Patent Grant
6981935
The present invention relates generally to industrial rolls, and more particularly to rolls for papermaking.
Cylindrical rolls are utilized in a number of industrial applications, especially those relating to papermaking. Such rolls are typically employed in demanding environments in which they can be exposed to high dynamic loads and temperatures and aggressive or corrosive chemical agents. As an example, in a typical paper mill, rolls are used not only for transporting a fibrous web sheet between processing stations, but also, in the case of press section and calender rolls, for processing the web sheet itself into paper.
A papermaking machine may include one or more suction rolls placed at various positions within the machine to draw moisture from a belt (such as a press felt) and/or the fiber web. Each suction roll is typically constructed from a metallic shell covered by a polymeric cover with a plurality of holes extending radially therethrough. Vacuum pressure is applied with a suction box located in the interior of the suction roll shell. Water is drawn into the radially-extending holes and is either propelled centrifugally from the holes after they pass out of the suction zone or transported from the interior of the suction roll shell through appropriate fluid conduits or piping. The holes are typically formed in a grid-like pattern by a multi-bit drill that forms a line of multiple holes at once (for example, the drill may form fifty aligned holes at once). In many grid patterns, the holes are arranged such that rows and columns of holes are at an oblique angle to the longitudinal axis of the roll.
As the paper web is conveyed through a papermaking machine, it can be very important to understand the pressure profile experienced by the paper web. Variations in pressure can impact the amount of water drained from the web, which can affect the ultimate sheet moisture content, thickness, and other properties. The magnitude of pressure applied with a suction roll can, therefore, impact the quality of paper produced with the paper machine.
Other properties of a suction roll can also be important. For example, the stress and strain experienced by the roll cover in the cross machine direction can provide information about the durability and dimensional stability of the cover. In addition, the temperature profile of the roll can assist in identifying potential problem areas of the cover.
It is known to include pressure and/or temperature sensors in the cover of an industrial roll. For example, U.S. Pat. No. 5,699,729 to Moschel et al. describes a roll with a helically-disposed fiber that includes a plurality of pressure sensors embedded in the polymeric cover of the roll. However, a suction roll of the type described above presents technical challenges that a conventional roll does not. For example, suction roll hole patterns are ordinarily designed with sufficient density that some of the holes would overlie portions of the sensors. Conventionally, the sensors and accompanying fiber are applied to the metallic shell prior to the application of the polymeric cover, and the suction holes are drilled after the application and curing of the cover. Thus, drilling holes in the cover in a conventional manner would almost certainly damage the sensors, and may well damage the optical fiber. Also, during curing of the cover often the polymeric material shifts slightly on the core, and in turn may shift the positions of the fiber and sensors; thus, it is not always possible to determine precisely the position of the fiber and sensors beneath the cover, and the shifting core may move a sensor or cable to a position directly beneath a hole. Further, ordinarily optical cable has a relative high minimum bending radius for suitable performance; thus, trying to weave an optical fiber between prospective holes in the roll may result in unacceptable optical transmission within the fiber.
The present invention is directed to sensing systems for industrial rolls that can be employed with suction rolls. As a first aspect, the present invention is directed to an industrial roll comprising: a substantially cylindrical shell having an outer surface and an internal lumen; a polymeric cover circumferentially overlying the shell outer surface; and
a sensing system. The sensing system includes: a plurality of sensors embedded in the cover, the sensors configured to sense an operating parameter of the roll; and a signal-carrying member serially connected with and extending between the plurality of sensors. The signal-carrying member follows a helical path over the outer surface of the shell, wherein the signal-carrying member extends between adjacent sensors extends over more than one complete revolution of the shell outer surface (and, preferably, an intermediate segment of the signal-carrying member extends over more than a full revolution of the roll between adjacent sensors).
As a second aspect, the present invention is directed to an industrial roll comprising: a substantially cylindrical shell having an outer surface and an internal lumen; a polymeric cover circumferentially overlying the shell outer surface, the cover including an internal groove that defines a helical path; and a sensing system, wherein the sensing system includes a plurality of sensors embedded in the cover that are configured to sense an operating parameter of the roll and a signal-carrying member serially connected with and extending between the plurality of sensors. The signal-carrying member resides in the groove and follows the helical path in the shell outer surface.
As a third aspect, the present invention is directed to an industrial roll, comprising: a substantially cylindrical shell having an outer surface and an internal lumen; a polymeric cover circumferentially overlying the shell outer surface; and a sensing system including a plurality of sensors embedded in the cover, the sensors configured to sense an operating parameter of the roll; and a signal-carrying member serially connected with and extending between the plurality of sensors. At least one of the plurality of sensors is configured to slide along and relative to the signal-carrying member.
