JP2006289871A - Method for manufacturing ring zone optical element and method for manufacturing mold for ring zone optical element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a ring zone optical element with a surface roughness to be improved without spending time, and a method for manufacturing a mold for a ring zone optical element. <P>SOLUTION: This method for manufacturing a phase ring zone optical element comprises a circular part forming process to form a circular surface 5 on a surface to be processed of a work W, while rotating the work W on a rotational axis T, a ring zone surface forming process to form a ring zone surface 61 on the surface to be processed, and a corner part forming process to form a corner part between the ring zone surface 61 and a border wall surface 62 by applying a rake surface 11a of a tipped tool 11 to the border wall surface 62 between the circular surface 5 and the ring zone surface 61 or the border wall surface 62 between the ring zone surfaces 61. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a manufacturing method of an annular optical element having an annular portion centered on an optical axis, and a manufacturing method of a mold for an annular optical element for molding the annular optical element.

  In general, an optical element such as a Fresnel lens or a blazed diffractive optical element having a spherical surface centered on the optical axis and a plurality of minute projections formed around the spherical surface is spherical. It is manufactured using a mold in which a concave portion corresponding to the portion and an annular groove corresponding to a minute annular portion are formed. As a method for manufacturing a mold having such an annular groove, a method of cutting a minute annular groove with a tip is known as a general method. In addition, optical elements such as phase ring elements having a circular surface whose plan view is a circle centered on the optical axis and a plurality of annular surfaces formed in a staircase pattern around it are directly turned by a tip or the like. Has been. By the way, in the method of scraping an optical element having such an annular surface formed in a staircase shape or a mold having the annular groove described above with a chip, the tip shape of the chip is a corner of the step of the optical element or a mold. Therefore, it is desired to sharpen the tip shape of the tip. However, there is a problem that the surface roughness of the processed surface is deteriorated only by sharpening the tip shape of the chip.

  Therefore, in the prior art, as shown in FIG. 5, a minute annular groove is formed in the mold by forming the tip of the tip 21 as a cutting tool in a curved shape with a minute radius (with a minute R). There is a method to do (see Patent Document 1). Specifically, as shown in FIG. 6, the tip 21 is continuously arranged along the radial direction of the cylindrical workpiece W with the rake face 21 a of the tip 21 being perpendicular to the rotation direction of the workpiece W. By moving in the axial direction of the workpiece W as appropriate, the minute annular groove 7 is formed so that the tip of the tip 21 is traced to the rough processed wavy surface PF. According to such a technique, the surface roughness is improved as compared with the case where the tip of the chip 21 is sharpened, and the bottom of the annular groove 7 can be formed in a small R shape. Further, it is considered that this technique can be similarly applied to an optical element in which the annular surface is formed in a step shape.

JP 2003-62707 A (paragraph 0059, FIGS. 3 and 6)

  However, with the above-described technique, the surface roughness can be slightly improved as compared with the case where the tip of the tip is sharpened, but the surface roughness is still in a desirable state as compared with the case where it is shaved with a generally used tip. I could not say. In addition, in order to improve the surface roughness as much as possible, processing may be performed while the tip feed rate is extremely reduced. In this case, however, the processing time will be increased, and the temperature stability of the processing environment will be increased. The possibility that the shape deteriorates due to the decrease was also high. In addition, since the tip of the chip is thin, there is a problem that consumption is greater than that of a generally used chip.

  Accordingly, an object of the present invention is to provide a method for manufacturing an annular optical element and a method for manufacturing a mold for an annular optical element that can improve surface roughness without taking time.

  In order to solve the above problems, the present invention provides a circular portion having a circular shape centered on the optical axis in plan view, at least one annular surface formed in a ring shape around the circular portion, and the circular portion. And an annular optical element having an annular surface or a boundary wall surface connecting the annular surfaces, and a chip is rotated while rotating a workpiece around a rotation axis corresponding to the optical axis. By moving the workpiece relative to the workpiece, a circular portion forming step for forming the circular portion on the work surface of the workpiece, and moving the tip relative to the workpiece, An annular surface forming step for forming the annular surface on a work surface, and by directing the rake face of the tip to a portion corresponding to the boundary wall surface, the boundary wall surface and the annular surface It has a corner forming process for forming the corner. The features.

  According to the present invention, in the corner forming step, for example, by directing the rake face of the chip to a portion corresponding to the boundary wall surface that connects the circular portion and the annular surface, as if on the side of the chip (edge of the rake face). Since the workpiece (annular optical element) is shaved, the rake face R is not transferred to the workpiece. That is, according to this method, it is possible to use a general tip having a relatively large R (tip-shaped radius of curvature) of the rake face, so that the surface roughness of the annular optical element can be reduced without taking time. Can be improved. In the present invention, the corner forming step may be performed as described above, and the order of the steps is not limited.

  In the present invention, at least in the corner forming step, the boundary wall surface may be inclined with respect to the rotation axis by inclining the rake face of the chip with respect to the rotation axis. According to this, even if it is an annular optical element in which the boundary wall surface is inclined, it can be satisfactorily formed.

  Furthermore, the present invention may include a roughing step of roughing the circular portion and the annular surface before the circular portion forming step, the annular zone surface forming step, and the corner portion forming step. According to this, since the circular portion and the annular surface are roughly processed with other chips or the like in the roughing step, the consumption of the chips used in the circular portion forming step, the annular surface forming step, and the corner forming step is suppressed. be able to.

  In the present invention, the tip may be rotated in a plane parallel to the rake face. According to this, the burr | flash which generate | occur | produces with the process of a workpiece | work can be skipped with the rotating chip | tip, and a workpiece | work can be processed more favorably. In the present invention, each processing using the above-described tip can be applied to a mold for an annular optical element.

  According to the present invention, in the corner forming step, for example, by cutting the workpiece while directing the rake face of the chip to the boundary wall surface connecting the circular portion and the annular zone surface, the R of the rake face is not transferred to the workpiece. By using a general chip having a relatively large R on the rake face, the surface roughness of the annular optical element and the mold can be processed in a good state without taking time.

  Next, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. 1 is a perspective view showing a turning device used in this embodiment, FIG. 2 is an enlarged perspective view showing a chip, FIG. 3 is a plan view (a) showing a work surface of a workpiece, It is BB sectional drawing (b) of).

  As shown in FIG. 1, the turning apparatus S mainly includes a tool portion Sa having a cutting tool 10 and a head portion Sb to which a columnar workpiece W is attached. Details of each part will be described below. Note that the workpiece W and the chip 11 in FIG. 1 are drawn with a relationship of a size different from the actual dimensions for convenience, but the relationship between the actual size of the workpiece W and the chip 11 is as shown in FIG. It has become a relationship.

[Tool part]
The tool portion Sa is mainly composed of a cutting tool 10 having a chip 11, and this cutting tool 10 is detachably fixed to a base (not shown).

  The cutting tool 10 is mainly composed of a chip 11 and a shank 13 (also referred to as a chip holder or a cutting tool body) to which the chip 11 is detachably attached.

  As shown in FIG. 2, the tip 11 is formed in a shape in which the tip side pressed against the workpiece W is tapered. The tip 11 is an off-the-shelf product manufactured according to a general standard, and its tip shape 11g (commonly referred to as the tip R or simply R) is formed with a relatively large radius of curvature.

  Further, the configuration of the chip 11 will be described. One surface of the chip 11 is a rake surface 11a for mainly cutting the workpiece W. Further, a first flank 11b and a second flank 11c for avoiding interference with the workpiece W are formed on the tip side of the chip 11 so as to be continuous with the tip shape 11g. Note that the clearance angle of the first clearance surface 11b of the tip 11 used in the present embodiment (the angle with respect to the workpiece reference surface BF described later) is an inclined annular zone surface 61 (FIG. 3B) formed on the workpiece W described later. It is formed to be larger than the angle of (see)).

