GB2300476A - Pyrometer with laser emissivity measurement - Google Patents
Pyrometer with laser emissivity measurement Download PDFInfo
- Publication number
- GB2300476A GB2300476A GB9507653A GB9507653A GB2300476A GB 2300476 A GB2300476 A GB 2300476A GB 9507653 A GB9507653 A GB 9507653A GB 9507653 A GB9507653 A GB 9507653A GB 2300476 A GB2300476 A GB 2300476A
- Authority
- GB
- United Kingdom
- Prior art keywords
- measuring
- emissivity
- reflectivity
- detector
- light source
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000005259 measurement Methods 0.000 title claims abstract description 27
- 238000002310 reflectometry Methods 0.000 claims abstract description 21
- 230000005855 radiation Effects 0.000 claims abstract description 13
- 238000000034 method Methods 0.000 claims description 17
- 238000009529 body temperature measurement Methods 0.000 claims description 12
- 230000010363 phase shift Effects 0.000 claims description 10
- 239000010438 granite Substances 0.000 abstract description 3
- 239000007787 solid Substances 0.000 abstract 1
- 238000004519 manufacturing process Methods 0.000 description 10
- 230000003287 optical effect Effects 0.000 description 5
- 230000008569 process Effects 0.000 description 5
- 230000008901 benefit Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000012937 correction Methods 0.000 description 2
- 238000012369 In process control Methods 0.000 description 1
- 230000003044 adaptive effect Effects 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000010965 in-process control Methods 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/0022—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiation of moving bodies
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/52—Radiation pyrometry, e.g. infrared or optical thermometry using comparison with reference sources, e.g. disappearing-filament pyrometer
- G01J5/53—Reference sources, e.g. standard lamps; Black bodies
Abstract
The device 14 for measuring the temperature of a heated body 10 comprises an infra-red pyrometer 15 for measuring the infra-red radiation emitted from the body 10 and an emissivity measurement device 16. The emissivity measurement device 16 includes a modulated laser light source and a photodiode detector (fig. 2) which are arranged to measure the reflectivity of the body 10 and from this calculate the emissivity of the body. The body referred to is a granite calender roll in a papermaking machine. Means are described (figure 3) for collecting laser light reflected from the surface from a solid angle so as to receive light that is both specularly and diffusely reflected from the calender.
Description
IXPROVEXENTS RELATING TO NON-CONTACT
TEMPERATURE MEA8VREMENT This invention concerns improvements relating to non-contact temperature measurement and particularly, though not exclusively, to an apparatus for measuring the temperature of a heated calender roll in a papermaking machine.
In the papermaking industry, paper is smoothed and pressed by large granite calenders which are heated electrically. It is essential to ensure that the surface of the calender is at a uniform temperature within predetermined working limits, since otherwise the calender can disintegrate with disastrous results. Accordingly, various methods have been used to measure the temperature at the surface of the granite calender.
One such method has been to use thermocouples provided at the ends of drilled holes just below the surface of the calender. This method does provide an accurate measure of temperature in the vicinity of each thermocouple. However, if the temperature of the entire calender is to be monitored, the required number of drilled holes and thermocouples becomes prohibitively large. In addition, there is always a danger that a thermocouple hole may ruin the calender by breaking through its surface. Accordingly, there has been a move away from this type of temperature measurement.
Non-contact temperature sensing of calender rolls has been carried out by use of an infra-red pyrometer which measures the radiation being emitted from the calender. For a black body (a perfect radiator), the emitted radiation is proportional to the temperature of the body. However, in practice objects to be measured do not behave as black bodies and a correction factor (emissivity) has to be calculated.
The emissivity can either be estimated as a fixed value or be determined for a sample calender by testing under laboratory conditions, the results being applied as an estimate for all calenders. However, under working conditions, emissivity can vary over a wide range of values during temperature measurement due to changes in surface conditions of the calender brought about by aspects of the paper production process that cannot be easily anticipated.
A two colour pyrometer, measuring emitted radiation at two different wavelengths, could in theory be used to cancel out the unpredictable changes in emissivity that occur during production processes, the two wavelengths of measurement being spaced far apart in order to achieve sufficient sensitivity.
However, this approach relies on the emissivity at the two different wavelengths being the same, which is not achievable in practice. Two colour pyrometers are therefore inherently inaccurate and have not been successful and are not readily available commercially.
The present invention aims to overcome at least some of the above problems and to provide a noncontact temperature measurement apparatus which is capable of accurately measuring the temperature of a body regardless of its changing surface condition during a production process.
