Patent GB-239563-A (GB)
Title: An improved machine for grinding or otherwise finishing metal articles
IPC: B24B3/18
Filed: 1924-04-14
Abstract: 239,563. Hanson, B. M. W. April 14, 1924. Milling screws ; milling-machines. -In a machine for grinding or otherwise finishing metal articles of the type described in Specification 184,510 and comprising a rocking- bed mounted on a fixed bed for rocking movement only, the tool or grinding-wheel being carried by one bed and the work by the other, and means being provided for effecting relative longitudinal movement between the grinding-wheel and the work, means are also provided which act between the rocking bed and the fixed bed, and are driven in a predetermined manner during the relative longitudinal movement between the grinding-wheel and the work, so as to produce a predetermined regular or irregular contour on the work: the machine is also adapted to grind or finish articles having circumferential contoured or relieved parts between spirallv arranged flutings therein. As described with reference to grinding the longitudinal contour is produced by a cam s, Fin. ? 2 which co-operates with the feed device p which is similar to that of Specification 184,510, by which the bed b is rocked to move the workholder towards the grinding-wheel f &c., to take a new cut, the cam being carried by a shaft 60, Figs. 5 and 8. in the short arm of a rocking beam c pivoted on a shaft 161 in the rearwardlyextending arm e of the rocking bed b. The drive for the cam s is connected with the drive of the lead screw passing through change and other gearing, including a bevel wheel on the shaft 161, and the cam rests upon an antifriction roller 34 at the end of the nut 28, forming part of the feed device p and is rotated through a small or large amount to rock the beam according to whether the taper of the articlebeing operated upon is of small or large amount; when a cylindrical article is being finished the. cam is rendered inoperative by turning a disc 62 loosely mounted on the cam-shaft 60 to engage the roller 34 and raise the cam from contact therewith; the cam may have rises and concentric portions when the work has both tapered and cylindrical surfaces. The relieving-cam r for producing the circumferential contour. e.g. relieving the thread of a tap, is driven through differential gearing associated with the drives of the workspindle n and lead screw h, and acts upon the long arm of the rocking beam o through an adjustable device comprising a piece 44 resting on the cam and pivoted to the part e of the bed b; a finger 47 carried by the rocking beam rests on the piece 44 and is adjustable along the beam to vary the extent to which the cam rocks the beam o and bed b according to the amount of relief. For producing reliefs on spirally-fluted articles the cam is driven through differential gear 174, Fig. 7, associated with the drives of the lead screw and work spindle. As shown, the shaft 170 of the cam r is driven through change gearing from a wheel 177 loose in a shaft 183 and meshing with the idlers of the differential gearing, the shaft carrying the idlers being fixed at right angles to the shaft 183 which is driven through worm and .change gearing from the lead screw drive; this gearing is disconnected and the shaft 183 fixed against rotation when a straight fluted article is being finished. The cam may be rendered inoperative for concentric work by actuating a screw 5 in the locking beam to raise the finger 47 from engagement with the piece 44. The eccentric q bv which the bed is rocked' away from the work at the completion of the operative stroke of the work-holder is connected to the rocking beam by an adjustable link 40 having a loose connection between the parts; a projection 52 on the link 40 lifts the piece 44 from the cam r during the inoperative stroke of the work-holder. To indicate the extent to which the bed is being rocked and to give warning of the danger of the nut 26 of the feed device jamming against the ends of the screw 31. a rod 184 resting on the fixed bed a is slidably mounted in a lug 185 on the rocking bed and has three marks reading against an edge 185 on the lug of the rocking bed. All the various drives are connected by a gearbox z on the arm e of the rocking bed and are driven from the shaft 70, the various movements being controlled by the reciprocation of the work-holder which carries a dog 115 contacting with dogs on a rod 117 slidably mounted on the fixed bed. The shaft 129, Fig. 12, carrying the eccentric g has a cam sleeve 128 fixed thereto adjacent a ratchet wheel 132 normally loose thereon, the cam sleeve being intermittently clutched for a halt a revolution to the ratchet wheel by a pawl 127 pivoted to the sleeve and moved out of engagement with the ratchet wheel at each half revolution by pins 126 carried by an escapement yoke mounted on a verticallymovable rod 124 actuated by connections from the rod 117. When the cam sleeve and shaft 129 are rotated, the eccentric q is actuated to move the locking bed away from or towards the wheel f, and the cam sleeve throws over a shipper lever 135 to reverse or restore the operative drive, of the lead screw; a cam 137 on the shaft 129 rocks a lever 138 connected through a rock-shaft 141 with a ratchet mechanism 146 which at each operative reciprocation of the work-holder automatically turns the shaft 35 of the feed-device p to give a new cut. The shipper lever 135 may be actuated by a handle 149 and the cam 128 has a wide portion which allows the clutch sleeve 88 of the lead screw drive, to be held in the neutral position ; the work-holder may be stopped at the end of any stroke by a slide 154 which is pushed by a rod 152 into the path of movement of the pawl 127 to stop the cam sleeve 128 when the shipper lever has moved the clutch sleeve. into neutral. The work is adjusted in relation to the grinding- wheel by a gauge similar to that described in Specification 185,376 and comprising a pointer 192 shaped to the thread to be ground, the pointer being carried by an arm 191 pivoted to a block 188 adjustable longitudinally along a bracket adjustably fixed to the rocking bed; the pointer is set to a test piece placed between the headstocks and after being locked in position is used to set the work and can be thrown back on its pivot when not in use. The grinding-wheel f is carried by a bearing box u mounted on ways 201 curved to the centre of the wheel so that the wheel can be adjusted to the lead of the thread: the wheel is driven by a belt x passing over idler pulleys 205, 206 carried on a horizontally and vertically adjustable slide 210, the idler 205 being carried by a spring-controlled bell-crank 212 pivoted to the slide.