A dresser apparatus for dressing a grinding wheel to a desired cross sectional shape, the apparatus including a dresser frame connected to a stationary dresser base, and a slider block slidably connected to the dresser frame. A follower frame is mounted to the slider block for sliding movement with respect to the slider block in a second, substantially vertical direction. Linear actuator means are disclosed for causing the slider block to slide in the first direction with respect to the dresser frame. A cam is provided, corresponding to the desired shape of the grinding wheel, and a cam follower is attached to the follower frame and postioned thereon so as to bear on the cam surface. In one embodiment the cam follower causes the follower frame to move in the second direction according to the shape of the cam surface while the linear actuator means moves the slider block in the first direction. In another embodiment, directed to dressing wheels with a flat or reverse angled surface, a second linear actuator provides the vertical movement. A grinding wheel dressing tool is affixed to the dresser arm and positioned so as to bear on and dress the grinding wheel in conformity with the shape of the cam surface. The dressing tool is attached to the dresser arm, and the cam follower to the follower frame, at an oblique angle with respect to the grinding wheel axis.

BACKGROUND OF THE INVENTION 
This invention relates to accessories for drill pointing machines, or 
machines for sharpening drill bits, and in particular to such accessories 
which are provided for the purpose of dressing the grinding wheels of such 
drill pointing machines. 
Drill pointing machines as shown in Winslow, U.S. Pat. No. 3,040,480, are 
generally well known, and are important to machine shops to keep a supply 
of relatively sharp and properly pointed drill bits on hand. As is also 
shown in that patent, the grinding wheels used in drill pointing machines 
as there described tend to wear and lose their proper shape with use, this 
proper shape being important to proper shaping of the drill point being 
ground. This loss of shape of the grinding wheel requires a grinding or 
"dressing" operation to be periodically performed on the wheel to restore 
it to proper form and shape. Since the drill pointing operation is 
generally automatic, it is desirable for the dressing operation to be as 
automatic as possible also. 
The Winslow patent shows a dressing apparatus which dresses the grinding 
wheel according to the shape of a cam, with respect to which a cam 
follower is moved by a power cylinder. However, in the Winslow apparatus 
the cylinder moves the cam follower along the surface of the cam, and the 
dresser tool is held against the wheel solely by the force of a spring. 
This arrangement can result in less dressing force being applied to the 
dressing tool and in turn to the wheel. Further, the dressing tool in 
Winslow is disclosed to be held perpendicular to the axis of rotation of 
the wheel. In addition, the Winslow patent discloses a dressing apparatus 
which is designed for application to a specific drill pointing machine. 
Montanus, U.S. Pat. No. 3,162,186, shows a dresser apparatus for a grinding 
wheel including a traverse motor which moves a cam follower along a cam so 
that a dressing tool is moved both vertically and horizontally. Here again 
dressing tool is disclosed to be held perpendicular to the axis of 
rotation of the wheel. In addition the Montanus apparatus is limited as to 
the wheel shapes it is capable of dressing, requiring that there be smooth 
curves and no flat vertical faces or reverse angles. 
Hoaglund, U.S. Pat. No. 2,938,515 shows a contour forming apparatus which 
carries a diamond cutting tool at an oblique angle. 
This invention relates to improvements to the apparatus described above, to 
solutions to the problems raised thereby, and to apparatus for other drill 
pointing machines. 
SUMMARY OF THE INVENTION 
None of the patents set forth above permits the dresser apparatus to dress 
a wheel requiring a face with a backward angle, or even for that matter a 
flat face. It is an object of this invention to provide for such an 
apparatus. 
To this end the apparatus of the invention includes a dresser base affixed 
substantially immovable with respect to the drill pointer base. A dresser 
frame is connected to the dresser base, and a follower frame slidably 
connected to the dresser frame. The follower frame includes a follower 
carriage mounted to the dresser frame for sliding movement with respect to 
the dresser frame in a first, substantially horizontally radially 
inward-and-outward direction. A dresser arm is mounted to the follower 
carriage for sliding movement with respect to the follower carriage in a 
second direction substantially parallel to the axis of rotation of the 
grinding wheel. The apparatus further includes linear actuator means for 
causing the follower frame to slide back and forth in the first direction. 
