US2490770A - Electric iron - Google Patents

Description

l. E. ASKE 2,490,770

ELECTRIC IRON Dec. 13, 1949 2 Shets-Sheet 1 Filed Sept. 6, 1945 v l I N V EN TOR. Mn; 4. flJ/rz 22 M W r7ffa/m ri.

Dec. 13, 1949 l. E. ASKE 2,490,770

' ELECTRIC IRON Filed Sept. 6, 1945 2 Sheets-Sheet 2 Lf/QQ IN VEN TOR.

Patented Dec. 13,1949

UNITED STATES PATENT OFFICE 8 Claims.

This invention relates to improvements in electric irons.

The main objects of this invention are:

First, to provide an electric iron in which the sole plate is formed as a cast iron casting and the heating element holders formed of sheet steel are cast bonded thereto, the holders constituting chills whereby the character of the grain of the cast iron is substantially modified or changed and compacted, or a finer grain produced than would result without the chill action, resulting in a unit which is capable of receiving a high polished smooth finish.

Second, to provide an electric iron to which the heating units may be very effectively clamped, providing for efficient heat exchange and at the same time one which permits the repair or replacement of the heating elements should occasion require.

Third, to provide a structure having these advantages which may be very economically manufactured, both as to its parts and the assembly thereof.

Fourth, to provide an electric heating umt having a bendable sheet metal heating element holder having a cast bonded joint or union with the body of the iron, preventing any relative warping or distortion of the holder resulting from variations in temperature.

Objects pertaining to details and economies of the invention will appear from the description to follow. The invention is defined and pointed out in the claims.

A structure which embodies the features of my invention is illustrated in the accompanying drawing, in which:

Fig. 1 is a side elevation of an electric sadiron embodying my invention.

Fig. 2 is a transverse section on line 2-2 of Fig. 3, the handle being partially broken away.

Fig. 3 is a fragmentary plan view of the sole plate unit viewed on line 3--3 of Fig. 1 with the heating elements installed therein and partially sectioned and broken away.

Fig. 4 is an enlarged fragmentary view in transverse section on a line corresponding to line 4--4 of Fig. 3.

Fig. 5 is a fragmentary view shown in partial section illustrating steps in the practical manufacture of the structure, this showing the method of preparing the mold.

Fig. 6 is a fragmentary view in section showing details of the mold.

Fig. 7 is a fragmentary view showing details of the structure and the relationship of its parts in the mold after the metal has been poured.

Fig. 8 is an enlarged fragmentary view showing further structural details and the relation of certain of the parts prior to assembling other parts therewith.

Fig. 9 is an exploded View of one of the heating elements and its holder. It should be understood, however, that the holder does not constitute a part of the heating element.

I have illustrated my invention as embodied in an electric sadiron, but certain features thereof are adapted for embodiment in other forms of electric heating units.

The embodiment of my invention illustrated comprises the sole plate body member I which is desirably formed as a cast iron casting.

The sheet steel heating element holders 2 are of tray or channel shape and are substantially embedded and cast bonded to the cast iron body member, this being shown conventionally at 3 in Fig. 4. These holders are of substantial depth and substantial portions of the walls thereof are surrounded by the cast metal so that the cast bonded joint or union extends upon the sides of the holder members. Preferably portions 4 of the holder members project above the cast bonded zones 5 and constitute bendable flanges adapted to be clamped upon the heating elements.

To facilitate this clamping, the edges of the cast metal surrounding the flange portions 4 are beveled as shown at 6. This is a matter of convenience in bending or rolling down the flanges into clamping engagement with the heating units. These holders are longitudinally disposed and in laterally spaced relation providing longitudinal ribs 1 between the holders of substantial mass and adapted to receive the thermostat controls designated generally by the numeral 8. I do not illustrate the details of the thermostat as such units are commercially available; neither do I show the electrical connections as they would be readily understood by those skilled in the art to which the invention relates.

