JP4340512B2 - Lens peripheral processing apparatus and processing method - Google Patents

Description

  The present invention relates to an outer periphery processing apparatus and an outer periphery processing method for a lens, and more particularly to an apparatus and a method for grinding a deformed lens having a part of the outer periphery cut (cut) using a rotating grindstone.

  The outer periphery processing of the lens by the lens centering machine is performed by holding the front and back surfaces of the lens with opposing cup-shaped holders and grinding the outer periphery of the lens with a rotating grindstone while rotating the lens around the optical axis. In general circular lenses, the outer periphery of the lens is processed into a perfect circle by holding the rotating grindstone in a fixed position.However, in the case of polygonal lenses and some finder lenses, the outer periphery A cutting process that cuts a part straight is necessary.

  Conventionally, as shown in FIG. 4, this cutting process is performed by grinding the lens outer periphery with a lens centering machine, and then rotating the lens 5 in a state where the rotation of the lens 5 is stopped. That is, it is performed by moving the lens 5 in the tangential direction.

  However, the method of FIG. 4 in which the rotating grindstone 6 of the lens centering machine is moved in the Y-axis direction requires a guide and a feeding device for guiding the grindstone table on which the grindstone 6 is mounted in the Y-axis direction, and the apparatus structure is complicated. become. That is, the lens centering machine moves the rotating grindstone 6 in the X-axis direction (the lens of the lens) in order to set the rotating grindstone 6 at a position corresponding to the processing diameter of the lens and to chamfer the periphery of the lens front and back surfaces. Although it is necessary to move in the radial direction) and the Z-axis direction (the optical axis direction of the lens), movement in the Y-axis direction is not necessary. Therefore, in the case of this method, it is necessary to provide a moving mechanism in the Y-axis direction of the rotating grindstone 6 in the lens centering machine only for cutting the outer periphery of the lens, and the apparatus becomes complicated and expensive. .

As a prior art for solving this problem, Patent Document 2 discloses a centering machine that cuts the outer diameter of a lens by holding the lens narrowly with a pair of opposing cup-shaped jigs. There has been proposed an automatic centering method for processing the outer shape of a lens into an oval shape and a square shape by using an NC device capable of electronic cam control of the rotation of the shaft and the direction of cutting the outer diameter of the grindstone shaft.
JP 59-19605 A JP 2000-218489 A

  However, even in the method described in Patent Document 2, the cutting process is performed after the perfect circle process on the outer periphery of the lens, and is a two-step process including a useless circular process such as a perfect circle process for the part to be cut. The processing efficiency is bad. Further, in the conventional processing method as described above, a sharp corner is formed in a portion where the linear cut portion and the circular outer periphery are connected, and the corner portion is chipped or injured during or after the processing. A problem occurs.

  Therefore, the present invention can continuously process a perfect circle portion and a cut portion in the centering processing of a deformed lens including a linear cut portion on the outer periphery, which is called D cut or H cut. Therefore, the outer circumference of the lens that can perform circular chamfering (R chamfering) or straight chamfering (C chamfering) without sharp corners or discontinuous steps at the boundary between the perfect circle part and the cut part. The problem is to provide a processing method.

  The outer periphery processing of the lens by the method of the present invention includes a workpiece driving motor 29 for rotating and driving a pair of workpiece shafts 1a and 1b having cup-shaped lens holders 3 and 4 at opposite ends, and a direction perpendicular to the axis of the workpiece shaft ( A rotating grindstone 6 that is mounted on a grindstone base 14 that advances and retreats in the X-axis direction and processes the outer periphery of the lens held by the lens holder, an X feed motor 35 that advances and retracts the grindstone base, the X feed motor, and the This is performed using a lens centering machine including an NC device 40 that controls the rotation angle of the work drive motor.

