US3273492A

US3273492A - Suction roll counter-deflector

Info

Publication number: US3273492A
Application number: US316711A
Authority: US
Inventors: Edgar J Justus
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1963-10-16
Filing date: 1963-10-16
Publication date: 1966-09-20
Anticipated expiration: 1983-09-20

Description

Sept. 20, 1966 E. J. JUSTUS 3,273,492

SUCTION ROLL COUNTER-DEFLECTOR Filed Oct. 16, 1963 2 Sheets-Sheet 1 II I! W INVENTOR. Z@a"z l Jzzsags A TTORNElaS United States Patent 3,273,492 SUCTION ROLL CUUNTER-DEFLECTQR Edgar J. Justus, Beloit, Wis, assignor to Beloit Qorporation, Beloit, Wis, a corporation of Wisconsin Filed Oct. 16, 1963, Ser. No. 316,711 18 Claims. (Cl. 100-90) This invention relates to apparatus for mounting a roll the centroidal axis of which is subject to deflection and more particularly relates to apparatus for mounting a suction roll which is subjected to a load tending to effect central deflection of the roll axis.

Although the instant invention may be useful in a number of arts, including textile treating, it is particularly useful in the papermaking art and will be described primarily in connection therewith. In general, the instant invention relates to apparatus for mounting a roll shell having a substantial length-to-diameter ratio and whose centroidal axis is subject to deflection in response to the loads applied to the shell during use.

In paper machines there are a number of different types of rolls of substantial size (i.e., substantial length) which are subjected to loads tending to deflect such rolls generally. For example, in press couples, calender stacks, etc., the web passes through a nip between a pair of rolls at which the web is subjected to pressures. The pressure thus applied at such nip tends to load the rolls defining the nip and to deflect the axes of these rolls, thereby causing non-uniform cross-machine nip loads.

Another example of a roll shell having a substantial length-to-diameter ratio is a suction roll which includes a perforated revolving roll shell over which a moist web passes and is dewatered due to a vacuum condition which exists within the roll shell. This shell is also generally subject to deflection due to the various loads acting thereon, which may include the vacuum applied to the shell and the weight of the shell and which may also include, when the suction roll is used in conjunction with another roll to define a press couple forming a press nip to squeeze the web, an additional load due to the nip loading.

If one of the rolls defining a nip is backed up by other rolls or other means, its tendency to deflect away from the nip is reduced or may be completely overcome so that it is defected in the direction of the nip. On the other hand, certain press rolls and, for example, a suction roll may not be provided with back up means and the pressures or loads thus applied thereto tend to deflect the same centrally. Such deflection results in undesirable and/or nonuniform application of forces across the roll, or across the nip, and other undesirable operating features.

Deflection of roll shells is often corrected in paper machines by crowning of the shell. Crowning requires accurate and expensive finishing of the roll surface so as to obtain a slightly greater roll diameter in the central portion of the roll and furthermore such crowning is carried out on the basis of a predetermined set of force conditions and may not be satisfactory for operating under a different set of force conditions. In addition, a crowned roll will have a somewhat greater circumference in the crowned region (usually at the center) than at the uncrowned regions of the roll, and this results in a slightly greater surface speed at the outer periphery of the roll in the crowned region. Such surface speed differences in the operation of certain nips result in undesirable operating characteristics in many instances. It will thus be seen that crowning of rolls often does not afford satisfactory operation for many different types of operat ing conditions.

Another method of correcting for roll deflection involves the use of force couples for applying internal 3,273,492 Patented Sept. 20, 1966 counter-deflection moments to the shell in response to the application of the load to the shell in such a manner as to more or less automatically resist or minimize deflection of the roll when it is subjected to various loads. General concepts as Well as more specific aspects of this type of roll shell mounting arrangement are described in Edgar J. Justus US. Patents 3,097,590 and 3,097,591 which are owned by the assignee of the instant invention and which disclosures are incorporated herein by reference.

The application of internal counter-deflection moments to the shell to minimize deflection presents peculiar problems in the case of suction rolls, however. Due to the drilling pattern of the perforations of a suction shell its bending efficiency may be as little as 40% to 50% of the efliciency of an undrilled shell. This unavoidable reduction in bending efficiency therefore generally results in a thicker and consequently more expensive suction roll shell.

The instant invention affords a unique improvement in roll shell mounting structures and particularly suction rolls which embody the basic concepts of counter-deflection moments heretofore mentioned. In certain rolls, for example, suction rolls, a roll shell may be carried on a shaft or beam member which extends through the shell. In the case of a suction roll, the roll shell may comprise a perforate portion for dewatering the web and the shaft or beam member is non-rotating and includes a suction box or gland formed integrally therewith to align with the perforate portion of the shell.

