WO2016112148A1 - Limiteur d'écoulement d'air à détection d'ouverture / fermeture - Google Patents

Limiteur d'écoulement d'air à détection d'ouverture / fermeture Download PDF

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Publication number
WO2016112148A1
WO2016112148A1 PCT/US2016/012411 US2016012411W WO2016112148A1 WO 2016112148 A1 WO2016112148 A1 WO 2016112148A1 US 2016012411 W US2016012411 W US 2016012411W WO 2016112148 A1 WO2016112148 A1 WO 2016112148A1
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WIPO (PCT)
Prior art keywords
tube
air flow
tubular segment
sail
movable
Prior art date
Application number
PCT/US2016/012411
Other languages
English (en)
Inventor
Stephen B. Maguire
Original Assignee
Maguire Stephen B
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US14/593,010 external-priority patent/US9550635B2/en
Application filed by Maguire Stephen B filed Critical Maguire Stephen B
Publication of WO2016112148A1 publication Critical patent/WO2016112148A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
    • B65G53/00—Conveying materials in bulk through troughs, pipes or tubes by floating the materials or by flow of gas, liquid or foam
    • B65G53/04—Conveying materials in bulk pneumatically through pipes or tubes; Air slides
    • B65G53/24—Gas suction systems
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C31/00—Handling, e.g. feeding of the material to be shaped, storage of plastics material before moulding; Automation, i.e. automated handling lines in plastics processing plants, e.g. using manipulators or robots
    • B29C31/04—Feeding of the material to be moulded, e.g. into a mould cavity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
    • B65G53/00—Conveying materials in bulk through troughs, pipes or tubes by floating the materials or by flow of gas, liquid or foam
    • B65G53/34—Details
    • B65G53/66—Use of indicator or control devices, e.g. for controlling gas pressure, for controlling proportions of material and gas, for indicating or preventing jamming of material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K17/00—Safety valves; Equalising valves, e.g. pressure relief valves
    • F16K17/20—Excess-flow valves
    • F16K17/22—Excess-flow valves actuated by the difference of pressure between two places in the flow line
    • F16K17/24—Excess-flow valves actuated by the difference of pressure between two places in the flow line acting directly on the cutting-off member
    • F16K17/28—Excess-flow valves actuated by the difference of pressure between two places in the flow line acting directly on the cutting-off member operating in one direction only
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K37/00—Special means in or on valves or other cut-off apparatus for indicating or recording operation thereof, or for enabling an alarm to be given
    • F16K37/0025—Electrical or magnetic means
    • F16K37/0041—Electrical or magnetic means for measuring valve parameters

Definitions

  • This invention relates to manufacture of plastic articles and more particularly relates to pneumatic conveyance and processing of plastic resin pellets prior to molding or extrusion of those pellets into a finished or semi-finished plastic product.
  • Plastics factories have multiple process machines, sometimes several hundred in one location. Virtually all plastics fabricating operations require that each process machine, namely a molding press or an extruder, be supplied automatically with the required raw resin material on a continuous basis.
  • This resin may be supplied in large boxes, called Gaylords, in fiber drums, in 50 pound bags, or more typically may be delivered by bulk truck or rail car, with the resin material then being transferred in bulk into storage silos. In all cases the resin material must be further distributed throughout the plant to each and every process machine. For that reason a great deal of design and capital expense is devoted to the automatic distribution of the raw resin material throughout the plant.
  • Resin pellets nominally about 1/8 inch in size, come in various shapes, with round, square, and cylindrical being the most common.
  • Flowing resin powder is also an option, and very fine but free flowing resin pellets and other granular materials may be conveyed as well.
  • the design variables to be considered for each customer include: Type of resin being conveyed. Size and consistency of the resin pellets. Distances the resin pellets are to be conveyed. Variability of these distances from shortest to longest. Acceptable range for velocity of resin material travel through the lines. Throughput rate of resin required for each machine. Total throughput rate of resin for the entire plant. Excess capacity performance margin so a molding or extrusion process is not interrupted by short term loading issues. Loss of resin material from or at the supply so that only air is being pulled, thereby reducing system vacuum levels and reducing overall design throughput. Loading sequence, or priority, when multiple receiver stations call for material. Detecting problems and alarm conditions. Proper air to material ratio for resin conveying.
  • One of the most important considerations is to hold a correct velocity for the conveyed resin material.
  • the type of resin material dictates the target conveying speed.
  • a high conveying speed is preferred, and air speed in any case must be sufficient to keep the resin pellets suspended and moving in the air stream. But velocity must be limited so as not to damage the pellets. Hard brittle pellets can fracture and break when conveyed, resulting in excessive dust.
  • Air speed and resin conveying velocity are directly related to pump capacity (rated CFM) and horsepower, as well as conveying line diameter. There is always a correct velocity "range” for each type of resin material. It is a design challenge to assure that resin material is conveyed within the correct velocity range.
  • Conveying distances affect system design. Conveying over short distances requires a less powerful vacuum source then over longer distances. Systems are generally sized to produce the best compromise for material velocity between the shortest and longest conveying distance.
  • Required conveying rate usually dictates line size (tube diameter), and this in turn dictates the CFM required to maintain correct velocity in a given diameter conduit. This means different tube sizes in the same system can be a problem if one vacuum pump is to draw air and resin through several different diameter conveying lines. Pumps have known CFM ratings. Pulling air through a small tube will result in higher velocity flow than pulling the same CFM through a larger tube.
  • a preferred approach for conveying plastic resin pellets from a storage location to a process machine which approach is often used in larger facilities, is to install a central vacuum pump or even several vacuum pumps, connected by common vacuum lines to multiple
  • Vacuum pumps connected to the vacuum lines draw vacuum, namely air at pressure slightly below atmospheric, as the vacuum pump sucks air through the "vacuum” line.
  • the suction moves large quantities of air which carries thermoplastic resin pellets through the "vacuum” line.