In other words, the lens outer peripheral processing apparatus according to the first aspect of the present invention includes a workpiece driving motor 29 that rotationally drives a pair of workpiece shafts 1a and 1b having cup-shaped lens holders 3 and 4 at opposite ends, and the workpiece. A rotating grindstone 6 that is mounted on a grindstone base 14 that advances and retreats in the direction perpendicular to the axis (X-axis direction) and processes the outer periphery of the lens held by the lens holder; an X feed motor 35 that advances and retracts the grindstone base; An NC device 40 for controlling the rotation angle of the X-feed motor and the work drive motor, and the NC device includes a rotation angle of the work shaft and a grindstone position when machining the cut portion 7 on a part of the outer periphery of the lens. And the relationship between the rotation angle of the workpiece axis and the grinding wheel position when the arc chamfered portion 8 is formed at the corner portion between the cut portions or between the cut portion and the perfect circle portion 9. Corner And control means (arc chamfered control means), the distance from the lens center of the cut portion H, the arc radius of the circular arc chamfer provided at the boundary between the true circle portion of the cutting portion and the lens a, the grinding wheel 6 Control conversion angle calculation that calculates angles α and β of the workpiece axis given by cosα = (Ha) / (ra), tanβ = (ra) sinα / (R + H) where R is the radius and r is the lens radius. Means.

In the lens outer periphery processing method of the present invention using the outer periphery processing apparatus according to the first aspect of the present invention, when the rotation angle of the workpiece axis reaches the control conversion angle calculated by the control conversion angle calculation means, From the perfect circle processing control for processing the outer periphery of the lens into a perfect circle while holding the rotating grindstone 6 at a fixed position, to the corner control by the control of the corner control means, and then from the corner control to the control of the cut control means. By converting the control to cut control, then from the cut control to the corner control again, and then from the corner control to the perfect circle machining control, the circular chamfer is formed at the corner of the round portion 9 and the cut portion 7. The round part and the cut part of the lens with or without the part 8 are continuously processed without separating the grindstone from the lens.

  Further, the lens outer periphery processing method according to the third aspect of the present invention uses the outer periphery processing apparatus according to the first aspect, and each time the rotation angle of the workpiece axis reaches the control conversion angle calculated by the control conversion angle calculation means. Further, the control is converted from the round control to four corner control with zero chamfer radius, three cut control performed between these corner controls, and the next round control. Thus, the perfect circle portion and the cut portion of the lens having the straight chamfered portion 11 at the corner portion between the perfect circle portion 9 and the cut portion 7 are continuously processed without separating the grindstone from the lens.

  According to the present invention, the lens centering that performs round processing on the outer periphery of the lens in order to cut the outer periphery of the lens in order to obtain a D-cut or H-cut that cuts a part of the outer periphery of the circular lens or a polygonal lens. It becomes possible to carry out without rounding the grindstone from the lens at the same time as processing a perfect circle on the machine. Therefore, it is possible to perform the cutting process of the deformed lens in one step at the same time as the centering process, and the outer periphery is continuously processed without separating the grindstone from the lens. It is possible to connect the boundary with smooth arcs and corners to avoid chipping due to discontinuous cutting force acting on the corners and steps due to separation and re-contact of the grindstone. be able to.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing an example of a lens centering machine according to the present invention, wherein 13 is a column, 1a and 1b are upper and lower work shafts arranged on the same vertical line, 6 is a grindstone, 14 is a grindstone base, and 15 is a Z slide. , 40 is an NC device.

  The lower work shaft 1b is pivotally supported by the column 13 so as to be rotatable and not movable up and down. An upper cup-shaped lower holder 4 is attached to the upper end of the lower work shaft 1b, and a lower driven gear 18 is fixed to the lower end. The upper work shaft 1a is pivotally supported by a bearing case (not shown) that is mounted on the column 13 so as to be movable up and down and urged upward with a weak force. The upper driven gear 16 is fixed to the upper end.

  A thrust bearing is built in the upper part of the shaft center of the upper driven gear 16, and a clamp cylinder 23 is arranged above it. When the downward rod 24 of the clamp cylinder extends and presses the thrust bearing, the upper work shaft 1a is lowered and the lens 5 is sandwiched between the upper holder 3 and the lower holder 4.

  A drive shaft 28 is supported in parallel with the work shaft 1 (1a, 1b), and the lower end of the drive shaft is connected to a servo motor 29. Drive gears 30 and 31 are fixed to the drive shaft 28 in the upper and lower directions, and mesh with the upper and lower driven gears 16 and 18, respectively. The upper driven gear 16 has a larger tooth width so that the upper drive gear 30 is not disengaged even when the upper work shaft 1a is moved upward when the lens 5 is attached or detached.

