GB2032399A – Apparatus for and a Method of Directing a Flexible Web
– Google Patents
GB2032399A – Apparatus for and a Method of Directing a Flexible Web
– Google Patents
Apparatus for and a Method of Directing a Flexible Web
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Publication number
GB2032399A
GB2032399A
GB7934442A
GB7934442A
GB2032399A
GB 2032399 A
GB2032399 A
GB 2032399A
GB 7934442 A
GB7934442 A
GB 7934442A
GB 7934442 A
GB7934442 A
GB 7934442A
GB 2032399 A
GB2032399 A
GB 2032399A
Authority
GB
United Kingdom
Prior art keywords
web
wall element
gaseous flow
coanda
coanda nozzle
Prior art date
1979-10-04
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.)
Granted
Application number
GB7934442A
Other versions
GB2032399B
(en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
James River Corp of Nevada
Original Assignee
Crown Zellerbach Corp
Priority date (The priority date 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 date listed.)
1979-10-04
Filing date
1979-10-04
Publication date
1980-05-08
1979-10-04
Application filed by Crown Zellerbach Corp
filed
Critical
Crown Zellerbach Corp
1979-10-04
Priority to GB7934442A
priority
Critical
patent/GB2032399B/en
1980-05-08
Publication of GB2032399A
publication
Critical
patent/GB2032399A/en
1982-11-10
Application granted
granted
Critical
1982-11-10
Publication of GB2032399B
publication
Critical
patent/GB2032399B/en
Status
Expired
legal-status
Critical
Current
Links
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Classifications
D—TEXTILES; PAPER
D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
D21G—CALENDERS; ACCESSORIES FOR PAPER-MAKING MACHINES
D21G9/00—Other accessories for paper-making machines
D21G9/0063—Devices for threading a web tail through a paper-making machine
B—PERFORMING OPERATIONS; TRANSPORTING
B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
B65H23/00—Registering, tensioning, smoothing or guiding webs
B65H23/04—Registering, tensioning, smoothing or guiding webs longitudinally
B65H23/24—Registering, tensioning, smoothing or guiding webs longitudinally by fluid action, e.g. to retard the running web
Abstract
Apparatus for and a method of directing the leading end of a web (40) of flexible material to a predetermined location includes a wall element (12) having side edges (14, 16) and a web entry end and web exit end and a Coanda nozzle (28) located at the wall element web entry end to direct a gaseous flow therealong toward the web exit end. Venting means in the form of opposed foil elements (32, 34) extend from the Coanda nozzle toward the wall element side edges for laterally venting portions of the gaseous flow past the side edges to exert lateral forces on the web and spread it as the web is propelled along the wall element.
Description
SPECIFICATION
Apparatus for and a Method of Directing a
Flexible Web
This invention relates to a method of an apparatus for directing a web of flexible material to a required location.
United States Patent Specifications Nos.
3,999,696 and 4,014,487 disclose systems for directing the end or tail of a moving web to a predetermined location such as into threading engagement with rolls forming a nip or the like. In the aforesaid systems, a gas such as air is directed through a restricted opening under pressure whereupon it attaches itself to a flow attachment surface due to the «Coanda effect», is directed to the predetermined location, and entrains ambient air. The web is placed into the path of the moving gas and air entrained thereby.
The gas is moving at a velocity greater than the velocity of the moving web and thus the web is straightened out and directed to the predetermined location.
The arrangements illustrated in the aforesaid patents are entirely adequate to handle the vast majority of threading situations. One exception has been with certain paper machine configurations used to produced tissue grades at high dry end speeds, e.g. in the order of 1 130metres per minute. Specific problems that have arisen in such an operating environment have included excessive vertical web oscillations at the web exit end of the threader system and excessive flooding at nip entry points by the entraining gases used to propel the web. As a consequence, tail transfer problems have been encountered on occasion when attempting to thread high speed tissue, particularly where the threader system must be installed in close proximity to rolls or other nip defining means where the web is to be projected.
It is therefore an object of the present invention to provide apparatus of a relatively inexpensive and simple construction which is adapted to provide stabilizing forces to a web being threaded and to vent a portion of the gaseous flow being used to propel the web prior to web exit from the system so that threading will not be interfered with by excessive air flow interference.
