An automated lapping system employing a rotating table with a horizontal lapping surface and one or more parts tracks with escapement mechanisms for regulating the rate at which parts cross the lapping table. Each parts track is suspended above the rotating surface of the table, and confines the parts to move in single file across the surface of the rotating table. Multiple stations are provided along each track to cause each part passing through the track to stop for a predetermined amount of time at each station. The escapement mechanisms control the stopping and releasing of the parts along each track at the stations. Selected stations, called powered lapping stations, are provided on each track for applying positive downwardly-directed pressure to the part stopped at the station. These powered lapping stations and the escapement mechanisms preferably employ hydraulic or pneumatic cylinders for actuators. All of the powered lapping stations and escapement mechanisms associated with a single track may be operated by a common set of directional control valves.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates in general to automatic lapping machines, and 
in particular to automatic lapping machines which feed one or more streams 
of parts onto and off of a lapping table without human intervention. 
2. Description of Related Art 
Traditional lapping machines have a large horizontally-arranged, generally 
circular table provided with multiple, pie-shaped lapping stone sections 
arranged around a common central vertical axis. A suitably sized electric 
motor provides the motive power to rotate the table through a conventional 
clutch-brake and gear reducer combination. The lapping table may include 
two, three or four heavy conditioning rings equiangularly spaced around 
the table. The lower annular slotted surface of each conditioning ring 
rubs against the table and serves to help keep the surface of the lapping 
stones very flat. A supply of conventional lapping compound and cleansing 
lubricant is continuously pumped onto the table by a recirculating pump 
system to help carry away metal lapped off the parts being processed and 
any disintegrated lapping stone. This fluid is filtered to remove the fine 
metal particles and debris suspended in the fluid, and then is 
recirculated. The conditioning rings themselves are held in place by 
conventional roller retainer wheels supported by a simple superstructure 
suspended above or to the side of the table. Mechanical or fluid-power 
means such as a hydraulic cylinder may be provided for raising or lowering 
one or more of the conditioning rings relative to the lapping surface of 
the table. The retainer wheels preferably include ball or roller bearings, 
and may be strategically placed about the inner circumference of the 
conditioning ring so that the conditioning ring can readily rotate about 
its own axis as the table rotates beneath it. This rotation of the 
conditioning rings is induced by the frictional forces caused by the 
rotation of the table. 
On a conventional lapping machine having four conditioning rings, only one 
or two of the rings are used for containment of parts being lapped. The 
remaining conditioning rings are not used for machining parts. Instead, 
they are employed to help condition the table surface and uniformly 
distribute lapping compound and lubricant on the lapping table. Parts 
having a generally flat bottom surface that is to be lapped are placed 
within one or two of the conditioning rings. As the table rotates, the 
conditioning rings and parts to be lapped each continuously revolve about 
their own central vertical axes, thus assuring a smooth and uniform lapped 
finish over the entire bottom surface of each part being lapped. 
One long-standing problem presented by the conventional lapping machines 
designed as just described relates to the loading and unloading of parts 
being lapped. Lapping cycles vary greatly, depending upon the parts the 
material they made of, and the quality of the finish desired, from as low 
as about one minute up to several hours. However, during a typical lapping 
cycle of five or ten minutes, for example, a significant amount of cycle 
time is required to start and stop the table, and unload and load of the 
parts. Traditionally, the individual parts have been removed from the 
conditioning rings and inserted into the conditioning rings manually. One 
technique for loading parts is to place them by hand in a circular 
configuration on a flat board. When the conditioning ring is in an 
elevated state, the board is then placed under the raised ring in the area 
normally occupied by a conditioning ring. The ring is then lowered, and 
the table is started up, so it begins to rotate again. To unload finished 
parts, the process is reversed. 
Recently, automatic loaders for such machines have been provided which 
shuttle the rings in and out of the table onto flat load/unload surfaces 
at the same height as the table's lapping surface. Although the table 
still rotates, the ring containing parts are to be removed from the 
lapping machine is no longer in productive use when that lapping ring is 
moved off of the table onto a nearby loading/unloading platform. The net 
result is a significant loss of productivity when a ring is being loaded 
or unloaded, even though the table continues to rotate, since no parts are 
being lapped within that ring for as long as it takes to unload the ring, 
and load it with new parts. 