Therefore, according to one aspect of the present invention there is provided a non-contact temperature measurement apparatus for measuring the temperature of a heated body, the apparatus comprising an infra-red pyrometer for measuring the infra-red radiation emitted from the body and means for measuring the emissivity of the body as a function of the reflectivity of the body.
The reflectivity can simply be measured by use of a light source and a detector. A significant advantage of measuring the reflectivity of the body is that the emissivity can be measured in real-time without the need for estimates. Manufacturing processes can therefore be made adaptive to changes in emissivity during operation of the processes.
Another advantage is that the measurement of reflectance can be used to detect surface imperfections, such as scratches and pits, as well as changes in surface conditions, such as coating streaks.
Preferably, in addition to a light source and a detector, the measuring means further comprises means for modulating the intensity of the light source and means for demodulating the output of the detector.
This has the advantage of overcoming problems with stray light, of the same wavelength as the light source, distorting the detected signal. In practice, the light source and the detector may be arranged to operate at visible light wavelengths. Visible light wavelengths are used in preference to infra-red light wavelengths to avoid distortion of the reflectivity measurement caused by infra-red heat radiation of the body. In addition, the light source preferably comprises a laser diode and the detector preferably comprises a linear photodiode.
The modulating means may advantageously be connected to the demodulating means such that the modulation frequency can be used as an accurate reference by the demodulating means. Preferably, phase shifting means are provided between the modulating and demodulating means, the phase shifting means being arranged to shift the phase of the reference frequency by an amount corresponding to the phase shift caused by the reflection of the modulated light. The phase shifting means may advantageously be adjustable to adjust the phase of the reference frequency. By this means the reference frequency can always be in phase with the reflected signal for demodulation and may be adaptable to different types of surfaces which cause different degrees of phase shifts.
Preferably, the measuring means may comprise focussing means for focussing light from the light source onto a surface of the body. Focussing of the illuminating light improves the accuracy of the reflectivity measurement. In addition, the focussing means may be arranged also to focus light reflected from the body to the detector. This can advantageously reduce the number of components in the measuring means as well as its overall size.
Alternatively, the measuring means may comprise additional focussing means for focussing light reflected from the body to the detector.
The pyrometer and the measuring means may be mounted on a movable carriage which can scan across a surface of the body and measure the temperature variation thereacross. Therefore, a large body, such as a calender, can have its temperature monitored over its entire surface by a single non-contact temperature measurement apparatus.
In a production line process, absolute measurement of the emissivity is in general not required because calibration of the production line system can be carried out before initiating the production line process. The use of the temperature measuring apparatus of the present invention in such a system allows for corrections to be made to the calibration due to process changes while the process is running.
According to another aspect of the present invention there is provided a method of non-contact temperature measurement of a heated body, said method comprising measuring infra-red radiation emitted from the body and measuring the emissivity of the body, said emissivity measuring being effected as a function of the reflectivity of the body, for example by illuminating said body from a light source and detecting light reflected from the body with a detector.
The above and further features of the present invention are set out with particularity in the appended claims and, together with the advantages thereof, will become clearer from consideration of the following detailed description of an exemplary embodiment of the invention given with reference to the accompanying drawings. In the drawings:
Figure 1 is a schematic diagram showing a noncontact temperature measurement apparatus embodying the present invention and being used in measuring the temperature of a calender;
Figure 2 is a schematic diagram showing an emissivity measurement device for use in the noncontact temperature measurement apparatus of Figure 1; and
Figure 3 is a schematic diagram showing the optical configuration of the emissivity measurement device of Figure 1.
Referring now to Figure 1, there is shown an exemplary embodiment of the present invention for use in the papermaking industry for measuring the temperature of a calender 10. The calender 10, shown in cross-section in Figure 1, is heated and rotates in direction 11 about an axis 12 to compress and flatten paper (not shown) which comes into contact with the outer surface 13 of the calender 10. A non-contact temperature sensing apparatus 14 includes an infra-red pyrometer 15 and an emissivity measurement device 16 provided at opposite sides of a carriage 17. The carriage 17 is mounted on a traversing head 18 which can move along the calender 10 substantially parallel to the axis 12 of the calender 10 to give a temperature profile along the calender.In this way, the temperatures across the entire surface 13 of the calender 10 can be measured in real-time during a production process when the calender is rotating.
The infra-red pyrometer 15 is directed towards the calender surface 13 and measures infra-red radiation emitted from the calender 10. In addition, this measurement includes any infra-red radiation that is reflected from the surface 13 of the calender 10 into the pyrometer together with any stray infra-red radiation incident on the pyrometer.
