US3441476A - Paper web transfer device utilizing suction box - Google Patents

Description

C. SCHIEL April 29, 1969 PAPER WEB TRANSFER DEVICE UTILIZING SUCTION BOX Filed Jan. 21, 1966 INVENTOR. QHRISTIAN SCHIEL United States Patent Int. 01. D21f 1/52 US. Cl. 162306 Claims ABSTRACT OF THE DISCLOSURE An arrangement for transferring a wet web from the wire of a papermaking machine to a porous belt-like conveyor member in which a stationary suction box is mounted adjacent and parallel to the wire of the papermaking machine and has a convex perforated region on the side nearest the wire and which region engages the back of the conveyor member and supplies suction therethrough to pick up the web from the Wire and to transfer it to the conveyor member. The conveyor member may have a wear resilient surface on the suction box side and this surface can be in the form of a belt-like member separate from the web engaging side of the conveyor member which can also be a belt-like member.

The present invention relates to paper making machines, particularly of the Fourdrinier type, and is most particularly concerned with transferring of the wet Web from the wire of the paper making machine to a pick up and conveyor member, such as a felt, which carries the web to a drying section.

In particular, the present invention relates to an improved arrangement for effecting the transfer of the wet web from the wire of the paper machine to the conveyor member, or felt, in such a manner that there is little loss of fiber from the paper web and the paper web is transferred from the wire to the felt in the best possible condition.

The transferring of a wet web from the wire of a paper making machine, such as a Fourdrinier machine, to a felt on which the web is conveyed to the drying section of the machine is, of course, known.

One matter of accomplishing the web transfer is to employ a pick-up roll for picking up the paper web from the wire in which the pick-up roll operates under suction. It has been found, however, that the perforated cylindrical surface of such a pick-up roll will impart spots, somewhat like watermarks, to the web of paper where the web is aligned with the suction holes in the roll. The direct suction action on the paper also introduces the possibility of damaging the surface of the paper and also creates the possibility that the paper will tear when picked up from the wire of the machine. Such perforated suction rolls are also quite expensive and the driving of the roll at the proper speed is diflicult and is well known that such rolls are quite noisy in operation. Considerable power is also required for maintaining the proper degree of suction inside vacuum pick-up rolls of this nature.

Another type of pick-up which is known utilizes two guide rolls which guide the felt and which enclose between each other a suction box while the rolls press the felt, which is subjected to the vacuum of the suction box, against the paper web to be picked up along a short arc in the region of the end of the suction zone of the couch roll, or shortly beyond the said region. The two rolls are adjustable with respect to each other and are tilted inwardly and outwardly together along with the suction box.

3,441,476 Patented Apr. 29, 1969 This construction involves several disadvantages including the fact that two rotating rolls are required each of which must have at least two bearings while roll driving means must be provided. Since such rolls are relatively large and involve large masses, vibration or oscillating of the rolls can occur which will materially effect the picking up of the paper web from the wire of the paper making machine. The picking up of the web is a rather delicate operation and any disturbance thereof is apt to lead to tearing, or otherwise damaging, of the web.

The adjustment of the rolls to the correct position to seal the vacuum space therebetween is also difficult and, furthermore, the adjusting means required for this purpose are expensive.

Another arrangement for picking up a web from the wire of a Fourdrinier machine is illustrated in Patent No. 3,207,65 8. In this patent, a member having a tip of small curvature, less than three inches radius of curvature, bears with the said tip on the back of the pick-up felt at the pick-up point and presses the pick-up felt against the wire of the paper making machine. The felt and wire approach each other on one side of the member, meet at the tip of the member, and diverge from each other on the other side of the member. The member bearing on the felt may be stationary or it may include a small roller forming the said tip and driven in rotation so as to roll on the back of the felt.

In the structure of this patent, a problem exists in effecting the substantially complete transfer of the web from the wire to the felt without any difiiculties merely by pressing the felt against the wire carrying the paper web. The member which bears on the felt, according to the United States patent, has a relatively small radius of curvature in order to develop the pressure necessary between the felt and the wire to effect pick-up of the web and, accordingly, a good possibility exists that the member will wear rapidly when it is stationary mounted and, also, considerable pressure is exerted on the felt, due to the small radius of curvature and this will also induce strain and wear in the felt. The tension of the wire of the paper making machine must be controlled closely to maintain the proper pressure at the pick up region without, however, overstressing the wire.

