US3915543A - Polarized electric contact blades - Google Patents

Abstract

Polarized electric contact blades are made of different widths having a different dimensional fold of metal for polarizing each blade.

Description

United States Patent 1191 Pieifer 1 Oct. 28, 1975 1 POLARIZED ELECTRIC CONTACT BLADES [75] Inventor: Louis F. J. Pfeifer, Springfield, NJ.

[73] Assignee: Heyman Manufacturing Company, Kenilworth, NJ. [22] Filed: Oct. 31, 1974 [21] Appl. No.: 519,558

Related U.S. Application Data [60] Division ofSer. No. 331,573, Feb. 12, 1973, Pat. No. 3,861,779, which is a continuation-impart of Ser. No. 177,395, Sept. 2, 1971, abandoned.

[52] U.S. C1. 339/184 R; 113/119; 339/276 SF [51] Int. Cl. HOlR 13/64 [58] Field of Search .1 339/184, 276; 113/119 [5 6] References Cited UNITED STATES PATENTS 3,149,898 9/1964 Klumpp, Jr. .1 339/184 R Primary Examiner-Joseph H. McGlynn Attorney, Agent, or Firm-Auslander & Thomas 57] ABSTRACT Polarized electric contact blades are made of different widths having a different dimensional fold of metal for polarizing each blade.

2 Claims, 16 Drawing Figures US. Patent Oct.28, 1975 Sheetlof4 3,915,543

FIG. 2

FIG. 3

US. Patent Oct. 28, 1975 Sheet2of4 3,915,543

FIG. 8

FIG. 7

FIG.6

US. Patent Oct.28, 1975 Sheet3of4 3,915,543

US. Patent Oct. 28, 1975 Sheet4 of4 3,915,543

POLARIZED ELECTRIC CONTACT BLADES This is a division of application Ser. No. 331,573 filed Feb. I2, 1973 now US. Pat. No. 3,861.779, which is a continuation-in-part of Ser; No. 177,395 filed Sept. 2, 1971 and now abandoned.

. The present invention relates to polarized contact blades for electric plugs.

Even with the extensive use of A.C. current, there has been a continued need for electric contact blades that are polarized, or constructed so that each blade may fit into only one of the female socket contacts of an electric outlet.

It is a standard practice to manufacture electric outlets with one contact opening to receive a blade having a given width, and the other contact opening having a different width. Then if the blades of the inserted line cord plug are given the appropriate width dimension, the plug can be inserted into the outlet in only one way, with only one polarity.

Today, most standard electric sockets are polarized with two contact blade openings adapted to receive two different widths of contact blade, one width being the standard width clearing a blade of approximately one quarter of an inch and the second width clearing a blade of about five sixteenth of an inch.

The polarized electric socket openings thus adapted can receive a standard non-polarized electric plug cap assembly which has both blades of one quarter of an inch width without regard to polarity. If a polarized plug is used having one blade with a five sixteenth of an inch width, however, the larger dimension of the five sixteenth of an inch blade prevents its insertion in other than the desired polarity.

Prior devices to accommodate this arrangement have employed such varying width blades, but have been uneconomic of material and difficult to assembly in quantity as will later be described. Expedients such as coining one blade in a plug have been used in assembling a plug with two different blades to achieve polarization.

In modern blade manufacture it has been found economical to manufacture electric contact blades in progressive punch, cutting or stamping operations. By this expedient, little or no metal is wasted between blades and blades may be manufactured and assembled in strips and standard equipment designed for non-polarized plug blades without substantial change.

Heretofore, blades for polarized plugs could not easily be manufactured in strips and assembled in standard machines because of the variation in blade widths.

Progressive stamping of blades in long strips of metal in turn result in long strips of blades that are assemblable automatically by machine to a line cord and in properly detached pairs.

One form of polarized blade has been able to take advantage of side-by-side stamping of blades achieving polarity in blade sets by cutting each blade with the standard one quarter inch shank, but providing one blade with a five sixteenth inch tip and alternating with blades of three sixteenth tips. By this expedient, the same amount of metal is used as in the making of a standard blade and the blades are even adapted for automatic assembly.

The polarized effect is achieved by virtue of the fact that the five sixteenth tip cannot fit into the one quarter inch socket. The three sixteenth tip of the other blade does not affect its useability and further, the blades 2 have a one quarter inch shank to properly engage in a one-quarter inch socket.

