| Title of Invention | "POLISHING MACHINE" |
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| Abstract | The invention relates to a polishing machine for rice or other cereals, said machine comprising an octagonal strainer basket (5) and a polishing compartment. The strainer basket (5) comprises two carved walls in the form of shells comprising inwardly projecting ribs (10). The two halves are connected to a divided strainer (2), preferably by means of screwing and spacers, in order to form a supporting strainer basket (5). |
| Full Text | POLISHING MACHINE The invention relates to a polishing machine, in particular to a polishing machine or grinding machine for polishing or grinding rice grains or wheat, etc. Polishing or grinding machines for rice or other grains with horizontally or vertically arranged grinding or polishing rotor constitute prior art. For example, EP-A-699478 or EP-A-646414 disclose machines with vertically arranged rotor that bear grinding or polishing implements: rotors and implements are enveloped at a distance by a screen, which is in turn held in a perforated basket. The perforated basket is enveloped by a casing to prevent grinding or polishing products from exiting uncontrolled. The casing can consist of a solid jacket or exhibit holes for viewing windows. The rotor can also be designed as a hollow shaft, and exhibit smaller holes in the area of the implements to feed air and/or moist air and/or water into the processing area. In like manner, air slits in the hollow shafts can be directly allocated to the polishing tools, e.g., in the form of cams, and additionally exhibit active surfaces (US-PS 4829893). The air passes through the polishing material and screen, and the ground flour is siphoned out of the polishing material and carried away. The rotors can also be provided with combined implements, e.g., with husking and polishing elements, as disclosed in EP-A-427504. In order to remove the ground flour or polishing dust that exits the slits of the screen, the casing can most often be flipped open to relay the aspirated air. The disadvantage here is that the perforated baskets often exhibit ribs transverse to the airflow, the distance of the air conduction casing is in part very great, and the flow rate of the air passing through is low in such areas. Transverse webs can also generate leeward turbulences. The production of hollow shafts with a plurality of holes is expensive, and high pressure losses may arise due to the small hole cross sections, resulting in a reduced air throughput and/or more powerful fans. The object of the invention is to develop a polishing machine with which the described disadvantages of prior art can be avoided. In particular, a uniform rate of air flow between the screen and external air conduction casing is to be achieved on the one hand, and an increased polishing action relative to the throughput quantity of rice on the other. The object is achieved with the features in the patent claims. The respective subclaims disclose advantageous embodiments. A rotor exhibits a polishing implement with more than four, preferably six cams, wherein the rotor preferably rotates at a higher speed than usual. Depending on the corresponding performance required of such a polishing machine, the number of cams can also distinctly exceed that, e.g., measure 10 or 12 cams. It was shown that the maximum speed or circumferential velocity of the rotor or implement is limited relative to the justifiable grain breakage. Therefore, the number of polishing actions must be increased by finding an optimum ratio between the cam number, corner number of the screen and rotor speed. The perforated basket and external jacket casing each consist of two bent walls. The screen is preferably designed as half-shells each having more than four, preferably five corners, while the perforated basket preferably exhibits ribs that project outwardly toward the jacket casing. The corner number applies to the screen side in conjunction with the ribs. The screen sheathing can consist of rounded, bent half-shells. Both halves can be joined to form a supporting casing, e.g., with screws and spacer elements. Both ends of the jacket casing with perforated basket are sealed by cover plates. The gap between the screen and jacket casing is selected in such a way as to provide as uniform a nip for a uniform rate of airflow. The nip preferably expands increasingly from narrower to wider from the top of the screen (or opposite the aspiration point) to the aspiration point with aspirating funnel, making it better adapted to the throughput air quantity. Only a little air flows through at the top, or opposite the aspiration point, increasing toward the aspiration point. To achieve an optimal cleaning effect, the nip should be slowly