US 3470529 A
Description (OCR text may contain errors)
Sept. 30, 1969 F. KLUMPP, JR
TUBULAR BLADE FOR ELECTRICAL PLUG CAPS 2 Sheets-Sheet 1 Filed May 22, 1967 l I I I I l m I N s.
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TUBULAR BLADE FOR ELECTRICAL PLUG CAPS Filed May 22, 1967 2 Sheets-Sheet 2 INVENTOR. 45 I FERDINAND A? an, J/P.
v rZn'nf'qk United States Patent US. Cl. 339276 1 Claim ABSTRACT OF THE DISCLOSURE A continuous blade strip which can be wound into rolls comprising a plurality of sets of generally round tubular blades positioned between a pair of generally flat blades, the blades being formed of oppositely positioned folded over and contacting portions, one of the portions of each blade having an extension forming a terminal for engaging a conductor, the oppositely disposed contacting portions providing the tubular blade having therein elongated trough-like embossed portions, the embossed portions forming an elongated tubular blade closed at its ends; also a tubular blade per se as described above; also a method for forming the strip and the tubular blade per se.
BACKGROUND OF THE INVENTION Field of the invention This invention relates to blades for use in electrical cap plugs and particularly to blade strips useful in pro viding the three blades used in electrical cap plugs in which one of the blades is usually grounded. It also relates to the grounding blade itself of tubular construction. It also relates to the method of making the strip and the grounding blade.
Description of the prior art In the prior art, plugs primarily for power tools are available having two, usually, fiat blades for fitting into the conventional or other sockets, and a grounding blade or pin, usually round, and offset from the other two terminals in the plug.
Each of the above blades is usually provided with a solder type or solderless type (crimped) terminal for receiving the wires or conductors of the cord or cable, one of which is the ground wire.
There are several disadvantages in the use of the old type of ground blade. Normally it was formed separately from the fiat blades from a separate strip of metal, usually brass, supplied in rolls. The general technique used was that described in my Patent 2,558,052. However, after being stamped from the strip, it was rolled to form a round tubular terminal which could be received by the socket. This meant handling two separate rolls and performing two separate operataions on two separate press machines when forming the blades usually requiring two operations. It also meant handling the blades and cords in two separate operations at two separate stations to connect the blades to the conductors by the assemblers. All three blades could not be connected at one time.
Furthermore, in molding the cap around the blades, the round tubular blades had to be threaded through a very accurately formed round aperture in the loading bar and its complementary clamp prior to molding, another time consuming operatioin. The conventional round pin available made it impossible to use the usual slot arrangement in the loading bar which could receive the flat blades.
To form the conventional round tubular blade, it was also necessary to use wider punched out sections in the Patented Sept. 30, 1969 "ice strip than for the flat blade and then form the punched out sections around a mandrel. Thus, more material was required to make the round blade than the flat blade.
It was also necessary to punch a tongue in the terminal end of the round blades and fold it transversely of the open end of the blade to close the blade so as to prevent the molding material from entering the inside of the pin during molding operations. This construction weakens the pin of its terminal end.
SUMMARY OF THE INVENTION The tubular blade comprises folded over contacting portions, the contacting registering portions of the tubular blade including oppositely disposed elongated embossed trough like sections of preferably semicircular cross section forming a tubular blade closed at its ends, one of the portions of the blade having an extension providing a terminal for engaging the conductors of a cord, and the other portion terminating in a stop.
BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a plan view of the plug cap blades in different stages of the process of manufacture,
FIGURE 2 is an end view of FIGURE 1,
FIGURE 3 is a perspective with the cap' shown in perspective showing the relationship of the blades in a finished product,
FIGURE 4 is a side elevation of the tubular blade in finished form,
FIGURE 5 is a top view of FIGURE 4,
FIGURE 6 is a perspective of the tubular blade,
FIGURE 7 is a top view of the cap and blade assembly,
FIGURE 8 is a side elevation of FIGURE 7, and
FIGURE 9 is a partial view of the loading bar used in the molding operations.
DETAILED DESCRIPTION Referring to the drawings, FIGURE 1 shows a strip 10 of suitable material, such as brass, of a width suitable for forming the blades from the material. As the strip 10 is passed through a press, various operations take place from punching apertures to forming the blades.
In the first step rows of holes or apertures 11, 12, 13 and 14 are punched out as well as the blanks 15. At a later stage, when the strip 10 has progressed far enough, the compound punch and die severs the strip along the lines 16, 17 leaving a small lug connection portion 18 which can later be easily broken.
At a later position the blades including the tubular blade 20 and flat blades 21 are formed by dies and folded in part. The final folding steps provide the formed tubular blade slightly separated from the two flat blades as shown at the end of the strip. During these later stages the terminals 22 are formed.
As shown in FIGURES 3, 7 and 8, the round tubular ground blade 20 is positioned displaced from the flat blades 21, 21 in the cap 25. The blades are connected to the conductors 27, 28 and 29 of the cable or cord 30.
Referring to FIGURES 4, 5 and 6 the round tubular blade 20 comprises the complementary portions 35 and 36, each being of an elongated trough like shaped closed at the ends. This prevents molding material from entering the interior of the tubular portion during molding operations. At the end opposite the fold the blade is provided with the anchoring or locking element 37 received within the cap. To make it possible to use a simple molding bar, I provide the flat portion 38. The solderless crimping terminal 22 is provided on the extension opposite the portion providing locking element 37.
Referring to FIGURE 9, the clamping bar comprises a lower slotted portion 40 and a cooperating upper memher 41. In assembly an operator takes a set of blades including blade 20 and two adjacent blades 21 and assembles the harness arrangement including the three conductors 27, 28 and 29, this being done in a single operation on a crimping apparatus. The assembled parts are then inserted in the clamping bar 40, 41. Flat portions 38, 42 and 43 are inserted in slots 44, 45 and 46 and clamped between the two parts, the bar defining the cap line when placed in the molding machine.
I claim: 1. A round tubular blade for a molded cap, said tubular blade comprising oppositely (a) disposed troughdike contacting portions, (b) one of said portions including an embossed section of semicircular cross section and terminating in a stop portion extending outwardly from and perpendicularly of said embossed section and providing a locking element to be received within a molded cap, (6) the other of said contacting portions having a complementary embossed section of semicircular cross section in abutting relation with said one por- UNITED STATES PATENTS 1,674,246 6/1928 Gaynor et a1 339-196X 2,163,779 6/1939 Draving 339-220 X 2,861,324 11/1958 Klumpp 339 218 X 3,134,632 5/1964 Kimball et a1. 339-195 3,268,847 8/1966 Klumpp 339-184 X RICHARD E. MOORE, Primary Examiner US. Cl. X.R.