Patent GB-837402-A (GB)
Title: Sanding machine
IPC: B24B21/12
Filed: 1958-12-16
Abstract: 837,402. Sanding. PENDERGAST, R. F. Dec. 16, 1958, No. 40589/58. Class 60. A workpiece is fed through a sanding machine by means including a power driven feed roller and is sanded by an endless belt travelling around contact and idler rolls mounted at opposite ends of a rocking frame pivoted about an axis parallel to that of the feed roller, the frame being biassed to urge the contact roll towards the feed roll. Steel support rolls 7, 8, 10, 10 and a rubber covered feed roller 22 are journalled in the side members 3, 4 of the machine frame. The roller 22 is driven through belt 30 by a motor 27 with built-in speed reduction gearing, and rolls 7, 8 are driven through belts 33, 34 from the shaft of the roller 22. Hold-down rolls 13, 13 with adjustable spring loading co-operate with the rolls 7, 8. An endless sanding belt 53, comprising abrasive adhered to a paper backing, passes around a contact roll 41, preferably rubber covered, and an idler roll 44 mounted at opposite ends of a rocking frame 35. The frame comprises side elements 36, 37, a cross bar 38 and transverse brace bars 39, 40. The frame is mounted for pivoted movement about an axis parallel to those of the feed roller 22 and contact roll 41 by a relatively large diameter primary pivot element 54 journalled in a fixed bracket 55 secured to the upper edge of the side member 3 of the machine frame, and a smaller diameter secondary pivot shaft 56 mounted in a bracket 57 vertically adjustable, by a screw 59, in a guide frame 58 secured to the side member 4 of the machine frame. To permit raising and lowering of the bracket 57 a self-aligning bearing is interposed between the primary pivot shaft 54 and its bearing bracket 55. The secondary pivot shaft 56 is removable from engagement with the side member 37 of the rocking frame 35 and the bracket 57 to facilitate removal of the sanding belt 53. The contact roll 41 is journalled in the side elements 36, 37 of the rocking frame 35 and its shaft carries a multiple sheave 66 connected by belts 67 with a multiple sheave section 65 of a pulley 63 rotatably mounted on the primary pivot element 54 ; the pulley 63 also has a sheave section 64 connected by a belt 68 with a pulley 69 on the shaft of a motor 61. The sanding belt runs at 3,000-6,000 linear ft./min. The idler roll 44 is journalled in supporting arms 46, 46 of a yoke 47 secured to the cross bar 38 by a bolt 48 about which it can pivot, the pivoted movement being limited by a pin 50 carried by the cross bar 38 and located within an arcuate slot 49 in the yoke 47. A compression spring 51 is interposed between the end of the yoke 47 and the adjacent end of the brace bar 40 ; an adjusting screw 52 carried by the other end of the brace bar 40 bears against the other end of the yoke 47, to effect proper tracking of the belt 53 over the rolls 41, 44. Lateral shift of the belt 53 owing to unbalanced conditions during sanding is counteracted by means similar to that in U.S.A. Specification 2,813,382 and comprising elongated pulleys 79, 79 ; each pulley 79 is journalled on one leg of a bracket 80 pivotally secured by a bolt 81 to a lug 82 secured to one side element of the rocking frame. Each bracket 80 has a projecting stem 83 on which is mounted a counter balance weight 84. Gravity bias is imparted to the rocking frame 35 by weights 71, 71 adjustably secured along rods 72 carried by legs 73, 74 secured to the side elements 36, 37 of the rocking frame. The legs 73, 74 may alternatively project laterally from the side elements 36, 37. Downward movement of the contact roll 41 is limited by stop screws 76 threaded through lugs 77 on the side elements 36, 37 and abutting lugs 78 projecting rearwardly from brackets 16 which carry the front holddown roll 13.