An eyeglass lens processing apparatus includes a processing control unit (50) which in the soft processing mode, roughs the lens such that the torque threshold value is set to a value tθs lower than the threshold value tθn of a normal processing mode, and when torque detected by a sensor unit does not exceed the threshold value tθs, a axis-to-axis distance varying unit or a lens rotating unit is controlled so that a cutting amount per rotation of the lens reaches a threshold cutting amount, and when the detected torque exceeds the threshold value tθs, the axis-to-axis distance varying unit or the lens rotating unit is controlled so that the torque becomes lower than the threshold value tθs to decrease the threshold cutting amount.
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1. An eyeglass lens processing apparatus comprising:
a lens rotating unit which includes a motor for rotating a lens chuck shaft for holding an eyeglass lens;
a grindstone rotating unit which includes a motor for rotating a grindstone spindle attached with a roughing grindstone for roughing a periphery of the lens;
an axis-to-axis distance varying unit which includes a motor for varying an axis-to-axis distance between the lens chuck shaft and the grindstone spindle;
a sensor unit which includes a sensor for detecting a torque applied to the lens chuck shaft at the time of roughing of the lens by the roughing grindstone, the torque being a rotation torque for rotating the lens chuck shaft;
a mode selecting switch which switches and selects a soft processing mode for processing a slippery lens coated with a water-repellent substance and a normal processing mode for processing a lens not coated with the water-repellent substance;
a processing control unit which
in the normal processing mode, sets a torque threshold value to a value tθn, and controls the axis-to-axis distance varying unit or the lens rotating unit so that the torque detected by the sensor unit is equal to or less than the value tθn, and
in the soft processing mode, sets the torque threshold value to a value tθs lower than the value tθn, and when the torque detected by the sensor unit does not exceed the value tθs, controls the axis-to-axis distance varying unit or the lens rotating unit so that a cutting amount per rotation of the lens reaches a predetermined cutting amount, and when the detected torque exceeds the value tθs, controls the axis-to-axis distance varying unit or the lens rotating unit so that the torque becomes lower than the value tθs to decrease the cutting amount.
2. The eyeglass lens processing apparatus according to
3. The eyeglass lens processing apparatus according to
4. The eyeglass lens processing apparatus according to
5. The eyeglass lens processing apparatus according to
6. The eyeglass lens processing apparatus according to
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The present invention relates to an eyeglass lens processing apparatus for processing a periphery of an eyeglass lens.
In eyeglass lens processing apparatuses used by an optician, a mainly used apparatus is that in which while an eyeglass lens held by a lens chuck shaft is rotated, an axis-to-axis distance between a grindstone spindle attached with roughing grindstone and the lens chuck shaft is changed based on target lens shape data, and the periphery of the lens is roughened by the roughing grindstone. In roughing a plastic lens by the roughing grindstone, a down-cut system in which a rotating direction of roughing grindstone 166 and that of an eyeglass lens LE are set opposite to each other, as shown in
In the down-cut system, the generation of the axial deviation is small. However, recently, there is a water-repellent lens of which the lens surface is coated with a water-repellent substance to which water, or oil, etc., does not easily adhere. At the time of processing the water-repellent lens, axial deviation tends to occur. As a method for alleviating the axial deviation, there has been proposed a technique in which a rotation torque of a lens chuck shaft for holding a lens is detected and a lens rotation speed is decelerated so that the rotation torque does not exceed a predetermined value, or an axis-to-axis distance between the lens chuck shaft and a grindstone spindle is moved in a direction into which the distance is enlarged (JP-A-2004-25561 (US 2004-0192170)). As another method, there has been proposed a technique in which a lens is rotated at a constant speed, and an axis-to-axis distance between a lens chuck shaft and a grindstone spindle is varied so that a cutting amount while the lens makes one rotation is substantially constant (JP-A-2006-334701).
However, in the down-cut system, there is a problem in that a processing sound is larger at the time of roughing as compared to the up-cut method. To suppress the generation of the large processing sound in the down-cut system, some measures there have been introduced. However, there is no example in which the effect is actually provided. When the up-cut system is adopted, the problem of the aforementioned axial deviation is present even in a normal lens, and in the water-repellent lens, the problem of the axial deviation becomes even more conspicuous.
