US1673567A - Electrically-heated tempering bath - Google Patents

Description

June l2. 1928.

- L. P. HYNEs ELECTRICALLY HEATED TEMPERING BATH Filed Aug. 6, 1926' lllllllllllllllll |01 lllll IIIIII G ,..ll Llllllllfllll Smvemtoz Le: P. HYNES SMM/mut Patented June 12, 1928.

UNITED f STATES l 1,673,567 PATENT OFFICE.

LEE P. AHYNES, F ALBANY,` NEW YORK, ASSIGNOR TO HYNES & COX ELECTRIC COR- PORATION, OF ALBANY, NEW YORK, AICORPQRATION OF NEW YORK.

ELECTRICALLY-HEATED TEMPERING BATH.

Application filed August 6, 1926. Serial No. 127,645.

For a detailed description of the present form of my invention, reference may be had [to the following specification and to the accompanying drawingsv forming apart thereof, wherein Fig. l is a longitudinal section of my device on the line 11v of Fig. 2;

Fig. 2 is a plan view with the cover removed;

Fig. 3 is a diametric section of the heater with the coil in elevation taken on the lines 3 3 of Fig. 4;

Fig. 4 is a plan view of Fig. 3 with the lcover removed.

My invention relates fundamentally to a method of heating electrically a liquid, such as the oil bath used for the tempering and heat treatment of many forms of metallic articles, wherein it is desired to maintain the y oil at a given temperature and in a clean Y condition. Heretofre it has been the practice to heat the oil electrically by placing i-n the body of oil an ordinary heater-coil suitably insulated and protected. The defect of this method is that for a considerable body of oil ahigh temperaturelin the heater-coil is employed, the surface area of the coill being relatively small and intensely hot;

. hence the oil will often carbonize on the surface of the heater and .in time cause the heater to burn out 'because of inadequate radiation, while the `oil becomes blackened and damaged by overheating. 'Also the oil "nearthe heater' is much hotter than that 35V farther away because the convection currents `f in the oil are very slow. Forsuch operations as the drawing of steel tempered tools'` uniformity of temperature in all parts of the oil bath is essential." 'Yet such uniformity of 40 temperature is not 'attainable in said prior arrangement, not only because of the unequal,l

,` distance of different parts of the oil from the electric heater," but lalso', because of the local chilling of the oil by the cold steel when rstfimmersed. "Nor is it possible to elimi!r nate this spotty heating by mechanically stirring thebody of oil, as is also attempted in the prior' arty because of the imperfect convection of heat by the oil. I have suc- .59 cessfully overcome these troubles yby the method of constantly drawing olf 'the oily c from the bath,forcing it in a stream through a coiled pipe which is electrically heated and then returning it to the bath. Preferably 551th@ ai is separate frein the' man fsuA that ne part ofthe oil will receive extra heat by .Contact with the outside surface of the coil 1n distinction from the normal heat which every part of the oil receives from the interior surface of the coil in it journey therethrough. Moreover, the forced flow through the coiled pipe, which is a pipe of circular cross section, produces a swirling action of the oil that keeps all parts thereof constantl Y and thoroughly intermingled. There y uniformity of temperature is promoted by the mutual convection of the inter l mingled parts, as wellas by their uniform exposure to the` heating agency. I have also devised other features that will be described hereinafter. f

Referring to the drawing, A represents a tank which, lin this case, is rectangular in form and provided with double walls that enclose between them the heat-insulating material B. A longitudinal L-shaped parti- Vtion() divides the interior space into two compartments of which the larger one, of L-shaped contour, may be termed the inflow compartment and the smaller one, of plain rectangular shape, the outflow compartment. Near the bottom'of the latter is a horizontal screen D; while in the former, also near the bottom is a Slow-moving conveyor 'belt E` which is kept in constant mot-ion by any suitable external -motive power, as is indicated by the crank-handle F. The oil enters by the upright vinflow pipe G which passes downV into the inflow compartment to a header G2 from which two branch pipes g,

g extends out horizontally underneath the upper course'o'f the conveyor beltl E. y The header G2 and the branch pipes g, g, which constitute a distributor for the incoming oil, are perforated with holes at intervals throughwhich thevoil enters the inflow compartment inV distributed jets. These jets are vmorey numerous at and near the header be cause rit is at that end of the compartment that the `cold articles to be treated are introduced. For example, the articles may be placed in a wire basket H, shownin Fig. l, and lowered into the oil, through an uplifted lid I on the top of the tank, and there placed on the left hand end of the conveyor belt. The ybelt carries them slowly through the. oil to the right-hand end ofthe compartment, where the basket with its Vcphtents isv lifted out through anwoverlylng cover-opening having a li. il.

