US2255951A - Paper machine - Google Patents

Description

Sept. 16, 1941. K. H. TOMTLUND PAPER MACHINE Filed Aug. so, 1959 2 sheets-sheet 1 Sept. 16, 1941. K. H. ToM'rLUND PAPER MACHINE Filed Aug. 30, 1939 2 sheets-she@ 1 Patented Sept. 16, 1941 UNITED STATES PATENT IOEI-*ICE 2,255,951 rArEn MacnnrEI Application August 30, 1939, Serial In Sweden August 31, 1 38 11 Claims.

It is well known that in paper-machines oi' which moves at a high rate of speed over the breast-roll, carrying along air from the angle or gap between the outlet nozzle and` the upward moving portion of the breast-roll, such air being then mixed with the pulp mixture which is delivered by the outlet nozzle to the wire-cloth.

In order to obviate this disadvantage it has been proposed to provide below the outlet nozzle and in front of the upward moving portion of the breast-roll covered by the wire-cloth, a closed chamber in which a reduced air pressure is maintained, and to allow the wire-cloth to pass vthrough the said chamber immediately before the wire-cloth arrives at the pulp outlet nozzle.

Such a chamber is an expensive structure,

- however, and it is often not possible-#or only after making considerable changes-to adapt the same to old machines. Furthermore, it is diillcult to eect the necessary tightness between the said chamber and the wire-cloth; since damage may easily be caused to the latter. Y

The present invention provides a considerably simpler solution of the problem.of preventing air bubbles from being formed in the 'manner above explained.

- The improvement according to the present invention is mainly characterized by the provision, in the angle' or gap between the outlet nozzle and the upward moving'portion of the breastroll covered by the wire-cloth,l and atthe upper boundary wall of said angle or gap, of a device by means of which-one or more jets of a gaseous or liquid medium of a pressure higher than the atmospheric pressure may be directed from the said boundary wall substantially tangentially to,

and in a dlrectio substantially opposite to theA direction of movement of, the upward moving portion of the wire-cloth, so that a screen or curtain of fluid pressure medium whichv shuts of! the gap from the outside/.is l:formed between the said boundary wall and the wire-cloth.

'I'he invention is illustrated in the accompanying drawing'which shows a few constructional 55 forms of apparatus according to the invention.v Fig. 1 shows a longitudinal section through the inlet end of a Fourdrinier machine, and Fig. 2 shows a vertical cross-section on the line II-II in Fig. 1.- Fig. 3 shows to a larger scale a crosssection of the supply pipe for pressure medium, and Fig. 4 shows another construction of the supply pipe. Fig. 5 shows a construction using a baille plate for spreading the jets of pressure medim,and Fig. 6 shows a construction having 4a movable baille plate. l

. Referring to Figs. 1 and 2, the pulp mixture iiows from a high-pressure breast-box I through an outlet nozzle 2 which extends across the entire width of the machine, out upon an endless wire-cloth 3 which runs over the breast-roll 4 which rotates at a high speed in the direction of the arrow 2|, the wire-cloth passing closely below the lower lip 5 of the outlet nozzle. The fibres settle on the Wire-cloth, while the water ilows through the wire-cloth and is led away.

Ordinarily, the wire-cloth would, oi course,

carry along air from the angle or gap 1 between the breast-roll and the bottom 6 of the outlet nozzle which gap is open towards the outer atmosphere, and into the narrow space 8 between the wire-cloth and the lower lip 5 of the outlet nozzle, and past the mouth of the nozzle, so that air would thus reach the lower side of the web of pulp delivered by the outlet to the upper side of the wire-cloth on the breast-roll. The air thus brought along would be forced upward in the web of pulp and cause the air bubbles previously mentioned. n l It is the object of the present invention to prevent air from being carried along in this manner and thus to prevent the formation of p air lbubbles in the web of pulp. For this purpose the two side Walls 9 of the breast-box are continued downwards and are so formed that they adhere to the curvature of the breast-roll. 'I'hese side walls may be provided with packing strips III forming interleaving seals with the wire-cloth on the lbreast-roll. According to theconstructional form here illustrated, there is provided.w in the bottom 6 of. -the outlet nozzle which forms the upper boundary wall of the said angle, a groove I6 which extends across the entire width of the machine, and in said groove there is pro-v vided a pipe I I for the supply of. a gaseous or liquid medium having 'a higher 'pressure than the atmospheric pressure, such as air under pressure, which is admitted at I2, and the supply of which may be regulated by any suitable means such as a. valve I3.