While it would appear that the problems of economy and polarity have been solved, the above-mentioned blade has a particular shortcoming. The points and edges of the blades of the larger blade easily stick or jam while being inserted into a socket.

Attempted expedients of coining circular protrusions between such blades have only provided difficult wings on the wide blade to further complicate use.

Although rounded blade ends are easy to insert as are evenly tapered blade ends, the round end seems generally incompatible with the sideby-side stamped, folded polarized blade. Providing a diamond or triangular punch to the corner of the blade could be helpful in providing a taper.

Blades not round ended or tapered are not preferred, since they are more likely to hitch. Yet even such blades made in accordance with the present invention have advantages over the prior art in that the blade thickness of a normal blade is preserved in a blade that can be stamped side by side and also be polarized, with blades of substantially uniform width shanks.

According to the present invention, stamped, folded or cut-folded polarized blades are provided, stamped with a minimum of waste, polarized, yet such blade pairs consume no more metal stock than a stamping for a conventional blade.

Although such novel feature or features believed to be characteristic of the invention are pointed out in the claims, the invention and the manner in which it may be carried out may be further understood by reference to the description following and the accompanying drawings.

FIG. 1 is a detail of a metal strip showing folds of the blades of the present invention.

FIG. 2 is a plan view of a connected strip of blades according to FIG. 1.

FIG. 3 is a section of FIG. 2 at lines 33.

FIG. 4 is an elevation of a plug with a pair of blades of the present invention.

FIG. 5 is a plan view of FIG. 4.

FIG. 6 is a side elevation of a variant set of blades of the present invention.

FIG. 7 is a plan view of FIG. 6.

FIG. 8 is a section of FIG. 7 at lines 8-8.

FIG. 9 is a detail of a metal strip cut for another embodiment of the present invention.

FIG. 10 is a plan view of a connected strip of blades according to FIG. 9.

FIG. 11 is a detail of a metal strip cut for another em bodiment of the present invention.

FIG. 12 is a partial front elevation of a wide blade made from the stamping strip of FIG. 11.

FIG. 13 is a partial rear elevation of a narrow blade of FIG. 11.

FIG. 14 is a side elevation of FIG. 13.

FIG. 15 is a detail of a metal strip cut for another embodiment of the present invention.

FIG. 16 is a cut-away view of completed blades made from the stamping strip of FIG. 16.

Referring now to the figures in greater detail, where like reference numbers denote like parts in the various figures.

The blades 12, 13 are designed for use in the standard U.S. electric plugs and sockets. The dimensions hereinafter described are for standard United States use and use elsewhere where the dimensions are the 3 same. It should be understood though, that the polarized relationship of the blade pairs 11 may be achieved with other dimensions also applying the teachings of the present invention.

In FIG. 1 the metal strip as shown incidates cuts and folds in the fabricating of the polarized blade pairs 11. Progressing in the direction of arrow A, the completed blades l2, 13 are shown to the right in FIG. 2.

The preliminary steps in fabrication preferably start on the left where the blank 14 is cut into the strip 10.

In order to form the shape of the blade pairs 11, the metal strip 10 is given a cut 15. Cut 15 leaves a small joint 16 to maintain the blades l2, 13 in strip form as shown in FIG. 2 for greater convenience in machine crimping, among other things.

The complete detail of the cut 15 is not shown since the balance of the cuts 15, 19 deal with selected styles of blade crimps l7 and blade lips 18,all well known in the art and set forth in FIGS. 2, 6 and 7 in detail.

Cut 19 is a mirror image of cut 15 and leaves another joint 16. For convenience and certain applications, blade location holes 20 may be punched or cut out of the strip 10 associated with the blades 12, 13.

The cuts 15, 19 define a blade width distance 21 which in this instance, is five sixteenth of an inch. On blank 14 the cuts 15, 19 have tapering angles 22, 23 whose ends span the bend line 24 which ultimately be comes the tip 25 of the end of the blade 12.

The taper angles 22, 23 are selected, preferred to provide tapered ends 32 to the blade tip 25 so that the blade 12 will have little difficulty in sliding into a socket.

The taper angles 22, 23 taper from the five sixteenth width to one quarter inch after which the width 26 spans the distance between the cuts 15, 19 and remains one quarter of an inch until the end of the blade section or the part that forms the slip 18.