  Further, a bolt hole 11h is formed in the base end portion of the tip 11, and the tip 11 is detachably attached to the tip holding portion 13a (see FIG. 1) of the shank 13 by a bolt (not shown). ing. The method for fixing the chip 11 to the shank 13 is not limited to the above-described method using bolts, and may be a method using brazing, for example.

  As shown in FIG. 1, the shank 13 is an arm having a substantially inverted L shape, and a chip holding portion 13a for holding the chip 11 is formed on one end side thereof. The other end of the shank 13 is detachably fixed to a base (not shown).

[Head]
The head part Sb mainly includes a moving stage 31 for changing the relative position of the workpiece W and the chip 11 in the three-dimensional direction and a chuck 32 for rotating the workpiece W.

  The moving stage 31 includes a forward / backward moving mechanism, a left / right moving mechanism, and an up / down moving mechanism (not shown), so that the moving stage 31 can move in three directions of front / back, left / right, and up / down with respect to the tool portion Sa. That is, as shown by the coordinate axes in FIG. 1, the moving stage 31 is arranged on the Z axis in the front-rear direction parallel to the main axis of the head portion Sb, the X axis in the horizontal direction perpendicular to the Z axis, and the Y axis in the vertical direction. Is free to move.

  The chuck 32 is a portion to which a cylindrical workpiece W is attached, and holds the workpiece W by gripping the outer peripheral surface of the workpiece W with, for example, a vacuum chuck or a plurality of jaws (also referred to as claws or collets) not shown. . The chuck 32 is rotatably attached to the moving stage 31 and is rotated at a predetermined speed by a driving motor (not shown). Here, the rotation speed of the chuck 32 is a relatively large general rotation speed.

  Moreover, the workpiece | work W becomes a raw material of the phase ring zone element (ring zone optical element) which has a step-like ring zone surface. That is, on the work surface 4 of the workpiece W, as shown in FIGS. 3A and 3B, a circular surface (circular portion) 5 whose plan view is a circle centered on the optical axis, or this circular surface. A plurality of annular zone surfaces 61 formed in a ring shape around 5, and a boundary wall surface 62 that connects the circular surface 5 and the adjacent annular zone surface 61 (or the annular zone surfaces 61) are formed by the chip 11. .

  Here, the boundary wall surface 62 is configured to be substantially perpendicular to the workpiece reference plane BF (virtual plane orthogonal to the rotation axis T of the workpiece W). Further, the circular surface 5 and each annular surface 61 are formed so as to be parallel to the workpiece reference surface BF. In the following description, for the sake of convenience, the first annular zone 61A, the second annular zone 61B, the third annular zone 61C, the fourth annular zone 61D, It will also be called the 5th ring surface 61E and the 6th ring surface 61F.

Next, the manufacturing method of the phase ring element by the said turning apparatus S is demonstrated.
In the present embodiment, it is assumed that the circular surface 5, the ring zone surface 61, and the boundary wall surface 62 of the workpiece W are roughened in advance before cutting with the tip 11. Incidentally, as this rough machining, there is a method of roughly forming (cutting) the shape of the workpiece surface 4 with another tool or the like.

  As shown in FIG. 1, first, by rotating the chuck 32, the workpiece W is rotated around a rotation axis T (see FIG. 3B) corresponding to the optical axis of the phase ring element, By moving the workpiece W on the moving stage 31, the rake face 11a of the chip 11 is positioned at the first processing position P1 (see FIG. 3A). The first machining position P1 is a position where the reference line BL extending in the radial direction (horizontal direction) through the center of the workpiece W intersects with the outer periphery of the circular surface 5 (the outer periphery of the circular surface 5). To the front side of the figure. Further, by moving the workpiece W by the moving stage 31 in this way, the chip 11 moves relative to the workpiece W. In the following description, for the sake of convenience, the movement of the workpiece W by the moving stage 31 is performed. The description will be omitted, and only the relative movement of the chip 11 with respect to the workpiece W will be described.

