US3238543A

US3238543A - Method of forming a sharp-edged lockwasher

Info

Publication number: US3238543A
Application number: US283004A
Authority: US
Inventors: Harold P Hopp; Bohm Rudolf
Original assignee: HOPP
Current assignee: HOPP
Priority date: 1963-05-24
Filing date: 1963-05-24
Publication date: 1966-03-08
Anticipated expiration: 1983-03-08

Description

March 8, 1966 HOPP EIAL METHOD OF FORMING A SHARP-EDGED LOCKWASHER 2 Sheets-Sheet 1 Filed May 24, 1963 ii ii PRIOR AIET PRIOR ART March 8, 1966 H. P. HOPP ET AL 3,238,543

METHOD OF FORMING A SHARP-EDGED LOCKWASHER Filed May 24, 1965 2 Sheets-Sheet 2' 7 W I 60 MN I United States Patent 3,238,543 METHOD OF FGRMING A SHARP-EDGED LOCKWASHER Harold P. Hopp, 372 Lantana Ave., Englewood, N..I.,

and Rudolf Bohm, New York, N.Y.; said Bohm assignor to said Hopp Filed May 24, 1963, Ser. No. 283,004 2 Claims. (CI. -86) This invention relates generally to the field of metal stamping, and more particularly to an improved lock washer or similar article and method of making the same.

Planar annular lock washers are well-known in the art, and have for many years been widely used for maintaining threaded interconnections in tightened condition. Lock washers of this general type are provided with a central opening through which the threaded bolt may project, and the inner or outer periphery of the washer is provided with teeth forming sharpened edges which cut into the surface of either the underportion of the screw or bolt head, or the corresponding abutting surface of another member. In the past, such lock washers have normally been formed by stamping operations, and burred edges, which are quite sharp, have been formed as an incidental result of the stamping operation, and have obtained a locking purchase in most cases sufi'icient to adequately secure the threaded member in position and vibrat-ion from loosening the same. Ideally, a lock wash- "er should provide sharpened edges projecting from both planar surfaces in order that this purchase is obtained on both of the interlocking members and not merely one of them. Owing to considerations of cost of fabrication, where lock washers of this type are formed by simple die stamping operations, this desired end has not been readily achieved.

In our prior patent No. 3,060,992, granted October 30, 1962, and entitled Means and Method for Forming Non- Planar Articles, we have disclosed a lock washer cut from sheet stock material in which sharpened projections extend axially out of the plane of the washer in both directions. These projections make point contact, and ofier to a considerable extent the desired result which is a scoring or digging action on both the undersurface of the screw head and the plate against which the screw head abuts. We have found, however, that it is possible to obtain a superior efiect by the method herein disclosed.

It is among the principal objects of the present invention to provide an improved lock washer or similar article in which sharp edges extend over a considerable area and away from the plane of the lock washer in either of two directions.

Another object of the invention lies in the provision of an improved means for forming a lock washer or similar article in which sharp edges extending from two oppositely disposed surfaces are formed as a result of a multiple stage stamping operation.

Another object of the invention lies in the provision of an improved lock washer of the class described capable of imparting increased purchase against each of two abutting surfaces between which it is disposed.

A further object of the invention lies in the provision of an improved method for form-ing an improved lack washer, in which sharp edges are formed as a result of partially punching the same from the sheet stock of which it is formed, and completely punching the same back through the opening formed as a result of the first punching operation to result in the formation of sharp edges extending in either of two oppositely disposed directions.

Another object of the invention lies in the provision of an improved lock washer in which the cost of fabrication may be directly comparable with that of existing ICC lock washer construction, thereby permitting consequent wide sale, distribution and use.

Still another object of the invention lies in the provision of an improved method for forming lock washers of improved type which may be readily incorporated into existing punch press constructions with little or no adjustment thereof.

A feature of the invention lies in the ready adaptability of the method to a wide variety of shapes and sizes of lock washers, as the employment of the method does not depend upon the particular outer configuration of the formed article.

These objects and features, as well as other incidental ends and advantages, will more fully appear in the progress of the following disclosure, and be pointed out in the appended claim-s.

In the drawings, to which references will he made in the specification, similar reference characters have been employed to designate corresponding parts throughout the several views.

FIGURE 1 is a view in perspective of a lock washer or similar article formed in accordance with the present invention.

FIGURE 2 is a fragmentary view in elevation of one of the .teeth of the lock washer seen in FIGURE 1, showing the teeth of the lock washer seen in FIGURE 1, showing the same positioned between two abutting surfaces, and just prior to the exertion of a compression thereupon.

FIGURE 3 is a schematic view, partially in section, showing the punching of an article from sheet stock in accordance with prior art methods.

FIGURE 4 is a schematic sectional view showing the product obtained as a result of the operation shown in FIGURE 3.

FIGURE 5 is a schematic sectional view showing an operation similar to that illustrated in FIGURE '3, in which the male die is provided with an angularly disposed face.