Since the bending efficiency of a perforate suction roll shell is appreciably reduced as compared to an imperforate shell, the necessary counter-deflection should be attained with minimum bending moment, particularly in the center of the shell. Such reduction in bending moment would, of course, permit the utilization of a thinner and consequently less expensive roll shell.

The present invention contemplates the utilization of novel mounting structure for appreciably reducing the bending moment of the roll shell for any given load applied thereto as a result, for example, of nip pressure, applied vacuum or weight of the shell. Briefly, the journals of the roll shell are extended and forced generally .in a direction opposite to the direction of the load which is applied to the shell thereby urging the center portion of the shell in a direction opposite to the direction of the applied loads. This mounting arrangement results in a drastic reduction of the bending moment in the center of the shell. In certain cases this reduction may be as high as 20 to 30%. Although the bending moment on the shell journals will generally increase, the journals are not drilled and are, therefore, fully capable of taking the additional load.

It is, therefore, an important object of the present invention to provide an improved roll mounting structure.

It is another object of the instant invention to provide an improved arrangement for mounting a roll shell having a substantial length-to-diameter ratio .in order to correct for tendencies toward deflection of the roll shell axis as a result of loads applied thereto.

Yet another object of the present invention is to provide a roll shell for a suction roll assembly having a perforate center portion and a substantial length-to-diameter ratio, and whose centroidal axis is subject to deflection in response to a load applied to the shell, axially aligned shaft means in the shell and in spaced relation thereto for rotatably mounting the shell, imperforate journal portions at each end of the roll shell, bearing means on the shaft means and engaging the journal portions of the shell for maintaing the shell in axially spaced relation to the shaft means, and force imposing means acting on the journals and axially spaced relative to the bearing means for imparting counter-deflection force cou- 'ice p le to the shell while minimizing bending moments in the shell, particularly in the perforate center portion thereof.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a preferred structural embodiment of the inventive principles herein disclosed is shown by way of illustrative example.

On the drawings:

FIGURE 1 is a somewhat diagrammatic elevational illustration of a roll shell mounting structure constructed in accordance with the principles of the present invention and showing portions of the structure in section;

FIGURE 2 is a fragmentary essentially diagrammatic view illustrating the suction roll shell and the press roll of FIGURE 1 arranged in nip-defining relation to provide a press couple;

FIGURE 3 is essentially a force diagram illustrating loads and forces applied to a conventional suction roll and includes a formulation of the maximum bending moment acting on the shell as a result of the applied loads and forces;

FIGURE 4 is also essentially a force diagram illustrating loads and forces applied to an anti-deflection suction roll constructed in accordance with the principles of the present invention and includes a formulation of the maximum bending moment acting on the shell as a result the improved mounting arrangement of the shell; and

FIGURE 5 is an essentially diagrammatic illustration of deflection curves involved in a consideration of the instant invention.

As shown on the drawings:

In FIGURE 1, it will be seen that the assembly of the instant invention, indicated generally by the reference numeral 10, is adapted to mount a suction roll assembly 11 including a roll shell 12 having a substantial length-todiameter ratio. A pressure roll 13 may conveniently be mounted in nip defining relation with the roll shell 12 for providing a press couple having a press nip as at 14. Journal means 16 are provided for rotatably mounting the press roll 13 and suitable apparatus may be provided for applying a load to the press roll to pressurize the nip 14, for example, pressurized hydraulic cylinder means (not shown).

The nip defining relationship between the press roll 13 and the suction roll shell 12 is also illustrated in FIG- URE 2 wherein is shown a web W in a moistened condition as supplied, for example, from the wire forming section of a paper-making machine to pass through the pressurized nip 14. In order to dewater the web as it passes through the nip a suction box or gland 17 is housed within the shell 12 in spaced relation thereto and it will be appreciated that during operation a suction chamber 18 defined by the suction box 17 is maintained at a subatmospheric or vacuum condition in order to withdraw water from the web into the chamber. To permit access of the water through the shell 12 into the chamber 18, a plurality of circumferentially and axially spaced perforations as at 19 are formed in the shell 12 to extend radially therethrough and an upper portion 20 of the suction box 17 immediately adjacent the pressurized nip 14 defines an axially extending slot 21 for communicating the chamber 18 with the perforations 19 and therefore with the nip 14.

The suction box 17 is non-rotatable, and in order to insure that the vacuum condition which exists within the chamber 18 acts only on that portion of the shell 12 adjacent the nip 14, a pair of axially extending seals 22 are carried by upper shoulders 23 of the suction box to isolate that portion of the inner periphery of the shell 12 from the remainder thereof, thereby providing that that portion of the shell 12 immediately adjacent the nip 14 will be in communication exclusively with the chamber 18 and thereby have a suction force applied thereto.

In order to provide for varying axial alignment and spacing between the shell 12 and the movable suction box 17 as various loads are applied to the shell to cause deflection thereof, the seals 22 may constitute any suitable resilient material, such as rubber, such that the suction area of the roll defined by the seals will remain under a vacuum condition regardless of deflection of the shell 12.