  The grindstone 6 is pivotally supported on the grindstone base 14 so as to be freely rotatable about a vertical axis. The grindstone base 14 is mounted on the Z slide 15 so that it can be moved and positioned in the cutting direction (X direction) of the grindstone 6 by a linear motion guide 33 and a feed screw 34 that is rotationally driven by an X direction feed motor 35. The Z slide 15 is mounted on the column 13 such that the Z slide 15 can be moved and positioned in the vertical direction (Z direction) by a feed screw 37 rotated by a vertical linear motion guide 36 and a Z direction feed motor 38. The X-direction and Z-direction feed motors 35 and 38 and the above-described work drive motor 29 are servo motors controlled by the NC device 40, and their rotation angles are controlled by the NC device 40 via servo amplifiers 41a, 41b and 41c. Has been.

  The NC device 40 includes a control conversion angle calculation means 42 for calculating the angles α and β of the workpiece shaft 1 when the control is converted based on the specified lens cut height H and chamfer radius a, and the calculated workpiece. An outer peripheral cut control means 43 and a corner control means 44 for moving the grindstone table 14 to a position on the smaller diameter side from the lens outer peripheral processing position in association with the rotation angle of the work shaft 1 between adjacent control conversion angles of the shaft 1 are provided. ing.

Arc chamfer radius a (a> = 0 at the boundary between the height H of the cut portion of the lens (see FIG. 2) and the cut portion and the perfect circle portion (a> = 0. The control conversion angle calculation means 42 controls the control conversion angle α between the perfect circle and the arc chamfer, and the control conversion angle β between the arc chamfer and the cut. And is calculated by the following equation.
cosα = (Ha) / (ra)
tanβ = (ra) sinα / (R + H)
Here, R is the radius of the grinding wheel, and r is the radius of the lens.

Further, the cut control means 43 is an expression for the rotation angle θ of the workpiece axis with the distance X from the lens center to the grindstone center and the cut center P being 0 degree.
X = (R + H) / cosθ
The grindstone table 14 is controlled so that the relationship of
X = (ra) cos (α-θ) + (R + a) cosσ
However, sinσ = (ra) sin (α-θ) / (R + a)
The grinding wheel base 14 is controlled so as to satisfy the following relationship.

  The meanings of these equations are shown in FIG. In the figure, 5 is a lens to be processed, 6 is a rotating grindstone, 7 is a cut portion with a cut height H, P is a midpoint of the cut portion 7, 8 is an arc chamfered portion with a chamfer radius a, and Q is The arc center of the arc chamfered portion, A is a contact point between the arc chamfered portion 8 and the perfect circle portion 9, and B is a contact point between the arc chamfered portion 8 and the cut portion 7. The circle indicated by an imaginary line in the figure is a circle having a radius ra, the straight line indicated by an imaginary line is a straight line having a distance Ha to the center of the lens, and the arc center of the circular chamfered portion 8 is at the intersection of these imaginary lines. There is Q. With respect to the rotation angle θ of the lens, the cut center P is 0 degree. The shape of the lens 5 shown in FIG. 2 is a shape after processing.

In FIG. 2, the contact point A is on the straight line OQ, and the grinding wheel center when grinding the point A is also on the straight line OQ. Therefore, the rotation angle α of the lens when grinding the point A is
cosα = (Ha) / (ra)
It is.

Since the contact point B is an intersection of a line drawn in parallel with the straight line OP from the point Q and the cut portion 7, the rotation angle β of the lens when the grindstone grinds this point B is (R + H) tan β = From (ra) sinα,
tanβ = (ra) sinα / (R + H)
It is.

The distance X from the center of the lens to the center of the grindstone when the cut portion 7 is processed is from Xcosθ = R + H, where θ is the lens rotation angle with the radius OP being 0 degrees,
X = (R + H) / cosθ
It is. Further, the distance X when the circular chamfered portion 8 is processed takes an angle σ as shown in FIG.
X = (ra) cos (α-θ) + (R + a) cosσ
Since (R + a) sinσ = (ra) sin (α−θ), the angle σ is obtained by sinσ = (ra) sin (α−θ) / (R + a).

