US 2504338 A
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April 18, 1950 ac c JR 2,504,338
ELECTRIC POWER APPLICATOR Filed June 350, 1945 \\\\\\\\\\\\\\\\\\\\\\\\\\Wfi INVENTOR R055 M r! Arm/i Je.
ATTORNEY parts I and 3 made of a material which has good heat insulating and electrical insulating properties. One such material, for example, is hard asbestos. The casing I, 3 serves as a handle by means of which the tool may be manipulated by an operator. The casing parts I and 3 may be held together by any suitable means, such as the screws 5.
A partition 1 of electrical insulating material extends longitudinally along and diametrically across the tubular casing I, 3 to divide it into two parts having chambers Ia and 3a. Within each chamber is a resilient, electrode clamping member 9, shown in detail in Figure 4. The clamping I members 9 may be constituted by tubing or channelling of berillium-copper alloy or any other suitable, resilient metal and are formed with one or more longitudinally extending slots or 1 outs 9a to provide tabs It which may be bent inwardly slightly. Also within the chambers Ia and 3a., are a pair of cooperating electrodes II and I3, theelectrodes being electrically insulated from each other by the partition I and being clamped orgrip'ped within their respective compartments by the inwardly sprung gripping tabs Ii]. 7
The electrode II is disposed against a copper or other suitable block I5 which may be brazed or soldered'to the upper clamping member 9 and acts as a stop which fixes the position of the electrode II within the casing so that its work engaging tip IIq, will protrude or extend from the casing-a short distance at all times. The lower clamp 9 is also provided with a similar stop block I1 ,"and a coil spring I9 is interposed between the block I! and the inner end of the electrode I3. The spring I9 normally forces the electrode I3 outwardly to a position where its work engaging tip I3a will protrude from the casing somewhat in advance of the tip Ila, as best seen in Figure I."' I-loWever, when the electrode tip l3a, is placed against a workpiece, such as the head of a metallie rivet 2|, and pressure is applied, the spring [9 will yield and the electrode I3 will be forced farther into the casing until the electrode tip I la also comes into contact with the conductive workpiece which then bridges the two electrodes. Current may be supplied to the electrodes II and I3 through a two conductor cable 23 having leads 25 which are soldered at one end to the clam s 9 and are connected at the other end to a'suitable source of alternating current through a transformer 21. If desired, a direct current source may beemployed, in which case, of course, the transformer 27 may be dispensed with. When the electrode tips Na and I3a are brought into engagement with the conductive rivet head,
thereof. The shank then expands to cause apair of sheets 29 through which it extends to be firmly united in known manner.
' The electrodes II and I3 are preferably both made of carbon or graphite, although one may be made of copper or other suitable metal, if found desirable in certain cases. Various grades of carbon or graphite welding rods of about 1%" diameter are readily obtainable. These may be cut or ground to the desired shapes and may be clectrodeposited with copper, if desired. In the latter case, the contact surfaces (the tips Ila and I 3a in the modification described above) must be shielded during plating, or else the plating must be removed therefrom. The copper coating may be found desirablesince it functions to reduce the electrical resistance at the points of contact between the carbon electrodes and the clamps Q, but if it is not, of course, absolutely essential. The important thing is to have the work engaging portions of carbon, graphite or the like to minimize the possibility of arcing or corona discharge with consequent un due wearing of the electrodes and marring of the work.
A carbon electrode applicator such as described above utilizes the electric energy in a very efficient manner because, among other things, it consumes power only during the actual heating process while the electrodes are in contact with the work and it converts a very large proportion of the input energy to useful heat in the work. This is in marked contrast to prior art applicators many of which require preheating and otherwise needlessly dissipate heat. Moreover, an applicator according to my invention is small in size and very light in weight (only several ounces) as a result of which and the further fact that it generates heat only when in engagement with the work (so that it does not itself heat up much) operator fatigue is minimized. Its small size also makes it easier to manipulate, and by backing the electrode I3 up with the spring I9, the electrodes can be applied to the work effectively at any angle. In addition, it may be pointed out that the carbon electrodes are very inexpensive and require little or no care.
Although I have shown and described but one embodiment of my invention, it will be undoubtedly be apparent to those skilled in the art thatmany modifications thereof are possible. Hence, I desire that my invention shall not be limited except insofar as is made necessary by the prior' art and by the spirit of the appended claims.
I claim as my invention:
-l.' An electric power applicator for feeding cur-' rent to a workpiece, said applicator comprising a other, said electrodes having work engageable" portions extending out of one end of said casing and adapted to be bridged by the workpiece when applied thereto, one of said electrodes being mounted for longitudinal movement within said casing relative to the other of said electrodes,
means associated with said electrodes for coupling said electrodes to a source of electric energy,' and yieldable means for projecting said movably mounted electrode a greater distance out of said casing than said other electrode whereby the work engageable portion of said movably mounted electrode normally occupies a position in advance of the work engageable portion of said other electrode.
2. An electric power applicator for feeding ur rent to a workpiece, said applicator comprising a tubular casing of insulating material consti tuting a handle, an insulating member within said casing extending diametrically acrossand longitudinally along said casing and dividing said 1' casing into two hollow parts, apair of conductive clamping members within said casing one in each of said hollow parts, a pair of electrodes within said casing one also within each of are parts, said clamping members having resilient" elements arranged to engage and grip their respectively associated electrodes for holding said electrodes in place within said casing and for providing electrical contact between said electrodes and said members, said insulating member maintaining said electrodes in electrically insulated relation to each other, said electrodes having work engageable portions extending out of one end of said casing and adapted to be bridged by the workpiece when applied thereto, stop means in each of said casing parts associated with the inner ends of said electrodes for determining the extent to which said electrodes will extend out of said casing, and means connected to said conductive clamping members for coupling said electrodes to a source of electric energy.
ROBERT MACLATCHIE, J n.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 1,109,592 Morgan Sept. 1, 1914 1,200,810 Clemens Oct. 10, 1916 1,690,101 Burns Nov. 6, 1928 1,862,653 Bean June 14, 1932 2,080,220 Butter et a1. May 11, 1937 2,180,665 Bruggerman Nov. 21, 1939 2,221,646 McPherson Nov. 12, 1940 2,422,265 Squires June 17, 1947