US3928909A - Method for producing cartridge heaters - Google Patents

Method for producing cartridge heaters Download PDF

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US3928909A
US3928909A US487958A US48795874A US3928909A US 3928909 A US3928909 A US 3928909A US 487958 A US487958 A US 487958A US 48795874 A US48795874 A US 48795874A US 3928909 A US3928909 A US 3928909A
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cover pipe
heating coil
section
cross
longer axis
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US487958A
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Isamu Saku
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KAWAIDENKISEISAKUSHO KK
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KAWAIDENKISEISAKUSHO KK
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B3/00—Ohmic-resistance heating
    • H05B3/40—Heating elements having the shape of rods or tubes
    • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
    • H05B3/48—Heating elements having the shape of rods or tubes non-flexible heating conductor embedded in insulating material
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49083—Heater type
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49087—Resistor making with envelope or housing
    • Y10T29/49089—Filling with powdered insulation
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T29/00—Metal working
    • Y10T29/49—Method of mechanical manufacture
    • Y10T29/49002—Electrical device making
    • Y10T29/49082—Resistor making
    • Y10T29/49087—Resistor making with envelope or housing
    • Y10T29/49089—Filling with powdered insulation
    • Y10T29/49091—Filling with powdered insulation with direct compression of powdered insulation

Definitions

  • ABSTRACT A method for producing cartridge heaters in which a going and returning heating coil is inserted into a heatresisting cove-r pipe with an elliptical cross-section so as to align the cross-sections of the going and the returning portions of the heating coil along the longer axis of the elliptical cross-section of the cover pipe,
  • powdered insulator is charged in the space within the p cover pipe not occupied by said coil, the longer axis is reduced by compressing the cover pipe in the direction along the longer axis and the cross-section of the heating coil is deformed into an ellipse having its longer axis perpendicular to the direction of the compression.
  • This invention relates to a method for producing cartridge heaters having a cover pipe and a going and returning heating coil contained therein.
  • This kind of cartridge heater comprises a heat-resisting cover pipe a going and returning heating coil 11 contained therein and powdered insulator 12 charged in the space within the cover pipe not occupied by the heating coil.
  • the circular cross-sectional area of the heating coil is limitted to within a certain value when the diameter of the cover pipe is kept constant.
  • the length of the resistance wire of the heating coil containable in unit length of the cover pipe is limitted and the heat generated in unit length of the heating coil is subject to limitation.
  • the density of the heat generated must be large, it can not be avoided to use a heater under an over-load condition by passing an over-current in the resistance wire. It can be considered to make the crosssection of the heating coil elliptical in order to increase the quantity of the resistance wire containable in unit length of the cover pipe.
  • the powdered insulator is charged within the cover pipe during a process where only a guiding jig is pulled out from the cover pipe after the heating coil held firmly by the guiding jig has been inserted in the cover pipe as shown in FIG. 5.
  • this charging process some oscillation is applied to the cover pipe longitudinally and transversely in order to enlarge the charging efficiency and so it happens that the circular cover pipe is rotated against the heating coil, the heating coil being twisted. This twist of the heating coil is apt to occur more often when longer heaters are manufactured. If the heating coil is provided with some clamp in order to eliminate this twist, the oscillation for effectuating the charging of the powdered insulator is weakened and the charging work becomes troublesome.
  • a going and returning heating coil is inserted in a cover pipe having an elliptical cross-section and the cross-sections of the going and the returning parts of the heating coil are aligned on the longer axis of the ellipse.
  • This arrangement of the cover pipe and the heating coil itself makes the going and the returning portions of the heating coil difficult to be twisted and moreover, the prevention of the twist is still effective, if a guiding jig fit in the cover pipe for inserting the heating coil is used.
  • the cover pipe After the powdered insulator has been charged within the cover pipe, the cover pipe is compressed along the longer axis of it and the cross-section of the cover pipe is deformed to be substantially circular in most cases, that of the heating coil becoming elliptical at the same time.
  • the cross-section of the compressed cartridge heater When the cross-section of the compressed cartridge heater is observed, it is found that the cross-sectional area of the heating coil deforms elliptically and extends in such a region in the cover pipe that was not made use of in a conventional cartridge heater where a going and returning heating coil with a circular cross-section is contained within a cover pipe with a circular cross-section.
  • the density of heat generated in unit length of a heater is much increased.
  • FIG. 1 is a cross-sectional view of a cartridge heater according to the present invention before it is compressed.
  • FIG. 2 is a cross-sectional view of the heater in FIG. 1 after it is compressed.
  • FIG. 3 is a cross-sectional view of a conventional heater before it is compressed.
  • FIG. 4 is a cross-sectional view of the heater in FIG. 3 after it is compressed.
  • FIG. 5 is a front elevational view of partial section showing the cartridge heater according to the present invention in a powdered insulator charging process.
  • FIG. 6 is a section taken on a line 66 of FIG. 5.
  • FIG. 7 is a longitudinal section for showing the situation of a heating coil.
  • 10 shows generally a cover pipe having an elliptical cross-section and made of heat-resisting material such as stainless steel or copper.
  • a heating coil 11 is made of a resistance wire wound helically and has a circular cross-section. Either end of the heating coil is connected to a lead wire 14 by means of a terminal pin 13 and hook 13a.
  • a guiding jig or a guiding pipe 15 for inserting said heating coil into the cover pipe 10 has an elliptical cross-section similar to and smaller than that of the cover pipe in order to be inserted in the cover pipe 10 and is provided with a pair of guiding paths 16 having a cross-section suitable for passing the heating coil 11 therein.
  • Said heating coil 11 is bent at the middle portion and passed through the pair of guiding paths.
  • the guidingjig 15 containing the going and returning heating coil 11 therein is inserted in the cover pipe 10.
  • the cross-sections of the going and the returning portions of the heating coil 11 are aligned within the cover pipe 10 along the longer axis of its elliptical cross-section. While only the guiding jig 15 is pulled out from the cover pipe 10 and longitudinal and transverse oscillations are applied to the cover pipe, some powdered insulator 12 such as alumina or magnesia is charged on.
  • the cover pipe 10 is compressed by a diameter-reducing machine such as a awaging machine or a roll-press along its longer axis indicated by an arrow 17. Also in the direction along the shorter axis shown by an arrow 18, the cover pipe is compressed to some extent in order to prevent the cover pipe from extending in this direction and to effectuate more or less compression.
  • a diameter-reducing machine such as a awaging machine or a roll-press along its longer axis indicated by an arrow 17.
  • the cover pipe is compressed to some extent in order to prevent the cover pipe from extending in this direction and to effectuate more or less compression.
  • the powdered insulator 12 becomes of high density and on the other hand the cross-section of the cover pipe deforms to be substantially circular and the cross-section of the heating coil becomes an ellipse having its shorter axis along the direction of the compression, that is, the direction of the longer axis of the cross-section of the cover pipe before compression.
  • the elliptically deformed heating coil 11 is extending into the region, where a heating coil 11' would not be situated in a conventional cartridge heater, without reducing the insulating distance between the cover pipe and the heating coil 11 and between the going and the returning portions of the heating coil.
  • the quantity of resistance wire containable in unit length of the heater is increased and thereby heat generated in unit length of the heater is also enlarged.
  • a method for producing cartridge heaters which includes the steps of inserting a going and returning heating coil of a circular cross-section within a heatresisting cover pipe with an elliptical cross-section, the
  • heating coil being aligned along the longer axis of the elliptical cross-section of said cover pipe, charging powdered insulator in the region within the cover pipe not occupied by said heating coil and reducing said longer axis by compressing said cover pipe along said longer axis to deform the cross-section into a less eccentric ellipse and the cross-section of said heating coil into an elliptical one having its longer axis perpendicular to the direction of compression.
  • a method for producing cartridge heaters according to claim 1 including the step of using a guiding jig having a cross-section suitable for being set within the cover pipe before compression and provided with a pair of parallel guiding paths for inserting said going and returning coil in said cover pipe.
  • a method for producing cartridge heaters according to claim 1 including the step of making the crosssection of said cover pipe circular by compressing said

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  • Resistance Heating (AREA)

Abstract

A method for producing cartridge heaters in which a going and returning heating coil is inserted into a heat-resisting cover pipe with an elliptical cross-section so as to align the crosssections of the going and the returning portions of the heating coil along the longer axis of the elliptical cross-section of the cover pipe, powdered insulator is charged in the space within the cover pipe not occupied by said coil, the longer axis is reduced by compressing the cover pipe in the direction along the longer axis and the cross-section of the heating coil is deformed into an ellipse having its longer axis perpendicular to the direction of the compression.

Description

United States Patent [191 Saku [ Dec. 30, 1975 [54] METHOD FOR PRODUCING CARTRIDGE HEATERS [75] Inventor:
[73] Assignee: Kabushikikaisha Kawaidenkiseisakusho, Nagoya, Japan 22 Filed: July 12,1974
211 Appl. No.: 487,958
Isamu Saku, Aichi, Japan [30] Foreign Application Priority Data FOREIGN PATENT S OR APPLICATIONS 717,494 10/1954 United Kingdom 29/614 Primary Examiner-Victor A. Di Palma Attorney, Agent, or FirmWilliam Anthony Drucker [57] ABSTRACT A method for producing cartridge heaters in which a going and returning heating coil is inserted into a heatresisting cove-r pipe with an elliptical cross-section so as to align the cross-sections of the going and the returning portions of the heating coil along the longer axis of the elliptical cross-section of the cover pipe,
powdered insulator is charged in the space within the p cover pipe not occupied by said coil, the longer axis is reduced by compressing the cover pipe in the direction along the longer axis and the cross-section of the heating coil is deformed into an ellipse having its longer axis perpendicular to the direction of the compression.
3 Claims, 7 Drawing Figures US. Patent Dec. 30, 1975 METHOD FOR PRODUCING CARTRIDGE HEATERS BACKGROUND OF THE INVENTION This invention relates to a method for producing cartridge heaters having a cover pipe and a going and returning heating coil contained therein. This kind of cartridge heater comprises a heat-resisting cover pipe a going and returning heating coil 11 contained therein and powdered insulator 12 charged in the space within the cover pipe not occupied by the heating coil. As insulation must be maintained between the heating coil and the cover pipe and between the going and the returning portions of the heating coil, the circular cross-sectional area of the heating coil is limitted to within a certain value when the diameter of the cover pipe is kept constant. For this reason, the length of the resistance wire of the heating coil containable in unit length of the cover pipe is limitted and the heat generated in unit length of the heating coil is subject to limitation. When the density of the heat generated must be large, it can not be avoided to use a heater under an over-load condition by passing an over-current in the resistance wire. It can be considered to make the crosssection of the heating coil elliptical in order to increase the quantity of the resistance wire containable in unit length of the cover pipe. However, it is not easy to make the cross-section of the heating coil elliptical and such heating coil is apt to be damaged in a manufacturing process.
The powdered insulator is charged within the cover pipe during a process where only a guiding jig is pulled out from the cover pipe after the heating coil held firmly by the guiding jig has been inserted in the cover pipe as shown in FIG. 5. In this charging process, some oscillation is applied to the cover pipe longitudinally and transversely in order to enlarge the charging efficiency and so it happens that the circular cover pipe is rotated against the heating coil, the heating coil being twisted. This twist of the heating coil is apt to occur more often when longer heaters are manufactured. If the heating coil is provided with some clamp in order to eliminate this twist, the oscillation for effectuating the charging of the powdered insulator is weakened and the charging work becomes troublesome.
SUMMARY OF THE INVENTION A going and returning heating coil is inserted in a cover pipe having an elliptical cross-section and the cross-sections of the going and the returning parts of the heating coil are aligned on the longer axis of the ellipse. This arrangement of the cover pipe and the heating coil itself makes the going and the returning portions of the heating coil difficult to be twisted and moreover, the prevention of the twist is still effective, if a guiding jig fit in the cover pipe for inserting the heating coil is used. After the powdered insulator has been charged within the cover pipe, the cover pipe is compressed along the longer axis of it and the cross-section of the cover pipe is deformed to be substantially circular in most cases, that of the heating coil becoming elliptical at the same time. When the cross-section of the compressed cartridge heater is observed, it is found that the cross-sectional area of the heating coil deforms elliptically and extends in such a region in the cover pipe that was not made use of in a conventional cartridge heater where a going and returning heating coil with a circular cross-section is contained within a cover pipe with a circular cross-section. The density of heat generated in unit length of a heater is much increased.
The salient relationships of the present invention have been made clear and it will be understood that the heater according to the present invention is easy to manufacture and of high heat-generating density. The other objects of the present invention will become clear in conjunction with the following detailed description and drawings.