  The NC device 40 controls the grindstone 6 so that the position of the grindstone during the centering of a perfect circle, that is, the position of X = R + r, is in the range of θ = −180 degrees to −α and α to 180 degrees. In the range of θ = −α to −β and in the range of θ = β to α, the workpiece drive motor 29 and the X feed motor 35 are controlled according to the command of the corner control means 44, and the range of θ = −β to β. Then, the work drive motor 29 and the X feed motor 35 are controlled in accordance with a command from the cut control means 43.

  The lens 5 to be processed is placed on the lower holder 4 with the upper surface of the upper work shaft 1 a moved upward, with the upper surface being vacuum-sucked by a loader hand (not shown). After the loader is retracted, low pressure air pressure is supplied to the clamp cylinder 23, and the lens 5 is lightly held between the upper and lower holders 3 and 4. When the servo motor 29 is rotated at a high speed in this state, the upper and lower workpiece axes rotate at a high speed, the lens 5 moves to a stable position according to the curvature of the spherical surface, and the optical axis coincides with the axis of the workpiece axes 1a and 1b. . Therefore, the air pressure of a predetermined pressure is supplied to the clamp cylinder 23 to clamp the lens 5, the servo motor 29 is rotated at a predetermined rotation number, and the outer periphery of the lens 5 is processed by the grindstone 6.

  The outer peripheral machining is started from a perfect circle portion. While rotating the workpiece axis slowly, the grinding wheel base 14 is fed and fixed until the center of the grinding wheel reaches the distance R + r from the lens center, and the round part is processed while rotating the workpiece axes 1a and 1b at a speed corresponding to the cutting depth. I do. When the rotation angle of the work drive shaft reaches -α, the control of the NC device is switched to the corner control means, and when it reaches -β, the control is switched to the cut control means. The corner control means 44 and the cut control means 43 control the rotation angles of the work drive motor 29 and the X feed motor 35 in accordance with the relationship described above. At this time, the rotation of the work drive motor is changed in a direction in which the rotation speed of the lens becomes slower in accordance with the increase in the cut amount of the work. When the rotation angle of the workpiece drive shaft 1 reaches β, the control is returned to the corner control means 44 again, and when the rotation angle reaches α, the control is returned to the initial round processing state.

  The above-described processing does not require processing to the desired finished size by one rotation of the lens, and the lens radius r is gradually decreased so as to gradually approach the desired finished radius every time the lens rotates. The height H may be gradually reduced from a value close to r so that the height H becomes a desired cut height, and finally changed to a desired cut height.

  When the outer periphery processing of the lens is completed as described above, the servo motor 29 is stopped, the air pressure of the clamp cylinder 23 is released, the upper work shaft 1a is moved up, and the processed lens is removed by vacuum suction of the loader. Take it out.

  If the chamfering radius a is set to 0 in the above processing, a cutting process without chamfering at the corners of the perfect circle portion 9 and the cut portion 7 is realized. The processing shape in this case is the same as the processing shape by the conventional method, but the processing from the perfect circle part 9 to the cut part 7 and from the cut part 7 to the perfect circle part 9 is continuous without separating the grindstone from the lens. Therefore, discontinuous cutting stress does not act on the corner portion, and chipping of the corner portion during machining can be prevented.

The above example is an example in which circular chamfering is performed at the corner of the cut portion 7, but linear chamfering can also be performed. Since the straight chamfering is the same tangential straight line processing as the cutting process, as shown in FIG. 3, when the cutting height is G and the chamfering angle is φ, the processing of the straight chamfering portion 12 is the lens. The distance X from the center to the center of the grinding wheel is
When θ> 0, X = (R + G) / cos (θ + φ)
When θ <0, X = (R + G) / cos (θ−φ)
It becomes. Therefore, the linear chamfered portion 11 can be processed by designating these numerical values in the cutting means 43.

When converting control from round processing to cut processing of the straight chamfer 11, control is converted from round processing to circular chamfering, and control from circular chamfering to cutting of straight chamfered portions with a = 0. To do. The angle when converting is
cosα = G / r
tanβ = rsinα / (R + G)
As φ + α and φ + β.