As part of the conventional lapping processes described above, a large and 
heavy one-piece weight plate is typically placed over the many parts 
within an individual conditioning ring. If desired, a piece of cushioning 
material such as synthetic felt may be placed between the parts and weight 
plate. In this situation, the tallest parts are necessarily subjected to 
heavy forced lapping first, since all or most of the weight of the plate 
bears down on these taller parts. Those parts of lower height are lapped 
only by the force gravity exerts on the part until the higher parts are 
lapped down to a uniform height, at which time the weight of the plate 
begins to bear down on those parts as well. This approach to lapping parts 
necessarily requires a lapping cycle sufficiently long to ensure that the 
taller parts are lapped down to the height of the shorter parts, and that 
the lower-height parts will then receive a minimum desired amount of 
lapping, as required to obtain the desired surface finish. 
In light of the foregoing shortcomings of prior art lapping systems, it is 
a primary object of the present invention to provide a lapping system and 
method which allows parts to automatically be loaded onto and 
automatically removed from a rotating lapping table having a horizontal 
lapping surface without human intervention. It is a related object of the 
present invention to provide a lapping apparatus which causes parts to be 
lapped to move single file in one or more streams across a lapping table, 
by action of the rotating table rubbing on the parts to be lapped. 
It is a further object of the present invention to provide a parts track to 
guide the parts in a single file across the table. A related object is to 
provide escapement mechanisms for controlling the timing of movement of 
the parts between specified locations, which may be called stations, 
located along the parts track, so as to closely regulate the amount of 
lapping each part receives. It is another object of the present invention 
to provide multiple tracks and escapement mechanisms for feeding parts to 
be lapped in parallel streams across a rotating lapping table. 
It is yet another object of the present invention to provide individual 
powered lapping stations where a positive downwardly-directed force is 
selectively applied to a part to be lapped to increase the rate of 
material removal from the lapping table. One more object of the present 
invention is provide a lapping system capable of efficiently lapping parts 
of uneven height in a minimum amount of time. 
SUMMARY OF THE INVENTION 
In light of the foregoing problems and in order to fulfill the foregoing 
objects, there is provided a thru-feed lapping apparatus. The apparatus 
comprises: a power-driven lapping table having a smooth, substantially 
continuous, generally cylindrical lapping surface, first track means for 
automatically guiding parts having at least one surface to be lapped 
across the lapping surface of the table; and first automatically-operated 
escapement means for selectively blocking the forward movement of parts to 
be lapped through the first track means, and for selectively releasing 
parts to proceed along the first track means. The foregoing automatic 
thru-feed lapping apparatus preferably has multiple tracks for feeding 
parts to be lapped across the table. The tracks are preferably straight 
and arranged parallel to one another. 
The thru-feed lapping apparatus of the present invention may be retrofitted 
onto existing lapping machines by removing one or two of the conventional 
conditioning rings from a lapping machine and replacing them with two or 
more substantially straight tracks that are parallel to one another. In a 
prototype apparatus of the invention, four parts tracks are used. However, 
the number of tracks may vary from one to as many as may be as may be 
accommodated on the available space of the lapping table. The precise 
number of tracks may well be dictated by the effective working radius of 
the table in comparison to the size of the part. 
In our preferred design, commonly-operated multiple escapement mechanisms 
are provided along each parts track for selectively blocking progress of 
parts to be lapped while such parts are guided by the track. These 
escapement mechanisms each selectively stop the part for a predetermined 
period of time, and then release the part so that it may proceed along the 
parts tracks. The escapement mechanisms are spaced from one another along 
the track, and each includes at least one mechanical stop movable between 
a blocking position where the parts are stopped and a "clear" position 
which allows the parts to proceed in a forward direction along the track. 
To speed up the operation of the lapping machine, powered lapping means may 
be provided. Basically, at each location of the track where more vigorous 
lapping of parts is desired, a hydraulic or pneumatic power cylinder may 
be utilized to provide positive downwardly-directed pressure to bear upon 
the top of the part. This produces a much more vigorous lapping action on 
the bottom surface of the part which bears against the lapping surface of 
the table. Such locations may be called powered lapping stations, and will 
typically be provided along the early stations of the track. Each such 
station may apply a predetermined amount of force onto the part to provide 
for a rough lapping stage within the continuous operation. A number of 
rough lapping stages can be provided, and if desired, each may have a 
tailored force to achieve a desired amount of lapping at a particular 
location of the lapping track. Then, at later stations along the track, 
gravity alone may be utilized to provide the downward force upon the 
parts, so as to produce a smoother finish on the lapped surface of the 
part. 
The location of the various stations may be staggered along the parallel 
tracks, so as to provide for substantially equal wear on the lapping 
surface of the table at various radii from the center of the table, and to 
provide for equal lapping of the parts no matter which track they may move 
along. Also, since there is less linear travel across the lapping surface 
provided by the outer tracks, the lapping stations of the outer tracks may 
need to be placed closer together.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
An exemplary automated thru-feed lapping system will now be described with 
respect to the Figures. While the apparatus which will be described is the 
presently preferred embodiment of the invention, those in the art should 
appreciate it is susceptible to variation, modification and improvement 
without departing from the broader scope of our invention. 
FIGS. 1 and 2 show a simplified top and plan view of an automatically 
loaded and unloaded thru-feed lapping system 30. The system 30 includes a 
rotating lapping table 32 surrounded by a circular trough 34 which 
contains and captures lapping compound applied to the table. Any 
conventional lapping table may be used with the thru-feed lapping system 
of the present invention, such as a Lappmaster table or Speedframe table. 
The table is supported by a conventional base 36, shown in FIG. 2. The 
table is driven by an electric motor 38 through a conventional clutch and 
gear-reducer combination 40, which translates the high-speed rotation of 
motor 38 into a suitably slower speed rotation of vertical drive shaft 42, 
which may be driven by any suitable gear arrangement, such as gears 43 and 
44. The table 32 may rotate at a suitable speed such as 60 to 150 rpm. 
The superstructure 45 supports conditioning ring assemblies 46 and 48 and 
the parts track assembly 50 above the table 32, and a set 52 of hydraulic 
valves 54a-54d, and a small reservoir 58 for lapping compound distributed 
by flexible tubing 60 and 62 to the lapping rings 46 and 48. A 
conventional hydraulic power supply 64, including electric drive motor 66, 
hydraulic pump 68 and reservoir 70, are connected to the valves 54 by 
supply and return conduits 72 and 74. A conventional recirculating lapping 
compound filter system 80 includes an electric drive motor 82, pump 84 and 
reservoir 86 connected by supply and return conduits 88 and 90. 
The parts track assembly 50 includes a main section 94, a load magazine 
section 96, and a parts removal section 98 which feeds parts to take-away 
conveyor system 100. There are four magazine tracks 102, 104, 106 and 108 
which feed parts into four distinct part tracks whose center lines are 
represented by dashed lines 112, 114, 116 and 118. After the parts from 
magazines 102-108 pass through their respective tracks 112-118, they drop 
through respective openings 122-128 onto revolving turntable platters 130 
and 132 driven by electric motors 134 and 136. The dropped parts then 
contact stationary stops 140 and 142, which force them to drop onto 
endless belt conveyor 150, which carries them to endless belt conveyor 
152, that takes them to the next operation, which may be a washing machine 
that removes the lapping compound from the finished parts. 
As shown in FIG. 1, the system 30 may also include an electric control 
panel 160, which may be connected by suitable electrical conductors in 
conduit 162 to the valves 54. Other conduits (not shown) may provide 
electrical power and control signals from the control panel 160 to other 
electrical devices such as motors, limit switches, solenoids and the like, 
located on the machine. An operator control station 166 including 
pushbuttons such as button 168 and indicator lights such as light 171. The 
electrical control panel 160 and operator station 166 may be constructed 
of conventional control components and include timing, and logic control 
circuits to operate the machine in the manner described herein. The design 
and construction of the control panel 160 and operator station 166 needed 
to implement the automatic operation of the lapping system 30 is well 
within the skill of those in the art once the automatic operation of the 
machinery is described with respect to FIGS. 1 through 9. Thus the control 
circuitry need not be described further, other than to note that it may be 
implemented using any conventional or suitable components, such as 
electromechanical relays, modular solid-state control circuits or by a 
computerized system having a suitable number of inputs and outputs, such 
as any one of several programmable controllers now in common use in many 
different types of industrial machinery. 
