Information
-
Patent Grant
-
6331133
-
Patent Number
6,331,133
-
Date Filed
Monday, October 5, 199826 years ago
-
Date Issued
Tuesday, December 18, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Eley; Timothy V.
- Berry, Jr.; Willie
Agents
-
CPC
-
US Classifications
Field of Search
US
- 451 5
- 451 9
- 451 10
- 451 259
- 451 293
- 451 375
-
International Classifications
-
Abstract
A method and apparatus for automatically re-pointing twist drill bits includes a drill support mechanism including means for rotatably and axially translatably holding the shank of a drill bit, and a fluted portion receiver for supporting the fluted front cutting portion of the drill bit. The apparatus also includes an optical sensor unit which views the tip and blade part of the drill bit with the drill support mechanism in an off-line position, i.e., rotated away from a grinding wheel station. Responsive to error correction servo command signals received from a comparison of the actual orientation of drill bit cutting lips with a desired pre-determined template position, rotary and linear actuators in the drill support mechanism rotate the drill bit to the proper angular orientation, and advance the bit axially to a pre-determined protrusion length. Also, command signals to the fluted portion receiver elevate the drill bit point to a pre-determined elevation, whereupon a linear actuator cylinder linked via a pivot pin to the drill support mechanism rotates the latter to thereby place the properly oriented drill bit in contact with grinding wheels of a sharpening unit. After each of the grinding wheels has sequentially contacted the cutting edges and point of the drill bit and resurfaces the contacted areas to a desired sharpness, the linear actuator cylinder is used to rotate the drill support mechanism to the off-line position, whereupon a shank retainer is pivoted vertically away from the drill bit shank, allowing the re-conditioned bit to be removed and replaced with another bit to be re-pointed.
Description
BACKGROUND OF THE INVENTION
A. Field of the Invention
The present invention relates to devices and methods for sharpening or re-pointing twist drill bits. More particularly, the invention relates to an apparatus for automatically re-pointing twist drill bits.
B. Description of Background Art
Printed wiring boards (PWB's) used to hold and electrically interconnect electronic circuit components are typically fabricated as laminated stacks of copper foil sheets alternating with insulating sheets made of fiberglass, the latter containing glass fibers solidified with a resin such as epoxy. The glass fibers are highly abrasive, and can quickly dull drill bits used to drill holes in the PWB for receiving component leads, or for forming passageways or vias through the PWB. A typical PWB has a thickness of about 0.062 inch, and has hundreds of holes drilled through it. Each contact with the upper surface of a PWlB to drill a hole is referred to as a “hit.” Since PWB's are usually arranged in stacks of two to five boards for drilling, a corresponding number of holes are drilled for each hit. Because the abrasive nature of the PWB board materials dulls typical drill bits after about 3000-5000 holes are drilled, the drill bit must be removed from service and re-sharpened after about 1,500-2,000 hits.
In conventional drill bit grinding apparatuses used to sharpen or re-point twist drill bits, the drill bit must be held in a chuck. Consequently, the operator must manually perform operations such as inserting the drill into the chuck of a drill bit holder mechanism, tightening the chuck to grip the drill, positioning or aligning the drill in relation to the drill bit holding mechanism and to a rotary grinding stone, advancing the drill bit towards a grindstone, retracting the re-pointed drill bit from the grindstone and removing the re-pointed drill bit. Because of all of the aforementioned operations, an operator can usually operate only a single drill bit grinding apparatus at a time. Thus, even an experienced operator can typically re-point no more than about 800 to 1,000 drill bits over an eight-hour work shift Therefore, there has been a strong demand for an automated drill bit re-pointing apparatus that has a higher throughput rate than existing re-pointing apparatuses, and which may be operated by less than highly skilled personnel. Despite a widespread need for an improved drill bit re-pointing apparatus, various difficulties have prevented the development of such an apparatus. The present invention was conceived of to provide an improved, automatic drill bit re-pointing apparatus in which functions performed manually in prior art devices are largely automated.
OBJECTS OF THE INVENTION
An object of the present invention is to provide an automatic apparatus for sharpening or re-pointing twist drill bits.
Another object of the invention is to provide a drill bit re-pointing apparatus which includes means for automatically aligning a drill bit with respect to a grinding wheel.
Another object of the invention is to provide a drill bit re-pointing apparatus having a drill bit holder mechanism which facilitates attachment of the drill bit to the apparatus for grinding, and removal of the bit upon completion of grinding.
Another object of the invention is to provide a drill bit re-pointing apparatus having a drill bit holder which incorporates means for rotating the bit about its longitudinal axis to a desired phase angle to orient the fluted, front cutting portion of the bit to a desired disposition relative to a grinding wheel.
Another object of the invention is to provide a drill bit re-pointing apparatus having fluted portion support means translatable transversely or perpendicularly relative to the longitudinal axis of the bit, between a position contacting the fluted portion of drill bits of various diameters and a non-contacting position.
Another object of the invention is to provide a drill bit re-pointing apparatus having a drill bit holder mechanism which includes means for axially advancing a drill bit to position the point of the bit at a desired extension distance from the holder mechanism.
