JP5797986B2 - Lens polishing method and lens polishing apparatus - Google Patents

Description

  The present invention relates to a lens polishing method and a lens polishing apparatus for polishing a lens surface while swinging and rotating the processing plate in a state where a spherical processing surface of a processing plate is pressed against a lens surface of a lens to be processed.

  2. Description of the Related Art A lens polishing method and a lens polishing apparatus are known that perform polishing (grinding or cutting) while swinging and rotating while pressing a processing dish against a lens to be processed. The applicants of the present application have proposed such a rocking and rotating lens polishing apparatus in Patent Documents 1 to 3.

  The lens polishing apparatus displayed in FIG. 7 of Patent Document 1 can swing and rotate the processing dish and can change the rotation speed thereof. In addition, in order to press the lens to be processed attached to the lens holder against the processing plate, a free rotating spindle with the lens holder attached, a holder shaft that supports the spindle in a rotatable state, and a pressing force are generated. An air cylinder is provided. An adjustment screw is attached to the holder shaft in parallel with the moving direction, and a dial gauge is installed at a position where the measuring element contacts the adjustment screw. The cutting target position of the lens to be processed is set to a position where the dial gauge scale becomes “0”, and when the dial gauge probe moves as the cutting progresses and the scale becomes “0”, the cutting process is finished. It is like that.

JP 2004-298985 A JP 2003-340702 A JP 2011-93044 A

  In recent years, a high lens thickness accuracy of 10 microns or less has been required for such a oscillating and rotating lens polishing apparatus. However, the conventional oscillating and rotating lens polishing apparatus may have insufficient performance to perform such high-precision polishing. It is assumed that the main reason for this is that the processing completion time point cannot be accurately detected due to the measurement error of the lens polishing apparatus and the measurement error due to vibration during processing.

  For example, the lens cutting amount of an oscillating and rotating lens polishing apparatus is 70 microns, the cutting time is 20 seconds, the rotational speed of the processing dish is 3000 rpm, and the cutting amount per rotation of the processing dish is 0.7 microns. . In this case, it takes about 2 seconds for the processing plate to actually stop after the processing plate rotation stop command is issued at the end of processing. Since the processing plate rotates about 50 rotations after the rotation stop command is issued until the processing plate stops, the cutting amount during this period becomes about 3.5 microns.

  On the other hand, if the vibration width during processing is 30 microns, the dial gauge probe also vibrates due to the vibration transmitted from the processing position to the holder shaft, so the measured value of the dial gauge should also change within a width of 30 microns. However, there are protective buffer materials, lens holders, holder shafts, etc. for the lens to be processed between the processing position and the gauge gauge. Due to expansion and contraction of these members, gaps between the members, rattling, and the like, vibration at the machining position is often not accurately transmitted to the measuring element. In particular, in the processing state in which the lens to be processed is pressed against the processing plate with a high pressing force, the fluctuation range of the dial gauge measurement value tends to be larger than the actual vibration width. In addition, when the measurement response by the probe coming from the dial gauge structure is slower than the actual machining vibration speed, the machining is completed even though the machining is completed, the measured value does not become “0”. There is a risk of falling into a non-detection state. The measurement error of the dial gauge due to these factors is assumed to be about 10 to 20 microns.

  An object of the present invention is to propose a lens polishing method and a lens polishing apparatus capable of performing lens polishing with an accuracy of 10 microns or less using a swinging and rotating lens polishing apparatus.

  In order to solve the above problems, in the lens polishing method and the lens polishing apparatus of the present invention, in order to reduce the processing vibration speed that causes an increase in the measurement error of the polishing amount in the conventional oscillating rotation type lens polishing apparatus. The processing plate rotation speed is slow. In addition, the pressing force of the lens to be processed on the processing plate, which causes an increase in measurement error, is reduced. Furthermore, in order to suppress an increase in processing time, the rotational speed of the processing pan is switched from high speed to low speed near the end of processing and the pressing force is switched from high pressure to low pressure. In addition, in order to avoid the occurrence of measurement errors due to switching of the pressing force, as a measured value representing the processing end position, when the lens to be processed reaches the target processing thickness when polished with a low pressing force Is adopted.

