JP4524097B2 - Spherical surface generating device and spherical surface generating method - Google Patents

Description

  The present invention relates to a spherical surface generating device and a spherical surface generating method for accurately generating a minute concave spherical surface to a desired depth with respect to an optical lens or an optical element.

  Conventionally, a spherical surface generating apparatus and a spherical surface generating method such as an optical lens and an optical element are known (see, for example, Patent Document 1). The spherical surface generating method and the spherical surface generating device disclosed in Patent Document 1 are configured as shown in FIG.

  That is, in FIG. 12, reference numeral 101 denotes an optical element which is a workpiece, and is fixed to the mounting table 102. The mounting table 102 can be pressurized upward by a pressure cylinder 103 and a guide mechanism (not shown). Further, the terminal of the micrometer 104 is in contact with the upper surface of the mounting table 102, and the height of the mounting table 102 can be detected. On the other hand, a spherical tool 105 made of a steel ball is rotatably held by a horn 106 formed into a tapered outer shape. The horn 106 is fixed to an ultrasonic oscillator 108 via a shaft body 107, and an ultrasonic output can be controlled by a controller 109.

  The horn 106, the shaft body 107, and the ultrasonic oscillator 108 constitute an upper shaft portion 110. The upper shaft portion 110 holds a spherical tool 105 by a ball screw 111, a guide mechanism (not shown) and a motor 112. It can be moved up and down. The dispenser 113 can move the tip of the needle of the dispenser 113 to the vicinity of the tool 105 and the optical element 101 by a guide (not shown), and can apply the processing liquid 114 between the spherical tool 105 and the optical element 101. It is.

  Next, the operation will be described. The optical element 101 is pressed upward by the pressure cylinder 103 and the guide mechanism while being fixed to the mounting table 102, and stops at the stroke end of the pressure cylinder 103. The upper shaft portion 110 is lowered by the ball screw 111 and the guide mechanism and the motor 112 while holding the spherical tool 105, and the tool 105 eventually comes into contact with the optical element 101.

  When lowered as it is, the mounting table 102 is pushed down by the upper shaft portion 110, and the value of the micrometer 104 changes. Upon detecting this change, the motor 112 stops and the upper shaft portion stops descending. Here, the dispenser 113 is moved by the guide mechanism, and after applying the processing liquid 114 between the tool 105 and the optical element 101, the dispenser 113 returns to the standby position. The value of the micrometer 104 at this time is stored, the value of the target machining depth is added, and the value of the micrometer 104 that should stop machining is calculated.

The ultrasonic wave whose output is controlled by the controller 109 is oscillated from the ultrasonic oscillator 108, and the tool 105 vibrates via the shaft body 107 and the horn 106. This vibration causes friction between the machining liquid 114 and the optical element 101, and the optical element 101 is gradually scraped, eventually forming a shape opposite to the tool 105, that is, a concave surface. When the concave surface is formed on the optical element 101, the tool 105 is recessed into the optical element 101 correspondingly, and the mounting table 102 gradually rises. When the value of the micrometer 104 reaches a value at which machining is to be stopped, the output of the ultrasonic wave is stopped and the machining is terminated. Then, a concave surface having substantially the same radius as the tool 105 is formed on the optical element 101 at the target depth. It is formed.
JP-A-11-333702

  The spherical surface generating method and the spherical surface generating device disclosed in Patent Document 1 detect the target processing depth by the micrometer 104. However, since the processing is performed by vibration generated by the ultrasonic oscillator 108, the micrometer 104 at the time of processing is used. The value of becomes a state where chattering having a certain amplitude is generated. Therefore, even if the processing stops when the value of the micrometer 104 during chattering becomes a value to stop processing for a moment, the actual concave surface of the optical element 101 often does not reach the target depth. . Due to the occurrence of chattering, it is difficult to detect the exact target concave surface depth of the optical element 101 from the value of the micrometer 104.

  For this reason, the timing for stopping the ultrasonic oscillation is required to have a certain time lag after the micrometer 104 detects a value to stop processing, but the processing speed of the concave surface advances. As the speed gradually increases, the machining speed is not constant. Also, the processing speed changes due to variations in the shape and amount of abrasive grains in the applied processing liquid 114, variations in the surface accuracy of the tool 105, and variations in the processing surface shape of the optical element 101. The processing speed cannot be constant. Therefore, even if the processing is finished with the same time lag, the concave depth of the optical element 101 varies, making it difficult to produce the target concave depth.

  The present invention has been made paying attention to the above circumstances, and the object of the present invention is that a workpiece having an accurate target concave surface depth can be obtained without being affected by variations in the machining fluid, tool, and workpiece. It is an object to provide an obtained spherical surface forming apparatus and a spherical surface generating method.

