US2349872A - Skin clamp - Google Patents

Description

Patented May 30, 1944 SKIN CLAMP Elmer L.A Lipp, Glendale, Calif., assignor to Herman H. Helbush, Los Angeles, Calif.

Application March 2, 1943, Serial No.l 477,693 9 claims. (ol. s55) This invention relates to clamps which serve in the nature of temporary rivets to hold together perforated sheets with the perforations in alignment, preparatory to application of permanent rivets.

The type of skin clamp to which my invention is particularly adaptable comprises generally a cylindric `body within which there is reciprocally mounted for protraction and retraction a springpressed, longitudinally split retaining pin having shoulders at the outer end of the pin for engaging the sheets. The pins are protracted and inserted through the register of perforations and, upon release of the spring, the pins are retracted relative to a spreader, causing the shoulders to engage the sheets and clamp them against the 228, filed January 9, 1942, which application hasv matured into Patent No. 2,320,493.

Such clamps, many millions of which are being used in the aircraft industry, must neces-` sarily be capable of being made relatively cheaply and yet must be capable of withstanding hard usage. One of the disadvantages inherent in the construction of prior clamps of this character has been the relatively high cost of manufacturing and assembling the plunger-like retaining pin unit and it is therefore to the production of a retaining pin unit of a design and construction which may be made and assembled relatively cheaply and which at the same time perform e'fciently, that my present invention is principally directed. f

Still further objects and corresponding advantages, however, will become apparent from the following detailed description of a presently preferred adaptation of the invention, for which purpose I shall refer to the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional View of a retaining pin unit;

Fig. 2 is an end view of Fig. 1;

Fig. 3 is a section on line 3--3 of Fig. 1;

Fig. 4 is a longitudinal section of my improved i thimble-shaped cylindric body having an opening 6 through its endwall 1, which opening normally is of the same diameter as the perforationsf,

P in` the sheet S to be clamped. l I

Reciprocally mounted in the body. there isa retaining member, pin'unit or plunger I Il to which this invention is more particularly directed and `which will now be described.r

`As best shown in Fig. 1, the unit I0 consists of a pair of retaining pins I I', each of which is preferably of semi-circular or segmental cross-` section and each of which presents at its ,outer end an enlarged portion I2 providing a shoulder I5 facing towards the body.

The pins II, with their inner flat surfaces facing towards each-other, are disposed longitudinally in the housing 20. The housing is formed of two opposed sections each having a flat inner plateportion 2l (see Fig. 3), which ilat portions are positioned between the'pins II to space the inner ends of the'pins apart. The side portions of each plate are curved outwardly and inwardly towards each otherto provide a semi-circular skirt 22 and thence are bent inwardly at 23, the

two end portions 23 diverging to provide there" between a longitudinal channel 24 of V-crosssection. The two plates being formed in the same manner, except that they are opposed, Aa description of one suflices for both. The bent portions 22, 23 of the housing elements terminate at their,

topends at the point 25, but the fiat inner portions 2| have each-an extension 2Ia projecting" outwardly beyond the plane of the ends 25 to receive a ferrule having an opening 3l through its end wall to pass the inner ends IIa. of pins and the extensions 2Ia.

In assembling the device, the two housing elements are placed together with their flat portions 2| in face to face relationship and the ex-.

tensions 2Ia are inserted through the opening' 3| in the ferrule end wall, after which the pins. which have bent inner ends IIa, are inserted through the channels 24 until the pin ends IIa. rest against the inner surface of the ferrule'end wall; Then the extensions 2Ia are bent down over the pin ends IIa and the side wall of the' ferrule is bent inwardly to the position shown in Fig. 4. then inserted in the body with the coil *springli therearoundthe spring bearing at its inner end against the body end wall and at its outer end against the ferrule 30. The pins Il are projected through the body end wall opening 5 and a spreader 40 is inserted vbetween the projecting outer end of the pins. Spreader 40 is T-shaped,

the l The retainer member assembly` isi having a cross arm 4ta and a central arm Mib. An end cap 50 is then applied to the body, the cap having its peripheral edge crimped into the annular groove 1a of the body, so that the central arm 40a. of the spreader projects outwardly between the pins through the opening 5l in the cap and the cross arm is held against longitudinal movement relative to the pins and body by being confined in the chamber 52 betweenthe body end Wall and the}cap;f j

As thusassembled, the retaining unit' 'l0 is normally urged to the right in Fig. 4, or into the retracted position, by the spring 45.

pins Il engaging in the opening' E5 in the bodyl housing sections are held together against lateral separation on the one hand by the ferrule. .3U v and on the other hand by the outer ends ofthe spacer plates disposed in face to face relation- I ship between the inner end portions of the pins,

end wall, the at portions 2l ofthehousing sections being positioned between the pins.

fact that the retaining pins do not have to be made .with `the shank` portion .of relatively large diameter to space them apart and, yfor the pin housing, it is possible to'use a stamping instead of more expensive tube stock. Moreover, the structure is more durable and less apt to become loose or disassembled, since the pins are spaced apart by the spacer plates2l which form an integral part of the housing. Assembly, which forms a very considerable part of the cost of such devices, is also materially reduced. Still further advantages inherent in this novel lconstruction Will 'be readily recognized by those skilled in this art. f

