Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Patent
1992-02-04
1993-08-17
Ip, Paul
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
318 39, 318 68, 318569, 36447431, 36447412, B22B 4700, B23G 300, B23G 116
Patent
active
052372510
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a control unit for use with a machine having main spindles for workpiece rotation and tool rotation and provided with a tapping function, and more particularly, to a control unit for controlling the drive of main spindles so as to achieve tapping onto an end face of a rotating workpiece.
2. Description of the Related Art
In a machine of a type having main spindles respectively for workpiece rotation and for tool rotation, e.g., a compound lathe such as a turning center, a series of machining operations is implemented in succession. For instance, tapping is made onto an end face of a workpiece after cutting onto the peripheral face of the workpiece is performed, and then another cutting operation is carried out. In this case, generally, upon completion of the first cutting operation, the rotation of the workpiece is decelerated and stopped, and then the tapping is started. Further, upon completion of the tapping operation, the rotation of the workpiece is started and is then accelerated until a predetermined rotational speed suited for the second cutting operation is reached. Conventionally, therefore, it is impossible to effect machining which requires workpiece rotation simultaneously with tapping. Moreover, the workpiece rotation must be decelerated and stopped before the start of tapping, and the workpiece rotation must be restarted and accelerated after completion of tapping. As a result, a total machining time required for a series of machining operations is prolonged, leading to lower machining efficiency.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a control unit capable of controlling the drive of a machine having main spindles for workpiece rotation and for tool rotation and provided with a tapping function, in a manner permitting tapping onto an end surface of a rotating workpiece.
To achieve the above-mentioned object, according to the present invention, there is provided a control unit for use with a machine, with a tapping function, which is arranged to rotatively drive a first main spindle adapted to be mounted with a workpiece by a first motor, and rotatively drive a second main spindle adapted to be mounted with a tapping tool by a second motor, and axially drive the latter spindle by a third motor.
The control unit comprises: a position detector coupled to the second main spindle; a first control circuit for controlling rotation of the first motor in accordance with a workpiece rotational speed command supplied from a host controller; a second control circuit for periodically executing position control processing in accordance with a tool rotational speed command supplied from the host controller and a positional feedback signal, indicative of an actual rotational position of the tool, supplied from the position detector to thereby periodically calculate a tool rotational speed command during the workpiece rotation, and for periodically executing speed control processing in accordance with the thus calculated speed command to thereby control rotation of the second motor; and a third control circuit for controlling rotation of the third motor in accordance with a tool axial moving speed command supplied from the host controller and corresponding to the tool rotational speed command.
According to the present invention, as described above, during the workpiece rotation effected in accordance with a workpiece rotational speed command, speed control processing is periodically executed in accordance with a tool rotational speed command during the workpiece rotation which is determined by position control processing periodically carried out in accordance with a tool rotational speed command and an actual tool rotational position, whereby the second motor for tool drive is so driven as to rotate the tool at a speed equal to a sum of a target workpiece rotational speed and a target tool rotational speed. Thus, it is possible to simultaneously rotate the workpiece and the tool wit
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Kono Shinichi
Takahashi Hironobu
Franc Ltd.
Ip Paul
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