  • An alternative is to use positive pressure produced by a blower or the exhaust side of a vacuum pump. With such an approach, the positive pressure results in a movement of substantial amounts of air which may be used to carry the plastic resin pellets.
  • the vacuum approach of drawing or sucking pellets through the system conduits is preferable to the positive pressure approach of pushing the resin pellets through the system conduits.
  • vacuum pumps are preferred and vacuum lines are desirable in part because power requirements to create the required vacuum necessary to draw plastic resin pellets through the lines are lower than the power requirements if the plastic resin pellets are pushed through the lines by a blower or by the exhaust side of a vacuum pump.
  • the static pressure within the line may be not much less than atmospheric.
  • positive pressure the dynamic pressure of the air flowing through the line must be relatively high in order to move an adequate quantity of plastic resin pellets.
  • vacuum pump As used herein, and in light of the foregoing explanation, the terms "vacuum pump” and “blower” are used interchangeably.
  • a receiver When one or more central vacuum pumps are connected to multiple receivers, a receiver is typically located over each temporary storage hopper, in which the plastic resin pellets are temporarily stored before being molded or extruded.
  • a temporary storage hopper is typically associated with each process machine.
  • the receiver is connected by a control wire to a central control system.
  • the control system works by selectively opening a vacuum valve located in each receiver, allowing one or several vacuum pumps to work in sequence drawing "vacuum", i.e. below atmospheric pressure air, to carry the pellets among and to multiple receivers as individual ones of the receivers, positioned over individual hoppers associated with the individual process machines, require additional plastic resin pellets.
  • the receiver for a given hopper-process machine combination is actuated by opening the vacuum valve located in or near the receiver, causing the receiver to supply plastic resin pellets by gravity feed into the hopper from where the pellets may be fed further by gravity downwardly into the associated process machine.
  • Plastic resin pellets delivered in bulk are typically pumped into large silos for storage.
  • the distance from a plastic resin pellet storage silo to a process machine may be several hundred feet, or more. Accordingly, when plastic resin pellets are purchased in bulk, a central vacuum- powered conveying system, powered by one or more large, high capacity industrial vacuum pumps, is a necessity.
  • central plastic resin pellet conveying systems have one or more vacuum pumps, each typically from 5 to 20 horsepower. These central systems include central controls connected by wire to each receiver associated with each process machine in the facility. Typically eight, sixteen, thirty-two or sixty-four receivers, each associated with a process machine, may be connected to and served by the central plastic resin pellet vacuum conveying system. Of course, the higher the number of receivers served by the system, the higher the cost.
  • a factor to be considered in designing such a system is the speed of the plastic resin pellets as they flow through a conduit as the plastic resin pellets are carried by the moving air stream drawn by the vacuum pump. If air flow is too slow, the plastic resin pellets fall out of the air stream and lie on the bottom of the conduit, with resulting risk of clogging the conduit. If air flow is too fast, the plastic resin pellets can skid along the conduit surface. In such case, harder, more brittle plastic resin pellets may be damaged, resulting in dust within the conduit, which when drawn into the vacuum pump can damage the vacuum pump and render the system inoperative. Softer plastic resin pellets heat up and can melt from friction when contacting the conduit interior surface. This results in "angel hair" - long, wispy-thin strands of plastic film which eventually clog the conduit and cause the system to shut down.
  • conveying speed of the plastic resin pellets is most often controlled by controlling air flow, measured in cubic feet per minute, and varying the desired and designed cubic feet per minute based on conduit diameter, with a larger diameter conduit requiring more cubic feet per minute of air flow to maintain proper air flow speed through the conduit.
  • Controlling air flow measured in cubic feet per minute, is conventionally done by properly specifying the vacuum pump by capacity and, in some cases, by varying speed of the vacuum pump as the vacuum pump draws the air in a "vacuum" condition through the conduit, carrying plastic resin pellets in the moving, below atmospheric pressure air. Controlling cubic feet per minute of air flow is an indirect way of controlling plastic resin pellet speed as the plastic resin pellets flow through a conduit of a given diameter.
  • a 2 inch diameter conduit requires about 60 cubic feet per minute of air flow to convey typical plastic resin pellets.
  • a 2-1/2 inch diameter conduit typically requires about 100 cubic feet per minute of air flow to convey typical plastic resin pellets.
  • a conventional designer must carefully match the horsepower of a vacuum pump, which has a given cubic feet of air per minute rating, to a selected size conduit, taking into consideration the average distance the plastic resin pellets must be conveyed through the conduit from a storage silo to a receiver or loader. If this results in selection of a 5 horsepower blower/vacuum pump, then a given facility may require several such blowers/vacuum pumps, with each blower/vacuum pump supplying only a selected number of receivers.
  • a single plastic resin molding or extruding facility might theoretically require a 20 horsepower blower and the corresponding cubic feet per minute capability for the conveyance provided by the single blower to meet the total conveying requirements for plastic resin pellets throughout the facility.
  • a single twenty horsepower blower would result in far too high a conveying speed for the plastic resin pellets through any reasonable size conduit.
  • the conveying system for the plastic resin pellets in a large facility is necessarily divided and powered by three or four smaller blowers, resulting in three or four different, separate systems for conveyance of plastic resin pellets.
  • several blowers are connected to a single set of receivers, with one or more of the extra blowers turning "on" only when required to furnish the required extra cubic feet per minute of air flow. This is controlled by a central station monitoring all receivers and all blowers, with the central station being programmed to maintain all of the hoppers associated with the process machines in a full condition, wherever those hoppers are located throughout the facility.
  • the instant invention provides an improvement to known pneumatic plastic resin pellet conveying systems, reducing the costs of those systems while providing consistent control of delivered cubic feet per minute of air.
  • the invention also facilitates easy expansion of the pneumatic plastic resin pellet conveying system as the system grows. Such expandable systems are made feasible by an inventive air flow limiter embodying aspects of this invention.
