US1593511A - Method and apparatus for shaping metallic articles - Google Patents

Description

July 20 1926. 1,593,511

J. A. SPENCER METHOD AND APPARATUS FOR SHAPING METALLIC ARTICLES Filed June 29, 1922 Paton ted July 20, 1926.

-UNITED STATES PATENT OFFICE.

JOHN A. SPENCER, OI REVERE, MASSACHUSETTS, ASSIGNOR T SPENCER THERMO- STAT .COHPANY, OF CAMBRIDGE, MASSACHUSETTS, A CORPORATION OF MASSA- OEUBET'IB.

IETHOD AND APPABATUS FOB SHAPING- METALLIC ARTICLES- Application filed June $9, 1922- Serial No. 571,801.

The present invention relates to a method and apparatus for shaping metallic articles and more particularly for shaping relatively thin flat b anks.

e The object of the present invention is to shape previously blanked metallic sheets into a predetermined form without frac turing or otherwise injuring the sheets durin the forming operation.

TVith this object in view a feature of the invention contem lates the provision of cooperating dies 0 dissimilar shape which are designed to initially engage the blank throughout a restricted portion of its area to im art approximately the desired shape and w ich are adapted to positively engage with one another, leaving a cavity of suffioient depth to receive the blank without exerting too great a pressure thereon. This feature of construction is of particular importance when operating upon metallic lanks of relatively soft material which which may vary in thickness, as otherwise a settin of the dies for a relatively thin blank might well cause too great a pressure to be exerted upon a'blank of greater thickness. The invention has particular utility in connection with the shaping of blanks consisting of two metals having dissimilar thermal coeficients of ex ansion and united to form a composite s eet, such blanks varying in thickness owin to irregularities in the thickness of the eet from which they are stamped. A further feature of the present invention consists in the combination with cooperating dies for the production of an arched or cup shaped blank of means for varying the arch or curvature of the blankthroughout the central portion, as desired. The provision of such an adjustment permits the temperature at which the arched blank suddenly flexes to be varied within desired limits. In this connection, it may be stated that blanks of this type are designed to suddenly change shape at predetermined temperature limits and a relatively slight change in arch or curvature of the central portions of the blank permits the temperature point at which change of shape occurs to be varied accordingly.

Still further features of the invention ously blanked out sheets according to the improved method; Fig. 2 is a detail showing a section in elevation of the cooperating dies with the blank engaged there etween,

together with means for varying the curvature of the blank; and Fig. 3 is a detail illustrating one of the blanks formed according'to the improved method.

The illustrated embodiment of the invention is shown more particularly in connection with the formation of a thermostatic disk such as disclosed in the copending application of Spencer, Serial No. 565,255, filed June 1, 1922. This disk is blanked out of a sheet of thermostatic material consisting of two metals having dissimilar thermal coeficients of ex ansion intimately united to form a composite sheet. By shaping such a sheet into a non-develo able surface, which may be an aproximate y spherical surface or a cup shaped surface having a relatively fiat central ortion and an annular rim por tion inclined thereto, it has been found that upon raising the temperature of the blank or thermostatic member to a predetermined point a sudden reversal of curvature takes place. Thereafter, upon reducing the temperature of the blank to a certain lower predetermined point, the blank reverses to the initial shape. As these thermostatic members are formed from flat blanks of sheet material which may be made of relatively soft metals, the shaping of the blank without obtaining a high percentage of discards or rejects presents a considerable problem. According to the present invention, the fiat blank is shaped between cooperating male and female dies, indicated generally at 10 and 12. The female dies is provided with a cavity indicated at 14, whichhas a smooth unbroken curved surface 16, which cal surface 22, as indica The cooperating die 10 is provided with a shapin projection 18 havin a pressing surface, w ich consists of a re atively flat central portion 20 bounded b an annular comclearly in Fig. 2. The inclination of the conical surface 22 is such with respect to the curvature of the surface 16 that as the two d es move together to shape the blank between them the latter is engaged by the die 10 at the unction of the surfaces 20 and 22 and thereby pressed into substantial conformity with the surface 16. By engaging the blank in this manner, the outer peripheral [801131011 of the blank is free to move inwar y within the die cavity 14 without drawing the blank or changing the thickness. In order to prevent the exertion of too great a pressure upon the blank, the cooperating dies 10 and 12 are provided with shouldered portions 24 and 26, which positively engage with one another when the two dies are moved into substantiallv the position shown in Fig. 2 and thereafter prevent the exertion of urther pressure u on the blank, these shouldered portions eing so designed, however, that a suflicient relative movement of the dies to properly shape the blank is permitted. In order to prevent too reat an impact when the dies come toget er, the upper die 10 is preferably reciprocated 1n the usual manner by any suitable form of mechanism and the lower die 12, which is normally stationary, is supported upon a ielding buffer 30, which, as indicated, may formed of rubber or similar material, this yielding buffer being interposed between the lower portion of the die 12 and a fixed ortion, 32 of the machine frame. .It should e understood in this connection that the buffer or other means for supporting the die 12 should have sufficient strength to resist any downward movement of the die 12 until the shouldered portions 24 and 26 positively engage but to thereafter permit movement of the two dies in unison until the stroke of the u per die is completed. The removal of the b ank from the cavity 14 may be conveniently effected by a jet of air, which is projected beneath the blank through an air passage 40, extending through the die 12 into one side of the mold cavity and connected through a pipe 42 with any suitable source of air under pressure (not shown). In this connection it should be understood that the removal of the blank from the die cavity 14 is a relativel simple matter, as the s a ing of the blan reduces the diameter an draws the eripheral ed es of the blank away from t e correspon ing edges of the mold cavity.

