Precision machine system

• US 4,602,540 A
• Filed: 02/19/1985
• Issued: 07/29/1986
• Est. Priority Date: 11/26/1981
• Status: Expired due to Term

• Current Assignee: Toshiba Kikai Kabushiki Kaisha
• Original Assignee: Toshiba Kikai Kabushiki Kaisha
• Inventors: Tanimoto, Isamu, Sagara, Toshio, Murofushi, Masatoshi
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Kearns, Jerry
• Application Number:
  US06/701,811
• Time in Patent Office: 525 Days
• Field of Search: 82/2 B, 82/24 R, 318/592, 318/593, 318/594, 318/640, 364/182
• US Class Current: 82/118
• CPC Class Codes: G05B 19/39 using a combination of the means covered by at least two of the preceding groups G05B19/21, G05B19/27 and G05B19/33
• CPC Class Codes: G05B 2219/34161 Superposition curves, combine xy slides with other xy or polar slides
• CPC Class Codes: G05B 2219/37275 Laser, interferometer
• CPC Class Codes: G05B 2219/37405 Contact detection between workpiece and tool, probe, feeler
• CPC Class Codes: G05B 2219/42075 Two position loops
• CPC Class Codes: G05B 2219/50313 Tool offset, tool wear
• CPC Class Codes: Y10T 82/2502 with program control

Abstract

A precision machining system for machining a workpiece into a desired surface with two tool driving units. A first drive unit moves the tool along at least two axes to shape the workpiece similar to a desired surface. A second drive unit moves the tool along one of the axes in a very finely controlled manner. A measuring unit measures the tool position with an accuracy higher than that to which the first drive unit can respond. A signal producing unit is responsive to the measuring unit for producing a control signal for controlling the operation of the second drive unit while the first drive unit is operating.

Claims

1. A precision system for controlling the movement of a tool which moves relative to a workpiece to machine said workpiece into a desirable shape, said precision system comprising:

a tool holding unit for holding said tool;

a tool support operatively connected to said tool holding unit for holding said tool holding unit;

fine displacing drive means operatively connected to said tool holding unit for driving said tool holding unit relative to said tool support and along a first direction, in response to a fine displacing drive means control signal;

first tool support drive means operatively connected to said tool support for moving said tool support relative to said workpiece along said first direction;

second tool support drive means operatively connected to said tool support for moving said tool support relative to said workpiece along a second direction perpendicular to said first direction said first and second tool support drive means moving said tool support in accordance with a predetermined pattern of movement, and said first tool support drive means moving said tool support relative to said workpiece along said first direction by a predetermined amount in response to a tool support drive means control signal;

first measuring means operatively associated with said tool holding unit for measuring said tool position with respect to said workpiece along said second direction with accuracy higher than that to which said second tool support drive means can respond, and for outputting a second direction position signal;

function generating means operatively connected with said first measuring means for receiving said second direction position signal from said first measuring means and producing a desired position signal corresponding to a desired tool position along said first direction of said predetermined pattern of movement;

second measuring means operatively associated with said tool holding unit for measuring said tool position with respect to said workpiece along said first direction with accuracy higher than that to which said first tool support drive means can respond, and for outputting a first position signal;

first comparing means operatively connected with said function generating means and second measuring means for receiving said desired position signal from said function generating means and for receiving said first position signal from said second measuring means, and being operatively connected with said fine displacing drive means for producting said fine displacing drive means control control signal, representing a difference between said desired tool position and said tool position along said first direction for controlling the operation of said fine displacing drive means for driving said tool holding unit while said first and second tool support drive means are operating; and

second comparing means operatively connected with said function generating means and second measuring means for receiving said desired position signal from said function generating means and for receiving said first position signal from said second measuring means and for producing said tool support drive means control signal, when the difference between said desired position signal and said first position signal exceeds a predetermined value and being operatively connected to said first tool support drive means, for causing said first tool support drive means to move said tool support relative to said workpiece along said first direction by said predetermined amount.

2. A precision system as in claim 1 wherein each of said first and second measuring means comprises a laser interferometer device.

