Device for gel-coating seeds

A device for gel-coating seeds includes: a plurality of nozzles into each of which a gelling agent is filled and a seed is charged and held in the gelling agent to form a gel-coated seed; a pair of upper and lower nozzle casings joined with each other through a joint surface; galleries for the gelling agent formed on the junction surface; and passages formed in the lower nozzle casing which extend from the respective galleries to the respective gel-filled portions of the nozzles below the galleries. The nozzles vertically penetrate the upper and lower nozzle casings which may be comprised of a bottom plate and nozzle sleeves. The joint surface is arranged higher than a gel-filled portion of each nozzle.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for gel-coating seeds and more particularly to a device which continuously and simultaneously coats a plurality of seeds with a gelling agent, wherein the device is applicable to a whole size of seeds.

2. Description of the Related Art

Conventionally, there is a well-known device for coating seeds with a gelling agent mixed with nutriment, medicament or the like, which has a plurality of nozzles into which respective seeds are dropped and the gelling agent is filled. The process of gel-coating a seed in each of the nozzles is performed as follows:

First of all, a little amount of gelling agent is discharged into the nozzle so as to form a gel-membrane blocking in a bottom tip of the nozzle. Next, a seed is dropped into the nozzle so as to be caught with the gel-membrane. Then, the gelling agent is more filled into the nozzle so as to thicken the gel-membrane, thereby gel-coating the seed. This gel-coated seed falls from the bottom tip of the nozzle with its empty weight.

Incidentally, the gel-coated seeds from the nozzles fall into hardener solution. The gel-coated seeds are conveyed in the hardener while their gel-coats are hardened. Then, the gel-coated seeds are carried into a rinsing unit such that the hardener stuck on the gel-coated seeds is rinsed out. Thus, the gel-coated seeds are finished to be products.

The nozzle unit of the conventional device for gel-coating seeds as mentioned above has a drawback such that each nozzle is supplied into its bottom tip with a gelling agent, which is substantially horizontally discharged from a longitudinal or lateral side of the nozzle. If the pressure for discharging the gelling agent is insufficient, it may happen that the gel-membranes, i.e., the gel-coated seeds cannot be formed.

Besides, the gel-coated seeds fall from the bottom tips of the nozzles with their empty weight. If the seeds are very small, it may happen that the seeds do not acceptably fall from the nozzles.

SUMMARY OF THE INVENTION

The present invention is a device for gel-coating seeds having a nozzle into which a gelling agent is filled and a seed is charged and held in the gelling agent to form a gel-coated seed which is then allowed to fall. The nozzle vertically penetrates a nozzle casing which is divisible up and down. A joint surface through which the upper and lower parts of the nozzle casing are joined together is disposed higher than a gel-filled portion of the nozzle. A gallery for the gelling agent is formed on the joint surface. The lower part of the nozzle casing is formed therein with a passage from the gallery to be connected to the gel-filled portion below the gallery. Due to such a structure, the gelling agent is charged downward into the gel-filled portion of the nozzle. Therefore, the pressure for discharging the gelling agent is increased to surely form a gel-membrane for receiving the seed.

The gallery for the gelling agent may be compactly formed into a groove which is circular centering a horizontal section of the nozzle, when viewed in plan, thereby enabling the gelling agent to be sufficiently stored around the nozzle.

The passage from the gallery to the gel-filled portion of the nozzle may comprise a pair of paths arranged in opposite to each other with respect to an axis of the nozzle to communicate to the gel-filled portion. More than one of the pair of paths may be disposed at regular intervals. Therefore, the gelling agent is evenly dispersed and filled into the gel-filled portion of the nozzle from all the paths, thereby forming an even gel-membrane.

Preferably, a device for gel-coating seeds according to the present invention is provided with a plurality of nozzles in each of which a gelling agent is filled and a seed is charged and held in the gelling agent so as to from a gel-coated seed which is then allowed to fall. Each of the nozzles vertically penetrates a pair of upper and lower nozzle casings joined with each other through a joint surface arranged higher than a gel-filled of the nozzle. A gallery of the gelling agent is formed on the joint surface for each of the nozzles. In an embodiment, the lower nozzle casing may be comprised of a bottom plate and nozzle sleeves mounted thereon. The nozzle sleeves are provided for the respective nozzles. Each of the passages is formed in the lower nozzle casing with a passage extended from the gallery to the gel-filled portion below the gallery.

Due to such a structure, the gelling agent is charged downward into the gel-filled portion of each of the nozzles. Therefore, in each of the nozzles, the pressure for discharging the gelling agent is increased to surely form a gel-membrane for receiving a seed. Further, the device for gel-coating seeds is available for coating a large amount of seeds or other particles in one operation, wherein various kinds or sizes of particles are applicable. In a case where the lower nozzle casing is comprised of a bottom plate and nozzle sleeves, if a passage of one of the nozzles is blocked or has any other troubles, what is required is to detach-and-attach or change only the nozzle sleeve corresponding to the troubling nozzle because the nozzle sleeves are independently and individually replaceable and detachable not only from the upper nozzle casing but also from the bottom plate of the lower nozzle casing. Consequently, the device for gel-coating seeds facilitates detaching-and-attaching work of the lower nozzle casing and contributes to lowering costs.

Further preferably, each of the nozzle sleeves may be constituted by a plurality of parts detachably attached to each other. Therefore, any of the parts may be changed so as to facilitate maintenance of each of the nozzles.

Furthermore, a nozzle intermediate portion is formed into an open/close portion that can be switched between opening and blocking states. Compressed air can be charged into a portion of the nozzle between the open/close portion and the gel-filled portion. The air is charged synchronously with the blocking state of the open/close portion. Therefore, this air pressure surely makes the gel-coated seeds, even if they are granular and light, fall from the nozzle.

Incidentally, the open/close portion of the nozzle may be constituted by reciprocally inserting an open/close member, in which a part of said nozzle is formed, into the nozzle casing forming the nozzle. In the same nozzle casing, an air chamber is formed so as to communicate with a portion of the nozzle between the open/close portion and the gel-filled portion. A piston interlocking with the open/close member is reciprocally inserted into the air chamber so as to pressure-charge air into the nozzle. Therefore, the above-mentioned structure wherein gel-coated seeds are dropped by air-pressure can be obtained.

Furthermore, if there are disposed a plurality of the nozzles, a means for integrally reciprocating all the open/closing members and the pistons provided to the respective nozzles may be provided so as to exert the effort of the compressed air to all the nozzles simultaneously.

Further aspects, features and advantages of this invention will become apparent from the detailed description of the preferred embodiments which follow.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Detailed description will be given on the present invention in accordance with the accompanied drawings.

First of all, an entire structure of a device for gel-coating seeds of the present invention will be described in accordance withFIGS. 1to3. The device for gel-coating seeds comprises a seed charging unit1, a processing unit2, a hardening unit3and a rinsing unit4, which are all supported by a base frame10. Base frame10can be easily carried because it is provided at its lower portion with casters12. Seed charging unit1comprises a hopper13, absorption tips16, a carrier17for moving absorption tips16, and so on. Processing unit2is disposed at the upper middle portion of base frame10. Processing unit2receives seeds from seed charging unit1and coats them with a gelling agent so as to form a predetermined size of gel-coated seeds which are then allowed to fall.

Hardening unit3comprises a tank19extended rightward from the lower portion of processing unit2on base frame10. Hardener is filled in tank19. Tank19is formed at its right end in opposite to processing unit2with a dropping outlet20. A conveyor belt21is disposed above tank19. Paddles22are provided at regular intervals on the outer surface of conveyor belt21so as to project perpendicularly to the conveying direction of conveyor belt21. Conveyor belt21is driven with a motor26.

Due to this structure, the unhardened gel-coated seeds dropped from processing unit2fall into tank19and are brought into contact with the hardener. Conveyor belt21is rotated such that paddles22push the gel-coated seeds in tank19. Finally, the gel-coated seeds reach dropping outlet20and fall therefrom to rinsing unit4. For adjusting the time for this hardening process, the rotary speed of motor26is controlled so as to adjust the speed of conveyor belt21, thereby adjusting the degree of hardness of the gel-coats of seeds.

Rinsing unit4is disposed at an approximately middle portion in base frame10. Rinsing unit4is extended leftward from the lower portion of dropping outlet20and formed at its left end with a final outlet23. A product container24is located below final outlet23. Rinsing unit4is structured similarly with hardening unit3such that paddles28provided on a conveyor belt29which is driven with a motor27convey the gel-coated seeds so as to drop them into product container24.

In this structure, rinsing water is filled in a tank25. The gel-coated seeds, which have been hardened to the predetermined degree, are dropped from dropping outlet20via a guide member30into the right end of rinsing tank25and sunk in the water. Motor27is rotated to convey the gel-coated seeds to outlet23. During this conveying, the hardener is rinsed out of the gel-coated seeds, thereby stopping further hardening of the gel-coats of the seeds. Then, the gel-coated seeds are dropped from final outlet23into product container24.

Next, processing unit2will be detailed in accordance withFIGS. 1 and 4to6. As shown inFIG. 1, attachment plates51are erected respectively at front and rear ends on the approximately lateral middle portion of base frame10. A base plate53is longitudinally laid between the top ends of attachment plates51. As shown inFIGS. 4to6, on base plate53is fixed a longitudinally elongated valve casing54. In front of valve casing54is disposed a valve cylinder55, from which a piston rod55aprojects rearward toward valve casing55a. At the right side of valve casing54are disposed a plurality of parallel discharging cylinders56, from which respective piston rods56aproject toward valve casing54. An air cylinder, an electromagnetic solenoid, a hydraulic cylinder or the like is adaptable to valve cylinder55and discharging cylinders56. At the left side of valve casing54is fixedly provided a nozzle block58formed with a plurality of vertical nozzles98which are aligned longitudinally. Hence, processing unit2is provided with (in this embodiment, eight) discharging cylinders56, nozzles98and the like which are respectively as many as absorption tips16, thereby enabling gel-coating plural seeds simultaneously.

A first valve61and a second valve62which are formed into rods slidably penetrate valve casing54in the longitudinal direction. A horizontal plate serving as a shutter63is disposed below nozzle block58. First valve61, second valve62and shutter63are fixed at their front ends to a connection member64fixed to piston rod55aof valve cylinder55. Accordingly, piston rod55aof valve cylinder55is actuated to move first valve61, second valve62and shutter63together in the longitudinal direction, thereby simultaneously performing a later-discussed open-and-close operation of plural valve holes61aand62aand holes63aof shutter63.

A gel charge casing57is hung down from the underside of base plate53so as to be extended longitudinally along valve casing54above base plate53. Gel charge casing57is longitudinally bored with a gel charge hole57a. The rear end of gel charge hole57ais brought into communication with a gelling (coating) agent tank (not shown) through a hose or the like. Gel charge casing57is further provided with a plurality of gel distribution holes57b, which are extended upward from gel charge hole57aand upwardly open. Base plate53is bored with a plurality of vertical through-holes in connection with respective gel distribution holes57b.

As shown inFIGS. 6,7and others, valve casing54is bored with a plurality of first gel passages54awhich are vertically extended and downwardly open and which are aligned in the longitudinal direction. The lower open ends of first gel passages54aare brought into communication with respective gel distribution holes57bvia the through-holes in base plate53. Valve casing54is laterally bored through with second gel passages54baligned in the longitudinal direction. The top end of each first gel passage54ais joined to a halfway portion of each second gel passage54b. The left open ends of second gel passages54bcommunicate with respective nozzles98of nozzle block58, as discussed later. Valve casing54is formed with diametrically larger plunger chambers54c, each of which is disposed at the right side of each second gel passage54band open toward piston rod56aof each discharging cylinder56.

First valve61is disposed so as to intersect all first gel passages54aat their halfway portions. Second valve62is disposed at the left side of the junctions of all second gel passages54bto first gel passages54a(toward nozzles98) so as to intersect all second gel passages54bat their halfway portions. First valve61is vertically and diametrically bored through with valve holes61ain correspondence to respective first gel passages54a. Second valve62is laterally and diametrically bored through with valve holes62ain correspondence to respective second gel passages54b. As shown inFIG. 4, shutter63is formed vertically through with holes63ain correspondence to respective drop holes98bof nozzles98.

First and second valves61aand62aand shutter63are located in the longitudinal direction so that, at the same time when valve holes62acommunicate with respective second gel passages54b, holes63acommunicate with respective drop holes98aand valve holes61aare offset at their one pitches from their opening positions so as to block first gel passages54a. Then, first and second valves61aand62aand shutter63are connected together with connection member64. This state of first and second valves61aand62aand shutter63is established by locating piston rod55aof valve cylinder55at a first actuating position. When valve holes61acommunicate with respective first gel passages54a, valve holes62aand holes63aare offset at their one pitches from their opening positions so as to block second gel passages54band shut drop holes98b. This state is established by locating piston rod55aof valve cylinder55at a second actuating position.

As shown inFIG. 6, each plunger chamber54cis formed at its right portion (its open side portion) into female screw. A cylindrical adjusting screw66whose outer end (right end) is formed into a flange is inserted into plunger chamber54cwhile adjusting screw66engages at its periphery with the female screw. A plunger body65a, which is diametrically larger than second gel passage62b, is axially oriented in the lateral direction and disposed in plunger chamber54cso as to be freely inserted in adjusting screw66. In plunger chamber54cis interposed a compressed spring59around plunger body65abetween the inward (left) end of plunger chamber54cand the inward (left) end of adjusting screw66. Compressed spring59is used as a cushion for a later-discussed stopper67when stopper67comes to abut against adjusting screw66.

A plunger65whose diameter is approximately as large as that of second gel passage54bprojects coaxially from each plunger body65aso as to be slidably inserted into each second gel passage54b. Also, a thread rod65bprojects coaxially rightward (outward) from each plunger body65a. Stopper67is screwed around each thread rod65bto be allowed to abut against the outer end flange of adjusting screw66. At the outside of stopper67, each thread rod65bis screwed into a female screw formed in a tip of each discharging cylinder56. Therefore, plunger body65a, plunger65and stopper67are actuated integrally with the actuation of each piston rod56a. The position of piston rod56aat the time when stopper67abuts against the flange of adjusting screw66is defined as the maximum extensive position thereof, which is adjusted by rotating adjusting screw66so as to adjust the position of its flange in the axial direction of adjusting screw66. Therefore, the stroke of plunger65, i.e., the position of the tip of plunger65at its maximum stroke is adjusted, thereby enabling adjusting the discharge amount of the gelling agent. Incidentally, the tip of plunger65, even when adjusted at its leftward limit position (toward nozzle block58), is located in each second gel passage54brightward (toward discharging piston56) from the junction of second gel passage54bwith first gel passage54a.

Discharging cylinders56are structured so that their piston rods56aare extended at several steps. In this embodiment, as shown inFIG. 6, each discharging cylinder56is constituted by a first cylinder56band a second cylinder56cconnected with each other in series, thereby establishing two steps in its actuation. For the first step, first cylinder56bis actuated to thrust out piston rod56atogether with a piston (not shown) of first cylinder56b. For the second step, second cylinder56cis actuated to thrust out only piston rod56aseparately from first cylinder56b.

Description will be given on the control of first and second valves61and62and shutter53, and the control of plungers65with the actuation of discharging cylinders56during one process of charging the gelling agent into the nozzles. At the beginning, while the gelling agent is filled from gel charging hole57ato all gel passages54a, piston rod55aof valve cylinder55is actuated to the first actuating position. Therefore, first valve61blocks first gel passages54a, in other words, valve holes61aare offset from respective first gel passages54aso as not to send the gelling agent to gel charge casing57during the next extensive slide of plungers65. Simultaneously, second gel passages are fully opened with respective valve holes62aof second valve62. At this time, shutter63is located to arrange holes63ajust under respective drop holes98bof nozzles98.

From this condition, the plurality of discharging cylinders56are simultaneously actuated to advance plungers65slidably, thereby discharging the gelling agent, which has been filled in second gel passages54b, into respective nozzles98. More specified, the first actuation step of discharging cylinders56is established such that first cylinders56bis actuated to slightly advance plungers65(leftward). Therefore, a little amount of the gelling agent is discharged and formed into gel-membranes which are blocked in respective drop holes98bat the lower end portions of nozzles98. Then, seeds are dropped from absorption tips16above respective nozzles98and held in the gel-membranes at respective drop holes98bof nozzles98. Next, the second actuation step of discharging cylinders56is established such that second cylinders56care actuated to further advance plungers65, thereby thickening the gel-membranes holding the seeds in respective nozzles98. When the gel-membranes become sufficiently thick, the gel-coated seeds fall with their empty weight from respective drop holes98bthrough holes63aof shutter63so as to be transferred to hardening unit3for the next process.

Then, piston rod55aof valve cylinder55is switched to the second actuating position. Therefore, holes63aof shutter63are offset from respective drop holes98bof nozzles98so as to prevent nozzles98from leaking the gelling agent through drop holes98b. Simultaneously, second valve62blocks second gel passages54bso as to stop the gelling agent from being discharged to nozzles98. First valve61opens first gel passage54awith valve holes61aso as to fill the gelling agent from gel charging hole57athrough respective first gel passages54ato the upstream sides of second valve62in respective second gel passages54b, thereby being prepared for the next process of gel-discharging to nozzles98.

Description will be given on the structure of nozzle block58according to a first embodiment of the present invention. As shown inFIGS. 7,9and10, nozzle block58comprises an upper casing70and a lower casing71. The left top portion of lower casing71is made to fall a degree so as to form a joint surface. Upper casing70is spaced from the left end surface of valve casing54and fixedly placed on the joint surface. As shown inFIG. 4, a plurality of rods73laterally inserted into upper casing70project rightward so as to be disposed between the right end of upper casing70and the left end of valve casing54.

Upper and lower casings70and71are formed vertically throughout with nozzles98which are as many as absorption tips16. More specified, funnel-shaped casting holes98aformed in upper casing70communicate with respective drop holes98bformed in lower casing71through the joint surface between both casings70and71. Incidentally, a pipe99penetrates the joint surface between both casings70and71so as to prevent each of seeds from being hitched on the step between casting hole98aand drop hole98bwhich are diametrically different from each other.

As shown inFIGS. 9to11, lower casing71is laterally bored with connection holes71bwhose right ends communicate with respective second gel passages54b. The left ends of connection holes71bare curved vertically upward to be open at the joint surface between upper and lower casings70and71.

As shown in FIG.9and others, on the joint surface of lower casing71are formed distribution grooves71c, which are circular centering respective drop holes98bin horizontal section when viewed in plan. Distribution grooves71c, serving as galleries for the gelling agent, communicate with open ends of respective connection holes71b. Each distribution groove71cis formed over a range of 270° from left-rear 45° position to left-front 45° position with respect to each drop hole98b. Discharging holes71dare bored in lower casing71at 90° intervals from four positions of front and rear leftward 45° positions and front and rear rightward 45° positions, which are symmetric to the front and rear leftward 45° positions, in each distribution groove71c. The lower ends of four discharging holes71dare connected to a lower peripheral surface of each drop hole98bwith the same height such that the gelling agent can be discharged into the lower portion of each drop hole98bfrom four directions at 90° intervals.

Furthermore, on the top joint surface of lower casing71is formed seal grooves71eand71f, which are circular centering each drop hole98b. In the radial direction of each drop hole98b, seal groove71eis disposed inward from distribution groove71cand seal groove71fis disposed outward from distribution groove71c. Seals are engaged into respective seal grooves71eand71f, and then, upper casing70is fixedly mounted on lower casing71. Therefore, the seal in seal groove71fprevents the gelling agent from leaking outward along the junction surface of casings70and71from each distribution groove71c. Also, the seal in seal groove71eprevents the gelling agent from leaking inward to nozzle98from each distribution groove71c.

In this manner, the gelling agent discharged from each second gel passage54bby plunger65flows into each distribution groove71cthrough each connection hole71bso as to be evenly distributed among discharging holes71d, and is discharged into the lower portion of each nozzle hole98bso as to surely block this portion. Therefore, in each nozzle98is surely formed the gel-membrane for catching and holding a seed dropped thereinto, thereby surely forming gel-coated seeds. Consequently, the precision of processing gel-coated seeds can be improved.

Upper casing70is laterally bored with insertion holes70cintersecting respective casting holes98a. Open/close rod73is laterally slidably inserted into each insertion hole70c. Open/close rod73is a switching member which forms an intermediate portion of each nozzle98(casting hole98a) into an open/close portion. Each open/close rod73is bored vertically throughout with a hole73ain correspondence to each casting hole98a. Right end portions of open/close rods73project rightward from upper casing70and engage with a single interlocking plate96which is approximately as long as nozzle block58in the longitudinal direction. Therefore, right end portions of open/close rods73are connected through interlocking plate96to a tip of a piston rod95aof a nozzle open/close cylinder95disposed on the upper longitudinal middle portion of valve casing54. An air cylinder, an electromagnetic solenoid or a hydraulic cylinder may be provided as nozzle open/close cylinder95. Consequently, by single nozzle open/close cylinder95, open/close rods73of respective nozzles98fixed to interlocking plate96are simultaneously slid in respective insertion holes70c. Nozzles98are opened when holes73aare located coaxially with respective casting holes98cof nozzles98, as shown in FIG.7. And, nozzles98are blocked when holes73aare offset from so as to make the body of open/close rod73cross nozzles98, as shown in FIG.8. Thus, nozzles98are switched between their opened state and their blocked state. Incidentally, the right portion of each open/close rod73projecting rightward from the right side portion of upper casing70is formed at its bottom surface with a laterally long groove73b.

In upper casing70, air chambers70bare formed just below respective insertion holes70cso as to communicate with respective insertion holes70cthrough respective casting holes98aand orifices. Air chambers70bare open rightward. Compression pins74are laterally extended and formed at their left ends with respective pistons74a, which are laterally slidably inserted into respective air chambers70b. The right ends of compression pins74are slidably inserted into the left portion of valve casing54.

Each compression pin74is threaded around. Left and right pin stoppers97L and97R, which are nut-shaped, are laterally adjustably fit around each compression pin74. Each right pin stopper97R is disposed between the right end of each open/close rod73and the left end surface of valve casing54. A top portion of left pin stopper97L is arranged in groove73b. As shown inFIG. 7, when open/close rods73are located to open respective casting holes98athrough their holes73a, the right ends of open/close rods73abut against respective right pin stoppers97R. At this time, piston rod96of nozzle open/close cylinder96is located at its most retractive position, which is defined as its nozzle opening position. As piston rod96is extended, the right ends of open/close rods73come to abut against respective left pin stoppers97L in grooves73band push respective compression pins74leftward. Therefore, as shown inFIG. 8, open/close rods73block respective casting holes98aso that pistons74aare deeply inserted in respective air chambers70bso as to charge air under pressure from air chambers70binto casting holes98bbelow respective open/close rods73through the orifices. Consequently, the air is charged to drop holes98b. Incidentally, by adjusting the position of left pin stopper97L on compression pin74, the timing when each open/close rod73comes to abut against left pin stopper97L by extensive action of piston rod96ais adjusted. Therefore, the sliding degree of each piston74ain air chamber70b, i.e., the amount of air charged into each casting hole98acan be adjusted.

Description will now be given on a nozzle block158shown inFIGS. 12to15according to a second embodiment of the present invention.

As shown inFIGS. 12 and 13, nozzle block158formed therein with a plurality of (in this embodiment, eight) vertical nozzles198in a longitudinal row is fixed to the left end of valve casing54. For gel-coating a plurality of (eight) seeds at a time are provided sets of nozzles198, discharging cylinders56, etc., which are as many as the absorption tips16.

As shown inFIG. 14, the nozzle block158comprises a single upper casing171and lower casings171which are as many as nozzles198. Corresponding to the nozzles198, respective open/close rods173are laterally reciprocally inserted into upper casing170and project outwardly rightward into a space between the right end of upper casing171and the left end of valve casing54.

Nozzles198vertically penetrates upper casing170and respective lower casings171. Each of nozzles198is provided at the top portion thereof with a casting hole198awhich is tapered for easily receiving seeds cast from each absorption tip16. Each of nozzles198is provided at the bottom portion thereof with a drop hole198bformed in each of lower casings171so as to communicate with each casting hole198athrough a joint surface between upper and lower casings170and171. Each nozzle198is provided with a vertical seed guide sleeve199between casting and drop holes198aand198bthrough the joint surface between upper and lower casings170and171. A hole for guiding seeds vertically axially penetrating each seed guide member199is tapered at the top portion thereof so as to prevent the difference of diameter between casting hole198aand drop hole198bfrom causing such a step as to catch seeds.

As shown inFIGS. 14 and 15, each lower casing171comprises substantially vertical cylindrical inner nozzle sleeve172aand outer nozzle sleeve172barranged concentrically around the vertical axis of seed guide sleeve199. A single bottom plate172chaving a substantially rectangular shape is detachably fixed to the bottom end surface of upper casing170. Seed guide sleeve199is peripherally tightly fitted downward into inner nozzle sleeve172a, and inner nozzle sleeve172ais inserted downward into outer nozzle sleeve172b. A passage175for gelling agent is formed between the outer peripheral surface of inner nozzle sleeve172aand the inner peripheral surface of outer nozzle sleeve172b.

All outer nozzle sleeve172bare engaged downward into bottom plate172c. In bottom plate172c, drop holes198bare formed just below respective outer nozzle sleeves172b. For each of lower casings171, bottoms of seed guide sleeve199, inner nozzle sleeve172aand outer nozzle sleeve172bare arranged in downward order, and their bottoms are so open as to bring the axial hole for guiding seeds in seed guide sleeve199into communication with drop hole198b, thereby ensuring a passage for seeds from casting hole198ato drop hole198b. On the other hand, passage175is connected to drop hole198bserving as the gel-filled portion so as to charge the gelling agent into drop hole198b.

In a lower portion of upper casing170are bored lateral passages170afor supplying gelling agent to respective nozzles198. Passages170aare connected at right ends thereof to respective second gel passages54b. Each passage170ais open at the left end thereof on the joint surface between lower casing171(in detail, outer nozzle sleeve172b) and upper casing170. Each outer nozzle sleeve172bis outer-peripherally notched at the top end thereof so as to provide an annular gallery171for gelling agent which is enclosed by outer nozzle sleeve172b, upper casing170and an upper edge of inner nozzle sleeve172aabove outer nozzle sleeve172a. Each outer nozzle sleeve172bis provided at the upper edge thereof with a plurality of notches171darranged at substantially regular intervals along the periphery of outer nozzle sleeve172bso as to bring gallery171cinto communication with passage175. Preferably, notches171bare so arranged that each pair of them are disposed in opposite to each other with respect to the vertical axis of said nozzle198to be connected to drop hole198b.

For each of nozzles198, gelling agent discharged from second gel passage54bby plunger65flows into gallery171cand is evenly distributed into notches171dso as to be sent into drop hole198bthrough passage175from notches171b. Thus, the gelling agent is surely filled in the lower portion of drop hole198bso as to form a stable gel membrane for catching a seed cast into nozzle198, thereby enhancing the precise of gel-coating seeds.

For making the plurality of lower casings171corresponding to respective nozzles198, while seed guide sleeves199are previously inserted into upper casing170, inner nozzle sleeves172aare inserted into upper casing170so as to cover respective seed guide sleeves199, and outer nozzle sleeves172bare inserted into upper casing170so as to press inner nozzle sleeves172a. Then, single bottom plate172cis attached onto the bottom surface of upper casing170so that outer nozzle sleeves172bare fit at the bottoms thereof into bottom plate172cand fixedly engage with respective steps each of which is formed on the joint surface between bottom plate172band upper casing170. By removing bottom plate172cfrom upper casing170, inner and outer nozzle sleeves172aand172bcan be easily removed from upper casing170. Therefore, if any of nozzles198in nozzle block158is blocked with gel agent or has another trouble, any part of lower casing171corresponding to the troubling nozzle198is allowed to be repaired or changed independently of the other lower nozzles171.

As shown inFIG. 14, in each nozzle198, inner nozzle sleeve172ais provided at the top thereof with an annular groove171e, and outer nozzle sleeve172bis peripherally provided with an annular groove171f. Seals are provided in respective grooves171eand171fso as to abut against upper casing170, thereby preventing nozzle198from leak of gelling agent.

Upper casing170is bored with lateral insertion holes170cintersecting respective casting holes198a. Open/close rods173are laterally slidably inserted into respective insertion holes170c. Each open/close rod173is provided with a vertical through-hole173acorresponding to casting hole198aso as to constitute an open/close portion for passing/checking seeds at the intermediate portion of nozzle198(casting hole198a). A single interlocking plate196which is substantially longitudinally as long as nozzle block158is provided along nozzle block158. Interlocking plate196is provided with a short engaging portion196aand a long engaging portion196b. Open/close rods173project rightward from upper casing170and fixedly engage at the right end portions thereof with short engaging portion196aof connection plate196so as to be connected to piston rod95aof nozzle open/close cylinder95.

By acting single open/close cylinder95, all open/close rods173fixed to interlocking plate196are simultaneously slid in respective insertion holes170cbetween an opening position where through-holes173aof open/close rods173are disposed coaxially to respective casting holes198aof nozzles198, and a closing position where through-holes173aof open/close rods173are offset from respective casting holes198aof nozzles198so that open/close rods173block respective casting holes198cof nozzles198.

In upper casing170, air chambers170bare formed just below respective insertion holes170cso as to be connected to respective casting holes198athrough respective orifices. Air chambers170care rightwardly open, and compression pins174are laterally slidably inserted into respective air chambers170cthrough the right openings thereof. Each compression pin174is formed at the portion thereof rightwardly projecting from upper casing170with a downward recess174a. Long engaging portion196bof interlocking plate196is fitted into recesses174aof all compression pins174. When piston rod95aof nozzle open/close cylinder95is contracted, long engaging portion196bof interlocking plate196comes to abut against compression pins174at the right end of recesses174aso as to define the minimum stroke of piston rod95aof nozzle open/close cylinder95corresponding to the opening position of nozzles198where open/close rods173open respective casting holes198afor free passage through respective holes173athereof. When piston rod95aof nozzle open/close cylinder95is extended, long engaging portion196bof interlocking plate196slides leftward in recesses174aof compression pins174, and then abuts against compression pins174at the left ends of recesses174aand presses compression pins174leftward. Therefore, while open/close rod173shut off casting holes198a, compression pins174are deeply inserted into respective air chambers170bso as to charge air through the orifices into respective casting holes198abelow open/close rods173, and into respective drop holes198b.

In the foregoing structure of nozzles comprising an open/closing structure and an air pressure-charging structure, description will be given on the actuating timings of open/close rods73and compression pins74by controlling nozzle open/close cylinder96during forming gel-coated seeds in the nozzles in association with the control of valve cylinder55and discharging cylinders56for filling the gelling agent into the nozzles. In the following description, nozzle block58according to the first embodiment will be mainly referred to, so as to represent nozzle block158according to the second embodiment having the same function and effect.

At the beginning, as mentioned above, when piston rod55aof valve cylinder55is located at the first actuating position so that second valve62is opened and that first valve61is closed, discharging cylinders56are actuated to the first actuation step so as to extensively actuate first cylinder56bfor discharging a little amount of the gelling agent, thereby forming the gel-membranes in the lower portions of drop holes98b. At this time, open/close rods73are located rearward so as to open respective casting holes98athrough respective holes73a. Then, the seeds are dropped from absorption tips16and fall onto the gel-membranes formed in the lower portions of respective drop holes98b.

After the seeds fall, discharging cylinders56are actuated to the second actuation step so that second cylinders56care extensively actuated to discharge the gelling agent into the lower portions of drop holes98b, thereby gel-coating the seeds and dropping the gel-coated seeds from the lower portions of respective drop holes98b. Approximately simultaneously, nozzle open/close cylinders95are actuated, as shown inFIG. 8, so as to thrust open/close rods73into respective casting holes98cand block casting holes98a. Open/close rods73are further thrust in. Just before open/close rods73reach their limit positions, compression pins74with pistons74aare thrust in so as to charge air from air chambers70binto casting holes98a.

Casting holes98aare upwardly air-tightened by respective open/close rods73so that the pressure-charged air in casting holes98apressures downward the gel-coats plugging respective drop holes98bso as to separate the gel-membranes including seeds from drop holes98b. Therefore, the seeds coated with the gelling agent are dropped so as to be formed as gel-coated seeds. Hence, however small the seeds coated with the gelling agent may be so as to be impossible to fall with their empty weight, this charged-air enables the gel-membranes to be discharged from the lower portions of drop holes98bwithout remains stuck on drop holes98b, thereby surely forming gel-coated seeds. More specified, processing unit2is improved in its general versatility because it is adaptable to various sizes of seeds.

Air chambers70bare formed in nozzle block58(lower casing70), and the air-pressure is generated by reciprocating pistons74bof compression pins74which actuate interlockingly with open/close rods73in the blocking actuation. By such a simple structure, air can be charged into drop holes98bwithout another separate member such as a compressor, thereby saving costs.

After dropping the gel-coated seeds from drop holes98b, nozzle open/close cylinder95is retractively actuated in the opposite direction (rightward) so as to slide open/close rods73rightward, thereby opening drop holes98bso as to allow seeds to fall. Also, compression pins74are moved to the right side portions in respective air chambers70b. This series of actuation is repeated so as to form gel-coated seeds continuously.

As shown inFIG. 1, a control box11is disposed on a left side portion of base frame10. A controller is disposed in control box11. Output means, which are conveyor motor26in hardening unit3, conveyor motor27in rinsing unit4, and valve cylinder55, discharging cylinders56and open/close cylinder95in processing unit2, are connected to the controller, and input means like various sensors are connected to the same. Therefore, the output means are controlled so as to establish the above-mentioned motions.

A device for gel-coating seeds having the foregoing structure of nozzles according to the invention serve as a device which simultaneously coat many seeds in various sides with a gelling agent. Furthermore, by using this technique, a device for simultaneously coating many particles in various kinds and sides with gelling agent in various compositions may be structured.