Gear pair evaluation apparatus, gear pair evaluation program, and gear pair whose tooth surfaces are evaluated using the apparatus and program

1. A gear pair evaluation apparatus comprising:

coordinate converting means for associating, at a predetermined meshing rotational position, three-dimensional coordinate data on an orthogonal coordinate system measured at a set of measurement points on a tooth surface of a first gear with three-dimensional coordinate data on an orthogonal coordinate system measured at a set of measurement points on a tooth surface of a second gear that meshes with the first gear by using an assembly specification of the gear pair and converting the three-dimensional coordinate data into three-dimensional coordinate data on a cylindrical coordinate system based on the first gear;

function generating means for generating a function representing the path of a point on a tooth surface of the second gear on the basis of the three dimensional coordinate data on a tooth surface of the second gear;

inter-tooth-surface gap information calculating means for calculating, by using the function, relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that exists on the same circumference on which the point on the tooth surface of the first gear exists on the cylindrical coordinate system and corresponds to the point; and

enveloping surface calculating means for extracting the smallest relative angle information from the relative angle information calculated at each meshing rotational position at which the first and second gears mesh with each other and calculating a three-dimensional enveloping surface representing a relative gap distance between a tooth surface of the first gear and a tooth surface of the second gear from the start of meshing between the first and second gears to the end of the meshing with respect to the extracted minimum relative angle information on the basis of the relative angle information.

2. The gear pair evaluation apparatus according to claim 1 , wherein the coordinate converting means corrects the pieces of three-dimensional coordinate data associated with each other using the assembly specification of the gear pair by using a deflection value of the gear pair.

3. The gear pair evaluation apparatus according to claim 1 , wherein the enveloping surface calculating means extracts, as an apex of the gear pair, a point on the enveloping surface that corresponds to the extracted minimum relative angle information.

4. The gear pair evaluation apparatus according to claim 1 , wherein the enveloping surface calculating means converts information on the calculated three-dimensional enveloping surface into two-dimensional contour information.

5. The gear pair evaluation apparatus according to claim 1 , wherein the function generating means generates a function of radius coordinates, a function of axis coordinates, and a function of angle coordinates that represent the path of a point on a tooth surface of the second gear on the basis of the three-dimensional coordinate data on the tooth surface of the second gear by using a two-dimensional parameter set on the tooth surface of the second gear; and

the inter-tooth-surface gap information calculating means calculates the parameter representing a point on a tooth surface of the second gear that exists on the same circumference on which the path of a point on a tooth surface of the first gear exists on the cylindrical coordinate system from the function of the radius coordinates and the function of the axis coordinates and calculates relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that corresponds to the point on the tooth surface of the first gear on the basis of the calculated parameter by using the function of the angle coordinates.

6. The gear pair evaluation apparatus according to claim 1 , wherein the function generating means is set by a flat surface equation that approximates a tooth surface on the basis of a combination of three adjacent grid points on the basis of coordinate data of each grid point on a second tooth surface.

7. A gear pair evaluation program stored on computer readable medium for execution by a computer comprising:

a coordinate converting step of associating, at a predetermined meshing rotational position, three-dimensional coordinate data measured at a set of measurement points on a tooth surface of a first gear with three-dimensional coordinate data measured at a set of measurement points on a tooth surface of a second gear that meshes with the first gear by using an assembly specification of the gear pair and converting the three-dimensional coordinate data into three-dimensional coordinate data on a cylindrical coordinate system based on the first gear;

a function generating step of generating a function representing the path of a point on a tooth surface of the second gear on the basis of the three dimensional coordinate data on a tooth surface of the second gear;

an inter-tooth-surface gap information calculating step of calculating, by using the function, relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that exists on the same circumference on which the point on the tooth surface of the first gear exists on the cylindrical coordinate system and corresponds to the point; and

an enveloping surface calculating step for extracting the smallest relative angle information from the relative angle information calculated at each meshing rotational position at which the first and second nears mesh with each other and calculating a three-dimensional enveloping surface representing a relative gap distance between a tooth surface of the first gear and a tooth surface of the second gear from the start of meshing between the first and second gears to the end of the meshing with respect to the extracted minimum relative angle information on the basis of the relative angle information.

8. The gear pair evaluation apparatus according to claim 1 , further comprising a processing unit, wherein the processing unit calculates a division number per pitch of the second gear and a rotation angle of the second gear per step.

9. The gear pair evaluation apparatus according to claim 8 , wherein the processing unit calculates rotation angles of the first gear and the second gear that correspond to a current gear rotation step and repeats the calculation till a gear rotation step count reaches a maximum gear rotation step count.

10. The gear pair evaluation apparatus according to claim 9 , wherein the processing unit moves coordinates grid points on the orthogonal coordinate system of the first gear and the second gear respectively related to the rotation angles.

11. The gear pair evaluation apparatus according to claim 10 , wherein the processing unit converts a coordinate data of the grid points on the second gear tooth surface at a current step rotational position into coordinate data on the orthogonal coordinate system of the first gear.