ascending in design. It is particularly preferred that the ribs be provided with plug-in lugs and the casing walls with slits, so that the ribs are easy to position, and can be welded from outside, for example, enabling a stable screen fit relative to pressure and oscillations. Since the distance to the screen is also uniform, the rate of airflow in the processing chamber is about the same, and ground flour deposits are largely avoidable. The rotor is designed as a solid shaft or simple shaft (hollow shaft), preferably exhibits six cams on the polishing implement, and the air is preferably passed between the rotor and internal diameter of a feed screw for the polishing material and grinding or polishing implement, e.g., a cam implement. The air is preferably introduced prior to and independently of the product feed, and conducted in the working area. It is particularly preferred that the air get into the working area from both ends. Another object is to develop a method for polishing or grinding rice grains in particular, with which the gloss and fineness of the rice surface can be improved. The object is achieved with the features in claim 10 by having the rotor rotate at a higher speed in the working area of a polishing machine formed between a fixed screen and rotating rotor with a polishing implement, so that the number of polishing actions rises relative to a throughput rice quantity per kg. In addition to increasing the speed, use is also made of a polishing implement with a higher cam number. The method can be implemented in dry or wet conditions. The invention will be described in greater detail below in an exemplary embodiment based on a drawing. The drawing shows: Fig. la: a section of the working area of a polishing or grinding machine; Fig. lb: a section of the working area for a second embodiment; Fig. 2: a longitudinal section of the depiction on Fig. 1 Fig. 3: a longitudinal section of the rotor and screen arrangement of the polishing or grinding machine; Fig. 4: a cross section of the depiction on Fig. 3; Fig. 5: a cross section through a rotor with an elevated number of cams. The polishing machine depicted illustrates only the parts to be examined here, and exhibits a tubular rotor 1, which is fitted with the usual polishing implements 18, e.g., cams. In the polishing implement area, the rotor 1 is enveloped by an octagonal screen 2, which consists of two screen sheets 3 and 4. The screen 2 is in turn enveloped by a two-part perforated basket 5 in the form of a sheet jacket, which consists of two half-shells. Screen sheets 3, 4 and perforated basket 5 are joined by screwed connections 6 and spacer sheaths to form a self-supporting unit sealed at the ends with terminating sheets 7, 8. Situated between the screen 2 and perforated basket is a uniformly narrow nip 9, resulting in a uniform and high airflow rate that permits only a slight tendency of ground flour to deposit. The half-shells of the perforated basket 5 exhibit low, inwardly projecting ribs 10, which are advantageously provided with plug-in lugs. The half-shells of the perforated basket 5 preferably exhibit slits, so that the ribs with the plug-in lugs can be easily positioned and, for example, welded on from outside. The half-shells of the perorated basket 5 can also be bent without corners to avoid the adhesion of ground flour. In another embodiment, the number of corners of the polishing area (nip 9) is increased to ten, wherein both the screen sheets 3, 4 and the perforated basket 5 exhibit a corresponding number of corners. In this embodiment, the polishing implement on the rotor 1 exhibits six cams 23. The rotor speed is also increased to enhance the effect. The circumferential velocity measures at least 7.6 m/s, for example. Higher pressure peaks are generated in the polishing area, helping to generate the frictional forces required for the polishing process. The number of polishing and pressure actions per throughput rice quantity also increases, e.g., to approx. 500 per kg of rice at a capacity of 5 t/h. Linearly arranging at least two polishing machines makes it possible to further increase the number of polishing actions. Both embodiments yield a stable accommodation of the screen 2, which withstands high oscillation loads and pressures, and exhibits a uniform distance of approx. 20 mm between the screen sheets 3, 4 and perforated basket 5 from an upper air entry 11 for secondary air to a lower air outlet 12 with similar cross sections. The airflow rate can here measure approx. 