JPH04348850A - Method and device for measuring shape of cylindrical cam - Google Patents

Abstract

PURPOSE:To cause coincidence of a cam with a regular measurement starting point through correction of an error by calculating an error angle with the measurement starting point of the cam mounted on a reference point planned during measurement of the shape of a manufactured cam. CONSTITUTION:A cam P is supported to a support bed 4 capable of controlling revolution dividing, an error detector 37 is located to a slider capable of controlling positioning in the direction of an R-axis, and a manual cam P is mounted so that a temporary measurement starting point R1 is set to a value within + or -10 deg. of a design reference point (a regular measurement starting point) R0. Based on the temporary measurement stating point R1, measurement is determined through temporary measurement and a difference eni between a change amount r'n of a cam profile radium and a change amount r''ni of a design value of thetai calculated by a design formula is determined. An angle thetai at which a square sum of the difference eni is minimized is determined. By correcting and rotating the temporary measurement starting position of a cam based on the thetai forming an angle displacement amount T, the cam is caused to coincide with the regular measurement starting point.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for measuring the shape of a cam manufactured based on design values.

0002

[Prior Art] In order to measure the error in the contour shape of conventionally manufactured discs and cylindrical cams (hereinafter referred to as cylindrical cams),
One method is to use a computer to draw a full-size outline of the theoretical cam using an X-Y plotter, and then superimpose the manufactured cam on top of that drawing or use a projection method to draw it as shown in Figure 7. Measure machining errors. Another method is to rotate the cam by a fixed angle with the cam installed in the mechanism, and directly measure the displacement of the nodal end as shown in Figure 8. Let the error be calculated.

0003

[Problems to be solved by the invention] One is that a projected drawing of the manufactured cam shape is placed on a full-size computer-generated drawing to check for errors, so only rough judgments can be made, and it is impossible to express the errors numerically. In addition to not being accurate, it is time consuming and inefficient. Second, it is necessary to match the measurement starting point of the cam with the design reference point, which makes data analysis troublesome. Further, there is a problem in that it involves a troublesome operation of turning at a predetermined angle and measuring the contour radius, and also requires a long time.

The present invention was made in view of the problems of the conventional technology, and its purpose is to automatically and accurately determine the measurement start point of a cam shape from provisional measurement data. The purpose of this paper is to provide a measuring method and a measuring device for the

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention has a radial displacement measuring device and uses a measuring instrument that supports a cylindrical cam at its axis, and measures the supported cylindrical cam. Position a temporary measurement start point near the actual measurement start point, temporarily measure the contour radius at the cam angle θi, and find the difference between the shape of the cam in a certain range near the measurement start point and the cam shape at the designed angle θi. This method finds the starting point for the actual measurement of the cam by finding the minimum value of .

The invention further includes a cam holding and driving member that supports the cylindrical cam along its axis and is capable of rotationally positioning the cylindrical cam, a means for detecting the rotation angle of the cylindrical cam, and a means for moving and positioning the cylindrical cam in the axial direction and radial direction. a means for calculating and storing a design value of the cam shape of the cylindrical cam; and calculating a minimum value of an error between a provisional measurement value of the contour radius detection means and the design value. The method includes a calculating means, and means for adjusting the phase of the cylindrical cam to the starting point of the actual measurement of the cam shape based on the angle corresponding to the calculated minimum value of the error.

[0007]

[Operation] The method is as claimed in claim 1.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to FIGS. 1 and 2. A wall 2 is installed on the machine base 1, and a support shaft 4 supported by an air bearing 3 is vertically rotatably held on the front surface of the wall 2. A table 5 is attached and a drive center 6 is fitted in the center thereof. A pulley 7 is keyed to the lower part of the support shaft 4, and a rotary encoder 8 is attached to the lower end. A belt 12 is stretched between the pulley 7 and a pulley 11 on the output shaft of a servo motor 10 attached to the frame 1.

A tailstock 15 is attached to the upper part of the wall 2, and a tailstock center 16 is fitted concentrically with the support shaft 4. This tailstock center 16 has a rack carved in the axial direction, and is moved in the axial direction by a pinion that engages with a rack at the shaft end of a handle 17 that is horizontally supported on the tailstock 15 that engages with the rack. Further, the spherical body at the tip presses the tailstock center 16 by the pusher 18 in a direction perpendicular to the tailstock center 16 so that the cam P to be measured is not loosened when the cam P is supported by both the upper and lower centers.

