JPH05332765A - Shape measurement device - Google Patents

Abstract

PURPOSE:To easily obtain measurement data excepting an irregular section outside the range of a measurement object without any need to fit a positioning mechanism by processing the data outputted from a measurement section with a median filter. CONSTITUTION:A measurement section 14 outputs analog signals showing the outline form of a workpiece 20 to a median filter processing section 16, on the basis of the shift amount of probes 18 and 18 due to the rotation of the workpiece 20. The signals are amplified with an amplifier 22, and subjected to a sampling process in an A/D converter at the predetermined intervals. Then, the signals are digitized and sequentially saved in RAM 28. The signals as saved are subjected to filtering process 16 through a median filter programmed in ROM 30, and outputted from CPU 26 to a display. In this case, the median filter obtains the median value of consecutive digital signals, while dephasing a filtering time, during a filtering time exceeding the double of the time to output the digital signal of a cutout groove 21 outside the range of a measurement object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shape measuring apparatus, and more particularly to a shape measuring apparatus for measuring an outer diameter shape of an object to be measured having an uneven portion which is not an object of measurement formed on an outer peripheral surface.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, a shape measuring device of this type rotatably supports a rod-shaped object to be measured (hereinafter referred to as "workpiece") 1 with its shaft center. 1
On the outer peripheral surface 1a of the pair of stylus 2, which is vertically movable,
2 is pressed and brought into contact. When the work 1 is rotated, the tracing styluses 2, 2 move in the vertical direction along the minute irregularities on the outer peripheral surface of the work 1, and when this movement amount is output to the measurement unit 3, the measurement unit 3 moves as described above. The outer shape of the work 1 is measured based on the amount.

When a cutout groove 4 such as a key groove which is not to be measured is formed on the outer peripheral surface 1a of the work 1, the measuring section 3 measures the outer shape including the cutout groove 4. However, when the workpiece 1 rotates quickly, the probe 2 jumps when it crosses over the notch groove 4, so the measured data 5 is the measured data portion (recess) 5a of the notched groove 4 as shown in FIG. The measured data portion 5b that exceeds the distance becomes wavy. Therefore, the shape of the measurement data section 5b cannot be measured accurately.

On the other hand, the rotation of the work 1 is slowed down and the probe 2
Prevent jumps and output measurement data 6
There is a measuring method in which (see FIG. 6) is binarized with a threshold value 7 (see FIG. 7) that does not include the measured data portion 5a in the measured value, and the measured data portion 5a is deleted. However, in this method, as shown in FIG. 7, the measurement data portion 6c of the chamfered portion of the cutout portion 4 cannot be completely deleted.
However, there is a drawback that the shape cannot be measured accurately. The horizontal axis of the measurement data 5 and 6 shown in FIGS. 5 to 7 represents the measurement time, and the vertical axis represents the displacement amount of the measurement data.

Therefore, as a means for solving such a problem, a positioning mechanism is preliminarily attached to a position corresponding to the uneven portion outside the object of measurement so that the tracing stylus 2 can pass through the uneven portion.

[0006]

However, in the conventional shape measuring apparatus, it is necessary to attach a positioning mechanism corresponding to the uneven portion other than the object to be measured to each work piece 1, which is troublesome and requires a long time for the measurement. There is a drawback that it costs. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a shape measuring device that can easily obtain measurement data excluding irregularities outside the measurement target without attaching a positioning mechanism. ..

[0007]

In order to achieve the above object, the present invention provides a shape for measuring an outer diameter shape of an object to be measured, in which an outer peripheral surface is provided with concave and convex portions such as notched grooves and protrusions which are not the object of measurement. In a measuring device, a shape-measuring device comprising a measuring element to be brought into contact with the outer peripheral surface of the measuring object, and a measuring section for measuring the outer shape of the measuring object based on the movement of the measuring element, Means for sampling the signal output from the measuring unit at a predetermined interval to sequentially output measured data, and a median value of continuous measured data in a filter period exceeding twice the period in which the measured data of the uneven portion is output. And a median filter for calculating the filter period while shifting the filter period.

[0008]

According to the present invention, the signal output from the measuring section is sampled at a predetermined interval, the measured data is sequentially output to the median filter, and the median filter performs the filter processing. As a result, the measurement data of the uneven portion that is not the measurement target is removed by performing the filter processing with the median filter, so that the measurement data excluding the uneven portion can be easily obtained without attaching a positioning mechanism to the measurement object. be able to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the shape measuring apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows an embodiment of a shape measuring device 10 according to the present invention.
In the figure, the shape measuring apparatus 10 is composed of a measuring unit 12, a measuring unit 14, and a median filter processing unit 16.

