JP4743649B2 - Curved surface polishing apparatus and curved surface polishing method - Google Patents

Description

The present invention is for polishing an optical element having a free curved surface, for example, various parts having a complicated curved surface such as an fθ lens used in a laser beam printer or a digital copying machine, and a mold for molding the same with high accuracy. The present invention relates to a polishing apparatus and a processing method thereof.
The present invention can be widely used not only for a polishing apparatus and its processing method but also for speed control of a tool, a robot arm or a measurement probe that scans a curved surface by a copying operation. It can also be used as a control method for multi-axis control machines in certain cutting and grinding processes.

  Along with the downsizing of optical systems, the number of free-form optical elements having no rotational symmetry axis is increasing. As an apparatus for polishing such an optical element or a mold for molding the optical element, a processing method is implemented in which a part of the polishing tool is brought into approximate point contact and this contact point is scanned to process the entire processing surface. Yes. As the tool is scanned, the tilting posture control is performed so that the angle between the polishing load direction and the normal vector set at the workpiece point is always constant. Therefore, the polishing device requires multi-axis control. Yes. As an axis configuration, a configuration that includes at least a four-axis configuration of an X axis and a Y axis, which are linear movement axes, and an A axis and a B axis that rotate about axes parallel to these axes is generally used.

  In polishing for correcting the shape of a free-form surface, a technique for controlling the tool residence time on the work surface is widely used by utilizing Preston's empirical formula that the tool residence time is proportional to the removal depth. Such a technique is often called polishing by residence time control. In order to perform dwell time controlled polishing, it is necessary to strictly control the speed on the trajectory of the polishing tool. However, in the multi-axis control polishing apparatus in which the rotational movement axis and the linear movement axis as described above are combined, the mechanism is complicated, and in order to obtain a predetermined speed on the processing surface, X, Y, A, B What speed command should be issued for each axis cannot be easily determined, and is usually calculated by a CAM system for a multi-axis machine.

  In response to such a problem, Japanese Patent Laid-Open No. 2003-195917 discloses a mechanism in which interpolation points are formed on the tool trajectory at intervals required for speed control, and the coordinates are converted as control points on machine coordinates. And a configuration in which this is incorporated into a processing machine controller is disclosed. In this method, the NC data itself can be simplified, but the amount of calculation in the controller increases. Therefore, an expensive controller having high-speed calculation processing capability is required to ensure the operation speed. . In the polishing process, since the copying operation is performed on the surface to be processed, it is not necessary to form a tool path having a bend in the polishing load direction strictly by NC control.

  Japanese Patent Laid-Open No. 2002-210654 discloses a polishing controller that considers copying operation and places importance on dwell time control. Here, a tool locus in a workpiece coordinate system is converted into machine coordinates for operation commands inside the controller. As the speed command, a configuration is disclosed in which the dwell time is directly used as the command value as the operation completion time of each block of NC data (= command of one line). According to this method, it is possible to command a dwell time corresponding to the feed speed even when the amount of movement of each axis converted into machine coordinates is unknown. However, this method also requires an expensive controller with a special specification that has a high-speed calculation processing capability and operates with a time command because the amount of calculation inside the controller increases.

Japanese Patent Laid-Open No. 2003-195917 JP 2002-210654 A

  In view of the above problems, an object of the present invention is to operate a multi-axis control polishing apparatus with accurate dwell time control by an inexpensive and general-purpose processing machine controller, taking advantage of polishing by a copying operation. In particular, in a general-purpose controller, an NC data format called G code is standard, and the above-described problem is realized in a form adapted to this.

The solution to the above problem is that at least one of the linear movement axis or the rotation movement axis is the master axis and the other axis is the slave axis, the feed rate command value is given to the master axis, and the slave axis is the master axis. Basically, the control is performed by changing the tool contact point at a predetermined speed on the surface to be processed.
In order to solve the above-mentioned problem, the coordinate conversion for machine operation command that has been provided in the controller in the conventional example is performed in advance and converted into NC data, thereby reducing the burden on the controller and using the G code format. It was possible. The calculation of the feed rate required for dwell time control is limited to a specific axis for giving a control command, so that the accuracy of dwell time control is not degraded, and an extremely simple and expensive multi-axis CAM system is not required. did. A processing machine must have a synchronous control mechanism in which a specific axis is a master axis and another axis is a slave axis, and the master axis must have a function that can be switched to an arbitrary axis during processing. In addition, as a method of calculating the feed rate required for dwell time control, it is calculated based on the ratio of the actual trajectory length generated by the tool tip following the copying operation and the master axis movement amount in the NC data commanded to the processing machine. By doing so, it became possible to derive the feed rate with a very simple calculation.

[Solution 1] (corresponding to claim 1)
The solution 1 taken to solve the above-mentioned problem is that when the tool is brought into approximate point contact with a part of the surface to be processed, the tool contact point is scanned, and the entire surface of the surface to be processed is processed. A control method of a multi-axis control polishing apparatus having two or more axes that performs an inclination posture control so that an angle formed by a polishing load direction and a normal vector set on the work surface at the tool contact point is always constant. There,
When the tool scanning is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotational movement axis, the feed speed command value with at least one control axis as master axis and other axes as slave axes Is applied to the master axis, the master axis performs positioning control with respect to the command value, the slave axis performs synchronous follow-up control with respect to the master axis, and the tool contact point is changed and controlled at a predetermined speed on the work surface. While scanning.
[Operation]
When the tool scanning is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotational movement axis, the feed speed command value with at least one control axis as master axis and other axes as slave axes Is given to the master axis, the master axis performs positioning control with respect to the command value, and the slave axis is configured to perform synchronous tracking control with respect to the master axis, making it easy to focus on the amount of movement of the specific control axis. In addition, since it is possible to instruct the feed speed necessary for the residence time control, it is possible to instruct an accurate feed speed.

[Solution 2] (corresponding to claim 2)
The solution 2 taken to solve the above problem is that the tool is brought into point contact with a part of the surface to be processed, the tool contact point is scanned, and the entire surface of the processing surface is processed. In a multi-axis control polishing apparatus having two or more axes that performs an inclination posture control so that an angle formed by a polishing load direction and a normal vector set on the work surface at the tool contact point is always constant,
When the tool scan is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotary movement axis, feed speed command with at least one linear movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control by the position feedback mechanism, the slave axis performs synchronous tracking control with respect to the master axis, and the tool contact point is changed at a predetermined speed on the work surface. Scanning while controlling.
[Operation]
When the tool scan is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotary movement axis, feed speed command with at least one linear movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control by the position feedback mechanism, and the slave axis performs synchronous tracking control with respect to the master axis, so that only the amount of movement of a specific linear movement axis is focused. Thus, since it is possible to easily command the feed speed necessary for the residence time control, it is possible to command an accurate feed speed even in a shape in which the rotational movement shaft hardly moves.

[Solution 3] (Corresponding to Claim 3)
The solution means 3 taken to solve the above problem is that the tool is brought into point contact with a part of the surface to be processed, the tool contact point is scanned, and the entire surface of the processing surface is processed. In a multi-axis control polishing apparatus having two or more axes that performs an inclination posture control so that an angle formed by a polishing load direction and a normal vector set on the work surface at the tool contact point is always constant,
When the tool scan is in the simultaneous control state of multiple axes that are a combination of linear movement axis and rotational movement axis, feed speed command with at least one rotational movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control by the position feedback mechanism, the slave axis performs synchronous tracking control with respect to the master axis, and the tool contact point is changed at a predetermined speed on the work surface. Scanning while controlling.
[Operation]
When the tool scan is in the simultaneous control state of multiple axes that are a combination of linear movement axis and rotational movement axis, feed speed command with at least one rotational movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control by the position feedback mechanism, and the slave axis performs synchronous tracking control with respect to the master axis, paying attention only to the movement amount of the specific rotational movement axis. Thus, since it is possible to easily instruct the feed speed necessary for the residence time control, it is possible to instruct an accurate feed speed even in a shape in which the linear movement axis hardly moves.

[Solution 4] (corresponding to claim 4)
The solving means 4 taken to solve the above problem is that the tool is brought into point contact with a part of the surface to be processed, the tool contact point is scanned, and the entire surface of the processing surface is processed. A control method of a multi-axis control polishing apparatus having two or more axes that performs an inclination posture control so that an angle formed by a polishing load direction and a normal vector set on the work surface at the tool contact point is always constant. There,
When the tool scan is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotary movement axis, feed speed command with at least one linear movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control with respect to the command value, the slave axis performs synchronous tracking control with respect to the master axis, and the tool contact point is changed at a predetermined speed on the work surface. the scanning in the basic form while, by changing the master axis to any rotary movement axis during pressurization Engineering, is to perform switching to the other axis as a slave axis.

[Operation]
When the tool scan is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotary movement axis, feed speed command with at least one linear movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control with respect to the command value, and the slave axis performs synchronous tracking control with respect to the master axis. Depending on the situation, the master axis can be rotated freely during machining. By changing to a moving axis, it is possible to sequentially switch so that the other axis is a slave axis. Depending on the curved surface shape to be machined, there may be a mixture of shapes in which the rotational movement axis hardly moves and shapes in which the linear movement axis hardly moves. By setting the minimum movement amount of the master axis and switching the master axis in a tool path less than this, it is possible to always instruct a feed speed necessary for accurate dwell time control for various curved surface shapes.

[Embodiment 1] (corresponding to claim 5)
The embodiment 1 is a control method of the multi-axis control polishing apparatus of the solving means 2, wherein the command value of the feed speed given to the master axis is a moving distance per unit time.
[Operation]
The command value of the feed speed given to the master axis can be used as a moving distance per unit time such as mm / min, so that a general-purpose controller compatible with the G code format can be used, and the interpolation function provided by this can be used as it is. can do.

[Embodiment 2] (corresponding to claim 6)
The embodiment 2 is a control method of the multi-axis control polishing apparatus of the solving means 3, wherein the command value of the angular velocity given to the master shaft is the amount of change in angle per unit time.
[Operation]
The command value of the feed speed given to the master axis is an angular speed such as deg / min, so that a general-purpose controller corresponding to the G code format can be used as in the first embodiment. Can be used as is.

[Embodiment 3] (corresponding to claim 7)
The embodiment 3 is a control method of the multi-axis control polishing apparatus of the solution means 4, wherein the master axis can be switched to an arbitrary axis for each command (block ) of NC data by a command from the NC data. It is possible.
[Operation]
Master axis, by a command from the NC data, since it is possible to switch any axis for each command of a single line of NC data, performed operations of the above solution 4 in unmanned operation, and for a variety of curved surface It becomes possible.

