US2423257A - Fluid operated tube cleaner with flushing means - Google Patents

Description

July l, 1947. D. E. SCHOTT ETAL FLUID OPERATED TUBE CLEANER WITHFLUSHING MEANS Filed, May l, 1943 ATTO RN EYS Patented July 1, 17.9427

FLUID OPERATED TUBE CLEANER WI'H FLUSHIN G MEANS Donald Edward Schott, Flushing, N. Y., and Daniel H. Crepeau, East Braintree, Mass., assignors to Thomas C. Wilson, Inc., Long Island City, N. Y., a corporation of New York Application May 1, 1943, Serial No. 485,390

1 Claim.

This invention relates to tube cleaning appar ratus used for removing deposits and incrustations from the interior of the tubes. More particularly, the invention resides in la novel tube cleaning apparatus which operates eficiently on both hard and soft deposits and may be employed in tubes that are warped or distorted without doing injury thereto. The new apparatus is especially adapted for cleaning small diameter tubes and its application for that purpose will, accordingly, be described in detail for purposes of explanation.

Small diameter tubes ranging from about to about 11/2" or larger in inside diameter are commonly used in many types of apparatus, such as heat exchangers, preheaters, condensers, coolers, economizers, etc., in order to obtain efficient heat transfer. Such tubes are made of both fer- Tous and non-ferrous metals and, in many instances, for example, the oil industry, alloys and alloy steels are used for the tubes. Such tube materials are all critical at the present time, so that it is now more important than ever that tube replacement bereduced to `a minimum.

In many forms of apparatus including small tubes, such as condensing and cooling equipment used in chemical and power plants, salt or hard water is frequently employed as the cooling medium passing through the tubes, while in other forms of apparatus used, for example, in the oil industry, the tubes often contain liquid hydrocarbons. In both ca-ses, deposits and incrustations form on the inner walls of the tubes during the use of the apparatus and often accumulate to such an extent as to plug the tubes completely. The formation of deposits Within a tube reduces the rate of heat transfer through its walls, so that the deposits should be periodically removed and, of course, when a tube is plugged up, it must be cleaned or replaced promptly.

Heretofore, the problem of cleaning small diameter tubes has not Ibeen satisfactorily solved, and salthough apparatus for the purpose is available, it is of limited application. Thus, the present commercial apparatus for cleaning small tubes will function only on soft deposits in straight tubes. Accordingly, when small tubes are badly warped or partly or wholly plugged with a hard deposit, they cannot be cleaned by such equipment and up to now, it has been necessary to remove and replace them.v Such operations are expensive, not only because of the labor and materials involved but also because of the loss of operating time of the apparatus containing the tubes. Also, the lack of apparatus for cleaning small tubes has made it necessary, in many instances, to instal additional units of equipment so that one unit may operate while another is out of operation Ito permit replacement of its tubes.

In our study of the problem of providing an apparatus capable of cleaning small tubes, We have found that the unsatisfactory performance of the cleaning apparatus now available arises from a number of factors. The equipment includes aslow speed motor operating at from about 900 to 1250 R. P. M. and with high torque. The motor drives a shaft carrying a drill bit which is l inserted in the tube and, because of the high torque of the motor, the shaft necessarily is of considerable rigidity. Also the bit lits the inside of the tube fairly closely. Because of the rigidity of the shaft, it will not conform to any considerable irregularity of the tube, so that with the drill bit fitting relatively closely in the tube, any attempt to clean a warped tube with such apparatus is liable to result in damage to the tube wall, particularly when the tube is made of nonferrous material. Such apparatus is sometimes provided with means for introducing a fluid, usually water, into the tube during cleaning but the Y fluid serves merely to carry away debris that has been broken loose by the drill and lies behind it.

