Claims
- 1. A method of making plug-in fuse elements having different desired fuse ratings and each comprising a plug-in element including a pair of spaced confronting generally parallel terminal blade portions to be received by pressure clip terminals or the like, a pair of confronting current-carrying extensions projecting longitudinally from the inner ends of the pair of terminal blade portions and a fuse link portion interconnecting the current-carrying extensions, said method comprising the steps of providing substantially identical blank portions of fuse metal for forming fuse elements of different fuse ratings which blank portions are initially provided with portions of substantially identical reduced thickness and substantially identical width for plug-in fuse elements of different fuse ratings, blanking at least said portions of reduced thickness of each blank portion to leave a pair of spaced confronting general parallel terminal blade portions to be received by pressure clip terminals of the like and confronting current-carrying extensions projecting longitudinally from the inner end portions of each pair of terminal blade portions, the fuse elements of different ratings being obtained by blanking said longitudinally extending portions of reduced thickness to provide fuse-forming links of substantially different locations between the confronting portions of said current-carrying extensions where the heat dissipation characteristics thereof are substantially different.
- 2. The method of claim 1 wherein said blanking step forms in said blank portions of different ratings fuse-forming links of different configurations which include a configuration which is relatively straight and a configuration which is undulating.
- 3. The method of making plug-in fuse elements having different desired fuse ratings and each comprising a plug-in element including a pair of spaced confronting generally parallel terminal blade portions to be received by pressure clip terminals or the like, a pair of confronting current-carrying extensions projecting longitudinally from the inner ends of the pair of terminal blade portions and a fuse link portion interconnecting the current-carrying extensions, said method comprising the steps of providing substantially identical blank portions of fuse metal for forming fuse elements of different fuse ratings which blank portions are initially provided with portions of substantially identical reduced thickness and substantially identical width for a variety of desired fuse ratings, blanking said portions of reduced thickness of each blank portion to leave a pair of spaced confronting generally parallel terminal blade portion to be received by pressure clip terminals or the like and confronting current-carrying extensions projecting longitudinally from the inner end portions of each pair of terminal blade portions, the fuse elements of different ratings being obtained by blanking said portions of reduced thickness to provide fuse links of substantially different configurations between the confronting portions of said current-carrying extensions.
- 4. The method of claim 3 wherein said blanking step forms fuse links in the fuse elements of different ratings which have a configuration which is relatively straight and a configuration which is undulating.
- 5. The method of claim 3 wherein said blanking step forms fuse links in the fuse elements of different ratings which include a relatively U-shaped configuration and a repeatedly undulating configuration.
- 6. The method of claim 3 wherein said longitudinally extending portions of reduced thickness formed in said blank portions are continuous to extend the full length of said blank portion.
- 7. The method as defined in claim 3 wherein said blanking step for making fuse elements of different ratings in said identical portions of reduced thickness forms said fuse link portions with substantially different width dimensions.
- 8. The method as defined in claim 3 wherein said blanking step for making fuse elements of different ratings form fuse link portions with substantially different lengths.
- 9. The method as defined in claim 3 wherein said blanking step for making fuse elements of different ratings form fuse link portions with substantially different width and length dimensions.
- 10. The method as defined in claim 3 wherein said blank portions of reduced thickness are continuous over the length of the blank portions and are reduced by a step including decreasing the thickness from one side only of the blank.
- 11. The method of claim 3 wherein said fuse link portions of the fuse elements are too thin to maintain the integrity thereof, said blanking operation leaving a rigid web between each pair of terminal blade portions thereof, and the method includes the steps of securing between said current-carrying extensions insulating means which rigidly interconnects the same, at least said pair of terminal blade portions of the blank and said rigid web being outside of the insulating means, and blanking the exposed rigid web of fuse metal interconnecting the terminal blade portions.
- 12. A method of making plug-in fuse assemblies having different desired fuse ratings and each comprising a plug-in element including a plate-like body of fuse metal having a pair of spaced terminal blade portions to be received by pressure clip terminals or the like, current-carrying extensions at the inner ends of said pairs of terminal blade portions and fuse link portions of reduced thickness interconnecting the current-carrying extensions, said method comprising the steps of providing strips of fuse metal for forming fuse elements of different fuse ratings which strips are initially longitudinally provided throughout the lengths thereof with continuous portions of reduced thickness, sequentially advancing the continuous strips of fuse metal, blanking said portions of reduced thickness to leave at longitudinally spaced intervals in said strip spaced longitudinally extending interconnected pairs of terminal blade portions, and current-carrying extensions interconnected by fuse link portions of reduced thickness, the fuse elements of different ratings being obtained by forming said fuse link portions of different configurations and/or locations along the confronting margins of said pairs of current-carrying extensions, and severing completed plug-in elements from the end of each strip.
