BULK PRODUCT STABILIZING BELT CONVEYOR

Abstract: A bulk product stabilization conveyor (10) is described having a continuous-length wide belt (30) extending in an upper flight (44) and in a lower flight (46) between an infeed end (32) and an outfeed end (34). The outfeed end (34) is elevationally below the infeed end (32) and the distance between the infeed end (32) and outfeed end (34) is such that the upper flight (44) is slack with the upper flight forming a dynamic catenary profile as it is being driven at a high velocity in excess of 400 feet per minute and preferably between 400-800 feet per minute. The upper flight (44) has an inclined downward and forward section (52) adjacent the infeed end that has an inclination of between 30 and 45 degrees to initially receive a wide swath of articles from an article feeder (14). The upper flight (44) has an intermediate section (54) with a progressively decreasing radius of curvatures to progressively apply an increasing centrifugal force on the articles to stabilize the articles on the high velocity upper flight. The upper flight (44) has an inclined upward section (56) adjacent the outfeed end (34) to propel the articles from the outfeed end to an optical inspection station (36) with an upward and forward trajectory (68).

Description: DESCRIPTION BULK PRODUCT STABILIZING BELT CONVEYOR Technical Field This invention relates to continuous-length high speed belt conveyors for conveying bulk products or articles and particularly those belt conveyors having features for stabilizing the articles on the conveyor to prevent the articles from moving relative to the belt as the articles are being presented to optical inspection equipment for determining optical properties of the articles, such as blemishes and other imperfections. Background Art Over the years, optical inspection equipment has been devised to automatically optically inspect each article in a mass of articles passing an inspection station. One such very effective system is described in U .S. Patent No. 4,581,632 granted in 1986 (reissued on September 25, 1990 as RE 33,357) . In such systems, it is not uncommon to utilize high speed conveyor belts of up to seventy-two inches in width to convey a wide swath of the articles past such automatic optical inspection equipment. To obtain the optimum benefits of high speed optical equipment and to increase the effectiveness and accuracy of the inspection, it is highly desirable to maintain each article relatively stationary with respect to adjacent articles, even though the articles are moving in mass at high velocities. Such an "article stabilized condition", is particularly important, if not mandatory, when high speed sorting equipment is associated with the optical inspection equipment to sort the articles based on the results of the optical inspection, such as optically recognizable defects. It is important that each article maintain its relative position during the inspection and sorting process. The problem becomes quite difficult when the articles are dropped onto the infeed end of a high speed conveyor at a relatively slow forward velocity from a shaker feeder that is designed to evenly distribute the articles laterally and longitudinally and then propel the articles from the feeder in a wide swath. When articles to be inspected exit a feeder and drop onto a high speed conveyor, the articles, because of the large difference between their velocity and the velocity of the conveyor, tend to bounce and slide or roll longitudinally as well as transversely relative to the conveyor and relative to each other. Several solutions to the problem have been suggested in the W. Sheldon Ferguson et al. U.S. Patent No. 4,830,180 granted May 16, 1989 and the John H . Wilbur et al U .S. Patent No. 5,048,674 granted September 17, 1991. Both patents describe roller mechanisms overlying the high speed conveyor that are rotating at about the same tangential speed of the conveyor to bias the articles into firm contact with the conveyor to quickly "stabilize" the articles on the high speed conveyor. Although such roller stabilizers have been reasonably successful, they have to be adjusted and cleaned frequently. Also it is not uncommon for the articles to stick to the rollers causing injury to the articles and providing irregular results. One of the objectives and advantages of this invention is to greatly simplify the stabilization process without having to engage the articles to force the articles to become stationary on the high speed belt. An additional objective and advantage of this invention is to provide a unique high speed conveyor that incorporates within itself the ability to stabilize the articles even though the articles are being fed to the high speed conveyor by slow speed feeders such as shaker feeders. A further object and advantage of this invention is to provide a unique high speed conveyor that minimizes damage or spillage of the articles, particularly fragile vegetables, even though the articles are accelerated from a low speed to a high speed very rapidly. These and other objects and advantages of this invention will become apparent upon careful consideration of a description of a preferred embodiment as set forth in the following sections including the claims. Brief Description of the Drawings A preferred embodiment of the invention is described below with reference to the accompanying schematic side view drawing of a high speed continuous length belt conveyor that receives bulk products from a shaker feeder and stabilizes the articles on the conveyor and conveys the articles in their stabilized condition at high speeds to an optical inspection and sorting station. Best Modes for Carrying Out the Invention and Disclosure of Invention A preferred embodiment