Glass scratch removal apparatus and method

A glass scratch removal apparatus includes a driven rotating tool that is supported on a skirt that can be sealed against a surface to be treated for scratch removal. The skirt is conical and has some flexibility to permit the edge of the skirt in contact with the surface to deform in shape to follow curves or irregularities (such as on a curved windshield of an automobile) and at the same time, the skirt is held in place through the use of a vacuum. The rotating tool is pressed against the surface to lap and polish the surface. The tool is manually actuable toward and away from the surface, and a slurry is fed into the skirt to provide either for "fining" which is an initial step of rough removal of material adjacent the scratch and/or "polishing" which blends in or feathers the surface adjacent the scratch and provides for an optically satisfactory surface. The amount of pressure on the tool can easily be controlled at the same time that the tool is being moved across the scratch, so that the tools can be lowered gradually against the surface to be worked on to avoid gouges or burnished spots or the like.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an apparatus and a method of using the 
apparatus for removing scratches from smooth surfaces such as glass. 
2. Description of the Prior Art 
Grinding and polishing glass has been done utilizing rotary grinders. 
Removing scratches from the surfaces of glass, such as windshields without 
leaving detectable surface dpressions or irregularities in a cost 
effective process has not been accomplished. 
U.S. Pat. No. 3,012,384 shows a device for removing surface imperfections 
from bent glass sheets. This involves the use of a hand-held rotating 
surfacing tool. A hard felt cylinder is used as the polishing tool, and 
held in a chuck while it is rotationally driven. However, the removal of a 
surface imperfection such as a scratch using this process requires a high 
degree of skill, and is a completely manual task. 
While hand drill driven grinder discs also have been tried, they rotate 
slowly, which makes good scratch removal and polishing almost impossible. 
High rotational speeds help in making a satisfactory scratch removal. 
U.S. Pat. No. 3,176,441 shows a device for surfacing glass and, in 
particular, polishing both surfaces of a glass sheet as the sheet moves 
between the two polishing devices. 
A lapping machine is shown in U.S. Pat. No. 2,423,112, for lapping 
surfaces, and it shows an orbiting-type surfacing member that is 
independently rotatably mounted onto a type of a crank which in turn is 
power driven for rotation so that the actual polishing wheel orbits about 
the powered rotational axis. 
Other types of glass grinders have been utilized with a flow of cutting 
fluid. U.S. Pat. No. 2,906,256 shows a cutting tool that has a vacuum 
created on the inside of the tool to draw liquid across the cutting edge. 
The flow keeps the tool and workpiece cool. 
U.S. Pat. No. 4,073,094 shows a glass cutter which is driven from a motor 
having a hollow shaft through which a lubricating fluid is supplied to the 
cutter. In other words, the lubricating fluid is supplied from the 
interior of the shaft to the inside portions of the cutter and then the 
fluid flows out of the cutter. 
U.S. Pat. No. 3,243,922 also shows a grinder with a lubricating or cooling 
flow coming in through the center and out the edges of the grinding wheel. 
Thus, the use of grinding wheels, including orbiting grinding wheels, has 
been advanced, and the flow of fluid from the center of the tool outwardly 
also has been shown. However, the present device includes structure which 
permits use of lapping and polishing tools for rapid, reliable and 
repeatable polishing for removing scratches from surfaces, such as the 
surface of a pane of glass, even when the pane is curved. 
SUMMARY OF THE INVENTION 
The present invention relates to a tool that can be used for removing 
localized scratches in smooth surfaces, including surfaces that are 
curved, such as windshields. The tool comprises a power driven, high speed 
rotating shaft which can drive a selected type of grinding or polishing 
disc, and which is housed inside of a flexible, generally conical skirt. A 
vacuum is supplied to the interior of the skirt to hold the skirt onto the 
surface under vacuum force, and at the same time, provide for a flow of a 
polishing compound slurry across the polishing surface of the member. 
In the form shown, the vacuum that holds the flexible skirt in place also 
causes the flow of the polishing compound-cooling slurry through the 
interior of the skirt. 