Blank 27 adjacent blank 14 is three sixteenth of an inch in its width 28, blank 27 is adjacent blank l4s width 21 between a cut 19 and a cut 15. The taper angles 22, 23 point inward on blank 27 and reduce to a three sixteenth of an inch width 28 from the upper portion of the blank 27 beyond the bend line 30, which has a width 29 of one quarter inch.

The narrow end of the taper angles 22, 23 on the blank 27 spans the bending line 30 which forms the tip 31 of the blade 13. The narrow end of the taper angles 22, 23 on the blank 14 spans the bending line 24 which forms the lip 25 of the blade 12.

The upper portion of the blanks 14, 27 both have widths 26, 29 one quarter of an inch wide. Although the blank l4s bend line 24 is at a higher level than the blank 27s bend line 30, bending of the blanks 14, 27 to form the blades 12, 13 forms a smooth blade set 11. The one quarter inch blade sections fit in side by side in bent relationship, the blade 13 having a tapered corner 32 on a line with the bottom of the blade 12s tapered corners 32. Each blade l2, 13 has a one quarter inch fold, blade 13 having a width 21 of five sixteenth of an inch on one face and blade 12 having a one quarter inch width 29 on one face folded over the three sixteenth inch width 28 fold.

As a practical matter. as can be seen in FIG. 2, the blades 12, 13 are complete with crimp 17 and lip 18 and the lower portion of the blanks 14, 27 have tapers 33, 34 which widen the bases 35, 36 of the blades 12, 13 to a full one quarter width of both folds.

Referring to blade 12 as shown in FIG. 2, the first blade fold 27a starts at the bend line 30 and extends a uniform width to the base 35. The second longitudinal fold 27b can be seen in FIG. 1 or in phantom in FIG. 2.

The taper 32 on the second fold 27b forms a linear indentation 32a which extends longitudinally down the second blade fold 27b until near the base where tapers 33, 34 extended the second blade fold 27b to normal blade width.

The second blade 13 as shown in FIG. 2 has the first blade fold 14a start at the bend line 24 and extend a uniform width to the base 36. The second longitudinal fold 14b can be seen in FIG. 1 or in phantom in FIG. 2.

The taper 32 on the second fold 14b forms a linear protrusion 32b which extends longitudinally down the second blade fold 14b until near the base where tapers 33, 34 extend the second blade fold 14b to normal blade width.

In FIG. 3 is shown the cross-sectional relationship of blades 12, 13.

In FIG. 7 a blade pair 37 is shown having substantially the same blade widths 21, 28 and tapered corners 32 as the blade pair 11. The blades 38, 39 are bowed. Blade 39 has its five sixteenth section 40 flat while its one quarter inch section 41 has a blow in it to give the blade 39 a spring-like quality to better grasp the inside of a socket.

The blade 36 has its three sixteenth inch portion 42 bowed while the one quarter portion 43 lies flat. The bowed relationship of blades 38, 39 joined by the joint 16 can be seen in the section 22 of FIG. 7 as shown in FIG. 8.

In fabricating the blades 12, 13, a metal strip 10 of appropriate thickness is given cuts 15, 19. It is advantageous to make the cuts 15, 19 one at a time in progressive movements of the strip 10 progressively bending the blanks 14, 27 at lines 24, and line 30 until the blades 12, 13 are complete at the end of the direction of arrow A as shown in FIG. 1.

The blades 12, 13 as shown in FIG. 2 are preferably constructed in the same manner as hereinbefore referred to with regard to FIG. 1, but in this instance, the blades 12, 13 include the further steps well known in the art, those of stamping crimps l7 and lips 18. The style of the crimp is of course an option as is the question whether or not to include lips, and then the shape the lip may take.

Other option features which may be cut during the forming of the blades 12, 13, 38, 39 are the location holes 20, their number and alignment, all of which is well known in the art.

The blades 38, 39 are constructed by the same means as the blades 12, 13 with the exception of the bowing of blade sections 41, 42. As shown in FIG. 7, the blade pair 37 is a basic unit for use in a polarized plug 44. The joined blades 12, 13 as shown in FIG. 2 represent a part of a strip 47 as distinguished from a basic unit blade pair 37, which may be employed in machine crimping of line cords 45, 46, accompanied or separate from the molding of polarized plugs 44 in an automated operation known in the art.

