Equipment for grinding optical fiber end

A device for grinding and polishing optical fiber ends. The device includes a holder and an elastic grinding surface. The holder is used to hold equidistantly a set of optical fibers such that the ends of the optical fibers are in contact with the elastic grinding surface capable of only eccentric rotation, to enable the grinding speed and the grinding direction of each of the optical fiber ends to be the same. The grinding direction is uniformly changed along with the change in time and the grinding angles in all direction are substantially the same.

FIELD OF THE INVENTION

The present invention relates generally to an equipment for grinding the ends of optical fibers, and more particularly to a grinding motion mode enabling instantly the grinding speed and grinding direction of the end of each optical fiber to be equal.

BACKGROUND OF THE INVENTION

As far as the current or future communication technology is concerned, the optical fiber communication is an indispensable tool. Like the cable communication system in which the signal cable and the signal connector are joined together, the optical fiber communication involves the use of the optical fiber connector. In the process of forming the optical fiber connector, an optical fiber is put through the hole of a ring such that the optical fiber is attached to the ring by an adhesive. The ring is made of a plastic, glass, or ceramic material. The end of the optical fiber attached to the ring is pressured on an elastic grinding surface and is then treated with a preliminary grinding process, a precision grinding process, and a polishing process, thereby resulting in the formation of a convex spherical face. The convex spherical face must be devoid of any defect. The optic axis of the convex spherical face may be parallel to the center line of the optical fiber or may form a small angle along with the center line of the optical fiber. The current grinding technology of the optical fiber end is basically evolved from the grinding technology of the optical lens. The manual grinding technology was followed by the machine grinding technology as illustrated in FIG.1. Such a conventional method for grinding an optical lens involves the use of a grinding tray10, which is provided with a grinding surface of cast iron in the course of the preliminary grinding and the precision grinding. The grinding tray10is provided with a grinding surface of asphalt or other polishing materials in the course of the polishing. In the grinding and the polishing processes, the grinding powders and the polishing powders of various grain densities are used along with water. The conventional method also involves the use of a workpiece holder to which a grinding workpiece assembly2is attached. The assembly2may be moved leftward and rightward in a reciprocating manner. The assembly2may be stationary. In case of an appropriate movement, the grinding surface in its entirety may be able to maintain a constant curvature due to the uniform wear. If the grinding surface is turned counterclockwise at ω angular speed, the workpiece assembly is also caused to turn counterclockwise by virtue of frictional force. In the absence of a special arrangement, these two angular speeds will not be equal to each other. At the conclusion of the preliminary grinding and the precision grinding, curvature of the lens is almost in line with the requirement. The workpiece is finally polished in such a manner that the polishing is done from the fringe of the workpiece toward the central part of the workpiece, and that curvature of the workpiece conforms to specifications. The grinding process and the polishing process may last as long as thirty minutes. As far as the conventional method for grinding the optical lens is concerned, the wear is greater at the fringes of the workpiece than at the inner part of the workpiece.

The grinding technology of the optical fiber end was developed two decades ago from the conventional method for grinding the optical lens. The grinding process of the optical fiber end is carried out in such a manner that the optical fiber is attached to the ring, and the holder of the optical fiber end must be stationary. In light of the relative motion of the workpiece and the grinding tray of the conventional method for grinding the optical lens, the grinding surface must be caused to engage in a movement or rotation of other form in relation to the optical fiber end holder in addition to its self-revolution, as shown in the U.S. Pat. Nos. 4,831,784; 4,905,415; 4,979,334; and 5,458,531. The most commonly-used grinding tray movement is illustrated inFIG. 2in which the reference numerals3,4, and5denote respectively an optical fiber end holder, self-revolution of a grinding surface, eccentric rotation of the grinding surface. The prior art methods for grinding the optical fiber end are technically similar to the conventional method for grinding the optical lens such that the wear is greater at the fringe of the optical fiber end than the inner part of the optical fiber end.

The precision grinding and the polishing of the optical fiber end are done on an elastic grinding surface, as illustrated inFIG. 3in which the reference numerals7,8, and9denote respectively a workpiece, a pressure, and an elastic grinding surface. The elastic grinding surface9is exerted on by the pressure8such that the elastic grinding surface9is caused to have a depression by means of which the workpiece7is so shaped as to have a convex surface. In view of the fact that the workpiece to be shaped by the elastic grinding surface is relatively small in size, the time that is required for the preliminary grinding, the precision grinding and the polishing lasts less than thirty seconds, which are considerably short as compared with the conventional method for grinding the optical lens. It is therefore necessary that all optical fiber ends held by the holder must be subjected to the same grinding strength in a relatively short period of time. In other words, the optical fiber ends are located at positions which are equal in grinding strength to one another. For example, twelve optical fiber ends are arranged along the circumference of a round holder such that all optical fiber ends are exerted on by the same pressure, thereby resulting in the shaping of all optical fiber ends in a uniform manner. Such a control method is respectively disclosed in the U.S. Pat. Nos. 6,039,630; and 6,077,154. These prior art methods are limited in design in that the optical fiber end holder can accommodate only a few optical fiber ends, and that they are not suitable for use in mass production.