A cam is provided, corresponding to the desired shape of the grinding 
wheel, and a cam follower is attached to the follower frame and positioned 
thereon so as to bear on the cam surface, thereby causing the follower 
frame to move in the second direction according to the shape of the cam 
surface while the linear actuator means moves the follower frame in the 
first direction. A grinding wheel dressing tool is affixed to the dresser 
arm and positioned so as to bear on and dress the grinding wheel in 
conformity with the shape of the cam surface. The dressing tool is 
attached to the dresser arm at an oblique angle with respect to the 
grinding wheel axis. The dresser frame is slidable with respect to the 
dresser base, permitting adjustment of the apparatus for removal of 
material from the grinding wheel in the dressing operation, by means of a 
screw, including markings for indicating the distance the dresser frame 
has been adjusted with respect to the dresser base. 
In one embodiment directed to a wheel with a flat face or a reverse angle 
of incline, the follower frame moves in the first direction until the 
follower contacts the cam. Upon that occurrence the dresser arm is caused 
to move in the second direction by a second linear actuator means, and the 
first linear actuator means is constructed so as to permit reverse 
movement if necessary. 
Other objects and advantages of the invention will become apparent 
hereinafter.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, the apparatus 10 constructed according to a 
preferred embodiment of the invention is a grinding wheel dressing 
apparatus designed as an accessory to a drill pointing machine 12. As is 
conventional for such machines, the drill pointing machine 12 includes a 
grinding wheel 14, which is continuously rotated about an axis 16 by any 
suitable prime mover, shown schematically at 18. While it is generally 
conventional that the axis 16 be substantially vertical, the invention is 
in no way intended to be limited to any one particular orientation. Any 
relative directions referred to herein, such as vertical or horizontal, 
are for ease of reference only. 
The drill pointing machine 12 generally includes a stationary base 20, 
which provides support to the prime mover 18 and via bearings (not shown) 
to the grinding wheel 14. The grinding wheel 14 will generally have a 
cross section which, when taken perpendicularly to the axis 16, is 
substantially circular. 
According to the invention, the dressing apparatus 10 includes a dresser 
base 22 immovably affixed such as by screws 24 to the stationary base 20. 
A dresser frame 26 is slidably connected to the dresser base 22 in such a 
manner that the dresser frame may be continuously moved along the dresser 
base, radially toward and away from the grinding wheel 14. The purpose of 
permitting this movement is to provide a means for moving the apparatus 10 
with respect to the wheel 14, thus compensating for the material removed 
from the wheel in the dressing and drill bit grinding operations. The 
movement is preferably continuous or, more explicitly, continuously 
variable, so as to provide for even small changes in the size of the wheel 
14. In the embodiment shown, this continuous movement is accomplished by 
means of a screw 28, which is oriented substantially radially with respect 
to the wheel 14, journaled to the dresser frame 26 and threaded into the 
dresser base 22. A crank handle 30 may be provided, attached to an end of 
the screw 28, to facilitate the turning of the screw and thus the 
positioning of the apparatus 10 with respect to the wheel 14. 
The dresser frame 26 includes a dresser frame base plate 32 and a pair of 
substantially vertically oriented support plates 34 and 36 spaced apart 
from each other. Front plate 34 is attached to an end of the base plate 32 
proximal to the wheel 14, while back plate 36 attached to an end of the 
base plate distal from the wheel 14. The two plates 34 and 36 are oriented 
in spaced-apart substantially parallel planes, each substantially 
perpendicular to the same radial of wheel 14. The plates 34 and 36 are 
secured to the dresser frame base plate 32 by any suitable means, such as 
bolts 38 or welds (not shown), or may be integrally formed therewith. The 
dresser frame 26 also includes a pair of slider rods 40 affixed between 
the front plate 34 and back plate 36, substantially horizontally oriented 
and arranged in parallel spaced apart relation to each other. In the 
embodiment shown the rods 40 are arranged vertically, one above the other, 
but their relative arrangement may be otherwise, as long as they are 
substantially parallel with each other and substantially perpendicular to 
the front and back plates 34 and 36. 