As a fourth aspect, the present invention is directed to an industrial roll, comprising: a substantially cylindrical shell having an outer surface and an internal lumen; a polymeric cover circumferentially overlying the shell outer surface, wherein the cover and shell include a plurality of through holes extending from an outer surface of the cover to the shell lumen, such that the lumen is in fluid communication with the environmental external to the cover outer surface; and a sensing system comprising: a plurality of sensors embedded in the cover, the sensors configured to sense an operating parameter of the roll; and a signal-carrying member serially connected with and extending between the plurality of sensors, the signal-carrying member following a helical path over the outer surface of the shell. The cover further comprises at least one blind drilled hole located over one of the plurality of sensors.
As a fifth aspect, the present invention is directed to a method of calculating the axial and circumferential positions of sensors on an industrial suction roll. The method comprises the steps of: providing as input variables (a) one of the diameter and circumference of the roll and (b) an angle defined by a hole pattern in the industrial roll and a plane perpendicular to the longitudinal axis of the roll; selecting a value for one of an axial or circumferential position of a sensor; and determining the other of the axial or circumferential position of the sensor based on the values of the diameter or circumference of the roll, hole pattern angle and axial or circumferential position.
Each of these aspects of the invention (as well as others) can facilitate the employment of a sensing system within a suction roll cover, thereby overcoming some of the difficulties presented by prior sensing systems.
The present invention will now be described more fully hereinafter, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, like numbers refer to like elements throughout. Thicknesses and dimensions of some components may be exaggerated for clarity.
Referring now to the figures, a suction roll, designated broadly at 20, is illustrated in
The shell 22 is typically formed of a corrosion-resistant metallic material, such as stainless steel or bronze. A suction box (not shown) is typically positioned within the lumen of the shell 22 to apply negative pressure (i.e., suction) through holes in the shell 22 and cover 24. Typically, the shell 22 will already include through holes that will later align with through holes 82 and blind-drilled holes 84. An exemplary shell and suction box combination is illustrated and described in U.S. Pat. No. 6,358,370 to Huttunen, the disclosure of which is hereby incorporated herein in its entirety.
The cover 24 can take any form and can be formed of any polymeric and/or elastomeric material recognized by those skilled in this art to be suitable for use with a suction roll. Exemplary materials include natural rubber, synthetic rubbers such as neoprene, styrene-butadiene (SBR), nitrile rubber, chlorosulfonated polyethylene (“CSPE”—also known under the trade name HYPALON), EDPM (the name given to an ethylene-propylene terpolymer formed of ethylene-propylene diene monomer), epoxy, and polyurethane. In many instances, the cover 24 will comprise multiple layers (
The cover 24 has a pattern of holes (which includes through holes 82 and blind drilled holes 84) that may be any of the hole patterns conventionally employed with suction rolls or recognized to be suitable for applying suction to an overlying papermaker's felt or fabric and/or a paper web as it travels over the roll 20. A base repeat unit 86 of one exemplary hole pattern is illustrated in
Referring back to
The processor 32 is typically a personal computer or similar data exchange device, such as the distributive control system of a paper mill, that can process signals from the sensors 30 into useful, easily understood information. It is preferred that a wireless communication mode, such as RF signaling, be used to transmit the data from the sensors 30 to the processing unit 32. Other alternative configurations include slip ring connectors that enable the signals to be transmitted from the sensors 30 to the processor 32. Suitable exemplary processing units are discussed in U.S. Pat. No. 5,562,027 to Moore and U.S. patent application Ser. No. 09/872,584, the disclosures of which are hereby incorporated herein in their entireties.
The suction roll 20 can be manufactured in the manner described below and illustrated in
Referring now to
Turning now to
Referring now to
It may be desirable to shift the positions of the sensors 30 slightly to precise locations on the base layer 42. Because the optical fiber 28 is retained within the groove 50 and its relative inflexibility (i.e., it may break at a relatively high bending radius) may prevent bending a portion of the fiber 28 out of the groove in order to position a sensor 30, in some embodiments the sensor 30 may be free to slide short distances along the fiber 28. One exemplary design is illustrated in
Once the sensors 30 are in desired positions, they can be adhered in place. This may be carried out by any technique known to those skilled in this art; an exemplary technique is adhesive bonding.
Referring now to
Referring now to
Because the hole pattern may define the path that the optical fiber 28 (and, in turn, the groove 50) can follow, in some rolls conventional placement of the sensors 30 (i.e., evenly spaced axially and circumferentially, and in a single helix) may not be possible. As such, one must determine which axial and circumferential positions are available for a particular roll. Variables that can impact the positioning of sensors include the size of the roll (the length, diameter and/or circumference) and the angle θ defined by the hole pattern. Specifically, the relationships between these variables can be described in the manner discussed below.
The length of the fiber extending from an origin point on the roll to a particular axial and circumferential position can be modeled as the hypotenuse of a right triangle, in which the axial position serves as the height of the triangle and the total circumferential distance covered by the fiber serves as the base of the triangle (see
sin θ=a/FL; and Equation 1
cos θ=Xdπ/FL Equation 2
wherein:
FL=fiber length from origin to sensor position;
a=axial distance from origin to sensor position;
d=diameter of the roll;
X=number of revolutions of fiber around the circumference of the roll; and
θ=angle defined by suction hole pattern relative to plane through axis of roll.
