US2107812A - Suction roll - Google Patents

Description

E. E. BERRY ET'AL SUCTION ROLL Filed April 25. 1955 Feb. 8, 1938.

v Patented Feb. 8, 1938 UNITED STATES i PATENT OFFICE Application April 25, 1935, Serial No. 18,0801/2 15 Claims.

This invention relates to paper making machines and has reference more particularly to a suction roll of novel construction.

'I'he conventional suction roll is provided with f a perforated rotating cylinder having a stationary suction box operating against the inner surface thereof, the suction box carrying a relatively high vacuum which is transmitted to the sheet of pulp through the perforations in the cylinder to draw the water fromv the sheet and compact the same. l The suction rolls of the prior art, regardless of design or manufacture, produce noise when operating at speeds of about 400 linear feetper minute and higher, that is, when the rolls operate at a peripheral speed of about 400 feet per minute which is the speed of the paper running through the machine. Suction rolls operating on high speed machines, where the paper speed is 1000 to 1500 feet per minute, are exceedingly noisy, being high in pitch and particularly irritating and wearisome to the operators.

An important object of this invention is the provisioniof a suction roll so constructed as to substantially eliminate the noise inciden*J to the operation thereof at higher speeds.

A further object of the invention is the provision of a suction roll wherein the noise normally occasioned by the operation thereof is substantially eliminated and the eiiiciency of the equipment is substantially enhanced.

A still further object of the invention is the provision of a suction roll construction wherein the vacuum losses due to the operation of the machine are` materially reduced. '35 Other objects and attendant advantages will become apparent to those skilled in the art from the following description and the accompanying drawing, in which- Figure 1 is a fragmentary section through a suction roll embodying our invention;

Fig. 3 is a fragmentary section through a further embodiment of our invention, and

Fig. 4 isa fragmentary section through a suction roll showing a third and preferred embodiment of the silencing means.

This invention contemplates means for increasing the eiliciency of the mechanism through reduction in the vacuum pump requirements of the 50 roll, combined with means for effecting substantial silencing of the noise occasioned by the operation of the roll. These purposes are accomplished by providing secondary vacuum chambers on opposed sides of the main suction box so that the air in the holes of the shell at the oncoming Fig. 2 is a section on the line 2'-2 of Figure 1;

side of the suction box is partially transferred to the holes at the oigoing side so as to create a partial vacuum in the oncoming holes and partly break the vacuum in the oigoing holes, and by providing means for controlling the flow of air into the holes of the shell -as they leave the evacuated area of the roll.

Referring to the drawing, the numeral 6 designates generally the conventionalouter shell of a suction roll having the usual perforations or holes 10 'l for transmitting the vacuum through the shell to the sheet 8 carried on the conventional felt or wire 9 contacting the outer'surface of the roll. The roll has the usual suction box II positioned therein carrying a packing holder designated gen- 15 erally by the numeral I2 and having springs' I3 and I4 for urging the packing carrier toward the shell to cause the packing to seat thereagainst. The packing holder I2 carries two packings I5 and I6 defining a vacuum chamber I'I extending longitudinally of the roll. The chamber II communicates with the interior of the suction box through centrally located ports I8 spaced longitudinally of the packing holder. It will be seen that this is more or less the conventional suction roll arrangement wherein a relatively high vacuum is maintained in the chamberl I'I by means of suitable vacuum pumps.4

It is our belief that the sound caused by the high speed operation of the suction rolls is caused by the rapid egress of air from the perforations or holes 'l as these holes pass into registration with the vacuum chamber I'I and by the rapid ingress of air thereto as the holes pass from the packingon the oifgoing side of the suction box. 5 It should be noted that an average suction roll operating at one thousand feet per minute has about '730'holes per second passing over the suction box in one ring or plane perpendicular'` to v .the axis of the roll and a roll 136" wide, having 40 as an'average 400 holes'on each line longitudinal of the roll has a total of 292 thousand holes per second passing over the suction box when the roll operates at 1000 feet per minute. Thus, while the air rushing into or outof each of the holesl produces, in itself, only a relatively small sound vibration, the sum total produced by all of the holes assumes considerable proportion and produces a siren type of sound. Our investigations have shown us that this sound is produced principally at the offgoing side of the suction box,

a and it is our belief that it is caused by the entry of the air into the holes of the shell. While sound is probably also produced by the exit of air from the holes, this is normally not audible to the operators and may be absorbed in the suction box. During our experiments it occurred to us that the sound might be eliminated by arranging the holes in bands helically on the shell so that each band would act as a siren, the holes 'of each band breaking in succession over the packing so as to produce a pitch above the audible range. However, suchcondition is impossible of practical accomplishment because of the difference in the distance from the hearer to the successive bands of the shell, and numerous experiments have demonstrated the impracticability of silencing the roll in this manner.

