JP2953765B2 - Spiral shaped object shape measuring method, spiral shaped object processing system, and worm inspection method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring a shape of a spiral-shaped object such as a worm having a trapezoidal cross section at right angles to a tooth, a processing system, and a worm inspection method. The present invention relates to an inspection method capable of separately measuring a worm's reed random walk error and pitch runout.

[Conventional technology]

Conventionally, a method of inserting a ball into a perpendicular section of a worm tooth as shown in FIG. 5 or a tooth surface measurement by a contact as shown in FIG. Methods are known.

FIG. 4 shows an outline of the tooth surface measuring device, in which the worm 1 to be inspected is rotatably supported, and the touch sensor 3 is arranged so that the touch sensor 3 comes into contact with the pitch circle 2 of the worm 1. It is supported by a z-axis stage 4 and an x-axis stage 5.

In the former method of inserting a ball, when the tooth profile of the worm is a theoretical shape, the ball 7
The diameter of the ball is set in advance so that
When the worm is rotated while pressing against the tooth surface,
The movement amount of the ball in the worm axis direction (x direction) was measured in correspondence with the rotation angle of the worm, and as shown in FIG. 7, an actual measurement value c as the movement amount and a straight line d of the theoretical helical winding were obtained. Is calculated, and the absolute value of the maximum value and the minimum value within the measurement range is set as the read random walking error a. b is a single pitch error.

According to this method, there is an advantage that a value obtained by subtracting the amount of change in the tooth surface due to pitch fluctuation from the value of the lead random error can be measured.

However, in a state where the worm to be measured is used while meshing with the worm wheel, since the distance between the worm and the worm wheel is set to be constant,
There is a possibility that the position of the ball on the worm tooth surface and the position on the worm tooth surface where the worm actually contacts the worm wheel may not match .

Further, when the tooth width of the worm in the cross section perpendicular to the teeth is not equal, that is, the shape error of the tooth surface of the worm meshing with the worm wheel and the shape error of the tooth surface on the opposite side which are not necessary for practical use. In the case where the distance between the two tooth surfaces does not indicate the theoretical value, when the ball is inserted between the tooth surfaces of the worm, the ball 7 does not contact the tooth surface 6 on the pitch circle 2 and the tooth surface due to the pitch circle runout. However, there is a disadvantage that the amount of change cannot be removed.

From the above, the value of the lead random walking error measured by the conventional method means a value that is not related to the rotation of the worm and the worm wheel in practical use.

Next, in the latter method of measuring the tooth surface using the contact 8, the contact 8 is fixed at a fixed distance from the rotation axis of the worm in the radial direction (Z direction) of the worm, usually at a position on the theoretical pitch circle 2. When the worm 1 is rotated, the amount of movement of the contact 8 in the worm axis direction (X direction) is measured in correspondence with the rotation angle of the worm. Find the error.

According to this method, there is an advantage that the amount of change in the worm axial direction at a point on the worm tooth surface where the worm and the worm wheel come into contact in actual use of the worm can be measured.

However, if pitch worms occur in the worm 1, the tooth surface of the worm changes due to the effects of the pitch undulations. Have been. This measured value is shown as a value composed of the lead random walk error e and the pitch circle fluctuation f in FIG.

Here, when considering the worm processing, the lead random walk error e and the pitch circular runout f as the tooth shape shape errors are considered.
May be caused by the same processing factor,
It often occurs due to different processing factors.

Due to these different processing factors, when two errors are generated, a sufficient effect cannot be obtained even if the processing conditions are determined by feeding back the measured value of the lead random walk error including the influence of the pitch circle runout. However, the measurement data when manufacturing a high-precision worm was insufficient.

[Problems to be solved by the invention]

The present invention has been made in view of the above points,
The lead random error, which indicates the amount of change in the tooth surface on the theoretical pitch circle required for actual use of the worm, the effect of uneven tooth width required to determine the worm processing conditions, and the effect of pitch circle runout It is possible to measure lead run-out errors that are not affected, and also to measure pitch runout that is not affected by uneven tooth width, and thus efficiently perform worm performance inspection and feedback to worm processing conditions. It is an object of the present invention to provide a worm inspection method that can be performed with high accuracy, a method for measuring the shape of a spiral-shaped object such as a worm, and a processing system.

