Patent GB-656686-A (GB)
Title: Improvements in method and apparatus for smoothing and polishing workpieces
IPC: B24D9/00
Filed: 1948-10-18
Abstract: 656,686. Grinding, polishing and burnushing thread spools. THORNTON, A. A. (Nash Co., J. M.). Oct. 18, 1948, No. 27014. [Class 60] A method of smoothing and polishing flanged workpieces of fibrous material, such as thread spools with wooden or pressed fibre heads, includes rotating the workpiece while smoothing the surface thereof by abrasion 'and subsequently polishing such smoothed surface by engaging same with a flexible, non-abrasive material during rotation. The workpiece may also be burnished by a hard surface in pressure engagement therewith during rotation. A machine comprises a headstock 11 and tailstock 12 mounted on a turret shaft 10 slowly rotated from motor 13 through belt drive 14 and double worm gear reduction 15. The headstock 11 carries live spindles 16 having pulleys 16<SP>1</SP> driven by belt 17 ;passing circuitously about the pulleys remote from idler pulley 18 and driving pulley 19, the shaft 20 of the latter being driven from the motor 13 by belt 14. During rotation of the turret, the spindle-driving pulley arriving at the loading station A passes out of contact with the belt 17; rotation of the spindle is arrested by a brake shoe 21 operating on the pulley. The tailstock 12 carries dead spindles 23 biassed towards the spindles 16 but having cam followers 24 which in the course of turret rotation, engage stationary cam member 25 to retract successive dead spindles; this allows the release of the respective finished workpieces and as the turret continues to revolve, a fresh workpiece is picked up from supports 26 at loading station A in which it has been placed by the operator A bar 31 suspended by links 30 at the rear of the machine carries a sub-frame comprising arms 32 connected by tie rod 33 at their lower ends and curved forwardly at their upper ends. The sub-frame can be swung about the bar 31, to an inoperative position. The sub-frame is locked in its operative position by means allowing lateral reciprocation of the sub-frame; a cross bar 400, Figs. 10, 11, on the sub-frame is reciprocably confined by rear guide members 97, fixed on arms 98 projecting from standards 99 of the main frame, and coacting guide members 100 mounted on arms 98 and yieldable thereon under compression of spring 101; the guide members 100 are oscillatable on the arms 98 from operative to inoperative position, and are connected by link 102 pivoted to one guide member at 103, and pivoted to the other guide member 100 upon a clamp bolt 104 having a handle 105 by means of which the eye 106 at the end of link 102 may be clamped to member 100 or released. To effect lateral reciprocation of the subframe, one link 30 is provided with a bell crank arm 28 slotted to receive a connection, adjustable as to radius, with a pitman arm 34 reciprocated by eccentric 35 on shaft 36 which is an intermediate shaft in the double worm gear reduction 15. The upper ends of the arms 32 of the sub-frame are cross-connected bv bars 40 which support smoothing and polishing webs and guides therefor. The smoothing webs 41 comprise paper and fabric with abrasive grains on the surface, and are scored to facilitate their folding along desired lines. The polishing web 41a comprises a fabric such as burlap. The webs 41, 41a are in rolls 42 carried by arm extensions 43 and rods 44. Each cross bar 40 has a bracket 50 clamped thereto which includes a guide surface 51 engaging the back of the web adjacent a right angle. fold 45 therein. The web is held releasably to such surface by an eccentrically mounted clamping disc 52 freely rotatable, by the operator, on a headed pintle 53. The pintle has a shoulder 54 clampingly engaged with an eccentric disc 55 whereby such disc is held to clamping surface 56 of bracket arm 57 under pressure provided by nut 58 on the threaded end of pintle 53; the disc is set to any desired position to form a channel in polishing web 41a or to fit within the channel formed in web 41 by the prescored creases. A guide rod 59, passing through a transverse bore in the pintle 53, carries a finger 60 lying behind the channel of the web to hold it properly fitted about the forming disc 55; the guide rod 59 also has a finger 61 engaging the disc 55 so that the guide rod 59 is self-adjusting to provide the desired backing support between finger 60 and the web. Immediately below each of the bars 40,. the space between the sub-frame arms 32 is spanned by pintle rods 64 which support pads for backing the webs. A wide pad 65 is flanked by narrower pads 66, 67; each pad comprises a head 68 supporting broom corn 69 covered with a sheet of sponge rubber 70; pressure is obtained by the resilience of the broom corn and by adjustment of set screws 71 threaded through the bracket 70. The channels formed in the webs are accommodated by the space between the central pad 65 and the side pads 66, 67, the broad surface of the web between the channels being supported on the resiliently yielding facing 70 of the central pad 65. The links 30 by which the sub-frame is pivotally mounted are carried on bars 75 which are extended inwardly to support a cross bar 76 upon which burnishing mechanism is carried, comprising members 77 each mounted individually on a leaf spring 78 carried by an arm 79 of clamping bracket 80 fast to bar 76; the members 77 are designed to fit the surfaces of the spool 27 immediately adjacent the bases of the flanges 29. Clamping brackets 83 are provided on the cross-bar 76; intermediate the ends of the clamping brackets are provided fulcrum pins 84 on which are pdvoted arms 85 urged upwardly by compression springs 86 seated upon the outer ends of brackets 83. The arms 85 have ears 87 for the support of the burnishing tool 58 which is fulcrumed on cross pin 89 and adjusted by set screws 90; this tool is for burnishing the rounded periphery of the flange 29 and has a V-groove 91 which is relatively deep at the end first engaged by the spool flanges but gradually decreases in depth until it runs out completely at the remote end of the tool. Each arm 85 has a bracket 93 carrying cam 94 which, during normal operation, is spaced from the collar 22 of live spindle 16, but is so located that it will engage such collar and prevent the spring 86 from forcing the tool into the path of the spindle in the event that the spindle carries no workpiece 27.