US2544557A - Oscillating doctor for paper machines - Google Patents

Description

March 6, 1951 w. LYON OSCILLATING DOCTOR FOR PAPER MACHINE 4 Sheets-Sheet 1 Filed Aug. 27, 1947 TJi/lzl 0m Lyon,

INVENTOR.

BY fi March 6, 1951 w LYON 2,544,557

OSCILLATING DOCTOR FOR PAPER MACHINE Filed Aug. 27; 1947 4 Sheets-Sheet 2 William Lyon IN VEN TOR.

March 6, 1951 w, LYON I 2,544,557

OSCILLATING DOCTOR FOR PAPER MACHINE Filed Aug. 27, 1947 4 Sheets-Sheet 3 William Lyon,

IN VENTOR.

March 6, 1951 w. LYON OSCILLATING DOCTOR FOR PAPER MACHINE 4 Sheets-Sheet 4 Filed Aug. 2'7. 1947 ZJZl/L'Gm Lyon,

INVENTOR.

Patented Mar. 6, i951 UNITED STATES PATENT 'OEF Fl CE 2,544,557 SCILLATING'DOCTQR'FORPAPER FMACHINES f William Lyon, -Prestwich, near :Manchester, England, :assignor to :Messrs. -Walmsleys '(Bury) ...Ltd., .Bury,.England, a British company Application August 27, 1947,"Serial-'No. 770,807 In Great Britain March 1, 1945 9 Claims. (Cl. 927.4)

Thisinvention relates to-paper machinery, and

more 'particularlyto. arrangements for control- 'ling the doctor bladeorblades used on the rolls of such machinery.

The art has long recognized the advisability of reciprocating ea-doctor blade :to avoid localized wear between the blade and the roll. Where this has been accomplished by gearing,- the mechanism 'is cumbersome -and-/interferes-with general servicing of the roll. IMOIGOVBI', positivetgearing between the roll and the reciprocating .mechanism for the ,doctor'maintains acyclic fixedrelationship between the blade and the roll surface resulting in a'localized wear pattern between the blade and the roll. The prior-art has pro- ;posed hydraulic actuation as a means of over,-

coming the difiiculties occasioned zby the useof gears but all such arrangements have necessitated very substantial modification of the doctor blade supports. Such modificationsare often in conflict with the intended application of the doctor, since the design .of the doctor blade support is dictatedbythetype .of roll to which the doctor is applied. For example, a .doctor .blade support which would serve. excellently well on a .top pressrollis completely unsuitedto operating on .a breast roll. The present invention there- .fore contemplates .a hydraulic actuating means which can beadapted to various .doctor blades with a minimum of modification in the design. Modern highspeed paper making machines are already of great length, notwithstanding .the fact that the amountofspac'e allowedfor theoperators to-obtain access to the various parts of the machine has been cut down to the minimum.

Existing mechanical oscillating gear cannot be applied to many of 'the places where it isdesirable to oscillate the mechanism without interfering with the operation of .the paper machine, or

alternatively making its operation dangerousfor the operators.

In the case of new machines, the designersare very reluctant to extend the length vof the machine merely to provide facilities forfitting oscillators. vIt is therefore an additional object to provide anoscillating mechanism whichmay be applied either to existing equipments or to those newly manufactured, without interfering with space requirements, and which will have a minimum of exposed parts so as to minimize the'risk of injury to the operators.

Since reciprocation of .the doctor blade during "periods when the troll is :at rest-would -.also -pro- .=duce excessive local wear,--it is ;a. further object around the breast 'roll as shownat I6. .observedfrom'Figs. 1' and 2 that the reflective width of breast roll H5 is sonearly equaltothe space between .the main side supports and 1 2 thereis little orno space between'either of the to provide an arrangement .for discontinuing reciprocation during "such'periods.

Still :anotherobject is to provide such aldevice which is of simple, dependable and ruggedwon- :struction, and .which can .be manufacturedand installed at a :cost which .is low considering the objects .to be satisfied.

