Method and apparatus of polishing end surfaces of rod-shaped members

Abstract: In a method of polishing end surfaces of rod-shaped members in which the rod-shaped members 41 to 46 are mounted on a holder 3 and the respective tip ends of the rod-shaped members are polished while the respective tip ends of the rod-shaped members 41 to 46 are pressed against a polishing disc 2 disposed opposite the holder 3, the distances between the centre of the polishing disc 2 and the respective rod-shaped members 41 to 46 are made different from one another.

Description: The present invention relates to a method and apparatus of polishing end surfaces of rod-shaped members, which is suitable for polishing the respective end surfaces of a plurality of rod-shaped members at the same time, as per the preamble of claims 1 and 2. An example of such apparatus and method is disclosed by US 5 184 433 A. For example, in the case where end surfaces of rod-shaped members such as ferrules with optical fibres are required to be finished into a desired shape by polishing the end surfaces, conventionally, as shown in Fig. 5, a large number of ferrules 102 with optical fibres are fixed to a periphery 101 of a regular polygonal holder 100 by suitable means while leaving a space between the ferrules, and a relative trochoid curvilinear motion is caused in the state that the respective tip ends of the ferrules 102 with optical fibres are pressed against a polishing disc 103 disposed opposite the holder 100, whereby the respective tip ends of the ferrules 102 with optical fibres are polished. However, according to the conventional method as shown in Fig. 5, although end surfaces of a large number of rod-shaped members can be polished at the same time as shown in Fig. 6, only a specific portion near an outer circumference (indicated by oblique lines) of the polishing disc 103 is used, so that a large part of a polishing sheet is not used, thus the conventional method has a problem that an economical use of the polishing sheet cannot be attained. US 5184433 discloses a method and apparatus of polishing the end of an optical fibre that produces relative lateral movement between the end of the fibre and an abrasive surface of the fibre in which the angle of attack of the relative movement is changed. An object of the present invention is therefore to provide a method of polishing end surfaces of rod-shaped members in which the entire surface of a polishing sheet is uniformly used so that the lifetime of the polishing sheet can be elongated and running costs can be lowered. According to a first aspect of the present invention, there is provided a method of polishing end surfaces of rod-shaped members as per claim 1. According to a second aspect of the present invention, there is provided a polishing apparatus as per claim 2. According to this method and apparatus, it is avoided that the regions on the polishing disc used by the respective rod-shaped members become quite identical to one another, so that almost all the surface of the polishing disc can be used. An embodiment of the invention will now be described by way of example only, with reference to the accompanying diagrammatic figures, in which: Fig. 1 is a schematic structural view showing an example of a polishing apparatus for practising the method of the present invention; Fig. 2 is a sectional view showing a polishing disc shown in Fig. 1; Fig. 3 is an explanatory view for explaining an example of a method of mounting ferrules with optical fibres on a holder shown in Fig. 1; Fig. 4 is a view showing loci drawn by the tip ends of the ferrules with optical fibres on the polishing disc in the case of the mounting method shown in Fig. 3; Fig. 5 is a schematic structural view showing a conventional polishing apparatus; Fig. 6 is a view for explaining the state of use of a polishing disc by the conventional polishing apparatus shown in Fig. 5. An embodiment mode of the present invention will now be described in detail with reference to the drawings. Fig. 1 is a schematic structural view showing an embodiment mode of a polishing apparatus for practising the method of the present invention. In this embodiment, a polishing apparatus 1 is constructed as an apparatus for polishing the respective tip ends of a plurality of ferrules with optical fibres into spherical surfaces, and includes a circular polishing disc 2 and a holder (ferrule holder) 3 to be mounted by the ferrules with optical fibres. The polishing disc 2 has a well known structure as shown in Fig. 2 in detail that a relatively thick elastic plate 22 having elasticity like rubber is disposed on a board 21 made of a stiff material, and a polishing sheet 23 is bonded to the elastic plate 22. As the polishing surface, even if an abradant is applied to the board 21 instead of the elastic material, the same result can be obtained. Returning to Fig. 1, the polishing disc 2 is attached to a driving apparatus (not shown). On the other hand, a holder 3 formed as a long and narrow rectangular parallelopiped is fixed to a frame of the not shown driving apparatus by a suitable means so that the holder is aligned to be parallel with the polishing sheet 23 with a predetermined space therebetween. The not shown driving apparatus is a motion causing apparatus of a well known structure capable of causing a trochoid curvilinear motion in a plane parallel with a main surface 2A of the polishing disc 2. As a result, the relative trochoid curvilinear motion can be given between the polishing disc 2 and the holder 3. In order to finish the tip end portions of ferrules with optical fibres into a spherical surface by the relative trochoid curvilinear motion, a plurality of ferrules 41 to 46 with optical fibres are mounted on a peripheral surface 3A of the holder 3 by well known means so that the ferrules have a predetermined posture to be almost vertical to the polishing disc 2. Here, in order to effectively use the polishing sheet 23, the ferrules 41 to 46 with optical fibres are positioned so that the respective distances L1, L2, ... between the ferrules and the centre point C of the holder 3 are made different from one another (see Fig. 3) Thus, if the relative trochoid curvilinear motion is given between the polishing disc 2 and the holder 3 in the state that the respective tip ends of the ferrules 41 to 46 with optical fibres are pressed against the polishing sheet 23, there is generated a combined motion of rotating motion M1 with a centre axis of the polishing disc 2 as the centre and small circular motions M2 of the respective tip ends of the ferrules 41 to 46 with optical fibres. As a result, as shown in Fig. 4, on the polishing sheet 23 of the polishing disc 2, loci T1 to T6 drawn by the respective tip ends of the ferrules 41 to 46 with optical fibres do not overlap with one another, so that almost all the surface of the polishing sheet 23 can be used and the polishing sheet 23 can be extremely effectively used. Accordingly, the lifetime of the polishing sheet 23 can be greatly elongated as compared with the prior art, and the running costs can be greatly lowered. In the above described example, there is exemplified the case in which a rectangular parallelopiped mounting block having a rectangular plane shape is used as the holder. However, it is apparent from the above description that the holder may be formed into any shape as long as a plurality of ferrules with optical fibres can be mounted thereon so that the distances between the respective ferrules and the centre of the polishing disc are different from one another. Accordingly, it is not necessarily required that the centre of the holder should coincide with the centre of the polishing disc. Further, in the example shown in Fig. 4, although the loci T1 to T6 do not overlap with one another, the method according to the present invention is not limited to this example, and the respective loci may partially overlap with one another as long as the distances between the respective rod-shaped members and the centre of the polishing disc are different from one another. Similarly, the rod shaped members could be arranged in groups having the same distance from the centre of the polishing disc with the distances of the respective groups being different such that although the loci of each group overlapped, the loci of different groups partially overlapped or did not overlap and almost all of the surface of the polishing sheet can be used. According to the present invention, as described above, since the distances between the respective rod-shaped members and the centre of a polishing disc are made different from one another, it is possible to avoid that only a specific portion of the polishing disc is concentrically used. As a result, it is possible to use almost all the surface of the polishing disc, so that the lifetime of the polishing disc can be elongated and the running costs can be decreased. The aforegoing description has been given by way of example only.

