US2598456A

US2598456A - Bobby pin

Info

Publication number: US2598456A
Application number: US71787A
Authority: US
Inventors: Burton K Snyder
Original assignee: Gaylord Products Inc
Current assignee: Gaylord Products Inc
Priority date: 1949-01-21
Filing date: 1949-01-21
Publication date: 1952-05-27
Anticipated expiration: 1969-05-27
Also published as: CH283921A; DE826338C; GB669148A; FR998292A

Description

May 27, 1952 B. K. sNYDER 2,598,456

BOBBY PIN Filed Jan. 21, 1949 3 Sheetsrsheet 1 Uzzzt aad a? j Z 5 4 5 6 7 8 9 M 3 Sheets-Sheet 2 BOBBY PIN B. K. SNYDER May 27, 1952 Filed Jan. 21, 19.49

-m -WFL B. K. SNYDER May 27, 1952,

BOBBY PIN Filed Jan. 21, 1949 3 Sl'xeetS-Sheeil 5 bazazaagfzzapazza FIET.

Patented May 27, 1952 BOBBY PIN Burton K. Snyder, Chicago, ".Ill., .assigner ltoGaylord Products, Incorporated, Chicago, Ill., `a

corporation of Delaware ApplicationJanu'ary 21, 1949,Serial No.7f1,787

l3 Claims.

'This invention relates to .hair fasteners "and is more particularlyconcerned with the provision of .a hair fastener of the bobby pin type comprising a piece of resilient wire bent intermediate its ends to 4form opposing hair clamping legs normally disposed in contacting engagement by means yof a connecting loop portion.

n The present invention contemplates the .provision `of a bobby pin construction in which the opposing legs are placed under'a relatively .high

initial tension or clamping force to. prevent accidental displacement of the 'bobby pin from a relatively small lock of hair or from a display card upon which the bobby pins are mounted for distribution and sale. yIn Athe manufacture of bobby pins, a piece of resilient Wire is bent interme'diatev its ends to form opposing legs vand a connecting loop portion and it is well known in this art that such an operation Yplaces the metal along the inner face of the loop -portion under compression and places the metal on the outer face -o'f the Aloop portion under tension. To cause the legs of the bobby pin to exert a higher initial clamping force, the `present invention contemplates the provision of a shot peening operationen the outer surface of the loop Yportion Vto thereby cause the vmetal on -the outer surface to be placed under compression. By shot peening the outer surface of the connecting loop portion of the bobbypin, it has been found'po'ssible to `open'the legs of the 'bobby pin to a greater width without exceeding the elastic limits of the material. It will be 'appreciated that 'a bobby pin 'loses its usefulness lin clamping hair in position when the elastic limits of the material 'has 'been 'exceeded to cause the legs of the bobby pinto be set to an open spacedapart' position.

In Lthe preferred form of construction, the bobby pins are formed from round, oval or halfround wire bent intermediate its ends to form opposing legsof gradually increasing width and decreasing thickness, with one of the legs'crimped transversely at spaced intervals and throughout the major portion of its length. In this form of construction, 'the bending'stren'gth of the legs at various points throughout their length lis-proportional .to the leverage between the 'various points and their connected ends, thus permitting a more uniform spread of ,the legs throughout their length without exceeding "the elasticflimits of *the various-sections. By -s'ho't peening 'the outer .surface of-theconnecting lo'op portion and the portions `.of `the Ylegs `adjacent thereto, the legs of the bobby pin may bewspreacl apart to a greater width than hasv heretofore been possible W-ithout exceeding the elastic limitof the material. This invention embodies other-novel features, details yof construction and `arrangement Y-of' parts which-are hereinafter -set'forth in the specification and claims and illustrated in the `accompanying drawings, wherein:

Fig. 1 is a topplan viewshowing a bobby pin embodying features ofy this invention.

Fig. 2 is a side elevational viewof same. Fig. 3 is a bottom plan view of same.

Fig. 4 is a graph illustrating `the opening of unp'e'ened bobby pin's'ls'bje'cted to unit loads.

Fig.. 5 is a graph illus'tratin'githeopeningo pe'ened, heat-treated 'bobby pins under unit load.

Fig. 6 is a graph illustrating the o'penin'g of peened, heat-treated; black japa'nned 'bobby pins underrunit load.

Fig. 7 is a graph-illustrating the'initia'l grip of unpeened bobby pins, peenecl 2bobby pins, and peened black 'japannedbobby pins.4

Referring now to theiirawings `for-a 4rdbetter understanding of this'invention, the bobby'pin is shown as preferably comprising fa lengthfof resilient wire 'bent intermediateitsven'clsfto form a loop .portion 6 and a pair-of depending legs 'l and S of gradually increasing `.width"an'c'ljiecreasing thickness" from the loop portion to their free ends. It is 'contemplated vthat the bobby pin may befformed from round, 'oval or l.halfa round resilient steelwire. `The`-outerflegf11 ,is formed Athroughout the greater yportion `of its length with a plurality of inwardly converging crimps having their Ybases 9 normally ldisposed in contact 'with the opposingleg. `A relatively large hair receiving fpocketll is formed at the inner end of th-e bobby pin `vand is -dened .,by the .leg 8, the uncri'mped portion l2 .oi the crimped leg l, andthe connecting .loop ,portion 6.