The measurement device 16 is arranged to measure the emissivity of the calender 10 as a function of the reflectivity of its surface 13. The measurement device 16 generates a light beam 19 which is directed to a part of the surface 13 of the calender 10. The light beam 19 is reflected from the surface 13 of the calender 10 back to the measurement device 16 where the amount of reflected light is measured. The reflectivity of that portion of the surface 13 is a ratio of the intensity of the detected light to the intensity of the transmitted light, and is proportional to the emissivity of the surface at that portion.Once the emissivity has been determined, the temperature of the calender can be calculated from the output of the pyrometer by using the following simple relationship:
To oc R - e equation (1) where To = temperature of the surface of the body
R = the amount of radiation detected from
the body
E = the emissivity of the body.
Referring now to Figure 2, a schematic block diagram of the measurement device 16 is shown. The measurement device 16 comprises a laser diode 20 for generating a light beam 21 at a visible light wavelength and a linear photodiode 22 for detecting the light beam 21 reflected from the surface 13 of the calender 10.
The laser diode 20 is intensity modulated by a modulating signal of 2.01KHz which is provided by an oscillator 23. The frequency of the modulating signal is chosen to be well out of 1/f noise, to be much higher than the frequency of ambient light fluctuations that might affect the results, and not to be a multiple of power line frequencies. Any other modulating frequencies which meet these criteria may be used for the modulating signal.
The oscillator 23 sends the modulating signal to a phase shifter 24 where the phase of the modulating signal is shifted an amount corresponding to the inherent phase shift caused by the surface reflection of the light beam 21. The phase shifter 24 has an adjustable phase shift to accommodate different degrees of phase shift caused by reflection from different types of surfaces. The phase shifted modulating signal is combined with the output of the linear photodiode 22 at a multiplier 25 where these signals are multiplied together. The output of the multiplier 25 is filtered by a low pass filter 26 to provide an output voltage which is proportional to, and therefore a measure of, the reflectivity of the surface 13.
The output R of the pyrometer 15 and the emissivity e derived from the measured reflectivity can be used in equation 1 to calculate the temperature
To of the calender 10.
A detailed example showing how the signals are processed by the measurement device 16 to derive the reflectivity is set out below:
The oscillator generates the modulating signal: vl cos (wt)
where v, = the amplitude of the modulating
signal; and
w = 2nf, f being the frequency of the
modulating signal.
The phase shifter shifts the modulating signal to
give: v1 cos(wt+#1) where #1 = the adjustable phase shift angle.
The linear photodiode 23 receives a signal: v2 cos(wt+#2) + v3 cos (w1 t)
where v2 = the amplitude of the reflected
signal; v3 = the amplitude of ambient light
fluctuations;
w1 = 2#f, fl being the relatively low
frequency of the ambient light
fluctuations; and 02 = the phase shift in the received signal observed at the
photodiode.
The signal received by the photodiode is
multiplied by the phase shifted modulation signal
giving the result:
V1 = {v1 cos (wt+#1)}x{v2 cos (wt+)+V3 cos (w1 t)} - v1y2 cos (#1-#2 + v1v2 cos (2wt+02+#1)+ 2 2
v1v3 cos ((w+w1)t+#1)+v1v3 cos ((w-w,) t+#1) 2 2 This signal is then low pass filtered giving the
output::
V2 v1v2 COS (#2-#1) 2
However, the reflectivity R = v2 and so v1 V2 = Rv12 cos (02-l) 2
If v1, #1 and #2 are constant the output voltage V2 of the measurement device 16 is a measure of the reflectivity R. Also if the phase shifter 24 is adjusted to match the two phase shifts, i.e. = then cos(2-1)=l giving a maximum output signal V2.
Furthermore, many small deviations in 2 about this set point produce a minimal change in V2 because dV2 = 0.
d92 Referring now to Figure 3, an exemplary optical configuration for the measurement device 16 is shown.
The measurement devices includes optical focussing arrangement 30 for directing the light beam 21 from the laser diode 20 onto the target surface 13 and also for focussing the reflected light from the surface to the photodiode 22. The laser diode 20 includes a focussing device (not shown) for focussing its light output into the light beam 21, and the light beam 21 is reflected by a mirror 31 and passes through the centre of a lens 32 onto the surface 13 to produce an illuminated spot. Reflected light 33 is then refocussed by the lens 32 to produce an image of the illuminated spot at the photodiode 22.
This optical configuration allows the measurement device 16 to be constructed in a compact and minimal sized enclosure. In addition, if the surface 13 is not uniform, having scratches or pits for example, the reflected light 33 will not be reflected directly back towards the centre of the lens 32, rather it will spread out (scatter) as shown in Figure 3. The illustrated optical arrangement enables these scattered reflections to be focussed onto the photodiode 22.
