GB2539172A

GB2539172A - Circumferential surface profile measurement device

Info

Publication number: GB2539172A
Application number: GB1507198.8A
Authority: GB
Inventors: Yang Jiannan
Original assignee: Hitachi Ltd
Current assignee: Hitachi Ltd
Priority date: 2015-04-28
Filing date: 2015-04-28
Publication date: 2016-12-14
Anticipated expiration: 2035-04-28
Also published as: GB201507198D0; GB2539172B

Abstract

A measurement device 1 for measuring a circumferential surface profile of a wheel 6 comprises a base 2 mounted at a position axially and radially fixed relative to the rotation axis of the wheel 6 and a probe 8a-c ending in a measurement head 10a-c. Measurement head 10a-c measures the radial position of a location on the surface profile relative to the rotation axis. Rotation of probe 8a-c relative to the wheel 6 allows it to detect variation in the measured radial position with distance around the surface profile. Base 2 may be removable such that the device can measure surface profiles of different wheels. Measurement head 10a-c may measure surface profiles of different diameters and/or may move in the axial direction relative to the base 2. Measurement head 10a-c may be contactless or may be a contact head biased to keep it in contact with the surface profile. There may be a reference probe 8b which measures the radial position of a location on the surface profile relative to the rotation axis and may be rotatably fixed relative to the wheel axis 4. There may be a recorder and/or a transmitter. There may be a processor calculating wavelengths of surface roughness around the surface profile from the detected variation in radial position. This device may be used on a wheel of a railway vehicle during maintenance related monitoring.

Description

CIRCUMFERENTIAL SURFACE PROFILE MEASUREMENT DEVICE Field of the Invention The present invention relates to the measurement of the circumferential surface profile of a wheel.

Background

Surface roughness of railway vehicle wheels can induce vibration in both the vehicle and railway track. Along with the resultant noise (which is proportional to vehicle speed and inversely proportional to the wavelength of the surface roughness), this can be unpleasant for passengers. The vibration can also increase the rate of wear of the wheel and the track.

It is therefore desirable to monitor the roughness of railway wheels in order to determine when maintenance is required so that the required level of acoustic and dynamic performance of the railway can be maintained.

The roughness of the wheel surface can be determined from measurements of the circumferential surface profile. Existing devices which measure the circumferential surface profile require the railway wheel to be lifted from the track so that the wheel can be rotated, and then measure the surface profile relative to the rail. However, this approach is time-consuming and inconvenient. Once lifted, the measurements are taken while the wheel is rotated by at least one complete revolution, as the wheel roughness is regarded as periodic over a complete circumference. However, as the relevant acoustic wavelength range is less than 250mm, which is much less than the length (about 3 m) of a typical circumferential surface profile of a railway wheel, the data recorded using existing devices is often over-defined for engineering purposes.

Summary

The existing methods of measuring the circumferential surface profile are primarily used for research and are inconvenient for maintenance-related or in-service monitoring measurement of the circumferential surface profile of the wheel. Thus it would be desirable to provide an alternative device for measuring the surface profile of a wheel, which addresses the above issues.

Accordingly, in a first aspect, the present invention provides a measurement device for measuring a circumferential surface profile of a wheel, such as a railway vehicle wheel, the device including: a base which is configured such that the base is mountable at a position which is axially and radially fixed relative to the rotation axis of the wheel; and a probe extending from the base to a measurement head which measures the radial position of a location on the circumferential surface profile relative to the rotation axis, the probe being rotatable around the axis of the wheel; wherein rotation of the probe relative to the wheel allows the probe to detect variation in the measured radial position with distance around the circumferential surface profile.

In the case of for example a railway vehicle wheel, the present invention is at least partly based on a recognition that surface profile measurements do not necessarily need to be taken around the complete circumference of the wheel. In particular, measurements to determine surface roughness that produces relevant acoustic noise may only be required over a fraction of the complete circumference. Accordingly, the present invention provides a measurement device that does not require the wheel to be lifted or indeed rotated. Further, once fitted, the device can take measurements speedily. Furthermore, as the device takes measurements relative to the wheel's rotation axis, rather than the rail, the measurements can be used as an indication of the surface wear of the wheel.