  As shown in FIG. 3 (a), the tip 11 is once moved to the back side of the drawing, so that the tip 11 is bitten into the workpiece W by a predetermined amount, and then moved in the direction of the arrow AR1. A circular surface 5 is formed on W (circular portion forming step). When the formation of the circular surface 5 is completed, the tip 11 is once released from the workpiece W, and then the tip 11 is moved downward and to the right, thereby positioning the rake face 11a of the tip 11 at the second processing position P2. The second machining position P2 is a position where the tangent parallel to the reference line BL in contact with the outer peripheral edge of the circular surface 5 and the outer peripheral edge of the first annular surface 61A intersect (outside the first annular surface 61A). (A position a little away from a predetermined position on the periphery). Incidentally, there are actually two positions on the upper side of the figure and two points on the lower side of the figure, but the positions shown in the figure depend on the rotation direction of the workpiece W and the direction of the rake face 11a of the chip 11. It is determined in such a position.

  And after making the chip | tip 11 bite into the workpiece | work W similarly to the above, it moves to the direction of arrow AR2 (specifically left direction and back direction of a figure), and forms the 1st ring zone surface 61A (ring | wheel). Band surface forming step).

  Thereafter, when the tip 11 moves to the boundary wall surface 62 of the circular surface 5 (the end point of the arrow AR2), the rake surface 11a of the chip 11 hits (or faces) the boundary wall surface 62 between the circular surface 5 and the first annular surface 61A. As a result, the boundary wall surface 62 is formed and the corners of the boundary wall surface 62 and the first annular surface 61A are processed as if they were cut at the edge of the rake face 11a of the chip 11. (In actuality, the workpiece W is cut off when the workpiece W enters obliquely with respect to the rake face 11a). Therefore, the tip shape 11g (see FIG. 2) of the chip 11 is not transferred to the workpiece W, and the corners of the boundary wall surface 62 and the annular zone surface 61 are formed at right angles (corner forming step).

  After that, the chip 11 is sequentially positioned at the third machining position P3, the fourth machining position P4, the fifth machining position P5, the sixth machining position P6, and the seventh machining position P7, and the above-mentioned machining positions P3 to P7 are referred to. By performing the annular zone surface forming step (cutting along arrows AR3 to AR7) and the corner forming step, a plurality of annular zone surfaces 61 and boundary wall surfaces 62 are formed. Note that these processing positions P3 to P7 include a tangent line parallel to the reference line BL in contact with the outer peripheral edge of each annular surface 61 (61A to 61E), and an outer peripheral edge of each annular surface 61 (61B to 61F). (The front side of the figure from a predetermined position of the outer peripheral edge of the second or third ring surface 61B, 61C, 61D, 61D, 61E, 61F) The position is a little further away. In other words, in the present embodiment, the tip 11 is moved relative to each other so that the rake face 11a is along each tangent of each boundary wall surface 62 formed in a cylindrical shape, whereby each annular surface 61, each boundary wall surface 62, and Each corner is formed.

According to the above, the following effects can be obtained in the present embodiment.
Since the R (tip shape) of the rake face 11a is not transferred to the workpiece W by applying (orienting) the rake face 11a of the chip 11 to the boundary wall surface 62 in the corner forming step, the R of the rake face 11a is relatively large. A general chip 11 can be used. And since it becomes possible to use the general chip | tip 11 with comparatively large R of the rake face 11a in this way, it does not spend time and processes the surface roughness of a phase annular element in a favorable state. can do. In addition, since the general chip 11 having a relatively large R can be used as described above, the consumption of the chip 11 can be suppressed as compared with the conventional case where a chip having a small R is used.

Since the circular surface 5, the ring zone surface 61, and the boundary wall surface 62 are rough-processed in advance before cutting with the tip 11, consumption of the tip 11 used for final finishing can be further suppressed.
Further, according to the processing method as in the present embodiment, since the workpiece W can be cut only with the top of the tip R of the chip 11, it is sufficient to process only the top with high accuracy. That is, since the contour accuracy width (window angle) of the chip 11 can be set small, high-precision machining can be performed at low cost and with short delivery time. By the way, in the conventional method (method shown in FIG. 6), most of the tip R must be machined with high precision by cutting the tip R using most of the tip R (for example, the half on one side). Therefore, the cost is high and the delivery time is also slow.