of pulp delivered Intermediate/the side walls 9 in which Ithe or more apertures Il, slots or in such manner that said air unvided with one holes, arranged a der pressure flowing out through said apertures l is directed substantially tangentially to the upward moving part rection substantially opposite to the direction of of the wire-cloth, and in a dimovement of the same. l

Said air owing out through the apertures in the pipe Il forms an air layer or a screen or cur--` tain of air, as it were, which closes the said angle or gap which is otherwise bounded by the side walls 9,' 9, the the wire-cloth 3 on the upward moving portion of the breast-roll l, and prevents the air outside said screen or curtain from by the wire-cloth. The yejector action set up by the air jet or gap on the inner side of the jets, also contributes to the air in the angle on the inner side of said air curtain tending to flow in the opposite direction to the wire-cloth, and also produces a pressure drop in the said portion of the gapl and thus also in 'the abovementioned space 8, which obviouslyv results in that no air bubbles can penetrate from the wire-cloth into the web on the same against the atmospheric pressure prevailingabove said web of pulp. Secured .to the pipe l I isa suitable means, such as a-lever- I5 by means of which the pipe may be turned so as to adjust the direction of the jets of pressure air from the pipemore or less vtangentially with relation to the wire-cloth. l

The outflow aperture on the pipe Il may,'of course, consist of a single longitudinal slot in the pipe extending across the whole width of the machine.' Itis also possible to usea greater number of shorter longitudinal slots- I4, and in such case these slots are preferably arranged in at least two rows and in such manner that the ends of the slots overlap or pass each othe as shown in Fig. 2. These slots Il should also preferably be arranged in such manner, as shown to a larger scale in Fig. 3, that the jets from the slots converge, approximately at the point of tangency on the breast-roll as indicatedin Fig. l.

Instead of slots it is also possible to make the outflow apertures on the pipe Il in the form of round holes l1', as shown in Fig. 4, which holes should also in this case be located in several rows, and which may be bored in different angles relatively to the axis of the pipe,

jets will cross one another as indicated by the ar- A rows in Fig. 4, and d o not leave anyintermediate spaces through which the outside air might posf sibly penetratel into the gap.

being carried along so that the air4 bottom 6 of the outlet nozzle, and

Jets in the portion of said angle or portion of the wire-cloth. In this case 'the slots or holes are preferably arranged in one row only.

Fig. 6 shows another constructional form of a spreading device in which the baiile plate I9 is rotatably mounted on the pipe I l which may also be rotatably journalled. Suitable means, such as a lever indicated at 20, may be attached to the baffle plate I9 for adjusting the position of the same. This arrangement facilitates considerably the directing of the jets relatively to the breastroll.

In other respects-the constructional forms having spreading devices as shown in Figs. 5 and 6 conform to that shown in Figs. 1 and 2.

I claim: f

1. In a paper-machine of the Fourdrinier type, the combination of a breast-roll, a wire-cloth running over said breast-roll, a breast-box, a pulp outlet nozzle on said breast-box for supplying pulp to said wire-cloth above said breast-roll,`

said outlet nozzle having a lower wall vforming the upper boundary wall of an angle or gap between said outlet nozzle and the upward moving portion of said breast-roll, means enclosing said angle or gap at the ends of said breast-roll, and means lo'- cated adjacent said upper boundary wall for directing at least one jet of a Afluid mediumjex tending 'over substantially the entire width of said breast-roll, substantially tangentially to the upwardly moving portion of said wire-cloth and. in a direction substantially opposite to the direction of movement of said wire-cloth.