  That is, the lens polishing apparatus of the present invention includes a processing plate rotating mechanism that rotates the processing plate around the processing plate central axis, and a processing plate rocking mechanism that swings the processing plate around the spherical center of the spherical processing surface. A moving mechanism, a holder shaft that supports the lens holder so as to be rotatable about a central axis of the holder, and the lens to be processed held by the lens holder via the holder shaft and the lens holder. A pressing cylinder that applies a pressing force that presses the lens surface against the spherical processing surface of the processing plate, and detects that the holder shaft has moved to a first position and a second position in a direction along the holder central axis. And a detector.

The lens polishing apparatus sets the pressing force to the first pressing force and the rotation speed of the processing dish until the detection movement position of the holder shaft detected by the detector reaches the first position from the polishing start position. The lens surface is polished under the polishing conditions set at the first rotation speed. Also, until the detected movement position of the holder shaft reaches the second position from the first position, the polishing force is set to the second pressing force and the rotation speed is set to the second rotation speed. The polishing operation is performed on the lens surface to be processed.

Here, the second pressing force is a value lower than the first pressing force, and the second rotation speed is a value lower than the first rotation speed. Further, the first position and the second position are in the direction of the holder central axis between the detection position of the holder shaft by the detector and the processing position of the lens to be processed held by the lens holder. It is a position set based on a measurement result obtained by measuring in advance that the distance increases or decreases according to the pressing force. More specifically, the first position is polished until the lens center thickness of the lens to be processed is thicker by a predetermined amount than the target lens center thickness under the first pressing force. It is the detected movement position of the holder shaft at the time when the operation is performed. The second position is the detection of the holder shaft at the time when the polishing operation is performed until the lens center thickness of the lens to be processed becomes the target lens center thickness under the second pressing force. It is a moving position.

  The lens polishing method and the lens polishing apparatus of the present invention can suppress a decrease in accuracy due to a measurement error of the lens polishing amount. According to the experiments by the present inventors, it was confirmed that the lens processing accuracy can be increased to 10 microns or less. Therefore, it becomes possible to perform lens polishing processing that meets the demand for higher lens wall thickness accuracy using a rocking and rotating lens polishing apparatus.

It is a schematic block diagram which shows the rocking | fluctuation rotation type lens polisher to which this invention is applied. It is a schematic flowchart which shows an example of lens grinding | polishing operation | movement using the lens grinding | polishing apparatus of FIG.

  Embodiments of a swinging and rotating lens polishing apparatus to which the present invention is applied will be described below with reference to the drawings.

  With reference to FIG. 1, the overall configuration of a rocking and rotating lens polishing apparatus according to the present embodiment will be described. The lens polishing apparatus 1 includes a lower unit 2, an upper unit 3, and a controller 4. The lower unit 2 includes a processing dish 5, a processing dish rotating mechanism 6, and a processing dish swinging mechanism 7. The processing dish 5 includes a spherical processing surface 5b formed on the surface of the hemispherical head 5a, and a columnar rotating shaft portion 5c extending coaxially from the back surface of the head 5a. The processing plate rotating mechanism 6 includes a processing plate rotating motor 8 and a speed reducer unit 9, and the processing plate 5 is driven to rotate about the processing plate center axis 5 d by decelerating rotation output from the speed reducer unit 9. . The processing dish swing mechanism 7 is a mechanism for swinging the processing dish 5 in a predetermined direction with a predetermined amplitude about the spherical center O of the spherical processing surface 5b of the processing dish 5.

  The upper unit 3 includes a lens holder 11, a spindle 12, a holder shaft 13, and an air cylinder 14. On the lower surface of the lens holder 11, the lens 15 to be processed can be concentrically held with the concave spherical lens surface 15a facing downward. The lens holder 11 is coaxially attached to the lower end of the spindle 12. The spindle 12 is attached to the lower end portion of the hollow holder shaft 13 through a bearing 16 so as to be coaxial and rotatable. The holder shaft 13 is slidably held in a coaxial state by a shaft holding sleeve 17. The shaft holding sleeve 17 and the air cylinder 14 are supported by a lifting mechanism (not shown) and can be lifted and lowered together. By driving the air cylinder 14, the holder shaft 13 can be slid in the vertical direction with respect to the shaft holding sleeve 17. The holder center line of the lens holder 11, the spindle center axis of the spindle 12, and the shaft center axis of the holder shaft 13 are located on a vertical line L passing through the sphere center O of the processing plate 5. L is referred to as “center axis L”.

