JP2005103669A - Recessed end surface machining method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a recessed end surface machining method and device for grinding, and polishing by machining with free abrasive grains swirling along with a grinding wheel, with high accuracy with the free abrasive grains easily supplied and hardly dissipated. <P>SOLUTION: A workpiece 2 is fixed to a rotating shaft tip 3a, and the bar-like grinding wheel 7 is controlled in a Z-axis 4, an X-axis 5 and a B-axis 14a to grind a workpiece end face into predetermined recessed face shape. The grinding wheel is moved again in an escape direction to have a predetermined space, and a polishing fluid 10 which is a magnetic fluid containing free abrasive grains, is supplied into a clearance 9 between the workpiece end face 2a and the grinding wheel. High-speed accelerating force is applied to the polishing fluid, which is the magnetic fluid containing the free abrasive grains, by the grinding wheel to perform polishing by swirling along with the grinding wheel. In this case, magnetic forces 16, 17 are arranged in the diagonal direction of the recessed end face to perform polishing while supplying the recessed end face with the polishing fluid which is the magnetic fluid containing the free abrasive gains. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for processing a concave end surface, which grinds an end surface of a work having a concave end surface such as a free-form surface such as an ultra-precision mold for optical parts, and performs polishing using a grindstone used for grinding. .

  Although a die is processed by grinding with an ultra-precision processing machine such as an aspherical surface or a free-form surface processing machine, there is a problem that the surface roughness of the workpiece is insufficient for use as an optical component. Conventionally, in order to improve the surface roughness of the mold, a mold that has been ground with an ultra-precision processing machine is mounted on a polishing machine and polished to improve the surface roughness of the mold. . At present, however, the aspherical and free-form surface molds have a higher precision in the required shape of the mold, and a deep shape and a complicated curvature distribution shape are required. For this reason, the polishing machine performs polishing of the mold by a function of controlling the surface pressure of the polishing head to be constant or controlling the direction of the polishing (polishing) head in accordance with the processing surface. However, since the mold shape is complicated and deep, the surface pressure is kept constant in consideration of the tilt of the workpiece surface, and the direction of the polishing head is controlled in accordance with the workpiece surface. It has become difficult.

  On the other hand, a mold with high required accuracy is subjected to grinding processing, and then polishing processing → shape measurement → polishing processing is repeatedly performed to improve the shape and surface roughness of the mold. However, in order to add a polishing function to an ultra-precision grinding machine, it is necessary to mount both a grindstone spindle and a polisher head, or to attach and detach a grinding head and a polisher head. In this case, in the case of a small-diameter grinding machine, it is necessary to mount the tool on the tool rotation axis (B axis), but if both are mounted, there are problems such as an increase in machine size and stroke. Further, when the grinding head and the polisher head are attached / detached, there is a problem that it is difficult to attach / detach the grinding head and the shape error due to the attachment / detachment of the grinding head is small, and it is difficult to attach / detach.

Therefore, the thing of patent document 1 is processing of the end face of an optical fiber connector, but from rough processing to finishing processing is processed into a predetermined shape by grinding using a grinding means using a cup grindstone. A minute gap is provided between them, and free abrasive grains are polished in the minute gap by a follow-up process using a cup grindstone, and grinding and polishing are processed in a continuous process. As shown in FIG. 5, in this spinning process, the loose abrasive grains 21 in the machining liquid 20 are accelerated by the cup grindstone 22 rotating at high speed and collide with the end surface 23a of the connector 23 being worked, so that the cup grindstone is in a non-contact state. Processing. This non-contact machining has very little damage to the workpiece. If the workpiece is held for an appropriate time, the non-contact machining is performed only by the non-contact machining using the free abrasive grains 21, and a clean end face machining is possible. Moreover, in patent document 2, the cutting | disconnection and end surface grinding | polishing of a rod-shaped material are performed by the accompanying grinding process of the free abrasive grain by a disk-shaped rigid body. Further, in Patent Document 3, loose abrasive grains are interposed between the R portion of the turbine blade and the R portion of the ceramic disk having a hardness higher than that of the turbine blade. However, in this case, the abrasive grains are pressed against the turbine blade side, which is different from the rotation processing in Patent Documents 1 and 2.
JP-A-9-248750 Japanese Patent Publication No. 6-047228 JP-A-6-31358

  However, the thing of patent document 1 only presses the workpiece surface of a predetermined angle with respect to a cup grindstone surface, grinds it, makes it a fixed clearance, and supplies a free abrasive grain, and is restricted to a simple shape. Moreover, the thing of patent document 2 is only transferred to the planar shape of a grindstone, and can process only a plane. Moreover, since the thing of patent document 3 presses an abrasive grain, the favorable surface like patent documents 1 and 2 cannot be obtained. In addition, there is no suggestion or disclosure about the application to the free-form surface processing such as the lens mold described above for the follow-up processing or similar processing by the free abrasive grains.