SUMMARY OF THE INVENTION

The primary objective of the present invention is to provide an equipment for shaping at the same time a plurality of workpiece ends such that the workpiece ends are provided with a convex surface. The equipment of the present invention comprises a workpiece end holder, an elastic grinding surface, a driving device, and a pressure device.

The workpiece end holder is designed to hold a plurality of workpiece ends such that the workpiece ends are substantially equal in height with reference to a horizontal plane of the holder.

The elastic grinding surface is used to grind and polish the workpiece ends.

The driving device is used to drive the holder or the elastic grinding surface to engage in an eccentric rotation of a constant orientation.

The pressure device is used to provide a predetermined pressure under which the workpiece ends are kept in contact with the elastic grinding surface throughout the time that the workpiece ends are being ground or polished by the elastic grinding surface.

Preferably, the equipment of the present invention further comprises one or more elastic grinding surfaces in addition to the elastic grinding surface whereby the elastic grinding surfaces are used to grind or polish the workpiece ends in conformity with various specifications, with the elastic grinding surfaces being driven by the driving device to engage in an eccentric rotation in a constant orientation such that the elastic grinding surfaces come in contact with the workpiece ends one after another under the same or different pressure provided by the pressure device.

Preferably, the equipment of the present invention further comprises one or more cleansing devices for cleansing the workpiece ends at the time when the workpiece ends are disengaged with the elastic grinding surfaces. Preferably, the cleansing devices are brushing surfaces, ultrasonic cleansing devices, or a combination of the brushing surfaces and the ultrasonic cleansing devices.

Preferably, the cleansing devices are elastic brushing surfaces, whereby the elastic brushing surfaces form with the elastic grinding surfaces a tape-shaped element such that the elastic brushing surfaces and the elastic grinding surfaces are serially arranged at intervals.

Preferably, the equipment of the present invention further comprises a grinding tray to which the elastic grinding surface is attached such that the grinding tray and the elastic grinding surface are driven at the same time by the driving device to engage in the eccentric rotation in the constant orientation.

Preferably, the holder and the elastic grinding surface are driven by the driving device to engage in the eccentric rotation at different speeds and in the constant orientation.

Preferably, the elastic grinding surface is driven to engage in a linear reciprocating motion.

Preferably, the elastic grinding surface is driven to engage in a linear reciprocating motion.

Preferably, the holder is driven to engage in a linear reciprocating motion.

Preferably, the holder and the elastic grinding surface are driven to engage in a linear reciprocating motion in different directions.

Preferably, the elastic grinding surface is provided with a plurality of holes, wherein the holes are uniformly arranged and have a hole diameter ranging between 0.1 mm and 4.0 mm.

Preferably, the elastic grinding surface and the grinding tray are provided at a center thereof with a center hole with a diameter ranging between 0.1 mm and 4.0 cm, wherein the center hole of the grinding tray does not penetrate through the grinding tray.

Preferably, the equipment of the present invention further comprises a vacuum suction system corresponding in location to the grinding tray, wherein the grinding tray is provided with a plurality of holes ranging in diameter from 0.1 mm to 4.0 mm, and the vacuum suction system is for removing grinding chips and grinding fluid, and for holding the elastic grinding surface by providing suction to the plurality of holes of the grinding tray.

Preferably, the equipment of the present invention further comprises a plurality of add-on elastic grinding surfaces, and a plurality of add-on holders identical to the holder, with some of the add-on holders or all of the add-on elastic grinding surfaces being driven by the driving device to engage in the eccentric rotation in the constant orientation such that a plurality of workpiece ends held by some of the add-on holders are kept in contact at the same time with the add-on elastic grinding surfaces under a predetermined pressure provided by the pressure device, thereby enabling the workpiece ends to be ground or polished in various degrees.

Preferably, the add-on elastic grinding surfaces comprise an elastic tape on which a grinding material or a polishing material is disposed, wherein the elastic tape is wound at both ends on two reels.

Preferably, the equipment of the present invention further comprises a plurality of cleansing devices for cleansing the workpiece ends, the cleansing devices being arranged at intervals along with the add-on elastic grinding surfaces thereby enabling the workpiece ends held by other portion of the add-on holders to be cleansed at the same time by the cleansing devices during the time that the workpiece ends held by the some of the add-on holders are being ground or polished.

Preferably, the equipment of the present invention further comprises a conveyer for transporting all of said holders such that the holders move past one after another all of the elastic grinding surfaces and all of the cleansing devices.

