Seal strip wear monitoring systems and assemblies therefor

Abstract

A seal strip for a suction roll includes: an elongate body comprising a polymeric material, the elongate body having a lower surface and a subchannel with an open end that opens at the lower surface, the subchannel extending upwardly from the lower surface, wherein a longitudinal axis of the subchannel extends parallel with a longitudinal axis of the elongate body; a system for monitoring operational parameters, the system including a plurality of sensors and a controller for receiving signals from the sensors, the system residing within the subchannel; and additional polymeric material in the subchannel that embeds the system within the subchannel.

Description

SEAL STRIP WEAR MONITORING SYSTEMS AND ASSEMBLIES THEREFORRelated Application

[0001] The present application claims priority from and the benefit of U.S. Provisional Patent Application No. 63 / 507,549, filed June 12, 2023, the disclosure of which is hereby incorporated herein by reference in full.Field of the Invention

[0002] The present invention is directed generally to papermaking, and more specifically to suction rolls and equipment within a papermaking machine.Background of the Invention

[0003] Paper manufacturing inherently requires at many points in the production process the removal of water. In general, the paper pulp (slurry of water and wood and other fibers) rides on top of a felt (in the form of a wide belt) which acts as a carrier for the wet pulp before the actual sheet of paper is formed. Felts are used to carry the pulp in the wet section of the paper machine until enough moisture has been removed from the pulp to allow the paper sheet to be processed without the added support added by the felt.

[0004] Quite commonly on the wet end of a paper machine, initial water removal is accomplished using a suction roll in a press section (be it a couch, pickup, or press suction roll) used in conjunction with a standard press roll without holes (or against a Yankee dryer in a tissue machine) that mates in alignment with the suction roll. The felt pulp carrier is pressed between these two rolls.

[0005] The main component of a suction roll 10 includes a hollow shell 12 (FIG. 1) made of stainless steel, bronze or other metal that has tens of thousands of holes, drilled in a prescribed pattern radially around the circumference of the roll. These holes are gauged in size (ranging from under 1 / 8" to nearly %") and are engineered for the particular paper material to be processed. It is these holes that form the "venting" for water removal. This venting can typically range from approximately 20 to 45 percent of the active roll surface area. The suction roll shell is driven by a drive system that rotates the shell around a stationary core called a suction box.

[0006] The suction box 20 (FIG. 2) can be thought of as conventional long rectangular box without a lid on the top and with ports on the end, bottom or sides. The end (specifically the drive end) of the box typically has a pilot bearing, of which the inner raceway is a pilot bushing or bearing with a slip fit to a journal on the suction box and the outer raceway is pressed onto the rotating shell. The suction box 20 is connected with a suction source (e.g., a vacuum pump). An exemplary suction box and shell are shown in U.S. Patent No. 6,358,370 to Huttunen, the disclosure of which is hereby incorporated herein in its entirety.

[0007] In order to take advantage of the holes in the shell, a vacuum zone 30 must be created using these ports on the inside of the suction roll shell in a zonethat is directly underneath the paper pulp that is being processed. This is accomplished by the suction box 20 using a slotted holder 32 which holds a seal along the long axis of the suction box on both sides. FIG. 2 shows the slotted holders 32, and FIGS. 3 and 4 show two varieties of seals 34, 34' which are in the form of strips (hereinafter "seal strips"). In addition to these long seals there are two shorter seals (called end deckles) on the short ends (called tending and drive ends) that permit some axial adjustment as needed to accommodate various sheet widths.

[0008] The seal strips 34, 34' are usually made of rubberized polymerized graphite and are held nearly in contact with the inner surface of the shell 12 during operation (see FIGS. 3 and 4). Between the seal strips 34, 34' a constant vacuum is drawn. This allows the vacuum zone 30 to be created underneath the sheet 40 as is passes over the roll 10. The seal strips 34, 34' are biased upwardly toward the suction roll shell 12 by load tubes 42, which are sealed hoses that run underneath the entire length of the seal strip 34, 34'. Pressure in the load tube 42 expands the load tube 42 (much like air in a balloon) and lifts the seal strip 34, 34' toward the inside surface of the shell 12. This effect, along with help from the system vacuum from the suction box 20 and the laminar flow of lubrication water mentioned previously, forms the seal between the edge of the seal strip 34 and the inside of the shell 12.

[0009] In actual application, in a properly functioning suction roll the seal strips 34, 34' never directly contact the inside of the suction roll shell 12. If the seal strips 34, 34' were to contact the shell 12 they would wear away and would quickly lose their sealing ability. In order to eliminate or significantly reduce this wear and to provide a seal, water is applied along the length of the seal strips 34,34' with a lubrication shower formed with water flowing through a spray nozzle 24 (see FIG. 2). This shower keeps the seal strips 34, 34' lubricated with a laminar flow of water between the seal surface and the inside surface of the shell 12.

[0010] The amount of water used for lubrication should be gauged properly so that the proper amount of lubrication is applied to keep the seal strips 34, 34' lubricated, but not so much to either become an issue for the pulp being processed or to be wasting water. In addition, process water used in a paper mill may contain chemicals and also significant particulates that may clog the lubrication shower nozzles 24 during normal operation. Since these nozzles 24 are located inside the rotating shell 12 they are not visible to the paper machine operator.

[0011] Seal strips are typically replaced periodically after some degree of wear occurs. However, because the seal strips inside a suction roll are not visible to the operator of the paper making equipment or to anyone trying to view the seal strips, many conditions inside an operating suction roll, including the degree of seal strip wear, are unknown. As such, a reliable method of detecting seal strip wear to inform the operator of the papermaking equipment that maintenance is needed on the equipment before a failure occurs may be desirable.Summary

[0012] As a first aspect, embodiments of the invention are directed to a seal strip for a suction roll. The seal strip comprises: an elongate body comprising a polymeric material, the elongate body having a lower surface and a subchannel with an open end that opens at the lower surface, the subchannel extending upwardly from the lower surface, wherein a longitudinal axis of the subchannelextends parallel with a longitudinal axis of the elongate body; a system for monitoring operational parameters, the system including a plurality of sensors and a controller for receiving signals from the sensors, the system residing within the subchannel; and additional polymeric material in the subchannel that embeds the system within the subchannel.

[0013] As a second aspect, embodiments of the invention are directed to a process for manufacturing a seal strip. The process comprises the steps of:(a) extruding, from a polymeric material, an elongate seal strip body having a lower surface and a subchannel with an open end that opens at the lower surface, the subchannel extending upwardly from the lower surface, wherein a longitudinal axis of the subchannel extends parallel with a longitudinal axis of the elongate body;(b) installing in the subchannel a system for monitoring operational parameters, the system including a plurality of sensors and a controller for receiving signals from the sensors; and(c) adding additional polymeric material to the subchannel to embed the system within the subchannel.Brief Description of the Figures

[0014] FIG. 1 is a perspective end view of a typical paper machine suction roll.

[0015] FIG. 2 is an enlarged perspective end view of the suction box area of a typical suction roll.

[0016] FIG. 3 is an end view of the suction box area and seal strips of a conventional suction roll.

[0017] FIG. 4 is an end view of the suction box area and seal strips of another conventional suction roll.

[0018] FIG. 5 is a schematic side view of a seal strip and wear monitoring system according to embodiments of the invention.

[0019] FIG . 6 is a plan view of a seal strip monitoring system according to embodiments of the invention.

[0020] FIGS. 7A-7D are sequential perspective views illustrating the construction of the seal strip monitoring system of FIG. 6.

[0021] FIG. 8 is a schematic perspective view of the body of a seal strip according to embodiments of the invention.

[0022] FIG. 9 is a schematic end view of a seal strip with a wear monitoring system according to embodiments of the invention.

[0023] FIG. 10 is a schematic end view of a seal strip with a wear monitoring system according to alternative embodiments of the invention.Detailed Description of the Embodiments

[0024] The present invention will now be described more fully hereinafter, in which 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.

[0025] In addition, spatially relative terms, such as "under", "below", "lower", "over", "upper" and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "under" or "beneath" other elements or features would then be oriented "over" the other elements or features. Thus, the exemplary term "under" can encompass both an orientation of over and under. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

[0026] Well-known functions or constructions may not be described in detail for brevity and / or clarity.