:FIGURE 6 is a sectional view corresponding to that seen in FIGURE 4, but showing the product obtained as a result of the operation shown in FIGURE 5.

FIGURE 7 is an exploded view in elevation, partly in section, showing an improved male and female die means in accordance with the present invention.

FIGURE 8 is a fragmentary plan view of partially blanked sheet metal stock, being the product of the die means illustrated in FIGURE 7.

FIGURE 9 is a fragmentary side elevational view as might be seen from the lower portion of FIGURE 8.

FIGURE 10 is a schematic view, partly in section, showing a second male and 'female die means employed in accordance with the present invention.

FIGURE 11 is a sectional view corresponding to the product obtained from operation of the die means shown in FIGURE 10.

FIGURE 12 is a schematic side elevational view, partly in section, showing serial operation of the die means illustrated in FIGURES 7 and 10.

In accordance with the invention, there is illustrated in FIGURE 1 in the drawings a completed lock washer or similar article, generally indicated by reference char-.

acter 19, and resembling in most respects the lock washer disclosed in our above-mentioned prior patent 3,060,- 9212. The washer includes a central opening 11, first and second

planar surfaces

12 and 13, respectively, and a plurality of teeth 14, first portions '15 of which extend upwardly from the first planar surface 12, and second portions 16 of which extend downwardly from the second planar surface 13. By cutting, in accordance with the teaching of. the above-mentioned patent, there are formed first and second sharp points 17 and 1 8 which are adapted to cut into each of first and second

abutting surfaces

19 and 20 on objects such as a nut and bolt, sheet, or other structure. When manufactured in accordance with our prior patent, the stamping of the finished product is done by a single set of dies resembling to a degree the schematic illustration in FIGURE 3. In this view, there is illustrated a male die member 22, and a female die member 23, between which there is disposed a sheet 24 of metallic stock. The shearing edges 25 of the male die member 22, and 26 of the female die mem ber 23, pass each other during the stamping operation to blank out the finished object, which is illustrated in FIG- URE 4. The blank 27, as completed, includes a first surface 28 formed by the face of the male die member 22, the surface being bounded by a sharp peripheral edge 29. The second surface 30 defined by the female die member 23 is bounded by a relatively rounded peripheral edge 31. It is to be noted that the illustration of the

edges

29 and 31 in FIGURE 4 is greatly exaggerated for purposes of clarity, since in most cases the sharpness of the edge 29 will be observable only on critical examination with the naked eye, and is caused by the plastic flow of metal occurring while the die elements are pressing upon the metal, and prior to severance of the formed part.

Referring to FIGURE 5, there is schematically illustrated a similar die stamping operation in which the male die 33 is provided with an angularly disposed face 34, so that the stamping action is of a progressive shearing nature, and the angular face 34 may partially form as Well as cut the finished article, as taught in our above-mentioned patent, No. 3,060,992. The shearing edge 35, as illustrated in FIGURE 5, will have passed through the plane of the stock 38 at the leftwardmost portion thereof, before the rightwardmost portion has entered the plane of the stock. The female die 36 includes a shearing edge 37 lying in a plane substantially perpendicular to the axis of movement of the male die member 36. Under such conditions, the severed blank 39 will assume the appearance shown in 'FIGURE 6, wherein the first surface 40 and second surface 41 are angularly disposed with respect to the edge surface. The first surface 40 will terminate in a sharpened edge 42 extending upwardly therefrom. I

Referring to FIGURE 7, there is illustrated a die element 45 employed in practicing the present invention, the same including a plurality of individual tooth-cutting members 46, as well as first and second generally oppositely disposed cutting members 47 and 48 in which the pointed portions thereof have been ground off. The corresponding female die element 49 is conventional, and mates with the male die element 45. During the stamping operation, using the

die elements

45 and 49, the male die element 45 enters the female die element 49 to a point indicated by the dashed line in FIGURE 7, so that the cutting members 47 and 48 will only partially shear the blank, and allow the same to remain attached to and parallel to the plane of the stock. In this operation, the male die element 45 is placed below the stock as shown in FIGURE 7.

As seen in FIGURES 8 and 9, the stock 53, after a series of such operations, includes a plurality of formed but unsevered washers 54, each connected at first and second points of interconnection and 56. The stock in this condition is fed to a second set of male and

female die elements

58 and 59, respectively, for a second stamping operation as illustrated in FIGURE 10. The die

elements

58 and 59 are reversed in orientation with respect to the

die elements

45 and 49, and are substantially identical except that the members 47 and 48 :are eliminated, as the second set of die elements performs a complete stamping operation which severs the completed article from the stock. FIGURE 11 illustrates a schematic sectional view in which first and second relatively sharp edges 62 and '63, respectively, are oppositely disposed, the first sharp edge 62 having been formed by the final punching operation, and the second edge 63 having been formed by the initial punching operation, whereby the completely severed Washer 54 is provided with sharpened edges which project from both

planar surfaces

64 and 65 thereof.