The superstructure 45 includes a main top horizontal member 170 supported 
by transverse horizontal member 172 connected to vertical support columns 
174 and 176. The left end of beam 170 is supported by vertical support 
column 178. Vertical beams 174-178 are suitably bolted to the floor 180. 
The conditioning ring assemblies 46 and 48 are supported by central 
transverse horizontal beam 182 which has vertical beams 184 and 186 
connected to and extending downwardly from either end thereof. 
The superstructure 45 also includes top transverse member 192 supported by 
beam 170. Vertical members 194 and 196 extend downwardly from either end 
of beam 192. Short beams 198 and 200 extend outwardly to the inner 
elongated side 202 of main section 94 of the parts track assembly 50. 
Longer horizontal beams 204 and 206 respectively extend from vertical legs 
174 and 176 to the outer elongated side 208 of main section 94. Thus, 
short horizontal beams 198 and 200 and long horizontal beams 204 and 206 
support and suspend the parts track 50 a predetermined distance above the 
table 32, as is best seen in FIG. 2. 
The lapping table 32 is preferably made of a plurality of pie-shaped 
lapping stone sections 221 through 226, which may be supported by a common 
cylindrical metal plate 228, which may in turn be supported by any 
suitable means, such as rollers 230 through 236, provided under the table 
and supported by stationary cylindrical frame 240 that is part of the base 
36. A central section 242 may be provided if desired in the center of 
table 32 into which the vertices of the pie-shaped stone sections 221-226 
are anchored. The pie-shaped lapping stone sections 221-226 may comprise 
substantially identical, generally pie-shaped, equiangularly lapping stone 
sections arranged about the central vertical axis of the lapping table, 
the pie-shaped lapping stone sections each having an upper, planar 
surface, with all of such upper planar surfaces of these stone sections 
forming the substantially continuous lapping surface. 
The conditioning ring assemblies 46 and 48 may have large, conventional 
conditioning rings 246 and 248 made of hardened steel. The rings 246 and 
248 rest against the table and are supported for rotation about their 
centers by three roller wheels such as wheels 251, 252 and 253 supported 
by triangular frame 254 connected to stationary vertical member 184 in any 
conventional manner. If desired, the frame 254 may include a conventional 
fluid power cylinder (not shown) for raising and lowering the lapping ring 
246 off of the horizontal surface 260 of the table 32. 
FIGS. 3 and 4 are enlarged plan and side views respectively of the parts 
track assembly 50 showing its overall construction and the arrangement of 
various escapement mechanisms on the main parts tracks and loading 
magazines. The details of the main section 94 and four parts tracks 
112-118 will be described first, followed by a description of the 
arrangement of the individual lapping stations on the tracks. 
The main section 94 includes five elongated rectangular tubular frame 
members 271, 273, 275, 277 and 279 into which are fit complementary 
rectangular members 281, 283, 285, 287 and 289 that may each be rigidly 
connected to tubular cross piece 290. The opposite ends of the rectangular 
tubes 271-279 are respectively connected to the end piece 292, shown in 
FIG. 1. 
Main section 94 also includes lower and upper plates 294 and 296 which 
extend horizontally over substantially the entire length of elongated 
tubular members 271-279. The plates 294 and 296 are kept apart from one 
another by cylindrical spacers 300 placed at regular intervals between the 
upper and lower plates 294 and 296. The plates 294 and 296 may be held 
together by any suitable means, including threaded holes in lower plate 
294, and tie bolts passing through holes in upper plate 296 and extending 
through the centers of cylindrical spacers 300. Two vertical reinforcing 
plates 308 and 310 may be provided along inner side 208 of main section 
94. Similarly, vertical reinforcing plates 314 and 316 may be provided 
along outer side 204 of main section 94 as shown in FIG. 3. Horizontal 
support members 198 and 200 may then be welded or otherwise rigidly 
attached to reinforcing plates 308 and 310. Similarly, horizontal support 
members 204 and 206 may be bolted or otherwise rigidly fastened to 
reinforcing plates 314 and 316 as shown in FIG. 3. In this manner, the 
frame 94 is rigidly suspended a fixed distance or height 320 above the 
surface 260 of table 32. This distance may be anywhere from 0.5 
centimeters (cm) to 5.0 cm or more, and is dictated by the overall height 
of the parts to be lapped. For example, where the part to be lapped is 
only about 1.5 cm high, the gap 320 may be in the range from 0.5 cm to 1.0 
cm. This relationship is shown more clearly in FIG. 5 which shows the gap 
320 in comparison to the height 322 of the part shown in phantom there. 
