Tool changing – Including machine tool or component – Rotary spindle machine tool
Reexamination Certificate
2002-10-15
2004-06-22
Wellington, A. L. (Department: 3722)
Tool changing
Including machine tool or component
Rotary spindle machine tool
C409S230000, C409S231000, C409S234000, C408S124000
Reexamination Certificate
active
06752750
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tool to be attached to a spindle of a machine tool for machining a workpiece.
2. Description of the Related Art
In, for example, a machining center or other machine tool provided with a spindle, the maximum rotational speed of the spindle (per unit time) is determined by the structure of a main bearing rotatably supporting the spindle and a lubrication system. For this reason, when rotation of a tool at a higher rotational speed than the maximum rotational speed of the spindle is desired, an accelerating apparatus is used.
An accelerating apparatus which holds the tool and is able to be attached to the spindle and which can increase the rotary force of the spindle by a gear mechanism such as epicyclic gearing to increase the rotational speed of the tool is known.
For example, in a machining center, when it is desired to increase the rotational speed of the tool to higher than the maximum speed of the spindle temporarily, such an accelerating apparatus is attached to the spindle in the same way as an ordinary tool to enable the tool to be rotated at a higher rotational speed.
However, when raising the rotational speed of the tool to a higher speed than the spindle by the above gear mechanism such as at a super high rotational speed such as tens of thousands to hundreds of thousands of revolutions per minute, the accelerating apparatus increasingly generates heat so the machining tolerance of a workpiece can be influenced by the heat. Further, at the above super high rotational speed, the noise from the accelerating apparatus can also increase. Furthermore, a highly reliable precision structure able to withstand the above super high rotational speed is required for the accelerating apparatus. Therefore, there is the disadvantage that the manufacturing cost becomes relatively high.
Further, in a case of an accelerating apparatus with a gear mechanism, it is necessary to lubricate the gear or bearing and arrange a supply passage and a discharge passage for the lubricating oil in the accelerating apparatus, so there is the disadvantage that the apparatus becomes larger and it is difficult to automatically change the tool by an automatic tool changer.
Further, as another accelerating method, sometimes the method is adopted of using a high frequency motor for the motor driving the tool and supplying drive current to this high frequency motor from a specially provided control apparatus so as to rotate the tool at a high speed. With this method, however, since there is a cable for supplying electric power from the outside, there are the disadvantages that it is difficult to automatically change tools like with an ordinary tool and the cost of the facilities is relatively high.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a tool and a tool holder able to be attached to a spindle of a machine tool by an automatic tool changer in the same way as an ordinary tool, capable of operating without connection with an external power supply etc., and enabling tool rotation at a different rotational speed than that of the spindle of the machine tool without supplying electric power from the outside.
Another object of the present invention is to provide a machine tool not requiring the supply of electric power to an attachment using electric power attached to the machine tool body from an external power supply through a power feed cable.
Another object of the present invention is to provide a machine tool provided with the above tool and tool holder.
According to a first aspect of the present invention, there is provided a tool attachable to a spindle of a machine tool comprising a machining tool for machining a workpiece; a motor connected to the machining tool and causing the machining tool to rotate; and a generator to which rotary force is transmitted from a spindle of the machine tool and generating electric power to drive the motor; wherein a shaft of the motor is arranged in an orientation different from an axial center of the spindle.
Preferably, the tool is provided with a plurality of the motors and machining tools.
Preferably, the tool further comprises an attachment part attachable to the spindle and transmitting rotary force of the spindle to the motor and a case for holding the motor and generator, rotatably holding the attachment part, and engaging with a non-rotating portion of the machine tool so as to be restricted from rotation.
Preferably, the generator is an alternating current generator which supplies voltage of a frequency in accordance with the rotational speed of the spindle to the motor, and the motor is an induction motor rotating by the rotational speed in accordance with a frequency.
According to a second aspect of the invention, there is provided a tool holder able to hold a machining tool for machining a workpiece and attachable to a spindle of a machine tool body, comprising a tool holding part for rotatably holding the machining tool; a motor for rotating the tool holding part; and a generator to which rotary force is transmitted from a spindle of the machine tool and generating electric power to drive the motor; wherein a shaft of the motor is arranged in an orientation different from an axial center of the spindle.
Preferably, the tool holder is provided with a plurality of the motors and tool holding parts.
According to a third aspect of the present invention, there is provided a machine tool comprising a machine tool body provided with a spindle, a driving means for driving the spindle, and at least one control axis for changing a relative position between the spindle and a workpiece; a control apparatus for controlling the driving means and the control axis in accordance with a machining program; and an automatic tool changer provided with a plurality of types of tools and attaching a tool to the spindle; the plurality of types of tools each including a machining tool for machining a workpiece, a motor connected to the machining tool and rotating the machining tool, and a generator to which rotary force is transmitted from the spindle and generating electric power to drive the motor.
Preferably, the tools include a plurality of tools having different postures of shafts of the motors with respect to axial centers of the spindle.
Alternatively, the tools include tools provided with a plurality of motors and machining tools.
According to a fourth aspect of the present invention, there is provided a machine tool comprising a generator for generating electric power by power supplied from the outside and an electrodischarge machining electrode for performing electrodischarge machining using the electric power generated by the generator.
Preferably, the tool further comprises an attachment part able to be attached to a moving and positioning means for moving and positioning the electrodischarge machining electrode with respect to a workpiece to be machined by electrodischarge machining.
Alternatively, the tool further comprises an electrode holding means for exchangeably holding the electrodischarge machining electrode.
More preferably, the moving and positioning means is a machine tool able to cut a workpiece, and the generator generates electric power by power from a power source provided in the machine tool.
Still more preferably, the generator generates electric power by the transmission of rotary force of the spindle of the machine tool.
According to a fifth aspect of the present invention, there is provided an electrodischarge electrode holder comprising a generator for generating electric power by power supplied from the outside and a holding means for exchangeably holding an electrodischarge machining electrode for electrodischarge machining using electric power generated by the generator.
Preferably, the holder further comprises an attachment part able to be attached to a moving and positioning means for moving and positioning the electrodischarge machining electrode with respect to a workpiece to be machined by electrodischarge machining.
Acc
Adachi Sakashi
Katsumata Koji
Pillsbury & Winthrop LLP
Toshiba Kikai Kabushiki Kaisha
Wellington A. L.
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