  In the polishing operation of the lens 15 to be processed, the lens 15 to be processed is held on the lower surface of the lens holder 11, and the upper unit 3 is lowered and positioned with respect to the lower unit 2 in this state. Then, the holder shaft 13 is slid downward by the air cylinder 14 to form a state in which the lens surface 15a of the lens 15 to be processed is pressed against the spherical processing surface 5b of the processing plate 5 with a predetermined pressing force. In this state, the polishing of the lens surface 15a is started while the processing plate 5 is swung and rotated. As the polishing amount increases, the lens holder 11, the spindle 12 and the holder shaft 13 holding the lens 15 to be processed move downward. The controller 4 controls the pressing force by the air cylinder 14 via the electropneumatic regulator 18 (electronic vacuum regulator). Further, the swinging and rotation of the processing dish 5 during polishing is controlled. Instead of the electropneumatic regulator 18, two regulators (a first regulator for generating a first pressing force described later and a second regulator for generating a second pressing force described later) can be used. is there.

  A holder shaft arm 21 is horizontally attached to the upper end of the holder shaft 13. A micrometer head 22 is attached to the tip of the holder shaft arm 21 in a vertical posture. Directly below the micrometer head 22, the length measuring unit 23 is arranged at a predetermined position in an upward posture. When the holder shaft 13 is lowered along the central axis L, the lower end of the micrometer head 22 that is lowered integrally with the holder shaft 13 pushes down the measuring element 23 a that protrudes vertically upward from the length measuring unit 23. At the time of polishing of the lens 15 to be processed, the micrometer head 22 is adjusted so that the polishing start position becomes the origin position of the length measurement unit 23. Since the lens holder 11 moves in accordance with the amount of polishing when the workpiece lens 15 is polished, the movement position of the lens holder 11 from the polishing start position can be detected by the length measurement unit 23.

  In this example, the length measuring unit 23 detects that the holder shaft 13 has moved to the first position T1 and the second position T2 set in advance. Under the control of the controller 4, until the detected movement position of the holder shaft 13 reaches the first position T1, the pressing force between the lens surface 15a of the lens 15 to be processed and the spherical processing surface 5b of the processing plate 5 is changed. The polishing operation of the lens surface 15a is performed under the polishing conditions in which the first pressing force P1 and the rotational speed of the processing plate 5 are set to the first rotational speed N1. Further, until the movement position of the holder shaft 13 reaches from the first position T1 to the second position T2, the lens is subjected to polishing conditions in which the pressing force is set to the second pressing force P2 and the rotation speed is set to the second rotation speed N2. The polishing operation of the surface 15a is performed.

  The second pressing force P2 is a value lower than the first pressing force P1, and the second rotation speed N2 is a value lower than the first rotation speed N1. In the first position T1, the lens center thickness of the lens 15 to be processed is thicker than the target lens center thickness by a predetermined amount, for example, several tens of microns, under the first pressing force P1. This is the movement position of the holder shaft 13 when the polishing operation is performed. Similarly, the second position T2 is the movement of the holder shaft 13 when the polishing operation is performed until the lens center thickness of the lens 15 to be processed reaches the target lens center thickness under the second pressing force P2. Position.

  Here, the second position T2 of the holder shaft 13 under the second pressing force P2 is the processing position of the lens 15 to be processed with respect to the first position T1 of the holder shaft 13 under the first pressing force P1. In some cases, the position may be closer to the processing position, but on the other hand, the position may be further away from the processing position of the lens 15 to be processed. When the pressing force is loosened, gaps between the members arranged between the measurement position by the length measurement unit 23 and the processing position of the lens 15 to be processed held by the lens holder 11, rattling, a buffer member, or the like. As a result, the length in the direction of the central axis L becomes longer, and accordingly, the second position T2 under the second pressing force P2 is processed more than the first position T1 under the first pressing force P1. There may be a position on the side away from the position. In any case, it is only necessary to perform the polishing operation and set the positions T1 and T2 in advance. The set positions T1 and T2 are set in the length measurement unit 23. When the holder shaft 13 reaches the set positions T1 and T2, a detection signal is output to the controller 4. Further, the first pressing force P1, the second pressing force P2, the first rotation speed N1, and the second rotation speed N2 are also set in the built-in memory of the controller 4 in advance.

