US2927549A - Laminated guerin box - Google Patents

Description

March 8, 1960 c. F. DERBYSHIRE LAMINATED GUERIN'BOX Filed May 18, 1953 IIZIZZZZ:

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United States Patent-* LAMINATED GUERlN BOX Charles F. Derbyshire, Chula Vista, Calif., assignor to Rohr Aircraft Corporation, Chula Vista, Califl, a corporation of California Application May 18, 1953, Serial No. 355,711 3 Claims. (Cl. 113-44) which is supported on a metal pedestal which has the same shape as the opening in the bottom of the box and fits closely within the opening. As the box descends the rubber applies an increasing pressure to the workpiece which causes it to bend and progressively conform to the surface of the die.

-It has been the practice, as illustrated in the above patent, to make the top and sides of the box of a single piece of metal, such as a casting or forging, or to fasten the sides to the top of the box by welding. During the last few years this method has been used for the forming of increasingly larger workpieces and thicker sheet metal with an attendant increase in pressure developed in the rubber. The rubber presses against the sides of the box and develops a shear force which tends to shear the sides from the top of the box and the pressure against the sides induces cantilever type bending stresses in the box which tend to fracture it. It is a main object of this invention to provide a box construction for the rubber which is free of such cantilever induced bending stresses and shear stress.

It is a further object of the invention to provide a slidable connection between the top and sides of the box so that the sides can expand and contract independently of the top under the outward force applied by'the rubber.

A further object is to provide a deep box of great strength made up of a plurality of steel laminations each of which is a single piece of metal and the several laminations being welded together into a unitary structure.

A further object is to provide means for sealing the joint between the sides and top of the box which will prevent the rubber under pressure from creeping between the sides and top and escaping from the area in which it is confined thus causing failure of the press.

Another object is to provide guide pins for guiding the box into proper registry with the pedestal which supports the die or dies.

Further objects will become apparent as the description of the forming press proceeds. For a better understanding of the invention reference is made to the accompanying drawings, in which:

Figure 1 is a view, partly in section on line 1-1 of Figure 3, of a portion of a forming machine embodying the invention;

Figure 2 is a top view of the lower portion of the machine of Figure 1 with the forming die and workpiece removed;

Figure 3 is a top view of a portion of the machine and;

Figure 4 is a sectional view showing the means for securing two portions of the machine together.

.On a stationary base 10 is secured by any suitable means 2,927,549 Pf'tented ll'lar. 8, 196 0 center plate 11 has secured to it a generally rectangular shaped pedestal 15, the vertical sides and top of which are machined smooth. Pedestal 15 supports the forming die 16 and metal sheet 17 which is to be formed to the contour of the curved top face 18 and side face 19 of the die. For simplicity only a single die and workpiece have been shown but it will be understood that a plurality of dies of different shapes may be set on pedestal 15 and a corresponding number of metal sheets bent simultaneously to the shapes of these dies. 7

The movable portion of the forming machine com? prises the ram 20 of a press, the ram being vertically reciprocated in a known manner by means of a fluid actuated piston (not shown). Attached to ram 20 is .a flat plate 21, the plate having along its opposite edges a plurality of slots 22 through which bolts 23 pass, the shanks of the bolts entering threaded holes in the ram.

Attached to plate 21 (see Figs. '3 and 4) by a plurality of Allen head screws 24 is a containing box wall 25 in a manner to permit sliding contact between-the wall and plate. This is secured by. drilling a plurality of holes 26 in the plate and counterboring each hole to provide a shoulder 27 against which a washer 28 disposed under the head of the screw is seated. Each hole 26 is of substantially greater diameter than thediameter of the shank of screw 24 so that a sliding connection is provided between box wall 25 and plate 21 as the wall expands and contracts slightly under the high internal pressure to which it is subjected. The wall shown has straight ends 29 while the front and rear. faces 30 are convexly curved. The box wall is composed'of a plurality. of strong steel laminations welded together, as shown, and welded to the sides of the wall are a pair of lugs 31 which have guide bushings 32 adapted to egage and slide along guide pins 13 as ram 20 descends. The bottom lamination 33 is machined to provide a smooth vertical face 34 of the same shape as the top of pedestal 15 so that face 34 has close telescopic engagement with the pedestal.

