RIGID TAPPING FEEDBACK ASSEMBLY FOR A MILLING MACHINE

• US 20090016833A1
• Filed: 07/12/2007
• Published: 01/15/2009
• Est. Priority Date: 07/12/2007
• Status: Active Grant

• Current Assignee: Dwayne S. Elrod, Elizabeth A. Domokos-Elrod
• Original Assignee: Dwayne S. Elrod, Elizabeth A. Domokos-Elrod
• Inventors: ELROD, DWAYNE S.
• Granted Patent: US 7,972,097 B2
• Time in Patent Office: Days
• US Class Current: 408/102
• CPC Class Codes: B23Q 17/10 for indicating or measuring cutting speed or number of revolutions
• CPC Class Codes: B23Q 5/043 Accessories for spindle drives
• CPC Class Codes: Y10T 29/49716 Converting
• CPC Class Codes: Y10T 408/17 to control infeed
• CPC Class Codes: Y10T 408/172 Responsive to Tool
• CPC Class Codes: Y10T 408/5628 Tool having screw-thread engaging frame to cause infeed
• CPC Class Codes: Y10T 408/67 Belt and pulley
• CPC Class Codes: Y10T 409/306888 In response to cutter condition
• CPC Class Codes: Y10T 409/307784 Plural cutters
• CPC Class Codes: Y10T 409/309352 Cutter spindle or spindle support

Abstract

This invention is related to a rigid tapping feedback assembly that is adapted to being retrofit on a milling machine having a spindle with a spindle end extending beyond a bearing cap and an automated drive. In embodiments, the assembly comprising a housing, spindle-pulley adapter that is drivably engaged with the spindle end, pulley assembly, shaft assembly, housing cover plate, and rotary encoder. The housing mounts to the bearing cap and holds the shaft assembly in substantially parallel-spaced alignment with the spindle-pulley adapter. The pulley assembly mechanically links the spindle-pulley adapter and the shaft assembly, typically utilizing pulleys and a timing belt. The housing cover plate mounts to the housing enclosing the assembly components above and supporting the rotary encoder in substantial axial alignment with the shaft assembly. In operation, the rotary encoder senses spindle rotational speed spindle and provides feedback to the automated drive to control downward movement of the spindle.

Claims

1. A rigid tapping feedback assembly for a milling machine having a spindle with a spindle end machined on one end and a tool attached on the opposed end, a computing device operably connected to an automated drive to that translates the spindle in a Z-axis, and milling machine motor that rotates the spindle at a rate of revolution, the rigid tapping feedback assembly comprising:

a spindle-pulley adapter that is drivably engaged to the spindle end;

a housing that is fixedly attached to the milling machine;

a sensor shaft that rotatably coupled to the housing, the housing supporting the sensor shaft in substantial parallel-spaced relation to the spindle-pulley adapter;

a pulley assembly that mechanically links the spindle-pulley adapter and the sensor shaft, wherein the rate of revolution of the spindle is generally proportional to resultant angular rotation of the sensor shaft; and

a sensor configured to monitor the resultant angular rotation of the sensor shaft, wherein the sensor communicates an indication of the resultant angular rotation to the computing device.

2. The rigid tapping feedback assembly of claim 1, further comprising a housing cover plate fixedly attached to the housing, where the attached housing cover plate and housing substantially encompass the drive assembly.

3. The rigid tapping feedback assembly of claim 2, wherein the housing cover plate supports the sensor in substantial axial alignment with the sensor shaft.

4. The rigid tapping feedback assembly of claim 1, wherein the housing is fixedly attached to a bearing cap of the milling machine, the bearing cap configured with an aperture to receive the spindle end extending therethrough.

5. The rigid tapping feedback assembly of claim 4, wherein the housing cover plate includes a mounting footprint, the mounting footprint is adapted to receive fasteners for attaching a drawbar to the housing cover plate.

6. The rigid tapping feedback assembly of claim 5, wherein the spindle-pulley adapter that is drivably engaged to the spindle end is interconnected between the spindle and the draw bar.

7. The rigid tapping feedback assembly of claim 1, wherein the sensor is a rotary encoder, the rotary encoder is rotatably engaged with the sensor shaft.