In a method of carrying out the process of removing a scratch, first a 
"fining" or lapping operation is done, which is somewhat more abrasive 
than the later polishing operations utilizes an orbiting disc, with a 
suitable slurry in which it operates. A polishing step is then performed 
to provide a fine polish finish and long radius smoothness that is 
desired. 
The present invention involve two separate types of rotating tools, but 
essentially one form of tool holder that uses a different drive shaft for 
each operation mounted in substantially the same type of housing used for 
different rotating tools. If desired, quick change chucks can be used for 
interchanging the tools, but inasmuch as the exact coupling of the 
rotating device to the drive shaft is not critical to performance of the 
invention or the method, the parts shown herein are shown as two separate 
assemblies. 
In the process of removing a scratch from the surface of a windshield or 
other hard surface, such as any type of glass or other type of polished 
surface, it has been found that it is desirable, and in most instances 
necessary, to have two separate operations for satisfactory, repeatable 
results. 
The first process is called a "fining" operation and this, essentially, 
uses a self leveling lapping disc (made of metal) which works a lapping 
compound in a slurry against the surface and has the capability of 
removing very small particles of material such as glass in a relatively 
short time. A high rpm drive operates the fining or lapping tool in a 
slurry that is passed through a housing or shroud that properly orients 
the tool and its drive assembly relative to the surface that is being 
worked on. 
The second process is a polishing operation and utilizes the same tool 
assembly driving a felt pad that is rotated in a polishing slurry for 
providing a very smooth, gently concave surface, in a final step of the 
scratch removal. 
In both operations, the same support and drive motor is utilized, and the 
unit is held onto the surface through the use of vacuum from a source that 
also transfers the slurry used through the shroud or support. The unit is 
capable of being moved along the surface as it rotates without breaking 
the vacuum seal and the engagement of the rotating tools with the surface 
being worked on is controlled manually so that the tool can be gradually 
lowered down to the surface as the tool is moving laterally to insure a 
smooth transition from the unworked surface to the polished surface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1, the tool arranged for the fining step is illustrated. The 
illustration is part schematic, and it is to be understood that the 
support housing and the tube supporting the drive shaft for the tool, as 
well as the drive motor arrangement, is the same for the tools used in 
both operations. 
A scratch removal apparatus indicated generally at 10 is supported on the 
surface of a pane of glass 11 that has a scratch that is to be removed. 
As shown, apparatus 10 includes a support housing or shroud 12 that is made 
of a semiflexible plastic, such as ABS plastic, and that is generally 
conically shaped. The housing has a lower edge indicated at 13 defining a 
line that is nominally a plane that lies along the planar surface of the 
glass pane 11 to be repaired. The cone-shape may deform so the line on 
edge 13 will define shapes other than circular so the line of edge 13 will 
seal on a curved surface. 
The upper end or first end of the generally conical housing or shroud 12 is 
connected to a suitable collar 14 that in turn is fixed to a housing tube 
15 at a desired level. The housing tube 15 supports a drive shaft for 
driving a hub 16 for an orbiting type lapping tool 17. The lapping tool is 
shown in greater detail in FIG. 3. As can be seen in FIG. 3, the outer 
housing tube 15 has a bearing 21 at the lower end thereof that rotatably 
mounts a tubular sleeve 22 which is drivably coupled to a pulley 25 at the 
upper end 22A thereof (FIG. 1), and as will be shown in connection with 
FIG. 4, the pulley 25 rotationally drives sleeve 22 through a suitable 
connector such as a spline or pin. An axially movable spider or hub 26 is 
driven by the pulley 25, as will be explained. The hub 26 is movable along 
the vertical or central axis and drives a central drive shaft 28, 
extending out the bottom of the sleeve 22. The drive shaft 28 may be slid 
axially on the inside of sleeve 22 with spider 26 but rotates at the same 
speed as the sleeve. 