20 m/s. Air can be passed through the channels 13, 14 and into the screen 2 from both sides. It passes form the channel 13 through an annular gap 15 between the rotor 1 and a feed screw 16 for the polishing material into the space between the rotor 1 and screen 2, and then streams through the gap 9 and polishing material. An underpressure prevails in the working area. The polishing implement 18 is spaced apart from the rotor by spokes 17, so that the air can flow through virtually unimpeded. The star-shaped polishing implement 18 is here pushed onto the rotor 1. The bearings 20 of the rotor 1 are sealed and isolated from the streaming air by simple gaskets 19. As a result, bearings are subject to very little contamination, since the bearings 20 do not contact the polishing material. The polishing material is introduced through a product inlet 21, conveyed by the feed screw 16 into the working area and there polished, and exits the polishing machine through a product outlet 22. As a rule, two air streams are passed through the working area. A first, large stream of air is passed through the polishing material and screen 2 to remove ground and polished flour, and a second air stream is passed from above through the perforated basket 5 (air inlet 11} outside the screen 2 to prevent deposition. At least the second air stream can be kept at a low quantity by the narrow gap 9, so that both the fan and separator can be appropriately compact in design. Reference List 1 Rotor 2 Screen 3 Screen sheet 4 Screen sheet 5 Perforated basket 6 Screw connection 7 Terminal sheet 8 Terminal sheet 9 Nip 10 Rib 11 Air inlet 12 Air outlet 13 Channel 14 Channel 15 Annular gap 16 Feed screw 17 Spoke 18 Polishing implement 19 Gasket 20 Bearing 21 Product inlet 22 Product outlet 23 Cam CLAIMS 1. A polishing machine for grinding or polishing the outer grain husks of rice or another cereal with a rotatably mounted rotor (1), which bears grinding and/or polishing and/or husking implements, enveloped by a screen (2) supported in a perforated basket, characterized in that the rotor (1) exhibits a polishing implement with more than four cams (23), and that the screen (2) consists ' of two screen sheets (3, 4) or two half-shells each with more than four corners, which are jointed by shared connecting elements at the separation points, wherein a uniform nip (9) is provided as the polishing area between the screen (2) and perforated basket (5). 2. The polishing machine according to claim 1, characterized in that the nip (9) measures approx. 15 to 25 mm. 3. The polishing machine according to claim 1 or 2, characterized in that the half-shells of the perforated basket (5) exhibit inwardly directed radial ribs (10), and are rounded with or without corners. 4. The polishing machine according to at least one of claims 1 to 3, characterized in that the rotor (1) further exhibits a feed screw (16) for the polishing material, characterized in that an annular gap (15) is provided between the rotor (1) and interior diameter of the feed screw (16). 5. The polishing machine according to claim 4, characterized in that a channel (13) is provided for feeding air in and through the annular gap (15) . 6. The polishing machine according to at least one of claims 1 to 5, characterized in that the rotor (1) is designed as a solid shaft or pipe, and has six cams (23) . 1 1. The polishing machine according to claim 1, characterized in that the screen (2) and perforated basket (5) are divided in an axial direction, and connected at the separation points, wherein the polishing area formed between them is more than octagonal. 8. The polishing machine according to claim 1, characterized in that the gap gets wider toward the aspiration point. 9. A method for polishing in particular rice grains in a working area formed between a rotatable rotor that carries a polishing implement and a fixed screen, wherein the rice grains in the working area are subject to grain-on-grain friction and exposed to the polishing implement, characterized in that the speed of the rotor is increased to the point where at least 500 polishing actions per kg of throughput rice are reached, which are generated by the cams located on the rotor and a rotational speed of the rotor of at least 7 m/s. |
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| Patent Number | 268306 | |||||||||
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| Indian Patent Application Number | 305/DELNP/2008 | |||||||||
| PG Journal Number | 35/2015 | |||||||||
| Publication Date | 28-Aug-2015 | |||||||||
| Grant Date | 25-Aug-2015 | |||||||||
| Date of Filing | 11-Jan-2008 | |||||||||
| Name of Patentee | BUHLER AG. | |||||||||
| Applicant Address | BAHNHOFSTRASSE, CH-9240 UZWIL, SWITZERLAND | |||||||||
Inventors:
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| PCT International Classification Number | B02B 3/04 | |||||||||
| PCT International Application Number | PCT/CH2005/000677 | |||||||||
| PCT International Filing date | 2005-11-15 | |||||||||
PCT Conventions:
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