US1827279A - Method and apparatus for refining pulp - Google Patents

Description

Oct. 13, 1931. CARNAHAN 1,827,279

METHOD AND APPARATUS FOR REFINING PULP Filed Dec. 9, 1929 Fig 3.

Fig 4! INVENTO R George/$ 1 Car/MA BY 1%1'2/7 1 6 [)0 W5, PlarVi/H Ec/m ends ATTORN EYS Patented Oct. 13, 1931 UNITED STATES PATENT OFFICE GEORGE HOLMES CARNAIIAN, OF NEW YORK, N. Y., ASSIGNOR TO RUBBER SURFAGERS, INCL, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE METHOD AND,APPARATUS FOR REFINING PULP Application filed December 9 Thisinvention relates to an improved meth-t d and apparatus for treating fibrous material and more particularly for treating pulp or paper stock whereby the felting properties of the fibers are improved and, in the case of vegetable fibers, the fiber substance is also hydrated while minimizing the shortening of the fiber length which results from the cutting or breaking of the fibers when treated by the methods now commonly used. The

new method and apparatus also reduces the time usually required for the beating treatment and produces a stock which improves the tea-ring, tensile, bursting and folding 1 strength of the paper made from it.

It has heretofore been the practice inthe paper and allied industries to subject the ulp or stock to the action of a'refining mac 'ne such as the kollergang or edge runner. The

usual machine consists of a circular pan havthe weight of which is ing the center portion thereof raised. A shaft projects through the raised portion of the pan and fastened to it at right angles are two or more axles on which are mounted large rolls, carried largely by the bottom of the pan. The rolls are usuallg made of stone or other heavy material.

source of power is connected to the shaft so ,the pan in a circular path.

and this also accommodates the machine to f the wear of the L By reasonof the inherent hardnessor rlgthat the rolls may be caused to travel around The material to be treated is placed in the bottom of the' pan and the rolls pass'over 1t in their travel around the circular path in stones.

idity of the stone or other heavy material used in the rolls, the rolls have a shearing and cutting effect on the pulp so thatthe fibers are 1929. Serial No. 412,698.

0 a large extent cut oif with the result that the fibers so out are not only shortened, but are left with more or less clean ends, instead of ends in a frayed or torn condition, which is desirable" to give the ulp good felting properties. the rolls, is usually made of stone, and with constant use both the roll and the bottom become worn irregularly due to irregularities in the composition of the stone used. The fibers caught between these two hard and rigid surfaces and subjected to a rubbing action are too often cut by irregularities in the hard surfaces of the roll and bed plate, and the fibers also tend to out each other.

With the present invention this cutting action is largely avoided and the fiber bundles are disintegrated or separated into their individual fibers by a shearingaction substantially devoid of the cutting effect and the individual fibers are given the desired flattened and frayed condition by a non-cutting, rub- 1 bing and crushing action. This is accomplished by providing the rolls or the bed plate, and preferably both the rolls and the bed plate, with yielding resilient cushion-like surfaces which have no cutting edges or surfaces and which exert on the pulp a rubbing effect without cutting, in place of the hard rigid surfaces heretofore used. Preferably these surfaces are of rubber, the rubber used beingof about the consistency of that used in rubber automobile tires.

The hard rubber used throughout the spec ification and claims includes not only rubber and rubber compositions in a strict sense, but also rubber substances and equivalent compo-.

sitions having the proper rubber-like con-- sistencies and physical characteristics for making yielding resilient surfaces suitable for performiiig the method of the present invention. These cushion-like surfaces of rubber or equivalent substances not only yield as a whole to the pulp but are also ca able of yielding locally to bundles of fi rs or H bunches, thereby further minimizing the danger of injury to the fibers during the treatment.

By the rotation of the shaft the rolls travel around the circular channel of the pan and The bottom 0 the pan, as well as as I the fiber bundles and fibers are thus subjected substantially without cutting them to a shearing action characterized by rubbing, crushing and flattening by the rolls so that the fiber bundles are separated into their individual fibers and the fibers are hydrated and frayed, as contrasted with the usual cutting action, the degree of hydration depending largely upon the severity and duration of the beating process.

As a result the felting properties of the fibers are improved and a more uniform close web is obtained when the pulp passes over the aper machine wire, and the resulting paper 1s stronger than could be made from the same stock with the beating methods heretofore commonly used. The squeezing, crushing and rubbing action between the relatively yielding surfaces tends to flatten out the fibers and to split them into fibrillae and to gelatinize or hydrate the fibers in a manner which develops their felting and inherent strength-giving properties without objectionable shortening of the fibers. The average length of the treated pulp fiber is greater than in similar pulp SllbJGCtGCl to the action of the ordinary -kollergang and the pulp is relatively free from out fiber and blunt ends found in the.pulp beaten in an ordinary'kollergang. Paper can be produced from the ulp resulting from the process of the present invention having higher tensile strength and bursting strength, higher tearing strength and higher folding strength than with the same pulp beaten by usual methods. Moreover, the pulp itself is a free pulp from which the water readily drains away faster than with pulp treated to the same extent in an ordinary kollergang. Freeness, as that term is used in paper making, denotes the rate at which water drains away from the pulp on the wire of the papermaking machine. The principal factors affecting freeness are the hydration of the individual fibers and the average length of the fibers. Hydration tends to make a pulp slow that is, less free), but that is more than offset by the fiber length resulting from the method of the present invention. A free pulp is desirable in that it permits increasing the speed of the paper making process, and hence reduces the cost, for the reason that the water will drain away faster from the pulp on the wire and the presses will express more water than from a less free pulp and hence the volume of the water which must subsequently be removed by the dryers is reduced. By reason of the increased-average length of the fibers produced by the new method of the present in- 'vention the freeness of the pulp is improved notwithstanding the fibers are adequately hydrated.

