Patent Application
20170059042
The present disclosure generally relates to paper manufacturing.
Paper machines (i.e., machines for manufacturing tissue, cardboard, newspaper, and the like) typically incorporate a suction roll for drawing off liquids from a liquid-laden pulp substrate that is carried through the machinery by a carrying wire or mat. Such a suction roll includes a rotating shell and a stationary vacuum box located within the shell. As the shell rotates around the vacuum box, vacuum pressure draws liquid (e.g., water) from the pulp substrate through holes in the suction roll and toward the vacuum box.
Transferring the vacuum in the vacuum box through the holes in the rotating shell typically involves the use of one or more axially-extending seals located between the stationary box and the rotating shell. Such a seal typically is washed with lubricant to prevent the seal from contacting the inner surfaces of the rotating shell in an effort to prolong the life of the seal and prevent drag load on the rotating shell. However, too little lubricant may allow contact with the shell, shortening seal life and increasing the drag load on the shell.
Sealing systems and related methods are provided. In this regard, an example embodiment of a sealing system comprises: an elongated seal having a contact surface configured to form an airtight seal with an inner surface of the drum; contact sensor circuitry configured to provide an electrical signal containing information indicative of direct contact between the seal and the inner surface of the drum; and a control actuator configured to direct a flow of lubricant responsive to receiving the information from the contact sensor indicating direct contact such that the flow of lubricant forms a film of lubricant between the contact surface and the inner surface of the drum to prevent direct contact between the seal and the drum.
An example embodiment of a sealing method comprises: monitoring locations of a seal formed between a sealing element and an inner surface of a rotatable perforated drum; receiving information indicative of direct contact between the sealing element and the inner surface; and responsive to the information, directing lubrication to a vicinity of the seal to alleviate the direct contact.
Another example embodiment of a sealing method comprises: providing a first zone of a seal formed between a sealing element and an inner surface of a rotatable perforated drum; providing a second zone of the seal, wherein the first zone and the second zone are not coextensive; and selectively dispensing lubrication to at least one of the first zone and the second zone.
Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
Reference will now be made in detail to that which is illustrated in the drawings. While the disclosure will be described in connection with these drawings, there is no intent to limit the scope of legal protection to the embodiment or embodiments disclosed herein. Rather, the intent is to cover all alternatives, modifications and equivalents included within the spirit and scope of the disclosure as defined by the appended claims.
As will be described in detail, sealing systems and related methods are provided for sealing at least one underpressure or overpressure area adjoining a surface, which is moved in a movement direction in a paper machine. Typically, such a surface is an inner surface of a perforated drum that is rotatable about a rotational axis. The system typically comprises components that are positioned within an interior chamber of the drum.
In this regard,
In the cross-sectional view of
Vacuum pressure is provided by a suction or vacuum box 30 that is mounted within interior 26, with the generated vacuum pressure preferably being confined to vacuum pressure area 24 by seals. In this embodiment, two such seals (32, 34) are provided, each of which includes a corresponding contact surface (42, 44). Each contact surface is configured to form an airtight seal with the inner surface 46 of suction roll 14.
In operation, the seals typically hydroplane on lubricant (e.g., water) that is located between the contact surfaces 42, 44 and the inner surface 46, with the lubricant preferably preventing direct contact between the contact surfaces and the inner surface of the suction roll. The lubricant is directed to the appropriate locations by control actuator 50 that selectively directs the flow of lubricant and/or varies the flow rate of the lubricant. Control actuator 50 may be provided in various forms such as a manually-controlled or automated valve(s), for example.
In some embodiments (such as described in detail later), lubrication can be supplied via a lubrication shower configured to apply lubricant upstream of (in a rotational sense) the contact surface. Additionally or alternatively, lubrication can be provided by a lubrication outlet. Such a lubrication outlet can be positioned along the contact surface of the seal itself and is configured to dispense lubricant. A lubrication passage communicates with the lubrication outlet and is configured to provide the lubrication outlet with a flow of lubricant so that the lubricant dispensed from the lubrication outlet forms a film of lubricant between the contact surface and the inner surface of the drum in a vicinity of the lubrication outlet.
In some embodiments, a lubrication outlet and/or shower may be configured to dispense lubrication associated with one or more zones of the contact surface (i.e., one or more axially extending portions of the contact surface). Moreover, one or more outlets or shower nozzles may be used to selectively provide lubrication to multiple zones.
