Patent ID: 12251742

DESCRIPTION OF EMBODIMENTS

The coating apparatus100is a rotary batch coater for coating seed. The apparatus includes a coating chamber120including a wall arrangement121, a base123and a lid125. The wall arrangement121surrounds a space, atop the base123, for coating the seed. The space is closed by the lid125. The lid125is equipped with a funnel122for receiving seed into the seed coating chamber. Other forms of inlet are possible.

The lid125further includes a coating material inlet arrangement125c,125dand a dust extraction port125e(FIG.3A). The coating material inlet arrangement125c,125dincludes a port125c, surrounded by a bolting flange, and a simple hole125dsurrounded by bolt holes. When the apparatus100is installed as part of a coating installation, the inlets125c,125dwill typically be plumbed to suitable powder conveying conduits associated with powder dispensing apparatus, e.g. with dispensers incorporating augers responsive to load cells to deliver a defined amount of powder. Typically the port122would be connected to a suitable duct via which dust is extracted. Typically the dust-carrying air extracted from the chamber120is routed through a suitable filtering arrangement.

An interior of the wall arrangement121is substantially cylindrical. Other revolved shapes, such as substantially conical or substantially toroidal, would also be convenient. The base121is mounted to rotate about an upright rotation axis RA. Preferably an interior of the wall arrangement121is substantially concentric to the axis RA.

In operation seed and coating material are supplied to the chamber120and the base is rotated by an underlying motor140while the wall arrangement is stationary. The movement and relative movement stirs and agitates the materials to coat the seed in the coating material. The motor140may be configured to rotate the rotating base at about 230 RPM. Preferably the speed of the rotating base is adjustable, e.g. the motor140might be driven by a variable speed drive.

The apparatus100includes a cleaning assembly200for cleaning the seed coating chamber. The cleaning assembly200includes a hub220by which the assembly200is suspended from the lid125. The assembly200may be otherwise20mounted.

As best shown inFIG.3B, the lid125defines a lower portion125aand an upper portion125beach of which, in this example, takes the form of a horizontal portion of sheet material.

The cleaning assembly200includes a rotatable set of parts231and a non-rotating set of parts233. The rotating set of parts231includes sprocket221and drive hub222of the hub220. The drive hub222is upright and tubular, and includes an outwardly projecting radial flange about its lower end. The sprocket is connected to a top of the drive hub222via a connecting ring290and arrangements of keys and keyways between the components. The sprocket forms part of a chain-drive transmission by which the rotating set231is driven by a motor (not shown).

The drive hub222is mounted to rotate with a body mount hub224of the hub220. The hub224is upright and tubular, and includes an outwardly projecting radial flange about its lower end. The flange of the hub224is a bolting flange by which the hub224is fixed to the lower portion125a.

The non-rotating set233is suspended from the upper portion125b. A suspending member226is fastened to the upper portion125band extends downwardly through the hub222. Glacial bearings227are fitted between the hub222and the member226whereby the hub222laterally supports the member226.

This example of the member226is a two-part member including an inner cylindrical tube fitted with a sleeve. The portion125ahas an opening via which an interior of the tube is accessible whereby the member226constitutes a dosing tube for supplying substances to the chamber120.

As best shown inFIG.8, the base125includes a drive hub126and an outer body128carried by the drive hub126. The drive hub126upwardly presents a downwardly-divergent conical exterior. The outer body defines a horizontal floor128aand an upwardly divergent conical exterior128b.

The base123is carried by a tubular drive shaft269and an arrangement of thrust bearings. An atomising arrangement271is arranged to atomise fluid received via the member226and includes a rotor273at the top of a drive shaft275carried concentrically within the drive shaft269by bearings. In this example, the rotor273takes the form of a saucer-like disc and is positioned to sit above the loose material and rotate at speed, e.g. at 1,400 RPM, to atomise, and disperse over the loose material, the incoming liquid. The member226may internally carry several flexible liquid-introducing lines for supplying separate liquids.

The non-rotating portion233includes a base-scraping arrangement127(FIG.4B). The arrangement127includes a base-scraping member129and a mounting arrangement131. The mounting arrangement131includes the suspending member226and an actuated pivotal connection228by which the base-scraping member is mounted to be pivotally lowered from coating position to a base-scraping position.

The actuated pivotal connection includes an actuator228a, upper bracket228b, lower bracket228c, spacer228dand fluid lines228e,228f. In this example the actuator is a double acting pneumatic ram and the lines228e,228fare pneumatic lines via which the ram is actuated. Preferably the ram is configured to produce 165 kgf at 120 PSI.

The inner tube of the member226has a wall thickness within which conduits for carrying the lines228e,228fare formed. The lower ends of the lines228e,228femerge laterally from the member226and are connected to the actuator228avia flexible lines (not shown). The tops of the lines228e,228fproject upwardly beyond the upper portion125bfor connection to a pressure source.

The brackets228b,228care vertically spaced from each other along the member226. The lower bracket defines a yoke for receiving a vertical planar web243bof the base-scraping member129and via which the member129is pivotally mounted. In this case the member129is mounted to pivot about a horizontal pivot axis PA. A body of the actuator228ais pivotally connected to the upper bracket228b. A rod end of the actuator228ais pivotally connected to the base-scraping member129via the spacer228d.

The base-scraping member129is a five part construction including:main body243having holes by which the base-scraping member129is pivotally mounted and connected to the actuator;reinforcement243aabout the holes;blade244carried by the body243to scrape build-up from the body128of the base;bracket245; andblade246carried by the bracket245.

The main body243includes the vertical planar web243b(perpendicular to the pivot axis PA), a vertical planar web243cand a planar blade mounting portion243d. The vertical web243bis offset from the rotation axis RA by the bracket228c. The mounting arrangement228, and more specifically in this case the bracket228care configured to position the pivot axis PA in proximity to the rotation axis RA to enable the blade246to clean close to the centre of the hub226and then pivot upwardly away (as opposed to downwardly into) the base125for the coating operation. In this example, the pivot axis PA overlies the build-up-contacting portion CP closest the rotation axis RA. In other variants of the technology the pivot axis PA may be horizontally set back further from the build-up-contacting portions of the base-scraping arrangement127.

Whilst the bracket228coffsets the main body243from the axis RA, the bracket245offsets the blade246from the main body243to position the blade246in proximity to the rotational axis RA to clean the drive hub126.

The bracket245has a planar flange including a pair of threaded bores. The blade246is a planar piece having bolt holes via which bolts engage the threaded bores of the bracket245to mount the blade. The bolt holes of the blade246are slotted whereby the clearance CH (FIG.6) to the hub126can be adjusted. A nominal clearance within the range of 1 mm to 3.5 mm inclusive is preferred.

The web243cis inclined relative to the web243band meets that web at a vertical corner overlying the junction between the floor128aand the conical outer base portion128b. The portion243cis inclined rearwardly relative to the rotation of the base: when viewed in plan, the portion243cis also inclined relative to lines tangent to the underlying portions of the base125such that loose material carried by these underlying portions of the base ride outwardly along the portion243c. The base-scraping arrangement127is thereby shaped for build-up scraped from the base to be driven, by rotation of the base, outwardly along the base-scraping arrangement.

The blade-carrying piece243dis a planar portion shaped to curve about the lower edges of the portions243b,243c. The blade244is another planar piece and has a shape complementary to portion243d. The blade244is mounted to the portion243din a manner akin to the mounting between components245,246whereby a clearance CF (FIG.7) to the floor can be adjusted.

The actuator228is also adjustable. In this example, the rod of the ram228terminates in a rose joint co-operable with the spacer228dand includes a threaded adjustment by which the effective length of the rod is adjustable.

When the base-scraping arrangement127is lowered into its operative position the ram228ais fully extended. Through the aforedescribed adjustments, the clearances to the base125can be adjusted. When the ram228ais retracted to lift the scraping arrangement127to its coating position (as inFIG.2a) scraping arrangement127is held clear of the loose material. This reduces the build-up on the base-scraping arrangement itself. It also avoids stressing the loose material. Whilst the loose material is agitated to ensure that it is coated, excessive stress (such as that that might be caused by a lowered base-scraping arrangement) can damage certain loose materials such as seeds.

The rotating parts231form part of a wall-scraping arrangement232and includes an elongate drive arm223. A mid portion of the arm223is directly bolted to the hub222. One end of the arm223carries a wall-scraping blade229whilst the other end carries a paddle237. As best shown inFIGS.5aand5bthe blade229is an upright member adjustably connected to the arm223via a bracket239. Bracket239includes a body239ashaped to sit flat against a planar underside of the arm223. An end of the body239is bolted to the blade229. The bracket239further includes a diagonal brace239bextending downwardly from the body239aat an oblique angle to provide further support to the blade229.

The body239ahas a slotted bolt hole239cthrough which a bolt engages a threaded bore of the arm223to mount the bracket. An end of the body239aspaced from the blade229is surrounded by a trio of lugs223a. Each of the lugs223adefines a respective internally threaded horizontal bore through which a respective adjustment bolt is passed to act on the body239a. The blade239is thus screw adjustable to enable the clearance CW and the clearance angle CA to be varied. Other modes of screw adjustment, and indeed other modes of adjustment more generally, are possible. In this example a clearance of not more than 12 mm, a clearance angle in the vicinity of 8 degrees and a lip angle in the vicinity of 40 degrees are preferred.

The rotating assembly231may be held stationary whilst coating is in progress. The stationary blade229and paddle237can agitate the loose material upwardly driven against those components by the rotation of the base125. Alternatively, the rotating arrangement may be rotated whilst coating is in progress, e.g. the rotating set of parts231might be rotated in a direction opposite to a direction of rotation of the base125. This can lead to more efficient use of the coating materials in that the coating material can be scraped from a wall before it sets and subsequently adhere to the loose material. The rotating set of parts also provides additional agitation to the loose material whereby ‘dead spots’ of untreated seeds are less likely—indeed, a bladeless variant of the set of parts231would be useful. In this example, the drive and transmission are configured to turn the set of parts231at about 5 RPM.

As best shown inFIG.4Bthe cylindrical interior of the wall arrangement121is partly defined by a door241which serves to close an outlet249during the coating operation. Door241is suspended from a pivotal mounting (defining a horizontal pivot axis) and driven by an actuator251to pivot outwardly to open outlet249to enable material to pass from the chamber120into receiving space253. The receiving space253is downwardly open and shaped to funnel the material down towards a diverter255(FIG.1A). The diverter255is operable to selectively direct the material to a selected one of a first outlet257and a second outlet259. Other mechanisms for selectively directing are possible. In this case the diverter takes the form of a flap driven by an actuator261and the actuators251,261are pneumatic rams.

A control arrangement263(FIG.1A) in the form of a programmable logic controller co-ordinates the operation of the motor140, the drive motor (not shown) by which the wall-scraping arrangement232is driven, and the actuators228a,251,261. The control arrangement263is connected to each of the controlled elements via wired connections. Other control arrangements and modes of connection are possible.

The control arrangement263incorporates a user interface, e.g. push button, by which the coating apparatus100is operable. In use a defined quantity of loose material is supplied via the funnel122and coating material is supplied via the member226. Under the control of the arrangement263, the base123is rotated whilst the wall-scraping arrangement232is rotated in the opposite direction and the base-scraping arrangement is held clear of the loose material. After a period of time selected to coat the loose material, the control arrangement263automatically opens the door241. The wall-scraping arrangement232may be stopped at this point. Energised by the rotating base123, the coated loose material is ejected via the open outlet249to pass through the receiving space253, diverter255and outlet259to a destination such as a vessel or a conveyor belt.

After a period of time sufficient for substantially all of the coated loose material to leave the chamber120the control arrangement263may close the door241and deactivate the motor140to await further user and material input.

Preferably the control arrangement263is configured to periodically clean the base123, e.g. to clean the base after a defined number of coating cycles. By way of example, once substantially all of a batch of coated loose material has left the chamber120, but whilst the door241remains open, the base-scraping arrangement127may be lowered to its scraping position whereat it remains stationary whilst the build-up carried by the rotating base123is driven against it. The build-up on the base123is thus scraped off. As previously described, the base-scraping arrangement is shaped to outwardly drive the build-up scraped from the base. It also sits in register with the outlet249to assist with the ejection of the waste material via the outlet.

The control arrangement263is configured to end this base-scraping mode after a predetermined period of time by elevating the base-scraping arrangement127and deactivating the motor140before entering the standby mode. Preferably the period is not more than 15 seconds. The inventors have found this is more than adequate to clean the base123and that the cleaning assembly200can increase the output of the coating apparatus by as much as 50%.

The control arrangement263is configured to switch the diverter255substantially simultaneously with the lowering of the base-scraping arrangement127whereby the waste material is directed through the outlet257.

Whilst an example of the invention is illustrated, variants of the described outlet249, diverter255and/or the aforedescribed operating sequence may be usefully applied in other contexts, e.g. in the context of a coating apparatus fitted with an entirely different cleaning apparatus.

The present inventors have recognised that the wear between adjacent portions of the rotating base125and the stationary wall arrangement121contributes to the cost of operating the coating apparatus. Turning toFIGS.8and9, preferred variants of the apparatus100incorporate a replaceable wear arrangement265to minimise these costs.

The wall arrangement121incorporates a stationary rotor base267. The base267has a heavy steel construction and defines a short cylindrical wall surrounding the rotatable base125.

An interior of the cylindrical wall of the stationary base267is stepped to define an annular ledge267aand an inwardly directed cylindrical267b. An exterior of the base123, or more specifically the body128in this case, has a complementary step defining an annular ledge128aand an outwardly directed cylindrical surface128b.

In this example of the apparatus100, the replaceable wear arrangement takes the form of an integrally formed ring having a substantially rectangular profile.

A square is an example of a rectangle as the word ‘rectangle’, and similar wording, is used herein. As the wording is used herein ‘integral formation’ refers to a single continuous body of material—two bodies may be integrated by welding but not by conventional mechanical fastening.

In this case the arrangement265is formed of steel and has a cross section in the vicinity of 10 mm to 12 mm by about 20 mm. Relative to the more substantial stationary base267the arrangement265is flexible. An exterior of the arrangement265is dimensioned to fit within the cylindrical surface267band the arrangement265is held in place by an array of radially oriented bolts passing through counter-bored through holes267cand engaging threaded bores265a. The stationary base267thus constitutes a support structure for supporting the arrangement265.

An interior265bof the arrangement265is a cylindrical surface sitting in opposition to the cylindrical surface128b. These opposing surfaces co-operate to impede the escape of material from the chamber120. Thus the interior265bconstitutes an operative portion of the arrangement265.

Whilst the arrangement265is relatively flexible, it is supported by the stationary base267to hold its operative portion265bconcentric to the rotation axis RA whereby a small peripheral clearance PC (between the surfaces128b,265b) become practical. A nominal clearance in the vicinity of 0.8 mm is preferred albeit that with typical circularity tolerances, and other practical variations, some rubbing occurs. This narrow gap impedes the loss of seed from the chamber120.

The body128, or more relevantly the portion128bthat might rub against the operative portion265b, is formed of a material harder than the wear arrangement265whereby for the most part the arrangement265rather than the body128wears away as a result of this rubbing. In this case the body128is hard chromed. The arrangement265can be periodically replaced. By the adoption of the arrangement265, the service life of the larger components128,267is extended. This is cost efficient.

In other variants of the apparatus100, the arrangement265might take other forms, e.g. instead of a single integrally formed ring, multiple arcuate segments might be placed end to end. Other mounting arrangements and material specifications are possible. Whilst in this example, the stationary base267carries the arrangement265, in other variants the rotor123may carry the arrangement265. Indeed, in yet another variant each of the rotor and the wall arrangement might carry a respective replaceable element.

Various examples of technology have been described. The invention is not limited to these examples. Rather, the invention is defined by the claims. By way of example, whilst the apparatus100includes a rotatable base123, variants of the rotating set of parts may be applied to coating apparatus having no such base.