The above and other objectsand advantages of the invention will best be understood byrcfer- .ence to the following detailed specification. of the invention,- reference 'being had .to .the accomqpanying drawings, in which:

Fig. '1 is asectional elevation ota typicallpaper :machine showing the application of.theimproved doctorarrangement to the .breast roll,

Fig. 2 isra plan view of the same,

Fig-3 is a sectional view taken ontheflinet- -t *Fig. A is an enlarged -view.-of the v.rightehand .portion of Fig. 1, parts being'broken away..-for

clarity of illustration,

Fig. 5 is a'fragmenta'ryrsectional viewtaken .Fig; 6 isuarplanview ofthe application .of the invention .to .an .upper press :roll 0f agpaper machine,

Fig. '7 is a side view of the same,

Fig. 8 is. a longitudinal sectional view .of :the self-reversing hydraulic/motor employed in. connection with the invention,

Fig-9 is a plan view of .saidmotonand Fig. 10 is a diagrammatic view 1 of an arrange- 'ment .for'interrupting the oscillation whenever the associated. roll is stationary.

Referring'now to Figs. 1 to 3 ofthe drawings, numerals -l0 and L2 designate respectively the side frame-members of a typical form of .F'ourdrinier machine, between which :is ;.;journailed the breast roll l4,-by means :of -:journals (not shown). The 'wire of the machine passes :It: will be adjacent its opposite ends to.stub shafts 26rand 23 :each of which .is .rotatably received in asbearing block of square cross-section. Bearing block 36 at the left end of the doctor support (looking at Figs. 1 and 2) is slidably received within an upwardly open square pocket 32 of a support bracket 34 bolted to frame member It), so that block 38 is held against rotation within said pocket but is freely slidable therein to a limited extent. Anti-friction bearings such as rollers 36 (Fig. 2) may be interposed between block 36 and the bottom of pocket 32 to facilitate this sliding movement. A shoulder bolt 38 secures the end of stub shaft 26 to the end of block 36 so that the latter is carried with the stub shaft during reciprocation, but permitting free rotative movement of these parts relative to one another.

At the right end of the doctor support beam (see Fig. 4) a portion 49 of such beam is cut away to provide space for a bearing similar to that just described, as well as for the installation of the reciprocating motor to be described below. More specifically, stub shaft 28 at this end of the doctor is provided with an end portion 42 of reduced diameter rotatably received within the cylindrical bore of a bearing block 44 whose outer profile is square (see Fig. so as to slide within the upwardly open box support 46 of a support bracket 48 bolted or otherwise secured to frame member l2. As in the case of the bearing at the opposite side of the machine, a shoulder bolt 56 passes freely through an aperture in the end of block 44 and is threaded into shaft 28, a slight clearance being provided between the end of this shaft and the inner end wall of the block to permit free rotation of shaft 28 therein. Anti-friction rollers 52 support the block 44 upon the bottom wall of the box 46. Thus, the bearing blocks, the doctor blade support beam, the blade support and the blade may be reciprocated freely as a unit laterally of the machine, while the support beam and parts carried thereby may additionally be rotated to a limited extent to enable the blade to be withdrawn from the surface of roll l4. Moreover, the upwardly-open box- like support 32 and 46 permit the entire doctor assembly to be lifted out and replaced in the identical position with respect to the roll [4.