[Embodiment 4] (corresponding to claim 8)
Embodiment 4 is the control method of the multi-axis control polishing apparatus according to Solution 4 or Embodiment 3 described above, and when the master axis is a linear movement axis, the command value of the feed rate applied to the master axis is the movement per unit time. When the master axis is a rotational movement axis, the command value of the angular velocity given to the master axis is the amount of change in angle per unit time.
[Operation]
When the master axis is a linear movement axis, it is the movement distance per unit time, and when the master axis is a rotation movement axis, it is the amount of angular change per unit time. Since the format can be used, a general-purpose controller corresponding to the G code format can be used.

[Embodiment 5] (corresponding to claim 9)
Embodiment 5 is the multi-axis control polishing apparatus according to Solution 2 or Solution 3, wherein the linear movement axis is X, Y orthogonal 2 axes or X, Y, Z orthogonal 3 axes, and the polishing load direction is Z axis. In this case, the rotational movement axis is composed of two axes, an A axis having a rotational movement axis parallel to the X axis and a B axis having a rotational movement axis parallel to the Y axis, and the total number of control axes is four or five. It is an axis | shaft structure and the axis of rotation of A axis and B axis is orthogonal.
[Operation]
When the linear movement axis is two orthogonal axes of X, Y or three orthogonal axes of X, Y, Z and the polishing load direction is the Z axis, the rotational movement axis is an A axis having a rotational movement axis parallel to the X axis, It consists of two axes, the B axis, which has a rotational movement axis parallel to the Y axis. The total number of control axes is four or five. The rotational movement axis is normal to the polishing load direction and the machining point. This is an axis that performs attitude control to match the vectors, and this is not always possible with the B, C, A, and C axes, but the NC data is easier to create and positioning with the A and B axes configuration. The configuration is also excellent in terms of accuracy.

[Solution 5] (Corresponding to Claim 10)
Solution 5 taken in order to solve the above-mentioned problem is the multi-axis control polishing apparatus according to Solution 2, or the control method of the multi-axis control polishing apparatus according to Solution 4, wherein the multi-axis control polishing apparatus NC data creation method for driving
The feed speed command value given to the linear movement axis in the NC data is F, the desired tool feed speed on the work surface is f, and the NC data is operated by a command command of one line of NC data by the linear movement axis in the NC data ( When the movement distance between blocks) is Lm and the tool scanning trajectory length on the work surface is Ls,
The above F is calculated by the following equation.
F = f × (Lm / Ls)
[Operation]
As NC data creation method for driving the multi-axis control polishing apparatus, F is the feed speed command value given to the linear movement axis in NC data, f is the desired tool feed speed on the work surface, and NC data F is calculated by the following equation, where Lm is the movement distance during operation by a command command of one line of NC data by the linear movement axis, and the tool scanning trajectory length Ls on the work surface is: It is possible to derive the feed rate for accurate residence time control with a simple calculation formula.
F = f × (Lm / Ls)

[Solution 6] (Corresponding to Claim 11)
The solution means 6 taken to solve the above problem is the multi-axis control polishing apparatus described in the solution means 3 or the control method of the multi-axis control polishing apparatus described in the solution means 4 in the multi-axis control polishing apparatus. NC data creation method for driving
The angular velocity command value given to the rotational movement axis in the NC data is F, the desired tool feed speed on the surface to be processed is f, and the NC data is operated by the command command of one line of NC data by the rotational movement axis in the NC data (block ) And the tool scanning trajectory length on the work surface is Ls,
The above F is calculated by the following equation.
F = f × (θ / Ls)
[Operation]
As NC data creation method for driving multi-axis control polishing equipment, F is the feed rate command value given to the rotational movement axis in NC data, f is the desired tool feed rate on the work surface, and it is rotated within NC data. F is calculated by the following equation, where θ is the movement angle during operation according to the command command of one line of NC data by the movement axis, and Ls is the tool scanning trajectory length on the work surface. It is possible to derive the feed rate for accurate residence time control with a simple calculation formula. Even in a shape where the linear movement axis hardly moves, an accurate feed speed can be commanded.
F = f × (θ / Ls)

[Solution 7] (Corresponding to Claim 12)
The solution means 7 taken to solve the above problem is the NC data generation method of the solution means 5 or 6, wherein the tool scanning trajectory length Ls on the work surface is determined on the work surface. This is an NC program creation method for approximating a tool scanning locus with an arc.
[Operation]
In the NC data creation method, the tool scanning distance Ls on the work surface is obtained by approximating the tool path on the work surface with an arc. In normal optical surface polishing, Ls by a command (one block ) of NC data is 1 mm or less, and in the case of an fθ lens optical surface, the minimum curvature radius is about 10 mm. There is no problem in accuracy even if a non-arc trajectory is replaced with an arc.

[Solution 8] (Corresponding to Claim 13)
The solving means 8 taken to solve the above problems is the above-described solving means 1, the solving means 4, or the control method of the multi-axis controlled polishing apparatus according to any one of the first to fourth embodiments, and the solving means. 2, the multi-axis control polishing apparatus according to any one of the solving means 3 or the embodiment 5, the NC data creation method according to the solving means 5 or 6 or the NC program according to the solving means 7 A curved surface polishing method using at least one of the preparation methods.
[Operation]
High-precision shape correction polishing using dwell time control can be performed by the configuration of a general-purpose NC controller and a multi-axis control polishing apparatus. Also, the creation of NC data necessary for machining can be easily performed without requiring an expensive CAM system.