FIG. 3 also shows that the first through fourth parts tracks 112-118 are 
respectively formed by adjacent pairs of elongated tubular members or 
rails 271-279. For example, the first or innermost parts track 112 
includes rails 271 and 273, the second parts track 114 is formed by rails 
273 and 275, the third parts track 116 is formed by rails 275 and 277, and 
the fourth parts track 118 is formed by rails 277 and 279. 
In FIG. 3, parts are shown in various positions along the first loading 
magazine 102 and the first parts track 112. For ease of understanding, the 
parts are shown in solid, as though the upper plate 296 did not exist. In 
practice, the plate 296 actually obscures the location of all of the parts 
in the first track 112 and the other tracks. The illustrated parts have a 
cylindrical shape when viewed from the top. The three complete parts shown 
in magazine 102 are numbered 327 through 329, while the parts along the 
first track 112 are numbered from 330 through 341. There are 12 distinct 
lapping stations along the first parts track 112, and the general 
locations of these lapping stations corresponds with the part 330 (station 
1-0) through part 341 (station 1-11). The station 1-0 has a single 
cylinder assembly 350 associated with it, which is provided to ensure the 
orderly movement of parts from the magazine 102 into the station 1-1 which 
follows. Stations 1-1 through 1-5 are powered lapping stations, each of 
which includes three cylinder assemblies sequentially located one after 
another. Lapping stations 1-6 through 1-11 are finish lapping stations, 
and each has only one cylinder assembly associated with it. 
A study of the second, third and fourth parts tracks 114, 116 and 118 in 
FIG. 3 reveals that they contain 10 stations, 11 stations and 10 stations 
respectively, including a transition station (station 0), five powered 
lapping stations (stations 1-5), and five or six finish lapping stations 
(stations 6-10 or 11). FIG. 4 shows the relative location of the cylinder 
assemblies of the fourth parts track 118 that are associated with 
transition station 4-0, power lapping stations 4-1 through 4-5 and five 
finish lapping stations 4-6 through 4-10. 
FIG. 4 also shows that the loading magazines 102-108 are inclined at a 
sufficient angle, so that gravity will cause the parts to advance in a 
forward direction toward the table. As best shown in FIG. 3, each of the 
loading magazines 102-108 includes a pair of escapement cylinders, such as 
first and second cylinders 360 and 362 on the fourth parts tracks. The 
rods of the first and second cylinders are shown in opposite positions. 
This is meant to illustrate that whenever the rod of first cylinder 360 is 
in its retracted position, as shown in FIG. 3, the rod of second cylinder 
362 is in its extended position. Similarly, when the rod of the first 
cylinder 360 is extended, the rod of the second cylinder 362 is retracted. 
A similar state of cylinder rods is shown by the escapement cylinders of 
the third magazine 106. The rod of the cylinder pairs associated with each 
magazine change state at the same time, with the net result being that 
parts stacked up in each magazine are ejected one at a time from the lower 
end of the magazine into its respective parts track. The table 32 rotates 
in the direction indicated by arrow 370. Frictional forces between the 
rotating table and the parts ejected onto the table from the magazines 
102-108 cause the parts to advance in a forward direction along the 
respective parts tracks transition station (station 0), which is 
encountered promptly after being deposited upon the flat surface 260 of 
the table 32. 
As shown in FIG. 4, each of the parts magazines may be supported by a 
suitable bracket, such as brackets 376 and 378 attached to lower plate 294 
that respectively support magazines 106 and 108. The magazines, such as 
magazines 106 and 108, are preferably made of a pair of elongated U-shaped 
rails which face one another and are sized so as to contain the parts 
therein, while allowing the parts to slide by the action of gravity down 
the chute formed by the rails. Examples of the two rails are rails 380 and 
382 which form parts magazine 108 shown in FIG. 3. 
Those skilled in the art will appreciate that any suitable magazine design 
may be used, and that any suitable escapement mechanism which toggles 
parts one at a time out onto the table may be used with each magazine. 
