US2138720A - Sadiron sole plate and method of making - Google Patents

Description

Nov. 29, 1938. H. c. WRIGHT 2,133,720

SADIRON SOLE PLATE AND METH OD OF MAKING Filed Sept. a, less 13 19 1a 1a Z1 7 Q 2.5 I I g Patented Nov. 29, 1938 SADIRON SOLE PLATE ANDMETBOD OF MAKING Horace C. Wright, Chicago, 111., aasignor to Chieago Flexible Shaft Company, Chicago, 111., a

corporation of Illinois Application September 3, 1936, Serial No. 99,223

'7 Claims.

This invention relates to sadirons and has special reference to a sole plate for sadirons and of a method for making the same.

The invention contemplates a sole plate of cavity. The main cavity is adapted to receive 15 a heating element and a retaining element as disclosed in the copending application of Ivar Jepson, Serial No. 38,533, filed August 30, 1935. In the past, the sole plates of this character have been made from steel or malleable iron through 20 forging operations, which method has been satisfactory in some respects but highly unsatisfactory in others. The cost of producing the sole plates in quantity has been high because of the close tolerances allowed in the size of the cavity 25 which has resulted in a considerable proportion of rejects. Even when the tolerances are maintained within the closest limits with which the forging operation can be reasonably successful the variation in the size of the cavity is such as 30 to introduce major difficulties in the manufacture and assembly of the iron. Another source of serious trouble is in the fact that the forging operations must be conducted hot and, under the circumstances, there is a tendency toward the 35 formation of scale and pits resulting from scale,

on the bottom surface of the cavity. Since the heat from the heating element must be carried across this face these irregularities have a material effect on the rate of heat transfer. More 40 than this, however, the presence of pits or points along the surface where the heating element cannot be pressed firmly against the surface results in a burning out of the heating element because in these small areas the heat is not properly con- 45 ducted away from the resistance wire of the heating element, causing the wire to become overheated and to fuse, thus opening the circuit through the element. 'I'heproduction of a sole plate of this character which would be free of 50 the defects enumerated on a commercially feasible basis has, therefore, been an important problem.

Among the objects of the invention is the provision of a generally improved sole plate of great- 56 er uniformity in production, of lower cost, of im- 'rected to Figure 1.

proved properties, and wherein the bottom of the cavity therein is smooth and bright, the dimensions of the cavity are consistently uniform and the side walls of the cavityare vertical with respect to the bottom thereof and the provision of a method for making the sole plate whereby certain economies are effected and wherein the base plate and side walls are independently formed and thereafter brazed together to form the sole plate.

Other objects and advantages will become apparent from the following description and the accompanying drawing, in which- Figure 1 is an expanded view showing the parts entering into the construction of the sole plate;

Fig. 2 is a perspective view of the finished sole plate;

Fig. 3 is a section on the line 3--3 of Fig. 2, and

Fig. 4 is a section on the line 4-4 of Fig.

