US2867824A

US2867824A - Method for making sheet material split-ring lock washers

Info

Publication number: US2867824A
Application number: US506011A
Authority: US
Inventors: John B O'connor
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 1955-05-04
Filing date: 1955-05-04
Publication date: 1959-01-13
Anticipated expiration: 1976-01-13

Description

1959 J. B. O'CONNOR 2,867,824

METHOD FOR MAKING" SHEET MATERIAL-SPLIT-RING LOCK WASHERS Filed-May 4, 1955 INVENTOK- @mZUCam dZvw/W;

United States Patent METHOD FOR MAKING SHEET MATERIAL SPLIT-RING LOCK WASHERS John B. OConnor, Glenview, lll., assignor to Illinois The present invention relates to a novel method for producing lock washers, and more particularly to a novel method for producing split-ring type lock washers from a continuous strip of sheet material.

It has heretofore been proposed to manufacture splitring type lock washers by stamping them from sheet material or by coiling a wire or rod and subsequently severing convolutions of the coil. One disadvantage of the lock Washers formed in accordance with such prior methods is that their holding power rapidly diminishes after they have been substantially flattened between a workpiece and a clamping member such as a nut or screwhead.

To overcome this disadvantage, it has been proposed to provide a sheet material split-ring lock washer having double compressibility or, in other words, a lock washer which ma for example, have a body which is helically twisted and which has a radial cross sectional shape such that it may be collapsed whereby the washer may be compressed by flattening the helix and also by flattening the radial cross sectional shape of the body.

An important object of the present invention is to provide a novel method for producing a lock washer having double compressibility from an elongated strip of sheet material in a rapid, continuous and economical manner, and in a manner which substantially eliminates waste of sheet material stock.

A more specific object of the present invention is the provision of a novel method for continuously producing from a strip of substantially flat sheet material a splitring lock washer which has a helically twisted body, and which body has a folded or axially collapsible radial ross sectional shape so as to provide the washer with materially improved locking characteristics.

A further object of the present invention is to provide a novel method for forming lock washers of the above described type from a continuous narrow strip of sheet material, by which method ends of'the formed washers are broken from the end of the strip easily and without substantially deforming or bending such ends during separation. D

Other objects and advantages of the present nvention will become apparent from the following description and the accompanying drawings wherein:

Fig. 1 is a diagrammatic elevational view showing an apparatus for accomplishing'thenovel method of this invention;

Fig. 2 is a diagrammatic plan view of the apparatus shown in Fig. l;

Fig. 3 is a perspective view showing a section of an elongated flat sheet material strip to be formed mto washers in accordance with the present invention;

Fig. 4 is a fragmentary perspective view showing how the flat elongated strip may be scored so that the subsequently formed washers may be easily separated;

Fig. 5 is a fragmentary perspective view showing a sectiOn of the elongated strip at an intermediate stage of its formation into washers;

Fig. 6 is a fragmentary perspective view showing a Patented Jan. 13, 1959 section of the elongated sheet material strip in a folded condition;

Fig. 7 is an elevational view showing how the folded elongated strip is coiled in accordance with the present invention;

Fig. 8 is an elevational view showing a lock washer formed in accordance with the method of this invention; and

Figs. 9 through 12 are fragmentary plan views respectively showing different methods of scoring the elongated sheet material strip so that the subsequently formed washers may be easily broken apart without bending or deforming the ends of the washers.

Referring now more specificially to the drawings wherein like parts are designated by the same numerals throughout the various figures, a lock washer 20 formed in accordance with the method of the present invention is shown in Fig. 8.. The lock washer is in the form of a split-ring which is helically twisted in the manner shown. In addition, the body of the washer is folded so that it includes upper and

lower flanges

22 and 24 joined by a curved Web portion 26, whereby to provide the washer body with a generally U-shaped radial cross section. When the washer 20 is clamped between a workpiece and a nut or a screwhead, the helical twist of the washer will first be flattened out so that the inherent resiliency of the sheet material provides a force tending to prevent unauthorized retrograde movement or loosening of the nut or screw. After the helical twist of the washer has been substantially flattened, further tightening of the nut or screw causes the

flanges

22 and 24 to collapse axially toward each other and causes further flexing of the web portion 26, and .as a result, the inherent resiliency of the sheet material provides a further force tending to lock the nut or screw against retrograde movement.

In accordance with the present invention the method for producing lock washers such as the washer 20 includes the steps of feeding a continuous strip 28 of sheet material from a source of supply, continuously forming or folding the fiat strip along longitudinally extending mid-portions thereof to provide opposed longitudinally extending marginal flanges, continuously coiling the advancing formed strip, and separating convolutions of the coil from each other to provide individual washers. The strip of sheet material i preferably sheet metal and is of substantially uniform thickness and width throughout its length. The strip is formed and helically coiled while it is relatively soft, and after the coiling operation has been completed, the washers are heat-treated to provide them with the desired resiliency.

Figs. 1 and 2 diagrammatically show an apparatus 30 for carrying out the method of the present invention. More specifically, the strip 28 of sheet metal is fed from a reel 32 to means 34 for continuously forming the strip to provide it with the desired cross sectional shape. In the apparatus illustrated, the means 34 comprises a plurality of sets of rollers which are continuously driven by suitable means not shown. The first set of rollers 36 are preferably feed rollers. Succeeding sets of rollers are formed so as to fold the strip progressively from. the fiat condition shown in Figs. 3 and 4 through the partially folded condition shown in Fig. 5 to the folded condition shown in Fig. 6. It will be appreciated that the number of sets of forming rollers may be increased or decreased in accordance with requirements dictated by the sheet material stock being formed. The formed strip of sheet material is continuously drawn from the rolling means 34 into a coiling mechanism 38 which may be of any known construction capable of forming the strip into a helical coil 40 as shown in Figs. 2 and 7.