The heating elements comprise suitable spiders or cores 9 on which the resistance wires ID are wound, the resistance wires being provided with terminals ll. Bottom and top insulating plates [2 and I3 are provided, usually of mica. Both plates are provided with holes M to receive the terminals ll although it will be understood that the holes of the lower insulating plate do not function in the assembly. These heating elements are shaped to fit into the holders 2 which it will be understood are modified or adapted to the particular shape of iron. In the embodiment illustrated the iron has a straight heel portion; other types of iron are tapered at both ends. It will be understood that the holders and heating elements are correspondingly shaped. However, one of the advantages of the structure is that the heating element covers a large percentage of the area of the sole plate.

The projecting edges of the holders are folded 00 over upon the top or cover plate l5 as clearly shown at [6 in the drawings. These bendable flanges may be turned up to permit removal of the heating element if occasion should require and again bent to retaining position, which is also a feature of considerable advantage in this structure. The holders cover a substantial area of the sole plate body and permit the use of heating elements of substantial area.

The clamping flanges or holders preferably have a substantial overlap on the plate I5 as shown at it, this constituting an additional heat transfer means for the plate. l5, a substantialamount of the heat from the plate l5 being transferred or taken up by the flanges l6 and transferred through the holder to the body of the sole plate. While it is of substantial manufacturing advantage to have the edges of the holders extend substantially from the cast ironthat is, above the bonding zone, desirable results can be had without that as the portions of the sides of the holders can be broken away from the surrounding cast iron and folded upon the heating element. There is, however, a very substantial manufacturing advantage in having the edges of the holders project above the bond.

I use the term cast bonded to designate the joint or union between the cast iron or sole plate body and the holder which isvery secure throughout the contacting surfaces and it is my opinion that the bond includes the factor of common oxide-that is, the merging of the oxide of the two metals under the casting conditions; also the shrinkage of the cast iron upon the steel holders, and there may be also other factors. In any event, the bond or union between the holders and the cast iron body of the sole plate is very effective and it is not at all affected by such difference in the coefficients of expansion of the two metals and the joint or union is very uniform and complete throughout the contacting area of the molten metal with the holder.

The cast bonded joint between the holders and he cast metal is highly efficient as a heat transfer joint, and as the cast bonded union extends throughout the contacting surfaces there are no portions that are out of contact and the holders cannot warp away from the cast iron. Another highly important advantage of the structure is that the holders form effective chills and result in closing up the grain of the cast iron, providing a highly desirable face for polishing. This feature of the holders constituting chills results in an iron having very superior qualities or characteristics and results that cannot practically be secured by changing ingredients of the cast iron.

it is desirable that the carbon content of the cast iron shall not be too low, otherwise the sole plate body resulting from casting with the holders constituting chills may be so hard that it cannot be machined effectively. My present experience is that cast iron of a carbon content of 3.20 percent and silicon of 1.98 percent produces a casting that is much too hard to machine; since the chilling effect of the steel holders raises the combined carbon content from .63 percent at the. central rib to .80 percent on the sole plate surface. I have found that an iron having 3164 percent total carbon and 2.31 percent silicon will chill to .70 percent combined carbon and produce a machineable surface that will take-a high polish, The steel holders, therefore, make it possible to use a softer iron that is easier to cast and still have a fine grain structure of iron on the sole plate. While iron is highly desirable and is at present the material I prefer, other metals might be used for both the sole plate body and the holders with desirable results. The coefficient of expansion of the steel and the cast iron does not greatly vary, which is another advantage of using steel. It is also desirable that the thickness and mass of the cast metal shall be such that the holders act as chills to affect the face structure of the iron.

In my experience the use of a .025 gauge for steel holders and three-sixteenths of cast iron beneath the holders results in a very desirable structure; In casting the iron around the steel holders I have found it desirable to first tin the steel holders which appears to improve the bond although a satisfactory bond may be had without this.

In Figs. 5, 6 and 7 I illustrate steps in the manufacture. The pattern ll is arranged on the mold member is, the holders 2 are inserted in cavities provided therefor in the pattern, and the sand of the mold member I9 is suitably compacted around the pattern and the holders. The pattern is then removed providing the mold cavity designated generally by the numeral 20, Fig. 6.

