JPH04330389A - Method of monitoring displacement type pump and abrasion thereof and method of balancing delivery screw thereof - Google Patents

Abstract

PURPOSE: To provide an improved screw pump which has extremely reduced wear between a static member and a rotating member and can operate at a high speed for a long time. CONSTITUTION: A displacement pump having a single or two screws 2 is disclosed, screw flights 34, 36, 38, 40 are arranged on its outer surface, balance holes 82 which can be filled with material with density lower than that of the screw flights are provided, and each hole can be closed by a cap 84 having the outer surface as high as that of an adjacent flight. A wear measuring port 86 into which a measuring device for measuring relative wear between the corresponding screw flight and a pump casing for each screw flight can be inserted is disclosed. Selectively, a proximity sensor 98 is arranged in the measuring port, and, during a pump operation, can dynamically detect the wear of the corresponding flight.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to pumps and pumping methods. The present invention relates in particular to pumps operating at high pump speeds when pumping especially large volumes of low viscosity liquids.

0002

BACKGROUND OF THE INVENTION High-speed operation of pumps as used herein means an operating speed of at least 500 revolutions per minute (rpm), preferably at least 900 rpm, particularly preferably at least 1200 rpm. It is also expected that the pumps disclosed herein can be operated at constant speeds within the range of about 1500 rpm to about 1900 rpm.

It is known to pump highly viscous products such as pastes, creams, oils, etc. using positive displacement pumps having two screws rotating in opposite directions.

It is also known to pump low viscosity fluids, such as water, at high speeds and in large quantities using pumps that are not generally considered positive displacement pumps.

[0005] In the paper industry, for example, 50
Part-liquid, part-gas, such as foamed liquids containing up to 80% air and optionally some solid materials2
It is known to use fan pumps to pump three phase media. Expanded fiber furnishes containing solid cellulose fibers used in papermaking processes are described, for example, in U.S. Pat. No. 4,443,2 to Cheshire et al., incorporated herein by reference.
It is well known as disclosed in No. 97. Delivering such multiphase foaming media presents several problems due to increased pump speed, flow rate, and delivery pressure. When using conventional fan pumps, because the foaming medium is compressible, an increase in flow rate does not result in a corresponding increase in pump speed.

[0006] Therefore, in order to achieve efficient delivery of larger volumes and higher pumping speeds, Applicants have found it advantageous to use positive displacement pumps to deliver such foaming media. I learned. Such pumps have traditionally been used for pumping products of high viscosity, such as those that provide some fluid lubricity between a stationary pump casing and a moving impeller (e.g. a screw). .

An advantage of such positive displacement pumps is that they generally form an isolated batch of media to be pumped, isolating this media batch at a pressure approximately near the inlet pressure, so that the foaming media batch is at the inlet. It is pumped in a generally predictable amount from the pump to the outlet, and the pumped volume, as measured at the pump inlet, is approximately linearly related to the operating speed of the pump.

[0008]

The applicant has discovered that when the above-mentioned foaming medium is delivered at, for example, 900 rpm, a pressure pulse is formed by the pumping action, which pressure pulse is transmitted via the outlet of the pump. I learned. The fluid within the isolated and pumped cell is at a pressure generally below the outlet pressure of the pump. When the outlet is reached, the outlet pressure of the fluid suddenly flows into the open cell, compressing the fluid within the cell. The sudden influx of fluid into the newly opened cell causes a sudden and temporary change in the pressure at the pump outlet. This pressure change is transmitted from the pump via the pump outlet as a fluid pressure pulse in a closed pressurized system downstream of the pump.

[0009] Such pressure pulses have little effect on operations solely for the purpose of conveying the medium, but when the pump output is closely related to the formation of the web during the papermaking process, such pressure pulses , which directly affects the uniform flow rate of the furnish to the papermaking fabric and thus affects the machine direction uniformity of the paper so produced.

[0010] The applicant has also discovered that some conventionally manufactured screw-type positive displacement pumps have a weight ratio of about 1% to about 4% by weight.
It has been found that operating at a rated speed of 900 rpm for extended periods of time to pump the three-phase media described above containing 50% cellulose fiber results in excessive wear. For example, 0.5 mm (0.5 mm) between the rotating delivery screw and the stationary bore.
A typical pump with a design clearance of 1.0 mm (0.020 inch) reaches a clearance size of 1.0 mm (0.040 inch) when measured after only 3 hours of continuous operation.

It is an object of the present invention to provide an improved screw pump that can operate at high speeds for extended periods of time with significantly reduced wear between the stationary and rotating members.

Another object is to provide a means of measuring the wear of parts of a pump without removing the movable member from the stationary member.

Yet another object is to provide a means for monitoring the wear of pump components over time without removing the movable members from the stationary members.

Yet another object is to provide a method for monitoring pump component wear without removing the movable member from the stationary member.

Yet another object is to provide a pump capable of pumping low viscosity fluids with high velocity actuation of low amplitude pressure pulses.

Yet another object is to provide a pump capable of pumping low viscosity fluids at high speeds of operation with small pressure changes.

Yet another object is to provide a method for pumping low viscosity fluids at high rates of low amplitude pressure pulses.

Yet another object is to provide a method for pumping low viscosity fluids at high speed operation with low pressure changes.

Yet another object is to remove material to equilibrate without increasing leakage between the high pressure outlet end of the screw and the low pressure inlet end of the screw, or the typical 360° To provide a method for balancing the screw of a screw pump without reducing the pumping function of the screw and without significantly weakening the screw over rotation.