[Solution 9] (corresponding to claim 14)
The solution means 9 taken to solve the above-mentioned problems is the control method of the multi-axis control polishing apparatus according to any one of the solution means 1, the solution means 4, or the embodiments 1 to 4, and the solution means. 2, the multi-axis control polishing apparatus according to any one of the solving means 3 or the embodiment 5, the NC data creation method according to the solving means 5 or 6 or the NC program according to the solving means 7 An optical element processed using at least one of the production methods or a mold thereof.
[Operation]
High-accuracy shape correction polishing using dwell time control can be performed with the configuration of a general-purpose NC controller and multi-axis control polishing apparatus, so high-precision optical elements or their molds are processed relatively inexpensively. It is possible.

The effects of the present invention are summarized for each main claim as follows.
(1) Invention according to claim 1
The command value of the feed speed is given to the control axis which is the master axis, the master axis performs positioning control with respect to the command value, and the slave axis performs synchronous tracking control with respect to the master axis. Paying attention only to the amount of movement, it is possible to simply command the feed speed necessary for the residence time control, so it is possible to command an accurate feed speed. Thus, since one common speed command value can be given to the operation of the linear movement axis and the rotational movement axis, the interpolation function such as the linear interpolation of the general-purpose NC controller can be utilized as it is. .

(2) The invention according to claim 2 The command value of the feed speed is given to the linear movement axis which is the master axis, the master axis performs positioning control by the position feedback mechanism, and the slave axis performs synchronous tracking control with respect to the master axis. By adopting the form, it is possible to easily command the feed speed necessary for the dwell time control by paying attention only to the amount of movement of the specific linear movement axis. The feed rate can be commanded. Thus, since one common speed command value can be given to the operation of the linear movement axis and the rotational movement axis, the interpolation function such as the linear interpolation of the general-purpose NC controller can be utilized as it is. .

(3) The invention according to claim 3 The feed rate command value is given to the rotational axis that is the master axis, the master axis performs positioning control by the position feedback mechanism, and the slave axis performs synchronous tracking control with respect to the master axis. By adopting the form, it is possible to directly command the angular velocity necessary for the dwell time control by paying attention only to the movement amount of the specific rotational movement axis, so that the linear movement axis is like a specific concave cylinder shape. Even in a shape that hardly moves, an accurate feed speed can be commanded. Thus, since one common speed command value can be given to the operation of the linear movement axis and the rotational movement axis, the interpolation function such as the linear interpolation of the general-purpose NC controller can be utilized as it is. .
(4) The invention according to claim 4 Since the master axis can be sequentially switched from the linear movement axis to the rotation movement axis or vice versa for each command (one block) in one line , the rotation movement axis is almost moved. It is possible to cope with processing of various curved surface shapes in which shapes that do not move and shapes in which the linear movement axis hardly moves are mixed.
One common speed command value can be given to the operations of the linear movement axis and the rotational movement axis, and the interpolation function such as linear interpolation of the general-purpose NC controller can be utilized as it is.

(5) Invention according to claim 5
By setting the feed rate command value given to the master axis to the movement distance per unit time, a general-purpose controller corresponding to the G code format can be used, and the interpolation function provided by this can be used as it is. .
(6) The invention according to claim 6 The command value of the feed speed given to the master shaft is an angular speed, and a general-purpose controller corresponding to the G code format is used as in the invention according to claim 5. It is possible to use the interpolation function as it is.

(7) The invention according to claim 7 Since the master axis can be switched to an arbitrary axis for each command of one line of NC data by a command from NC data, the operation of the invention according to claim 4 is unmanned. It can be implemented for various curved surfaces by driving.
(8) The invention according to claim 8 When the master axis is a linear movement axis, it is the movement distance per unit time, and when the master axis is a rotation movement axis, it is the angle change amount per unit time. Similarly to the invention according to 5, a general-purpose controller corresponding to the G code format can be used, and the interpolation function provided therein can be utilized as it is.

(9) The invention according to claim 9 The rotational movement axis is an axis that performs posture control for making the polishing load direction and the normal vector at the machining point coincide with each other, and is an X, Y, Z axis of three orthogonal straight axes In a processing machine having an X axis, if the rotation axis around the X axis is the A axis, the Y axis around the B axis, and the Z axis around the C axis, the B, C, A, and C axes are not necessarily impossible. Therefore, the B-axis configuration is easier to create NC data, and the configuration is superior in terms of positioning accuracy. In particular, in the embodiment, since the rotation axes of the A axis and the B axis are orthogonal to each other, and the mutual rotation movement does not move the other rotation axis, the coordinate calculation for posture control is further simplified. Has been.
(10) Inventions according to claims 10 and 11 Since the feed speed is commanded only by the movement amount of the specific axis set as the master axis, the feed speed for accurate dwell time control is derived by a simple calculation formula. can do.

(11) Invention of Claim 12 In the case of the fθ lens optical surface, the minimum radius of curvature is about 10 mm, and there is no problem in accuracy even if such a non-circular locus on the continuous curved surface is replaced with an arc. This approximation makes it very easy to derive scanning of an arbitrary curve, and Ls necessary for deriving the feed rate can be obtained.
(12) Inventions according to Claims 13 and 14 High-precision shape-correction polishing can be carried out by the configuration of a general-purpose NC controller and a multi-axis control polishing apparatus, and the creation of NC data necessary for processing is also expensive CAM It can be done easily without the need for a system. As a result, the equipment cost for the polishing process can be reduced, and the NC data can be created in a short time, so that the cost of parts can be reduced.