FIG. 3 helps illustrate the operation and function of the transition 
station 1-0. As shown there, the rod of cylinder 350 extends down into the 
opening of parts track 112 formed between rails 271 and 273, so as to 
block passage of the part 330 shown behind it. Retracting the rod of this 
cylinder will raise the rod out of the way of the part so that the part 
may advance to the next station where a part 330a is shown in dotted 
lines. This kind of relationship is also illustrated in FIG. 4, where the 
cylinder 390 associated with station 4-0 is shown with its rod 392 in an 
extended position, thus blocking movement of parts along the track 118 
which are upstream of the rod 392. The operation of this transition 
station 0 cylinder assembly is also identical to that of the first 
cylinder in the group of three cylinders found at each lapping stations. 
FIGS. 5 and 6 help further illustrate the operation of the various cylinder 
assemblies found on the FIG. 1 machine. In particular, FIG. 5 is a 
detailed cross-sectional view of the various components of cylinder 
assemblies taken along line 5--5 of FIG. 3. This corresponds to lapping 
stations 4-5 and 4-6 of the fourth parts track 118. FIG. 5 thus shows an 
enlarged view of powered lapping station 4-5 and finish lapping station 
4-6 of the fourth parts track. The construction of this powered lapping 
station and of this finish lapping station are representative of the other 
powered lapping stations and finish lapping stations. Hence, when the 
operation of these two stations are understood, those skilled in the art 
will appreciate how all of the lapping stations found in automated parts 
tracks assembly 50 are constructed and individually operate. 
FIG. 5 shows that the typical powered lapping station 4-5 includes three 
fluid power cylinders 402, 404 and 406, while the typical finish station 
4-6 has only one fluid power cylinder 408. These four cylinders are 
rigidly attached by any conventional fasteners (not shown) to upper plate 
296. The plate 296 has holes 412, 414, 416 and 418 which extend through 
the plate 296 so that cylinder rods 422-428 respectively associated with 
cylinders 402-408 can move freely up and down. All of the cylinder rods 
are shown in their lowered positions in FIG. 5. At the lower free end of 
each of the cylinder rods 422-428 is a replaceable tool assembly which 
comes in contact with the part to be lapped. Each of these tool assemblies 
is threaded into a bore such as bore 429 shown in cylinder rod 422. One or 
two locking nuts such as nuts 430 and 431 are provided on each of the 
cylinder rods to help prevent loosening of the end rod tool, such as tool 
432, threaded into the respective bore of the cylinder rod. The tools 
432-438 respectively provided on the ends of cylinder rods 422-428 are 
each guided by one of the bushings 442-448, threaded through corresponding 
holes in the lower plate 294. Locking screws 452-458 fit in corresponding 
arcuate hollows machined into the bushings 442-448, and prevent the 
bushings from being backed out due to vibration while the system 30 is 
operating. Locking screws 452-458 may be of any suitable or conventional 
variety and are preferably of the type that will not back out on account 
of vibration. 
The function of end rod tool 432 is to stop parts traveling downstream, 
that is, in the direction indicated by arrow 460, until such time as they 
may be advanced to the position where part 462 is shown. End rod 434 bears 
down against the center of the part to be lapped and is used to apply 
extra downward force so that a correspondingly greater amount of material 
is lapped off of the bottom surface 464 of the part as the tble 32 
continuously rotates. The rod 426 of cylinder 406 is used to stop the part 
462 in the precise location desired prior to time that rod 424 of cylinder 
404 is lowered. In the finish lapping stations, the end rod 438 is used to 
stop the part such as part 468 shown in phantom upstream of stop rod 438. 
The lapping of the part in location 468 is accomplished by the force of 
gravity acting upon the part so as to make it bear against the lapping 
surface of the table. Worn end tooling 432-438 shown on the ends of 
cylinder rods 422-428 may be periodocally replaced as necessary. In order 
to reduce the amount of wear on the parts, this replaceable tooling may be 
wear-hardened using any conventional or suitable technique such as 
carburization, nitriding or induction hardening. 