When the device of the said patent includes a roller rolling on the felt, the roller is so small in diameter as to require additional support because of the great relative width of the machine and this involves added expensive structure in the form of a machined back-up member to prevent the small roller from deflecting during operation.

Having the foregoing in mind, the present invention proposes the provision of an arrangement for effecting the transfer of a moist paper web from the wire of paper making machine, such as a Fourdrinier machine, to a conveyor member such as a felt in which the disadvantages referred to above in connection with known transfer arrangements is eliminated.

A particular object of the present invention is the effecting of the transfer of the web from the wire to the felt by the use of a stationary suction box acting through the conveyor member.

Another object is the provision of an arrangment for transferring a wet paper web from the wire of a paper making machine to a conveyor felt in which the structure employed is quite simple, avoiding rotating parts and bearings therefor and drive means therefor so that the installation is relatively inexpensive.

Another object of this invention is the provision of a pick-up arrangement of the nature referred to which is located along the wire of the paper making machine at a spot between the couch roll and the driving roller so that the wire is engaged by the conveyor member or felt along an unsupported region of the wire so that the suction exerted in the pick-up device is fully effective for picking up the web from the wire.

Still another object is the provision of a suction type pick-up for transferring a wet paper web from a paper making machine wire to a conveyor member, or felt, in which the paper web and the wire of the paper making machine, as well as the conveyor member or felt, are prevented from being subjected to high pressure so that damage thereto does not result and so that where foreign matter such as lumps of pulp or dirt might accidently become entrained in the paper web, there is no damage to the parts of the structure because the wire can easily yield to pass such foreign matter.

The above mentioned objects and advantages of the present invention as Well as still other objects and advantages thereof will become more apparent upon reference to the following specification taken in connection wtih the accompanying drawing in which:

FIGURE 1 is a somewhat schematic sectional view showing the fundamental set up of the present invention, utilizing a suction box over which the web pick-up conveyor member slides;

FIGURE 2 is a view similar to FIGURE 1 but shows a cylindrical suction box; and

FIGURE 3 is a somewhat diagrammatic view showing the complete pick-up portion of a paper making machine with a suction box according to the present invention and also showing the use of a supporting member with the pick-up felt.

In the practice of the present invention, a non-rotatable suction box is employed over which the member which is to pick-up the wet paper web slides. The suction box holds the pick-up member in close proximity with the paper machine wire along an unsupported section of the wire between the couch roll and the driver roll of the paper making machine, which last mentioned roll is located where the wire of the machine turns to return toward the head box end of the machine.

According to the present invention, the pick-up member may comprise a conventional endless felt or it may also consist of a compound member in which the side or layer thereof which slides on the suction shoe is particularly constructed to resist wear and abrasion and to slide freely on the suction shoe While the other side or layer thereof which engages the paper web is particularly constructed for that specific function.

For example, the side of the pick-up member which slides on the suction shoe may be constructed of polyamide or polyester fibers which will slide easily on the suction shoe and resist wear even when woven to form a porous member through which the suction of the shoe can act. The shoe itself, of course, is manufactured of a material which will resist wear, such as an alloyed steel or the like, and which material can also take a flnish so as to present a smooth surface to the member sliding thereover.

The present invention further permits the separation of the pick-up and conveying member into two parts which include a lower or inner supporting member which slides directly on the suction shoe, and an upper or outer member which is the actual pickup member itself. With either a compound member, or a two part member, a separation of functions is thus introduced which makes it possible that each of the two parts referred to may be constructed of those materials which are best suited to the particular function of the respective part.

The further advantage exists that only the supporting member which is the one most subjected to wear and abrasion when it slides over the suction box, needs to be replaced from time to time, while the upper or outer member or felt is free of such abrasion and will last for a long time. The upper or outer member, furthermore, may be made so that it will be highly absorbent to water and thereby improve the treatment of the paper web.

