US2889865A - Clamping jaw - Google Patents

Description

June 9, 1959 R. A. LALLl 2,889,865

CLAMPING JAw Filed April 2, 1956 2 Sheets-Sheei 1 L A- 7 V//////A /////7A 29 INVENTOR. 31 l .9! Romea A. Lalh 36 364 35 7 35d BY ATTORNEYS R. A. LALLI CLAMPING JAW June 9, 1959 2 Sheets-Sheet 2 Filed April 2, 1956 INVENTOR. Romeo A. la ZZL' United States CLAMPING JAW Romeo A. Lalli, Bridgeport, Conn. Application April 2, 1956, Serial No. 575,470

2 Claims. (Cl. 153-48) This invention relates to a stretch press and more particularly to a stretch press having an improved clamping means for securing the marginal edge portions of a sheet metal material during the stretching or forming operation.

In shaping magnesium and titanium sheet material or the like, such as are used in the formation of skin surfaces of an airplane, helicopter or the like, it has been discovered that a practical way of shaping such sheets into the desired form is by a stretching operation. Heretofore, the stretching operations have been performed by disposing a blank of sheet material between a pair of clamping means and forcibly moving a particular forming die or block into engagement with the material secured between the clamps so that the material is stretched to assume permanently the shape of the forming die. However, in the past, for each forming die having differently shaped die surfaces, a particular pair of clamps was required to be used in conjunction therewith in order to properly shape the desired form. Consequently, the clamping means utilized with one forming die could not be adapted or used with a second forming die for shaping a differently shaped component part of an airplane or the like.

In order to overcome the disadvantage of requiring a special pair of clamping means for each forming die required to make up each of the component shapes, there is provided according to this invention a stretch press having a universal clamping means which is adapted to be used in conjunction with any of a plurality of differently shaped forming dies, thereby eliminating the need of the specialized clamping means heretofore required for each particular forming die.

An object of this invention is to provide a stretch press with a universal clamping means for anchoring the marginal portions of a sheet material in a predeterminate, complementary, cooperative relationship with a forming die which is adapted to be forcibly moved against the material to permanently shape the material into a form having irregular curvatures orcontours corresponding to that of the forming die.

Another object of this invention is to provide a stretch press with a bank of relatively narrow individually operated clamping jaws which are movable relative to each other andto the forming-die 0f the press for securing the marginal edge portions of a sheet material disposed over said die, whereby the jaws are individually positioned in a of the individual clamping jaws comprising the bank with I novel clamping means for gripping the sheets and holding them securely while the stretching pressures are applied and with means for accelerating the opening and closing movement of the jaw members.

I The objects of this invention are accomplished by a i an airplane, helicopter or the like.

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stretch press having a forming die over which a sheet material is stretched until the material permanently assumes the shape of the die. Disposed on opposite sides of the forming die are improved clamping means for securing the marginal edge portions of the said material in a manner to simulate the approximate curvature complementing that of the forming surface of the die to facilitate stretching the material into the desired form as the forming die is moved relative to the clamping means. According to this invention, the clamping means are universally mounted on the frame to assume any predeterminate contour to conform to any of a plurality of forming dies, each having a different contour or shape. This: is accomplished by universally mounting the improved clamping means so that it can be arranged to simulate any of a number of differing marginal contours depending upon the particular shape of forming die to be used. Accordingly, each clamping means comprises a bank of a plurality of relatively narrow, individually operated, clamping jaw units which are movable relative to each other and to the forming die. Each bank of jaw units is rotatably and pivotally mounted as a whole about a perpendicularly disposed axis, and is also adapted for movement relative to the forming die. Further, each clamping jaw unit in the bank is individually rotatable and transversely adjustable relative to each other. As a result, the individual clamping. jaw units in the bank, within a given range, can be adjusted in space to simulate the approximate curvature complementing that of the forming die. Furthermore, each of the individual jaw units are provided with novel cam means for accelerating the opening and closing of the individual jaw members by a simple manual movement.

A feature of this invention resides in the provision of a novel clamp means comprising a plurality of individually operated jaw units which means is rotatably and pivotally mounted as a whole about axes which are perpendicularly disposed relative to each other.

Another feature of this invention resides in the provision whereby the individual clamping jaw units com prising the clamping means are individually and inde pendently rotatable and transversely adjustable relative to each other.

Another feature of this invention resides in. means whereby the opening and closing of the jaw members of each unit is accelerated by simple rotary action exerted on the actuating means of each individual clamping jaw.

Other features and advantages will be apparent from the specification and claims when considered in connection with the drawings in which:

Figure 1 is a front elevational view of a stretch press according to this invention.

Fig.2 is an end view illustrating a bank vof clamping aws.