It will be appreciated that the roll shell 12 of FIGURE 1 has a length which exceeds by many times its diameter, and whose centroidal axis defines a straight line (indicated at C-12 in FIGURE 5) in a completely unloaded condition of the shell. That is, the axis C-1-2 is a center line for the shell 12 when the shell is not subjected to any loading forces whatsoever, including the load of its own weight. Practically speaking, however, the shell 12 is always subjected to a load across its entire width. This load is equal to at least the load of the weight of the shell, but of course in operation this load may be increased by the load applied 'by the press roll 13 and the effective load applied by the vacuum condition in the suction chamber 18, both of which act across substantially the entire width of the shell 12. Generally, any load or any combination of loads acting on the shell '12 are uniformly distributed over the width of the shell to cause a deflection in the axis of the shell to a position indicated in exaggerated form in FIGURE 5 by the dashed line DD-12.

The actual deflection of any given roll shell, of course, depends upon many factors including the length-to-diameter ratio of the shell, the load or combination of loads applied to the shell, the thickness of the shell, the material of construction of the shell as well as the mounting arrangement of the shell, among others.

In FIGURE 1 that portion of the width of the shell across which the perforations are formed is indicated at 23. In conventional suction roll shells the perforated por tion extends substantially across the entire width of the shell but in the embodiment illustrated in FIGURE 1 the perforate portion 23, while comprising a substantial percentage of the width of the shell 12, does not extend to the ends of the shell as indicated at 24 and 26.

At each end of the perforate portion 23, that is, between the perforate portion and the shell ends 24 and 26 respectively, is formed an axially extending tubularly shaped reduced diameter imperforate journal portion as at 27 and 28. The inboard ends of

journals

27 and 28, that is, the ends thereof that are situated in the direction of the center of the width of the shell 12, are joined to the enlarged diameter perforate portion 23 by means of a circumferentia-lly continuous radially extending member thereof as at 25.

It is important to note that the invention is directed to the control of deflection in perforate suction roll shells which have certain general characteristics which make such control particularly diflicult. For example, such shells may have a radial thickness of from perhaps to 2 inches; for varying stiffness in the shell; but in any case the length-to-diameter ratio of the perforate portion of the shell alone is within the range of about 6:1 to 12:1 and the average open area (i.e. total area of the perforations divided by total peripheral area of the perforate position of the shell) is about 15% to 40% so that the roll shell is particularly responsive to loads. In the instant invention the imperforate end portions (the portions M, M in FIGURE 4) have lengths suflicient for the application of the desired force couple thereto; and as compared to the central perforate portion (N of FIG- URE 4) the ratio of the lengths of M :N is Within the range of 1:10 to 1:6.

Additional details of the construction of the roll shell '12 will be discussed hereinafter, but it is important to note that the embodiment of the roll shell illustrated in FIGURE 1 and which is constructed in accordance with the principles of the present invention difi'ers from the conventional suction roll 12 in that it comprises. a pair of journal portions, and in the embodiment illustrated a reduced diameter imperforate journal portion is formed at each end of the perforate portion, at which the bending efficiency of the roll shell is substantially and unavoidably reduced because of the necessary drilled perforations.

As in the case of a conventional suction roll assembly, the suction box 17 shown in FIGURE 1 is formed integrally with and comprises the center portion of a center beam or shaft 29 which is housed within the tubular roll shell 12 and which extends outwardly therefrom at the end-s thereof as at 30 and 31.

Opposed end portions

32 and 33 of the beam 29 may preferably be cylindrically shaped and one end portion as at 33 may be formed with a bore as at 34 formed therein and extending therethrough for communicating the suction chamber 18 of the suction box 17 with a suitable vacuum producing means, such as a vacuum pump (not shown). The opposite end portion 32 may comprise a solid member and both of the end portions may be immovably supported by means of a fixed support member as illustrated at 36.

In accordance with the principles of the present invention the roll shell 12 may be supported for rotation by means of the beam or shaft 29 and to this end a pair of bearing members 37 and 3*? are mounted respectively on the

end portions

32 and 33 of the shaft 29 to engage the

journal portions

27 and 28 inboardly of their respective ends 24 and 26. In addition to providing for rotation of roll shell 12, the bearing members perform the additional function of maintaining the shell i 2 and the beam 29 in coaxially spaced relation.

It will be appreciated that the beam 29 is also subject to deflection in response to loads to which it may be subjected, which may include of course the weight of the beam itself and also the load imposed thereon by the roll shell 12. Other factors, of course, enter into the deflection characteristics of the beam, such as the length-to-diameter ratio, the materials of construction and the other factors mentioned heretofore in connection with the deflection characteristics of the roll she'll.

