Automatic or manual four-axes sanding machine system for sanding and/or finishing a vertically held contoured part

A vertical wing skin sanding machine which includes one or more sanding stations, dust/sound enclosure, operator console, and dust collectors all mounted on a common trolley designed to travel a linear path over the required length. The system provides an opening bisecting the device to allow for finishing the stationary part on both sides of the part. The system provides a mechanical means of propulsion of the device and guide rolls to stabilize, sound damp, and direct the part by the finishing wheel.

The present invention relates to vertical wing skin sanding methods and 
apparatus and, more particularly, to a vertical wing skin sanding system 
which provides an opening bisecting the device to allow for finishing the 
stationary part on both sides of the part including means of propulsion of 
the device and guide rolls to stabilize and direct the part by the 
finishing wheels. 
Prior attempts to solve the problem of vertical wing skin sanding over the 
last twenty years have included floor sanders and hand sanding in a lay 
down position. Those methods are both labor intensive and require 
excessive floor space. Recent attempts have included a multiple disc 
rotary counterbalanced sanding head. This method required an elevated 
platform and ten operators; it was neither efficient nor capable of 
maintaining the production rate required. 
In the patent literature, U.S. Pat. Nos. 3,807,098 and 3,717,892 teach the 
use of master control systems for automatic grinding and finishing 
operations, while U.S. Pat. Nos. 2,269,197; 2,881,570; and 3,823,455 
describe the use of flap wheels and buffers being mechanically directed to 
accomplish the finishing operation over a contoured area. 
In contrast, the present sanding machine system includes means for sanding 
vertically held contoured wing skin by shot peen and further includes 
methods and apparatus for transporting the wing skin and lowering it into 
the wing skin sanding machine. 
In accordance with a preferred embodiment of the invention, an operator 
sets a set of heads (two sets per side) for the predetermined area of 
desired sanding operation. The operator adjusts the height (Y motion), 
radial (C motion) and feed rate of the machine (X motion). The spindles 
are set at a predetermined RPM and the machine feed (X) motion is started; 
each abrasive head is then brought into contact (Z motion) by air pressure 
to the part. In accordance with preferred embodiment, the air pressure is 
controlled during the sanding pass for metal removal rate, the system 
automatically compensating for variances in nominal thickness (.+-.1/2 
inch) while the operator makes adjustment for major deviations.