As a method for alleviating the axial deviation in the water-repellent lens, the technique of JP-A-2004-25561 (US 2004-0192170) was adopted in the down-cut system. As a result, due to advancement of the roughing, a case where the rotation torque is applied to a plus side opposite to the rotating direction of the lens and a case where the rotation torque is applied to a minus side which is the same direction as the rotating direction of the lens frequently occur. Thus, controlling of a change of the axis-to-axis distance or the lens rotation speed is difficult, and therefore, its application is difficult. Further, when the cutting amount increases, a permissible value of the torque applied to the lens is rapidly exceeded, and when it is controlled so that the lens is rapidly kept apart from the grindstone so as to decrease the torque, the lens chuck shaft is vibrated in up and down directions.
On the other hand, at the time of adopting the technique of JP-A-2006-334701 in the down-cut system, when a lens thickness is unknown, there is a need for estimating the thickest lens and setting the cutting amount to very small amount for the sake of safety so that no axial deviation is generated. In this case, the number of rotations of the lens is increased, and thus, the processing time is lengthened. Even when the lens thickness is measured, accurate measurement of the lens thickness is not easy, and in an astigmatic lens, the lens thickness differs depending on each radial angle, and thus, it is even more difficult to know the lens thickness over the entire lens.
An object of the present invention is to provide an eyeglass lens processing apparatus, capable of reducing generation of an axial deviation of a lens while reducing generation of a large processing sound at the time of roughing.
In order to achieve the object, the present invention provides the following arrangements.
a lens rotating unit which includes a motor for rotating a lens chuck shaft for holding an eyeglass lens;
a grindstone rotating unit which includes a motor for rotating a grindstone spindle attached with a roughing grindstone for roughing a periphery of the lens;
an axis-to-axis distance varying unit which includes a motor for varying an axis-to-axis distance between the lens chuck shaft and the grindstone spindle;
a sensor unit which includes a sensor for detecting a torque applied to the lens chuck shaft at the time of roughing of the lens by the roughing grindstone;
a mode selecting switch which switches and selects a normal processing mode and a soft processing mode;
a processing control unit which
in the normal processing mode, sets a torque threshold value to a value TθN, and controls the axis-to-axis distance varying unit or the lens rotating unit so that the torque detected by the sensor unit is equal to or less than the value TθN, and
in the soft processing mode, sets the torque threshold value to a value Tθs lower than the value TθN, and when the torque detected by the sensor unit does not exceed the value Tθs, controls the axis-to-axis distance varying unit or the lens rotating unit so that a cutting amount per rotation of the lens reaches a predetermined cutting amount, and when the detected torque exceeds the value Tθs, controls the axis-to-axis distance varying unit or the lens rotating unit so that the torque becomes lower than the value Tθs to decrease the cutting amount.
Hereinafter, an embodiment of the present invention is described based on the drawings.
A carriage portion 100 is mounted onto a base 170 of a processing apparatus main body 1. An eyeglass lens LE to be processed is held (chucked) by lens chuck shafts (lens rotating shafts) 102L and 102R of a carriage 101, and a peripheral edge of the lens is pressed and processed by a grindstone group 168 coaxially attached to a grindstone spindle 161a. The grindstone group 168 includes a roughing grindstone 162 for glass, a high curve bevel-finishing (beveling) grindstone 163 having a bevel slope to form a bevel in a high curve lens, a finishing grindstone 164 having a V groove (bevel groove) VG to form a bevel in a low curve lens and a flat processing surface, a flat polishing grindstone 165, and a roughing grindstone 166 for plastic. The grindstone spindle 161a is rotated by a motor 160. By these components, a grindstone rotating unit is configured.
The lens chuck shaft 102L is held by a left arm 101L of the carriage 101 and the lens chuck shaft 102R is held by a right arm 101R rotatably and coaxially. The lens chuck shaft 102R is moved toward the lens chuck shaft 102L by a motor 110 attached to the right arm 101R, and the lens LE is held by the two lens chuck shafts 102R and 102L. Further, the two lens chuck shafts 102R and 102L are rotated in synchronization with each other by a motor 120 attached to the left arm 101L through a rotation transmission mechanism such as a gear. Accordingly, a lens rotating mechanism is configured in this manner. A rotating shaft of the motor 120 is provided with an encoder 120a for detecting rotations of the lens chuck shafts 102L and 102R. The encoder 120a is used as a sensor for detecting a torque applied to the lens chuck shafts 102L and 102R at the time of processing the peripheral edge of the lens.