[0020]

[Means for Solving the Problems] The present invention provides an entrance (14)
and an outlet (16), and an outer casing (12) provided with an inner passageway (18) connecting the inlet and the outlet and in which a bore (20) is formed; a screw flight (34) extending along and radially outwardly from the shaft and having an outer surface (32) formed between a front surface (60) and a rear surface (62) of the flight; a delivery screw (22) with flights (34);
a positive displacement pump comprising a bearing (46, 52) supported within the casing and rotatably mounted such that the shaft can extend axially within the bore; said screw flight has one or two pumps arranged with respect to said bore such that the gap therebetween is sufficiently small to facilitate efficient delivery of material through said bore by said screw; The present invention relates to a positive displacement pump characterized in that the above-mentioned holes (82) are formed to reduce the tendency of the above-mentioned screw to become unbalanced during operation of the pump.

In one embodiment of the pump of the invention, the casing passageway (18) is connected to the bore adjacent to each end thereof, and the outlet is connected to the bore at a position substantially midway between the ends; The shaft is provided with two spaced apart screw flights that connect to the outlet from respective locations adjacent opposite ends of the bore to direct fluid from the inlet to the outlet of the casing. It extends towards its said position so that it can be delivered. Each of the above screw flights includes:
One or more holes (82) are provided which reduce the tendency of the screw to become unbalanced during operation of the pump.

In another embodiment of the pump according to the invention, first and second similar delivery screws (22, 24) arranged in parallel and rotatably mounted within said bore are provided, the screw flights of which are inserted into each other,
Each of the screw flights has an outer surface (32) formed between a front surface (60) and a back surface (62) thereof, the outer surfaces (32) of the flights having a sufficiently small gap therebetween; The screw is positioned relative to the bore to facilitate efficient delivery of material through the bore. Each of the screw flights is provided with one or more holes (82) that reduce the tendency for imbalance.

The present invention provides an inlet (14) and an outlet (16)
, and an outer casing (12) connected to the inlet and outlet and provided with an inner passageway (18) in which a bore (20) is formed, a shaft (28) and a shaft (28) fixed to and along the shaft. a screw flight (34) extending and extending radially outwardly from the shaft;
) and an outer surface (32) formed between a front surface (60) and a rear surface (62) of the flight.
22) and bearings (46, 52) supported within the casing and rotatably mounted such that the shaft can extend axially within the bore, the outer surface of the flight being at least one measurement port (86) in an outer casing disposed with respect to said bore such that the clearance is sufficiently small to facilitate efficient pumping of material through said bore by said screw; Extending through the casing and into the bore, the outer surface (32) of said flight is located opposite said port, thereby allowing a measuring device to be operated through said port and to reduce the relative wear of said screw and bore. This invention relates to an outer casing characterized by being able to be measured. If the delivery screw is provided with respective flights at each end, at least one measurement port (86) extends through the casing (12) into a bore adjacent to each flight of said delivery screw, and extends from the outer surface (32) of each flight. ) is located opposite said port, thereby operating a measuring device through said port;
The relative wear of the screw and the bore can be measured. Furthermore, if the pump is a two-screw pump, at least one measurement port (86) extends through the casing (12) into a bore adjacent to each flight of each delivery screw and extends from the outer surface of the corresponding flight. (32) is located on the opposite side thereof, so that a measuring device can be operated through the port to measure the relative wear of the screw and the bore. instead of operating a wear measurement device through each of the wear measurement ports, a proximity sensor is placed within the wear measurement port to detect wear on the corresponding pump delivery screw flight, and the wear measurement port is closed and substantially sealed; Normal operation of the pump can be allowed.

The present invention relates to positive displacement pumps with single or dual screws, in which the outer surface of each screw flight is provided with an elongated hardened wear strip having a width less than half the width of said outer surface. It is. The width of the wear strip increases from one end of the corresponding flight adjacent the bore entrance to the other end such that the width at any given location is related to the amount of wear contact between the corresponding delivery screw flight and the bore. It is desirable to do so.

The present invention also provides an inlet (14) and an outlet (1
6), and the inlet and outlet are connected and the bore (20
) and a shaft (28) and a screw secured to and extending along and radially outwardly from the shaft. Flight (34
) and an outer surface (32) formed between a front surface (60) and a rear surface (62) of the flight.
22); and a bearing (46, 52) supported within the casing and rotatably mounted such that the shaft can extend axially within the bore, the positive displacement pump comprising: The pump is arranged with respect to the bore such that the outer surfaces of the flights are such that the clearance therebetween is sufficiently small to facilitate efficient delivery of material through the bore by the screw. If the pump screw has flights at both ends,
or if two screws are present, each delivery screw flight has a fluid pressure supply port (116) disposed within said casing at the higher pressure pump delivery fluid pressure end of said delivery screw flight; a fluid pressure feedback control system (119) comprising a fluid pressure receiving port (104) disposed within the casing between the ends of the delivery screw flight and a conduit (112) connecting the fluid supply port to the fluid receiving port; ) is provided. In both versions of the invention, the bore of the casing is provided with a gradually increasing cross-sectional area in the direction towards the pump outlet (16) of that part facing the part of the discharge end of each flight. I can do it.

The present invention provides a method for monitoring wear in a positive displacement pump provided with one or more wear measurement ports, comprising the steps of: locating the outer surface of each screw flight opposite the corresponding measurement port; inserting a measuring device into said corresponding measuring port and using said measuring device on a surface (32) of a flight facing said corresponding measuring port;
and measuring wear of the device.

The present invention provides a method for monitoring the wear of a positive displacement pump provided with one or more wear measurement ports, including the steps of arranging a proximity switch in each measurement port and closing each wear measurement port. and by sealing and allowing normal pump operation with said sensor located within each measurement port, and by detecting a change in distance between said sensor and the outer surface of the corresponding screw flight. monitoring the wear of the outer surface of the screw flight opposite the sensor during operation of the pump with a sensor.

The present invention balances the delivery screw of a positive displacement pump by locating the unbalanced angular position of the screw along its periphery and removing material at said position to alleviate said imbalance. The method further relates to the method. Removal of said material is preferably accomplished by forming one or more holes (82) in each screw at said unbalanced location extending inwardly from the outer surface (32) of the screw. It is desirable to form a cap over each hole having an outer surface disposed flush with the outer surface of an adjacent screw. If desired, the holes can be filled with a less dense material than the adjacent screw flights.

