HAND TOOL AND METHOD FOR CUTTING PLASTIC FIBER OPTIC CABLE WITHOUT ERROR |
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申请号 | EP12810642.4 | 申请日 | 2012-06-26 | 公开(公告)号 | EP2729282B1 | 公开(公告)日 | 2016-11-30 |
申请人 | Elbex Video Ltd.; | 发明人 | ELBERBAUM, David; | ||||
摘要 | |||||||
权利要求 | |||||||
说明书全文 | 1. This invention is related to a disposable hand tool for cutting plastic optical fiber cable known as POF and to an hand tool with disposable cutting blade. There are not too many hand held cutting tools made for POF, mostly are small "in palm" sized plastic molded tool, including a thin blade or a razor in a range of 0.2∼0.5mm thick, comprising row of holes that fit the thickness of a commonly used single POF cable (such as 2.2mm diameter) or of a commonly used twin core POF cable with each of the twin cable diameter is 2.2mm. The cutters are all operating in a guillotine style wherein the POF cable is inserted into one of a single hole or twin holes and the blade or the razor is pushed toward the cable to cut it perpendicular to the cable length, providing smooth cut surface. To provide smooth cut without scratches, cracks or other deformed surfaces the blade's edge should be used only once per cut. This was proven time and again that the edge is damaged by the cut and when the blade's sharp edge is used more than once, the cuttings become unreliable. The repeated use of the sharp edge by cutting the POF through the same given hole is a cause for scratches, cracks and uneven surfaces of the core itself, moreover it creates residues of hanging whiskers of the core's cladding and of the cable protective cover, some of which may adhere onto the cut surface plane of the core. The optical characteristics and the performances of the plastic optical fiber (POF) cable are severely affected by the defects caused by the repeated use of the blade's edge and such repeated cuttings should be prevented. Literally all of the known disposable hand cutting tool provide only instruction and warning not to use the same hole twice, but do nothing to prevent a repeated cutting through the same hole. The warning is a failed solution, because users genuinely forget which of the holes is already used and unintentionally re-use the same hole. Some are searching for a solution and an hand tool for cutting POF by a blade with a mechanism for preventing repeated cutting by the same sharp edge portion is disclosed in Other hand tools for cleaving and cutting glass fiber cables of It is the object of the present invention to provide a disposable hand tool for cutting and terminating plastic optical fibre according to claim 1 and a method for cutting and terminating plastic optical fibre using a hand tool according to claim 6. The foregoing and other objects and features of the present invention will become apparent from the following description of the preferred embodiments of the invention with reference to the accompanying drawings, in which:
Shown in The selected blade for the preferred embodiment is the standard NT blade made of hard steel and having thickness of 0.25mm or 1/100". However, many different blade shapes, size or thicknesses can be used by simply modifying the blade holding shown in The blade holder 10 comprises four parts, all molded together into one piece 10. The four parts can be termed as top bar or blade holder 11, the bottom bar or cable insertion bar 12 and two springy rings 19A and 19B that hold the top bar 11 and bottom bar 12 apart, yet providing by their flexibility to press the bars all the way till they touch each other. The top bar includes a protruding structure 11A that serves two purposes, one is to hold the edge 13E of the blade in place and the other is to act as a structured guide for the up down press action, by sliding through the receptive cutout 12A. The structured guide 11A and the cutout 12A together ensure no horizontal shifting position when the two bars 11 and 12 are pressed all the way until they touch each other, or during the POF cutting that is explained later. The bottom bar or the cable insertion bar 12 further includes a row of circular holes 16 with each of the shown holes has a diameter to fit the POF cable that the hand tool is designed to cut. The diameter of the popular size POF is 2.2mm, but any circular cable diameter or non circular shapes can be provided by row of holes made to fit precisely the POF cable size and shape. The reference to POF is to an optical cable known as Plastic Fiber Optic. The POF plastic core PMMA is softer to cut in comparison with the silica or a glass base core of the known fiber optic cables and while the silica core must be polished and lapped, the POF need no further treatment if it is cut cleanly without scratches and or other deformation of its cut surface. For this reason the cutting hand tool of the POF of the present invention can be viewed as a cutting and/or termination tool for POF cables. This is why the cutting should not be permitted to repeat through the same hole 16. Even though it may be possible, for example, to cut several times the POF via the same hole with no scratches, there are no means to verify how many cuts can be made without damaging the sharp edge 13C of the blade in a given position. This