US3204552A

US3204552A - Calender loading mechanism

Info

Publication number: US3204552A
Application number: US304106A
Authority: US
Inventors: Edward D Beachler; Elmer E Crist
Original assignee: Beloit Corp
Current assignee: Beloit Corp
Priority date: 1963-08-23
Filing date: 1963-08-23
Publication date: 1965-09-07
Anticipated expiration: 1982-09-07

Description

Sept. 7, 1965 D. BEACHLER ETAL 3,204,552

CALENDER LOADING MECHANISM Filed Aug. 25, 1963 5 Sheets-Sheet 1 SPt 7, 1965 E. D. BEACHLER ETAL 3,204,552

CLENDER LOADING MECHANISM 3 Sheets-Sheet 2 Filed Aug. 23, 1963 INV ENTORS Edward D. Beach/ef /vmefczjz kw-Q a/@ATTORNEYS Sept 7, 1965 E. D. BEACHLER ETAL 3,204,552

CALENDER LOADING MECHANISM Filed Aug. 23, 1965 3 Sheets-Sheet 5 A j!! l 1 INVENTORS Zdzaa'. eafcl; er Time/E Clif/)5% United States Patent Office 3,204,552 Patented Sept. '7, 1965 3,204,552 CALENDER LOADING MECHANISM Edward D. Beachler and Elmer E. Crist, Beloit, Wis.,

assignors to Beloit Corporation, Beloit, Wis., a corporation of Wisconsin Filed Aug. 23, 1963, Ser. No. 304,106 8 Claims. (Cl. 100-170) This invention relates to improvements in paper making machines and more particularly relates to that portion of the paper making machine known as the calender stack.

In calenders or calender stacks for calendering paper and the like, the bottom roll of the stack is mounted on a base and rotates about a lixed horizontal axis and forms the support for a plurality of superposed rolls extending thereabove. In such calender stacks, the pressure between.

the nips of the rolls is determined by the weight of the individual rolls resting on the bottom roll, together with the weight of the bearings and bearing supports therefor. The pressure, therefore, is the greatest at the nip between the bottom calender roll and bottom roll of the calender stack and the pressure increases progressively from the top to the bottom of the stack. Due to this heavy pressure on the bottom roll it is usually necessary to crown the bottom roll to compensate for downward detlection of the roll by the weight of the superposed calender rolls resting thereon. The crown increases the diameter of the bottom roll at its center. The crowning of a bottom roll adds to the expense of the calender stack.

Also, it many times is desirable to have a uniform nip pressure between each roll and to increase or decrease the pressure of calendering in accordance with the grade of paper being calendered. This is not possible where the nip pressures are determined by the Weight of the rolls on the bottom roll, and while uid pressure means have been provided to relieve the rolls from the weight of the bearings, such iluid pressure means is not effective to distribute the load across the rolls, and therefore does not eliminate the need for crowning at least the bottom roll of the calender stack.

The principal object of the present invention is to provide an improved form of calender stack in which the top roll of the calender stack is uniformly loaded at selected pressures, and in which the loading of the top roll and the pressure between the nips of the rolls may be varied over a wide range.

Another object of the invention is to provide a novel calender stack in which pressure may be applied to the rolls of the stack to load the rolls in such a manner as to avoid the necessity of crowning the rolls.

A further object of the invention is to improve upon the loading of the rolls of a calender stack by uniformly loading the top roll of the stack at loads determined by the calendering requirements.

A further object of the invention is to provide a simplied and improved system for controlling the pressure between two or more rolls of a calender stack permitting a wide range of unit pressure between the rolls, Without changing the roll shape.

Still another object of the invention is to provide a system for controlling the pressure between two or more rolls of a calender stack by uniformly loading the top roll of the stack and relieving the rolls of the stack of the weight of the bearings and supports to the extent necessary to provide the required pressure nips between the rolls of the stack.

These and other objects of the invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings where- FIGURE 1 is a diagrammatic view in side elevation of a calender stack constructed in accordance with the principles of the present invention;

FIGURE 2 is a diagrammatic front end view of a calender stack shown in FIGURE 1;

FIGURE 3 is an enlarged partial fragmentary side elevational view with parts in section in order to show certain details of a modified form of support for the loading means for the top roll of the calender stack; and

FIGURE 4 is a fragmentary side elevational view of a portion of a calender stack illustrating still another form in which the invention may be embodied.