[Means for solving the problem]

In order to achieve the above object, the invention according to claim 1 is a method for measuring the shape of a spiral-shaped object formed in a substantially mountain shape having an inclined surface with respect to an axis and continuously formed spirally along an axial direction, Measure the coordinates in two directions on the inclined surface in the axial direction and the direction perpendicular to the axial direction, and the coordinates in the direction perpendicular to the axial direction of the bottom surface located between the adjacent substantially chevron shapes, Based on the inclination angle θ of the inclined surface obtained from the coordinates of the two points and the amount of change in the coordinates of the bottom surface from the specific reference coordinates, the pitch circle deflection amount = the change amount The lead random walk error = (the specific A coordinate perpendicular to the axis direction of the reference coordinate of (a) − (the amount of change) * tanθ. The method for measuring the shape of a spiral-shaped object is characterized by calculating a pitch circle deflection amount and a lead random walk error. .

According to a second aspect of the present invention, in the method for measuring the shape of a spiral shaped object according to the first aspect, the spiral shaped object is a worm gear, and the specific reference coordinates are a theoretical worm axis and a theoretical pitch circle. Are intersecting coordinates.

According to a third aspect of the present invention, there is provided a machining system for a spiral-shaped object which is formed in a substantially mountain shape having an inclined surface with respect to an axis and which is spirally formed continuously along the axial direction. Measure the coordinates in the axial direction and the direction perpendicular to the axial direction, and the coordinates in the direction perpendicular to the axial direction of the bottom surface located between the adjacent substantially chevron shapes, and obtain the coordinates from the coordinates of two points on the inclined surface. Based on the inclination angle θ of the inclined surface thus determined and the amount of change in the coordinates of the bottom surface from the specific reference coordinates, the pitch circle deflection amount = the amount of change Lead random error = (in the axial direction of the specific reference coordinates) The calculation of the orthogonal coordinates) − (the amount of change) * tanθ is used to calculate the pitch circle runout and the lead random walk error, and determine the processing conditions based on the calculated pitch circle runout and the lead random walk error. Characteristic spiral shape Which is a processing system.

According to a fourth aspect of the present invention, there is provided a trapezoidal shape having a tooth bottom surface parallel to a theoretical worm axis, a tooth tip surface, and an inclined tooth surface having a predetermined pressure angle. In the worm inspection method for the worm, the intersection point u between the inclined tooth profile and the theoretical pitch circle is detected, and the position t of any one point on the inclined tooth profile is detected, and the pressure angle is calculated from the two positions. Calculate, and further, by detecting the position of the tooth root surface parallel to the theoretical worm axis, measure the distance from the theoretical pitch circle to the tooth profile, calculate the pitch circle runout, and detect the detected inclined tooth profile. The value of the lead random walk error is derived from the intersection point u of the pitch circle and the theoretical pitch circle, and the calculated pitch circle fluctuation amount and pressure angle.

(Operation)

According to the configuration of the present invention, it is possible to determine the lead random walk error of the worm separately from the pitch runout, and the lead random walk error indicating the amount of change in the tooth surface on the theoretical pitch circle and the worm processing conditions required for determination. Measure the lead run-out error that is not affected by the difference in tooth width and the pitch circle runout, measure the pitch runout that is not affected by the tooth width difference, and obtain the pressure angle, pitch circle runout, and lead random walk error. Is a measurement method suitable as a worm performance test, and also enables measurement of data suitable for processing by feedback, thereby enabling high-precision processing of the worm. I do.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In FIG. 8, A is the theoretical shape of a section perpendicular to the tooth of the worm, and 2 is the theoretical pitch circle. B is a shape of a perpendicular cross section of the worm to be measured including a lead random walk error and a pitch runout, which is processed on the premise of the theoretical shape A of the worm perpendicular cross section.
The shape B of the cross section perpendicular to the tooth includes a tooth bottom surface and a tooth top surface parallel to the theoretical worm axis, and an inclined tooth profile that is an inclined surface having a predetermined pressure angle.

Then, C ₁ in the theoretical shape A tooth normal plane of the worm, the shape of the worm tooth normal plane only lead random walk error has occurred, and, C ₂ is the theoretical shape of the tooth normal plane of the worm 5A shows the shape of a cross section perpendicular to the tooth of the worm in which only the pitch runout occurs.

In FIG. 8, a line segment ▼ includes a pure lead random walk error and a change amount of the tooth surface due to pitch circle fluctuation, and the change amount 歯 of the tooth surface can be expressed by the following equation.

▲ ▼ = e + f (1) Therefore, a pure lead random walk error is expressed by the following equation.

e = ▲ -f (2) Here, assuming that the angle between the line segment ▼ and the line segment ▼, that is, the so-called pressure angle is θ, the variation f of the tooth surface due to the pitch swing is f = ######################################################## to ## EQU3 ## When the expression (3) is substituted into the expression (2), the following expression is obtained. ▼, ▲
By measuring three parameters, ▼ and θ,
You can ask.

