JP2565789B2 - Cam shape input method and device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input method and device for creating a cam shape based on lift data.

2. Description of the Related Art Conventionally, it has been a general method to input lift data in detail for a cam shape.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the cam shape inputting method described in the related art, it is necessary to input as many points as possible in order to smooth the finished shape of the cam, which requires a great amount of time. It had a problem that

The present invention has been made in view of the above problems of the conventional technique, and an object of the present invention is to provide a cam-shaped input method and device capable of performing a smooth finish with a small amount of input data. To do.

Means for Solving the Problems In order to achieve the above object, a method and apparatus for inputting a cam shape according to the present invention include a rotation angle of a cam shaft and a tool according to lift data for specifying the shape of the cam and a type of a tool diameter. In the numerical controller that converts the data to the X-axis position of the feed axis and controls the machining of the cam based on this data, specify the type of lift data corresponding to the shape of the cam follower and specify the lift data for each rough pitch. By inputting and interpolating the input lift data with a cubic spline curve, lift data that represents the contour shape of the cam with more data is created, and the error included in the data of the interpolation point of the cubic spline curve is created. The fine unevenness of the coordinates caused by is removed by the base spline curve and corrected to a smooth lift curve to interpolate the cubic spline curve. The correction points of the points with finer pitches by the base spline curve are converted into X-axis position data corresponding to the types of lift data and the type of tool diameter, and this position data is again set to 3
Interpolation is performed using the following spline curve to obtain X-axis position data with a minute pitch, which is used as the NC command value.

Also, the lift data that identifies the shape of the cam and data that shows the relationship between the rotation angle of the cam shaft and the X-axis position of the tool feed shaft according to the type of the tool diameter are converted into numerical values that control the machining of the cam. The control device includes an input data curve interpolation unit that interpolates the input rough lift data of the cam with a cubic spline curve and expresses the contour shape of the cam with more data, and the interpolation point data of the interpolation curve. Interpolation curve correction unit that removes fine irregularities of coordinates caused by errors by the base spline curve and corrects the interpolation points into a smooth curve, and the corrected lift data is converted into X-axis position data corresponding to the rotation angle of the cam shaft. The X-axis position conversion unit of the lift and the X-axis position data are again curve-interpolated by the cubic spline curve to correspond the X-axis position data with a minute pitch to the rotation angle of the cam shaft. Those comprising an X-axis position interpolation and position command output unit for outputting as that command value.

Action Lift data entered at a rough pitch is interpolated into lift data of a predetermined fine pitch, based on the type of cam follower based on the contents of the entered cam follower and the contents of the machining tool such as a grindstone. Converted to NC position data of the tool cutting axis from the type of processing tool,
This NC position data is again curvedly interpolated to obtain an NC coordinate value for each predetermined minute pitch, which is set as an NC command value corresponding to the spindle rotation angle.

Embodiments Embodiments will be described with reference to FIGS. 1 to 9.

In a known NC cylindrical grinder, the wheel head 1 is movably mounted on a guide (not shown) in the front-rear direction (X axis) that is carved on the rear side of the bed, and the wheel head 1 is fixed to the bed. NC
It is moved and positioned via a ball screw 3 by a servo motor 2 for driving. A grindstone shaft 4 is rotatably supported on the grindstone base 1 by a plurality of bearings, and a grindstone 5 is attached to the grindstone shaft 4. Left and right (Z
A table (not shown) is movably mounted on the guide in the (axis) direction, and the work spindle 6 and tailstock 7 are movably mounted on the table. A spindle 8 is rotatably supported by the work spindle stock 6, and a chuck 9 is attached to the tip of the spindle 8.
, And the rotation of the spindle 8 is controlled by an NC-driven servomotor 11. A tailstock shaft 12 is supported on the tailstock 7 concentrically with the main shaft so as to be movable in the axial direction, and a tailstock center 13 is attached to the tip of the tailstock shaft 12. Cam 14 which is a workpiece
Has a shaft portion 14a integrally on both sides on the rotation center line, one end of the shaft portion is gripped by the chuck 9, and the other end is the tailstock center.
Supported by 13.

The block diagram portion of FIG. 1 includes the X-axis servomotor 2 and the spindle rotation control axis (hereinafter referred to as C-axis) servomotor.
11 is an example of a servo system for controlling 11 according to the method of the present invention, where part A is the part according to the present invention and the other parts are general servo systems. Next, the contents of the servo system will be described. The program memory 15 is a part for storing the input program, and the program interpreting part 16 is a part for interpreting a signal from the program memory and sorting it into a necessary part. Input data curve interpolation 17 is a cubic spline that divides a section from the sent rough lift data of the cam and divides all the coordinate points of the input data between them to make the curve approximate to a cubic equation and obtain its linear derivative. The portion that creates lift data in which the contour shape of the cam is represented by more data by interpolating with a curve, the interpolation curve correction unit 18 is caused by the error included in the given lift data of this interpolated curve. A part for removing the fine irregularities of the coordinates by applying the least squares method to the base spline function, and correcting the interpolation point into a smooth curve, the X-axis position interpolation and position command output unit 21 again converts the converted position signal into a cubic curve. This is a portion for performing curve interpolation with a spline curve and outputting an X-axis position signal value with a fine pitch, for example, every 1.6 msec as a command value corresponding to the rotation angle of the C-axis. The position command calculation unit 22 synchronizes the X-axis command value with the C-axis command value, and outputs the X-axis servomotor 2 fixed position detector 25 and the C-axis servomotor 11 fixed position detector 26 output X. The speed command calculation unit 23 compares the current position of the axis and the current position of the C axis with the command value and outputs a signal that allows the current position to match the command value. A part that obtains a value and outputs a signal that allows the current speed value sent from the position-to-speed conversion unit 27 to match the speed command value, the current command calculation unit 24 converts the speed command value into a current command value. It is the part to do. The X-axis power amplification unit 28 supplies electric power to the X-axis servomotor 2 according to the X-axis current command value from the current command calculation unit 24. The C-axis power amplification unit 29 uses the current command calculation unit 24.
This is a part for supplying electric power to the C-axis servomotor 11 according to the C-axis current command value from.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

In step S1, as shown in FIGS. 3 to 5, the lift amounts l ₁ , l ₂ , l ₃ with respect to the rotation angle θ are different depending on the respective shapes of the cam followers 31A, 31B, 31C. In addition to designating the type of lift data, the lift data is input at a rough pitch as shown in FIG. In step 2, the lift data input at this rough pitch is interpolated by a cubic spline curve drawn by a function that can pass all the input points without fail and smoothly interpolate the contour shape of the cam. The lift data with a relatively fine pitch as shown in FIG. 7 is created by expressing it with a lot of data, and the data number is made larger than the given data number.

The calculation method of this curve is that the given coordinates (data) are divided into certain sections, and they are successively approximated to a cubic equation,
The second derivative is calculated, but the coordinate given at this time is always passed.

However, although it is possible to smoothly connect the given coordinates, a smooth but fine unevenness occurs due to an error included in the data. In step S3, fine irregularities caused by an error included in the lift data of the interpolation points which are curve-interpolated to the specified pitch by the cubic spline curve are removed by applying the base spline curve to correct the interpolation points, and FIG. The cam curve is smoother as shown in.

The calculation method of this curve is to obtain new data by fitting the above-mentioned fine pitch lift data to the base spline function by the least square method. Step
In S4, when the cam shape is created by the grinding wheel 5 with the given lift data, the contact angle C changes depending on the wheel diameter as shown in FIG. 9, so the lift amount l = f
Since it is necessary to convert (θ) into a position on the X-axis, x = f (c), the lift → X-axis position conversion unit 19 converts each point of the lift data, which is curve-interpolated and the pitch becomes finer. , NC X corresponding to the type of lift data and grindstone diameter by calculation
Convert to axis position. In step S5, the NC X-axis position data is again interpolated by the cubic spline curve, and the tenth
Calculate NCX axis position command data with a fine pitch every 1.6 msec as shown in the figure by calculation.

Although the present embodiment is directed to the case where the cam surface is ground by the grinder, it is needless to say that the present invention can be applied to the case where the cam surface is cut by another machine tool such as a lathe.

EFFECTS OF THE INVENTION Since the present invention is configured as described above, it has the following effects.

The lift data input at a rough pitch is converted into NC coordinate values after making fine lift data by the first curve interpolation, and this coordinate value is further interpolated by the second curve to make a fine pitch NC.
Since the coordinate value is calculated and used as the position command value for the tool cutting axis that corresponds to the cam rotation angle, it is possible to reduce the time and effort for data input, and it is possible to process a smooth cam curve with a small amount of data input. Therefore, the machining program becomes easy and the efficiency is improved.

[Brief description of drawings]

FIG. 1 is a block diagram of an NC servo system including a partial perspective view of a grinding machine of this embodiment, FIG. 2 is a flow chart showing the operation of this embodiment, and FIGS. 3 to 4 show the types of cam followers. FIG. 3 is an explanatory view showing the relationship of the lift amount, FIG. 3 shows a flat case, FIG. 4 shows a spherical case, FIG. 5 shows a − linear case, and FIG. 6 shows 7 is a graph of lift data for explaining a rough pitch input state, FIG. 7 is a graph of lift data in a state in which a curve is interpolated to a fine pitch, and FIG. Fig. 9 is a diagram showing a cam curve, Fig. 9 is an explanatory diagram of a state in which the X-axis position for obtaining a desired cam curve changes depending on the diameter of a grindstone, and Fig. 10 is a part of a graph showing NC data which is curve-interpolated to a fine pitch. It is a figure. 5 …… Whetstone, 14 …… Cam 17 …… Input data curve interpolation section 18 …… Interpolation curve correction section 19 …… Lift → X axis position conversion section 21 …… X axis position interpolation and position command output section 31A to 31C… … Cam followers

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsuhiro Yoshimura 1-32 Tsujimachi, Kita-ku, Nagoya-shi, Aichi Prefecture Okuma Iron Works Co., Ltd. (56) Reference JP-A-1-206406 (JP, A) Kaihei 1-100606 (JP, A)

Claims (2)

(57) [Claims] 1. Lift data for specifying a shape of a cam and data showing a relation between a rotation angle of a cam shaft and an X-axis position of a tool feed shaft are converted according to a kind of a tool diameter, and the cam is machined by this data. In the controlling numerical control device, the type of lift data corresponding to the shape of the cam follower is specified, the lift data for each rough pitch is input, and the input lift data is interpolated by a cubic spline curve to form the contour of the cam. Create lift data that expresses the shape with more data, remove the fine irregularities of the coordinates caused by the error contained in the data of the interpolation points of the cubic spline curve by the base spline curve, and correct it to a smooth lift curve. Lift data is used as a correction point for correction points of the base spline curve, which are fine pitches obtained by the interpolation of the cubic spline curve. And X-axis position data corresponding to the type of tool diameter, and this position data is interpolated again by a cubic spline curve to obtain X-axis position data with a minute pitch and set as the NC command value. How to input the cam shape. 2. Lift data specifying the shape of the cam and data representing the relationship between the rotation angle of the cam shaft and the X-axis position of the tool feed shaft are converted according to the type of the tool diameter, and the cam is machined by this data. In a numerical control device for controlling, an input data curve interpolating section for interpolating the input rough lift data of a cam with a cubic spline curve and expressing the contour shape of the cam with more data, and interpolation point data of the interpolation curve. Interpolation curve correction unit that corrects the interpolation points into a smooth curve by removing the fine irregularities of the coordinates caused by the error included in the base spline curve, and the corrected lift data for the X-axis position corresponding to the rotation angle of the cam shaft. An X-axis position conversion unit of the lift that converts the data into X-axis position data, and the X-axis position data is again curve-interpolated by a cubic spline curve to convert the X-axis position data with a minute pitch into the rotation angle of the cam shaft. Input device cam profile, characterized in that it comprises an X-axis position interpolation and position command output unit outputs a corresponding command value.