FIG. 6 shows the parts handling apparatus 50 in a transverse 
cross-sectional view taken along line 6--6 of FIG. 3. In this view, the 
power lapping cylinder 404, is shown in the lowered position for first and 
third tracks 112 and 116 and in the raised positions for the second track 
114. Also, the vertical reinforcing plates 308 and 314 and the cylindrical 
spacer members 300 may be seen in this view separating the lower and upper 
plates 294 and 296 by a predetermined distance. 
FIG. 7 shows a part of a typical hydraulic system which may be used to 
operate the cylinders associated with one of the tracks of part handling 
apparatus 50, such as the first track 112. The hydraulic system used to 
operate each of the other parts tracks may be substantially identical. As 
previously explained, there are three different types of cylinders, namely 
stop (or "load-station") cylinders, power lap cylinders and position (or 
"unload-station") cylinders. Specifically, as shown in FIG. 3, the first 
parts track 112 has eleven stop cylinders, five power lap cylinders and 
five position cylinders. All of the stop cylinders may be operated by a 
common two-position, four-way solenoid-operated, spring-returned 
directional control valve 54a which supplies fluid via the common lines 
476 and 478 to the eleven cylinders 350-360 associated with station 1-0 
through station 1-10. A separate pressure reducing valve 480 may be 
utilized to control the amount of pressure in the hydraulic fluid being 
applied to the cylinders. A second directional valve 54b is used to 
operate the powered lapping cylinders associated with stations 1-1 through 
1-5 via hydraulic conduit or lines 482 and 484. A common pressure-reducing 
valve 486 may be used to control the amount of hydraulic pressure to these 
lines. 
The third set of cylinders, namely the position cylinders, are operated by 
another directional valve 54c which supplies hydraulic fluid via lines 488 
and 490 to the position cylinders associated with stations 1-1 through 
1-5. Once again, a pressure reducing valve 492 may be provided if desired 
to control the pressure of hydraulic fluid delivered to the position 
cylinders. The hydraulic circuit of FIG. 7 shows that the stop cylinders 
of the first parts track operate in unison, all of the power lap cylinders 
of the first parts track operate in unison, and all of the position 
cylinders of the first parts track operate in unison. This simplifies the 
designing of controls to operate the parts handling apparatus 50 by 
reducing the number of hydraulic directional valves required to operate 
the system. 
Those in the art will appreciate that the hydraulic circuit for operating 
the other parts tracks may be substantially identical to the circuitry 
shown in FIG. 7. Alternatively, if desired, the stop cylinders of one or 
more of the other tracks may be operated in parallel off of lines 476 and 
478 for one or more of the other tracks. For example, the first and third 
tracks might be caused to operate in unison and the second and fourth 
tracks might be caused to operate in unison. In this manner, the number of 
hydraulic components can be reduced still further. 
FIG. 8 shows a typical pneumatic circuit for operating the escapement 
mechanisms for one of the load magazines, such as magazine 108. 
Specifically, FIG. 8 shows that pressurized air on shop air line 500 is 
supplied through a conventional filter regulator unit 502 to line 504 
which supplies two-position, four-way, solenoid-operated, spring-returned 
directional valve 506 with pressurized air, which is then fed through 
lines 510 and 512 to a pair of escapement cylinders, such as cylinders 360 
and 362, associated with magazine 108. Thus, whenever the solenoid 508 of 
valve 506 is energized, pressurized air from regulator 502 is diverted 
from line 510 to the opposite line 512, which causes the cylinders 360 and 
362 to change state. Thus, each time the valve 506 is cycled by energizing 
and de-energizing solenoid 508, another part to be lapped is cycled out 
onto the table. 
FIG. 9 is a timing diagram which shows one preferred method for operating 
the stop, power lap and position cylinders of a common parts track, such 
as parts track 112, in a coordinated fashion so as to process a maximum 
number of parts in a minimum time. In FIG. 9, the state of each of these 
types of cylinders is shown at each instant along a common time 520, which 
depicts three successive cycles during the operation of the system 30. 
Time T0 shows the states of the rods of the various cylinders of parts 
track 112 in their initial position. The first complete cycle of operation 
involves three identifiable cylinder transition times, namely times T1, T2 
and T3. The second complete cycle is a duplicate of the first cycle, and 
for clarity its transition times are labelled as times T11, T12 and T13. 
The third and subsequent cycles are identical to the first cycle as well. 