of a bulk product stabilizing belt conveyor is illustrated in the drawing and is generally designated with the numeral 10. The conveyor 10 is designed to (1) receive bulk articles 12 fed in a wide swath from a low velocity bulk feeder 14, such as a feed shaker; (2) stabilize the articles on the belt conveyor; and (3) convey the articles at a high velocity individually past an optical inspection station 36 and possibly a sorting station 38. The bulk feeder 14, such as a feed shaker, generally spreads the articles out both laterally and longitudinally into a single layer having a wide swath. The bulk feeder 14 has a discharge end 16 that discharges the articles in a wide swath from the feeder 14 into free flight toward the conveyor 10 at a low horizontal velocity of 200 feet per minute or less. The free flight trajectory of the articles 12 discharged from the feeder 14 is designated with the numeral 18. The conveyor 10 has a wide continuous-length belt 30. Preferably, the belt 30 varies in width from twelve inches to seventy-four inches to receive the wide swath of articles discharged from the feeder 14. The belt 30 extends between an infeed end adjacent the discharge end 16 of the feeder 14 and an outfeed end 34 adjacent the optical inspection station 36. The belt 30 is supported on a drive roller 40 at the infeed end 32 and an idler roller or nose bar 42 at the outfeed end 34 that define a belt upper flight 44 and a return lower flight 46 extending therebetween. The belt 30 is driven at a high velocity, greater than 400 feet per minute, by a drive 48 attached to the drive roller 40. Preferably, the upper flight 44 is driven at a belt speed of between 400 and 800 feet per minute. It is preferable that the belt 30 is driven from the drive roller 40 at the infeed end 32 rather than from the outfeed end 34. Importantly, the outfeed end 34 is positioned at an elevation below that of the infeed end 32 and is positioned sufficiently close to the infeed end 32 to generate slack in the upper flight 44 to cause the upper flight to droop in a general catenary profile between the infeed end 32 and the outfeed end 34 as illustrated in the drawing. The precise profile of the upper flight will be modified by the centrifugal force that is exerted on the upper flight as it passes at a high velocity between the infeed end 32 and the outfeed end. For purposes of description, such modified profile will be referred to as "dynamic catenary profile". More specifically, the upper flight 44 has an article receiving section 52 adjacent the infeed end 32 that extends downward and forward, a curved intermediate section 54, and an inclined upward section 56 that extends inclined upward and forward adjacent the outfeed end 34. Preferably the article receiving section 52 is inclined downward and forward at an angle of between 30 and 45 degrees from horizontal for initially receiving the articles to minimize article turbulence such as bouncing, tumbling and rolling on the belt. The curved intermediate section 54 has a progressively decreasing radius of curvature to progressively increase centrifugal forces applied to the articles to cause the articles to remain stationary or stabilized on the belt and not to move relative to the adjacent articles as the articles are conveyed to the outfeed end 34. The upper flight 44 has a trough portion 58 that is elevationally below that of the outfeed end 34. The inclined upward section 56 extends upward and forward at a rather shallow angle to provide a small upward velocity vector on the articles 12 to assist in the separation and gentle transfer of the stabilized articles 12 as the articles are propelled into free flight past the optical inspection station 36 and the sorting station 38. To adjust the relative positions of the infeed end 32 and the outfeed end 34, horizontal adjustments 62 and vertical adjustments 64 are connected to at least the outfeed end. Such adjustments enable the operator to adjust the contour, particularly the radii of curvatures of the upper flight, to accommodate various products, speed, product volume and other variables. Additionally, a torque control mechanism 66 may be attached to the idler roller 42 to control the tension and slack on the upper and lower belt flights 44, 46. Additionally, the conveyor 10 is positioned relative to the discharge end 16 of the feeder 14 or relative to the trajectory 18 of the articles 12 so that the angle of the receiving section 52 more closely coincides with the trajectory angle of the articles. Such a feature minimizes bouncing and article turbulence upon initial contact of the articles on the upper flight 44 of the conveyor 10. Further, the infeed end 32 of the conveyor 10 is positioned sufficiently below and underneath the discharge end 16 so that the articles 12 in free flight in the trajectory 18 are given sufficient time to accelerate by gravity to a velocity that more nearly approximates the velocity of the upper flight 44. It is desirable for the infeed end 32 to be elevated sufficiently below the discharge 16 so that the articles are given an opponunity to accelerate during free flight by the forces of gravity to velocities greater than three-quarters that of the velocity of the upper flight before engaging the inclined section 52. Such a feature appears to significantly reduce the initial article turbulence on the belt. The above features provide a rather inexpensive conveyor that is able to quickly and efficiently stabilize the articles on the conveyor while being able to transport the articles at very high volumes and speeds to the optical inspection and sorting stations. It is anticipated that such a conveyor 10 will be able to provide for accurate sorting of between 6,000 and 60,000 lbs. per hour depending upon the product.