A suitable bellows seal 30 can be provided between the rotating sleeve 22 
and shaft 28 and the hub 16. The hub 16 is drivably coupled to the shaft 
28 in a suitable manner. The hub 16 has a disc 32 drivably mounted thereon 
to form part of the fining tool 17. As shown in FIG. 3, a stub shaft 34 
extends perpendicular to the disc and is offset from the axis 36 of the 
sleeve 22 and shaft 28, and is used for rotatably mounting a pad support 
38, that has a fining or lapping pad 40 of zinc or the like held on a 
compressible foam layer 39 which is fixed to the undersurface of pad 
support 38. The pad support 38 includes a bearing 42 that rotatably mounts 
the pad support 38 onto the shaft 34. In addition, a sealing boot 42A is 
provided to shield the bearing 42 from the slurry. The bearing 42 is made 
to provide some tilting of the pad for self-leveling. 
The sleeve 22 and the shaft 28 rotate together, and are drivably coupled as 
will be shown in FIG. 4, but the shaft 28 can slide axially, along the 
axis 36, relative to the sleeve 22. Suitable bushings one of which is 
shown at 44 in FIG. 3 are provided at spaced locations between the 
interior wall of sleeve 22 and the shaft 28 to permit this axial sliding 
movement. 
Tubular housing 15 has an additional bearing 21 at the upper end to support 
the sleeve 22. The central axis of housing 15 is supported on the central 
axis of shroud or housing 12. 
A motor support plate 52 is mounted to the upper end of the housing 15, and 
a motor (110 volt) indicated at 53 is mounted to the support plate spaced 
laterally of the tube 15. A pulley 54 is coupled to the output shaft of 
the motor 53, and a belt 55 drives the pulley 25. 
The movement of the central shaft 2S along axis 36 is controlled by a 
manual handle or lever 56, that is supported on a pivot pin 57 relative to 
a bracket 58, attached to the plate 52. The handle 56 has an actuator arm 
section 60 that is connected with pivot pins 61 to a bearing carrier 62. 
The carrier 62 comprises two bearing holder clips (FIG. 5) which hold the 
outer race of a bearing 63 therein. The bearing 63 is a standard bearing 
which has an inner race supporting the interior shaft 28. The bearing 63 
is prevented from axial movement with a suitable snap ring at the top and 
the hub or spider 26 so that when the handle 56 is pivoted, the actuator 
arm section 60 will cause the interior shaft (28 in FIG. 1) to be moved 
axially under control of the handle. 
The handle 56 is urged in a direction about the pivot pin 57 so as to cause 
the arm section 60 to move toward the tube 15, that is, to urge the shaft 
and tool downwardly, through the use of a compression spring assembly 65. 
The spring assembly 65 includes a spring 64 that abuts against one portion 
of the bracket 58, and is guided with an adjustment rod 66 that extends 
through a suitable reaction bracket shown in dotted lines at 67 in FIG. 1. 
The bracket reacts force from the spring 64 to tend to pivot the lever arm 
60 downwardly about the pivot pin 57. Thus, spring 64 will provide a 
spring load against the fining tool of FIG. 1 to urge it against the 
surface of the glass or pane 11 that is being worked on. The tool is urged 
toward the plane 13 defined by the lower edge of the shroud or housing 12. 
In order to carry out the fining operation, it is desirable to have a 
slurry including abrasive or rubbing compound particles in the slurry in 
which the tool can work. In order to accomplish this, a seal member 
indicated at 70 is provided just inside the skirt or shroud 12 adjacent 
the plane 13, and extending slightly beyond the edge 13 in direction 
opposite from the upper end 14. The sleeve 14 is tightly fitted onto the 
housing 15, so that it will support the housing as previously stated, and 
the seal 70 then seals against the surface indicated at 71 that is being 
worked on, when there is a force holding the seal against the surface. 
The housing or shroud 12 is held on the surface 71 under a vacuum on the 
interior thereof, above the level of the slurry on the interior of the 
shroud. The slurry is indicated generally at 73. The pane 11 being worked 
on is an inclined windshield of an automobile, so that the level of the 
slurry is tilted relative to the axis 36 of the drive shaft and shroud. 