The cushion-like surfaces also have the ef-' feet of increasing the area of contact between the rolls and the bed stone. With the har and rigid surfaces of the stone rolls and bed stones, the area of contact at any instant must necessarily be represented by a straight line across the face of the roll at the point of contact. With the yielding resilient surfaces of the present invention the area of contact will be much larger due to the compression of the surfaces at the point of contact and any resultant bulging adjacent thereto. The fibers are thus treated with a twisting, rubbing motrate the new apparatus suitable for practicing the new method:

Fig. 1 is a sectional elevation;

Fig. 2 is a plan view of part of Fig. 1; and

Figs. 3 and 4 are detail views on an enlarged scale in section illustrating different constructions of the yielding resilient surfaces applied to the rolls.

The pulp or sock to be treated is continuously fed into the pan 5 of the kollergang by means of spiral feed 6 and screw conveyor 7 or by any other appropriate means of maintainmg a constant feed. The kollergang may be provided with two or more rolls 8 and the machine illustrated is shown as having three rolls. These rolls are made of a dense material which lends weight to them and enables them to crush the pulp fibers as they pass around the pan. The rolls 8 are provided with a v rubber surface approximately one half or more inches thick which may be made in strips and cemented to the rolls or may be vulcanized directly thereon.

The bottom of the pan or bed stone 9 is provided with a rubber surfacing 10 of any desired thickness which may be applied in the same manner as the rubber surfacing on the rolls. The rolls 8 are mounted on axles 11 which in turn are fastened to the central shaft 12. The shaft 12 is provided with a bevel gear 13 by means of which power is applied to the shaft to cause the rolls to travel around the bottom of the pan 5.

The pulp or stock is withdrawn continuously through the opening 14. This opening is provided with a weir 15 which may be lowered or raised as desired to decrease or increase the depth of the body of pulp or stock being treated in the pan 5. The stock passes into chamber 16 from which it is removed by spiral conveyor to another step in the paper making process, or to another treatment in another kollergang; By regulating the height of the weir and the rate of feed to the pan, the length of time to which the pulp is subjected to the treatment can be regulated.

For example, with a relatively large body of plate, the higher portions 17 are flattened so that a kneading action is applied to the fibers, which amplifies the rubbing and crushing action of the process of this invention with resulting increase in hydrationof the fibers and the separation of the bundles of fibers. The effect of having this wavy rubber surface on the roll is to intensify the treatment ofthe fibers in each revolution of the rolls with resulting speeding up of the process and conse uent saving in time.

ith a surface simiar to that shown in Fig. 3 in which the raised portions 18 are relatively more prominent, the said raised portions do not become entirely flattened when the surface of the rolls comes into contact with the bed plate. The raised portions are flattened somewhat, but the depressions between the raised portions are not entirely eliminated, so that the depressed portions of the roll do not touch the bed plate. This results in an even more pronounced kneading effect on the fibers with resulting increased efiiciency in each revolution of a roll and tends to hold the fibers under the roll and prevent their slipping out ahead of the roll. This also tends to increase the efliciency of the operation as a whole.

I When the rolls travel around the bed plate, the pulp 1s subjected to the kneading action of I the resilient yielding surface, certain forms of which have been, described by way of illustration, the effect is to rub, crush, abrade and pull the pulp without substantlal cutting so as to separate bundles of fibers roll and bed plate surfaces, one at least of said surfaces being of substantial thickness and resilient and yieldable, whereby the fibrous material is subjected to the squeezing and rubbing action of the contacting surfaces having a substantial area of surface yieldably contacting with each other.

2. The process according to the preceding claim in which both surfaces contacting with each other are resilient and yieldable whereby the fibrous material is subjected to a squeezing and rubbing action between such yieldable surfaces.

3. [A kollergang comprising rolls and a bed plate therefor, said rolls having resilient yieldable surfaces of substantial thickness which have a substantial surface contact with the bed plate during operation.

4. A kollergang comprising rolls and a bed plate therefor, the said plate with which the rolls come in contact having a yieldable resilient surface of substantial-thickness which has a substantial area of contact with the rolls during operation.

5. A kollergang com risin' rolls and a bed plate therefor, both t e rol s and the bed plate having resilient and yielding surfaces of substantial thickness which have substantial surface areas in contact with each other during operation.

into individual fibers and to fray out the ends ile the .present invention is of particular value for the beating of chemical wood fiber, it includes in its broader aspects the refining of other materials which require similar treatment.

I claim 1. The method of treating fibrous material, which comprises-subjecting sucli material to a combined squeezing and rubbing treatment in a kollergang having contacting

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