Further, two linear guides 21a and 21b parallel to the cylindrical camshaft are attached to the front surface of the wall 2, and a table 23 is supported and guided via linear bearings 22a and 22b. There is. Linear guide 2
A feed screw 24 rotatably supported by the wall 2 is supported between 1a and 21b, and a nut provided on the back surface of the table 23 is screwed into the feed screw 24. The position of the table 23 in the vertical direction (Z-axis) is controlled by a servo motor 25 driven by a control device (not shown) attached to the wall 2.

Further, in parallel with the linear guide 21a, a main scale 26 of a measuring member, for example, a commercially available Minilid Model 310 manufactured by Heidenhain, is provided on a mounting base. The main scale 26 is an optical grating of the required length in which light transmitting parts and non-transmitting parts are formed at a predetermined pitch.An optical grating index scale 27 is attached to the table 23 side, and the necessary light emitter and receiver are attached to the table 23 side. It is provided. However, if such precision is not required in the Z-axis direction, a magnetic scale may be used. Furthermore, positioning can be replaced by NC control by providing a position detector on the feed ball screw without using a scale.

As shown in FIG. 2, linear guides 30a and 30b are mounted on the table 23, and the slider 32 is connected to the cam P via linear bearings 31a and 31b.
It is supported so that it can move horizontally toward the axis of the The slider 32 is connected to a servo motor 33 driven by a control device, and is moved via a nut screwed onto a feed ball screw 34 rotatably supported on the table 23. To measure this movement amount, for example, mini lid 3
Type 10 is used.

That is, the slider 32 is provided with a main scale 35 having an optical grating in which light transmitting portions and non-transmitting portions are alternately formed at a predetermined pitch, and the table 23 is provided with a main scale 35 having a predetermined interval from the main scale 35. An index scale 36 is provided which also has an optical grating arranged oppositely. Although not shown, the main scale 35 and the index scale 36 are provided with a light projector that irradiates known light and a light receiver that receives the transmitted light across the scale, and movement signals of the interference fringes are sent to a control device and counted. The amount of movement can be detected with high accuracy. Furthermore, slider 32
For example, an error detector 37 such as a non-contact sensor of the LD-2510 type manufactured by Keyence Corporation or a differential transformer type contact sensor manufactured by Tokyo Seimitsu is used, and an output signal for detecting displacement resulting in an error is sent to the control device.

A description will be given based on FIG. 3 showing a control block diagram for measuring the cam contour radius of the slider 32. 51 is MD
I, the design formula for the desired cam shape using an input member such as a tape, r = Ro - R = f (θ), where r: displacement amount of the contour radius R from the actual measurement starting point Ro, provisional measurement (automatically The measurement pitch, measurement range, and the like during the actual measurement after positioning are input to the actual measurement starting point Ro. 52 is a computer, 53 is MDI5
3, a storage device that stores the data input from 3; 54, a calculator that calculates the design value from the stored design formula; 55, the current values of the R-axis position detectors 35 and 36; the Z-axis position detector 26;
The current value of 27, the angular position of the θ-axis position detector 8 and the calculator 5
4 is a memory for storing the cam design value calculated in step 4 and the detection error δn of the error detector 37; 56 is the R-axis position detector 35;
, 36, current values of Z-axis position detectors 26 and 27,
A comparator that compares the angular position of the θ-axis position detector and the cam design value stored in the memory 55 and outputs the difference.

57 is an arithmetic unit that calculates r'n = f(θn) + δn and Δr'n = r'n - r'n-1, and 58 is an arithmetic unit that calculates the calculated values r'n and Δr'n of the arithmetic unit 57. The memory device 59 is r〃ni=(θn −θi) and Δr
Arithmetic unit for calculating 〃ni=r〃ni-r〃n-1i, 6
0 is a memory for the calculated values r〃ni, Δr〃ni of the arithmetic unit 59, 61 is an arithmetic unit that calculates Equation 1, 62 is a memory for the calculated values eni, Ei of the arithmetic unit 62, and 63 is a memory for E>Ei. Compare, when NO, add 0.1° to θi and set θi to 1
A comparator 64 compares and determines whether the angle is 0.1°, and 64 indicates θ when Ei compared by the comparator 63 is small and at this time.
65 is a function generator that generates a function corresponding to the error angle T in the memory 64 in response to a command; 66 is the R-axis, Z-axis, and θ compared by the comparator 56;
A function generator that generates a function of the difference between the axes, 67 is an R-axis motor drive circuit, 68 is a Z-axis motor drive circuit, and 69 is a θ-axis motor drive circuit.