[0029]

[Embodiment] First, referring to FIGS. 1 to 4, a pump 1
0 includes an outer casing 12 having an inlet 14, an outlet 16, and an internal passageway, generally designated 18, that traverses the casing 12 between the inlet 14 and the outlet 16. The internal passageway 18 is connected to a pair of delivery screws 22, 2.
4 is provided within the bore 20. The cross-section of the bore 20, and thus the space defined therebetween, is defined by the inner surface 26 at any given point along its length. The bore 20 further includes an outer surface 27 and a wall 29 between the inner surface 26 and the outer surface 27.

The delivery screws 22 and 24 are connected to the shaft 2
8 and 30, respectively. Each of these shafts has a longitudinal axis 33 extending along its length. screw 22,
24, as shown in FIG.
It further includes a large perimeter 31 defined by an outer surface 32 of 0 . In the illustrated embodiment, each of the shafts includes a pair of oriented and mounted flights at opposite ends thereof.

[0031] The packing boxes 42 and 43 are the outer casing 1.
2 and accommodates packing seals 44 and 45. These packing boxes 42, 43 support the screws 22, 24 over the bearings 46, 48, 50, 52, with seals 44, 45 between the bearings and the delivery chamber generally defined by the internal passageway 18. will be placed in These bearings and seals can of course be placed in reverse positions and used to deliver material capable of lubricating the bearings.

A gear box 54 is attached to the right end of the right packing box 43 and houses gears 56, 58, which are preferably integral parts of the respective screws 22, 24, as shown. These gears 56, 58 are
The teeth of gear 56 mesh with the teeth of gear 58 such that a motor or other prime mover (not shown) causes shaft 2
8 rotates the screws 22, 24 in opposite directions, thereby positioning one of the screws 22, 24 to rotate clockwise and the other screw counterclockwise.

Each of the screw flights extends radially and longitudinally about a respective shaft and extends outwardly from the shaft to the outer surface 32 of the respective shaft. Each of the flights includes a front face 60 disposed toward the exit 16 and a rear face 62 disposed away from the exit 16 .
defines the thickness of each flight between and at any point along the length of each flight. At any point along a given flight, the flight has a height "H" measured between the respective shaft 28 or 30 and the respective outer surface 32.

Pumping cell spaces 64, 66 are defined between the shaft 28 and the outer surface 32 of the flights 34, 38 between the front and rear facing portions of each flight 34, 38. A pumping cell space 68, 70 is defined between the shaft 30 and the outer surface 32 of the flights 36, 40 and between the opposing front and rear surfaces of each flight 36, 40.

As is apparent from the combined teachings of FIGS. 1, 2, and 4, the design and placement of the screws allows flights 34, 36,
38, 40 mesh between the shafts 28, 30 such that the flights 34, 38 of the screw 22 reach into the pumping cell space 68, 70 above the screw 24 and the cell space 68, 70 between the shafts 28, 30. Almost sealed. Similarly, flights 36 above screw 24
, 40 extend into the pumping cell space 64, 66 above the screw 22 and substantially seal the cell space 64, 66 between the shafts 28, 30. The thickness of the flights and the corresponding front and back spaces above adjacent flights (width "W" of the cell space) cooperate so that the gap between the flights of an intermeshing screw is smaller than that of the flights of one screw. is small enough to act as an effective lid for the opposite screw cell space where it interlocks between its shafts of the screw.

The outer surface 32 and bore 20 of each flight
The gap between the bore 20 and the bore 20 is sufficiently small and long enough.
water, foaming liquid (e.g. 50% by volume)
This can facilitate the efficient delivery of low viscosity materials, such as those containing 80% to 80% air) and the same media within which papermaking fibers are dispersed. Typical gaps are about 0.5 to about 1.0 mm (about 0.02 to about 0.0 mm).
4 inches). A typical seal gap is usually effective for at least one full revolution of each flight, thereby effectively isolating the inlet end of the flight from the outlet pressure at the outlet end of the flight.

The engagement of the screws between the shafts 28, 30 causes the delivery cell spaces 64, 66, 68,
Closing 70 results in at least one and preferably a plurality of isolated and distinct delivery cells 72 being defined for each flight of each screw. Opposing flight (e.g. 36)
between the respective shaft (e.g., 28) and the adjacent inner surface 26 of the bore 20, such that the delivery cell space (e.g., 64) rotates approximately one revolution while the delivery cell space (e.g., 64) extends into the delivery cell at the screw engagement position. a delivery cell space (e.g. 64) between opposing front and rear portions 60, 62;
Each sending cell 72 is formed within. Thus, each of the delivery cells rotates approximately one revolution (slightly less) about the shaft between adjacent windings of the corresponding flight.
Stretch. The cell has a beginning and an end where the screw engages. Therefore, the sending cell has an inlet,
isolated from the exit and other cells. screw(
For example, when 22) is rotated in the delivery direction, the delivery cell moves along the screw to the outlet 16 at the center of the screw 22.
move forward towards.

[0038] The screw portion 74 within the internal passageway 18 is
A portion between seals 44 and 45 is provided. The part 74
has a first length in which the screw and the bore extend equally (within the bore 20), and a second length between the bore 20 and the respective seals 44, 45.

[0039] Screw flights 34, 36, 38, 4
0 begins with an inlet end positioned toward the respective packing seal 44 or 45 and terminates at an outlet end 78 positioned toward the outlet 16. The inlet end 76 of the flight can and preferably extends at least a portion of the distance between the bore 20 and the seals 44, 45. The outlet end 78 is shown in FIGS.
It is desirable to have a shape as shown in Figure 1 to reduce the pressure pulse of the fluid being delivered. The clearance between the outer surface 32 of the flight and the inner surface 26 of the bore extends to the exit end 78 of the flight over a portion of the same length where the bore and screw extend equally along the longitudinal axis of the shaft of each screw. It can be increased.

