This disclosure generally pertains to apparatus for metering material that includes particles. More specifically, this disclosure concerns apparatus having a compressed air acceleration.
Overview:
This disclosure has particular application to pouching machines used for forming and assembling pouches of particulate material, such as by way of example fine cut smokeless tobacco. Typical pouching machines simultaneously form and assemble, for example, ten pouches from a substantially continuous strip or web of pouch material and metered charges of prepared smokeless tobacco. To effect the simultaneous pouch assembly, pouching machines typically include a bank of generally vertical tobacco feed tubes. Typical pouching machines also include arrangements for drawing and directing a strip or ribbon of pouch web to each feed tube, and wrapping the strip around the corresponding feed tube to form a tubular formation, as well as arrangements to repetitively close and seal that tubular formation so as to form a lower transverse seam at a lower end portion of the tubular web formation just prior to charging each tubular formation with predetermined amount of smokeless tobacco. The pouching machine further includes arrangements for repetitively feeding individual charges of tobacco down corresponding feed tubes and into corresponding tubular formations. After each tobacco charge, the pouching machines close and seal the tubular formation at a second location above the tobacco charge to form an individual loaded and sealed pouch, which is then severed from the tubular formation.
Typically, smokeless tobacco material has a low moisture content, for example, about 30 to about 40% moisture level, and optionally includes flavorants, humectants and/or other tacky substances. Accordingly, smokeless tobacco has a tendency to stick to machine surfaces. Such smokeless tobacco is difficult to feed through pouch forming machines that rely merely on gravity feed techniques. Some pouching machinery incorporates pressurized air in the tobacco feed tubes to augment gravitational delivery of the smokeless tobacco charges. Because drier tobaccos are lighter than wetter tobaccos, the drier tobaccos have a greater tendency to scatter if subjected to jets of pressurized air during feeding, and that scatter can adversely affect the top seal on the associated pouch.
Prior pouching machines include a tobacco feed mechanism for repetitively discharging a predetermined amount of tobacco from a hopper or the like into a funnel at the upper end portion of a tobacco feed tube. Generally, if gravity is the only active force to move the tobacco down the feed tube, a charge of tobacco released into the tube forms into a column of tobacco traveling down the feed tube such that it is constrained along a significant path length that may be too long for proper filling operations. More particularly, not all of the entrained tobacco may have time to enter the confines of a partially closed pouch before the machine closes and seals the pouch along its upper transverse seam.
One solution has been to establish a Venturi arrangement at the base of the funnel. In this arrangement, pressurized air is introduced into the feed tube from a manifold through four to six or so small channels. Those small channels are fixed in size and may vary from tube to tube depending on machine tolerances and the like. Any clogging of one or more of the small channels tends to affect tobacco delivery for that feed tube in such a way that the bank of feed tubes performs inconsistently from one feed tube to another.
Another disadvantage of the foregoing arrangement that the small channels may impart a horizontal or transverse velocity component to the air being introduced through the small channels, with the result that some tobacco flow back may be caused.
It is desired to have the feed tubes of the bank of tobacco feed tubes operate consistently amongst one another so that filling operations across the entire bank are consistent with one another.
The many innovative features and aspects of the present disclosure will be apparent to those skilled in the art when this specification is read in conjunction with the attached drawings wherein like reference numerals are applied to like elements and wherein:
In the production of pouched products, including for example and without limitation, smokeless tobacco products, continuous-motion packaging machinery is often used, and is commonly known as form/fill/seal equipment. Such machinery receives packaging material is substantially continuous strips, receives material to be pouched as a substantially continuous supply from a supply chamber, meters substantially uniform quantities of the material, partially forms a pouch, fills the metered material into the pouch, and finally seals the pouch such that the pouch surrounds that material. While various companies make such equipment, one such company is known as Ropak.