-The manner in which the doctor support is periodically and automatically reciprocated across the face of roll M will now be described, it being understood that the purpose of such reciprocation is to prevent the formation of localized ridges or imperfections in either the roll or the doctor blade, as might occur if the same point on the doctor were continuously in contact with the same zone of the roll, or if a cyclic relation existed between roll and blade. Stub shaft 28 is provided with an annular groove 54 which receives an upwardly open crosshead 56 (Fig. 4) provided with laterally extending ears to which are secured as by nut 58 the ends of a pair of drive rods 68 extending inside the hydraulic motor 62, and which may receive sliding support from a pair of laterally extending ears 54 (Fig. 5) preferably integral with the square 'box structure 46. Since drive rods 60 are spaced equally on opposite sides of the stub shaft 28, it is clear that a reciprocation of such rods by the motor 62 will cause the entire doctor support structure to slide easily back and forth across the face of roll I4 Without binding, and that the doctor blade itself is free to rotate to a limited extent in its axial bearings, either to accommodate for slight eccentricities in the roll M, or to enable the blade to be withdrawn from the surface of the roll for changing or for other reasons.

Additionally, it will be observed that since the square bearing blocks 36 and 44 are received within upwardly open box formations 32 and 46, and cross-head 56 passes beneath the stub shaft 28, the entire doctor structure, including bearing blocks 36 and 44, can easily be lifted away from its support and drive means when such operation is necessary, without in any way disturbing the bolted support brackets or the drive motor mounting, or the angular relation between the roll surface and the doctor blade when the parts are replaced. This is a very valuable feature particularly when it is necessary to change the clothing on the machine; for example, the Fourdrinier wire carried by a breast roll.

Figs. 6 and '7 illustrate the application of the improved form of doctor drive as applied to a double doctor arrangement for use on a top press roll. Since the arrangements for the two doctors are duplicates of one another, only that for the lower of the pair (as seen in Fig. '7) will be described in detail. The top press roll is indicated by numeral 64, and is supported as by bearings 66 and 68 mounted upon the opposite machine frames, one of which is shown at 10, in the usual pivoted journal frames or supports 14 (Fig. 7), whose purpose is to permit a limited swinging of the press roll 64 about the axle 16, thereby to press against the lower roll 18 (or upon an interposed felt) with a regulated pressure.

Hydraulically reciprocating drive motor for the lower doctor assembly is bolted to swinging journal frame 14 as by support bolts 82. The operating rods 84 of the motor, two in number, are here again spaced equally on opposite sides of the doctor operating shaft 86, and connected thereto by a cross-head 88. Unlike the previous embodiment, however, the combination of sliding. and rotating movement of the doctor is achieved by journalling the same as at 96 within opposed cylindrical pockets 92 and 94 secured to the support frames, said pockets being sufficiently deep to accommodate a limited amount of sidewise reciprocation of the doctor assembly. The operating shaft 86 passes from the crosshead 88 through an aperture in frame member 14.

The above arrangement is duplicated for the upper doctor assembly, except that in this case the motor and doctor supports are mounted upon a pair of pillow blocks 96 and 98 respectively secured as by keyways upon the upper surfaces of the swinging journal frames, bolsters I00 and H12 providing the necessary bearing support for the doctor assembly and for the hydraulic motor. Since it is obviously impossible with this arrangement to lift the entire doctor assembly bodily out of its mounting, as was done in the previously described arrangement, the doctor blades and their supports are here shown as secured bolted brackets such as indicated at I84 (Fig. 6), which enable the doctor support to be removed bodily when occasion requires. However, these doctors, like those previously described, are capable of the free swinging movement toward and away from press roll '64 by virtue of the cross-head connections between the doctor operating shafts and the respective hydraulic motors.

In accordance with the invention, a specialized form of hydraulic reciprocating drive motor is provided to causethe diesired'l'slatcralitraverse of the doctor, blade support.

As best shown in "Figs. v8;and:.9,: thedoctor is connected to .a cross-head I06 secured 'around central shaft I.08.carrying at. its outer ends hydraulic pistons IIO, .I I2. These pistons are provided'with ,cup leathers .I I4 and are adaptedto oscillate ina pairof cylinders I I6, .8 having inlet passages I20, I22, respectively, .at their ends connected oneatzatime itoa valvechamber I24 in which oscillates an; automatic :shuttle :element I26 controlling-the passage of. pressure liquid from an inlet I28'to passages I20, I22,;alternately.