FIG. 9 shows the relationship between the theoretical shape A of the worm tooth perpendicular cross section and the shape B of the worm to be measured, which is perpendicular to the tooth surface, for easy understanding. Here, in the theoretical pitch circle 2 and the theoretical shape A of the cross section perpendicular to the tooth of the worm, the intersection point between the tooth surface on the side meshing with the worm wheel is represented by w.
And the mz coordinate is set with this w as the origin.

In FIG. 9, ▲ in equation (4) represents u from the origin w.
The distance to the point, which can be determined by bringing the contact 8 into contact with the point u.

In Expression (4), θ is the pressure angle of the tooth surface on the side where the worm wheel meshes with the worm wheel on the cross section perpendicular to the tooth of the worm to be measured, in the shape B of the worm to be measured.
As shown in the figure, a straight line passing through a point t, which is an arbitrary measurement point, and a point u, which is a measurement point on the pitch circle, is an angle formed with the z-axis. Assuming that the coordinates of the points t and u are (M, E) and (L, 0), θ is expressed by the following equation.

θ = tan ⁻¹ [(LM) / E] (5) θ is 0 ° on the z-axis, and the positive direction is counterclockwise.
There is no negative direction.

In equation (4), ▲ ▼ is the value of the pitch fluctuation, and d
Since the position of a point cannot be specified, it cannot be measured directly. Thus, as an example, consider a worm machined by the screw grinder shown in FIG. This screw grinder tip section is inclined disk-shaped grindstone in which the trapezoidal worm lead angle gamma _b, while rotating, and simultaneously grinding the tooth surface and the tooth bottom.

A right-angle cross section of the worm manufactured by such a processing method is, as shown in FIG.
There is a difference K between the position of the tooth surface after processing (the position indicated by the dotted line) and the position of the ideal tooth surface (the position indicated by the solid line), and the difference K in the z-axis direction is equal at all positions. This value K can be said to be the amount of pitch circle deflection, and the difference between the theoretical position of the tooth root surface due to the theoretical shape of the worm's tooth perpendicular cross section and the position of the worm to be measured due to the shape of the tooth perpendicular cross section is measured. By measuring, it is possible to measure the pitch circle runout without being affected by the difference in the tooth width between the tooth surfaces.

Therefore, ▲ in equation (4), which is the pitch swing amount,
For ▼, the displacement in the z-axis direction from the theoretical position of the root surface in FIG. 9 to the point v may be measured.

 Therefore, ▼ = − (PS) (6)

Although the processing method shown in FIG. 10 is an example, even in the case of a worm manufactured by another processing method, the lead random walking error,
If the pitch runout is measured without being affected by the difference in the tooth width, ▲ ▼ can be measured.

As is clear from the above description, Equations (5) and (6)
Is calculated, and the distance L from the coordinate origin w to the point u is measured and calculated, and is substituted into the equation (4), so that the pure reed random walk error e is represented by the following equation.

e = L + [(P−S) · (L−M) / E] (7) In addition, pitch circular runout which is not affected by lead random walk error and uneven tooth width is given by − (PS).

Further, the pressure angle θ on the flank side of the worm that meshes with the worm and the worm wheel can also be obtained by Expression (5).

The worm inspection method of the present invention can be carried out based on the above principle using a processing system which is an inspection device as shown in FIG.

In FIG. 1, worms are chucks 10 and 11
Fixed between. An encoder 12 for detecting a rotation angle is connected to one chuck 10 via an air bearing 13. An AC servomotor 15 for rotational drive is connected to the other chuck 11 via an air bearing 14. The setting direction of the worm is a direction in which the rotation axis and the worm axis become parallel.

The touch sensor 16 for measuring the tooth surface position is installed via an z-axis stage 18 on an air slider 17 having a slide axis arranged in parallel to the x-axis. The air slider 17
On the top, a detection length measuring device 19 that can detect the movement position of the touch sensor 16 in the z-axis direction is also installed.

Further, in order to move the air slider 17 in the x-axis direction, a ball screw rotated by an AC servomotor 20 is used.
21 is provided on a surface plate 22. Further, a laser length measuring device 23 is used for detecting the movement position of the touch sensor 16 in the x-axis direction.
Is installed. Each component is provided on a surface plate 22,
The surface plate 22 is set on a vibration isolation table.