The edge 62 is formed by the final punching operation by virtue of interference existing between the previously formed washer '54 and the edge of the opening 54a (see FIGURE 10) in the stock from which the washer is cut. During the initial punching operation, the clearance between the female die 67 and the male die '68 causes metal to flow at the points of shear. It is this metal flow which causes the formation of the edge 63. When the washer is again forced back through the opening 54a, the decrease in size of the opening caused by the above-mentioned flow of metal causes a rubbing or interference between the peripheral surfaceof the opening 54a and the washer 54, a flow of metal in both pieces tending to move the metal in a direction opposite that of the initial flow.

We wish it to be understood that we do not consider the invention limited to the precise details of structure shown and set forth in this specification, for obvious modifications will occur to those skilled in the art to which the invention pertains.

We claim:

1. The method of forming a generally planar toothlock washer or similar article having sharp edges thereon extending longitudinally outward in opposite directions from the plane of said lockwasher, comprising the steps of:

(a) providing a first set of mating male and female die elements having principal coaxial axes, said die elements having a first direction of relative movement;

(b) providing a second set of corresponding male and female die elements having principal coaxial axes, and a second direction of relative movement opposite said first direction of relative movement;

(c) providing sheet stock material and positioning the same between said first set of die elements and substantially completely forming and at least partially severing said lockwasher from said stock, said forming and severing operation also forming a corresponding opening in said stock and a simultaneous first flow of metal resulting in the formation of a first sharpened edge on said lockwasher at a surface contacting the male die element of said first set of die elements;

(d) positioning said stock between said second set of die elements and forcing said completed washer back through said opening in said stock whereby interference resulting from said first flow of metal causes a second flow of metal in said washer and the formation of a sharp edge on a surface contacting the male die element of said second set of die elements.

2. The method of forming a generally planar toothlock washer or similar article having sharp edges thereon extending longitudinally outward in opposite directions from the plane of said lockwasher, comprising the steps of:

(0) providing sheet stock material and positioning the same between said first set of die elements and substantially completely forming and at least partially severing said lockwasher from said stock, said forming and severing operation also forming a corresponding opening in said stock and a simultaneous first flow of metal resulting in the formation of a first sharpened edge on said lockwasher at a surface contacting the male die element of said first set of die elements;

(d) positioning said stock between said second set of die elements and forcing said completed washer back through said opening in said stock whereby interfer- 5 ence resulting from said first flow of metal causes a second flow of metal in said washer and the formation of a sharp edge on a surface contacting the male die element of said second set of die elements and shearing said lockwasher completely from said stock.

References Cited by the Examiner UNITED STATES PATENTS 1,785,281 12/1930 Olson 10 73 2,508,758 5/1950 Hollerith 83-51 3,060,992 10/1962 Hopp et a1 153 2 ANDREW R. JUHASZ, Primary Examiner.

Claims

1. THE METHOD OF FORMING A GENERALLY PLANAR TOOTHLOCK WASHER OR SIMILAR ARTICLE HAVING SHARP EDGES THEREON EXTENDING LONGITUDINALLY OUTWARD IN OPPOSITE DIRECTIONS FROM THE PLANE OF SAID LOCKWASHER, COMPRISING THE STEPS OF: (A) PROVIDING A FIRST SET OF MATING MALE AND FEMALE DIE ELEMENTS HAVING PRINCIPAL COAXIAL AXES, SAID DIE ELEMENTS HAVING A FIRST DIRECTION OF RELATIVE MOVEMENT; (B) PROVIDING A SECOND SET OF CORRESPONDING MALE AND FEMALE DIE ELEMENTS HAVING PRINCIPAL COAXIAL AXES, AND A SECOND DIRECTION OF RELATIVE MOVEMENT OPPOSITE SAID FIRST DIRECTION OF RELATIVE MOVEMENT; (C) PROVIDING SHEET STOCK MATERIAL AND POSITIONING THE SAME BETWEEN SAID FIRST SET OF DIE ELEMENTS AND SUBSTANTIALLY COMPLETELY FORMING AND AT LEAST PARTIALLY SEVERING SAID LOCKWASHER FROM SAID STOCK, SAID FORMING SAID SEVERING OPERATION ALSO FORMING A CORRESPONDING OPENING IN SAID STOCK AND A SIMULTANEOUS FIRST FLOW OF METAL RESULTING IN THE FORMATION OF A FIRST SHARPENED EDGE ON SAID LOCKWASHER AT A SURFACE CONTACTING THE MALE DIE ELEMENT OF SAID FIRST SET OF DIE ELEMENTS; (D) POSITIONING SAID STOCK BETWEEN SAID SECOND SET OF DIE ELEMENTS AND FORCING SAID COMPLETED WASHER BACK THROUGH SAID OPENING IN SAID STOCK WHEREBY INTERFERENCE RESULTING FROM SAID FIRST FLOW OF METAL CAUSES A SECOND FLOW OF METAL IN SAID WASHER AND THE FORMATION OF A SHARP EDGE ON A SURFACE CONTACTING THE MALE DIE ELEMENT OF SAID SECOND SET OF DIE ELEMENTS.