CA1094618A - Fuse with housing end caps secured by magnetic pulse forming - Google Patents
Fuse with housing end caps secured by magnetic pulse formingInfo
- Publication number
- CA1094618A CA1094618A CA262,492A CA262492A CA1094618A CA 1094618 A CA1094618 A CA 1094618A CA 262492 A CA262492 A CA 262492A CA 1094618 A CA1094618 A CA 1094618A
- Authority
- CA
- Canada
- Prior art keywords
- housing
- fuse
- metallic
- thickness
- flange
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H69/00—Apparatus or processes for the manufacture of emergency protective devices
- H01H69/02—Manufacture of fuses
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
- H01H85/0013—Means for preventing damage, e.g. by ambient influences to the fuse
- H01H85/0021—Means for preventing damage, e.g. by ambient influences to the fuse water or dustproof devices
- H01H85/003—Means for preventing damage, e.g. by ambient influences to the fuse water or dustproof devices casings for the fusible element
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H85/00—Protective devices in which the current flows through a part of fusible material and this current is interrupted by displacement of the fusible material when this current becomes excessive
- H01H85/02—Details
- H01H85/04—Fuses, i.e. expendable parts of the protective device, e.g. cartridges
- H01H85/041—Fuses, i.e. expendable parts of the protective device, e.g. cartridges characterised by the type
- H01H85/042—General constructions or structure of high voltage fuses, i.e. above 1000 V
-
- 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
- Y10T29/49803—Magnetically shaping
-
- 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
- Y10T29/49826—Assembling or joining
- Y10T29/49908—Joining by deforming
- Y10T29/49915—Overedge assembling of seated part
- Y10T29/49917—Overedge assembling of seated part by necking in cup or tube wall
- Y10T29/49918—At cup or tube end
-
- 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
- Y10T29/49826—Assembling or joining
- Y10T29/49908—Joining by deforming
- Y10T29/49925—Inward deformation of aperture or hollow body wall
- Y10T29/49927—Hollow body is axially joined cup or tube
Abstract
ABSTRACT: End ferrules of a current limiting fuse are mounted to the end of a relatively fragile non-metallic insulator housing of the fuse by magnetic pulse forming. The end ferrules are formed so that there is a flat circular end wall and an annular mounting flange. The flat circular end walls are of a first thickness sufficient to withstand mechanical forces that may be experienced due to fuse operation or due to mounting of the fuse. The annular mounting flange is of a second thickness less than the first thickness so that the flange can be compressed around the housing by magnetic pulse forming without causing undue stress to be exerted on the housing that may result in damage to the housing. A unique elastomer ring seal is provided between the housing and the end ferrule to assure a moisture tight seal. The method disclosed is applicable to allow compressive attach-ment of a variety of metallic members to a variety of rela-tively fragile members so that the strength of the metallic member may be maintained, but the metallic member may be compressed without damage to the fragile member.
Description
~3 ~fl~
Magnetic~pulse forming machines were first introduced in 1962. Since that time, magnetic pulse forming machi~es have been utilized to assemble a variety of com-posite articles of manufacture which would be difficult and S costly to assemble by conventional methods.
Magnetic pulse forming i8 an assemhly technique which utilizes a high intensity magnetic field to expand or contract metallic work pieces. Magnetic pulse fonming is based on the interaction of a rapidly changing magnetic field and the currents induced in an electrically conductive work piece. Magnetic pulse forming is capable of compressing or expanding me~al members wi~hout direct physical contac~ and without lubricants or torque normally encountered in rolling and spinning operations.
~he high flux densities necessary tv perform such magnetic pulse forming can be produced in the absence of a material of high permeability by discharging a capacitor through coil for a period of a f~w microseconds. Thus, tremendous flux densities are produced for a short period of : 20 tLme. Further, since it is the magnetic force which moves he metal~ the introduction ofa non-conductive material between the work piece and the magnetic field pro-ducing member has no eff~cton the assembly operation, al-; though more enexgy i~ required for this type of operation because of the increased distance through which the magnetic: field must act~
~ agnetic pulse forming is par~icularly advantageous to form metallic members tG non metallic members. For example, brass tubing and aluminum ~leeves may be successfully assembled to a ~ariety o~ phenolic materials to provide structurally sound joints. The time consuming and costly spinning opera-tions generally required for such assemblies are eliminated when the parts are assembled magnetically.