  • air flow control devices most desirably of the type newly disclosed herein and only slightly less desirably of the type disclosed in co-pending U.S. patent application serial number 14/185,016 entitled “Air Flow Regulator", filed 20 February 2014 in the name of Stephen B. Maguire, are added to each receiver so that the air pulled from any single receiver at the correct predetermined, preselected flow rate. This prevents excessive flow rates and "open" lines that dump too much air into the system.
  • a central control station is not required, and neither is wiring from each receiver to a central control station, thus further reducing costs.
  • CFM is a term referring to a cubic foot of air regardless of the density of the air.
  • SCFM refers to a cubic foot of air at standard temperature and pressure, namely 70° F at sea level.
  • the air flow limiter holds SCFM constant. This means that air flow through the air flow limiter will be faster when the air is thin, such as at high altitudes, and slower when the air is thick, such as at sea- level.
  • the air flow limiter maintains SCFM, namely air flow in standard cubic feet per minute, constant. Stated differently, so long as the SCFM is held steady, as is the case with an air flow limiter, the same weight of air, or number of air molecules, flows through the limiter regardless of conditions. Air flow rate through the limiter may change in terms of the speed of the air, but in all cases the quantity of air flowing, measured in standard cubic feet per minute, is constant.
  • VFD Very Frequency Drive
  • VFD Variable Frequency Drive motors allow vacuum pumps to operate at different speeds, and therefore at different CFM rates, with the vacuum pump pulling different vacuum levels depending on preset information about each receiver being served, and/or making adjustments based on real time feedback of vacuum sensors located at various places in the system.
  • SCFM Standard Cubic Feet per Minute
  • Reading vacuum levels at various points tells the controlling processor if the line is open, which means only air (and no resin material) is present and air is flowing unrestrictedly. This signals a loss of resin material at the source. A high vacuum reading indicates a plugged or nearly plugged line. Normal conditions are present where material is flowing correctly at detected mid- vacuum levels.
  • One line size for all receivers assures the resin transport velocity is more likely to be in the acceptable range.
  • most processes require the basic resin material be delivered at 50 times the rate of additives such as color concentrate.
  • Virgin (or natural) resin pellets may have to be loaded at a rate of 1000 pounds per hour, requiring a 2.5 or 3 inch line size, while color is only required to be delivered at a rate of 20 to 40 pounds an hour.
  • a smaller receiver is used for color, namely a receiver that loads perhaps 5 pounds at a time, while the receiver for the virgin resin material will be larger, perhaps loading 50 pounds of each load cycle.
  • a 2.5 inch line on a 5 pound receiver would be too large.
  • 1.5 inch line would be standard, and the use of 1.5 inch resin conveying line would be better, but this risks velocities that are excessive, resulting in trade-offs in design.
  • one air flow limiter in place as a single air flow limiter at the vacuum pump suction inlet with the vacuum pump being connected to a plurality of receivers all connected in a system. This provides a selected, correct rate of air flow in standard cubic feet per minute. In this embodiment, only a single air flow limiter is used at the vacuum pump inlet, as opposed to the alternative embodiment described above where one air flow limiter is used at each receiver.
  • An advantage of using only a single air flow limiter of the type disclosed herein is that the vacuum pump can be sized and operated for the longest distance over which resin is to be conveyed in a given locale. This can be done while still protecting shorter runs of the system from excessive resin material velocity, where less vacuum is required.
  • One air flow limiter costs less than having an air flow limiter located at every receiver; this provides an advantageous aspect to this approach.
  • each receiver in a facility is preferably fitted with an improved air flow limiter embodying the invention so the flow for each receiver in cubic feet per minute is self- limiting.
  • This approach eliminates the need to match vacuum pumps or blowers to a specific material conduit size or conveyance distance.
  • the improved flow limiter of the invention permits operators to run a very large vacuum pump or blower at a speed that will maintain a desired high level of vacuum throughout the entire vacuum (or pneumatic) plastic resin pellet conveying system.
  • a variable frequency drive control may be used to adjust the speed of the vacuum pump to maintain air flow at the desired standard cubic feet per minute rate through the air flow limiter.
  • each receiver preferably controls its own operation and is not wired to any central control facility.
  • a level sensor preferably tells the receiver to load the hopper of the process machine. Coupled to the level sensor may be a vacuum sensor, which preferably confirms that the main system has sufficient vacuum available to load the receiver. If too many other receivers are currently loading, and the vacuum level is sensed to be below the threshold for effective loading, then the receiver associated with the sensor will wait until vacuum readings rise.
  • the vacuum sensor causes a vacuum valve preferably associated with the receiver to open the connection of the receiver to the conduit carrying the plastic resin pellets, and the receiver fills with resin pellets.
  • each receiver acts on its own sensed information.
  • Use of the high horsepower vacuum pump means that several receivers can load simultaneously.
  • the improved air flow limiter aspect of the invention does several things to make such systems in accordance with the invention possible.
  • the risk of a too high a conveyance speed of the plastic resin pellets through the conduit is eliminated.
  • the empty conduit of the conveying system would ordinarily convey a substantial amount of air, which normally would drop the vacuum reserve of the entire pneumatic conveying system very rapidly.
  • the limiter preferably has a single moving part, namely a valve, which relies on two opposing forces, gravity in one direction and "lift" created by air flow in the opposite direction. Because the improved air flow limiter uses gravity to close the valve portion of the limiter, orientation of the air flow limiter is important. Air flow must be upward, essentially vertically through the air flow limiter, to counter the downward force of gravity.
  • the improved air flow limiter is desirably in the form of a tube with an air flow actuated valve within the tube. In a "no flow” condition, gravity holds the valve closed.
  • the valve opens as air lifts it.
  • the valve would continue moving upwardly except for the fact that the valve reaches a point of air flow restriction, where the valve holds air flow steady at the desired design value. If the valve moves further upwardly towards a "closed” position, this reduces air flow and resulting force in the valve, causing the valve to drop in response to gravity. If the valve drops below the control level, this allows more air flow and consequently the valve rises as the air pushes the valve upwardly. As a result, the valve reaches the desired design valve equilibrium control point essentially instantly and very accurately.