  Furthermore, since it is necessary to draw loose abrasive grains between the processed surface and the grinding wheel, it can be performed only in a convex shape as in Patent Literature 1 or in a planar shape as in Patent Literature 2. For this reason, the follow-up process or the similar process using such loose abrasive grains is not applied to the processing of the concave surface such as the lens mold described above. Further, the free abrasive grains may be held in the concave surface with the end face facing upward, but in this case, the replacement of the abrasive grains is not stable, and a uniform surface cannot always be obtained. Further, when the processing end face is directed upward, there is a problem that the processing apparatus becomes large and complicated. Furthermore, loose abrasive grains are easily dissipated by acceleration by a grinding wheel, and the periphery of the processed part is soiled, which is not preferable for a high-precision machine.

  In view of the above-described problems, an object of the present invention is to provide a concave end face processing method and apparatus capable of performing grinding processing by a grinding wheel and polishing by concave end face processing of the grinding wheel and loose abrasive grains by concave end face processing. It is. It is another object of the present invention to provide a method and apparatus for processing a concave end face that is easy to supplement loose abrasive grains and has high accuracy, and in which loose abrasive grains are difficult to dissipate.

  In the present invention, a workpiece is fixed to the tip of the rotating shaft, and a rod-shaped grinding wheel rotating around the grinding wheel axis is arranged in the same Z-axis direction as the rotating shaft, the X-axis direction perpendicular to the rotating shaft, the Z and After moving around the rotation axis B axis perpendicular to the X axis and grinding the workpiece end surface into a predetermined concave shape, the predetermined concave shape locus of the grinding wheel is a predetermined interval in the escape direction. And the polishing liquid of the free abrasive-containing magnetic fluid is supplied to the gap between the workpiece end surface processed into the concave shape and the grinding wheel to the polishing liquid of the free abrasive-containing magnetic fluid A method of forming a concave end surface on the workpiece end surface by applying a high-speed acceleration force by a grinding wheel to form a concave end surface on the workpiece end surface, and arranging a magnetic force in a diagonal direction of the concave end surface, Polishing fluid for magnetic fluid containing abrasive grains It has solved the above problems by providing a concave end surface processing method of polishing while trapped in the concave end face.

  That is, as a method for improving the grinding and surface roughness of an aspheric lens mold and a free-form lens mold, grinding is performed with a grindstone spindle mounted on an ultra-precision machining machine to finish the shape of the end face of the mold. Next, the shape of the machined mold is measured to determine the shape error of the mold. Then, an NC program is created such that the clearance between the grindstone and the workpiece has a predetermined value with respect to the ground surface (the feed speed may be set according to the shape error). After grinding, a magnet and an electromagnet are disposed on the outer periphery of the workpiece or the outer periphery of the grindstone. Thereby, the polishing liquid using the magnetic fluid containing free abrasive grains is allowed to stay on the workpiece surface. In this state, the grinding wheel spindle is rotated to rotate the polishing fluid of the free fluid containing the free abrasive grains around the periphery of the grinding wheel, and the workpiece surface is polished by the flow of polishing fluid (free abrasive grains) flowing between the workpiece and the grinding stone. Is done. The polishing liquid is not supplemented entirely by magnetic force, but flows away due to the polishing liquid supplied later, gravity, and acceleration force caused by the rotation of the grindstone, so that the free whetstone is appropriately replaced. Further, the amount of the polishing liquid supplemented with the loose abrasive-containing magnetic fluid at the concave end surface is controlled by the supply amount from the nozzle and the strength of the magnetic force.

  As an apparatus for carrying out such a method, in the invention according to claim 2, a rotating shaft to which a workpiece is fixed at the tip, a rod-shaped grinding wheel, a grinding wheel shaft on which a rod-shaped grinding wheel is rotatably provided, A grindstone shaft is mounted and can move relatively around the Z-axis direction in the same direction as the rotation axis, the X-axis direction perpendicular to the rotation axis, and the rotation axis B-axis perpendicular to the Z and X axes. Means capable of controlling the trajectory of the grinding wheel again so that there is a predetermined gap between the tool mounting portion and the ground end surface, and free abrasive-grain-containing magnets between the concave end surface and the bar-shaped grinding wheel. What is necessary is just to set it as the concave end surface processing apparatus which has the nozzle which supplies the polishing liquid of a fluid, and the magnet or electromagnet which generate | occur | produces a magnetic force in the diagonal direction of the said concave end surface. If the processing tip of the rod-shaped grinding wheel is cylindrical and the end surface is processed at the corner, the clearance between the processing end surface and the corner can be reduced, and the other parts can be processed. Since the gap becomes sufficiently large, the influence of loose abrasive grains is small. Highly accurate polishing is possible.