The present invention is directed to the provision of an apparatus for cleaning small tubes, whether straight or Warped, and regardless of the nature of the deposit or incrustation therein. The new apparatus operates eiiciently under varying conditions of use and its satisfactory performance results from the application of principles quite different from those employed in present equipment for the same purpose.

rlhe new apparatus includes a high speed motor driving a hollow shaft on the end of which i-s mounted a cutter bit. The shaft is of considerable flexibility sumcient to permit it to conform to the irregularities of warped tubes and the cutter is not a close fit within the tube. The cutter is constructed to cut substantially entirely on itsforward face and it has blunt peripheral portions opposed to the inner Wall of the tube, so that it will not do damage to the wall when it comes into contact therewith. Since the cutter is driven at high speed and will, accordingly, function satisfactorily, although of substantially less diameter than the tube, the clearance between the cutter and tube wall facilitates the passage of debris pas-t'the cutter.- The removal of debris is promoted by meansof a fluid which is introduced into the hollow shaft and escapes t merging one into the other.

at the cutting end of the cutter centrally of the cutting edges. The fluid thus flows through the cutting zone and effectively washes away refuse and also keeps the cutter cool.

The new apparatus includes a motor of novel construction and various other new features referred to in the following detailed description. For a better understanding of the invention, reference may be made to the accompanying drawing in which Fig. l is a plan view of the cdmplete apparatus with certain parts broken away;

Fig. 2 is a longitudinal vertical sectional View through the motor,

Figs. 3, 4, and 5 are sectional views ori the-lines 3 3, 4 4, and 55, of Fig. 2; Y

Fig. 6 is a plan View on an enlarged scale of one form of cutter used in the apparatus;

Fig. '7 is an end view of the cutters shown in Figs. l and 6; and

Figs. 8 and 9 are end and partial side views, respectively, of a modified cutter.

Referring now to the drawing, the apparatus in the form illustrated comprises a motor generally designated I and having a spindle or shaft II to which a hollow shaft I2 is connected by means of a shaft support I3. A cutter or bit I4 is mounted-on the end of shaft I2.

The motor I!! is of the high speed type and preferably one having a free speed ranging from about 6000 R. P. M. to 7000 R. P. M. and it is capable of driving the shaft and bit during operation at speeds ranging from about 2500 R. P. M. up to 4000 R. P. M. The lower speeds occur when the apparatus includes a cutter suitable for use in tubes of about 11/2 inside diameter, while the higher speeds occur with smaller bits. A motor embodying the general features of that disclosed in Schott Patent No. 2,222,689, issued November 26, 1940, is entirely satisfactory for the purpose and such a motor is illustrated in the drawing.

The motor includes a casing I5 provided with diametrically extending arms I6 and a top boss il in which an eyebolt I8 is threaded, the bolt permitting the motor to be supported by a block andV tackle from a trolley while it is in use. The casing I5 is a casting carrying a hollow hub I9 at one end and containing a liner 20, which is formed with three bores in parallel relation and Mounted axially within the liner is a cylindrical rotor 2|, the main body of which has a radius substantially equal to the radius of the central bore. The rotor lits closely in the central bore so that two crescent shaped chambers 22 are formed on opposite sides of the rotor. At its forward end, the rotor is provided with the integral spindle or shaft II which extends through a bushing 23 in the hub I9. The shaft Il is threaded at Ila and the shaft support I3 mounted thereon. The shaft I I extends through a wear plate 24 within the casing, the wear plate lying at the forward end of the liner 28 and being held against rotation relative thereto by pins 25 seated in recesses in the end of the liner and passing through the wear plate.