2. In a paper-machine of the Fourdrinier type, the combination of ay breast-roll, a wire-cloth running over said breast-roll, a. .breast-box, a pulp outlet nozzle on said breast-box forjsupplying pulp to said wire-cloth above said breastroll,- said outlet nozzle havinga lower wall forming-the upper boundary wall of an angle or gap between said outlet nozzle and the upward moving portion of said breast-roll, means enclosing said angle or gap at the ends of saidbreast-roll, a tubular chamber located adjacent said upper boundary wall and extending over substantially said chamber and directed substantially tangen- Viewed in cross section the said holes vI1 may Y be arranged in the same manner as that above mentioned in connection with the slots Il, and as illustrated in Fig. 3, that is to say, so that the jets v'from the holes I1 converge approximately at the point of tangency on the breast-roll.

In order still more to facilitate the formation oi' an air screen or curtain without objectionable interspaces, when'using a supply pipe Il having outow apertures in the form ofvslots or holes, there may be provided, as illustrated in Fig. 5, a bailie plate I8, which width of the machine, and which is parallel to the pipe l I which also in this case may be rotatably journalled, against which baille plate the air 4.iets from the slots or holes are directed so as to spread the same, after which they are directed substantially tangentially tially to the upward moving Portion of said wirecloth and substantially opposite to the direction of movement of said wire-cloth, and means connected to said chamber for supplying a Iiuid under pressure to the same.

3. In a paper-machine of the Fourdrinier type, the combination of a breast-roll, a wire-cloth running over said breast-roll, a breast-box, a'pulp outlet nozzle on said breast-box for supplying pulp to said wire-cloth above said'breast-roll, .said outlet nozzle having a lower wall forming the upper boundary wall of an angle or gap between said outlet nozzle and the upward moving portion of said breast-roll, meansgenclosing said angle or gap at the ends of said breast-roll, a tubular chamber located adjacent said upper boundary wall and extending'over substantially the entire width of said breast-roll, said tubular chamber being provided with a number of outflow l f being directed substantially tangentially to the tothe upward moving .'15

upward moving portion of said wire-cloth and l substantially opposite to the' direction of move.- ment of said wire-cloth, and means connected to over substantially the entire width of said breastsaid chamber for supplying fluid pressure to the same, in excess of atmospheric pressure. 4. In a paper-machine of the Fourdrinier type, the combination of a breast-roll, a wire-cloth running over said breast-roll, a breast-box, a pulp outlet nozzle on said breast-box for supplyy ing pulp to said wire-cloth above said'breastroll, said outlet nomle having a lower wall forming the upper boundary wall of an angle or gap between said outlet nozzlel and the upward moving portion of said` breast-roll, means enclosing said angle or gap atthe ends of said breast-roll, a tubular chamber located adjacent said upper boundary wall and extending over substantially the entire width of said breast-roll, said tubular chamber being provided with a number of outow apertures consisting of holes which are arranged ln at least two rows extending in the longitudinal direction of said tubular chamber and the Adirection of the axes of which form diierent angles to the axis of said tubular chamber, said holes being directed substantially tangentially to the upward moving portion of said wire-cloth and substantially opposite to the direction of movement of said wire-cloth, and means connected to said chamber for supplying a iluid under pres- -sure to the same. i 5. In a paper-machine of the Fourdrinier type, the combination of a breast-roll, a wire-cloth running over said breast-roll, a breast-box, a pulp outlet nozzle on said breast-box for supply-- ing pulp to said wire-cloth above said breastroll, said outlet nozzle having a lower wail forming the upper boundary wall of an angle or gap between said outlet nozzle and the upward moving portion of said breast-roll, means enclosing said angle or gap at the ends of said breast-roll, a pipe rotatably journalled about its axis near saidvupper boundary wall and extending over substantially the entire width of said breast-roll, said pipe being provided with at least one outiiow aperture extending in the longitudinal direction of said Apipe and directed substantially tangentially to the upward moving portion of said wire-cloth and substantially opposite to the ldirection oi movement of said wire-cloth, and means connected Ato said pipe for supplying a iluid under pressure to the same'.