The structure of the sole plate will be apparent from a description of the method for making the same when considered in connection with the drawing and attention is, therefore, first di- A base plate designated generally by the numeral 5 is first cut from a sheet of rolled metal having plane upper and lower faces. Advantageously this will be a sheet of cold rolled steel or other cold rolled metal, as in this manner the scale and pitting associated with hot working processes are avoided and the sheet will, without further processing, have a smooth and bright upper and lower surface. In the present instance, the base plate 5 is cut from a sheet of about stock, this being the thickness desired in the cavity portion of thesole plate. The base plate 5 is then subjectedjo a swedging operation along. the upper edge or its periphery so as to bevel at least a portion of the edge thereof as shown at 6 through which operation a considerable amount of grinding is eliminated in the finishing operations. The marginal side walls designated generally by the numerals I and 8 are cut to length from a straight rod of stock which is rolled to the desired cross-sec-' 5 tional dimensions, a sloping side as shown at 9 being rolled on the stock at the mill. These rods are preferably made of cold rolled steel in the usual manner. The side members 1 and 8 are then subjected to a forming operation through which they are given a curvature conforming to the curvature of the side of the base plate 5 so that when placed thereon the outer beveled sides 9 will form a continuation of the beveled portion 8 of the base plate and the forward ends H and u l2 thereof will abut each other at the forward end of the base plate. A back wall member I3 is likewise cut to length from rod stock which is cold rolled to the proper cross-sectional shape and dimensions at the mill. This member may have a beveled side M of the same or a different slopefrom the beveled side 9 and is adapted to be interposed at the rear of the base plate 5 between the spaced ends of the side members I and 8 so that the side N forms a continuation of the rear edge of the base plate 5. The member I3 is, in this instance, drilled and tapped, as shown at l5, for the purpose ,of supporting other parts of the iron structure. Rods l6 and I! also preferably of cold rolled steel, though not necessarily so, are cut to size to form the side walls for the thermostat well, as shown in Fig. 2. A block l8 which may be tapped and drilled, as shown at 19, is cut to size to be interposed between the well walls l6 and I1 against thebase plate 5 for the purpose, in this instance, of supporting a portion of the thermostat .mechanism. A boss 2| which is drilled and tapped, as shown at 22, is cut of somewhat greater height, in this instance, than the side walls I and 8 and is adapted to be positioned with its end against the base plate 5 in the manner shown in Fig. 2, thereby serving as an end wall for the thermostat .well and for the purpose of attaching the super-structureof the iron. A second boss 23 having an annular shoulder 24 adjacent its upper end is cut in a suitable manner and is of such height that the distance between the lower end thereof and the lower face of the shoulder 24 is substantially equal to the height of the side walls I and 8, whereby when positioned in the manner shown in Fig. 2 the shoulder 24 overhangs and confines the upper edge of the side walls I and 8.v

The elements are assembled together in the positions shown in Fig. 2 and are firmly held in these positions by any suitable means as, for example, by spot-welding or by the use of a suitable jig. While I have satisfactorily employed spot-welding for the purpose I prefer to employ a jig, the particular structure of which forms no part of this invention and is consequently not shown.

With the elements held or secured in the positions described, the parts are brazed together in a brazing furnace according to methods well known in the art. The brazing operation involves the use of a brazing medium which may consist of wire, chips, or paste, of a suitable brazing metal as is well known in the art. In this instance, I prefer to use wire as the brazing medium which may be either copper wire or a wire made of a copper zinc alloy. This brazing medium is placed along the junction of the surfaces to be brazed and the assembled sole plate is passed through a brazing furnace. The brazing oven is of the well known type employing control of the atmosphere in the furnace which are commonly known as controlled atmosphere furnaces, suitable types being manufactured by the General Electric Company and The Electric Furnace Company. In this furnace the temperature of the sole plate assembly is brought to a point at which the brazing medium becomes molten whereupon the molten metal flows through capillarity into the interface between the parts, the atmosphere in the furnace being controlled as to its chemical action both upon the sole plate and the brazing medium. As the sole plate assembly moves on through the brazing furnace the temperature is gradually reduced so that the brazing medium solidifies and the temperature of the composite structure is reduced to a point at which it may be removed from the furnace without detrimental effect.

The brazed sole plate is then removed from the jig, the annular beveled edges 25 are ground to smoothness and to the proper slope, the edges and the bottom of the plate are polished and subsequently electro-plated according to the usual procedure in finishing sole plates of this character.

The finished and plated sole plate as shown in Fig. 2, when assembled in the iron cannot be distinguished from a sole plate made by the use of the foregoing operation. The sole plate is, however, characterized by the smooth and bright bottom of the cavity 28, by the freedom of this bottom from pits or scale, by the accurate inside dimensions of the pit 26, and by the smooth vertical sides of the pit which meet the bottom at a sharp right angle. These properties are of material value in the sole plate in that the absence of pits or scale greatly reduces the number of irons which become defective in use due to the buming out of the heating element. The smoothness and brightness of the surface substantially facilitates the transfer of heat to the sole plate. The accuracy in the dimensions of the cavity permits the heating'element and the retaining element subsequently inserted in the cavity to fit therein within close limits and materially reduces the cost in that heating elements of a single fixed size may be utilized in the assembly of the irons as distinguished from the provision of a plurality of sizes differing from each other a small,

amount, as has been heretofore necessary to obtain a close fit.