Another object of the invention is to provide a drill bit re-pointing apparatus which includes means for aligning the phase angle and longitudinal protrusion or extension of a drill bit tip relative to an optical alignment device at a first, load/unload station, rotating the drill bit holder mechanism to second, grinding station where drill bit grinding stones grind the properly phased and extended drill bit, and rotating the drill bit holder back to the first load/unload station to permit the re-pointed drill bit to be removed from the apparatus.
Another object of the invention is to provide a drill bit re-pointing apparatus which includes a drill bit holder which has a pivotable shank retainer which may be pivoted upwards to allow the shank of a drill bit to be placed on a pair of phase-controlling roller wheels, and which may be pivoted downwardly to retain the shank in rotatable contact with the roller wheels.
Various other objects and advantages of the present invention, and its most novel features, will become apparent to those skilled in the art by perusing the accompanying specification, drawings and claims.
It is to be understood that although the invention disclosed herein is fully capable of achieving the objects and providing the advantages described, the characteristics of the invention described herein are merely illustrative of the preferred embodiments. Accordingly, we do not intend that the scope of our exclusive rights and privileges in the invention be limited to details of the embodiments described. We do intend that equivalents, adaptations and modifications of the invention reasonably inferable from the description contained herein be included within the scope of the invention as defined by the appended claims.
SUMMARY OF THE INVENTION
Briefly stated, the present invention comprehends an apparatus for sharpening or re-pointing twist drill bits, in which functions required in the re-pointing process are largely automated.
An automatic drill bit re-pointing apparatus according to the present invention includes a drill bit holder mechanism having a rear, shank holder structure and a front, fluted holder structure which is actuable from a lowered, rear non-contacting position to a raised position contacting and supporting the fluted front portion of drill bits of various diameters. The drill bit holder mechanism includes a motor-driven shank retainer which is pivotable upwardly to a first position allowing placement of a drill bit in the apparatus, and removal of the bit after it has been re-pointed, and pivotable downwards to a second position bearirg against the shank of the drill bit to thereby secure the bit in the holder mechanism. The drill bit holder mechanism also includes a pair of laterally adjacent, “phase control” rollers which support the lower portion of a drill bit shank, the rollers being motor driven to permit rotating the bit about its longitudinal axis to a particular orientation or phase angle of the cutting lips of the fluted front cutting portion of the bit. A motor-driven lead screw in the drill bit holder mechanism pushes against the rear shank face of a drill bit in the holder mechanism to advance the drill bit axially with respect to the phase control rollers to a desired protrusion length or extension distance from the holder mechanism.
According to the present invention, the drill bit holder mechanism is pivotably mounted on a spindle rotatable by means of a connecting link coupled to a station position linear actuator cylinder from a first, load/unload station position to a second, grinding station position. At the load/unload station is located an optical alignment apparatus including an optical imaging unit that has an objective lens longitudinally aligned with and spaced outwards from the tip or point of a drill bit held in the drill bit holder mechanism. The optical imaging unit includes a CCD camera, on the focal plane of which is formed an image of the tip of the drill bit. The image is displayed on a monitor and also transmitted to an optical pattern recognition computer which outputs command signals to the phase control roller drive motor that rotates the bit to a desired phase angle or orientation suitable for contacting grinding wheels at a grinding station.
The optical alignment apparatus also includes an electro-optical drill bit point extension sensor located between the optical imaging apparatus and the drill bit holder mechanism. Output signals from the extension sensor drive the lead screw motor to advance the drill bit axially in the holder to a pre-determined longitudinal extension distance therefrom.
When the drill bit phase angle and extension have been automatically adjusted as described above, the station position actuator is energized to pivot the drill bit holder mechanism from the first, load/unload station position to the second, grinding station position at which is located a plurality of rotating grinding stones which sequentially sharpen various surfaces of the drill bit, including the chisel point and lips or cutting edges of the drill bit flutes. During the sharpening process, a controller device inputs command signals to the phase rotating rollers which rotate the bit at a predetermined rate from its initial position adjusted at the load/unload station. Upon completion of the sharpening process, the bit holder mechanism is pivotably rotated back to the first, loadlunload station. Then, the shank retainer motor is operated to pivot the shank retainer away from the re-pointed drill bit, allowing the latter to be removed and replaced with another bit to be re-pointed. By utilizing a robotic arm or similar device to load and unload drill bits from the apparatus, drill bits may be re-pointed completely automatically.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG.
1
(
1
) is a partly sectional upper plan view of a drill bit holder mechanism comprising part of an automatic drill bit re-pointing method and apparatus according to the present invention.
FIG.
1
(
2
) is a partly sectional side elevation view of the mechanism of FIG.
1
(
1
).
FIG. 2
is a side elevation view of an automatic drill bit re-pointing apparatus according to the present invention.
FIG. 3
is a fragmentary side elevation view of the apparatus of
FIG. 2
on a somewhat enlarged scale, and showing the drill bit holder mechanism thereof pivoted from a first, load/unload/align station position indicated by solid lines, to a second, grinding station position indicated by phantom lines.
FIG. 4
is a fragmentary front elevation view of the drill bit holder mechanism of
FIG. 1
, showing details of a blade receiver portion of the mechanism used to support the front, fluted blade portion of a drill bit.