  According to the present invention, the loose abrasive grains of the magnetic fluid are held on the concave end surface by the magnetic force provided in the diagonal direction of the concave end surface, so that the free curved surface of the mold such as a lens or the concave end surface such as an aspherical surface or a spherical surface In the processing, the present invention provides a polishing method and apparatus by grinding with a grinding wheel and accompanying processing of the grinding wheel and loose abrasive grains. High-precision processing is possible because polishing can be performed by follow-up processing. Further, since the free abrasive grains can be supplemented by the magnetic force, the polishing liquid of the free abrasive-containing magnetic fluid is difficult to dissipate. In addition, the required accuracy of the mold shape is high, and even for aspherical and free-form optical component molds with deep and complex shapes, grinding using the grindstone and grindstone spindle as it is Therefore, the surface roughness of the processed surface can be improved. In addition, the grindstone used in the polishing process has a dress effect due to the action of the free abrasive-containing magnetic fluid with the polishing liquid, and an effect of recovering the sharpness of the grindstone.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a plan view of a concave end surface processing apparatus showing an embodiment of the present invention, FIG. 2 is a side view of the same, FIG. 3 shows the relationship between a workpiece and a grinding wheel, and an enlarged cross section when a magnetic field is arranged vertically. FIG. 4 is a plan view and FIG. 4 is a side view when the magnetic field is arranged in the lateral (processing) direction. 1 and 2, the concave end surface processing apparatus 1 has a work table 12 movable in the Z-axis 4 direction and a tool table 13 movable in the direction perpendicular to the Z-axis (X-axis 5) on the base 6. The rotating shaft 3 is provided on the work table 12 in the same direction as the Z axis. The workpiece 2 is attached to the end 3a of the rotary shaft 3, and the workpiece is rotatable around the rotary shaft. On the tool table 13, there is provided a turning stage 14 which can be turned around a B axis 14b which is a turning axis perpendicular to the table surface 13a, and a tool mounting portion 15 is provided on the turning stage 14a. A rod-shaped grinding wheel 7 is attached so as to be rotatable about the grinding wheel shaft 7a. The grinding wheel 7 is formed in a columnar shape, and serves as a processing tip portion for processing the workpiece end surface by moving the corner portion 7b of the cylindrical outer surface with respect to the workpiece end surface 2a. An axis 7 a of the grinding wheel 7 is parallel to the base surface 6 a, is tilted with respect to the rotating shaft 3, and has the same height as the rotating shaft 3. Fluid bearings and high-precision rolling bearings are used to feed the rotary shaft 3, work table 12, tool table 13, swivel stage 14, and grindstone shaft 7a, and the X axis 5, Z axis 4, and swivel axis 14b. Is controlled with high precision by NC control using a servo motor, enabling ultra-precision aspherical processing. The rotary shaft 3 and the grindstone shaft 7a are also preferably NC controlled. Although NC control may be performed in the vertical direction, it is necessary to control at least the X, Z, and B axes. In addition, the code | symbol 8 shown with a dotted line in FIG. 1 is a probe contact-type measuring instrument for a measurement, is attached whenever needed during a process, and measures a workpiece end surface shape.

  In particular, in the present invention, during the polishing process, as shown in FIG. 3, the polishing solution 10 of the magnetic fluid containing free abrasive grains can be supplied to the gap 9 between the concave end surface 2 a of the work 3 and the corner 7 b of the grinding wheel 7. Nozzle 11 is provided on. In addition, electromagnets 16 and 17 are provided on the upper and lower sides of the concave end surface in a diagonal direction, respectively, and a magnetic field is formed with the N pole on the upper side and the S pole on the lower side. As for the polishing liquid, the electromagnet may be arranged in the lateral direction as shown in FIG. The magnetic field of the electromagnet supplements the polishing fluid 10 of the magnetic fluid containing free abrasive grains. A tray 18 is provided below the workpiece end surface, and receives the polishing liquid of the magnetic fluid containing free abrasive grains falling downward, and returns it to a polishing liquid tank (not shown). The workpiece end surface 2a is ground by rotating the rotary shaft 3, the Z axis 4, the X axis 5, the B axis 14b, and the grindstone shaft 7a to perform concave end surface grinding. At the time of polishing, a predetermined gap 9 is formed between the ground end face 2a and the corner 7b (the relief direction of the recessed end face), for example, a gap of several nm (nanometer) to several micrometers (micrometer). The trajectory of the corner portion 7b of the grinding wheel can be controlled again while maintaining the above.