In order to achieve the object, the invention according to claim 1 has a spherical tool for processing a concave spherical surface on a workpiece and a holding portion for holding the tool at one end, and is held by the holding portion. A horn that ultrasonically vibrates the tool with ultrasonic waves from an ultrasonic oscillator, and the workpiece is disposed so as to face the tool held by the horn, and the workpiece is fixed, and the machining is performed during machining. A predetermined load is applied to the mounting table that can be moved to the tool side according to the amount, the tool that has been ultrasonically vibrated through the horn by the ultrasonic wave from the ultrasonic oscillator, and the workpiece. a pressurizing means you creating a concave spherical surface on the workpiece by contact is allowed by the tool, a measuring means for measuring the amount of displacement of the mounting table generated by the processing of the tool, the displacement amount measured by the measuring means Value equivalent to machining target value After reaching even to continue the ultrasonic vibration of the tool, and a controller for stopping the ultrasonic vibration of the tool with a time lag, height target value of the mounting table to move to the pressing direction of the pressing means A stopper for fixing the mounting table to the position corresponding to the position, a positioning means for moving the stopper to determine the position of the stopper at a position corresponding to the target value, and a working fluid containing abrasive grains And a machining fluid supply means for supplying a machining fluid supply means to a contact portion between the workpiece and the tool.

According to a second aspect of the present invention, a spherical tool is held in a holding portion of a horn connected to an ultrasonic oscillator, and a stopper at a position facing the pressing direction of the mounting table on which a workpiece is mounted is mounted. In a state where the workpiece is in contact with the workpiece, the workpiece is brought into contact with the tool with a predetermined load by a pressurizing means, and a working fluid containing abrasive grains is supplied to the contact portion between the tool and the workpiece, After the position of the mounting table at this time is stored by a measuring means for measuring the amount of displacement of the mounting table, the stopper is moved in the pressurizing direction of the mounting table by the target machining depth and fixed at that position. , The tool is ultrasonically vibrated through the horn to create a concave spherical surface on the workpiece, and the displacement of the mounting table generated along with the creation of the concave spherical surface is measured by the measuring means. Continue ultrasonic vibration even after the measured value reaches the target value. Determines that the mounting table before with a time lag is in contact with the stopper stops the ultrasonic vibration, a spherical creation processing method, characterized in that the machining end.

  According to the present invention, it is possible to mass-produce a workpiece having a more accurate concave processing depth without being affected by chattering.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a spherical surface generating apparatus showing the first embodiment. Reference numeral 1 denotes an optical element which is a workpiece, and is fixed to the mounting table 2. The mounting table 2 can be pressurized upward by a pressure cylinder 3 as a pressure means and a guide mechanism (not shown). Moreover, the terminal 4a of the micrometer 4 as a measuring means is in contact with the upper surface of the mounting table 2 so that the height of the mounting table 2 can be detected. A stopper 12 is in contact with the upper surface of the other mounting table 2. The stopper 12 can be moved up and down via a nut 15 by a ball screw 13, a guide mechanism (not shown) and a servo motor 14 as positioning means.

  On the other hand, the spherical tool 5 made of a steel ball is held by a horn 6 formed into a tapered outer shape so as to be freely rollable. The horn 6 is fixed to the ultrasonic oscillator 8 through the shaft body 7, and the ultrasonic output can be controlled by the ultrasonic controller 16. The horn 6, the shaft body 7, and the ultrasonic oscillator 8 constitute an upper shaft portion 9. The upper shaft portion 9 can be raised and lowered while holding the tool 5 by a ball screw 18 and a guide mechanism (not shown) and a servo motor 19 via a nut 17. The dispenser 20 as the processing liquid supply means can move the tip of the needle 20a of the dispenser 20 to the vicinity of the tool 5 and the optical element 1 by a guide (not shown). It is possible to apply.

  Next, the operation of the first embodiment will be described based on FIGS. In FIG. 2, the pressurizing cylinder 3 lifts the mounting table 2 and the optical element 1 with a certain pressurizing force, and stops at the upper end stroke end of the pressurizing cylinder 3. At this time, the servo motor 14 is not excited, and the stopper 12 is lowered by its own weight of the stopper 12 and the nut 15 and is in contact with the upper end of the mounting table 2.