In order to increase the efliciency of the vacuum system and cooperate with other devices to improve the sound characteristics of the'roll, we have provided chambers designated generally by the numerals I9 and 2I on opposite sides of the chamber I1, which chambers are formed by providing packings 22 and 23 in spaced relation to the packings I5 and I6, the packings being carried on the packing holder I2. The chambers I9 and 2l are interconnected at spaced points by means of ports 24 cored in cross members 25 of the packing holder. Channels 20 connect the ports 24 with the interior of the suction box. These channels are of very small size, insufficient to cause material increase of the vacuum in the chambers I9 and 2I but suilcient to permit the drainage of Water from the chamber 2 I. Through this arrangement when the holes of the shell pass over the packing strip I5, air enters the holes from the chamber I9 partially destroying the vacuum therein. This decreases the air pressure in the chamber I9 causing air to be drawn from the chamber 2I. The chamber 2I in turn draws air from the holes 1 in the shell on the oncoming side of the suction box, thereby producing a partial vacuum in these holes. It will be seen that this tends to conserve the vacuum in the holes 1 so that instead of air from the atmosphere completely discharging the vacuum in these holes, this reduced pressure is transferred by way of the chamber I9, the ports 24 and the chamber 2I to the oncoming side, thereby creating a partial vacuum in the holes prior to their registration with the chamber I1. By means of this structure, the holes, as they come to the packing holder, are first partially evacuated in the chamber 2i on the oncoming side and then fully evacuated at the main vacuum chamber I1. Upon continued rotation of the shell, the vacuum is then partially broken in the chamber I9 on the oigoing side of the main vacuum chamber I1. This structure results in a' very material reduction of the sound created by operation of the machine and also in a reduction in the vacuum pump capacity required to handle the suction roll and therefore in the power consumption for the vacuum producing equipment. This saving varies with the size and speed of the roll and with the relative proportion of the pump capacity required to evacuate the holes as against that part which is required to pull air through the sheet and paper and felt into the suction box. It may be conservatively said that this saving is between 15 and 30% or the total vacuum pump capacity required for a plain packing holder suction roll. While we have described this phase of the invention in connection with a suction roll having a separate packing holder, it will be understood that it is not limited in any way tothe manner of supporting the suction roll packing and may be applied to rolls wherein the packing is carried directly on the suction box or in any other manner.

While the supplementary chambers are designed primarily to improve the vacuum efficiency of the roll, they are also effective to a certain degree to reduce the noise of the roll. However, where the noise conditions are particularly aggravated, as, for instance, when the suction roll operates at very high speeds, this structure is normally not sufilcient to completely eliminate the sound. Under these circumstances we prefer to use a silencing device, one form of which is shown in Fig. 1 in conjunction with the chambers just described. In this form a strip of material 26 is bolted to the ongoing side of the suctionA box and extends from a position substantially to but not quite in contact with the inner surface of the shell, the edge being beveled as shown at 21 to conform with the curvature of the shell. This strip may be made of any material which does not tend to vibrate so as to produce sound, and we have found that wood or resin impregnated :ber such as Micarta is satisfactory. The lower edge of the strip 26 extends to a point close to the outer surface of the suction box so as to leave an opening such as shown at 28 between the lower edge of the strip and the outer surface of the suction box for the passage of air therebetween. The strip cooperates with the outer surface of the suction box to form a chamber 29 across which the shell of the roll passes so that when the holes 1 of the shell passv beyond the packing strip 22, air is drawn therein from the chamber 29 to completely break the vacuum. A sound deadening material, indicated generally by 3l, is positioned in the lower portion of the chamber 29. We have found that most any fibrous material may be used for this and have used burlap and similar material. We prefer, however, to use copper wire as the packing material because of its greater permanency. This packing material is conned in the bottom of the chamber 29 under a plate 32 having a plurality of perforations 33 for the passage of air through the plate. The plate 32 and the strip 2S are held against the suction box by means of bolts 34 and 35 secured in spaced ribs 38 projecting from the outer surface of the suction box. The embodiment just described has been found to be highly effective for the purpose of eliminating the sound, and may be used either with or without the supplementary vacuum chambers, that is, it may be used with or without the packing strips 22 and 23 and the chambers I9 and 2 I.