As shown, a fitting 74 is provided adjacent the lower end of the shroud or 
skirt 12, and is selected to be on a side thereof which would normally be 
on the low side of the skirt or shroud when the tool is in use. This 
fitting 74 is connected so that it has an interior passageway open to the 
interior of the shroud. A tube 75 is coupled to the fitting 74, and in the 
form shown, the tube 75 is connected to the low pressure section of a 
venturi assembly 76 that is located inside a suitable container 77, well 
below the level of the slurry supply liquid indicated at 78 in the 
container. The venturi 76 is known and provides a low pressure section in 
the center between converging and diverging portions, and a low power 
consumption pump indicated at 8O is provided inside the container 77 to 
pump liquid oomprising the slurry 78 out through a pump outlet tube 82, 
through the venturi 76, and then the liquid is discharged through a nozzle 
forming part of outlet tube 82 back into the container 77 below the level 
of the slurry liquid 78. 
The vacuum created at the venturi 76 will act through tube 75 and chamber 
72 to create a vacuum in a tube 94 to draw the slurry up into chamber 72. 
A quantity of slurry will accumulate in the chamber 72, depending on the 
lift, and the sizes of the inlet and outlet tubes. The slurry 73 in the 
chamber formed by the shroud will be drawn through the tube 75 into the 
venturi 76 and then discharged (along with the pump discharge) back out 
into the container 77. The amount of vacuum being drawn can be regulated 
by adjusting a vacuum regulator valve 84 that has an air inlet pipe 85, 
and a control handle 86. Controlling the vacuum level adjusts the rate of 
flow of the slurry. The level of the vacuum also adjusts the force holding 
the skirt onto the glass surface. 
A vacuum gauge 90 can be coupled into a fitting in a conduit 91 that leads 
from the valve 84 to a Y connector 92 connecting two portions of the tube 
75. By opening and closing the valve member 84, the amount of air being 
bled in through inlet 85 can be regulated and this will control the level 
of vacuum that is created with the venturi 76. 
Because the seal 70 seals the interior chamber indicated at 72 inside the 
shroud 12, the vacuum is created in the shroud as the slurry 73 is pulled 
through the fitting 74 and tube 75. This partial vacuum is used for 
maintaining a supply of the slurry in the interior of the shroud 12 to 
keep the tool 17 working the slurry for abrading and also for cooling the 
windshield and tool. 
The tube 94 is connected through a fitting 95 to a side of the shroud 12 
opposite from the fitting 74 in an area which is not covered with the 
slurry 73. The free end of the suction tube 94 extends into the container 
77, and has a weight 96 on the bottom end thereof to maintain it near the 
bottom of the container. 
It should be noted that the outlet tube 82 from the pump 80 expels liquid 
under pressure, and this tends to agitate the slurry and maintain the 
solids in the slurry forming the polishing compound in suspension in the 
slurry. Thus, the pump serves not only as a low power consumption source 
of vacuum for moving the slurry through the interior chamber 72 of the 
shroud, but also for agitating the slurry in the container 77. 
The partial vacuum inside the chamber 72 also tends to hold the shroud 12 
and the housing 15, motor 53, and other accessories, against the surface 
11. The amount of force or pressure holding the shroud in place is 
counteracted by the spring force from the spring 65 tending to push the 
shroud up as the tool pushes against the surface 71. The support forces 
for the tool are thus localized to the area under the shroud and are not 
reacted back to the frame that holds the windshield or glass pane. 
The entire tool can be moved as indicated by the arrow 98, along the 
surface, at the same time that the orbiting fining tool 17 is working 
against the surface, utilizing the slurry to lap away a very fine layer of 
the glass or other material. 
The manual lever 56 permits lifting the fining tool away from the surface, 
generally as shown by the dotted lines in FIG. 3, and at the same time, 
provide agitation. 
A problem which is faced with portable electrically powered tools, such as 
the apparatus disclosed, is that they will be used where an extension cord 
is necessary, as for example, repairing the scratch on a windshield of an 
automobile, and the use of a small pump such as pump 8O, which also acts 
as a vacuum pump insures that there will be adequate power, approximately 
12 amps, for running the drive motor 52 for the lapping or polishing tool. 
Powering a separate vacuum pump source and a separate pump for the slurry, 
as well as powering the main motor pump with only one extension cord and 
from one 15 amp circuit is a problem, so the two functions of vacuum and 
slurry supply pump combined into one provide a benefit from a powering 
standpoint. The agitation achieved by pumping the material through the 
venturi back into the tank through the outlet 82 insures that the 
polishing particles are distributed in a liquid carrier. 
