face opposing that of the abutment member 28 but offset so that its upper flange is disposed between the flanges of the abutment member and the bottom flange of the abutment member is disposed within the channel of the work-engaging member. A clamp plate 31 bears against the rear face of the work-engaging member 30 and is secured to the abutment member 28 by two rows of screws 32 the upper row of which is above the top flange of the work-engaging member and the from the end opposite the work face into the flange having the work face. The slot is a single slot down to the lower flange where it branches into two slots diverging at about and continuing a substantial distance into the flange, leaving an unslotted strip of the softer steel as 1a backing for the hardened work face, such strip being thin enough to be substantially flexible. Those slots which have the screws 32 passing through them have widened portions 33a to accommodate the screws which widened portions are of sufficient length to permit of the relative longitudinal adjustment of the workengaging member, as will be described. The slots diverge somewhat toward their open ends so as to provide ample room for considerable convex curvature of the work face without the slotsclosing The slots are in practice spaced about an inch and a quarter.

Flexing of the work face is done by exerting pressure upon the inner face of one or the other of the flanges of the work-engaging member. For this purpose a series of longitudinally extensible adjusting screws are located in'screw-threaded holes through the flange of the abutment member which is disposed within the channel of the work-engaging member.

Each of the screws shown is composed of two telescopic parts. An external screw member 34 screws into the hole tapped in the flange of the abutment member and is hollow and internally screw-threaded. It is somewhat shorter than the distance between the inner faces of the flanges of the work engaging member and has one end squared to receive a tool and the other end concavely cupped to receive a bearing button 35 having a spherical under side to fit and rock in the cupped end of the external screw member 34, the purpose of the bearing button being to assure a full parallel surface contact between the end of the screw and the flange surface.

A smaller screw 36 having a hexagon head screws into the internal threaded bore of the larger screw. If it is desired to use a screw to exert upward pressure, the

smaller screw 36 will first be screwed into the larger screw section to raise its head off the lower flange of ithe work-engaging member a distance as near as can be judged equal to that which the section of working face at that point is to be raised. Then with screw 36 held against rotation, the tool is placed on the square end of the larger screw section and that section is screwed up until the bottom flange again engages the head of the smaller screw. When trial shows that the right contour is obtained, the screws are given a final expansive turn to assure that the composite screw braces the workengaging flange against the opposite flange. In this way the hardened work face is rigidly supported against any deformation under the stress of the work drawing force.

The third stage forming element is in all substantial respects a duplicate of the second stage element, being reversely arranged. The corresponding parts are there- 'fore identified with the same numerals with a prime mark.

The chief difference between the lower and upper forming elements is in the shape of the work face bearing flange and in the cross-sectional shape of the hardened work-engaging strip. It will be noticed that the forward face of the flangeis beveled off on the lower element andth'at the hardened strip is oblong in cross-section and set into a longitudinal groove, being narrower than the width of the flange, while the strip on the second stage element covers the entire face of the flangeand has ajwo'rk ridge at the entrance edge.

Other embodiments of the invention will readily occur to those skilled in the art without departing from the scope of the invention as defined in the following claims:

What is claimed is:

1. In a forming-by drawing machine having a first and second stage of operation and means to pull a work sheet through the two stages in succession, a forming element for each stage each of which forming elements has a work sheet engaging face over which the sheet is pulled and the work sheet engaging face of the first stage forming element being non-deformable and having a fixed geometrical contour and the forming element for the second stage being deformable to modify the longitudinal geometrical contour of its worksheet engaging face, said second stage forming element comprising a rigid bar having a flange along one edge and an elongated integral work engaging element channel shaped in cross section and attached to the rigid bar with the flange disposed in the channel and adjustable transversely of the flange, the work engaging element having a flexible continuous integral face along one flanged end disposed at a different level from that of the work sheet engaging face of the first stage and constituting the work sheet engaging face of the second stage, the work engaging element also being slotted at intervals from the other flanged edge to the flange of the said one flanged edge, and adjusting screws disposed between each adjacent pair of the slots and threaded through the flange on the rigid bar and bearing at its ends against the flanges of the work engaging element.

2. The mechanism defined in claim 1 in which the adjusting screws are extensible and are composed of two telescopic parts with one part having internal screw threaded engagement with the other part and the other part having screw threaded engagement with the flange on the rigid bar.

3. The mechanism defined in claim 1 in which the work engaging element of the second stage is composed of relatively soft steel and its work sheet engaging face is a thin strip of hard steel welded to its continuous integral face.

4. In a forming-by-drawing machine having a first, second and third stage of operation and means to pull a Work sheet through the three stages in succession, a forming element for each stage each of which forming elements has a work sheet engaging face over which the sheet is pulled and the Work sheet engaging face of the first stage forming element being non-deformable and having a fixed geometrical contour and the forming elements of the second and third stages being each deformable to modify the longitudinal geometrical contour of their work sheet engaging faces, each of said second and third stage forming elements comprising a rigid bar having a flange along one edge and an elongated integral work engaging element channel shaped in cross section and attached to the respective rigid bar with the flange disposed in the channel and adjustable transversely of the flange, each work engaging element having a flexible continuous integral face along one flanged edge constituting their respective work sheet engaging faces, the work sheet engaging faces of the three forming elements being at different levels and that of the third stage being at a level intermediate those of the first and second stages, the work engaging elements of each of the second and third stages being slotted at intervals from the other flanged edge to the flange of the said one flanged edge and adjusting screws disposed between each adjacent pair of slots and threaded through the flange of the rigid bar of each of the second and third stage work engaging elements and hearing at its ends against the flanges of the respective work engaging element.

References Cited in the file of this patent UNITED STATES PATENTS 453,592 Gardner June 2, 1891 1,251,678 McIntyre Jan. 1, 1918 2,301,960 Lermont et a1 Nov. 17, 1942 2,449,247 Paucek Sept. 14, 1948 2,480,826 Anderson Sept. 6, 1949 FOREIGN PATENTS 432,766 Great Britain Aug. 1, 1935

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