Preferably, the equipment of the present invention further comprises a conveyer for transporting intermittently all of the elastic grinding surfaces and all of the cleansing devices such that all of the elastic grinding surfaces and all of the cleansing devices move past one after another all of said holders.

Preferably, the equipment of the present invention further comprises a grinding tray on which all of the elastic grinding surfaces are disposed whereby said grinding tray and the elastic grinding surfaces are driven by the driving device to engage synchronously in the eccentric rotation in the constant orientation.

Preferably, the driving device drives portion of the holders and all of the elastic grinding surfaces to engage in the eccentric rotation at various speeds and in the constant orientation.

Preferably, the equipment of the present invention further comprises a grinding tray on which all of the elastic grinding surfaces and all of the cleansing devices are disposed, wherein the grinding tray is driven by the driving device to engage in the eccentric rotation in the constant orientation.

Preferably, all of the elastic grinding surfaces are provided with a plurality of holes ranging in diameter between 0.1 mm and 4.0 mm.

Preferably, all of the elastic grinding surfaces and the grinding tray are provided at a center thereof with a center trench ranging in width from 1 mm to 4 cm, wherein the center trench of said grinding tray does not penetrate through the grinding tray.

Preferably, the equipment of the present invention further comprises a plurality of containers, wherein the containers are disposed on the grinding tray such that all of the elastic grinding surfaces are held in the containers, with the containers serving to collect grinding chips and grinding fluids.

Preferably, the equipment of the present invention further comprises a plurality of containers, wherein the containers are disposed on the grinding tray such that all of the elastic grinding surfaces and all of the cleansing devices are held in the containers, with the containers serving to collect grinding chips, grinding fluids, and cleansing wastes.

The features, functions, and advantages of the present invention will be more readily understood upon a thoughtful deliberation of the following detailed description of the present invention with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a grinding equipment with a grinding motion mode enabling a plurality of ground optic fiber ends to be instantaneously equal to one another in grinding speed and grinding direction. The grinding directions of the optic fiber ends are uniformly changed along with a change in time. In other words, the grinding equipment of the present invention is capable of a uniform grinding level in all directions.

A mathematical analysis of the grinding motion of the prior art is first completed with reference toFIGS. 2 and 4.

As shown inFIG. 4, the XY Cartesian coordinates of the optical fiber holder of the prior art is stationary, with O being an original point of the stationary coordinates or a center point of optical fiber holder. The r1line represents a line connecting the center point O and a given point on the optical fiber holder. In other words, r1represents the position of an optical fiber end to be ground, with its coordinate point being (X1, Y1). O′ is the center of a circle around which the grinding surface is engaged in the self-revolution. R stands for a distance between the O point and the O′ point. θ is the angle of the eccentric rotation at time t. φ is the angle of the self-revolution of the grinding surface at time t. O′ is the original point of the x′y′ coordinates of the eccentric rotation of the grinding surface while the grinding surface direction remains unchanged.

(x″, y″) is a given point on the grinding surface. If t=0, θ=0, and φ=0. At time t, (x1, y1), (x′, y′) and (x″, y″) are on the same point. First of all, ask for the relationship of (x1, y1) and (x″, y″) along with the time change.x′′=x′⁢cos⁢⁢ϕ+y′⁢sin⁢⁢ϕy′′=-x′⁢sin⁢⁢ϕ+y′⁢cos⁢⁢ϕ}(1)x′=x1-R⁢⁢cos⁢⁢θy′=y1-R⁢⁢sin⁢⁢θ}(2)

If equation (2) is substituted into equation (1), an equation (3) is obtained as follows:x′′=(x1-R⁢⁢cos⁢⁢θ)⁢cos⁢⁢ϕ+(y1-R⁢⁢sin⁢⁢θ)⁢sin⁢⁢ϕy′′=(y1-R⁢⁢cos⁢⁢θ)⁢sin⁢⁢ϕ+(y1-R⁢⁢sin⁢⁢θ)⁢cos⁢⁢ϕ}(3)

If the angular speed of the eccentric rotation of the grinding surfaceⅆθⅆt=θ.
and the angular speed of the self-revolutionⅆφⅆt=ϕ.
are constant, the above equation may be written as follows:x′′=(x1-R⁢⁢cos⁢⁢θ.⁢t)⁢cos⁢ϕ.⁢t+(y1-R⁢⁢sin⁢⁢θ.⁢t)⁢sin⁢ϕ.⁢ty′′=(x1-R⁢⁢cos⁢⁢θ.⁢t)⁢sin⁢ϕ.⁢t+(y1-R⁢⁢sin⁢⁢θ.⁢t)⁢cos⁢ϕ.⁢t}(4)

