Patent GB-567550-A (GB)
Title: Improvements in and relating to metal cutting or like machine tools
IPC: B23Q5/14
Filed: 1943-06-01
Abstract: 567,550. Controlling change-speed gearing. WARNER & SWASEY CO. June 1, 1943, No. 8785. Convention date, May 23, 1942. [Class 80 (ii)] [Also in Group XXII] In a machine tool such as a turning lathe having means for preselecting the speeds at which the traverse of one or more slides may be effected, and embodying indexable means for selecting said speeds, the indexing is poweroperated and the indexing means, together with the control thereof, are carried by one of the movable slides. As applied to a turret lathe, the bed carries a saddle provided with a cross slide and tool turret and a turret slide, all the feeds of which are operated from a shaft 29, Fig. 5, which is driven from the headstock spindle through change-speed gearing. An eight-speed change gear driven by the shaft 29 is mounted in the apron 28 of the saddle and is controlled by two sliding keys 35, 48, Fig. 5, the former co-operating with two gear pinions 42 and the latter with four pinions 56 in series therewith, and the output shaft 64 traverses the saddle through further gearing and a rack and pinion 71, and traverses the cross-slide through gearing 76 and a feed screw 82. These two drives are controlled by clutches 65, 79 respectively which are actuated by cams 83 rotatable on their respective shafts by means of hand levers 85, 86, Figs. 2 and 5. The keys 35, 48 are slid axially to engage the appropriate gear trains by collars 37, 50 actuated by levers 90, 94 whose free ends 92, 96 lie in the path of dogs on drums 100 when the latter are moved axially, the drums being indexable between cutting traverses of a cycle to position different dogs opposite the levers and thus select the speed for the next traverse. The drums are moved axially towards or from each other by levers 101, 103 pivoted respectively at 101<1> and 103<1> and tied together for simultaneous movement by a link 102 provided with a step 106 engaged by a pawl 107 on a bush 108 loosely pivoted on the boss of the hand lever 85. Oscillation of the lever 85 clockwise from the position shown in Fig. 2 engages the clutch 65 for traverse of the saddle, the first part of the oscillation moving the bush 108 through a pin 111 on the lever to cause the link 102 to be moved to the left. This swings the levers 101, 103 towards each other and slides the drums 100 to set the speed-controlling levers 90, 94 in the appropriate positions for the required rate of traverse of the saddle. Towards the end of the movement of the lever 85 into its dotted line position, in which the clutch 65 is engaged, the pawl 107 strikes an adjustable fixed stop 117 and is thereby lifted away from the step 106 on the link 102. Simultaneously a projection 114 on the bush 108 engages an arm 104 on the lever 103 to rock the latter anti-clockwise and cause the drums 100 to be moved apart into indexing position. The lever 85 is held in clutchengaged position by a spring detent 87 and when the required traverse of the saddle has been completed the appropriate stop 174 of an indexable stop roll 175 meets a fixed abutment to release the detent 87 and allow the lever to fall into the full line position in which it rests on a lever 133. To index the drums 100 for the next traverse of a cycle the lever 85 is pushed downwards by the operator against a fixed stop 142, rocking the lever 133 clockwise and sliding a rod 135 to the left against a spring 137. This rocks a lever 139 connected thereto and causes a further arm 144 of the lever to raise a link 145 attached at its lower end to a crank on a flange- 146, Fig. 10, freely rotatable on a shaft 129 and carrying a spring pawl 148. The pawl engages teeth on a ratchet 150 secured to the shaft 129 and thereby rotates the shaft through an angle sufficient to cause a screwed sleeve 128 secured thereto to move a nut 127 axially through a distance equal to the width of one of a series of discs 121, collectively splined to a shaft 97 to which the drums 100 are splined. An arm 126 on the nut 127 is thereby moved from contact with a lug 122 on a disc 121 into position to engage a similar lug on the next disc to the right. At this time an arm 134 on the lever 133 is moved from contact with a spring pawl 166, Fig. 9, pivoted on a bush 165 freely mounted on the shaft 97. This allows the pawl to rock and engage with the teeth of a constantly rotating ratchet 164 driven from an electric motor 60 whereby the bush 165 is driven from the motor and rotates the disc assembly 121 through friction pins 169. The discs, together with shaft 97 and drums 100, then rotate until the lug 122 on the disc aligned with the arm 126 meets this arm and thereby stops the rotation, with the drums indexed to give the required speed of traverse for the next step of the machine cycle. The discs 121 are rotatably adjusted on the shaft 97 to space the successive lugs 122 in the positions necessary to give the required sequence of speeds of traverse for the cycle, and are secured in the adjusted position by longitudinal pins 124. The operator may release the lever 85 as soon as the indexing mechanism for the drums 100 has commenced to function, but if the lever is held against the stop 142 for a longer period the friction pins 169 will slip as soon as the arm 126 meets the lug 122. On release of the lever 85 the spring 137 restores the rod 135 to its right hand position, the arm 134 moves into the path of the pawl 166 to remove it from engagement with the ratchet 164 and stop rotation of the bush 165, the lever 85 is raised to the full line position, and the pawl 148 returns to a position ready for rotating the shaft 129 at the next indexing operation. A spring pawl normally prevents reverse rotation of the shaft 129. In a modified method of operation the spring 137 may be adjusted by a screw 138 so that it does not resist the lever 85 when the latter falls after a cutting traverse and the indexing is thus effected automatically, but when the operator raises the lever 85 to start the next traverse of the cycle, the spring 137 restores the' rod 135 to normal position. On completion of a working cycle, which as shown consists of six traverses with one disc 121 for each traverse, a second arm 130, Fig. 10, on the nut 127 engages a collar 157 on the rod 131 to move the rod to the right and cause a cone 159 connected thereto by a yoke to remove the two pawls from contact with the ratchet 150 and thus allow a spring 153, which has been wound up by the successive rotations of the shaft 129, to rotate the shaft in the reverse direction and return the nut 127 to starting position for the next cycle. The hand lever 86 for actuating the cross-slide clutch 79 carries a projection 115, Fig. 2, engaging a lug on the bush 108 and in the disengaged position rests on an arm 141 of the lever 139 so that oscillation of the lever 86 by the operator clockwise against a stop 143 will effect indexing of the drums 100 whilst anti-clockwise oscillation to engage the clutch will effect the gear change by sliding motion of the drums 100, in the same manner as actuation of the hand lever 85. The working cycle may be made up of saddle and cross-slide traverses in any desired sequence, the appropriate lever 85 or 86 being operated in each case, a numbered disc 170 on the shaft 129 indicating which step of the cycle is in operation at any time. In a modified construction the arms 133, 141 of the levers 134, 139 are omitted and a separate hand lever is attached to the lever 139 to effect the power indexing of the drums 100, the preselection of the traverse speeds and actuation of the clutches 65, 79 being effected by the hand levers 85, 86 as described above. Similar mechanism is used for traversing the turret slide and hand wheels are provided for,traversing the respective slides by hand, and for adjusting the shaft 97 when setting up the indexing discs 121.