CN1170379A - Pelletizer particularly suitable for pelletizing water dispersible melt-extrudate - Google Patents

Abstract

A pelletizer particularly useful for pelletizing water-dispersible melt-extrudate, among other materials, delivered from an extruder through a die positioned in communication with the interior of the pelletizer housing. The pelletizer includes a rotor disposed inside the housing and knives mounted around the periphery of the rotor. The knives pelletize the melt-extrudate as the rotor rotates. A fluid supply system selectively delivers a fluid, such as air, to the knives when the knives are at a selected location in the housing. The selected location is preferably just past the inlet and can extend in a circumferential direction around the housing in the area of the housing which is near the outlet. The circumferential extent can vary according to the configuration of the knives and the fluid supply system. The fluid supply system supplies fluid in a radially outward direction and tangentially along the cutting edge of the knives so as to sweep the pellets from the knives, as well as cool the knives, the pellets and the interior components of the pelletizer. The selective delivery of fluid sweeps the pellets off the knives as close to the outlet as possible. This prevents fouling, as well as avoids undesirable cooling of the knives in proximity to the die, which could lower the temperature and interrupt the flow of the extrudate.

Description

Granulators especially suitable for producing pellets of molten extrudates that dissolve in water

This patent application is a continuation-in-part of now abandoned US Patent Application Serial No. 08/357,618, filed December 15, 1994.

Background of the Invention

1. Field of the present invention

The present invention relates to a granulator for producing granular materials. In particular, the present invention relates to pelletizers for producing pellets of hydrodisintegrable melt extrudates, including fully water soluble melt extrudates.

2. Description of related technologies

Melt extrusion is an advanced method for producing granular agricultural products that dissolve in water. See for example published PCT patent application WO 9215197. A limitation to the commercial development of this technology is the inability of known pelletizers to produce pellets of molten extrudate that disintegrate in water, since these pelletizers are designed for water-insoluble materials and are cooled with water medium. Such typical granulators are described in US Patent No. 3,341,892 to Mayner, US Patent No. 3,753,637 to Gasior et al., and US Patent No. 5,186,959 to Tanaka. Water cooling is clearly not suitable for dissolving molten extrudates upon contact with water. If such known granulators were run without any cooling, fouling of the granulator would quickly result due to granules sticking to the granulator. Attempts to simply operate such known granulators with air instead of water have been unsuccessful due to insufficient air cooling.

Air-cooled granulators are also known. For example, Japanese Unexamined Patent Application Publication No. 5-169,441 discloses a pelletizer for producing thermal resin pellets, which pelletizer has spray holes formed on nozzle die openings to spray coolant from the die face, For example air. The die faces are disposed on the outer circumference of the rotor, while cooling air is delivered in a radially inward direction. US Patent No. 4,212,617 to Bagdan et al. discloses an apparatus for cutting cheese strips that delivers cooling air through channels disposed within the shaft. Cooling air is delivered to the inner edge of the blade assembly, which is spaced from the cutting edge of the blade. Thus, while the devices of No. 5-169,441 and Bagdan et al. provide means for cooling the blades, neither device assists in sweeping particles from the blades in a configuration that prevents fouling of the granulator. Conversely, in both devices, when the rotor on which some blades are mounted turns, the centrifugal force causes the granules to be thrown in all directions inside the granulator, fouling the granulator.

Accordingly, there is a need for a pelletizer that can produce pellets of molten extrudate that disintegrate on contact with water and at the same time assist in sweeping the pellets from the blades in a configuration that effectively prevents pelletizer fouling.

Summary of the invention

The present invention solves the problems of the prior art by providing efficient air cooling of pelletizers which produce pellets of hydrodisintegrable molten extrudate. It should also be noted, however, that the pelletizer of the present invention can provide effective air cooling for almost any material being pelletized, as long as the material can be extruded and is brittle or hard enough to be cut into pellets at melt extrusion temperatures. .

The present invention also solves some of the problems of the prior art by providing some mechanism to prevent fouling of the granulator. In the present invention, the cooling blades, granules and cooling fluid inside the granulator are delivered to at least one blade in a radially outward direction and tangential to the cutting edge of the blades to sweep the granules from the blades. Also, when the blades are located within the housing close to the pelletizer outlet, cooling fluid is delivered to the blades, thus increasing the chances of pellets going directly to the outlet immediately and without fouling around the inside of the housing. In addition, the enclosure can be configured with a fluid supply inlet that sweeps the particles along the enclosure wall toward the outlet, also providing additional cooling to the blades, particles, and enclosure internal components.

In order to obtain the solution of the aforementioned problems, and in accordance with the object of the present invention, as embodied and generally described herein, there is provided a granulator for granulating material comprising a rotor rotatable around an axis of rotation; at least one bladed , blades mounted on the rotor for cutting material into particles as the rotor rotates; and means for supplying fluid in a radially outward direction and tangential to the cutting edges of the blades to sweep the particles from the blades.

In addition, according to the purpose of the present invention, there is provided a granulator for granulating materials, which comprises a casing; a rotor arranged in the casing and capable of rotating around an axis of rotation; at least one rotor mounted on the rotor for blades for cutting material into particles as the rotor rotates; and means for selectively supplying fluid to the blades through the rotor when the blades are in selected positions within the housing.

A brief description of the accompanying drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the invention and together with the description serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a longitudinal sectional view taken through the centerline of a die opening and pelletizer according to a first embodiment of the present invention.

FIG. 2 is a partial sectional view of the granulator of the first embodiment with the top cover removed, taken through line 2-2 of FIG. 1. FIG.

Figure 3 is a longitudinal sectional view taken through the centerline of a die opening and pelletizer according to a second embodiment of the present invention.

Figure 4 is a partial sectional view of the granulator of the second embodiment with the top cover removed, taken through line 4-4 of Figure 3 .

Figure 5 is a longitudinal sectional view taken through the centerline of a die opening and pelletizer according to a third embodiment of the present invention.

Fig. 6 is a partial sectional view of the third embodiment granulator with the top cover removed, taken through line 6-6 of Fig. 5 .

Detailed Description of Preferred Embodiments

The presently preferred embodiments of the invention will not be discussed in detail, only examples are illustrated in the drawings. Wherever possible, the same reference numbers will be used throughout the drawings to designate the same or like parts.

According to the present invention, a first embodiment of the invention includes a granulator for granulating material. Although the pelletizer of the present invention is particularly useful for producing pellets of hydrodisintegrable molten extrudates, which entirely includes water-soluble molten extrudates, the use of the present invention is not limited to this material. Thus, the pelletizer of the present invention can be used to produce pellets of almost any material that is extrudable and brittle enough to be cut into pellets at its melt extrusion temperature. The pelletizer of the present invention is particularly suitable for materials which become brittle soon after being cooled by a cooling fluid, since the material can be pelletized on the die face and then cooled immediately, as will be explained below.

Referring to Figs. 1 and 2, a granulator according to a first embodiment will be described. A pelletizer according to a first embodiment is shown generally at 10 in FIGS. 1 and 2 in an operative position on the die face of the extruder. The die opening is marked 12 in FIGS. 1 and 2 . The remainder of the extruder feeding the die is not shown.

The granulator of the first embodiment comprises a cabinet 14 shown in FIGS. 1 and 2 . The cabinet 14 has an interior front wall 14a and an interior rear wall 14b shown in FIGS. 1 and 2 . The enclosure 14 also includes a top cover 16 shown in FIG. 1 for covering the top of the enclosure. The die opening 12 is configured on the casing, as shown in FIGS. 1 and 2 . As shown particularly in FIG. 2, die opening 12 has a plurality of holes 18 formed therein, only one of which is shown in FIG. For convenience, only one hole is marked in Figure 2. Material, such as molten extrudate, is extruded through holes 18 which include an inlet into the housing. The housing also includes an outlet 20 . A cooling chamber 22 is contained within one side of the enclosure as shown in Figures 1 and 2, cooling the interior rear wall 14b of the enclosure. The casing and the cooling cavity are welded structures, and the top cover plate 23a and the bottom cover plate 23b seal the cooling cavity, as shown in FIG. 1 . In addition, part 27a is located on one side of the housing and is located at the top of the housing as shown in Figure 1, which contains the outlet for the fluid. Similarly, part 27a is provided at the bottom of the casing as shown in FIG. 1, and this part contains the inlet for fluid. The inlet and outlet are shown as tapered and they fit with pipe threads. The cooling fluid passing through the cooling cavity 22 may be either air or liquid. A pair of fluid supply inlets 24a and 24b, shown in FIG. 1, may be formed in the enclosure top 16 for sweeping material particles along the interior walls of the enclosure. The sweeping action is illustrated by arrow 25 shown in FIG. 1 . Furthermore, the fluid supply inlet provides additional cooling to the interior of the granulator. As discussed above for the first embodiment, the fluid supply inlet 24b shown on the right in Figure 1 is used to connect to the cooling chamber if air is used in the cooling chamber. In this case, cooling fluid enters the cooling cavity from a supply source (not shown) and is introduced via arrow 29 into part 27b. Cooling fluid exits the cooling chamber through upper part 27a and feeds fluid to inlet 24b so that fluid exiting cooling chamber 22 sweeps particles along the inner walls of the enclosure. If liquid is used in the cooling chamber, the cooling chamber is blocked from the supply inlet 24b and air is fed through holes 27a and inlet 24b respectively as described above for cooling and sweeping of material particles.