It is not necessary, of course, that the roll shell 12 and the beam 29 have similar deflection characteristics and preferably in this respect they are quite different. In a preferred embodiment of the invention the rigidity of the beam 29, that is, its inherent resistance to deflection, is greater than the corresponding inherent resistance to deflection of the roll shell 12 so that in the event that a load is imposed upon the roll shell its inherent resistance to deflection will yield substantially to the greater inherent resistance of the shaft 29, that is, although the shell may deflect relatively substantially, the beam will deflect very little or not at all.

Referring to FIGURE 3, the various loads imposed upon a conventional suction roll shell are illustrated as acting at various locations along the width of the shell. The perforated portion of the conventional suction roll shell 39, which essentially comprises the entire Width of the shell, is indicated by the reference character N which represents the width of the shell and may conveniently be expressed in terms of lineal inches of width. The load applied to the shell, which may comprise the weight of the shell, the action of the vacuum imposed thereon at the suction area thereof and the force applied by a press roll cooperating with the shell to from a press couple, is indicated by the reference L and since this composite load or any separate component thereof acts uniformly across the entire width of the shell, the load L may be expressed in terms of pounds per linear inch of shell width. Since a conventional suction roll shell is generally supported on its associated beam only at the ends of the shell, the oppositely acting supporting forces at the ends of the shell are equal to each other as indicated at reference characters R and may conveniently be expressed in terms of pounds of force.

The maximum bending moment to which a conventional suction roll shell is subjected in operation may be de- 6 fined by the equation indicated in FIGURE 3 which reads as follows:

Maximum bending moment (R N/2)(L N/2 N/4) Where:

L=composite applied load acting uniformly across width of shell, lbs. per lineal inch N=width of shell=-width of perforated portion of shell, inches R=equal forces acting against load L at shell support members, lbs.

To illustrate the maximum bending moment to which a conventional suction roll shell 39 is subjected in accordance with the above equation, assume that the composite applied load L equals 50 lbs. per inch and the shell width N equals 200 inches. The opposing forces R will then equal 5,000 lbs. and the maximum bending moment of the shell can be calculated as follows:

Maximum bending moment =5,000 200-:-250 l00 50 =250,000 inch-lbs.

As will become apparent hereinafter the improved roll shell mounting means of the present invention not only acts to cause counter-deflection of the roll shell to partially offset and compensate for the deflection resulting from the applied load but also performs the advantageous function of actually decreasing the maximum bending moment to which the perforated portion of the shell is subjected, thereby permitting the utilization of a thinner and less expensive shell.

Referring again to FIGURE 1, it will be noted that at each of the outboard end portions of

journals

27 and 28 there is mounted respectively thereon a bearing member as indicated at 40 and 41 which can be effectively utilized to impose a force at the end of each journal, thereby providing a force couple in conjunction with the corresponding axially spaced bearing

members

37 and 38. In effect, bearing

members

37 and 38 act as fulcrum points for two force couples, one of which is the force couple provided by the load applied to the roll shell and which acts effectively at the center point across the width of the shell, and the second of which is provided by a force acting on the axially spaced bearing

members

40 and 41. Generally the most advantageous utilization of bearing

members

40 and 41 occurs when forces are imposed thereon which act in a direction similar to the direction of the composite load acting upon the roll shell 12 which, in the illustrated embodiment, lies in a vertically downward direction. Thus, means are provided for imposing a downward force on each of the bearing

members

40 and 41 and such force imposing means may conveniently take the form of pressurized fluid operated hydraulic cylinders illustrated diagrammatically at 42 and 43, one end of which as at 44 engages a corresponding bearing member and another end of which as at 46 is connected to and immovably supported by a fixed support member, .for example, members 36.

The advantages of the improved mounting structure of FIGURE 1 can be exemplified by making advantageous reference to FIGURE 4 wherein is illustrated'diagrammatically the roll shell 12 of FIGURE 1 being acted upon by the composite applied load L acting across the entire width of the perforate portion as at N. As opposed to the conventional roll shell illustrated in FIGURE 3, the anti-deflection roll shell of the present invention as illustrated in FIGURE 4 comprises the

journal portions

27 and 28 extending from the ends thereof. It will be assumed that the axial position of the forces R corresponds with the axial positioning of the bearing

members

37 and 38, the forces R comprising the restraining force acting upon the shell 12 through the bearing

members

37 and 38. The reference character M" indicates the axial displace ment between corresponding bearing

members

37 and 40 and 38 and 41, such displacement being equal to the width of

journal members

27 and 23 conveniently expressed in terms of lineal inches. Forces indicated by the reference characters S indicate the forces imposed respectively on bearing

members

40 and 41 by the force Imposing means or hydraulic cylinders 42 and 43.

