Numerical-controlled machine tool

Gear cutting – milling – or planing – Gear cutting – With regulation of operation by use of templet – card – or...

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Details

51 2AA, 51 95GH, 364474, 409 15, B23F 522, B23F 1502

Patent

active

045853770

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a numerical-controlled machine tool for cutting a gear, such as a gear hobbing machine, a gear grinding machine or the like.
Generally, in this kind of machine tool, the synchronous relationships of the rotation of a cutter, such as a hob or the like, the rotation of a table carrying a workpiece and the vertical movement of the cutter are determined in accordance with the number of teeth and the tooth profile of the gear to be cut. In consequence, also in conventional numerical-controlled machine tools, command pulses are naturally distributed to respective drive shafts so that the synchronous relationships may be satisfied. In the prior art, however, the distribution pulses are produced by mounting a pulse generator on the shaft of the cutter and performing an operation of obtaining a unit amount of movement of each shaft which satisfies the above synchronous relationships, for each pulse generated by the rotation of the cutter; it is difficult to stop the vertical movement of a hob or change its speed, for example, during hobbing a helical gear. Accordingly, the prior art has the defect of severe limitations imposed on cutting conditions.


SUMMARY OF THE INVENTION

An object of the present invention is to make it possible to stop the relative movement of a cutter and a gear blank or change its speed during cutting in a numerical-controlled machine tool for cutting a gear, such as a gear hobbing machine, a gear grinding machine or the like.
The numerical-controlled machine tool of the present invention is provided with a synchronization control pulse distributor for controlling the synchronous relationship between the rotation of a cutter and the rotation of a gear blank, which is determined in accordance with the number of teeth of a gear to be obtained, a tooth profile forming pulse distributor for controlling a vertically-moving shaft of at least the cutter or the gear blank and a rotary shaft of the gear blank, and an adder for adding together distribution pulses of the tooth profile forming pulse distributor and the synchronization control pulse distributor to produce command pulses to be supplied to the rotary shaft of the gear blank. The synchronization between the rotation of the cutter and the rotation of the gear blank is provided by the synchronization control pulse distributor and an additional rotation of the gear blank necessary for forming the tooth profile of the gear is performed by the tooth profile forming pulse distributor, so that even if the vertical movement of the cutter, such as a hob, is stopped or its feed rate is changed during cutting, no troubles will be caused since the rotary shaft of the gear blank (a shaft C) and the rotary shaft of the cutter cutter (a shaft T), such as hob, are synchronized with each other. Accordingly, cutting conditions can be changed freely.


BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing the arrangement of the principal part of an embodiment of the present invention; and
FIG. 2 is a diagram explanatory of the operation of a tooth profile forming pulse distributor in the cutting of a helical crowing gear.


DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates the arrangement of the principal part of an embodiment of the present invention as being applied to a numerical-control gear hobbing machine.
In FIG. 1, reference numeral 100 indicates a bed of the gear hobbing machine and 101 a table pivotally mounted on the bed 100, on the top surface of which a gear blank can be mounted. The table 101 is driven by a motor 102 (the drive shaft of which will hereinafter be referred to as the shaft C) and its rotational position is detected by a position detector 103 and fed back to a C-shaft servo unit 104, by which the table is controlled in position. On the bed 100 is mounted a ram 106 which is driven by a motor 105 (the drive shaft of which will hereinafter be referred to as the shaft Z) to be movable up and down and its vertical position is detected by a position detecto

REFERENCES:
patent: 3204532 (1965-09-01), Budnick
patent: 3267344 (1966-08-01), McDaniel
patent: 4178537 (1979-12-01), Angst

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