US3731034A - Heating rollers with axial magnetic force reduction means - Google Patents

Abstract

In a heating roller of the class comprising a cup-shaped cylindrical roller having a closed bottom, a driving shaft for rotating the roller connected to the center of the bottom and extending coaxially through the cylindrical roller, a stationary bobbin supported within the cylindrical roller coaxially with the driving shaft, the bobbin having an inner flange facing to the bottom and an outer flange close to the open end of the cupshaped cylindrical roller, and an induction coil wound about the bobbin for inductively heating the cylindrical roller, there are provided a radially extending flange at the open end of the cupshaped cylindrical roller and a surrounding annular ring connected to the periphery of the outer flange to surround the radially extending flange.

Description

United States a t'ent 1191 Arita [s41 HEATING ROLLERS wmr AXIAL MAGNETIC FORCE REDUCTHON MEANS [76'] inventor: Koshei Arita, 10,23 2-ch0me, Minamimagone, Ohota-ku, Tokyo, Japan [22] Filed: 1 Mar. 23, 1972 [21] App]. No.: 237,249

[52] US. Cl ..2l9/10.49, 219/1061 [51] Int. Cl. ..H05b 5/08 [58] Field of Search..'...; ..219/10.49, 10.61,

[56] References Cited UNITED STATES: PATENTS 3,412,229 11/1968 Seagrave....- ..2l9/10.61 2,273,423 2 1942 Somes ..219/1049 [451 May 1, 1973 Primary Examiner-J. V. Truhe Assistant Examiner-B. A. Reynolds Att0rney-Char1es W. Helze'r 57] ABSTRACT In a heating roller of the class comprising a cupshaped cylindrical roller having a closed bottom, a driving shaft for rotating the roller connected to the center of the bottom and extending coaxially through the cylindrical roller, a stationary bobbin supported within the cylindrical roller coaxially with the driving shaft, the bobbin having an inner flange facing to the bottom and an outer flange close to the open end of the cup-shaped cylindrical roller, and an induction coil wound about the bobbin for inductively heating the cylindrical roller, there are provided a radially extending flange at the open end of the cup-shaped cylindrical roller and a surrounding annular ring connected to the periphery of the outer flange to surround the radially extending flange.

7 Claims, 4 Drawing Figures HEATING ROLLERS WITH AXIAL MAGNETIC FORCE REDUCTION MEANS BACKGROUND OF INVENTION 1. Field oflnvention This invention relates to an improved construction for a heating roller adapted to heat synthetic fibers or strings which are are required to be heat treated at a constant temperature.

2. Prior Art Problem As shown in FIG. 1, a conventional heating roller utilized for this purpose comprises a cup-shaped cylindrical roller 1 having one end (left hand end as viewed in FIG. 1) closed and provided with a driving shaft 2 connected to the center of the bottom. Although not shown in the drawing, the shaft 2 is supported by a bearing and connected to a source of drive. The inner surface of the cylindrical roller 1 is covered by a heat generating layer 3 of conductive material. A cylindrical bobbin 4 having an inner flange 4 and an outer flange 4 is provided to concentrically surround driving shaft 2. The outer diameter of inner flange 4 is made smaller than the inner diameter of the cylindrical roller 1 whereas the outer flange 4 has an outer diameter substantially equal to that of the cup-shaped cylindrical roller 1 and is positioned opposite the open end thereof with a small gap g therebetween. On the outside of the bobbin 4 are mounted a laminated magnetic core 5 and an induction coil 6 which is energized by a source of aland outer flange 4 are made ofmagnetic material so as to form a substantially closedmagnetic circuit.

When the induction coil 6 "is energized from the source of AC, magnetic flux' is induced to flow through the magnetic path indicated by dotted lines thereby heating the cylindrical roller by the eddy current loss and hysteresis loss produced therein, the heating being across the gap g between the opening of the cylindrical roller 1 and the outer flange 4 and the gap g; between the inner bottom surface of the cylindrical roller 1 and the inner flange 4, of the bobbin 4, thrust loads act ternating current (not shown). The cylindrical roller 1 upon the shaft 2 inthe directions shown by arrows a I and a Since these thrust loads operate cumulatively, the shaft will be biased by the resultant of these thrust loads to the right as viewed in FIG. 1.

