Rotary dispensing tank

A dispensing system for a rotary dispensing machine includes a tank, a fill tube, and a piston that moves along the fill tube and defines an air chamber and a fluid chamber within the tank. The tank is rotatable relative to the fill tube. A fluid is dispensed from the fluid chamber of the tank through at least one outlet formed in the tank.

FIELD OF THE INVENTION

The present invention relates to a dispensing system for a rotary dispensing machine.

BACKGROUND OF THE INVENTION

It is common in can assembly operations to dispense a sealant material into an annular groove of a can lid for attachment of the lid to the open end of a can body. Typically, this is done through the use of a rotary can end lining machine where the can lids are advanced in rapid succession onto continuously rotating chuck(s).

SUMMARY OF THE INVENTION

In accordance with an aspect of the invention, a dispensing system for a rotary dispensing machine is provided where the dispensing system has a table rotatable about a central axis of rotation. A tank is mounted to the table and includes at least one fluid outlet port for supplying a fluid from the tank. A fill tube extends through an upper end of the tank where the tank is rotatable relative to the fill tube. A piston is provided within the tank and movable along the fill tube. The piston defines an air chamber in an upper portion on the tank and a fluid chamber in a lower portion of the tank.

The dispensing system may further comprise at least one seal supported on the piston for engagement with an inner surface of a sidewall of the tank.

The at least one seal may be a resilient self-energizing seal.

The dispensing system may further comprise a labyrinth seal system extending around the piston comprising upper and lower circumferential self-energizing seals formed of a resilient material for engagement with the inner surface of the sidewall, and a guide band located on the piston between the upper and lower self-energizing circumferential seals.

The dispensing system may further comprise at least one seal supported on the piston for engagement with an outer surface of the fill tube.

The at least one seal may be a resilient self-energizing seal.

The dispensing system may further comprise a labyrinth seal system comprising upper and lower inner self-energizing seals located in respective grooves formed in the piston and formed of a resilient material for engagement with the outer surface of the fill tube, and a guide band located between the upper and lower self-energizing inner seals.

The fill tube may be non-rotatably supported and the piston may be rotatable relative to the fill tube.

The dispensing system may further comprise a sensor structure for detecting a position of the piston within the tank.

In accordance with another aspect of the invention, a dispensing system for a rotary dispensing machine is provided where the dispensing system has a table rotatable about a central axis of rotation. A rotatable tank is mounted to the table and has an upper end, a lower end, and a sidewall extending between the upper and lower ends. A fill tube extends through the upper end of the tank and has an upper end located outside of the tank and a lower end located within the tank. A piston is located within the tank where the fill tube extends through the piston and the piston being movable relative to the fill tube and the tank. One or more outlet ports are formed in the tank for dispensing a flowable material from an area defined between the piston and the lower end of the tank.

The dispensing system may further comprise a non-rotatable housing located above the upper end of the tank for supporting the fill tube, the housing including an air supply port for supplying air to an area defined between the piston and the upper end of the tank.

The dispensing system may further comprise a bearing positioned within the housing and around the fill tube, and an air passage defined between the fill tube and the housing for receiving air from the air supply port.

The dispensing system may further comprise a seal defined between an outer surface of the fill tube and the housing.

The dispensing system may further comprise an outer seal structure supported on an outer circumference of the piston, the outer seal structure having a normal position out of sealing engagement with an inner surface of the tank sidewall and having a pressure actuated self-energizing position in sealing engagement with the inner surface of the tank sidewall.

The outer seal structure may comprise an upper self-energizing circumferential seal located near an upper end of the piston and a lower self-energizing circumferential seal located near a lower end of the piston.

The upper and lower self-energizing circumferential seals may comprise cup seals actuated by pressure above and below the piston biasing the circumferential seals into sealing engagement with the inner surface of the tank sidewall.

The dispensing system may further comprise a guide band located on the outer circumference of the piston between the upper and lower self-energizing circumferential seals, the guide band having an outer surface in sealing relationship adjacent to the inner surface of the tank sidewall to form a labyrinth seal system with the upper and lower circumferential seals.

The guide band may comprise a magnetic material, and the dispensing system may further comprise at least one sensor located external to the tank for sensing the magnetic material in the guide band to determine a vertical position of the piston.

The dispensing system may further comprise a fluid level sensor supported with the tank for detecting a position of the piston within the tank, wherein the fluid level sensor comprises at least one of an optical sensor or a magnetic sensor.

The dispensing system may further comprise an inner seal structure located in a circumferential groove formed in the piston, the inner seal structure having a normal position out of sealing engagement with an outer surface of the fill tube and having a resilient self-energizing pressure actuated position in sealing engagement with the outer surface of the fill tube.

DETAILED DESCRIPTION OF THE INVENTION

The following text sets forth a broad description of one or more embodiments of the present disclosure. The description is to be construed as exemplary only and does not describe every possible embodiment since describing every possible embodiment would be impractical, if not impossible, and it will be understood that any feature, characteristic, component, composition, ingredient, product, step or methodology described herein may be deleted, combined with or substituted for, in whole or part, any other feature, characteristic, component, composition, ingredient, product, step or methodology described herein. It should be understood that multiple combinations of the embodiments described and shown are contemplated and that a particular focus on one embodiment does not preclude its inclusion in a combination of other described embodiments. Numerous alternative embodiments could also be implemented, using either current technology or technology developed after the filing date of this patent, which would still fall within the scope of the claims.

Referring toFIG.1, a dispensing system10according to an embodiment is shown. The dispensing system10includes a supply tank100that is supported for rotation with a chuck table T. A lower end1000aof the supply tank100includes a plurality of fluid outlet ports102for supplying a flowable material comprising a fluid compound, e.g., a sealant, to a plurality of spray devices SD, as will be discussed below. The dispensing system10further includes a fill tube104that extends down into the supply tank100in a longitudinal direction DLongof the dispensing system10. The fill tube104has a lower end104alocated within the supply tank100and an upper end104blocated outside the supply tank100. The fluid compound, received from a fluid source FS, is supplied to the upper end104bof the fill tube104. The fluid compound then exits at the lower end104aof the fill tube104into a lower fluid chamber100alocated within a lower portion of the supply tank100. The fill tube104supports a piston106inside the supply tank100, wherein the supply tank100and the piston106are rotatable about a central axis of rotation A of the dispensing system10. The piston106is movable in the longitudinal direction DLongalong the fill tube104and divides the interior of the supply tank100into the lower fluid chamber100abelow the piston106and an upper air chamber100babove the piston106.

Referring toFIG.2, an outer surface106aof the piston106includes upper and lower outer circumferential grooves107a1,107a2, which grooves107a1,107a2receive respective circumferential upper and lower outer seals108,110for sealing a gap between the outer surface106aof the piston106and an inner surface100cof a sidewall109of the supply tank100. An inner surface106bof the piston106includes upper and lower inner circumferential grooves107b1,107b2, which grooves107b1,107b2receive respective circumferential upper and lower inner seals114,116for sealing a gap between the inner surface106bof the piston106and an outer surface104cof the fill tube104.

According to one exemplary embodiment, the seals108,110,114,116may be resilient self-energizing seals, such as, for example, outward facing cup seals, and may be formed from a thermoplastic polymer, such as, for example, polyether ether ketone. As described in further detail below, the outer seals108,110are normally out of contact with the sidewall109of the supply tank100, and the inner seals114,116are normally out of contact with the outer surface104cof the fill tube104.FIG.2shows the seals108,110,114,116in dashed lines in an energized position.

The piston106also includes outer and inner circumferential guide bands118a,118bthat are respectively positioned between the upper and lower seals108,110,114,116, wherein the outer guide band118ais positioned in an outer groove107con the outer surface106aof the piston106and the inner guide band118bis positioned in an inner grove107don the inner surface106bof the piston106. The guide bands118a,118bmay be formed from a polymer and at least the outer guide band118amay comprise a magnetic material, such as, for example, metallic flakes embedded therein. The guide bands118a,118bcreate very thin air gaps between the guide bands118a,118band the inner surface100cof the supply tank sidewall109and the outer surface104cof the fill tube104, respectively. The guide bands118a,118bthus provide additional seals between the lower fluid chamber100aand the upper air chamber100b. The guide bands118a,118bpreferably have a height of at least 0.5″ such that the air gaps are sufficiently long enough to maximize sealing between the lower fluid chamber100aand the upper air chamber100b. According to one aspect, the inner and outer guide bands118a,118bmay each have a unique minimum height, with the outer guide band118ahaving a greater height than the inner guide band118bsince the diameter of the outer guide band118ais greater than the diameter of the inner guide band118b. For example, in one exemplary embodiment, the outer guide band118amay have a height of at least about 1″, and the inner guide band118bmay have a height of at least about 0.5″. The minimum heights of the inner and outer guide bands118a,118bmay be proportional to their diameters. As described in further detail below, when the seals108,110,114,116are engaged with the inner surface100cof the supply tank sidewall109and the outer surface104cof the fill tube104, the combination of the seals108,110,114,116and the guide bands118a,118bcreates a labyrinth sealing system.

With reference now toFIG.3, the dispensing system10includes a non-rotatable housing101located above an upper end1000bof the supply tank100. The housing101supports the fill tube104and is stationary along with the fill tube104relative to the rotatable supply tank100. As shown inFIG.3, the housing101includes an air supply port112that provides air from an air source AS (seeFIG.1) to the upper air chamber100bof the supply tank100, as described in further detail below. The air source AS may comprise a self-relieving regulator to control the air pressure in the upper air chamber100b. An air passage113is defined between the housing101and the fill tube104. The air passage113connects the air supply port112to the upper air chamber100bfor supplying air to the upper air chamber100b.

The dispensing system10further comprises a rotary union including a bearing103that is positioned around the fill tube104within the stationary housing101. The bearing103allows the supply tank100to rotate relative to the fill tube104. A seal105is located between the housing101and the upper end1000bof the supply tank100for sealing the upper air chamber100b.

Referring again toFIG.1, the dispensing system10may include sensor structure120to monitor the position of the piston106. According to one exemplary embodiment,FIG.4illustrates the sensor structure in the form of a fiber optic sensing device120a. The fiber optic sensing device120ais positioned on an outer surface100dof the supply tank sidewall109and includes a sensing end121that is located within a slot100eof the supply tank100. As described in detail below, the fiber optic sensing device120ais able to provide a continuous monitoring of the position of the piston106within the supply tank100.

According to another exemplary embodiment,FIG.5illustrates the sensor structure in the form of a set of magnetic field sensors120b. Each magnetic field sensor120bmay be mounted on the outer surface100dof the supply tank sidewall109. As described in detail below, the magnetic field sensors120beach provide discrete monitoring of a fixed point within the supply tank100. Contemplated measurement locations for the magnetic field sensors120bshown inFIG.5include a low fluid level location LL, a high fluid level location LH, and an overflow fluid level location LO. Additional or fewer sensors120bmay be used as desired. One or more of the magnetic field sensors120bmay determine the vertical position of the piston106by sensing the outer guide band118a, as will be discussed below.

In accordance with an embodiment, both types of sensors120a,120bmay transmit data wirelessly. Alternatively, wires of the sensors120a,120bmay terminate in a junction box, such as a ROTOCON Model MX-6 rotary contact manufactured by Meridian Laboratory (not shown) that may be located, for example, beneath the supply tank100. With reference toFIG.6, in one exemplary embodiment, the sensor(s)120may be powered by a 24 VDC power supply610.

During operation of the dispensing system10, the fluid compound is supplied from the fluid source FS to the lower fluid chamber100aof the supply tank100through the fill tube104. As the fluid chamber100afills with the fluid compound, i.e., as the volume of the fluid compound in the fluid chamber100aincreases, the piston106moves upwardly along the fill tube104in the longitudinal direction DLong. As the piston106moves along the fill tube104, the guide bands118a,118bhelp stabilize the piston106within the supply tank100.

If equipped in the dispensing system10, the sensor(s)120determine the location of the piston106in the supply tank100, wherein the position of the piston106may be used to control the dispersal of fluid compound from the dispensing system10as will be described in more detail below.

In the embodiment including the fiber optic sensor120a, the fiber optic sensor120amay continuously monitor the location of the piston106by monitoring the distance between the sensing end121of the fiber optic sensor120aand a top portion106cof the piston106. For example, the sensing end121may transmit light that is reflected off the top portion106cof the piston106back to the sensing end121, wherein the fiber optic sensing device120adetermines the position of the piston106based on the time of flight of the light. Thus, the fiber optic sensing device120ais able to provide a continuous monitoring of the position of the piston106within the supply tank100. Because the fiber optic sensing device is able to provide continuous monitoring, only one fiber optic sensing device120awould be required to monitor the position of the piston106.

In the embodiment including the plurality of magnetic field sensors120b, each sensor120bis able to detect a magnetic field given off by the outer guide band118awhen the piston106is near that specific sensor120b. Since each magnetic field sensors120bmeasures the position of the piston106at the specific position where the sensor120bis located, multiple magnetic field sensors120bmay be used to monitor the movement of the piston106between various locations. The sensors120bmay be placed at specific locations on the outer surface100dof the supply tank100that correspond to different fluid levels, for example, wherein the fluid is at a low level corresponding to the low fluid level location LL, a high level corresponding to the high fluid level location LH, or an overflow level corresponding to the overflow fluid level location LO.

As the fluid is introduced into the supply tank100and the fluid pressure builds in the lower fluid chamber100a, the lower outer and inner seals110,116are respectively energized into sealing contact with the inner surface100cof the supply tank sidewall109and the fill tube104, thus creating seals to militate against fluid escaping from the lower fluid chamber100aat these locations.

Similarly, as air is supplied to the upper air chamber100bof the supply tank100from the air source AS through the air supply port112and the air passage113, the air pressure builds in the upper air chamber100b, causing the upper outer and inner seals114,116to respectively energize into sealing contact with the inner surface100cof the supply tank sidewall109and the fill tube104, thus creating seals to militate against air escaping from the upper air chamber100bat these locations.

In combination with the upper and lower seals108,110,114,116, the air gaps created by the guide bands118a,118bform a labyrinth seal system between the lower fluid chamber100aand the upper air chamber100b. Even while the upper and lower seals108,110,114,116are not energized into contact with the inner surface100cof the supply tank sidewall109and the fill tube104(e.g., when the pressures in the lower fluid chamber100aand the upper air chamber100bare below seal-energizing levels, which is defined as the pressure level at which the seals108,110,114,116are not energized into contact with the respective inner surface100cof the supply tank sidewall109and the fill tube104), this labyrinth seal system militates against the leakage of fluid and air between the lower fluid chamber100aand the upper air chamber100b, as described in more detail below.

As the supply tank100rotates about the central axis of rotation A of the dispensing system10, the engagement of the energized outer seals108,110with the inner surface100cof the supply tank sidewall109causes the piston106to rotate about the central axis of rotation A, i.e., the piston is rotationally carried by the rotating supply tank100. The rotation of the piston106with the supply tank100reduces wear on the outer seals108,110due to a reduction in friction, as compared to a situation where one of the supply tank100or the piston106rotates relative to the other. This reduction in friction and associated heat is believed to increase the useable life of the seals108,110.

The fluid compound is distributed from the outlet ports102of the supply tank100to the plurality of spray devices SD, where the fluid may be sprayed onto cans that are provided onto continuously rotating chuck(s) RC (SeeFIG.6) underneath the supply tank100. The reduction in volume of the fluid compound in the lower fluid chamber100acauses the piston106to move downwardly along the fill tube104in the longitudinal direction DLong. As noted above, the location of the piston106may be monitored using the sensor(s)120, wherein the location of the piston106may be used to determine when additional fluid compound needs to be supplied from the fluid source FS to maintain fluid pressure in the lower fluid chamber100a. Additionally, as the piston106moves along the fill tube104, the pressure in the upper air chamber100bchanges, i.e., as the piston106moves up, the area of the upper air chamber100bdecreases, which increases pressure in the upper air chamber100b, and as the piston106moves down, the area of the upper air chamber100bincreases, which decreases pressure in the upper air chamber100b. The self-relieving regulator is operated to introduce air into the upper air chamber100bas the pressure becomes too low, and also expels air from the upper air chamber100bif the pressure becomes too high. Maintaining the pressure within the upper air chamber100bcontrols the distribution of compound fluid out of the outlet ports102. This precise control of the discharge of the fluid compound from the dispensing system10decreases waste and operating costs.

Referring toFIG.6, an exemplary embodiment of a rotary dispensing machine600, which includes the dispensing system10disclosed herein, is shown. As discussed above, the dispensing system10is positioned on a chuck table T to support rotation of the supply tank100. Air and fluid compound are supplied to the dispensing system10respectively from an air source AS and a fluid source FS to maintain pressure within the chamber100. A pressure gauge602is provided in an air supply line603extending from the air source AS to the dispensing system10. The pressure gauge602measures the air pressure in the upper air chamber100b.

The fluid compound is supplied to the supply tank100from a fluid source FS via a fluid supply line605. As shown inFIG.6, the fluid compound exits the fluid source FS and then passes through a compound filter604, which removes contaminants from the compound fluid. The compound fluid is then fed to a valve606, which controls the supply of the compound fluid to the lower fluid chamber100a. According to the exemplary embodiment shown, the sensor120measures the height of the piston and sends an analog signal to a liner logic control608. The liner logic control608converts the analog signal to a digital output that controls the valve606, e.g., when the sensor120detects that the piston106is at or near the high fluid level location LH, the liner logic control608turns the valve606off to stop the supply of the compound fluid to the lower fluid chamber100a, and when the sensor120detects that the piston106is at or near the low fluid level location LL, the liner logic control608turns the valve606on to supply the compound fluid to the lower fluid chamber100a. This control of the air pressure and compound fluid level regulates the amount of compound fluid sprayed through the plurality of spray devices SD onto cans that are provided onto continuously rotating chuck(s) RC from at least one can source CS.

The presently disclosed dispensing system10offers multiple means to improve the can assembly process. For example, the division of the supply tank100into the lower fluid chamber100aand the upper air chamber100bmilitates against contamination of the pressurized air with the fluid compound and thus avoids the drying or curing of the fluid compound. This isolation of the pressurized air source from the fluid compound reduces the required maintenance of the dispensing system.

Additionally, the disclosed dispensing system10isolates the electrical sensor(s)120from the fluid compound. This isolation of the sensor(s)120prevents the fluid compound from drying or curing on the sensors and therefore reduces the required maintenance of the dispensing system.

Finally, the disclosed dispensing system10is suitable for use of corrosive abrasive electrically-conductive water based sealant compounds and non-corrosive, non-abrasive solvent based compounds.

The description of the present disclosure has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited only to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention.