US2680225A - Multiple unit resistor assembly - Google Patents

Description

June l, 1954v c. H. STEVENS, JR 2,580,225

MULTIPLE UNIT RESISTOR ASSEMBLY Filed July 8, 1953 4 Sheets-Sheet l ATTORNEYS June 1, 1954 Filed July 8' 1953 MUL TIPLE UNIT RESISTOR ASSEMBLY H. sTEvEN, JR 2 680 225 4 Sheets-.Sheet 2 Illu' (am "a," |30 1NVENTOR I Charles H. Stevens Jr BY M @am ATTORNEYS June 1, 1954 C. H. STEVENS, JR

MULTIPLE UNIT RESISTOR ASSEMBLY Filed July 8, 1953 4 Sheets-Sheet 3 ATTORNEYS June l, 1954 c. H. STEVENS, JR

MULTIPLE UNIT RESISTOR ASSEMBLY 4 Sheets-Sheet 4 Filed July 8, 1953 FI G I6 JNVENToR.

Charles H. Stevens,Jr.

l n IH FI IH lu ATTORNEYS Patented June l, 1954 OFFICE Claims.

rIhe present invention relates to apparatus for the control of the supplying of current to welding units and more particularly7 to improved apparatus for individual control by the individual welder whereby the current requirements of his job may be fullled without affecting the current requirements for other Welders plugged into the same apparatus. The present invention may be employed in combination with apparatus such as is shown and described in my copending application led of even date or with other apparatus providing constant voltage in the manner of my referred to apparatus.

An object of my present invention is to provide an improved resistor assembly for welding units wherein the desired amperage can be supplied for use in a particular welding unit by simple manual actuation of switches, various combinations of actuated switches placing preselected of a group of resistances in parallel with respect to each other and in series in the circuit to the electrode holder of a welding unit so as to give :i wide range current for that unit as required.

Another object of the present invention is to provided an improved resistor assembly for multiple welding units which is of rigid and well protected construction so as to withstand the hard usage to which such devices are normally subjected.

A further object of the present invention is to provide a substantially completely enclosed resistor assembly for supplying current to multiple welding units wherein the overall size and weight are at a minimum as opposed to other arrangements each or which normally accommodates but a single welding unit.

Still another object of the present invention is to provide an improved resistor assembly embodying removable drawers housing resistances and providing mountings for switches controlling inclusion of such resistances in the electrical circuit so that controls for a single welding unit are essentially separate and entirely removable for repair and replacement without requiring major disassembly operations or the like.

A still further object of the present invention is to provide an improved resistor assembly for multiple welding units wherein a single supply cable feeds all ci said units by the use of bus bars, the drawer assemblies being so cooperatively related to such bus bars that electrical disconnection is effected prior to removal of the individual drawers for safety in making repairs on a single drawer assembly without requiring dis connection of the main power source.

Another object of the present invention is to provide an improved resistor assembly wherein there is ilexibility of control by the individual welders without regard to requirements by other Welders.

Still another object of the present invention is to provide improved resistances which embody ample support with maximum cooling of the resistance wires along with unrestricted longitudinal expansion and contraction of the resistance wires.

Various other objects and advantages will become apparent from the detailed description to follow.

In the drawings:

Fig. 1 is a perspective View of my entire improved resistor assembly showing a cable plugged into one of the resistor drawers, the cable bee ing adapted to be connected to the electrode of a welding unit, and also showing one of the drawers partially withdrawn to expose the resistance coils housed therein;

Fig. 2 is a View of part of the bus bar assembly showing the connection for the inlet cable and also the knife switch arrangement whereby each of the drawers is detachably electrically connected with the bus bar assembly;

Fig. 3 is a top plan view of the arrangement of Fig. 2 with parts being broken away;

Fig. 4 is a longitudinal sectional view through one of the switch plungers of which several are employed with each drawer of resistors;

Fig. 5 is a rear perspective view of the assembly of Fig. l with part of the screening removed so as to expose the bus bar assembly at the rear of the plurality of drawers and also showing details of the framework;