6. In a paper-machine of the Fourdrinier type, the combination of a breast-roll, a wire-cloth running over said breast-roll, a breast-box, a pulp outlet nozzle on said breast-box for supplying pulp to said wire-cloth above said breast-` roll, said outlet nozzle having a lower wall forming the upper boundary wall of an angle or gap between said outlet nozzle and the upward movving portion of said breast-roll, means enclosing `said angle or gap at the ends of said breastroll, a pipe rotatably journalled about its axis near said upper boundary wall and extending roll, said pipe being provided with a number of outflow apertures consisting of slots extending' in the longitudinal direction of said pipe and arranged in several rows in such manner that their ends overlap one another, said slots being y the combinationof a breast-roll, a wire-cloth running over said breast-roll, a breast-box, a

pulp outlet nozzle on said breast-box for supplying pulp to said wire-cloth above said breastroll, said outlet nozzle having a lower wall forming the upper boundary wall of an angle or gap between said outlet nozzle and the upward moving portion of said breast-roll, means enclosing said angle or gap at the ends of said breast-roll, a pipe rotatably journalled about its axis near said upper boundary wall and extending over substantially the entire width of said breast-y roll, said pipe being provided with a number of outiiow apertures consisting of holes which are arranged in at least two rows extendingin the longitudinal direction of said pipe and the direction of the axes of which form diierent angles to the axis of said pipe, said holes being directed substantially tangentially to the upward movingportion of said wire-cloth and substantially opposite to the direction of movement of said wire-cloth, and means connected to said pipe for supplying a fluid under pressure to the same.

8. In a paper-machine of the Fourdrnier type, the combination of a breast-roll, a wire-cloth running over said breast-roll, a breast-box, a pulp outlet nozzle on said breast-box for supplying pulp to said wire-cloth above said breastroll,`said outlet nozzle having a lower wall forming the upper boundary wall of an angle or gap between said outlet nozzle and the upward moving portion of said breast-roll, means enclosing said angle or gap at the ends of said breast-roll,

and a baiile plate extending over substantially the entire width of said breast-roll and located in such position relatively to said pipe that a jet of fluid under pressure issuing from said outviiow apertureon said pipe4 against said baile plate is deiiected by the latter in a direction substantially tangential to the upward moving portion of said wire-cloth on said breast-roll and substantially opposite to the direction of movement of said wire-cloth.

' 9. A paper-machine as in claim' 8, in which' said baiiie plate is adjustable relatively to said pipe. l 10. In a paper machine having a non-perforated breast-roll rotating at comparatively high speed, the combination with a wire cloth running over said breast-roll, a breast box, a pulp outlet nozzle connected to said breast-box for supplying pulp to said wire-cloth above said breast-roll, saidoutlet nozzle having a lower wall forming the upper boundary wall of an angle or gap between said outlet nozzle and the upward moving A portion of said breaast-roll, of means enclosing said angle or gap at the ends of said breast-roll, and means located in close proximity to said upper boundary wall of said angle for directing at least one jet of air having a higher pressure than atmospheric pressure, over substantially utilow cloth above said breast-roll, said outlet nozzle' having a lower wall forming the upper boundary wall of a'chamber, another boundary wall which is formed by the upwardly moving portion o! said breast-roll, end closures for said chamber, and means 'located in close proximity to said upperboundary wall for directinga screen of air substantially tangentially downwardly to the upwardly moving portion of said wire-cloth over substantially theentirekwidth of said breast-roll, to prevent air outside of said chamber from being carried into said chamber and into the pulp mixture by the movement of said wire-cloth.

KARL HELGE TOMTLUND.

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