However, some difficulty is experienced when assembling metallic members to non-metallic relatively fragile members. For example, many non-metallic materials have a relatively high tensile strength but a relatively low comp-ressive strength. Consequently, extreme care must be utilized when compressing such metallic members onto such non-metallic members by magnetic pulse forming to prevent fracture of the non-metallic member. A further problem is experienced where the metallic members must be of sufficient strength to with-stand stress forces applied to the metallic member but the member must be compressed onto a relatively fragile non-metallic member. Since the metallic member must be thick enough to withstand the stress applied, a relatively large magnetic force must be applied to compress the metallic member onto the non-metallic member by magnetic pulse forming. Often in such circumstances, magnetic pulse forming is not suitable since sufficient force cannot be applied to compress the metallic member without also fracturing the non-metallic member~
A composite article of manufacture in accordance with the present invention comprised a first member formed of a brittle material or a material having low compressive strength and a second metallic member that is normally anticipated to be subjected to mechanical stress. The second metallic member includes a first portion dimensioned to withstand the anticipated mechanical stress, and a second portion integrally connected to the first portion and .~.7U
n,~. .i~
~ a'~
being dimensioned to be compressed onto the first member to attach the second member to the first member by magnetic pulse forming without damaging the first member.
More specifically, the first member may be a cylindrical hollow housing of an e]ectrical fuse which is formed of an electrically insulating material having low compressive strength. The second metallic member may comprise an end member having a circular end wall of a first thickness sufficient to withstand the mechanical stress incident to the mounting and operation of the use. An annular flange is formed integrally with the circular end wall along the edge thereof and extending approximately perpendicular thereto. ~he flange has a second thickness less than the first thickness of the circular end wall.
First and second end members are positioned over opposite open ends of the housing and the annular flanges are compressed onto the ends of the housing by magnetic pulse forming. The second thickness of the flange of the end walls is thin enough to permit the annular flanges to be compressed by magnetic pulse forming without causing damage to the housing~
The housing may also include an annular rabbet formed around the exterior edge of each end of the housing which is dimensioned to receive a seal member, such as an elastomer ring so that when the first and second members are attached over the ends of the housing, the seal member seat against the end members providing a moisture-proof seal between the end members and the housing. To further assure a proper seal, the seal member may be coated with a vulcanizing silicone rubber material.
The present invention also involves a method of ~4 -3-D ~
attaching a metallic member that will be subject to stress to a relatively frayile non-metallic member by compressing a portion of the metallic member around the fragi]e member.
The method comprises the steps of forming the metal~ic member so that the portion of the metallic member that is subject to the stress is of a first thickness sufficient to withstand those stresses and the portion of the metallic member that will be compressed onto the fragile member is of a second thickness thin enough to permit compression without damaging the fragile member. The next step is to place the metallic member in the proper position over the fragile member, and the last step is to compress the portion having the second thickness against the fragile member by magnetic pulse forming.
Accordingly, it is a primary object of the present invention to provide a composite article of manufacture and method of fabrication thereof for attaching a metallic member to a relatively fragile non-metallic member by mag-netic pulse forming without damaging the relatively fragile member.
It is yet another subject of the present invention to provide a unique construction of a high voltage fuse having a metallic end members attached to a non-metallic insulator housing by magnetic pulse forming in such a manner that damage to the insulator housing is avoided.
It is yet another object of the present invention to provide a unique construction for a high voltage fuse having a unique seal between the insulated housing and end member that assures a moisture~proof seal.
It is yet another object of the present invention ~.L.~
-to provide a method oE connecting a metallic member to a non-metallic member having relatively low compressive strength by magnetic pulse forming in such a r,lanner that damage to the non-metallic member is avoided.
These and other objects, advantages, and features will hereinafter appear, and for the purpose of illustration, but not of limitation, exemplary embodiments are illustrated in the accompanying drawings.
FIGURE 1 is a cross-sectional view of a high voltage fuse preferrea embodiment of the present invention.
FIGURE 2 is a partially fragmentary, partially cross-sectional view of the insulator housing of the preferred embodiment illustrated in FIGURE 1.
FIGURE 3 is an end view taken substantially along line 3~3 in FIGURE 2.
FIGURE 4 is a cross-sectional, partially fragmentary view of a portion of the end of the insulator housing.
FIGURE 5 is an end view of the end ferrule member of the preferred embodiment illustrated in FIGURE 1.
FIGURE 6 is a cross-sectional view taken sub-stantially along line 6-6 in FIGURE 5.
FIGURE 7 is a cross-sectional, partially fragmentary view showing the end ferrule member in position ready for magnetic pulse forming.
With reference to FIGURE 1, high voltage fuse 10 comprises hollow cylindrical insulator housing 12 of a suitable electrically insulating material such as glass reinforced epoxy resin. Mounted over each end of hollow cylindrical housing 12 in a manner more fully described hereinafter are metallic end ferrule members 1~. Mounted on end ferrule .~1 ,'`
~ ,. ...