In the embodiment of the invention illustrated in the drawings, I have shown in FIGURES l and 2 a calender stack 10 comprising a pair of parallel spaced upright columns 11, suitably connected in parallel spaced relation with respect to each other. The columns 11 may be hollow columns and extend upwardly from a base 12 extending in advance of said columns. The base 12 has bearing supports 13, 13 extending upwardly therefrom, forming bearing supports for a bottom or king roll 15. Extending above the bottom roll 15 and supported on said roll is a series of superposed

calender rolls

16, 16 extending upwardly therefrom and in alignment therewith, to provide a series of pressure nips between said calender rolls and in nip defining relation with respect to the bottom roll 15.

The bottom roll may have a cylindrical face ground straight for economy and accuracy in finishing the roll. The calender rolls 16 may also have straight cylindrical faces. The bottom roll 15 may be driven from a suitable source of power in a conventional manner (not shown) and may have a plated surface, plated with chrome or nickel, to provide a highly polished surface where the calender is used for glossing treatment. The

superposed rolls

16, 16 are driven by contact with a web W and the bottom roll 15, although they may be positively driven, if desired.

The

rolls

16, 16 Iare of a similar construction and are each mounted on the columns 12, '12 in a similar manner 'so the mounting for one roll only need herein be shown rand described in detail.

Each roll 16 is journalled at its opposite ends in bearing

housings

17, 17 mounted on the -outer ends of pressure relieving arms 19, 19. The pressure relieving arms 19, 19 extend through the column beyond the rear end thereof and are transversely pivoted to said column on pivot pins 22 journalled at their opposite ends in bearing brackets 21, 21 extending along opposite sides of said arms and mounted on and projecting forwardly from the front faces of the columns 11. The pressure relieving arms 19 have rear end portions extending rearwardly of the columns 11 having iluid pressure diaphragms 23 mounted thereon. The diaphragms 23 are interposed be- ,tween the projecting ends of the pressure relieving arms 19 and the horizontal legs of angle brackets 24 secured to the rear faces of the columns 11 on their vertical legs.

The diaphragms 23 may 'be air operated diaphragms of a conventional form and serve to lift the bearing housings 17 about the .axes of the pivot pins 20 upon the application of fluid under pressure to said di-aphragms. The diaphragms may thus relieve a part of the load between the nips -of the calender r-olls relieving said rolls and the bottom roll 15, of a part of the weight of the bearing

housings

17, 17, the bearings carried by said housings and the pressure relieving levers 19 supporting said bearings. Suitable valve means '(not shown) may be provided to admit air to the various diaphragms 23 independently of each other as selected by the operator in accordance with calendering requirements.

A suitable lifting means (not shown) may also be provided to lift the calender rolls out of engagement with each other at the termination of a calendering operation.

Said lifting means may be of a conventional form so as not herein shown or described.

Referring now in particular to the means for loading the -top roll vof the calender stack and permitting a Wide range of unit pressures in the nips between the rolls of the stack, a plurality of uniformly spaced loading rolls 25 are provided to engage the top roll 16 of the calender stack. As shown in FIGURES 2 and 4 the loading rolls 25 are each journalled on a horizontal shaft 26 through suitable bearing means (not shown). Each transverse shaft 26 is mounted at its opposite ends in lever arms 27, transversely pivoted to brackets 29 depending from -a beam 30 extending between the columns 11 and suit-ably mounted on the forward end portions thereof.

The beam 30 is shown as being an I-beam, transversely pivoted to supports 31, extending angularly upwardly and forwardly of plates 32 extending across the

columns

11, 11 and welded or otherwise secured thereto. The supports 31 extend along opposite sides of brackets 33, secured to the top surface of the I-beam 30 and extending upwardly and angularly inwardly therefrom. Pivot pins 35 are provided to pivotally mount the brackets 33 to the supports 31.

A means is provided to move the beam 30 and the loading rolls 25 out of the way -of the top calender roll 16 when desired, as at the termination of a calendering operation, which is herein shown :as being a fluid pressure cylinder 36 having a piston rod 37 extensible therefrom. As shown in FIGURE 2 the front end of the piston rod is in the form of a yoke extending along opposite sides of an arm 39 depending from the lower web of the I-beam 30, and pivotally connected thereto -as by a pivot pin 40. The head end of the cylinder is pivotally connected to a bra-cket 43 extending rearwardly of the column 11 on ra pivot pin 44. A cylinder and piston may be mounted on each column 11, to raise the beam 30 about the axes of the pivot pins 35, and to raise the loading rolls 25 above the Itop calender roll 16 and to accommodate the beam 30 to move to a lowermost position and rest against the plate 32 during operation of the calender, and loading of the top calender roll 16 by the loading rolls, 25.