3. A precision system as in claim 1, wherein said fine displacing means comprises a piezo-electric element.

4. A precision system as in claim 1 wherein said fine displacing drive means comprises a drive circuit having a plurality of power transistors connected in series along their emitter-collector paths.

5. A precision system as in claim 1, wherein said function generating means comprises a data memory which stores said desired tool position in relation to said tool position along said second direction.

6. A precision system as in claim 1, wherein said first measuring means includes a counter which increments said second direction position signal when said tool is moved each predetermined distance in a direction perpendicular to said first direction, said second direction position signal being applied to said function generating means.

7. A precision system as in claim 1, wherein said function generating means produces an indication of the difference between a present said desired tool position and a next desired tool position.

8. A precision system as in claim 1, wherein said second comparing means comprises hold circuit means for retaining a tool position along said first direction measured by said second measuring means;

and

a comparator for producing said tool support drive means control signal when a difference between said position retained by said hold circuit means and said desired tool position exceeds said predetermined value.

9. A precision system for controlling the movement of a tool which moves relative to a workpiece to machine said workpiece into a desirable shape, said precision system comprising:

a tool holding unit for holding said tool;

a tool support operatively connected to said tool holding unit for holding said tool holding unit;

fine displacing drive means operatively connected to said tool holding unit for driving said tool holding unit relative to said tool support and along a first direction, in response to a fine displacing drive means control signal;

first tool support drive means operatively connected to said tool support for moving said tool support relative to said workpiece along first direction by a predetermined amount in response to a tool support drive means control signal;

second tool support drive means operatively connected to said tool support for moving said tool support relative to said workpiece along a second direction perpendicular to said first direction in accordance with a predetermined pattern of movement in said second direction;

first measuring means operatively associated with said tool holding unit for measuring said tool position with respect to said workpkece along said second direction with accuracy higher than that to which said second tool support drive means can respond, and for outputting a second direction position signal;

function generating means operatively connected to said first measuring means for receiving said second direction position signal from said first measuring means and producing a desired position signal corresponding to a desired tool position along said first direction;

second measuring means operatively associated with said tool holding unit for measuring said tool position with respect to said workpiece along said first direction with accuracy higher than that to which said first tool support drive means can respond, and for outputting a first position signal;

first comparing means operatively connected to said function generating means and second measuring means for receiving said desired position signal from said function generating means and for receiving said first position signal from said second measuring means, and for producing said fine displacing drive means control signal, representing a difference between said desired tool position and said tool position along said first direction and being operatively connected to said fine displacing drive means for controlling the operation of said fine displacing drive means for driving said tool holding unit while said first and second tool support drive means are operating; and

second comparing means operatively connected with said function generating means and second measuring means for receiving said desired position signal from said function generqting means and for receiving said first position signal from said second measuring means and for producing said tool support drive means control signal, in accordance with the difference between said desired position signal and said first position signal; and

computing means for adding said tool support drive means control signal to said desired position signal from said function generating means and being operatively connected to said tool support drive means for causing said tool support drive means to move said tool support relative to said workpiece along said first direction.

10. A precision system as in claim 9, wherein said second tool support drive means includes servo drive means for setting a feed rate of said tool in said second direction in accordance with said predetermined pattern of movement.

11. A precision system as in claim 9 wherein each of said first and second measuring means comprises a laser interferometer device.

12. A precision system as in claim 9, wherein said fine displacing means comprises a piezo-electric element.

13. A precision system as in claim 9, wherein said fine displacing controlling means comprises a drive circuit having a plurality of power transistors connected in series along their emitter-collector paths.

14. A precision system as in claim 9, wherein said function generating means comprises a data memory which stores said desired tool position in relation to said tool position along said second direction.

15. A precision system as in claim 9, wherein said first measuring means includes a counter which increments said second direction position signal when said tool is moved each predetermined distance in a direction perpendicular to said first direction, said second direction position signal being applied to said function generating means.

16. A precision system as in claim 9, wherein said function generating means produces an indication of the difference between a present said desired tool position and a next desired tool position.