For clarity, transition times of the third cycle are labelled T21, T22 and 
T23. The line 522 shows the position or state of the rod of parts magazine 
cylinder 362, i.e., the rod is either extended, which blocks the part, or 
is returned, which releases the part. The line 524 shows the state of the 
rod of each of the stop cylinders of stations 1-0 through 1-10, which 
either are all up, thereby allowing parts to pass thereunder, or are all 
down, thereby blocking the passage of the parts through the stations 
associated with the cylinders. In a similar manner, lines 526 and 528 
respectively represent the states of rods of the powered lapping cylinders 
of stations 1-1 through 1-5 and the position cylinders of stations 1-1 
through 1-5, which move up and down at selected transition times as shown. 
The periods between the transition times may be adjusted as desired to 
achieve the desired amount of lapping time at successive stations, and to 
ensure that the parts moving along the parts track are stopped as desired 
upstream of each lowered cylinder rod. Conventional adjustable analog or 
digital electronic timers may be used within the control panel 160 shown 
in FIG. 1 to set these times as desired. 
An overall advantage of the thru-feed operation of the present invention is 
that the parts never need to be removed from the tracks, and thus can be 
automatically fed, without human intervention into a subsequent operation, 
such as a washing machine to remove the lapping compound from the part 
before additional machining or assembly steps. Another advantage is that 
the parts loading mechanism, since it is a magazine or track, can receive 
parts, without human intervention, from another earlier automation 
station. 
All of the lapping stations of the present invention may be functionally 
identical, except some do not utilize power cylinders to promote more 
vigorous lapping action. In particular, the finishing stations where the 
weight of the part alone is sufficient to produce the desired lapping 
rate, it is not necessary to use the power cylinders. 
The staggering of the locations of stations along the four tracks may be 
used to provide for equal lapping of parts no matter which track they move 
along. This may be accomplished as shown by crowding more lapping 
locations along the outer track, since there is less linear travel across 
the lapping wheel provided at that point. As will be appreciated, the 
locations of the various lapping stations can be varied along the 
individual tracks as desired to produce the desired amount of lapping. 
As may be seen from the plan view of the lapping table in FIG. 1, there is 
room for providing one or more lapping tracks on the opposite side for 
finishing parts there. This may be accomplished by adding the additional 
lapping tracks to the left on the conditioning rings 46 and 48. The parts 
would be fed through in a direction which permits the rotation of table 32 
to cause the parts to move from station to station, as is done with parts 
track assembly 50. Those skilled in the art will appreciate that a part 
that must be lapped on both sides can simply be turned over in a suitably 
designed power conveyor and run back through the machine on another track 
so that 2-sided lapping can be accomplished substantially continuously on 
a sequential basis using this invention. 
Using the conventional technology described in the background portion of 
this application, two persons were able to make 844 parts per hour on a 
conventional 84-inch lapping table. The parts in question were thrust 
plates or pressure plates for use in power steering pumps. With our new 
automatic thru-feed lapping system and process, which has been described 
above, the production rate has been increased for these same parts to 
about 1300 parts per hour with only one person loading the machine having 
the automatic thru-feed lapping system and process. Unloading is 
accomplished automatically as described above. The finished quality at 
this higher rate of production is at least as good as that achieved with 
the old process. 
Another advantage of the present invention is that it appears to produce 
more uniform and quicker lapping of parts of uneven height. As explained 
above, the lapping system and method of the present invention provides for 
consistent uniform lapping of parts of varying heights since each part is 
treated individually as it proceeds through the feed-through lapping 
mechanism. 
The foregoing detailed description shows that the preferred embodiments of 
the present invention are well suited to fulfill the objects above-stated. 
It is recognized that those skilled in the art may make various 
modifications or additions to the preferred embodiments chosen to 
illustrate the present invention without departing from the spirit and 
proper scope of the invention. For example, the number and orientation of 
the parts tracks may be varied. Also, different arrangements and spacings 
for the powered lapping stations may be utilized. Further, pneumatic 
rather than hydraulic cylinders may be used if desired to provide the 
positive downwardly-directed force against the parts. Accordingly, it is 
to be understood that the protection sought and to be afforded hereby 
should be deemed to extend to the subject matter defined by the appended 
claims, including all fair equivalents thereof.