The loading rolls 25 are moved about the axes of the pivot pins 28 to load the .upper calender roll 16 by operation of fluid pressure operated diaphragms 45. The diaphragms 45 are suitably mounted between the vertical leg of the I-beam 31D and pressure plates 47 on the upper ends of lever arms 48, extending upwardly of the arms 27, and shown as being formed integrally therewith.

As shown in lFIGURES l `and 2 a diaphragm 45 and lever -arm 48 is provided for each end of each transverse shaft 26, to move the loading rolls 25 downwardly against the top roll 16 of the calender stack under pressure, which may be selected at the will of the operator of the calender stack, in accordance with the requirements for loading the rolls of the calender stack. A suitable valve means (not shown) may be provided to admit air to and release air from the diaphragms 45 and to hold air therein at the required pressure. The valve means may be of any well known forrn and is no part of the present invention so need not herein be shown or described.

It may be seen from -FIGURES l and 2 that during operation of the calender lstack, a specific pressure at the nip A between the lower calender roll 16 and the bottom roll of the stack, will tend to deflect the-bottom roll downwardly. The upward forces yF on each .bearing housing 17 will cause the roll 16 to deflect downwardly to the exact shape of the bottom roll. The necessary equal loading forces on -the rolls are applied by the loading rolls -at L to give a specific nip pressure at A.

The nip load at A is, therefore, the sum of the L forces plus the weight of the rolls above A, minus the sum of the F forces, which depend upon the pressure relieving forces exerted by the diaphragms 23.

Equal pressures in the nips between the rolls can be attained under the control of the diaphragms 23 and the 4 diaphragms 45 by applying pressure to said diaphragms to the extent that the sum of the F forces will equal the weight of all of the rolls of A, in which case the diaphragms 45 will apply all of the pressure at L and the sum of the pressures of each of the nips will equal the sum of the L forces.

Inl FIGURE 3 we have shown a modified form of structure for supporting a series of loading rolls 50 in association with a top calender roll 51 of a calender stack, one loading roll only being shown herein in the interest of simplicity.

In this form of the invention the calender stack is of a conventional form and may be somewhat similar to the calender stack illustrated in Patent No. 2,850,952 which issued to Lloyd Hornbostel on September 9, 1958, and includes a series of calender rolls 51 spaced forwardly of spaced posts 53 of the calender frame and transversely pivoted thereto on lift arms 55 carrying bearing supports 56, for the associated calender roll. Each lift arm 55 may extend along its associated post and be lifted to lift the weight of the bearing supports and bearings carried thereby from the individual rolls about the axes of pivot pins 58.

The bearing supports 56 have arms 59 extending upwardly and forwardly of the forward end portions thereof and connected with a suitable lifting mechanism (not shown) for lifting the calender rolls out of engagement with each other at the termination of a calendering operation.

The loading rolls 5t? are supported on a beam 60 extending across the calender stack and transversely pivoted to the posts 53 on pivot pins 61. The pivot pins 61 are each mounted in a boss 62 extending forwardly of a plate 63, mounted on the forward end portion of each post 53. Each pivot pin 61 extends through a yoke 64 extending rearwardly of the lower end portion of the beam 60 along opposite sides of the associated boss 62.

The beam 60 is of a fabricated structure having a hollow beam member 65 extending along the top of a shelf 66 and having a rear depending leg portion 67, from which the yokes 64 extend.

The beam 60 is held in position and pivoted upwardly about the axis of the pivot pin 61 by cylinders 69 having pistons (not shown) therein and piston rods 70 extensible therefrom. A cylinder 69 is at each end of the calender st acl; 1and is mounted on each post 53 on a transverse pivot pm Each piston rod 70 has a connector 73 at its outer end extending between a pair of spaced links 74, and pivotally connected thereto on a pivot pin 75.

