US2346746A - Continuous freeness recording method and means - Google Patents

Description

Patented Apr. 18, 1944 CONTINUOUS FREENESS RECORDING METHOD AND MEANS Arthur Brooks Green, Needham, Mass, assignor to Paprex Company, Wakefield, Mass, a corporation of Massachusetts Application March 3, 1941, Serial No. 381,419 Claims. (Cl. 73-51) This invention relates tothe' measurement of the rate of release of a liquid from its mixture with solid particles and the recording of such measurement.

board, for determining the condition of the paper stock prior to its delivery to the forming machines,

When the body of paper stock is in such condition that water will be released rapidly from the solid material, the stock is saidto be free. If, on the other hand, the release of water therefrom takes a relatively long time, then the stock is said to be slow. Accordingly, devices for testing such conditions of paper stock are known as freeness or slownesstesters. this application, the invention will be referred to as a freeness tester, although it is to be understood that the device also indicates slowness, the two terms being in effect the reverse of each other.

As paper making stock is prepared, prior to The invention-is particularly related to the manufacture of paper and paper In connection with justment of the refining equipment. contrary, the adjustments of the refining equip- Owing to the variable paper making properties of untreated fibrous pulps, which arise from the random growth of woods and other plant sources of fibre, it 'is not possible to deliver a specified freeness uniformly by maintaining a uniform ad- On the ment must be changed constantly in such way as to compensate for the unavoidable variables in thepaper making properties of incoming pulps, and for the furthervariables in the response. or

yield, of fibrous pulps to the mechanical stock samples which then pass to a, laboratory or to a passing to the Web-forming machine, it passes I through two types of machines, either of which can be. used without the other, but both of which are commonly used together. The first type is known as a beater, and operates as a batch process. The second type is known as a refiner, and operates as a continuous process. '-If the batch beater is employed, 'either singly or in multiple,

the successive batches, when the beater preparation has been completed, discharge to a chest, provided with a mixer or agitator, which serves as a reservoir. It is from such a chest that stock is then drawn continuously for the next paper. making process, whether this be continuous refining or continuous web-forming as on the paper or paperboard machine.

Where batch heaters and continuous refinersare both employed, the total work of preparing the stock is shared between them, the batch heaters being the vessels in -which the furnish, or composition, of the final product is determined, and the engines in which the preparation of the stock by mechanical treatment is begun. When the stock leaves the batch heaters, in this case,

and passes through a reservoir chest to continuous refiners, it usually sumces for practical pu poses if the refiners deliverthe stock continu-- If continuous remanual tester; or to introduce into the stock a freeness tester ofthe type disclosed in the patent toArthur'B. Green, No. 1,985,321, periodically and to make a freeness reading therefrom. However, such methods have proven unsatisfactory, as such readings do not keep the operator of the refining equipment-continuously informed, and they further requireextra labor. In consequence, departures from a specified freeness may occur. and pass undetected, and the quality of the product may be correspondingly impaired, and the productivity of the web-forming machine mayI be correspondingly limited; also a special labor cost is incurred, increasing the total cost of production.

According to {the presentjinvention, the freeness testing device is combined with a mecha-' nism which produces a series of tests at predetermined intervals and records the result of each test in a permanentrecord -for continuing inspection by the operator. Thus, by employing time intervals between tests suficiently short, the operator is; informed immediately of variations from a specified freeness and is able to make immediate corrections by readjustment of the refining equipment, and maintain correctly that freeness which will produce the desired product.

A further object of the invention is the pro vision of a freeness tester with means for introducing it into the stock uniformly and periodically while the stock is undergoing treatment, combined with means for recording the results of each test. Thus, by the elimination of'the variables that have inevitably appeared in tests made ac-' cording to methods heretofore used, the resulting running record made by this invention will give a reliable report of the freeness at the time of each test. As previously stated, however, control of the stock density and temperature is assumed as indicated freeness varies with changing density and temperature.

These and other objects of the invention will appear more fully as the description and explanation of the invention proceed, with the aid of the accompanying drawing, in which;

Fig. 1 is a side elevation of the invention, part being in section, showing the freeness tester in the position it normally assumes between the periodically made tests.

Fig. 2 is a side elevation of the invention, also partly in section, with the freeness testing mechanism immersed in the paper stock.