  • Known air flow shutoffs are subject to "vacuum pull", causing them to shut off completely once air begins to flow. This is because in known shutoffs, vacuum "pull" of the vacuum pump is always present.
  • a short vertical tube closes against a flat horizontal surface.
  • air flow is directed through the center of a short tube and escapes over the top edge of the short tube and then around open edges of a flat shutoff surface.
  • a flat, desirably triangular or star-shaped plate is positioned in the air flow below and connected to the short tube. This plate acts as a sail in the air flow and will, as the designed desired standard cubic feet per minute air flow rate is exceeded, provide enough lift to raise the short tube against the shutoff plate.
  • the surface of the end of the short tube, at the short tube end edge, is a horizontal surface and can provide a small vertical force when air travelling upwards impinges on the surface. For this reason, the air flow limiter of the invention uses a very thin wall short tube, to minimize this horizontal surface area of the short tube.
  • air flow rate in cubic feet per minute can be adjusted by adding or subtracting weight from the floating valve, or by adjusting the surface area of the sail, or by adjusting the size or shape of the sail in the air flow.
  • the invention provides a resin delivery system and method that includes an air flow limiter having a preferably vertically oriented tube, a pair of open-ended preferably telescoping tubular internal segments within the tube, with an outer tubular segment preferably being fixed and the other preferably being slidably moveable along the fixed segment in the axial direction.
  • the air flow limiter includes a detector, preferably utilizing an electromagnetic beam, most preferably a visible light beam or an infrared beam, to intersect the slidably moveable telescoping internal segment to determine when the slidably moveable tubular internal segment has contacted a stop and thereby has halted air flow through the air flow limiter due to air flow exceeding the pre- selected design maximum.
  • the air flow limiter further includes a plate extending partially across the interior of the vertically oriented tube and positioned for contacting the moveable one of the telescoping tubular segments and limiting travel of the moveable telescoping tubular segment, with the plate covering the upper, open end of the moveable telescoping tubular segment upon contact therewith.
  • the invention preferably yet further includes a sail positioned in the vertically oriented tube below the telescoping segments, a strut preferably connecting the sail and the moveable telescoping tubular segment, and a baffle preferably positioned to direct upward air flow within the tube through the telescoping tubular segments.
  • the moveable telescoping tubular segment preferably moves vertically within the tube, unitarily with the sail, responsively to air flow upwardly through the tube against the sail.
  • the tubular segments are preferably cylindrical; the surface of the plate contacted by the moveable tubular segment is preferably planar; and the portion of the moveable tubular segment contacting the plate surface is preferably annular.
  • the detector portion of the limiter preferably detects an electromagnetic beam, most preferably a visible light beam or an infrared beam to determine when the top portion of the moveable tubular segment has contacted the plate surface.
  • a surface of the plate contacted by the moveable tubular segment is flat, the tubular segments are cylindrical, and the circular edge of the tubular segment contacting the plate service is annular and normal to the axis of the tubular segment.
  • this invention provides a resin delivery system having at least one air flow limiter consisting of a vertically oriented tube, a tubular segment within the tube, which segment is moveable in the axial direction, a plate extending at least partially across the interior of the tube for contacting the movable tubular segment and defining a limit of travel of the moveable tubular segment, a sail positioned in the tube below the moveable tubular segment and being moveable vertically within the tube, a strut connecting the tubular segment and the sail, a baffle connected to and located within the tube defining a lower limit of travel of the moveable tubular segment upon contact of the strut with an upper extremity of the baffle, and a emitter-detector combination in which the emitter preferably emits an electromagnetic beam and the detector detects the electromagnetic beam when the
  • the moveable tubular segment is in sliding telescoping engagement with the tubular portion of the baffle, directing upward air flow within the tube, with the moveable tubular segment being moveable unitarily with the sail in response to upward air flow through the tube contacting the sail.
  • this invention provides a resin delivery system that includes at least one air flow limiter having a vertically oriented tube with a sail assembly positioned in the tube and moveable therewithin responsively to air flow through the tube to regulate air flow through the tube and to stop air flow thorough the tube upon air flow exceeding a preselected value expressed in standard cubic feet per minute.
  • An emitter-detector having a vertically oriented tube with a sail assembly positioned in the tube and moveable therewithin responsively to air flow through the tube to regulate air flow through the tube and to stop air flow thorough the tube upon air flow exceeding a preselected value expressed in standard cubic feet per minute.
  • combination preferably using an electromagnetic beam, provides the beam and projects it across the tube interior to intersect the vertically oriented moveable tubular assembly when the moveable tubular assembly is in a position of having stopped air flow through the air flow limiter due to air flow exceeding the pre-selected maximum design value.
  • this invention provides a method for conveying granular plastic resin by controlled air flow where air flow control involves the steps of providing a vertically oriented tube, positioning a moveable sail assembly including a sail within the tube, positioning a stop within the tube, and permitting the sail assembly to move
  • a detector senses that the sail assembly is at the position contacting the stop and thereby blocking air flow through the tube.
  • this invention provides a pneumatic resin delivery system utilizing air flow limiting apparatus including a vertically oriented first tube, a vertically oriented second tube which is moveable along and within the first tube, a baffle within the first tube for forcing air flow in the first tube through the second tube, a guide within the first tube for limiting the second tube to vertical co-axial movement within and relative to the first tube, a sail within the first tube being connected to the second tube and being moveable responsively to air flow within the first tube, and a stop within and connected to the first tube for limiting vertically upward travel of the second tube.
  • this invention provides apparatus for conveying granular plastic resin from a supply to receivers that retain and dispense the resin when needed by a process machine, where the apparatus includes a vacuum pump, a single air flow limiter connected to a suction head of the vacuum pump, a first conduit connecting the receivers to the air flow limiter, and a second conduit connecting the granular material supply to the receivers.