Fig. 6 is a perspective view of one of the drawer resistor assemblies entirely removed and showing the switch arrangement on the inside of the front plate of the drawer;

Fig. 7 is a top plan view of the drawer assembly of Fig. 6;

Fig. 8 is a longitudinal vertical sectional view taken substantially on the plane of line 8 8 of Fig. '7;

Fig. 9 is a front elevational view showing at least one drawer assembly when mounted in place in the supporting framework;

Fig. 10 is an enlarged detail view of one of the resistance coils, partly in section and showing the manner in which the plurality of relatively movable porcelain blocks support the coils of wire for cooling and for freedom of expansion and contraction;

Fig. 11 is a vertical transverse sectional view taken substantially along the plane of line l-i I of Fig.

Fig. 12 is a vertical sectional View through a portion of the front plate of one of the drawer assemblies and showing the details of the spring switch contacts and the cooperation of the switch plunger therewith;

Fig. 13 is a detail view showing the pair of spring switch contacts as mounted on the insulating block therefor;

Fig. 14 is an end elevational view of the arrangement of Fig. 13;

Fig. 15 is a detail sectional view showing the cam-surfaced stud and bracket assembly which is carried by the front plate of each drawer.

Fig. 16 is a fragmentary schema-tic circuit and structure view of the upper and lower resistance coil arrangement of Fig. 8 with supply and work leads added and also schematically shown.

Referring more particularly to the drawings it will be seen that my improved resistor assembly l is comprised of a supporti-ng framework designated generally by the numeral i2 and providing multiple drawer-receiving spaces is, bus bar means l5 and a plurality of drawer assemblies I8.

The supporting framework i2 is best shown in Figs. 1, 5y and 9 as comprising four upstanding front corner posts 2G and 22 and rear posts 213 and 26, the front posts being joined adjacent their tops, midsections and bottoms by cross bars 28, 39 and 32, while `the rear posts are similarly joined at 31%, 35 and 38, angle iron being used because of its high strength and facile assembly into the construction shown. Additionally, vertical divider and rigidifying bars are provided at the rear of the framework at 40, 42 so that as viewed from the rear the framework is divided into six subdivisions although it will be understood that it is within my contemplation to construct my assembly for use by any practicable number of welding units.

As viewed from each of the sides there areprovided horizontal upper, intermediate and lower joinder bars 54, 46 and 48 joining the front and rear corner posts at each side. Intermediate the ends of the framework, the cross bars are joined by drawer supporting irons 5D, 52, 54 and 56 and also the upper drawer guides 53 and SEI at the upper ends of the rigidifying bars extending forwardly to the cross-bar 28.

In addition to the foregoing the framework includes bus bar supporting means in the form of three upstanding angle irons 62, iid and Sii located substantially centrally between the upstanding bars Ztl, di); Mi, d2; and 42, 25.

The entire framework described is preferably thru-welded at all joints although it will be understood that other modes and means of forming the joints may be employed as desired.

For protective reasons I provide the angulated roof member 68 over the top of the framework to protect the interior from precipitation and falling objects, etc., bolts or other attachment elements as at 'I0 securing the roof member 58 to the -top of the framework. At the top front of the framework and as shown in Fig. l, there is provided an overhang element 'i2 in the form of an elongated double thickness strip of metal which is secured by the attachment means in the form of bolts at l, the overhang being provided to protect the switch plungers of the drawer assemblies, to be described in detail hereinafter, from falling objects such as might be encountered on the job.

The framework is also provided with wire screening covering the sides and rear of the framework at 76, 18 and 8B, screws preferably being employed to secure the angle irons as at 32 and 84 over the corners of the wire scree to hold the same yto the framework. The screening over the lower central drawer space at the rear is preferably removable so as to provide access to the cable connection for the inlet power, as will presently be described.