Fig. 3 is an end elevation on the line 3-3 of Fig. 1.

Fig. 4 is a section on the line 4-4 of Fig. 1.

Fig. 5 is a detail of cushioning means used to check the descent of the piston. Referring to Fig. 1, a flow box 2 is connected to carry stock by intake pipe 4 and outlet pipe 6. A dam 8 provides for the maintenance of a constant level of stock as at Ill. The stock, as it flows in through pipe 4 and out through pipe 6,

is representative of the stock under treatment. Thus, any tests made on the stock within the flow box will be representative of tests of all stock moving towardthe web-forming machine. It will be understood that the stock is flowing into flow box 2 continuously through intake pipe 4 and likewise is flowing continuously over the dam 8. As a-result, the stock in the flow box is in continuous movement and is being continuously replaced by the new stock being added from intake pipe 4. There is 'never any dead or stationary stock in the flow box so that any tests thatmay be made thereon will always be made on the newly arriving and continuously changing incoming stock.

An immersion freeness tester I2 is mounted on means designed to provide for periodic immersion of the tester into the stock of the flow box.

A construction that has been found convenient is shown in the drawing and consists of a cylinder l4, a, piston 46 carrying tester l2 and vertically movable within the cylinder, an automatic recording mechanism 18 and control means, referred to generally at 20, for automatic lowering and raising of piston l6 and immersion and removal of the freeness tester l2.

Through the operation of control means 20, the freeness tester I2 is periodically introduced into the stock in the flow box 2, a recording of the degree of freeness at that time is made on the recording mechanism Hi, all followed by subsequent removal of the freoness tester until such time as the operation is repeated. Thus, as the freeness of the stock in the flow box changes, such change will be noted and recorded through the periodic immersion of the tester.

While one form of tester of the immersion type is disclosed, it is to be understood that any other suitable type of tester capable of giving a recordable reading may be used, and likewise the means for introducing the tester into the stock may be varied.

The control mechanism for raising and lowering piston I6 operates as follows. Connected in order to a water supply pipe 22 are shut-oil valve 24, strainer 26, pressure regulator 28, T 36 and fitting I06, the latter of which connects with the generally referred to at 38 and shown in Figs. 1.

and 3.

For purposes of rigidity and general support, an extension 40 placed beneath the fitting I06 supports the piping and cylinder structure. This. however, is but illustrative and any other type of suitable support may be used with equal eflect.

Water entering pipe 22 under suitable pressure exerts an upward force against the end of piston I6 to drive the latter upwardly to the limiting position shown in Fig. 1. Valve 34 at this time is closed, and with the piston in upward position, no further flow of water through pipe 22 takes place. If however, quick acting valve 34 is opened so that not only the incoming water may escape through discharge pipe 36, but also the water within cylinder [4 under the influence of the downward pressure of piston I6 and its associated structure, it is apparent that piston I6 will move downwardly at a rate determined by the dimensions of the various parts and the water pressure as controlled by valve 24 and pressure regulator 28.

As the load on piston I6 is constant, it is obvious that the rate of descent of the piston upon the opening of valve 34 will be the same on each occurrence, except as it may be afiected by resistance of the stock to entrance of the freeness tester I2. For all practical purposes, however, the time of the descent of the freeness tester l2 into the stock is substantiall the same on each test. This being so, it is apparent that a mechanism has been provided which is capable of immersing the tester repeatedly into the stock at the same rate and within the same time interval.

The means for controlling the operation of valve 34, which in turn controls the movement of piston 16, is shown in Figs. 1 and 3 and referred to generally as at 38. This mechanism comprises an electric motor 42 which through reduction gearing 44 and 46 rotates cam 48 counter-clockwise, as indicated in Fig. 3. The gearing maybe adjusted to give the cam any desired speed of rotation, it being contemplated, however, that for each revolution of the cam, there will be one complete reciprocation of piston I6.

Resting on cam 48 is a cam follower 50 which is supported in position by lever 52, pivoted at 54. As cam 48 rotates, follower 50 will move up and down and will carry with it lever 56, which in turn is pivoted at 58 to arm'BO of valve 34. Upward movement of arm 60 closes valve 34; downward movement opens it. In the position shown in Fig. 3, valve 34 has just been opened.