  • suction created by operation of the vacuum pump draws granular plastic resin from the supply into the receivers through the second conduit and draws air from the second conduit through the receivers, the first conduit and the air flow limiter.
  • the air flow limiter is oriented in a vertical direction for vertical flow of air upwardly therethrough.
  • the emitter-detector combination are preferably oriented to provide a horizontal beam within and passing through a tubular housing portion of the air flow limiter with the beam preferably being perpendicular to the air flow limiter axis.
  • this invention provides apparatus for conveying granular plastic resin material from a supply of resin material to receivers that retain and dispense the resin material when needed by a process machine, where the apparatus includes a vacuum pump, air flow limiters connected to outlets of the receivers, with the air flow limiters being vertically oriented for vertical flow of air drawn by suction therethrough, a first conduit connecting the air flow limiters to a suction head of the vacuum pump and a second conduit connecting the granular resin material supply to the receivers.
  • suction created by operation of the vacuum pump draws granular plastic resin from the supply of granular plastic resin material into the receivers through the second conduit, and also draws air from the second conduit through the receivers, the air limiters, and the first conduit.
  • At least one of the air flow limiters preferably consists of a tube, a tubular segment within the tube that is moveable in the axial vertical direction, a plate extending at least partially across the interior of the tube for contacting the moveable tubular segment and defining a limit of vertical travel of the moveable tubular segment, a sail connected to the moveable tubular segment and being moveable therewith within the tube, and a baffle connected to and within the tube defining a second limit of vertical travel of the moveable tubular segment, where the moveable tubular segment is in sliding telescoping engagement with the tubular portion of the baffle and the baffle directs air flow within the tube into the tubular segment.
  • the moveable tubular segment moves unitarily with the sail in response to vertical air flow through the tube contacting the sail.
  • Figure 1 is a schematic representation of a resin delivery system with a single air flow regulator in accordance with aspects of the invention.
  • Figure 2 is a schematic representation of a resin delivery system with a plurality of air flow regulators in accordance with aspects of this invention.
  • Figure 3 is an isometric view of the exterior of an air flow limiter portion of apparatus for pneumatically conveying granular plastic resin as disclosed in co-pending applications serial numbers 14/185,016 and 14/574,561 referenced above.
  • Figure 4 is a front elevation of the air flow limiter illustrated in Figure 3.
  • Figure 5 is an isometric sectional view of the air flow limiter illustrated in Figures 3 and 4, with the section taken at arrows 3-3 in Figure 4.
  • Figure 6 is a sectional view in elevation of the air flow limiter illustrated in Figures 3 and 5, with the section taken at lines and arrows 3-3 in Figure 4, with air flow through the air flow limiter being depicted in Figure 6 by curved dark arrows.
  • Figure 7 is a sectional view in elevation, similar to Figure 6, of the air flow limiter illustrated in Figures 3 through 6, but with the air flow limiter internal parts in position whereby there is no air entering the air flow limiter and hence there is no air flow upwardly through the air flow limiter, in contrast to the condition with such air flow shown in Figure 6.
  • Figure 8 is a sectional view in elevation, similar to Figures 6 and 7 of the air flow limiter illustrated in Figures 3 through 7, but with the air flow limiter internal parts in position where there is an excessive amount of air attempting to enter the air flow limited but there is no air flow upwardly through the air flow limiter due to the air flow limiter valve having moved to block air flow upwardly through the air flow limiter, in contrast to air flow upwardly through the air flow limiter as shown in Figure 4.
  • Figure 9 is an exploded isometric view of the air flow limiter illustrated in Figures 3 through 8.
  • Figure 10 is an isometric view of the movable portion of the air flow limiter illustrated in Figures 3 through 9.
  • Figure 11 is a sectional view of an air flow limiter similar to Figures 6, 7 and 8, illustrating an alternate construction of the baffle portion of the air flow limiter.
  • Figure 12 is sectional view of the air flow limiter similar to Figures 6, 7, and 11, illustrating a second alternate construction of the baffle portion of the air flow limiter.
  • Figure 13 is a sectional view in elevation, similar to Figure 7, of an improved air flow limiter in accordance with the invention, with the air flow limiter internal parts in position whereby there is no air entering the air flow limiter, the sail assembly has not been lifted by any air flow, the electromagnetic beam passes through the air flow limiter without impinging on any internal parts and there is no air flow upwardly through the air flow limiter.
  • Figure 14 is a sectional view in elevation of the air flow limiter illustrated in Figure 13, with the air flow limiter internal parts in position whereby no air can flow through the air flow limiter due to those internal parts having blocked air flow due to instantaneous air flow exceeding the design value and with the electronic beam, which would normally go from an emitter to a detector, being blocked by the air flow limiter internal parts, thereby indicating that air flow has exceeded a maximum design value and has been halted.
  • vacuum means "air at slightly below atmospheric pressure.”
  • the "vacuum” meaning air at slightly below atmospheric pressure
  • This invention is based on the flow limiter disclosed and claimed in pending United States patent application 14/185,016 referenced above and adds at least a sensor to detect when the limiter has stopped flow, or to detect other flow conditions, according to the location of the sensor.
  • the limiter When air flow is below the design limit, the limiter remains fully open. The moment air flow exceeds the design limit the limiter closes instantly and fully to the point at which it properly stops flow. The movement is sudden and complete. There is no intermediate modulation of the limiter. It does not close gradually nor does any air flow close it partially. For this reason it is easy to detect closing.
  • the preferred way to do this is to place a photo detection device on one side of the limiter, so that it can detect when a beam of light is either blocked, or reflected by the valve closing. A clear window may be used, or the detection device can be mounted into the tubular wall of the limiter.
  • FIG. 1 apparatus for conveying granular plastic resin material from the supply to receivers that retain and dispense the resin material when needed by a process machine is illustrated in Figure 1.
  • the apparatus which is designated generally 88 in Figure 1, preferably includes a vacuum pump designated generally 92 and shown schematically in Figure 1.