A passage I30 leads to exhaust or relief. The shuttle valve I26 is guided .byiforming'a recess I62 in it into which astoppin I34-engages.

This shuttle valve ifurther :has arecess I36 :in

communication alternately iwiththe passages I20 and I22.

In operation pressure liquid, preferably oil'under. pressure, is :passedfromthe inlet. I28to the recess I36 and thence to either cylinder H6, 8 through passage I20 or passage I22. In the position shown in Fig. 8, this pressure liquid can pass to passageway I22 in the cylinder block to displace the piston I I2 at the outer end of its stroke inwardly fromtheouten end of its cylinder, driving piston I I towards the outer end of itscylinder.

Liquid behind the piston I I0 can escape by passage I 20 into theVaIVe-chamber I24 and thence through outlet port I38 communicating with the exhaust I30.

As the piston I I2 subject to pressure from the passage I22, reaches its end position, a groove I40 in it communicating with an :axial passage I42 in the piston head, comes .intocoincidence with a groove I44 in the cylinder communicating with passage I46 leading to the space I48 behind the shuttle valve I26 thus flicking it across so that the pressure inlet I 28 now communicates through recess I 36 with the passage I20 causing the piston elements H0, H2, to move back in the opposite direction carrying with them the crosshead I06 attached to the doctor.

It is obvious that instead of forming the shuttle valve chamber I24 containing the shuttle valve I26 within a unitary casting containing the cylinders II6, I I8, this may if desired be formed as a separate unit connected with the passages I20, I22 and I46, I50 respectively by connection pipes.

Chamfers I52 are formed at the ends of the valve so that the valve faces controlling ports I54 and I56 of passages I20 and I22 are only very slightly wider (by a few thousandths of an inch) than the ports I54 and I56. The recess I36 is slightly longer than the shortest distance between the ports I54 and I56 so as to ensure that one port is slightly open to pressure liquid before the other finally closes during movement of the valve.

Thus during operation there will be little danger of the valve stopping in an intermediate position since although closure of the port I56 for example during movement of the valve from right to left will prevent any further feed of liquid through the port I56 and through passages I22 and I46 to the space I48, nevertheless the port I54 will by this time be open to pressure liquid so as to cause movement of the pistons H0 and H2 from left to right to cause displacement of liquid from the right hand end of the cylinder I I8, first through passages I42, I44 to space I48 and then through port I56 to space I48 whereby to ensure completion of the movement of the shuttle valve from'right to :left. :In this rconnectionfitristo'he noted that the righthand outlet port I39 does not open until after theport I56-hasopenedto continue through the passage I42 whose outlet in the cylinder H6 is notclosed until the piston I I0 approaches its mid stroke.

.It will be appreciated that the hydraulic oscillating gear-of the present inventioncan be built .compactly and'with .a minimum of exposed ;mov- .ing partsand that, in operation, the rate-of oscillation can be readily adjusted and that since the movement of the doctor dependsauponthe val- .umetic displacement (of the operating liquid -,fed

to .the pistons, a steadily progressive movement of thedoctor across the roll gislachieved.

A valuable feature of the operating gearof the present :invention is its reliability since stoppage of a doctor in a paper making machine is liable to give riseto considerable damage and expensive .repairsas well as loss of production.

In order to prevent the reciprocating motion of the doctor blade from occurring when the roll being doctored is at a standstill, which would tend to cause local wear upon the roll surface along atransverse line, the doctor motors .of any of the above arrangements may be provided with a control which is sensitive to the rotation of the breast or press roll. ,Asshown in Fig. '10, such a control may comprise any known orconvenient typeof hydraulic pump,.suchas-gear type pump I62 driven from the rollbeing doctored, either by a frictional contact wheel engaging the face or sideof the roll, or by pulley or gear drive, and