In operation, the clamp is placed in the cradle ofl a conventional Vclamp-applying tool, not shown, which tool has a portion 'engageable against the ,annular shoulder 47 provided bythe annular ange `48 on the clamp body and a plunger presses inwardly against-the end of the ferrule 30 `to protract the enlarged ends lf2 of the retaining pins -until they are spaced far enough from the body end wall 1 to be exed together and inserted throughthe registering perforationsPin the sheets S tor be clamped. Upon releasing the plunger. which releases the thus compressed spring 45, the spring expands to retract the pins relative tothe spreader 40 'and body 5, causing the shoulders I5 of the pins to engage the outermost sheet and Athus clamp the two sheets between those shoulders and the outer surface rof the cap 5l), as best shown in Fig. 4. f

The .specificdetails of construction and arrangement embodied in the foregoing description are intended merely-as illustrative lvand are not to be deemed limitative since the underlying elements of novelty permit of variations and modifications -within the scope of the appended claims. Y

1. A clamp of the class described comprising a body having an endwall presenting: an opening, a pair of work-retaining pins reciprocally mounted in the body for protraction and retraction relative thereto, the pin portions adjacent their outerends being held againstlateral movement .away from each other by the body end wall, spacer meansfdisposed between the inner ends of the pins, said spacer means 'having integral portions embracingthe inner-ends of the respective pins whereby to prevent .relative lateral outward movement of the inner ends of the pins, spring means interposed between the body and pins whereby normally to urge the pins into 'i imeans retaining the plates against lateral separationand means carried by the plates and embracing. thepins 'whereby to prevent relative lateral movement of the pins.

' :3.-A'clamp of the class described including a body and a retaining member reciprocally mounted in the body for protraction and retraction relative thereto, said retaining member comprising a pair of pins having their outer end portions projectingirom the body and a pair lof. plates disposed in face to face relationship between the inner ends of the pins, each of said plates having afskirt portion bent upon itself to provide a pin housing.

4, A clamp of the class described including 'a body and a retainingv member reciprocally mounted in the body for protraction and retraction relative thereto, said retaining member com-- prising a pair of pins having their outer end portions projecting from the body, a pair of plates disposed in face to face relationship between the inner ends of the pins, each of said plates having a skirt portion bent upon itself to provide a pin housing, andl a ferrule encompassing the outer ends of the plates.

5. Aclamp of the class described including a body and a retaining member reciprocally mounted in the body for protraction and retraction relative thereto, said retaining member comprising a pair of pins having their outer end portions projecting from the body, a pair of plates disposed in face to face relationship between the inner ends of the pins, each of said plates having `a skirt portion bent upon itself toprovide a pin housing, a ferrule encompassing the outer ends of the plates, and a coil spring bearing `at one end against the body and at its other end against the ferrule whereby normally to urge the retaining member into retracted potions are oppositely bent Voutwardly to form a substantially semi-circular skirt, the' outer-'ends of said portions being disposed divergently 'inwardly to deilne, together with the medial p0rtion of the plate, a pin-receiving channel.

7. A clamp of the class described lincluding a body and a retaining member reciprocally `,mounted in the body for protractionand retraction relative thereto, said retaining member comprising a pair of pins .having their outer end portions projecting from the body and a pin housing member consisting of a pair of vi'lat `plates disposed in face to face relationship between the pins whereby to space them apart, each of the plates having an outer end extension and a portion on each of its sides, which latter portions are bent towards each other to provide a longitudinal pin-receiving channel, and a ferrule mounted over the end extensions of said plates.

8. A clamp of the class described including a body and a retaining member reciprocally mounted in the body for protraction and retraction relative thereto, said retaining member comprising a pair of pins having their outer end portions projecting from the body, and a pin housing member consisting of a pair of at plates disposed in face to face relationship between the pins whereby to space them apart, each of the plates having an outer end extension and a portion on each of its sides, which latter portions are bent towards each other to provide a longitudinal pin-receiving channel, and a ferrule mounted over the end extensions of said plates and having an end Wall disposed against the adjacent ends of the side portions, said end extensions being oppositely laterally bent within the ferrule.

9. A clamp of the class described including a body and a retaining member reciprocally mounted in the body for protraction and retraction relative thereto, said retaining member comprising a pair of pins having their outer end portions projecting from the body, and a pin housing member consisting of a pair of at plates disposed in face to face relationship between the pins whereby to space them apart, each of the plates having an outer end extension and a portion on each of its sides, which latter portions are bent towards each other to provide a longitudinal pin-receiving channel, and a ferrule mounted over the end extension of said plates, said ferrule having an end Wall disposed against the adjacent ends of the side portions, the inner ends of the pins and the end eX- tensions of the plates projecting into and being oppositely laterally bent Within the ferrule to secure the ferrule on the housing and prevent longitudinal movement of the pins in one direction relative to the housing ELMER L. LIPP.

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