CA1320757C - Method of detecting surface damages in the stone roll of the press section of a paper machine or the like - Google Patents
Method of detecting surface damages in the stone roll of the press section of a paper machine or the likeInfo
- Publication number
- CA1320757C CA1320757C CA000570105A CA570105A CA1320757C CA 1320757 C CA1320757 C CA 1320757C CA 000570105 A CA000570105 A CA 000570105A CA 570105 A CA570105 A CA 570105A CA 1320757 C CA1320757 C CA 1320757C
- Authority
- CA
- Canada
- Prior art keywords
- roll
- stone
- stone roll
- holder
- doctor blade
- 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.)
- Expired - Lifetime
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/08—Pressure rolls
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
- D21F3/00—Press section of machines for making continuous webs of paper
- D21F3/02—Wet presses
- D21F3/04—Arrangements thereof
Landscapes
- Paper (AREA)
- Crushing And Grinding (AREA)
Abstract
Abstract The invention relates to a method of detecting sur-face damages in a stone roll of a press section in a paper machine or the like. The stone roll is provided with a doctor blade arranged in a pivotable holder so as to extend over the whole length of the roll for scraping the surface of the roll. In order that sur-face damages in the stone roll could be detected during the run, shocks exerted on the doctor blade due to surface damages in the stone roll are recorded by acceleration transducers arranged in the holder. The signal obtained from each transducer is summed in a synchronized manner with the rotation of the roll.
(Figure 2)
(Figure 2)
Description
~t~2~7~7 A method of detecting surface damages in the stone roll of the press section of a paper machine or the like The invention relates to a method of detecting surface damages in a stone roll of a press section in a paper machine or the like, said stone roll being provided with a doctor blade arranged in a pivotable holder so as to extend over the whole length of the roll for scraping the sur~ace of the roll.
At present, stone rolls are used e.g. in the press sections o paper machines. In a modern paper machine the proper press of the press section can be formed e.g. by four rolls which are so positioned with respect to each other that they form three press nips.
One of these four rolls is made of stone, gen-erally granite. The granite shell of ~he stone roll is made in one piece by quarrying, machining and finally grinding. A stone roll so obtained is an expensive component, which is used for its good properties. Good practical properties include the micro structure and the anti-static quality of the surface.
However, cracks may be formed in stone rolls in use which damage the roll when expanding. At worst such cracks may result in total breakage of the roll during the run. Such a roll explosion has extramely serious consequences. In practice, the stone mass of the roll, e.g. about 70 tons, breaks the entire press section when it is thrown into the surrounding space, thus causing a long and expensive break in the produc-tion. In addition to material damages, stone roll breakages have also caused personal injuries.
For these reasons, it is of grea-t importance ~hat a damage in the stone roll is detected before the roll breaks up totally. By means of methods presently in use it is possible to monitor the shape of the ~ 3 ~ t~ 7 ~ I
stone roll and vibrations caused by the stone roll in the other rolls and the frame structures of the press section. In paper industries, however, there is no prior method by means of which cracks in the roll sur-face could be localized during the run.
The object of the invention is to provide a method by means o~ which the condition of the roll can be monitored during the operation of the paper machine. This is achieved by means of a method accord-ing to the invention, which is characterized in that shocks exerted on the doctor blade due to surface dam-ages in the stone roll are recorded by acceleration transducers positioned in the holder and that the sig-nal obtained from each acceleration transducer is summed in a synchronized manner with the rotation of the roll.
A major advantage o~ the invention is its flexibility as it is possible to accurately localize cracks in the roll surface during the run, whereby the hazardous roll breakages can be avoided. A further ad-vantage is that the method is simple so that the in-vention can be applied advantageously. The invention can also be applied to existing press sections since it is not necessary to make any substantial changes in the press section.
~ he invention will be described in the follow-ing in more detail by means of an embodiment shown in the attached drawing, wherein Figure 1 is a general side view of a press sec-tion in a modern paper machine;
Figure 2 illustrates an arrangement utilizing the invention in a view seen in the axial direction of the stone roll;
Figure 3 is a top view of the arrangement of Figure 2; and ~ 3 2 ~ 7 Figure ~ illustrates generally the output of one transducer.
