US 4,866,630 A · Programmable band saw and method of sawing

Abstract

A method of automatic sawing employs an automatic sawing machine having an automatic workpiece shuttle, shuttle and stationary vises, an automatic saw blade feed, one or more incremental motion encoders and a programmable microcomputer. The microcomputer is capable of storing a series of sawing jobs. Each job has a number of sawing steps. Each step in turn defines a sawed workpiece length and (in an embodiment employing a saw blade tilting mechanism) a sawing angle, both of which parameters may be different from those of other steps. The microcomputer receives signals from the motion encoders to determine shuttle and (in a tilt embodiment) tilt position and uses these positions to control shuttle, (in the tilt embodiment) tilt, and vise operation. The microcomputer also corrects each workpiece length with a saw kerf and pivot point correction factor, both modified for sawing angle. The microprocessor receives motion increment signals from the motion encoders which are decoded to determine the direction in which the increment was travelled, and which are decoded in a manner which increases conventional accuracy by four. An operator may simultaneously program one saw job while executing another.

Claims24

Dependent claims

In a method of automatic sawing, the steps of:

a. retaining the location of a first position of a workpiece shuttle movable between the first position and a plurality of second positions;
b. calculating a specific second position from a desired sawed workpiece length stored in memory means;
c. actuating the shuttle to move from the first position toward the specific second position;
d. using shuttle motion sensing means to encode a plurality of signals for each distance increment travelled by the shuttle;
e. processing the signals to periodically determine the position of the shuttle;
f. stopping the shuttle when the specific second position and the last determined shuttle position are substantially equivalent;
g. clamping the workpiece to the shuttle;
h. actuating the shuttle to move back to the located first position;
i. clamping the workpiece into a position to be sawed;
j. unclamping the workpiece from the shuttle;
k. sawing the workpiece;
and
l. repeating steps (b)-(l) for a plurality of sawing steps, the steps producing workpieces of possibly different lengths.

10 more elements

In a method of automatic sawing using saw blade tilting means, a workpiece shuttle, saw station clamping means, shuttle clamping means, and programmable calculator means in operative communication with the tilting means, clamping means and shuttle, the steps of:

a. programming the calculator means with a saw blade kerf value and a pivot point correction factor equal to the perpendicular distance between a saw blade tilt axis of tilt and a top surface of a saw station,
b. using the calculator means to store data for a plurality of sawing steps, the data for each step comprising
a sawing tilt angle and
a sawed workpiece length;
c. sensing and storing a first shuttle position in the calculator means;
d. commanding the saw blade tilting means to commence tilting a saw blade;
e. sensing a plurality of angular movement increments of the saw blade;
f. for each angular increment, transmitting a plurality of signals to the calculator means including a first signal and a second signal;
g. decoding the pulses by the order of receipt of the first and second signals by the calculator means to determine whether a positive or negative angular increment has been sensed;
h. processing the signals to periodically calculate a current tilt angle;
i. periodically comparing the current tilt angle to an angle calculated from the saw tilt angle and clamping the saw blade in an angularly fixed position when the current angle is substantially equal to said last angle;
j. modifying the sawed workpiece length as a function of the blade kerf value, pivot point correction factor, saw blade tilt angle and shuttle stroke to obtain a displacement between the first shuttle position and the second shuttle position;
k. moving the shuttle toward a second position;
l. sensing a series of shuttle displacement increments;
m. for each increment, sending a plurality of signals including a first signal and second signal to the calculator means;
n. decoding the signals by the order of receipt by the calculator means to determine whether an increment in the first direction or in the second direction has been sensed;
o. processing the shuttle displacement increment signals to find a current shuttle location;
p. comparing the shuttle location to the second shuttle position and actuating the shuttle clamping means to clamp the workpiece to the shuttle when the current shuttle location and the second shuttle position become substantially equivalent;
q. thereafter moving the shuttle to the first position;
r. opening the shuttle clamping means and actuating the saw station clamping means to clamp the workpiece;
s. sawing the workpiece, and retracting the saw blade after the cut is complete;
t. repeating steps (d)-(s) for each remaining stored saw step unless a stop command is issued or an abnormal condition occurs.