- 13. The method of making plug-in fuse assemblies having different desired fuse ratings and each comprising a plug-in element including a plate-like body having a pair of spaced terminal blade portions to be received by pressure clip terminals or the like, current-carrying extensions at the inner ends of said terminal blade portions and fuse link portions interconnecting the current-carrying extensions, and rigid insulating means interconnecting said current-carrying extensions and with the pair of terminal blade portions thereof extending outwardly from said insulating means, said method comprising the steps of providing strips of fuse metal for forming fuse elements of different fuse ratings which strips are initially longitudinally provided throughout their lengths with continuous portions of substantially identical reduced thickness and substantially identical width regardless of the desired fuse ratings, sequentially advancing the strips of fuse metal, blanking said strips of fuse metal to provide at spaced intervals in said strips longitudinally interconnected blanks containing pairs of laterally spaced terminal blade portions formed outside of said reduced thickness portions interconnected by rigid webs, current-carrying extensions at the ends of said pairs of terminal blade portions at least partially formed externally of said portions of reduced thickness and fuse link portions formed in said portions of reduced thickness, said interconnecting fuse link portions of reduced thickness for the fuse elements of different ratings being obtained by blanking said portions of reduced thickness in said strips of fuse metal which form the differently rated fuse elements so the fuse link portions have substantially different locations and/or configurations, severing the end blanks from the sequentially advanced strips of fuse metal, and anchoring to the current-carrying extensions of each end blank a rigid insulating means with the pair of terminal blade portions of the end blank and the rigid web outside of the insulating means, and blanking the rigid webs of each blank.
RELATED APPLICATIONS
This application deals with a method which is an improvement over that disclosed in copending application Ser. No. 692,040, filed June 2, 1976 which issued as U.S. Pat. No. 4,023,265 for Method of Making a Miniature Plug-In Fuse, and is a continuation-in-part of application Ser. No. 698,079, filed June 21, 1976 which issued as U.S. Pat. No. 4,023,264.
The principal object of this invention is to provide an improved method for making a plug-in fuse assembly preferably like the miniature plug-in fuse disclosed in U.S. Pat. No. 3,909,767, granted Sept. 30, 1975.
Briefly, this invention has to do with a method of making a plug-in fuse assembly like that disclosed in U.S. Pat. No. 3,909,767, granted Sept. 30, 1975, and which preferably comprises a plug-in element including a plate-like body of fuse metal having a pair of spaced confronting terminal blade portions to be received by pressure clip terminals in a mounting panel, current-carrying extensions at the inner end portions of the pair of terminal blade portions and a fuse link portion of reduced thickness interconnecting the current-carrying extensions, and an insulating body, preferably a synthetic plastic housing, anchored between the current-carrying extensions, with the pair of terminal blade portions thereof extending outwardly from the housing.
The preferred method of making such a plug-in fuse assembly comprises providing a blank of fuse metal which is blanked to form the pair of laterally spaced coplanar terminal blade portions current-carrying extensions thereof and the interconnecting fuse link portion generally of reduced thickness (although very high current rated fuses may not have fuse link portions of reduced thickness). When the fuse link portion thereof is very fragile, the blanking operation leaves a relatively rigid web between the terminal blade portions formed in the blank.
The synthetic plastic housing is then inserted over said blank of fuse metal so it terminates short of the transverse web and the blank of fuse metal is suitably secured in the synthetic plastic housing as by staking or other means so that it acts as a rigid insulating body connected between the current-carrying extensions and/or terminal blade portions of the partially enclosed plug-in fuse element. (While less desirable, the housing function for this body of insulation material can be eliminated so it acts only as a rigid support and, if desired, a convenient gripping surface for the plug-in fuse element.) Where used, the exposed transverse web of fuse metal interconnecting the exposed terminal blade portions of the blank is then blanked or otherwise removed to complete the formation of a housed plug-in fuse element whose exposed pair of terminal blade portions may be inserted into metal sockets or the like of a terminal strip.