The inner or supporting web may also serve as an auxiliary wire for removal of water and to this end may be provided with corresponding pores or may be constructed so as to have a relatively open mesh. The significance of the supporting web is that it serves simultaneously as the fabric in the fabric press 10, 11 of FIGURE 3. Such a fabric, which may consist of incompressible meshes of a polymer, is employed in modern pressing technology; it serves the purpose of picking up a portion of the water which is squeezed out of the fibrous web, and in this way, avoids the migration of too much moisture back into the pressing felt 5 which truly does the pressing in the correct sense of the word. The water which is retained in the meshes of the supporting web 8 is removed by, blowing, for example, after the web 8 has left the pressure zone. The supporting web thus serves simultaneously as the fabric of the fabric press.

A still further advantageous possibility exists in that no true felt need to be used in the pick-up of a paper web because the pick-up is accomplished by the application of the suction through the supporting member and which member, as mentioned, need not be felted but is so constructed that it is highly porous and resists abrasion and slides freely on the suction shoe. The outer member which directly contacts the paper web may, of course, be a felt.

By having the suction shoe or suction box stationarily mounted, the suction zone thereof, which is formed by providing the box or shoe with perforations, extends only over that portion of the shoe engaged by the pick-up member so that the maintaining of a high degree of suction within the box or shoe is a relatively simple matter.

Referring now to the drawings somewhat more in detail, in FIGURE 1, wire 1 of a paper making machine is guided over couch roll 2 and the deviating or reversing roll 3, and which is also a driving roll. Wet paper web 4 is disposed on wire 1.

A pickup and conveying member 5 is guided over a stationary hollow suction shoe or suction box 6 so as to make contact with paper web 4 at a point therealong located between couch roll 2 and deviating or reversing roll 3. The paper web 4, due to the influence of suction box 6 is transferred at that point to conveying member 5.

The suction box 6 is provided with holes 7 extending therethrough and communicating with the back of member 5. These holes are distributed over the region where the paper web 4 is picked up and extend laterally across the entire width of the felt or member 5 where the paper web is to be picked up. Suction is developed within the suction box or shoe 6 by way of connection 8 which is connected to a suitable source of suction. Connection 8 is so located at the bottom of the suction shoe as to serve also as a drain connection for water drawn into the shoe.

In FIGURE 2, substantially the same arrangement is illustrated and the same reference numerals are employed except that in FIGURE 2 the suction box or suction shoe, designated 6a, is a hollow cylinder instead of being of the configuration shown in FIGURE 1.

In both of the modifications of FIGURES 1 and 2 water which is drawn through member 5 and into the suction box or shoe runs to the bottom thereof and can fiow off via connection 8.

FIGURE 3 is a view showing more completely the pickup section according to the present invention. In FIG- URE 3 wire 1, as before, passes about the couch roll 2 and deviating or reversing roll 3 and carries the wet paper web 4, which is designated by the dotted lines in FIGURE 3. The pick-up member in FIGURE 3 consists of an outer endless member 5 in the form of a pick-up felt and an inner supporting member 8 which may be a fabric-like member of a different character than member 5. Member 8 is shown as a dashed line.

The members 5 and 8 converge and pass as a unit in face to face engagement about suction shoe or box 6a and then continue as a unit and with the paper web 4 adhered thereto about the deviating roller 9 and then pass through a press section consisting of rolls and 11.

Web 4 is drawn off from roll 11, whereas member 5 continues from rolls 10 and 11 along an independent path and passes about a series of idler rolls and then returns through the two rolls 12 and 13, forming a washing press, and then again passes to suction box 6a. The inner or supporting member 8 on the other hand, separates from pick-up member 5 as the members leave rolls 10 and 11 and passes along an independent path about its own idling rolls and then returns to the suction box 6a where it again joins with the pick-up member 5.

It will be understood that the showing in FIGURE 3 is only exemplary of different arrangements that could be made and that the Washing section 12 and 13 is not essential in all cases.

FIGURE 3 illustrates what might be done when the pick-up member 5 and supporting member 8 are constructed of different materials. Member 8 for example, can be made from polyamide or from polyester fibers and is relatively porous for the free passage therethrough of suction and water. Member 5, on the other hand, is more in the nature of a conventional felt in that it presents a surface to the paper which will not damage the paper in any way. Member 5, however, does not have to have the characteristics of a felt, as this term is generally employed in the paper making art, because the transfer of the web thereto is accomplished by suction from the suction box or suction shoe and not in the manner that a paper web is usually transferred to a felt conveyor member by the application of pressure between the paper web and the felt member.