The blade sets 11, 37 in each instance include the five sixteenth blades 13, 39 of greater length than the narrower one quarter inch blades 12, 38. In polarized blade sets 11, 37 such as these, it is important that the longer blade 13, 39 be the wider blade 13, 39, otherwise a narrower blade 12, 38 might first enter the wrong polarity electric socket by virtue of its greater length. In FIG. 4, a plug 44 is shown with blades 12, 13 attached to line cords 45, 46. It should be noted that the greater height of blade 13 does not affect its electrical characteristics.

In FIG. 5 the blades 12, 13 can be seen from above with their multiple width bent plies in the plug 44. The width 21 of blade 13 selects only an available five sixteenth inch socket. The thicknesses of the plies of folded metal is selected to fit into a socket without undue looseness. The fact that the narrow portion of the blade 13 had a width 26 of one quarter inch does not affect blade 13s thickness. Thus, in thickness and width, the blade 13 is properly suited for a five sixteenth inch polarized socket.

The blade 12 is by the same token as blade 13, suited for a one quarter inch socket and is unaffected by the three sixteenth inch width 28 of the fold of the blade 12.

In FIGS. 9 and 10, the metal strip 50, as shown, indicates cuts and folds in fabricating blade pairs 51 progressing left to right as heretofore shown by arrow A in FIG. 1. The completed blades 52, 53 are shown on the completed strip 54.

The preliminary steps in fabrication preferably start on the left where the blank 55 is cut into the strip 50.

In order to form the shape of the blade pairs 51, the metal strip 50 is given a cut 56. Cut 56 leaves a small joint 57 to maintain the blades 52, 53 in strip form as shown in FIG. for greater convenience in machine crimping, among other things.

The complete detail of the cut 56 is not shown since the balance of the cuts 56 and the second cut 58 deals with selected styles of blade crimps 17 and blade lips 18, all well known in the art and set forth in FIGS. 2, 6 and 7 in detail.

Cut 58 is a mirror image of cut 56 and leaves another joint 57. For convenience and certain applications, blade location holes may be punched or cut out of the strip 50 associated with the blades 52, 53.

The cuts 56, 58 define a blade width distance 59 which in this instance, is five sixteenth of an inch. On blank 55 the cuts 56, 58 are right angles 60, 61 whose ends span the bend line 62 which ultimately becomes the tip 63 of the end of the blade 52.

The right angles 60, 61 are selected as a selected alternate blade set 51 having the polarized blade 53 longer than the regular blade 52.

The right angles 60, 61 extend from the five sixteenth width to one quarter inch after which the width 59 spans the distance between the cuts 56, 58 and remains one quarter of an inch until the end of the blade section or the part that forms the lip 18.

Blank 64 adjacent blank 55 is three sixteenth of an inch in its width 65, blank 64 is adjacent blank 55s width 59 between a cut 58 and a cut 56. The right angles 60, 61 point inward on blank 64 and reduce to a three sixteenth of an inch width 65 from the upper portion of the blank 64 beyond the bend line 69, which has a width 67 of one quarter inch.

The narrow end of the right angles 60, 61 on the blank 64 spans the bending line 62 which forms the tip 63 of the blade 53. The narrow end of the right angles 60, 61 on the blank 55 spans the bending line 62 which forms the tip 68 of the blade 52.

The upper portion of the blanks 55, 64 both have widths 71, 67 one quarter of an inch wide. Although the blank 555 bend line 62 is at a higher level than the blank 65s bend line 69, bending of the blanks 55, 64 to 6 form the blades 52, 53 forms a smooth blade set 51. The one quarter inch blade sections fit in side by side in bent relationship, the blade 53 having a cut-out corner 70 on a line with the bottom of the blade 64. Each blade 52, 53 has a one quarter inch fold, blade 58 having a width 59 of five sixteenth of an inch on one face and blade 53 having a one quarter inch width 67 on one face folded over the three sixteenth inch width 65 fold.

As a practical matter, as in the case of the blades of FIG. 2, the blades 52, 53 may be complete with crimp 17 and lip 18 and the lower portion of the blanks 14, 27 have tapers 33, 34 which widen the base 35, 36 of the blades 12, 13 to a full one quarter width of both folds.

In FIGS. 11-14, a further embodiment of the present invention is set forth.

