US2536767A

US2536767A - Cast-metal electrically-heated device and resistance elements therefor

Info

Publication number: US2536767A
Application number: US703600A
Authority: US
Inventors: Alfred E Reimers
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-10-16
Filing date: 1946-10-16
Publication date: 1951-01-02
Anticipated expiration: 1968-01-02

Description

Jan. 2, 1951 A E REIMERS 2,536,767

CAST-METAL EILEc'TRIcALLY-HEATED DEVICE AND RESISTANCE ELEMENTS THEREFOR Filed Oct. 16, 1946 2 Sheets-Sheet l 10 INVENTOR.

AL FRED E. BE/MEES Jan. 2, 1951 A E. REIMERS 2,536,767

CAST-METAL EILECTRICALLY-HEATED DEVICE AND RESISTANCE ELEMENTS THEREFOR 7 Filed Oct. 16, 1946 2 Sheets-Sheet 2 ZNVENTOR. ALFRED E. EE/MEES Patented Jan. 2, 1951 UNITED PATENT OFFICE HEEEFQBT Alfred It, Iteiniers, Harrington Park, N. J. n p i no o t a r 16, 1946, SerialNo. 703,600 5 Qlai ns. (Cl. 219:25)

This invention relates toimprovements in cast-. metal electrically-heated devices and resistance elements therefor.

Embedding electric heating resistors has long been found a reliable means of. transmitting the developed heat to the working surfaces of the devices they are required to. heat. Certain factors, however, limit the effectiveness of suchem: bedding and embedded resistors. For example, where efiicient design and moderate to heavy duty isrequired, the known electrical-insulating and heat-conducting materials are restricted to finely: divided or granular materials that are hard or refractory, friable and uncohesive though compactable, such as electrically-fused alumina, magnesium oxide, and zirconia. These materials possess relatively high heat conductivityand high electrical insulation at elevated tempera tures.

This embedding material even when bonded by clays and fired to cause. vitrification the-recipessesses little structural strength and heretofore cast-metal electrical heating devices, and par. ticularly cast metal sadeiron s hav in 0ider to permit handling thereof, reinforced; such structural strength by using metallic containers therefor before casting the material in a castmetal shell, or have compressedthe mass of embedding material before such cast g.

For the purpose of electricallyconnecting ape like were used adjacent to the connection with the element terminal and hetviieen the element terminals and the supporting bracketon the one hand and between the appliance terminals and the supporting bracket on the otherhand. construction and the assemblyand connection of these parts required considerable material and also required considerable manual labor to be performed after the casting-in of, the element was completed.

In the form of element referred to stand handling and the molding operation, ter- 'minals connected to the resistors and passing through a fragile layer of compressed embedding. material similarly comprised flexible leadwires or strips which inturn extended to and through a heavy metallic supporting bracket for the. appliance and/or thermostat terminal. Insulating washers Were used adjacent to the connection with the element terminals and between the element terminals and the supporting bracket on the one hand and between the appliance terminals and the supporting bracket on the other hand. This construction similarly required the use of considerable material and considerable manual labor had to be performed after the casting-in of the element was completed.

One of the objects of this invention is, in devices of the character specified, to avoid the above-mentioned connections, flexible lead-wires and independent metallic supporting brackets and to provide in a cast-metal electrical heating device, such as sad-irons, element terminals adapted for connection to appliance terminals and/or thermostat terminals that will be rigid and have. sufiicient structural strength to serve as a support for the appliance and/or thermostat terminals, and to enable a satisfactory screw and bolt electrical connection with the appliance and/or thermostat terminals to be made.

Another object of my invention is to reinforce such inherently rigid and structurally strong element terminal members by mounting the same in blocks or bosses of insulating material having inherent structural strength and rigidity that are in turn held rigidly in place by being cast into the metallic shell, thus producing a cast-in mounting that will embody such structural strength and rigidity as to be capable of serving as an efiicient supporting or mounting structure for appliance and/or thermostat terminals as well as serving as insulated element terminals.

