Starscreen

Abstract: The invention relates to a star scalper for separating supplied material, comprising a number of parallel, rotatable shafts that are each equipped with a number of star bodies placed at a distance from each other, which bodies have a hub and radially protruding star fingers, in which the star bodies of each shaft extend between the star bodies of the adjacent shaft. According to the invention at least one star body is provided with a scraper, which scraper reaches to the hub of the adjacent star body.

Description: The invention relates to a, star scalper for separating supplied material, as described in the preamble of claim 1. Such a scaled is known from DE-U-8 116 786 . Another scalper is known for instance from NL-A-90.02165 and for instance meant for sifting waste, in which the waste has to be separated in a crude and fine fraction. There is a certain distance between the extremities of the fingers of the one star body on one shaft and the hub of the star wheels in between which the one star body has to rotate on the adjacent shaft, which distance together with the intermediate distance between two consecutive star bodies on the adjacent shaft determine a rectangular passage. Said rectangular passage is normative for the size of the objects which are let through by the star scalper. The star fingers of the star scalper move along each other with small intermediate distance. Usually the shafts of the star scalper all rotate in the same direction, so that the material moves over the scalper and the fraction which is left on the scalper is discharged. In this way it is also effected that an object which is too large for the passage will not block the passage, because in every passage a star body is present which makes an upward movement, so that the object is released. A disadvantage of the known star scalper is that fine material into the fine fraction may cake onto the hubs of the star bodies, as a result of which the effective passage is made narrower. In this way the sifting effect of the star scalper is reduced after some time. The star scalper also has to be cleansed regularly. FR-A-1.240.250 discloses an apparatus for cleaning agricultural products, having a plurality of parallel shafts with discs, and stationary comb-shaped scrapers between the discs for cleaning. In one embodiment, the apparatus is further provided with star-shaped wheels with scrapers, which work together with the stationary scrapers. It is an object of the invention to provide an improved star scalper. This object is achieved according to the invention with a star scalper as defined by claim 1. In this way it is effected that at each revolution of the star body with the scraper, the hub of the adjacent star body is at least partly cleansed, as a result of which caking of dirt and silting up of the passage is prevented. Because there is less pollution, less engine power is necessary during sifting, the star scalper has to be cleansed less often and the sifting fraction remains more regular. Preferably the scraper is arranged near the extremity of a star finger of the star body. In this way the scraper can remain small. The scraper is at least as wide as the thickness of the star finger. In this way a large part of the adjacent hub is cleansed. Preferably on one side of the star body the scraper continues until the star fingers of the adjacent star body. In this way these star fingers are at least partly cleansed as well. According to a preferred embodiment each star body is provided with a scraper, in which way all hubs are kept clean. Preferably all star bodies with scraper are identical, so that the star bodies can be economically manufactured. Preferably per rotatable shaft the scrapers of the star bodies are placed in a jumped manner, so that the scrapers on one shaft do not scrape all at a time along the hubs of the adjacent shaft. In this way the load of the shaft is more regular. According to a preferred embodiment the star fingers of the star body are flexible in axial direction. In this way the star fingers will not break off but be able to deflect when a hard object such as for instance a stone gets stuck in a slit between two consecutive star bodies. Preferably shafts that are adjacent to each other are always rotatable with a different number of revolutions, as a result of which the entire circumference of the hub is kept clean by the scraper. The invention also relates to a star body as defined in claim 8. According to a preferred embodiment of the star body the scraper is arranged near the extremity of a star finger, and preferably the fingers of the star body are flexible in axial direction. The invention will now be elucidated on the basis of a preferred embodiment, referring to the drawing. Figure 1 schematically shows a part of the star scalper according to the invention in top view. Figure 2 shows a part A of the star scalper according to figure 1 on a larger scale. Figure 3 shows a single star body of the star scalper according to figure 1 on a larger scale. Figure 1 shows the top view of a part of a star scalper 1 with parallel shafts 2 arranged at equal distances and on each shaft 2 a great number of star bodies 3. A part A of figure 1 is shown on a larger scale in figure 2. Figure 2 shows some star bodies 3 which each consist of a hub 5 with a number of star fingers 4 which are not shown separately. On one of the star fingers 4 of each star body 3 a scraper 6 has been arranged. Figure 3 shows a view in perspective of one star body 3 with a hub 5, a number of star fingers 4, and a scraper 6. In the hub 5 a square hole 7 has been arranged in order to be able to arrange the star wheel 3 locked against rotation on a square shaft 2. As is shown in figures 2 and 3 the scraper 6 protrudes radially and to one side axially. The scraper 6 can only protrude axially to one side, in order not to collide with the scraper on the adjacent star body. When using the star scalper 1 the scraper 6 will always scrape the hubs of the star bodies on the adjacent shaft, so that no material can attach itself there. The scraper 6 scrapes along the major part of the width of the hubs of the star bodies in between which the scraper 6 moves, and the scraper 6 also scrapes along one side of the fingers 4 of an adjacent star body. Thus the major part of the passage between the hubs and the star fingers is kept free, and because the shafts 2 of the star scalper 1 rotate at mutual different speeds, the entire circumference of the hubs 5 is kept clean by the scraper 6. By arranging the star bodies 3 on one shaft 2, as seen in relation to the scraper 6, turned one to the other a quarter of a turn around the shaft 2, a quarter of the number of scrapers 6 at a time will scrape along the hubs of the star bodies of the adjacent shaft 2, as a result of which the load of the driving of the shafts 2 is more even. With the star scalper according to the invention all star bodies 3 with a scraper 6 are identical, as a result of which the costs of manufacturing of a star body 3 with scraper 6 are not significantly higher than the costs of manufacturing a star body 3 without scraper. Preferably the star fingers 4 of the star body 3 are flexible in axial direction, as a result of which the star fingers 4 will not break off but will deflect when for instance a hard object gets stuck in the intermediate space between two star bodies 3 moving along each other. It is possible to place a close fitting steel bush over two hubs 5 that are adjacent to each other. It will be understood that the scrapers will then be active on the surface of the bush.