An adjustable stop 61, positioned to engage lever 52, serves to limit the downward movement of arm 60. Thus, by suitable adjustment of stop 6!, the extent of opening of valve 34 may be controlled, and in this way the desired rate of descent of piston l6 may be achieved.

With the automatic immersion mechanism in operation and with cam follower Soon the large circumference or dwell portion of cam 48, arm

reach the position shown in Fig. 2. In the meanwhile, rotation of cam 48 has proceeded and valve 38 is gradually closed. Closure, however, is timed to take place only after the immersion tester I2 the bottom of the cylinder body 62 and then'upwardly into tube 68. Since .the resistance eleas that disclosed in the Green Patent No.'

1,985,321, previously referred to, and consists of a cylindrical body 62 having therethrough a plurality of suitably sized perforations 68. Body 82 could if desired be composed Of screening or any other material that would permit suitable infiltration of water when immersed in the pulp stock. The lower end of body 62 is closed by end member 68. Within and positioned coaxially therewith is an imperforate tube 68 open at its lower end. Inside of tube 68 is a movable rod Ill having on its lower end a resistance element 12 so designed as topermit controlled passage of liquid thereby. A suitable form of resistance element is shown in Figs. 1 and 4, in which there is a bottom disk 14 perforated at I8 and carrying thereabove a plurality of angularl set blades 78. Water passing upwardly through perfora- 80 and a stop 82 limits the downward motion of rod I8 and element I2 within tube 68. Another stop 84! on rod 10 acts as a means for making engagement with a lever arm 85 of the recording mechanism I8. The recording mechanism I8 is shown diagrammatically as the particular con struction thereof does not constitute part of this invention. However, it will be seen that if lever 86 is swung upwardly about its pivot at 88, arm 88 will be swung to the right to make a permanent record of its movement as at 92 on the rotating paper disk 98.

In Fig. 5 is shown a detail of the construction of the lower end of the piston, which includes special cushioning means for eliminatin any shock to the recordin apparatus that would otherwise occur at the completion 0f.its descent.

The lower end of cylinder It terminates in a tubular portion which forms what may be calleda cushioning cylinder. as at I86.

It is at this reduced section that the T 38 is connected, with a portion of the cushioning cylinder extending therebelow. The piston I6 has extending from its lower end a secondary piston I08 shaped to fit relatively closely within the confines of the cushioning'cylinder I I18. Primary piston I 6 also has at its lower end a cup packing I I 0 which seals the piston I6 and cylinder It against leakage.

As piston I6 descends following the opening of valve 38, secondary piston I08 will finally reach the entrance to the cushioning cylinder I06, when the recording apparatus is close to the bottom of its movement. As 'soon as secondary piston I08 enters cushioning cylinder l 06, which may be con sidered that part below the connection to T 38, and in turn discharge pipe 36, the downward travel of piston I6 and associatedparts will be slowed, due to the fact that the fluid imprisoned in the bottom of cushioning cylinder 106 can escape upwardly past secondary piston I88 'to pass into discharg pipe 36 but slowly. This results, in

tions 16 will impinge on the blades 18 to cause a gentle easing of piston It to its final position of rest and insures that there will be no jarring of the recording apparatus at the termination of its downward movement. As a result, the recordings made thereon willbe accurate and in ac-' cordancewith the exact movement of rod I0.

Operation of tester As the tester is immersed in the stock, water from the stock will immediately begin to filterthrough perforations B4. The water will flow to ment I2 resists the upward movement of water in.

the tube, it and rod ID will b carried upwardly along with the water, lagging somewhat behind as Water passes through perforations I8 of the resistance element. This, of course, moves stop 84 into engagement with lever 86. and recording arm 90 commences its swing to the right.

At the outset, the infiow'of water through per forations-Sd is rapid, but as the stock accumulates on the outside of the cylinder body 82 to gradually block perforations '64, passage of water to the interior becomes slower so that the rate of rise in tube 68 decreases Y i It will be apparent, therefore, that a'point will finally be reached at which the rate of descent of resistance element 12 and rod III through the water in tube 68 will exactly equal the rate of rise of the water column. At this point, the upward movement of rod Ill ceases and arm 90 will have-moved its maximum distance to the right to complete the recording on that test.

Thereafter, as rod "Ill .descends, further rise of the water column within tube 68 is immaterial and valve 34 may be closed to cause withdrawal of the tester from the stock to its original position-as in Fig.1.