The embodiment shown in FIGS. 1 and 2 shows that over one 360° rotation of the flight on the shaft (FIG. 2), the gap between the outer surface of the flight at the exit end 78 and the inner surface 26 of the bore is Indicates that it increases.

The gradual increase in the gap between the outer surface 32 of the flight and the inner surface 26 of the bore indicates a gradual opening of the delivery cell to the working pressure of the outlet 16 of the pump, thereby causing the cell to The opening pulse effect is spread over a longer period of time, and the time is shorter than during high-speed operation of the pump, when the height of the flight reaches the edge from its full height at the periphery to the end. shorter than time. As a result, when delivering papermaking furnishes based on water or foamed liquids as disclosed herein, even at speeds as low as 900 rpm, approximately 50 p.p.
A pressure difference of si can be generated.

The state in which the gap gradually increases is shown in FIGS. 1 and 2.
, which shows that the dimensions of the bore 20 are constant and the height "H" of the screw flight gradually decreases at the exit end 78 of the flight. FIG. 3 shows another method of increasing the clearance, i.e. the flight height "H" is kept constant according to each large circumference 31 up to the exit end 78;
Alternatively, the height may be tapered over a relatively short distance while increasing the cross-sectional area of the bore 20 adjacent the exit end of the flight.

Of course, it is possible to vary both, so that the height of the flights is gradually lowered and the cross-sectional area of the bore is changed (increased or reduced) to correspond to the desired rate of change in clearance. You can.

[0044] At the higher speeds of operation envisaged for the pump of the present invention, screw imbalance is manifested by vibration and wear of the pump screws and bores. Therefore, it is desirable that the screw be in a balanced state. This balancing defines the unbalance angle (the radial angle about the shaft when the screw is heavy) and removes the appropriate amount of material from the flight to create the unbalance at the appropriate radial angle and location. This is achieved by reducing the balance so that the instantaneous efficiency of subsequent delivery operations is not reduced.

A preferred location for material removal is shown in FIG. The hidden hole 82 is approximately 2 of the distance between the bearings 46, 52.
5% (75% each), these holes reduce the tendency of the screw to produce one cycle of standing sinusoidal oscillations. Hole 82 is formed by removing a calculated amount of material, typically with a drill. As shown in FIG. 5, the hole 82 is preferably capped with a cap 84 that is welded in place over the hole, which is then machined or ground flat and the outer surface 32 of the flight so that it becomes an integral part of the Therefore, the counterbore hole 82 does not penetrate into the outer surface 32, thereby forming an isolated delivery cell by appropriately controlling fluid leakage between the outer surface 32 and the inner surface 26 of the bore 20. Does not affect functionality. The balanced holes can be plugged with a material that is less dense than the material of the flights used to form these holes.

As shown in FIG. 2, a wear measurement port 86 extends through the outer casing 12 from an inner end 88 of its inner surface 26 to an outer end 90 of the pump's outer surface. The wear measurement port 86 has a longitudinal axis 87 and is closed by a removable plug 92 that maintains the pump sealed during normal pump operation. The simplest plug 92
(left side of Figure 2) is typically threaded and is removed when the pump is not in use, then the measuring tool is connected to port 86.
through and to the outer surface 32 of each flight. For such applications, the screw should be
The outer surface 32 is connected to the hole 8 between the screw hole 86 and the shaft.
It is necessary to arrange it so that it is aligned with 6. The shaft 28 and the outside of the gear box or other suitable stationary surface are
Shaft 28 is marked at a compatible location as indicated by 94. As a result, by aligning the marks 94 on the shaft 28 with the matching marks on the outer surface of the gear box, the outer surface 32 of the flight is aligned with the wear measurement port 8 used for that purpose.
6 and become aligned.

The port 86 shown on the right side of FIG. 2 is closed by a plug 96 with a dynamic proximity sensor 98 connected to a monitoring device 102 by a signal carrier 100 (eg, a wire cable). pump is running,
Plug 96 is in place within port 86. As each screw rotates, the outer surface 32 passes the proximity sensor 98 so that a discrete signal is sent to the monitoring device 102, which monitors the pump for wear while the pump is in operation. becomes possible. An acceptable proximity transducer device comprising proximity sensor 98 and monitoring device 102 is available from Kaman Instrumentation Corporation, Colorado Springs, Colorado.
7200 Proximi, available from Trumentation Corporation.
tor).

By constantly inputting information from the proximity sensor in this way, the detected proximity is recorded over a certain period of time, and changes in proximity can therefore be detected to prevent pump wear or damage before an accident occurs. It is possible to indicate impending failure, so that a complex papermaking process (or any other process) can be shut down in an orderly manner and its maintenance, servicing or reassembly planned efficiently. .

Referring now to FIG. 4, fluid pressure receiving ports 104, pipes 106, valves 108, manifold 1
10, a pipe 112, and a fluid pressure feedback control system comprising a fluid supply port 116. The fluid pressure receiving port 104 is similar to the wear measurement port 86 and extends through the wall 27 of the bore 20 to the inner surface 26 of the bore.
Extends to. The ports 104 are typically spaced apart, with multiple fluid pressure receiving ports 104 opening into different delivery cells. Port 104 is connected by pipe 106 through valve 108 and manifold 110 to pipe 112, which is in fluid communication with high pressure portion 114 of bore 20 through fluid pressure supply port 116. By manipulating valve 108, fluid at the pump outlet pressure can be controllably and adjustably returned into the delivery cell, as indicated by pressure gauge 118, thereby
By allowing pressure to build up within the cell before fully opening to the exit pressure at the exit end of the flight, the pressure differential between the high pressure section 114 and the next cell to be opened can be reduced.