The granulator of the first embodiment also includes a rotor disposed in the housing and rotatable about the axis of rotation. The rotor 26 is disposed within the housing 14 as shown in FIGS. 1 and 2 . The shaft 28 is arranged along the axis of rotation of the rotor, and the rotor rotates about the axis. Preferably, shaft 28 is fixed and does not rotate with the rotor. The rotor is rotated by any known means such as a motor and coupling not shown, or a connecting belt to the end of a shaft extending through the casing 14, as shown in FIG. The rotor 26 is journalled at each end by bearings 30a and 30b, respectively, as shown in FIG. The end cover 32 fits between the bearing 30b and the rotor 26 as shown in FIG. 2 . End cap 32 is fastened to the shaft by bolts 35 and keeps bearing 30b positioned against the shaft. A shaft cover 33 as shown in Figure 2 separates the shaft from the exterior of the housing and enables quick access to the interior of the housing.

The granulator of the first embodiment further includes at least one cutter having a cutting edge and mounted on the rotor to cut the material into granules when the rotor rotates. The at least one cutter may be a single blade, or a plurality of blades. The number of blades depends on how fast the material comes out of the die face and how fast the rotor turns. It is best to use at least two blades. Eight blades such as blades 34a-34h are shown in FIG. 1 . The blades are firmly aligned on the rotor at a cutting angle so that the material is cut on the die face as soon as it emerges from the die.

The present invention clearly recognizes the fact that the centrifugal force generated by the rotating rotor tends to throw the particles radially outwards after they have been cut. However, it is also clearly recognized by the present invention that these particles tend to fall towards the outlet due to gravity. With the configuration of the invention, the particles can emerge from the housing as quickly as possible. This avoids the possibility of granules being thrown around the inside of the granulator, thereby preventing fouling of the granulator. Thus, in accordance with the present invention, the pelletizer of the first embodiment further includes means for selectively supplying fluid to the blades via the rotor when the blades are in selected positions within the housing. This optional location is preferably just past the inlet and may extend around the circumference of the housing in the region of the housing close to the outlet. The extent of the circumference may vary depending on the configuration of the blades and fluid supply. In the configuration illustrated for the first embodiment in FIG. 1 , the extent of the circumference is about 180°. Alternatively, or in addition, the granulator of the first embodiment may also be described as including means for supplying fluid in a radially outward direction and tangentially to the cutting edges of the blades to sweep particles from the blades.

As practiced herein, the fluid supply means includes a fluid supply system. The fluid supply system of the first embodiment of the present invention performs several functions. It cools the blades, pellets and pellet mill parts inside the housing. Also, since the fluid supply system supplies fluid in a radially outward direction and tangentially to the cutting edge of the blade, this system provides the greatest possible force to sweep particles off the blade.

In the first embodiment of Figures 1 and 2, the fluid supply system includes a fluid port formed in the rotor adjacent each blade for supplying fluid to the blade. Fluid ports 36a-36h are located within rotor 26 adjacent blades 34a-34h, respectively, as shown in FIG. However, as mentioned above, when only a single blade is used, only one fluid port is formed in the rotor. Only one fluid port need be provided adjacent to each blade. The fluid port can be any desired structure suitable for delivering fluid to the blade. For example, another alternative configuration could be a series of holes formed radially within the rotor, which holes could occupy the same radial area as the fluid ports. In the first embodiment, fluid is supplied radially outwardly through fluid port 36d and tangentially to the cutting edge of the blade, as indicated by arrow 39 in FIG. 1 .

In a first embodiment, the fluid supply system also includes a fluid supply channel disposed within the shaft. The fluid supply channel 38 is shown in FIGS. 1 and 2 . The fluid supply system of the present invention also includes a fluid supply channel 40 , one end of which is connected to the fluid supply channel as shown in FIG. 1 . The fluid supply passage 40 is suitably connected at its other end to a fluid source 42 .

In the first embodiment of FIGS. 1 and 2, the fluid supply system further includes a slot configured in fluid communication with the fluid supply channel and with the fluid port in the rotor. Slot 44 is shown in FIGS. 1 and 2 . The slots 44 supply fluid to one or more fluid ports, which in turn supply fluid to the communicating blades. The circumferential extent of the groove is chosen such that no fluid flows to the blade as the groove approaches the die opening. This is because the cooling fluid can lower the temperature of the material and possibly interrupt the flow of the material from the die.

The granulator of the first embodiment also includes a sleeve arranged on the outer circumference of the shaft, the sleeve 46 being shown in FIGS. 1 and 2 . A groove is formed on a part of the outer circumference of the sleeve. Sleeve 46 is secured to stationary shaft 28 by any suitable means such as key 48 shown in FIG.

