Patent GB-920204-A (GB)
Title: Machine for preparing screw-threaded pipes
IPC: B23G1/22
Filed: 1959-05-15
Abstract: 920,204. Screw-threading. RUHRSTAHL A.G. May 15, 1959 [May 17, 1958], No. 16826/59. Class 83 (3). [Also in Group XXIII] A machine for preparing a threaded pipe 1, which machine may be mounted on a truck, comprises a slidable tool spindle 35 carrying a circular saw 36 and a cylindrical or slightlytapered thread cutter 37 with closed grooves, the tool spindle being movable by slides 39, 40, transversely and longitudinally relatively to the pipe which is held by a longitudinally adjustable headstock 4. The headstock is traversed by a lever 25 rotating a pinion engaging a fixed rack. When the lever is swung towards the headstock, yoke-pins thereon move a graduated collar 10 axially to force a pin against a gib on the headstock guide, so clamping the headstock in position. An electric motor 47 rotates a shaft 57, Fig. 5, driving a pinion 60 and thus the chuck 3. The shaft 57 also rotates a shaft 62 bearing at one end a cam 63 and at the other being engaged by a cam-shaft 69 which can be withdrawn by a handle 71. The shaft 57 is rotated through a change-speed gearing set by a knob 78, the gearing in one position actuating a cut-out switch and enabling adjustments to be made by a wheel 83. A further cam 65, Fig. 8, on the shaft 62 engages a lever 95 to move a rod 98 against a stepped cam 100a on a shaft 101. The shaft 101 carries two other cams 100b, 100c and is adjusted angularly by a lever 131 according to the diameter of the work. The lever 131 also moves a cam 122, rods 119, 120, a bellcrank 123 and a yoke 126 to move a group of pitch-changing cams 128 axially of the shaft 69. A lever 111 on the upper tool slide 39 can be moved to allow a surface 137b on the slide 40 to bear against a wedge 136 having a roller 135 bearing on one of the cams 128. In operation, the pipe 1, which is to be shortened by an amount a and threaded along a length b, is mounted in the chuck. The machine is started by a push-button 155 and the cam 65 rotates to move the lever 95, the rod 98, the shaft 101, supported on a swinging lever 108, and an auxiliary slide 105 locked to the tool slide 39 by an eccentric 112 operated also by the lever 111. The saw thus advances a distance h and severs the pipe end. The cam 63 then actuates a switch 64 and stops the motor 47, the saw being returned via the lever 108 by a spring 117. The headstock is next moved by the lever 25 for a distance c, the amount b to be threaded then being shown on a scale adjacent the lever. The lever 111 is now turned through 180 degrees and the eccentric 112 moves the slide 39 towards the work by a distance 2e. When the motor 47 is started, the cam 65 moves the slide again by the distance h and the thread is cut to the correct depth while the selected cam 128 moves the wedge 136 to retract the slide 40 by one thread pitch. The machine is then switched off by the cam 63. The auxiliary slide 105 carries three stop rods 103a-103c, Fig. 9, which can be individually adjusted by screws 104. The screws 104 enable adjustments to be made when a cutter is reground and the three rods enable three different cutters to be used on the machine. Reference has been directed by the Comptroller to Specification 697,042.