The links 74 are connected at their lower ends to an upright ear 76 on the outer end portion of the beam 60, beneath the shelf 66. The opposite ends of the links 74 extend along opposite sides of a pivoted connector ear 77 and are connected thereto as by a pivot pin 7S. The connector ear extends between a pair of spaced connectors 79, spaced above the ends of the links 74 and is pivotally connected to said connectors on a pivot pin 80. Downward pivotal movement of the ear 77 is limited by a flat face 81 of the connector ear 77 engageable with the front face of the plate 63. Thus as fluid under pressure, such as air, is admitted to the head end of the cylinder 69, the links 74 will pivot the ears 77 about the pivot pins and pivot the beam 60 about the axis of the pivot pins 61 and thereby raise the loading rolls 50 out of engagement with the top calender roll 51.

Each loading roll 50 is journalled between arms 83 of a yoke 85 on a transverse shaft 86, suitably mounted in said yoke at its ends.

Each yoke 85 is pivoted at its rear end to a connector 87 on a pivot pin 88. The connector 87 is mounted on the rear face of the leg 67 and depends therefrom.

Each loading roll is loaded, by a diaphragm (not shown) contained within a diaphragm casing 90, mounted on the top of the forward end portion of the shelf 66. A rod 91 depends from the casing 90 through and beneath the shelf 66 and has a yoke 93 secured to and depending from its lower end and extending along opposite sides of a connector 94 extending upwardly from the forward end portion of the yoke 85. A pivot pin 95 connects said yoke to said connector.

The rod 91 is secured to the diaphragm (not shown) within the casing 90 in a conventional manner to load the calender roll 51 upon the admission of fluid under pressure to said casing in the same manner, as in the form of the invention illustrated in FIGURES l and 2.

In the form of the invention illustrated in FIGURE 4, we have shown series of calender rolls 100 mounted on

posts

101, 101 of a calender frame on pressure relieving arms 102, in the same manner the calender rolls 16 are mounted on the posts 12. The mounting for said rolls, therefore, need not herein be described further.

The top calender roll is engaged by a series of loading rolls 103, 103 circumferentially spaced to opposite sides of a vertical diametral line extending through the center of said roll, and uniformly spaced along the surface of said roll.

The loading rolls 103, 103 are journalled on

shafts

104, 104 mounted at their ends between the furcations of bifurcated arms of

lever arms

105, 105. The

lever arms

105, 105 are in the general form of bell-cranks and are `pivoted intermediate their ends on a common pivot pin 106 mounted in a bracket 107 depending from a beam 109.

The beam 109 extends across the calender frame and is mounted thereon to be raised above the top calender roll 100 on transversely pivoted

support brackets

110, 110 pivotally mounted at their upper ends on pivot pins 111 mounted on support ears 112, extending forwardly of said posts.

Each bracket 110 has a depending arm 113 abutting the front face of the associated post 101, when the loading rolls 103, 103 are in the position shown in FIGURE 4. A fluid pressure cylinder 115 having a piston rod 116 extensible therefrom is mounted on each post 101, to pivot the associated bracket upwardly about the axis of the pivot pins 111. Each piston rod is pivoted to the lower end portion of the associated depending arm 13 on a pivot'pin 117.

The loading rolls 103, 103 are loaded by

iiuid pressure diaphragms

119, 119 which may be in the form of airV springs of a conventional construction. As herein shown the

diaphragms

119, 119 are interposed between abutment faces 121, 121 on the beam 109 and abutment faces 122, 122 on

arms

123, 123 of the

lever arms

105, 105. The admission of fluid under pressure, such as air to the

diaphragms

119, 119 will engage the loading rolls 103, 103 with the periphery of the top calender roll 100 on opposite sides of a vertical axis extending through the center of said roll and exert radial pressure thereon along lines intersecting the center of said roll in accordance with the pressure of air in said diaphragms. This form of the invention is particularly adapted to installations where it is necessary to stabilize the top roll and resist vibration thereof.

It may be seen from the foregoing that we have provided a novel form of variable nip pressure systems for paper calenders in which the pressure at the n'p between the bottom calender roll and the bottom roll of a calender stack may be governed by uniformly loading the top roll of the calender stack and in which the pressure between the nips of the calender stack may be made equal by cooperation of the load relieving diaphragms with the loading rollers, loading the top roll of the calender stack.

It may further be seen that with the pressure system of the present invention, the rolls may all be ground straight, resulting in a more economical and accurate calender stack and the exacting nip pressure required for calendering may be finely controlled by the cooperation of the load relieving diaphrgam with the loading diaphragm.