In Fig. 3 we have shown a further embodiment of the silencing device which is eiective to materially reduce the sound caused by the operation of suction rolls. In this form a shaped piece 31 of non-resonant material is attached to the offgoing side of a conventional packing holder 38 or direct to the suction box if no packing holder is used. This piece may be of such material as wood or synthetic resin and has a plurality of recesses or grooves designated generally by the numeral 39 connected to the atmosphere through channels 40 providing a labyrinth type of passage for the air to the holes of the shell. 'Ihe grooves 39 extend the full length of the perforated portion of the shell and are closed at their ends, and are so arranged that the holes 1 of the shell Will come into registration therewith successively upon rotation of the shell, whereby the vacuum existing in the holes as they leave the suction box is gradually reduced to atmospheric pressure through a series of stages or steps. The channels 40 are of selected size so that a step by step reduction inthe vacuum results. For the best results, however, the size of the grooves and the air inlets must be made to correspond to the conditions of operation. The proportioning of the grooves and the air inlets for this type of device can only be correct for a predetermined roll speed and vacuum condition, and should these conditions be changed, such as by increasing the speed or the amount of vacuum it might result in the holes having an appreciable vacuum when they pass from the member 31 so that the sound would not be reduced to the desired extent. This construction proves satisfactory, however, when the grooves and air channels are properly proportioned with respect to the speed and the vacuum.

In Fig. 4 We have shown what we now consider to be the preferred embodiment of silencing means for the roll. In this form we have provided a side piece 42 on the off-going side of the suction box Il attached thereto by means of bolts 43 andA spaced therefrom by spacing collars 44 on the bolts 43 and a shoulder 45 to provide a silencing chamber 46 extending longitudinally of the suction box substantially the full length of the roll.. The upper edge of the side piece 42 rests in closely spaced relationship with the inner surface of theshell, as shown at 41, and the lower edge of the side piece is provided with slots 48 spaced .longitudinally of the side piece. A dam, indicated generally by the numeral 49, is attached to the suction box by means of bolts 5I and is spaced `outwardly from the side piece 42, the upper edge ofv the dam extending 'a short distance above the upper ends of the slots 48, as shown at 52, whereby to provide a space 53 between the upper part of the dam and the lower part of the 'side piece. Water is supplied to the chamber 46 through a pipe 54 and normally lls the chamber 46 to a level above the upper edges of the slots 48. When the suction roll is in operation, the holes 'l pass over the packing I5 with a relatively high degree of vacuum, and air enters the holes l'from the chamber 46. The air is replaced in the chamber 46 by entry thereto through the slots 48, the air bubbling up through the water in the bottom of the chamber. 'I'his acts to produce a difference in the level of the water Within the chamber 46 and within the space 53, as shown in Fig. 4..

The effect of this mode of operation is to bring about substantial silencing of the operation of the roll so far as movement of air into the holes 'l is concerned. As previously mentioned, this is at present considered to be the preferred embodiment of the i`nvention largelybecause of the self-cleaning properties of the device. Any accumulation of paper stock which tends to form around the parts is held in suspension in the water due to the agitation taking place, and as additional water is admitted through the supply pipe, the stock particles are eventually washed away and thrown out of the roll.

Attention is directed to the fact that we are enabled to materially reduce the vacuum losses in the suction roll and while reducing the vacuum in the holes of the shell at one side of the suction box, We transfer this vacuum to the opposite side so as to partially evacuate oncoming holes, using for this purpose reduced pressures which have heretofore been dissipated. This reduction in the degree of vacuum in the holes at the off-going side of the machine is, in and of itself, not only effective to at least partially silence the operation of the roll, but cooperates with silencing means to effectuate the silencing of the roll.

