Patent GB-768092-A (GB)
Title: Apparatus and method for burnishing articles
IPC: B24B31/12
Filed: 1954-04-13
Abstract: 768.092. Tumbling ROLL BRITE CORPORATION. April 13, 1954 [April 14, 1953], No. 10871/54. Class 60 Articles, such as aluminium die castings, are burnished in a tumbling barrel A, preferably polygonal in cross-section, rotating about a horizontal axis. The barrel has a closed end 1 bolted to a plate 2 secured on a shaft 3 journalled in bearings and driven through toothed gearing and belt and pulley gearing from an electric motor. The barrel has an opening 16 in. its side wall for the charging of the barrel with tumbling balls and water or other suitable liquid, the opening being provided with a door 17 held in closed position by swing bolts 18. A rack-supporting shaft 10, preferably hollow for lightness, is rigidly mounted at one end on the end wall 1; the shaft is coaxial with the barrel, and its free end registers with a recess 12 on the inner surface of an end cover 13 provided with handles 15 and clamped on the end of the barrel by swing bolts 14. The articles to be burnished are mounted, outside the barrel, on a rack B which has a central tubular body section 19 of a diameter slightly greater than that of the shaft 10 and of a length approximately equal to the distance betwen the end 1 and cover 13 of the barrel. A rack designed for supporting aluminium nozzles C for vacuum cleaners has four pairs of radial posts 20 rigidly mounted on the body section, the posts of each pair being spaced apart longitudinally. On each pair of posts are two rails 21 spaced apart radially of the body section. On each rail are secured brackets 22, one for each of the articles C. Each bracket comprises a main tubular cylindrical portion 23 of a diameter to fit a socket D in the article C, the portion 23 having a leg 24 bolted to the rail 21; the portion 23 has a screw-threaded opening 24a receiving a screw 25 between the head of which and the base of a recess E in the article is a washer 26. For supporting the rack during the mounting of the articles thereon and transporting the rack to the barrel, a wheeled carriage F is provided, including a 'base frame G having a vertical post H from which projects a horizontal arm I of a diameter less than the diameter of the body section 19 of the rack. During mounting of the articles on the rack, the latter is supported on the arm I; a clamping screw J may be used to hold the rack against rotation on the arm. When it is desired to place the articles in the barrel the end cover 13 of the barrel is removed and the carriage F is moved to bring the arm I into axial alignment with the shaft 10 of the barrel, whereupon the rack is slid off the arm I and on to the shaft 10; the end cover 13 of the barrel is then clamped in barrel-dosing position. The door 17 is removed from the opening 16 with the latter disposed above the horizontal diametral plan of the barrel, and the material such as metal shot or polishing balls 27 to be used for burnishing the articles C poured into the barrel in sufficient quantity to completely embed the articles that are below the horizontal diametral plane of the barrel; enough water or other suitable liquid is then poured through the opening 16 to bring the level of the liquid 28 substantially above the horizontal diametral plane of the barrel, and the door 17 is clamped in posi-, tion to close the opening 16. The barrel is then rotated at between ten to thirty revolutions per minute. The rack, may rotate relatively to the barrel shaft 10; proferably, however, one end of the central body section of the rack has a lug 29 rigidly secured thereon and interposed between two adjacent nuts 30 on the bolts that fasten the shaft 10 to the solid end wall 1 of the barrel, so as to cause the rack to rotate with the shaft 10. After completion of the burnishing operation, end cover 13 of the barrel is loosened to permit the liquid to flow out into a receptacle; the shot may or may not be removed. The end cover is removed from the barrel and the rack slid off the shaft 10. Where the articles are to be subjected to subsequent treatments such as washing and drying, the body section 19 of the rack is formed at one or both ends with transverse openings 31 through which a pin 32 may be inserted to support a hook or eye 33 by which the rack may be attached to the hook 34 of a hoisting apparatus 35. After the rack has been entirely disengaged from the barrel shaft 10 it may be hoisted and then dipped into a washing tank 36 and then removed from the tank and transported to a drying atmosphere; the rack may be rapidly spun about the axis of the hook 34 to cause throwoff of the liquid by centrifugal action. When it is not desired to subject the articles to washing, dipping or like operations the rack is slid from the barrel shaft directly on to the arm I of the carriage F. Racks of different structure for supporting different articles can be interchangeably used, each rack having a central tubular body like the section 19.