Air must be used in the fluid supply system of the present invention when a water-dissolving, especially, water-soluble, melt extrudate is pelletized. Preferably, the air has a lower amount of moisture so as not to dissolve the extrudate. However, it is within the scope of the invention to use other fluids, such as water, when using water-insoluble materials. The cooling fluid may be any suitable gas other than air, such as nitrogen, carbon dioxide and the like, or any mixture thereof. Regardless of the fluid used, the temperature of the fluid is usually lower than the temperature of the extruded material, preferably the ambient temperature, as this is the most economical mode of operation. Another possibility is that the fluid can be cooled below the ambient temperature if cooling is required faster than with an ambient temperature fluid.

In operation, material, such as molten extrudate, is conveyed from the extruder to die 12 and fed through holes 18 into the interior of the housing to form multiple strands of material. The strands are cut into pellets by the blade closest to the die, such as blade 34a in FIG. As the rotor 26 is rotating, each blade, which in turn reaches the position occupied by the blade 34a in FIG. 1, cuts the strands into particles. As shown in FIG. 1, the blades 34c-34f, or any blades rotated to these respective positions, are in fluid communication with the slot 44 as the rotor rotates. In the first embodiment, cooling fluid supplied by source 42 enters groove 44 through passage 40 and channel 38 and is delivered to blades 34c-34f through communicating fluid ports 36c-36f. Fluid ports direct fluid, such as air, radially outward and tangential to the cutting edge of each blade to cool the blades, particles and internal components of the housing and to sweep particles from the blades. Fluid supply inlets 24a and 24b formed in the enclosure top 16 may also be used to sweep particles along the interior of the enclosure and provide additional cooling. The fluid supply inlet 24b is supplied with air from the cooling cavity 22 formed in the cabinet. Cooling fluid flows from a fluid source through an inlet formed in part 27b, through cavity 22, through an outlet formed in part 27a and back to fluid supply inlet 24b. Alternatively, if a liquid is used in the cooling chamber, the cooling chamber is blocked from the supply inlet 24b and air is fed through port 27a and through inlet 24b respectively for cooling and sweeping as described above material particles. Once cut, the particles fall through the outlet 20 of the housing 14 by gravity. These particles can be collected on a conveyor belt, not shown, arranged outside the housing, which allows the particles to be further cooled before being transported by the conveyor belt to a collection hopper, also not shown.

According to a second embodiment of the present invention, there is provided a different type of granulator for granulating material. The granulator of the second embodiment will be described in conjunction with Figures 3 and 4, in which those components identical to those of the first embodiment are designated with the same reference numerals as in Figures 1 and 2, but include a prime in the upper right corner Number('). The granulator according to the second embodiment is generally 10'

It is shown in Figures 3 and 4 in the operative position on the die face of the extruder. The die opening is shown at 12' in Figures 3 and 4 . As in the first embodiment, the pelletizer of the second embodiment is particularly suitable for producing pellets of hydrodisintegrable molten extrudate, but its utility is not limited to this material.

The granulator of the second embodiment includes a housing 14' as shown in FIGS. 3 and 4 . The housing 14' has an interior front wall 14a' and an interior rear wall 14b', as shown in FIGS. 3 and 4 . The housing 14' also includes a top cover 16' as shown in FIG. 3 for covering the top of the housing. Die opening 12' is disposed within the housing as shown in Figures 3 and 4 . As shown particularly in FIG. 4, the die opening 12' has a plurality of holes 18' formed in the housing, only one of which is shown in FIG. For convenience, only one hole is marked in Figure 4. Material, such as molten extrudate, is extruded through holes 18' which include an inlet to the casing. The housing also includes an outlet 20'. A cooling chamber 22' for cooling the inner rear wall 14b of the cabinet is contained within one side of the cabinet as shown in FIGS. 3 and 4 . The casing and the cooling cavity are welded structures, and the top cover plate 23a' and the bottom cover plate 23b' seal the cavity as shown in FIG. 3 . In addition, a part 27a' is provided on the side of the case at the top of the case as shown in FIG. 3, and this part includes a fluid outlet. Similarly, a part 27b' is provided at the bottom of the housing as shown in FIG. 3, and this part includes a fluid inlet. As in the first embodiment, both the inlet and outlet are shown as tapered, which indicates a pipe thread fit. The cooling fluid passing through cavity 22' is either air or liquid. A pair of fluid supply inlets 24a', 24b' shown in FIG. 3 may be formed in the enclosure top cover 16' as described above for the first embodiment for sweeping particles along the interior walls of the enclosure. This sweeping action is illustrated by arrow 25' shown in FIG. If air is used in the cooling chamber, a fluid supply inlet 24b' as shown on the right in FIG. 3 is used in connection with the cooling chamber. In this case, cooling fluid enters the cooling cavity from a fluid source (not shown) and is then introduced into part 27b' via arrow 29'. Cooling fluid exits the cooling cavity through the upper part 27a' and is fed into the fluid supply inlet 24b' so that the fluid exiting the cooling cavity 22' sweeps material particles along the inner walls of the enclosure. If a liquid is used in the cooling chamber, the cooling chamber is blocked from the supply inlet 24b' and the air passes through port 27a' and through inlet 24b respectively.

Feed for cooling and sweeping of material particles as described above.

The granulator of the second embodiment includes a rotor disposed within a housing and rotatable about an axis of rotation. A rotor 26', shown in Figures 3 and 4, is disposed within the housing 14'. The second embodiment granulator also includes a shaft 28' disposed along the axis of rotation of the rotor, as seen in Figure 4 but spaced from the rotor. As seen in Figure 4, the rotor is rotated by any known means connected to the end of the rotor projecting through the casing 14', such as a motor and coupling not shown, or a connecting belt. In a second embodiment, the rotor is cantilevered from such a connection and rotates about an axis 28' without being journalled at either end. As shown in Figure 4, the shaft cover 33' separates the shaft from the exterior of the housing and enables quick access to the interior of the housing. Same as in the first embodiment. Shaft 28' is preferably fixed.

The granulator of the second embodiment also includes at least one knife having cutting blades mounted on the rotor for cutting the material into granules when the rotor rotates. As in the first embodiment, the at least one knife may be a single blade, or a plurality of blades. In addition, the number of blades depends on how fast the material comes out of the die face and the speed of the rotor rotation. In this embodiment, preferably at least 4 blades are used. Eight blades 34a'-34h' are shown in FIG.

The pelletizer of the second embodiment also includes selectively supplying fluid to the blades via the rotor when the blades are in selected positions within the housing. Although in the second embodiment, as illustrated in FIG. 3, the range of this selection position is about 90°, this selection position is determined with reference to the first embodiment described above. Alternatively, or in addition, the granulator of the second embodiment may be described as including means for supplying fluid in a radially outward direction and tangential to the cutting edge of the blade to sweep the granules from the blade. installation. The fluid supply of the second embodiment cools the blades, particles and the interior of the housing while preventing fouling, as described above for the first embodiment. As embodied herein, the supply device of the second embodiment includes a fluid supply system. Same as in the first embodiment. Fluids other than air may be used in the fluid supply system of the second embodiment.

In the second embodiment of Figures 3 and 4, the fluid supply system includes a fluid port formed in the rotor adjacent each blade. As shown in FIG. 3, fluid ports 36a'-36h' are all formed within rotor 26' adjacent to respective blades 34a'-34h'. Fluid is supplied through fluid port 36b' radially outwardly and in the direction of the cutting edge of the blade as indicated by arrow 39'. As noted above for the first embodiment, when only a single blade is used, only one fluid port is formed in the rotor. Only one fluid port need be provided adjacent to each blade. The fluid port can be any structure suitable for delivering fluid to the blade, such as described above for the first embodiment.

The fluid supply system of the second embodiment also includes a fluid supply channel disposed within the shaft. Fluid supply channel 38' is shown in FIG. 3 . The fluid supply system of the second embodiment further includes a fluid supply channel 40', one end of which is connected to the fluid supply channel as shown in FIG. The fluid supply passage 40' is suitably connected at its other end to a fluid source 42' as shown in FIG.

In a second embodiment illustrated in Figures 3 and 4, the fluid supply system further includes a slot configured in fluid communication with the fluid supply channel and with the fluid port in the rotor. Groove 44' is shown in FIGS. 3 and 4 . A groove 44' is formed on a portion of the outer circumference of the shaft. In the most preferred implementation of the second embodiment, only one fluid supply channel is used, and the slots distribute the fluid supply for continuous flow. It should be noted, however, that if grooves are not used, several additional fluid supply channels could be used in the second embodiment for intermittent flow. As in the first embodiment, the circumferential extent of the grooves of the second embodiment is selected such that no fluid flows to the blades as they approach the die opening.

In operation, material, such as molten extrudate, is conveyed by the extruder to die 12' and fed through holes 18' into the interior of the casing to form a multi-strand rope. The strands are cut into pellets by the blade closest to the die, such as blade 34h' shown in FIG. 3 . As the rotor 26' is rotating, each successive blade reaching the position occupied by the blade 34' in FIG. 3 cuts the strands of material into particles. As shown in FIG. 3, blades 34b' and 34c', or whichever blades pivot into these respective positions as the rotor rotates, are in communication with slot 44'. In the second embodiment, cooling fluid supplied by source 42' passes through passage 40' and channel 38' into groove 44' and is delivered to blades 34b' and 34c' through associated fluid ports 36b' and 36c'. The fluid ports direct fluid, such as air, in a radially outward direction and tangentially along the cutting edges of the blades to cool the blades, particles and internal components of the housing while sweeping the particles from the blades. As in the first embodiment, fluid supply inlets 24a' and 24b' formed in the enclosure top 16' also serve to sweep particles along the enclosure walls and provide additional cooling. The fluid supply inlet 24b' is supplied with air from a cooling cavity 22' formed in the housing. Cooling fluid flows from the source through the inlet formed in part 27b', through cavity 22', through the dispersion cavity formed in part 27a' and back to fluid supply inlet 24b'. Another alternative is that if a liquid is used in the cooling chamber, the cooling chamber is blocked from the supply inlet 24b' and the air is fed separately through port 27a' and through inlet 24b', as before It is used to cool and sweep away material particles. Once cut, the pellets fall and pass through the housing 14' onto a conveyor belt (if used), as described above for the first embodiment.

It should be noted that the granulator of the second embodiment is an improved version of the granulator commercially available from Werner & Pfleiderer, of Ramsey, New Jersey. Bought, model MWG 40. The rotor of the commercially available granulator was modified into a commercially available variant by changing its four sides to eight sides. The blades of this commercially available granulator were also modified to accommodate the new configuration of the rotor. The shaft 28' is also enlarged, and passages 40', channels 38' and 44' are formed in the shaft for fluid transfer. Port cover 33' has also been enlarged to accommodate the enlarged shaft. In addition, cooling chamber 22', and associated cover plates 23a', 23b', components 27a', 27b' and fluid supply inlets 24a', 24b' are added to the housing of commercially available pelletizers.

According to a third embodiment of the present invention, another variant of a granulator for producing granules of material is provided. The granulator of the third embodiment will be described with reference to Figures 5 and 6, in which those parts which are the same as those of the first and second embodiments are given the same reference numerals as in Figures 1-4 as appropriate , but add a double prime (") in the upper right corner of the number ("). According to the third embodiment, the granulator in the operating position on the die face of the extruder is generally represented by 10" in FIGS. 5 and 6. The die opening is indicated at 12" in Figures 5 and 6. As with the first two embodiments, the pelletizer of the third embodiment is not limited to the use of water-disintegrable materials, although it is particularly suitable for such materials.

The pellet mill of the third embodiment includes a housing 14" shown in Figures 5 and 6. The housing 14" as shown in Figures 5 and 6 has an inner front wall 14a" and an inner rear wall 14b". The housing 14" also includes a top cover 16" as shown in FIG. 5 for covering the top of the housing. The die opening 12" configured in the casing is shown in Figures 5 and 6. As shown particularly in Figure 6, the die opening 12" has a plurality of holes 18" formed in the casing, only one of which is shown in Figure 5 For convenience, only one hole is labeled in Figure 6. Material, such as molten extrudate, is extruded through holes 18", which include the inlet to the housing. The casing also includes an outlet 20 ". As shown in Figures 3 and 4, the cooling cavity 22 " of the inner rear wall 14b " for cooling is included in one side of the casing as shown in Figures 5 and 6. Same as the above embodiment , the casing and the cooling cavity are welded structures, as shown in Figure 5, the top cover plate 23a "and the bottom cover plate 23b" seal the cooling cavity. In addition, the parts 27a" are provided on the side of the casing as shown in Figure 5 and are located at the The top of the housing, this part contains a fluid outlet. Similarly, a part 27" is provided at the bottom of the casing as shown in Fig. 5, and this part contains a fluid inlet. Like the above embodiment, the inlet and outlet are shown as tapered, and they are fitted with pipe threads. By cooling The cooling fluid for cavity 22" is either air or liquid. A pair of fluid supply inlet 24a ", 24b " can be formed in casing top cover 16 " as shown in Figure 5 and be used for sweeping material particle along the inner wall of casing as above to first embodiment narration. This sweeping effect Illustrated by arrow 25" shown in Fig. 5 . In addition, the fluid supply inlets 24a", 24b" provide additional cooling to the inner walls of the granulator. As described for the above embodiment, if air is used in the cooling chamber, the fluid supply inlet 24b" shown on the right side of Fig. 5 is used to connect with the cooling chamber. In this case, the cooling fluid is supplied from a source (not shown) Enter the cooling chamber and enter the component 27b through the arrow 29 ". The cooling fluid passes through the upper part 27a " to come out of the cooling chamber and feed into the fluid supply inlet 24b ". Generally, the fluid coming from the cooling chamber sweeps the material particles along the inner wall of the casing. If Where liquid is used in the cooling chamber, the cooling chamber is blocked from the supply inlet 24b" and air is fed through port 27a" and through inlet 24b", respectively, for cooling and sweeping of material particles as described above.

The granulator of the third embodiment further includes a rotor disposed in the housing and rotatable around the axis of rotation. The rotor 26" disposed within the casing 14" is shown in FIGS. 5 and 6. Referring to FIG. As in the second embodiment, it can be seen from Figure 6 that the shaft 28" extends only partially along the axial length of the casing and does not pass completely through the rotor. A shaft cover 33" separates the shaft from the exterior of the casing as shown in Figure 6 And enable quick access to the inside of the enclosure. Preferably, the shaft 28" is fixed. As shown in Fig. 6, the rotor is connected to one end of the rotor protruding from the casing 14" by any known means such as an electric motor and coupling or connecting belt not shown. and was rotated.

The pelletizer of the third embodiment also includes at least one blade having a cutting edge and mounted on the rotor for cutting the material into pellets as the rotor rotates. As in the first two embodiments, this at least one knife can be a single blade or a plurality of blades. Also, the number of blades depends on how fast the material comes out of the die face and how fast the rotor turns. In this embodiment, preferably at least two blades are used. Eight blades 34a"-34h" are shown in FIG. In the third embodiment, only the blades are cantilevered from the rotor for rotation about axis 28", in contrast to the second embodiment in which the rotor and associated blades are cantilevered.

The pelletizer of the third embodiment also includes selectively supplying fluid to the blades through the rotor when the blades are in selected positions within the housing. This selected location is determined with reference to the first embodiment above, although in the third embodiment, as illustrated in Figure 5, the selected location extends the circumferential length of the fluid supply channel 38", as described below. Alternatively, or The granulator of the third embodiment can be described as comprising means for supplying fluid in a radially outward direction and tangential to the cutting edge of the blade so as to sweep the particles from the blade. As described above for the first embodiment, The fluid supply device of the third embodiment cools the inside of the blade, the particles, the rear casing while preventing fouling. As implemented here, the fluid supply device of the third embodiment includes a fluid supply system. And in the first two implementations As in the example, a fluid other than air may be used in the fluid supply system of the third embodiment.

In a third embodiment of Figures 5 and 6, the fluid supply system includes a fluid supply channel disposed within the shaft. The fluid supply channel 38" is shown in Fig. 5. In the third embodiment, the position of the fluid supply channel is selected such that no fluid flows to the blade when approaching the die to prevent lowering the temperature of the material and interrupting the flow of the material from the die Out, as described above for the first two embodiments. Fluid is supplied through channel 38" radially outwardly and tangentially to the cutting edge of the blade, as indicated by arrow 39".

The fluid supply system of the third embodiment also includes a fluid supply passage configured to communicate with the fluid supply channel and suitably connected to a fluid source. Fluid supply passage 40"is shown in FIGS. 5 and 6 in communication with fluid supply channel 38". The fluid supply passage 40" is suitably connected to a fluid source 42" as shown in FIG.

In operation, material, such as molten extrudate, is conveyed by the extruder to die 12" and then fed through holes 18" into the interior of the housing to form strands of material. The strands of material are chopped into pellets by the blade closest to the die, such as blade 34a" shown in FIG. The strands are granulated. As shown in Figure 5, the blade 34c", or any blade that is turned to this position when the rotor rotates, communicates with the fluid supply channel 38". In a third embodiment, the source 42" Cooling fluid is supplied through passage 40", enters channel 38" and is delivered to blade 34c". The channel conducts fluid, such as air, radially outward and tangential to the cutting edge of the blade to cool the blade, particles Particles are swept from the blades at the same time as components in the casing. As in the first two embodiments, fluid supply inlets 24a" and 24b" formed in the casing top cover 16" are used to sweep particles along the inner walls of the casing , and provide additional cooling. The fluid supply inlet 24b" is supplied with air from the cooling cavity 22" formed in the cabinet. Cooling fluid flows from the source through the inlet formed in part 27b", through the cooling cavity 22", through the outlet formed in part 27a", and then back to the fluid supply inlet 24b". On the other hand, if a liquid is used in the cooling chamber, the cooling chamber is blocked from the supply inlet 24b" and air is supplied via inlet 27a" and via inlet 24b" respectively for cooling and sweeping of the material particles as shown above. Once cut , the particles fall through the casing 14", if a conveyor belt is used and falls on it, as described above for the first embodiment.

The granulator of the third embodiment is also a modified version of the MWG 40 model granulator, commercially available from Wemer & Pfleiderer. Modifications to a commercially available granulator to obtain the granulator of the third embodiment were similar to the modifications performed to obtain the granulator of the second embodiment. The rotors of commercially available granulators have been modified to have eight sides instead of the four sides of existing commercial models. The blades of this commercially available granulator were also modified to accommodate the new configuration of the rotor. The shaft 28" is also enlarged, and passages 40" and channels 38" are formed in the shaft to conduct fluid. The shaft cap 33" is enlarged to accommodate the shaft enlargement. In addition, cooling chamber 22", and associated cover plates 23a", 23b", components 27a", 27b", and fluid supply inlets 24a", 24b" are added to the housing of commercially available pelletizers.

It will be apparent to those skilled in the art that various modifications and changes can be made in the structure of the granulator of the first to third embodiments of the present invention without departing from the scope and spirit of the present invention. As an example, the shaft may not need to be stationary, but only needs to rotate at a different speed than the rotor in order for the fluid supply system to deliver fluid to the blades at selected locations within the housing. It is true that there can be one, two, or even multiple blade rotational speed to blade number ratios, as long as air is supplied at the same location at all times.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and examples of the invention disclosed herein. It is intended that the specification be considered exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

Claims (19)

1. The granulator used to produce a material granule includes: (a) a rotor rotatable about an axis of rotation; (b) at least one blade having a cutting edge and mounted on the rotor for cutting material into particles as the rotor rotates; (c) Means for supplying fluid radially outwardly and tangentially to the cutting edge of the blade to sweep particles from the blade. 2. The granulator used to produce a material granule includes: (a) a casing; (b) a shaft extending from the casing; (c) a rotor capable of rotating about an axis; (d) at least one blade mounted on the rotor for cutting material into particles; and (e) means for selectively supplying fluid to the blades through the rotor when the blades are in selected positions within the housing. 3. The granulator of claim 1, further comprising a casing surrounding the rotor, wherein the casing has a front inner wall and a rear inner wall. 4. The granulator according to claim 2 or 3, characterized in that the casing has a cooling cavity for cooling the rear inner wall of the casing. 5. A granulator as claimed in any one of claims 2 or 3, further comprising a fluid supply inlet formed in the housing for sweeping material particles along the housing wall. 6. The granulator according to claim 5, characterized in that the casing has a cooling cavity for cooling the rear inner wall of the casing, and also includes a fluid supply inlet formed in the casing and communicated with the cooling cavity. , used to sweep material particles along the wall of the casing. 7. The granulator of claim 1, wherein the fluid supply means comprises a fluid supply system. 8. The granulator of claim 2, wherein the fluid supply means comprises a fluid supply system. 9. A granulator as claimed in any one of claims 7 or 8 further comprising a shaft disposed along the axis of rotation of the rotor. 10. A granulator as claimed in claim 9, characterized in that the fluid supply means comprises a fluid supply channel arranged in the shaft. 11. A granulator as claimed in claim 10, wherein the fluid supply system further comprises a fluid supply channel connected at one end to the supply channel and at the other end for connection to the fluid source. 12. A granulator as claimed in any one of claims 7 or 8 wherein the fluid supply system includes a fluid port disposed in the rotor adjacent the blade for supplying fluid to the blade. 13. The granulator of claim 12, wherein the fluid supply system further includes a channel arranged in fluid communication with the fluid supply channel and with the fluid port in the rotor. 14. The granulator as claimed in claim 13, further comprising a sleeve disposed on the outer circumference of the shaft, wherein the groove is formed in a part of the outer circumference of the sleeve. 15. A granulator as claimed in claim 14 wherein the shaft is stationary and the sleeve is mounted on the stationary shaft so that the grooves communicate with the fluid ports when the rotor rotates. 16. A granulator as claimed in claim 13, wherein the groove is formed on a part of the outer circumference of the shaft. 17. A granulator as claimed in any one of claims 1 or 2, characterized in that the rotor is cantilevered. 18. A granulator as claimed in any one of claims 1 or 2, characterized in that the blades are cantilevered. 19. Granulators for producing pellets of water-soluble molten extrudates include: (a) a casing; (b) a rotor disposed within the casing and capable of rotating about an axis of rotation; (c) a plurality of blades mounted on the outer circumference of the rotor; (d) a plurality of fluid ports formed in the rotor, wherein a blade is associated with each fluid port; (e) a stationary shaft disposed inside the rotor; (f) air supply passages formed in the shaft; (g) an air supply channel formed in the shaft and arranged to communicate with the air supply passage; (h) a sleeve arranged around the outer circumference of the rotor through which the air supply channel extends; and (i) A groove disposed on a part of the outer circumference of the sleeve, the groove communicating with the air supply channel for supplying air to the blade.

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