Claims: CLAIMS 1. A high speed continuous-length belt conveyor for stabilizing a wide swath of articles on the conveyor and conveying the stabilized articles along the conveyor at high speeds, comprising: an elongated wide continuous-length belt extending horizontally between an infeed end and an outfeed end and having an upper belt flight for ( 1) initially receiving the articles in a wide swath from an article feeder adjacent the infeed end, (2) stabilizing the articles on the upper flight between the infeed end and the outfeed end, and (3) launching the stabilized articles from the upper belt flight at the outfeed end; a high speed belt drive operatively connected to at least one of the ends for moving the upper flight at a high forward velocity between the infeed end and the outfeed end; and wherein the infeed end and outfeed end of the belt conveyor are positioned with the outfeed end being at a lower elevation than the infeed end, and wherein the outfeed end and infeed end are sufficiently close together to provide sufficient slack in the upper flight to cause the high velocity upper flight to curve downwardly and forwardly between the infeed end and the outfeed end to generate sufficient centrifugal forces on the articles to stabilize the articles on the upper flight and prevent the wide swath of articles from moving relative to each other. 2. The high speed continuous-length conveyor as defined in claim 1 wherein the slack upper flight of the belt has an intermediate section that is elevationally lower than the upper flight at the outfeed end. 3. The high speed continuous-length conveyor as defined in claim 1 wherein the upper flight has a section adjacent the infeed end that has a slope of between 30 and 45 degrees for initially receiving the articles on the upper flight. 4. The high speed continuous-length conveyor as defined in claim 1 wherein the upper flight has a curved intermediate section between the infeed end and the outfeed end that has a progressively decreasing radius of curvature as the intermediate section extends toward the outfeed end. 5. The high speed continuous-length conveyor as defined in claim 1 wherein the upper flight is essentially unsupported between the infeed end and the outfeed end forming a dynamic catenary profile therebetween with a section of the upper flight at a lower elevation than a section at the outfeed end. 6. The high speed continuous-length conveyor as defined in claim 1 wherein the upper flight of the belt is driven at the high velocity from the infeed end. 7. The high speed continuous-length conveyor as defined in claim 1 wherein the upper flight of the belt has an upward inclined section adjacent the outfeed end to propel the articles from the outfeed end with an initial vertical velocity component to facilitate the separation of the stabilized articles from the upper flight. 8. The high speed continuous-length conveyor as defined in claim 1 wherein the articles are ejected onto the upper flight adjacent the infeed end with a forward and downward trajectory and wherein the upper flight has a receiving section adjacent the infeed end that is inclined downward and forward for initially receiving the ejected articles to minimize bouncing. 9. The high speed continuous-length conveyor as defined in claim 8 wherein the upper flight of the belt is driven at a preset high velocity and wherein the articles are initially ejected toward the upper flight at a prescribed feed elevation with a horizontal velocity less than one-half of the velocity of the upper flight and wherein the infeed end is positioned relative to the prescribed feed elevation a distance sufficient to permit the articles to accelerate in free flight by gravity to a velocity greater than three-quarter that of the preset high velocity of the upper flight prior to engaging the inclined receiving section of the upper flight to minimize article turbulence on the upper flight. 10. The high speed continuous-length conveyor as defined in claim 9 wherein the receiving section of the upper flight is inclined at an angle of between 30 and 45 degrees. 11. A high speed continuous-length belt conveyor for ( 1) receiving a wide swath of articles fed to the conveyor in free flight from an article feeder at a prescribed elevation and at an initial prescribed low horizontal velocity, (2) stabilizing the wide swath of articles on the conveyor, and (3) conveying the stabilized articles along the conveyor at a high velocity, comprising: an elongated wide continuous-length belt extending horizontally between an infeed end and an outfeed end and having an upper belt flight for ( 1) initially receiving the articles in a wide swath from an article feeder adjacent the infeed end, (2) stabilizing the articles on the upper flight between the infeed end and the outfeed end, and (3) launching the stabilized articles from the upper belt flight at the outfeed end; a high speed belt drive operatively connected to at least one of the ends to move the upper flight at a high forward velocity greater than twice the low horizontal initial velocity of the articles fed from the article feeder, between the infeed end and the outfeed end; wherein the upper flight has a receiving section adjacent the infeed end that is inclined downward and forward for initially receiving the ejected articles; and wherein the infeed end is positioned relative to the prescribed feed elevation a distance sufficient to permit the articles to accelerate in free flight by gravity to a velocity sufficient to engage the inclined receiving section of the upper flight with minimum article turbulence. 