According to the present invention there is provided apparatus for directing a web of flexible material to a predetermined location comprising: a wall element having side edges and a web entry end and a web exit end; a Coanda nozzle located at the wall element web entry end and adapted to direct a gaseous flow therealong toward said web exit end; and venting means in operative association with the wall element and extending from the Coanda nozzle to a location between the web entry and web exit ends of the wall element for laterally venting portions of the gaseous flow past opposed side edges of the wall element whereby a web will have lateral forces exerted thereupon by said gaseous flow portions to spread and stabilize the web as the web is propelled forward by the remainder of the gaseous flow in use of the apparatus.The venting means may conveniently be in the form of foil elements disposed in opposition to one another along the sides of the wall element. The foil elements each have fluid flow attachment surfaces leading from the Coanda nozzle to opposed side edges of the wall element.
According to another aspect of the invention there is provided a method of directing a web of flexible material to a predetermined location comprising: flowing a pressurized gas through an elongated fluid flow exit defined by a Coanda nozzle so that a gaseous flow is induced thereby along a predetermined path defined by a wall element adjacent to said nozzle; propelling the web along the wall element by entraining the web with the gaseous flow; venting portions of the gaseous flow in opposed lateral directions during the step of propelling the web; and spreading and stabilizing the web during propulsion thereof by entraining the edges of the web with said portions of the gaseous flow.
Preferred embodiments of the present invention are illustrated in the accompanying drawings in which:
Fig. 1 is a schematic plan view illustrating one embodiment of web directing apparatus of the present invention and including a schematic presentation of the velocity profile associated therewith;
Fig. 2 is a cross-sectional view taken along line 2-2 of Fig. 1;
Fig. 3 is a schematic plan view of another form of apparatus constructed in accordance with the present invention; and
Fig. 4 is a cross-sectional view taken along line 4-4 in Fig. 3.
Referring now to Figs. 1 and 2, the web directing apparatus illustrated includes a flat wall element 12 having side edges 14 and 16, a web entry end 18 and a web exit end 20. A Coanda nozzle is located at the web entry end and comprises a Coanda foil 22 and a bracket member 24 attached thereto which carries an upstanding leg 26 which cooperates with the
Coanda foil 22 to define an elongated slit 28 extending the full length of the Coanda nozzle.
The Coanda nozzle is of a two-dimensional type such as that illustrated in the specification of
United States Patents Nos. 3,999,696 and 4,014,487 and the operation thereof will not be described in detail other than to the state that a gas such as air is forced under pressure upwardly through slit 28. Due to the Coanda effect the pressurized gas attaches itself to the curved outer surface of Coanda foil 22 and flows therealong toward the right as viewed in Figs. 1 and 2. The pressurized entraining gas and ambient air entrained thereby will then flow along the upper surface of wall element 12.
Venting means in the form of foil elements 32 and 34 are disposed in opposition to one another along the sides of wall element 12. The foil elements 32 and 34 extend from slit 28 to a location between the web entry and web exit ends of the wall element. Due to the Coanda effect portions of the gaseous flow passing over
Coanda foil 22 will attach to foil elements 32 and 34 and flow along the fluid flow attachement surfaces thereof to opposed side edges of the wall element. The slit 28 extends between the side edges of the wall element and is disposed immediately adjacent to the foil elements 32 and 34 to facilitate attachment of the portions of the gaseous flow thereto.
The operation of the apparatus according to
Figs. 1 and 2 will now be described. When it is desired to use the apparatus to direct a web of flexible material such as tissue to a predetermined location, pressurized gas is forced through slit 28 so that it attaches to the Coanda foil 22.
Assuming for the moment that the apparatus of
Figs. 1 and 2 does not utilize venting means in the form of foil elements 32 and 34, light weight material such as tissue when introduced into the gaseous flow established by the Coanda nozzle will have a tendency to bunch up and migrate toward the centre of the wall element 1 2 as illustrated in dashed lines in Fig. 1. A second undesirable result is that such light weight material when exiting from the web exit end of the wall element will have a tendency to flutter or oscillate vertically as shown in phantom in Fig. 2, due not only to its bunched up condition but also due to a possibly excessive amount of entraining gases exiting therewith.Use of the venting means minimizes this undesirable web movement and in addition greatly reduces the possibility of excessive gaseous flow flooding a nip or otherwise interfering with the proper operation of the threading system. In the arrangement of Figs.
1 and 2 a portion of the gaseous flow passing over wall element 12 will attach to each of the foil elements 32 and 34 due to the Coanda effect and be laterally vented from the device by passing beyond the side edges of the wall element due to the fact that no side walls are attached to the wall element. This flow pattern will cause lateral forces to be exerted upon the web to spread and stabilize it as it is propelled forward by the remainder of the gaseous flow. The condition of such a spread web 40 is shown in solid lines in
Fig. 1. Due to these stabilizing forces and the venting of excess gaseous flow, the web 40 will tend to remain in a rather straight path as it exits from the wall element as shown in solid lines in
Fig. 2.