Figure 1 shows generally the press section of a modern paper machine. The reference numeral 1 indi-cates a suction roll in the proper press; the refer-ence numeral 2 a variable crown roll; the reference numeral 3 a stone roll; and the reference numeral 4 another variable crown roll. The reference numeral 5 indicates a doctor blade means which trails along the surface of the stone roll, thus scraping impurities from the surface. In the case of Figure 1, a web 6 to be dried passes from the left to the righ-t.
The structure and operation of the press sec-tion belong ~o the prior art, so these matters are not discusses more closely herein.
Figures 2 and 3 show generally the doctor blade means indicated with the reference numeral 5 in Figure 1. The same reference numerals as in Figure 1 are used in Figures 2 and 3 for corresponding parts.
The doctor blade means 5 is formed by a holder 7 and a doctor blade 8 attached thereto. The holder 7 is mounted in bearing in the body of the press sec-tion so that it is pivotable around the longitudinal axis thereof. The holder 7 and the doctor blade 8 attached thereto extend over the whole length of the stone roll 3, as appears from Figure 3. The holder 7 with the doc~or blade 8 is pivoted so that the doctor blade 8 trails along the surface of the roll 3 during the rotation of the roll, thus scraping it clean.
In the method according to the invention, ac-celeration transducers 9 provided in the holder record shocks exerted on the doctor blade 8 due to surfaces damages in the stone roll 3. The shocks exerted on the doctor blade 8 also affect the holder 7, so the ac-celerat:ion transducers can be positioned in the ~32~'7~7 holder so that they are well protecked in view of the operation of the apparatus.
In order that surface damages in the roll, such as cracks, could be locali~ed in the direction of the length of the roll, a plurality of accelaration trans-ducers 9 are positioned with a mutual spacing over the whole length of the stonle roll 3. The positioning of the acceleration transducers in the direction of the length of the roll is shown generally in Figure 3, in which the acceleration transducers 9 are indicated by means of arrows.
According to the invention the signal obtained from the acceleration transducers 9 is further summed in a synchroni~ed manner with the rotation of the roll 3. In this way incidental disturbances will not inter-fere with the measuring process. As a result of this summing, the output obtained from each transducer 9 is such as shown in Figure 4. It appears from the output of Figure 4 that the sliding of the doctor blade is clearly disturbed at points A and B. The circle shown in Figure 4 represents the roll 3, so the disturbance, that is, the location of the damaged point on the pe-ripheral surface of the stone roll, can be determined.
The reference numeral 10 indicates the synchronization point used in the summing of the signal. The wa~eli~e line 11 in Figure 4 illustrates shocks exerted on the doctor blade 8 by the surface of the stone roll at each particular transducer 9. As stated above, the roll surface is clearly damaged at the points A and B, while the rest of the roll surface is intact.
The above embodiment is by no means intended to restrict the invention, but the invention can be mod-ified within the scope of the claims as desired. Ac-cordingly, it i.s obvious that the number of the ac-celerat:ion transducers, for instance, is by no means 2~7~7 restricted but can be chosen according to the require-ments in each particular case.
At present, stone rolls are used e.g. in the press sections o paper machines. In a modern paper machine the proper press of the press section can be formed e.g. by four rolls which are so positioned with respect to each other that they form three press nips.
One of these four rolls is made of stone, gen-erally granite. The granite shell of ~he stone roll is made in one piece by quarrying, machining and finally grinding. A stone roll so obtained is an expensive component, which is used for its good properties. Good practical properties include the micro structure and the anti-static quality of the surface.
However, cracks may be formed in stone rolls in use which damage the roll when expanding. At worst such cracks may result in total breakage of the roll during the run. Such a roll explosion has extramely serious consequences. In practice, the stone mass of the roll, e.g. about 70 tons, breaks the entire press section when it is thrown into the surrounding space, thus causing a long and expensive break in the produc-tion. In addition to material damages, stone roll breakages have also caused personal injuries.
For these reasons, it is of grea-t importance ~hat a damage in the stone roll is detected before the roll breaks up totally. By means of methods presently in use it is possible to monitor the shape of the ~ 3 ~ t~ 7 ~ I
stone roll and vibrations caused by the stone roll in the other rolls and the frame structures of the press section. In paper industries, however, there is no prior method by means of which cracks in the roll sur-face could be localized during the run.
The object of the invention is to provide a method by means o~ which the condition of the roll can be monitored during the operation of the paper machine. This is achieved by means of a method accord-ing to the invention, which is characterized in that shocks exerted on the doctor blade due to surface dam-ages in the stone roll are recorded by acceleration transducers positioned in the holder and that the sig-nal obtained from each acceleration transducer is summed in a synchronized manner with the rotation of the roll.
A major advantage o~ the invention is its flexibility as it is possible to accurately localize cracks in the roll surface during the run, whereby the hazardous roll breakages can be avoided. A further ad-vantage is that the method is simple so that the in-vention can be applied advantageously. The invention can also be applied to existing press sections since it is not necessary to make any substantial changes in the press section.
~ he invention will be described in the follow-ing in more detail by means of an embodiment shown in the attached drawing, wherein Figure 1 is a general side view of a press sec-tion in a modern paper machine;
Figure 2 illustrates an arrangement utilizing the invention in a view seen in the axial direction of the stone roll;
Figure 3 is a top view of the arrangement of Figure 2; and ~ 3 2 ~ 7 Figure ~ illustrates generally the output of one transducer.
Figure 1 shows generally the press section of a modern paper machine. The reference numeral 1 indi-cates a suction roll in the proper press; the refer-ence numeral 2 a variable crown roll; the reference numeral 3 a stone roll; and the reference numeral 4 another variable crown roll. The reference numeral 5 indicates a doctor blade means which trails along the surface of the stone roll, thus scraping impurities from the surface. In the case of Figure 1, a web 6 to be dried passes from the left to the righ-t.
The structure and operation of the press sec-tion belong ~o the prior art, so these matters are not discusses more closely herein.
Figures 2 and 3 show generally the doctor blade means indicated with the reference numeral 5 in Figure 1. The same reference numerals as in Figure 1 are used in Figures 2 and 3 for corresponding parts.
The doctor blade means 5 is formed by a holder 7 and a doctor blade 8 attached thereto. The holder 7 is mounted in bearing in the body of the press sec-tion so that it is pivotable around the longitudinal axis thereof. The holder 7 and the doctor blade 8 attached thereto extend over the whole length of the stone roll 3, as appears from Figure 3. The holder 7 with the doc~or blade 8 is pivoted so that the doctor blade 8 trails along the surface of the roll 3 during the rotation of the roll, thus scraping it clean.
In the method according to the invention, ac-celeration transducers 9 provided in the holder record shocks exerted on the doctor blade 8 due to surfaces damages in the stone roll 3. The shocks exerted on the doctor blade 8 also affect the holder 7, so the ac-celerat:ion transducers can be positioned in the ~32~'7~7 holder so that they are well protecked in view of the operation of the apparatus.
In order that surface damages in the roll, such as cracks, could be locali~ed in the direction of the length of the roll, a plurality of accelaration trans-ducers 9 are positioned with a mutual spacing over the whole length of the stonle roll 3. The positioning of the acceleration transducers in the direction of the length of the roll is shown generally in Figure 3, in which the acceleration transducers 9 are indicated by means of arrows.
According to the invention the signal obtained from the acceleration transducers 9 is further summed in a synchroni~ed manner with the rotation of the roll 3. In this way incidental disturbances will not inter-fere with the measuring process. As a result of this summing, the output obtained from each transducer 9 is such as shown in Figure 4. It appears from the output of Figure 4 that the sliding of the doctor blade is clearly disturbed at points A and B. The circle shown in Figure 4 represents the roll 3, so the disturbance, that is, the location of the damaged point on the pe-ripheral surface of the stone roll, can be determined.