  • the vacuum pump preferably includes a vacuum pump suction head 93 also shown schematically in Figure 1.
  • Connected to the vacuum pump suction head 93 is an airflow limiter 30 shown only in schematic form in Figure 1, but shown in various details in Figures 3 through 14.
  • Airflow limiter 30 receives vacuum drawn by vacuum pump 92 through vacuum drawing conduit 100.
  • Vacuum drawing conduit 100 is connected to a plurality of receivers 16, each of which receives, retains and dispenses, as needed, granular plastic resin material to a machine, such as a gravimetric blender, or an extruder, or a molding press, as located preferably below a receiver 16.
  • a machine such as a gravimetric blender, or an extruder, or a molding press
  • FIG. 1 Further illustrated in Figure 1 is a hopper 18 for storage of granular plastic resin material therein and a resin conveying conduit 98, which serves to draw resin from hopper 18 and to deliver the resin through resin conveying conduit 98 to the respective receivers as vacuum is drawn by the vacuum pump, with vacuum propagating through air flow limiter 30, vacuum drawing conduit 100, the various receivers 16, and resin conveying conduit 98, back to hopper 18.
  • a resin conveying conduit 98 which serves to draw resin from hopper 18 and to deliver the resin through resin conveying conduit 98 to the respective receivers as vacuum is drawn by the vacuum pump, with vacuum propagating through air flow limiter 30, vacuum drawing conduit 100, the various receivers 16, and resin conveying conduit 98, back to hopper 18.
  • FIG. 2 shows an alternate embodiment of a resin conveying system where this alternate embodiment of the conveying system has been designated 88 A.
  • Figure 2 depicts a vacuum pump 92 shown in schematic form having a vacuum pump suction head 93 also depicted in schematic form.
  • vacuum drawing conduit 100 leads directly into and communicates with vacuum pump suction head 93.
  • an air flow limiter 30 is provided for each receiver 16, with the air flow limiter 30 for a respective receiver 16 being located in a portion of a connection conduit 102 that connects a respective receiver to vacuum drawing conduit 100.
  • each air flow limiter 30 is depicted in a vertical orientation, just as is airflow limiter 30 depicted in a vertical orientation in Figure 1.
  • Each receiver is connected by connection conduit 102 to vacuum drawing conduit 100 with air flow limiter 30 forming a portion of connection conduit 102.
  • a first conduit 98 serves to convey granular plastic resin from hopper 18 to the respective receivers in response to vacuum drawn by vacuum pump 92 as that vacuum propagates from vacuum pump 92 through second conduit 100, connection conduits 102, receivers 16, and resin conveying conduit 98 to hopper 18.
  • the air flow limiter 30 portion of the resin delivery systems is preferably in the general form of a vertically oriented tube, preferably having inlet and outlet ends 54, 56 respectively.
  • the tubular character of air flow limiter 30 is apparent from Figures 3 through 14, where air flow limiter 30 preferably includes a vertically oriented exterior tube 32, with open-end caps 58, 60 defining and providing open inlet and outlet ends 54, 56 respectively.
  • End caps 58, 60 are open, of generally cylindrical configuration, and are configured to fit closely about vertically oriented tube 32 so as to provide a substantially air tight fit between end caps 54, 56 and tube 32.
  • air flow limiter 30 preferably includes, within vertically oriented exterior tube 32, a horizontally positioned plate 46, which is oriented perpendicularly to the axis of tube 32.
  • Plate 46 is preferably configured as a circular disk of lesser diameter than the inner diameter of vertically oriented tube 32, with plate 46 further preferably including three legs extending outwardly from the circular interior disk portion of plate 46.
  • Legs of plate 46 are designated 62 in Figure 9, while the circular interior portion of plate 46 is designated 64 in Figure 9.
  • Plate 46 is secured to the interior of vertically oriented outer tube 32 by attachment of legs 62 to the interior surface of tube 32. Any suitable means of attachment, such as by welding, adhesive, mechanical screws, or end portion of legs 62 defining tabs fitting into slots within tube 32 as shown in Figure 5, may be used.
  • a baffle 52 is positioned within vertically oriented outer tube 32, below plate 46.
  • Baffle 52 has a lower conical portion 66 and an upper cylindrical portion 44, with cylindrical portion 44 defining a fixed internal tubular segment of air flow limiter 30.
  • Baffle 52 is preferably retained in position by a pair of screws designated 68, 70 respectively.
  • Baffle 52 preferably rests on screw 68.
  • Screw 70 preferably fits against the fixed internal tubular segment 44 portion of baffle 52 to secure baffle 52 in position within vertically oriented external tube 32.
  • Lateral force applied by screw 70 in a direction perpendicular to the axis of vertically oriented external tube 32, with screw 70 in contact with fixed internal tubular segment 44, serves to effectively retain baffle 52 against movement within vertically oriented external tube 32.
  • baffle 52 defining fixed internal tubular segment 44, is adapted for sliding telescopic engagement with movable tubular segment 42.
  • Fixed to movable tubular segment 42 is a first strut 48 preferably extending transversely across the upper portion of movable tubular segment 42 and preferably secured on either end to movable tubular segment 42, as illustrated in Figure 10.
  • Preferably extending downwardly from first strut 48 is a second strut 50, preferably secured to first strut 48 and preferably also to a sail 34, as illustrated in Figure 10 and in Figures 5, 6, 7, 8, 9, 13 and 14.
  • Movable sail 34 is preferably planar and positioned fixedly on second strut 50 to remain perpendicular with respect to the axis of vertically oriented outer tube 32.
  • Movable sail 34 is preferably of generally triangular configuration, as illustrated in Figures 9 and 10, with the sides of the triangle curving slightly inwardly.
  • the curved edges 72 of movable sail 34 converge and terminate to form small rectangularly shaped extremities of sail 34, which are designated 76 in Figure 9.
