US2489475A - Magnetic welder's ground clamp - Google Patents

Description

Nov. 29, 1949 K. A. BLIND MAGNETIC WELDER S GROUND CLAMP Filed Dec. 18, 1947 1N VEIY TOR.

MW}: MW

A 770 E/VEVS.

Patented Nov. 29, 1949 UNITED STATES PATENT OFFICE MAGNETIC WELDERS GROUND CLAIVIP Karl A. Blind,v Thicnsville, Wis assignor to-Dings Magnetic Separator 00;, Milwaukee, Wis.,. a

corporation of Wisconsin.

Application December 18, 1947, Serial No. 792,558

'7 Claims. 1.

This invention relates in general to improvements in current ground connectors as used by electric welders, and relates more specifically to improvements in the construction and operation of magnetically actuated electric welders ground clamps. Many different types of current ground connections and attaching clamps for electric welding use, have heretofore been proposed and utilized commercially with varying degrees of success, and in some of these prior devices it has also been" proposed to employ a permanent magnet for the purpose'of holding the ground terminal in contact with a grounded body such as a piece of work. In order toprevent excessive loss of time, these grounding clamps must be quickly and conveniently applicable and removable, but in order to function: properly while in actual use they must also provide a most efiective electrical connection between the ground terminal and the grounding body. Since these ground connectors are ordinarily subjected to considerable abuse they must also be sturdily constructed without unnecessary complication, and the prior devices of this type did not meet all of these requirements since most of them were either cumbersome, costly, difficult to apply and remove, or failed to providea suitable connection;

It is therefore an object of my present invention to provide an improved magnetic welders ground clamp which besides being simple and durable inconstruction, may be readily manipulated to provideefiective electrical ground connections;

Another object of the present invention is to provide an improved ground device for welders; which is operable by one-ormore-perman'ent magnets to automaticallyestablish an efiicient ground "when applied toa grounding body.

A further object of this invention is tcr provide a compact welders ground connector adapted to eifectively withstand normal abuse, and which may be-rapi'clly and e'asily'appliedto-the-work and removed therefrom.

Still another object" of the invention' is to provide an: improved electric ground clamp adapted for diverse uses, and which maybe readily constructed. of relatively few: simple parts and sold at moderate cost.

An additional object of my invention: is to provide an improved magnetically actuated ground clamp: for welding equi'pmentor the like, which wlll'mosiz effectively hold the terminal in contact ,withthegrounding bodywhile being-J conveniently removable. therefroim z These and other objects and advantages of the invention willbe apparent from the following detailed description. A clear conception of the features constituting my present-improvement, and of the mode of constructing and of utilizing several typical embodiments of the invention, may be had by referring to the drawing accompanying and forming a part of this specification wherein like reference characters, designate the same or similar parts in the various'views.

Fig; l is a topview'of one typical embodiment of my improved magnetically actuated ground clamp wherein the terminal is su-rrounded by the magnet assemblage;

Fig. 2 is a central vertical section through the clamp and termlnal unit'of Fig. 1-, taken along the line 22;

Fig; 3 is a bottom view of the unit shown in Figs. 1 and 2-; and

Fig. 4 is a central vertical section througha modified typical clamp and terminal unit of the type wherein the terminal surrounds the magnet assemblage;

While the invention has been illustrated and described herein as being advantageously applicable to welders ground clamps operable by means of several permanently magnetized slugs or blocks of special metal such as Alnico containing aluminum, nickel, cobalt, copper and iron, it is not my desire or intent to unnecessarily restrict the scope or utility ofthe improvement by virtue of this limited disclosure;

Referring to Figs. 1 and 3 inclusive of the drawing, the ground clamp with internal terminal disclosed therein, comprises in general, a circular backing plate 1' having a central opening 8 and a tubular element! of somewhat larger internal diameter than the opening 8 secured to and projecting away from'one side of the plate 1, both the plate 1 and the. element 9 being formed of electrical.insulation; a ground terminal l0 slid- .ably penetrating the plate opening 8 and having one end adapted for attachment to a conductor H whilexits opposite contact end is provided with a head I2 slidable within the sleeve element 9 and its medial portion is embraced by a helical compression spring l4 coacting with the head l2 and reacting. against the plate I; outer and inner coaxial annular cup-shapedpole-pieces l5, I6 respectively having fiat annular pole faces lying in a common plane, and being secured to the oppositeend's of a series of magnetized cores or blocks I1; and screw bolts. l8.firmly-'attaching the polepieces [5; IE to the backing plate 1 and simul- 3 taneously clamping these pole-pieces against the intervening magnet blocks ll.

The backing plate I and the sleeve element 9 may be formed of any durable electrical insulating material such as synthetic resin, hard rubber, or the like, and these parts may be permanently united in any suitable manner with the bor of the sleeve disposed coaxial with the opening 8. The ground terminal H) which is slidably confined within the opening 8 and element 9, may be formed of copper or copper alloy, and the contact face of the terminal head I2 is preferably covered with a, protective layer or coating of silver or the like. The conductor I l is ordinarilly a flexible insulation covered cable having its end provided with a terminal fitting l9 which is firmly attached to the outer end of the terminal l6 and is clamped against a terminal stop washer by means of a nut 21 and a lock washer 22.

The stop washer 20 v,coacts with a shoulder formed upon the terminal l0 and is so located relative to the terminal head 12, that when the ground clamp is not in use the contact surface of the head l2 will be forced outwardly beyond the common plane of the faces of the pole-pieces l5,

I3 by the spring I4 and the washer 23 will then engage the backing plate I.

The outer and inner annular cup-shaped polepieces l5, l6 may be constructed of ferrous sheet metal having high magnetic permeability with the aid of punches and dies, and the adjacent annular inner and outer flanges of the coaxial pole-pieces are segregated from each other by rings 24, 25 respectively, formed of non-magnetic material such as brass. netic slugs or blocks H are of cylindrical shape and are clamped between the pole-pieces l5, l6 and attached to the plate I by means of screw bolts, but any desired number of these blocks ll of diverse shapes and sizes may be secured to the pole-pieces in any other suitable manner. The core blocks 11 are preferably formed of material such as Alnico adapted to retain high magnetic energy when permanently magnetized, and when assembled as shown, these blocks I1 cooperate with the pole-pieces I5, [6 to produce powerful fields of magnetic influence spanning the rings 24, 25 outwardly beyond the common plane of the pole-pieces.

When the improved ground clamp unit has been constructed and assembled as shown in Figs. -1, 2 and 3, the magnet assembly and its suspension plate 1 will normally rest and float upon the helical spring l4, and the contact surface of the terminal head l2 will be located outwardly beyond the common plane of the pole faces. However, whenever the active faces of the polepieces l5, [6 are brought in proximity to a grounding member or body 26, the magnetic fields which constantly span the segregating rings 24, 25 will quickly clamp the pole-pieces to the body 23 and will force the terminal l0 into the sleeve element *9 thereby compressing the helical spring M and causing the outer surface of the terminal head E2 to snugly engage the body 26, as illustrated in Fig. 2. Electric current may then be caused to flow through the conductor H and terminal ill; and when the flow of current has been interrupted, the terminal clamp may be readily removed by moving or lifting the unit away from the surface of the body 26 sufficiently to remove the latter from the field of magnetic influence.

While the terminal ll] of Figs. 1 to 3 inclusive is disposed centrally within and is surrounded by the relatively movable magnet assemblage, such As shown, the six magspecific disposition of the parts is not essential, and the magnet assembly may in fact be located within and surrounded by an annular terminal.

as shown in the modification of Fig. 4. This modified ground clamp unit comprises in general a circular backing plate 21 movably confined Within a recess 28 formed in an annular terminal 30, by means of a closure disk 29; an annular series of helical compression springs 34 coacting with sockets 3| formed in the terminal recess 28 and reacting against the peripheral portion of the plate 21; outer and inner cup-shaped polepieces 35, 36 respectively having flat annular pole faces lying in a common plane, and coacting with the opposite ends of an annular series of ma netized cores or blocks 31; and a screw bolt 38 firmly attaching the pole-pieces 35, 36 to the plate 21 and clamping this plate to the intervening blocks 31.

