US3351521A

US3351521A - Transfer mechanism for web

Info

Publication number: US3351521A
Application number: US463741A
Authority: US
Inventors: Maurice M Murray; Bill H Andrews
Original assignee: Publishers Paper Co
Current assignee: Publishers Paper Co
Priority date: 1965-06-14
Filing date: 1965-06-14
Publication date: 1967-11-07
Anticipated expiration: 1984-11-07

Description

N v. 7,1967 M. M. MURRAY Em 3,351,521

TRANSFER MECHANISM FOR WEB Filed June 14, 1965 Bi]! H. Andre ws Ma urice M.Mur-rc1 g JNVENTORS United States Patent 3,351,521 TRANSFER MECHANISM FOR WEB Maurice M. Murray and iliili H. Andrews, Oregon City, Greg, assignors to Publishers Paper (10., Oregon City, 0mg, a corporation of Delaware Filed June 14, 1965, Ser. No. 463,741 6 (Ilaims. (Cl. 162-367) This invention relates to paper-making machines, and more particularly to improvements in the manner in which a continuous web to be formed into paper is transferred from a traveling endless screen onto a traveling felt or other belt positioned to receive material traveling from the screen.

Describing a typical paper-making machine, it may comprise a head box for holding a supply of pulp and water, which is adapted to distribute this pulp and water onto an endless wire mesh or screen, thus to form a mat on the screen. Water is removed form this mat with the formation of a continuous paper web as the screen together with the mat thereon advances in the machine. The web is further processed to form completed paper, by further drying and usually compressing of the web. It is a requirement in the machine that the continuous web transfer from the screen to the felt, and conditions existing at the time such occurs introduces certain problems.

One manner of transferring a web from the screen to the felt comprises employing a so-called poor mans roll, which is mounted as close as conveniently possible to the screen, and which trains the felt in a region close to the screen so that the web can travel from the screen to the felt while extending in a freely suspended state over the smallest possible distance. Usually it is required that the felt he moved a little faster than the screen, so that the web on moving onto the felt be stretched tightly, i.e., so that a so-called tight draw exists. The system has some disadvantages, including the fact that there is some stretching of the paper due to the pressure of the tight draw. Papers having some strength usually are best handled in this manner, and there is limitation on the diameter of the roll that may be used for training the felt.

Again considering the usual paper-making machine, the screen may travel over a couch roll near the region where the web leaves the screen and transfers to the felt. In the couch roll suction apparatus within the roll functions to withdraw water from the web, which produces some imbedding of the fibers of the web within the interstices of the screen. This affects the ease with which the paper web may be separated from the screen. Separation is made easier if there is some rewetting of the paper web after the same leaves the Vicinity of the couch roll, but in the ordinary case such rewetting is not desirable as the principal purpose to be attained in the paper-making machine is drying of the web.

Generally, an object of this invention is to provide improved means for effecting transfer of a paper web from a screen to a felt or other belt which takes care of the above-indicated difiiculties in a practical and satisfactory manner.

More specifically, an object of this invention is to provide a paper-making machine, which includes means for loosening the paper web from a screen without the necessity of producing rewetting of the web, more specifically, means relying upon the introduction of a stream of air against the underside of the web which travels against the web by traveling through the screen, and means adjacent the felt for removing excess air promoting laying down of the web on the felt.

Thus, this invention features, and contemplates as an object thereof, the provision of an air shower positioned immediately after the couch roll and before the transfer region in the paper-making machine which, by blowing a stream of air continuously up into the fourdrinier screen and against the paper web carried thereon, is effective to loosen this web to facilitate its transfer from the screen to the felt. The web then is enabled to travel from the screen to the felt to a position where the same is directly adjacent tthe surface of the felt. Due to the introduction of the air from the shower which travels through the screen, there tends to be an excess of air, or a slightly pressurized air condition, in the region where the paper web comes to adjacent the felt. To remove this air, and to inhibit wrinkling of the web and folding over of the web edges (which edges tend naturally to stretch somewhat relative to the center of the web), air evacuator means is provided for drawing air laterally outwardly relative to the sides of the web on the top of the felt, whereby the web may settle down on the felt in a truly flat state. Removal of air is not through the felt itself, which is somewhat inefficient due to the physical structure of the felt, and which also might tend to maitnain wrinkles in the web, but instead from the sides of the web and from over that surface of the felt which ultimately is to receive the paper web. In summary, the air shower promotes loosening, and the air evacuator means remove air introduced to the machine in a special manner which promotes a fiattened condition in the web.