The spreading action just described can be further accentuated by increasing the percentage of gaseous flow that is vented away from the system by foil elements 32 and 34. One simple approach for accomplishing this end is by widening the slit 28 as it extends from the centre of the wall element 12 to the side edges thereof.
For example, a good spreading of tissue paper grade was obtained by utilizing a 0.05 mm slit opening at the centre and 0.13 mm at the edges.
Adjustment screws 41 extending between the upwardly extending legs of the bracket member may be employed to adjust the slit width. The velocity profile resulting from such a non-uniform slit is illustrated in Fig. 1 and designated by reference letter A. This should be compared with the velocity profile resulting from a uniform width slit and designated by reference letter B.
An alternative form of the invention is shown in
Figs. 3 and 4. The embodiment includes a wall element 1 2A and a Coanda foil at the web entry end thereof comprised of a Coanda foil 22A and a bracket member 24A forming a slit 28A therewith. Foil elements 32A and 34A are disposed in opposition to one another along the side edges of the wall element 1 2A leading from the slit 28A to the side edges of the wall element as previously described with reference to the embodiment in Figs. 1 and 2. Disposed immediately adjacent to the web exit end of wall element 1 2A is a second Coanda nozzle comprised of Coanda foil 22B and a bracket member 248 defining a slit 28B therewith.A pair of foil elements 32B and 34B are disposed in opposition with respect to one another immediately adjacent to and downstream from slit 288. The foil elements 32B and 348 extend along the edges of a wall element 1 2B which leads form Coanda foil 22B. It should be noted that wall element 1 2B is «stepped» downwardly from wall element 1 2A so that it lies in a different plane. All of the previously described elements are retained in fixed position relative to one another by being attached to a pair of side walls, one of which, side wall 42, is shown in Fig. 4.
The embodiment of Figs. 3 and 4 includes a flat guide platform 44 upstream from the nozzle comprised of bracket member 24A and Coanda foil 22A. The guide platform 44 extends between side wall 42 and its companion side wail so that it extends the full width of the apparatus. The guide platform 44 improves lateral and horizontal web stability. The stabilizing effect is illustrated schematicaily in Fig. 4. The guide platform directs the entrained flow beneath and parallel to the path of web 40. The fast moving flow creates low pressure between the platform and the web, hence a normal stabilizing force is produced as shown by the arrow. Experiments have shown that a guide platform length from 1.25 to 5 cms is sufficlent to generate a pronounced stabilizing effect. It should be appreciated that a web guide platform may also be used in a single nozzle apparatus of the type illustrated in Figs. 1 and 2.
The embodiment of Figs. 3 and 4 operates as follows. The Coanda nozzles are pressurized so that entraining fluid passes upwardly through slits 28A and 288 to create a continuous flow along the wall elements associated therewith. When a web is placed in engagement with the flow induced along Coanda foil 22A it is projected along wall element 1 2A. Portions of the gaseous flow are vented from the apparatus by foil elements 32A and 34A in a manner previously described with reference to the first embodiment.
When the web reaches slit 28B it is again entrained by the air passing over Coanda foil 22B and along wall element 12B. Foil elements 32B and 34B exert a second opposed lateral force on the web to spread and further stabilize it. It has been found that the multiple Coanda nozzle and venting arrangement as illustrated in Figs. 3 and 4 result in a strong vertical tail stabilizing effect. The «stepped» pattern serves particularly well in long, steeply inclined draws.
Claims (12)
Claims
1. Apparatus for directing a web of flexible material to a predetermined location comprising: a wall element having side edges and a web entry end and a web exit end; a Coanda nozzle located at the wall element web entry end and adapted to direct a gaseous flow therealong toward said web exit end; and venting means in operative association with the wall element and extending from the Coanda nozzle to a location between the web entry and web exit ends of the wall element for laterally venting portions of the gaseous flow past opposed side edges of the wall element whereby a web will have lateral forces exerted thereupon by said gaseous flow portions to spread and stabilize the web as the web is propelled forward by the remainder of the gaseous flow in use of the apparatus.
2. Apparatus according to claim 1, wherein the venting means comprises foil elements disposed in opposition to one another along the sides of the wall element.