In a second aspect, the present invention provides a wheel, such as a railway vehicle wheel, fitted with a measurement device for measuring a circumferential surface profile of the wheel according to the first aspect, the base being mounted at a position which is axially and radially fixed relative to the rotation axis of the wheel. Conveniently, the measurement device may have the base mounted at an axle of the wheel.

In a third aspect, the present invention provides use of a measurement device according to the first aspect for detecting variation in measured radial position with distance around a circumferential surface profile of a wheel, such as a railway vehicle wheel. The use may further include calculating wavelengths of surface roughness around the circumferential surface profile from the detected variation in the measured radial position.

Optional features of the invention will now be set out. These are applicable singly or in any combination with any aspect of the invention.

The base may be removably mountable at the fixed position such that the device can be used to measure circumferential surface profiles of different wheels.

The probe may be configured such that its measurement head can be moved to measure circumferential surface profiles having different diameters. In this way, the device can be used on wheels of different sizes, and/or can accommodate the conical taper which is typically used on railway vehicle wheels.

The probe may be configured such that its measurement head can be moved in the axial direction relative to the base. In this way, different axial distances between the fitting position of the base and the selected circumferential surface profile can be accommodated.

The measurement head may be a contact head which makes physical contact with the surface profile. Furthermore, the probe may be biased to keep the contact head in contact with the surface profile. For example, the contact head may use spring biasing to keep the contact head in contact with the surface profile.

The measurement head may be a contactless measurement head. For example, the contactless measurement head may be a light, e.g. LED or laser, reflection instrument which uses light reflection off a location on the circumferential surface profile to measure its radial position.

As mentioned above, the relevant acoustic wavelength range is typically less than 250mm. Therefore, there is generally no need for the device to measure over the entire circumference (typically about 3m) of the wheel. However, in view of the range of relevant acoustic wavelengths, measurements over at least 500 mm of the circumference may be desirable. With just one probe, the probe's radial position measurement can be combined with a measurement or knowledge of its rotational speed or a measurement of its angular spacing from a reference location on the surface profile. In this way, the radial position measurements can be correlated to probe angular position. Another approach is for the measurement device to have plural probes extending to respective and angularly spaced measurement heads. This allows simultaneous measurement of the circumferential surface profile at multiple locations around the circumference of the wheel. For example, the measurement device may have three probes. Advantageously, when three probes are used, the radius of the wheel can be estimated directly from the recorded values, e.g. by fitting a circle to the three simultaneously measured radii. The first and the last of the angularly spaced measurement heads may be at least 60° apart.

The device may further have a reference probe extending from the base to a measurement head which measures the radial position of a location on the circumferential surface profile relative to the rotation axis, the reference probe being rotatably fixed relative to the axis of the wheel. Optional features of the rotatable probe(s) can pertain also to the reference probe. Preferably, when the device has a reference probe, it has two rotatable probes so that the radius of the wheel can be estimated by fitting a circle to the three simultaneously measured radii.

The measurement device may further include a recording unit which records the measured radial positions and/or a transmitter which transmits the measured radial positions.

The measurement device may further include a processor unit which calculates wavelengths of surface roughness around the circumferential surface profile from the detected variation in the measured radial position.

Brief Description of the Drawings

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a schematic cross-section of a railway vehicle wheel fitted with a measurement device for measuring a circumferential surface profile of the wheel, the cross-section containing the rotation axis of the wheel; Figure 2 shows schematically the railway vehicle wheel of Figure 1 viewed along its rotation axis; Figure 3 shows a synthetic example of a measured circumferential roughness profile; and Figure 4 shows a wavelength spectrum for the roughness profile of Figure 3. Detailed Description and Further Optional Features Figure 1 shows a schematic cross-section of a railway vehicle wheel 6 fitted with a measurement device 1 for measuring a circumferential surface profile of the wheel, the cross-section containing the rotation axis of the wheel. Figure 2 shows schematically the railway vehicle wheel of Figure 1 viewed along its rotation axis.

