Note: Descriptions are shown in the official language in which they were submitted.
20~100~
Case 5980
CEB:am
METHOD AND APPARATUS FOR GRINDING
THE END OF A TUBULAR WORKPIECE
Thi~ invention relates to an improved method and
apparatus for finishing the end of a tubular workpiece, and
more particularly ~o a method and apparatus wherein a
finishing tool is pivotable outwardly to permit insertion of a
tubular workpiece into a rotatable holder.
G~UND QE THF.INVENTION
There is a krlown technique for casting articles from
molten metal, commonly referred to as bottom pressure casting,
wherein molten metal in an enclosed ladle is pressurized and
forced upwardly through a refractory pouring tube and into the
bottom of a mold. When the mold is filled it is closed with a
stopper and removed from the pouring tube. The pouring tube
itself must be frequently replaced but is normally usable to
successively supply a large number of molds. The upper end of
the pouring tube must closely fit the mold bottom to prevent
leakage of molten metal at that juncture and is preferably
chamfered. Also it is necessary to encircle the upper end of
the pouring tube with a cylindrical backing (known as a tube
holdin~ casting) ~nd an annular reinforcement ~known in the
trade a~ a tube parting ring) that also must abut the mold
bottom. Con~equently, the pouring tube end must be carefully
finished by grinding, or the like, after the annular
reinforcement and cylindrical backing are mounted thereon; and
the outer edge of the tube end must be accurately finished to
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be flush with the upper face of the parting ring
reinforcement.
Furthermore, such pouring tubes are sizeable pieces of
equipment. For instance in an installation for casting
railcar wheels the pouring tubes are 6 1/2 inches in diameter
and several feet long. Heretofore the tube ends have been
finished by hand held grinders. Thus it will be understood
that it has been difficult to position such a workpiece for
end finishing; and it has also been difficult to properly
posture and maintain a finishing tool to obtain an accurate
chamfered end on the workpiece.
SUMMARY OF THE INVENTIQ~
Accordin~ly, it is a principal object of the present
invention to provide a method and apparatus for positioning a
tubular workpiece and accurately finishing an end thereof.
It is another object of the present invention to provide
an improved method and apparatus for receiving a tubular
workpiece in a rotatable holder and swinging a finishing tool
in a radial direction respecting the workpiece.
It i~ a further object of the present invention to
provide a method and apparatus for holding and rotating a
tubular workpiece and for moving a finishing tool between an
operative posture, to grind a chamfer on a workpiece end, and
an inoperative posture, to permit replacement of the
workpiece.
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Briefly stated the present invention involve~ the
inserting of a tubular workpiece in an axial direction into an
annular holder, pivoting a finishing tool in a direction
radial to the holder and workpiece to a posture over the
workpiece, extending the finishing tool in a generally
longitudinal direction against the workpiece end while
rotating the workpiece about its longitudinal axis and
thereafter withdrawing and pivoting the tool in an opposite
direction to permit extraction of the workpiece in an axial
direction from the annular holder. An apparatus to perform
the foregoing steps comprises an upstanding base with an
annular workpiece holder rotatably mounted on the base, a
carriage pivotally mounted to one side of the base for pivotal
movement substantially radially of the annular holder, tool
means reciprocally mounted on the carriage, and power means
connected between the base and carriage to pivot the latter.
BBIEE DESC~IpTION OF ~E DRAWING~:
Further objects and advantages will become apparent upon
reading the following detailed description in conjunction with
the drawings wherein:
FIGURE 1 is a qide elevation view of a preferred
embodiment of the invention with certain parts in section for
clarity; and
FIGURE 2 i9 an end elevation view of the apparatus of
FIGURE 1.
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D~TAILED DEScRIpTIoN:
The preferred embodiment of the invention was devised to
finish the end of a six and one half inch (6 1/2") diameter
molten metal pouring tube 10, made of a refractory material,
and thereby provide an accurate planar inner end edge with a
slight chamfer downward from the inside tube surface to the
outside surface. It will be seen in FIGURE 1 that the end of
the tube 10 is, prior to the finishing operation, encircled by
a reinforcing tube parting ring 12 and tube holding casting
10 14; and it is required that the finishing operation place the
outer edge of the end chamfer even with the axial face of the
parting ring. The finishing tool is a carborundum grinding
disk generally 20 having a flat circular abrasive fa~e 22 that
is spun at high speed about the disk axis.