~ D~
members 14 are a mounting stud 15 and a mounting spade 18 for connecting the fuse 10 in a high voltage electrical circuit. Mounted on the inside of housing 12 is a fusible element support assembly 20 which supports fusible elements 22 and 24. The exact construction of fusible element support assembly 20 does not form a part of the subject matter of the present invention and is more fully described in co~
pending Canadian patent application Serial No. 262,491 Schmunk, et al., entitled HIGH VOLTAGE FUSE AND METHOD OF
CONSTRUCTION THEREOF, filed October 1, 1976, and assigned to the same assignee as the present invention.
With reference to FIGURES 2, 3,and 4, housing 12 comprises an annular groove 26 formed around the exterior of housing 12 adjacent each end thereof. Also formed around the exterior edge of each end of housing 12 is a rabbet 28 in which an elastomer ring 30 is positioned. Rabbet 28 is dimen-sioned so that elastomer ring 30 ext~nds slightly beyond the end of housing 12 so that when end ferrule member 14 is positioned over the end of housing 12 and connected thereto a moisture-proof seal is formed between housing 12 and end ferrule member 1~.
With reference to FIGURES 5 and 6, end ferrule members 14 are initially fabricated to comprise an essentially flat circular end wall 32 and an annular flange 34 integrally formed to the flat circular end wall around the periphery thereof and extending approximately perpendicular from flat circular end wall 32, An opening 36 is provided through wall 32 for receiving the end of support assemhly 20 so that support assembly 20 may be welded to end ferrule members 14. In addition, another opening 38 may be provided through .~. -6 encl ferrule member to allow an electrically non-conducting filler material such as quartz sand to be inserted into fuse 10 after end ferrule members 14 have been mounted to the ends of housing 12. Opening 38 is then welded closed after the filler material has been inserted. A suitable mounting fixture such as mounting stud 16 of mounting stud 18 may be welded to the center of circular end wall 32 as illustrated in FIGWRE 1.
When fuse 10 is mounted in an electrical circuit, mechanical forces may be exerted on end wall 32 by mounting stud 16 and mounting spade lg. Further, when fuse 10 operates, fusible member 22 and 24 will rapidly vaporize causing an increase in gas pressure within the fuse 10.
Accor~ingly, end ferrule member 14 will e~perience stresses incident to both the mounting and operation of fuse 10.
To withstand these stresses, end wall 32 is fabricated so that i-t has a thickness Dl (see FIGURE 6) that is thick ; enough to withstand the stresses that will be applied to end wall 32. However, since housing 12 is typically formed o a glass reinforced epoxy resin material which has a relatively high tensile strength but a relatively low compres-sive strength, hollow cylindrical housing 12 is relatively fragile and could be damaged when end ferrule members 14 are compressed over the ends of housing 12. Accordingly, annular flange 34 is fabricated to have a thickness D2 which is less than the thickness Dl of circular end wall 32. Thickness D2 is selected so that flange B4 can be compressed by magnetic pulse forming without causing damage to housing 12.
End ferrule members 14 are attached to the end of : 30 housing 12 by magnetic pulse forming. With reference to --7~
! ~, i ~3~
FIGURE 7, an uncompressed end ferrule member 14 is shown positioned over the end of housing 12 with the magnetic pulse forming flux producing member 40 positioned immediately adjacent annular flange 34. Flux producing member 40 is a part of conventional magnetic pulse forming equipment that operates in the conventional manner to produce a short duration, high flux magnetic field which causes a compressive force to be applied to annular flange 34 to cause annular flange 34 to be compressed into annular groove 26 as illustrated in FIGURE 1.
~ lastomer ring 30 is placed in rabbet 28 before end ferrule member 14 is placed over the end of housing 12.
Elastomer ring 30 forms a seal between the housing 12 and the end ferrule member 14. To further facilitate the seal between the housing 12 and end ferrule member 14, the elastomer ring 30 may be coated with a vulcanizing sili-cone rubber material such as the vulcanizing silicone rubber material sold under the trademark SILASTIC, 732 RTV by the Dow Corning Co. This on-part vulcanizing silicone rubber acts to further assure that a moisture-proof seal is form~d between housing 12 and end ferrule member 14. This is particularly desirable where housing 12 is fabricated from a glass reinforced epoxy resin since it is difficult to machine a smooth rabbet 28 in such material that will provide a moisture-proof seal with elastomer ring 30. The vulcanizing silicone rubber material assures a moisture-proof seal despite possible roughness of rabbet 28.