  In this example, the first position T1 and the second position T2 are detected using the length measurement unit 23, but two detection dial gauges may be used instead of the length measurement unit 23. In this case, the first position T1 is set on the first detection dial gauge, the second position T2 is set on the second detection dial gauge, and the holder shaft 13 reaches the first position T1 and the second position T2. This can be detected.

(Polishing operation)
An example of the polishing operation of the rocking and rotating lens polishing apparatus 1 will be described with reference to a schematic flowchart shown in FIG. First, after the lens 15 to be processed is attached to the lens polishing apparatus 1 in which the above values are set, the upper unit 3 is lowered and positioned with respect to the lower unit 2, and then the lens holder 11 is moved by the air cylinder 14. Is lowered to press the lens surface 15a of the lens 15 to be processed against the spherical processing surface 5b of the lower processing plate 5 (step ST1: holder shaft arm lowering). Further, the processing dish swinging mechanism 7 and the processing dish rotating mechanism 6 are driven to start swinging and rotating the processing dish 5 (step ST2: processing dish rotation and swinging). The polishing start position is set as the origin position of the length measurement unit 23, and is the position where the tip of the micrometer head 22 is in contact with the measuring element 23a.

  Next, the electropneumatic regulator 18 is operated to pressurize the air cylinder 14, and the lens surface 15a of the lens 15 to be processed is pressed against the spherical processing surface 5b of the processing plate 5 with the first pressing force P1 (step ST3). : Pressurization), polishing of the lens surface 15a of the lens 15 to be processed is started while the processing plate 5 is swung at a predetermined rocking speed and rotated at the first rotation speed N1.

  When the polishing under the first polishing condition (the first pressing force P1, the first rotation speed N1) proceeds, and along with this, the holder shaft 13 gradually descends from the polishing start position and reaches the first position T1, A detection signal is output from the length measurement unit 23 and input to the controller 4 (steps ST3 and ST4). Note that, based on the measurement signal from the length measurement unit 23, it may be determined that the first position T1 has been reached on the controller 4 side.

  Thereafter, the pressing force is reduced to the second pressing force P2 lower than the first pressing force P1, and the rotational speed of the processing tray 5 is decreased from the first rotational speed N1 to the second rotational speed N2. The same speed is maintained without changing the rocking speed of the processing plate 5. When polishing under this second polishing condition (second pressing force P2, second rotation speed N2) proceeds and the holder shaft 13 reaches the second position T2 along with this, a detection signal is sent from the length measurement unit 23. It is output and input to the controller 4 (steps ST5 and ST6). When this detection signal is input, the controller 4 determines that the lens center thickness of the lens 15 to be processed has reached the target thickness, stops the swinging and rotation of the processing dish 5, and pressurizes with the air cylinder 14. (Step ST7: Stop processing plate rotation, stop rocking). Note that it may be determined on the controller 4 side that the second position T2 has been reached based on the measurement signal from the length measurement unit 23.

  Thereafter, the upper unit 3 is raised and returned to the initial position, and the processed lens 15 that has been processed is removed from the lens holder 11 and moved to a predetermined position (step ST8: holder shaft arm is raised). This completes a series of polishing operations.

DESCRIPTION OF SYMBOLS 1 Lens polisher 2 Lower unit 3 Upper unit 4 Controller 5 Processing pan 5a Head 5b Spherical processing surface 5c Rotating shaft part 5d Processing pan center axis 6 Processing pan rotation mechanism 7 Processing pan rocking mechanism 8 Processing pan rotation motor 9 Deceleration Machine unit 11 Lens holder 12 Spindle 13 Holder shaft 14 Air cylinder 15 Processed lens 15a Lens surface 16 Bearing 17 Shaft holding sleeve 18 Electropneumatic regulator 21 Holder shaft arm 22 Micrometer head 23 Measuring unit 23a Measuring element

Claims (5)