The temperature sensing apparatus 14 of the present embodiment is well suited for use in process control in a papermaking production line. In particular, the apparatus 14 would provide real-time feed back of temperature measurement to a controller which would control the temperature of the calender.
Having thus described the invention by reference to a specific embodiment, it is to be appreciated that the described embodiment is exemplary only and is susceptible to modification and variation without departure from the spirit and scope of the invention as set forth in the appended claims. For example, whereas the invention has been described in the foregoing with reference to measurement of the temperature of a calender roll in a papermaking application it could alternatively be used for measuring the temperature of any heated body in any industrial process. In addition, whereas a laser diode and photodiode are used as the light source and detector in the described embodiment, other light sources such as light emitting diodes, lamps, etc., and other detectors such as light dependent resistors, photo-transistors, etc., could alternatively be used.
Also a non-linear photodiode could be used as the detector. In this case, internal feedback would be provided to maintain quiescent gain condition with ambient light fluctuations. Furthermore, it is possible that for some applications the infra-red pyrometer is not required and only the reflectivity measurement is necessary, and the invention in another of its aspects is to be regarded as embracing this possibility.
Claims (21)
1. A non-contact temperature measurement apparatus for measuring the temperature of a heated body, the apparatus comprising:
an infra-red pyrometer for measuring the infrared radiation emitted from the body; and
means for measuring the emissivity of the body as a function of the reflectivity of the body.
2. An apparatus as claimed in claim 1 wherein the emissivity measuring means comprises a light source for illuminating the body and a detector for detecting light reflected from the body.
3. An apparatus as claimed in claim 2, wherein said measuring means further comprises means for modulating the intensity of the light source and means for demodulating an output of the detector.
4. An apparatus as claimed in claim 3, wherein the modulating means is operatively coupled to the demodulating means such that the modulating frequency can be used as a reference frequency by the demodulating means.
5. An apparatus as claimed in claim 4, further comprising phase shifting means connected between said modulating means and said demodulating means, said phase shifting means being arranged to shift the phase of the reference frequency by an amount substantially equivalent to the phase shift caused by reflection of the modulated light.
6. An apparatus as claimed in claim 5, wherein said phase shifting means is adjustable for adjusting the phase shift of the reference frequency.
7. An apparatus as claimed in any of claims 2 to 6 wherein said light source comprises a laser diode.
8. An apparatus as claimed in any of claims 2 to 7 wherein said measuring means further comprises:
focussing means for focussing light from the light source onto a surface of the body.
9. An apparatus as claimed in claim 8, wherein said focussing means is arranged to focus light reflected from said body to said detector.
10. An apparatus as claimed in claim 8, wherein said measuring means further comprises additional focussing means for focussing light reflected from the body to the detector.
11. An apparatus as claimed in any of claims 2 to 10 wherein said detector comprises a linear photodiode.
12. An apparatus as claimed in any of claims 2 to 11 wherein said light source and detector are arranged to operate at visible light wavelengths.
13. An apparatus as claimed in any preceding claim, wherein the measuring means further comprises a low pass filter.
14. An apparatus as claimed in any preceding claim, wherein said pyrometer and measuring means are mounted on a movable carriage, said carriage being arranged to scan across a surface of said body to measure temperature variations thereacross.
15. An apparatus as claimed in any preceding claim wherein said measuring means is arranged to monitor the surface reflectivity of the body to identify surface imperfections thereon.
16. A method of non-contact temperature measurement of a heated body, said method comprising:
measuring infra-red radiation emitted from the body: and
measuring the emissivity of the body as a function of the reflectivity of the body.
17. A method as claimed in claim 16 wherein the emissivity measurement is effected by illuminating the body from a light source and detecting light reflected from the body with a detector.
18. A method as claimed in claim 17, further comprising modulating the intensity of the light source and demodulating the detected light reflected from the body.
19. An apparatus or method substantially as herein described with reference to the accompanying drawings.
20. An apparatus for measuring the emissivity of a body, said apparatus comprising means for measuring the reflectivity of the body.