Bm and 19m the flux densities at the gaps g, and g and no the permeability of air. The resultant F of these attractive forces, that is the thrust load acting upon shaft 2 in the direction of the arrows is expressed by the following equation.

F= F F l/2p.o) (S,Bm, S Bm [N] Accordingly, when the induction coil 6 is energized by a sine'wave alternating current, the thrust load-fluctuates sinusoidally and canresult in damaging the bearing of the shaft 2. Where thebearing is damaged heavily, the coil 6 also might be damaged.

SUMMARY or INvENTIoN It is an object of this invention to provide an improved heating roller which is free from the axial thrust described above.

Accordingly, to this invention there is provided a heating roller of the class comprising a cup-shaped cylindrical roller having a closed bottom, a driving shaft connected to the center of the bottom and extending coaxially through the cylindrical roller, a stationary bobbin contained in the cylindrical roller coaxially with the driving shaft, the bobbin having an inner flange facing the bottom and an outer flange close to the open end of the cup-shaped cylindrical roller, and an induction coil wound about the bobbin for inductively heating the cylindrical roller. The invention is characterized in that there are provided a radially extending flange at the open end of the cup-shaped cylindrical roller and a surrounding annular ring connected to the periphery of the outer flange and surrounding v the radially extending flange.

BRIEF DESCRIPTION or DRAWINGS DESCRIPTION OF THE PREFERRED r EMBODIMENT FIGS. 3 and 4 show one embodiment of the present invention in which portions corresponding to parts of the heated roller shown and described with relation to FIGS. 1 and 2 are designated by the same'reference characters. In this embodiment, the cylindrical roller 1 is provided with a radially extending flange 1 at its open end and the outerdiameter of the outer-flange 4 of the bobbin 4 is considerably larger thanthat of the flange 1,. A surrounding annular ring 7 having a crosssectional configuration of a letter L is secured to and extended as part of the outer end of flange 4 to surround the flange 1,. The axi al gaps between flanges 1 and 4 and 1, and 7 are represented by g and g,', respectively, while the axial gap between the bottom of the roller. 1 and the inner flange 4 of bobbin 4 is represented by g The flange 1 and annular ring 7 are also made of magnetic material to form a magnetic path indicated by dotted lines.

With this construction, the attractive forces F and F at the gaps g and g create thrust loads in the direction of arrow bjust in the same manner as in the construction shown in FIG. 1. However, the attractive force F 1 at gap 3 operates in the opposite direction as shown by arrow C. Thus the force F counteractsthe sum of the forces (F F These attractive forces are given by 1=( 1 1 /2I 2= 2 2 /2u 3=( 3 3 The relation F 1 F F can be readily satisfied by varying the cross-sectional areas 8,, S and S of the magnetic paths or the flux densities B B and B at the respective gaps g g and g;, by appropriate spacing of the gaps. For this purpose, g and g may have a greater spacing than g With the improved construction, since the flange 1 of the roller 1 is surrounded by the intumed L-shaped ring 7, the heated air inside the cylinder is retained therein thus improving the heat efficiency of the heating roller.

As above-described according to this invention there is provided an improved heating roller wherein the thrust acting upon the driving shaft can be eliminated or substantially reduced by simple means.

While the invention has been shown and described in terms of a preferred embodiment it will be clear that many changes and modifications may be made without departing from the true spirit and scope of the invention as defined in the appended claims.

What is claimed is: 1

1. In a heating roller of the class comprising a rotatable cup-shaped cylindrical roller having a closed bottom, a driving shaft connected to the center of the bottom and extending coaxially through said cup-shaped cylindrical roller for rotating said roller, a stationary bobbin supported within said cup-shaped cylindrical roller coaxially with said driving shaft with said roller being freely rotatable relative to said bobbin, said bobbin having an inner flange facing said bottom and an outer flange close tov the open end of said cup-shaped cylindrical roller, and an induction coil wound about said bobbin for producing magnetic lines of flux magnetically coupling'said bobbin and said roller through said flanges for inductively heating said cylindrical roller, the improvement which comprises, a radially extending flange secured to the open end of said cupshaped cylindrical roller and a surrounding annular ring connected to the periphery of the outer flange of said bobbin and surrounding said radially extending flange for producing counter-balancing magnetic forces acting between the roller and the bobbin.

