US2958361A

US2958361A - Apparatus for stretch bending metal strip material

Info

Publication number: US2958361A
Application number: US643431A
Authority: US
Inventors: Hunter Dudley Allison
Original assignee: HK Porter Co Inc
Current assignee: HK Porter Co Inc
Priority date: 1957-03-01
Filing date: 1957-03-01
Publication date: 1960-11-01
Anticipated expiration: 1977-11-01

Description

D. A. HUNTER 7 2,958,361

Nov. 1, 1960 APPARATUS FOR STRETCH BENDING METAL STRIP MATERIAL Filed March 1. 1957 IVE/S,

APPARATUS FOR STRETCH BENDING METAL STRIP MATERIAL Dudley Allison Hunter, Utica, Mich assignor, by mesne assignments, to H. K. Porter Company Inc., Pittsburgh, Pa., a corporation of Delaware Filed Mar. 1, 1957, Ser. No. 643,431

2 Claims. C 153-321 This invention relates generally to bending machines and more particularly to a machine for bending light gauge strip material of irregular cross sectional shapes which must be held in a form during bending.

Previous machines for bending material of the type described above, such as the molding and trim material used on automobiles, have utilized a fixed form. A strip of material to be bent is clamped at one of its ends to one end of the form and a form engaging plug is moved longitudinally of the strip material for progressively 'moving the strip into a bent position against the form.

The plugs are formed of bronze to facilitate their sliding movement along the strip and each particular strip shape of course requires a separate especially shaped plug. The plugs readily wear out during use on such a machine and, therefore, require frequent replacement. Furthermore, overbending is required in using such a machine since some snap back of a bent strip cannot be avoided.

An object of this invention, therefore, is to provide an improved machine .for bending material of the above type.

A further object of this invention is to provide an improved machine for bending strip material which operates a movable form section tostretch the material concurrently with the bending thereof so that substantially no overbending of the strip is required.

Another object of this invention is to provide a bending machine which does not require the bronze plugs described above so that a machine requiring a minimum of maintenance is achieved.

A further object of this invention is to provide a bending machine which includes a form having fixed and movable sections so that bending is readily accomplished by clamping one end of a strip to each of the sections and then moving the movable section into a predetermined position relative to the fixed section.

Still a further object of this invention is to provide a bending machine for strip material which is simple in construction, economical to manufacture, and efiicient in operation in bending such material to a predetermined shape.

Further objects, features and advantages of this invention will become apparent from a consideration of the following description, the appended claims and the accompanying drawing in which:

Fig. 1 is a side elevational view of the bending machine of this invention;

Figs. 2 and 3 are transverse sectional views looking substantially along the lines 2-2 and 3-3, respectively, in Fig. 1; and

Fig. 4 is a fragmentary sectional view of a form section and a cooperating clamp member in the bending machine of this invention.

With reference to the drawing, the bending machine of this invention, indicated generally at 10, is illustrated in Fig. 1 as including a main supporting frame 11 having a base 12 adapted to be floor supported. Mounted in a fixed position on the upper end of the frame 11 is a a en ed Nov. 1, 1960 section 13 of a bending form 15 which determines the ultimate shape of the bent strips removed from the 'ma chine 10. A second section 14 of the form 15 is .supported on a transverse pivot 16, carried by a support 18 arranged at one end of the frame 11, for movement of the section 14 between the dotted and solid line positions illustrated in Fig. 1.

The form 15 is of a constant cross sectional shape to provide a support for a strip material during bending to thus avoid buckling or deforming of the strip. The machine 10 is illustrated in a form adapted for bending a molding strip 20 which is of a substantially C-shape in transverse section (Fig. 4). However, it is to be understood that the machine 10 is not limited to use with any particular shape molding.

The form 15 is formed with a longitudinally extended strip receiving cavity 22 which has a curved bottom surface 24'for supporting the lower side 26 of the strip 20 and an intermediate ledge 28 for supporting the upper edge 30 of the strip 20.

The end 32 of the form section 13 remote from the section 14 is provided with a gauge or stop 34 against which one end of a strip to be bent in the machine 10 is initially positioned to properly locate the strip. The end 32 also carries a clamp assembly, indicated generally at 36 mounted on a supporting structure 38 secured to and extended transversely of the form section 13, The clamp assembly 36 includes a hydraulic piston and cylinder assembly 40 having a cylinder 42 pivotally supported at 44 on an arm 46 carried by the support 38. A piston rod 48 for the assembly 40 is pivotally connected at its terminal end 50 to one end of a link 52 in a toggle mechanism indicated generally at 54.

The mechanism 54 includes in addition to the link 52 which is connected at its opposite end by a pivot 56 to an car 58 on the support 38, a second link 60 which is connected by a pivot 61 at one of its ends to the link 52. At its opposite end the link 60 is connected by a pivot 62 to a guide bar 64 which projects through an upright slot 63 in the support 38 for up and down guided movement therein.

It is apparent that on extension of the piston rod 48, the toggle mechanism 54 is operated to raise the bar 64. Conversely, on retraction of the piston rod 48, the toggle mechanism 54 operates to move the bar 64 downwardly. On its underside, the bar 64 carries a clamp member 66 which, as illustrated in Fig. 4, is of a' shape to conform to the shape of the upper side of the strip 20. Consequently, on engagement of the member 66 with the top side of the strip 20, the strip 20 is securely clampedbetween the form section 13 and the member 66 :and thus firmly maintained within the cavity 22.