Similarly, higher pressure fluid, and thus fluid pressure, can also be supplied to any or each pressure receiving port 104 via the manifold 110 and respective valves 108. In this way, each sending cell (
e.g. 64) to gradually increase within a given cell as the fluid traverses the length of the flight, such that the pressure within the cell when the cell opens at the exit end 78 increases gradually as the fluid traverses the length of the flight. Pressure changes can be controlled and, if desired, minimized when the cell is opened to the outlet pressure. Because the pressure change at the exit end 78 of the flight is reduced, the pressure pulse associated with such pressure change is also reduced, thereby reducing vibrations and resonances caused in the downstream pipe due to the pressure pulse. As such, the pressure feedback control system 119 shown in FIG. 4 effectively reduces fluid stresses, particularly vibrational and resonant stresses in pumps, pipes, and other equipment downstream from the pump and subject to pump discharge pressure. becomes possible.

One pressure feedback system 119 for controlling the pressure along the flights 34 is shown in FIG.
It will be appreciated that a similar feedback control system is used for 0).

Resonances, vibrations, etc. of the operating system of which the pump is a part, caused by operating several components at high speeds, may cause valve 108 to operate to reduce the intensity of the pressure pulses generated by pump 10. Some mitigation can be achieved by varying the intensity and duration to provide dynamic vibration and dynamic control within the resonant environment. Additionally, changes in vibrations and resonances within the actuation system (e.g., changes in response to changes in pump speed) can cause the control valve to actuate to provide a changed optimal amount of fluid and feedback pressure.

[0053] The pump of the present invention has screws 22, 24
For example, if the gap between the and the bore 20 is 0.5 mm (0.02
The screws 22, 24 have bearings 46, 48, 50 near their ends.
52 so that the screw does not actually contact the inner surface 26 of the bore 20 due to vibrations and resonances. Additionally, the pumps that Applicant intends to use in papermaking processes are large, e.g., with a large circumference of 127 cm (50 inches) and a small circumference of 63 cm (63 cm).
．． 5cm (25 inches), bearings 46, 48 and bearing 50
, 52 is greater than or equal to 3.05 m (10 ft). Various forces exert bending moments on the screws 22,24. For example, the middle of the screw,
That is, the mass of material within the screws 22, 24 intermediate the support bearings centered about the location of the outlet 16 responds to gravity and creates an amount of deflection force. This deflection force contributes to the eccentricity of the rotation of the screw. As the screw rotates, it produces resonance, which contributes to the eccentricity of the rotation. Also, as taught in U.S. Pat. No. 2,463,460, the screw moves toward the outlet in a direction perpendicular to the length of the shafts 28, 30 when the pump is actuated. It becomes a trend.

When such a force is applied to the screws 22, 24, the screws engage the outer surface 32 of the flight and the bore 20.
There is some contact between the inner surface 26 of the Of course, the moment of hard contact is related to the mass of each screw and the speed of each movement. Therefore, the outer surface 32 is hardened to be effective in reducing screw wear. A suitable degree of hardening for the screws 22, 24 is shown in FIGS. 6-8.

In FIG. 6, a groove 120 is formed along the middle of the outer surface 32 of the flight and is filled with a wear-resistant material 122, such as tungsten carbide or stellite. The wear-resistant material 122 is mechanically locked in place by the overlapping material of the wedge 128 to prevent movement in a direction perpendicular to the longitudinal axis of the shaft 22. The wear-resistant material 122 can be conventionally applied by plasma arc. However, it is desirable to insert the preformed strand material 122 into the groove 120 and then lock the wear resistant material in place by slightly deforming the surrounding material and securing the lock to the wedge 128.

Approximately 1/1/2 of the total thickness of the outer surface 32 of the flight
Since less than 2 parts are occupied by the wear-resistant material 122,
The cost and difficulty of finish sanding the outer surface 32 to form a single, uniform surface as shown is greater than applying a wear-resistant material to the entire width of the outer surface 32 and then finish sanding that surface. is reduced. Mechanical locking at wedge 128 makes the preformed wear resistant material less expensive than the more costly conventional method of thermally spraying wear resistant material at location 43 as in U.S. Pat. No. 3,841,805. It becomes possible to use strips of flexible material.

Selectable placement locations and orientations are illustrated in FIG.
26 and trailing edge 124, and could be on either or both edges, but is preferably applied on the leading edge. At the leading edge 126, the wear-resistant material 122 is mechanically locked in place such that movement in a direction perpendicular to and parallel to the longitudinal axis of the shaft 22 is mechanically locked as shown in FIG. Similar to the locked state, it is blocked by material overlapping the wedge 128. In FIG. 6, approximately half of the wear resistant material 122 will be worn out before the mechanical lock of the corresponding wedge 128 wears out. Similarly, a sufficient amount of material 122 is deposited on the leading edge before the mechanical lock on each wedge 128 wears out.
It will wear out in 26 minutes.

FIG. 8 shows the width of the wear-resistant material 122 varying along the length of the flight according to the likely wear rate at any given location of the screw. Since the largest moment arm of the screw is adjacent to the outlet, it is the part adjacent the outlet 16 that is most likely to wear, with the degree of wear becoming progressively smaller as one moves in the direction towards the support bearing. Therefore, flights 38, 40
The entire outer surface 32 of the wear resistant material 12
Covered by 2. As one progresses along the flights 38, 40 toward their inlet ends, the portion of surface 32 occupied by wear-resistant material 122 becomes progressively smaller, as shown in FIG.

As mentioned above, the pump of the present invention can be improved by adopting various modifications, and each of these modifications can be applied alone or in combination with many others. It is possible. It is desirable that all improvements be incorporated into a given pump so that their cumulative effect can be achieved. Such a pump is shown in FIG.
This is improved by introducing a portion of the fluid at the outlet pressure into the isolated delivery cell before the cell is fully opened to the outlet pressure, as shown in FIGS. These are Figures 1 and 5.
Balance the screw shown in Figure 1, select the position of the balance hole properly, cover it, and grind the cap above the balance hole smooth as shown in Figures 1 and 5. It is improved by this. These are improved by providing sensors and monitoring devices to detect and monitor screw wear. These are improved by providing a pressure feedback control system 119 within the isolated delivery cell 72 that allows dynamic control of the delivery pressure.