Fig. 3 is a top view of the clamping bank as viewed from Fig. 2.

Fig. 4 is a side view of an individual clamping jaw;

Fig. 5 is an enlarged detail view partly shown in sec-: tion of the clamping jaw.

Fig. 6 is an enlarged detail front view partly shown in section of the clamping jaw.

Referring to Fig. 1, there is shown an improved stretching press for shaping unformed or partially formed sheets of magnesium, titanium or the like into shapes such as might be used in forming the component skin sections of According to this invention, the press 10 consists of a supporting frame A, a forming die B mounted thereon and a pair-of improved clamping means C disposed on either side of the forming die and adapted to be secured to the marginal edge.

portion of a material 11 disposed over the die so that upon relative movement of the die and clamping means the material will be stretched to the desired shape. While the clamping means can be moved relative to a fixed die member in order to produce the relative movement therebetween, in the herein illustrated form of the invention, the clamping means is relatively fixed and the die is movable.

As "illustrated in Figs. 1 and 2, the frame A consists of a pair of channel members '12 supported in spaced back to-back relationship wherein 'theflange portions 13 thereof are outwardly turned to form a guide rail for the clamping means as will be hereinafter described. Intermediate the ends .of the frame, there is supported the forming die B which has its upper face provided with the desired shape which is adaptedto be forcibly moved by any suitable power means, as for example piston and cylinder means 14 actuated by'hydraulic pressure or the like, 'into engagement with the sheet material 11 disposed thereover and held in position by the clamping means C so that the sheet will permanently assume the shape of the die. While the die is herein illustrated as having both a transverse and longitudinal curved surface to form an article having a corresponding compound curvatureor contour, it will be understood that the forming die may be shaped to have any desired curvature or contour as might be required by the individual requirements of the skin components necessaryto make up a fuselage section or the like of an airplane, helicopter and the like.

To eliminate the necessity of utilizing a particular or specialized clamping means for each of several of the variously shaped forming dies which may be required to make up the particular sections necessary, an improved clamping means C is provided whereby the clamping means can be adjusted and utilized in conjunction with any of the variously shaped forming dies which might be required to form the various component sections .of an airplane and the like.

As illustrated in Fig. l, the clamping means C are disposed on either side of the forming die. While the clamping means may be both fixed to the frame or one fixed and the other rendered movable thereto, the clamping means are herein illustrated as being both movably mounted on the frame relative to each other so that they can be both adjustably positioned relative to the forming die as may be required by a particular "form to beshaped. Since the clamping means disposed on either side of the die are essentially alike, but opposite in construction, it is considered that for purposes of explanation, the description of one is sufl'icient.

According to this invention, the clamping means C includesa bank 15 of relatively narrow, individually .operated clamping jaw units pivotally and rotatably mounted on a carriage 16, the latter being slidablymounted on the upper flanges 13 of the channel members whereby the carriage 16 is adapted to be longitudinally moved along the frame to carry the bank of jaw units into the desired adjusted position relative to the forming die. While the adjustment of the carriage 16 along the frame isaccomplished manually, it is herein illustrated as being mova ble by a screw 17 mounted in a brace 18 disposed between the channel members 12 adjacent the end of the frame, the screw 17 being threaded to a nut member 19 fixed to and depending from carriage 16. A hand wheel 20 is mounted to the outer end of the screw, so that by simply rotating the wheel in either direction causes the carriage to be longitudinally moved along the frame.

Referring to Fig. 2, the carriage '16 comprises atop and bottom plate 21 and 22 respectively, the latter being provided with depending brackets 23 to form agroove for receiving the rail flanges 13 of the channel members on which the carriage is slidably mounted and .guided into adjusted position. Securing means in the form of set screws 24 may be provided to fix the carriage '16 in adjusted position along the frame.

In order that the bank 15 of clamping jaw units may be angularly disposed about avertical axis relativeto'the forming die in the event the-shape to be formed thereby so requires, the upper or top plate 21 is pivotally mounted by a central pivot bolt 25 to the bottom plate 22 whereby the top plate 21 is rotatably positioned relative to the bottom plate 22. To lock the plates 21 and 22 in adjusted position with relation to each other, the upper plate 21 is provided with a,-pair.of oppositely disposed arcuate slots 26 for receiving'locking bolts 27 threaded into the bottom plate 22.