It is desirable in the formation of articles of this characterthat the curvature shall be varied in orderto vary the temperature point at which the thermostatic member.

shall change shape and to this end the male die 10 is provided with an adjustable plug member 50 extending down through the male die and havin a lower curved end 52, which engages wit the central portion of the blank and sha it accordingly. B varying the project1on of this lower end 5 the curvature of the central portion of the blank may be accordingly varied; in other words, the central portion may be brought more or less into conformity with the shape of the surface 16 and thus the temperature at which the control changes shape may be likewise varied I claim 1. An apparatus for shapin metal blanks comprising cooperating dies ing surfaces of dissimilar shape, and coo erating abutments which do not engage t e blank, for limiting the movement of the dies toward one another, leavin a space between the pressing surfaces 0 the dies when the abutments are in engagement sufficient to receive the blank.

2. An apparatus for shaping metal blanks comprising cooperating male and female dies, one of the dies having a concave reesing surface developed upon a smoot unbroken curve and a cooperating die having a substantially fiat central portion and an outer conical portion so designed that the pressing surface enga es with the blank throughout a restricte portion of its area inside the eripheral edge, and cooperating shoulders ormed upon the dies and adapted to limit the movement of the dies toward one another.

3. An apparatus for shaping metal blanks comprising cooperating male and female dies,one of the dies having a concave reseing surface developed upon a smoot unbroken curve and a cooperating die having a substantially fiat central portion and an outer conical portion so designed that the pressing surface engages with the blank throughout a restricted portion of its area inside the peripheral edge.

4. An apparatus for shapin metal articles comprising male and emale dies shaped to clamp the stock therebetween along a conical annulus radially displaced from the center thereof, one die having less convexity throughout its central portion than the concavity of the other die throughout its corresponding portion, whereby the stock is not clamped throughout a region inside said annulus.

5. An apparatus for shaping metal articles comprising a die provided with a curved concave pressin surface, a cooperating die rovided with a convex pressing surface avin a substantiall flat central portion boun ed by an annu ar conical portion and adapted to grip the metal blank approximately at the unction of the flat aving presscentral portion and conical portion, and abutments for limiting the relative movement of the two dies toward one another.

'6.- An apparatus for shaping 'metal articles comprising cooperating dies adapted to form a flat blank into substantially concavo convex shape, and unitary means rigidly but adjustably associated with one of the dies for var ing the curvature of a portion of the blanl 7. An apparatus for shaping sheet metal blanks comprising cooperatlng dies adapted to form the blank into a substantially concavo convex shape, and an adjustable member movable to different fixed ositions relatively to one of the dies and a apted to vary the curvature imparted to the blank.

8. An apparatus for shaping metal articles comprlsing a female'die having a substantially concave pressing surface, a cooperating male die having a substantially convex pressing surface of dissimilar shape, and an adjustable lug projecting from the central portion 0? the convex pressing surface and movable to difierent positions to vary the curvature imparted to this portion of the blank.

JOHN A. SPENCER.

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