IN THE DRAWINGS FIG. 1 is a cross-sectional view of a cartridge heater according to the present invention before it is compressed.
FIG. 2 is a cross-sectional view of the heater in FIG. 1 after it is compressed.
FIG. 3 is a cross-sectional view of a conventional heater before it is compressed.
FIG. 4 is a cross-sectional view of the heater in FIG. 3 after it is compressed.
FIG. 5 is a front elevational view of partial section showing the cartridge heater according to the present invention in a powdered insulator charging process.
FIG. 6 is a section taken on a line 66 of FIG. 5.
FIG. 7 is a longitudinal section for showing the situation of a heating coil.
Referring to the drawings, 10 shows generally a cover pipe having an elliptical cross-section and made of heat-resisting material such as stainless steel or copper. A heating coil 11 is made of a resistance wire wound helically and has a circular cross-section. Either end of the heating coil is connected to a lead wire 14 by means of a terminal pin 13 and hook 13a. A guiding jig or a guiding pipe 15 for inserting said heating coil into the cover pipe 10 has an elliptical cross-section similar to and smaller than that of the cover pipe in order to be inserted in the cover pipe 10 and is provided with a pair of guiding paths 16 having a cross-section suitable for passing the heating coil 11 therein. Said heating coil 11 is bent at the middle portion and passed through the pair of guiding paths. Next the guidingjig 15 containing the going and returning heating coil 11 therein is inserted in the cover pipe 10. The cross-sections of the going and the returning portions of the heating coil 11 are aligned within the cover pipe 10 along the longer axis of its elliptical cross-section. While only the guiding jig 15 is pulled out from the cover pipe 10 and longitudinal and transverse oscillations are applied to the cover pipe, some powdered insulator 12 such as alumina or magnesia is charged on. The relative rotation between the cover pipe 10 and the guiding jig resulting from the oscillation for increasing the charging efficiency of this powdered insulator I2 is prevented in this case because the cross-section of them are nested ellipses. After the charging of the powdered insulator is finished, the cover pipe 10 is compressed by a diameter-reducing machine such as a awaging machine or a roll-press along its longer axis indicated by an arrow 17. Also in the direction along the shorter axis shown by an arrow 18, the cover pipe is compressed to some extent in order to prevent the cover pipe from extending in this direction and to effectuate more or less compression. As the result of compression, the powdered insulator 12 becomes of high density and on the other hand the cross-section of the cover pipe deforms to be substantially circular and the cross-section of the heating coil becomes an ellipse having its shorter axis along the direction of the compression, that is, the direction of the longer axis of the cross-section of the cover pipe before compression. By comparing FIGS. 2 and 4, it is easily found that the elliptically deformed heating coil 11 is extending into the region, where a heating coil 11' would not be situated in a conventional cartridge heater, without reducing the insulating distance between the cover pipe and the heating coil 11 and between the going and the returning portions of the heating coil. Thus, the quantity of resistance wire containable in unit length of the heater is increased and thereby heat generated in unit length of the heater is also enlarged.
What I claim is:
l. A method for producing cartridge heaters, which includes the steps of inserting a going and returning heating coil of a circular cross-section within a heatresisting cover pipe with an elliptical cross-section, the
heating coil being aligned along the longer axis of the elliptical cross-section of said cover pipe, charging powdered insulator in the region within the cover pipe not occupied by said heating coil and reducing said longer axis by compressing said cover pipe along said longer axis to deform the cross-section into a less eccentric ellipse and the cross-section of said heating coil into an elliptical one having its longer axis perpendicular to the direction of compression.
2. A method for producing cartridge heaters according to claim 1 including the step of using a guiding jig having a cross-section suitable for being set within the cover pipe before compression and provided with a pair of parallel guiding paths for inserting said going and returning coil in said cover pipe.
3. A method for producing cartridge heaters according to claim 1 including the step of making the crosssection of said cover pipe circular by compressing said