FIG. 5
is a view similar to that of
FIG. 4
, showing an alternate embodiment of a blade receiver.
FIG. 6
is a partly sectional side elevation view of the mechanism of FIG.
1
(
1
), but showing sections removed in addition to those removed in FIG.
1
(
2
).
FIG. 7
is a fragmentary front sectional view of the mechanism of FIG.
1
(
1
), showing details of the phase control device thereof.
FIG. 8
is a view similar to that of
FIG. 7
, but showing a first variation of the phase control device thereof.
FIG. 9
is a view similar to that of
FIG. 7
, but showing a second variation of the phase control device thereof.
FIG. 10
is a fragmentary side elevation view of the apparatus of
FIG. 2
, showing the relative arrangement of an optical alignment apparatus and sharpening unit thereof.
FIG. 11
is a front elevation view of the optical alignment apparatus portion of the re-pointing apparatus shown in FIG.
2
.
FIG. 12
is a front elevation of a drill bit tip as viewed on a monitor connected to the optical alignment apparatus of
FIGS. 2 and 11
.
FIG. 13
is a fragmentary upper plan view of a modification of the apparatus of
FIG. 1
, showing a modified shank retainer thereof pivoted upwards to permit a drill bit to be loaded or unloaded from the apparatus.
FIG. 14
is an oblique view of the structure of FIG.
13
.
FIG. 15
is a side elevation view of the structure of FIG.
14
DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIGS. 1-15
illustrate various features of an automatic drill bit re-pointing apparatus according to the present invention.
Referring first to
FIG. 2
, an automatic drill bit re-pointing apparatus
10
according to the present invention may be seen to include a support structure
34
to which is pivotably attached a drill bit holder mechanism
12
. Automatic drill bit re-pointing apparatus
10
also includes an optical alignment apparatus
30
fastened to an optical bench
36
, which is in turn fastened to support structure
34
of the apparatus. Optical alignment apparatus
30
includes a telescope
32
that images the point or tip of drill bit
18
on the focal plane of a CCD camera
38
, for ascertaining the angular orientation or phase of the cutting edges or lips of a drill bit held in holder mechanism
12
. Apparatus
30
also includes an optical tip position sensor
40
for ascertaining the protrusion distance longitudinal extension of the drill bit tip relative to drill bit holder mechanism
12
.
As shown in sold lines in
FIG. 2
, drill bit holder mechanism
12
of automatic drill bit re-pointing apparatus
10
is located at a first, load/unload/align station position at which drill bits may be loaded or attached to the drill bit holder mechanism and aligned properly by means of optical alignment apparatus
30
, in a manner to be described in detail below. Then, drill bit holder mechanism
12
is pivoted to a second, sharpening station location indicated by dashed lines, by a linear actuator
16
coupled by a coupling link
26
to a pivot pin or spindle
22
. At the sharpening station, the drill bit is contacted by grinding wheels of a sharpening or grinding unit
14
. Upon completion of the grinding or re-pointing process, drill bit holder mechanism
12
is pivoted back to the first, load/unload/align station by operation of linear actuator
16
. Here the re-pointed drill bit may be removed and replaced by another bit to be re-pointed.
Referring now to FIGS.
1
(
1
) and
1
(
2
), it may be seen that drill bit holder mechanism
12
includes a generally flat, longitudinally elongated base plate
20
. A pivot pin or spindle
22
disposed laterally near the rear edge wall of the plate is secured to the underside of the plate. As shown in
FIG. 2
, opposite lateral ends of spindle
22
are rotatably secured in a pair of opposed bushings
24
fastened to apparatus support structure
34
.
Referring still to FIGS.
1
(
1
) and
1
(
2
), it may be seen that drill bit holder mechanism
12
of apparatus
10
includes a motor mounting plate
42
which protrudes perpendicularly upwards from base plate
20
of the mechanism. Attached to motor mounting plate
42
is a drill bit tip axial position controller motor
44
which powers a lead screw-type linear tip position actuator mechanism used to advance drill bit
18
in the direction of its longitudinal axis. Also attached to motor mounting plate
42
is a phase controller motor
46
which powers a rotary flute orientation actuator used to rotate drill bit
18
around its longitudinal axis. As shown in FIG.
1
(
1
), drill bit holder mechanism
12
also includes a linear shank holder actuator cylinder
48
which is preferably a pneumatic cylinder, and has a piston rod
76
which is longitudinally slidably disposed through motor mounting plate
42
. The remaining structural components and functions of the three aforementioned actuators are described in detail below.
Referring again to FIGS.
1
(
1
) and
1
(
2
), it may be seen that drill bit holder mechanism
12
includes a drill bit shank holder block
50
which protrudes perpendicularly upwards from upper surface
21
of base plate
20
. Shank holder block
50
is located longitudinally forward of actuator motor mounting plate
20
, and rearward of the front transverse edge wall of base plate
20
. Referring to
FIGS. 6 and 7
in addition to FIGS.
