Abrasive slurry regulator assembly

The regulator assembly comprises body member carried by a support and defining a cavity for detaining a pool of abrasive slurry. An overflow device is associated with the body member for establishing the upper level of a pool of abrasive slurry in the cavity. At least one flow-restrictive conduit component is secured at one end to the body member, communicates with the cavity at the lower end of the pool of abrasive slurry, and presents an outer end from which abrasive slurry is discharged. One of the above-indicated elements is movable whereby to selectively adjust the vertical distance between the plane of the upper level of the pool of abrasive slurry and the plane of the outer end of the conduit component.

BACKGROUND OF THE INVENTION 
Conventionally, a freely flowing abrasive slurry is fed to the lapping disc 
of a lapping machine or the like. The abrasive slurry is usually 
circulated by means of a pump a delivered to the lapping disc through 
flow-restrictive discharge tubes or conduit means. Heretofore, it has been 
extremely difficult to maintain a constant discharge rate of abrasive 
slurry because of variations in pressure and flow of the pump, and it has 
also been difficult to adjust conveniently the discharge rate for 
different operating conditions, because of the perverse nature of various 
slurries. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the flow-restrictive discharge 
tubes are incorporated in a regulator assembly. The abrasive slurry 
received from the pump by the regulator assembly is detained in a pool at 
a given level established by overflow means, and the flow-restrictive 
discharge tubes convey the abrasive slurry from the lower end of the pool 
to the lapping disc. 
By reason of the detention pool of abrasive slurry, the regulator assembly 
maintains a constant fluid head, and hence provides a constant discharge 
rate of abrasive slurry, irrespective of variations in pressure and flow 
of the pump. 
Also, in the regulator assembly of the present invention, the fluid head is 
selectively adjustable for conveniently adjusting the discharge rate of 
the abrasive slurry whereby to accommodate differing operational 
requirements of the lapping machine. Depending upon the particular 
embodiment of regulator assembly, the fluid head is adjusted either by 
varying the level of the pool of abrasive slurry or by varying the level 
of the outer ends of the discharge tubes.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, there is indicated generally by the reference 
numeral 10 a typical lapping machine with which is incorporated an 
abrasive slurry regulator assembly 12 embodying the principles of the 
present invention. 
The lapping machine 10 comprises a framework including a tubular base or 
housing 14 which provides support for a horizontal annular lapping disc 16 
and a staging table 18 surrounding the lapping disc. Selective rotation of 
the lapping disc 16 about a vertical axis is effected by suitable drive 
means (not shown) mounted within the housing 14. Suitably secured to the 
opposite sides of the housing 14 are lower ends of vertical columns 20. 
Extending between the upper ends of the columns 20, above the lapping disc 
16, is a horizontal bridge member 22 provided with lateral arms 24 which 
number four in the particular lapping machine herein disclosed. Mounted at 
the outer ends of each of the lateral arms 24 is a vertical pneumatic 
piston and cylinder assembly 26. Each of the pneumatic assemblies 26 
includes a cylinder 28 and a piston rod 30. The lower ends of the piston 
rods 30 are secured to horizontal pressure plates (not shown) which fit, 
with slight clearance, within truing and retaining rings 32 engageable 
with the lapping disc 16. 
When the lapping disc 16 is rotated, the truing rings 32 rotate relative to 
the pressure plates about the axes defined by the piston rods 30 whereby 
to dress the lapping disc 16 for maintenance of its planar condition. When 
work pieces (not shown) are confined within the truing rings 32 below the 
pressure plates therein, and the lapping disc 16 is rotated, a freely 
flowing abrasive slurry--that is, a mixture of abrasive particles and an 
oil or other fluid carrier--is fed by the regulator assembly 12 to the 
lapping disc 16. 
