US2363786A - Cylinder machine construction - Google Patents

Description

1944' P. H. GOLDSMITH 12, 5

CYLINDER MACHINE CONSTRUCTION Original Filed Sept. 2'7, 1938 2 Sheets-Sheet l INVEN+OR Philip E gold-smith Nov. 28, 1944. I P. H. GOLDMITH 2,363,786

' CYLINDER MACHINE CONSTRUCTION Original Fileisept. 27, 1938 2 Sheets-Sheet 2 r .U:

INVE NTOR I v Philipfi goldsmifh Patented Nov. 28, 1944 CYLINDER MACHINE CONSTRUCTION Philip H. Goldsmith, Wilmington, Del.

Original application September 2'7, 1938, Serial No. 231,854. Divided and this application November 18, 1941, Serial No. 419,563

7 Claims. (Cl. 92 43) This invention relates to the art of paper making and more particularly to cylinder paper machines of the type commonly used for manufacturing the heavier grades of paper, such as paperboard and the like. division of my copending application, Serial No.

. 231,854, filed September 27, 1938.

A cylinder paper machine commonly consists of one or more vats, each equipped with a foraminous rotatable cylinder mold 'which rotates in a roughly semi-cylindrical compartment located within the vat, the wall of the compartment being known as the vat circle. A paper stock is caused to flow between the surface of the cylinder mold and the vat circle through what is known as the vat circle space, and the water from the stock passes through the foraminous surface of the rotating cylinder mold, the fibers being retained on the surface to form a continuous web which is removed near the top of the cylinder mold onto an endless felt belt. Water from the interior of the cylinder, known as white water, is removed at both ends of the cylinder. machines the same felt usually picks up the web from several cylinder molds to form a composite sheet. Since it is frequently desirable to make the different plies of the sheet of different materials and diiferent thicknesses, each vat is ordinarily equipped with its own stock supply system and is really a separate machine.

There are many types of vats known in the art, each suitable for a particulargrade of paperboard under individual conditions of speed, nature of raw material, and requirements of products. The twotypes of vats most widely used heretofore may be referred to for the purpose of this description as the counterflow type of vat and the overflow type of vat. In the counterflow vat stock is fed to the uptuming side of the cylinder mold and flows in a direction contrary to the direction of rotation of the cylinder mold. Such The present application is a the fibers on the surface of the cylinder moldand for generally improving the physical characteristics of the web. The characteristics of the web are affected by many factors, among which might be mentioned stock velocity ratio, that is. the ratio of the mean velocity of the stock flowing through the vat circle space to the peripheral speed of the cylinder'mold; homogeneity of the stock supplied to the vat circle space; uniformity of stock velocity across the width of the machine; I

and the extent to whichthe flow of stock approaches theoretically perfect streamline flow. The stock velocity ratio has an important bearing on therelation between the tensile strength of the sheet in the machine direction and the crosstensile strength. As the stock velocity ratio increasesin an overflow vat the cross-tensile strength of the sheet improves at the expense of the tensile strength in the machine direction.

On multi-cylinder In order to obtain the desired degree of uniformity, it is desirable to maintain the stock velocity ratio constant, and since formation takes place all the way around the vat circle the quantity of stock flowing is constantly being reduced and optimum stock velocity ratios can be attained only by suitably reducing the cross-sectional area of the vat circle space.

and the quantity of circulating flow are substantially independent-of each other, the optimum rate of decrease in the cross-sectional area of the vat circle space will vary with the quantity of circulating flow. Hence, for best results the vat circle should be made adjustable.

a vat normally operates without recirculation of stock. In the overflow type of vat the stock is Y changes theinvention may equally well be applied to a counterflow type vat.

The present invention provides a methodand means for obtaining more uniform formation of Previous attempts to make the vat circle adjustable have not been completely satisfactory because of the fact that it is diflicult to prevent leakage of stock at the vat end walls. Asa result, there has been costly leakage of valuable stock, or, if the circle fitted tightly to the vat end walls,

it was difiicult to use the adjustment because of binding. To overcome this clifliculty water pressure chambers have been tried, but these have resulted in even more serious operating difliculties. If a water seal is used the water pressure must be maintained at ahigher value than that I but has a tendency to tear very easily on the machine.