W'hen a bobby .pin v'has beenformedin the manner illustrated and described, the `metal deiini-ng the inner'suriace oi the lloop endo'i the bobby .pin is under compression, while the metal deiining the outer surface .Id wof the loop -V end is urfde'r tension. To jincrease the initial grip of the opposing legs "l and Y'8 and also to ,permit the legs'tobe s'pra'dto' Va'wid'e open 4position without exceeding the elastic ^limit `oi the material., the outer' surace of vthe 'bobby pin vadiacent the loop .end f6 is shot peene'd to place vthe metal un'der compression. The apparatus `for accomplishing the shot i-.peeningoperation may be of anysutabletypa'well yknown to those skilled in thelart, in which .relatively small steel shot are `directed against the outer `surface-oi the loop 'end ci the `lmilibyfpin at various' intensities which, for example, may be of from .002 arc height to .012 arc height depending upon the carbon content of the steel Wire and the physical properties desired to be imparted to the bobby pin. As illustrated in Fig. 5, groups of bobby pins were shot peened at various intensities ranging from .002 arc height to .012 arc height in order to determine which intensities were most desirable. In the chart it will be noted that bobby pins shot peened to an arc height intensity of .012 offered greater resistance to initial load deflection than bobby pins shot peened to an arc height of .002. However, the tests indicated that the deflection or spread of the bobby pin legs was substantially equal at the maximum unit load or the point at which the material reached the end of its elastic limit.

In making the tests of peened bobby pins and unpeened bobby pins it was found that 60% of the unpeened pins were sprung beyond their elastic limits under the unit load E, While only 26% of the peened pins were sprung beyond their elastic limits under the unit load indicated at llE'H Fig. 7 in the drawings graphically illustrates the units of initial grip of unpeened bobby pins and shot peened bobby pins and it will be noted that the initial grip of peened bobby pins greatly exceeds the initial grip of unpeened bobby pins. It was further learned that the overall stiiness and holding power of the shot peened bobby pins exceeded that of the unpeened pins by 181/2%.

It is a common practice in this industry to japan pins after heat-treatment to provide the pins with a relatively hard, smooth, moistureresistant surface. As graphically illustrated in Fig. 4, the japanning operation appears to normalize or anneal the metal as japanned bobby pins have greater deflection under unit load than unjapanned bobby pins.

Fig. 6 in the drawings graphically illustrates the deflection under unit load of bobby pins which have been peened after heat-treatment and then black japanned after peening. It will be noted that these bobby pins were subjected to a relatively greater unit load F and greater deection l Without exceeding the elastic limit of the metal. A comparison of the tests between japanned pins and unjapanned pins is graphically illustrated in Figs. 6 and 5, respectively. In carrying out the tests of bobby pins it was found that only 3.3% of the pins were sprung beyond their elastic limits under the unit load indicated at EL Whereas 60% of the unpeened, unjapanned pins opened at E and 26% of the peened, unjapanned pins opened at E.

In the manufacture of bobby pins of the type illustrated and described, the pins are rst formed on a conventional forming machine and then heat-treated to enhance the physical Properties of the metal. The loop end of the bobby pin is then shot peened along its outer surface to place the metal along the outer surface under compression. 'Ihe heat-treated, shot peened pin is then japanned, if desired. The results of numerous tests indicate that heat-treated, shot peened pins may be opened to a greater degree than heattreated pins which have not been shot peened, and that heat-treated, shot peened, japanned pins may be opened to a greater degree than heattreated, shot peened pins without exceeding the elastic limit of the metal. In subjecting the several types of pins to a predetermined unit load,

it was found that the elastic limit of the metal was exceeded on 60% of the unpeened unjapanned pins, the elastic limit of the metal was exceeded on 26% of the peened unjapanned pins, and the elastic limit of the metal was exceeded on only 3.3% of the peened japanned pins. The tests further indicate that heat-treated, shot peened pins have a higher initial grip than pins which are not shot peened.

In summarizing the advantages of the shot peening operation, shot peening the loop ends of bobby pins definitely improves the initial tension, overall stiffness, and gripping qualities, and at the same time permits the legs to be spread farther apart without exceeding the elastic limit of the metal. The tests indicate that shot peening the pins at increased arc height intensities further enhances the physical properties of the pins, that shot peened pins have an initial grip 25% greater than unpeened pins, and that the overall stiffness and holding power of shot peened pins exceeds that of the unpeened pins by 18%.

While this invention has been shown in but one form, it is obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications without departing from the spirit and scope of the claimed invention.

I claim as my invention:

l. A bobby pin formed of resilient heat-treated metal, comprising a pair of opposing legs, and a loop connection normally urging said legs into contacting engagement, the surface metal along the outer surface of said loop connection and along the outer surface of adjacent portions of said legs being locally densied and relieved of residual tensile stresses.

2. A bobby pin formed of resilient heat-treated metal, comprising a pair of opposing legs, and a loop connection normally urging said legs into contacting engagement, the surface metal along the outer surface of said loop connection and along the outer surface of adjacent portions of said legs being locally densied and relieved of residual tensile stresses, said bobby pins being provided with a j apanned nish.

3. A Ibobby pin formed of resilient metal, comprising a pair of opposing legs, and a loop connection normally urging said legs into contacting engagement, the surface of the metal along the outer portion of said loop connection and along the outer surface of adjacent portions of said legs -being densied and relieved of tensile stresses occasioned by forming the loop, said bobby pins being provided with a japanned nish.

BURTON K. SNYDER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS 15,939 Great Britain of 1893