As shown in FIG. 2, the regulator assembly 12 comprises a support or 
mounting flange 34, body means 36, overflow means 38, and flow-restrictive 
conduit means 40 which correspond in number to the number of truing rings 
32. The support 34 is suitably secured to the lapping machine bridge 
member 22, and is provided with inlet passageway means 42 connected by 
tubing 44 to a suitable source of abrasive slurry under pressure. The body 
means 36 is formed with a central axial bore defining a cavity or chamber 
46, an aperture 48 venting the cavity 46 to atmosphere, an overflow 
opening 50, a plurality of circumferentially spaced apart discharge 
apertures 52, an annular drip collar portion 54, and a lower threaded end 
section 56. The body means 36 is secured to the support 34 by a set screw 
58. The overflow means 38 includes a sleeve member 60 suitably secured in 
the overflow opening 50, and tubing 62 connected between the sleeve member 
60 ad the source of abrasive slurry under pressure for the return and 
recirculation of the abrasive slurry. Each of the conduit means 40 
includes an inner tube section 64 secured in one of the discharge 
apertures 52, an outer section 66 presenting an outer end overlying the 
space between an adjacent pair of the truing rings 32, and an intermediate 
flexible tube section 68 flexibly interconnecting the inner and outer tube 
sections 64 and 66. A selectively adjustable hand wheel 70 is threaded on 
the threaded end section 56 and at its outer periphery has engagement with 
the outer tube sections 66 of the several conduit means 40 for vertically 
angularly positioning the tube sections 66. Rotation of the hand wheel 70 
between the solid- and dotted-line positions effects vertical angular 
movement of the outer tube sections 66 between the solid- and dotted-line 
positions. 
In the operation of the regulator assembly 12, abrasive slurry is 
introduced through the inlet passageway means 42 into the cavity 46 where 
a pool of abrasive slurry 72 is detained. The lower inner edge of the 
sleeve member 60, which serves as a weir, establishes the upper level of 
the pool of abrasive slurry 72 in the cavity 46. This level remains 
substantially constant regardless of the amount of abrasive slurry 
introduced into the cavity 46; excess abrasive slurry flows into the 
overflow means 38. The conduit means 40 serve to convey abrasive slurry 
from the lower end of the pool of abrasive slurry 72 and to discharge the 
same from the outer ends of the outer tube sections 66 to the spaces 
between the adjacent pairs of the truing rings 32. 
The rate at which abrasive slurry is discharged from the conduit means 40 
is a function of the viscosity and specific gravity of the abrasive 
slurry, of the composite flow resistance of the conduit means 40, and of 
the fluid head of the abrasive slurry. The flow resistance of each conduit 
means 40, in turn, is a function of the inner diameter and length thereof. 
The fluid head of the abrasive slurry is equal to the vertical distance 
"h" between the plane of the upper level of the pool of abrasive slurry 72 
and the plane of the outer ends of the outer tube section 66 of the 
conduit means 40. For a given fluid head and conduit means 40 of a given 
size, the discharge rate of abrasive slurry will stabilize at a point 
where the flow resistance and the fluid pressure at the outer ends of the 
outer tube sections 66 are equal. For any number of conduit means 40 of 
equal size, the discharge rate from each is substantially identical. The 
discharge rate of the abrasive slurry may be regulated by rotating the 
hand wheel 70 which alters not only the inclinations of the outer tube 
sections 66 but also the fluid head of the abrasive slurry (the distance 
of the outer ends of the tube sections 66 below the upper level of the 
pool of abrasive slurry 72). Because the inclinations of the several tube 
sections 66 are adjusted simultaneously and equally, the change in 
discharge rate from each conduit means 40 is substantially identical. 
A modified embodiment of regulator assembly 74 is shown in FIG. 3. The 
regulator assembly 74 comprises a support or mounting flange 76, body 
means 78, overflow means 80, and flow-restrictive conduit means 82. The 
support 76 is adapted to be secured to the lapping machine bridge member 
22, and is provided with inlet passageway means 84 adapted to be connected 
by tubing 86 to a suitable source of abrasive slurry under pressure. The 
body means 78 is formed with a central axial bore defining a cavity or 
chamber 88, a vertical elongated opening 90 in the side thereof, and a 
plurality of bottom circumferentially spaced apart discharge apertures 92. 
The body means 78 is secured to the support 76 by a set screw 94. The 
overflow means 80 includes a sleeve member 96 which is vertically slidably 
mounted on the body means 78 and which is formed with an aperture 98 
aligned with and vertically positionable along the elongated body opening 
90. Seal means between the sleeve member 96 and the body means 78 are 
provided by O-rings 99. The sleeve aperture 98 is adapted to be connected 
by tubing 100 to the source of abrasive slurry under pressure for the 
return and recirculation of the abrasive slurry. Each of the conduit means 
82 is in the form of a tube 102, the upper inner end of which is secured 
in one of the discharge apertures 92 and the lower outer end of which is 
adapted to overlie the space between an adjacent pair of the truing rings 
32. 