3. Apparatus according to Claim 2, wherein the foil elements each have fluid flow attachment surfaces leading from the Coanda nozzle to opposed side edges of the wall element.
4. Apparatus according to Claim 2 or 3, wherein the Coanda nozzle includes a Coanda foil and means cooperating with the Coanda foil to define a slit through which entraining gases exit to create gaseous flow along said wall element, said slit extending between the side edges of the wall element immediately adjacent to the foil elements.
5. Apparatus according to Claim 4, wherein the width of the slit is greater at the ends thereof than at the centre thereof.
6. Apparatus according to any preceding
Claim, additionally comprising a second Coanda nozzle disposed adjacent to the wall element exit end, a second wall element operatively associated with said second Coanda nozzle for receiving a gaseous flow induced by the second Coanda nozzle and second venting means in operative association with the second wall element for again exerting lateral forces on the web in use of the apparatus.
7. Apparatus according to any preceding
Claim, additionally comprising a web guide platform positioned adjacent to the Coanda nozzle on the side of the nozzle remote from the wall element.
8. A method of directing a web of flexible material to a predetermined location comprising: flowing a pressurized gas through an elongated fluid flow exit defined by a Coanda nozzle so that a gaseous flow is induced thereby along a predetermined path defined by a wall element adjacent to said nozzle; propelling the web along the wall element by entraining the web with the gaseous flow; venting portions of the gaseous flow in opposed lateral directions during the step of propelling the web; and spreading and stabilizing the web during propulsion thereof by entraining the edges of the web with said portions of the gaseous flow.
9. A method according to Claim 8, wherein said portions of gaseous flow are vented by attaching same to foil elements disposed along the sides of the wall element.
10. A method according to Claim 8 or 9, including the step of exerting a normal force on the web at a location upstream from the Coanda nozzle.
11. A method of directing a web of flexible material substantially as herein described with reference to the accompanying drawings.
12. Apparatus for directing a web of flexible material constructed and arranged to operate substantially as herein described with reference to and as illustrated in Figures 1 and 2 or Figures 3 and 4 of the accompanying drawings.
GB7934442A
1979-10-04
1979-10-04
Apparatus for and a method of directing a flexible web
Expired
GB2032399B
(en)
Priority Applications (1)
Application Number
Priority Date
Filing Date
Title
GB7934442A
GB2032399B
(en)
1979-10-04
1979-10-04
Apparatus for and a method of directing a flexible web
Applications Claiming Priority (1)
Application Number
Priority Date
Filing Date
Title
GB7934442A
GB2032399B
(en)
1979-10-04
1979-10-04
Apparatus for and a method of directing a flexible web
Publications (2)
Publication Number
Publication Date
GB2032399A
true
GB2032399A
(en)
1980-05-08
GB2032399B
GB2032399B
(en)
1982-11-10
Family
ID=10508285
Family Applications (1)
Application Number
Title
Priority Date
Filing Date
GB7934442A
Expired
GB2032399B
(en)
1979-10-04
1979-10-04
Apparatus for and a method of directing a flexible web
Country Status (1)
Country
Link
GB
(1)
GB2032399B
(en)
Cited By (3)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
GB2147572A
(en)
*
1983-10-07
1985-05-15
Fmc Corp
Stacking thermoplastic sheets or bags
EP0644141A1
(en)
*
1993-09-21
1995-03-22
Angel Balsells Ventura
Web guide for textile web unwinder
FR2715679A1
(en)
*
1994-02-02
1995-08-04
Devillers Jacques
Method of coating of honeycombed transparent or translucent panel with filtering film
1979
1979-10-04
GB
GB7934442A
patent/GB2032399B/en
not_active
Expired
Cited By (4)
* Cited by examiner, † Cited by third party
Publication number
Priority date
Publication date
Assignee
Title
GB2147572A
(en)
*
1983-10-07
1985-05-15
Fmc Corp
Stacking thermoplastic sheets or bags
EP0644141A1
(en)
*
1993-09-21
1995-03-22
Angel Balsells Ventura
Web guide for textile web unwinder
ES2083909A2
(en)
*
1993-09-21
1996-04-16
Ventura Angel Balsells
Web guide for textile web unwinder.
FR2715679A1
(en)
*
1994-02-02
1995-08-04
Devillers Jacques
Method of coating of honeycombed transparent or translucent panel with filtering film
Also Published As
Publication number
Publication date
GB2032399B
(en)
1982-11-10
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Legal Events
Date
Code
Title
Description
1988-05-25
PCNP
Patent ceased through non-payment of renewal fee
