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Microprocessor Control of Drilling Spindles

IP.com Disclosure Number: IPCOM000101629D
Original Publication Date: 1990-Aug-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 111K

Publishing Venue


Related People

Grant, SC: AUTHOR [+2]


Disclosed is a means to achieve improved control of the printed circuit panel drilling process through the application of a microprocessor per spindle.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Microprocessor Control of Drilling Spindles

       Disclosed is a means to achieve improved control of the
printed circuit panel drilling process through the application of a
microprocessor per spindle.

      The microprocessor per spindle provides a means to relate
previously decoupled process feedback parameters resulting in
adaptive control of the drilling process.  The microprocessor can
monitor a broad range of process parameters for error checking and
process feedback to a host controller.  Parallel network
communications allows a large number of spindle controllers to
communicate with a host controllers at a high rate of speed.

      In the figure a smart drilling spindle controller is shown to
consist of:  a microprocessor 1 for process monitoring a control; a
dedicated digital, servo controller 2 for vertical motion control;
network I/O 3 for host communications; a four-channel, 12-bit,
digital- to-analog converter 4 for analog display of process
parameters; local RAM 5 for variable process parameters; EPROM 6 for
local program storage; an RPM timer 7 for digital conversion of the
revolution period; direct I/O 8 for emergency stop, Z limits and top
reference; digital position feedback 9 for the Z servo; an amplifier
and summing junction 11 for producing a compensated Z motion command
12; and an address and data bus 13 for microprocessor communication
with peripheral components.

      The microprocessor (MPU) executes a program stored in the local
EPROM (Erasable Programmable Read Only Memory). Programmable process
parameters are received from the host over the network communications
bus and stored in the local RAM.  The network communications bus
allows up to 255 spindles to share the same 8-bit parallel bus.
Hardware interrupts are provided for emergency stop, + or - Z limit,
top panel reference (need for blind hole operations) and rpm pulse.

      The dedicated digital Z servo controller manages the vertical
motion of the spindle independent of the MPU.  The MPU can program
the servo controller for velocity, acceleration, sample rate, and
position.  The servo controller also provides programmable gain,
pole, and zero factors to customize the performance of each Z servo
and returns actual position on request.  The digital feedback
resolution is 1 rpm per count.

      The rpm sensor produces a pulse once per revolution. The period
between pulses is timed by the microprocessor to the near...