Connected to .the upper plate 21 and projecting upwardly therefrom is a pair of opposed bracket members 28 to which a base plate29 forsupporting the individual clamping jaw units 30 is pivotally connected. Referring to Figs. 2 and 3, the base plate 29 consists of an elongate plate 31 having a dependent web 31a located in and secured to a pair of depending lugs 32 by which it is pivotally supported on the brackets 28 by means of pins .33. The base plate 29 is further provided with a plurality of spaced, transversely extending, inverted T-slots 34 .in which the individual clamping jaw units 30, as will be hereinafter described, are mounted to form the bank of clamping jaw units, which jaw units are adapted to be shiftably mounted, transversely of the base plate so as to assume any adjusted or staggered-position relative to each other. "Therefore, as shown in Fig. 3, the clamping jaw units 30 can be adjusted to have a curvature corresponding to that curvature of the forming die. Further, since the base plate 29 is pivoted to the carriage 16 by means of pins '33, 'it will be noted that the bank as a whole can be pivoted toward or away from the die as may be desired.

According to the-present invention, the base plate has mounted thereon a plurality of improved individually operated clamping jaw units 30. The individual units include an L-shaped base portion 35 having the base leg 35a slidably and pivotally mounted to the base plate 29 for rendering the unit transversely adjustable along its respective slot 34. A stud 36 projecting upwardly through the slot secures the base portion 35 of the unit to the base plate, the head 36:: of the stud being retained in the T-slot. The upwardly extending leg portion 35b of the base portion 35 is provided with a transversely extending bore for receiving a pin 37about which a jaw member 38 is pivoted so that it may be tilted with respect to the base plate 29 as may be required, the upper portion of the jawmember being provided with a gripping portion 38a. Secured to the jaw member by suitable fasteners 39 is a bracket 40 which is provided with a recessed portion 41, the recessed portion being adapted to be positioned opposite the gripping portion 38a of the jaw member. Mounted in the recess 41 of the bracket is a second or normally retracted, movably mounted clamping jaw member 42 which is adapted to be moved relative to the fixed jaw member 38. This is accomplished by supporting the movable jaw member 42 on the bracket 40 by a plurality of pin members 43 which are slidably mounted in transversely extending bores 44, a portion of each bore 44 being enlarged to accommodate a coil spring 45 which normally tends to urge the pin members 43 and attached jaw member 42 into retracted position within the recess, as shown in Fig. 5. If desired, the base of the movable jaw member 42 may be provided with serrations 42a to securely grip the material disposed between the jaw members.

According to this invention, each clamping jaw'uni-t 30 arranged in the bank is provided with an individual operating means by which the jaws can be individually operated by a simple manual operation. As shown in the drawings, the means for operating the movable jaws comprises a shaft 49 mounted in a transverse .bore in the bracket 40 and having an eccentric camming portion 49b thereon which engages adowel or roller 47 disposed in apassage 46, while roller 47 engages a recess 42!) in the back of the movable jaw. Shaft 49 is rotatably mounted on the bracket 40 in a transversely extending bore, the ends 49a of the shaft being in bearing relationship in the bore of the bracket. The eccentric camming portion 49b engages the roller 47 so that upon rotation of the shaft 49, the eccentricity of the intermediate portion 49b of the shaft displaces the roller 47 laterally, thereby advancing the jaw member 42 into clamping position.

To facilitate rotation of the shaft 49, a manual operator 50 is provided. As illustrated in Figs. 2 and 4 to 6, the operator comprises a rod 51 having a knob 52 fixed to the upper end thereof, the rod 51 being connected to the shaft 49 intermediate the ends thereof. As illustrated in Figs. 2 and 5, the bracket 40 is provided with a slot 53 to accommodate for rotation of the handle for clamping and unclamping the jaw members.

In order that the movable jaw member 42 may be accelerated to its clamping and unclamping position upon actuation of the actuating means 50, the eccentric cam portion 49b of the shaft is provided with a longitudinally extending recess 49c which is adapted to receive the roller 47. Therefore, with reference to Fig. 5, it will be noted that in normal, open jaw position the roller 47 is in the recess 42b of the jaw member and recess 490 of the cam. Thus, as the handle 50 is rotated, counterclockwise as viewed in Fig. 5, the shaft is rotated counterclockwise causing the camming surfaces 49d of the eccentric camming portion 49b to engage the roller 47 to quickly cam or displace the roller 47 laterally and to the right to move the clamping jaw 42 into clamping position onto the marginal portion of a sheet material disposed between the jaw members. Because of the roller being normally seated in the recess 490, it will be noted that maximum lateral displacement occurs during the initial rotation of the handle whereby the roller 47 is forced out of the recess 490 to move the movable jaw member into clamping position. Continued rotation of the shaft 49 causes the outer camming surface 49d of the shaft to wedge the roller against the movable jaw member to lock the same in clamped position. Conversely, it will be noted that in unclamping the sheet, the shaft 49 is rotated clockwise from clamped position to the position illustrated in Fig. 5. As a result, the gripping action is gradually released until the instant the recess 490 is aligned with the roller 47, whereupon the latter is quickly snapped into seated position due to the action of the springs 45 normally biasing the jaw member 42 to open position. Consequently, it will be noted that the accelerated feature of the novel clamping jaw herein described greatly reduces the amount of time involved in opening and closing of the clamping jaw units 30. Further, the clamping means of this invention comprises relatively few parts which greatly reduces the cost of manufacture and material, yet being sufiiciently strong to resist the forces applied for stretching the material secured thereby. Furthermore, it will be noted that the movable clamping jaw units are easily and readily operated between the clamped or unclamped position by a simple rotary movement of the shaft.