In the present embodiment of. the invention Furthermore, since the rate of flow of water through the cylinder mold complete. adjustability is attained and the leak age problem overcome by the use of a double circle vat. The stock upon entering the vatpasses between an outer rigid vat circle and an inner adjustable vat circle before reaching the inner vat circle space. Since the consistency of the stock is substantially the same in both the inner vat circle space and the outer vat circle space, leakage at the ends of .the inner vat circle will result in no change in the composition of the stock. Furthermore, since the pressure difference between inner and outer vat circle spaces is negligible, there will be very little leakage. Ample clearances may be allowed between the inner vat circle and the vat end walls to permit the adjustments to function easily.

The homogeneity of the stock supplied to the vat has not heretofore received the consideration to which it is entitled. The common practice has been to mix the incoming fresh stock, the recirculated stock and the white water in an open top rectangular headbox. Each of the three components is normally introduced into the headbox through a separate pipe line, and it has been. as-

sumed that the natural turbulence resulting from ferent consistency stocks are formed in the corners of the headbox, and thissegregation causes streaks of uneven consistencies of stock to pass through the underfeed pipe and cause irregularities in the sheet. These irregularities produce blemishes in the formation, irregular caliper and finish across the sheet, and numerous operating troubles.

The present invention provides an improved type of mixing device comprising a venturishaped fitting through which one component of the stock flows while a second component of the stock is introduced at the neck of theventuri where the velocity is highest. It has been found that the most thorough and intimate mixture is obtained by joining two streams of flow in such a manner that their. cross-sectional areas are small and their velocities high at the point of mixing, and hence the diameters of both pipes are reduced at the point of joining. Themix'ing is accomplished before the stock reaches the head-box, and hence does not interfere with the proper functions of the headbox which are the maintenance of a constant flow level and the elimination of air or other gaseous materials from the stock.

Owing to the present tendency in the art to use wider machines and also higher rates of flow, the problem of obtaining proper approach flow has become increasingly important. One of the most important features of the present invention is the improved approach flow obtained. It has heretofore been the practice to attempt to obtain smooth and uniform fiow by passing the stock over orunder baiiles just before it reaches the vat circle space. While baflles of this type reduce turbulence to some extent, they are introduced too late in the process to accomplish best results. They bring with them other evils, such as=segregation of stock into uneven consistencies, flocculation of fibers into bunches, and a generally disturbed formation, and make-proper "washing up" of the vat more diflicult. They must be critical points in the process. The mixing of the various components of stock is completed before the stock reaches the headbox, and anupflow headbox is' provided. This enables the stock to flow smoothly over the dam of the headbox, and thus the elimination of ,air is more complete than I in the conventional type headbox wherein the extreme turbulence of mixing serves to increase the air content of the stock. The stock is spread to the full machine width by means of a flow spreader having a constant or slightly decreasing cross-sectional area and makes a full pass in the regarded in the nature of one evil which is used to counteract another.

The machine of the present invention-is designed to minimize turbulence at a number of 7 the vat circle space H machine direction before entering the inner vat circle space. In this way eddy currents are substantially eliminated and uniform stock velocity V across the width of the vat is obtained.

Apparatus capable of carrying out the method of the present invention is shown in the accompanying drawings in which:

Figure 1 is a diagrammatic view of the cylinder machine in perspective;

Figure 2 is a cross-section of thl'! vat and flow spreader taken along line 22.of Figure 1; and Figure 3 is a view of the vat end showing the white water compartment in section taken along line 3-3 of Figure 1.

Referring to the drawings, and more particu-'- larly to Figure 1, there is shown a vat of generally rectangular shape indicated at l and containing a foraminous cylinder mold 2' rotatably supported by the bearings 3, only one of which is shown. The mechanism for rotating the cylin der mold forms no part of the present invention and hence is not shown. Stock is supplied to the vat I through a flow spreader 4, which as noted above is of such shape and cross-sectional area as to spread the flow of stock to the full machine width with substantially no change or with a slight increase in stock velocity. Upon entering the vat I, the stock passes through a conduit 5 (see Figure 2) to the outer vat circle space 6 which is formed by an outer vat circle, wall, or partition 1 of generally cylindrical contour, and an inner vat. circle, wall, or partition 8 of similar contour, the vat circle I being rigidly secured to the vat end walls and the vat circle 8 adjustably secured to the vet end walls in a manner more fully' described hereinafter. 8 are constructed of sheet metal, preferably of copper, in order that the desired degree of flexibility may be obtained. A washout connection 9a is provided near the bottom of the vat circle I and a similar washout connection'Sb is pro-' vided near the bottom of the vat circle 8 to facilitate' cleaning of the vat circle spaces when it is necessary to change the type of stock supplied to the machine in order to produce adifierent.

