US 3191797 A
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June 29, 1965 E. c. FRAZE 3,19l,797
SHEET MEAI J'0INT Fi1ed March 4 1963 10 Sheets-Sheet 2 June 29, 1965 E. c. FRAZE 3,19l,797
Fi1ed March 4, 1963 10 Sheets-Sheet 3 Inited States Patent Tis application is a contin11ati011i11-part of my app1ica tion Serial NO. 193,060 med May 2, 196Z for "Sheet 1Ietal Iint and Method and Means of Fabrication," Ilovv abandoned, which il1 turI1, is a C0Ilti]1uation-jx1-1)art of 1Tly applicati0n Serial NO l30 884 med August l1, 1961, f01' Sheet Metal Joint and Method of Fabrication," now abandoned.
I'his invention relates t0 a Sheet nleta1 joil1t and Inore 1articularly iS directed 0 a j0int construction for attaching a nleInber or device t0 a Sheet of deforlnable ITaterial Without breaking the continuity 0f the Sheet.
I'he invention has been iniia1Iy a )1ied to th fabrication of thi1-va11ed containers having tear strips fol' Opening the containers, the inventi011 being en1p10yed t0 attach tabs to the tear Stfips 'This particular practice of the inventi011 has bee11 Selected fO the purpose ()f the present disc10sufe and Wi]1 provide adequate guidance fof those skilled il1 the art who may have pccasion to apply the uder1ying 1incip1es to other Specic purp0ses It is highly desirable t0 produce sealable cans 01 c0n tainers, fol exan1ple, cans for fruit juices 0I' like beverages, Various food I)roducts, articles Sllbject to deterioration by the atnTosphere, vvith the t0 S OT ends Walls of thecans Scored to provide tear Strips and vvi'h abS attached to te tear strips to Serve as handles fOT Severing the tear s riPS Withollt the use of caI1 0 eners or like t001s Infortunate ly, however, the probleIn of attachi11g the tabs 'to the tea1 stli )S in a reliable nlanner that is sati8factory for IIaSS Production has not b en hefetofore Solved I]:le 11Se 0f a Separate Tivet or like fastener for Seculing a tab to the tear Strip of a can top has been unsatisfact0fy for a nun1ber o Teasons, i11clllding the in1p0rtant reason that the I1Se of Such a fastenef necessitates punctuTing the can top or Wall With the )OsSibility of subsequent leakage Spot weld-ing techniqlles have a1S0 been roposed but have not been Successful foI' reasons that have plagued SPOt Weld connections for n1any years ^#`tternpts have also been lade to attach the tabs to the tear strips by cold pressure ve1di11gtech...1iques Whjle t11e cold pressure vvelding pr0cess has been SuCceSsul in careuuy controlled appHcations, it has not pfoved satisfactory in c(nn1ecial production of cans f01 a I111Inbef of reasons' In the TSt place, the n'lating Surfaces to be pressure vve1d ed toget]1er must be carefully cleaned and )repared for exanple, by bTush elenel1tsthat abrade the surfaces to be vvelded, but Such cleaning OpeatiOnS are diicult to carry out successfully by nlass pf0duction equipnle11t In the second place the inner suffaces of cans are COInn10nly necessarily Coated With a Suitable Sealant which is i1 evitably TuptuTed 'by the cold ressure vve1djng pfocess.
The cold veld pfocess also re(111ires that the faying surfaces of the parts be free of (any contaminants Such as dust o1 the like and it hasbeeI1imp0ssible in n1ass pr0duction 0 erations t0 insure that the faying sllrfaces are n]ain tained free of contaminants until j0ined by the cold vveld technique Experience has Show11 that Such -veld j0ints 0ften al eithe1' because the s11ffaces yvefe not adequately abraded or becaue dust or other forIns of c0ntaninantS interfere With the cold ressure vveld 0 eration.