  The pressurizing force of the pressurizing cylinder 3 is larger than the total weight of the mounting table 2, the optical element 1, the terminal 4 a of the micrometer 4, the stopper 12, and the nut 15. The upper stroke end of 3 remains. On the other hand, the tool 5 is held on the upper shaft portion 9 so as to be freely rollable. In FIG. 3, the upper shaft portion 9 is lowered by a servo motor 19 through a nut 17 and a ball screw 18. Eventually, the tool 5 comes into contact with the optical element 1, and the upper shaft portion 9 pushes down the optical element 1, the mounting table 2, the terminal 4 a of the micrometer 4, the stopper 12, and the nut 15. Within the stroke range of the pressure cylinder 3, the servo motor 19 stops and the upper shaft part 9 also stops.

  The device controller (not shown) stores the current position of the mounting table 2 and the current position of the stopper 12 from the value of the micrometer 4 and the value of the encoder of the servo motor 14 at this time. By adding the preset target concave surface depth to the current value of the micrometer 4, the present device controller (not shown) determines the value of the micrometer 4 at which machining should be stopped and the position of the stopper 12 at the time of machining. calculate.

  In FIG. 4, the dispenser 20 protrudes by a guide mechanism (not shown), and after applying the processing liquid 10 between the tool 5 and the optical element 1, the dispenser 20 returns to the standby position by the guide mechanism. In FIG. 5, the servo motor 14 is excited, and the stopper 12 is raised through the ball screw 13 and the nut 15 to the position at the time of machining calculated by the apparatus controller (not shown) and stopped. The slight gap 11 between the mounting table 2 and the stopper 12 at this time corresponds to the target concave surface processing depth.

  In FIG. 6, the ultrasonic wave whose output is controlled by the ultrasonic controller 16 is output from the ultrasonic oscillator 8, and the tool 5 vibrates through the shaft body 7 and the horn 6, and the friction between the machining liquid 10 and the optical element 1 causes the vibration. The optical element 1 is gradually scraped and the machining is started. A concave spherical surface almost the same as the radius of curvature of the tool 5 begins to be formed on the optical element 1, and the spherical tool 5 is shaped to be recessed into the optical element 1. It begins to rise gradually while chattering. As the mounting table 2 rises, the terminal 4a of the micrometer 4 also starts to rise, and the value of the micrometer 4 starts to change.

  In FIG. 7, the micrometer 4 becomes a target value to be processed, and this apparatus controller (not shown) detects this, but the processing is continued for a certain time. Eventually, when the upper surface of the mounting table 2 completely comes into contact with the stopper 12, the pressure applied to the tool 5 above the optical element 1 disappears, and chattering also stops.

  In FIG. 8, the apparatus controller (not shown) outputs a machining stop command due to a sufficiently long time lag, and the ultrasonic controller 16 stops the output. In FIG. 9, the upper shaft portion 9 is lifted by the servo motor 19 via the nut 17 and the ball screw 18 while holding the tool 5, and the machining is completed.

  According to the first embodiment, the processing is continued even when the micrometer 4 reaches a target value to be processed, but when the upper surface of the mounting table 2 is completely in contact with the stopper 12, the processing with respect to the tool 5 is performed. The pressing force above the optical element 1 is lost, chattering is stopped, and the processing does not proceed. Therefore, even if the processing is finished with a sufficient time lag, the processing depth of the concave surface of the optical element 1 after the processing is always the same as the gap 11 and is constant, and high-precision processing without variations is possible.

  10 and 11 show a second embodiment, and the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In this embodiment, the first embodiment is improved and a chuck 21 and a chuck cylinder 22 capable of forcibly fixing the stopper 12 at the current position are added.

  FIG. 10 shows the same process as that of FIG. 5 in the first embodiment. When the servo motor 14 is excited, the stopper 12 is moved to the position of the ball screw calculated by the apparatus controller (not shown). 13. Raise through the nut 15 and stop. The slight gap 11 between the mounting table 2 and the stopper 12 at this time corresponds to the target concave surface processing depth. Here, when the chuck cylinder 22 closes the pawl, the chuck 21 sandwiches the stopper 12 from both sides and fixes the stopper 12 at the current position. After fixing, the excitation of the servo motor 14 is released again.

  FIG. 11 shows the same process as the process of FIG. 7 in the first embodiment, in which the processing progresses and the upper surface of the mounting table 2 is in contact with the stopper 12. 22 and the chuck 21 continue to fix the stopper 12 and release the fixing when the upper shaft portion 9 is lifted after finishing the processing.

  According to the second embodiment, in addition to the effects of the first embodiment, the stopper 12 is not fixed by the excitation of the servo motor 14 but forcedly by the pressure of the chuck 21 driven by the chuck cylinder 22. Therefore, when the processing proceeds and the upper surface of the mounting table 2 comes into contact with the stopper 12, the stopper 12 can be reliably fixed without being affected by chattering from the mounting table 2. Therefore, an optical element having a concave processing depth with higher accuracy than in the first embodiment can be obtained.

  According to the said structure, the following structures are obtained.