The carriage 101 is mounted on a movement support base 140 capable of moving in an X-axis direction along shafts 103 and 104 extending in parallel to the lens chuck shafts 102R and 102L and the grindstone spindle 161a. A ball screw (not shown) extending in parallel to the shaft 103 is attached to the rear portion of the support base 140, and the ball screw is attached to a rotating shaft of an X-axis movement motor 145. By the rotation of the motor 145, the carriage 101 as well as the support base 140 is linearly moved in an X-axis direction (an axial direction of the lens chuck shaft). Accordingly, these components constitute an X-axis direction moving unit. The rotating shaft of the motor 145 is provided with an encoder 146 as a detector for detecting a movement in the X-axis direction of the carriage 101.
The support base 140 is fixed with shafts 156 and 157 extending in a Y-axis direction (a direction into which an axis-to-axis distance between the lens chuck shafts 102L and 102R and the grindstone spindle 161a is changed). The carriage 101 is mounted on the support base 140 so as to be movable in a Y-axis direction along the shafts 156 and 157. A Y-axis movement motor 150 is fixed to the support base 140. The rotation of the motor 150 is transmitted to a ball screw 155 extending in the Y-axis direction, and the carriage 101 is moved in a Y-axis direction by a rotation of the ball screw 155. Accordingly, a Y-axis direction moving unit (axis-to-axis distance varying unit) is configured in this manner. A rotating shaft of the motor 150 is provided with an encoder 150a as detector for detecting a movement of the carriage 101 in the Y-axis direction.
In
A rack 211F is fixed to a lower end portion of the slide base 210F. The rack 211F meshes with a pinion 212F of an encoder 213F fixed on the attaching support base 201F. A rotation of a motor 216F is transmitted to the rack 211F via a gear 215F, an idle gear 214F, and the pinion 212F, thereby moving the slide base 210F in the X-axis direction. During the measurement of the lens edge position, the motor 216F presses the measurement portion 206F against the lens LE at the constant force all the time. The pressing force of the measurement portion 206F applied from the motor 216F to the lens refractive surface is set to a small force in order to prevent a scratch of the lens refractive surface. As means for applying a pressing force of the measurement portion 206F against the lens refractive surface, pressure applying device such as spring may be employed. The encoder 213F detects a measurement position in the X-axis direction of the measurement portion 206F by detecting the measurement position of the slide base 210F. On the basis of the movement position information, the rotating angle information of the lens chuck shafts 102L and 102R, and Y-axis movement information the edge position on the front surface of the lens LE (and the lens front surface position) is measured.
Since a configuration of the measurement portion 200R for measuring the edge of a rear surface of the lens LE is symmetric to the configuration of the measurement portion 200F, “F” of the reference numerals given to the components of the measurement portion 200F shown in
During the measurement of the lens edge position, the measurement portion 206F is brought into contact with the front surface of the lens and the measurement portion 206R is brought into contact with the rear surface of the lens. When the carriage 101 is moved in the Y-axis direction based on target lens shape data, and the lens LE is rotated n the basis of lens shape data (target lens shape data) in this state, the edge positions of the lens front surface and the lens rear surface are measured for processing a peripheral edge of the lens. In the case that the lens edge position measurement portion is configured so that the measurement portion 206F and the measurement portion 206R can integrally move in the X-axis direction, the lens front surface and the lens rear surface are separately measured.
Thus, for configurations of the carriage portion 100, and the lens edge position measurement portions 200F and 200R, those described in JP-A-2003-145328 (US 2003-087584) can be basically used, and therefore, a detailed explanation will be omitted.