The surface of a glass pane 11 may have a localized scratch that may be as 
much as 0.001 inch deep, and about a two inch wide band along the scratch 
is lapped or "fined" and then later polished. Optically correct feathering 
of the surface from the scratch is important, and, of course, doing it 
economically is also important. 
As the tool 17 is lowered into contact with surface 71 and also as it is 
removed from contact with the surface by operating handle 56, the shroud 
12 and tool will be slid laterally along the surface. The tool will not be 
started while it is in contact with the surface. This is important in the 
initial startup so there isn't any burnished spot or circular ground spot 
that would be left as could happen if the tool is left stationary when the 
motor 53 is started. The work does have to be visually inspected, so the 
tool can be lifted and the shroud moved to expose the scratch area without 
breaking the vacuum seal at the edge of the shroud which contacts and 
seals on the surface of pane 11. 
The motor 53 is a very high speed motor and the tool may be rotating in the 
range of 6000 to 7000 rpm. 
In the first stage of operation, the lapping or "fining" tool is operated 
to lap a band with feathered edges along the sides of the scratch down to 
almost the level of the bottom of the scratch. 
In FIG. 2, and also in FIG. 4, the apparatus for the polishing operation 
subsequent to the lapping or fining operation is illustrated. 
In this form, different numbers will be used for the center drive shaft, 
but the drive motor 53, and the supports and the like, are all shown with 
the same numbers. However, there is a different connection of tubes for 
feeding in the slurry that is used for the polishing operation. The 
container 77 for the slurry is the same, as well as the adjustment valve 
for regulating the vacuum. 
In this form of the invention, the polishing tool shown at 112 has the 
outer tube 15 mounted onto a skirt or shroud 113, which has a seal 114 
around the perimeter thereof, and the lower edge of which defines a plane 
115. The motor 53 in this form of the invention drives the pulley 54 and 
belt 55, to drive the main drive pulley 25 which is drivably mounted on 
the upper tube section 22A and thus drives the tube 22, as shown in more 
detail in FIG. 4. 
As shown in detail in FIG. 4, the drive spider 26 has drive pins 120 fixed 
thereto which slide in suitable bushings 121 in a web 122 forming part of 
the pulley 25. This permits the drive spider 26 and the pins 120 to slide 
axially along the axis shown at 123 for the interior drive tube shown at 
125 which forms a drive shaft for the polishing tool (and corresponds to 
shaft 28) as will be explained. The drive spider 26 is pinned with a 
suitable pin 126 to the tubular shaft 125 so that there is a drivable 
connection. A similar pin can be used for driving the shaft 28 for the 
fining tool. 
The arm section 60 of handle 56, as shown in FIG. 4, is connected through 
the bearing carrier 62 to the bearing 63 which permits rotation of the 
shaft 25 relative to the outer race and the carrier 62 so the axial 
movement of the tubular shaft 125 can be controlled. 
As shown, the handle 56 is mounted onto the support 58, which has the 
upright extending arm 58A for the mounting of pin 57, and also shown in 
greater detail is the spring assembly, held on a lower portion 58B of the 
bracket 58. 
Further, the motor support member 52, as shown in FIG. 2, has an upstanding 
rim for reinforcement, so it can support the motor 53 adequately. 
The interior tubular shaft 125 is suitably mounted in low friction bearings 
135 in the outer tube 22, as previously explained, and the upper bearing 
21 inside the tube 15 is also shown in FIG. 4. The shaft 28 used with the 
fining tool is mounted in the same manner as tubular shaft 125. 
The bushings 135 can be low friction material such as Teflon, and while 
they do not support the tubular shaft 125 for rotation, they permit linear 
sliding movement along the axis 123. 
In this form of the invention, the tubular shaft 125 extends down and 
supports a polishing tool 140. The polishing tool 140 has a hub 141, and 
as shown, the tube 22 has a seal 142 at its lower end to seal off against 
liquid flow toward the bearings. A suitable boot 143 is provided over the 
lower end of the rotating tube 22 and down to the hub 141. The polishing 
tool 140 as shown comprises a cup that is drivably mounted onto the 
tubular shaft 125, and supports a felt pad 144 on its interior surface. 