1
(
1
) and
1
(
2
), it may be seen that shank holder block
50
supports a pair of parallel, laterally spaced apart and aligned spindles
52
which are rotatably supported by bearing (not shown) within the block, and which protrude longitudinally forward from the front surface of the block. Near the front end of each rotatable spindle
52
is attached a circular disk-shaped roller
154
having an outer circumferential surface made of rubber. As may be seen best by referring to
FIG. 7
, the inner facing surface of rollers
54
are spaced very slightly apart from one another, thus forming an arcuately curved, generally V-shaped recess
55
between the upper portion of the rollers which may receive the shank of a drill bit
18
. As shown in
FIGS. 1 and 2
, drill bit
18
is placed on rollers
54
with the shank of the bit protruding rearward towards shank holder block
50
.
Referring now to
FIG. 4
in addition to
FIGS. 1 and 2
, it may be seen that drill bit holder mechanism
12
includes a front fluted portion receiver
56
for supporting the front fluted portion of a drill bit
18
. Fluted portion receiver
56
includes an arm
57
which protrudes obliquely upwardly from a support block
58
, and has at the upper end thereof a fluted portion support flange
59
adapted to support the lower surface of the front, fluted cutting portion of a drill bit
18
held in holder mechanism
12
. Support block
58
is attached to the upper end of a vertically disposed fluted portion receiver actuator
60
, which is in turn fastened to support plate
20
. By energizing actuator
60
, fluted portion receiver
56
may be moved up and down, as indicated by arrows
62
in
FIG. 4
, to support the front fluted portion of drill bits of various diameters.
FIG. 5
illustrates an alternate mechanism
65
for raising and lowering fluted portion receiver
56
. Alternate mechanism
56
includes a pivot arm
64
which is attached at the upper end thereof to fluted portion receiver
56
. A side of the lower end of pivot arm
64
bear's tangentially against the outer surface of a cam
66
driven by a motor (not shown). Thus, when the cam is driven by the motor, pivot arm
64
pivots in the direction indicated by arrows
68
in
FIG. 5
, raising or lowering fluted portion receiver
56
.
Referring again to FIG.
1
(
2
), it may be seen that drill bit holder mechanism
12
includes a finger-like shank retainer
70
. As shown by arrows
74
in FIG.
1
(
2
), shank retainer
70
may be pivoted in a vertical plane between an upper, non-contacting position allowing loading and unloading of a drill bit
18
into drill bit holder mechanism
12
, and a lower position in which the “finger tip” of the shank retainer bears against the upper surface of the shank of a drill bit
18
, thus pressing the shank against phase controller rollers
54
, (see FIG.
1
-(
1
)), and thereby securing the drill bit in the holder. Drill bit holder mechanism
12
includes components described below which cooperate with shank retainer actuator cylinder
48
to pivot shank retainer
70
between an upper, load/unload position to a lower, shank retaining position.
Thus, as shown in FIG.
1
-(
1
), a piston rod
76
protrudes forward from actuator cylinder
48
through motor mounting plate
42
, and is coupled at the front end thereof through a first crank arm-link structure
82
to an intermediate longitudinal location of an operating spindle or first pivot shaft
80
, which is rotatably mounted about its longitudinal axis relative to drill bit shank retainer block
50
. First pivot shaft
80
in turn is coupled at an inner longitudinal location thereof, nearer shank retainer block
50
, by a second, inner crank arm-link structure
82
to a first, left side longitudinal support arm
72
L for shank retainer finger
70
. Pivot arm
72
L and a counterpart support arm
72
R are disposed parallel to left and right sides of shank retainer support block
50
, respectively, and are fastened to opposite lateral ends of a second pivot rod
73
that is transversely disposed through the shank retainer block, and rotatably supported therein. Attached to the front ends of arms
72
L,
72
R is a transversely disposed cross arm
85
. Shank retainer finger
70
is fastened to the center of cross arm
85
. Therefore, when shank retainer actuator cylinder
48
is energized, coupling link structure
78
causes operating spindle
80
to rotate, rotational motion of which is transferred through coupling link structure
82
to the rear end of left longitudinal shank retainer support arm
72
L. Downward pivotal motion of the rear end of shank retainer longitudinal support arm
72
L causes the longitudinal support arm to pivot upwards about pivot rod axle
73
, which in turn causes the front end of support arm
72
L, cross arm
85
and shank retainer finger
70
to pivot upwardly away from the shank of drill bit
18
. Conversely, actuation of linear actuator cylinder
48
in the opposite direction causes shank retainer finger
70
to pivot downwardly and bear against the shank of drill bit
18
.
FIG. 6
illustrates the structure and function of components which cooperate with drill bit tip axial position controller motor
44
to extend the point of a drill bit
18
to a desired protrusion length or extension distance relative to fluted portion receiver
56
. As shown in
FIG. 6
, axial tip position controller motor
44
has a shaft
89
which protrudes forward through actuator motor mounting plate
42
, the shaft having a drive gear
84
pinned to the front end of the shaft. Drive gear
84
is a spur gear having longitudinally disposed teeth that slidably mesh with teeth of a driven gear
88
pinned to the rear end of a spindle
86
. Spindle
86
has an enlarged diameter. longitudinally centrally located mid-section
90
which has a helically threaded outer surface. Threaded mid-section
90
of spindle
86
is threadingly engaged within an internally threaded bore
91
disposed longitudinally through drill bit shank holder block
50
. Thus, when motor
44
turns drive gear
84
, driven gear
88
threadingly advances or retracts mid-section
90
Of spindle
86
in threaded bore
91
, depending upon whether motor shaft
89
rotates clockwise or counterclockwise. Since gears
84
and
88
are spur gears, relative longitudinal sliding movement between the gears may occur while torque is transmitted through the meshed gears to spindle
86
.
