Turning – Process of turning
Patent
1982-03-17
1985-04-02
Bray, W. D.
Turning
Process of turning
82 25, 82 45, B23B 1308
Patent
active
045079927
DESCRIPTION:
BRIEF SUMMARY
The bars loaded into the headstock spindles of automatic lathes are much longer than the spindles themselves. It therefore is important that the part extending to the rear of the lathe be supported to prevent it from excessively snapping about under the combined effects of flexure due to its own weight and the centrifugal force induced by the rotation of the spindle. As a rule this is accomplished by keeping this part of the workpiece bar within a guidance tube maintained by two uprights in alignment with the spindle of the lathe headstock and by keeping the free space between the guidance tube and the workpiece bar filled with oil.
While the oil cushion thus formed within the guidance tube and around the workpiece bar is relatively effective when the bar diameter is less than the bore of the guidance tube by only a few millimeters, it proves on the other hand to be inadequate, even wholly inoperative for a larger difference between the diameters of the bar and of the tube. It is conventional practice to machine bars of different diameters in a given automatic lathe, the smaller bars being of a diameter about one fourth of the lathe capacity. Thus, for an 80 mm capacity lathe, sometimes bars merely 20 mm across will be machined. In view of these operational conditions, equipment comprising several guidance tubes of different diameters has been created to assure guiding of different workpiece bars lending themselves to machining on an automatic lathe, while avoiding excessive differences between the diameters of the bar being worked and the bore of the guidance tube.
The various guidance tubes of the known equipment are designed in the manner of consecutive reducer means. This known equipment comprises a first guidance tube with a bore exceeding by less than 5 mm the diameter of those bars corresponding to the maximum lathe capacity. This tube is kept aligned with the headstock spindle of the lathe in a conventional manner, that is, by two uprights. The other tubes of this known equipment are progressively smaller so they can be slipped one within the other to act as consecutive reducers. To machine a small-diameter bar in a given large-capacity lathe, there might be therefore up to five guidance tubes one within the other. A small guidance tube is kept aligned with the lathe headstock spindle by the following guidance tube into which it is slipped by the interposition of soft stuffing surrounding the small tube from place to place all along it.
Such known equipment suffers from drawbacks. Besides the delicate operation of putting a reducing tube in place due to the danger of displacing or even scoring the stuffing which surrounds it, and the soiling involved in removing such a tube due to the oil in the annular spaces between the various coaxial tubes, such known equipment will not neutralize the vibrations relating to the operational bars as would be desirable in all cases. It happens, and especially as regards large-diameter bars (60 mm and more), that at a given speed of rotation the bar being worked on will resonate, which in turn causes the guidance tube to vibrate, whereby the latter no longer fills its function.
The equipment of the present invention is free of these defects. Only one guidance tube will be in operation at one time. The various complexities caused by emplacing and removing the known reducing means therefore are eliminated.
According to one aspect of the present invention, the operational guidance tube is connected to a reinforcing element extending along the entire length of the tube by fastening members arranged at at least three points distributed along the guidance tube. This tube therefore constitutes a rigid guidance means for part of the workpiece bar extending to the rear of the lathe, in the sense that the amplitude of the vibrations of the bar is strictly limited to the nominal dimensions of the tube bore without there being a need to provide this tube with an abnormally thick wall.
According to another aspect of the invention, the fastening members provide a detachable inte
REFERENCES:
patent: 3162315 (1964-12-01), Holden
patent: 4365529 (1982-12-01), Neukomm
Geiser Markus
Vandevoir Claude A.
Bray W. D.
Sameca S.A.
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