JPH04319601A - Method and equipment for measuring precision of shape of round machined article - Google Patents

Abstract

PURPOSE:To obtain a method and equipment for measuring the precision of a shape of a machined article in rotation and enabling automation of measurement. CONSTITUTION:Detectors 2, 2 for measuring a diametric dimension are disposed so that they are opposed to a machined article 1 fitted to a spindle of a grinding machine and those detectors 2, 2 are connected to an arithmetic element 5 of a control device 4 through filter devices 3, 3 of which a filtering frequency can be changed. A proximity switch 13 detecting one rotation of the machined article is connected to the arithmetic element 5. The diametric dimension of the machined article in one rotation is measured, unevenness or indentation of the surface of the machined article is determined from a measured value of the dimension, and outof-roundness, roughness, etc., are calculated from this unevenness or the like.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] This invention is designed to improve the shape accuracy of circular workpieces such as rings and shafts, including the roundness, roughness, and generatrix shape.
The present invention relates to a measuring method and apparatus for measuring a workpiece while it is being rotated.

0002

[Prior art and its problems] Conventionally, accuracy control of workpieces on production lines at manufacturing plants, etc. has been carried out by conducting sampling inspections or 100% inspection of workpieces in each process, and checking the dimensions of the inspected workpieces and guarantee standards. This is done by comparing dimensions.

Among the precision of the workpiece managed in this way, the diameter dimension only needs to be detected by simply detecting the surface shape of the workpiece, so it can be directly detected during processing, and it is actually measured on the processing machine. It has also been possible to automatically measure the diameter dimensions of all workpieces.

On the other hand, shape accuracy such as roundness, roughness, and generatrix shape must be measured by placing the terminal of the detector in contact with the surface of the workpiece. Measurement is difficult, and in reality, workers manually measure the shape accuracy of workpieces extracted at regular intervals after processing.
The method used is to compare the measured value with standard dimensions.

[0005] For this reason, if a defect in shape accuracy is confirmed at the time of sampling inspection, it is necessary to measure and sort all of the workpieces before the inspection to see if they are defective. especially,
In recent grinding machines, the intervals between dressings have become dramatically longer due to the spread of highly wear-resistant grinding wheels such as CBN grinding wheels. Therefore, defects in shape accuracy such as roundness may occur during sampling inspections immediately after or during dressing. If this occurs, there is a problem in that a large number of defective products will be produced during the processing up to that point.

However, if the number of sampling inspections is increased in order to prevent the production of a large number of defective products, there is a problem that the burden on the worker increases and the processing efficiency decreases.

[0007] Therefore, in view of the above problems, the present invention
The purpose of this invention is to provide a measuring method that directly detects the shape accuracy of a rotating workpiece and automates the measuring work, and a measuring device that implements the method.

[0008]

[Means for Solving the Problems] In order to solve the above problems, the method of the present invention measures the diameter dimension of a rotating workpiece, and performs processing based on the measured value during one rotation of the workpiece. This method was developed to detect the shape accuracy of the surface of an object.

On the other hand, the apparatus of the present invention includes a spindle that rotates a workpiece at an arbitrary rotation speed, a detector that detects the diameter of the workpiece surface, and a detector that detects the diameter of the workpiece during one rotation. The present invention is configured to include calculation means for calculating the shape accuracy of the surface of the workpiece based on the measured values.

Furthermore, in the above device, a filter device capable of changing the filtering frequency may be provided on the signal path between the detector and the arithmetic device.

[0011]

[Operation] In the means of the present invention, the diameter of the workpiece is measured over its entire circumference, the undulations and uneven shape of the surface of the workpiece are determined from the measured values, and the roundness and roughness are determined from the undulations and the uneven shape. Calculate. Further, by extracting only a specific frequency component from the signal of the detector, it is possible to detect what kind of square shape the surface of the workpiece has.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show an example in which the present invention is applied to the measurement of shape accuracy when a ring-shaped workpiece is ground by a grinder.

As shown in FIGS. 2(a) and 2(b), the outer diameter surface of the workpiece 1 is slidably supported by a front shoe 20 and a rear shoe 21, and one end surface thereof is connected to a spindle 22 of a grinding machine. It is magnetically chucked by a packing plate 23, and in this state, the outer diameter surface is polished by a grinding wheel 24.

The workpiece 1 is located near the tip of the spindle 22.
A pair of detectors 2 facing each other to measure the outer diameter of the workpiece
, 2 are arranged, and each of the detectors 2, 2 is connected to a calculation section 5 of a control device 4 via a filter device 3, 3, as shown in FIG.

[0015] This control device 4 has a calculation function, a discrimination function,
A microcomputer having a data memory function, etc. is used, and includes the arithmetic unit 5 and a determination unit 6 that compares the output value from the arithmetic unit 5 with a reference value input and set from the outside and outputs a control signal. It is configured. Further, the control signal output from the determination unit 6 is output to an alarm device 7 that issues an alarm to the outside, and an automatic correction mechanism 8 that changes the cutting amount, dressing amount, etc. of the grindstone 24.

On the other hand, the filter device 3 includes a low-pass filter circuit 9 that removes high-frequency periodic noise components from the signals of the detectors 2 and stabilizes the accuracy of diameter measurement, and a It consists of a special filter circuit 10 for extracting frequency components and detecting the angular shape of the surface of the workpiece, both filter circuits 9 and 10 and each detector 2,
A switch 11 is provided to change over the connection with 2. In this case, the filtering frequency of the above-mentioned low-pass filter circuit 9 is normally set to around 2 Hz, but the filtering frequency of the special filter circuit 10 is appropriately set depending on the rotation speed of the workpiece at the time of measurement, and is generally several tens of Hz. A high frequency is set. Note that this filter device does not change the filtering frequency by switching between different filter circuits by operating a switch as described above, but instead uses an analog variable filter circuit that allows the filtering frequency to be set to an arbitrary value by adjusting the volume. You can also do it.