  Taking advantage of the polishing by the copying operation, the master of at least one of the linear moving shaft and the rotating moving shaft is used for the purpose of operating the multi-axis control polishing device with accurate dwell time control by an inexpensive and general-purpose processing machine controller. This was realized by using the other axis as a slave axis and giving a command value for the feed rate to the master axis, and the slave axis performing synchronous tracking control on the master axis.

Embodiment 1 of the present invention (corresponding to claims 1, 2, 5, 9, 10, 13, and 14) will be described with reference to FIGS. 1-1 is an enlarged perspective view of a main part of a polishing apparatus capable of 5-axis control, FIG. 1-2 is an overall schematic view of the polishing apparatus, FIG. 2 is a plan view of an optical molding surface of an fθ lens mold, and FIG. FIG. 4 is an explanatory diagram regarding an axis command value necessary for attitude control, and FIG. 4 is an explanatory diagram regarding a position command value as NC data.
Example 1 is an example in which an error component with respect to a mold design value of an fθ lens mold that has been subjected to ultra-precise cutting with a diamond tool is corrected by point contact polishing. In the case of the fθ lens, the longitudinal direction is called the main scanning direction and the short side direction is called the sub-scanning direction, and the following explanation is correction of the radius of curvature in the cross section in the sub-scanning direction. The amount of correction varies depending on the location, but is about 200 nm to 400 nm in terms of depth.

As shown in FIG. 1-1, this processing apparatus is a polishing apparatus capable of five-axis control of X, Y, Z, A, and B. Of the three orthogonal linear movement axes X, Y, and Z, the Z axis coincides with the polishing load direction. As shown in FIG. 1-2, the Z-axis is composed of a movable member 20 positioned by the NC in the Z-axis direction and a linear motion guide 10 that is attached to the Z-axis and serves as a load control shaft. The linear motion guide 10 is a static air pressure guide and has a frictionless structure in a non-contact state. The linear motion guide 10 is assembled so as to be parallel to the Z axis. In order to generate a pressing force on the polishing tool 1, a pneumatic cylinder 12 for generating a thrust is connected to the spindle holder 11, and the polishing load is controlled by changing the supply air pressure.
The rotation axis is composed of two axes: an A axis that rotates around the X axis and a B axis that rotates around the Y axis. The B-axis is constituted by a normal rotary bearing. The A-axis has a cylinder-shaped guide surface and is called a swivel stage. The upper surface of the stage is a work attachment surface, and the fθ lens mold 2 is attached by a magnet chuck disposed here. In the example of FIG. 1-1, the scanning lens mold is mounted so that the main scanning direction (longitudinal direction) is parallel to the X axis.

  The axis of rotation of the A axis and the B axis intersect, and the intersection is G. By intersecting the rotation axes, the influence of the change in the rotation axis position due to the movement of the A axis and the B axis can be mitigated in the angular attitude control for matching the normal vector of the machining point and the polishing load direction, and unnecessary rotation movement Can be reduced. Since the Z-axis has the linear motion guide 10 for load control, the NC-controlled Z-axis is operated only when the tool contacts and retracts, and is fixed at a fixed coordinate during machining. The machining surface moves up and down as the tool is scanned, but the copying operation is performed in a state where the polishing tool 1 is pressed with a constant load. The polishing tool 1 is made by solidifying wood powder with a resin, has a shape of a part of a sphere, and has a shape with a shaft. Since itself does not have abrasive grains, a diamond paste having a particle diameter of ½ μm is uniformly applied over the entire area of the optical molding surface 2a, which is the work surface. FIG. 2 is a view of the optical molding surface 2a as viewed from directly above, and the center is the work origin. When the workpiece origin is set to X = 0 and Y = 0, the curved surface shape of the optical molding surface 2a is defined by the following equation. This is generally called a curved axis type toroidal surface. The cross section in the main scanning direction at Y = 0 is defined by an aspherical expression, the cross section in the sub scanning direction is an arc, and its radius of curvature changes according to the X position. It is a form to do.

(２) 副走査曲率式
副走査曲率Ｃｓが主走査方向位置Ｘに応じて変化する式を(２)で示す。

Ｃｓ(Ｘ)＝１／Ｒｓ(０)＋Ｂ1・Ｘ＋Ｂ2・Ｘ^∧2＋Ｂ3・Ｘ^∧3＋
Ｂ4・Ｘ^∧4＋Ｂ5・Ｘ^∧5＋……＋Ｂn・Ｘ^∧n ‥‥‥‥‥‥‥ (２)

図１−１〜図４に示されている実施例１においては、主走査方向の近軸曲率半径ＲｍがＲ７００ｍｍ、副走査方向の曲率半径ＲｓはＸ位置によって異なるが、Ｒ３０ｍｍ〜４０ｍｍで変化する凸形状の円弧である。 (1) Main scanning non-arc type The surface shape in the main scanning plane is a non-arc shape, the paraxial radius of curvature in the main scanning plane on the optical axis is Rm, and the distance in the main scanning direction from the optical axis is X When the conic constant is K and the higher order coefficients are A1, A2, A3, A4, A5, A6,..., An, the depth in the optical axis direction is Z and is expressed by the following polynomial.

(2) Sub-scanning curvature formula (2) shows a formula in which the sub-scanning curvature Cs changes according to the position X in the main scanning direction.