As seen best in Figs. 2, 3 and 5, the bus means. l@ includes horizontal bus bars E35 and 8% joined by the single vertical bus bar di) at their centers. The horizontal bus bars Si) and 68 are secured to insulating pads, as of Bakelite, 92, Siti and :35 and 93, it and by bolts |94, the insulating pads in turn being secured to the bus bar supporting angle irons $32, Jl by bolts |55. For supplying electrical power to the assembly and partie" arly to the bus bar arrangement, an inlet cable its has its attachment end lili secured to the vertical bus bar by the bolt H2, as shown in Fig. 2, it being understood that the cable is desirably the output of such an arrangement as is shown and ciaimed in my referred to copending application. 'For electiically connecting each. of the drawer assemblies to be described hereinafter, prc= switch means-in the form of spring clips lli and H5 as seen best in Figs. 2, 3 and 5. Each clip includes a bus bar embracing portion H and resilient fingers i' and |22. One of the spring clips liliis secured by a bolt at 12s to the respective bus bar and the other spring clip of the pair is secured by a bolt extending through the insulating pad such as at ed.

As seen in Fig. 1, there are provided six drawer assemblies N3, one for each welding unit, and a power take-off cable such as at |25 is provided for each welder for coupling in the socket |25 at the front plate |30 of each drawer assembly.

Figs. 1, 6, 7, 8 and 9 show one of the drawer assemblies i8 as comprised of front piate i3 l, rear plate |32, longitudinally extending bars |313 and |36 at the sides of the bottom and inclined rigidifying straps at |38 and Mii at each side joining the rear and front plates to the longitudinally extending angle iron bars |341 and |36. The rear plate 32 has a centrally located opening through which a threaded stud M2 extends. Nuts li and 66 and Bakelite washers M8 and E55) on opposing sides of the rear plate are employed to secure the stud M2 in insulated relationship with the rear plate |32. The stud |42 has its outer end bifurcated and a knife switch element |52 is received therein and secured thereto by screws |54.

A plurality of resistances as at |56, six as shown, are mounted in each drawer assembly. As seen best in Figs. l0 and 11, each resistance |55 is in the form of a wire coil and is comprised of a mounting rod |58 of square or other non-circular cross-section having threaded ends at |E and |62 for mounting in the front and rear plates |30 and |32, as by nuts |54. Each resistance further includes a plurality of porcelain blocks |66 having a relatively flattened cross section but with substantially cylindrical peripheral surface portions at |68 and l, which cylindrical surface portions are only a small portion of the surface of a complete cylinder. The surn face portions |68 and H0 have grooves V12 formed therein which are substantially in the locus of a helix, the widths and depths of the grooves being such as to support the coiled wire |14 with a minimum of contact and with freedom of air circulation beneath the wire and within each groove as at |16.

The plurality of blocks |66 are alternately relatively rotated through 90 relative to each other and since they have openings therethrough corresponding to the cross section of the rod |58 the blocks will be held in their desired relationship. Pins |78 and Hill` are engaged through the rod |58 spaced from the end blocks so as to afford relative longitudinal movement between the blocks upon expansion or contraction of the wire of the coil |74. Prior to assembling the resistance unit the wire is preformed into a coil and the blocks are engaged on the rod as described and shown. Next the wire coil is threaded into the grooves so as to resiliently hold the blocks in a longitudinal relationship which is free to vary as the temperature varies.

Adjacent the rear plate |32 each coil has its wire terminal extended for connection to the transverse bus bar |82 as at |84, |56, |88, |90, m2 and |94, the bus bar |82 in turn being connected to the inner end of the stud |42 so that all of the resistances are in parallel relative to each other and in series with the inlet cable |08. The opposing end of each coil has its wire terminal as |95 extended for connection to one of the individual posts as at |26, in Fig. 12, a pair of nuts |98 securing the same to the post. It is to be noted that each coil is connected to but one of the posts as |96 and each post in turn is electrically connected with but one plunger clip as 200.

The plunger clips are best shown in Figs. 12 14 as being substantially U-shaped in form with the leg portions 202 and 2M somewhat bowed and resilient so as to resiliently electrically contact the plunger 205 engageable therebetween. A pair of such clips 2li@ and 29E are secured in longitudinally aligned spaced and insulated relationship by the posts |95 and |91 engaged through the mounting enhancing the resiliency of the clips, I provide steel springs 2|@ which in side elevation as in Fig. 13 are S-shaped and in end elevation as in Fig. la are substantially U-shaped with the legs 2|2 and 2|4 bowed to conform with the leg portions 202 and 2l4 of the clips. The bight portion Elli is positioned so as to be beneath the plunger presently to be described.