Also, since relatively narrow jaw units are employed and are universally adjustable on the clamping means, they may be positioned to assume any desired predetermined setting to conform to that contour to be formed by the forming die. Because of this important feature, the marginal edge portions of the sheet material can be reduced to a minimum and can correspond more accurately to the curvature to be formed by the die proper, thereby substantially reducing the amount of material required to be trimmed from the finished article formed thereby. Further, the need of specialized clamps for each differently shaped die is eliminated; consequently, a press having a universal type clamp as herein described can be utilized in conjunction with any of the variously shaped dies required.

Variations and-modifications may be made within the scope of the claims and portions of the improvements may be used without others.

I claim:

1. For use in a stretch press for shaping an article of manufacture, said press having a frame, a forming die for shaping articles having irregular contours, said frame and die being relatively movable for stretching a sheet of unformed or partially formed sheet metal disposed over said die for assuming permanently the shape thereof, and a carriage slidably mounted on said frame for longitudinal adjustment relative thereto; clamping means adapted to be mounted on said carriage for gripping the edge portion of said sheet during the stretching operation, said clamping means including a base plate adapted to be pivotally mounted on said carriage, said base plate having a plurality of spaced slots, a bank of individually operated relatively narrow clamping jaw units mounted on said base plate, said jaw units each having a base portion rotatably mounted on said base plate and slidably mounted in said slots for movement therein, a jaw member pivoted to said base portion, a bracket connected to said jaw member, a second jaw member movably mounted on said bracket and adapted to be moved relative to said other jaw member, spring means normally urging said second jaw member away from said I'll'SL mentioned jaw member to maintain said jaw members normally spaced, and means for moving said second jaw member against the force of said spring means and toward said first mentioned jaw member, said moving means including a roller mounted on said backet in engagement with the movable jaw member, and a cam means including an eccentric cam member having a shaft mounted for rotation in said bracket in fixed relation to said first jaw member and having a portion forming a recess and being in camming engagement with said roller, said recess normally forming a seat for said roller in normal open jaw position, and means including an individually operated handle connected to said shaft for rotating said eccentric member to earn said roller in and out of said recess for accelerating lateral displacement of said roller and engaging jaw member relative to said other jaw member to clamp and unclamp the sheet therebetween, said jaw units being adapted to be individually positioned relative to each other along said base plate to conform the contour edge to be formed so that the desired contours of the sheet can be maintained adjacent the edge portions thereof thereby substantially reducing the amount of metal required to be trimmed along the edge portions of the finished article.

2. In a clamping means to be mounted on a stretch press including a pivotally mounted base plate having a plurality of spaced slots therein; a clamping jaw unit comprising a jaw member, a bracket mounted on said jaw member, a second jaw member movably mounted on said bracket, said movable jaw member being adapted to be moved relative to other said jaw member, means for moving second said jaw member, said means including a dowel mounted on said bracket in engagement with the movable member, a shaft rotatably mounted on said bracket in fixed relation to said first jaw member and having a portion forming cam means in camming engagement with said dowel means for laterally displacing said dowel means and engaging jaw member relative to said other jaw member upon rotation of said shaft for clamping and unclamping an article therebetween and a base portion pivotally connected to said first jaw member, said base portion being adapted to slidably engage one of said slots in said base plate whereby-on engaging the material to be stretched in said clamping means and stretching the same-said jaw unit adjusts itself to the changing conformation of the material.

(References on following page) 7" 8 :ReferencesCited in=:the;fi1eof"this patent 2;609;860 =Kindelberger Sapt. 9, :195'2 UNITED STATES :PA'PENTS M2692j633 Grsen .0613. 26, 11954 1,683,906 M honey S pt-11,1 2 1,732,445 Lapointe. Oct.22, 1929 5 y 1,781,180 .Jarecki Nov. 11, 1930 v 1,944,603 Hacker Jan.23,-1934 FOREIGN PATENTS 2,269,549 Oeckl Jan. v13, 1942 112,321 Sweden NOV. 7, 7-1944

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