The basket f from. 'it any4 foreign matter.

an inch indepth, througli'whi'ch"the oil from vthe inflow compartment overflows into the outflow compartment, theremtalling down lon `the' aforesaid screen D which removes After passing through screen D to the bottomV of the com- .partmenathe oil is sucked up the outow pipe-K, through the agency ofpump VP'and,V delivered to the electric. heater.

The vertical tube T- in the inflow compartment is openf'at both ends Vfor thereception of a thermometer equipped to serve vas a thermostat. v-

,-fThe heater-is lshown inflfigs. Sande.y `It hasa cylindrical casing, with double walls enclosingheatinsulation B2, and areniova- {.b'le Ivcover O. Within this casing acentral metal frame M,c`arries` on its outer4 periphery a series of vertical heater elements R, lt, such, for example, as-are shownzin my f Patent-No.A 1,549,773, grantedAugust 18 1925. Surrounding-'theseand inside, the ,an-

f nularspace within the casing wall is arpipecoil, L through which the oil: is circulated by pump As is `indicated by dottedlines,VY the fintake of rthe ypump is connected with the outflow pipe of the oil-tank, `while the inflow pipe of the. tank draws from thel outflow terminal of. theLcoil M. The

` coil beinglocated inthe annulajrspace between-the heater elements R and thecasing ";wall'will-b e subjected throughoutits `entire helical length to Vthefradially Vradiated heat,`

ot any desiredintensizy,` said heat being ydis- *tribu'ted by thev heater-:over the entireannuf larspace, but the-foil willnot become carbonized because-,of its rapi'dflow in4 the pipe,

wh'i-lfethe heating r effect .of the heater ele-i fmentswill be v.limited by afthermostatrin the boXfjSf at ,the voutflow "end of theJ Vpipecoil where it is-subjected to the temperature ofrfthe outgoing oil. ,An linstrument-box Q,

n on the outsidefwal-l Yofthe casing contains' the electrical :control-switches;meters` and connection-terminals.- lI? have not' shown'y herein-the thermostat and the-,electrical details, nor the driving motor -for' the` pump, p.

sincek these may be ofcany suitable known construction Ijha-ve, however, shown 1n av ,separateapplication for kpatent al desirable system of electrical control Vforthis Oiltank -andfo'ther ta-nk'sfof Aa similar' type). I call particular attention tothe fact that the heating-ofthe oil -is 'carried on outside of andV independentlyof the body` of oilv :'ln'ather'trank.` Thusthe(utilization-ofthe heated oil in the vtempering or treatment of the metal articles fis notfafectedby the changesand variationsin temperaturel incident to thel opera.-

.pering liquid,A a:

tion, of securing and maintaining the oil temperature and keeping it `constant and' uniform. vThe latter operation is a separate Y and independent' one7 carried'onby itsown peculiaruneans fin a waytoadequately prepare the oil for its subsequent tempering or analogous function in the bath.

llifhilel am claiming herein the above described apparatus and method for heat-- ing ol,vi,t isto be regarded as-only a specific T embodiment otga more (fundamental method ofheating; liquids, such 'as-"oils, Syrups, and

chemicalstliat-f are liable to damage bya` momenta'ryor'local excess of temperature.

