GB1058153A - Screw thread cutting mechanism - Google Patents

Abstract

1,058,153. Lathe details. HARDINGE BROS. Inc. June 24, 1964, No. 26100/64. Heading B3T. A screwing attachment is secured to the headstock 25 of a lathe, Figs. 1, 3 (not shown), having a work spindle screwed at 27, and comprises a fixed casing 35, a bar 34 pivotable about its axis and slidable in the casing, an arm 31 adjustably fixed to bar 34 and carrying a follower 32 for engagement with screw 27, and a second arm 42 fixed to bar 34 for controlling the radial and lengthwise movement of the cutting tool 30. Tool head 100 is clamped on bar 34 at 101, Fig. 11 (not shown), and comprises a tool slide 102 vertically movable to increase the depth of cut, by a pneumatic piston 105. This movement is controlled by a rotatable cam 115, which co-operates with a pin 116 carried on slide 102. Cam 115 is mounted on a shaft 119, and the latter also carries a ratchet wheel 121, which co-operates with a pawl 122, Figs. 14, 15 (not shown). The pawl is mounted on a push rod 125 actuated by a piston 126, Fig. 10 (not shown), against a spring 128. Wheel 121 carries a pin 155, Fig. 15 (not shown), for cooperation with a stop 157 to stop the machine, is turned by pawl 122 against a torsion spring, and is held against back rotation by a holding pawl 135. A dial 145, Fig. 19 (not shown), is provided on shaft 119 for indicating the depth of cut of tool 30; and carries a pin 150 which is placed in any one of a number of holes 151 in wheel 121, and also carries a pin 153 for controlling the stopping of the attachment. After pawl 122 has advanced wheel 121 to its full extent, pin 153 engages a recess 165 in a bar 166, Fig. 14 (not shown), the bar is raised against a spring 167, and allows a horizontal bar 170 to move to the right to disengage pawls 122, 135, from ratchet wheel 121, which is then rotated by the torsion spring to its starting position. Bar 166 engages a pin 182, Fig. 11 (not shown), which closes a switch 185 to shut off all electric power to the attachment. Arm 42, Fig. 9 (not shown), is clamped on housing 41 during sliding by a pivoting clamp 55, actuated by a pneumatic piston 59, and is pivoted by a pneumatic piston 50. Air is admitted to cylinders 60, 53, by an electrically operated air valve actuated by limit switches arranged in a housing 71, Fig. 6 (not shown). The switches are tripped by a block 72 mounted on a reciprocating rod 73, the rod being movable by a block 90 fixed to arm 42, which engages collars 77, 78. In operation, .bar 34 is pivoted so that tool 30 engages work 29. Rod 73 is moved by block 90 and air is supplied to cylinders 60 and 53, thus permitting arm 31 to pivot and engage follower 32 and screw 27. Clamp 55 clamps arm 42 and the work is screwed until rod 73 is moved in the reverse direction to admit air to the opposite ends of the cylinder, to thus pivot bar 34 to disengage follower 32 and tool 30 from the spindle and work respectively, and a spring moves bar 34 axially to its starting position. Pawl 122 actuates ratchet 121 to rotate cam 115, and air is supplied to piston 105, to thus advance tool 30 to increase the depth of cut.