Note: Descriptions are shown in the official language in which they were submitted.
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TITLE: IMPROVED GRINDING APPARATUS
BACKGROUND OF THE INVENTION
The present invention relates to improvements in
apparatus for grinding the hard metal inserts or working
tips of drill bits (percussive or rotary), tunnel boring
machine cutters (TBM) and raised bore machine cutters (RBM
and more specifically, but not exclusively, for grinding
the tungsten carbide cutting teeth or buttons of a drill
bit or cutter.
In drilling operations the cutting teeth
(buttons) on the drill bits or cutters become flattened
(worn) after continued use. Regular maintenance of the
drill bit or cutter by regrinding (sharpening) the buttons
to restore them to substantially their original profile
enhances the bit/cutter life, speeds up drilling and
reduces drilling costs. Regrinding should be undertaken
when the wear of the buttons is optimally one third to a
maximum of one-half the button diameter.
Different manual and semi-automatic grinding
machines are known for grinding button bits/cutters (see
for example U.S. Patent Nos. 5,193,312 and 5,070,654). In a
conventional type of machine a grinding cup having the
desired profile is rotated at high speed to grind the
carbide button and the face of the bit/cutter surrounding
the base of the button to restore the button to
substantially its original profile for effective drilling.
C.M.E. Mining & Blasting Equipment Ltd. (~~CME")
has developed a range of grinding machines including hand
held grinders, single arm and double arm self centering
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machines for setting up two or more bits to be ground,
mobile machines for grinding on the road or in a workshop
(the CME JuniorTM grinder) and grinders designed
specifically for mounting on drill rigs, service vehicles
or set up in the shop (CME Mini JuniorTM). While the present
invention is applicable to all grinding machines (except
hand held grinders) the invention is particularly
applicable to mobile grinding apparatus of the type
described in U.S. Patent No. 5,193,312 or distributed by
CME under the Junior or Mini Junior designations.
BRIEF DESCRIPTION OF THE DRAWINGS
In order that the invention may be more clearly
understood, the preferred embodiment thereof will now be
described in detail by way of example, with reference to
the accompanying drawings, in which:
FIG. 1 is a front plan view of one embodiment of an
improved grinding apparatus according to the
present invention having a grinding machine
carried for vertical and horizontal adjustment by
an arm or lever system journaled on a stand or
frame and with a tiltable table for holding the
bit to be ground;
FIG. 2 is a front plan view of the frame for the
grinding apparatus of Fig. 1.
FIG 3 is a left side plan view of the frame of FIG. 2;
FIG. 4 is a right side view of the frame of FIG. 2;
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FIG. 5 is a front plan view of the arm or lever system
of FIG. 1;
FIG. 6 is a top plan view of the arm or lever system of
FIG. 5;
FIG. 7 is a top plan view of the tiltable table, for
holding the bits to be ground, of the grinding
apparatus of FIG. 1;
FIG. 8 is a right side plan view of the table of FIG. 7;
and
FIG. 9 is a plan view of bottom of the frame of FIG. 2
with a splash guard.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
With reference to the FIGS, one embodiment of an
improved grinding apparatus according to the present
invention is generally indicated at 1. While the present
invention is applicable to all grinding apparatus having a
grinding machine carried for vertical and horizontal
adjustment by an arm or lever system journaled on a stand or
frame and preferably with a tiltable table for holding the
bit to be ground, the grinding apparatus shown is of the
type intended to be mounted on drill rigs, service vehicles
or set up in the shop such as the CME Mini JuniorT" grinders.
The grinding apparatus 1 consists of a frame 2 supporting a
table 3 for holding one or more bits to be ground. The frame
2 of the illustrated embodiment consists of a generally
rectangular box 4 having a back panel 5, left and right side
walls 6, 7 normal to said back panel, two extending support
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arms 8, 9, a top plate 12, bottom plate 10 and hinged cover
11.
A grinding machine 13 is carried by an arm or
lever system, generally indicated at 14, journaled on a
cylinder rod 15 of cylinder 16 attached to the frame 2. A
compressed air connection 17 is provided to operate various
aspects of the grinding apparatus as discussed in detail
below.
Table 3 is tiltably mounted to the frame 2 at
pivot points 18,19 on the appropriate places of the
extending arms 8, 9 on frame 2 (see FIGS 3 and 4). The table
3 is provided with one or more apertures 20 to hold one more
bits to be ground. A bit (not shown) is positioned in
aperture 20 and positioned with the button to be ground in
the vertical position. The bit is held in place by pressure
plate 22 controlled by a locking cylinder 23. The locking
cylinder can be backed off slightly to rotate the bit (to
the next button to be ground) within the aperture 20 without
full release of the pressure on the locking cylinder.
