Title:
Coreless induction heater and method of making same
United States Patent 2457179


Abstract:
The present invention relates to improvements in coreless induction heaters and method of making the same and more particularly to improvements in a coreless induction heater of the type disclosed in my Patent No. 2,176,103 dated October 17, 1939. An object of the present invention is the...



Inventors:
Bela, Ronay
Application Number:
US61715645A
Publication Date:
12/28/1948
Filing Date:
09/18/1945
Assignee:
Bela, Ronay
Primary Class:
Other Classes:
29/602.1, 219/659, 219/674, 228/155
International Classes:
H05B6/10
View Patent Images:
US Patent References:



Description:

The present invention relates to improvements in coreless induction heaters and method of making the same and more particularly to improvements in a coreless induction heater of the type disclosed in my Patent No. 2,176,103 dated October 17, 1939.

An object of the present invention is the provision of means enabling a ready assembly of the coreless induction heater and providing a strong and durable construction.

Another object is to provide an improved method of fabrication and assembly of the coreless induction heater coil or coil sections which requires a minimum of tooling and a minimum manufacturing cost.

A further object is the provision of a plurality of heater coil sections with means for readily connecting and disconnecting the sections.

A still further object is to provide means for varying the number and spacing of the turns or units of the coil in a coil section and for varying the pitch of the turns or units to control and regulate the application of heat to the article being heated, at different points along the length of the article.

Other objects and advantages of the invention will be made more apparent by the following description in connection with the accompanying drawings which are exemplary and in which: Fig. 1 is an end elevation of a coreless induction heater according to the present invention, applied to an object to be heated.

Fig. 2 is a plan view of the coreless induction heater.

Fig. 3 is a fragmentary sectional view of the structure substantially on line 3-3 of Fig. 2 and showing the connection between the tie rods of adjacent sections of the heating coil.

Fig. 4 is an elevation partly in section of the U-shaped coil unit or portion at one stage in its manufacture or fabrication according to the present invention.

Fig. 5 is an edge elevation of the assembly of Fig. 4.

Fig. 6 is an elevation partly in section of the completed U-shaped coil unit or member with connecting blade or strap assembled therewith.

Fig. 7 is an edge elevation of the U-shaped coil unit or portion which is slotted to receive an end of the connecting blade or strap.

Figs. 8, 9, and 10 are diagrams showing that the coil sections may be connected in series parallel as in Fig. 8, in parallel as in Fig. 9, and in direct series as are the end or outer sections in Fig. 10, depending on the requirements for heat distribution and on the number of transformers available.

Fig. 11 is a fragmentary plan view similar to Fig. 2 of a portion of the coil and apparatus of the present invention adjusted and arranged for controlled or regulated heating.

Referring to the drawings showing a coreless induction heater constructed in accordance with the invention, a coil or conductor unit of U-shape is shown in Figs. 6 and 1, which is designed to be assembled with a plurality of like U-shaped units in spaced parallel relation and with bent or offset connecting blades or straps I, as indicated in Fig. 2, and together forming a heating coil adapted to embrace an article to be heated, in the manner set forth in my Patent No. 2,176,103. One end of each blade or strap I is pivoted at one end of a Ushaped unit with the other end of the blade or strap received in the slotted opposite end of the next adjacent U-shaped unit, thus forming a coil or helix.

The individual U-shaped members or units of the coil in my said patent are disclosed as preferably constructed of metal tubing bent into US5 shaped and flattened to a total thickness of substantially three times that of the wall of the tubing, thus permitting the slotted ends of the Ushaped members or units to receive the ends of the straps or blades I in the manner of a knife switch blade.

The fabrication to form and flatten the Ushaped units in the manner described in my said patent requires considerable tooling which in turn makes for a substantial manufacturing cost. The present invention is designed to provide an effective assembly and method including novel features of construction and fabrication which involve a minimum of tooling and manufacturing cost and which is adjustable to provide for varying conditions and heating requirements.

According to the present invention, the individual U-shaped coil unit is formed by using a straight tube section 2 and two tube sections 3 and 4 intermediately bent or offset at approximately 20° from straight, and two 90° elbows 5 and 6, all desirably of metal such as soft copper.