In a preferred embodiment of the invention, a roll is provided in the transfer region between the screen and the felt receiving the paper web, which trains the web in a U-shaped bend where the web extends from the screen to the felt. The roll inhibits billowing of the web as the re sult of air currents in said transfer region.

Other objects and advantages of the invention will become more fully apparent as the following description is read in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side elevation, somewhat simplified, of portions of .apaper-making machine, including a screen and a continuous felt receiving material traveling from the screen;

FIG. 2 is a cross-sectional View, taken. generally along the line 22 in FIG. 1, showing an air shower present in the construction, and illustrating diagrammatically means for supplying air under pressure to the air shower;

FIG. 3 is a cross-sectional view, taken generally along the line 3-3 in FIG. 1, showing evacuator means contemplated for removing air from lateral margins of the paper web immediately prior to the web laying down on the felt, and also illustrating diagrammatically means for supplying subatmospheric pressure or a vacuum to said evacuator means; and

FIG. 4 is a cross-sectional view, somewhat enlarged, taken along the line 4-4 in FIG. 2.

Referring now to the drawings, a screen or Wire mesh such as is used in the manufacture of paper, adapted to have deposited thereon a layer of pulp and water as a mat, is shown at 10. A paper web 11 is. carried by the screen forwardly in the paper-making machine, along a horizontal reach indicated at 10a, and a downwardly inclining reach indicated at 1%. Not shown in the drawings, but also a part of the paper-making machine, is the usual head box which carries a mass of water and pulp and which is used in distributing this water and pulp mixture on the screen, on a portion of reach 10a.

The screen is trained over a vacuum or suction couch roll shown at 14, and a turning roll shown at 16. The couch roll may be conventional, and thus may include an outer perforated cylindrical part 18 and within part 18 a vacuum chamber (not shown) which communicates with the perforations thus to apply a vacuum to the web carried thereacross by the screen, with the removal of water from the mat. Details of the couch have not been included, since this is a well-known item of equipment in paper-making machines, and specifics with respect to its construction forms no part of the invention. Suffice it to say that on the screen traveling over the couch roll and water being withdrawn from the web carried on the top face of the screen, fibers in the web tend to be drawn into the interstices of the screen which tends to inhibit separation of the web from the screen.

Web 11 travels from reach 1% of the screen onto a reach 20a of a felt 20. The felt has its upper reach 20a moving from left to right, or in the direction indicated by the arrow in FIG. 1, thus to carry the web toward the discharge end of the paper-making machine. The felt is trained over a lead-in felt roll 22 which is journaled in the usual manner on the frame of the machine.

It will be noted that the web extends in an expense 11a where it is out of contact with either the screen or the felt. In this region the web is transferring from the screen to the felt and thus this region is referred to herein as the transfer region for the web. In the apparatus shown, in this transfer region the web extends in a U-shaped bend, first downwardly, and thence around a blow roll shown at 24 which is journaled in the usual manner in the machine. The bottom of roll 24 engages the top face of the paper web in this transfer region.

Referring now also to FIGS. 2, 3 and 4, web 11 is loosened from the screen immediately before the transfer region by means of an air shower 30. The air shower directs a continuous stream of air, in the form of a curtain extending substantially continuously across the entire width of the screen, against the base of the screen. The air travels through the screen and against the bottom face of the web. The air pressure thus produced under the web tends to force the web upwardly thus to produce initial separation of the web from the screen, with pulling of web fibers out of the interstices of the screen.

In the embodiment illustrated, the air shower comprises a pipe 32 mounted in a suitable manner in a position extending transversely across the underside of the screen. Perforations in the pipe extending as a row therealong are shown at 34. Fastened as by welding to either side of the pipe and projecting upwardly therefrom are elongated plates or

deflectors

36, 38 which funnel air discharged from the perforations into a slot 37 defined by the upper margins of the deflectors. With the plates, the air flowing from the pipe is mixed so that instead of multiple air jets striking the screen producing isolated regions of loose material, a curtain of air flows against the underside of the screen to produce uniform loosening across the entire width of the screen.