12. The high speed continuous-length conveyor as defined in claim 11 wherein the infeed end and outfeed end of the belt conveyor are positioned with the outfeed end being at a lower elevation than the infeed end and wherein the outfeed end and infeed end are sufficiently close together to provide sufficient slack in the upper flight to cause the high velocity upper flight to curve downwardly and forwardly between the infeed end and the outfeed end to generate sufficient centrifugal forces on the articles to stabilize the articles on the upper flight and prevent the wide swath of articles from moving relative to each other 13. The high speed continuous-length conveyor as defined in claim 12 wherein the slack upper flight of the belt has an intermediate section that is elevationally lower than the upper flight at the outfeed end. 14. The high speed continuous-length conveyor as defined in claim 12 wherein the inclined downward section of the upper flight has a slope of between 30 and 45 degrees for initially receiving the articles on the upper flight. 15. The high speed continuous-length conveyor as defined in claim 13 wherein the upper flight has a curved intermediate section between the infeed end and the outfeed end that has a progressively decreasing radius of curvature as the intermediate section extends toward the outfeed end. 16. The high speed continuous-length conveyor as defined in claim 13 wherein the upper flight is essentially unsupported between the infeed end and the outfeed end forming a dynamic catenary profile therebetween with a section of the upper flight at a lower elevation than a section at the outfeed end. 17. The high speed continuous-length conveyor as defined in claim 12 wherein the upper flight of the belt is driven at the high velocity from the infeed end. 18. The high speed continuous-length conveyor as defined in claim 13 wherein the upper flight of the belt has an upward inclined section adjacent the outfeed end to propel the articles from the outfeed end with an initial vertical velocity component to facilitate the separation of the stabilized articles from the upper flight. 19. A high speed, wide swath continuous-length belt conveyor for ( 1) receiving a wide swath of articles fed from a low speed article feeder, (2) stabilizing a wide swath of articles on the conveyor, and (3) conveying the stabilized articles along the conveyor at high speeds to an article inspection and sorting station, comprising: an elongated wide continuous-length belt extending horizontally between an infeed end adjacent the low speed article feeder and an outfeed end adjacent the inspection and sorting station; said belt having an upper belt flight for ( 1) initially receiving the articles in a wide swath from the article feeder adjacent the infeed end, (2) stabilizing the articles on the upper flight between the infeed end and the outfeed end, and (3) launching the stabilized articles from the upper belt flight at the outfeed end in a free flight path to the inspection and sorting station; a high speed belt drive operatively connected to at least one of the ends for moving the upper flight at a high forward velocity between the infeed end and the outfeed end; and wherein the infeed end and outfeed end of the belt conveyor are positioned with the outfeed end being at a lower elevation than the infeed end and wherein the outfeed end and infeed end are sufficiently close together to provide sufficient slack in the upper flight to cause the high velocity upper flight to curve downwardly and forwardly between the infeed end and the outfeed end to generate sufficient centrifugal forces on the articles to stabilize the articles on the upper flight and to prevent the wide swath of articles from moving relative to each other in free flight to the inspection and sorting station. 20. The high speed continuous-length conveyor as defined in claim 19 wherein the upper flight of the belt has an upward inclined section adjacent the outfeed end to propel the articles in free flight from the outfeed end with an initial vertical velocity component to facilitate the separation of the stabilized articles from the upper flight.

Inventors: HAIMBERGER HANS, SANCHEZ RODOLFO, HAIMBERGER, HANS, SANCHEZ, RODOLFO
Applicants: KEY TECHNOLOGY INC, KEY TECHNOLOGY, INC.
Application year: 1996
Main classification: B65G
IPC codes: B07C5, B65G31, B65G47