Whereas the posts |95 and clips 20@ are individually electrically isolated by the insulation ll, the clips 20| and the posts |97 are all electrically interconnected with each other by the bus bar 2 I8 which in turn is connected with the fuse 22|! by the bolt 222. The other end of the fuse has connected thereto at the bolt 224 a conductor 226 which extends to the bracket 228, 222 mounted on the inside of the front plate at its center for electrical connection with the split and cam surfaced stud 23), the latter constituting the outlet to which a Welder connects his cable as the cable |26 in Fig. l.

in order to include a resistance in the circuit, l. provide a plurality of plungers 2%, one for each coil. As shown in Fig. 4 a plunger 2F36 is disclosed as including a Bakelite body 232 molded so as to include a finger-engaged enlarged head 234, and an elongated reduced diameter portion 236 on which the Bakelite washer 23S is engaged and held in spaced relation to the head 234 whereby withdrawal of the plunger relative to Bakelite insulator block 208. For

the front plate |30 is limited, the shoulder at 240 acting to limit inward engaging movement of the plunger. The body 232 has a further reduced diameter portion at 242 and an axial tapped bore 244. A tubular sleeve 246 preferably of brass is engaged on the reduced diameter portion 242 and has its end turned in at 248 to provide a seat. A steel conical element 2&0 is engaged on the seat and a ilat head screw also of steel is inserted through the conical element and threaded into the bore 244 with the head 252 tightly abutting the conical element 250 so as to hold the brass sleeve firmly in place on the Bakelite body 236.

Referring once again to the resistance coils as shown in Figs. 6-8, I employ six coils the bottom three of which as at 254 are all ampere coils made from No. 4 Nichrome wire, fifty turns. The upper three coils 256, 258 and 25E) are made from No. 13, No. 10 and No. 7 Nichrome wire with '75, 52 and 48 turns, respectively, to provide l0, 20 and 40 ampere coils, respectively. With such coils the Welder, by proper selection and actuation of the plungers 296, can provide in his cable |26 amperage ranging from 10 amperes to 310 amper-es in l0 ampere increments. In order not to overload, the fuse link 220 has a maximum capacity of 400 amperes. Of course, the numbers of turns employed, wire size, etc., are by way of example and may be varied to fulfill special requirements.

There is shown in Fig. 16 a schematic view of an electric circuit which may be used wherein S. P. denotes source of power and W denotes work I with all other parts of the circuit and structure designated as in the other iigures of drawings.

Thus, if a Welder requires 80 amperes for a particular job, he merely presses one of the plungers 236 which is identied as controlling the circuit to one of the 80 ampere coils, the plunger by means of the sleeve 246 completing the circuit between the switch or contact clips 202 and 253i, as shown in full lines in Fig. 12. Current will then pass from the source through the cable |28, bus bar 90, clip H4, knife switch element 52, stud |42, coil 254, contact clip 263D, sleeve 251e, clip 20|, bus bar 218, fuse clip 220, strap 22e, stud 230 and cable I 2li to the welding electrode, not shown. Of course, if 70 amperes are required, the plungers inserting the 40, 20 and l0 ampere coils are pressed instead, current flowing in series through the parallel group of resistance coils.

When repairs or replacements are required or if for any reason it is desired to obtain access to the coils or other associate elements w" hin the framework, it is merely necessary to grip the handle 262, as in Fig. 1, and slide the drawer outwardly. For safety the knife switch element |52 breaks contact with the clip contacts l i4 and I6 upon initial withdrawing movement of the drawer so as not to have live coils exposed.

As this invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, the present embodiment is therefore illustrative and not restrictive, since the scope of the invention is defined by the appended claims rather than by the description preceding them, and all changes that fall within the metes and bounds of the claims or that form their functional as well as conjointly cooperative equivalents, are therefore intended to be embraced by those claims.