Since housing 12 is not capable of wi~hstanding substantial compressive stresses~ the thickness D2 of annular flange 3~ must be sufficiently thin so that it "~,;3~
~.l 8 may be magnetically pulse formed around housing 12 without causing housing 12 to crack or be otherwise damaged.
However, since flat circular end wall 32 is not subject to magnetic pulse forming but is subjected to substantial mechanical stresses during mounting and fuse operation, the thickness Dl of circular end wall 32 may be made much thicker to withstand the mechanical stresses without jeopardizing the ability of the end ferrule member 14 to be magnetically pulse formed over the end of housing 12.
It should be apparent that the method and technique of attaching metallic end ferrule member 14 to the end of relatively fragile cylindrical housing 12 has applicability in a wide range of composite articles of manufacture wherein a metallic member must be attached to a relatively fragile non-metallic member by magnetic pulse forming. Thus, where a portion of the metallic member will experience mechanical stresses, that portion may be made substantially thick enough to withstand those mechanical forces provided that the portion of the metallic member which is compressed over the relatively ~ragile non-metallic member is made thin enough so that when the metallic member is compressed over the fragile member by magnetic pulse forming damage does not result to the fragile member.
Thus, it may be seen that a variety of metallic members may be mounted to a variety of relatively fragile non-metallic members by magnetic pulse forming utilizing the invention described herein without departing from the spirit and scope of the present invention as defined in the appended claims.
, ~ ".
Magnetic~pulse forming machines were first introduced in 1962. Since that time, magnetic pulse forming machi~es have been utilized to assemble a variety of com-posite articles of manufacture which would be difficult and S costly to assemble by conventional methods.
Magnetic pulse forming i8 an assemhly technique which utilizes a high intensity magnetic field to expand or contract metallic work pieces. Magnetic pulse fonming is based on the interaction of a rapidly changing magnetic field and the currents induced in an electrically conductive work piece. Magnetic pulse forming is capable of compressing or expanding me~al members wi~hout direct physical contac~ and without lubricants or torque normally encountered in rolling and spinning operations.
~he high flux densities necessary tv perform such magnetic pulse forming can be produced in the absence of a material of high permeability by discharging a capacitor through coil for a period of a f~w microseconds. Thus, tremendous flux densities are produced for a short period of : 20 tLme. Further, since it is the magnetic force which moves he metal~ the introduction ofa non-conductive material between the work piece and the magnetic field pro-ducing member has no eff~cton the assembly operation, al-; though more enexgy i~ required for this type of operation because of the increased distance through which the magnetic: field must act~
~ agnetic pulse forming is par~icularly advantageous to form metallic members tG non metallic members. For example, brass tubing and aluminum ~leeves may be successfully assembled to a ~ariety o~ phenolic materials to provide structurally sound joints. The time consuming and costly spinning opera-tions generally required for such assemblies are eliminated when the parts are assembled magnetically.
However, some difficulty is experienced when assembling metallic members to non-metallic relatively fragile members. For example, many non-metallic materials have a relatively high tensile strength but a relatively low comp-ressive strength. Consequently, extreme care must be utilized when compressing such metallic members onto such non-metallic members by magnetic pulse forming to prevent fracture of the non-metallic member. A further problem is experienced where the metallic members must be of sufficient strength to with-stand stress forces applied to the metallic member but the member must be compressed onto a relatively fragile non-metallic member. Since the metallic member must be thick enough to withstand the stress applied, a relatively large magnetic force must be applied to compress the metallic member onto the non-metallic member by magnetic pulse forming. Often in such circumstances, magnetic pulse forming is not suitable since sufficient force cannot be applied to compress the metallic member without also fracturing the non-metallic member~
A composite article of manufacture in accordance with the present invention comprised a first member formed of a brittle material or a material having low compressive strength and a second metallic member that is normally anticipated to be subjected to mechanical stress. The second metallic member includes a first portion dimensioned to withstand the anticipated mechanical stress, and a second portion integrally connected to the first portion and .~.7U
n,~. .i~
~ a'~
being dimensioned to be compressed onto the first member to attach the second member to the first member by magnetic pulse forming without damaging the first member.
More specifically, the first member may be a cylindrical hollow housing of an e]ectrical fuse which is formed of an electrically insulating material having low compressive strength. The second metallic member may comprise an end member having a circular end wall of a first thickness sufficient to withstand the mechanical stress incident to the mounting and operation of the use. An annular flange is formed integrally with the circular end wall along the edge thereof and extending approximately perpendicular thereto. ~he flange has a second thickness less than the first thickness of the circular end wall.