The sanding machine which is a preferred embodiment of the present 
invention, as shown in structural detail in FIGS. 1-5, 7 and 9 with 
control system therefor shown in FIG. 8, comprises an automatic or manual 
four-axes sanding system for sanding and/or finishing a vertically held 
contoured part. The machine is operational in finishing of parts of 
varying length (four to 110 feet), varying height (one to nine feet), 
varying thickness (0.03 to seven inches), and varying contour (span and 
chordwise up to an eighth inch deviation from centerline). 
The present sanding machine is capable of deburring, radiusing, finishing 
and blending to the required specifications with a discontinuous scratch 
pattern. The machine configuration, in accordance with the hereinafter 
described preferred embodiment, automatically compensates for deviations 
in nominal part thickness and will remove material to a tolerance of 
.+-.0.002 inch over the entire part length. 
Turning to FIG. 8, the machine consists of one or more sanding stations 
enclosed within a dust/sound enclosure, two operator elevators and control 
consoles, and two dust collectors, all mounted on a common trolley 
designed to roll upon a floor-mounted rail system. Each sanding station 
consists of two counter-rotating abrasive wheels mounted on a column. Each 
sanding station operates in three axes: height "Y", radial "C", and toward 
the centertine of the machine "Z", while length "X" is handled by the 
common trolley. 
Each abrasive wheel preferably comprises a series of coated abrasive 
segments mounted on a common hub removable from the spindle by means of a 
threaded nut. Though coated abrasives are preferable, other finish means 
may be utilized. 
FIG. 6 is illustrative of a typical operation sequence of the present 
vertical wing skin sanding system. If should be noted that this operation 
sequence can be operated manually or automatically by means of a device 
such as a numerical control tape or microprocessor. Each station has an 
optical encoder for position on each axis with "X" motion optical encoder 
mounted on the common trolley. The overall system has been set up for 
optical identification of part type and nomenclature with the part set up 
point found by means of a proximity of optical indicators, such as 
manufactured by Sundstrand Inc. or NCR Inc. 
In the manual mode, the two operators position part 14, bring their 
respective guides 4 into contact with the part for vertical positioning 
within the machine. The sanding stations 3-3 and 3-N are then positioned 
for proper height "X" and radial angle "C" and station 3-1 and 3-2 are 
brought within the same plane "Y" and "C". At this point the operators 
must select which operator shall be in master/slave condition. This is 
required to set the proportional angularity control for stations 3-1 and 
3-2, oscillation frequency for all stations, and machine feed "X" rate. 
The proportional angularity control is a variable frequency drive 
controlling the Y motors 19 on stations 3-1 and 3-2 which is, in turn, 
controlled by the "X" motion variable frequency drive motor 7. This 
ensures that sanding stations 3-1 and 3-2 will follow a lower edge 
lengthwise angle of the part 14 if required. 
Both operators then select the proper spindle revolutions per minute (RPM) 
for their respective spindles. The dust collectors 10, sanding station 
spindle motors 26 and oscillation motors 25, and feed motor 7 are then 
turned on. A safety interlock system continuously ensures that a safe 
operation can be carried out. 
As the machine starts its pass along the part 14, the operators bring each 
sanding wheel into contact with the part 14 at a predetermined air 
pressure. This air pressure may be varied by the operators or tape control 
for gross deviations in the part 14 such as openings. Normally, this 
variation is not required as the machine automatically compensates for 
part deviation over nominal thickness. 
At the end of the pass, the operators remove the sanding wheels from the 
part, re-adjust the sanding station for the next pass on the "Y", "Z", and 
"C" axes, re-adjust the feed "X" rate and spindle RPM, if required, and 
start the next pass. This continues until the part 14 is completed. 
It should be noted that as the number of sanding stations 3 in cascade is 
increased, fewer passes over the part 14 would be required. It should also 
be noted that the machine does not necessarily have to move by the part 
but that the part can be moved through the machine with the machine being 
stationary. 
There are three double sets of guide roll stations 4 set up at either end 
and the middle of the machine. The purpose of these guides 4 is to direct 
and support the part 14 into and through the machine. However, they also 
provide for sounding damping of the part 14. They are set at staggered 
heights throughout the machine, but opposite sets are the same height. 
Sheet material parts 14 have a tendency to vibrate in symphony to the 
abrasive wheels with that vibration magnifying in loudness down the length 
of the part. As the guide rolls are made of a flexible material, edge 
patterned cut, and set at staggered heights, that sympathetic vibration is 
dampened. 
FIG. 1 is illustrative of the present vertical sanding system feature of 
travel down the length of the stationary part 14 with a plurality of 
sanding stations 3 mounted on a trolley. For convenience, only four 
sanding stations have been illustrated, but it will be appreciated that 
any number of stations, 1, 2, 3, 4, . . . N may be located in cascade to 
sand a common part on a common pass line. Each illustrated sanding station 
3 is further identified by a number identifying its particular station 1, 
2, 3, . . . N in the cascade system. To keep the part 14 centered within 
the sanding system, there is a plurality of staggered guide roll sets 4. 
Each sanding station is braced by means of weldment 15. Only six sets have 
been illustrated but it will be appreciated that any number 1, 2, 3, . . . 
N may be utilized as the sanding stations 3 are increased. Each guide roll 
set is further identified by a number identifying its particular position 
1, 2, 3, . . . N. 
The sanding stations 3 and guide rolls 4 are enclosed within a sound 
enclosure 2 with the enclosure dust sealed by a series of overlapping (as 
seen in FIG. 5) flexible brushes 18 designed to allow passage of the part 
14 with a minimum amount of air seepage. This dust/sound enclosure 2, 
sanding stations 3, and guide rolls 4 are mounted on a baseplate 42 and 
fastened to trolley 12. 
Behind the dust/sound enclosure on the common trolley 12 are two 
operator-controlled elevators 5 and control consoles 6, operated 
vertically by lift motors 9. Behind the operator control stations are two 
water-based dust collectors 10. These dust collectors 10 are connected to 
the sound/dust enclosure through duct work 11 with the volume of air 
controlled by sliding access windows 44 and inlet 41. At either end of the 
trolley 12 are two safety bumpers 13 designed to prevent the trolley from 
destroying anything in its path. 
The operators observe the sanding operation through two bullet-proof 
windows 43, while variable speed drive motor 7 provides motive power in 
the X motion through gear box 8, chain drive 16 and idlers 25 to the 
driven set of trucks 16 illustrated in detail in FIGS. 2 and 3. 
Only three sets of trucks 16 have been shown in the FIGURES; however, it 
can be understood that as many may be added as required, and they are 
further identified by numbers 1, 2, . . . N. The machine rolls on a set of 
rails 1 down the length of the part 14 with power, control signals, water, 
and air provided through an overhead power track system 17 as e.g. 
manufactured by Gelco Inc. Each sanding station consists of two 
counter-rotating sanding wheels 31, each consisting of abrasive segments 
such as those available from Merit Abrasives Co. (individually marked A-H 
on FIGS. 1, 2, 3, and on the control console 6). These sanding wheels are 
driven through an articulated arm mechanism consisting of sleeves 40, 
double belt drives 30, belt guards 34, pillow blocks 33, and spindles 38 
by electric motor 26. This assembly is mounted onto baseplate 27 and 
suspended on three shafts 29 with guide bushings and counterbalancing 
springs, the counterbalancing springs being required to allow the entire 
baseplate 27 and assembly to oscillate over a variable range and frequency 
independent of the main weldment 28. This variable amplitude and frequency 
oscillation is controlled by the oscillation motor 25 through a right 
angle gear box 39 to a spring loaded eccentric cam as shown in FIG. 7. The 
articulation, or Z motion, is controlled by an air pressure system 32 
individually controlled from the respective control console 6. The air 
pressure system is designed to allow for a deviation in part 14 thickness 
without an associated variation in wheel/part contact pressure. Uniform 
air pressure for the Z motion is provided through the surge resistor tank 
24. The C, or radial, motion is controlled by an electrically operated 
activator. This causes the entire sanding station 3 to vary in 
perpendicularity from the line created by the column 20. The entire 
sanding station 3 is vertically adjustable along the length of column 20 
in the Y motion, driven by the ball screw 21 and motor 19. Dust protection 
for all sliding assemblies is provided by rubber bellows such as 22 and 
24. 
Height, or Y position, is indicated by optical encoders 23, radial, or C, 
position by optical encoders 45, with X position indicated by optical 
encoder 46. 
The guide roll stations 4 are composed of a flexible roll 47, bracket 50, 
and an electrically operated activator 48, all mounted to the weldment 49 
and fastened to the trolley deck 42.