It will be noted that

plates

36, 38 not only direct the air in a direction extending toward the underside of the web, but also in an upward direction opposing the downward travel of the web. Travel of the web and screen downwardly along reach 1% has the effect of drawing air back into the region where it is being discharged from the air shower, increasing the pressure of the air under the web produceable by the shower.

Illustrated diagrammatically in FIG. 2 is a compressor .50 supplying air under pressure through lines 51, 52 to the air shower.

Shown at 60 is evacuator means provided for evacuating air from under the paper web where the same overlies the felt, with such air flowing while being evacuated laterally outwardly of the margins of the web in streams paralleling the top face of the felt. As a consequence, air which has been introduced partly by reason of the air shower is eliminated. With such removal, billowing of the web is prevented and the same is caused to lie flat on the felt without wrinkles therein or turning over of edges.

Evacuator means 60 comprises a pair of vacuum hoses shown at 62 and 64, with

ends

62a, 64a extending inwardly from the margins of the felt and overlying the felt. Ends 62a and 64a of the hoses have openings in their extremities facing the center of the felt. The hoses are connected to a vacuum source such as the vacuum pump shown schematically at 66. With such an organization, and on operation of the vacuum pump, air is drawn into the open ends of the hoses from over the top face of the felt and under the web.

Air under the web where it extends in the transfer region tends to cause billowing and disarrangement of the web if the web is unrestrained, and for this reason blow roll 24 is included. The roll maintains the web with one reach thereof generally paralleling the reach of the screen extending from the couch to the turning roll, and another reach generally paralleling the reach of the felt where the same extends forwardly from the lead-in felt roll.

While there has been described an embodiment of the invention, variations are possible without departing therefrom. It is desired to cover all modifications and variations as would be apparent to one skilled in the art, and that come within the scope of the appended claims.

It is claimed and desired to secure by letters patent:

1. In a paper-making machine, comprising an endless screen for carrying wet pulp while the same has water removed therefrom in the formation of a continuous paper web, and an endless belt for carrying a paper web moving from the screen, said belt and screen traveling in courses that come to close adjacency in a transfer region where the web transfers from the screen to the belt,

means for introducing against the underside of said screen, immediately before said transfer region, across substantially the entire width of the screen, a stream of air directed at the underside of the paper web carried by the screen, whereby the web may be loosened from the screen, and

means adjacent said belt for producing lateral outward flow of air, between the web and said belt, relative to the margins of the paper web, in a region directly following the transfer region, whereby air is removed from under the web from across the top of the belt permitting the web to lay down on the belt.

2. In a paper-making machine comprising an endless screen for carrying wet pulp while the same has water removed therefrom in the formation of a continuous paper web, and an endless belt for carrying a paper web moving from the screen, said belt and screen traveling in courses that come to close adjacency in a transfer region where the web travels from the screen to the belt.

means for introducing against the underside of said screen, immediately before said transfer region, across substantially the entire width of the screen, a stream of air directed at the underside of the paper web carried by the screen whereby the web may be loosened from the screen,

means adjacent said belt for producing lateral outward flow of air, between the web and said belt, and relative to the margins of the paper web, in a region directly following the transfer region, whereby air is removed from under the web from across the top of the belt permitting the web to lay down on the belt, and

roll means in said transfer region supporting the web where the same extends out of contact with either the screen or belt by engaging the side of the web opposite the side which faces said screen.

3. In a paper-making machine, comprising an endless screen for carrying wet pulp while the same has water removed therefrom in the formation of a continuous paper web, and an endless belt for carrying a paper web moving from the screen, said belt and screen traveling in courses that come to close adjacency in a transfer region where the web transfers from the screen to the belt,

means for introducing against the underside of said screen, immediately before said transfer region, across substantially the entire width of the screen, a stream of air directed at the underside of the paper web carried by the screen whereby the web may be adjacent each margin, with ends extending in a generally transverse direction with respect to the belt, each having an opening in its said end facing the center of the belt.