Cs (X) = 1 / Rs (0) + B1, X + B2, X ^∧ 2 + B3, X ^∧ 3+
B4 ・ X ^∧ 4 + B5 ・ X ^∧ 5 + …… + Bn ・ X ^∧ n ........................... (2)

1-1 to FIG. 4, the paraxial radius of curvature Rm in the main scanning direction is R700 mm, and the radius of curvature Rs in the sub-scanning direction varies depending on the X position, but varies between R30 mm and 40 mm. It is a convex arc.

  As shown in FIG. 2, the polishing tool 1 scans the optical molding surface 2a in the sub-scanning direction, cuts back at the end, and scans again in the sub-scanning direction to process the entire area of the optical molding surface 2a. Is going. In the first embodiment, correction processing is performed in which the radius of curvature in the sub-scanning direction is finely adjusted according to the X position. This is based on the dwell time based on the corrected height data by slowly adjusting the scanning speed of the polishing tool 1. It is implemented by performing control. The scanning speed of the polishing tool is given by the coordinate values of points P and Q, which are NC data position command points, and the feed speed F in that section. In FIG. 1-1, position command points other than the point P and the point Q are also shown. However, the illustrated points are thinned out for convenience of explanation. They are arranged so that the length as a curve is equal to 0.2 mm. Attitude control is performed to match the normal vector at the machining point with the Z axis which is the polishing load direction. To maintain this attitude control, the A axis and B axis are simultaneously controlled as the polishing tool 1 is scanned. ing. As shown in FIG. 2, the tool path 3 is a straight line when viewed from above, but in order to perform the normal posture control along this path, four axes of X, Y, A, and B axes are used. Simultaneous control is required. The Z axis performs a copying operation by load control.

  FIG. 3 explains the axis command values necessary for the attitude control. In FIG. 3A, the polishing tool 1 performs an operation of scanning from point P to point Q on the optical molding surface 2a. FIG. 3B shows a state in which the attitude control is performed and the polishing tool 1 is scanned to the point Q. In actual control, the simultaneous 4-axis control is performed as described above. However, since the movement amount of the X-axis and the B-axis is very small in this one-block operation, the Y-axis and the A-axis are simultaneously described for the sake of explanation. A description will be given below in place of 2-axis control. The optical molding surface 2a is rotated counterclockwise around the point G by the A-axis mechanism. By this operation, the point P and the point Q are moved to the point P ′ and the point Q ′, respectively. By this rotation operation, the point Q moves in the negative direction of the Y axis and in the positive direction of the Z axis.

The position command as NC data must take this into account. FIG. 4 is a diagram for explaining the position command value. In FIG. 4, Y-axis movement amount when not performing A-axis motion is [Delta] Y _1. When accompanied by A-axis scan is [Delta] Y _2. Against the point P is an operation starting point, but so that the displaced by [Delta] Z ₂ to Z + direction and the tool for the Z direction to perform a copying operation by the load control, NC data for this amount position control Need not be considered. Based on the shape error data of the optical molding surface 2a and the removal depth of the polishing tool 1 per unit time, the tool residence time W between the position command points is obtained. By obtaining the tool feed speed F from the tool residence time W, NC data in the G code format can be created. Since the tool feed speed F has a reciprocal relationship with the tool residence time W, if the tool movement distance moved by NC data 1 block is obtained for the tool residence time per unit length, If the reciprocal is taken, the F value can be obtained. If the dwell time given between the circular arcs PQ is W1, when the attitude control is not performed, the speed f on the work surface of the tool can be obtained by the following equation (3). Ls is the length of the tool scanning trajectory that operates according to one block command, and corresponds to the length of the arc PQ.

f = Length of circular arc PQ / W1 = Ls / W1 (3)

However, when simultaneous control of the Y axis and the A axis is performed, the scanning distance of the polishing tool is the length of the arc PQ, but the tool movement distance on the NC data is ΔY ₂ as described above. In order to scan accurately with the residence time W1, the tool feed speed F was calculated by the following equation (4). Here, Lm is the movement distance between blocks by the linear movement axis in the NC data.

F = f × ΔY ₂ / length of arc PQ = f × (Lm / Ls) (4)

Since this F value generates a predetermined residence time W1 when the Y-axis is uniaxially fed, the parameter is also changed on the processing machine side. The X, Y, and Z axes are set as master axes capable of F-number commands, and the other axes, the A and B axes, are slave axes that perform tracking control with respect to the master axis. What made the X and Z axes the master axes? The former is because pick feed is performed by two-axis simultaneous control of the X and Y axes at the time of the reversing operation, and the latter is because an F value command is required when performing the contact and retract operation with the Z axis alone. In this example, the master axis and the slave axis were set on the processing machine side parameter setting screen before starting the processing.

In the above description, the scanning of the polishing tool has been described by replacing it with the two-axis operation of the Y and A axes. However, since the actual machining operation is simultaneous control of four axes of X, Y, A, and B, in this case, X equation (3) the actual travel distance of the axis as [Delta] X ₂ is the following form.