The measuring unit 12 includes a pair of measuring elements 18, 18
The measuring elements 18, 18 are movably supported in the vertical direction in the figure. In addition, the measuring elements 18, 18 are
The rod-shaped workpiece 20 is sandwiched between the workpieces 20. The tip portions 18a, 18a of the workpieces 20 are pressed against the outer peripheral surface 20a of the workpiece 20. The work 20 is rotatably supported by its axis, and the outer peripheral surface 20a of the work is provided with notch grooves 21, 21 which are not to be measured.

A measuring section 16 is connected to the measuring elements 18, 18. The measuring unit 16 outputs an analog signal indicating the outer shape of the work 20 to the median filter processing unit 16 based on the amount of movement of the measuring elements 18, 18 caused by rotating the work 20. The median filter processing unit 16 includes an amplifier 22 and an A / D converter 2
4 and CPU 26, and the analog signal output from the measuring unit 14 is amplified by the amplifier 22. The analog signal amplified by the amplifier 22 is sampled at predetermined intervals by the A / D converter 24, converted into a digital signal, and sequentially stored in the RAM 28 of the CPU 26. The digital signal stored in the RAM 28 is filtered by a median filter (described later) programmed in the ROM 30 and output from the CPU 26 to a display (not shown).

Next, the filter processing by the median filter will be described with reference to FIG. First, the median filter is to obtain the median value of continuous digital signals while shifting the filter period in the filter period that exceeds twice the period in which the digital signal of the cutout groove 21 is output.

Next, a method for setting the filter period based on the displacement amount shown in FIG. 2 will be described. The displacement amount in FIG. 2 is obtained by converting the analog signal of the measurement data shown in FIG. 6 into a digital signal at a predetermined interval and storing it in the RAM 28. From the magnitude of this amount of displacement, it is found that the positions of the notch groove 21 are at two locations, part A and part B, and the count number of the digital signal is two. Thus, when the displacement amount is filtered by a median filter having five continuous digital signals as the filter period, the data output from the CPU 26 is:
3 → 3.2 → 3.4 → 3.7 → 3.7 → 3.7 → 3.3 → 3.3.

That is, a signal obtained by removing the digital signals [(-7.2, -7.3) and (-7.5, -7.9)] of the cutout groove 21 out of the displacement amount is output from the CPU 26 to the display. As a result, even if the notch groove 21 is actually measured by the probe 18, the measurement data 32 as shown in FIG. 3 can be obtained. Therefore, according to the present embodiment, the cutout groove 2 of the work 20 is not attached to the cutout groove 21 and the cutout groove 2 is not attached.
The measurement data except 1 can be easily obtained.

In the present embodiment, the notch groove (recess) 21 has been described, but a projection (convex) which is not the object of measurement can be similarly filtered with a median filter.
In this case, the filter period of the median filter may be set to a period that exceeds twice the period in which the digital signal of the protrusion is output.

[0016]

As described above, according to the shape measuring apparatus of the present invention, the signal output from the measuring section is sampled at a predetermined interval, and the measurement data is sequentially output to the median filter, and the median filter is used. Filter processing. As a result, the measurement data of the uneven portion that is not the object of measurement is removed by being filtered by the median filter, so that the measurement data excluding the uneven portion can be easily obtained without attaching a positioning mechanism to the measurement object. You can

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a shape measuring apparatus according to the present invention.

FIG. 2 is an explanatory view showing a filter process by a median filter applied to the shape measuring apparatus according to the present invention.

FIG. 3 is measurement data showing an outer diameter shape of a work measured by a shape measuring apparatus according to the present invention.

FIG. 4 is an explanatory view showing an embodiment of a conventional shape measuring device.

FIG. 5: Measurement data showing the outer diameter shape of a work measured by a conventional shape measuring device

FIG. 6 is measurement data showing an outer diameter shape of a work measured by a conventional shape measuring apparatus.

FIG. 7 is an explanatory view of binarizing the measurement data of the work with a predetermined threshold value.

[Explanation of symbols]

 10 ... Shape measuring device 12 ... Measuring unit 14 ... Measuring unit 16 ... Median filter processing unit 18 ... Measuring element 20 ... Work 22 ... Amplifier 24 ... A / D converter 26 ... CPU

Claims (1)

[Claims] 1. A shape measuring device for measuring an outer diameter shape of a measurement object, wherein an unevenness portion such as a notch groove, a protrusion, etc., which is not an object of measurement is formed on the outer circumference surface, the shape measurement device being in contact with the outer circumferential surface of the measurement object. In a shape measuring device comprising a measuring element and a measuring section for measuring the outer shape of a measurement object based on the movement of the measuring element, a signal output from the measuring section is sampled at a predetermined interval and successively. A means for outputting measurement data; and a median filter for obtaining a median value of continuous measurement data while shifting the filter period in a filter period exceeding twice the period in which the measurement data of the uneven portion is output. Shape measuring device characterized by.