the water from the stock passes through th fo-- raminous surface of the cylinder mold forming a web of fibers on the surface of the mold, which is removed near the top of the mold after it has emerged from the stock. The water passing through the surface of the mold, known in the art as white water, is removed in a manner which will be described later. The excess stock from passes over an adjustable The vat circles 1 and l3 and I4 (best shown in Figure '1) to be recir-- The inner vat circle I is fabricated in such a manner as to be supported bythree adjusting bars l8, l9, and 20, preferably of tubular crosssection. Theseadiusting bars are covered on both sides by'the sheet metal forming the inner vat circle so that both of the vat circle spaces are completely streamlined and no obstruction is presented to the flow of stock. The adjusting bars are in turn supported. by a series of movable plates 2|, :2, and 23 located at the vat ends (best shown in Figure 3). Adjustment of the clearance between the vat circle 3 and the periphery of the cylinder mold is accomplished by loosening the bolts 24 which hold the movable. plates in position and moving the plates in the desired direction. Normally the adjustable bar It will be positioned further from the periphery of the cylinder mold 2, than will the bar 23, and the bar I I3 will be positioned at an intermediate distance from the c linder mold in order to form a vat circle space havinga decreasing cross-sectional area which will compensate for decreases'in the quantity of stock due to water flowing through the surface of the mold.

The water which flows through the surface of the cylinder mold is removed at the end of the mold and flows into two white water compartments 25 and 26 at the vat ends, the compartments being separated from the vat ends by the spacer rings ZIa'gand 21b. Suitable seals should be provided at the ends of the cylinder mold 2 to prevent stock in the vat circle space H from flowing into the interior of the cylinder, mold. Such seals are well known in the art and hence are not shown in detail. As shown in Figure 3,. the white water compartments contain an adjustable dam having a rack 29 rigidly attached thereto. Raising and lowering of the dam is accomplished by rotation of the pinion 30, which in turn is attuated by rotation of a knob 3| located on the outside of the white water compartment. The portion of the white water which overflows the dam 28 is the excess white water and flows out of the white water compartment through a line 32 which leads to a suitable point of disposal. The remainder of.the white water, constituting the major portion thereof, is pumped by means of the white water pump from the white water compartment through the line 33,

3 cylindrical section which may be made adi ustabie in height. It is desirable that the dimensions of the cones 4| and 42 be such that at the top of the inner cone the annulararea between the two cones approximately equal the cross-sectional area of the inner cone. Stock flows upwardly through the inner cone 42 at a constantly decreasing velocity, passes over the dam 45 formed by the upper edge of the cone 42 and flows downwardly through the annular space 43st a constantly increasing rate. Because of the upward direction of flow of the incoming stock and the relatively low stock velocityat the dam 45, headbox 40 is well adapted to remove air and other gaseous materials from the stock and improve the smoothness of flow. Furthermore, variations in the rate of flow of stock will cause only relatively small turbulence or changes in the liquid level in the headbox because of the large overflow area of the dam 45 and the large area of the free liquid surface. It is to be noted that this type of headbox has no dead corners where stock segregation can occur and is much easier to wash up" than the usual type 01' headbox.

From the annular space 43 stock flOws through an underfeed supply pipe 46 which is preferably of a relatively large size and thence to the flow spreader 4 and the vat I.

takes place at a point remote from the forming whence it is again divided, one portion flowing through the line 34 and pump 35 to the screen or screens (not shown), where it is used as a dilucut, and a second portion flowing to a Venturishaped mixing device 36. In the mixing device 36 the white water is thoroughly mixed with the recirculated stock coming from the lilies l3 and I4. The recirculated stock is introducedv at the most restricted portion of the mixerand hence I at the point where the white water velocity is a maximum, thus insuring adequate mixingof the two components. From the mixer 36 stock passes through pump 31 to a second mixing device 38 of similar design where fresh incoming stock from the screens (not shown) is introduced through the line 39.