FIG. 2 shows a control unit for driving and position detection in the inspection apparatus shown in FIG.

The control unit includes a first pulse oscillator 25, a second pulse oscillator 26, and drivers 27, 28 for controlling the respective AC servomotors 15, 20 according to a command from the main control personal computer 24. 29 is connected to the comparison circuit 30,
The contact of the touch sensor 16 with the measurement tooth surface is detected.

A z-axis stage that moves the touch sensor 16 in the z-axis direction
18 is controlled by the second controller 32.

Further, the length measuring device 19 for detecting the moving amount of the z-axis stage 18 in the z-axis direction and the laser measuring device 23 for detecting the moving amount of the air slider 17 in the x-axis direction are respectively a first controller 31 and a third controller. It is connected to 33 and outputs position data.

The output of the encoder 12 for detecting the worm rotation angle is converted into a pulse number by the counter 34.

Further, the controllers 31, 32, 33, the counter 34, the drivers 27, 28, the pulse oscillators 25, 26, and the comparison circuit 30 are connected to the main control personal computer 24 via the interface boards 35, 36, 37, 38. The central control is performed by the main control personal computer 24.

Hereinafter, the operation of the present invention will be described with reference to the flowchart shown in FIG.

First, the pitch circle radius P _{0 of} the worm to be measured,
The lead L ₀ , the number β of the sections perpendicular to the tooth to be measured, and the measurement range h are input using a keyboard. These data are used for calculating the theoretical winding of the object to be measured and determining the measurement points.

Next, the touch sensor 16 is brought into contact with the end surface of the worm tooth surface, and the position of the tooth surface is recognized on the xz coordinate system.
Furthermore, from the previous value of the read L ₀ calculates the measurement starting point, to rotate the worm, by moving the touch sensor 16 x, in the z-direction, and the point of first measured at the pitch circle, opposite the tooth surface And an intermediate position.

Next, the touch sensor 16 is minutely fed in the x-axis direction to contact the point u on the tooth surface. The xz coordinate of point u at this time is
Obtained from the output from the laser length measuring device 23 and the length measuring device 19, x
The value on the coordinates is set to L and input to the main control personal computer 24.

Then, the touch sensor 16 is moved in the z direction by a predetermined fixed amount, coordinate data of the point t is obtained in the same manner as in the measurement of the point u, and (M, E) is obtained as the value. Is input to the main control personal computer 24.

Further, the touch sensor 16 is moved in the x direction by a predetermined fixed amount, and the touch sensor 16 is further moved in the z direction from that position to obtain coordinate data of the point v. Z at this time
Obtain the value S at the coordinates and use it as the main control personal computer
Enter 24.

As described above, the main control personal computer 24 calculates the pressure angle θ, the pitch swing ▲, and the lead random walk error e based on the coordinate data of the points u, t, and v.

These series of operations are performed for the number of tooth perpendicular sections set at the beginning, and finally, the difference between the maximum value and the minimum value of the lead random walk error e from each tooth perpendicular section is determined by the worm to be measured. It is assumed to be the lead random walk error. Note that the cross section perpendicular to the tooth mentioned here is not actually parallel to the x-axis,
Since the cross section is inclined by an advance angle from the x axis, the measurement point on the cross section perpendicular to the tooth requires the operation of being positioned on the x axis by rotating the worm.

After the above operation is completed, data is output, and the inspection ends.

As is apparent from the above description, the worm inspection method of the present invention measures the position where the inclined tooth surface intersects the theoretical pitch circle, compares the measured position with the theoretical tooth shape, and obtains the amount of change, L is determined from the u point) Further, the pitch circle runout which is not affected by the unevenness of the tooth width and the stagger of the tooth surface is determined (−
(PS)), and a value obtained by subtracting the variation (f) of the tooth surface due to the pitch circle deflection from the variation of the tooth surface on the theoretical pitch circle is defined as a read random error (e).

Since it is possible to obtain a pure lead random walk error that is not affected by uneven tooth width or pitch runout, it is possible to obtain data necessary for determining the processing conditions during warm processing, and to obtain highly accurate data based on the data. The worm can be manufactured efficiently.

(Effect)

According to the configuration of the present invention, it is possible to determine the lead random run error of the worm separately from the pitch circular runout, and it is possible to feed back the worm in a state in which the worm is matched with the processing conditions of the worm. There is an advantage in manufacturing, and since the amount of change from the theoretical tooth profile of the tooth surface on the theoretical pitch circle can be obtained as it is, when the worm is actually meshed with the worm wheel, the rotation unevenness of the worm wheel is used. Can be detected, which is suitable for a worm performance inspection.

[Brief description of the drawings]

1 is a perspective view of an inspection apparatus for performing the method of the present invention, FIG. 2 is a control unit in the inspection apparatus, FIG. 3 is a flowchart showing the operation of the inspection method of the present invention, and FIG. FIG. 5 is a schematic diagram of a conventional worm inspection method by inserting a ball, FIG. 6 is a schematic diagram of a conventional worm inspection method by a contact, and FIG. 7 is a conventional lead random error. FIG. 8 is an explanatory diagram showing a relationship between a lead random walk error and a pitch swing in a conventional worm inspection method, FIG. 9 is a drawing for explaining a worm inspection method of the present invention, FIG. 10 is a schematic view of a worm when machined with a screw grinder, and FIGS. 11 (a) and 11 (b) are cross-sectional views of a worm manufactured by the machining method shown in FIG. 7, and other machining methods. It is the schematic which shows the tooth perpendicular cross section of the manufactured worm. 2 ... Theoretical pitch circle, 10,11 ... Chuck, 12 ... Encoder, 13,14 ... Air bearing, 15 ... AC servomotor, 16 ... Touch sensor for tooth surface position measurement, 17 ... Air Slider, 18 ... z-axis stage, 19 ... length measuring machine for z-axis direction detection, 20 ... AC servomotor, 21 ... ball screw,
22 ... plate, 23 ... laser measuring machine, 24 ... main control personal computer, A ... theoretical shape of worm worm tooth cross section,
B: shape of the section of the worm to be measured perpendicular to the teeth
C ₁ … the shape of the worm's right-angled cross section where only the lead random walk error occurs, C ₂ …… the shape of the worm's right-angled cross section where only the pitch circular run-out occurs, e… .. Pure lead random walk error , Θ ... Pressure angle.

Claims (4)

(57) [Claims] 1. A method for measuring the shape of a spiral-shaped object formed in a substantially mountain-like shape having an inclined surface with respect to an axis and spirally formed along the axial direction, comprising: an axial direction at two points on the inclined surface; Measure the coordinates in the direction perpendicular to the axial direction and the coordinates in the direction perpendicular to the axial direction of the bottom surface located between the adjacent substantially chevron shapes, the angle obtained from the coordinates of two points on the inclined surface Based on θ and the amount of change from the specific reference coordinates in the coordinates of the bottom surface, the pitch circle deflection amount = the amount of change Lead random walk error = (coordinates orthogonal to the axis direction of the specific reference coordinates) − ( A method for measuring the shape of a spiral-shaped object, comprising calculating a lead random walk error from which a pitch circle fluctuation amount has been removed by calculating a change amount) * tanθ. 2. The helical shape according to claim 1, wherein the helical shape object is a worm gear, and the specific reference coordinates are coordinates at which a theoretical worm axis and a theoretical pitch circle intersect. An object shape measurement method. 3. A processing system for a spirally shaped object formed in a substantially mountain shape having an inclined surface with respect to an axis and spirally formed continuously along an axial direction, wherein the axial direction and the axis at two points on the inclined surface. Measure the coordinates in the direction perpendicular to the direction and the coordinates in the direction perpendicular to the axial direction of the bottom surface located between the adjacent substantially chevron shapes, the angle θ obtained from the coordinates of two points on the inclined surface And the amount of change in the coordinates of the bottom surface from a specific reference coordinate, the pitch circle deflection amount = the amount of change Lead random error = (coordinate orthogonal to the axis direction of the specific reference coordinate) − (the change Amount) * tanθ, the pitch circular runout amount and the lead random walk error are calculated, and the machining conditions are determined based on the calculated pitch circular runout amount and the lead random walk error. Processing system. 4. A worm inspection of a trapezoidal worm having a tooth bottom surface parallel to a theoretical worm axis, a tooth top surface of a tooth tip, and an inclined tooth surface having a predetermined pressure angle as a tooth profile of a cross section perpendicular to a tooth of the worm. Detecting the position of the intersection point u between the inclined tooth profile and the theoretical pitch circle, detecting the position t of any one point on the inclined tooth profile, calculating the pressure angle from the two positions, By detecting the position of the tooth root surface parallel to the theoretical worm axis, the distance from the theoretical pitch circle to the tooth profile surface is measured, and the pitch circle deflection amount is calculated,
An intersection point u between the detected inclined tooth profile and the theoretical pitch circle;
A warm inspection method, wherein a value of a lead random walk error is derived from the calculated pitch circle runout amount and pressure angle.