Example 2 (corresponding to claims 3, 6, 9, 11, 13, and 14) of the present invention will be described with reference to FIGS. FIG. 1-1 is an enlarged perspective view of a main part of a polishing apparatus capable of 5-axis control, and FIG. 5 is an explanatory diagram relating to an axis command value necessary for posture control when the optical molding surface has a concave cylinder shape.
The second embodiment relates to a case where the mold member whose optical molding surface 12a has a concave cylinder shape is polished by the polishing apparatus shown in FIG. 1-1 (see the description of the first embodiment). When expressed by the above equations (1) and (2), the sub-scanning cross section of Rm = ∞, Rs = 32 mm, Ai = 0, Bi = 0 (i = 1, 2, 3,... N) is a concave arc. It is a concave cylinder surface. FIG. 5 explains the axis command value necessary for this attitude control, and the polishing tool 1 is moved from the point P to the point Q ′ while performing attitude control to make the normal vector at the machining point coincide with the polishing load direction. Scanning. 3 and 5, P and P ′ and Q and Q ′ have different coordinates on the processing machine, but the points on the processing surface indicate the same points of P = P ′ and Q = Q ′. Yes. In this operation, since the center of curvature of the sub-scanning section and the A-axis swing center G of the processing machine are substantially coincident, the polishing tool scans the curved surface by the rotation operation for posture control, and the Y direction The amount of movement was several μm. Even if the feed rate F is designated for such a minute movement, there is a problem in that an accurate dwell time cannot be generated because there is a limit to the interpolation resolution of 0.1 μm.

In the second embodiment, in order to avoid this problem, the A axis and the B axis are set as master axes, and the X, Y, and Z axes are set as slave axes. The F value is an angular velocity command in units of deg / min. The F value of the tool feed speed was calculated by the following formula (6).

F = Δθ / (length of arc PQ / f) = Δθ / (Ls / f) (6)

Here, as described above, f is the tool feed speed on the machining surface obtained from the required residence time. Δθ is a movement angle of the A axis required for the angle posture control when the polishing tool is scanned from P to Q ′.

Example 3 (corresponding to claims 4 and 7 to 14) of the present invention will be described with reference to FIG. FIG. 1-1 is an enlarged perspective view of a main part of a polishing apparatus capable of 5-axis control.
In the third embodiment, the main scanning section is expressed in the form of the formula (1) by the polishing apparatus (see the description of the first embodiment) shown in FIG. This relates to a case of processing a mold member having a free-form surface shape expressed by the following. In the third embodiment, the movement amount of the linear movement axis (X axis, Y axis) becomes extremely small depending on the machining position, and conversely, the movement amount of the rotational movement axis (A axis, B axis) becomes extremely small. It is a form where the places are mixed. In the third embodiment, NC data is blocked from the NC data from the linear movement axis (X, Y, Z axis) to the rotational movement axis (A, B axis) or vice versa by the custom macro function. It was set as the structure which can be switched for every.

  The F value when the master axis is a linear movement axis is obtained from Expression (5), and the F value when the master axis is a rotational movement axis is obtained from Expression (6). Further, since the sub-scan section is a non-arc, the term of the length of the arc PQ becomes the length of the curve PQ and cannot be obtained directly. As this correspondence, an approximate arc is obtained from the three points of the obtained points P, M, and Q with respect to the coordinates of the midpoint M of the curve PQ existing on the curved surface from the definition formula of the curved surface. As the curve length, sufficient approximation accuracy can be obtained, and it can be fully utilized for residence time control.

  As described above, the first to third embodiments have been described by taking the polishing process for the purpose of shape correction as an example, but the multi-axis control method of the present invention is applicable to the cutting process and the grinding process which are trajectory transfer processes. It can be applied sufficiently. In such cutting and grinding, a tool feed speed f excellent in surface roughness and shape accuracy is separately required for the surface to be processed, and the purpose is to keep this always stable on the tool path. Be utilized. According to the present invention, it is possible to easily derive the tool feed speed F as an NC data command that makes the tool feed speed f on the scanning locus constant.

These are the principal part expansion perspective views of the grinding | polishing apparatus in which 5-axis control is possible. These are the whole schematic diagrams of the polisher in which 5-axis control is possible. These are the top views of the optical shaping | molding surface of a f (theta) lens metal mold | die. These are explanatory drawings regarding an axis command value necessary for posture control of a workpiece, (a) is a state where the polishing tool is at point P, and (b) is a state where the polishing tool is scanned from point P to point Q. It is explanatory drawing. These are explanatory drawings regarding the position command value as NC data. These are explanatory drawings regarding an axis command value required for posture control when the optical molding surface has a concave cylinder shape, (a) is a state where the polishing tool is at point P, and (b) is a state where the polishing tool is moved from point P. It is explanatory drawing of the state scanned to the point Q. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Polishing tool 2 ... f (theta) lens metal mold 2a, 12a ... Optical molding surface (surface to be processed) 3 ... Scanning locus of polishing tool on optical molding surface 4 ... B axis of rotation axis 5 ... Rotating shaft center of A-axis 10 ··· Linear motion guide 11 ··· Spindle holder 12 · · · Pneumatic cylinder 20 · · · Moving member G · · · Intersection of rotating shaft centers of A and B axes in polishing machine P ··· Tool Scan start point in posture before scanning P '... Scan start point in posture after tool scan Q ... Scan end point in posture before tool scan Q' ... Scan end point in posture after tool scan ΔY ₁ ... Y-axis movement amount without A-axis operation ΔY ₂ ... Y-axis movement amount with A-axis scanning ΔZ ₂ ... Z-axis movement amount with A-axis scanning Δθ ... From P to Q ' A-axis rotation angle required when moving

Claims (13)