As shown in
FIG. 6
, bore
91
through shank holder block
50
is coaxially aligned with a drill bit
18
supported on phase control rollers
54
. When a drill bit
18
is initially loaded into drill bit holder mechanism
12
, motor
44
is commanded to fully retract spindle
86
in bore
91
, allowing the shank of the bit to be inserted some distance into bore
91
until the rear face of the shank abuts the front face of spindle
86
. With this arrangement, motor
44
may be powered for a duration sufficient to advance spindle
86
and bit
18
axially forward until the point
132
of the bit protrudes a desired distance from fluted portion receiver
56
.
FIG. 6
also illustrates components of holder mechanism
72
which cooperate with phase controller motor
46
to rotate a drill bit
18
about its longitudinal axis to a predetermined angular orientation of the cutting lips of the drill bit.
Thus, as shown in
FIG. 6
, phase controller motor
46
has a shaft
97
which protrudes forward through actuator motor mounting plate
42
, the shaft having a drive gear
92
pinned to the front end of the shaft. Drive gear
92
is a spur gear having longitudinally disposed teeth that mesh with teeth of a driven gear
96
pinned to the rear end of an axle shaft
52
. Axle shaft
52
is rotatably supported in drill bit shank holder block
50
, and protrudes forward through the drill bit shank holder block, beyond the front wall surface thereof. As shown in
FIG. 7
, a driver roller
98
is pinned to the front end of axle shaft
52
, and tangentially contacts a pair of adjacent phase control rollers
54
. Thus, when axle shaft
52
and driver roller
98
are rotated in a clockwise direction by phase controller motor
46
, contact of the driver roller with phase control rollers
54
causes the latter to rotate in the opposite, i.e., counterclockwise direction. Also, tangential contact between phase control rollers
54
and the shank of a drill bit
18
pressed downwardly into recess
55
between the rollers causes the shank to rotate in a direction opposite to that of the rollers, i.e., in a clockwise sense. Thus, drill bit
18
may be rotated in a clockwise or counterclockwise direction to a desired angular orientation by electrically powering phase controller motor
46
to rotate in a clockwise or counterclockwise direction.
FIG. 8
illustrates a first variation of the phase control device depicted in FIG.
7
and described above. In this first variation, the shank of a drill bit
18
is pressed into contact with a pair of adjacent idler rollers
102
made of a metal or the like. The upper surface of drill bit shank
18
is pressed against by a friction pad
108
disposed laterally on the underside of a laterally disposed, phase adjusting drive arm
106
movable in a lateral direction by a linear actuator (not shown). When drive arm
106
is moved forward to the left or back to the right, as shown by the arrows
104
; drill bit
18
is caused to rotate in a counterclockwise or clockwise sense, respectively.
FIG. 9
illustrates a second variation of a phase control device, which is substantially similar in structure and function to the device depicted in FIG.
8
and described above. However, in the device depicted in
FIG. 9
, idler rollers
102
are replaced by a block
110
having in the upper surface thereof a V-shaped groove for rotatably receiving the shank of a drill bit
18
.
FIG. 10
illustrates structural details of sharpening unit
14
. As shown in
FIG. 10
, sharpening unit
14
has a primary rotating sharpening stone
112
which sharpens a first tip surface of a drill bit
18
, and a secondary sharpening stone
114
which sharpens a second tip surface. Sharpening stones
112
,
114
are installed on rotary drive motors
116
,
118
, respectively, the spin axes of which are inclined at different angles with respect to the longitudinal axis of a drill bit
18
to an orientation suitable for sharpening the first and second surfaces of the drill bit tip. In addition, sharpening stones
112
,
114
are arranged on a table
120
which is made to tilt against the drill bit
18
, with a traversing structure (not shown) which moves sharpening stone driver motors
1
16
,
11
8
, with respect to the table
120
, as shown by arrows
122
.
The structure and function of optical alignment apparatus
30
of drill bit re-pointing apparatus
10
, may be best understood by referring to
FIGS. 2
,
11
and
12
.
As shown in
FIG. 11
, optical imaging unit
31
of optical alignment apparatus
30
includes an annular light source
126
which fits coaxially over the objective lens tube
124
of a telescope tube
32
. An annular pattern of light rays directed forward from light source
126
is effective in illuminating tip of drill bit
18
.
Tip position sensor
40
of apparatus
30
includes a photo detector
128
which protrudes radially outwards from optical bench
36
, near the front end of the optical bench. Photo detector
128
is axially offset inwardly from the optical axis of telescope tube
32
, and transversely aligned with a plane spaced forward of objective lens
124
. Optical tip position sensor
40
also includes a light source
130
transversely aligned with photo detector
128
, and radially offset outwardly from the optical axis of telescope tube
32
. Light source
130
illuminates sensor
128
with a transversely disposed beam of light. Photo detector
128
outputs a detection signal indicative of the axial extension distance of the point of a drill bit
18
relative to sensor
40
, the detection signal being used to command axial position motor
44
to advance drill bit
18
to a pre-determined extension position forward of fluted portion receiver
56
.