As the tester is withdrawn from the stock, the water which has collected within body 52 and tube 68 reverses its direction and fio-wsoutwardly through the perforations 64, causing the fiber mat on the outside to leave the screen and to fall back into the stock along with the flushing water, the next stock, as just described, may be assisted by spray nozzles '96 and 98 which are provided to give sumcient additional washing effect as the tester is Y withdrawn to drive any residue therefrom. Nozzle I08, directed at piston I6, cleans the latter to insure uniform performance. These nozzles receive their water supply from any convenient source and may be brought into operation by'any convenient means upon the commencement of upward movement ofpiston Hi to be shut off when the upper limit of travel is reached.

Summary of operation .The complete operation of the invention is as follows. box 2 and is maintained at a constant level there-.-

Paper stock flows continuously into flow in by dam 8. 'Cam 48, which controls the fall 'and rise of'piston I5, rotates at a constant speed Arm is swung to the right and makes a per.

slower or faster rate, due to the change of character of the stock that accumulates over the perforations. As a result, the rate of rise of the water within tube 68 will be lessor more and the corresponding movement of arm 90 to the right will be less or greater. Successive tests therefore give a running record of the variations in freeness of the stock, the point of reading on the recording mechanism being the outer end of the mark. Through suitable calibration of the tester, the recordings will indicate directly the freeness, so that the operator in charge of stock treatment will know immediately by mere reading of the recorder when the stock is at the desired freeness to go to the machines.

While a preferred construction has been illustrated and described, it is recognized that other means may be used for controlling the immersion and withdrawal of the tester from the stock. For example, air instead of water'could be used to control the piston operation.

However, whatever the particular means for controlling the immersion of the tester is, it is to be understood that it is to be immersed at determined intervals of time and at the same rate, whereby any change in reading on the recorder will be an indication of a corresponding change in freeness. Likewise, it is to be understood that the particular construction of the immersion tester itself may be varied so long as ing a fluid operated piston, a valve controlling 1 the requisites of operation are the immersion of the tester into the stock on each test at the same rate and to a fixed depth. Furthermore, it is understood that the invention is to be limited only by the appended claims.

Iclaim:

' 1. Means for testing and recording the freeness of paper stock, comprising a constant level flow box containing paper stock to be tested, an immersion type freeness tester, means for recording the result of each test made. by said freshness tester on said paper stock, and means for periodically and uniformly immersing said freeness tester into said paper stock and then withdrawing it from said stock after each test has been recorded.

2. Means for testing and recording the freeness of paper stock, comprising a constant level flow box containing paper stock to be tested, an immersion'type freeness tester, means for recording the result of each test made by said freeness tester on said paper stock, and means operated by fluid under pressure for automatically conducting a series of uniform tests at predetermined intervals, each test comprising the movement of said tester into and out of said stock.

3. Means for testing and recording the freeness of paper stock, comprising a constant level flow box containing paper stock to be tested, an immersion type freeness tester, means for recording the result of each test made by said freeness tester on said paper stock, means for automatically conducting a series of uniform tests by immersing said tester to a fixed depth at a determined rate at predetermined intervals. said uniform test means including means for cleaning said freeness tester of paper stock after each test, whereby the conditions at the commencement of each test will be identical.

4. Means for testing and recording the freeness of paper stock, comprising a constant level flow box containing paper stock to be tested, an immersion type freeness tester, means for recording the result of each test made by said freeness tester on said paper stock, means for lowering said freeness tester into said paper stock tc a fixed depth and at a determined rate at predetermined intervals, and means for subsequently withdrawing said freeness tester from said paper stock prior to the time of making the next test.

5. Means for testing and recording the freeness of paper stock, comprising a receptacle containing paper stock to be tested, means for maintaining a uniform level of said paper stock, an immersion type freeness tester, means for recording the result of each test made by said freeness tester on said paper stock, means for immersing and withdrawing said freeness tester into and from said paper stock at predetermined times, said immersing and withdrawing means compristhe pressure of fluid against said piston, and means for opening and closing said valve at predetermined time intervals.