In view of the fact that {dot over (θ)} and {dot over (φ)} are constant values, x1and y1are also constant values, thereforeⅆx′′ⅆt=⁢x.′′=-ϕ.⁢sin⁢ϕ.⁢t⁡(x1-R⁢⁢cos⁢θ.⁢t)+(R⁢θ.)⁢cos⁢ϕ.⁢t⁢⁢sin⁢θ.⁢t+⁢ϕ.⁢cos⁢ϕ.⁢t⁡(y1-R⁢⁢sin⁢θ.⁢t)-R⁢θ.⁢sin⁢ϕ.⁢t⁢⁢cos⁢θ.⁢t(5)ⅆy′′ⅆt=⁢y.′′=-ϕ.⁢cos⁢ϕ.⁢t⁡(x1-R⁢⁢cos⁢θ.⁢t)-(R⁢θ.)⁢sin⁢ϕ.⁢t⁢⁢sin⁢θ.⁢t+⁢ϕ.⁢sin⁢ϕ.⁢t⁡(y1-R⁢⁢sin⁢θ.⁢t)-R⁢θ.⁢cos⁢ϕ.⁢t⁢⁢cos⁢θ.⁢t(6)

In view of the fact that (x″, y″) are coordinates of a point on the grinding surface at the time t, which is coincident on a point (x1,y1) on the optical fiber end holder, and that(ⅆx′′ⅆt,ⅆy′′ⅆt)
is differential of this point coordinate relative to time,(-ⅆx′′ⅆt,-ⅆy′′ⅆt)
is the instantaneous speed of a point on the grinding surface which is on the point (x1, y1) of the optical fiber end holder at the time t.

The following equation (7) is derived from the above equation (5).(x*″)2=⁢ϕ*2⁢sin2⁢ϕ*⁢⁢t⁡(x-R⁢⁢cos⁢⁢θ*⁢⁢t)2+(R⁢⁢θ*)2⁢ϕ*⁢⁢t⁢⁢sin2⁢⁢θ*⁢⁢t⁢⁢cos2⁢ϕ*⁢⁢t+⁢ϕ*2⁢cos2⁢ϕ*⁢⁢t⁡(y1-R⁢⁢sin⁢⁢θ*⁢⁢t)2+(R⁢⁢θ*)2⁢sin2⁢ϕ*⁢⁢t⁢⁢cos2⁢⁢θ*⁢⁢t-⁢2⁢⁢ϕ*⁢⁢R⁢⁢θ*⁢⁢sin⁢⁢ϕ*⁢⁢t⁢⁢cos⁢⁢ϕ*⁢⁢t⁢⁢(x1-R⁢⁢cos⁢⁢θ*⁢⁢t)⁢⁢sin⁢⁢θ*⁢⁢t-⁢2⁢ϕ*2⁢sin⁢⁢ϕ*⁢⁢t⁢⁢cos⁢⁢ϕ*⁢⁢t⁡(x1-R⁢⁢cos⁢⁢θ*⁢⁢t)⁢(y1-R⁢⁢sin⁢⁢θ*⁢⁢t)+⁢2⁢ϕ*⁢R⁢⁢θ*⁢⁢sin2⁢ϕ*⁢⁢t⁡(x1-R⁢⁢cos⁢⁢θ*⁢⁢t)⁢cos⁢⁢θ*⁢t+⁢2⁢⁢ϕ*⁢⁢R⁢⁢θ*⁢cos2⁢ϕ*⁢⁢t⁢⁢sin⁢⁢θ*⁢⁢t⁡(y1-R⁢⁢sin⁢⁢θ*⁢⁢t)-⁢2⁢(R⁢⁢θ*)2⁢sin⁢⁢ϕ*⁢⁢t⁢⁢cos⁢⁢ϕ*⁢⁢t⁢⁢sin⁢⁢θ*⁢t⁢⁢cos⁢⁢θ*⁢t-⁢2⁢ϕ*⁢⁢R⁢θ*⁢sin⁢⁢ϕ*⁢⁢t⁢⁢cos⁢⁢ϕ*⁢⁢t⁡(y1-R⁢⁢sin⁢θ*⁢⁢t)⁢cos⁢⁢θ*⁢⁢t⁢(7)