Typical materials to be pumped by the pumps of the present invention are low viscosity fluids such as water and compositions containing significant amounts of water. Of course, other materials can also be delivered. A preferred material is Chesh
U.S. Pat. No. 4,443,2 to E. ire et al.
97, a foamed fiber furnish for paper making. Suitable expanded fiber furnishes for papermaking contain from about 50 to about 80 percent air by volume. The overall liquid medium contains about 200 to about 300 ppm of a surfactant, such as the surfactant sold by Arco Chemicals Inc. under the trademark A-OK. The papermaking fibers are dispersed in the blowing agent at a concentration of about 2% to about 3% by weight.

During the pump delivery operation, a prime mover such as an electric motor drives the shaft 2 of the screw 22 at the right end of the pump.
8 (Figure 1). When the motor rotates the shaft, the entire screw 2 including flights 34, 38
2 rotates and is rotatably supported within bearings 46, 52 and end bearings 130. As the screw 22 rotates, the engaged gears 56, 58 simultaneously rotate the shaft 24 in opposite directions. Each of the flights 34, 36, 38, 40 has an exit end of the respective flight within the respective delivery cell of material taken into the delivery cell defined by the respective screw flight by rotation of the respective screw. 78 and thus towards the outlet 16 of the pump 10.

The material to be delivered (eg, a three-phase expanded fiber furnish) enters the pump at inlet 14 and follows a branching path to opposite inlet ends 76 of the flights at each end of bore 20 . As the screw rotates, material is introduced into the bore 20 by the rotating screw. Once the material enters the bore 20, individual units of material are taken into a delivery cell 72 where the material is isolated from the inlet, outlet and from each other. This isolation is, of course, partially lost due to normal leakage allowed by the small gaps between some respective parts of the pump. As the screw continues to rotate, the delivery cell continues to advance, thus moving the liquid entrained within it to the outlet end 78 of the flight and finally out of the pump through the outlet 16.

Although the pump of the present invention has been described with respect to delivering water and aqueous foam liquids dispersed in a given condition, the present invention may be used with other deliverable materials and other delivery conditions. Of course it is possible.

Although the improvements disclosed herein have been described with respect to a positive displacement pump having two screws, those skilled in the art will know how to form counterbalance holes in the flights of the pump screws and how to balance the flights of the pump screws. It will be clear that it is also applicable to axial pumps with a single screw with a single screw flight or multiple screw flights at each end of the screw. It is also possible to provide a wear measurement port in the screw flight of such a single screw pump as disclosed herein, and it is also possible to provide a proximity sensor in such a port, as described above. Similarly, each of the screw flights of the single screw pump described above may be provided with an abrasion resistant strip and a fluid pressure feedback control system as disclosed herein.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view of a pump of the present invention.

FIG. 2 is a cross-sectional view of a portion of the pump taken along line 2-2 of FIG. 1;

FIG. 3 is a partial cross-sectional view showing alternative combinations of bores and screws to reduce pressure pulse effects.

FIG. 4 is a partial sectional view with a dynamic control device making it possible to reduce pressure pulse effects by providing a control device for controlling the amount of pressure leakage from the exit region of the screw back towards the inlet end of the screw; be.

FIG. 5 is a cross-sectional view of the counterbalance hole taken along line 5-5 of FIG. 1;

FIG. 6 is a partial cross-sectional view of the screw showing the wear-resistant strip on the screw.

FIG. 7 is a partial cross-sectional view of the screw showing the wear-resistant strip on the screw.

8 is a right side view of the pump of FIG. 1 showing the change in position of the wear-resistant strip with respect to its position on the screw; FIG.

[Explanation of symbols]

12 Casing
14 Screw inlet 16 Screw outlet
18 Inner passage 20 Bore
22 Pump delivery screw 24 Pump delivery screw 2
6 Bore inner surface 27 Bore outer surface
28 Shaft 29 Bore wall
30 Shaft 32 External surface of screw flight
34 Screw flight 36 Screw flight
38 Screw flight 40 Screw flight
42 Packing box 43 Packing box
44 Packing seal 45 Packing seal
46 Bearing 52 Bearing
54 Gear box 56
gear
58 Gear 60 Front of flight
62 Back of flight 64 Sending cell space
66 Sending cell space 68 Sending cell space
70 Delivery cell space 74 Screw part
76 Flight entrance end 78 Flight exit end
82 hole 84 cap
86 Measurement port 88 Inner end of the inner surface of the bore
90 Outer end of inner bore 92 Plug
94 Sign 96 Plug
98 Proximity sensor 100 Signal carrier
102 Monitoring device 104 Receiving port
106 pipe 108 valve
110 Manifold 112 Connection conduit
116 Fluid Supply Port 119 Control System

Claims (29)