Thus, this embodiment of the invention serves for the simultaneous reductionin the operating noise of the machine and increase of the efiiciency thereof.

We have also provided means located solely on the oifgoing side of the suction box for eliminating the sound incident to the entry of air aware that numerous alterations and changes may be made therein without departing from the spirit of the invention or the scope of the appended claims, in which- We claim:

1. The combination in a suction roll of a perfo- 1 rate shell, a suction box, and a sound trap at the offgoing side of Athe suction box for reducing the sound caused by the breaking of the vacuum in said perforations.

2. The combination in a suction roll of a shell having a plurality of perforations, and means for evacuating said perforations including a ceni trai 'high vacuum chamber and low vacuum chambers on opposite sides of said high vacuum chamber, said low vacuum chambers being interconnectedv whereby the reduced pressure in the perforations at the oigoing side of said suction box is transmitted Ato the perforations on the oncoming side thereof.

3. The combination in a suction roll of a shell having a plurality of perforations, a suctionbox for evacuating said perforations, and means to control the fiow of atmospheric air into said perforations to admit the same` through a plurality of steps whereby to reduce the sound produced by operation of the roll.

4. The combination in a suction roll of a shel -having a plurality of perforations, a suction box for evacuating said perforations, a chamber adjacent the oigoing side of the suction box, and

sound deadening material positioned in said chamber for absorbing the sound caused by the entry of air into said perforations.

5. The combination in a suction roll of a shell having a plurality of perforations, a suction box for evacuating said perforations, a chamber adjacent the oigoing side of the suction box, a

packing of metal wool positioned in said chamber for absorbing the sound caused by the entry of air into said perforations, and means for holding the metal wool in xed compacted position.

6. The combination in a suction roll for high speed operation 'of a shell having a plurality of perforations, a suction box for evacuating said perforations, and means to break the vacuum in said perforations by a plurality of stages to prevent the production of sound.

7. The combination in a suction roll of a shell having a plurality of perforations, a suction box channels for the admission of air thereto, the chambers and channels being proportioned to the speed and the degree of vacuum of the roll, said chambers being positioned for successive registration With said perforations to supply air to said perforations in a step by step fashion to gradually break the vacuum therein.

9. The combination in a suction roll of a shell having a plurality of perforations, a suction box for evacuating said perforations, and means for drawing air from the holes of the shell at the oncoming side of the suction box to break the vacuum in the holes at the oilgoing side of the suction box whereby to reduce the vacuum pump requirements of the roll.

10. The combination in a suction roll of a perforate shell, a suction box, and means for controlling the iiow of atmospheric air into the holes of the shell as they pass out of registration with the suction box to silence the operation of the roll.

1l. The combination in a suction roll of a shell having a plurality of perforations, a suction box i'or evacuating said perforations, a chamber at the offgoing side of the suction box communicating with the perforations in said shell, said chamber having a water seal through which air is supplied to said chamber to silence the operation of theroll.

12. The combination in a suction roll of a perforate shell, a suction box for evacuating the perforations in said shell, a chamber at the oigoing side of the suction box having bottom openings for the supply of air to said perforations, and

means for supplying water to said chamber above the level of said openings to cause the air entering said chamber to bubble through the water whereby to silence the operation of the roll.

13. The combination in a suction roll of a shell having a plurality of perforations, a suction box for evacuating said perforations, a chamber at the oigoing side of the suction box extending substantially the full length of the roll, said chamber having a plurality of longitudinally spaced bottom openings for supplying air to said chamber, means for supplying Water to said chamber, and a dam extending longitudinally ofand in spaced relation to said chamber for retaining the Water in said chamber at a levelabove said openings to provide a water seal to cause air entering said chamber to pass through the water whereby to silence the roll.

14. A suction roll comprising a perforated shell, a suction box in said shell adapted to be placed under partial vacuum, and sound reducing means at the offgoing side of the suction box packing for reducing sound caused by the breaking of the vacuum in the perforations as they leave the packing.

15. The combination in a suction roll for high speed operation of a shell having a plurality of perforations, a suction box for evacuating said perforations, and means to gradually break the vacuum in said perforati'ons to prevent the proy duction of sound.

EARL E. BERRY. LLOYD HORNBOSTEL. JOHN E. GOODWILLIE.

Images