is why it is necessary to limit the cut to only one per hole. The open ended access 17 is provided for cutting long pieces of POF cable 40, for example when it is cut from a spool 49 shown in The four studs 18-1 to 18-4 are protruding to fit the four corresponding recesses 28-A to 28-D of the cover 20 shown in It should be noted that though the springy rings are shown as molded parts connecting the two bars as a combination single part, this relates only to one preferred embodiment. The single part blade holder and/or the single part cover can be constructed of metal cast individual parts, or machined parts including such parts as spring and guides instead of the shown springy rings 19 or 29. Same applies to the top and bottom bars, they can be fabricated, or die casted, or made of plastic material and individually injected. Further the spring action described here is not necessary for the error free cutting process. The spring action is improving upon the performance of the hand tool, making it more convenient to use but the hand tool can operate by manual movement up-down with no springs or springy movements. The most significant other difference is the structure of the holes 26 which provide for retaining the residue cuts 42 of the terminated end of the POF cables 41 shown in The shown hole 26 is the inner hole of the cover 20. The outer side for the cover 20 in Therefore the attaching of the two, the blade holder 10 and the cover 20 including the blade 13 using the screws 38-1 to 38-4 or any other fasteners or fastening methods, including the methods discussed above will result in a cutting hand tool shown in The cutting hand tool 30 in The numeric showing the combined open ended access is 37, the numeric for retaining rear end holes are shown as 36A, the combined guides 11A and 21A are shown as 31A, the corresponding receptive cutouts 12A and 22A are shown as 32A and the combined springy rings are shown as 39A and 39B. Even in the event that a user is trying to force the POF piece 41 into the blocked hole 26 through the insert hole 36 the blade will push the inserted POF cable 41 back by acting as a thin divider between the retained residue cut 42 and the newly inserted POF cable 41. In the extreme when the user strongly pushes inwards the POF cable 41 and tries to cut it the blade may chip or otherwise damage the inserted cable 41 end, such that it will be obvious and recognizable to the user that he has inserted the POF piece 41 into a used hole. The shown transparent hand tool 40 is identical to the structure shown for the hand tool 30, however when different structures are adopted (not shown) for cutting hand tools, such as the top bar 31 and the bottom bar 32 are molded or otherwise individually constructed, for example with a spring and guide attaching the bars together, it is preferable to construct at least the bottom bar of such tool, comprising the inserting and the retaining holes in a transparent clear material for improving the viewing of the retained residue cuts and the cutting or the terminating process, thereby improving upon the error prevention during the working of the tool. For a cutting hand tool 30 in which its blade holder 10 and cover 20 are attached together by fasteners such as rivets, or attached by bond, or by other processes that prevent the disassembly of the hand tool, the cutting hand tool 30 becomes disposable, to be discarded after using all of its holes for cutting and terminating POF cables. Users that intentionally try to misuse the disposable hand tool 30 by attempts to remove the residue cuts 42 from their respective hole 26, using a pushing pin to force the cut 42 back through the hole 36 will fail. The hole 36 is sized to be precisely fit the size (diameter) of the POF cable. On the other hand the retaining hole 26 is structured to be very tight at its rear end, closer to the hole 36A and slightly loose at its entry 26. This serves two purposes, one is to hold firmly the retained cut piece 42 inside the hole 26 and the other is to make it extremely unlikely that the pushing back of the cut piece 42 will be in a "perfect" position to enter the tight size hole 36. After few attempts any one will give up the imaginary re-use of a low cost disposable cutting hand tool 30 or 40. The cutting hand tool 30 shown assembled in All other explanations and details referred to above in connection with the hand tool and the method for cutting plastic optical fiber cable without error applies to the cutting hand tools 50 and 60. Further the POF cable can be manufactured in a ribbon structures combining more than just two cores, shown as the POF cable 60. For such ribbon cables with, for example three or more cores, the insert holes 36 or 66 and the retaining holes 26, with the push back holes 36A or 66A can be redesigned and structured to accommodate such ribbons, this includes a universal cutting hand tool (not shown) made by combining different insert holes and retaining holes in different shapes, diameters, and combinations thereof, and not limited to a specific size cable as shown above for the cutting hand tool 30, 40, 50 or 60. It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the invention that are within the scope of the attached claims. |