Claims (3)

1. A method for producing cartridge heaters, which includes the steps of inserting a going and returning heating coil of a circular cross-section within a heat-resisting cover pipe with an elliptical cross-section, the cross-section of the going and returning portions of the heating coil being aligned along the longer axis of the elliptical cross-section of said cover pipe, charging powdered insulator in the region within the cover pipe not occupied by said heating coil and reducing said longer axis by compressing said cover pipe along said longer axis to deform the cross-section into a less eccentric ellipse and the crosssection of said heating coil into an elliptical one having its longer axis perpendicular to the direction of compression.
2. A method for producing cartridge heaters according to claim 1 including the step of using a guiding jig having a cross-section suitable for being set within the cover pipe before compression and provided with a pair of parallel guiding paths for inserting said going and returning coil in said cover pipe.
3. A method for producing cartridge heaters according to claim 1 including the step of making the cross-section of said cover pipe circular by compressing said cover pipe.
US487958A 1973-07-12 1974-07-12 Method for producing cartridge heaters Expired - Lifetime US3928909A (en)

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1982001112A1 (en) * 1980-09-18 1982-04-01 Mfg Co Thermon Parallel-type heating cable and method of making same
DE3340359A1 (en) * 1982-11-08 1984-05-10 Ngk Spark Plug Co., Ltd., Nagoya, Aichi METHOD FOR PRODUCING A CERAMIC RADIATOR AND CERAMIC GLOW PLUG
US20040211771A1 (en) * 2003-04-25 2004-10-28 Walter Crandell Compacted cartridge heating element with a substantially polygonal cross section
US20080175572A1 (en) * 2007-01-19 2008-07-24 Barnes Ronald R Heating element for appliance
US20140263282A1 (en) * 2013-03-14 2014-09-18 Chromalox, Inc. Medium voltage heating element assembly

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2012074312A (en) * 2010-09-29 2012-04-12 Mach Kiki Kk Lip heater for fryer

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2643317A (en) * 1950-02-11 1953-06-23 Tuttle & Kift Inc Electric heater
US2701410A (en) * 1950-07-01 1955-02-08 Knapp Monarch Co Method of producing electric heating elements
US2808492A (en) * 1954-07-26 1957-10-01 Gen Electric Electric heating units and methods of making the same
US2897467A (en) * 1955-05-04 1959-07-28 Gen Motors Corp Sheathed tubular electrical heater
US3007235A (en) * 1958-09-02 1961-11-07 Gen Electric Method of making sheathed electric heating units
US3082511A (en) * 1957-11-14 1963-03-26 Gen Motors Corp Heating unit manufacture
US3468023A (en) * 1966-11-01 1969-09-23 Wiegand Co Edwin L Method of making electric resistance heating units

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2643317A (en) * 1950-02-11 1953-06-23 Tuttle & Kift Inc Electric heater
US2701410A (en) * 1950-07-01 1955-02-08 Knapp Monarch Co Method of producing electric heating elements
US2808492A (en) * 1954-07-26 1957-10-01 Gen Electric Electric heating units and methods of making the same
US2897467A (en) * 1955-05-04 1959-07-28 Gen Motors Corp Sheathed tubular electrical heater
US3082511A (en) * 1957-11-14 1963-03-26 Gen Motors Corp Heating unit manufacture
US3007235A (en) * 1958-09-02 1961-11-07 Gen Electric Method of making sheathed electric heating units
US3468023A (en) * 1966-11-01 1969-09-23 Wiegand Co Edwin L Method of making electric resistance heating units

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1982001112A1 (en) * 1980-09-18 1982-04-01 Mfg Co Thermon Parallel-type heating cable and method of making same
US4345368A (en) * 1980-09-18 1982-08-24 Thermon Manufacturing Co. Parallel-type heating cable and method of making same
US4392051A (en) * 1980-09-18 1983-07-05 Thermon Manufacturing Company Parallel-type heating cable
DE3340359A1 (en) * 1982-11-08 1984-05-10 Ngk Spark Plug Co., Ltd., Nagoya, Aichi METHOD FOR PRODUCING A CERAMIC RADIATOR AND CERAMIC GLOW PLUG
US20040211771A1 (en) * 2003-04-25 2004-10-28 Walter Crandell Compacted cartridge heating element with a substantially polygonal cross section
US20080175572A1 (en) * 2007-01-19 2008-07-24 Barnes Ronald R Heating element for appliance
US7949238B2 (en) * 2007-01-19 2011-05-24 Emerson Electric Co. Heating element for appliance
US20140263282A1 (en) * 2013-03-14 2014-09-18 Chromalox, Inc. Medium voltage heating element assembly
US9301341B2 (en) * 2013-03-14 2016-03-29 Chromalox, Inc. Medium voltage heating element assembly

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