While We have herein shown and described one form in which our invention may be embodied, it may readily be understood that various variations and modifications in the invention may be attained without departing from the spirit and scope of the novel concepts thereof, as defined by the claims appended hereto.

We claim as our invention:

1. 1n a paper machine, a multi-nip calender comprising a calender frame, a bottom roll rotatably journalled in said frame for movement about a horizontal stationary axis, a stack of calender rolls supported on said bottom roll and movably supported in said frame, separate and independent bearings supporting said calender rolls, individual lift levers supporting said bearings and transversely pivoted to said frame for movement about axes parallel to the axes of rotation of said rolls, iluid pressure means exerting pressure on said pressure relieving levers in a direction to relieve said rolls from the weight of said levers and the supporting bearings for the associated rolls, a series of loading rolls engaging the top roll of the stack of rolls at equally spaced points therealong, individual fluid operated members exerting pressure on said loading rolls to produce a desired nip pressure in the nip between said bottom roll and the lowermost roll of said stack of rolls, and a beam means supporting all of said loading rolls and vertically movable relative to the calender frame for simultaneously elevating all of said loading rolls facilitating threading between the rolls.

2. A calender stack comprising a frame, a bottom roll rotatably journalled in said frame, a stack of calender rolls supported on said bottom roll and supported on said frame for vertical movement with respect to each other, and including a top roll, a beam extending across said frame above said top roll, means transversely pivoting said beam to said frame, other means raising and lowering said beam, a plurality of loading rolls supported on said beam for vertical movement with respect thereto and for engagement with said top roll and being simultaneously raised with said beam to facilitate threading a web between the calender rolls, and uid pressure operated -means for loading said loading rolls.

3. A calender stack comprising a frame, a bottom roll rotatably journalled in said frame for rotation about a stationary horizontal axis, a stack of calender rolls supported on said bottom roll and supported on said frame for vertical movement With respect thereto and including a top roll, laterally spaced arms transversely pivoted to said frame, each pair of arms supporting a calender roll therebetween, uid pressure operated means moving said arms in a direction to relieve said rolls from the weight of said bearings and the supports therefor, a transverse beam extending across said frame above said top roll, means transversely pivoting said beam to said frame, fluid pressure means holding said beam in position and moving said beam vertically with respect to said top roll, a plurality of loading rolls mounted on said beam for vertical movement with respect thereto, and fluid pressure means disposed between said beam and loading rolls and exerting pressure on said loading rolls to load said top roll at a pre-selected pressure.

4. A calender stack comprising a frame, a bottom roll rotatably journalled in said frame, a stack of calender rolls supported on said bottom roll and including a top roll, separate bearings for supporting opposite ends of said calender rolls, individual load relieving levers transversely pivoted to said frame and supporting each bearing, pressure operated means for exerting pressure on said pressure relieving levers to relieve the calender rolls from the Weight of said bearings and supports therefor, a plurality of loading rolls engaging and loading said top calender roll, means supporting said loading rolls comprising a beam extending across said frame above the top roll of the stack of rolls, means transversely pivoting said beam to said frame, other means raising said beam with respect to said frame and top calender roll, to raise said loading rolls above said top calender roll, a series of arms transversely pivoted to said beam about coaxial axes and forming bearing supports for said loading rolls, said arms having upright arms extending upwardly therefrom., and fluid pressure operated diaphragms interposed between said beam and said upright arms for exerting pressure on said loading rolls and loading said top calender roll to provide pre-selected nip pressures between said rolls in cooperation with said lift arms 5. A calender stack comprising a frame, a bottom roll rotatably journalled in said frame, a stack of calender rolls supported on said bottom roll and including a top roll, separate bearings for supporting opposite ends of said calender rolls, individual load relieving levers transversely pivoted to said frame and supporting each bearing, pressure operated means for exerting pressure on said pressure relieving levers to relieve the calender rolls from the weight of said bearings and supports therefor, a plurality of loading rolls engaging and loading said top calender roll, means supporting said loading rolls comprising a beam extending across said frame above the top roll of the stack of rolls, means transversely pivoting said beam to said frame, linkage means connected between said frame and beam and holding said beam and loading rolls in operative association with the top roll of the stack of calender rolls, uid pressure cylinder and piston means connected between said frame and links for raising said beam and loading rolls with respect to the top roll, a series of yokes transversely pivoted to said frame and extending forwardly therefrom, each yoke forming a support for a loading roll, and an individual diaphragm for each loading roll mounted on said beam in advance of said loading roll, and a separate pressure rod connecting each diaphragm to each yoke.