The measurement device 1 has a base 2 attached to an axle 4 of the wheel 6 such that the base 2 is in a position which is axially and radially fixed relative to the rotation axis of the wheel 6. Three probes 8a-c of the device 1 extend from the base 2 to respective measurement heads 10a-c. The measurement heads 10a-c are positioned so that they can each measure the radial position of a location on the same circumferential surface profile of the wheel 6. The two outer probes 8a, c can be rotated about the base 2, and hence about the axis of the wheel 6, while the inner probe 8b is rotationally fixed relative to the base 2 and provides a reference position on the surface profile. Thus the angular distance a between the probes can be varied by rotating the outer probes 8a, c. This rotation allows the outer probes 8a, c to detect variation in the measured radial position with distance around the circumferential surface profile without lifting the railway wheel 6 from the track. As the measurements are taken relative to the wheel's rotation axis, they can also be used as an indication of the surface wear of the wheel 6.

As illustrated, the measurement heads 10a-c are contact heads that make physical contact with the surface profile of the wheel 6. The contact heads may be biased, e.g. spring-biased, to ensure the heads stay in contact with the surface profile. However, an alternative arrangement may use contactless measurement heads such as LED or laser reflection instruments. These do not require biasing, and as they are not in contact with the surface profile and do not wear during use.

As the relevant acoustic wavelength range is less than 250mm it is generally desirable to obtain measurements over at least 500 mm of the circumference of the wheel 6. Given that the circumference of the railway vehicle wheel 6 is typically about 3 m, there is however no need to measure over the entire circumference. By using three angularly spaced measurement heads 10a-c, it is possible to estimate the radius of the wheel 6 from the recorded values, e.g. by fitting a circle to the three simultaneously measured radii.

The probes 8a-c are configured such that the measurement heads 10a-c can be moved to measure circumferential surface profiles with different diameters and such that the measurement heads 10a-c can have a different axial spacing from the base 2. Additionally, the base 2 is removably mountable so that the measurement device 1 can be used to measure the circumferential surface profiles of different wheels. The measurement device 1 can therefore be used to measure a circumferential surface profile at any point on the surface of a wheel, irrespective of the wheel's size and shape, e.g. wheels with a conical taper, whilst accommodating for different axial distances between the fitting position of the base 2 and the selected circumferential surface profile.

Although not shown in this arrangement, the measurement device 1 may further include a recording unit which records the measured radial positions, a transmitter which transmits the measured radial positions, and/or a processor unit which calculates wavelengths of surface roughness around the circumferential surface profile from the detected variation in the measured radial position or any combination of the three. These devices facilitate the recording and processing of measurement data. For example, the processor unit can Fourier transform time series data of the radius of the circle fitted to the three simultaneously measured radii in order to obtain the roughness amplitude of the wheel against roughness wavelength.

Variants of the device are possible. For example, one option is for the device to have just a single probe and measurement head. In this case a mark or other indicator can be made on the surface profile to provide a reference angular position for the measured radial position. If the probe is rotated at a constant angular velocity from the reference position to an end position, the radial position measurements can then be correlated to angular position. Other possibilities are to measure the angular velocity of the probe or to measure the probe's angular separation from the reference position to derive the same correlation.

Another option is for the device to have plural (e.g. three) probes in a fixed angular relation to each other, and then to rotate the base and hence all the probes around the axis of the wheel. For such a device, the first and the last of the measurement heads may be as little as 60° apart (i.e. a 30°). The angular spacing of the probes can be set so as to provide good estimates of wheel radius derived from circle fitting to simultaneously measured radii.

Figure 3 shows a synthetic example of a measured circumferential roughness profile for a railway vehicle wheel. Such a profile can be obtained e.g. from circle fitting to simultaneously measured radii, or from a single probe's radial position measurement, as discussed above. As the probe or probes move around the circumference of the wheel, the roughness profile, as a deviation from the perfect smooth profile, is recorded. In this example, around half of one complete circumference is measured. The process can be repeated if time is allowed to reduce measurement uncertainties. The roughness profile recorded can then be processed by converting it to the wavelength domain, as shown for example in Figure 4, which is a wavelength spectrum for the roughness profile of Figure 3.