[0027] Referring now to the drawings, an exemplary seal strip 100 and an accompanying wear monitoring system 120 are shown in FIG. 5. With the exception of accommodations for the wear monitoring system 120 described below, the seal strip 100 is of conventional design much in the manner described above: it is elongate and of generally constant cross-section; it resides within a channel-shaped holder and is supported by load tubes against its lower surface 105; the load cells bias the seal strip 100 upwardly (i.e., toward the shell of a suction roll) so that its upper surface 106 confronts the shell and contributes to a seal therewith; and it is formed of a polymeric material such as rubber (which may be filled with a filler, such as graphite).

[0028] Referring now to FIG. 5, the wear monitoring system 120 is shown partially embedded within the seal strip 100. The wear monitoring system 120 includes a sensing portion 122, a signal processing portion 124, and cables 126 that connect the sensing portion 122 with the signal processing portion 124. The seal strip 100 includes a channel 108 in the lower surface in which cables 110 between adjacent wear monitoring systems 120 are routed. Also, a cap 128 surrounds the upper end of the sensing portion 122 and is flush with the upper surface 106 of the seal strip 100.

[0029] FIG. 6 illustrates another wear monitoring system, designated broadly at 420. The wear monitoring system 420 is mounted on a single PCB 423 (i.e., both the sensing portion 422 and the signal processing portion 424 are located on the same PCB 423). As such, there are no cables like cable 126; instead, the traces 430 are connected directly to the components of the signal processing portion 424. The PCB 423 is flexible, enabling it to be bent so that the finger 421 on which the sensing portion 422 is mounted can be oriented generally perpendicularly to the main portion 427 of the PCB 423.

[0030] In this embodiment, a temperature monitoring system 470 is also mounted on the PCB 423. The temperature monitoring system 470 may take many forms, including that described in U.S. Provisional Patent Application No. 63 / 375,587, filed September 14, 2022, the disclosure of which is hereby incorporated herein by reference in full. A sensing portion 472 of the temperature monitoring system 470 is mounted on finger 471 of the PCB 423, and signal processing components of the temperature monitoring system 470 are mounted on the main portion 427 of the PCB 423. Together the wear monitoringsystem 420 and the temperature monitoring system 470 form an overall seal strip monitoring system 480.

[0031] Referring to FIGS. 7A-7D, the mounting of the wear monitoring system 420 within the channel 408 of a seal strip 400 is shown. FIG. 7A illustrates the lower surface of the seal strip 400, wherein the channel 408 has been formed and holes 409, 410 have been drilled perpendicularly to the channel 408. FIG. 7B illustrates that the system 420 is installed in the seal strip 400, with fingers 421, 471 inserted into the holes 409, 410 to deploy the sensing portions 422, 472, and the main portion 427 of the PCB 423 mounted in the channel 408 itself. FIG. 7C illustrates the connection of cables 490 to the PCB 423 to allow for the aforementioned "daisy-chaining" of systems 420 along the length of the seal strip 400. FIG. 7D illustrates that potting compound 492 (e.g., an elastomeric silicone) is added to fill in the channel 408.

[0032] Additional embodiments and details regarding the wear systems 120, 420 are discussed in U.S. Provisional Patent Application No. 63 / 481,835, filed January 27, 2023, the disclosure of which is hereby incorporated herein by reference in full.

[0033] There is a concern that may be raised by the wear systems 120 discussed above: i.e., forming the seal strip 100, routing or otherwise forming the channel 108 in the seal strip 100, installing the electronics / cabling of the wear monitoring system 120 in the channel 108, then filling the channel 108 with the epoxy / potting compound. This technique has the possibility of creating issues with thermal expansion (because the potting compound has a different coefficient of thermal expansion than the remainder of the seal strip 100),structural integrity of the seal strips 100, and damage to the shell 12 of the suction roll 10. Similar issues may arise with the wear system 420.

[0034] This concern can be addressed by the seal strip 200 illustrated in FIGS. 8 and 9. The seal strip 200 has a body 202 that includes a lower channel 208 much like the seal strip 100, but further includes a subchannel 214 that extends much, if not all, of the length of the seal strip 200. The subchannel 214 has a side that is open to the channel 210 and serves as an inlet 214a to the subchannel 214. In the illustrated embodiment, the subchannel 214 is generally hexagonal in profile, but as discussed below other profile shapes may also be employed (e.g., rectangular).

[0035] In some embodiments, the body 202 of the seal strip 200 is formed via an extrusion process. Because the body 202 of the seal strip 200 is largely, if not entirely, uniform in cross-section, it can be formed in a relatively straightforward extrusion process. In such a process, both the lower channel 208 and the subchannel 214 can be formed within the body 202 during extrusion.

[0036] In contrast to the wear monitoring systems 120, 420, which reside in the channels 108, 408 of the seal strips 100, 400, a wear monitoring system 220 resides within the subchannel 214 of the seal strip 200. The wear monitoring system 220 may take the same or a similar form to that of the wear systems 120, 420 with the exception of its location within the subchannel 214. The wear system 220 includes fingers 221, 271 with sensing portions 222, 272 thereon that are inserted into holes 209, 210 in the body 202 and a PCB 223 that is mounted within the subchannel 214. Cables 290 can be connected to the PCB 223 to permitted daisy-chaining of additional wear monitoring systems 220 within the subchannel 214.

[0037] Also, the seal strip 200 differs from the seal strip 100 in that the wear monitoring system 220 is embedded within the body 202 of the seal strip 200. The wear system 220 is "embedded" in that, once the wear system 220 is positioned in the subchannel 214, an additional amount 240 of the material that is used to form the body 202 of the seal strip 200 are added to "seal" the wear monitoring system 220 within the subchannel 214. Because the wear monitoring system 220 is embedded within the body 202 of the seal strip 200 with the same material as the remainder of the body 202, any issues that might otherwise arise with differing coefficients of thermal expansion between different materials should be reduced or alleviated. Moreover, the similarity of the additional material 240 to that of the body 202 also renders the filled subchannel 214 with similar wear and flexibility characteristics as the remainder of the body 202.

[0038] As discussed above, the body 202 of the seal strip 200 typically comprises a polymeric material, with one exemplary material being rubber filled with a filler such as graphite. It follows that the additional material 240 used to fill the subchannel 214 typically comprises the same or a similar material.

[0039] In one embodiment, the manufacturing process would proceed in the following manner. First, the body 202 of the seal strip 200 is extruded. Any additional holes (e.g., the holes 209, 210) are drilled in the body 202. The wear monitoring system 220 is then installed into the subchannel 214 of the body 202 through the inlet 214a. In some instances it may be beneficial to coat the electronic components (e.g., the PCB 223 and the sensing portions 222, 272 with a small amount of a potting compound to protect the components and / or to help them to adhere in position. Next, the additional amount 240 of the seal strip material is added into the subchannel 214 through the inlet 214a to embed thewear monitoring system 220. The entire seal strip 200 (including the wear monitoring system 220 and the additional material 240) is then cured. Thus, the finished product has the wear monitoring system 220 embedded within the body 202 of the seal strip 200.

[0040] In some embodiments the additional material 240 bonds to the original seal strip material so that the bonded area simulates or closely resembles the integrity of the material in unbonded regions. This may be achieved through simply adding the additional material 240 to the body 202 of the seal strip 200. In some instances, the bond may have less integrity than the reminder of the body 202 of the seal strip 200. In such instances, the hexagonal profile of the subchannel 214 may provide protection against separation of the additional material 240; because the inlet 214a of the subchannel 214 is relatively narrow compared to the remainder of the subchannel 214, once it is cured the additional material 240 is wedged into place within the subchannel 214 and should not be dislodged during operation of the seal strip 200 even if the bond lacks some integrity. Thus, the additional material 240 in the subchannel 214 can provide the above-discussed advantages of using a similar material to fill the subchannel 214 without the risk of the additional material 240 inadvertently being displaced.

[0041] In some embodiments, the body 202 may be at least partially cured prior to the addition of the wear monitoring system 220 or the additional material 240. Partial curing may have the advantage of facilitating other manufacturing steps (e.g., the drilling of the holes 209, 210). After such steps are performed, the wear monitoring system 220 can be installed in the subchannel 214 and the additional material 240 can be added. Curing then can be completed. In such an embodiment, the additional material 240 may be less cured than the remainderof the body 202, in which case the additional material 240 may be more flexible than the remainder of the body 202.

[0042] FIG. 10 illustrates another seal strip configuration (designated broadly at 300) in which the profile of the body 302 of the seal strip is generally rectangular (i.e., it does not have a channel like the channel 208 of the seal strip 200). A subchannel 314 (shown herein as having a hexagonal profile) is present and has an inlet 314a at its lower end. A wear monitoring system 320 is housed within the subchannel 314 and is held in place by additional material 340 in a similar manner to that described above for the wear monitoring system 220.

[0043] Those of skill in this art will appreciate that the seal strips 200, 300 shown herein may take different forms. For example, although the subchannels 214, 314 shown herein are hexagonal in profile, other profile shapes (e.g., rectangular, pentagonal, octagonal, trapezoidal, truncated cylindrical) may also be used. It may be advantageous for the inlet to be narrower than the widest dimension of the subchannel so that the additional material can be retained more securely therein.

[0044] As another example, in some embodiments the additional material may be treated slightly to enhance bonding to the remainder of the body 202, 302 to increase its cure time, and / or modify its flexibility. Such treatments may be desirable for embodiments in which the body of the seal strip is partially cured before the additional material is added.

[0045] Finally, although wear monitoring systems are discussed herein, the concepts discussed may be suitable for other types of devices for monitoring operational parameters of a seal strip, such as temperature monitoring systems.Such systems are discussed in, for example, U.S. Patent Publication No. 2022 / 0145538.

[0046] The foregoing is illustrative of the present invention and is not to be construed as limiting thereof. Although a few 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 as defined in the claims. The invention is defined by the following claims, with equivalents of the claims to be included therein.

Claims

What is Claimed is:

1. A seal strip for a suction roll, comprising: an elongate body comprising a polymeric material, the elongate body having a lower surface and a subchannel with an open end that opens at the lower surface, the subchannel extending upwardly from the lower surface, wherein a longitudinal axis of the subchannel extends parallel with a longitudinal axis of the elongate body; a system for monitoring operational parameters, the system including a plurality of sensors and a controller for receiving signals from the sensors, the system residing within the subchannel; and additional polymeric material in the subchannel that embeds the system within the subchannel.

2. The seal strip defined in Claim 1, wherein the subchannel extends for a full length of the elongate body.

3. The seal strip defined in Claim 1 or Claim 2, wherein the open end of the subchannel has a width less than a maximum width of the subchannel.

4. The seal strip defined in Claim 3, wherein the subchannel has a generally hexagonal profile.

5. The seal strip defined in Claim 1, wherein the polymeric material comprises rubber filled with graphite.

6. The seal strip defined in Claim 1 or Claim 5, wherein the additional polymeric material is the same as the polymeric material of the elongate body.

7. The seal strip defined in Claim 1, wherein the lower surface includes a channel, and wherein the open end of the subchannel opens at the channel.

8. The seal strip defined in Claim 1, wherein the elongate body is extruded, and wherein the subchannel is formed during extrusion of the elongate body.

9. The seal strip defined in Claim 1, wherein the sensors are wear sensors.

10. A process for manufacturing a seal strip, comprising the steps of:(a) extruding, from a polymeric material, an elongate seal strip body having a lower surface and a subchannel with an open end that opens at the lower surface, the subchannel extending upwardly from the lower surface, wherein a longitudinal axis of the subchannel extends parallel with a longitudinal axis of the elongate body;(b) installing in the subchannel a system for monitoring operational parameters, the system including a plurality of sensors and a controller for receiving signals from the sensors; and(c) adding additional polymeric material to the subchannel to embed the system within the subchannel.

11. The process defined in Claim 10, further comprising the step of:(d) curing the elongate body and the additional material.

12. The process defined in Claim 11, further comprising the step of partially curing the elongate seal strip body prior to step (c).

13. The process defined in any of Claims 10-12, wherein the additional material is substantially similar to the polymeric material.

14. The process defined in Claim 10, wherein the subchannel extends for a full length of the elongate body.

15. The process defined in Claim 10, wherein the open end of the subchannel has a width less than a maximum width of the subchannel.

16. The process defined in Claim 15, wherein the subchannel has a generally hexagonal profile.

17. The process defined in Claim 10, wherein the polymeric material comprises rubber filled with graphite.

18. The process defined in Claim 10, wherein the sensors are wear sensors.

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