First and second end members are positioned over opposite open ends of the housing and the annular flanges are compressed onto the ends of the housing by magnetic pulse forming. The second thickness of the flange of the end walls is thin enough to permit the annular flanges to be compressed by magnetic pulse forming without causing damage to the housing~
The housing may also include an annular rabbet formed around the exterior edge of each end of the housing which is dimensioned to receive a seal member, such as an elastomer ring so that when the first and second members are attached over the ends of the housing, the seal member seat against the end members providing a moisture-proof seal between the end members and the housing. To further assure a proper seal, the seal member may be coated with a vulcanizing silicone rubber material.
The present invention also involves a method of ~4 -3-D ~
attaching a metallic member that will be subject to stress to a relatively frayile non-metallic member by compressing a portion of the metallic member around the fragi]e member.
The method comprises the steps of forming the metal~ic member so that the portion of the metallic member that is subject to the stress is of a first thickness sufficient to withstand those stresses and the portion of the metallic member that will be compressed onto the fragile member is of a second thickness thin enough to permit compression without damaging the fragile member. The next step is to place the metallic member in the proper position over the fragile member, and the last step is to compress the portion having the second thickness against the fragile member by magnetic pulse forming.
Accordingly, it is a primary object of the present invention to provide a composite article of manufacture and method of fabrication thereof for attaching a metallic member to a relatively fragile non-metallic member by mag-netic pulse forming without damaging the relatively fragile member.
It is yet another subject of the present invention to provide a unique construction of a high voltage fuse having a metallic end members attached to a non-metallic insulator housing by magnetic pulse forming in such a manner that damage to the insulator housing is avoided.
It is yet another object of the present invention to provide a unique construction for a high voltage fuse having a unique seal between the insulated housing and end member that assures a moisture~proof seal.
It is yet another object of the present invention ~.L.~
-to provide a method oE connecting a metallic member to a non-metallic member having relatively low compressive strength by magnetic pulse forming in such a r,lanner that damage to the non-metallic member is avoided.
These and other objects, advantages, and features will hereinafter appear, and for the purpose of illustration, but not of limitation, exemplary embodiments are illustrated in the accompanying drawings.
FIGURE 1 is a cross-sectional view of a high voltage fuse preferrea embodiment of the present invention.
FIGURE 2 is a partially fragmentary, partially cross-sectional view of the insulator housing of the preferred embodiment illustrated in FIGURE 1.
FIGURE 3 is an end view taken substantially along line 3~3 in FIGURE 2.
FIGURE 4 is a cross-sectional, partially fragmentary view of a portion of the end of the insulator housing.
FIGURE 5 is an end view of the end ferrule member of the preferred embodiment illustrated in FIGURE 1.
FIGURE 6 is a cross-sectional view taken sub-stantially along line 6-6 in FIGURE 5.
FIGURE 7 is a cross-sectional, partially fragmentary view showing the end ferrule member in position ready for magnetic pulse forming.
With reference to FIGURE 1, high voltage fuse 10 comprises hollow cylindrical insulator housing 12 of a suitable electrically insulating material such as glass reinforced epoxy resin. Mounted over each end of hollow cylindrical housing 12 in a manner more fully described hereinafter are metallic end ferrule members 1~. Mounted on end ferrule .~1 ,'`
~ ,. ...
~ D~
members 14 are a mounting stud 15 and a mounting spade 18 for connecting the fuse 10 in a high voltage electrical circuit. Mounted on the inside of housing 12 is a fusible element support assembly 20 which supports fusible elements 22 and 24. The exact construction of fusible element support assembly 20 does not form a part of the subject matter of the present invention and is more fully described in co~
pending Canadian patent application Serial No. 262,491 Schmunk, et al., entitled HIGH VOLTAGE FUSE AND METHOD OF
CONSTRUCTION THEREOF, filed October 1, 1976, and assigned to the same assignee as the present invention.
With reference to FIGURES 2, 3,and 4, housing 12 comprises an annular groove 26 formed around the exterior of housing 12 adjacent each end thereof. Also formed around the exterior edge of each end of housing 12 is a rabbet 28 in which an elastomer ring 30 is positioned. Rabbet 28 is dimen-sioned so that elastomer ring 30 ext~nds slightly beyond the end of housing 12 so that when end ferrule member 14 is positioned over the end of housing 12 and connected thereto a moisture-proof seal is formed between housing 12 and end ferrule member 1~.