The grinding machine 13 in order to properly
regrind a worn button must be aligned over the longitudinal
axis of the button. Accordingly to regrind the gauge
buttons, table 3 is tilted to correspond to the angle at
which the gauge button are mounted in the bit. The bit is
then indexed in the table so that the longitudinal axis of
the button to be ground is in the vertical. The means of
tilting table 3 is best illustrated with reference to FIGS
2, 7 and 8. The front edge of right side 7 is bent to form
an inwardly extending flange 25. A longitudinal slot 24 is
provided in flange 2. A scale 26 is preferably provided to
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indicate the angle at which the table 3 will be tilted. A
stop 27 is positioned within the slot 24 at the desired
angle and locked in place by lever 28. Once set for a
particular bit type, the angle is fixed and doesn't have to
be reset for each bit or button to be reground. A cylinder
29 is connected to stop 27 and the end 30 of the cylinder
rod 31 is connected to the side 32 of table 3 at point 33.
When air is fed to cylinder 29, retraction of the rod 31
will tilt table 3 until the rod is fully retracted. As shown
in FIG. 1, controls, generally indicated at 34, for tilting
the table and locking the bits) in place are provided on
the instrumentation panel 35 on the hinged protective cover
11. One switch 36 controls the cylinder 29 for tilting the
table 3 and a second switch 37 controls the locking cylinder
23 and pressure plate 22. Flow controls are provided to
regulate the speed of movement of the table and the pressure
plate.
Large down the hole bits to be reground typically
have a relatively long shaft that fits through aperture 20.
In order to regrind smaller bits a floor plate 38 that can
be slid in and out of position under aperture 20 is
provided. Knob 39 and slot 40 in table 3 control the
location of the floor plate 38. Adapters for holding
multiple small sized bits can be inserted into aperture 20.
Use of the adapters eliminates repetitive set up time for
the operator.
A splash guard 41 connected to bottom plate of
frame 2 is provided at the front of the grinding machine 13
that can be raised and lowered.
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The arm system 14 for carrying and positioning
grinding machine 13 as noted previously is journaled onto
cylinder rod 15. With reference to FIGS 1, 5 and 6, the arm
system 14 consists of a first arm section 42 having one end
43 journaled to cylinder rod 15. The other end 44 of the
first arm section 42 provides the mount for the second arm
section 45. The second arm section 45 is journaled to the
first arm section 42. The other end 46 of the second arm
section 45 is journaled to the back mount 47 connected to
control box 48. Locking lever 49 allows control box 48, with
back mount 47 and their journaled position in relation to
the axis of the second arm section, to be locked. Cylinder
16 through cylinder rod 15 controls the vertical movement of
the grinding machine up and down. Cylinder 16 through
cylinder rod 15 provides a balance pressure to the arm
system when the grinding machine 13 is not in sue and
grinding pressure/feed when in use. The grinding balance
pressure and pressure/feed can be adjusted.
Within the second control box 48, is a rotation
motor 50 and bearing arrangement 51 for providing an orbital
rotation to grinding machine 13. The grinding machine 13 is
attached to control box 48 by means of plates 52, 53. The
grinding machine 13 has an electric motor in the embodiment
shown but can also utilize other motor type such as air or
hydraulic motor. Each of the plates 52, 53 is provided with
an acruate slot 54, 55. The angle of attachment of the
grinding machine 13 relative to control box 48 can be
adjusted by means of slots 54, 55 and locking lever 56. By
having the grinding machine oscillate slightly off vertical,
nipple formation on the button being reground is minimized
and uneven wear on the grinding cup avoided.
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When grinding buttons, the self-centering aspects
of the grinding machine tend to center the grinding machine
over the highest point on the button. On buttons where wear
is uneven, typically gauge buttons, this may result in
regrinding the button off center from its vertical axis. To
substantially center the grinding machine over the
longitudinal axis of the button, the second arm section 45
is provided with a cylinder 57 having one end 58 connected
to for example the cylinder 7 16 and the other end 59
connected to the mount 60 of the second arm section 45. The
cylinder 57 provides a biased load to grinding machine 13 to
help center the grinding machine over the button. In the
embodiment shown, the cylinder 57 is automatically activated
when the table is tilted by the pilot feed from cylinder
through valve 61 in instrumentation panel 35. The biased
load causes the grinding machine to grind more on the inside
of the gauge buttons thereby tending to shift the grinding
machine over the true center of the button. The suitable
biased load can be provided by other means such as counter
weights, etc. In cases where deemed necessary, cylinder 57
could be used to lock the horizontal distance of grinding
machine 13 from, for example, cylinder 16 and cylinder rod
15 or frame 2. Other methods such as mechanical locks can
also be used for locking the horizontal distance of grinding
machine 13 from, for example, cylinder 16 and cylinder rod
15 or frame 2.
In addition, variations of the same above
described principle of biased loads or counter balancing can
also be used to allow for grinding at angles other than
vertical. Combinations of variations of the above described
principle of biased side loads or counter balancing can be
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used to substantially eliminate the need for
tilting/pivoting the bit when switching between grinding of
face buttons and gauge buttons. This principle would be
ideal in cases where tilting or pivoting of the bit is
difficult due to size, weight, etc.
Having illustrated and described a preferred
embodiment of the invention and certain possible
modifications thereto, it should be apparent to those of
ordinary skill in the art that the invention permits of
further modification in arrangement and detail.
It will be appreciated that the above description
related to the preferred embodiment by way of example only.
Many variations on the invention will be obvious to those
knowledgeable in the field, and such obvious variations are
within the scope of the invention as described and claimed,
whether or not expressly described.