A body 35 of resilient, fiowable rubber is packed into the box wall 25, the bottom face of the rubber being a substantial distance above the bottom of wall 25, as shown. The rubber is of approximately 60 Shore test and preferably consists of several horizontal laminations. To prevent the rubber from being squeezed between the.plate 21 and the top lamination and thereby separating portions of the box in which the rubber must be confined, a continuous sealing member 36 in the form of an angle iron has a verticle leg in contact with the inside of the top lamination and a horizontal leg in contact with the bottom face of plate 21, as shown in Figures 1 and 3. Member 36 may be secured to body 25 by any suitable means such as screws (not shown). The several parts of the machine, except rubber body 35, are preferably made of strong steel. Since each lamination is designed to counteract the total outward pressure of the portion of the rubber, body lying within it, the number of laminations can be increased to any desired extent.

To operate the machine the ram 20 is raised to the position shown, die 16 is placed on pedestal 15 and a metal sheet 17 of aluminum, brass or other flexible metal placed on the die. Ram 20 is then slowly lowered and as vertical face 34 of the box wall commences to slide along the vertical face of pedestal 15, the rubber 35 commences to press sheet 17 against die 16 and to bend the sheet. This bending continues as the ram descends, the bottom face of the rubber no longer remaining flat but shaping progressively as the sides of the sheet are bent down into conformance with the sides 19 of the die and against the end of pedestal at the right as the ram continued to descend. In forming many parts on the same die this repeated rubbing together of these surfaces would gradually wear them away. Such sidewise motion of pedestal 15 with reference to flange is efiectively preventedby the cooperative action of the guide pins 13 andbushin'gs 32 which maintain pedestal 15 substantially central within opening 34. After. the workpiece is fully formed, the ram is raised to its top position, the formed workpiece removed from the die and other metal sheets formed in the same manner.

. It has been thepractice, as illustrated in the above 'patent, to make the box wall 25 and plate 21 which enclose the rubber as a one piece forging or casting with the "result that the wall acted as a beam anchored at its upper end. Under the high outward pressure of the rubber, large bendingstresses ofthe cantilever type are set up in the flat plate in the region where it joins the wall-and have caused boxes to fracture in this region so that they could not be used again. Also large shear stresses were set up in'the wall where itjoins the plate, which fur .ther weakened the structure. .By this invention such bending and shear stresses are entirely avoided since at:- plicant's box wall '25 is free to move in and out along "plate 21 as it expands and contracts under the stresses applied internally by the rubber.

.This invention may be embodied in other forms. or carried out in other ways without departing from the spirit-or essential characteristics thereof. The present embodiment of the invention is therefore to be .considered 'as in all respects illustrative and. not restrictive, the scope of the invention being indicated by the appended claims, andall changes which conic within the meaning and range .of equivalency of the claims are intended to be embraced therein.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is: 1. A device for forming a sheet metal blank to the form of a shaped die by-pressure 'from the vertical ram iofapress comprising; a fiat plate composed ofrigid metal,

a plurality of spaced apart detachable fasteners securing the topof said plate continually against the bottom of the, ram, said plate being provided with a plurality of spaced apart vertical bores; a rigid box walldepending deems-19 IQ .j il91t. fliiwl u yifil t orm ng a r s t r' recess, the top of said wall having a plurality of threadedopenings in alignment with. said bores; a plurality of beaded screw fasteners having their shanks disposed in said bores and having their threaded lower ends screwed into said threaded openings to hold the top face of said box wall continually in contact with the bottom face of said plate, the shanks of said headed fasteners being of substantially smaller diameter than said bores to thereby per'rhit limited jr'riov erhiento'f the top face of said boa wall along the bottom face of said plate; a body or resilient fiowable material disposed in said recess, the top of said body being in ehgagerri'entwith said plate and the body having an exposed lower surface at a level above the bottom of said wall; a stationary base under said wall; a pedestal projecting up from said base and having a substantially horizontal top face adapted to support the die and sheet metal. blank resting on'the die, :said box wall and body of resilient material when in raised position being well spaced fr'omthe die to allow ready access to the blank for its rapid, placement on and removal from the die; the lower portion of the. wall being of substantially .the same shape and size as the pedestal :so as to fit =di' rectly-in telescoping relation therewith uponloweringthc press ram whereby loweringthe ram causes 'saidbody of yielding material to be compressed-and restiained'against outward expansion by 'saidplate :and wall and wid first :press said blank against said die by engagement of said lower exposed surface. therewithand upon application 0f further pressure will shape said blank along the die.

,2. .1A forming device as claimed in claim 1.; inzwliich :said box. wall :is composed of a plurality of steel lamina- ,tions welded together and said headed fasteners are 'in threaded engagement with the top lamination only.

3.. A forming :device as claimed .in claim '1; in which {said box Wallis composed eta-plurality of steel lamina- 1tions welded together and the portion 'ofthe wall which is the sameshape and size as :thepedestal consists of 'a smooth vertical face formed-on-only the bottom lamina- Great Britain Mar. 1 2, 1946

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