US2395196A - Electrical heating apparatus - Google Patents

Electrical heating apparatus Download PDF

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US2395196A
US2395196A US492817A US49281743A US2395196A US 2395196 A US2395196 A US 2395196A US 492817 A US492817 A US 492817A US 49281743 A US49281743 A US 49281743A US 2395196 A US2395196 A US 2395196A
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support
coil
bore
heating apparatus
secured
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US492817A
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Wesley M Roberds
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RCA Corp
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RCA Corp
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    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05BELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B6/00Heating by electric, magnetic or electromagnetic fields
    • H05B6/02Induction heating
    • H05B6/36Coil arrangements
    • H05B6/365Coil arrangements using supplementary conductive or ferromagnetic pieces

Definitions

  • This invention relates to electrical heatingl apparatus, and more particularly to inductive heating apparatus for rapidly heating the work to be treated.
  • the work to be scanned is of such small diameter at the surface to be treated that the use of an applicator ring or an inductor kof the type conventionally employed with radio frequency currents is not feasible, since coils of small diameter are diilicult to form out of hollow or tubular conductors,
  • the conventional applicator or inductor is not suitable because it cannot be formed satisfactorily on a sufciently small diameter.
  • the applicator or coupling coil proper is constituted by a split copper ring ymounted at y the end of a Bakelite or-other suitable non-conbore in the cylindrical guide so as to provide an.
  • the bore in the guide and the split rod are both suitably tapered adjacent their ends so as to insure spraying of the cooling Water against the inductor ring ask it leaves the device.
  • the novel features that I consider characteristic of my invention are set forth with particu-
  • the primary object of my present invention is to provide an improved coupling inductor which is free from the above mentioned disadvantage.
  • yit is an object of my present invention to provide an improved coupling inductor which is particularly suitable for use in bores of small diameter.
  • Another object of my present invention is to Y provide an improved ⁇ coupling inductor as aforesaid which can be readily manufactured by-machine methods and which. therefore, can be made with great accuracy.
  • Still another object of my present invention ls to provide an improved inductor as set forth larity vin the appended claims.
  • the invention itself howeven. both as to its organization and method of operation, as well as additional objects and advantages thereof, will best'y be understood from the following description of one embodiment thereof, lwhen read in connection with the accompanying drawing, inwhich:
  • Figure 1 is a central sectional vview of a heating unit formed in accordance with my present invention
  • Figure 2 is a front elevation thereof
  • Figure 3 is a sectional view taken on the line III--III of Figure 2.
  • tubular support I to one end of which is secured a split ring 3 of copper or the like, as by. means of cement 4 or other suitable adhesive.
  • the support I is formed with a bore 5 which, at
  • a split Copper rod constituted by the parts Iva .and 1b, the rod being concentric with the support I and the ring 3, but being of a smaller diameter than the bore 5 whereby to provide an annular space or passage 5a between the rod 1a, 1b and the wall of the bore 5,' as clearly seen from Figures l and 3.
  • the rod 1a, 'Ib is tapered similarly to the bore i, the tapered portions 1c thereof terminating at points short of that end of the support I to which the ring l is secured. Beyond the tapered portions 'Ic, each of the rod parts 1a, 'Ib' continues on a smaller diameter and, at the extreme end,
  • each of the parts 1a, Ib is bent at right angles to provide offset portions 9a and 3b, respectively, which extend radially of the applicator ring 3.
  • One of the offset terminal portions 3a is secured to one terminal of the applicator ring 3, and the other offset portion 9b is secured to the other terminal of the ring 3, as best seen in Figure 2.
  • each of the rod parts 1a, Ib extends longitudinally along the support I, whereas each offset portion 9a, 9b is disposed substantially ⁇ radially within the inductor 3.
  • a strip I I of mica or other suitable insulating material is inserted between the parts la and 1b.