It is noted that the X-axis direction moving means and the Y-axis direction moving means in the eyeglass lens processing apparatus in
Subsequently, the rotating direction of the lens LE according to the present apparatus will be explained. In the present apparatus, in order to reduce the generation of a large processing sound at the time of roughing, the up-cut system (a system in which the lens LE is rotated in the same direction as that of the roughing grindstone 166) is adopted for the rotation of the lens LE at the time of roughing. Hereinafter, explained are reasons for reducing the generation of the large processing sound in the up-cut system, which is not the case in the down-cut system.
In the down-cut system in
Subsequently, a processing operation of the present apparatus will be explained. First, an operator inputs target lens shape data of an eyeglass frame F. The target lens shape data (rn, θn) (n=1, 2, 3, . . . , N) of the eyeglass frame F measured by the eyeglass frame shape measurement portion 2 is input by depressing a switch provided in the switch portion 7 and stored into the memory 51. A target lens shape diagram FT based on the input target lens shape data is displayed on a screen 500a of the display 5. This results in a state of being capable of inputting layout data of a pupillary distance (PD value) of a wearer, a frame pupillary distance (FPD value) of the eyeglass frame F, a height of an optical center OC relative to a geometrical center FC of the target lens shape, etc. The layout data can be input by operating a predetermined touch key displayed on a screen 500b. Further, by touch keys 510, 511, 512, and 513, processing conditions such as a material quality of the lens, types of frames, a processing mode, and presence or absence of chamfering can be set.
Prior to the processing of the lens LE, the operator uses a well-known blocking device to fix a cup or fixing jig to the lens front surface of the lens LE. At this time, there are two modes, i.e., an optical center mode for fixing the cup to the optical center OC of the lens LE and a boxing center mode for fixing the cup to the geometrical center FC of the target lens shape. The optical center mode and the boxing center mode can be selected by the touch key 514. Herein, a case of using the boxing center mode will be explained. That is, the geometric center FC of the target lens shape is held to the lens chuck shafts 102R and 102L so as to serve as the rotation center of the lens (processing center of the lens).
In a water-repellent-coated slippery lens, an axial deviation tends to generate more frequently at the time of roughing. A soft processing mode used at the time of processing a slippery lens and a normal processing mode used at the time of processing a normal plastic lens not applied with water-repellent coating can be selected by the touch key 515 (mode selection switch). First, a case where the soft processing mode is selected is explained.
When a start switch of the switch 7 is depressed after the lens LE is held by the lens chuck shaft, the lens edge position measurement portions 200F and 200R are activated by the control portion 50, and the edge positions of the lens front surface and the lens rear surface are detected based on the target lens shape data. When beveling is set, path data of a bevel position is determined based on the detection result of the edge positions of the lens front surface and the lens rear surface, and the target lens shape data (a well-known method can be used to calculate bevel path data).
Upon completion of the measurement of the lens shape, the process shifts to roughing by the roughing grindstone 166. At the time of roughing, a measuring step for obtaining an outer diameter of an unprocessed lens LE is first executed. By the movement of the lens chuck shafts 102R and 102L in the X-axis direction, the lens LE is moved to a position of the roughing grindstone 166. Subsequently, the lens LE is moved to the grindstone 166 side by drive of the motor 150. At the time of starting the roughing, as shown in
rL=La−Lb−RC Equation 1
The axis-to-axis distance La is obtained based on the pulse signal from the encoder 150a when it is detected that the lens LE is in contact with the roughing grindstone 166. The distance Lb is determined from the FPD value, the PD value of layout data first input, and height data of the optical center OC relative to the geometric center FC of the target lens shape. The radius RC of the roughing grindstone 166 is a known value in terms of design, and stored in the memory 51.
Further, in the case of the boxing center mode, the geometric center FC is the lens chuck center. Thus, based on the radius rL and the layout data (data of a positional relationship between the optical center OC and the geometric center FC), the geometric center FC is replaced with lens outer diameter data (rLEn, θn) (n=1, 2, 3, . . . , N) in which FC or lens chuck center is the center.