Another object of my invention is to produce amounting for appliance and/or thermostat terminals which greatly simplifies prior-art constructions, while providing proper insulation from the metal shell of the element and enablingspeedy screw and bolt connection to the applianceand/or thermostat terminals, and also even n th when ssemb a a nl tion ofinsulation washers, lead members and heavy metallic brackets and the labor incident a ep l gatie th r Another object of my invention is to provide a construction in which the holding power of con tracting cast-metal of the shell of an electricallyheated device is utilized to produce a strongly held cast-in setting or base for a rigid block of insulating material that in turn provides 'a Fig. 1 is a view in plan of the base of an iron embodying my invention;

Fig. 2 is a view in side elevation of the base shown in Fig. 1 with the upper casing illustrated in broken lines;

Fig. 3 is a View in end elevation of the base shown in Figsrl and 2 with the appliance terminals connected to wires;

Fig. 4 is a section on the line 44 of Fig. 2

I looking in the direction of the arrows;

--- Fig. 5 is .a section on the line 55 of Fig. 2

looking in the direction of the arrows;

strong and rigid mounting for an element terminal that may be employed as a post for attachment by bolts of appliance terminals so as to avoid the use of subsequent installation of brackets and other assembly features heretofore necessary for mounting such appliance terminals. Another object of my invention is to produce an element for cast-metal electrically-heated devices provided with element-terminal members having inherent structural strength and'a rigidly-integrated electrical connection within the element to a resistor in combination with an inherently rigid mounting portion projecting outwardly therefrom and reinforced by an inherently-rigid block of insulating material and adapted when cast in to form a simple insulated mounting means for both supporting and electrically-connecting appliance and/or thermostat terminals.

Another object of my invention is to produce a resistance element composed of the uncohesive Fig. 6 is a horizontal cross-section of the com pressed element before casting in;

-Fig. -7 is a section on the line 'i-l of Fig. 6 looking in the direction of the arrows;

Fig. 8 is a cross-sectional View of a die for compressing the electrical resistance heating element with its embedded. resistance coil as shown in Figs. 4 to 6 inclusive;

'Fig. 9 is a view in side elevation of my resistance element removed from the iron; and 1 Fig. 10 is a fragmentary enlarged section substantially 0n the line 1-l of Fig. 6 looking in the direction of the arrows showing the shell of castmetal contracted around my metallic terminal members andsolid blocks of insulation.

i Referring now to these drawings, which illuski trate aapreferred embodiment of my invention,

embedding material hereinabove referred to by compressing same in a die, connecting such terminal-insulating and supporting block or blocks of a solid and rigid insulation material having structural strength and preferably partly embedding such blocks below the surface of said compressed embedding material to partly project thereabove, and then reinforcing said connection by vitrifying the embedding material around said rigid block or blocks.

Another object of my invention is to further reinforce the mounting of the element terminal members by providing a vitrified frit in the interstices between said terminal members and the terminal-mounting aperture in said block or blocks of solid insulation, and thus to produce an element of such inherent strength and rigidity as to enable casting-in thereof.

Still another object of my invention is to cast metal around the surface of an element prepared as specified and around the edges of the projecting portion of said inherently-strong block or blocks of insulation and to produce in the castmetal shell 2. seat or seats adapted to lock said blocks of insulating material and the metal terminal parts together, and thus to provide a strong and rigid cast-in mounting for the appliance and thermostat terminals.

With these and other objects in view, the invention comprises the combination of members and arrangement of parts so combined as to 09- I act and cooperate with each other in the performance of the functions and the accomplishment of the results herein contemplated, and comprises in one of its adaptations the species'or preferred form illustrated in the accompany n drawings, in which:

lQ-indicates an electrical heated cast-in sad-iron base, comprising a cast-in electrical heating resistance element H composed of a resistor-coil 12 and a-compressed mass ofelectrical insulating and heat conducting material embedding said resistor coil l2. In accordanc with this in- -'v'e'ntion,-I have'produced' a greatly simplified terminal mounting device both for the appliance terminals and for the thermostat terminals. By said improved and novel mounting I have been enabled in devices of the character specified, such as sad-iron bases, to procure the advantages of said embedding material and of a secure and rigid mounting for the appliance terminals and/or thermostat terminals that will possess s'ufiicient 'structural'strength to serve as a firm support to permit ready and facile attachment of such terminals, and which will avoid and eliminate all subsequent assembly and the subsequent application of insulation washers, lead members and prior art heavy metallic brackets, together with the labor incident to and necessary for the mounting of such terminals.

In the preferred embodiment of my invention, the heating element 1! l is composed, as aforesaid, ofa resistor coil I2 embedded in a mass of electrical-insulating and heat-conducting material l 3"of the uncohesive type hereinabove referred to which is'compressed about the coil in a suitable die I4 toa degree that will enable subsequent handling thereof, and during the compressing of said element, I connect to the resistor "rigid and inherently strong metallic terminal member's" I5, each having a resistor-engaging and gripping lower base or shoe portion l5 embedded in the compressed material and each having a shank portion [5 projecting upwardly above the top fiat surface thereof. Each shank portion extends through and is embraced and reinforced by a solid block l6 of inherently strong' 'an'd rigid insulating material which is partially embedded inthe: surface of said element I f and, asshowngnasr its base or bottom portion bodyand top 'portions'extending above the. surface thereof. Each solid block I6 engages a terminal member I and holds the same in an initially rigid position within the said heating ele ment.

The said embedding material i3 of the element H, after the mounting therein of the resistor, terminal members and mounting blocks. hereinabove specified, is preferably subjected to vitrification. Such vitrification more securely locks within the element the said block of insulating material. Each block It is preferably composed of porcelain, lava or similar independently-vitrified material having a high degree of structural strength, and, in the embodiment shown, each of these insulating blocks has a relatively narrow centrally disposed slot I! through which the shank portion of the terminal member H5 is extended. The terminal member I5 is composed of a rigid piece of stainless steel or other suitable metal and its shank portion l5 fits this slot H, and in the preferred embodiment (if my invention, the joint between the walls of said slot in the block [6 and the shank 45 has coated, painted or has spread about the said slot a vitrifiable flux or frit so that upon vitrification of the element and said flux or frit, the metallic terminal shank portion will be more securely and rigidly locked into the block 15 of solid and inherently-strong insulating material, and said block will be more securely and rigidly locked to the element l l.

Afte such vitrification of the compressed embedding material of the element ll, the heating element is then cast into the cast-metal shell or base member I0 shown in Figs. 1 to 7, while the upper surface of the block or blocks it of solid and inherently strong insulating material and the terminal shanks extending therethrough are properly shielded to avoid the deposit of cast metal thereon. Such casting in may be accomplished in a suitable permanent mold or by diecasting, if desired. Upon cooling, the cast-metal shell lil of the base membe it contracts about the edges of such insulating block [6 while the upper surface thereof is kept free of such cast metal, and a seat is thus provided in the cas metal shell which, in the casting-in operation, firmly anchors said block it securely in place within the said shell of cast-metal, which, in the accompanying drawings, forms the outer metallic portion of the sad-iron base member id, as shown in Figs. 1 to 7 inclusive. Each of said blocks l6 of insulation. in turn firmly supports a terminal member 15 securely in place and insulates said terminal member ts from said shell Ill I thus provide an electrical heated device, such as a sad-iron, having a cast-in electrical resistance element of the fragile embedding material referred to and embody in such device an inherently rigid metallic terminal member with the shank projecting above but securely and firmly anchored to but insulated from said shell.

The terminal members l5 are preferably composed of strong and rigid strips of metal having at its bottom an embedded foot portion provided with a looped lateral extension adapted to engage the end of a resistance coil and to form a securely locked terminal therefor, and each strip includes a vertical shank portion extending up wardly from said looped foot or base portion. Each of the vertical shank portions 55 is provided with a hole ll for connection by bolts H to an appliance terminal H3 or to a thermostat terminal 19, such as shown in Figs. 1 to 4 of the drawings.

It will be seen that in view of the mounting 6 and the initially cast-in vitrification thereof, together with the subsequent metallic casting-in operation, the us of prior art appliance-terminal brackets and involved thermostat connections is eliminated. In the preferred embodiment of my invention illustrated, the resistor coil or wire is interrupted intermediate its ends to provide terminals which are separate and additional from the members utilized in the production of the appliance terminals.

The use of additional element terminal members for connection to a thermostat is made possible and desirable because of the simplicity of the mounting of the said element terminal mem bers and consequently a highly simplified form of terminal connections both to the house current and to the thermostat is provided for and made possible.

Having described my invention, I claim:

1. An electrical heated device comprising a sad-iron base embodying, in combination, an electrical resistance heating element having a resistor member, a compressed mass of friable electrical insulating and heat-conducting material having substantially fiat surfaces and completely embedding said resistor between said surfaces, said base having a pair of rigid terminal members for connection thereto of appliance terminals, each of said terminal members having an embedded portion connected within said compressed mass with said resistor member and having another portion projecting outwardly above a surface thereof, a solid block of inherentlystrong and ri id insulating material connected by a liquid-tight joint and partly embedded in and partly projecting from said compressed mass of embedding material and surrounding each projecting terminal-portion, and a metallic shell cast in direct contact with the surface of said mass of embedding material and with a part of the edges of said block of insulating material to cause said block to be cast into said shell and to produce a tightly-contracted joint with such edges while leaving the upper surface thereof free of metal, whereby rigid and firm mountings of insulating material for said rigid elementterminals are produced.

2. An electrical heated device comprising a sad-iron base embodying, in combination, an electrical resistance heating element having a resistor comprising a continuous member, a compressed mass of friable electrical insulating and heat-conducting material having substantially fiat surfaces and completely embedding said resistor between said surfaces, said base having a pair of rigid terminal members for connection thereto of appliance terminals, and another pair of element terminal members for connection to thermostat terminals, each of said terminal members having an embedded portion connected within said compressed mass with said resistor member and having another portion projecting outwardly above a surface thereof, a solid block of inherently-strong and rigid insulating material connected by a liquid-tight joint and partly embedded in and partly projecting from said compressed mass of embedding material and surrounding each projecting terminal-portion, and a metallic shell cast in direct contact with the surface of said mass of embedding material and with a part of the edges of said block of insulating material to cause said block to be cast into said shell and to produce a tightly-contracted joint with such edges while leaving the upper surface thereof free of metal, whereby J rigid and firm mountings of insulating material for said rigid element-terminal members are produced.

3. An electrical heated device comprising a sad-iron base embodying, in combination, an electrical resistance heating element having a resistor member, a compressed mass of friable electrical insulating and heat-conducting material having substantially fiat surfaces and comhaving a liquid-tight connection therewith, and

a metallic shell cast in direct contact with the surface of said mass of embedding material and with a part of the edges of said block of insulating material to cause said block to be cast into said shell with the upper surface thereof free of metal, whereby a rigid and firm mounting of insulating material for said rigid element-terminal members are produced, said resisto member com rising a coiled Wire bent to provide a continuous outside leg and an inside leg having two pairs of terminals therein, one pair comprising terminals for a thermostat and the othe comprising element terminals for th appliance terminals.

4. An electrical heated device comprising a sad-iron base embodying, in combination, an

electrical resistance heating element having a resistor member, a compressed mass of friable electrical insulating and heat-conducting material having substantially fiat surfaces and completely embedding said resistor between said surfaces, said base having a pair of terminals for connection thereto of appliance terminals and another pair of element terminals for connection to thermostat terminals, each of said terminal members having an embedded portion connected within said compressed mass of said resistor member and having another portion projecting outwardly above a surface thereof, a block of solid and rigid insulating material surrounding said projecting portion, partly embedded in said compressed mass of embedding material and having a liquid-tight connection therewith, and

a metallic shell cast in direct contact with the surface of said mass of embedding material and with a part of the edges of said block of insulating material to cause said block to be cast into said shell with the upper surface thereof free of metal, whereby rigid and firm mountings of insulating material for said rigid element-terminal members are produced, said embedded terminal portion comprising a shoe extending in alignment with the axis of the resistor and said projecting terminal portion comprising a rigid strip extending at right angles to said shoe.

5. An electrical heated device comprising a sadiron base embodying in combination, a resistor member comprising a resistor coil, a compressed and vitrified mass of friable electricalinsulating and heat-conducting embedding material having substantially fiat surfaces and completely embedding said resistor between said surfaces, rigid metallic terminal members, each having an embedded portion connected to said resistor member within said compressed and vitrified mass and having another portion projecting outwardly therefrom, a solid and rigid block of insulating material surrounding said projecting portion and partly embedded in and having a liquid-tight vitrified bond to said compressed mass of embedding material, said mounting block of insulating material having a vitrified frit inserted between the walls of its slot and the strip of metal passing therethrough to tighten the connection therebetween, and a metallic shell cast in direct contact with the surface of said mass of embedding material and with theprojecting edges of said terminal insulating block to cause said block to be cast into said shell and to produce a tightly-contracted joint with such edges while leaving the upper surface thereof free of metal, whereby rigid and firm mountings of insulating material for said rigid element-terminal members are produced.

ALFRED E. REIMERS.

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

UNITED STATES PATENTS Jepson Mar. 24, 1942