In order to exemplify the advantageous reduction in maximum bending moment provided by the novel mounting arrangement of the present invention, assume that the composite load L acting on the roll shell 12 of FIGURE 4 is equal to the load L of FIGURE 3, that is, 50 lbs. per lineal inch. In addition, assume that a force S equal to 2,000 lbs. is imposed upon

journal portions

27 and 28 in the same direction as the load L is imposed upon the roll shell 12. The restraining or opposite forces R would then each equal s 200+2 2000 +2=7000 lbs.

The maximum bending moment at the center of the shell 12 can be calculated by means of the equation illustrated in FIGURE 4, and in the assumed example given, is as follows:

Maximum bending moment =(R N/2)(L N/2 N/4) 200/4)[2000(200/2+25)] =200,000 in.-lbs.

Where M: distance between R and 8:25" S=force imposed at bearing members 42 and 43 =2,000 lbs.

It will be apparent, therefore, that in the event that the load L is given the same value for the conventional roll shell arrangement of FIGURE 3 and the anti'deflec- :ion roll shell arrangement of FIGURE 4, the maximum bending moment of the center of the roll shell 12 of FIGURE 4, constructed and mounted in accordance with ;he principles of the present invention, is 20% less than ;he maximum bending moment at the center of the conventional roll shell of FIGURE 3.

In addition to reducing the maximum bending moment :0 which the imperforate portion of the roll shell 12 is subjected, the improved mounting arrangement of the present invention also serves the advantageous function of providing anti-deflection to the shell to partially compensate for and offset the deflection caused by the applied load. Referring to FIGURE 5, the dashed lines 8-37 and B-38 arranged perpendicularly to the center axis line C-12 represent the locations of bearing members 57 and 38 respectively, and dashed lines B-40 and B4l1 represent the positioning of the bearing

members

40 and 41 respectively. It will be apparent that if no load what- ;oever were imposed upon the roll shell with the excepiion of the forces imposed on bearing

members

40 and 41, the roll shell axis would assume an upwardly directed deflection as indicated by the dashed lines UD12. In operation, of course, the composite load L acts downwardly upon the roll shell and the resulting deflection of the axis when the shell is subjected to the applied load L and the loads imposed by bearing

members

40 and 41 assume the curve indicated at CD12, which is exaggerated for the sake of clarity in FIGURE 5.

It will be noted that curve CD-l2 includes a pair of peaks as at P-37 and P-38 which result from the restraining action of the fulcrum-acting

bearing members

37 and 38. The so-called peaks are actually so small as to be negligible in most instances, even though they represent the maximum final deflection of the center line CD-12 from the true center line C-12.

It will be appreciated that although the force imposing means 42 and 43 are described herein as fluid pressurized hydraulic cylinders, any suitable apparatus for imposing a force upon bearing

members

40 and 41 may be conyeniently utilized. It will further be appreciated that the seals 22 (FIGURE 2) are resilient and subject to sufficient deformation so as to insure isolation of the suction area of the inner periphery of the shell 12 in spite of the deflection to which the roll shell is subjected.

Although minor modifications might be suggested by those versed in the art, it should be understood that I Wish to embody within the scope of the patent warranted hereon all such modifications as reasonably come Within the scope of my contribution to the art.

I claim as my invention:

1. A roll assembly for use in a suction press or the like apparatus comprising:

a roll shell having normally a straight line centroidal axis that develops normally a central deflection in response to a load applied to the shell,

shaft means for the roll shell,

fixed support means for supporting said shaft means at the ends thereof,

first bearing means mounted on said shaft means inboard of said fixed support means and engaging said roll shell for normally maintaining said shaft means and said roll shell in coaxially aligned and spaced relation,

second bearing means mounted on said roll shell at the ends thereof for vertical movement relative to said fixed support means and situated between said fixed support means and said first bearing means, and

force imposing means operatively engaging said second bearing means for applying a force to the ends of said roll shell to act against restraint provided by said first bearing means to provide counter deflection of said roll shell in opposition to the deflection caused by a load applied thereto.

2. A roll assembly for use in a suction press or the like apparatus comprising:

a roll shell having normally a straight line centroidal 'axis'that develops normally a central deflection in response to a load applied to the shell,

shaft means for the roll shell,

fixed support means for supporting said shaft means at the ends thereof,

second bearing means mounted on said roll shell at the ends thereof for vertical movement relative to said fixed support means and situated between said fixed support means and said first bearing means,

force imposing means operatively engaging said second bearing means for applying a force to the ends of said roll shell to act against restraint Provided by said first bearing means to provide counter deflection of said roll shell in opposition to the deflection caused by a load applied thereto,

said shaft means having a greater resistance to deflection than said roll shell.

3. A suction roll for use in a press couple forming a press nip in a papermaking machine comprising:

a roll shell the centroidal axis of which is subject to deflection in response to a load applied to the shell,

shaft means for said roll shell,

support means for supporting said shaft means at the ends thereof,

first bearing means carried by said shaft means and engaging said roll shell for maintaining said shaft means and said roll shell in mutually spaced relation,

second bearing means carried by said roll shell in axially spaced relation to said first bearing means, and

force imposing means operatively connected to said second bearing means for imposing a force on said roll shell to act against said first bearing means and the restraint to the shell afforded thereby to cause deflection of the shell.