  • a tubular conductor I3 which, together with a second tubular conductor I5 connected to the rod part 1a, constitutes a concentric line.
  • outer conductor I3 terminates in an enlarged, outwardly threaded portion I1 on which a threaded cap I9 is received.
  • between which a soft rubber washer 23 is confined serve to maintain the tubular conductors I3 and I5 in concentric relation.
  • the rod part 'Ib is connected to the outer conductor I3 by'a block of conducting material 25, which may be soldered thereto, and by a screw 21. Connection of the concentric line I3, I5 to a source of high frequency electrical energy 29, such as a vacuum tube oscillation generator operating at radio frequency, may be made through a coupling transformer 3
  • the support I For heating the wall of a bore 33 of the work 35, the support I is inserted into the bore 33 in engagement with the wall of the bore.
  • the applicator coil 3 is of somewhat smaller diameter than the outside diameter of the support I, wherefcre the support I acts as a guide for maintaining the ring 3 in concentric relation with the bore 33.
  • current in the inductor 3 induces heating current in the work which rapidly heats the wall of the bore 33 to the desired temperature. Scanning may be performed at whatever rate is found suitable.
  • a cooling fluid such as Water, may be forced l a taper which converges or tapers inwardly away from the support I.
  • the cooling fluid is sure to strike at least the tapered portion of the tube 3 after which it may or may not be deflected onto the Work for cooling thelatter, depending upon the angle of taper of the coll 3. With this arrangement, much more cooling fluid may be utilized than in conventional coils constructed of tubular conductors.
  • inductive heating apparatus the combination of a tubular support of insulating material, a coupling coil secured to one end of said support and adapted to be brought into inductive relation with the work to be heated, said support having a bore at least part of which tapers outwardly toward said coil, and a pair of conductive members within said bore secured to the terminals of said coil and adapted to connect said coil to a source of electrical energy, said members being formed at least in part on a taper similar to that of said bore but being spaced from said support whereby to provide a passage for the reception of cooling fluid, and said coil having a portion located in the path of movement of cooling fluid passed through said passage.
  • Heating apparatus i characterized in that the tapered portions of said members terminate at points short of that end of said support to which said coil is secured, said members continuing beyond said points on a smaller diameter.
  • Heating apparatus characterized in that said coil tapers inwardly away from said support.
  • Heating apparatus characterized in that said coil tapers inwardly away from said support, and characterized further in that the tapered portions of said members terminate at points short of that end of said support to which said coil is secured, said members continuing beyond said points on a smaller diameter, and the taper of said members being such as to direct the cooling fluid onto at least the tapered portion of said coil.
  • Heating apparatus wherein said coil is constituted by a single-tum, annular member, and wherein each of said conductive members includes a portion disposed substantially radially within said annular member.
  • Heating apparatus wherein said coil is constituted by a single-turn, annular member, and wherein each of said conductive members includes a main portion extending longitudinallyalong said support and an offset portion disposed substantially radially within said annular member, said offset portions being secured one to each of the terminals of said annular member.
  • inductive heating apparatus the combination of a tubular support of insulating material, acoupling coil secured to one end of said support and adapted to be brought into inductive relation with the work to be heated, a pair of conductive members Within said support each secured to a separate terminal of said coil, said members being spaced from said support whereby to provide a space therearound for the passage of cooling fluid, and a concentric line for external connection of said coil to a source of high frequency electrical energy, said line comprising inner and outer tubular conductors the outer one of which is secured to said support and is connected electrically to one of said conductive members and the inner one oi which is connected electrically to the other one oi said conductive members, one of said concentric line conductors having communication with said space whereby cooling fluid forced into said last mentioned conductor will also be forced through said space.