  (Supplementary note 1) A spherical tool for processing a concave spherical surface on a workpiece and a holding part for holding the tool so as to roll freely are provided at one end, and the tool held in the holding part is supplied from an ultrasonic oscillator. A horn that is ultrasonically vibrated by ultrasonic waves, a mounting table that fixes the work piece so as to face the tool held by the horn, and the tool and the work piece that are applied with a predetermined load. A pressurizing means for contacting, a measuring means for measuring a displacement amount of the mounting table generated by processing of the tool, a stopper capable of fixing the height of the mounting table facing the pressing direction of the pressing means, A spherical generating apparatus comprising: positioning means capable of raising and lowering the stopper; and processing liquid supply means for supplying a processing liquid containing abrasive grains to a contact portion between the workpiece and the tool.

  (Additional remark 2) The spherical surface creation apparatus of Additional remark 1 characterized by the said pressurizing means being a pressurization cylinder.

  (Supplementary note 3) The spherical surface generating apparatus according to supplementary note 1, wherein the measuring means is a micrometer.

  (Supplementary note 4) The spherical surface generating apparatus according to Supplementary note 1, wherein the positioning means is a servo motor and a ball screw driven by the servo motor.

  (Supplementary note 5) The spherical surface generating apparatus according to supplementary note 1, wherein the positioning means is a chuck and a chuck cylinder for driving the chuck.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, you may combine suitably the component covering different embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic structure figure of the spherical surface creation processing apparatus which shows 1st Embodiment of this invention. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. The schematic block diagram of the spherical surface creation processing apparatus which shows 2nd Embodiment of this invention. Operation | movement explanatory drawing of the spherical surface creation processing apparatus which shows the same embodiment. The schematic block diagram of the spherical surface creation processing apparatus in a prior art.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Optical element (workpiece), 2 ... Mounting stand, 3 ... Pressure cylinder (pressurization means), 4 ... Micrometer (measurement means), 5 ... Tool, 6 ... Horn, 7 ... Shaft, 8 ... Ultrasonic oscillator, 9 ... upper shaft portion, 10 ... machining fluid, 11 ... gap, 12 ... stopper, 13 ... ball screw, 14 ... servo motor (positioning means), 15 ... nut, 16 ... ultrasonic controller, 17 ... nut, DESCRIPTION OF SYMBOLS 18 ... Ball screw, 19 ... Servo motor, 20 ... Dispenser (working fluid supply means), 21 ... Chuck, 22 ... Chuck cylinder

Claims (2)

A spherical tool for machining a concave spherical surface on the workpiece;
A horn for holding the tool at one end, and ultrasonically vibrating the tool held by the holding part with ultrasonic waves from an ultrasonic oscillator;
The work piece is placed so as to face the tool held by the horn, the work piece is fixed, and a mounting table that can move to the tool side according to the amount of work during processing ,
A concave spherical surface is created on the workpiece by the tool by applying a predetermined load to the workpiece which is ultrasonically vibrated through the horn by ultrasonic waves from the ultrasonic oscillator. and a pressure means you,
Measuring means for measuring the amount of displacement of the mounting table generated by machining the tool;
A controller that continues the ultrasonic vibration of the tool even after the displacement measured by the measuring means reaches a value corresponding to a target value for machining, and stops the ultrasonic vibration of the tool with a time lag,
A stopper for fixing the mounting table at the position when the height of the mounting table moving in the pressurizing direction of the pressing means reaches a position corresponding to a target value ;
Positioning means for moving the stopper to determine the position of the stopper at a position corresponding to the target value ;
A working fluid supply means for supplying a working fluid containing abrasive grains to a contact portion between the workpiece and the tool;
A spherical surface generating device characterized by comprising: In a state where the spherical tool is held in the holding portion of the horn connected to the ultrasonic oscillator, and the stopper at the position facing the pressing direction of the mounting table on which the workpiece is mounted is in contact with the mounting table, The workpiece is brought into contact with the tool with a predetermined load by a pressurizing means, and a working fluid containing abrasive grains is supplied to a contact portion between the tool and the workpiece, and the position of the mounting table at this time Is stored by the measuring means for measuring the displacement amount of the mounting table, and then the stopper is moved in the pressurizing direction of the mounting table by the target machining depth and fixed at the position, and the tool is inserted through the horn. Is created by oscillating the workpiece to create a concave spherical surface on the workpiece, and measuring the displacement of the mounting table as a result of creation of the concave spherical surface by the measuring means, and the measured value reaches a target value. Continue the ultrasonic vibration after the It determines that the mounting base is in contact with the stopper stops the ultrasonic vibration, the spherical creation processing method characterized by the processing ends.

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