4. A suction roll for use in a press couple forming a press nip in a papermaking machine comprising:

shaft means for said roll shell,

support means for supporting said shaft means at the ends thereof,

second bearing means carried by said roll shell in axially spaced relation to said first bearing means and in radially spaced relation to said shaft means, and

5. A suction roll for use in a press couple forming a press nip in a papermaking machine comprising:

shaft means for said roll shell,

support means for supporting said shaft means at the ends thereof,

second bearing means carried by said roll shell outboard of said first bearing means, and

a radially directed force imposing means operatively connected to said second bearing means for imposing a radial force on said roll shell to act against said first bearing means and the restraint to the shell afforded thereby to cause deflection of the shell.

6. A suction roll for use in a press couple forming a press nip in a papermaking machine comprising:

a roll shell the centroidal :axis of which is subject to deflection in response to a load applied to the shell,

shaft means for said roll shell,

support means for supporting said shaft means at the ends thereof,

second bearing means carried by said roll shell between said first bearing means and said support means and in radially spaced relation to said shaft means, and

a radially directed force imposing means operatively connected to said second bearing means for imposing a radial force on said shell to act against said first bearing means and the restraint to the shell afforded thereby to cause deflection of the shell.

7. A roll assembly for use in a suction press or the like apparatus comprising:

a roll shell having a given resistance to deflection and having normally a straight line centroidal axis that develops normally a central deflection in response to a load applied to the shell,

said roll shell comprising a first portion having an inherent resistance to deflection of a first degree and a second portion at each end of said first portion having an inherent resistance to deflection of a second degree,

shaft means for said roll shell having a given resistance to deflection which is greater than the given resistance to deflection of said roll shell, fixed support means for supporting said shaft means at the ends thereof,

first bearing means mounted on said shaft means and engaging said second portions of said shell for normally maintaining said shaft means and said shell in coaxially mutually spaced relation,

second bearing means mounted on said second portion of said shell in axially spaced relation to said first bearing means, and

radially directed force imposing means operatively engaging said second bearing means for applying a force thereto to act against restraint provided by said first bearing means for causing a force couple to deflect said roll shell relative to said shaft means and in opposition to a deflection caused by a load applied to said roll shell.

8. A roll assembly for use in a suction press or the like apparatus comprising:

said roll shell comprising a first portion having an inherent resistance to deflection of a first degree and second portion at each end of said first portion having an inherent resistance to deflection of a second degree,

shaft means for said roll shell having a given resistance to deflection which is greater than the given resistance to deflection of said roll shell,

fixed support means for supporting said shaft means at the ends thereof,

first support means mounted on said shaft means inboard of said fixed support means and engaging said second portions of said roll shell for normally maintaining said shaft means and said shell in coaxially aligned and mutually spaced relation,

second bearing means mounted on said second portions of said roll shell and axially spaced relative to and outboard of said first bearing means, and

radially directed force imposing means operatively engaging said second bearing means for applying a force thereto to act against restraint provided by said first bearing means for causing force couples to deflect said roll shell in opposition to a deflection caused by a load applied thereto.

9. A roll assembly for use in a suction press or the like apparatus comprising:

said r-oll shell comprising a first portion having an inherent resistance to deflection of a first degree and second portions at each end of said first portion having an inherent resistance to deflection of a second degree,

shaft means for said roll shell having 'a given resistance to deflection which is greater than the given resistance to deflection of said roll shell,

fixed support means for supporting said shaft means at the ends thereof,

first bearing means mounted on said shaft means inboard of said fixed support means and engaging said second portions of said roll shell for normally maintaining said shaft means and said shell in coaxially aligned and mutually spaced relation,

second bearing means mounted on said second portions of said shell and axially spaced relative to said first bearing means, and

radially directed force imposing means operatively engaging said second bearing means for applying a force thereto to act against restraint provided by said first bearing means for causing force couples to deflect said roll shell in opposition to a deflection caused 'by a load applied thereto and to deflect said shaft means oppositely to the deflection of said roll shell,

the deflection of .said roll shell being greater than the deflection of said shaft means when acted upon by the force couples.

10. A roll assembly for use in a suction press or the like apparatus comprising:

a roll shell having a first portion of a first diameter and second portions at each end of said first portion of a second diameter,

shaft means extending through said roll shell,

said roll shell and said shaft means being subject to deflection in response to loads applied thereto,

fixed support means for supporting said shaft means at the ends thereof,

first bearing means mounted on said shaft means and engaging said roll shell for maintaining said shaft means and said roll shell in coaxially spaced relation,

second bearing means carried by said second portions of said roll shell, and

radially directed force imposing means operatively connected to said second bearing means for applying a force thereto to act against the restraint provided by said first'bearing means and said fixed support means, said second bearing means being spaced axially relative to said first bearing means and said fixed support means such that force couples set up thereby will deflect said roll shell more than said shaft means.

11. A roll assembly for use in a suction press or the like apparatus comprising:

shaft means extending through said roll shell,

fixed support means for supporting said shaft means at the ends thereof,

first bearing means mounted on said shaft means and engaging said roll shell at said second portions for maintaining said shaft means and said roll shell in coaxially spaced relation,

second bearing means carried by said second portions of said roll shell, and

radially directed force imposing means operatively connected to said second bearing means for applying a force thereto to act against the restraint provided by said first bearing means and said fixed support means,

said second bearing means being positioned between said first hearing means and said fixed support means and being spaced axially relative to said first hearing means and said fixed support means such that force couples set up thereby will deflect said roll shell in a first direction and said shaft means in a second direction.

12. A roll assembly for use in a suction press or the like apparatus comprising:

a roll shell'having a first portion of a first diameter and second portions at each end of said first portion of a second diameter,

shaft means extending through said roll shell,

said roll shell and said shaft means being subject to deflection in response to loads applied there- [0,

fixed support means for supporting said shaft means at the ends therof,

second bearing means carried by said second portions of said roll shell, and

said second bearing means being positioned between said first bearing means and said fixed support means and being spaced axially relative to said first bearing means and said fixed support means such that force couples set up thereby Will deflect said r-oll shell in a first direction and said shaft means in a second direction, the deflection of said roll shell being greater than the deflection of said shaft means regardless of the magnitude of the force imposed by said force imposing means.

13. A roll assembly for use in a suction press or the like apparatus comprising:

shaft means extending through said roll shell,

fixed support means for supporting said shaft means at the ends thereof,

second bearing means carried by said second portions of said roll shell outboard of said first bearing means and inboard of said fixed support means,

radially directed force imposing means operatively connected to said second bearing means for applying a radial force thereto to act against the restraint provided by said first bearing means and said fixed support means,

whereby a force supplied by said force imposing means will set up force couples in said roll shell to deflect said shell in opposition to a load applied thereto.

14. A suction roll for use in a press couple forming a press nip in a papermaking machine comprising:

a roll shell the centroidal axis of which is subject to deflection in response to a load applied thereto,

said roll shell having a perforate portion of a first diameter and other portions of a second di' ameter at each end of the perforate portion, shaft means extending through said roll shell and hav ing suction gland means in axial alignment with said perforate portion,

fixed support means for supporting said shaft means at the ends thereof,

first bearing means mounted on said shaft means and engaging said roll shell at said other portions thereof,

second bearing means carried by said other portions and spaced axially relative to said first bearing means, and

force imposing means engageable with said second bearing means for providing a force couple with said first bearing means to deflect said roll shell in opposition to deflection caused by the load applied thereto.

15. A suction roll for use in a press couple forming a press nip in a papermaking machine comprising:

a roll shell of the centroidal axis of which is subject to deflection in response to a load applied thereto,

said roll shell having a perforate portion and other portions at each end of the perforate portion,

the diameter of said perforate portion being greater than the diameter of said other portions.

shaft means extending through said roll shell and having suction gland means in axial alignment with said perforate portion,

fixed support means for supporting said shaft means at the ends thereof outboard of said roll shell, first bearing means mounted on said shaft means and engaging said roll shell at said other portions thereof,

second bearing means carried by said other portions and spaced axially outboardly relative to said first bearing means and axilly in'boardly relative to said fixed support means, and

radially directed force imposing means engageable with said second bearing means for providing a force couple with said first bearing means to deflect said roll shell in opposition to deflection caused by the load applied thereto.

16. A suction roll for use in a press couple forming a press nip in a papermaking machine comprising:

said roll shell having a perforate portion situated in the middle thereof an imperforate portion at each end thereof,

the diameter of said perforate portions being greater than the diameter of said imperforate portions,

said roll shell having a given inherent resistance to deflection and said shaft means having a substantially greater resistance to deflection,

fixed support means for supporting said shaft means at the ends thereof outboard of said roll shell,

a pair of first bearing means mounted on said shaft means and engaging respectively said roll shell at each of the imperforate portions thereof for maintaining said roll shell and said shaft means in mutual spaced relation and normally in mutually coaxial alignment,

a pair of second bearing means carried respectively on each of said imperforate portions outboard of said first bearing means and inboard of said fixed support means,

said second bearing means being in radially spaced relation relative to said shaft means,

radial force imposing means engageable with said second bearing means for imposing a radially directed force thereon said first bearing means acting as fulcrum to set up a force couple with said force imposing means to deflect said perforate portions in the direction of the force applied by said force imposing means and to cause deflection of said imperforate portion in a direction opposite to the direction of the force supplied by said force imposing means,

said shaft means being caused by said force imposing means to deflect in the same direction as the force imposed thereby,

the axial spacing of said second bearing means relative to said first bearing means and said fixed support means being such that the roll shell deflects more than the shaft means for any given force applied by said force imposing means.