21. A method of measuring the emissivity of a body, said method comprising measuring the reflectivity of the body, and deriving the emissivity measurement as a function of the reflectivity measurement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9507653A GB2300476A (en) | 1995-04-12 | 1995-04-12 | Pyrometer with laser emissivity measurement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9507653A GB2300476A (en) | 1995-04-12 | 1995-04-12 | Pyrometer with laser emissivity measurement |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9507653D0 GB9507653D0 (en) | 1995-05-31 |
| GB2300476A true GB2300476A (en) | 1996-11-06 |
Family
ID=10772989
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9507653A Withdrawn GB2300476A (en) | 1995-04-12 | 1995-04-12 | Pyrometer with laser emissivity measurement |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2300476A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19922278A1 (en) * | 1999-05-11 | 2000-11-16 | Friedrich Schiller Uni Jena Bu | Method for determining the emission and absorption levels of objects uses different intensities from a narrow-band radiation source to irradiate a test object in flow-measuring flumes and a sensor to measure an object's radiation. |
| EP1091200A3 (en) * | 1999-10-06 | 2003-01-29 | Axcelis Technologies, Inc. | System and method for determining stray light in a thermal processing system |
| DE102006023190A1 (en) * | 2006-05-17 | 2007-11-22 | BSH Bosch und Siemens Hausgeräte GmbH | Temperature sensing device |
| DE10338582B4 (en) * | 2003-08-22 | 2011-08-11 | MTU Aero Engines GmbH, 80995 | Method for measuring a parameter of a coating |
| DE102010015858A1 (en) * | 2010-03-08 | 2011-09-08 | Andritz Küsters Gmbh | Solidifying a filament made of thermoplastic material comprising layer, to a fleece web, in which layer is conducted through roller gap formed between first and second roller, and one of the rollers is heated |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4417822A (en) * | 1981-01-28 | 1983-11-29 | Exxon Research And Engineering Company | Laser radiometer |
| US4647774A (en) * | 1985-03-04 | 1987-03-03 | Quantum Logic Corporation | Pyrometer #2 |
| US4799788A (en) * | 1986-08-08 | 1989-01-24 | Electricite De France Service National | Process for measuring the temperature of a body by optical detection and modulated heating |
| US5156461A (en) * | 1991-05-17 | 1992-10-20 | Texas Instruments Incorporated | Multi-point pyrometry with real-time surface emissivity compensation |
| EP0605055A2 (en) * | 1992-12-29 | 1994-07-06 | Koninklijke Philips Electronics N.V. | Pyrometer including an emissivity meter |
-
1995
- 1995-04-12 GB GB9507653A patent/GB2300476A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4417822A (en) * | 1981-01-28 | 1983-11-29 | Exxon Research And Engineering Company | Laser radiometer |
| US4647774A (en) * | 1985-03-04 | 1987-03-03 | Quantum Logic Corporation | Pyrometer #2 |
| US4799788A (en) * | 1986-08-08 | 1989-01-24 | Electricite De France Service National | Process for measuring the temperature of a body by optical detection and modulated heating |
| US5156461A (en) * | 1991-05-17 | 1992-10-20 | Texas Instruments Incorporated | Multi-point pyrometry with real-time surface emissivity compensation |
| EP0605055A2 (en) * | 1992-12-29 | 1994-07-06 | Koninklijke Philips Electronics N.V. | Pyrometer including an emissivity meter |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19922278A1 (en) * | 1999-05-11 | 2000-11-16 | Friedrich Schiller Uni Jena Bu | Method for determining the emission and absorption levels of objects uses different intensities from a narrow-band radiation source to irradiate a test object in flow-measuring flumes and a sensor to measure an object's radiation. |
| DE19922278B4 (en) * | 1999-05-11 | 2004-02-12 | Virtualfab Technologie Gmbh | Procedure for determining the degree of emission or absorption of objects |
| EP1091200A3 (en) * | 1999-10-06 | 2003-01-29 | Axcelis Technologies, Inc. | System and method for determining stray light in a thermal processing system |
| DE10338582B4 (en) * | 2003-08-22 | 2011-08-11 | MTU Aero Engines GmbH, 80995 | Method for measuring a parameter of a coating |
| DE102006023190A1 (en) * | 2006-05-17 | 2007-11-22 | BSH Bosch und Siemens Hausgeräte GmbH | Temperature sensing device |
| DE102010015858A1 (en) * | 2010-03-08 | 2011-09-08 | Andritz Küsters Gmbh | Solidifying a filament made of thermoplastic material comprising layer, to a fleece web, in which layer is conducted through roller gap formed between first and second roller, and one of the rollers is heated |
| DE102010015858B4 (en) * | 2010-03-08 | 2012-01-26 | Andritz Küsters Gmbh | Solidification process of a filament of thermoplastic material comprising layer to a nonwoven web and thermobonding calender |
Also Published As
| Publication number | Publication date |
|---|---|
| GB9507653D0 (en) | 1995-05-31 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |