US2472144A - Electric heater for softening thermoplastics - Google Patents

Description

June'7, 1949. J. v. CALHOUN ELECTRIC HEATER FOR SOFTENING THERMOPLASTICS a Sheets-Sheet 1 Filed July 8, 1947 IINF I H H I I I \l l l f l f nhn JMH h H u 5 B 5 Wm H 5 2 my O 1 9. 4 I, 2 M I: 7 I a 3 ||l| JUHN v. EALHUL/N IN VEN TOR.

ATTORNEY June 7, 1949. J. v. CALHOUN ELECTRIC HEATER FOR SOFTENING THERMOPLASTICS Filed July 8, 1947 3 Sheets-Sheet 2 JUHN v. EALHUL/N INVENTOR.

ATTORNEY J. v. CALHOUN ELECTRIC HEATER FOR SOFTENING THERMOPLASTICS June 7, 1949.

3 Shets-Sheet 3 7 Filed July 8, 1947 JUHN v. L'ALHUL/N INVENTOR.

.iIL rxllllL ATTORNEY Patented June 7, 1949 UNITED-;; Es PAT E'NT or F 1c E;

ELECTRIU=HEA-TER FORSOFTENING THEBMOPLASTICS John. V. CalhoumrHaverford, 2a., assignor to Edwin Ii. Wie'gand'Company, Pittsburgh, Pa., a corporation ofPelinsylvania Applicatiomlulyfi; 1947,; SeriaIsN o. '7 59,557

2 Claims? (Cl-i 219-19) Myinvention relatesgto electric, heating and.

a principal object of my .inventiomislthe, provi. sion of an electric heater satisfactory for melting or softening viscous or other material in a container, thus to facilitate-removal ofthe material from the container.

In this application I have shown- :and- 'described, for purpose of illustration; oneembodiment which'my invention'may assume, and in the drawings accompanying this specification and. forming part of this applicationz Figure I isa'view of an electricheater.according, to my invention, partiallydnfront elevation andpartially in vertical section; I.

Figure 2 is. a top planviewofthe heatermf Figureil; I

Figures 3, 4, and 5','are transverse sectionsron the lines 33, 4'-'4, and 5-5; of Figure I'; and

Figure 6 is a circuit diagram showing one manner in which the heater may be connected.

The electric heater herein shown and described comprises two sheathed embedded-resistor electric heating elements II, herein shown as triangular in cross-section, having their active sections I2 disposed in recesses in the lower face of a base I3, having their terminal portions I4 rising through openings I5 provided in the base I3, and held in position by means of a face plate I6 overlying the lower face of the base I3 and herein shown as secured to the base I3 by means of a series of bolts II extending through alined apertures in the face plate I6 and base I3.

Rising from the base I3 is a frame herein shown as comprising two tubes I8 screw-threaded in the openings I5 in the base I3, Ts I9 screwthreaded to the upper ends of the tubes I8, nipples 20 screw-threaded into the side openings of the Ts I9, and a union 2I connecting the two nipples 20 and completing a cross-brace between the two sides of the frame, while welded or otherwise suitably secured to the upper ends of the Ts I9 is a sheet metal housing 22 containing a thermostatic switch 23 adjustable by means of a knob 24 positioned above the top of the casing 22.

With this construction the electric heating elements II are energized under control of the thermostatic switch 23 by means of conductors 25 extending from the heating element terminals 26 through the tubes I8 and Ts I9 into the interior of the casing 22 and connected to the thermostatic switch 23, and conductors 21 extending to the thermostatic switch 23 from a suitable source of electric power, and the thermostatic switch 23 is responsive to operating temperature by means of a thermostat bulb 2.8. car-1 ried by a cross-frame 36 clampedrto the-tubes I3 a'ndoperatively connected to the thermostatic switch-2 3. by means of a connecting tube indicated at 29.