Note that the wavelength axis of the spectrum is descending. This spectrum, stored in 1/3 octave band, can then be used for subsequent railway noise analysis.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

Claims

CLAIMS1. A measurement device for measuring a circumferential surface profile of a wheel, the device including: a base which is configured such that the base is mountable at a position which is axially and radially fixed relative to the rotation axis of the wheel; and a probe extending from the base to a measurement head which measures the radial position of a location on the circumferential surface profile relative to the rotation axis, the probe being rotatable around the axis of the wheel; wherein rotation of the probe relative to the wheel allows the probe to detect variation in the measured radial position with distance around the circumferential surface profile.
2. A measurement device according to claim 1, wherein the base is removably mountable at the fixed position such that the device can be used to measure circumferential surface profiles of different wheels.
3. A measurement device according to claim 1 or 2, wherein the probe is configured such that its measurement head can be moved to measure circumferential surface profiles having different diameters.
4. A measurement device according to any one of the previous claims, wherein the probe is configured such that its measurement head can be moved in the axial direction relative to the base.
5. A measurement device according to any one of the previous claims, wherein the measurement head is a contact head which makes physical contact with the surface profile.
6. A measurement device according to claim 5, wherein the probe is biased to keep the contact head in contact with the surface profile.
7. A measurement device according to any one of claims 1 to 4, wherein the measurement head is a contactless measurement head.
8. A measurement device according to any one of the previous claims, having plural probes extending to respective and angularly spaced measurement heads.
9. A measurement device according to claim 8, further having a reference probe extending from the base to a measurement head which measures the radial position of a location on the circumferential surface profile relative to the rotation axis, the reference probe being rotatably fixed relative to the axis of the wheel.
10. A measurement device according to any one of the previous claims, further including a recording unit which records the measured radial positions and/or a transmitter which transmits the measured radial positions.
11. A measurement device according to any one of the previous claims, further including a processor unit which calculates wavelengths of surface roughness around the circumferential surface profile from the detected variation in the measured radial position.
12. A wheel fitted with a measurement device according to any one of the previous claims for measuring a circumferential surface profile of the wheel, the base being mounted at a position which is axially and radially fixed relative to the rotation axis of the wheel.
13. A wheel according to claim 12, wherein the base is mounted at an axle of the wheel.
14. Use of a measurement device according to any one of claims 1 to 11 for detecting variation in measured radial position with distance around a circumferential surface profile of a wheel.Amendments to the Claims have been filed as follows:-CLAIMS 1. A measurement device for measuring a circumferential surface profile of a wheel, the device including: a base which is configured such that the base is mountable at a position which is axially and radially fixed relative to the rotation axis of the wheel; and a probe extending from the base to a measurement head which measures the radial position of a location on the circumferential surface profile relative to the rotation axis, the probe being rotatable around the axis of the wheel; wherein rotation of the probe relative to the wheel allows the probe to detect variation in the measured radial position with distance around the circumferential surface profile; and wherein the device further includes a processor unit which calculates wavelengths of surface roughness around the circumferential surface profile from the detected variation in the measured radial position.2. A measurement device according to claim 1, wherein the base is removably mountable at the fixed position such that the device can be used to measure circumferential CO surface profiles of different wheels.3. A measurement device according to claim 1 or 2, wherein the probe is configured such that its measurement head can be moved to measure circumferential surface profiles having different diameters.4. A measurement device according to any one of the previous claims, wherein the probe is configured such that its measurement head can be moved in the axial direction relative to the base.5. A measurement device according to any one of the previous claims, wherein the measurement head is a contact head which makes physical contact with the surface profile.6. A measurement device according to claim 5, wherein the probe is biased to keep the contact head in contact with the surface profile.7. A measurement device according to any one of claims 1 to 4, wherein the measurement head is a contactless measurement head.8. A measurement device according to any one of the previous claims, having plural probes extending to respective and angularly spaced measurement heads.9. A measurement device according to claim 8, further having a reference probe extending from the base to a measurement head which measures the radial position of a location on the circumferential surface profile relative to the rotation axis, the reference probe being rotatably fixed relative to the axis of the wheel.10. A measurement device according to any one of the previous claims, further including a recording unit which records the measured radial positions and/or a transmitter which transmits the measured radial positions.11. A wheel fitted with a measurement device according to any one of the previous claims for measuring a circumferential surface profile of the wheel, the base being mounted at a position which is axially and radially fixed relative to the rotation axis of the wheel.12. A wheel according to claim 11, wherein the base is mounted at an axle of the wheel.13. Use of a measurement device according to any one of claims 1 to 10 for detecting variation in measured radial position with distance around a circumferential surface profile of TM a wheel.O