Average ({dot over (x)}″)2in relation to time. In light of the averages of sin {dot over (θ)} t, cos {dot over (θ)} t, sin {dot over (φ)} t, and cos {dot over (φ)} t being zero in relation to time, the odd orders of sine, cosine of the equation (7) are zero in relation to time. As a result, equation (8) is obtained as follows:(x*″)2_=⁢ϕ*2⁢sin2⁢ϕ*⁢⁢t⁡(x1-R⁢⁢cos⁢⁢θ*⁢⁢t)2+(R⁢⁢θ*)2⁢cos2⁢ϕ*⁢⁢t⁢⁢sin2⁢θ*⁢⁢t+⁢ϕ*2⁢cos2⁢ϕ*⁢⁢t⁡(y1-R⁢⁢sin⁢⁢θ⁢*⁢t)2+(R⁢⁢θ*)2⁢sin2⁢ϕ*⁢⁢t⁢⁢cos2⁢θ*⁢⁢t-⁢2⁢⁢ϕ*⁢⁢R2⁢θ⁢*⁢sin2⁢ϕ*⁢⁢t⁢⁢cos2⁢θ*⁢⁢t-2⁢ϕ*⁢⁢R2⁢θ⁢*⁢cos2⁢ϕ*⁢⁢t⁢⁢sin2⁢θ⁢*⁢t(8)
Similarly, equation (9) is obtained as follows:(y*″)2_=⁢ϕ*2⁢cos2⁢ϕ*⁢⁢t⁡(x1-R⁢⁢cos⁢⁢θ*⁢⁢t)2+(R⁢⁢θ*)2⁢sin2⁢ϕ*⁢⁢t⁢⁢sin2⁢θ*⁢⁢t+⁢ϕ*2⁢sin2⁢ϕ*⁢⁢t⁡(y1-R⁢⁢sin⁢⁢θ⁢*⁢t)2+(R⁢⁢θ*)2⁢cos2⁢ϕ*⁢⁢t⁢⁢cos2⁢θ*⁢⁢t-⁢2⁢⁢ϕ*⁢⁢R2⁢θ⁢*⁢cos2⁢ϕ*⁢⁢t⁢⁢cos2⁢θ*⁢⁢t-2⁢ϕ*⁢⁢R2⁢θ⁢*⁢sin2⁢θ*⁢⁢t⁢⁢sin2⁢θ*⁢⁢t(9)

The square of the average speed of the point (x″,y″) on the grinding surface passing the point (x1, y1) on the optical fiber end holder is therefore as follows:(x*″)2_+(y*″)2_=⁢(x*″)2_+(y*″)2_=⁢ϕ*2⁡(sin2⁢ϕ*⁢⁢t+cos2⁢ϕ*⁢⁢t)⁢(x1-R⁢⁢cos⁢⁢θ*⁢⁢t)2+⁢(R⁢θ*)2⁢(sin2⁢ϕ*⁢⁢t+cos2⁢ϕ*⁢⁢t)⁢sin2⁢θ*⁢t+⁢ϕ*2⁡(sin2⁢ϕ*⁢⁢t+cos2⁢ϕ*⁢⁢t)⁢(y1-R⁢⁢sin⁢⁢θ*⁢⁢t)2+⁢(R⁢⁢θ*)2⁢(sin2⁢ϕ*⁢⁢t+cos2⁢ϕ*⁢⁢t)⁢cos2⁢θ*⁢⁢t-⁢2⁢⁢ϕ*⁢⁢R2⁢θ*⁡(sin2⁢ϕ*⁢⁢t+cos2⁢ϕ*⁢⁢t)⁢cos2⁢θ*⁢⁢t-⁢2⁢ϕ*⁢⁢R2⁢θ*⁡(sin2⁢ϕ*⁢⁢t+cos2⁢ϕ*⁢⁢t)⁢sin2⁢θ*⁢⁢t=⁢ϕ*2⁡(x1-R⁢⁢cos⁢⁢θ*⁢t)2+ϕ*2⁡(y1-R⁢⁢sin⁢⁢θ*⁢t)2+⁢(R⁢⁢θ*)2⁢(sin2⁢θ*⁢t+cos2⁢θ*⁢⁢t)-⁢2⁢⁢ϕ*⁢R2⁢θ*⁡(sin2⁢θ*⁢⁢t+cos2⁢θ*⁢t)=⁢ϕ*2⁡(x12+y12)+ϕ*2⁢R2-2⁢ϕ*⁢⁢x1⁢R⁢⁢cos⁢θ*⁢⁢t-⁢2⁢⁢ϕ*⁢⁢y1⁢R⁢⁢sin⁢θ*⁢⁢t+(R⁢⁢θ*)2-2⁢⁢ϕ*⁢R2⁢θ*(10)
Because of the averages of cos {dot over (θ)} t and sin {dot over (θ)} t being zero in relation to time, equation (11) is obtained as follows:x.′′2+y.′′2=⁢ϕ.2⁢r12+ϕ.2⁢R2+θ.2⁢R2-2⁢ϕ.⁢R2⁢θ.=⁢r12⁢ϕ.2+R2⁡(ϕ.-θ.)2(11)

The first item on the right side of the equal sign of the above equation (11) is related to the position of the optical fiber end holder, with the second item being irrelevant to the position of the optical fiber end holder. {dot over (φ)} is angular speed of self-revolution and {dot over (θ)} is angular speed of eccentric rotation of the grinding surface.