To produce balanced heating of the faceplate I6, preferably the two elements II are. at-least approximately equal, and to avoid inductance on alternating current,preferably the conductors 2 1 are so. connected to. the thermostaticswitch 2.3; that. the two currentswithinreach. of theitubes I8 andTs i9 flow in opposite.direction for example, as indicated by the diagram-,Figureaii;--

In operation,.the heater is placed in position with the face plateAfi.restingontheviscous-or other. material to be heated or softened; the thermostatic switch isset forlthedesiredvteme perature, and thereupon the heater will progressively melt or soften the viscous or other material, whereby the material may be removed from the container, but avoiding any temperature that would injure the material, and particularly important in this respect is the location of the thermostat bulb 28 substantially above the base I3, whereby the operation of the device is responsive directly to the temperature of the softened or melted material.

After operation any material that may have entered the tubes I9 may flow out through openings 29, while for convenience in handling preferably the heater is provided with handle means herein shown as comprising a plate 3| embracing the tubes 58 immediately below the Ts I9, a lower channel 32 extending transversely below the plate 3!, an upper channel 33 extending transversely above the top of the housing 22, connecting bolts 34 extending between the lower channel 32 and the upper channel 33, and an eye-bolt 35 secured to the upper channel 33.

As will be understood, the heater is made relatively heavy, whereby the apparatus will come into close contact with the viscous or other material and further will descend into the material as rapidly as the melting or softening is accomplished, and to facilitate the latter function preferably the base I3 and face plate I6 are provided with a plurality of apertures 31, as shown.

From the foregoing it will be apparent that the embodiment of my invention herein shown and described accomplishes the object specifically stated. Further it will be apparent that the said embodiment also accomplishes various other desirable objects and embodies various desirable advantages. On the other hand, obviously various changes and modifications may be made, and

various other embodiments may be substituted, within the spirit of my invention, and retaining some or all of the advantages and accomplishments of the present embodiment, and accordingly it will be understood that the present disclosure is illustrative only, and that my invention is not limited thereto.

Whereupon I claim:

1. An electric heater particularly for melting or softening a body of material within a .container to facilitate removal of the material from the container, comprising a platen adapted to be imposed on the body of material, metalsheathed electric heating means carried by said platen constructed and arranged to heat said platen to cause said platen to impart heat to said material to melt or soften said material, structural means comprising a superstructure disposed a substantial distance above said platen and duct means rising from said platen and connecting said platen and said superstructure, electric conductors for supplying electric energy to said heating means, connected to said heating means and extending through said duct means, and thermostatic switch means responsive to the temperature of said platen to control the supply of electric energy to said heating means to avoid increase in temperature of said platen above approximately a set value, comprising switch means connected in circuit with said heating means and mounted on said structural means at a substantial distance above said platen to avoid immersion of said swtich means in the material upon sinking of said heater upon melting or softening of the material.

2. An electric heater comprising a platen adapted to be imposed on a body of material, a

4 pair of electric heating elements carried by said platen constructed and arranged to heat said platen to cause said platen to impart heat to said material to melt or soften said material, a superstructure disposed above said platen and comprising a pair of ducts rising from said platen and to which said platen is connected, electric conductors for supplying electric energy to said heating elements extending through said duets with the two conductors for each of said heating elements extending one through one of said ducts and the other through the other of said ducts and the two conductors in each of said ducts connected one to one side of the supply and the other to the other side thereby to reduce or avoid induction of current in said ducts when the heater is operated on alternating current, and thermostatic switch means responsive to the temperature of said platen .-to control the supply of electric energy to said heating means to avoid increase in temperature of said platen above approximately a set value.

JOHN V. CALHOUN.

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

UNITED STATES PATENTS Number Name Date 1,070,966 Kicklighter Aug. 19, 1913 1,226,350 Mark et al. May 15, 1917 1,756,444 Brockdorfi Apr. 29, 1930 2,148,407 Pierson Feb. 21, 1939 2,162,287 Smith June 13, 1939 2,176,656 Caputo Oct. 17, 1939 2,366,318 Vecchio Jan. 2, 1945

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