The measurement of the outer diameter of the lens LE is preferably performed while the rotation of the roughing grindstone 166 is stopped. However, to shorten the processing time, the measurement may be performed while the roughing grindstone 166 is rotated in order to continuously perform the roughing. In this case, since the roughing grindstone 166 is rotated, a contacted portion of the lens LE is slightly ground. However, the grinding amount is a maximum of about 1 mm, and thus, the radius rL of the lens LE can be approximately obtained. With respect to management of a cutting amount described next, when a grinding amount at the time of measuring the lens outer diameter is estimated, there occurs only a small practical problem. A member to be contacted at the time of measuring the lens outer diameter includes not only the roughing grindstone 166 but also another grindstone attached to the grindstone spindle 161a.
The lens edge position measurement portion 200F or 200R may also be used as means for measuring the outer diameter of the unprocessed lens LE. For example, in the same manner as shown in
Upon completion of the obtaining step of the lens outer diameter, the process is then moved to a roughing step. Control of roughing in the soft processing mode in order to reduce the axial deviation of the lens LE at the time of roughing as a result of adoption of the up-cut system is described by using
The torque Tθ is detected by the control portion 50 based on a difference between a rotation command signal (command pulse) to the motor 120 and a detection signal (output pulse) of an actual rotating angle by the encoder 120a. Even in the up-cut system of the roughing, the threshold value Tθs in the soft processing mode is set as a value (low value in which an allowance is provided relative to a limit torque Tθr when the axial deviation is generated) that can sufficiently suppress the generation of the axial deviation, and stored in the memory 51. For example, the threshold value Tθs in the soft processing mode is 1.5 Nm (newton meters), and is a value lower than a threshold value TθN (for example, 2.6 Nm) in the normal processing mode described later.
The cutting setting amount dn in the soft processing mode is set so that the roughing grindstone 166 is not deeply cut even when the torque Tθ falls below the threshold value Tθs. In the up-cut system in which the rotating directions of the roughing grindstone 166 and the lens LE are identical, when the cutting amount D is large (the roughing grindstone 166 bites deeply into the lens LE), the force for pulling the lens LE to the grindstone 166 as indicated by the arrow FB in
The control portion 50 rotates the lens LE, and at the same time, advances the axis-to-axis distance L by the cutting setting amount dn while the torque Tθ falls below the threshold value Tθs. Thereafter, as shown in
Subsequently, when the torque Tθ detected subsequent to the time t4 falls below the threshold value Tθs, the control portion 50, this time, controls the axis-to-axis distance L so as to increase the cutting amount by a predetermined amount ΔW0 at a subsequent time t5. For example, the control portion 50 pulse-rotates the Y-axis movement motor 150 at each five pulse rotations of the lens rotating motor 120 so as to gradually reduce the axis-to-axis distance L by each certain amount. After this point onward, while the torque Tθ falls below the threshold value Tθs, the control portion 50 rotates the lens LE at a constant speed by each predetermined angle Δθ, and controls the axis-to-axis distance L to gradually increase the cutting amount by a predetermined amount ΔW0 (to increase the cutting amount by a certain inclination). Even when the torque Tθ falls below the threshold value Tθs, at a time tb at which the cutting amount D reaches a preset cutting setting amount dn, the control portion 50 controls to obtain the axis-to-axis distance L of the cutting setting amount dn.
After the second rotation of the lens, similarly, the control portion 50 controls the axis-to-axis distance L so that the torque Tθ stays under the threshold value Tθs, and when the torque Tθ falls below the threshold value Tθs, the control portion 50 controls the axis-to-axis distance L so that the cutting amount D stays under the cutting setting amount dn.
Herein, the cutting setting amount dn may be constant irrespective of the number of rotations of the lens. However, preferably, the control portion 50 increases the cutting setting amount dn in conjunction with an increase in the number of rotations n of the lens LE. When a distance rLE from the rotation center FC to the lens periphery to be roughened is long, the torque applied to the lens LE is large, and when the distance rLE is short, the torque applied to the lens LE also is small. Thus, according to the number of rotations n of the lens LE, when the cutting setting amount dn is increased as the distance rLE becomes shorter, the processing time can be shortened. For example, a cutting setting amount dn at the time of n-th rotation of the lens LE, where α denotes an increase amount of a cutting amount when the number of rotations of the lens LE increases by one rotation, is as follows:
dn=d1+(n−1)×α (n=1,2,3, . . . ) Equation 2
A first rotation of the lens LE is a cutting setting amount d1, a second rotation is d2=d1+α, and a third rotation is d3=d1+2×α . . . . Herein, the cutting setting amount d1 of the first rotation is set to an amount by which no axial deviation is generated, where average diameter and lens thickness of the lens LE are used as a reference. For example, the cutting setting amount d1 is set to 3 mm and a is set to 0.5 mm. Even when the lens thickness is thicker than the average thickness, by the change of the cutting amount by the axis-to-axis distance L based on the aforementioned detection result of the torque Tθ, the axial deviation can be suppressed.
