US3861779A

US3861779A - Polarized electric contact blade

Info

Publication number: US3861779A
Application number: US331573A
Authority: US
Inventors: Louis F J Pfeifer
Original assignee: Heyman Manufacturing Co
Current assignee: Heyman Manufacturing Co
Priority date: 1971-09-02
Filing date: 1973-02-12
Publication date: 1975-01-21
Anticipated expiration: 1992-01-21
Also published as: US3915543A

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 Pfeifer 1 1 Jan. 21, 1975 POLARIZED ELECTRIC CONTACT BLADE [75] Inventor: Louis F. J. Pfeiier, Springfield, NJ.

[73] Assignee: l-Ieyman Manufacturing Company, Kenilworth, NJ.

[22] Filed: Feb. 12, 1973 [21] Appl. No; 331,573

Related U.S. Application Data [63] Continuation-impart of Ser, No, 177,395, Sept. 2,

1971, abandoned.

[52] U.S. Cl 339/184 M, 339/276 SF, 113/119 [51] Int. Cl H011 13/64 [58] Field of Search 339/65, 66, 184, 195, 196,

339/275 FS, 278 T; 113/119; 29/630 A, 193.5

[56] 1 References Cited UNITED STATES PATENTS 1,615,302 l/1927 Hartmann 339/184 R X 2,159,939 5/1939 Chirelstein 33 /195 R 2,174,383 9/1939 Folsom 339/196 M X 2,273,099 2/1942 Gilbert 339/195 R UX 3,149,898 9/1964 Klumpp 339/195 R X 3,163,485 12/1964 Kruitwagen et al. 339/276 SF UX 3,268,847 8/1966 Klumpp 339/1114 R X 3,470,529 9/1969 Klumpp 339/195 M X Primary Examiner-RoyD. Frazier Assistant ExaminerLawrence 1. Staab Attorney, Agent, or FirmM. Arthur Auslandcr [57] ABSTRACT Polarized electric contact blades are made of different widths having a different dimensional fold of metal for polarizing each blade.

13 Claims, 16 Drawing Figures POLARIZED ELECTRIC CONTACT BLADE This application is a continuation-in-part application of Serial no. 177,395 filed September 2, 1971 in Group 353 of the United States Patent Office, and now abandoned.

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

Even with the extensive use of AC. 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 nonpolarized 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 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 side-by-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 3-3.

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 ofa metal strip cut for another embodiment 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 United States electric plugs and sockets. The di mensions hereinafter described are for standard United States use and use elsewhere where the dimensions are the 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

12, 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

12, 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 l2, 13.

The cuts l5, 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 becomes 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 14's 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 14's 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 l2s tapered corners 32. Each

blade

12, 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 l2, 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. I 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 line24 and extend a uniform width to the base 36. The second longitudinal fold 14b can be seen in FIG. I 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 2-2 of FIG. 7 as shown in FIG. 8.

In fabricating the blades l2, 13, a metal strip l0 of appropriate thickness is given cuts I5, 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 17 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 l2, 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 l2, 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 l7 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 20 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 spans the bending line62 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 55s bend lines 62 is at a higher level than the blank s bend line 69, bending of the

blanks

55, 64 to 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 presmetal strip 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 l7 and blade lips 18, all well known in the art and set forth in FIGS. 2, 6 and 7 in detail.

Cut 88 has an upper straight edge 89 and on its lower portion, a straight protrusion 90 part of the distance of the cut. There is a second cut 91 which starts straight, then has an indentation 92 the shape of the protrusion 91 on one upper side. At the lower portion of the cut is a like 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.

The bend line 95 is uniform for both

blades

83, 84, 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 blank 85. By bending the blank 85 forward, its protrusion 92 folds under the blank 96 and is inset with the protrusion 90 of cut 88, thus forming 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 1/32 inch inset 98 on each side and the blade 84 is one quarter inch wide with a 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 10]. 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 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.

What is claimed is:

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 folds, folding from a bending line, the first fold of each of said blades being of the same given width, the second fold of the narrow blade having a width less than said given width, and the second fold of said wide blade having a width greater than said given width, each blade end having crimping means to join the blade to a line cord, joint means for maintaining said blades in a continuous strip with said first folds juxtaposed with each other on one side of said bending lines and with said second folds juxtaposed with each other on the opposite side of said bending lines.

2. The invention of claim 1 wherein said first longitudinal fold of said narrow blade tapers at its bending line to form a first blade tip and said second longitudinal fold of said wide blade tapers at its bending line to form a second blade tip.

3. The invention of claim 1 wherein said wide blade is longer than said narrow blade.

4. The invention of claim 1 wherein said crimping means are metal arms.

5. The invention of claim 1 in combination with an electric plug.

6. The invention of claim 1 wherein said wide blade is longer than said narrow blade by a distance about equal to the spacing between said narrow blades bending line and said wide blades bending line.

7. The invention of claim 1 wherein at least one of said longitudinal folds of at least one of said blades is bowed outward.

8. The invention of claim 7 wherein both said blades have at least one of said longitudinal folds bowed outward.

9. The invention of claim 1 wherein said first longitudinal fold of said narrow blade and said second longitu' dinal fold of said wide blade have aligned bending lines.

10. The invention of claim 9 wherein said first longitudinal fold of said narrow blade tapers at its bending line to form a first blade tip and second first longitudinal fold of said wide blade tapers at its bending line to form a second blade tip.

11. The invention of claim 1 wherein said joint means is on said first fold of said narrow and wide blades.

12. The invention of claim 1 wherein the longitudinal folds of said narrow and wide blades have concavities at their respective bending lines.

13. The invention of claim 3 wherein the longitudinal folds of said narrow and wide blades at their respective bendings lines defining tip portions, alternate tip portions of said blade being inset relative to adjacent tip portions.

Claims

4. The invention of claim 1 wherein said crimping means are metal arms.

5. The invention of claim 1 in combination with an electric plug.

6. The invention of claim 1 wherein said wide blade is longer than said narrow blade by a distance about equal to the spacing between said narrow blade''s bending line and said wide blade''s bending line.

9. The invention of claim 1 wherein said first longitudinal fold of said narrow blade and said second longitudinal fold of said wide blade have aligned bending lines.