Description

w. M. RoBERDs ELECTRICAL HEATING APPARQTUS Filed June so, 194s mm J Y.
Feb. 19, 1946.
weslc M. E C@ Gttorncg Patented Feb. 19, 1946 ELECTRICAL HEATING APPARATUS wesley M. noberds, oomngswobd, N. J., sslgmr to Radio Corporation' of America, a corporation of Delaware Application June 30, 1943, Serial N0.' 492,817`
8 Claims.
This invention relates to electrical heatingl apparatus, and more particularly to inductive heating apparatus for rapidly heating the work to be treated.
The use of radio frequency electrical energy for rapidly heating various articles is now Well known. In heating metallicarticles, as for hardening the surfaces thereof, there is usually employed an inductor or coupling coil in the form of a tubular member 'through which cooling fluid is passed for cooling the applicator coil or inductor. In general, where the outside surface of an article is to -be heated, the coil is placed around the article, whereas if the inside surface is to be heated, as in the case of a Cylinder bore of an internal combustion engine, the applicator is placed within the bore. In any case, the work is scanned by the coupling coil by moving one relative to the other at an appropriate rate.
In many instances, the work to be scanned is of such small diameter at the surface to be treated that the use of an applicator ring or an inductor kof the type conventionally employed with radio frequency currents is not feasible, since coils of small diameter are diilicult to form out of hollow or tubular conductors, Thus, for ex ample, where the bore of a rifle is to be hardened by inductive heating at sufficiently high power from a source of radio frequency electrical energy, the conventional applicator or inductor is not suitable because it cannot be formed satisfactorily on a sufciently small diameter.
invention, the applicator or coupling coil proper is constituted by a split copper ring ymounted at y the end of a Bakelite or-other suitable non-conbore in the cylindrical guide so as to provide an.
annular spacev therebetween through which the cooling fluid may be passed, The bore in the guide and the split rod are both suitably tapered adjacent their ends so as to insure spraying of the cooling Water against the inductor ring ask it leaves the device.
The novel features that I consider characteristic of my invention are set forth with particu- The primary object of my present invention is to provide an improved coupling inductor which is free from the above mentioned disadvantage.
More particularly, yit is an object of my present invention to provide an improved coupling inductor which is particularly suitable for use in bores of small diameter.
Another object of my present invention is to Y provide an improved `coupling inductor as aforesaid which can be readily manufactured by-machine methods and which. therefore, can be made with great accuracy.
Still another object of my present invention ls to provide an improved inductor as set forth larity vin the appended claims. The invention itself, howeven. both as to its organization and method of operation, as well as additional objects and advantages thereof, will best'y be understood from the following description of one embodiment thereof, lwhen read in connection with the accompanying drawing, inwhich:
Figure 1 is a central sectional vview of a heating unit formed in accordance with my present invention,
Figure 2 is a front elevation thereof, and
Figure 3 is a sectional view taken on the line III--III of Figure 2.
Referring more particularly to the drawing,
wherein similar reference characters designate corresponding parts throughout, there is shown i a tubular support I to one end of which is secured a split ring 3 of copper or the like, as by. means of cement 4 or other suitable adhesive.
The support I is formed with a bore 5 which, at
above which can be readily cooled by a fluid k cient in use.
In accordance with one form of myspresent least in part, tapers outwardly as it approaches the applicator ring 3.
Within vthe bore of the support I is a split Copper rod constituted by the parts Iva .and 1b, the rod being concentric with the support I and the ring 3, but being of a smaller diameter than the bore 5 whereby to provide an annular space or passage 5a between the rod 1a, 1b and the wall of the bore 5,' as clearly seen from Figures l and 3. The rod 1a, 'Ib is tapered similarly to the bore i, the tapered portions 1c thereof terminating at points short of that end of the support I to which the ring l is secured. Beyond the tapered portions 'Ic, each of the rod parts 1a, 'Ib' continues on a smaller diameter and, at the extreme end,
each of the parts 1a, Ib is bent at right angles to provide offset portions 9a and 3b, respectively, which extend radially of the applicator ring 3. One of the offset terminal portions 3a is secured to one terminal of the applicator ring 3, and the other offset portion 9b is secured to the other terminal of the ring 3, as best seen in Figure 2.
Thus, the main portion of each of the rod parts 1a, Ib extends longitudinally along the support I, whereas each offset portion 9a, 9b is disposed substantially` radially within the inductor 3. A strip I I of mica or other suitable insulating material is inserted between the parts la and 1b.
For connecting the applicator ring to a source of radio frequency energy, there is connected to the support I by cement or the like I2 a tubular conductor I3 which, together with a second tubular conductor I5 connected to the rod part 1a, constitutes a concentric line. 'Ihe outer conductor I3 terminates in an enlarged, outwardly threaded portion I1 on which a threaded cap I9 is received. A pair of insulated bushings 2| between which a soft rubber washer 23 is confined serve to maintain the tubular conductors I3 and I5 in concentric relation. By threading the cap I9 onto the portion I1 tight against the bushings 2 I, the washer 23 is compressed to form a fluid tight connection between the conductors I3 and I5. The rod part 'Ib is connected to the outer conductor I3 by'a block of conducting material 25, which may be soldered thereto, and by a screw 21. Connection of the concentric line I3, I5 to a source of high frequency electrical energy 29, such as a vacuum tube oscillation generator operating at radio frequency, may be made through a coupling transformer 3| in well known manner.