12. The gear pair evaluation apparatus according to claim 2 , comprising enveloping surface calculating means for extracting the smallest relative angle information from the relative angle information calculated at each meshing rotational position at which the first and second gears mesh with each other and calculating a three-dimensional enveloping surface representing a relative gap distance between a tooth surface of the first gear and a tooth surface of the second gear from the start of meshing between the first and second gears to the end of the meshing with respect to the extracted minimum relative angle information on the basis of the relative angle information.

13. The gear pair evaluation apparatus according to claim 3 , wherein the enveloping surface calculating means converts information on the calculated three-dimensional enveloping surface into two-dimensional contour information.

14. The gear pair evaluation apparatus according to claim 2 , wherein the function generating means generates a function of radius coordinates, a function of axis coordinates, and a function of angle coordinates that represent the path of a point on a tooth surface of the second gear on the basis of the thee-dimensional coordinate data on the tooth surface of the second gear by using a two-dimensional parameter set on the tooth surface of the second gear; and

the inter-tooth-surface gap information calculating means calculates the parameter representing a point on a tooth surface of the second gear that exists on the same circumference on which the path of a point on a tooth surface of the first gear exists on the cylindrical coordinate system from the function of the radius coordinates and the function of the axis coordinates and calculates relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that corresponds to the point on the tooth surface of the first gear on the basis of the calculated parameter by using the function of the angle coordinates.

15. The gear pair evaluation apparatus according to claim 1 , wherein the function generating means generates a function of radius coordinates, a function of axis coordinates, and a function of angle coordinates that represent the path of a point on a tooth surface of the second gear on the basis of the three-dimensional coordinate data on the tooth surface of the second gear by using a two-dimensional parameter set on the tooth surface of the second gear; and

the inter-tooth-surface gap information calculating means calculates the parameter representing a point on a tooth surface of the second gear that exists on the same circumference on which the path of a point on a tooth surface of the first gear exists on the cylindrical coordinate system from the function of the radius coordinates and the function of the axis coordinates and calculates relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that corresponds to the point on the tooth surface of the first gear on the basis of the calculated parameter by using the function of the angle coordinates.

16. The gear pair evaluation apparatus according to claim 3 , wherein the function generating means generates a function of radius coordinates, a function of axis coordinates, and a function of angle coordinates that represent the path of a point on a tooth surface of the second gear on the basis of the three-dimensional coordinate data on the tooth surface of the second gear by using a two-dimensional parameter set on the tooth surface of the second gear; and

the inter-tooth-surface gap information calculating means calculates the parameter representing a point on a tooth surface of the second gear that exists on the same circumference on which the path of a point on a tooth surface of the first gear exists on the cylindrical coordinate system from the function of the radius coordinates and the function of the axis coordinates and calculates relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that corresponds to the point on the tooth surface of the first gear on the basis of the calculated parameter by using the function of the angle coordinates.

17. The gear pair evaluation gear pair evaluation program of claim 7 further comprising

an output step for outputting to a display data as to the gap information calculated in the information calculation step as to provide gear pair information useful for tooth surface analysis by a user.

18. A gear pair evaluation method, comprising:

conducting a coordinate converting step of associating, at a predetermined meshing rotational position, three-dimensional coordinate data measured at a set of measurement points on a tooth surface of a first gear of a gear pair with three-dimensional coordinate data measured at a set of measurement points on a tooth surface of a second gear of the gear pair that meshes with the first gear by using an assembly specification of the gear pair and converting the three-dimensional coordinate data into three-dimensional coordinate data on a cylindrical coordinate system based on the first gear;

a function generating step of generating a function representing the path of a point on a tooth surface of the second gear on the basis of the three dimensional coordinate data on a tooth surface of the second gear;

an inter-tooth-surface gap information calculating step of calculating, by using the function, relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that exists on the same circumference on which the point on the tooth surface of the first gear exists on the cylindrical coordinate system and corresponds to the point; and

an enveloping surface calculating step for extracting the smallest relative angle information from the relative angle information calculated at each meshing rotational position at which the first and second gears mesh with each other and calculating a three-dimensional enveloping surface representing a relative gap distance between a tooth surface of the first gear and a tooth surface of the second gear from the start of meshing between the first and second gears to the end of the meshing with respect to the extracted minimum relative angle information on the basis of the relative angle information.

19. The gear pair evaluation method according to claim 18 , further comprising providing a gear pair for evaluation and wherein in the function generating step there is generated a set of radius coordinates, a set of axis coordinates, and a set of angle coordinates that represent the path of a point on a tooth surface of the second gear on the basis of the three-dimensional coordinate data on the tooth surface of the second gear by using a two-dimensional parameter set on the tooth surface of the second gear; and wherein

in the inter-tooth-surface gap information calculating step there is calculated a parameter representing a point on a tooth surface of the second gear that exists on the same circumference on which the path of a point on a tooth surface of the first gear exists on the cylindrical coordinate system from the function of the radius coordinates and the function of the axis coordinates and there is further calculated relative angle information representing a gap between a point on a tooth surface of the first gear and a point on a tooth surface of the second gear that corresponds to the point on the tooth surface of the first gear on the basis of the calculated parameter by using the function of the angle coordinates; and

outputting to a display data based on the gap information calculated in the information calculation step as to provide gear pair information useful for tooth surface analysis by a user.