8. The rigid tapping feedback assembly of claim 7, wherein, incident to the rotary encoder communicating an indication of the resultant angular rotation of the sensor shaft, the computing device is configured to determine a derived rate of revolution based upon the indication of the resultant angular rotation of the sensor shaft.

9. The rigid tapping feedback assembly of claim 8, wherein, incident to the rotary encoder communicating the indication of the angular rotation of the sensor shaft, the computing device compares the derived rate of revolution against the rate of revolution provided by the milling machine motor and directs the automated drive to adjust the translation of the spindle in the Z-axis.

10. The rigid tapping feedback assembly of claim 1, wherein the pulley assembly that mechanically links the spindle-pulley adapter and the sensor shaft is comprised of:

a first pulley circumferentially engaged to the spindle-pulley adapter;

a second pulley circumferentially engaged to the sensor shaft; and

a belt coupling the first pulley and second pulley such that the spindle-pulley adapter and spindle shaft rotate concurrently.

11. The rigid tapping feedback assembly of claim 10, wherein the belt is a timing belt having teeth, wherein the pulleys each include outer radial surfaces having teeth that engaged with the teeth of the timing belt.

12. A milling machine, comprising:

a spindle with a spindle end machined on one end and a tool attached to the opposed end, wherein the spindle is configured to rotate at a rate of revolution;

an automated quill drive that translates the spindle in a Z-axis at an extension rate;

a CNC controller that is operably connected to the automated quill drive;

wherein the CNC controller is configured to control the extension rate of the automated quill drive;

a milling machine motor that rotates the spindle at an initial rotational speed;

a spindle-pulley adapter that is drivably engaged to the spindle end;

a housing that is fixedly attached to the milling machine;

an encoder shaft that is rotatably coupled to the housing, the housing supporting the encoder shaft in substantial parallel-spaced relation to the spindle-pulley adapter;

a pulley assembly that comprises a drive pulley circumferentially engaged to the spindle-pulley adapter, an encoder pulley circumferentially engaged to the encoder shaft, and a belt that mechanically links the drive pulley and encoder pulley, wherein the rate of revolution is of the spindle-pulley adapter is tracked by angular rotation of the encoder shaft; and

a rotary encoder that utilizes the encoder shaft to sense the angular rotation of the encoder shaft.

13. The milling machine of claim 12, further comprising a bearing that rotatably couples the encoder shaft to the housing.

14. The milling machine of claim 13, further comprising a shaft adapter having arcuate slots configured to receive fasteners, the shaft adapter is circumferentially engaged to the bearing and adjustably mounted to the housing with the fasteners, wherein lateral movement of the shaft adapter independent of the housing introduces or removes tension from the belt.

15. The milling machine of claim 12, wherein the drive pulley and the shaft pulley include outer radial surfaces having notches, wherein the belt is a timing belt having notches that engage with the notches on the outer radial surfaces.

16. The milling machine of claim 12, wherein the rotary encoder provides an output signal indicative of the angular rotation to the CNC controller, the CNC controller is configured to receive the output signal from the rotary encoder and determine the rate of revolution therefrom.

17. The milling machine of claim 15, wherein the circumference of the outer radial surfaces of the drive pulley and the shaft pulley are similar such that the rate of revolution of the spindle-pulley adapter and the angular rotation of the spindle-pulley adapter differ by less than one rotation per minute.

18. The milling machine of claim 12, further comprising a cover plate fixedly attached to the housing to a create a protective body, the protective body substantially encompassing the pulley assembly.

19. The milling machine of claim 18, further comprising a drawbar mounted to the cover plate, the cover plate having an aperture for receiving a portion of the spindle-pulley adapter, the portion of the spindle-pulley adapter drivably engaged with the drawbar.

20. A method for controlling an extension rate of a spindle utilizing feedback of a rate of revolution of the spindle to a CNC controller on a milling machine, the method comprising:

retrofitting a milling machine with a rotary sensor;

monitoring the spindle whereby the rotary encoder senses the rate of revolution of the spindle;

communicating an indication of the rate of revolution from the rotary encoder to the CNC controller, wherein the CNC controller is configured to compare the indication of the rate of revolution with an operator-provided initial rate of rotation and determine the rate of extension based upon the comparison;

receiving the a signal from the CNC controller containing an indication of the determined rate of extension at an automated quill drive; and

extending the spindle, utilizing the automated quill drive, according to the determined rate of extension.