According to the above equation (11), when the angular speed of the self-revolution of the grinding surface becomes greater, the degree of the grinding on various points on the optical fiber end holder becomes less uniform. In other words, the self-revolution of the grinding surface is apt to have an adverse effect on the grinding uniformity of various points of the optical fiber end holder. However, the grinding degree is uniform on all points which are equal on r1. That is to say that the grinding degree is uniform on all points of the circumference of a circle whose center is the center point of the eccentric rotation. For this reason, the conventional grinding method calls for the arrangement of all optical fiber ends on the circumference of the optical fiber end holder.

If {dot over (φ)}=0, {dot over (θ)}≠0, the grinding surface is capable of eccentric rotation and is incapable of self-revolution.

The following equation (12) is derived from the equations (5) and (6).x.′′=R⁢θ.⁢sin⁢θ.⁢t=-(x⁢⁢direction⁢⁢component⁢⁢of⁢⁢each⁢⁢point⁢velocity⁢⁢of⁢⁢grinding⁢⁢surface)y.′′=R⁢θ.⁢cos⁢θ.⁢t=-(y⁢⁢direction⁢⁢component⁢⁢of⁢⁢each⁢⁢point⁢velocity⁢⁢of⁢⁢grinding⁢⁢surface)}(12)

The following equation (13) is derived from the above equation (12).
(({dot over (x)}″)2+({dot over (y)}″)2)1/2=R{dot over (θ)}  (13)

According to the above equations (12) and (13), all points of the grinding surface are instantaneously engaged in a motion in the same direction and at the same speed R {dot over (θ)}. The direction is changed 360° at the constant speed along with time, with the angular speed being {dot over (θ)}.

In light of the optical fiber ends being arranged in the circumference of a holder, the grinding operation is done in a small-scale manner. Such a technical handicap is shared by all grinding operations in which all workpieces are forced to make contact with an elastic grinding surface so as to form a convex surface on the workpieces. For example, the optical fiber connector, GRIN lens of the optical fiber communication, and the magnetic read/write head can not be produced in a large-scale. operation.

The above technical limitation can be overcome by controlling the pressure by which the workplaces are forced to make contact with the grinding surface, and by controlling the grinding surface in such a manner that the speed of the self-revolution of the grinding surface is reduced to zero or a value much smaller than the speed of the eccentric rotation of the grinding surface. In the case of the grinding method as shown inFIG. 2, the technical limitation can be overcome by adjusting the motor speed in such a way that the angular speed of self-revolution is reduced to zero or almost zero. However, the speed adjustment is a time-consuming chore and must be done only by an experienced technician. In other words, a superior mechanical design should not call for such an adjustment and should provide means to enable the grinding tray to engage in only eccentric rotation, thereby making a mass production possible.

As shown inFIG. 5, the grinding equipment of the first preferred embodiment of the present invention comprises a grinding surface9, a grinding tray10, a transmission wheel11by which the grinding tray10is caused to engage in an eccentric rotation, and two gears12and13. The second gear13is driven by the motor so as to actuate the first gear12, thereby enabling the transmission wheel11to turn to actuate the grinding tray10to engage in the eccentric rotation. As shown inFIG. 6, three transmission wheels turn at a constant speed and in the same direction, so as to enable the grinding tray to engage in only the eccentric rotation.

As shown inFIGS. 7 and 9, the grinding equipment of the second preferred embodiment of the present invention comprises an eccentric transmission wheel15, a grinding surface16, a grinding tray17, a base25, with18,19,20,21being a mechanical assembly for stopping the self-revolution of the grinding tray17. As shown inFIG. 8, the mechanical assembly contains a movable linear ball guide rod18, a guide rod fastening seat19, a fixed linear ball guide rod20and a horizontal straight line ball bearing21. A grinding tray fastening seat23is used for fastening the grinding tray17and the movable linear ball guide rod18together. A longitudinal straight line ball bearing22and the horizontal straight line ball bearing21are joined together by a linear bearing fastening seat24such that they are perpendicular to each other. Depending on the circumstance, the grinding tray may be provided with a plurality of the constant direction assemblies. In addition, when the eccentric rotation speed is too fast, the other side of the eccentric rotation is provided with a sufficient weight to compensate the rotational stability so as to prevent vibration.

Another technical consideration is the problem of the wear uniformity of the grinding surface. If certain portions of the grinding tray are incapable of grinding the ends in the grinding process, while other portions of the grinding tray are kept grinding the ends of the workpieces, there will be a substantial consumption of the material and a high rejection rate of the product.