Typical form/fill/seal equipment produces pouched products in a plurality of parallel streams of packaging material and product. For example, 5, 10, or more parallel lanes may be provided. Operating speeds on the order of 100 cycles per minute are known for each of the parallel lanes. As may be expected, that actual manufacturing speed depends on, for example, product flow characteristics, packaging materials used, and temperature at which filling occurs.
In accord with this disclosure, a form/fill/seal apparatus 10 typically includes a plurality of suitable dose delivery apparatuses 20 (see
Each dosing apparatus 20 may include a supply conduit 24 connected at one end to the form/fill/seal apparatus 10 and connected at the other end to metering apparatus 12. The metering apparatus 12 is operable to receive particulate material from the apparatus 10, parse the particulate material into predetermined portions, doses, or quantities, and then deliver those predetermined portions, doses, or quantities of particulate material to the upper end of the dose delivery apparatus 20 at predetermined time intervals. The predetermined time intervals are selected so that a dose is delivered to the dose delivery apparatus 20 as each partial pouch is ready to be filled.
While the metering apparatus 12 may take a variety of physical forms and arrangements, a presently preferred arrangement is depicted in
The feed screws 14a, 14b are preferably designed such that the flight of one screw cleans the flight of the adjacent screw as the two screws rotate. This characteristic of the feed screws 14a, 14b helps assure consistent weight and volume for the predetermined doses being delivered to the dose delivery apparatus 20. Furthermore, the feed screws 14a, 14b are preferably fabricated from polyether ether ketone (PEEK).
The metering apparatus 12 also includes a housing 16 (see
The discharge end of the housing 16 is connected to a snout 18 which encloses the end of the housing and couples the housing 16 to the upper end of the funnel 32 of the dose delivery apparatus 20. The snout 18 assures that particulate tobacco material delivered to the dose delivery apparatus 20 by the feed screws 14a, 14b does not escape and falls into the dose delivery apparatus 20. In addition, the snout 18 is effective to avoid any external contamination of the particulate tobacco material passing therethrough. The snout 18 is also preferably fabricated from PEEK.
The use of PEEK as a preferred material for fabrication of the feed screws 14a, 14b, the housing 16, and the snout 18 has several advantageous and desirable attributes. PEEK functions as a thermal insulator. Thus, use of PEEK between the delivery apparatus 10 and the dose delivery apparatus 20 functions to substantially thermally insulated those apparatuses from one another. Moreover, PEEK substantially reduces and effectively avoids sticking of the particulate tobacco material to the surfaces of the housing, the feed screws, and the snout. Especially where the apparatus must be disassembled and cleaned on a regular basis (e.g., daily), this attribute is highly advantageous because it can reduce the cleaning time and thus add more processing time to the apparatus.
For purposes of this disclosure, the particulate material may be particulate tobacco that has optionally been blended with other components including, for example, flavorants, humectants, and/or other substances, some or all of which may be tacky or may add tackiness to the particulate tobacco. The particulate tobacco material may include fine cut tobacco that has been comminuted at about 70 cuts per inch. Preferred particulate tobacco material may include up to about 39% oven volatiles.
The snout 18 of the metering apparatus 12 attaches to a supply funnel 32 (see
At the bottom end, the air accelerator assembly 34 attaches to a dosing tube 36. That dosing tube 36 preferably terminates in a position where the pouch has been partially formed and can receive particulate material from the discharge end of the dosing tube 36.
The air accelerator assembly 34 includes a body 50, and an internal member 52 which is axially adjustable with respect to the body 50 along an axis 54. Preferably, the funnel member 32 is rotationally symmetric about the axis 54. Internal surfaces of the body 50 that are exposed to air flow, as well as surfaces of the internal member 52 that are exposed to air flow or to product flow are also rotationally symmetric with respect to the axis 54.
The narrow or lower end of the funnel member 32 preferably includes a radially extending flange 56 having a periphery that corresponds to the outer peripheral surface of the body 50. In addition, the flange 56 of the funnel member 32 includes a radially extending annular face 64 which is configured to mate with a corresponding radially extending annular face 66 at the upper end of the body 50. The flange 56 preferably also includes a projecting land 68 which is received in a threaded bore 70 of the body 50. Cooperation between the projecting land 68 and the associated bore 70 assures that the body 50 and the funnel member 32 are coaxial when joined together. To that end, a plurality of axially extending bolts, or threaded fasteners 58, may be used to attach the flange 56 and the body 50. Suitable gasket material may be provided between the abutting surfaces 64, 66 of the flange 56 and the body 50, respectively, if desired.
Extending longitudinally through the body 50, along the axis 54, is a body cavity that includes a threaded, generally cylindrical portion adjacent the funnel member 32, a frustoconical portion 72 extending downstream from the threaded portion, and a discharge tube connection portion at the lower or bottom end of the body 50. The frustoconical portion 72 essentially matches the diameter of the threaded portion at it upstream end. In addition, the downstream or lower end of the frustoconical portion 72 is preferably sized to have a diameter corresponding to the inside diameter of the discharge tube 36. The discharge tube 36 is preferably attached to the downstream end of the body 50 using a suitable conventional attachment. For example, any of a threaded connection, a welded connection, or an adhesively bonded and sealed connection would be satisfactory.
Turning to the longitudinally movable or adjustable member 52 of the air accelerator assembly 34, the adjustable member 52 includes a generally cylindrical longitudinal bore 80 extending from the upstream end to the downstream end of the adjustable member 52. The longitudinal bore 80 preferably has a diameter corresponding to the opening at the discharge end of the funnel member 32 so that particulate material can move downwardly through the funnel member 32 and into the longitudinal bore 80 substantially free of impediment.
The upper or upstream end of the adjustable member 52 includes a flange portion 84 preferably having a peripherally threaded portion that mates with the threaded portion of the cavity in the body 50. Cooperation between the externally threaded flange 84 and the internally threaded portion of the body cavity not only secures the adjustable member 52 in the body 50, but also allows the adjustable member 52 to have its spatial relationship with the body 50 controlled in the longitudinal direction along the axis 54.
Preferably, the exterior surface of the adjustable member 52 also includes a frustoconical surface 82 extending from the flange 84 to the distal end 88 at the downstream end of the adjustable member 52. Preferably, the frustoconical surface 82 meets the longitudinal bore 80 at the distal end 88 of the adjustable member 52 so that an acute sharp angle is defined in the material of the adjustable member 52. Both the frustoconical surface 82 of the adjustable member 52 and the frustoconical portion of the cavity in the body 50 are preferably polished. Because the facing frustoconical surfaces define a chamber for pressurized air, and because it is desirable to accurately control the flow rate of pressurized air through that chamber, it is believed to be important that those facing frustoconical surfaces be as smooth as possible so as to avoid creating inconsistent resistance to air flow from one air accelerator assembly 34 to another. Accordingly, these facing frustoconical surfaces may be honed and/or polished so that the surface roughness is about 100 microinches or less, and preferably about 30 microinches of less.
As noted, the cavity of the body 50 and the frustoconical surface 82 of the adjustable member 52 cooperate to define a chamber 90 for pressurized air. That chamber 90 has fluid communication with the conduit 38, and thus the pump 40 and associated control valve 42 (see
Since it is also important that air supplied to the chamber 90 (see
In a preferred embodiment, the body 50 and the adjustable member 52 are constructed from air-hardened tool steel.
As noted above, the particulate tobacco material processed through the dosing tube assembly described above may exhibit tackiness. Accordingly, one or more of the interior surface of the funnel member 32, the cylindrical channel 80 of the adjustable member 52, and the interior of the discharge tube 36 may also be coated with polyether ether ketone (PEEK). More preferably, the adjustable member 52 may be constructed entirely from PEEK. Such a coating can improve mechanical and chemical resistance to the particulate material as that material moves through the dosing tube assembly.
It will now be understood by those skilled in the art that the tapered angle b of the adjustable member 52 (see
Conventional set screws may be provided as a locking means to fix or otherwise lock the relative positions of the member 52 and the body 50.
To prepare an air acceleration assembly 34 for use, the assembly 34 and its discharge tube 36 are removed from the tobacco feed system. Then the assembly 34 is calibrated by adjusting the throat of the variable venturi such that a predetermined force is obtained from the associated discharge tube. To that end, the assembly 34 with its discharge tube 36 is positioned in a fixture such that the end 36 at the base of the discharge tube 36 is proximately positioned relative to a suitable conventional a precision scale 112. The discharge tube 36 is held at a predetermined stand-off distance d above the surface of the precision scale 112. Preferably that predetermined stand-off distance d between the end of the discharge tube 36 and the precision scale 112 is about 1 mm.
The feed tube is connected to the source 40 of pressurized air through the conduit 38 (see
After each air acceleration assembly 34 has been calibrated and returned to the tobacco feed mechanism, the pouching machine, i.e., the form/fill/seal machine, is ready for operation. Typically, a machine operator adjusts the air regulator 42 (
At one extreme, the air pressure may be too high, in which case the tobacco is driven into the pouch with such force that the pouch tends to open or cause tobacco to enter the first lower transverse seal of the pouch being formed. In another case, the pressure may be too low such that the upper transfer seam is closed and sealing initiated before all the tobacco has fully arrived into the body portion of the pouch. For this latter condition, the operator typically increases the operating pressure. Once the filling sequence has been optimized, the operator is assured uniform filling across the bank of feed tubes, because each air acceleration assembly has been calibrated the same way.
Preferably, the operating pressure of all feed lanes (or delivery apparatuses 20) is adjustable from a single, common regulator 42. Such arrangement contributes uniform tobacco feeding characteristics across the entire bank of feed lanes to enhance machine operation and performance. The arrangement assures that downstream timing requirements are uniformly met. For example the cutting knives for severing fully formed pouches operate uniformly at a fixed rate across the entire bank of feed lanes. The feed system as taught herein, with its locking down each air delivery system to a common, uniform calibration and uniform adjustment of operating pressure from a common regulator assures that tobacco is delivered at the right time and at the right speed across the bank of feed lanes. During operations, should delivery speed of the feed lanes drift, the operator may return the entire bank of feed lanes back into desired delivery speed by observing a single feed lane while adjusting the common regulator.
In this description, the word “substantially” is used as an adjective to show that the modified term need not be used literally, but is intended to include equivalent terms which do not materially depart from the spirit and scope of the term. When the word “substantially” is used in connection with a geometric term, it is intended that the geometric term not be interpreted rigidly with respect to geometric definitions.
To similar effect, the word “about” is used in this description in connection with numerical terms to demonstrate that mathematical precision is not required and that a tolerance of ±10% around that numerical term is intended.
It will now be apparent to those skilled in the art that this specification provides a novel and unobvious improvement to a metering device for particulate material, particularly where pressurized fluid functions to assist movement of the particulate material through the apparatus. Furthermore, it will be apparent to those skilled in the art that numerous modifications, variations, substitutions, and legal equivalents exist for features of the invention described herein. Accordingly, it is expressly intended that all such modifications, variations, substitution, and legal equivalents that fall within the spirit and scope of the appended claims be embraced thereby.
This application is a continuation application of U.S. patent application Ser. No. 13/546,649, filed Jul. 11, 2012, which claims priority under 35 U.S.C. § 119(e) to U.S. Provisional Application No. 61/506,465, filed on Jul. 11, 2011, the entire content of which is incorporated herein by reference thereto.
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Number | Date | Country | |
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Parent | 13546649 | Jul 2012 | US |
Child | 15973860 | US |