Screw-cut′ting ma-chine′.
A machine on the principle of the lathe, the rod to be threaded being suspended between the head and tail centers, and being dogged to a face-plate on the mandrel of the former.
The motion is derived from a bevel-pinion which engages one or the other of the bevel-wheels to rotate the feed-screws in one or the other direction; for feeding or returning the slide-rest to the commencing point; or for cutting right or left handed screws.
The feed-screws are shown a little within the ways of the machine, and are turned by pinions into which meshes the spur-wheel on the mandrel of the lathe-head.
By the intervention of suitable gearing, such a proportion is established between the rotation of the rod on which the screw is to be cut, and the feed-screws themselves, as to obtain any required pitch of thread on the rod. The rate of rotation of the rod being assumed as permanent, an equal rate of the feed-screws will cut a thread of a pitch equal to that of the feed-screws.
If the latter are rotated at a slower rate, the pitch of the screw will be less: if the feed-screws are rotated faster than the rod under treatment the pitch of the screw on the lathe will be proportionately increased.
See bolt-cutter; bolt-threading machine; Tur-Ret-lathe; screw-cutting lathe.
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2066]
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Screw-cutting lathe. |
General Sir Samuel Bentham made machines for cutting woodscrews by means of rotary cutters.
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Screw-cutting machine. |
In Royon's machine (
Fig. 4727), the die-chuck
E is hollow, and is turned by the hollow shaft
B, rotated by a pinion meshing with the bevel-wheel
C. The dies
K K are rotatable, have several sets of threads adapted to screws of different sizes and pitch, are secured within the chuck by screws
L, are caused to approach or recede from each other by moving in the eccentric slots
i′ i′ upon turning the ring
I, and are fixed at the proper distance apart by a movement of the lever
R.
T is the carriage on which the screws or bolts are held between the jaws
t′ t‴, approached by a right and left hand screw.
In tapping nuts, the nuts are held by a hollow-ended mandrel inserted through an opening in the chuck
E, into the hollow shaft, while the tap is grasped by the jaws
t′ t‴ of the carriage.
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Screw-cutting machine. |