19 more elements

In a method of automatic sawing using an automatic workpiece shuttle, shuttle clamping means, saw blade tilting means, saw blade feed means, stationary clamping means, and programmable calculator means, in operable communication with the shuttle, clamping means, tilting means and feed means, the steps of:

a. entering in to the calculator means a saw kerf value, a pivot point correction factor and a saw program comprising a number of sawing steps, the data for each sawing step including a sawed workpiece length and a saw angle;
b. recording a first shuttle position;
c. actuating the blade tilting means to tilt the saw blade to the entered saw angle;
d. calculating a displacement to a second shuttle position from the first position from the entered sawed workpiece length as a function of shuttle stroke, saw kerf value, pivot point correction factor and the entered saw angle;
e. actuating shuttle movement means to move the shuttle away from the first position toward the second position;
f. periodically sensing the location of the shuttle;
g. deactivating the shuttle movement means and actuating shuttle clamping means to clamp the workpiece to the shuttle when the shuttle location becomes substantially equivalent to the second position;
h. opening the stationary clamping means;
i. actuating shuttle movement means to move the shuttle to the first position with the workpiece;
j. thereafter closing the stationary clamping means on the workpiece;
k. opening the shuttle clamping means;
l. actuating the saw blade feed means to saw the workpiece;
m. retracting the saw blade after it is sensed that the workpiece has been sawed;
n. repeating steps (b)-(m) for each of the remaining saw steps unless a stop command is received or unless an abnormal condition occurs.

11 more elements

An automatic sawing machine, comprising:

(a) a shuttle actuatable to move a workpiece in a first direction to a cutting position,
(b) means sensing incremental movement of the shuttle,
(c) means actuating at least one workpiece shuttle clamp,
(d) means actuating a plurality of stationary clamps to hold the workpiece while the workpiece is being cut,
(e) means reducing the rate of shuttle displacement,
(f) means actuating the tilting of a saw blade,
(g) means sensing incremental tilting motion of the saw blade,
(h) means reducing the rate of saw blade angular displacement,
(i) programmable calculator means operably connected to the sensing, actuating and rate reducing means;
the calculator means sensing a plurality of signals sent from the shuttle movement sensing means each time the shuttle moves an incremental distance, the pulses including a first signal and a second signal, the first signal at least partially preceding the second signal when the incremental movement is in the first direction and the second signal at least partially preceding the first signal when the incremental movement is in a second direction;
the calculating means determining the direction of the incremental movement by noting which of the first and second signal comes first, the calculator means processing the signals into first and second directional movement counts, the calculator means summing the number of first directional movement counts and summing the number of second directional movement counts, the calculator means periodically subtracting the second directional sum from the first directional sum in the course of periodically arriving at a current position of the shuttle;
the calculator means sensing a plurality of signals sent from the incremental blade tilting motion sensing means upon the sensing of each tilting motion increment, said last signals including a first signal and a second signal, the first signal at least partially preceding the second signal when the direction of movement is positive, the second signal at least partially preceding the first signal when the direction of movement for that increment is negative, the calculating means determining the direction of angular movement by noting which of the first signal and the second signal was first received;
the calculator means processing the signals into positive and negative angular movement counts and summing the positive angular movement counts and summing the negative angular movement counts, the calculator means periodically subtracting the negative counts from the positive counts in the course of periodically determining a current angle of blade tilt;
the calculating means being programmable with a shuttle creep length, a stop-look-ahead length, a shuttle deadband length, a tilt deadband angle, a saw kerf value, a pivot point correction factor, a tilt creep angle and a tilt stop-look-ahead angle;
the calculating means further being programmable with a plurality of sawing steps, each step including data specifying a sawed workpiece length and a sawing angle;
the calculator means, for each step, commanding the blade tilt actuating means to tilt the blade at a normal angular displacement rate until the angle of displacement between the sawing angle and the current angular position does not exceed the tilt creep angle;
the calculator means then for each step actuating the angular displacement rate reduction means to slow the rate of tilting of the blade;
the calculator means for each step disabling the blade tilt actuating means, allowing the blade to coast, when the angular displacement between the sawing angle and the current angular position does not exceed the tilt stop-look-ahead angle;
the calculator means for each step actuating means fixing the blade at the desired sawing angle when the angular displacement between the desired sawing angle and the current angular position does not exceed the tilt deadband angle;
the calculator means for each step calculating a corrected shuttle pull length from the sawed workpiece length and horizontal lengths derived from the saw kerf and the pivot point correction factor as functions of the sawing angle;
the calculator means actuating the shuttle to move in the second direction;
the calculator means actuating the shuttle displacement rate reduction means when the displacement between the current shuttle position and the end of the corrected pull length does not exceed the shuttle creep length;
the calculator means disabling shuttle movement actuating means and allowing the shuttle to coast when the displacement between the current shuttle position and the end of the corrected pull length does not exceed the shuttle stop-look-ahead length;
the calculator means commanding the shuttle clamp actuating means to clamp the workpiece to the shuttle when the displacement between the current shuttle position and the end of the corrected pull length does not exceed the shuttle deadband length;
the calculator means then actuating the stationary clamps to open;
the calculator means thereafter for each step commanding the shuttle to move the workpiece in the first direction by an amount equal to the corrected pull length;
the calculator means thereafter for each stop actuating the stationary clamps to clamp the workpiece, and actuating the shuttle clamp to unclamp the workpiece;
the calculator means thereafter for each step commanding blade feed means to saw the workpiece.