At its rear end, the rotor is formed with an integral shaft or spindle 26 which fits within a rear bushing 2l within a journal 28 closed by a cap 2'9 threaded thereon. The journal has a flange seated against the rear end of the liner and it is held against rotation relative thereto by pins 30 entering recesses in the journal ange and liner, respectively. y

To the rear of the journal is a retainer and valve body 3l, the forward end of which is hollow and has an edge bearing against the vertical ange. This body contains a piston valve 32 having an axial bore in which is seated one end of spring 33, the spring bearing against a seat in the valve body 3| and tending to force the piston valve outwardly. The retainer and valve body is provided with a hollow internally threaded boss 34 by which the driving fluid, usually compressed air, is introduced into the valve chamber. The piston has a circumferential channel 35 in its outer surface and when the valve is in its closed position, the passage through the boss leads to the channel but cannot escape therefrom. When the valve is moved inwardly against the force of the spring, the channel permits communication between the inlet passage through the boss 34 and passages 36 leading into the space within the hollow forward end of Valve body 3| around the rear journal.

The valve is operated by a stem 3l passing through a valve bonnet 38 closing the rear end of valve body 3| and held in place by a retainer bolt 39 threaded into a cross brace 40. The stem 31 has an enlarged head normally bearing against the inner end of bolt 39 and the stem can be forced inward to open the valve by a control lever pivoted on the cross brace at 4| and having a pair of control handles 42a., 42h and an operating anm 43 bearing against the end of the stem projecting through bolt 39.

The bushing 21 within journal 28 is provided with diametrically arranged inlet openings 44 aligned with similar openings in journal 28. The rotor is provided with a plurality of radial slots 45' in which are mounted blades 46 and the slots have extensions 45a in rear spindle 26, which register with ports 44 as the spindle rotates. The construction is that disclosed in Schott Patent No. 2,222,689 and, as there explained, the arrangement is such that the driving fluid admitted through the ports 44 flows into the slots through the extensions thereof in the rear spindle and causes the blades to be forced radially outwardly from their slots. The air escapes from the slots on the trailing side of each blade into one or the other of the crescent shaped chambers 22 and acts on the blades to cause rotation of the rotor. The liner 20 is provided with a pair of diametrically disposed exhaust passages 4l extending longitudinally thereof, and each passage is connected to one of the crescent shaped chambers through suitable ports. As each blade passes one set of ports, the space to its rear between it and the next blade is in communication with an exhaust chamber and the fluid escapes into the chamber. The exhaust chambers 41 extend lengthwise in the liner and through the wear plate 24 into a circumferential channel 48 in an exhaust member 49 containing a journal bushing 5D. The channel 48 leads to anv exhaust passage in a boss 5I formed on the casing I5.

The forward spindle I I` has a longitudinal passage 52 therethrough which is provided at its inner end with a radial bore leading to an annular chamber 53 between bushings 23 and 58. Fluid for flushing debris from the tube is introduced into the chamber 53 through a threaded inlet 54 in boss 5I and the fluid enters passage 52 and flows therethrough into the hollow shaft I2. In order to take care of any leakage of the fluid from chamber 53, the bushing 23 is provided with a shallow internal channel 55 spaced forwardly of chamber 53, and the channel is aligned with and has an opening into a passage 56 ,in the wall of the casing which leads into the exhaust passage in boss l. Bushing 59 in the exhaust member 99 has a forwardl end of slightly reduced diameter seated against a shoulder at the forward end of the bore through the exhaust member and slightly to the rear of the shoulder, bushing 59 is provided with an internal circumferential channel through which iiuid escaping from chamber 53 may collect to flow away through an opening in the bushing into a passage 57 formed in the wall of the casing and leading to the exhaust passage in boss 5|.

The shaft i2 is made up preferably of a number cf hollow sections and, since some whipping of the shaft is desirable, the sections must be secured together and the first section must be connected to the shaft support i3 by connections which will withstand such action. In the construction shown, the support i3 is provided with a cylindrical bore of considerable length at its free end and rearwardly thereof, it is formed with tapered threads 59 into which similar threads on the first shaft section can be screwed. At its forward end, the first shaft section is provided with an internal tapered thread of considerable length and the second section is similarly threaded, the threaded joint so formed having substantially the full strength of the shaft without increasing the outer diameter thereof or decreasing the diameter of the passage therethrough. v