In addition, this invention is implemented in various forms, without being limited to the said embodiment.
In this embodiment, the boundary wall surface 62 is perpendicular to the workpiece reference plane BF. However, the present invention is not limited to this, and by changing the direction of the rake face 11a of the chip 11 during the corner forming process. The boundary wall surface 62 may be inclined. According to this, even an optical component having a tapered boundary wall surface can be formed satisfactorily. The rake face 11a may be inclined so that the base end portion of the rake face 11a approaches the workpiece surface 4 or may be inclined about an axis parallel to the rotation axis T. The tilt angle is preferably 5 ° or less when the rake surface 11a is tilted with respect to the workpiece surface 4, and is preferably 3 ° or less when the rake surface 11a is tilted around an axis parallel to the rotation axis T.

  In this embodiment, the movable stage 31 that can move in the three-axis direction is provided on the head portion Sb side, but the present invention is not limited to this. For example, a structure in which the head part Sb side is fixed and a movable stage that can move in three axis directions (front and rear, left and right, up and down) is provided on the tool part Sa side, or one axis direction (for example, front and rear) on the head part Sb side. A structure in which a movable stage is provided, and a movable stage (for example, left and right, up and down) that can be moved in the biaxial direction on the tool portion Sa side may be employed.

  In this embodiment, the processing is performed in the order of the circular portion forming step → the annular surface forming step → the corner forming step → the annular surface forming step →... →→ the corner forming step. For example, the process of the present embodiment is performed from the reverse side, that is, the corner forming process → the annular surface forming process → the corner forming process → ... → the annular surface forming process → the circular part forming process. You may process in order. In this case, each start position of the chip 11 for forming each annular zone surface 61 is the end of each arrow AR7, AR6, AR5, AR4, AR3, AR2 (in the vicinity of each boundary wall surface 62). However, since the rotational speed of the workpiece W is zero at the end of the arrow AR1, the start position of the chip 11 for forming the circular surface 5 is desirably the start of the arrow AR1 as in the present embodiment.

  In the present embodiment, roughing is added before finishing with the chip 11, but the present invention is not limited to this, and a solid workpiece W may be directly processed with the chip 11. When the workpiece W is in a solid state, the boundary wall surface 62 to which the rake surface 11a of the chip 11 is applied is naturally not formed, but the program of the NC processing device (turning device S) is changed as appropriate. Accordingly, the position of each boundary wall surface 62 and each processing position can be set. Therefore, the rim surface 11a of the chip 11 is placed on the place corresponding to the boundary wall surface 62, and the boundary between the annular surface 61 and the ring surface 61 is thus obtained. The corner of the wall surface 62 can be formed at a right angle (sharp).

  In the present embodiment, the chip 11 is fixed. However, the present invention is not limited to this. For example, the chip 11 may be rotated in a plane parallel to the rake face 11a. Specifically, as shown in FIG. 4, a plurality of chips 11 may be arranged on the outer peripheral surface of a cylindrical jig J so that the blades face outward, and the jig J is rotated about the center. Further, the rotation of the chip 11 may be performed in any one of the above-described steps, or may be performed in all the steps.

  In the present embodiment, the phase annular element is adopted as the annular optical element, but the present invention is not limited to this, and for example, a resin optical cutting product, a germanium lens, a metal mirror, or the like may be adopted. Further, as a manufacturing target, not only the annular optical element but also a mold for molding such an annular optical element (for example, a Fresnel lens) may be adopted.

  In the present embodiment, the present invention is applied to a type in which the cross-sectional shape of the annular zone surface 61 is a linear shape. The present invention can also be applied to.

  In the present embodiment, the circular portion is the planar circular surface 5, but the present invention is not limited to this, and may be a spherical concave portion, for example.