17. A press couple for use in a papermaking machine comprising, in combination:

a suction roll,

a pressure roll for applying a load to the suction roll to provide a pressed nip therebetween,

said suction roll comprising a roll shell the centroidal axis of which is subject to deflection in response to a load applied thereto by said pressure roll,

said roll shell having a perforate portion and a pair of imperforate portions respectively at each end of the perforate portion,

said perforate portion having a diameter which is greater than the diameter of said imperforate portions,

first bearing means mounted on said shaft means and engaging said roll shell at the imperforate portions thereof,

second bearing means carried by said imperforate portions and spaced axially outboardly relative to said first bearing means and axially inboardly relative to said fixed support means, and

radially directed force imposing means engageable with said second bearing means for providing a force couple with said first bearing means to deflect said roll shell in opposition to deflection caused by the load applied thereto from said pressure roll.

18. A press couple for use in a papermaking machine comprising, in combination:

a suction roll, a pressure roll for applying a 'load to the suction roll to provide a pressed nip therebetween, said suction roll comprising:

a roll shell centroidal axis of which is subject to deflection in response to a load applied thereto,

said roll shell having a perforate portion situated in the middle thereof and imperforate portions at each end thereof,

the diameter of said perforate portion being greater than the diameter of said imperforate portions,

shaft means extending through said roll shell and having suction gland means in axial alignment With said perforate portions,

[fixed support means for upporting said shaft means at the ends thereof outboard of said roll shell,

a pair of first bearing means mounted on said shaft means and engaging respectively said roll shell at each of the imperforate portions thereof for maintaining said roll shell and said shaft means in mutually spaced relation and normally in mutually coaxial alignment,

a pair of second bearing means carried respectively on each of said imperforate: portions outboard of said first bearing means and inboard of said fixed support means,

said second bearing being in radially spaced relation relative to said shaft means,

radial force imposing means engageable with said second bearing means for imposing a radially directed force thereon,

said first bearing means acting as a fulcrum to set up a force couple with said force imposing means to deflect said perforate portion in the direction of the force supplied by said force imposing means and to cause deflection of said imperforate portion in a direction opposite to the direction of the force applied 'by said force opposing means to opposing means to oppose the deflection of the perforate portion caused by the load of said pressure roll,

the axial spacing of said second bearing means relative to said first bearing means and said fixed support means being such that the rolls shall de-flex more than the shaft means for any given force applied by said force imposing means.

(References on following page) References Cited by the Examiner UNITED STATES PATENTS 4/1931 Berry 16 237 1 3/1943 Berry 162-371 5/ 1944 Goodwillie et a1 1 62-37 1 3/1958 Byrd 6 8256 Shapiro et a1 182 Moore 100-90 Justus 1'00155 Justus 100-155 LOUIS O. MAASSEL, Primary Examiner.

Claims

1. A ROLL ASSEMBLY FOR USE IN A SUCTION PRESS OR THE LIKE APPARATUS COMPRISING: A ROLL SHELL HAVING NORMALLY A STRAIGHT LINE CENTROIDAL AXIS THAT DEVELOPS NORMALLY A CENTRAL DEFLECTION IN RESPONSE TO A LOAD APPLIED TO THE SHELL, SHAFT MEANS FOR THE ROLL SHELL, FIXED SUPPORT MEANS FOR SUPPORTING SAID SHAFT MEANS AT THE ENDS THEREOF, FIRST BEARING MEANS MOUNTED ON SAID SHAFT MEANS INBOARD OF SAID FIXED SUPPORT MEANS AND ENGAGING SAID ROLL SHELL FOR NORMALLY MAINTAINING SAID SHAFT MEANS AND SAID ROLL SHELL IN COAXIALLY ALIGNED AND SPACED RELATION, SECOND BEARING MEANS MOUNTED ON SAID ROLL SHELL AT THE ENDS THEREOF FOR VERTICAL MOVEMENT RELATIVE TO SAID FIXED SUPPORT MEANS AND SITUATED BETWEEN SAID FIXED SUPPORT MEANS AND SAID FIRST BEARING MEANS, AND FORCE IMPOSING MEANS OPERATIVELY ENGAGING TO THE SECON BEARING MEANS FOR APPLYING A FORCE TO THE ENDS OF SAID ROLL SHELL TO ACT AGAINST RESTRAINT PROVIDED BY SAID FIRST BEARING MEANS TO PROVIDE COUNTER DEFLECTION OF SAID ROLL IN OPPOSITION TO THE DEFLECTION CAUSED BY A LOAD APPLIED THERETO.