The backing plate 21 of the modification may also be formed of durable electrical insulation, and is spaced from the closure disk 29 a distance sufiicient to permit the annular, contact surface of the terminal 30 to be forced downwardly beyond the common plane of the pole faces of the pole-pieces 35, 36, by the compression springs 34,: when the magnets are inactive. The annular terminal 30 is preferably formed of copper or copper alloy and may also be provided with a silver covered contact surface, and this terminal 33 has an integral terminal socket 39 to which the flexible conductor II is attachable in any suitable manner. The helical springs 34 are re tained in proper position by the sockets 3|; and the cup-shaped pole-pieces 35, 36 are preferably formed of sheet metal having high magnetic per; meability, while the blocks 31 are formed of material adapted to retain high magnetic energy When permanently magnetized, and may be fastened to the pole-pieces 35, 36 with the aid of screws or rivets 40 passing centrally through the blocks. The cooperating pole-pieces 35, 36 are segregated from each other by a non-magnetic inner ring 4|, and the outer pole-piece 35 is spaced from the terminal 30 but is guided for movement therein by an outer non-magnetic ring 42, the latter being formed of electrical insulation.

The normal operation and use of the modified ground clamp is substantially like that of Figs. 1, 2, and 3, and the magnetized. blocks 3'! constantly create magnetic fields spanning the spacer ring 4| onwardly of the common plane of the annular coaxial pole faces of pole-pieces 35, 36. However, when these fields are brought in close proximity to a grounding body 26, the magnet assemblage quickly becomes effective to compress the springs 34 and to clamp the annular terminal into snug engagement with the body 26, as depicted in Fig. 4. Electric current may then be passed from the conductor ll through the terminal 30 to the grounding body 26; and upon interruption of the current, the terminal clamp may be readily removed by merely lifting or moving the unit away from the magnetic surface of the body 26 a distance suflicient to remove this body from the field of magnetic influence.

It is to be noted that in both embodiments of the invention illustrated, the magnet assemblage is normally floating upon the compression springs which are supported by thetermlnal, so that the common plane of the annular magnet pole faces will in each case adjust itself to irregularities of the contacted body 26. The compression springs tend to move the terminal toward or against the grounding body 26 while the magnets tend to means:

,pull this body toward the fterminalythusrpro- ,ducing opposing forces which partially counter act each other and thereby make .it relatively :easy to release the clamping effect induced by the more powerful magnetic force. In each case, the cooperating coaxial annular pole-pieces provide extensive fields of magnetic influence, and in both embodiments the permanently magnetized blocks are concealed and protected within the cup-shaped pole-pieces. The helical springs of both types are also well concealed and protected, :andin each embodiment of the invention sufiicient clearance should be provided between the terminal and the magnet assemblage to permit slight relative rocking of these parts.

vFrom the'foregoing detailed description of several embodiments of my invention, it should be apparent that I have provided an improved ground terminal clamping unit which besides being exceedingly simple, compact and durable in construction, is also highly efiective in use and flexible in its adaptations. The various parts of theimproved clamp assemblage are obviously simple but durable and may be readily assembled or dismantled. The use of Alnico metal in the permanently magnetized blocks of the magnet assembly, insures prpduction of a powerful magnetic field, and the use of the cup-shaped pole-pieces enables concentration .of the field of magnetic influence throughout extensive annular areas which are disposed coaxial with the ground terminals. The floating ,spring suspension of the magnet also permits the pole faces to adjust themselves for proper cooperation with grounding bodies 26 of various shapes, and as previously indicated, any desired number of the permanently magnetized cores or blocks of diverse shapes may be utilized. It is however important that the current carrying conductors I0, 30 be insulated from the magnet assemblies in order to positively prevent the current from passing through the adjacent polepieces I5, of the magnets, since such flow of the current will burn the pole face edges and will thus prevent the springs I4, 34 from functioning properly. The invention has proven highly satisfactory in actual use especially as applied to welders ground clamps, although the improved features may also be utilized for other terminal clamping purposes.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise mode of use, of the clamps herein specifically shown and described, for various modifications within the scope constantlyfurgingthe conducting :means cute wardly beyond thexplaneof-said pole faces.

12.1-In .amagnetic clamp, electric current con-.- ducting means disposed symmetrically with respect to an axis, inner and outer circular pole pieces confined one within the other coaxially of said axis, means for suspending and insulating said pole pieces from said conducting means, said pole pieces having spaced flat portions provided with concentric cylindrical tubular flanges spaced from each other andprovided at their adjacent free edges with annular flat pole faces disposed in a common plane perpendicular to said axis, an annular group of permanently magnetized blocks contacting and secured between said fiat portions between said inner and outer pole pieces, and means interposed'between said conducting means and the outer-of said pole pieces for constantly resiliently urging the conducting means outwardly beyond the plane of said pole faces.