In FIG. 11 the metal strip 80, as shown, indicates cuts and folds in the fabricating of the polarized blade pairs 81. Progressing in the direction of arrow A, as shown in FIG. 1, the completed blades 83, 84 are shown to the right in FIG. 11.

The preliminary steps in fabrication preferably start on the left where the blank 85 is cut into the strip 80.

In order to form the shape of the blade pairs 81, the metal strip 80 is given a cut 86. Cut 86 leaves a small joint 87 to maintain the blades 83, 84 in strip form as shown in FIG. 2 for greater convenience in machine crimping, among other things.

The complete detail of the cut 86 is not shown since the balance of the cuts 86, 88 deal with selected styles of blade crimps 17 and blade lips 18, all well known in the art and set forth in FIGS. 2, 6 and 7 in detail.

Cut 86 has an upper straight edge 89 and on its lower portion, a straight protrusion 90 part of the distance of the cut 86. The second cut 88 has a cut portion 91 which starts straight, then has an indentation 92 the shape of the protrusion 91 on one upper side. At the lower portion of cut 88 is a straight edge 92. The alternate repeats of the cuts 86, 88 ultimately allow the strip 80 to be formed into a strip of blades 83, 84 joined by joints 87.

Blade edges may be formed by punching round holes 93 which round off the corners 94 of the blades 83, 84 when they have been folded.

As can be seen in FIGS. 11 through 14 the bend line 95 is uniform for both blades 83, 84. In bending the blank 96 or folding it from the bend line 95 forward, then straight edge 97 is folded under the protrusion 90 of the adjacent blank 85 or blade 84. By bending the blank 85 forward, its upper protrusion 99 or lip folds under the blank 96 and is inset with the straight edge 92 of cut 88, thus forming the adjacent polarized blades 83 having an inset lip 98 on either side and blades 84 having a protruding lip 99 on either side. The blades 83 are one quarter of an inch wide with a l /32 inch inset 98 on each side and the blade 84 is one quarter inch wide with a inset lip 99 on either side extending outward.

In FIG. 15 the metal strip 100, as shown, indicates cuts and bending line 101 in the fabricating of the polarized blade pairs 102. The blanks 103, 104 have small diamonds 105 cut out straddling the bending line 101. Blank 103 is formed into a blade 106 by folding forward from the bending line 101.. Blade 107 is formed by bending the blank 104 forward at the bending line 101.

As can be seen in FIG. 16, the blade tips 107, 108 are tapered by the folding of the diamonds 105 and folding together alternate wide and narrow blade faces 109, 110 of five sixteenth of an inch and three sixteenth of an inch respectively, the back folds 111 are uniformly 7 one quarter of an inch.

The terms and expressions which are employed are used as terms of description; it is recognized, though. that various modifications are possible.

I claim:

1. A set of folded metal polarized blades for an electric plug comprising a narrow blade and a wide blade, each of said blades being defined by first and second longitudinal blade faces folded from a bend line, the first and second blade faces of said narrow blade each having inset portions only one on either side of said blade, each said narrow blade having a width of a nonpolarized blade measured from furthest edge to furthest edge of said blade, the first and second blade faces of said wide blade each having only one protruding portion on either side of said blade, each said wide blade having a width of a polarized blade measured from furthest edge to furthest edge of each of said blade protrusion, joint means whereby said blades may be maintained in a continuous strip, and crimping means on each blade to connect the blade to a line cord.

2. The invention as claimed in claim 1 wherein each said narrow and wide blade insets and protrusions are interfitable in side-by-side relationship.

Claims (2)

1. A set of folded metal polarized blades for an electric plug comprising a narrow blade and a wide blade, each of said blades being defined by first and second longitudinal blade faces folded from a bend line, the first and second blade faces of said narrow blade each having inset portions only one on either side of said blade, each said narrow blade having a width of a nonpolarized blade measured from furthest edge to furthest edge of said blade, the first and second blade faces of said wide blade each having only one protruding portion on either side of said blade, each said wide blade having a width of a polarized blade measured from furthest edge to furthest edge of each of said blade protrusion, joint means whereby said blades may be maintained in a continuous strip, and crimping means on each blade to connect the blade to a line cord.

2. The invention as claimed in claim 1 wherein each said narrow and wide blade insets and protrusions are interfitable in side-by-side relationship.

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