Claims: A method of polishing end surfaces of rod-shaped members (41-46) comprising: mounting a plurality of the rod-shaped members on a holder (3); and causing a relative trochoid curvilinear motion between the holder (3) and a polishing disc (2) disposed opposite the holder (3) while respective tip ends of the rod-shaped members (41-46) are pressed against the polishing disc (2) so that the respective tip ends of the rod-shaped members are polished, characterised in that : distances between a centre of the holder (3) and the respective rod-shaped members (41-46) are made different from one another; and (2) said relative trochoid curvilinear motion is caused by rotating the disc (2) and imparting a constant orbital motion to the center of the holder. A polishing apparatus comprising: a holder (3) for mounting a plurality of rod-shaped members (41-46); and a polishing disc (2) disposed opposite the holder (3) and adapted for trochoid curvilinear motion relative to the holder (3) while respective tip ends of the rod-shaped members (41-46) are pressed against the polishing disc (2) for polishing the respective tip ends of the rod-shaped members, characterised in that : the holder (3) is adapted for mounting the rod-shaped members (41-46) such that distances between the a centre of the holder (3) and the respective rod-shaped members (41-46) are different from one another; and the polishing disc (2) is adapted to be rotated and the center of the holder (3) is adapted to be moved with a constant orbital motion for causing said relative trochoid curvilinear motion.

Inventors: KAWASAKI MUNEO, MINAMI KOUJI, SUZUKI NOBUO, TOKITA HIROYUKI, KAWASAKI, MUNEO, MINAMI, KOUJI, SUZUKI, NOBUO, TOKITA, HIROYUKI, Kawasaki, Muneo, c/o Nasutekku Precision Co., Ltd., Minami, Kouji, c/o Nasutekku Precision Co., Ltd., Suzuki, Nobuo, c/o Nasutekku Precision Co., Ltd., Tokita, Hiroyuki c/o Nasutekku Precision Co., Ltd.
Applicants: SEIKO INSTR INC, SEIKO INSTRUMENTS INC.
Application year: 1997
Main classification: B24B19
IPC codes: G02B6, B24B19