6. Means for testing and recording the freeness of paper stock, comprising a receptacle containing paper stock to be tested, means for maintaining the level of said paper stock in said receptacle at a constant point at the time of each test, an immersion type freeness tester comprising a perforated element, a tube within said element for receiving liquid that may pass through said perforated element, a resistancev element movable vertically within said tube, means for recording the result of each test made by said freeness tester on said paper stock in accordance with the vertical movement of said resistance element under the influence of a rising column of liquid within said tube, and means for automatically conducting a series of uniform tests at predetermined intervals by the introduction of said tester into said paper stock to a predetermined depth and at apredetermined rate, said last means comprising a fluid operated piston, a valve controlling the pressure of fluid against said piston, and means for opening and closing said valve at predetermined time intervals.

'7. Means for testing and recording the freeness of paper stock, comprising a receptacle containing paper stock to be tested, an immersion type freeness tester, means for recording the result of each test made by said freeness tester on said paper stock, means including a piston and cylinder for repeatedly lowering said freeness tester into said paper stock to a fixed depth in a substantially uniform time at predetermined intervals, and means for. decreasing the rate of descent of said freeness tester as it approaches the bottom of its travel, said last named means comprising an extension at the end of said cylinder of reduced cross sectional area and a projecting portion on the end of said piston adapted approaches the end of its-travel.

8. Means for testing and recording the freeness of paper stock, comprising a receptacle containing paper stock to be tested, a freeness tester, means for lowering said freeness tester into said stock in a substantially uniform time to a fixed vto enter said cylinder extension as the piston depth during each test, and means" for slowing the rate of descent of said tester into said stock as it approaches the bottom of its travel to prevent detrimental jarring 01' said tester.

9. The method of determining the freeness of paper stock, comprising the steps of continuously supplying paper stock to be tested to a receptacle and maintaining it therein at a constant level and in continuous motion, immersinga freeness tester into'said stock to a predetermined depth and at a predetermined rate, allowing said tester to remain in said stock until the result of said test has become known and recorded, then withdrawing said tester from said paper stock and thereafter repeating the aforesaid steps at predetermined time intervals.

10. The method of determining the ireeness of paper stock, comprising the steps of continuously supplying paper stock to a receptacle and maintaining it therein at a constant level and in continuous motion, immersing a freeness tester into said paper stock at predetermined time intervals and to a fixed depth and at a predetermined rate,

and at a predetermined rate, allowing said freeness tester to remain in said paper stock until the test is completed, recording the result of said test; and finally removing said freeness tester from said paper stock and at the same time cleaning it of paper stock which may have accumulated thereon during the making of the test.

12. Means for testing and recording the free! ness of paper stock, comprising a receptacle containing'paper stock to be tested, means for maintaining the level of said paper stock in said receptacle at a constant point at the time of each test, an immersion type freeness tester comprising a perforated element, a tube within said element for receiving liquid that may pass through 'said perforated element, a resistance element movable vertically within said tube, means .for recording the result of each test made by said freeness tester on said paper stock in accordance with the vertical movement of said resistance element under the influence of a rising column of liquid within said tube, and means for automatically conducting a series of uniform tests at predetermined intervals by the introduction of said tester into said paper stock to a predetermined depth and at a predetermined rate.

13. Means for testing and recording the 'freeness of paper stock, comprising a constant level flow box containing continuously moving stocin, means for progressively forming a single verticallydisposed mat within said stock, means for maintaining said mat in a fixed position within said stock for a time long enough to complete a test, said mat forming means being in the form of a screen through which water may pass, means for measuring and recording the relative rates of flow of water through successively formed individual mats while said mats are held stationary in said stock, and means for returning the material of each mat and the water whose flow has been measured to said flow box.

the rate of flow of water through said mat want out removing anylwater from said flow box, and means for causing operation of said recorder for recording the rate of flow through each individual mat so formed. I

15. In combination with a constant level flow" box through which paper stock tov be tested isflowing, mat forming means, means for'immersing said mat forming means in said stock thereby to cause theautomatic progressive formation thereonof an individual mat of paper stock of determined area, means for measuring and recording the rate of fiowof water through the paper stock as it is progressively developing as a mat on said mat forming means. said mat forming means so constructed that removal from said paper stock will cause the return of saidmat and the water whose flow has been measured through e reversal of water flow, to said flowbox, and cans for causing the periodic immersion and removal of said mat forming means into and out of said paper stock to be tested.

ARTHUR BROOKS GREEN.

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