Claims: Star scalper for separating supplied material, comprising a number of parallel, rotatable shafts (2) that are each equipped with a number of bodies (3) placed at a distance from each other, which bodies have a hub (5), in which all the bodies are star bodies having radially protruding star fingers (4), in which the star bodies of each shaft extend between the star bodies of the adjacent shaft, and in which each star body is provided with a scraper (6), which scraper reaches to the hub of an adjacent star body of said adjacent shaft, in which the scraper (6) is at least as wide as the thickness of the star finger (4), characterised in that all scrapers (6) protrude axially from the scraper fingers (4) in a common direction only. Star scalper according to claim 1, in which on one side of the star body (3) the scraper (6) continues until the star fingers (4) of the adjacent star body. Star scalper according to claim 1 or 2, in which the scraper (6) is arranged near the extremity of a star finger (4) of the star body (3). Star scalper according to any one of then preceding claims, in which all star bodies (3) are identical. Star scalper according to claim 4, in which per rotatable shaft the scrapers of the star bodies are placed in a jumped manner. Star scalper according to any one of the preceding claims, in which the star fingers (4) of the star body (3) are flexible in axial direction. Star scalper according to any one of the preceding claims, in which shafts (2) that are adjacent to each other are always rotatable with a different number of revolutions. Star body (3) for a star scalper (1) according to any one of the preceding claims, comprising a hub (5) with an aperture (7) for attachment on a shaft of the star scalper and a number of radially protruding star fingers (4), wherein a scraper (6) is arranged at the extremity of one of the star fingers (4) to scrape along the hub of a star body on an adjacent shaft of the star scalper, characterised in that the scraper (6) extends from the star finger (4) in only one axial direction.

Inventors: SWANINK GERARDUS CORNELIS PETR, SWANINK, GERARDUS CORNELIS PETRUS MARIA
Applicants: BOLLEGRAAF BEHEER APPINGEDAM B, BOLLEGRAAF BEHEER APPINGEDAM B.V.
Application year: 1998
Main classification: B07B1
IPC codes: B07B1