In the operation of the regulator assembly 74, abrasive slurry is 
introduced through the inlet passageway means 84 into the cavity 88 where 
a pool of abrasive slurry 104 is detained. The lower edge of the sleeve 
aperture 98, which serves as a weir, establishes the upper level of the 
pool of abrasive slurry 104 in the cavity 88. For a given position of the 
sleeve member 96, this level remains substantially constant; excess 
abrasive slurry flows through the aperture 98 into the tubing 100. The 
conduit means 82 are adapted to convey abrasive slurry from the lower end 
of the pool of abrasive slurry 104 and to discharge the same from the 
outer ends of the tubes 102 to the spaces between the adjacent pairs of 
the truing rings 32. 
The fluid head of the abrasive slurry is equal to the vertical distance "h" 
between the plane of the upper level of the pool of abrasive slurry 104 
and the plane of the outer ends of the tubes 102. To regulate the 
discharge rate of the abrasive slurry, the sleeve member 96 may be 
vertically moved between the solid- and dotted-line positions whereby the 
sleeve aperture 98 and the upper level of the pool of abrasive slurry 104 
are selectively adjusted thereby altering the fluid head of the abrasive 
slurry (the distance of the upper level of the pool of abrasive slurry 104 
above the outer ends of the tubes 102). In other functional respects, the 
regulator assembly 74 is substantially identical to the regulator assembly 
12. 
Another modified embodiment of regulator assembly 106 is shown in FIG. 4. 
The regulator assembly 106 comprises a support 108, overflow means 110, 
body means 112, and flow restrictive conduit means 114. The support 108 
includes a mounting flange 116 and a depending distributor 118 secured 
thereto by a set screw 120. The mounting flange 116 is adapted to be 
secured to the lapping machine bridge member 22, and is provided with 
inlet passageway means 122 connected by tubing 124 to a suitable source of 
abrasive slurry under pressure. The distributor 118 comprises a sleeve 
section 126 provided with a bottom closure disc 128 and formed with a 
plurality of radial ports 130. The overflow means 110 includes an overflow 
receptacle 132 having a bottom opening 134 connected by tubing 136 to the 
source of abrasive slurry under pressure of the return and recirculation 
of the abrasive slurry. The receptacle 132 is secured to or suspended 
below the sleeve section 126 by connecting portions 138. If desired, the 
sleeve section 126 and the receptacle 132 may be fabricated from a single 
tubular member by forming partial cutouts in the side thereof. The body 
means 112 includes an annular casing 140 which is vertically slidably 
mounted on the sleeve section 126 and the receptacle 132, which defines 
with the receptacle 132 an annular cavity or chamber 142. Seal means 
between the casing 140 and the sleeve section 126 and receptacle 132 are 
provided by O-rings 143. A plurality of bottom circumferentially spaced 
apart discharge apertures 144 are formed in the body of the casing 140. 
Each of the conduit means 114 is in the form of a tube 146 the upper end 
of which is secured in one of the discharge apertures 144 and the lower 
outer end of which is adapted to overlie the space between an adjacent 
pair of the truing rings 32. 
In the operation of the regulator assembly 106, abrasive slurry is 
introduced through the inlet passageway means 122 into the distributor 118 
from which it flows through the ports 130 into the cavity 142 where a pool 
of abrasive slurry 148 is detained. The upper edge of the receptacle 132, 
which serves as a weir, establishes the upper level of the pool of 
abrasive slurry 148 in the cavity 142. This level remains substantially 
constant; excess abrasive slurry flows into the overflow receptacle 132. 
Th conduit means 114 are adapted to convey abrasive slurry from the lower 
end of the pool of abrasive slurry 148 and to discharge the same from the 
outer ends of the tubes 146 to the spaces between the adjacent pairs of 
the truing rings 32. 
The fluid head of the abrasive slurry is equal to the vertical distance "h" 
between the plane of the upper level of the pool of abrasive slurry 148 
and the plane of the outer ends of the tubes 146. To regulate the 
discharge rate of the abrasive slurry, the casing 140 may be vertically 
moved between the solid- and dotted-line positions whereby the depth of 
the pool of abrasive slurry 148 and the vertical positions of the outer 
ends of the tubes 146 are selectively adjusted thereby altering the fluid 
head of the abrasive slurry (the distance of the outer ends of the tubes 
146 below the upper level of the pool of abrasive slurry 148). In other 
functional respects, the regulator assembly 106 is substantially identical 
to the regulator assembly 12. 
While there have been shown and described preferred embodiments of the 
present invention, it will be understood by those skilled in the art that 
various rearrangements and modifications may be made therein without 
departing from the spirit and scope of the invention.