For maximum mass production efficiency of the housed plug-in fuse element just described, the blank of fuse metal from which each plug-in fuse element is formed as preferably part of a long strip of fuse metal upon which various blanking operations are performed as the strip moves past various stamping stations. The individual plug-in fuse elements are not completely separated from the strip until just before or after the housing is applied thereto at the end of the strip.
One of the cost saving and size reducing aspects of the preferred method of making plug-in fuses just described is that each plug-in fuse element is a stamping made from a blank or strip of fuse metal, and a completely housed fuse results from merely enclosing the same in an insulating housing, so that the entire fuse assembly is formed of only two parts, and without any soldering operations required to connect a fuse link between the terminal portion of the fuse. The manufacturing costs are reduced to a minimum when various blanks form interconnected portions of a strip of fuse metal so that the strip acts as a carrier for the blanks as they are successively moved past stamping dies which carry out the blanking operations just described.
As disclosed in the aforementioned copending application Ser. No. 692,040 the portion of each blank from which the fuse link portions of reduced thickness is formed is a continuous band of reduced thickness extending between opposite margins thereof. Where the blanks are interconnected in a strip, the band of reduced thickness extends the full length of the strip. The different fuse ratings of the fuse link portions of the plug-in fuse elements as disclosed is selectively varied by varying the thickness of the band of reduced thickness from which the fuse link portions are stamped. Thus, a single blanking die configuration may be utilized for a number of different ratings of the plug-in fuse assemblies. However, this requires the making and stocking of a large inventory of many different fuse metal strips and blanks to be selectively used. In addition to being costly, it is difficult to maintain accurate dimension tolerances in such inventory of many different fuse metal strips and blanks. Furthermore, particularly in the plug-in fuse assemblies of low ampere ratings, the thickness of the fuse metal strips and blanks are quite small which make them fragile and pose problems in handling such strips and blanks and in blanking the blanks to provide the interconnecting fuse-forming link portions therein.
The aforementioned difficulties involved in the method of making the miniature plug-in fuses of the aforementioned copending application Ser. No. 692,040 are eliminated, or at least minimized, by the method of the instant invention. Here, the continuous bands of reduced thickness of the strips or blanks of fuse metal from which the fuse link portions of plug-in fuse elements having a variety of fuse rating are formed can have a fixed non-fragile thickness dimension. This is achieved by blanking the strips or blanks of fuse metal so that the fuse link portion of fixed reduced thickness dimension have widely varying locations, and/or configurations thereof. Thus, relatively low fuse ratings may be obtained by locating the fuse link portions at locations where heat conduction is at a minimum and/or by giving the same a thin, deeply undulating shape. The highest rated fuse would have a wide straight fuse link located at a point where heat conduction is at a maximum. By so doing, making and stocking of a large inventory of many different fuse metal strips and blanks covering a large range of fuse ratings is eliminated and costs are substantially reduced. Maintenance of accurate dimension tolerances is facilitated by the identically dimensioned strips and blanks. The identically dimensioned strips or blanks are readily handled and may be readily blanked without distortion or damage since the thickness dimensions of the central portions of the reduced thickness of the fuse metal strips and blanks may be maintained at a reasonable thickness affording strength thereto. The interconnecting fuse link portions remain strong and they are not overly fragile. While separate blanking dies are needed for each fuse rating, the costs thereof constitute initial tooling costs, as distinguished from ongoing material costs involved with the use of many different strips and blanks of fuse metal, so that the total costs for the manufacture of the plug-in fuse assemblies of this invention will be considerably less, particularly on a mass production basis, this in addition to better tolerance control and handling.
Further objects of this invention reside in the particular method steps and in the cooperative relationships between the method steps in making the aforementioned plug-in fuse assembly.
Other objects and advantages of this invention will become apparent to those skilled in the art upon reference to the accompanying specification, claims and drawings.
US Referenced Citations (7)
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 1,237,325 |
Jun 1960 |
FRX |
| 456,749 |
Jul 1968 |
CHX |
Continuation in Parts (1)
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Number |
Date |
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| Parent |
698079 |
Jun 1976 |
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Patent Grant
4099320