When a tool is brought into approximate point contact with a part of the work surface, and the tool contact point is scanned and the entire work surface is machined, along the tool scan, the tool is brought into contact with the work surface in the polishing load direction and the tool contact point. A control method of a multi-axis control polishing apparatus having two or more axes that performs tilt posture control so that an angle formed with a standing normal vector is always constant,
When the tool scanning is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotational movement axis, the feed speed command value with at least one control axis as master axis and other axes as slave axes Is applied to the master axis, the master axis performs positioning control with respect to the command value, the slave axis performs synchronous follow-up control with respect to the master axis, and the tool contact point is changed and controlled at a predetermined speed on the work surface. A polishing apparatus control method, wherein scanning is performed while scanning. When a tool is brought into approximate point contact with a part of the work surface, and the tool contact point is scanned and the entire work surface is machined, along the tool scan, the tool is brought into contact with the work surface in the polishing load direction and the tool contact point. In a multi-axis control polishing apparatus of two or more axes that performs tilt posture control so that the angle formed with the vertical normal vector is always constant,
When the tool scan is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotary movement axis, feed speed command with at least one linear movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control by the position feedback mechanism, the slave axis performs synchronous tracking control with respect to the master axis, and the tool contact point is changed at a predetermined speed on the work surface. A multi-axis control polishing apparatus that performs scanning while being controlled. When a tool is brought into approximate point contact with a part of the work surface, and the tool contact point is scanned and the entire work surface is machined, along the tool scan, the tool is brought into contact with the work surface in the polishing load direction and the tool contact point. In a multi-axis control polishing apparatus of two or more axes that performs tilt posture control so that the angle formed with the vertical normal vector is always constant,
When the tool scan is in the simultaneous control state of multiple axes that are a combination of linear movement axis and rotational movement axis, feed speed command with at least one rotational movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control by the position feedback mechanism, the slave axis performs synchronous tracking control with respect to the master axis, and the tool contact point is changed at a predetermined speed on the work surface. A multi-axis control polishing apparatus that performs scanning while being controlled. When a tool is brought into approximate point contact with a part of the work surface, and the tool contact point is scanned and the entire work surface is machined, along the tool scan, the tool is brought into contact with the work surface in the polishing load direction and the tool contact point. A control method of a multi-axis control polishing apparatus having two or more axes that performs tilt posture control so that an angle formed with a standing normal vector is always constant,
When the tool scan is in the simultaneous control state of multiple axes, which is a combination of linear movement axis and rotary movement axis, feed speed command with at least one linear movement axis as master axis and other axes as slave axes The value is given to the master axis, the master axis performs positioning control with respect to the command value, the slave axis performs synchronous tracking control with respect to the master axis, and the tool contact point is changed at a predetermined speed on the work surface. the scanning in the basic form while, by changing the master axis to any rotary movement axis during pressurization Engineering, control of multi-axis control polishing apparatus and performs switching to the other axis as a slave axis Method.   3. The control method for a multi-axis control polishing apparatus according to claim 2, wherein the command value of the feed speed given to the master axis is a moving distance per unit time. .   4. The control method for a multi-axis control polishing apparatus according to claim 3, wherein the command value of the angular velocity given to the master axis is an angle change amount per unit time. . 5. The control method for a multi-axis control polishing apparatus according to claim 4, wherein the master axis is switched to an arbitrary axis for each command in one line of NC data by a command from NC data.   When the master axis is a linear movement axis, the command value of the feed speed given to the master axis is the movement distance per unit time. When the master axis is a rotary movement axis, the command value of the angular speed given to the master axis is The method of controlling a multi-axis control polishing apparatus according to claim 4 or 7, wherein the amount of change in angle per unit time.   When the linear movement axis is two orthogonal axes of X and Y or three orthogonal axes of X, Y, and Z and the polishing load direction is the Z axis, the rotational movement axis is an A axis having a rotational movement axis parallel to the X axis. , Consisting of 2 axes of B axis having a rotational movement axis parallel to the Y axis, and the total number of control axes is 4 or 5 axes, and the axis of rotation of the A axis and the B axis is orthogonal The multi-axis control polishing apparatus according to claim 2 or 3. In the control method of the multi-axis control polishing apparatus according to claim 2 or the multi-axis control polishing apparatus according to claim 4, a method for creating NC data for driving the multi-axis control polishing apparatus,
The feed speed command value given to the linear movement axis in the NC data is F, the desired tool feed speed on the work surface is f, and the NC data is operated by a command command of one line of NC data by the linear movement axis in the NC data. When the movement distance is Lm and the tool scanning trajectory length on the work surface is Ls,
A method of creating NC data, characterized in that F is calculated by the following equation.
F = f × (Lm / Ls) In the control method of the multi-axis control polishing apparatus according to claim 3 or the multi-axis control polishing apparatus according to claim 4, a method for creating NC data for driving the multi-axis control polishing apparatus,
The angular velocity command value given to the rotational movement axis in the NC data is F, the desired tool feed speed on the surface to be processed is f, and the movement during the operation by the command command of one line of NC data by the rotational movement axis in the NC data. When the angle is θ and the tool scanning trajectory length on the work surface is Ls,
A method of creating NC data, characterized in that F is calculated by the following equation.
F = f × (θ / Ls)   The NC data creation method according to claim 10 or 11, wherein the tool scanning trajectory length Ls on the workpiece surface is obtained by approximating the tool scanning locus on the workpiece surface with an arc. A method for creating a featured NC program.   A curved surface polishing method using at least one of claims 1 to 12.

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