A shown inFIG. 10, L is a grinding tray diameter. R is the radius of a circle around which the grinding tray is engaged in the eccentric rotation. The optical fiber end holder can be held only in the O area of the inclined line, or in a circle having a diameter of L-2R. The optical fiber end holder has a diameter l and is held in the fringe of the inclined line area. With l≦L/2, the center to (L/2 −) of the grinding surface are not being ground. The extent of wear from (L/2−l) to L/2 is proportional tocos-1⁡(4⁢x2+(L-l)2-l24⁢x⁡(L-l))π(14)
wherein x is a distance between a given position on the grinding surface and the center point of the grinding surface. The different positions on the grinding surface are different in wear. In the grinding process, if the grinding tray10or the optical fiber holder is provided with a linear reciprocating motion, as shown inFIG. 11, the wear of the grinding surface will be more uniform. With respect to the speed of the eccentric rotation, the linear reciprocating motion speed is small and negligible. Another consideration is the relationship between the optical fibers distribution interval on the end holder and the eccentric rotational radius of the grinding tray. Each optical fiber end encircles a fixed point serving as a center of a circle with a radius R from the view of the grinding tray, as shown in FIG.12. If the optical fiber interval is D, D is greater than 2R, as shown inFIG. 12, only a portion of the grinding surface is being ground. If D<2R, as shown inFIG. 13, the grinding surface is uniformly ground.

If the entire operational flow is carried out on a machine, the grinding surfaces of various grain densities must be used throughout the entire operational flow. As a result, the operation can not be easily automated. Since the end holder is stationary while the grinding process is carried out by the grinding surface which is engaged in the eccentric rotation along with the grinding tray in the present invention, a long elastic strap is designed, as shown in FIG.14. The long elastic strap is provided with a plurality of portions different in grain density for preliminary grinding, precision grinding, and polishing. As shown inFIG. 14,9is the grinding surface,28is the brushing surface, and29represents portions having various functions. The grinding surfaces of various grain densities are separated by the brushing surface. The elastic grinding surface9is rolled into two cylindrical bodies, as shown inFIG. 15, with the middle portion passing a grinding tray10to grind the optical fiber ends which are held by a holder3. The grinding tray is provided with a vacuum means to attract the elastic grinding surface. Each time when the grinding surfaces of different grain densities are replaced, the motor is used to draw out of the spools to facilitate the replacing of the grinding surfaces. Located between the two grinding surfaces of different grain densities is a brushing surface. The motor is mounted at the side of the grinding tray such that the motor is in motion along with the grinding tray.

As shown inFIG. 16, the grinding tray10is of a long striplike structure and is capable of only eccentric rotation in a constant direction. The different positions of the grinding tray are provided with the grinding surfaces9of various grain densities, and a brushing surface28located between the two grinding surfaces, or an ultrasonic cleansing bath. A plurality of optical fibers are moved through the grinding surface9, and the brushing surface28or ultrasonic cleansing bath, thereby resulting in the grinding, the cleansing, and the polishing of the optical fiber ends. Preferably, twelve optical fibers are held by a holder. Since each sanding paper can only be used to grind about ten times. This slows down the mass grinding operation. For this reason, we design the reel-type elastic grinding surfaces which are provided with various grinding surfaces of various grain densities and are located at one side of the rectangular grinding tray10, and other reels serve to wind the worn-out grinding surface at the other side thereof, such that the grinding surface9can be rolled out across the grinding tray10, as shown in FIG.17. Depending on the wear condition, the other reel is driven by the motor to replace the grinding surface9. In light of the grinding surface9of the present invention being capable of only the eccentric rotation, the motor, the reels, and the elastic surface and the grinding tray10are linked together.

As shown inFIGS. 16 and 17, the continuous grinding process of the optical fiber end involves the preliminary grinding, the precision grinding, the polishing, and the cleansing. In each process, the holder3is exerted on by different pressure and is therefore provided with an adjustable pressure device8. The holder3may be movable or fixed. In the event that the holder3is fixed, the grinding tray10is movable.

The elastic grinding surface may be so changed that it is rigid to grind a planar mirror, a diamond mirror, or a planar optical fiber end. The wear of the grinding surface is uneven. At the outset, the grinding surface is planar. After a while, the grinding surface becomes recessed, thereby resulting in an increase in rejection rate in mass production. The remedial measure is to correct the grinding tray after a certain period of time or after a predetermined number of workpiece certain period of time or after a predetermined number of workpiece is processed, depending on the actual operational condition. The correction method involves the use of a heavy and rigid standard plane as a workpiece, which is placed on the grinding tray to proceed with the grinding. This correction process is done for a few times to planarize the grinding surface.