The elbows may be standard, commercial, forged elbows and must be fully annealed before assembly. The tube sections desirably are brazed or soldered into the elbows as seen in Fig. 4, and the U-shaped unit thus assembled is then flattened throughout to make the total thickness of the ends of the flattened U-shaped unit substantially equal to three times the wall thickness of said ends as indicated in Fig. 7, with the elbows flattened proportionately. As is apparent from Fig. 6, the 900 elbows of Fig. 4 are spread to more than 90° in the process of flattening them and the bent tube sections 3 and 4 are somewhat straightened in the flattening process to about 150 from straight. As is also apparent from Figs. 1 and 6, the degree of bend of the flattened bent tube sections 3 and 4 of the flattened unit, is such as to substantially compensate for the greater than 90 degree elbows of the flattened unit, the end portions of said bent sections being substantially parallel in said U-shaped unit. The ends of the flattened U-shaped unit of Fig. 6, are then slotted as indicated and provided with the pivoted straps or blades I and the U-shaped units are then assembled into a group or groups in the manner indicated in Fig. 2.

As indicated in Figs. 2 and 3 the individual Ushaped units are grouped in sections held together by tie rods 7 provided with tubular insulating members 8 between the rods and the Ushaped conductor coil units or members. Insulating spacer washers 8 are provided between the adjacent U-shaped coil units or members.

The tie rod connections between the units are provided at a plurality of points on the units, preferably three, as shown. Openings 10 are provided in the U-shaped units for receiving the tie rods and tubular insulating members.

Centering or positioning adjusting screws II like those disolosed in my Patent 2,176,103, are provided threaded into extension members 12 provided on the ends of the terminal tie rods, and are designed to engage the article A to be heated.

According to the present invention the extension members 12 are formed integral with a nut or head 13 on the end of the tie rod. The nut or head 13 engages a washer 14 which in turn engages the end of the tubular insulating member 8.

The washer 14 is of greater diameter than that of the tubular insulating member 8 and greater than the diameter of the opening 10 in the U-shaped coil unit, so that an insulating spacer or spacers 9 may be interposed between the washer 14 and the coil unit.

The washers 14 are preferably of the same diameter as the insulating spacers 9 in order to securely retain the end insulating spacers 9 in place. The washers 14 are held to the ends of the tubular insulators 8 by enlargements at each end of the tie rods, in the form of heads or nuts on the rods.

In the embodiment shown in Figs. 2 and 3, the enlargements on the ends of the rods of adjacent groups or sections are formed as pin and socket connections to permit ready centering and assembling of the groups or sections of heating coil as an interconnected induction heating assembly. A socket nut or head 15 may desirably be provided on the end of one tie rod to receive a nut or head 16 providing a pin or projection on the adjacent tie rod.

The coil sections or groups of U-shaped units may comprise any suitable number of U-shaped units, by way of example, four units being shown as comprising the end groups or sections and six units comprising the center section.

Fig. 2 and the diagrams of Figs. 8,: 9, 10 indicate that the coil sections or groups of U-shaped units may be connected in series as indicated in Fig. 2, or in series parallel as indicated in Figs. 8 and 10, Or in parallel as indicated in Fig. 9, depending upon the requirementsrfor heat distribution and on the number of transformers available. Fig. 8 indicates a four section heater. In Figs. 2, 9, and 10, three section heaters are indicated.

For example, the connection indicated in Fig.

10 is particularly applicable to a cylindrical object such as the journal portion of a heavy shaft.

For such use the center coil section or group which contains a sufficient number of U-shaped units or turns to cover the entire length of the journal portion of the shaft, is desirably connected directly to a power source of suitable capacity. The two, shorter, outer coil sections or groups, each comprising a lesser number of Ushaped units or coil turns, are shown in Fig. 10 as being connected in series and energized by another power source desirably of smaller capacity.

The end or outer sections, thus connected in series, serve to prevent loss of heat into the adjacent portions of the object being heated, and therefore require only enough energy input to compensate for the heat loss through conduction through the portions of the object adjoining the ends of the portion desired to be heated by the center section.

If, in addition, it is desired to maintain a uniform temperature throughout the entire length of the heated portion of the object, such as a shaft journal, this is accomplished according to the present invention, by the provision of naro0 rower insulating spacers 9a between the U-shaped coil units at the end zones of a coil section, such as the central coil section or group, and the provision of wider insulating spacers 9b between the U-shaped coil units at the central zone of the coil section or group. This is indicated in Fig. 11, including the provision of connecting blades la of reduced angular offset at the end zones of the coil section and connecting blades lb of increased bend or angular offset at the central zone of the coil section. Thus there is provided a decrease of the pitch of the U turns or coils at the end zones of the coil section and an increase of the pitch at the central zone of the coil section to control or regulate the heating of or to apply a uniform heating temperature to the object within the particular coil section, the heat input being thereby increased at the end zones and decreased at the central zone of the coil section.

Preferably the connecting blades or straps are 60 adapted to be readily bent to provide variations in the angular offset thereof for this purpose.