Stock from the mixing device 38 passes to a conical upflow headbox 40 comprising an outer inverted-cone 4| and an inner inverted cone 42 concentric therewith and forming an annular space 43. The outer cone 4| is provided at its top with a short cylindrical section 44. If desired,

the inner cone 42 may also be provided with a a vat, a cylinder mold in said vat. a curved inner The machine of the present invention makes possible the production of a paperboard having a substantially greater uniformity than was heretofore possible. The double circle vat enables the machine operator to control the stock velocity ratio in such a manner as to obtain the formation characteristics desired, uniform fiber deposition Positive, rapid, and complete mixing of the various components-of the stock is insured by the Venturi-shaped mixing devices, and this mixing surface. The upflow headbox insures proper elimination of air from the stock and the flow,

spreader spreads the flow t the full width of the machine with no sudden changes in stock velocity to produce unnecessary turbulence at this critical point in the process. Thus when the stock finally reaches the forming surface, eddy currents have been substantially eliminated and the flow of stock approaches theoretical streamline flow niigilch more closely than has heretofore been poss e.

Since many embodiments might be made of the above invention, and since many changes might be made in-the embodiment above disclosed, it is to be understood that all matter hereinbeiore set forth is to be interpreted as illustrative only and not in a limiting sense.

I claim: 1. In a cylinder paper machine, in combination,

wall cooperating with said mold to define a formin; section between said inner wall and the surface of said cylinder mold through which a paper stock may flow, an outer wall approximately 00- extensive with said inner wall and adapted to form with said inner wall a space between said inner and outer walls through which said paper stock may flow before reaching said forming secsurface of said cylinder mold through which a paper stock may flow, a curved outer wall adapted to formwith said inner wall a space between said inner and outer walls through which said stools may flow before reaching said forming section. and a plurality of adjusting means at spaced intervals along the length of said'inner wall for selectively varying at spaced intervals the distance between said inner wall and the surface of said cylinder mold.

3. In a cylinder paper machine, in combination, a vat having end walls, a cylinder mold in said vat, a curved partition cooperating with said cylinder mold and said end walls to deflne a forming section between said partition and the surface of said cylinder mold through which a paper stock may flow,-said partition abutting said end walls to prevent all but slight leakage of stock therebetween, means for'moving said partition with respect to said end walls and said cylinder mold to selectively adjust the distance between said partition and said mold, and means including a supply conduit for supplying stock to said forming section and returning said leakage stock to said forming section,

4. In a cylinder paper machine, in combination, a vat containing a rotatable cylinder mold, means forming an inner vat circle space through which stock flows in contact with the outer surface of said cylinder mold, means forming an outer vat circle space through which said stock flows before reaching said inner vat circle space, said outer vat circle space being approximately concentric with and coextensive with said inner vat circle space, and means for adjusting the distance between said inner vat circle forming means'and the surface of said cylinder mold at a plurality of points along said inner vat circle to maintain desired stock velocity ratios throughout said inner vat circle space, said inner vat circle forming means comprising a partition sufllciently combination of a flexible wall'conforming generally to the shape of said cylinder mold and cooperating therewith to define a forming section between said flexible wall and the surface of said cylinder mold through which said paper stock may flow, a rigid wall, approximately co-extensive with said flexible wall and cooperating with said flexible wall to form a space between said rigid and flexible walls through which said stock may flow before reaching said forming section and means for flexing said flexible wall at a plurality of points to selectively vary the distance between said flexible wall and said cylinder mold and thereby adjust the stock velocity through said forming section.

6. In'a'cylinder paper machine of the type wherein a. rotatable cylinder mold is partially immersed in a paper stock contained in a vat, the combination of a flexible wall extending around approximately one-half the perimeter of said mold and spaced therefrom, said flexible wall cooperating with said mold to define a forming section between said flexible wall and the surface of said cylinder mold through which said paper stock may flow, a rigid .wall, approximately coextensive with said flexiblewall and cooperating therewith to form a space between said rigid and flexible walls through which said stock may flow before reaching said forming section and means for flexing said flexible wall at a plurality of points to selectively vary the distance between said flexible wall and said cylinder mold and thereby adjust the stock velocity through said forming section.

'7. In a cylinder paper machine of the type wherein a rotatable cylinder mold is partially immersed in a paper stock contained in a vat, the combination of a flexible wall curved to conform approximately to the shape of said cylinder mold and cooperating therewith to define a forming section between said flexible wall and the surface of said cylinder mold through which said paper stock may flow, a rigidwall curved to conform approximately with said cylindermold and said flexible wall, said rigid wall cooperating with said flexible wall to form a space between said rigid and flexible walls through which said stock may flow before reaching said forming section and means for flexing said flexible wall at a plurality of points to selectively vary the distance between said flexible wall and said cylinder mold and thereby adjust the stock velocity through said forming section.

PHILIP H. GOLDSMITH.

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