25 more elements

In an automatic sawing machine with means to automatically control at least one workpiece shuttle to convey a workpiece to a sawing station, at least one shuttle workpiece clamping means selectively actuatable to clamp a workpiece to the shuttle, a plurality of stationary workpiece clamping means selectively actuatable to clamp the workpiece in sawing position, blade feed means selectively actuable to saw the workpiece and blade tilt means selectively actuatable to tilt a saw blade to a sawing angle, the improvement comprising

a. means sensing the motion of the shuttle,
b. means sensing the tilting motion of the saw blade,
c. means reducing the rate of shuttle movement,
d. means reducing the rate of tilt of the blade,
e. at least one programmable calculator means in operable communication with said controlling, sensing and rate-reducing means, and
f. data entry means and memory means in operable communication with the calculator means, the memory means capable of storing a plurality of sawing steps, each step having a sawed workpiece length and a sawing angle;
the calculating means controlling the shuttle and tilt mechanism control means, the force reducing means and receiving data from the sensing means to serially perform each programmed sawing step as long as normal operating conditions obtain;
the memory means also storing a saw blade kerf, a pivot point correction factor equivalent to the distance between a surface of the sawing station and the blade tilt axis measured as a perpendicular to the surface, a shuttle creep length, a shuttle stop-look-ahead length, a shuttle deadband length, a tilt creep angle, a tilt stop-look ahead angle and a tilt deadband angle,
for each sawing step, the calculator means deriving a corrected shuttle pull length from the stored sawed workpiece length and from lengths parallel to the sawing station surface derived from the saw blade kerf and pivot point correction factor as functions of the sawing angle;
for each sawing step, the calculator means commanding the shuttle control means to move the shuttle in a first direction;
for each sawing step, the calculator means periodically using the shuttle motion sensing means to determine a current shuttle position relative to the end of the shuttle stroke, the shuttle stroke being equal to the corrected shuttle pull length;
for each sawing step, the calculator means actuating the shuttle movement rate reduction means when the difference between the shuttle stroke end and the current shuttle position does not exceed the shuttle creep length;
for each sawing step, the calculator means disabling shuttle drive means, allowing the shuttle to coast, when the difference between the shuttle stroke end and the current shuttle position does not exceed the shuttle stop-look-ahead length;
for each sawing step, the calculator means commanding the shuttle clamping means to close when the difference between the shuttle stroke end and the current shuttle position does not exceed the shuttle deadband length;
for each sawing step, the calculator means thereafter actuating the stationary clamping means to open and actuating the shuttle to move in a second direction for a distance equal to the corrected pull length, the calculator means then closing the stationary clamping means and opening the shuttle clamping means;
for each sawing step, the calculator means actuating the tilt means to tilt the saw blade, the calculator means periodically using the tilt sensing means to determine a current tilt angle;
for each sawing step, the calculator means reducing the rate of blade tilt when the difference between the sawing angle and the current tilt angle does not exceed the tilt creep angle;
for each sawing step, the calculator means disabling tilt drive means, allowing the blade to angularly coast, when the difference between the sawing angle and the current position does not exceed the tilt stop-look-ahead angle;
for each sawing step, the calculator means commanding angular blade affixing means to fix the blade at the sawing angle when the difference between the sawing angle and the current position does not exceed the tilt deadband angle;
for each sawing step, the calculator means thereafter actuating the blade feed means to saw the workpiece.

17 more elements

Dependencies are inferred from the claim text.

Programmable band saw and method of sawing

Life of this patent

Programmable band saw and method of sawing

Life of this patent

Abstract

Claims24