Thus it is diicult, if not impossiblafto avoid in ordinary vflainefheaters',but can be avoided .witlrcertai-ntyby 'my method, while,"fin' addition, the whole body of liquid israised to its desired maximum temperature at the maximum' Vrate-fbecaus'e the heating is applied vf to succeeding' quota'sv'of the masswithin a r region that is heated uniformly' throughout by'radiated'electrical heat." The volume of ythe quota in a given time .is dependent-,on the controlledvelocity of ljlovt'f.l`v For x'illus-"9"- tration, my method hasbeen adopted 'by the'De Laval Separator Company tof/preheat transformer oilfbefore clarifying vit by `centrffugal separators. Suchfoil' is 'susceptible tocarbonization which it is :vitally important to. avoid because -it` impairs Vits jelec- .trica-l insulating `.qu`ality. v'In that operation the tcriticaly ratio between vthe three 'iac'tors of (heat energy, unity SuraCearea, and unit volumepe'rztimeunit, is foundto be 1000 gallons of oil per hour, 'al lgiea'ter coil of'one and one-.quarter incl-1 outside'diameter and nine lwatts' per square inch ofheatiiig surface.

i on

like manner-'the critical conditions ttor y i any similaliquid'f maybe determinedf and mai'ntai'ned;k witli-"speed and certainty. fThe `the .heating eliiect can beideterminedwith accuracy andl the'heating effect canbecontrolled with equalf` accuracy. 'Moreover, the perfect vminglingcreates. a mass vof uniform temperature under/certain and exactvcontrol.

l liVhatI claim "a's'hew 2 and desire to lSecure by'Letters'Batent is:v `7

l. lA'fterriper'ing .appa-ratus for the treatment of ,metallic articles 'comp risingv a'heatinsulated 'Vreceptacle for; containinga -ternsec'ond j heatinsulated receptacle, a lliquid, heatingv coily Y within the second receptacle, means also "within the last mentioned `receptacle for heating said coil by radi'atedelectrical heat, and ,means forl circulating vsaid tempering 'liquidithrough said 'coiland' also through the first mentioned receptacle consecutivelyso astio preventaJ- substantial drop in .temp eratureVy` "of j 'said liquid f2?, tempering apparatus 'forithe treatment of metallic articles comprising Ya heat- Vinst'ilateil receptacle liavinganv 'inflow' compartment 'a'ndaii" outflow "compartment,

uns p,

' volumeftliaftv is .at each ,moment subjected to y means by which liquid in the inflow compartment is caused to overflow into said outflow compartment, means within the inflow compartment for supporting the articles to be tempered, a heating coil, a conduit extending from the heating coil to the inflow compartment, a second conduit extending from the outflow compartment to said coil, and means for positively impelling said liquid.

3. A tempering apparatus for the treatment ofnietallic articles comprising a heatinsulated receptacle for containing a tempering liquid, a second heat-insulated receptacle, a liquid heating coil within the second receptacle, means also within the last mentioned receptacle for heating said coil, an endless conveyor so positioned in the first mentioned receptacle that it will be submerged by said tempering liquid, a supply conduit extending from said heating coil and having its discharge end located in the space enclosed by said conveyor, `means for supplying tempering liquid to said coil from the first mentioned receptacle, and means for positively impelling said liquid.

4. A tempering apparatus for the treatment of metallic articles comprising a heatinsulated receptacle provided with an inflow compartment and an outflow compartment divided by an overflow7 partition, an endless conveyor located in the inflow compartment so as to support the articles to be tempered, a heating coil, a conduit leading from said heating coil and discharging in the space enclosed by said conveyor, a second conduit leading from the outflow compartment to said heating coil, and means for positively impelling said liquid.

5. A tempering bath for metallic articles or a similiar liquid body comprising a heatinsulated receptacle having two separate compartments communicating respectively with the inflow and outflow pipes from an electrically heated container, and a screen in one compartment across the route of the heating medium leading to the outflow pipe from the bath.

6. A tempering bath for metallic articles or a similiar liquid body comprisin a heatinsulated receptacle, inflow and out ow pipes for said receptacle communicating with an electrically-heated container for the liquid, a screen interposed between said pipes so that the said medium will flow therethrough, and means for maintaining a circulation of. the liquid through the heater and the bath consecutively.

7. A liquid-heating apparatus comprising a receptacle for the liquid and a separate heater receptacle, means within the first mentioned receptacle for moving articles through said liquid, a pipe-coil in the heater-receptacle connected with said liquid receptacle, a series of distributed electric heating elements for distributing the heat over the external surface of the coil and means for maintaining a flow of the liquid through said coil.

Signed at State of New 1926.

Albany, county of Albany, York, this 2nd day of Aug.,

LEE P. HYNES.

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