I claim:

1. A resistor assembly for multiple welding units comprising a support, plural drawer assemblies removably mounted in said support, a source of electrical power, each of said drawer assemblies including multiple resistances, switch means releasably electrically interconnecting said source of electrical power with common ends of said resistances in each drawer assembly when the respective drawer assembly is in its non-removed relationship, additional switch means associated with the other end of each oi said resistances and associated with an outlet adapted to supply current to a welding unit, said additional switch means being selectively operable to include preselected of said resistances in the electrical circuit so as to control the amperage fed to the electrical outlet.

2. A resistor assembly for welding units coniprising a framework providing multiple drawer spaces, a drawer assembly removably mounted in each drawer space, each drawer assembly cornprising multiple resistances, a source of electrical power connected with one end of each o' resistances, switch means associated with the other end of each of said resista-ness and asso-- ciated with an outlet adapted to supply current to a welding unit, said switch means being selec-l tively operable to include preselected oi said resistances in the electrical circuit so as to control the amperage fed to the electrical outlet.

3. A resistor assembly for welding units comprising a framework providing multiple drawer spaces, a drawer assembly removably mounted in each drawer space, said framework having bus bar means behind each drawer space to be connected with a source ci electrical power, switch means releasably electrically interconnecting each drawer assembly with said bus bar means, each drawer assembly comp/risingmultiple resistances each having one end thereof connected with a portion of said switch means, additional switch means associated with the other end oi each of said resistances and associated with outlet adapted to supply current to a welding unit, the latter switch means being selectively operable to include preselected of resistances in the electrical circuit so as to control the amperage fed to the electrical outlet.

e. A resistor assembly for welding units coinpi g a framework providing multiple drawer spaces, a drawer assembly removably mounted in each drawer space, said framework having bus bar means behind each drawer space adapted to be connected with a source of electrical power, switch means releasably electrically interconnect-- ing each drawer assembly with said bus bar means, drawer assembly comprising multiple resistances each having one end thereof connected with a portion of said switch means, additional switch means associated with the other end of each of said resistances and associated with an outlet adapted to supply current to a welding` unit, the latter switch means being selectively operable to include preselected of said resistances in the electrical circuit so as to control the amperage fed to the electrical outlet, said first recited switch means including spring clips on the bus bar means and a knife switch element carried by each drawer assembly for cngagernent with the respective spring clips.

5. A resistor assembly fo welding units comprising a framework providing multiple drawer spaces, a drawer assembly removably mounted in each drawer space, each drawer assembly comprising multiple resistances, a source of electrical power connected with one end or" each of said resistances, switch means associated with the other end oi' each of said resistances and assoiated with an outlet adapted to supply current to a welcing unit, said switch means being selectively operable to include preselected of said resistances in the electrical circuit so as to control tlie amper-age fed to the electrical outlet, and a fuse in the electrical circuit between the switch means and said electrical outlet.

6. i resister assembly for welding units comprising multiple resistances, a source of electrical power connected with one end ci each ci said resistances, switch means associated with the other end of each of said resistances and associated with an outlet adapted to supply current to a welding unit, said switch means being selectively operable to include preselected ci said resistances the electrical circuit so as to control the ainperage fed to the electrical outlet, said switch means including push plungers, and a pair oi' longitudinally spaced contacts ier each push plunger, one of each of said pairs or" contacts being electrically connected with the respective push plunger and with a respective resistance while the other is selectively electrically en "fl by said plunger and is at all times connected with the electrical outlet,

References Cited in the file o this patent UNlTED STATES PATENTS Number Name Date 1,534,288 smith Apr. 21, 1925 2,023,544 Pierson Dec. l0, 1935 2,123,631 Koehler July l2, 1933 2,228,167 Kimball Jan. 19il 2,287,402 Wood et al "une 23, lef-l2 2,390,790 minel et al. Tijaec. 11, 19425 2,431,904 Andrews Dec. 1947 2,591,849 McDowell Apr. 8, 1G52

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