System 10 of
An example embodiment of a seal 70 is depicted in
Another example embodiment of a sealing system is depicted in
As shown in the
Sealing system 100 is for use in a suction roll in a paper, tissue or cardboard machine (and may comprise the roll or machine with which it is associated). A stationary suction box 104 forms an airtight seal around a vacuum area 105 and between the rotating, perforated roll shell (drum) 106.
In the depicted embodiment, the sealing elements (101A, 101B) are positioned upon variable tension springs in the form of flexible air tubes (107A, 107B), lightly pressurized so as to position the seal close to the roll shell.
In operation, it is intended that the sealing elements are in light contact with the inner surface of rotating shell during start-up, and wear in to match the profile of the shell in a few hours. From that point in time until the roll stops, water from the process 108 and from various other forms of applied lubrication form the actual seal with the sealing elements hydroplaning on this lubrication along the inside surface 120 of the shell. In this configuration, little additional seal wear typically occurs until the machine stops and the start-up cycle is repeated.
A lubrication shower 109 is often positioned (in a rotational sense) just prior to (i.e., rotationally upstream) one or each of the sealing elements. The shower typically includes one or more nozzles to direct a spray of lubricant. In some embodiments, multiple nozzles are provided and used to direct lubrication toward various zones of a contact surface. By way of example, a series of nozzles could be spaced along the axis 113 of the drum with each being used to selectively direct lubrication to a corresponding zone responsive to sensed conditions. Additionally or alternatively, in some applications, lubrication is directed through one or more lubrication outlets toward the contact surface of the sealing element (101A, 101B).
The science of proper lubrication for providing such a seal is quite complicated. The process water available for lubrication varies with the grade and weight of paper, tissue, or card board, the position of the suction roll in the paper machine, the applied vacuum, the quantity and diameter of shell perforations, the thickness of the shell, the rotational speed of the shell, the fabrics used to carry the sheet of paper 111, tissue or card board on the opposite side of the perforations, and the nip pressures from mating rolls, among others. The inability to properly calculate the amount of process water available for lubrication in any one application has led to additional lubrication being applied liberally across the sealing surface through the various means described above, without knowledge of the actual need. No attempt has been made in the prior art to detect when and where lubrication is actually needed and to apply it accordingly.
For this purpose, control circuitry 130 (
As shown in
In this embodiment, seal 101A is monitored by pressure sensor 102A and a temperature sensor 103A. Although capable of various configurations (including variations in the number, type and/or placement of sensors), the sensors 102A and 103A are implemented by being mounted within corresponding access passages (162, 163) formed through the sidewalls of the seal that facilitate placement of the sensing components of the sensors within lubrication passage 158.
In some embodiments, a sensor may be mounted at the side of a seal, such as along the lead-in side relative to rotation. The sensor may be positioned at least partially within a groove formed in the surface of the seal, for example. The sensor could be positioned near the seal contact surface to detect heat from wear.
Additionally or alternatively, “wearable” sensors (i.e., sensors configured for wearing away as the seal wears) may be used. For example, a V-shaped wearable sensor may be mounted to a seal, with the difference in distance between any two points on either side of the V being used for determining the corresponding amount of wear of the seal.
As shown in greater detail in
In this embodiment, seal 101B is monitored by pressure sensor 102B and a temperature sensor 103B. Although capable of various configurations (including variations in the number, type and/or placement of sensors), the sensors 102B and 103B are implemented by being mounted within corresponding access passages (182A, 183A) that open to contact surface 170. Thus, with seal 101B, the sensors (102B, 103B) do not extend into the lubrication passage 178.
Seal 201 is monitored by multiple sensors (e.g., sensors 212, 214). Although capable of various configurations (including variations in the number, type and/or placement of sensors), the sensors 212 and 214 are implemented by being mounted within a shared access passage 216 that is open to contact surface 201. In some embodiments (such as depicted here), lubrication outlet 206 is positioned at a location of the contact surface rotationally upstream of the opening 218 of access passage 216.
In various embodiments, such as those described herein, a sealing system incorporates contact sensors (such as for pressure and temperature). Pressure and temperature would be detected at various points or zones along the surface of the contact area of the seal with the roll shell. Relative differences in pressure and/or temperature along the length of the seal would indicate areas of contact between the seal and the roll shell. This information would then be used to activate lubrication to the point or zone of contact for a determined amount of time, thereby lubricating the contact area to limit the seal wear and prevent heat build-up that can cause the seal material to expand into the shell.