With respect to the cutting setting amount dn after the second rotation and onward, the thus roughened outer diameter of the lens periphery is preferably used as a reference. However, this process requires a time for arithmetic process of the control portion 50. When the cutting setting amount dn is set by providing an allowance for the axial deviation, in the second rotation of the lens LE, the cutting setting amount d2 may be adopted by using the path N1 as a reference. With respect to the third rotation and onward, the preset path is similarly used as a reference, and controlled by the cutting setting amount. Even in this case, when the axis-to-axis distance L (or the rotation speed of the lens chuck shaft) is controlled so that the torque Tθ applied to the lens chuck shafts 102R and 102L does not exceed the threshold value Tθs, the substantial axial deviation can be suppressed.
By the above-described control of the axis-to-axis distance L, even when the thickness of the lens LE is not known, or even when the thickness is changed depending on the rotating angle of the lens such as an astigmatic lens, the axial deviation in conjunction with the up-cut processing can be suppressed. Further, due to the fact that the up-cut system is adopted, the generation of a large processing noise can be suppressed.
Thus, the control system of the axis-to-axis distance L by the detection of the torque Tθ is described. Further, even when a method in which the rotation speed of the lens LE is controlled is adopted, it is possible to perform processing in which the axial deviation is similarly suppressed. That is, the control portion 50 rotates the lens LE at a constant rotation speed v (speed preset so that no axial deviation is generated) while controlling the axis-to-axis distance L by the cutting setting amount dn, and when the torque Tθ exceeds the threshold value Tθs, the control portion 50 controls the rotation speed of the lens chuck shafts 102R and 102L so as to decelerate the rotation speed of the lens LE according to the difference (ΔT). When the torque Tθ falls below the threshold value Tθs, the control portion 50 gradually accelerates the rotation speed until the rotation speed v is achieved. Thereby, roughing in which the axial deviation is prevented is performed.
Subsequently, a case where the normal processing mode is selected is described. In the processing of the normal plastic lens not processed with water-repellent coating, when the normal processing mode is selected, the processing time can be shortened while suppressing the generation of the axial deviation. In the normal processing mode, the up-cut system in which the lens LE is rotated in the same direction as that of the roughing grindstone 166 is performed. As compared to the soft mode, in the normal processing mode, a value of a threshold value TθN when the axis-to-axis distance L (or the rotation speed of the lens LE) is changed by the detection of the torque Tθ is set high. For example, the threshold value Tθs in the soft mode is 1.5 Nm while the threshold value TθN in the normal processing mode is set to 2.6 Nm. Further, the cutting setting amount dn in the normal processing mode is set larger than in the soft mode. For example, the cutting setting amount d1 in the soft mode is 3 mm while the cutting setting amount d1 in the normal processing mode is set to 5 mm. When the threshold value TθN at the time the axis-to-axis distance L is changed by the detection of the torque Tθ is set higher than at the time of the soft mode, the roughing can be easily processed by the cutting setting amount dn as it is. Further, because the cutting setting amount dn in the normal mode is set larger than that in the soft mode, the number of rotations of the lens LE is reduced at the time of roughing the lens LE to the identical target lens shape. Thereby, the time for roughing is shortened.
After the roughing, the lens chuck shafts 102R and 102L are moved in the X-axis direction and the Y-axis direction, and finishing processing is performed based on the target lens shape data by the finishing grindstone 163 or 164. The finishing processing is beveling and plane edging, and these are processed according to a well-known method, and thus, the description is omitted.
Obayashi, Hirokatsu, Takeichi, Kyoji
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| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Dec 08 2008 | Nidek Co., Ltd. | (assignment on the face of the patent) | / |
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