By the provision, according to the invention of the insulating spacers of various widths and the U-shaped coil units having connecting blades or straps of various degrees of angular offset and adjustable by bending to change the angular offset, means are provided to regulate and control the application of heat in any zone or portion of any coil section or group of coil units, and thus to control the heat imparted to any part of the portion of an object within the coil section.

Sufficient length of tie rod is provided in each group or section to provide room for varying the 6b spacing between the coil units by the removal or insertion of insulating spacers 9 at the ends of the tie rods and tubular insulating members and the removal and insertion of spacers 9 of various widths between the units.

The temperature of each heated section can be regulated automatically by use of controlling devices (not shown) attached by thermocouples fastened to the sections.

The electrical connections with the coil units or sections are diagrammatically illustrated in Fig. 2 and may be made in any suitable manner, such, for example, as is disclosed in my said Patent 2,176,103.

It will be understood that various changes in the construction and details of the apparatus and method illustrated and described herein may be made without departing from the spirit of the invention and it is not intended to limit the invention other than by the terms of the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is: 1. A coreless induction heater coil having Ushaped units secured together in mutually insulated relation with means extending between them to form the coil, each of said units consisting of a straight and two bent or offset tube sections connected by two elbows, said assembled unit being in a flattened condition and in substantially U-shape, the flattened tubing being of a thickness substantially three times its wall thickness, and said elbows being in a proportionately flattened condition and greater than 90 degrees, the degree of bend of the said bent sections of said flattened unit being about 15 degrees and such as to substantially compensate for the greater than 90 degree elbows, end portions of said bent sections being substantially parallel to each other in said U-shaped unit.

2. Steps in a method of making a coreless induction heater coil unit comprising connecting a straight and two bent tube members by inserting and brazing them into two 900 forged annealed elbows, flattening said assembled tubular unit to substantially three times the wall thickness of the tube members, and decreasing the angle of offset of the bent tube members, and flattening said elbows proportionately and increasing their angles to greater than 900, and thereby spreading the ends of said unit to substantially Ushape.

3. Steps in a method of making a coreless induction heater coil unit comprising connecting a straight and two bent tube members having an offset of substantially 20 degrees, by inserting and brazing them into two 900 forged annealed elbows, flattening said assembled tubular unit to substantially three times the wall thickness of the tube members, and thereby decreasing the angle of offset of the bent tube members to substantially 15 degrees, and flattening said elbows proportionately and increasing their angles to greater than 900 and thereby spreading the ends of said unit to substantially U-shape.

4. A coreless induction heater coil having Ushaped units secured together in mutually insulated relation with means extending between them to form the coil, each of said units consisting of a straight and two bent or offset tube sections connected by two elbows, said assembled unit being in a flattened condition and in substantially U-shape, and said elbows being in a proportionately flattened condition and greater than 90 degrees, the degree of bend of the said bent sections of said flattened unit being such as to substantially compensate for the greater than 90 degree elbows, end portions of said bent sections being substantially parallel to each other in said U-shaped unit.

5. Steps in a method of making a coreless induction heater coil unit comprising connecting a straight and two bent tube members by inserting and brazing them into two 90 degree forged annealed elbows, flattening said assembled tubular unit, and decreasing the angle of offset of the bent tube members, and flattening said elbows proportionately and increasing their angles to greater than 90 degrees, and thereby spreading the ends of said unit to substantially U-shape. 6. Steps in a method of making a coreless induction heater coil unit comprising connecting a straight and two bent tube members by inserting and brazing them into two 90 degree forged annealed elbows, flattening said assembled tubular 80 unit, and decreasing the angle of bend of the bent tube members and flattening said elbows proportionately and increasing their angles to greater than 90 degrees, and thereby spreading the ends of said unit to substantial parallelism 85 and providing substantially U-shape of said unit, the resultant angle of bend of said bent tube members and the resultant angle of said elbows substantially compensating each other and resulting in said parallelism.

BELA RONAY.

REFERENCES CITED The following references are of record in the file of this patent: UNITED STATES PATENTS Number 648,481 1,646,498 1,718,806 1,791,934 1,839,802 1,946,876 2,176,103 2,202,758 2,299,934 2,303,408 2,335,495 2,383,992 Name Date Berresford --------- May 1, 1900 Seede -------------_ Oct. 25, 1927 Witting --------- June 25, 1929 Northrup ---------- Feb. 10, 1931 Northrup --------- Jan. 5, 1932 Northrup ---__-- Feb. 13, 1934 Ronay ------------- Oct. 17, 1939 Denneen et al. ----. May 28, 1940 Sherman et al. ._____ Oct. 27, 1942 Soderholm -------- Dec. 1, 1942 Fink -----------_ Nov. 30, 1943 Sherman --------- Sept. 4, 1945