It will be understood, further, that the wire 1 of the paper making machine is quite porous whereas the paper Web 4 is relatively dense and that, therefore, the application of suction through the pick-up member to the paper web 4 will cause the paper web readily to be picked up from the wire with substantially no fibrous residue remaining on the wire. The transfer of the web from the paper making machine to the pick-up and conveying member 5 is thus relatively complete at all times resulting in highly efficient operation of the arrangement.

Still further, since the transfer of the paper web is effected by suction there is no need to add water at any time to the pick-up member 5 as is sometimes necessary with other types of pick-up devices not employing suction.

The device of the present invention operates well at any speed and is as effective for picking up thin webs as it is for picking up thick webs. In operation, no adjustments need be made except, possibly, to vary the degree of suction in the suction box or shoe.

It will be understood that this invention is susceptible to modification in order to adapt it to different usages and conditions and accordingly, it is desired to comprehend such modifications within this invention as may fall within scope of the appended claims.

What is claimed is:

1. In a paper making machine having a porous belt on which a fibrous web is formed and rolls supporting said porous belt and a porous belt-like conveyor member operable for picking up said web from said porous belt in a region extending transversely of said porous belt and for conveying the web to a following work station, said region being located between said rolls where said porous belt is unsupported, said conveyor member converging With said porous belt on one side of said region and diverging therefrom on the other side of said region and running in the direction and at substantially the same linear speed as said porous belt in said region, said conveyor member engaging the exposed side of the web in said region, and a stationary nonrotatable member relatively small in cross section extending transversely of said conveyor member and supportingly and slidingly engaging the back of said conveyor member in said region and guiding said conveyor member into and out of and through said region, said stationary member being in the form of a substantially rigid hollow box, the surface of said box which engages the back of said conveyor member being curved so as to be convex toward said porous belt at least over the range of said region, a suction connection to said box to develop suction therein, and apertures in said box distributed longitudinally and arcuately over the transverse exent of said region and over substantially the arcuate extent of said region, said apertures communicating with the back of said coveyor member at least in said region thereby to exert suction through said conveyor member on said web to effect transfer of the web from the porous belt of said paper-making machine to said conveyor member.

2. The combination according to claim 1 in which the said rolls supporting said porous belt include a couch roll and a driving roll spaced therefrom, and said stationary member being positioned substantially midway between said rolls so that the said region where the web is picked up is about in the middle of the reach of the porous belt exltfnding between the said couch roll and the said driving ro 3. The combination according to claim 1 in which said rolls have their axes horizontal and said stationary member has its longitudinal axis horizontal and said suction connection is located in substantially the lowest portion of said stationary member whereby water drawn into said stationary member through said apertures as the said web is picked up can be drained from said stationary member.

4. The combination according to claim 1 in which said conveyor member is two sided and comprises a wear resistant portion on the side engaging the said surface of said stationary member and a felt-like portion on the side which engages said web.

5. The combination according to claim 4 in which said wear resistant portion is a material formed of synthetic fibers such as polyamide or polyester fibers.

6. The combination according to claim 1 in which said conveyor member is a substantially incompressible, porous belt-like member resistant to wear.

7. The combination according to claim 1 in which said conveyor member comprises an inner belt which slides on said member and an outer belt separate therefrom which engages said web.

8. The combination according to claim 1 in which said conveyor member comprises an inner belt which slides on said member and an outer belt separate therefrom which engages said web, and means guiding said inner belt and outer belt for movement in face to face relation into and through and out of said region where the web is picked up and to the following work station and along independent paths from the exit of said work station to the entrance to said region.

9. The combination according to claim 7 in which said inner belt is in the form of a seine-like element through which air and water can freely move.

10. The combination according to claim 1 in which said stationary member is in the form of a hollow cylinder.

References Cited UNITED STATES PATENTS 2,709,398 5/1955 Beachler l62206 DONALL H. SYLVESTER, Primary Examiner.

A. C. HODGSON, Assistant Examiner.

US. Cl. X.R. l394l0

Images