Further, in order to detect the timing of one rotation of the workpiece, a detector 12 such as a metal plate is attached to the circumferential surface of the packing plate 23 or the spindle 22.
Proximity switch 13 facing it and detecting detector 12
is provided. The signal from the proximity switch 13 is input to the calculation section 5 of the control device 4 as a timing signal.

This embodiment has the structure as described above, and its operation will be explained next. During machining, when measuring the outer diameter of the workpiece 1 using the detectors 2, 2, connect the switch 11 of each filter device 3, 3 to the low-pass filter circuit 9 side, and set the workpiece 1 for grinding. Predetermined number of rotations (200
~1000 rpm), the detectors 2, 2
Measure the diameter of the workpiece. After noise components are removed from the detection signals of the detectors 2, 2 in a low-pass filter circuit 9, the calculation unit 5 of the control device 4 calculates the dimension values, and the judgment unit 6 compares them with guaranteed standard dimensions. .

On the other hand, when measuring the shape accuracy of the workpiece 1, the switch 11 of each filter device 3, 3 is switched to the special filter circuit 10, and in this state, the workpiece 1 is rotated at a low speed, and the proximity switch 13 1 of workpiece 1 by the signal of
The outer diameter dimension of the workpiece 1 over the entire circumference is detected by the detectors 2 at the timing of the rotation.

The signal detected in this way is shown in (a) in FIG.
), it becomes a signal indicating the undulations and uneven shape of the surface of the workpiece 1, and by comparing the size of these undulations and irregularities with the standard shape of the workpiece, the waviness and roughness of the workpiece surface can be detected. can.

[0021] Furthermore, as shown in Fig. 3(b), the roundness of each type of undulation and unevenness may be determined geometrically or experimentally in advance according to the size of each type of undulation and unevenness, and stored in a data memory. By comparing the roundness data with the size of the undulations obtained as shown in FIG. 3(a), it is possible to evaluate and determine the roundness of the workpiece 1.

Furthermore, by rotating the workpiece 1 at a low speed and extracting only low frequency components from the signals from the detectors 2, the number of squares on the surface of the workpiece can be determined. For example, the rotation of the workpiece is 60 rpm (1 rps; 1 rotation per second), and the filtering frequency of the special filter circuit 10 is 17H.
When set to z, 17 (Hz)/1 (rps) = 17 (
It is possible to detect the number of angles up to 17 angles from the equation.

[0023] After calculating the shape accuracy in this way, next,
It is compared with the guaranteed standard value in the determination section 6, and when the deviation exceeds the allowable amount, an alarm is issued from the alarm device 7 to notify the operator. Further, the automatic correction mechanism 8 changes the cutting depth and dressing amount of the grindstone to perform automatic correction. Thereby, the shape accuracy of the workpiece 1 can be continuously and automatically measured after the grinding process, and it is possible to prevent a large number of defective products from being produced.

FIGS. 4(a) and 4(b) show an example in which the inner diameter surface of the ring-shaped workpiece 1' is ground by the grinding wheel 24'. consists of two shoes 20', 21' and a packing plate 23'.
supported by a magnetic chuck.

In the above embodiment, the workpiece is rotated at a low speed when measuring the shape accuracy, but the filtering frequency of the special filter circuit 10 is set higher to increase the detection accuracy of the number of squares. , it is also possible to continuously measure the rotational speed during machining.

Further, although an example of detection at the grinding position has been shown, if the workpiece can be kept in a rotating state, detection can also be performed not only at the grinding position but also during transportation to the next process. Furthermore, although we have given an example in which the workpiece is supported by a shoe and a magnetic chuck, it can also be applied to machining with a cylindrical grinder that supports and grinds a shaft workpiece at both centers, and can also be used for machining other than grinding such as turning. It can also be implemented in the same way.

[0027]

[Effects] As described above, this invention calculates the shape accuracy of the workpiece from the diameter dimension, making it possible to automate measurement and prevent the production of a large number of defective products. This has the effect of stabilizing the quality of the product.

[Brief explanation of drawings]

[Fig. 1] Block diagram showing the measuring device of the example

[Figure 2]a
is a partially longitudinal front view showing the support structure of the workpiece, and b is a longitudinal side view thereof.

[Figure 3] A is a graph showing the detector signal, and b is a diagram showing data for detecting roundness.

FIG. 4 a is a partially longitudinal front view showing a workpiece support structure of another embodiment, and b is a longitudinal side view thereof.

[Explanation of symbols]

1 Processed product 2 Detector 3 Filter device 4 Control device 5 Arithmetic section 6 Judgment section 8 Automatic correction mechanism 12 Detector 13 Proximity switch

Claims (3)

[Claims] 1. A shape of a circular workpiece, characterized in that the diameter dimension of the workpiece in a rotating state is measured, and the shape accuracy of the workpiece surface is detected based on the measured value during one rotation of the workpiece. Accuracy measurement method. 2. A spindle that rotates a workpiece at an arbitrary rotation speed, a detector that detects the diameter dimension of the workpiece surface, and a sensor that detects the diameter of the workpiece surface based on the measured value detected during one rotation of the workpiece. 1. A shape accuracy measuring device for a circular workpiece, comprising: calculation means for calculating the shape accuracy of a surface of the workpiece. 3. The apparatus for measuring the shape accuracy of a circular workpiece according to claim 2, further comprising a filter device that can change a filtering frequency on a signal path between the detector and the arithmetic device.