There als0 have been attefnpts in the p1 i0l art to con- 11ect a tab OI thin Ineta1 level' to a containe1 Wall by forIning a portion of the c0ntanef Wall int0 a holw rivet f01 engagefnent vvith the tab or lever through an aperture thereof. In no instance, h0vever, has the hollow rivet proved Strong enough to be depended upon to carry out the metal tearing 0peration' The esentjnvention also forms a houow Tivet out of the container -vall and is based on the discovery of the cause of the failure of the l)riol' art llow rivets forn1ed ()ut of container Wa11s as vvell as the discove1y of how t0 avOd Such failue.
one c uSe 0f the failure Of Such a prior arth0110vv Tivet is that in the 11Sual f2tbrication procedllre the tota1 Surface area of the iinished rivet is so nluch greater than the area 0f the container vvall fr01T1 vvhich the rivet is-f0rn1ed that the nletal of the Tivet is greatly Stretched and thin11 (l. (;0I]Seq11e11tly the nletal -va11 0f the Tivet that must tran n1t the manual force for the Inetal tearing opefation is of a' thickIless that is bnly a fraction of the thickness of the origina1 sheet IIleta1 Stock froIn vvhich the container Wall is fabficated.
A Second and equany imp0ftant cause is that in )fior art pfocedures the ho110w sheet nletal rivet iS Subjected to overa11 axial C0Inpressi011 force il1 the operation of staking or heading the l10110v Tivet into POSitive engagelnent with the handle tab of 1ever The axial compressi01 force c01lapses the thil1 metal of the periphera1 vvall of the hol- 10W I`ivet, the thin Iletal Wall beillg crushgd and f0lded upol1itse1fwith consequent vveakening and destruction of the metal Sucture.
The resent inve11tion )Tesents a nuInber of concepts for dealing- With theS tvv0 causes for ri01 failures. one concept iS to elin1inate the l^St cause by 11tilizi...1g ...1 greater area of the container vall to forn1 the ho110w Tivet and thus increase the rati0 between the total area of the h01low rivet and the ara of the p0 tiOn of the container Wall that is converted into the hol10w rivet c0nguTati0n According1y, the hollow livet dravvs on a given area Of the container wall tht iS Substantially greatel than the area in )lan of the ii11ished hollow Tivetitse1f In the preferred PTactce of the iIlveli0l1, a Second concept is ilitia11y to displace 0I Shift the nletal of the container vvall froIn an outer atea into this given area before t1tilizing the Inetal of the given area to forIn the ho110w Tivet' The result bf applying these two concepts is that the thiclmess of the metal of the houow rivet aS Well as the thickeSS of the container yvall in1ediately around the base of the honow Tivet may be Substantia11y the thickness of the Origia1 Sheet I1etal Stock, Or nlay be even thicker.
A third COT1cept Telates t0 the Second cauSe of failure, i.e', the vveakening of the circunferential or peripheral vvall 0f the rivet by the Staking operation This third concept iS that the Staking operation may be cal1ied out by Tadially outvvard displacenent of th Deta1 0f the outer end vvall of the hollow fivet Without Subjecting the rivet as a whole to axial compression and Without destr11ctive crushing of the peripheral Wa110f the Tivet (...iven these 116W concepts, the problen1 is presented of how to put the concepts int0 actual practice The inventi0]1 teaches that this 0blem may be S0lved by forming the Tivet Stages.
The first stage consists of using an area of the container vvall that is Ilany tilTleS the area il1 plan of the desired Tivet t0 forIn a gradua1}y soped boss or din1ple 0f substa1itially greater area in plan of the desired Tivet and of Substan tially greatef height or axial di]1'1ension than the desired 1-ivet In the preferred practice of the invei1tion, this diIn 1)le-forning operation iS carried out vvith ffeedom foI` the Inetal outside the circulnference 0f the dimple t0 creep into the area Of the (1iIT1...)1 to avoid or at least to IniIli mize the thinning of the metal that forms the dimple Since the area of the outer annular zone from Which the IIletal is dravvi1 into the area ()f the diIlple varies With th Square of the Tadial din1en8ion of the annular zone and since that Tadial diInen ion isrelatively laTge, the See