Operation of automatic drill bit re-pointing apparatus
10
is as follows:
First, as shown in
FIG. 2
, a drill bit
18
to be re-pointed is loaded into drill bit holding apparatus
12
, with the holding apparatus located at the load/unload/alignment station position shown at the left-hand side of FIG.
2
. Drill bit
18
is loaded by placing the shank of the bit onto phase controller rollers
54
, and pushing the bit rearward into bore
91
of drill bit shank holder block
55
sufficiently far for the rear face of the drill bit shank to contact the front face of axial position controller spindle
86
, which has been retracted in bore
91
by an initialization command signal issued to axial drive motor
44
from an electronic controller, such as a computer (not shown). Drill bit
18
is loaded into holder apparatus
12
by any convenient means, such as by hand, or preferably by an automatic handling apparatus such as a robotic arm. As shown in FIGS.
1
-(
1
) and
1
-(
2
), drill bit
18
is positioned in holder apparatus
12
with the front, fluted portion of the bit supported on fluted portion receiver
56
. After drill bit
18
has been thus positioned in drill bit holder apparatus
12
, shank retainer actuator cylinder
48
is energized, causing shank retainer finger
70
to pivot downwardly against the upper surface of the shank of drill bit
18
, pressing the lower surface of the shank into secure contact with phase controller rollers
54
, as shown in FIG.
1
-(
2
).
With a drill bit
18
installed in drill bit holder apparatus
12
in the manner described above, the control computer issues a command signal which causes axial position drive motor
44
to rotate, causing lead screw spindle
86
to advance in bore
91
of shank holder support block
50
. Spindle
86
pushes drill bit
18
axially forward until point
132
of the bit extends to within a predetermined distance forward of objective lens
124
of optical alignment sensor
30
. At the predetermined position, axial point position sensor photo detector
128
produces a detection signal which commands cessation of drive current to drive motor
44
, thus maintaining the point of drill bit
18
at the predetermined axial extension.
When point
132
of drill bit
18
has been positioned at a desired axial extension beyond fluted portion receiver
56
, as determined by point position sensor
40
, telescope
32
of optical imaging unit
31
forms an image of the front fluted portion of drill bit
18
on the focal plane of CCD camera
38
, as shown in FIG.
12
. If the center of drill bit chisel point
132
is not at a pre-determined, centered position in the field of view of telescope
32
, such as the intersection of the horizontal and vertical cross hairs shown in monitor image
34
of
FIG. 12
, pattern recognition logic within the computer controller issues a command signal to fluted portion receiver actuator
60
to raise fluted portion receiver
56
, thus elevating chisel tip
132
to the pre-determined alignment position. Since, in the preferred embodiment, phase control rollers
54
, of bore
91
, and shank retainer finger
70
are arranged so that the front end of drill bit 18 tilts downward slightly, as viewed in FIG.
1
-(
1
), it is only necessary to elevate fluted portion receiver
56
to vertically align drill bit chisel point
132
in the monitor image
134
.
With chisel point
132
of drill bit
18
centered at a pre-determined position in monitor image
134
, as described above, pattern recognition logic within the computer controller determines whether the lips or cutting edges
140
of the drill bit are oriented at a predetermined phase angle θ (theta) with respect to the horizontal center line of the image. If the measured phase angle differs from the pre-determined value, the computer controller issues a command signal to phase controller motor
46
to rotate drill bit
18
to the pre-determined phase angle.
After drill bit
18
has been precisely aligned relative to drill bit holder mechanism
12
using optical alignment apparatus
30
, as described above, the computer controller issues a command signal to station position actuator cylinder
16
. This action causes drill bit holder mechanism
12
to pivot downwardly from the first, load/unload/align station position shown in
FIG. 2
, to a horizontal disposition in which drill bit
18
is presented to sharpening station
14
. Then, the computer controller issues command signals which cause first and second rotating grinding stone motors
116
and
118
to be moved by the traversing structure to translate the grinding stone motors in a pre-determined pattern, with first and second grinding stones sequentially contacting drill bit
18
. During this operation, the computer controller issues drive signals to phase controller motor
46
which rotate drill bit
18
during the sharpening process.
After completion of the sharpening process, the computer controller issues a command signal to station position actuator
16
which causes drill bit holder mechanism
12
to pivot upwardly from the sharpening station position adjacent sharpening unit
14
to the load/unload/align station position adjacent optical alignment apparatus
30
. Here an image of sharpened drill bit
18
is formed on the focal plane of CCD camera
38
. The image is conveyed to the computer controller, wherein pattern recognition logic determines whether the shape of the sharpened drill bit falls within pre-determined acceptance parameters, in which case a PASS status signal is issued, or if outside the limits, a FAIL status signal is issued. After the PASS/FAIL test determination, the computer controller causes a command signal to issue to shank retainer actuator cylinder
48
which causes shank retainer finger
70
to pivot upwardly to an unload position, thus allowing the re-pointed drill bit to be removed and replaced with another bit to be re-pointed.