The felt pad as shown in FIG. 4 is raised from the surface 71 of the pane 
11 that is being finished, and the underside plane 145 of the felt pad 144 
is the surface that will engage the surface 71 when the handle 56 is 
released so that the spring 65 can move the handle to lower the shaft 125. 
In this form of the invention, the seal 114 on shroud 113 rides along the 
pane 11, against the surface 71, and forms a fluid seal as before. A 
discharge fitting 74, as in the first form of the invention is provided in 
the skirt or shroud 113, and this connects to tube 75, and through a 
venturi 76 on the interior of a tank 77 (see FIG. 2). The pump 80 is 
operable to create a vacuum on the interior of the shroud 113. The slurry, 
however, indicated at 150 would be for polishing, and would be of a 
different consistency having different polishing particles than the fining 
slurry. 
The slurry intake tube 94 for the polishing tool is connected through a 
rotating fitting 151 coupled to the upper end of the tubular shaft 125, 
and the liquid that is sucked in through the suction tube 94 passes 
through the interior passageway shown at 125A in FIG. 4 into the interior 
chamber 153 of the felt pad, and then out into a reservoir portion 155 
formed on the interior of the shroud which holds the polishing slurry. 
Fitting 151 can be any type of suitable swivel having bearings that are 
capable of taking the rotational speeds of the tubular shaft 125. 
A modified seal and sliding support is shown in FIG. 3. The shroud 160 is 
cone shaped as before and a flange 161 is provided on the interior of the 
remote end of the shroud. Flange 161 forms a receptacle 164 which supports 
a foam seal 162 for engaging surface 71. The receptacle 164 has a height 
greater than the height of the seal, so the seal 162 will float or slide 
slightly in the receptacle. This insures sealing along contours of the 
glass surface as well as accommodating slight irrregularties. A plurality 
of glide clips or sliding feet 163 are fastened at spaced locations around 
the shroud to provide nonlapping support points or feet. The feet are 
preferably very high molecular weight nylon which is low friction to lower 
the forces needed for sliding the tool. Also, the material does not tend 
to lap in the presence of an abrasive slurry. The support clips are 
replaceable if they wear. 
The seal 162 has a shape to insure a seal is made against the surface being 
processed along an annular line defining the interior chamber. 
The seal 162 will be compressed when the glides or feet rest on the 
surface, but not excessively compressed. The compression will be 
sufficient to maintain the vacuum seal necessary for providing the 
retaining force and the transfer of the slurry. 
The slurry for the polishing operation feeds into the center of the 
polishing pad 140 and out past the outer edges as the pad rotates, to keep 
the glass cool and provide polishing compound for an adequate polishing 
job as the unit is slid back and forth across the path of the scratch in 
uniform strokes to provide a optically acceptable, well-feathered, 
depression that removes the scratch from the surface. 
The shroud, again, is of great importance in that the flexibility of the 
skirt member, with its relatively large diameter, where it contacts the 
surface and permits the seal along a curved surface by bulging or 
deforming in desired locations. 
By controlling the pressure of the fining and polishing pads both, as the 
tools are moved across the surface, tapering is easily achieved. 
Even though the shroud is capable of conforming along its lower edges to 
curves and the like, it has rigidity, so that the axis of the cone, which 
is also the axis of rotation of the tool drive shaft, remains 
substantially normal to the center of the shroud. The tool axis does not 
tend to tilt, which would cause an edge of the polishing tool to be 
overloaded. The seal on the shroud must be flexible enough to accommodate 
the curve of the windshield without losing the vacuum in the shroud. The 
forces on the tools substract from the vacuum forces and can be 
controlled. The fining tool is loaded with about 10 pounds force and the 
polishing tool has about 40 pounds force on it. 
The handle 56 is used to lift the polishing pad and lower it gradually as 
the shroud is moved laterally to taper the edges of the polished region. 
The switch for the motor is placed adjacent the handle 56 so it can be 
operated easily. 
Although the present invention has been described with reference to 
preferred embodiments, workers skilled in the art will recognize that 
changes may be made in form and detail without departing from the spirit 
and scope of the invention.