With reference to FIGURES 5 and 6, end ferrule members 14 are initially fabricated to comprise an essentially flat circular end wall 32 and an annular flange 34 integrally formed to the flat circular end wall around the periphery thereof and extending approximately perpendicular from flat circular end wall 32, An opening 36 is provided through wall 32 for receiving the end of support assemhly 20 so that support assembly 20 may be welded to end ferrule members 14. In addition, another opening 38 may be provided through .~. -6 encl ferrule member to allow an electrically non-conducting filler material such as quartz sand to be inserted into fuse 10 after end ferrule members 14 have been mounted to the ends of housing 12. Opening 38 is then welded closed after the filler material has been inserted. A suitable mounting fixture such as mounting stud 16 of mounting stud 18 may be welded to the center of circular end wall 32 as illustrated in FIGWRE 1.
When fuse 10 is mounted in an electrical circuit, mechanical forces may be exerted on end wall 32 by mounting stud 16 and mounting spade lg. Further, when fuse 10 operates, fusible member 22 and 24 will rapidly vaporize causing an increase in gas pressure within the fuse 10.
Accor~ingly, end ferrule member 14 will e~perience stresses incident to both the mounting and operation of fuse 10.
To withstand these stresses, end wall 32 is fabricated so that i-t has a thickness Dl (see FIGURE 6) that is thick ; enough to withstand the stresses that will be applied to end wall 32. However, since housing 12 is typically formed o a glass reinforced epoxy resin material which has a relatively high tensile strength but a relatively low compres-sive strength, hollow cylindrical housing 12 is relatively fragile and could be damaged when end ferrule members 14 are compressed over the ends of housing 12. Accordingly, annular flange 34 is fabricated to have a thickness D2 which is less than the thickness Dl of circular end wall 32. Thickness D2 is selected so that flange B4 can be compressed by magnetic pulse forming without causing damage to housing 12.
End ferrule members 14 are attached to the end of : 30 housing 12 by magnetic pulse forming. With reference to --7~
! ~, i ~3~
FIGURE 7, an uncompressed end ferrule member 14 is shown positioned over the end of housing 12 with the magnetic pulse forming flux producing member 40 positioned immediately adjacent annular flange 34. Flux producing member 40 is a part of conventional magnetic pulse forming equipment that operates in the conventional manner to produce a short duration, high flux magnetic field which causes a compressive force to be applied to annular flange 34 to cause annular flange 34 to be compressed into annular groove 26 as illustrated in FIGURE 1.
~ lastomer ring 30 is placed in rabbet 28 before end ferrule member 14 is placed over the end of housing 12.
Elastomer ring 30 forms a seal between the housing 12 and the end ferrule member 14. To further facilitate the seal between the housing 12 and end ferrule member 14, the elastomer ring 30 may be coated with a vulcanizing sili-cone rubber material such as the vulcanizing silicone rubber material sold under the trademark SILASTIC, 732 RTV by the Dow Corning Co. This on-part vulcanizing silicone rubber acts to further assure that a moisture-proof seal is form~d between housing 12 and end ferrule member 14. This is particularly desirable where housing 12 is fabricated from a glass reinforced epoxy resin since it is difficult to machine a smooth rabbet 28 in such material that will provide a moisture-proof seal with elastomer ring 30. The vulcanizing silicone rubber material assures a moisture-proof seal despite possible roughness of rabbet 28.
Since housing 12 is not capable of wi~hstanding substantial compressive stresses~ the thickness D2 of annular flange 3~ must be sufficiently thin so that it "~,;3~
~.l 8 may be magnetically pulse formed around housing 12 without causing housing 12 to crack or be otherwise damaged.
However, since flat circular end wall 32 is not subject to magnetic pulse forming but is subjected to substantial mechanical stresses during mounting and fuse operation, the thickness Dl of circular end wall 32 may be made much thicker to withstand the mechanical stresses without jeopardizing the ability of the end ferrule member 14 to be magnetically pulse formed over the end of housing 12.
It should be apparent that the method and technique of attaching metallic end ferrule member 14 to the end of relatively fragile cylindrical housing 12 has applicability in a wide range of composite articles of manufacture wherein a metallic member must be attached to a relatively fragile non-metallic member by magnetic pulse forming. Thus, where a portion of the metallic member will experience mechanical stresses, that portion may be made substantially thick enough to withstand those mechanical forces provided that the portion of the metallic member which is compressed over the relatively ~ragile non-metallic member is made thin enough so that when the metallic member is compressed over the fragile member by magnetic pulse forming damage does not result to the fragile member.
Thus, it may be seen that a variety of metallic members may be mounted to a variety of relatively fragile non-metallic members by magnetic pulse forming utilizing the invention described herein without departing from the spirit and scope of the present invention as defined in the appended claims.