For heating the wall of a bore 33 of the work 35, the support I is inserted into the bore 33 in engagement with the wall of the bore. The applicator coil 3 is of somewhat smaller diameter than the outside diameter of the support I, wherefcre the support I acts as a guide for maintaining the ring 3 in concentric relation with the bore 33. When power is applied and the device is moved along the bore 33, current in the inductor 3 induces heating current in the work which rapidly heats the wall of the bore 33 to the desired temperature. Scanning may be performed at whatever rate is found suitable. For cooling the applicator coil 3 and also the work (as for quenching) a cooling fluid, such as Water, may be forced l a taper which converges or tapers inwardly away from the support I. Thus, the cooling fluid is sure to strike at least the tapered portion of the tube 3 after which it may or may not be deflected onto the Work for cooling thelatter, depending upon the angle of taper of the coll 3. With this arrangement, much more cooling fluid may be utilized than in conventional coils constructed of tubular conductors.
From the foregoing description, it will be apparent that have provided an improved heatunit which is compact, simple in construction, highly efilcient in use. The various parts of the device can be readily machined and they are, therefore, much more uniform and accurate than the tube coil types of applicators. l'urthermore, by proper selection of the diameter of the supporting tube I and the applicator ring 3, bores of various sizes. can be treated with the present invention. Also, by merely selecting proper lengths of concentric line I3, I5, it is apparent that bores of various lengths may be adequately treated.
Although I have shown and described but one embodiment of my invention, it will, no doubt, be apparent to those skilled in the art that many other modifications thereof, as well as changes in the one described herein, are possible. I therefore desire that my invention shall not be limited except insofar as is made necessary by the prior art and by the spirit of the appended claims.
I claim as my invention:
l. In inductive heating apparatus, the combination of a tubular support of insulating material, a coupling coil secured to one end of said support and adapted to be brought into inductive relation with the work to be heated, said support having a bore at least part of which tapers outwardly toward said coil, and a pair of conductive members within said bore secured to the terminals of said coil and adapted to connect said coil to a source of electrical energy, said members being formed at least in part on a taper similar to that of said bore but being spaced from said support whereby to provide a passage for the reception of cooling fluid, and said coil having a portion located in the path of movement of cooling fluid passed through said passage.
2. Heating apparatus according to claim i characterized in that the tapered portions of said members terminate at points short of that end of said support to which said coil is secured, said members continuing beyond said points on a smaller diameter.
3. Heating apparatus according to claim 1 characterized in that said coil tapers inwardly away from said support.
4. Heating apparatus according to claim 1 characterized in that said coil tapers inwardly away from said support, and characterized further in that the tapered portions of said members terminate at points short of that end of said support to which said coil is secured, said members continuing beyond said points on a smaller diameter, and the taper of said members being such as to direct the cooling fluid onto at least the tapered portion of said coil.
5. Heating apparatus according to claim 1 wherein said coil is constituted by a single-tum, annular member, and wherein each of said conductive members includes a portion disposed substantially radially within said annular member.
6. Heating apparatus according to claim 1 wherein said coil is constituted by a single-turn, annular member, and wherein each of said conductive members includes a main portion extending longitudinallyalong said support and an offset portion disposed substantially radially within said annular member, said offset portions being secured one to each of the terminals of said annular member.
7. In inductive heating apparatus, the combination of a tubular support of insulating material, acoupling coil secured to one end of said support and adapted to be brought into inductive relation with the work to be heated, a pair of conductive members Within said support each secured to a separate terminal of said coil, said members being spaced from said support whereby to provide a space therearound for the passage of cooling fluid, and a concentric line for external connection of said coil to a source of high frequency electrical energy, said line comprising inner and outer tubular conductors the outer one of which is secured to said support and is connected electrically to one of said conductive members and the inner one oi which is connected electrically to the other one oi said conductive members, one of said concentric line conductors having communication with said space whereby cooling fluid forced into said last mentioned conductor will also be forced through said space.
8. Heating vapparatus according to claim 'l g wherein said inner conductor is the one which has communication with said space.
WESLEY M. ROBERDB.
US492817A 1943-06-30 1943-06-30 Electrical heating apparatus Expired - Lifetime US2395196A (en)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2665367A (en) * 1948-06-18 1954-01-05 Deutsche Edelstahlwerke Ag Inductor for the heat treatment of workpieces, especially crankshafts
US2759085A (en) * 1952-08-21 1956-08-14 Hartford Nat Bank & Trust Co Method of heating a workpiece by high-frequency currents
US3054074A (en) * 1953-02-04 1962-09-11 Bird Electronic Corp Termination device with removable center conductor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2665367A (en) * 1948-06-18 1954-01-05 Deutsche Edelstahlwerke Ag Inductor for the heat treatment of workpieces, especially crankshafts
US2759085A (en) * 1952-08-21 1956-08-14 Hartford Nat Bank & Trust Co Method of heating a workpiece by high-frequency currents
US3054074A (en) * 1953-02-04 1962-09-11 Bird Electronic Corp Termination device with removable center conductor

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