It is a perspective view which shows the turning apparatus used by this embodiment. It is an expansion perspective view which shows a chip | tip. It is the top view (a) which shows the to-be-processed surface of a workpiece | work, and BB sectional drawing (b) of (a). It is a perspective view which shows the form which rotates a chip | tip. It is an expansion perspective view which shows the chip | tip with the conventional small tip R. It is a figure which shows the manufacturing method of the conventional metal mold | die, and is the top view (a) which shows the to-be-processed surface of a workpiece | work, and AA sectional drawing (b) of (a).

Explanation of symbols

4 Work surface 5 Circular surface 10 Byte 11 Tip 11a Rake surface 31 Moving stage 32 Chuck 61 Ring surface 62 Boundary wall surface S Turning device Sa Tool part Sb Head part T Rotating shaft W Workpiece

Claims (6)

A circular portion whose planar view is a circle centered on the optical axis;
At least one ring surface formed in a ring shape around the circular portion;
A method for manufacturing an annular optical element having the circular portion and the annular surface, or a boundary wall surface connecting the annular surfaces,
A circular portion forming step of forming the circular portion on the work surface of the workpiece by rotating the workpiece relative to the workpiece while rotating the workpiece around a rotation axis corresponding to the optical axis. When,
An annular surface forming step for forming the annular surface on the work surface by moving the tip relative to the workpiece, and
A method for manufacturing an annular optical element, comprising: a corner forming step of forming a corner between the boundary wall surface and the annular surface by directing a rake face of the chip toward a portion corresponding to the boundary wall surface. . It is a manufacturing method of the zonal optical element according to claim 1,
At least during the corner forming step,
A method for manufacturing an annular optical element, wherein the boundary wall surface is inclined with respect to the rotation axis by inclining the rake face of the chip with respect to the rotation axis. A manufacturing method of the annular optical element according to claim 1 or 2,
Before the circular portion forming step, the ring zone surface forming step and the corner portion forming step,
A method for manufacturing an annular optical element, comprising: a roughing process for roughing the circular portion and the annular surface. It is a manufacturing method of the zonal optical element according to any one of claims 1 to 3,
In any one or more of the steps,
A method of manufacturing an annular optical element, wherein the tip is rotated in a plane parallel to the rake face. A circular portion whose planar view is a circle centered on the optical axis;
At least one ring surface formed in a ring shape around the circular portion;
A method for producing a mold for an annular optical element for molding an annular optical element having the circular portion and the annular surface, or a boundary wall surface connecting the annular surfaces,
A mold side circle corresponding to the circular portion is formed on the work surface of the work by rotating the work relative to the work while rotating the work around a rotation axis corresponding to the optical axis. A mold side circular part forming step for forming a part;
A mold side annular surface forming step for forming a mold side annular surface corresponding to the annular surface on the work surface by moving the tip relative to the workpiece; With
A mold side corner that forms a corner between the mold side boundary wall surface and the mold side ring surface by directing the rake face of the chip to a portion corresponding to the mold side boundary wall surface corresponding to the boundary wall surface. Part forming step,
At least during the corner forming step,
A method for producing a mold for an annular optical element, wherein the boundary wall surface is inclined with respect to the rotation axis by inclining the rake face of the chip with respect to the rotation axis. A circular portion whose planar view is a circle centered on the optical axis;
At least one ring surface formed in a ring shape around the circular portion;
A method for producing a mold for an annular optical element for molding an annular optical element having the circular portion and the annular surface, or a boundary wall surface connecting the annular surfaces,
A mold side circle corresponding to the circular portion is formed on the work surface of the work by rotating the work relative to the work while rotating the work around a rotation axis corresponding to the optical axis. A mold side circular part forming step for forming a part;
A mold side annular surface forming step for forming a mold side annular surface corresponding to the annular surface on the work surface by moving the tip relative to the workpiece; With
A mold side corner that forms a corner between the mold side boundary wall surface and the mold side ring surface by directing the rake face of the chip to a portion corresponding to the mold side boundary wall surface corresponding to the boundary wall surface. Part forming step,
In any one or more of the steps,
A method of manufacturing a mold for an annular optical element, wherein the chip is rotated in a plane parallel to the rake face.

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