  In such a concave end surface processing apparatus, first, the workpiece 2 is attached to the end surface 3a of the rotating shaft 3, and the concave surface of the workpiece end surface is ground by the corner portion 7b using the rod-shaped grindstone 7. The grinding workpiece 2 is subjected to shape measurement using a shape measuring device 8 mounted on the machine. The NC for polishing is controlled so that the gap 9 between the corner 7b of the bar-shaped grindstone 7 and the concave end surface 2a of the workpiece 2 becomes a predetermined value with respect to the locus finished by grinding. On the other hand, electromagnets 16 and 17 are installed on the outer periphery of the workpiece, and the polishing fluid 10 of the free abrasive-containing magnetic fluid whose temperature is adjusted is supplied from the nozzle 11. When the abrasive fluid 10 containing free abrasive grains containing the electromagnets 16 and 17 is supplied, a sufficient amount of the abrasive fluid containing free abrasive grains stays on the surface of the workpiece. The spindle of the grindstone shaft 7a is rotated, and the axis is moved by the NC program so that a predetermined gap is formed between the corner 7b of the grindstone 7 and the concave end surface 2a of the workpiece 2. As a result, the polishing liquid 10 of the magnetic fluid containing free abrasive grains rotates with the rotation of the rod-shaped grindstone, and the polishing effect is obtained at the location where the free abrasive grains hit the workpiece concave end surface 2a. Surface roughness is improved. The rotational speed of the rod-shaped grindstone 7 and the size of the loose abrasive grains are the speed (for example, several thousand to several tens of thousands of revolutions) and the size (0. Needless to say, 1 to 0.5 μm) and abrasive material (ultrafine silica) are selected as appropriate. Further, in the embodiment, a rod-shaped grindstone having a columnar outer surface corner at the tip has been described, but the rod-shaped grindstone is a cylindrical shape, a columnar shape, a cylinder having a different external shape, or a step in which columnar grindstones are connected in the axial direction. Various shapes such as attachments are possible. Furthermore, it cannot be overemphasized that it can apply to the processing method and apparatus by a shaping | molding grindstone and other various grindstones.

It is a top view of the concave end surface processing apparatus which shows embodiment of this invention. It is a side view of the concave end surface processing apparatus which shows embodiment of this invention. It is an expanded section top view at the time of arranging the magnetic field in the up-and-down direction, showing the relation between the work and the grinding stone showing the embodiment of the present invention. It is an expanded sectional side view at the time of arranging the magnetic field in the transverse (working) direction, showing the relationship between the workpiece and the grinding wheel showing the embodiment of the present invention. It is explanatory drawing of grinding | polishing by the accompanying process by a grinding wheel and a loose abrasive grain.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Concave end surface processing apparatus 2 Work piece 2a Work piece end surface (concave end surface)
DESCRIPTION OF SYMBOLS 3 Rotating shaft 3a Tip of rotating shaft 4 Z-axis 5 X-axis 7 Rod-shaped grinding wheel 7a Grinding wheel shaft 9 Clearance 10 Polishing liquid of magnetic fluid containing free abrasive grains 11 Nozzle 14b B-axis 15 Tool mounting portion 16, 17 Magnet or electromagnet

Claims (2)

  A workpiece is fixed to the tip of the rotating shaft, and a rod-shaped grinding wheel rotating around the wheel axis is rotated in the same Z-axis direction as the rotating shaft, in the X-axis direction perpendicular to the rotating shaft, and in the direction perpendicular to the Z and X axes. After the workpiece end surface is ground into a predetermined concave shape, the trajectory of the predetermined concave shape of the grinding wheel is moved again at a predetermined interval in the clearance direction. In addition, the polishing fluid of the magnetic fluid containing free abrasive grains is supplied to the gap between the workpiece end surface processed into the concave shape and the grinding wheel, and the polishing fluid of the free abrasive containing magnetic fluid is accelerated at high speed by the grinding stone. A method of forming a concave end surface on the workpiece end surface by applying a force to the grinding wheel along with the grinding wheel, wherein magnetic force is arranged in a diagonal direction of the concave end surface, and the free abrasive-containing magnetic fluid The polishing liquid is supplemented to the concave end surface. Concave end surface processing method characterized by polishing while. A rotating shaft to which a workpiece is fixed at the tip, a rod-shaped grinding wheel, a grindstone shaft on which a rod-shaped grinding wheel is rotatably provided, and the grindstone shaft are mounted and relatively Z in the same direction as the rotating shaft A predetermined distance is provided between the tool mounting portion that is movable in the axial direction, the X-axis direction perpendicular to the rotation axis, the rotation axis B-axis perpendicular to the Z and X axes, and the ground end surface that has been ground. Means capable of controlling the trajectory of the grinding wheel again so as to form a gap of the following, a nozzle for supplying a polishing liquid of magnetic fluid containing free abrasive grains between the concave end surface and the rod-shaped grinding wheel, and a magnetic force in the diagonal direction of the concave end surface A concave end surface processing apparatus comprising: a magnet or an electromagnet that generates

Images