As explained above, the design of the drill bit holder mechanism of the automatic drill bit re-pointing apparatus according to the present invention facilitates loading and unloading drill bits from the apparatus. In addition, because the holder includes a lead screw mechanism for axially moving the drill bit to a pre-determined axial position, a cutting portion receiver actuator for transversely moving the drill bit point to a pre-determined height, and a phase controller mechanism for rotating the bit to a pre-determined initial phase angle of the cutting lips of the drill bit, and rotating the bit from the initial phase angle during grinding, sharpening of drill bits can be performed fully automatically with the apparatus according to the present invention.
FIGS. 13-15
illustrate a preferred modification of the apparatus of FIGS.
1
-(
1
) and
1
-(
2
), which include a modification of the shank retainer
70
shown therein and described above.
As shown in
FIGS. 13-15
, modified shank retainer
100
, rather than having a finger-like shape as depicted in FIG.
1
-(
2
), comprises a cylindrically-shaped bushing
101
which protrudes from the front wall
103
surface of a plate-like cross arm
102
. Bushing
101
is rotatably supported by an internal roller bearing assembly
104
which is fastened to front surface
103
of cross arm
102
. With cross arm
102
pivoted downwardly as shown in
FIGS. 14 and 15
, bushing
101
tangentially contacts the shank of a drill bit
18
. With this arrangement, modified shank retainer
100
may exert a substantial normal force against the shank of drill bit
18
, while still allowing phase control rollers
54
to readily rotate the drill bit about its longitudinal axis.
Claims
- 1. An apparatus for sharpening twist drill bits comprises,a. a drill bit holder mechanism including, i. a front fluted portion holder structure adapted to support the fluted front portion of a drill bit, said structure including height adjustment actuator means effective in pivoting said drill bit to thereby position its tip at a pre-determined height, ii. a rear, shank holder structure adapted to support the shank of said drill bit, said structure including phase angle actuator means for rotating said drill bit about its longitudinal axis to a particular orientation or phase angle of the cutting edges or lips of said fluted front portion of said drill bit relative to said structure, b. an optical alignment apparatus located at a first, load/unload/align station position relative to said drill bit holder mechanism, said optical alignment apparatus adapted to measure the spatial position of said tip of said drill bit relative to said first station position, and c. station actuator means for moving said drill bit holder mechanism from said first station to a second, grinding station.
- 2. The apparatus of claim 1 further including controller means responsive to signals from said optical alignment apparatus in providing command signals to said phase actuator means effective in rotating said drill bit to a pre-determined phase angle.
- 3. The apparatus of claim 1 further including controller means responsive to signals from said optical alignment apparatus in providing command signals input to said height adjustment actuator means effective in moving said tip of said drill bit to a pre-determined height.
- 4. The apparatus of claim 1 further including controller means responsive to signals from said optical alignment appaatus in providing command signals input to said translational actuator means effective in moving said drill bit holder mechanism between said first station and said second station.
- 5. The apparatus of claim 1 wherein said rear shank holder structure is further defined as including a shank retainer pivotable between a first, unlocked position allowing placement of a drill bit in said holder structure, and a second, locking position bearing against said shank of said drill bit to thereby secure said bit in said holder structure.
- 6. The apparatus of claim 5 further including a retainer actuator effective in pivoting said retainer between said unlocked position and said locking position.
- 7. The apparatus of claim 1 wherein said optical alignment apparatus is further defined as including an optical imaging unit having a photo detector array and means for forming an image of the tip of said drill bit on said array, said photo detector array providing an output signal representative of the spatial orientation of said drill bit tip relative to said alignment apparatus.
- 8. The apparatus of claim 1 wherein said rear shank holder structure is further definied as including a longitudinal extension actuator for advancing said drill bit axially with respect to said structure.
- 9. The apparatus of claim 8 wherein said optical alignment apparatus is further defined as including a drill bit point extension sensor for determining the longitudinal extension of said drill bit tip relative to said shank holder structure and said optical alignment apparatus.
- 10. The apparatus of claim 1 wherein said phase angle actuator means for rotating said drill bit is further defined as comprising in combination adjacent roller means for rollably supporting a first longitudinal surface of said drill bit shank, shank retainer means for pressing against a second longitudinal surface of said drill bit shank opposite said first surface, and drive means for rotating said drill bit shank.
- 11. The apparatus of claim 10 wherein said drive means for rotating said drill bit shank is further defined as being a rotary actuator for rotatably driving at least one of said rollers.
- 12. The apparatus of claim 10 wherein said drive means for rotating said drill bit shank is further defined as a linear actuator frictionally contacting a surface of said drill bit shank, said linear actuator having a line of action transverse to the longitudinal axis of said drill bit shank.