6. In a paper machine, a multinip calender comprising a calender frame, a bottom roll rotatably journalled in said frame for movement about a horizontal stationary axis, a stack of calender rolls supported on said bottom roll and movably supported `on said frame, separate and independent bearings supporting said calender rolls, individual lift levers supporting said bearings and transversely pivoted to said frame for movement about axes parallel to the axes of rotation of said rolls, uid pressure means exerting pressure on said pressure relieving levers in a direction to relieve said rolls from the Weight of said levers and the supporting bearings for the associated rolls, a series `of loading rollsengaging the top roll of the stack of rolls at equally spaced points therealong and at opposite sides of a vertical line intersecting the rotational axis of said roll, individual fluid pressure operated diaphragms loading said loading rolls to apply preselected radial forces on the top surface of the top roll on opposite sides of a vertical line intersecting the axis of rotation of said roll, to produce a desired nip pressure in the nip between said bottom roll and the lowermost roll of said stack of rolls, and a beam means supporting said loading rolls and vertically movable relative to the calender frame for elevating all of the loading rolls to facilitate threading a web between the calender rolls.

7. A calender stack comprising a frame, a bottom roll rotatably journalled in said frame, a stack of calender rolls supported on said bottom roll and supported on said frame for vertical movement with respect to each other, and including a top roll, a beam extending across said frame above said top roll, means transversely pivoting said beam to said frame, fluid pressure operated means holding said beam in position and moving said beam vertically with respect to said top roll, the support for said loading rolls on said beam comprising a series of laterally spaced brackets depending from said beam, a pair of lever arms pivoted to each bracket for movement about an axis intersecting a vertical line extending through the axis of rotation of said top calender roll, loading rolls journalled on said lever arms for engagement with said top calender roll on each side of said vertical line, and fluid pressure operated diaphragms interposed between said beam and said lever arms for loading said lever arms to radially load said top roll on opposite sides of the axis of rotation thereof.

8. A calender stack comprising a frame, a stack of calender rolls supported on said frame for Vertical movement with respect thereto and including a top roll, laterally spaced arm-s transversely pivoted to said frame, each pair of arms supporting a calender roll therebetween, iluid pressure operated means moving said arms in a direction to relieve said rolls from the weight of said bearings and the supports therefor, a transverse beam extending across said frame above said top roll, means supporting said beam on said frame accommodating relative vertical movement, uid pressure means holding said beam in position and moving said beam vertically with respect to said top roll, a plurality of loading rolls mounted on said beam for vertical movement with respect thereto, and uid pressure means disposed between said beam and loading rolls and exerting pressure on said loading rolls to load said top roll at a preselected pressure.

References Cited by the Examiner UNITED STATES PATENTS 864,660 8/07 Love 100-160 2,718,827 9/55 Whittum 10D-160 2,850,952 9/58 Hornbostel 100-163 2,851,869 9/58- Quoos et al. 100-160 X 3,060,843 10/62 Moore et al 100-170 X FOREIGN PATENTS 152,232 2/62 Russia.

WALTER A. SCHEEL, Primary Examiner. LOUIS O. MAASELL, Examiner.

Claims

2. A CALENDER STACK COMPRISING A FRAME, A BOTTOM ROLL ROTATABLY JOURNALLED IN SAID FRAME, A STACK OF CALENDER ROLLS SUPPORTED ON SAID BOTTOM ROLL AND SUPPORTED ON SAID FRAME FOPR VERTICAL MOVEMENT WITH RESPECT TO EACH OTHER, AND INCLUDING A TOP ROLL, A BEAM EXTENDING ACROSS SAID FRAME ABOVE SAID TOP ROLL, MEANS TRANSVERSELY PIVOTING SAID BEAM TO SAID FRAME, OTHER MEANS RAISING AND LOWERING SAID BEAM, A PLURALITY OF LOADING ROLLS SUPPORTED ON SAID BEAM FOR VERTICAL MOVEMENT WITH RESPECT THERETO AND FOR ENGAGEMENT WITH SAID TOP ROLL AND BEING SIMULTANEOUSLY RAISED WITH SAID BEAM TO FACILITATE THREADING A