, ~ ".
Claims (11)
1. An electrical fuse comprising:
a cylindrical hollow housing formed of a non-metallic, electrically insulating material, said housing having opposite open ends, an annular recess formed adjacent each end of the exterior thereof, and an annular rabbet formed around the exterior edge of each end thereof and having an elastomer ring therein;
first and second metallic end members each comprising a circular end wall having a first thickness sufficient to withstand mechanical stress incident to mounting and operation of said fuse, and an annular flange formed integrally with said circular end wall along the edge thereof and extending approximately perpendicular thereto, said flange having a second thickness less than said first thickness;
said first and second members being positioned over the opposite open ends of said housing, said annular flanges being compressed into said annular recesses formed in said housing to attach and seal said first and second end members over the open ends of said housing and to seat said elastomer ring seats against said end members so that a moisture-proof seal is provided between said end members and said housing, said second thickness being thin enough to permit said annular flanges to be compressed by magnetic pulse forming without causing damage to said housing; and a current responsive element, connected between said first and second end members.
a cylindrical hollow housing formed of a non-metallic, electrically insulating material, said housing having opposite open ends, an annular recess formed adjacent each end of the exterior thereof, and an annular rabbet formed around the exterior edge of each end thereof and having an elastomer ring therein;
first and second metallic end members each comprising a circular end wall having a first thickness sufficient to withstand mechanical stress incident to mounting and operation of said fuse, and an annular flange formed integrally with said circular end wall along the edge thereof and extending approximately perpendicular thereto, said flange having a second thickness less than said first thickness;
said first and second members being positioned over the opposite open ends of said housing, said annular flanges being compressed into said annular recesses formed in said housing to attach and seal said first and second end members over the open ends of said housing and to seat said elastomer ring seats against said end members so that a moisture-proof seal is provided between said end members and said housing, said second thickness being thin enough to permit said annular flanges to be compressed by magnetic pulse forming without causing damage to said housing; and a current responsive element, connected between said first and second end members.
2. An electrical fuse, as claimed in Claim 1, wherein said elastomer ring is coated with a vulcanizing silicone rubber material.
3. An electrical fuse, as claimed in Claim 1, wherein said first end member has an opening therethrough for permitting insertion of an electrically non-conductive filler material into said fuse after said first and second end members are attached.
4. An electrical fuse, as claimed in Claim 1, wherein said first thickness is approximately twice said second thickness.
5. An electrical fuse, as claimed in Claim 1, wherein said first and second end members have mounting fixtures attached thereto.
6. An improved fuse of the type which includes a fusible element supported within an open-ended insulative housing, the housing having high tensile strength but relatively low compressive strength, wherein the improvement comprises:
a metallic ferrule for closing an open end of the housing, the ferrule including an end wall by which the fuse is mounted and which is shaped complementarily to the cross-section of the housing, and a flange which is thinner than the end wall and which is formed integrally with, and generally perpen-dicular to, the end wall, the flange being compressed against the periphery of the housing to maintain the end wall against the open end thereof, the relative thickness of the end wall and the flange being selected so that the end wall is capable of withstanding forces due to fuse mounting and fuse operation, and the flange is compressible by magnetic pulse forming against the housing without applying harmful compressive forces thereto;
a rabbet formed in an exterior edge at an end of the housing; and an elastomer member in the rabbet which is com-pressed by the ferrule to provide a seal between the ferrule and the housing.
a metallic ferrule for closing an open end of the housing, the ferrule including an end wall by which the fuse is mounted and which is shaped complementarily to the cross-section of the housing, and a flange which is thinner than the end wall and which is formed integrally with, and generally perpen-dicular to, the end wall, the flange being compressed against the periphery of the housing to maintain the end wall against the open end thereof, the relative thickness of the end wall and the flange being selected so that the end wall is capable of withstanding forces due to fuse mounting and fuse operation, and the flange is compressible by magnetic pulse forming against the housing without applying harmful compressive forces thereto;
a rabbet formed in an exterior edge at an end of the housing; and an elastomer member in the rabbet which is com-pressed by the ferrule to provide a seal between the ferrule and the housing.
7. The fuse of Claim 6, which further includes:
a groove formed in the exterior of the housing adjacent to, but spaced from, an end of the housing, a portion of the compressed flange being compressed into the groove.
a groove formed in the exterior of the housing adjacent to, but spaced from, an end of the housing, a portion of the compressed flange being compressed into the groove.
