JP2776446B2 - Shape measuring device - Google Patents

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 of an object having irregularities formed on an outer peripheral surface thereof.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 4, this type of shape measuring apparatus supports a rod-shaped measuring object (hereinafter referred to as "work") 1 rotatably around its axis. 1
A pair of tracing styluses 2 movable in the vertical direction on the outer peripheral surface 1a of the
2 is pressed and contacted. When the work 1 is rotated, the tracing styluses 2 and 2 move up and down along 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 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 unit 3 measures an outer shape including the cutout groove 4. However, when the rotation of the work 1 is fast, since the tracing stylus 2 jumps over the notch 4, the measurement data 5 is a measurement data portion (recess) 5 a of the notch 4 as shown in FIG. The measurement data portion 5b exceeding the threshold value becomes wavy. As a result, the shape of the measurement data section 5b cannot be accurately measured.

On the other hand, the rotation of the work 1
To prevent jumps and output measurement data 6
(See FIG. 6) is binarized with a threshold 7 (see FIG. 7) that does not include the measurement data section 5a in the measurement value, and there is a measurement method in which the measurement data section 5a is deleted. However, this method cannot completely delete the measurement data portion 6c of the chamfered portion of the notch 4 as shown in FIG.
However, there is a disadvantage that the shape cannot be measured accurately. The horizontal axis of the measurement data 5 and 6 shown in FIGS. 5 to 7 indicates the measurement time, and the vertical axis indicates the displacement of the measurement data.

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

[0006]

However, in the conventional shape measuring device, a positioning mechanism corresponding to the uneven portion outside the object to be measured must be attached to each work 1, so that it takes time and takes a long time for the measurement. There is a disadvantage that it requires. The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a shape measuring apparatus capable of easily obtaining measurement data excluding an uneven portion outside a 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 uneven surface such as a notched groove or a projection is formed on an outer peripheral surface. A measuring device, a measuring element that is in contact with an outer peripheral surface of the measuring object, and a measuring unit that measures an outer shape of the measuring object based on the movement of the measuring element, Means for sampling a signal output from the measuring unit at predetermined intervals and sequentially outputting measurement data, and a median value of continuous measurement data in a filter period exceeding twice a period during which the measurement data of the uneven portion is output. And a median filter that determines the filter period while shifting the filter period.

[0008]

According to the present invention, the signal output from the measuring section is sampled at predetermined intervals, the measurement data is sequentially output to a median filter, and the median filter performs a filtering process. Thereby, since the measurement data of the uneven portion outside the measurement target is removed by being filtered by the median filter, the measurement data excluding the uneven portion can be easily obtained without attaching the positioning mechanism to the measured object. be able to.

[0009]

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

The measuring section 12 includes a pair of tracing styluses 18, 18.
The tracing styluses 18 are supported so as to be movable in the vertical direction in the figure. Further, the tracing stylus 18, 18
It is provided vertically above and below the bar-shaped work 20, and its distal ends 18 a, 18 a are pressed against the outer peripheral surface 20 a of the work 20. The work 20 is rotatably supported by its axis, and notched grooves 21, 21 which are not to be measured are formed on the outer peripheral surface 20 a of the work.

A measuring section 16 is connected to the measuring elements 18 and 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 tracing stylus 18 caused by rotating the work 20. The median filter processing unit 16 includes an amplifier 22, an A / D converter 2
4, an analog signal output from the measuring section 14 is amplified by an 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 (to be 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, in the median filter, a median value of a continuous digital signal is obtained by shifting the filter period in a filter period that is more than twice as long as a period in which the digital signal in the notch 21 is output.

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

That is, a signal from which the digital signals [(−7.2, −7.3) and (−7.5, −7.9)] of the notch groove 21 are removed from the displacement amount is output from the CPU 26 to the display. Thereby, even if the notch groove 21 is actually measured by the tracing stylus 18, measurement data 32 as shown in FIG. 3 can be obtained. Therefore, according to the present embodiment, without attaching the positioning mechanism to the notch groove 21 of the work 20, the notch groove 2
Measurement data excluding 1 can be easily obtained.

In this embodiment, the cutout groove (recess) 21 has been described. However, a projection (projection) outside the measurement target can be similarly filtered by a median filter.
In this case, the filter period of the median filter may be set to a period that is more than twice the period during which the digital signal of the projection 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 measured data is sequentially output to the median filter. Filter processing. Thereby, since the measurement data of the uneven portion outside the measurement target is removed by being filtered by the median filter, the measurement data excluding the uneven portion can be easily obtained without attaching the positioning mechanism to the measurement object. Can be.

[Brief description of the 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 filter processing by a median filter applied to the shape measuring apparatus according to the present invention.

FIG. 3 shows measurement data indicating the outer diameter shape of a workpiece measured by the shape measuring device according to the present invention.

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

FIG. 5 shows measurement data indicating the outer diameter shape of a workpiece measured by a conventional shape measuring device.

FIG. 6 shows measurement data indicating the outer diameter shape of a workpiece measured by a conventional shape measuring device.

FIG. 7 is an explanatory diagram for performing binarization processing on work measurement data at a predetermined threshold value;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Shape measuring apparatus 12 ... Measuring part 14 ... Measuring part 16 ... Median filter processing part 18 ... Measuring element 20 ... Work 22 ... Amplifier 24 ... A / D converter 26 ... CPU

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Claims (1)

(57) [Claims] 1. A shape measuring device for measuring an outer diameter shape of a measured object having a concave and convex portion such as a notch groove, a projection or the like outside the object to be measured on an outer peripheral surface, wherein the measuring device is in contact with the outer peripheral surface of the measured object. A measuring element for measuring the external shape of the object to be measured based on the movement of the measuring element, a signal output from the measuring section is sampled at predetermined intervals and sequentially Means for outputting measurement data; and a median filter for obtaining a median of continuous measurement data in a filter period exceeding twice the period in which the measurement data of the uneven portion is output while shifting the filter period. A shape measuring device characterized by the above-mentioned.