  • Movable sail 34 is positioned within generally vertically oriented outer tube 32 so that rectangular extremities 76 are closely adjacent to but do not contact the inner surface of vertically oriented outer tube 32, so long as sail 34 moves vertically up and down within vertically oriented external tube 32.
  • the rectangular shape of extremities 76 with their outwardly facing planar surface assures minimal friction and consequent minimal resistance to movement of movable sail 34 in the event one of rectangular extremities 76 contacts the interior surface of vertically oriented tube 32, should sail 34 for some reason move laterally or otherwise and become skew to the vertical axis of tube 32.
  • Movable internal tubular segment 42 is telescopically movable, unitarily with sail 34, relative to and along fixed internal tubular segment 44.
  • a lower limit of movement of movable tubular segment 42 is illustrated in Figure 7, where the first strut portion 48 of movable tubular segment 42 (shown in Figure 10) rests on the upper circular edge of fixed internal tubular segment 44. This is the condition when no air is flowing or drawn through the air flow limiter and gravity causes sail 34 together with movable internal tubular segment 42 to drop, with first strut 48 coming to rest on the upper circular edge of fixed tubular segment 44.
  • first and second struts 48, 50 and sail 34 may oscillate somewhat about the position at which air flow drawn by suction is at the desired level, as the vacuum pump drawing air through flow limiter 30 varies in cubic feet per minute of air drawn.
  • ends of first strut 48 which is depicted as being horizontally disposed in the drawings, are mounted in movable tubular segment 42 in movable fashion such that first strut 48 can move slightly, rotationally, relative to movable internal segment 42.
  • first strut 48 being slightly rotatable relative to movable internal tubular segment 42, effectively precludes movable internal tubular segment 42 from binding with respect to fixed internal tubular segment 44 and thereby being restricted from what would otherwise be freely telescoping movement of movable internal tubular segment 42 relative to fixed internal tubular segment 44.
  • first strut 48 is rotatable relative to movable internal tubular segment 42, to provide maximum freedom of vertical motion of movable internal tubular segment 42 in the event movable sail 34 becomes skew to the axis of vertically oriented exterior tube 32, with consequent frictional force restricting vertical movement of movable sail 34.
  • Baffle 52 preferably includes two portions, the upper portion preferably being defined by fixed internal tubular segment 44 and a lower portion preferably being defined by conical portion 66 of baffle 52.
  • a lower edge of baffle 52 is circular and is designated 84 in the drawings. Circular edge 84 fits closely against the annular interior wall of vertically oriented exterior tube 32 so that all air passing upwardly through air flow limiter 30, namely through vertically oriented exterior tube 32, is constrained to flow through the interior of baffle 52.
  • the tight fitting of the circular lower edge of baffle 52 against the interior wall of vertically oriented exterior tube 32 forces all air entering flow limiter 30 from the bottom to flow through the interior of baffle 52, flowing upwardly through lower conical portion 66 of baffle 52.
  • baffle 52 may be constructed from two pieces that fit closely together, with the two pieces being in facing contact in the area where they define fixed internal tubular segment 44, but diverging one from another in the area where they define conical portion 66 of baffle 52. As illustrated in Figure 12, the two portions of baffle 52 are designated “66A” and “66B” where they diverge, with baffle portion 66A serving to channel air flow upwardly through vertically oriented exterior tube 32 into fixed internal tubular segment portion 44 of baffle 52.
  • baffle portions 66A and 66B The space between the lower parts of baffle portions 66A and 66B is filled with a filler material 86 to provide additional assurance that all air entering vertically oriented exterior tube 32 from the bottom flows through fixed internal tubular segment 44 and on through movable internal tubular segment 42, and does not pass around the edge of baffle 52, namely between baffle 52 and the interior surface of vertically oriented exterior tube 32.
  • Filler material 86 provides additional structural rigidity for flow limiter 30.
  • baffle 52 is one piece, preferably molded plastic, as illustrated in Figure 11, where baffle 52 is designated 52B to distinguish it from the baffle construction illustrated in Figure 12 and the baffle construction illustrated in the other drawing figures.
  • the one piece construction means that there is no need or space for any filler material.
  • the assembly illustrated in Figure 10 comprising the moveable internal tubular segment 42, first strut 48, second strut 50 and moveable sail 34 may be constructed as a single piece or several pieces as required.
  • the assembly of moveable internal segment 42, first and second struts, 48, 50 and moveable sail 34 is referred to as a "sail assembly.” It is not required that first and second struts 48, 50 be separate pieces; they may preferably be fabricated as a single piece. Additionally, second strut 50, which has been illustrated as a machine screw in Figures 9 and 10, need not be a machine screw.
  • any suitable structure can be used for second strut 50 and it is particularly desirable to fabricate first and second struts 48 and 50 from a single piece of plastic or metal, by molding, by machining, by welding, or by otherwise fastening two pieces together.
  • any other suitable means for attachment of the second strut or a vertical portion of a strut assembly to moveable sail 34 may be used.
  • an air flow limiter in accordance with the invention has been designated generally 30' and includes a vertically oriented exterior tube 32 and a moveable sail 34; these components are preferably the same as those described with respect to air flow limiter 30 above.
  • Air flow limiter 30' further includes a pair of concentric telescoping tubular segments 40, a moveable internal tubular segment 42, a fixed internal tubular segment 44, a flow limiting horizontal plate 46, first and second struts 48, 50, a baffle 52, and an inlet end 54 and an outlet end 56, all preferably the same as the air flow limiter illustrated in the other drawing figures and as described above.
  • Other parts that are shown in Figures 13 and 14, and that appear to be identical to corresponding parts shown in Figures 3 through 12, are identical and are not further delineated herein for the sake of some brevity.
  • Air flow limiter 30' in accordance with the invention includes a pair of housings 110, 112 mounted on either side of vertically oriented exterior tube 32, where housing 110 is provided generally for an emitter 114, and housing 112 is provided generally for a detector 116. Any suitable emitter-detector combination can be used. Preferably emitter 114 emits an
  • electromagnetic beam 118 and detector 116 detects beam 118 when beam 118 impinges on detector 116.