- 13. An apparatus for sharpening twist drill bits comprising;a. a drill bit holder mechanism including; (i) a front fluted portion holder structure adapted to support the fluted front portion of a drill bit, said structure including height adjustment actuator means effective in elevating the tip of said drill bit to a pre-determined height, (Ii) a rear, shank holder structure adapted to support the shank of said drill bit, said structure including a pair of adjacent phase angle rollers for supporting a lower longitudinal surface of said drill bit shank, a shank holder block having a bore axially aligned with said drill bit shank supported on said phase rollers and adapted to insertably receive the rear end of said shank, and a shank holder retainer pivotable between a first, upper position and a second, lower position bearing against an upper longitudinal surface of said drill bit shank, (Iii) a spindle longitudinally retractable within said bore to receive said drill bit shank, and longitudinally extendable to push said drill bit shank axially forward a pre-determined distance, (Iv) phase angle actuator means for rotating said drill bit about its longitudinal axis to a pre-determined angular orientation of cutting lips of said drill bit to a pre-determined phase angle, (v) tip axial position actuator means for retracting and advancing said spindle, for advancing the tip of said drill bit to a pre-determined axial protrusion distance forward of said shank holder block, (vi) shank retainer actuator means for pivoting said shank retainer between said upper and lower positions, b. an optical alignment apparatus located at a first, load/unload/align station position relative to said drill bit holder mechanism, said optical alignment apparatus adapted to produce sensor signals signifying the spatial orientation of said drill bit tip relative to said shank holder block and said optical alignment apparatus, c. station actuator means for moving said drill bit holder mechanism from said first station to a second, grinding station, and d. controller means responsive to signals from said optical alignment apparatus in providing command signals input to said station actuator means effective in moving said drill bit holder mechanism between said first and second stations.
- 14. The apparatus of claim 13 wherein said controller means is further defined as being responsive to signals from said optical alignment apparatus in providing command signals input to said height adjustment actuator means effective in elevating the tip of said drill bit to a pre-determined height.
- 15. The apparatus of claim 13 wherein said controller means is further defined as being responsive to signals from said optical alignment apparatus in providing command signals input to said axial tip position actuator effective in advancing said drill bit tip to a pre-determined axial position forward of said shank holder block.
- 16. The apparatus of claim 13 wherein said controller means is further defined as being responsive to signals from said optical alignment apparatus in providing command signals to said phase angle actuator means for rotating said drill bit about its longitudinal axis to a pre-determined angular orientation of cutting lips of said drill bit.
- 17. The apparatus of claim 13 wherein said optical alignment apparatus is further defined as including a photo detector array and means for forming an image of the tip of said drill bit on said array.
- 18. The apparatus of claim 17 wherein said controller means is further defined as including pattern recognition logic effective in processing signals from said photo detector array to confirm that said drill bit tip is at a pre-determined spatial orientation relative to said optical alignment apparatus.
- 19. The apparatus of claim 18 wherein said pattern recognition logic is further defined as including a capability for determining whether the shape and dimensions of said drill bit tip meet acceptance criteria.
- 20. The apparatus of claim 13 wherein said optical alignment apparatus is further defined as including a drill bit point extension sensor for monitoring the axial protrusion distance of said drill bit point forward of said shank holder.
- 21. The apparatus of claim 20 wherein said drill bit point extension sensor is further defined as comprising in combination an illumination source and a photo detector located on opposite transverse sides of said drill bit.
- 22. The apparatus of claim 13 wherein said shank holder retainer is further defined as comprising in combination a pivot assembly including a longitudinally disposed support arm and a front pivot cross arm disposed transversely to and above said drill bit shank, said cross arm having protruding from the front surface thereof a drill bit shank contactable member.
- 23. The apparatus of claim 22 wherein said drill bit shank contactable member is further defined as being a bushing rollably supported with respect to said cross arm.
- 24. The apparatus of claim 22 wherein said shank retainer actuator means is further defined as being a linear actuator coupled to said pivot assembly support arm.
- 25. The apparatus of claim 13 wherein said shank pusher spindle is further defined as being threadingly engaged within said bore within said shank holder block.
- 26. The apparatus of claim 25 wherein said tip axial position actuator means is further defined as being a rotary motor having an output shaft rotatably coupled to said spindle.
- 27. The apparatus of claim 13 wherein said phase angle actuator means is further defined as being a rotary motor having an output shaft rotatably coupled to at least one of said phase angle rollers.
- 28. A method for pointing twist drill bits comprising;a. loading a drill bit into a drill bit holder mechanism at a first, load/unload align station position, b. forming an image field including an image of the tip of said drill bit, c. advancing said drill bit axially to a pre-determined longitudinally extended position within said image field, d. elevating said tip of said drill bit to a pre-determined height within said image field, e. rotating said drill bit about its longitudinal axis to a pre-determined angular orientation of cutting lips of said drill bit within said image field, f. pivoting said drill bit holder mechanism to a second, grinding station, g. translating rotating grinding stones at said grinding station into contact with surfaces of said drill bit to thereby point said tip, h. pivoting said drill bit holder mechanism back to said first station, i. forming an image of said pointed tip to determine whether it meets acceptance criteria, and j. unloading said pointed drill bit from said drill bit holder mechanism.
- 29. The method of claim 28 wherein said elevating of said drill bit tip is further defined as being accomplished by pivoting said drill bit.
Priority Claims (1)
Number |
Date |
Country |
Kind |
9-289131 |
Oct 1997 |
JP |
|
US Referenced Citations (5)