At the outer end of the last shaft section is mounted a cutter bit and the cutter shown in Fig. 1 is of the single type, while a double cutter is shown in Fig. 6. Each such cutter has a passage 59 extending therethrough from end to end through which fluid for flushing debris may pass from the hollow shaft to the end of the cutter where the cutting action takes place. Each cutter has a tubular extension 69 having a long tapered thread 9| which may be introduced into the internally threaded end of the last shaft section. At its forward end, each cutter is provided with projections 52 having end cutting edges 93 and blunt peripheral surfaces 94. The cutting edge of each projection extends generally radially of the cutter and each projection has a pair of faces, one of which, designated 95, is of spiraling shape, while the other, 99, is radial.

The bit shown in Fig. l is intended for use in tubes which are solidly or almost solidly plugged with extremely hard deposits and, for cleaning such tubes, the apparatus may be provided with a device for reciprocating the bit, such a device being disclosed in the co-pending application of Donald E. Schott, Serial No. 487,057, led May 14, 1,943, now Patent No. 2,352,019, issued June 20, 1944. In a cutter bit for operation under the conditions mentioned, the diameter of the central passage 59 should b-e slightly smaller than the clearance between the bit and the inner wall of the tube to be cleaned. This lclearance is illustrated in Fig. '7 in which the inner diameter of the tube is indicated at 67 and the clearance between the bit and the inner surface of the tube indicated by the space A between the arrows. The space B between the arrows, which indicates the diameter of passage 59, should be slightly smaller, as, for example, 3-12- of an inch smaller than the clearance A. When this relation between the diameter of the passage and the clearance of the bit in the tube is maintained, the building up of a central core of deposit within the passage 59, as the cleaning operation proceeds, is prevented.

6 Such a core would plug passage 59 and prevent the escape of the flushing fluid.

In a bit for use with apparatus equipped with a reciprocating device above mentioned, it is desirable to have a relatively few teeth so that the vibrating blows will be effected to cause the bit to bite into the deposit. Under such conditions, the progress of the bit will be relatively slow and the blunt area or lands 64 immediately behind the cutting edges are made greater than would ordinarily be the case to eliminate the possibility of damage to the tube wall arising from the high speed rotation of the bit in the restricted space.

The bit shown in Fig. 6 is double ended and has a second set of projections, generally designated 68, the cutting edges of which lie to the rear. This cutter may best be employed in tubes in which the deposit is soft, gummy, or tarry and does not readily clear itself from the tube after having been freed from the tube wall. Such a deposit has a tendency to build up around the shaft to the rear of the cutter bit and may slow down or stall the shaft. When the double bit is employed, a cutting action may be obtained with the bit moving either forwardly or to the rear. The double ended bit greatly facilitates removal of deposits of the character described.

The bit shown in Figs. 8 and 9 is generally similar to that shown in Fig, 1, except that it has double the number of projections. This type of bit may be used for the same purposes as the bit shown in Fig. 1 but will not be quite as efficient l when reciprocated because the force of the blows on the deposit will be distributed over twice the area and will, therefore, be less intense. In the bit of Figs. 8 and 9, the projections 69 are of the same general form as the projections 62 but are necessarily thinner and the lands 10 on the projections 69 are smaller. The bit of Figs. 8 and 9 is preferred for use in cleaning tubes in which the deposit may be hard but not very thick. In such a cleaning operation, the bit of Fig. 1 would be likely to wear rapidly at the corners of the projections by reason of the concentration of Wear at these points, whereas when the bit of Figs. 8 and 9 is used in such an application, the presence of the greater number of teeth distributes the wear and increases the life of the bit. The bit of Figs. 8 and 9 is also entirely satisfactory for cleaning tubes in which the deposit is not suiiiciently hard to require the use of a reciprocating parts, the retainer and valve body will be placed with the inlet passages through boss 34 in the desired position. The crossbar 40 in which the retainer bolt 39 is mounted is held in place by retainer rods H passing through arm I6 on the motor casing and through slots 12 in the crossbar. When the motor is to be disassembled, the retainer bolt 39 is backed out of -the crossbar suniciently to permit removal of the valve bonnet 38. The crossbar is then moved forwardly on rod 'Il and lifted free. The retainer, the Valve body, and all the other parts contained within the motor casing can then be readily slipped out of' the casing.