  • Emitter 114 and detector 116 are mounted within housings 110, 112 at the positions illustrated in Figures 13 and 14. At this position, when emitter 114 emits an electromagnetic beam 118 and moveable internal tubular segment 42 is in contact with flow limiting horizontal plate 46, electromagnetic beam 118 is blocked by the cylindrical wall of tubular segment 42. Hence, detector 116 does not detect any electromagnetic beam and detector 116 sends a signal to an appropriate monitoring station or computer or other device indicating that the air flow limiter has blocked flow due to air flow through the air flow limiter exceeding the pre-selected design value.
  • electromagnetic beam 118 from emitter 114 is detected by detector 116.
  • the beam is indicated as 118 in the drawing.
  • Detection of electromagnetic beam 118 by detector 116 indicates that either there is some permissible flow through the air flow limiter 30 ' or the entire resin delivery system has been shut down, meaning there is no air flow entering air flow limiter 30' at inlet end 54.
  • the no air flow operation, or no air flow entering inlet end 54 is essentially of no interest, in that the air flow limiter of the invention, with the emitter-detector combination, is a self-limiting device as described above.
  • Air flow limiter 30' preferably contains no springs. Air flow limiter 30' preferably contains no sensors to provide operating feedback to a control device for regulation of air flow limiter 30'. No feedback control sensors are needed since because flow limiter 30' is self- regulating and once in place, an air flow limiter is not subject to outside intervention or control. Air flow limiter 30' preferably includes a tubular valve, closing against a flat surface, where the tubular valve is defined by movable internal tubular segment 42 closing against flow limiting horizontal plate 46. Movable internal tubular segment 42 is in the form of an open-ended cylinder and is connected to a plate in the form of movable sail 34 to move movable tubular segment 42 against flow limiting horizontal plate 46. Air flow limiter 30' uses gravity alone to open the valve defined by the assembly of movable internal tubular segment 42, movable sail 34, and the connecting structure therebetween.
  • the movable internal tubular segment 42 is preferably made with a very thin wall, preferably from metal tubing, where the wall is preferably less than 1/32 inch in thickness.
  • the air flow limiter of the invention functions equally well with a vacuum pump drawing air through air flow limiter 30' from bottom to top by application of vacuum to outlet end 56 as depicted generally in Figures 1 and 2, or by air being supplied under positive pressure at inlet end 54 for passage upwardly through air flow limiter 30'.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Robotics (AREA)
  • Processing And Handling Of Plastics And Other Materials For Molding In General (AREA)

Abstract

La présente invention concerne un procédé et un appareil de régulation de l'écoulement d'air, comprenant un tube orienté verticalement, un ensemble de voile positionné dans le tube et pouvant se déplacer à l'intérieur de celui-ci en réponse à un écoulement d'air à travers le tube pour réguler le débit d'air à travers le tube et pour arrêter l'écoulement d'air à travers le tube lorsque le débit d'air à travers le tube dépasse une valeur présélectionnée, doté d'un détecteur destiné à détecter quand l'ensemble de voile a arrêté l'écoulement d'air à travers le tube lorsque le débit d'air dépasse ladite valeur présélectionnée.
PCT/US2016/012411 2015-01-09 2016-01-07 Limiteur d'écoulement d'air à détection d'ouverture / fermeture WO2016112148A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US14/593,010 US9550635B2 (en) 2014-02-20 2015-01-09 Air flow limiter with closed/open sensing
US14/593,010 2015-01-09

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WO2016112148A1 true WO2016112148A1 (fr) 2016-07-14

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US3621873A (en) * 1969-07-08 1971-11-23 Marotta Valve Corp Pneumatic fuse
US4269223A (en) * 1980-04-14 1981-05-26 The Aro Corporation Resettable pneumatic overrun control valve
US4402635A (en) * 1980-07-21 1983-09-06 Nisshin Flour Milling Co., Ltd. Pneumatic conveyor system
US4501518A (en) * 1982-08-17 1985-02-26 Pneuveyor Systems Limited Automatic pneumatic feeder
US6158363A (en) * 1999-05-21 2000-12-12 Flexi-Coil Ltd. Apparatus for dispensing particles
US20040221893A1 (en) * 2003-05-06 2004-11-11 Johnson Dwight N. Excess flow shutoff
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US20150232287A1 (en) * 2014-02-20 2015-08-20 Stephen B. Maguire Air flow regulator

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Publication number Priority date Publication date Assignee Title
GB203758A (en) * 1922-06-09 1923-09-10 Henry James Deane Improvements in valve mechanism
GB271930A (en) * 1926-02-01 1927-06-01 Sturtevant Eng Co Ltd Improvements in pneumatic despatch apparatus
US3621873A (en) * 1969-07-08 1971-11-23 Marotta Valve Corp Pneumatic fuse
US4269223A (en) * 1980-04-14 1981-05-26 The Aro Corporation Resettable pneumatic overrun control valve
US4402635A (en) * 1980-07-21 1983-09-06 Nisshin Flour Milling Co., Ltd. Pneumatic conveyor system
US4501518A (en) * 1982-08-17 1985-02-26 Pneuveyor Systems Limited Automatic pneumatic feeder
US6158363A (en) * 1999-05-21 2000-12-12 Flexi-Coil Ltd. Apparatus for dispensing particles
US20040221893A1 (en) * 2003-05-06 2004-11-11 Johnson Dwight N. Excess flow shutoff
CN202302166U (zh) * 2011-07-29 2012-07-04 中国中材国际工程股份有限公司 一种恒流量调节阀
US20150232287A1 (en) * 2014-02-20 2015-08-20 Stephen B. Maguire Air flow regulator

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116163035A (zh) * 2023-03-02 2023-05-26 安徽寿县银丰棉业有限责任公司 一种风力送棉管道自检测及疏通装置

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