If the working areas of various grain densities are well partitioned, the conventional grinding material may be used in place of sand paper. The grinding material is a mixture of water and grinding powders different in graininess. It must be noted here that the grinding materials different in graininess must not be contaminated one another. The quality of the grinding will be seriously undermined by such contamination. The large granules are especially harmful to the optical fiber end which is being polished. We design the flow direction of the grinding fluid forward the preliminary grinding from the precision grinding. In addition, we deepen the trench for guiding the flow of the grinding fluid. In each cleansing process, the grinding material and the grinding chips are thoroughly removed from the optical fiber ends as well as the optical fiber holder.

Another task must be taken into consideration. This has to do with the removal of the grinding chips of the optical fiber ends. In the case of the conventional optical lens, if the grinding surface is asphalt, the failure to remove chips often results in difficulty for polishing the center of the optical lens. As a result, the grinding surface is often provided with trenches and a cavity located at the center of the grinding surface. The cavity and the trenches serve to store the chips which are removed from the workpiece, thereby enabling the grinding fluid to flow freely on the grinding surface without being obstructed by the chips.

In the grinding of the optical fiber ends, the optical fiber ends are held around an outer circumference of a holder. As a result, the removal of the grinding chips poses no problem at all. However, if the optical fiber ends are uniformly arranged in the holder, the removal of the grinding chips will be a problem. Under this circumstance, the grinding surface must be punched or provided with trenches. If the grinding tray is round, the optical fiber end holder must be round accordingly. The grinding tray10is provided at the center with a recess, as shown in FIG.18. In addition, the grinding surface9is uniformly provided with larger holes as shown by the dotted lines. The grinding tray10is uniformly provided with smaller but denser holes, which are shown by the dotted lines. The grinding fluid is removed by suction under the grinding tray in the direction indicated by an arrow in FIG.18.

The vacuum suction is intended to hold the grinding surface9and to remove the grinding fluid and the grinding chips. For this reason, the holes of the grinding tray10must be small enough to avoid adverse effect on the flatness of the grinding surface9. The holes of the grinding tray10must be also large enough to prevent the clogging by the grinding powder and the workplace chips. The density of the holes of the grinding tray10must be appropriate such that any large hole of the grinding surface9must include the smaller hole of the grinding tray. In the meantime, the large hole of the grinding surface9must not be so large as to affect the grinding uniformity. The continuous grinding process, as shown inFIGS. 16 and 17, is more complicated in removing the grinding fluid and the grinding chips, wherein a middle trench is designed. The formation of the middle trench in the equipment shown inFIG. 16is easier. The formation of the middle trench in the equipment shown inFIG. 17is difficult. The present invention provides the following modular design in which a grinding unit9A is first designed, as shown inFIG. 19, and in which a cleansing unit28A is also designed, as shown in FIG.20. Thereafter, a number of grinding units9A and the cleansing units28A are placed on a large planar surface10′ which undergoes eccentric rotation in a constant orientation, as shown in FIG.21. There are only three grinding units and three cleansing units in FIG.21. The number of the grinding unit and the cleansing unit depends on the operational requirement. The grinding unit9A ofFIG. 19is provided with the middle trench, with the grinding surface and the grinding tray being punched in accordance with the method described with reference to FIG.18. The removal of air, grinding fluid, and grinding chips is done by vacuum suction in the direction indicated by an arrow. As shown inFIG. 21, the optical fiber end holder3is rectangular. In view of the fact that each grinding unit9A and each cleansing unit28A are provided in the middle with a trench, the optical fiber ends must be held by the holder3in such a manner that the optical fiber ends should not obstruct the trenches.

The operation of the grinding of the optical fiber ends is done in a series of processes, such as preliminary grinding, cleansing, precision grinding, cleansing, polishing, and cleansing.

In the grinding process, caution must be exercised to prevent a grinding fluid of large granule from being mixed with a grinding fluid of small granule. In other words, these two grinding fluids must be carefully isolated. The present invention suggests that each grinding unit and each cleansing unit are kept in a case50, as shown inFIGS. 22,23, and24.

As shown inFIG. 22, a durable grinding surface9B is free of the middle trench and is not replaced frequently. As shown inFIG. 23, a nondurable grinding surface9is free of the middle trench and is replaced often. As shown inFIG. 24, a cleansing surface28is free of the middle trench. Similar to the way illustrated inFIG. 21, they are placed on a large planar surface10′ which undergoes a eccentric rotation in a constant orientation and, thereby making them ready for grinding operation, as shown in FIG.25.

As shown inFIGS. 26,27,28, and29, the designs are basically similar to those which are described above with reference toFIGS. 22-25, with the difference being that the former are provided with a middle trench on the grinding surface and the cleaning surface of each grinding unit and cleansing unit.

As shown inFIGS. 25-29, the continuous grinding equipments of the present invention are provided with the grinding unit in which the used grinding fluid is collected, discharged, or recycled. In addition, they are provided with the cleansing unit in which the used water is collected and discharged.