Wholly aside from the improved properties of the sole plate the method permits of substantial reduction in the cost of manufacturing the sole plate since the various elements may be turned out by large scale production methods and the various steps of the method may be conducted on a large scale production basis with a relatively small percentage of rejected product. This is contrasted with the forging operations of the prior art in which the forging of this piece constitutes a very difiicult forging operation because of the necessity of maintaining close limits in size and the necessity for obtaining in the production at least a reasonably smooth and scaleless surface at the bottom of the cavity. Material savings are also made in the finishing operations by the reduction in the amount of grinding required to prepare the article for plating operations.

I am aware that numerous alterations and changes may be made in the invention as herein described without departing from the spirit of the invention and I do not wish to be limited except as required bythe prior art and the scope of the appended claims, in which- I claim:

1. The combination in a sole plate for sadirons, of a base plate comprising a fiat rolled metal sheet having smooth surfaces free from pits and scale, upstanding marginal preformed walls thereon of a cross-section to prevent Warpage of the base plate and defining a top cavity for the reception of a heating element between said walls, and means within the cavity for attaching the super-structure of an iron, the sole plate being characterized by the accurate dimensions of said cavity, smoothness of the bottom of said cavity, and by the fact that said elements are se- "cured in position by a capillary layer of brazing material.

2. The method for making sadiron sole plates of the type having a heating element cavity and annular walls which includes the steps of cutting a base plate from smooth, bright'stock of rolled cross-section, cutting peripheral side walls of required length from straight smooth stock, bending said walls to the required curvature, securing said parts in the desired relationship and thereafter brazing said parts together in a furnace.

3. A method for making sadiron sole plates comprising cutting a base plate from a fiat sheet of smooth rolled metal, preshaping peripheral side walls for said plate, assembling said side walls on said plate to provide a top cavity therein having a smooth bottom, and thereafter brazing said parts together in a brazing furnace to produce successive plates wherein'the size and shape of the cavities are maintained within close limits. 4. A method for making sadiron sole plates comprising cutting a base plate from a flat sheet of rolled metal having a smooth scaleless surface, preshaping peripheral side walls and centrally disposed walls for said plate from rolled metal, assembling said walls on said plate, applying a brazing medium to the junction between said parts, and thereafter passing said assembly through a brazing furnace while retaining the parts in said position to produce successive plates in which the spaces between the walls are maintained uniform within relatively close limits.

5. A method for making sadiron sole plates comprising cutting a base plate from a flat sheet of cold rolled steel, preshaping peripheral walls for said plate from rods of predetermined rolled cross-sectional shape, preshaping walls for a centrally disposed thermostat wall, forming attaching means for the super-structure of the iron, assembling said parts in the desired relation, brazing said parts together in a brazing furnace while maintaining the parts in accurately fixed relation to produce uniformity of size in successive plates, and thereafter grinding, polishing and plating the bottom and sides of the sole plate thus produced.

6. The method for making sadiron sole plates comprising cutting a base plate from a flat sheet of cold rolled steel, beveling the edges of said base plate to slope inwardly from bottom to top, preshaping peripheral walls for said plate from rods having a beveled side rolled thereon, of a slope substantially identical with the slope of the beveled edges on said base plate so that when placed together said bevels are substantially coplanar, assembling the side walls on said plate, and thereafter brazing said parts together in a brazing furnace.

'7. The combination in a sole plate for sadirons, of a base plate comprising a flat rolled metal sheet having smooth surfaces free from pits and scale, upstanding marginal walls or rolled section thereon defining a top cavity for the reception therein of a heating element, the base plate and walls being of a thickness to substantially resist war-page of the sole plate in service, centrally disposed base walls on said plate within the cavity defining a thermostat well, and means within the cavity for attaching the super-structure of an iron, the sole plate being characterized by the accurate dimensions of said cavity, smoothness of the bottom of said cavity, and by the fact that said elements are secured in position by a capillary layer of brazing metal.

HORACE C. WRIGHT.

CERTIFICATE OF CO RRECTI ON Patent No. 2,158,720.

' HORACE 0.

November 29, 1958 WRIGHT.

It is hereby certified that error appears in the printedspecification of the above n b patent requiring correction as follows; Page}, second column, line 1, claim 5, for the word "wall" read well; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.-

Signed and sealed this 7th day of February, A. D. 1959.

(Seal) Henry Van arsdale Acting Commissioner of Patents.

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