Solving equations 1 and 2 for FL, then substituting yields:
Xdπ/cos θ=a/sin θ Equation 3
Because (sin θ/cos θ) can be simplified to tan θ, the expression can be reduced to
a=Xdπ(tan θ) Equation 4
Thus, for any axial position a, the corresponding circumferential position (expressed in the number revolutions, which can be converted into degrees by multiplying by 360) can be calculated; the reverse can be performed to calculate the axial position from a given circumferential position.
An alternative method for calculating the axial and circumferential positions employing some practical measurements used in suction rolls can also be used. For a specific roll with a designated hole pattern, the following variables can be assigned:
α=angular position on the roll;
z=axial position on the roll;
d=drill spacing;
N=number of frames in the circumference of a roll (this is a whole number); and
B=number of frames required for a diagonal row of holes to move in the axial direction the distance of one drill spacing.
For an optical fiber 28 that follows the drill pattern on a drilled roll,
α=(B/N)(z/d) Equation 5
with α being given in revolutions (again, multiplying α by 360 degrees gives the angular position in degrees). Thus, for a given drilled roll defined by a diameter, a length and a hole pattern, B, N and d are known. The circumferential position can then be calculated for a given axial position; alternatively, the axial position can be calculated for a given circumferential position.
Those skilled in this art will recognize that the aforementioned methods of calculating axial position and circumferential position may be performed using different forms of variables as demonstrated, and that other forms may also be used that consider the diameter and/or circumference of the roll and the angle at which the fiber travels in its helix.
In some embodiments, the calculation can be performed with a computer program designed and configured to receive data input of the type described above and, using such data, calculate axial and circumferential positions for sensors. Such a program is exemplified in
Inasmuch as the present invention may be embodied as methods, data processing systems, and/or computer program products, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embodied in the medium. Any suitable computer readable medium may be utilized including, but not limited to, hard disks, CD-ROMs, optical storage devices, and magnetic storage devices.
Computer program code for carrying out operations of the present invention may be written in an object oriented programming language such as JAVA®, Smalltalk or C++. The computer program code for carrying out operations of the present invention may also be written in conventional procedural programming languages, such as “C”, or in various other programming languages. Software embodiments of the present invention do not depend on implementation with a particular programming language. In addition, portions of computer program code may execute entirely on one or more data processing systems.
The present invention is described above with reference to block diagram and/or flowchart illustrations of methods, apparatus (systems) and computer program products according to embodiments of the invention. It is understood that each block of the block diagram and/or flowchart illustrations, and combinations of blocks in the block diagram and/or flowchart illustrations, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the block diagram and/or flowchart block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the block diagram and/or flowchart block or blocks.
The computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the block diagram and/or flowchart block or blocks.
It should be noted that, in some alternative embodiments of the present invention, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may in fact be executed substantially concurrently or the blocks may sometimes be executed in the reverse order, depending on the functionality involved. Furthermore, in certain embodiments of the present invention, such as object oriented programming embodiments, the sequential nature of the flowcharts may be replaced with an object model such that operations and/or functions may be performed in parallel or sequentially.
The use of the equations set forth above can be demonstrated with the following examples.
In this example, it is assumed that the roll has the dimensions set forth in Table 1, and that the hole pattern is that illustrated in
The diameter and frame measurements indicate that the variable N above is 156, and for the hole pattern of
α=0.041z Equation 6
This equation can then be used to calculate axial and circumferential coordinates for sensors.
If the circumferential spacing is maintained to be the same as a typical roll (usually 21 sensors over a 360 degree circumference, or about 17.14 degrees between sensors), a set of circumferential and axial positions can be calculated (Table 2).
It can be seen from the “Total Angle” calculation that, for each subsequent axial position, the angle increases by a full revolution of the roll. This corresponds to a full loop of the optical fiber 28 around the roll between adjacent sensors 30. It can also be seen that, for this embodiment, the sensors 30 would be positioned over less than a full circumference of the roll 20 (only about 154 degrees), so some portions of the circumferential surface of the roll 20 would not have sensors 30 below them. In addition, there are fewer sensors 30 (ten, as opposed to the more typical 21) spaced relatively evenly along the length of the roll 20.
If, rather than the circumferential spacing of a conventional roll being maintained, the conventional axial spacing of 11.9 inches is maintained, Equation 2 gives the circumferential positions shown in Table 3.
In this embodiment, all axial positions are satisfied. All angular positions are not, and in addition, the angular positions are not in circumferential order, so detecting of sensors may be more difficult.
The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although exemplary embodiments of this invention have been described, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of this invention. Accordingly, all such modifications are intended to be included within the scope of this invention.
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