A follower carriage 42 is slidably connected to the slider rods 40. To the 
follower carriage 42 is affixed a conventional dresser tool bit 44, 
positioned so as to bear upon the wheel 14. The precise positioning of the 
dresser tool bit 44 will be treated in more detail subsequently herein. 
In the preferred embodiment, the follower carriage 42 includes a slider 
block 46, shown best in FIGS. 2, 3 and 5, which is a generally rectangular 
solid, having longitudinal apertures 46a (FIG. 5) formed therein sized and 
positioned to fit somewhat loosely over the slider rods 40 to permit the 
slider block to slide along the rods. A linear actuator 48 is provided for 
moving the slider block 46 along the slider rods 40. This linear actuator 
48 may be any suitable structure for the purpose, such as a hydraulic or 
pneumatic cylinder, or other linear actuator. The linear actuator 48 is 
mounted to the dresser frame 26, such as to the back plate 36, and 
includes an actuated member 50, such as a cylinder rod, attached to the 
slider block 46. Hence when the linear actuator 48 moves or actuates the 
member 50, the slider block 46 is caused thereby to move in a 
corresponding direction along the rods 40. 
As shown best in FIGS. 3, 5 and 6, a bearing block 52 is secured to the 
side of the slider block 46. A follower frame 54 is connected to the 
bearing block 52 so as to be vertically movable with respect thereto. As 
shown most clearly in FIG. 6, the connection between the follower frame 54 
and the bearing block 52 is by means of vertically oriented bearings 56. 
In the embodiment shown, the follower frame 54 is an open rectangular 
shaped member made up of four flat parts, a top plate 58 and a bottom 
plate 60 connected together by two side plates 62 and 64. Referring again 
to FIG. 6, side plate 64 is the portion of the follower frame 54 which is 
mounted to the bearing block 52 by means of bearings 56. 
To side plate 62, opposite side plate 64, is affixed a cam follower 66. To 
the corresponding side of the back plate 36 and front plate 38 is affixed 
a cam carrier bracket 68, to which is removably affixed a cam 70. Any 
suitable secure but removable means may be employed for affixing the cam 
70 to the cam carrier bracket 68. In the embodiment shown, the cam 70 is 
affixed by resting it upon dowel pegs 72 secured to the cam carrier 
bracket, and also by a bolt 74. The cam 70 and the cam follower 66 are 
positioned on their respective mountings with respect to each other so 
that the cam follower bears upon the cam surface 70a of the cam 70. Then 
as the linear actuator 48 moves slider block 46 with respect to the 
dresser frame 26, the cam 70 causes the cam follower 66 and hence the 
follower frame 54 to move upward as well as forward, or permits the 
follower frame to move downward as well as backward, according to the 
shape of the cam surface 70a. One end of a dresser arm 76 is affixed to 
the side plate 64 to which the bearings 56 are attached. The opposite end 
of the dresser arm 76 carries the dresser tool 78 which, as indicated 
earlier, holds the dresser tool bit 44 in contact with the surface of the 
grinding wheel 14. Accordingly the dresser tool bit 44 moves corresponding 
to the cam surface 70a, along with the follower frame 54 as described 
above. 
As can be seen in FIGS. 1 and 4, the dresser bit 44 is mounted in the 
dresser tool 78 at an oblique angle, rather than strictly vertical or 
horizontal. This angled mounting is to permit the bit 44 to maintain 
contact with the surface of the grinding wheel 14 even though the cam 
surface 70a may have portions that are too rounded or flat for 
conventional dresser bits. For example, the dresser tool bit shown in the 
Winslow patent, referred to earlier, is held fully horizontally, and would 
not function to dress a wheel according to a cam with a concave surface or 
with a rounded top surface. In the present invention, the angle of this 
mounting is most preferred to be 50 degrees with respect to the tool 78, 
to yield the greatest flexibility in shapes of surfaces to be accommodated 
by the apparatus 10, and certainly at least 40 to 60 degrees. 
Another embodiment of the invention is shown in FIGS. 7 through 9. This 
embodiment is provided specifically for the purpose of dressing a grinding 
wheel 79 with a flat face or a reverse angle of incline, as shown in FIG. 
