Thread cutting machine and thread cutting method
First Claim
1. A thread cutting apparatus, comprising:
- a rotatable spindle;
a tapping tool attached to said rotatable spindle, said tapping tool having a cutting pitch at which threads are cut in a workpiece;
a servo drive system for driving an axial feeding speed, rotating speed, and axial feeding position of said tapping tool relative to said workpiece;
a load detecting system for detecting an axial load on said tapping tool based on an output of an amplifier of said servo drive system when said tapping tool taps said workpiece; and
a correcting system for correcting at least one of the rotating speed, feeding speed, or feeding pitch according to said detected axial load to reduce said axial load while maintaining said cutting pitch.
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Accused Products
Abstract
Axial loads encountered during thread cutting are reduced by controlling interactions between rotation speed, axial feeding speed, feeding (threading) pitch, and feeding position. A counterload is generated by changing a feeding pitch to a corrected feeding pitch, which changes the rotation speed, while keeping the feeding speed constant; by changing the feeding speed, while compensating the rotation speed (which is derived from the feeding speed) to remain constant; by changing the rotation speed, while compensating the rotation speed deviation feedback (to allow the deviation correction to follow the rotation speed change), while keeping the feeding speed constant; by generating a function according to empirical results that controls the feeding pitch, and therefore the rotation speed, while keeping the feeding speed constant; and by combinations of these methods.
11 Citations
35 Claims
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1. A thread cutting apparatus, comprising:
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a rotatable spindle; a tapping tool attached to said rotatable spindle, said tapping tool having a cutting pitch at which threads are cut in a workpiece; a servo drive system for driving an axial feeding speed, rotating speed, and axial feeding position of said tapping tool relative to said workpiece; a load detecting system for detecting an axial load on said tapping tool based on an output of an amplifier of said servo drive system when said tapping tool taps said workpiece; and a correcting system for correcting at least one of the rotating speed, feeding speed, or feeding pitch according to said detected axial load to reduce said axial load while maintaining said cutting pitch. - View Dependent Claims (2, 3, 4, 5)
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6. A thread cutting apparatus, comprising:
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a rotatable spindle; a tapping tool attached to said rotatable spindle, said tapping tool having a cutting pitch at which threads are cut in a workpiece; control means for controlling an axial feeding speed, rotating speed, and axial feeding position of said tapping tool relative to said workpiece; and means for generating a counterload in an opposite direction to an axial load on said workpiece while maintaining said cutting pitch during thread cutting of said workpiece; wherein said control means comprises; rotating means for relatively rotating said tapping tool and the workpiece at a predetermined rotating speed; feeding means for relatively axially feeding said tapping tool and the workpiece at a predetermined feeding speed related to said rotating speed by a feeding pitch; and an input unit for inputting said feeding pitch; wherein said means for generating a counterload comprises; a function generator for generating a feeding pitch function according to said feeding pitch; wherein said feeding speed and said rotating speed are determined according to a relationship with said feeding pitch function to change said axial load while maintaining said cutting pitch; and wherein said means for generating a counterload generates said counterload according to a predetermined relationship between said feeding pitch and said axial load. - View Dependent Claims (7, 8)
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9. A thread cutting apparatus, comprising:
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a spindle equipped with a tapping tool having a cutting pitch at which threads are tapped; control means to which a feeding pitch corresponding to said cutting pitch is input; rotating means for relatively rotating said tapping tool and a workpiece at a rotating speed; a servo feeding system for relatively axially feeding said tapping tool and the workpiece at a feeding speed related to said rotating speed and said input feeding pitch; a load detecting system for detecting an axial load on said tapping tool based on an output of an amplifier of said servo drive system when said tapping tool taps said workpiece; and correcting means for correcting at least one of the rotating speed, feeding speed, or feeding pitch according to said detected axial load to reduce said axial load while maintaining said cutting pitch. - View Dependent Claims (10, 11, 12, 13)
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14. A thread cutting apparatus, comprising:
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a rotatable spindle having a tapping tool attached, said tapping tool being axially feedable and rotatable; instruction means for sending a feeding speed instruction; feeding control means for setting a feeding speed of said tapping tool according to said feeding speed instruction; conversion means for converting said feeding speed instruction according to a predetermined ratio to a rotation speed instruction, rotation control means for setting a rotation speed of said tapping tool according to said rotation speed instruction; feedback means for correcting rotation speed when a feeding feedback signal, taken from detected feeding speed, deviates from said feeding speed instruction; means for changing said feeding speed away from said feeding speed instruction; and means for compensating said feeding feedback signal, in response to said means for changing, to maintain said rotation speed uncorrected even when said detected feeding speed is changed from said feeding speed instruction. - View Dependent Claims (15, 16)
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17. A thread cutting apparatus, comprising:
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a rotatable spindle having a tapping tool attached, said tapping tool being axially feedable and rotatable; instruction means for sending a feeding instruction; feeding control means for feeding said tapping tool according to said feeding instruction; conversion means for converting said feeding instruction according to a predetermined ratio to a rotation instruction, rotation control means for rotating said tapping tool according to said rotation instruction; feedback means for correcting rotation deviation from said rotation instruction according to a rotation feedback signal representing detected rotation; means for changing said rotation away from said rotation instruction; and means for compensating said rotation feedback signal, in response to said means for changing, to allow said changing of rotation even when said rotation deviates from said rotation instruction. - View Dependent Claims (18, 19)
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20. A thread cutting apparatus, comprising:
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a spindle equipped with a tapping tool having a cutting pitch at which threads are tapped; control means to which a feeding pitch corresponding to said cutting pitch is input; rotating means for relatively rotating said tapping tool and a workpiece at a rotating speed; feeding means for relatively axially feeding said tapping tool and the workpiece at a feeding speed; and a function generator for generating a feeding pitch function according to said feeding pitch; wherein said feeding speed and said rotating speed are determined according to a relationship with said feeding pitch function to change said axial load while maintaining said cutting pitch. - View Dependent Claims (21, 22, 23, 24)
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25. A thread cutting apparatus, comprising:
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a spindle equipped with a tapping tool having a cutting pitch at which threads are tapped; control means to which a feeding pitch corresponding to said cutting pitch is input; rotating means for relatively rotating said tapping tool and a workpiece at a rotating speed; feeding means for relatively axially feeding said tapping tool and the workpiece at a feeding speed; a feeding position detector for detecting a relative feeding position of said workpiece with respect to said tapping tool; and a function generator for generating a feeding pitch function according to said relative feeding position; wherein said feeding speed and said rotating speed are determined according to said feeding pitch function to change said axial load at differing relative feeding positions while maintaining said cutting pitch. - View Dependent Claims (26, 27, 28, 29)
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30. A thread cutting method applied in a thread cutting machine having a tapping tool with a cutting pitch, comprising the steps of:
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setting a rotation speed of a tapping tool to a feeding speed divided by a feeding pitch; detecting an axial load on said tapping tool when said tapping tool cuts threads in a workpiece; and generating a counterload in a direction opposite to said axial load while maintaining said cutting pitch. - View Dependent Claims (31, 32)
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33. A thread cutting method applied in a thread cutting machine having a tapping tool with a cutting pitch, comprising the steps of:
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generating a feeding pitch function defining a predetermined feeding pitch for any feeding position; setting a rotation speed of a tapping tool to a feeding speed divided by said feeding pitch function; and cutting threads in a workpiece according to said feeding pitch function. - View Dependent Claims (34, 35)
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Specification