In some embodiments, an additional sensor 112 (as shown in
By applying lubrication only when and where additionally needed, the amount of lubrication used may be greatly reduced—in some cases, no additional lubrication may be needed after a start-up phase. Use may also reduce any effect the sealing system could have on the power used to turn the roll, as the sealing system may bear on drive load when contact between the seal and shell occurs. By providing lubrication to contact points/zones when needed, the friction from the contact may be reduced thereby reducing any drag load from the sealing system.
As mentioned above, some embodiments involve the use of sensors/detectors for determining whether unwanted contact exists between a sealing element and the inner surface of the shell/drum. In such an embodiment, such a sensor/detector may communicate with a controller (incorporating control circuitry) for implementing various control functions. A manner for implementing such components may involve the use of a computer or processor-based device.
An example embodiment of such a device may include a processing device (processor circuitry), input/output interface circuits, network interface circuitry, a memory, an operating system, and mass storage, with each communicating across a local data bus. Note that the local data bus may be comprised of a plurality of buses.
The processing device may include any custom made or commercially available processor, a central processing unit (CPU) or an auxiliary processor among several processors associated with the mobile device, a semiconductor based microprocessor (in the form of a microchip), a macroprocessor, one or more application specific integrated circuits (ASICs), a plurality of suitably configured digital logic gates, and other electrical configurations comprising circuit elements both individually and in various combinations to coordinate the overall operation of the system.
The non-transitory memory can include any one of a combination of volatile memory elements (e.g., random-access memory (RAM, such as DRAM, and SRAM, etc.)) and nonvolatile memory elements. The memory typically comprises native operating system, one or more native applications, emulation systems, or emulated applications for any of a variety of operating systems and/or emulated hardware platforms, emulated operating systems, etc. In accordance with such embodiments, the components are stored in memory and executed by the processing device.
One of ordinary skill in the art will appreciate that the memory may, and typically will, comprise other components which have been omitted for purposes of brevity. Note that in the context of this disclosure, a non-transitory computer-readable medium stores one or more programs for use by or in connection with an instruction execution system, apparatus, or device.
Network interface circuitry comprises various components used to transmit and/or receive data over a networked environment. When such components are embodied as an application, the one or more components may be stored on a non-transitory computer-readable medium and executed by the processing device.
If embodied in software, it should be noted that each function described herein may represent a module, segment, or portion of code that comprises program instructions stored on a non-transitory computer readable medium to implement the specified logical function(s). In this regard, the program instructions may be embodied in the form of source code that comprises statements written in a programming language or machine code that comprises numerical instructions recognizable by a suitable execution system. The machine code may be converted from the source code, etc. If embodied in hardware, each function may represent a circuit or a number of interconnected circuits to implement the specified logical function(s).
An example embodiment of a controller that may be used in the sealing system of
In block 252, information indicative of direct contact between the sealing element and the inner surface of the suction roll is received. By way of example, the information may be in the form of electrical signals transmitted from the sensor to a corresponding controller that incorporates control circuitry. Responsive to the information (such as depicted in block 254), lubrication is directed to a vicinity of the seal indicated to alleviate the direct contact. In some embodiments, this may involve actuation of one or more control actuators to initiate and/or vary flow of lubricant to one or more zones of the sealing element.
In this regard, another example embodiment of a method for sealing is depicted in the flowchart of
In other embodiments, a sealing method may involve: providing a first zone of a seal formed between a sealing element and an inner surface of a rotatable perforated drum; providing a second zone of the seal, wherein the first zone and the second zone are not coextensive; and, selectively dispensing lubrication to at least one of the first zone and the second zone. Notably, the selective dispensing may involve varying a flow rate of the lubrication (e.g., on or off, or metering the flow rate) to the zone(s) such that the flow rates of the zones vary. Additionally, the dispensing may be provided by one or more lubrication showers configured to service multiple zones, one or more lubrication outlets configured to service multiple zones, and combinations thereof.
It should be emphasized that the above-described embodiments are merely examples of possible implementations. Many variations and modifications may be made to the above-described embodiments without departing from the principles of the present disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.
This utility application claims the benefit of and priority to U.S. Provisional application 62,211,137, filed on 28 Aug. 2015, the entire contents of which are incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 62211137 | Aug 2015 | US |