6. In a paper-making machine,

loosened from the screen, and 5 a couch and a turning roll lower than the couch, and means adjacent said belt for producing lateral outward an endless screen traveling from the couch and flow of air, between the web and said belt, relative thence around the turning roll, to the margins of the paper web, in a region directly a lead-in felt roll disposed to one side of the screen following the transfer region, whereby air is rewhere it extends between the couch and turning roll, moved from under the web from across the top of 10 and an endless felt trained over the lead-in felt roll the belt permitting the web to lay down on the belt, including a work-supporting reach extending from said means for producing lateral outward flow of air the top of the lead-in feet roll away from the screen, comprising a pair of vacuum conduits overlying said screen and felt providing support for a paper web margins of said belt, one adjacent each margin, with with said web traveling from the screen and thence ends extending in a generally transverse direction 1 to the felt, with respect to the belt, each having an opening in an air shower between said couch and turning roll for its said end facing toward the center of the belt. directing a stream of air against the underside of 4. In a paper-making machine comprising an endless the screen where the same extends in a reach bescreen for carrying wet pulp while the same has water tween the couch and turning roll, said air shower removed therefrom in the formation of a continuous 2 also having a construction whereby said air stream paper web, and an endless belt for carrying a paper Web is directed upwardly in a direction opposing the moving from the screen, said belt and screen traveling in downward movement of said screen in traveling courses that come to close adjacency in a transfer region from the couch to the turning roll, where the web transfers from the screen to the belt, a pair of substantially aligned vacuum conduits overmeans for introducing against the underside of said lying margins of the felt where it extends in said screen immediately before said transfer region, from work-supporting reach, one adjacent each margin, across substantially the entire width of the screen, said conduits extending in a generally transverse dia stream of air directed at the paper web carried rection with respect to the felt and each having an by the screen whereby the web may be loosened opening facing the center of the felt, and from the screen, a roll for engaging a paper web where it extends from said means comprising elongated deflectors extending said screen to said felt, said roll defining a bend in transversely of said screen, With margins defining said web between said air shower and said vacuum an elongated slot disposed adjacent the screen, pomeans with the web passing beneath the roll. sitioned so as to direct a stream emanating from the reflectors which travels in a direction partially op- References Cited posing the direction of travel of the web as the same UNITED STATES PATENTS is carried by the screen toward the deflectors, and means for producing lateral outward flow of air, be- 2, 067,350 1/1937 Schwartz l62-307 tween the web and said belt, relative to the margins of the paper web, in a region directly following the FOREIGN PATENTS transfer region, whereby an 1s removed from under 573,611 4/1959 Canada.

the web from across the top of the belt permitting the web to lay down on the belt. 5. The apparatus of claim 4, wherein the means for producing lateral outward flow of air comprises a pair of vacuum conduits overlying margins of said belt, one

DONALD H. SYLVESTER, Primary Examiner. 4 A. C. HODGSON, Assistant Examiner.

Claims

1. IN A PAPER-MAKING MACHINE, COMPRISING AN ENDLESS SCREEN FOR CARRYING WET PULP WHILE THE SAME HAS WATER REMOVED THEREFROM IN THE FORMATION OF A CONTINUOUS PAPER WEB, AND AN ENDLESS BELT FOR CARRYING A PAPER WEB MOVING FROM THE SCREEN, SAID BELT AND SCREEN TRAVELING IN COURSES THAT COME TO CLOSE ADJACENCE IN A TRANSFER REGION WHERE THE WEB TRANSFERS FROM THE SCREEN TO THE BELT, MEANS FOR INTRODUCING AGAINST THE UNDERSIDE OF SAID SCREEN, IMMEDIATELY BEFORE SAID TRANFER REGION, ACROSS SUBSTANTIALLY THE ENTIRE WIDTH OF THE SCREEN, A STREAM OF AIR DIRECTED AT THE UNDERSIDE OF THE PAPER WEB CARRIED BY THE SCREEN, WHEREBY THE WEB MAY BE LOOSENED FROM THE SCREEN, AND MEANS ADJACENT SAID BELT FOR PRODUCING LATERAL OUTWARD FLOW OF AIR, BETWEEN THE WEB AND SAID BELT, RELATIVE TO THE MARGINS OF THE PAPER WEB, IN A REGION DIRECTLY FOLLOWING THE TRANSFER REGION, WHEREBY AIR IS REMOVED FROM UNDER THE WEB FROM ACROSS THE TOP OF THE BELT PERMITTING THE WEB TO LAY DOWN ON THE BELT.