1. Field of the Invention
The present invention relates to a belt cleaner for removing the leavings of conveying material, e.g. coke, stuck on the surface of a conveyor belt during the return movement of the belt.
2. Description of Related Art
A prior art cleaner for a conveyor belt is disclosed in U.S. Pat. No. 3,841,470 wherein the belt cleaner includes a plurality of cleaner means disposed thereon in the transverse direction of the conveyor belt at the return running side thereof. Each cleaner means has a scraping portion thereof which intends to come into contact with the belt surface, while all of which are arranged in linear relationship. More specifically, said cleaner means which includes a scraper having said scraping portion formed with a tip member at uppermost end thereof is yieldingly supported by a resilient member so that the scraping portion thereof becomes in contact with the belt surface under pressure by the resilience of said resilient member.
It is known that an endless conveyor belt, which is fitted for running in a circle between a drive pulley and an idler pulley, is supported on the forward running side thereof by a plurality of guide rollers arranged at “trough” angles so as to be curved in an arcuate shape in cross section in order to carry the transferring material in a stable manner. In other words, on the forward running side of the belt where the material is transferred forward, the belt is supported so that the lengthwisely extending central region thereof can arcuately be deflected downward. The transferring materials are consecutively transferred generally on the central region of the belt, which will result in intensive wear on the central region of the belt surface rather than on both side regions of the same.
Because of the tendency to deflection (termed generally as a “trough” tendency), the belt is deflected arcuately upward on the return running side of the belt where the belt runs backward after discharging the transferring material therefrom. In such an arrangement of the known cleaner, the scraping portions of the cleaner means arranged in linear relationship are prevented from matching the belt surface when coming into close contact with the same. More specifically, there is a clearance between the scraping portions arranged linearly and the central region of the belt surface. The clearance becomes greater when the amount of wear on the central region of the belt surface is increased. Consequently, the leavings of material on the central region of the belt surface cannot positively be scraped off by the scraping portions of the cleaner. Since the leavings of material adhered to the belt are substantially greater in amount at the lengthwisely extending central region of the belt surface than the side regions of the same, some of the scraping portions disposed in the center get worn intensively in proportion to the amount of scraped material. This allows said clearance to become greater gradually.
Under the circumstances, an improved type of belt cleaner was developed by Nippon Tsusho Kabushiki Kaisha under the product name “U-Type Cleaner” to which some patents were granted as shown in the following patent documents.
Patent document 1: JP-H2-50009B (corresponding to EP0289659B1)
Patent document 2: JP-H5-65407B (corresponding to EP0338118B1)
Patent document 3: JP-H7-20766B
Patent document 4: JP-H11-35135A (corresponding to EP0891934B1)