7. With that type of wheel, a cam will not have a smoothly upwardly 
inclined face for causing the follower frame 54 to move upward as 
described above. Powered means must therefore be provided to furnish the 
necessary upward movement so that the dressing tool 44 properly dresses 
the wheel 79. 
As shown in FIGS. 7 through 9, this powered means for upward movement is 
embodied as a linear actuator, and particularly a hydraulic cylinder 80, 
affixed to the follower frame 54. The cylinder 80 includes a piston 82 
(FIG. 9) connected to a vertically oriented actuator rod 84. The distal 
end of the actuator rod 84 bears on a flat-topped land 86 attached to the 
dresser frame 26. 
The hydraulic/pneumatic circuit for this embodiment is shown partially 
schematically in FIG. 9. As there shown, the circuit includes a first 
control valve 88 which controls the linear actuator 48, and a second 
control valve 90 which controls the cylinder 80. For clarity the cylinder 
80 is shown twice in FIG. 9, once at the left side as it fits 
schematically into the circuit, and once at the right as it fits 
physically and functionally into the apparatus. In the embodiment shown in 
FIG. 9 the circuit is partially pneumatic and partially hydraulic, 
although this combination is not necessary to the invention. 
To begin the dressing operation with this embodiment, the first control 
valve 88 is pressed, which causes a slide valve 92 to shift, permitting 
pressure to enter a reservoir 94. This in turn causes the actuated member 
50 of the linear actuator 48 to advance, to the right as shown in FIG. 9, 
as in the embodiment described above. The actuated member 50 will continue 
to advance until the cam follower 96 of this embodiment contacts the cam 
98, at which point the dressing tool 44 is in contact with the wheel 79. 
In this embodiment, however, because the shape of the cam 98 to which this 
embodiment is directed is such as to not cause the follower frame 54 to 
rise, the actuator 48 simply stops when the follower 96 contacts the cam. 
The follower 96 in this embodiment is advantageously shaped in a different 
way, or alternatively simply rotated from the embodiment shown in FIG. 1, 
to permit the follower to properly interact with the cam 98 as required in 
this embodiment. 
When the follower 96 contacts the cam 98 and the actuator 48 stops, the 
operator then presses the second control valve 90, which causes another 
slide valve 100 to shift, in turn forcing the piston 82 and actuator rod 
84 of the cylinder 80 to move downward. When the rod 84 contacts the land 
86, and thereafter continues to extend, the follower frame 54 will be 
raised. If the face of cam 98 is completely flat and vertical, the 
movement of the follower frame 54 will be entirely vertical. If, however, 
the face of cam 98 is angled backwardly to some extent, as shown in FIGS. 
7 and 9, the follower frame 54 will be required to move backward to that 
same extent as the follower 96 follows the contour of the cam 98. To 
permit this backward movement, flow restrictors 102 are provided in the 
supply lines to the actuator 48, to reduce the pressure applied by the 
actuator compared to that of the embodiment shown in FIGS. 1 through 6. 
When the follower 96 reaches the top of the cam 98, as shown in phantom in 
FIG. 7, the actuator 48 again moves the follower 96, and hence the 
dressing tool 44, forward, now along the top of the cam. At a 
predetermined point, the follower frame 54 contacts an end valve 104. As 
shown in FIG. 9, this end valve 104 switches first slide valve 92, to 
shift pressure from the first reservoir 94 to a second reservoir 106. 
Since the second reservoir 106 is connected to the return side of both 
linear actuator 48 and cylinder 80, the follower frame 54 is returned to 
its starting position. 
Hence the invention provides an apparatus for dressing a grinding wheel 14 
which is more positive in its action and which is capable of dressing 
wheels that have different shapes than apparatus available in the prior 
art. 
While the apparatus hereinbefore described is effectively adapted to 
fulfill the aforesaid objects, it is to be understood that the invention 
is not intended to be limited to the specific preferred embodiment of 
semi-automatic dressing accessory set forth above. Rather, it is to be 
taken as including all reasonable equivalents within the scope of the 
following claims.