8. The fuse of Claim 7, wherein the groove is continuous about substantially the entire periphery of the housing.
9. The fuse of Claim 6, wherein the housing is generally cylindrical.
10. The fuse of Claim 6, wherein the rabbet is continuous about substantially the entire periphery of the housing end.
11. The fuse of Claim 10, wherein the housing is generally cylindrical.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/633,488 US4063208A (en) | 1975-11-19 | 1975-11-19 | Fuse housing end caps secured by magnetic pulse forming |
| US633,488 | 1975-11-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1094618A true CA1094618A (en) | 1981-01-27 |
Family
ID=24539835
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA262,492A Expired CA1094618A (en) | 1975-11-19 | 1976-10-01 | Fuse with housing end caps secured by magnetic pulse forming |
Country Status (2)
| Country | Link |
|---|---|
| US (1) | US4063208A (en) |
| CA (1) | CA1094618A (en) |
Families Citing this family (16)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4150353A (en) * | 1977-03-11 | 1979-04-17 | Mcgraw-Edison Company | Current limiting fuse |
| US4104604A (en) * | 1977-07-26 | 1978-08-01 | Gould Inc. | Narrowly knauled end cap for an electric fuse |
| US4158187A (en) * | 1977-08-05 | 1979-06-12 | Gould Inc. | Means for affixing ferrules to a fuse casing |
| DE2825669A1 (en) * | 1978-06-12 | 1979-12-13 | Vitus Hoegl | Fuse with insulating tube - whose ends are axis symmetrically deformed to provide grip for end cap |
| CA1137159A (en) * | 1979-04-23 | 1982-12-07 | John P. Dupont | Cap seal for resilient electrical housing |
| US4746381A (en) * | 1986-05-05 | 1988-05-24 | A. B. Chance Company | Method of making an end cap connection for a fluid-resistance electrical device |
| US4841356A (en) * | 1988-04-05 | 1989-06-20 | Brush Fuses, Inc. | Fuses and their manufacture |
| DE19602951C2 (en) * | 1996-01-27 | 2000-12-07 | Steingroever Magnet Physik | Method and device for expanding pipes or tubular parts by the magnetic field of a current pulse |
| US5671522A (en) * | 1996-01-29 | 1997-09-30 | Northrop Grumman Corporation | Method and apparatus for sealing a pressure vessel |
| US5966813A (en) * | 1997-12-23 | 1999-10-19 | Dana Corporation | Method for joining vehicle frame components |
| US6408515B1 (en) * | 1998-08-20 | 2002-06-25 | Dana Corporation | Method for manufacturing an engine cradle for a vehicle frame assembly |
| US6389697B1 (en) * | 2000-07-17 | 2002-05-21 | Fuel Cell Components And Integrators, Inc. | Fabricating automotive spaceframes using electromagnetic forming or magnetic pulse welding |
| US6688423B1 (en) * | 2000-11-03 | 2004-02-10 | Dana Corporation | Fluid-borne noise suppression |
| US7007362B2 (en) * | 2003-04-29 | 2006-03-07 | Torque-Tractiontechnologies, Inc. | Method of forming a slip joint |
| US20050168315A1 (en) * | 2004-01-30 | 2005-08-04 | Russel Brown | High capacity fuse and arc resistant end caps therefor |
| DE102005033212B4 (en) * | 2005-06-07 | 2007-04-19 | Siba Fuses Gmbh & Co. Kg | High voltage fuse |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3250879A (en) * | 1964-06-29 | 1966-05-10 | Chase Shawmut Co | Electric fuse comprising plug terminals having an improved seal and pinning means |
| US3313536A (en) * | 1965-02-01 | 1967-04-11 | Gen Motors Corp | Shock absorber |
| US3333336A (en) * | 1965-10-13 | 1967-08-01 | Westinghouse Electric Corp | Method of making a fuse by securing the terminals by magnetic forming |
| US3438115A (en) * | 1967-11-30 | 1969-04-15 | Union Carbide Corp | Method of making vacuum containers |
| US3529270A (en) * | 1968-05-13 | 1970-09-15 | Chase Shawmut Co | Electric high interrupting capacity fuse for low current ratings |
| US3848325A (en) * | 1972-05-01 | 1974-11-19 | C Bimba | Method for assembling body and end sections for fluid power cylinder |
| US3967228A (en) * | 1975-10-09 | 1976-06-29 | General Electric Company | Electric current limiting fuse having a filter disposed in one end cap |
-
1975
- 1975-11-19 US US05/633,488 patent/US4063208A/en not_active Expired - Lifetime
-
1976
- 1976-10-01 CA CA262,492A patent/CA1094618A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4063208A (en) | 1977-12-13 |
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| MKEX | Expiry | ||
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Effective date: 19980127 |