In a lens polishing method using a lens polishing apparatus that polishes the lens surface while swinging and rotating the processing plate in a state where the lens surface of the processing lens held by the lens holder is pressed against the spherical processing surface of the processing plate. There,
The lens polishing apparatus includes:
A processing plate rotating mechanism for rotating the processing plate around its center axis;
A processing pan swinging mechanism for swinging the processing pan around the spherical center of the spherical processing surface;
A holder shaft that supports the lens holder so as to be rotatable around the center axis of the holder;
A pressing cylinder for applying a pressing force to press the lens surface of the lens to be processed held by the lens holder against the spherical processing surface of the processing plate via the holder shaft and the lens holder;
A detector that detects that the holder shaft has moved to a first position and a second position in a direction along the holder central axis;
Until the detected moving position of the holder shaft detected by the detector reaches the first position, the pressing force is set to the first pressing force, and the rotational speed of the processing dish is set to the first rotating speed. Under the polishing operation of the lens surface to be processed,
Until the detected moving position of the holder shaft reaches the second position from the first position, the polishing force is set to the second pressing force and the rotation speed is set to the second rotation speed. Polishing the lens surface to be processed,
The second pressing force is a value lower than the first pressing force,
The second rotation speed is a value lower than the first rotation speed,
In the first position and the second position, a distance in a direction of the holder central axis from a detection position of the holder shaft by the detector to a processing position of the lens to be processed held by the lens holder is , Measuring in advance to increase or decrease according to the pressing force, is a position set based on the measurement result,
In the first position, the polishing operation is performed under the first pressing force until the lens center thickness of the lens to be processed is thicker by a predetermined amount than the target lens center thickness. The detected movement position of the holder shaft at the time of
The second position is the detection of the holder shaft at the time when the polishing operation is performed until the lens center thickness of the lens to be processed becomes the target lens center thickness under the second pressing force. A lens polishing method, which is a moving position. In claim 1,
2. The lens polishing method according to claim 1, wherein the second position is a position away from the spherical processing surface of the processing dish with respect to the first position. In claim 1 or 2,
A lens polishing method, wherein a first detection dial gauge for detecting the first position and a second detection dial gauge for detecting the second position are used as the detector. A lens polishing apparatus that polishes the lens surface while swinging and rotating the processing plate in a state where the lens surface of the processing lens held by the lens holder is pressed against the spherical processing surface of the processing plate,
A processing plate rotating mechanism for rotating the processing plate around its center axis;
A processing pan swinging mechanism for swinging the processing pan around the spherical center of the spherical processing surface;
A holder shaft that supports the lens holder so as to be rotatable around the center axis of the holder;
A pressing cylinder for applying a pressing force to press the lens surface of the lens to be processed held by the lens holder against the spherical processing surface of the processing plate via the holder shaft and the lens holder;
A detector that detects that the holder shaft has moved to a first position and a second position in a direction along the holder central axis;
A controller for controlling the polishing operation of the lens to be processed by the processing dish based on the detection result of the detector;
The controller is
Until the detected moving position of the holder shaft detected by the detector reaches the first position, the pressing force is set to the first pressing force, and the rotational speed of the processing dish is set to the first rotating speed. Under the polishing operation of the lens surface,
Until the detected moving position of the holder shaft reaches the second position from the first position, the polishing force is set to the second pressing force and the rotation speed is set to the second rotation speed. Have the lens surface polished,
The second pressing force is a value lower than the first pressing force,
The second rotation speed is a value lower than the first rotation speed,
In the first position and the second position, a distance in a direction of the holder central axis from a detection position of the holder shaft by the detector to a processing position of the lens to be processed held by the lens holder is , Measuring in advance to increase or decrease according to the pressing force, is a position set based on the measurement result,
In the first position, the polishing operation is performed under the first pressing force until the lens center thickness of the lens to be processed is thicker by a predetermined amount than the target lens center thickness. The detected movement position of the holder shaft at the time of
The second position is the detection of the holder shaft at the time when the polishing operation is performed until the lens center thickness of the lens to be processed becomes the target lens center thickness under the second pressing force. A lens polishing apparatus characterized by being in a moving position. In claim 4,
A lens polishing apparatus comprising: a first detection dial gauge for detecting the first position; and a second detection dial gauge for detecting the second position as the detector.

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