2. A heating roller according to claim 1 wherein a short circuited conductive ring is provided on the cylindrical surface of said cup-shaped cylindrical roller to induce heating current.

3. A heating roller according to claim 1 wherein the air gap between the bottom of said cup-shaped cylindrical roller and said inner flange of said bobbin and the air gap between said radially extending flange of said cylindrical roller and the outer flange of said bobbin create axial magnetic forces acting in the same direction and the air gap between said surrounding annu'lar ring and said radially extending flange creates an axial magnetic force counteracting said first mentioned magnetic forces.

4. A heating roller according to claim 3 wherein at least the air gap between the radially extending flange of the cylindrical roller and the outer flange of the bob bin is greater than the air gap between the surrounding annular ring and the radially extending flange.

5. A heating roller according to claim 3 wherein a short circuited conductive ring is provided on the cylindrical surface of said cup-shaped cylindrical roller to induce heating current, the surrounding annular ring has a cross-sectional configuration of a letter L with the bottom of the L-shaped ringe opposing and acting against the bottom side of the radial y extending flange on said roller.

6. A heating roller according to claim 6 wherein at least the air gap between the radially extending flange of the cylindrical roller and the outer flange of the bobbin is greater than the air gap between the surrounding annular ring and the radially extending flange.

7. A heating roller according to claim 1 wherein the surrounding annular ring has a cross-sectional configuration of a letter L with the bottom of the L-shaped ring opposing and acting against the bottom said of the radially extending flange on said roller.

Claims (7)

1. In a heating roller of the class comprising a rotatable cupshaped cylindrical roller having a closed bottom, a driving shaft connected to the center of the bottom and extending coaxially through said cup-shaped cylindrical roller for rotating said roller, a stationary bobbin supported within said cup-shaped cylindrical roller coaxially with said driving shaft with said roller being freely rotatable relative to said bobbin, said bobbin having an inner flange facing said bottom and an outer flange close to the open end of said cup-shaped cylindrical roller, and an induction coil wound about said bobbin for producing magnetic lines of flux magnetically coupling said bobbin and said roller through said flanges for inductively heating said cylindrical roller, the improvement which comprises, a radially extending flange secured to the open end of said cupshaped cylindrical roller and a surrounding annular ring connected to the periphery of the outer flange of said bobbin and surrounding said radially extending flange for producing counterbalancing magnetic forces acting between the roller and the bobbin.

2. A heating roller according to claim 1 wherein a short circuited conductive ring is provided on the cylindrical surface of said cup-shaped cylindrical roller to induce heating current.

3. A heating roller according to claim 1 wherein the air gap between the bottom of said cup-shaped cylindrical roller and said inner flange of said bobbin and the air gap between said radially extending flange of said cylindrical roller and the outer flange of said bobbin create axial magnetic forces acting in the same direction and the air gap between said surrounding annular ring and said radially extending flange creates an axial magnetic force counteracting said first mentioned magnetic forces.

4. A heating roller according to claim 3 wherein at least the air gap between the radially extending flange of the cylindrical roller and the outer flange of the bobbin is greater than the air gap between the surrounding annular ring and the radially extending flange.

5. A heating roller according to claim 3 wherein a short circuited conductive ring is provided on the cylindrical surface of said cup-shaped cylindrical roller to induce heating current, the surrounding annular ring has a cross-sectional configuration of a letter L with the bottom of the L-shaped ringe opposing and acting against the bottom side of the radially extending flange on said roller.

6. A heating roller according to claim 6 wherein at least the air gap between the radially extending flange of the cylindrical roller and the outer flange of the bobbin is greater than the air gap between the surrounding annular ring and the radially exteNding flange.

7. A heating roller according to claim 1 wherein the surrounding annular ring has a cross-sectional configuration of a letter L with the bottom of the L-shaped ring opposing and acting against the bottom said of the radially extending flange on said roller.

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