A similar clamp assembly 70 is carried on an upright plate 72 secured to the end 74 of the movable form section 14 which is remote from the section 13. The assembly 70 includes a hydraulic cylinder assembly 76 having a piston rod 78 which operates a toggle mechanism 80, like the mechanism 54 described in detail above, to in turn move a bar 82 up and down in a guide slot 81 in the plate 72. The bar 82 carries a clamping member 84 similar to the clamping member 66 previously described.

A strip 20 may thus be clamped at one of its ends to one end of the form section 13 on operation of the assembly 36 and at its opposite end to the remote end 74 sit" the form section 14 on operation of the clamp assem A hydraulic cylinder assembly (Fig. 1) has a cylinder 91 which is supported on a pivot 92 carried by the base 12. An upwardly extended piston rod 94 for the assembly 90 is connected at its upper end by a pivot 96 to a downwardly extended ear 98 on the end 74 of the form section 14. On retraction of the piston rod 94 to the stop position indicated at A in Fig. 1, the form secshown in Fig. 1. In its dotted line position, the section 14 constitutes a downwardly curved extension of the section 13, with the ends 97 and 99 of the sections being positioned adjacent each other.

The specific shapes of the form sections 13 and 14 is determined by the ultimate bent shape required of the strip 20. Thus, to obtain different bent shapes of the strip 20, different curvatures are provided for the form sections 13 and 14.

In the illustrated embodiment of the invention, the section 13 is only slightly curved, while the curvature of the section 14 is more convex. The'pivotal support 16 for the section 14 is arranged so that when the piston rod 94 is extended, the end 74 of the section 14 is a shorter distance from the end 32 of the section 13 when measured along the length of the strip 20 than when the piston rod 94 is retracted to move the section 14 to the dotted line position illustrated in Fig. 1. Accordingly, on movement of the section 14 from its solid to its dotted line position, a strip 20 clamped to the form by the clamp assemblies 36 and 70, in addition to being bent so as to conform to the shape of the sections 13 and 14, is also stretched. As a result, the bend of the strip has a tendency to be set in the strip so that only a minimum of spring back of the strip 20 toward its initial straight disposition takes place. The machine 10 is thus readily operable to quickly bend the strip 20 to the desired shape.

The control mechanism for operating the hydraulic cylinder assemblies 36, 70 and 90 is preferably centrally located so that the operator of the machine can handle the strips 20 and operate the cylinder assemblies from a single location. Since the machine does not require any parts resembling the previously used bronze plugs, a minimum of maintenance is required for the machine so that it can be continuously operated over long periods of time without shut-down to thus increase the production of which the machine is capable.

Although the invention has been described with respect to a preferred embodiment thereof, it is to be understood that it is not to be so limited, since changes can be made therein which are within the scope of the invention as defined by the appended claims.

What is claimed is:

1. In a machine for bending strip material to predetermined shapes, a main frame, a form for determining the final shape of the strip of material bent on said machine, said form comprising a first curved form section mounted on said frame in fixed relation thereto and a second curved form section generally of substantially greater curvature than said first form section, means mounting said second form section on said frame for pivotal movement relative to said first form section between a starting position and a finished position and cooperating with said first section when in said finished position to provide a substantially continuous form surface for supporting said strip of material, the adjacent ends of said first and second form sections being disposed in closely spaced parallel relation when said second section is in said finished position, the end surface of said first form section intersecting the outer curved surface of said form at an acute angle and the adjacent end surface of said second form section intersecting the outer curved surface of the form at a supplementary obtuse angle when said second section is in said finished position, said means mounting said second form section forpivotal movement about an axis being disposed between the ends of said second form section and inwardly of the curved outer surface thereof so as to avoid interference between said adjacent ends during said pivotal movement, clamp means individual to said sections and mounted at the remote ends thereof for releasably clamping said strip of material to said remote ends of said form sections, and means mounted on said frame for moving said second form section from said starting position to said finished position, said second form section being effective during pivotal movement from said starting position to said finished position to progressively elongate the strip of material.

2. In a machine for stretch bending a strip of metal moulding to a predetermined shape, a main frame, a form for determining the final shape of the strip of material bent on said machine and adapted to support said strip in said predetermined shape, said form comprising a first section mounted on said frame in fixed relation thereto and having relatively slight curvature, a second form section generally of substantially greater curvature than said first section, means mounting said second form section on said frame for pivotal movement relative thereto between a first position in which it co-operates with said first form section to provide a substantially continuous curved form and a second position in which a tangent to said second form section at the end thereof remote from said first form section is substantially tangent to said first form section at a point spaced from the end of said first form section adjacent said second form section, a clamp mounted on said first form section at said end thereof, another clamp mounted on said second section at said end thereof, each of said clampscomprising a jaw adapted to fit a portion of said strip and co operate with said form for holding one end of a said strip against movement relative to the form, means mounting said jaw on said form for movement toward and away from said form, and means for moving said jaw toward said form to clamp one end of a said strip to said form and hold it against movement relative thereto, said means pivotally mounting said second form section being so disposed relative to said first form section that the distance between said clamps measured along a said strip progressively increases during movement of said second form section from said second position to said first position, and means mounted on said frame for moving said second form section between said first and second positions, said means pivotally mounting said second form section supporting said second form section for pivotal movement about an axis disposed between the ends of said second form section and inwardly of the curved outer surface thereof.

References Cited in the file of this patent UNITED STATES PATENTS 281,640 Mosler July 17, 1883 975,184 Walsh Nov. 8, 1910 1,710,261 Kellogg Apr. 23, 1929 1,804,384 Miller May 5, 1931 2,457,483 Martin Dec. 28, 1948 2,476,556 Maize July 19, 1949 2,649,129 Schlank Aug. 18, 1953