connected to supply pressurefiuidthrough a duct I64 from a sump I66 and to a valve generally designated by I68. This valve maypomprisea spool I10 shiftable against the pressure of a spring I12 to open the supply line I14 of main hydraulic fluid to the doctor motor 62, whenever the pressure of fluid from pump I62 exceeds a predetermined amount. A safety or relief valve I16 of conventional construction may be provided to pass excess oil pumped by pump I62 through a drain line I18 and back to sump I66. Thus whenever roll I4 (or any equivalent roll being doctored) comes to a standstill, the pressure in line I64 will drop to a point at which spring I12 will shift spool I10 to the right and close the supply line I14, causing a cessation of the reciprocatory movement of the doctor. Upon resumption of rotation of the roll I4, pump I62 will cause a build-up of pressure behind spool I10 sufficient to shift the spool to its Fig. 10 position, whereupon reciprocation of the doctor blade will again ensue.

It will be seen from the above specification that I have provided an apparatus satisfying all of the objects of my invention in a relatively simple and highly efficient manner, but obviously many changes and modifications may be made in the specific details of construction without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. Doctor blade mechanism comprising: a rigid doctor blade support; a pair of axially aligned stub shafts rigidly secured, one at each end of said support; a pair of integral bearing members each rotatably receiving and enclosing one of said stub shafts with an ordinary journal fit, said bearing members having polygonal exterior cross-section, and a pair of supports slidably receiving said bearing members, said supports comprising troughs conforming to the exterior cross-section of said bearing members, the upper sides of said troughs being open to permit removal of the bearing members therefrom.

2. Doctor blade mechanism according to claim 1 including means penetrating said stub shafts for securing said bearing members to said stub shafts against axial separation.

3. Doctor blade mechanism according to claim 1 in which one of said stub shafts has a circumferential groove adjacent the inner end of its bearing member; a cross-head having a semicircular cutaway portion in its upper side engaging said groove, and means for reciprocating said crosshead.

4. Doctor blade mechanism according to claim 3 includin means penetrating said stub shafts for securing said bearing members to said stub shafts against axial separation.

5. Doctor blade mechanism comprising: a rigid doctor blade support; a pair of axially aligned stub shafts rigidly secured at each end of said support; a bearing for each of said stub shafts, each of said bearings providing for simultaneous reciprocation and rotation of said stub shafts therein, a reciprocating hydraulic motor, and means including a connection acting in a plane containing the axis of said stub shafts for connecting said motor to one of said shafts to reciprocate said support, said connecting means being rotatably free of said stub shafts.

6. Doctor blade mechanism as set forth in claim 5 in which the hydraulic motor has at least one piston mounted coaxially with the stub shafts.

7. Doctor blade mechanism comprising: a roll to be doctored; a doctor blade support adjacent said roll; a hydraulic motor for reciprocating said support; a line supplying fluid to said motor;

a normally closed valve in said line; a pump driven by the rotation of said roll, and means connecting said pump to said valve for opening the same when the roll is rotated.

8. Doctor blade mechanism comprising a rigid doctor blade support, a pair of axially aligned stub shafts rigidly secured one at each end of said support, a pair of bearing members each rotatably receiving and enclosing one of said stub shafts, said bearing members having polygonal exterior cross-sections and a pair of supports slidably receiving said bearing members, said supports comprising open troughs conforming to the exterior cross-section of said bearing members, one of said stub shafts having a circumferential groove adjacent the inner end of its bearing member, a cross-head having a semicircular cut-away port-ion in its upper side engaging said groove and means for reciprocating said cross-head.

9. Doctor blade mechanism according to claim 8, including means for securing said bearing members to said stub shafts against axial separation.

WILLIAM LYON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,243,049 Dewey Oct. 16, 1917 1,312,009 Thrift Aug. 5, 1919 1,798,887 Kutter Mar. 31, 1931 2,417,796 Happ Mar. 18, 1947 FOREIGN PATENTS Number Country Date 588,998 Great Britain June 9, 1947

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