[Claims] Claim 1: A positive displacement pump, comprising an inlet (14),
an outer casing (12) provided with an outlet (16) and an internal passageway (18) connecting said inlet and said outlet and in which a bore (20) is formed; Screw flights (34) extending radially outwardly from the shaft along the shaft.
) and the front (60) and rear (62) of said flight.
a flight (3) having an outer surface (32) formed between
4) and a bearing (46, 52) supported within the casing, the bearing being rotatably mounted so that the shaft can extend axially within the bore. (46, 52), the outer surface of the flight being arranged with respect to the bore such that the clearance therebetween is sufficiently small to facilitate efficient pumping of material through the bore by the screw. A positive displacement pump, characterized in that the screw flight is formed with one or more holes (82) to reduce the tendency of the screw to become unbalanced during operation of the pump. 2. A pump according to claim 1, wherein the casing passage (18) is connected to the bore adjacent to each end thereof, and the outlet is connected to the bore at a position approximately midway between the ends thereof. , the shaft is provided with two spaced apart screw flights extending from respective positions adjacent an end of the bore towards the position connecting to the outlet, the screw flights directing the fluid. The pump is adapted to pump from the inlet to the outlet of the casing, and each of the screw flights is formed with one or more holes (82) to prevent the screw from being unbalanced during operation of the pump. A pump characterized in that it reduces the tendency of 3. A pump according to claim 1 or 2, comprising a first and a second similar delivery screw (22, 24) arranged parallel and rotatably in the bore, the screw The flights are intercalated with each other, each of said screw flights having its front (60) and back (
62) and an outer surface (32) of the flight with respect to the bore, the clearance therebetween being sufficiently small for the screw to efficiently pump material through the bore. The pump is characterized in that each of the screw flights is formed with one or more holes (82) to reduce its tendency to become unbalanced. pump. 4. A pump according to any of claims 1 to 3, wherein the one or more counterbalancing holes are arranged at the location of the flights adjacent to each corresponding inlet to the bore. A pump characterized by: 5. A pump according to claim 1, wherein the inlet to the counterbalance hole is located on the outer surface of the flight and spaced a sufficient distance from the front and rear surfaces, A pump characterized in that the holes do not significantly reduce the pumping function of the material to be pumped. 6. Pump according to claim 1, characterized in that the balancing hole is plugged with a material having a density less than the average density of the adjacent flights. 7. A pump according to claim 1, wherein each of the counterbalance holes is located on the outer surface of the corresponding flight (
Pump characterized in that it is capped with a material (84) having an outer surface of the same height as (32). 8. In a positive displacement pump, the inlet (14)
, an outer casing (12) provided with an outlet (16) and an internal passageway (18) connecting said inlet and said outlet and in which a bore (20) is formed, a shaft (28) and fixed to said shaft; a screw flight (3) extending radially outwardly from the shaft along the shaft;
4), the front (60) and back (62) of the flight.
) having an outer surface (32) formed between the flight (
a delivery screw (22) comprising a delivery screw (22) (34); and a bearing (46, 52) supported within the casing, the bearing being rotatably mounted so that the shaft can extend axially within the bore. (46, 52), the outer surface of the flight being arranged with respect to the bore such that the clearance therebetween is sufficiently small to facilitate efficient pumping of material through the bore by the screw. For positive displacement pumps, at least one measurement port (86) extends through the casing into the bore and the outer surface (32) of said flight is located opposite said port, thereby allowing the measurement device to be connected to said A positive displacement pump, wherein the pump is positioned to operate through a port and to measure relative wear of the screw and the bore. 9. A pump according to claim 8, wherein the casing passage (18) is connected to the bore adjacent to each end thereof, and the outlet is connected to the bore at a position approximately midway between the ends thereof. , the shaft is provided with two spaced apart screw flights extending from respective positions adjacent an end of the bore towards the position connecting to the outlet, the screw flights directing the fluid. The pump is adapted to pump from said inlet to said outlet of a casing, wherein at least one measurement port (86) extends into the bore through the casing (12) and the outer surface (32) of said flight is A positive displacement pump, characterized in that it is positioned opposite the port so that a measuring device can be operated through the port to measure the relative wear of the screw and the bore. 10. The pump according to claim 8,
comprising first and second similar delivery screws (22, 24) arranged parallel and rotatably within said bore, the screw flights of which are mutually intercalated, each of said screw flights having a front face thereof; (60) and back (62)
and an outer surface (32) formed between said flights, said outer surfaces of said flights being arranged with respect to said bore such that the gap therebetween is sufficiently small to allow said screw to efficiently move material through said bore. A pump adapted to facilitate pumping, wherein at least one measurement port (86) extends into the bore through the casing (12) and the outer surface (32) of said flight is on the opposite side of said port. and positioned such that a measuring device can be operated through the port to measure the relative wear of the screw and the bore. 11. A pump according to claims 8 to 10, wherein a proximity sensor (98) is arranged in each of the wear measurement ports to detect the wear of the corresponding delivery screw flight and to detect the wear of the corresponding delivery screw flight. sealed and sealed,
A pump characterized in that it allows normal operation of the pump. 12. The pump according to claim 11,
Said means (100) extend from said proximity sensor and transmit signals generated by said proximity sensor to monitoring device means (100).
02) and monitoring the signal sent from the proximity sensor through the signal transmission means during normal operation of the pump. 13. In a positive displacement pump, the inlet (14
), an outer casing (12) provided with an outlet (16) and an internal passage (18) connecting said inlet and said outlet and in which a bore (20) is formed, a shaft (28) and fixed to said shaft; and a screw flight extending radially outwardly from the shaft along the shaft (
34) and the front (60) and back (6) of said flight.
a delivery screw (22) with a flight (34) having an outer surface (32) formed between the shaft and the shaft; a bearing (46, 52) rotatably mounted for axial extension within the bore, the outer surface of the flight being with respect to the bore with a sufficiently small clearance therebetween such that the screw allows the screw to pass through the bore; A positive displacement pump arranged to facilitate efficient pumping of material, wherein said outer surface (32) of said flight is an elongated hardened tube having a width that is less than or equal to one-half the width of said outer surface. Positive displacement pump, characterized in that it is provided with a wear-resistant strip (122). 14. A pump according to claim 13, wherein the passage (18) in the casing is connected to the bore adjacent to each end thereof, and the outlet is connected to the bore at a position approximately midway between the ends thereof. , the shaft is provided with two spaced apart screw flights extending from respective positions adjacent an end of the bore towards the position connecting to the outlet, the screw flights comprising:
The pump is adapted to pump fluid from said inlet to said outlet of a casing, wherein said outer surface (32) of said flight has an elongated, hardened, wear-resistant surface having a width that is less than or equal to one-half the width of said outer surface. sex strip (122)
A positive displacement pump comprising: 15. A pump according to claim 13 or 14, including first and second similar delivery screws (22, 24) arranged parallel and rotatably in the bore.
, whose screw flights are intercalated, each of said screw flights having an outer surface (32) formed between a front surface (60) and a rear surface (62) thereof, said outer surface of said flights; are arranged with respect to said bore, such that the gap therebetween is sufficiently small to facilitate efficient pumping of material through said bore by said screw, said outer surface ( 32) is an elongated hardened wear resistant strip (1
22) A positive displacement pump comprising: 16. A pump as claimed in claims 13 to 15, in which the width of the wear-resistant strip increases from one end of the corresponding flight adjacent the bore entrance to the other end, such that the width of the wear-resistant strip increases at any given point. A pump characterized in that the width is related to the amount of possible abrasive contact between the corresponding pump delivery screw flight and the bore. 17. A pump according to claims 13 to 16, wherein each part of the wear strip (122) is coated with a softer material (128) having a body corresponding to a delivery screw; said wear-resistant strip emerges from an adjacent screw flight both before and after the first wear of said wear-resistant strip on its surface corresponding to said outer surface (32) of said screw. , a pump characterized in that it can be held immovably in the longitudinal axis of a corresponding pump delivery screw. 18. In a positive displacement pump, the inlet (14
), an outer casing (12) provided with an outlet (16) and an internal passage (18) connecting said inlet and said outlet and in which a bore (20) is formed, a shaft (28) and fixed to said shaft; and a screw flight extending radially outwardly from the shaft along the shaft (
34) and the front (60) and back (6) of said flight.
a delivery screw (22) with a flight (34) having an outer surface (32) formed between the shaft and the shaft; a bearing (46, 52) rotatably mounted for axial extension within the bore, the outer surface of the flight being with respect to the bore with a sufficiently small clearance therebetween such that the screw allows the screw to pass through the bore; a fluid pressure supply port (116) located within the casing at a high pressure delivery fluid pressure end of the delivery screw flight, with a positive displacement pump arranged to facilitate efficient pumping of material; and a fluid pressure receiving port (104) disposed within the casing between ends of the delivery screw flight and a conduit (112) connecting the fluid supply port to the fluid receiving port. Positive displacement pump, characterized in that a system (119) is provided. 19. A pump according to claim 18, wherein the passage (18) in the casing is connected to the bore adjacent to each end thereof, and the outlet is connected to the bore at a position approximately midway between the ends thereof. , the shaft is provided with two spaced apart screw flights extending from respective positions adjacent an end of the bore towards the position connecting to the outlet, the screw flights comprising:
a fluid pressure supply port (116) disposed within the casing at a high pressure delivery fluid pressure end of the delivery screw flight, the pump being adapted to pump fluid from the inlet to the outlet of the casing; a fluid pressure feedback control system comprising: a fluid pressure receiving port (104) disposed within the casing between opposite ends of the delivery screw flight and a conduit (112) connecting the fluid supply port to the fluid receiving port; 119) is provided. 20. A pump according to claim 18, comprising first and second similar delivery screws (22, 24) arranged parallel and rotatably within the bore;
The screw flights are intercalated with each other such that each of the screw flights has its front (60) and back (62)
) having an outer surface (32) formed between said flights, said outer surface of said flight being disposed with respect to said bore, so that
The gap between them is sufficiently small, and the screw allows
a fluid pressure supply port (116) disposed within the casing at a high pressure delivery fluid pressure end of the delivery screw flight; a fluid pressure feedback control system comprising: a fluid pressure receiving port (104) disposed within the casing between ends of the delivery screw flight and a conduit (112) connecting the fluid supply port to the fluid receiving port; A pump characterized in that (119) is provided. 21. The screw pump according to claim 18, wherein each of the control systems includes a supply port (116) and a receiving port (116).
A screw pump characterized in that valve means (108) are provided for controlling the flow rate of fluid between said conduit (112) and said conduit (112). 22. The pump according to claim 21,
each of said control systems has a plurality of reception ports (104) spaced apart such that respective portions of a corresponding flight are disposed between successive said reception ports;
a conduit connecting said receiving port to said supply port, and valve means (108) adapted to distribute fluid flow from said supply port to said receiving port, said valve means comprising a conduit connecting said receiving port to said receiving port; controllable so that the pressure of the pumped fluid gradually increases as it traverses the length of the corresponding flight, so that when the fluid is discharged from said flight A pump characterized in that the pressure change is significantly smaller than the pressure difference between the pump outlet and the end of the screw receiving fluid delivered from the pump inlet. 23. A pump according to claim 1, wherein the cross-sectional area of the bore (20) of the pump casing is such that the cross-sectional area of the pump outlet (16) faces a part of the discharge end of each flight. ) A pump characterized by a gradual increase in the direction of 24. A method for monitoring the wear of a positive displacement pump according to any one of claims 8 to 10, comprising arranging the outer surface (32) of each screw flight opposite the corresponding measuring port. inserting the measuring device into the corresponding measuring port; and using the measuring device to measure the flight surface facing the corresponding measuring port (
32) measuring the wear of the method. 25. A method of monitoring wear in a positive displacement pump according to claim 11, comprising the steps of: arranging a proximity sensor in each of the measurement ports; closing and sealing each of the wear measurement ports; allowing normal operation of the pump by means of said sensors located at each of the ports; and during operation of the pump by detecting by said sensors a change in the distance between said sensor and the outer surface of the corresponding screw flight. and monitoring wear on an outer surface of a screw flight opposite said sensor. 26. A method of monitoring wear in a positive displacement pump of the form of claim 1 or 3, comprising the steps of: arranging each of the screws an unbalanced angular position along its circumference; and reducing the imbalance. 27. The method of claim 26, including one or more holes (
removing said material by forming a hole (82) such that said hole extends inwardly from the outer surface (32) of the screw. 28. A method according to claim 27, characterized in that it comprises the step of forming a cap (84) over each hole having an outer surface disposed flush with the outer surface of an adjacent screw. how to. 29. A method as claimed in claim 27 or 28, comprising the step of filling each hole with a less dense material than an adjacent screw flight.