' The body metal iron indicated at 2! is then poured, with the results that I have pointed out.

The top 22 of the iron is provided with suitable handle 23 and is secured to the sole plate in any suitable manner. The control switch 2% is conve tionaily shown. I have not illustrated the wiring and connections as these matters will be understood by those skilled in the art.

I have illustrated and described my invention in a highly practical embodiment thereof. I have not attempted to illustrate various adaptations and applications of the invention as it is believed this disclosure will enable those skilled in the art to embody my invention as may be desired. While the invention is illustrated as embodied in an electric iron I contemplate other adaptations to electric heating implements and devices. It is believed such adaptations will also be understood by those skilled in the art.

Having thus described my invention, what I v claim as new and desire to secure by Letters Patent, is:

1. An electric iron comprising a cast iron sole plate body member having laterally spaced upwardly facing heating element holders cast bonded therein with the longitudinal edges of the holders projecting from the body member, the lower portions of the sides of the holders being surrounded by integral portions of the cast metal body member and having cast bonded.

union therewith, said body member having an integral longitudinal rib of substantial mass between said holders, heating elements disposed in said holders, top plates for said heating elements, said flanges of said holders being bent inwardly into retainin clamping engagement with said top plates, and a thermostat mounted on said longitudinal rib.

2. An electric iron comprising a cast metal sole plate body member having an upwardly facing heating element holder of bendable metal embedded in and cast bonded in the body member with side portions of the holder projecting from the cast metal and constituting bendable elements for securing a heating element to the.

holder.

3. An electric iron comprising a cast iron body member, an upwardly facing sheet metal heating element holder of channel section embedded therein and cast bonded theretowith the cast.

metal having shrunk engagement with the holder including substantial portions of the sides thereof, edge portions of the sides of the holder extending above the cast bond between the holder and the cast body to constitute bendable flanges, a heating element arranged in said holder, and a retaining plate arranged on said heating element, said flange portions of said holder being folded inwardly onto said plate in clamping heat transfer engagement therewith.

An electric iron comprising a cast iron sole plate body member having an upwardly facing sheet steel heating element holder of channel section cast embedded in the upper side thereof with the cast metal embracing substantial portions of the sides of the holder and with portions of the sides of the holder projecting above the joint between the body member and the sides of the holder and constituting bendable heating element retaining flanges.

5. An electric heating unit comprising a cast metal body member having an outwardly facing sheet metal heating element holder of channel section cast embedded therein with the cast metal embracing substantial portions of the sides of the holder in heat transfer bonded relation thereto with portions of the sides of the holder projecting beyond the joint between the cast body member and the holder and. constituting bendable heating element fasteners, a heating element disposed in said holder, and a retaining plate superimposed on said heatin element, said bendable heating element fasteners being lapped and clamped upon said retaining plate in retaining heat transfer engagement therewith.

6. An electric heating unit comprising a cast metal body member having a sheet metal heating element holder of upwardly facing channel section embedded and cast bonded therein, said holder having portions of its sides projecting beyond the cast joint between the body member and the sides of the holder and constituting bendable elements, a heating element superimposed on said holder, and a retaining plate superimposed on said heating element, said bendable elements being lapped upon said retaining plate in heat transfer retaining engagement therewith.

7. An electric iron comprising a cast metal body member, an upwardly facing sheet metal heating element holder of channel section cast embedded therein with the cast metal embracing substantial portions of the sides of the holder member and with portions of the sides of the holder extending above the joint between the body member and the sides of the holder and constituting bendable flanges, a heating element arranged in said holder, and a retaining plate arranged on said heating element, said bendable flanges of said holder being folded upon said plate in clamping retaining heat transfer engagement therewith.

8. An electric heating unit comprising a cast body member having an outwardly facing sheet metal heating element holder of channel section cast embedded therein with the cast metal embracing substantial portions of the sides of the holder and With portions of the holder projecting from the cast body member and constituting bendable heating element fasteners, and heating element disposed in said holder and secured thereto by said bendable fasteners.

IRVING E. ASKE.

REFERENCES CITED he following references are of record in the

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