The devised method begins with positioning the pouring
tube 10 by inserting it into an annular holder generally 30
and then rotating the tube 10 about it~ axis. After inserting
the tube 10 the finishing tool is operatively located by
moving it inwardly from an inoperative posture, to one side of
20 the tube 10, in a direction radial to the tube axis to an
operative po~ture with the finishing tool opposing but spaced
from the tube end; while ~imultaneously exerting a biasing
force to move the tool away from the tube end. Preferably the
tool is moved radially into the operative posture by swinging
or pivoting it about a point to one side of the tube 10 and in
a plane containing the axis of the tube so as to maintain the
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axis of the grinding disk 20 in that plane and thereby assure
that the abrasive face 22 i5 maintained perpendicular to a
plane containing the tube axis. The swinging or pivoting
movement of the tool also enables limiting the inward movement
and thereby placing the axi~ of the tool at a slight angle to
the axis of the tube 10 at the operative posture, which angle
will establish the chamfer placed on the finished tube end.
The procedure is then continued by extending the tool into
contact with the tube end while both rotating the tube 10 and
spinning the grinding disk 20.
Preferably the tool is extended by applying fluid
pressure sufficient to overcome the aforementioned biasing
face and to urge the tool against the tube end. As the tube
rotates unevenness at the workpiece end will cause fluctuation
of the reaction against the tool and hence cause unevenness in
the fluid pressure. The rotating of the tube and spinning of
the tool are continued at least until thè pressure becomes
constant thereby indicating that an even finish of the
workpiece end ha~ been achieved. At that point the procedure
i9 concluded by terminating the fluid pressure overcoming the
biasing force, thereby withdrawing the tool away from the tube
end, then returning the tool to the inoperative posture by
swinging or pivoting it in the axial plane, and finally
extracting the tube 10 in an axial direction from the annual
holder 30.
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A preferred apparatus for carrying out the method
includes an upstanding fixed frame generally 40 supported on a
floor 42 or the like. The frame has a top 44 with a circular
opening 46. Concentric with the opening 46 are an annular
bearing raceway 48 and an annular ring gear 50 supported
therein. The annular holder generally 30 is secured to the
ring gear 50 and includes a chuck 52 to center and secure the
pouring tube generally 10, including parting ring 12 and
holding casting 14, therein. The floor beneath the fixed
frame 40 may also have an openin~ directly beneath circular
opening 46 in frame top 44 to permit the processing of long
workpieces.
An electric motor 60 is fastened to the frame 40 and a
gear reducer 62 connects the motor shaft to the annular ring
gear 50 to cau e the latter to rotate in the raceway 48 and
thereby rotate any workpiece centered in the chuck 52 about
the workpiece axis.
A flat base or pedestal 70 rests on the floor 42
immediately to one side of the fixed frame 40. A pair of
spaced trunnions 72, 74 are slidingly supported on the base 70
for adju~tment toward and away from the fixed frame 40; and a
pivot sh~ft or axle 80 is rotatably held in the trunnions 72,
74 to be perpendicular to the axis of rotation of both the
ring gear 50 and workpiece, and also perpendicular to a radius
of the workpiece that bisects the shaft 80. Threaded bolts
82, 84 extend through the respective trunnions 72, 74 and into
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the fixed frame 40. A plurality of adjustable nuts 86 on the
bolts 82, 84 provide for accurately positioning and securing
the trunnions, 72 74 with respect to the frame 40.
A pivotable carriage generally 90, comprising a pair of
upstanding channel members 92, 94 and one or more cross
members 90 fixed to the channels, is supported on the shaft 80
so as to be pivotable toward and away from the fixed frame 40.
Each respective channel member 92, 94 is connected to the
shaft 90 closely adjacent a trunnion 72, 74; and a power
cylinder 100 is fastened centrally to a cross member 96 with
its reciprocal rod 102 extending toward the fixed frame 40
where it is connected by a clevis 104 and pin 106. The clevis
104 is detachably fastened to the frame 40 so that a
selectable shim 110 i.q insertable therebetween. It will be
understood that operation of the power cylinder 100 will cause
the carriage generally 90 to swing inwardly and outwardly of
the fixed frame 40; and, assuming full throw of the rod 102,
the relative positions of the clevis pin 106 and pivot shaft
80 will fix the inward and outward angular positions of the
carriage 90.
A movable platform generally 120 is carried between the
chànnel members 92, 94 of carriage 90 at a level above the
chuck 52 and workpiece therein. The platform 120 includes a
cros3 arm 122 that extends between and is perpendicular to the
channels 92, 94 and a depending plate 124 fastened to the
underslde of cross arm 122 and extending parallel to the
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channels. Four casters 128 bolted to the channels 92, 94
engage opposite edges of the plate 124 and confine its
movement to parallel the channels. Compression springs 132,
134 are secured between brackets 138, 140 on each edge of the
plate 124 and opposing brackets 142, 144 fastened to the
respective channels 92, 94 and bias the platform 120 upwardly.
A beam 150 extends beneath cross arm 122 from the center
of one side of the depending plate 124 to a cylindrical casing
152 at the end over the fixed frame 40. An electric tool
driving motor 156 is mounted to the opposite side of the
depending plate 124 with its drive shaft 158 and drive pulley
160 disposed upwardly. A tool drive shaft 162 extends through
the casing 152 and a pulley 164 thereon is drivingly connected
to the motor pulley 160 by a belt 166. It is important that
the tool drive shaft 162 is aligned to be maintained in a
plane that contains the workpiece axis. That is accomplished
by centering shaft 162 with respect to the carriage 90 and
positioning the trunnions 72, 74 equally spaced from the
workpiece axis. The finishing tool such as grinding disk 20,
is connected to the lower end of tool drive shaft 162 and is
preferably partially enclosed by a shroud 170 held beneath the
beam 150. A suitable exhaust manifold (not shown) may be
connected to the shroud 170 to collect particulate material
during a finishing operation.
The platform generally 120, with motor 156 and grinding
disk 20 are moved parallel to the carriage channels 92, 94 by
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a fluid cylinder 180 and reciprocable piston rod 182 connected
between an angle 188 fastened between channels 92, 94 on the
carriage generally 90 and an angle 190 on the platform
depending plate 124. The cylinder is connectable to a
suitable pressurized fluid supply (not shown - preferably
pneumatic) and is operable to pull the platform 120 downwardly
with a controllable force overcoming the bias of the
compression springs 132, 134 and against the reaction of the
workpiece (tube 10) against the flat grinding face 22 of
grinding disk 20.
Thus in operating the aforedescribed apparatus, starting
with the carriage 90 being tilted away from the fixed frame 40
to an inoperative posture by actuating power cylinder 100 to
extend its reciprocable rod 102, a pouring tube 10 is first
inserted into the annular holder 30 and the chuck 52 is
secured. The electric motor 60 is then energized to rotate
the tube 10 about it~ axis. At the same time the power
cylinder 100 i9 reversed to swing the carriage 90 inwardly
toward the frame 40 and thereby to an operative posture with
2~ the grinding disk 20 located directly above the tube 10 and
the abra~ive face 20 thereof held at a slight angle, to
chamfer the tube end, in accordance with the attitude of
carriage 90 pre ~et by shim 110 and the adjustment bolts 82,
84. The tool driving motor 156 is energized and pressurized
fluid is introduced to the upper end of cylinder 180 to lower
the platform generally 120 thereby extending the spinning
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grinding disk 20 downwardly until the abrasive surface 22
engages the end of tube 10. When grinding is complete the
fluid is released from cylinder 180 and compression springs
132, 134 will cause the platform 120 and grinding disk 20 to
be withdrawn upwardly. The tool driving motor 156 may be
deenergized and the power cylinder 100 is again activated to
extend its rod 102 thereby swinging the carriage 90 outwardly
to the inoperative position moving the grinding disk 20
completely clear of the annular holder generally 30 and the
tube 10 held therein. At that point the tube is extracted
upwardly and a new workpiece inserted downwardly.
The foregoing details have been provided to describe a
best mode of the invention and further variations and
modifications may be made without departing from the spirit
and scope of the invention which is defined in the following
claims.