The reference numeral 10 indicates the synchronization point used in the summing of the signal. The wa~eli~e line 11 in Figure 4 illustrates shocks exerted on the doctor blade 8 by the surface of the stone roll at each particular transducer 9. As stated above, the roll surface is clearly damaged at the points A and B, while the rest of the roll surface is intact.
The above embodiment is by no means intended to restrict the invention, but the invention can be mod-ified within the scope of the claims as desired. Ac-cordingly, it i.s obvious that the number of the ac-celerat:ion transducers, for instance, is by no means 2~7~7 restricted but can be chosen according to the require-ments in each particular case.
Claims (2)
1. A method of detecting surface damages in a stone roll of a press section in a paper machine or the like, said stone roll being provided with a doctor blade arranged in a pivotable holder so as to extend over the whole length of the roll for scraping the surface of the roll, said method comprising recording shocks exerted on the doctor blade due to surface dam-ages in the stone roll by acceleration transducers positioned in the holder, and summing the signal ob-tained from each acceleration transducer in a syn-chronized manner with the rotation of the roll.
2. A method according to claim 1, wherein the acceleration transducers are positioned in the holder with a mutual spacing over the whole length of the stone roll.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FI872793A FI77490B (en) | 1987-06-23 | 1987-06-23 | FOERFARANDE FOER IDENTIFIERING AV YTSKADOR PAO EN STENVALS I ETT PRESSPARTI VID EN PAPPERSMASKIN ELLER LIKNANDE. |
| FI872793 | 1987-06-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1320757C true CA1320757C (en) | 1993-07-27 |
Family
ID=8524717
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000570105A Expired - Lifetime CA1320757C (en) | 1987-06-23 | 1988-06-22 | Method of detecting surface damages in the stone roll of the press section of a paper machine or the like |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1320757C (en) |
| DE (1) | DE3821095A1 (en) |
| FI (1) | FI77490B (en) |
| SE (1) | SE8802279L (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5048353A (en) * | 1990-03-01 | 1991-09-17 | Beloit Corporation | Method and apparatus for roll profile measurement |
| US6645349B1 (en) | 1998-01-20 | 2003-11-11 | Valmet Corporation | Method and device for conditioning of a roll, in particular of a roll in a paper machine or in a paper finishing device |
| DE102011051929B3 (en) * | 2011-07-19 | 2012-10-18 | Gerhard Hertel | Device for a scraper and scraper arrangement with such a device |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1164708B (en) * | 1961-11-16 | 1964-03-05 | Hans Biel Fa | Device for detecting surface defects on moving material webs, in particular paper webs |
| US3793627A (en) * | 1972-06-28 | 1974-02-19 | Gen Electric | Automatic sonic detection of chipped cutting tools |
| DE2937673A1 (en) * | 1979-09-14 | 1981-04-02 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | Shaft or vehicle wheel eccentricity monitoring system - has sensor and counter determining angular position and distance sensor for eccentricity |
| US4429578A (en) * | 1982-03-22 | 1984-02-07 | General Electric Company | Acoustical defect detection system |
| US4471444A (en) * | 1982-04-02 | 1984-09-11 | The United States Of America As Represented By The Secretary Of Commerce | Rotating tool wear monitoring apparatus |
-
1987
- 1987-06-23 FI FI872793A patent/FI77490B/en not_active Application Discontinuation
-
1988
- 1988-06-17 SE SE8802279A patent/SE8802279L/en not_active Application Discontinuation
- 1988-06-22 CA CA000570105A patent/CA1320757C/en not_active Expired - Lifetime
- 1988-06-22 DE DE19883821095 patent/DE3821095A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| SE8802279L (en) | 1988-12-24 |
| FI77490B (en) | 1988-11-30 |
| FI872793A0 (en) | 1987-06-23 |
| SE8802279D0 (en) | 1988-06-17 |
| DE3821095A1 (en) | 1989-01-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed | ||
| MKEC | Expiry (correction) |
Effective date: 20121205 |