[Math 1]

71 is a plotter that plots error curves and cam design values corresponding to cam angles based on the stored values of the error detector 37; 72 is a printer that similarly prints errors and design values for cam angles; 73; 74 is a display for the current value of the R axis, 74 is a display for the current value of the Z axis, and 75 is a display for the current angle of the θ axis.

Next, a description will be given based on the control flowchart shown in FIG. In step S1, the cam to be measured is supported between the drive center 6 and the center 16, and is considered to be the basic point (main measurement starting point Ro) of the design value of the cam shape calculated based on the cam contour radius design formula. Manually position the tentative measurement starting point R1 of the cam within ±10° of the position.

In step S2, it is determined whether the SDI has been input and the design value calculation has been completed. If NO, step S3
In the cam shape design formula from MDI51, the angle measurement pitch at the time of temporary measurement, for example, 1 degree, n = 1 to 21, measurement range -
10° to 10°, simulation correction angle pitch 0.
1 degree is -10 degrees to 10 degrees, and the angle measurement pitch at the time of actual measurement is, for example, 10 degrees, and the measurement range is 0 degrees to 360 degrees.

In step S4, 0° to 360° at 10° pitch and -10° at 1° pitch based on the design formula.
Calculation of the design value of .degree. to 10.degree. is performed in the arithmetic unit 54, and the value f(.theta.n) is stored in the storage device 55. Step S2
If YES, the process moves to step S5.

In step S5, the slider 32 is moved and positioned so that the measurement reference position of the non-contact sensor of the error detector 37 becomes the basic point of the design value, and then the slider 32 is moved at a pitch of 1°.
The cam is rotated and positioned from 10° to 10° by the servo motor 10, and the slider is positioned to the design value corresponding to that angle. For each angle, the error detector 37 reads the error δn and stores it in the memory 55, corresponding to the angle θn. The error δn is stored.

In step S6, the calculator 57 adds the error δn of the corresponding position of the cam contour radius design value f(θn) at the cam angle θn to calculate the amount of displacement of the contour radius from the provisional measurement starting point R1 at the angle θn. r´n = f(
θn)+δn is determined and stored in the storage device 58.

In step S4, the amount of displacement r'n when the angle is θn and the amount of displacement r'n-1 when the angle is θn-1
Therefore, the cam rotation angle θn-1 from the tentative measurement starting point R1
Displacement amount r'n, r'n-1 between and θn
Amount of change in contour radius for each measurement pitch Δr′n = {f(θ)+δn }-{f(θn-1
)+δn-1 }=r'n -r'n-1 in the memory 5
The calculation unit 57 calculates the value based on the stored value of 8, and stores it in the storage unit 58.

In step S8, in order to find out how many times the cam is installed with respect to the reference point which is the main measurement starting point Ro, the cam contour radius design formula r=R in the memory 53 is used.
o-R=f(θ) with θi as the correction angle parameter to generate the function r〃=f(θ-θi), and measure from -10° to 10° at 0.1 pitch for each pitch, which was done in temporary measurement. The calculation unit 5 calculates the amount of displacement r〃ni=f(θn −θi) of the contour radius from the main measurement starting point (Ro) by simulating the
9 and stores it in the memory 60.

Cam rotation angles θn, θn-1 from the main measurement starting point Ro stored in the memory 60 in step S9
Change amount Δr〃ni=f(θn −θi
)−f(θn−1−θi)=r〃ni−r〃n−
1i is determined by the arithmetic unit 59 and stored in the memory 60.

[0025] In step S10, provisional measurement starting point R1
Based on the amount of change Δr'n in the contour radius of the cam calculated based on and stored in the memory 58, and the actual measurement starting point Po on the design formula.
The difference e from the amount of change Δr〃ni in the contour radius calculated when the measurement point deviates by θi and is stored in the memory 60.
The arithmetic unit 61 calculates ni=Δr〃ni−Δr′n. That is, it is determined for each measurement pitch in the entire temporary measurement range n and is stored in the memory 62.

In step S11, the sum of squares 2 of eni for each pitch stored in the memory 62 is calculated by the calculator 6.
1 and stored in the memory 62. This sum of squares will be calculated for all parameters.

[Math 2]

In step S12, the previous sum of squares E stored in the memory 62 is compared with the sum of squares Ei obtained this time, and if E>Ei is YES, in step S13, E is set to Ei, and the current value is The error angle T is stored in the storage device 64 as θi. If NO in step S12, the process moves to step S14, but if Ei is the initial value, there is no comparison target, and the process moves to step S14.

In step S14, 0.1° is added to the correction angle θi in order to perform calculations using θi. In step S15, the comparator 63 determines whether θi has reached 10.1. If NO, the process moves to step S8 and the simulation is repeated in the same way until 10.1 is reached. If YES, in step S16, assuming that Ei stored in the memory 64 is the minimum value, the function generator 65 generates a function with θi at this time as the error angle T.
A command to drive the servo motor 10 by the shaft motor drive circuit 69 and rotate the support shaft 4 and rotary table 5 is issued.

In step S17, the cam P is positioned by rotating the error angle T°, and the main measurement starting point Ro corresponds to the front surface of the filler of the error detector 37. In step S18, the servo motor 10 is rotated, for example, 360 times at a pitch of 10°.
Rotate and position up to °. On the other hand, the motor 33 is driven to control the position of the slider 32 in the Z-axis direction so that it becomes the design value at the corresponding angle, and the error δ at that time is detected by the error detector 37, printed by the printer 72, and plotted by the plotter 71. do. The current value of the R axis is displayed on the R axis display 12, the current value of the Z axis is displayed on the Z axis position display 74, and the current angle of the θ axis is displayed on the θ axis.
Each is displayed on the axis angle error display 75. Note that if the cam 1 is a cylindrical cam, the main measurement is performed by controlling the position of the R axis. If the cylindrical cam is a torsion cam, provisional measurements are performed according to the method of the present invention at each R-axis position if necessary, and a similar actual measurement is performed in accordance with the actual measurement starting point.

[0029]

[Effects of the Invention] As described above, the present invention has the following effects. According to the method of claim 1, the correct measurement start position for the actual measurement can be determined based on the error value obtained by the preliminary measurement and the design value, so that the shape of the cam can be measured quickly and accurately. The device according to claim 2 makes it possible to carry out the method described above.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a measuring device of the present invention.

FIG. 2 is an explanatory diagram of a slider for movement in the R-axis direction.

FIG. 3 is a control block diagram.

FIG. 4 is a control flowchart.

FIG. 5 is a diagram showing measured values of the cam shape at the time of provisional measurement.

FIG. 6 is a diagram showing the measured values of the cam shape during the main measurement.

FIG. 7 is a diagram showing a first conventional measurement method.

FIG. 8 is a diagram showing a second conventional measurement method.

[Explanation of symbols]

3 Air bearing 6 Drive center 8 Angle detector 10, 25, 33 Servo motor 16 Center 21a, 21b, 31a, 31b Linear guide 24
, 34 Feed screw 26, 35 Main scale 27, 36 Index scale 32 Slider 37 Error detector 51 MDI 53, 56, 58, 60, 62, 64 Memory device 54,
57, 59, 61 Arithmetic unit 55, 63 Comparator 65, 66 Function generator 71 Plotter 72 Printer

Claims (2)

[Claims] Claim 1: Using a measuring device that has a radial displacement measuring device and supports a cylindrical cam at its axis, the supported cylindrical cam is positioned at a temporary measurement starting point in the vicinity of the main measurement starting point. The contour radius at the cam angle θi is tentatively measured and the shape of a certain range near the measurement starting point of the cam is determined, and the design angle θi is determined.
A method for measuring the shape of a cylindrical cam, characterized in that the starting point for the actual measurement of the cam is found by finding the minimum value of the difference between the shape of the cam and the shape of the cam. 2. A cam holding and driving member that supports a cylindrical cam at its axis and is capable of rotationally positioning the cylindrical cam, a means for detecting a rotation angle of the cylindrical cam, and a cam holding and driving member that moves in the axial direction and radial direction of the cylindrical cam. a contour radius detection means provided so as to be positionable; a means for calculating and storing a design value of the cam shape of the cylindrical cam; and a minimum value of an error between a tentative measurement value of the contour radius detection means and the design value. A cylindrical cam shape measuring device comprising: calculation means for calculating the minimum value of the calculated error; and means for adjusting the phase of the cylindrical cam to a cam shape main measurement starting point based on the angle corresponding to the minimum value of the calculated error.