After the strip has been coiled, the coil may be directed to a mechanism 42 of known construction which is adapted to sever the'convolutions of the coil from each other. However, in accordance with another feature of 1 the present invention, the strip is preferably scored in a manner which causes each helically formed convolution to break away from the strip substantially automatically during the coiling operation. This enables the severing mechanism 42 to be eliminated. "In Figs. 1 and 2 there is shown punch press means 44 for scoring the sheetmaterial strip as indicated generally at 46 in Fig. 4. As will be understood, the punch press is intermittently actuated in timed relationship with respect 'to the feed rolls so that successive scores on the strip are spaced a distance slightly less than the circumferential extent of each of the subsequently formed coil convolutions. When the intermittently operated punch press 44 is used to score the strip, means, not shown, is provided for maintaining a loop 48 in the sheet material strip between the rolling means and the punch press as shown in broken lines in 3 it is still flat, and the set of rollers 50 of the rolling means 34 may be conveniently adapted to act as scoring'rollers.

It has been found that when the strip is provided with scores such as the score 46 shown in Fig. 4, the

pointed portions

52 and 54 of the ends of the strip to be separated may be bent or twisted as the ends are broken apart. In

accordance with another feature of this invention, the strip may be scored as shown in Figs. 9 through 12 so as to prevent the separated ends of the strip from becoming bent or twisted while they are being broken apart. More lspecifically, Fig. 9 shows how

recesses

56 and 58 may be punched from the strip 28 at opposite ends of the score line 46 so as to eliminate the above described

pointed portions

52 and 54 and provide the ends of the strip to be separated with relatively broad tips which are not easily deformed.

In Fig. the strip is provided with a diagonal score .line 60 and short

transverse score lines

62 and 64 respec- :tively merging with opposite ends of the score line 60.

This arrangement also causes the ends of the strip to be separated to have relatively broad tips which are not easily deformed. In addition, the

score lines

62 and 64 may be formed deeper than the score line 60 so as further to promote a clean break between the ends of the strip.

In the above described method for scoring the strip, identical score lines are provided in opposing relationship in opposite surfaces ofthe strip. In Fig. 11, however, the strip is provided with short diagonal score lines 66 and 68 on one side and a long diagonal score line 70 on its opposite side, which long score line overlaps the short score lines but terminates within the longitudinal margins of the strip. Furthermore, the long score line 70 is formed in the surface of the strip which subsequently provides the outer surface of a helical convolution. Since the outer surface of the strip is stretched as the strip is coiled as well as while the strip is being folded, the location of the score line 70 causes the break to initiate at a mid-portion of the strip and progress outwardly toward the margins. This breaking action substantially reduces or eliminates undesirable bending or twisting of the separated end corners.

Fig. 12 shows another method of scoring the strip so that the strip will break from mid-portions toward its marginal edges. In this embodiment the strip is completely slit or severed as at 72 and scores 74 and 76 extend from opposite ends of the slit to the edges of the strip.

From the above description it is seen that the present invention has provided a novel method whereby splitring lock washers having double compressibility characteristics may be rapidly and economically produced. More specifically, it is seen that the present invention has pro'. vided a novel method wherein the lock Washers are continuously formed from an advancing strip of sheet metal rapidly and substantially without waste of the sheet metal stock. It is further seen that the present invention has provided a method wherein the sheet metal strip is scored so that the subsequently formed washers will break apart easily and without having their ends. bent or twisted.

While the preferred embodiments ;of the present invention have been shown and describedherein, it is obvious that many changes may be made without departing from the spirit and scope of the appended claims.

The invention is claimed as follows:

1. A substantially scrapless method for manufacturing sheet material lock washers having a split annular body and split annular marginal flanges extending inwardly in opposing spaced relationship, comprising continuously advancing an elongated strip of sheet material of substantially uniform thickness along a predetermined path of travel, successively scoring said strip along substantially equally spaced lines extending obliquely to the longitudinal axis of the strip for providing predetermined lines along which the strip is subsequently broken while providing junctures between adjacent sections of the strip which resist unintentional breaking, the distance between said score lines being equal to the circumferential meas urement of a finished washer article, then longitudinally folding the advancing strip to provide the strip with a central body portion and opposite spaced marginal flanges, subsequently helically coiling the advancing strip so that said flanges extend inwardly and each convolution carries a score mark, and then'breaking the strip along each of said obliquely extending score lines.

2. A method, as defined in claim 1, which includes the step of providing marginal recesses at opposite ends of each of the oblique scores before the strip is coiled .to facilitate the subsequent separation of adjacent convolutions along the scores without substantial bending'of end portions of the convolutions.

References Cited in the file of this patent UNITED STATES PATENTS 329,544 Flagg Nov. 3,1885 1,190,500 Allen July 11, 1916 1,397,787 Sibley Nov. 22, 1921 1,504,511 Ross Aug. 12, 1924 1,835,002 Birckmayer Dec. ,8, 1931 1,910,214 Durr May 23, 1933 2,260,053 Platt Oct. '21, 1941 2,635,572 Hesterman Apr. 21, 1953 2,697,865 Norton Dec. 28, 1954 2,712,768 Winkler July 12, 1955 2,742,279 Small Apr. 17, 1956