Further, the control conversion from the perfect circle portion 9 to the cut portion 7 is performed in the procedure of cut control → circular chamfering control → cut control. The angles γ and δ when converting each control are shown in FIG. Referring to point B as the intersection of the cut surface and the chamfered surface, and the angle between the perpendicular drawn from the lens center O to the chamfered surface and point B as ε,
From Gtanεtanφ = GH / cosφ
tanε = 1 / tanφ-H / Gsinφ
Since ε is obtained from this, using this angle ε,
(G + R) tan (γ-φ) = Gtanε
(H + R) tanδ = Htan (φ + ε)
It can be obtained from the relationship. And between the angles γ and δ,
X = Gcos (θ-φ) + Rcos (θ-φ)
It is only necessary to control the relationship. The cut portion 7 is processed in the range of the angle −δ to δ as in the case of the circular chamfering described above.
X = (H + R) / cosθ
Control may be performed so that

The figure which shows the side structure and control system of the principal part of the lens centering machine The figure explaining the positional relationship between the rotation angle of the lens and the rotating wheel The figure explaining the positional relationship between the rotation angle of the lens and the rotating grindstone when performing straight chamfering Explanatory drawing showing an example of conventional cutting

Explanation of symbols

1a Upper workpiece axis
1b Lower work shaft 3 Upper holder 4 Lower holder 6 Grinding stone 7 Cut part with cut height H 8 Arc chamfer part with chamfer radius a 9 Round part
11 Straight chamfer
14 Grinding wheel
29 Servo motor
35 X direction feed motor
40 NC unit A Contact point between circular chamfered part 8 and perfect circle part 9 Angle of workpiece axis 1 Angle of workpiece axis 1

Claims (3)

A work drive motor (29) that rotationally drives a pair of work shafts (1a, 1b) provided with cup-shaped lens holders (3,4) at opposite ends, and a grindstone base that moves forward and backward in the direction perpendicular to the axis of the work shaft ( 14) a rotating grindstone (6) for processing the outer periphery of the lens held by the lens holder, an X feed motor (35) for advancing and retracting the grindstone table, and the X feed motor and the work drive motor. An NC device (40) for controlling the rotation angle, and the NC device has a rotation angle of the work shaft and a grinding wheel position when machining a cut portion (7) obtained by linearly cutting a part of the lens outer periphery. Cut control means for controlling the relationship between the rotation angle of the workpiece axis and the grinding wheel position when the arc chamfered portion (8) is formed at the corner portion between the cut portions or between the cut portion and the perfect circle portion (9). a corner control means for controlling the relationship, the distance from the lens center of the cut portion H, the cutting portion and Le Cosα = (Ha) / (ra), tanβ = (ra) sinα, where a is the arc radius of the circular chamfer provided at the boundary with the true circle part of the groove A lens outer peripheral processing apparatus comprising: a control conversion angle calculation means for calculating angles (α) and (β) of a workpiece axis given by / (R + H) . When the rotation angle of the workpiece axis reaches the angle calculated by the control conversion angle calculation means , the outer periphery of the lens is processed into a perfect circle by holding the rotating grindstone at a fixed position when the rotation angle of the workpiece axis reaches the angle calculated by the control conversion angle calculation means. to the corner control by the corner control roundness machining control, then to the cut control by said cut control means, and then to the corner portion control again, followed by converting the control to the perfect circle machining control, true Continuous processing of the round part and the cut part of the lens with or without the circular chamfered part (8) at the corners of the circular part (9) and the cut part (7) without separating the grindstone from the lens. The outer periphery processing method of a lens. Using the periphery processing device according to claim 1, in each rotation angle of the workpiece shaft reaches the angle where the control converting angle calculating means is calculated, the roundness machining control, the corners of the four chamfered zero radius control and, with the cut control of three performed between these corners controlled by converting the control to the next of the perfect circle machining control, perfect circle section (9) cutting portion (7) A method for processing an outer periphery of a lens, in which the round portion and the cut portion of the lens having the linear chamfered portion (11) at the corner portion thereof are continuously processed without separating the grindstone from the lens.

Images