3. In a magnetic clamp, electric current conducting means disposedsymmetrically-with respect to an axis,'inner and outer annular pole pieces confined one within the other coaxially of said axis, means fol-uniting and for insulating said pole pieces from said conducting means, said pole pieces having spaced parallel fiat portions provided with integral concentric tubular flanges spaced from each other and said flanges being provided at their adjacent free edges with annular pole faces disposed in a common plane perpendicular to said axis, an annular group of permanently magnetized blocks confined in the space between said flat inner and outer pole piece portions, and spring means interposed between said conducting means and said outer pole piece for constantly resiliently urging the conducting means outwardly beyond the plane of said pole disposed in a common plane perpendicular to said axis, an annular group of permanently magnetized blocks contacting and secured between said fiat portions of both of said pole pieces, and

of th appended claims may occ t person spring means interposed between said conductskilled in the art; and it is also contemplated that specific descriptive terms used herein be given the broadest possible interpretation consistent with the actual disclosure.

I claim:

1. In a magnetic clamp, electric current conducting means disposed symmetrically with respect to an axis, inner and outer annular pole pieces confined one within the other coaxially of ing means and said outer pole piece for constantly urging the conducting means outwardly beyond the plane of said pole faces.

5. In a magnetic clamp, electric current conducting means disposed symmetrically with respect to an axis, inner and outer annular pole pieces confined one within the other concentrically of each other around said conducting means coaxially of said axis, means for suspendsaid axis, means for suspending and insulating 66 mg Said p018 Pieces from Said conducting means,

said pole-pieces from said conducting means, said pole pieces having spaced flat portions provided with concentric tubular flanges spaced from each other and provided at their adjacent free said pole pieces having spaced flat portions provided with concentric tubular flanges spaced from each other and provided at their adjacent free edges with annular pole faces disposed in a edges with annular pole faces disposed in a com- 70 c m on plane p pendicular to said axis, an

mon plane perpendicular to said axis, an annular group of magnetized blocks contacting and confined between the flat portions of said inner and outer pole pieces, and means interposed between annular group of permanently magnetized blocks contacting and secured to the adjacent surfaces of both of said flat pole piece portions, spring means interposed between said conductin means said conducting means and said pole pieces for and said outer Pole piece for constantly ur ng the conducting means outwardly beyond the plane of said pole faces, and an insulation member between the inner periphery of said outer pole piece and said conducting means for guiding the latter for movement longitudinally of said axis.

6. In a magnetic clamp, annular electric current conducting means disposed symmetrically with respect to an axis, inner and outer annular pole pieces confinedone within the other concentrically of each other within said conducting means coaxially of said axis, means for suspending and for insulating said pole pieces from said conducting means, said pole pieces having spaced flat portions provided with concentric tubular flanges spaced from each other and provided at their adjacent free edges with annular pole faces disposed in a common plane perpendicular to said axis, an annular group of permanently magnetized blocks contacting, and secured to the spaced fiat portions of both of said pole pieces,

and sprin means interposed between said 0011- ducting means and said outer pole piece for constantly urging the annular conducting means outwardly beyond the plane of said pole faces.

'7. In a magnetic clamp, annular electric current conducting means disposed symmetrically with respect to an axis, inner and outer annular pole pieces confined one within th other concentrically of each other within said conducting means coaxially of said axis, means for retaining said pole pieces within said conducting means, said pole pieces having spaced fiat portions provided with concentric tubular flanges spaced from each other and provided at their adjacent free edges with annular pole faces disposed in a common plan perpendicular to said axis, an annular group of permanently magnetized blocks contacting and secured within the space between said flat pole piece portions, spring means interposed between said conducting means and said outer pole piece for constantly urging the annular conducting means outwardly beyond the plane of said pole faces, and an insulation member between the outer periphery of said outer pole piece and said annular conducting means for guiding the latter for movement along said axis.

KARL A. BLIND.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,105,552 Downes July 28, 1914 1,561,554 Little Nov. 17, 1925 1,778,481 Boucher Oct. 14, 1930 2,083,845 Hovious June 15, 1937 2,170,287 Kinnebraw Aug. 22, 1939 2,287,112 Lourie June 23, 1942 2,312,083 Diane Feb. 23, 1943 2,429,526 Savon Oct. 21, 1947 2,437,633 Abram Mar. 9, 1948

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