The valve 32 provides a delicate control of the motor, since the valve is balanced and can be moved in small steps by the control lever, Also, the forward wall of channel 35 is slightly beveled at 13 to permit opening of the Valve to very limited extents and thus give precise control.

It will be apparent from the foregoing that the new apparatus differs from that heretofore employed for cleaning small tubes in that it includes a high speed motor, a relatively ilexible shaft, a cutter bit which can cut the deposit only and has'blunt surfaces opposed to the tube wall, and means for supplying fluid directed at the plane of the cut for washing away the debris dislodged. The motor employed in the new apparatus perates at speeds much greater than those used in the prior apparatus and, since reliance is placed on speed for effecting the cleaning, the shaft can be much less rigid than that employed in the prior apparatus. As a result, the shaft will conform to the irregularities of Warped tubes ordinarily encountered and in cleaning such a tube, the inner wall thereof is not damaged because of the blunt surfaces on the cutter pro-- jections exposed to the wall. With the uid discharged at the end of the bit and centrally of the cutter projections, the iluid can only escape by [lowing backwardly between adjacent projections. This insures a good flushing effect and also results in the cutter beingv thoroughly cooled at all times. The introduction of the iluid into the hollow shaft through the motor spindle by a passage in the motor casing avoids the inconvenience and danger that would be involved in the use of a gland outside the motor casing and surrounding the hollow shaft. Such a gland might seize and whip about the revolving shaft with consequent damage to the fluid supply line. With the construction disclosed, any possible objection to introducing the fluid into the shaft through the motor casing is overcome, since leakage of the fluid is taken care of by causing it to be trapped in the passages in the bushings and carried off through the motor exhaust line.

The use of the balanced valve with the beveled surface l'I3 makes operation of the apparatus easy, since the eifort required to control the valve is constant regardless of line pressure and the operator has a sensitive control of the motor at all times. This is particularly desirable during the initial operation of cleaning a tube which is completely plugged since, in that situation, the operator has to make an opening in the deposit or start the cleaning of the tube without having the benefit of the tube wall to assist him in steadying the cutter.

We claim:

In a tube cleaning apparatus, a motor comprising a casing, a rotor within the casing, a spindle connected to one end of the rotor and extending out of the casing, a chamber within the casing surrounding the spindle between the rotor and the free end of the spindle, a passage through the spindle from the chamber through the free end of the spindle, means for supplying fluid to the chamber to escape through the passage, a pair of channels within the casing encircling the spindle on opposite sides of the chamber for collecting fluid which may escape from the chamber along the spindle, and an exhaust passage communicating with the channels.

DONALD EDWARD SCHOTT. DANIEL H. CRE-PEAU.

REFERENCES CTED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 2,233,163 Fosnot Feb, 25, 1941 2,250,368 Good July 22, 1941 1,044,920 Schilow Nov. 19, 1912 940,150 Hauer Nov. 16, 1909 1,208,203 Plimley Dec. 12, 1916 2,081,919 Gartin June 1, 1937 1,355,726 Zlatnik Oct. 12, 1920 1,477,563 Hirschfeld et al. Dec. 18, 1923 1,940,220 McGrath Dec. 19, 1933 1,263,143 Sturtevant Apr. 16, 1918 966,998 Carlson Aug. 9, 1910 1,607,559 Pekovich Nov. 16, 1926 2,038,004 Russell Apr, 21, 1936 1,837,904 Hanelt Dec. 22, 1931 1,193,361 Crepeau Aug. 1, 1916 FOREIGN PATENTS Number Country Date 422,574 Germany Dec. 3, 1925

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