Method and apparatus for surface treating a workpiece

A method for surface treating a continuous flow of workpieces includes the steps of fluidizing a stationary bed of surface treating media, aggitating the fluidized bed of surface treating to create a scrubbing action to the surface treating media, suspending the workpieces from an overhead conveyor located over the bed of surface treating media and moving the workpieces to be treated suspended from the overhead conveyor through the stationary, fluidized aggitated media bed subjecting the workpieces to the scrubbing action of the media. Further, an apparatus for surface treating workpieces which includes a reservoir for containing a bed or pool of surface treating media, a force vibration generating device for imparting a reciprocating force to the reservoir and therefore, the surface treating media contained in the reservoir, the reciprocating force having at least a vertical vector and an overhead conveyor means located over the reservoir for conveying the workpieces to be treated continuously through the reservoir and, therefore, through the media.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a method and apparatus for surface 
treating the surfaces of a workpiece, more particularly, to a method and 
apparatus wherein the workpieces to be surface treated are continuously 
moved through a bed of aggitated surface treating media. 
2. Discussion of the Prior Art 
Various processes and apparatus are known to the art for surface treating 
workpieces. Examples are shown in the following U.S. Patents. 
U.S. Pat. No. 2,815,609 issued on Dec. 20, 1957 shows an apparatus for 
deburring and polishing workpieces including a pan which holds deburring 
material such as steel balls o stones. The pan is mounted in a stationary 
frame for vertical reciprocating movement by means of sprockets and chains 
supported on the frame. The apparatus includes a shaft which is mounted to 
the frame over the pan and is moved in a reciprocating motion along its 
longitudinal axis by means of an eccentric. The workpiece to be deburred 
is clamped to the reciprocating shaft to depend therefrom, and the pan is 
raised so that the workpiece is submerged in the deburring material. The 
shaft is then reciprocated to move the workpiece back and forth through 
the deburring material. After a sufficient time, the pan is lowered and 
the workpiece is removed from the deburring material, and the deburred 
workpiece is removed from the shaft. 
U.S. Pat. No. 2,918,926 issued on Dec. 29, 1959 shows a washing and 
degreasing apparatus which includes a large tank for holding a suitable 
liquid cleaning solution. A parts basket having perforated walls is 
suspended into the liquid solution in the tank. The parts basket has one 
open end, and is mounted on springs for vibrator and oscillatory motion. A 
vibration generating device which includes an electric motor is connected 
to the parts basket by means of a belt to impart a vibratory motion to the 
basket. In addition, a sloped endless conveyor is located within the tank 
so that a portion of the conveyor lies below the open end of the parts 
basket to receive the parts from the basket and convey the parts out of 
the tank. Parts to be cleaned are deposited in the basket near the end 
thereof opposite the open basket end so that they are immersed in the 
cleaning solution. The basket is then caused to vibrate so that the parts 
therein will be moved toward the open basket end and be discharged onto 
the endless conveyor for removal from the tank. 
U.S. Pat. No. 3,045,397 issued on July 24, 1962 shows an apparatus for 
surface treating parts which includes a support frame mounted on springs 
and an electric motor connected to the support frame through a belt system 
for imparting a vibratory action to the support frame. The apparatus 
further includes a plurality of parts receiving vats rigidly mounted to 
the support frame. The parts to be treated as well as liquid treating 
agent are place in the vats, and the frame is vibrated. 
U.S. Pat. No. 3,128,577 issued on Apr. 14, 1964 shows an apparatus for 
deburring articles of considerable length which includes a tank containing 
abrasive material. Vibrator devices are attached to the outer side of the 
floor of the tank to vibrate the abrasive material in the tank. The 
opposite end walls of the tank have aligned apertures for accommodating 
the longitudinal movement of an elongated article to be deburred through 
the tank. The apertures have seals to prevent abrasive material from 
leaking out of the tank. Powered, article feed rollers are located outside 
the tank at one end wall. The elongated article to be deburred is inserted 
longitudinally through the apertures in the tank end walls and is engaged 
by the feed rollers. The feed rollers move the elongated article through 
the tank wherein it is subjected to the vibrating abrasive material and is 
deburred thereby. 
U.S. Pat. No. 3,148,483 issued on Sept. 15, 1964 shows a machine for the 
surface treatment of an article by the reaction of media in vibratory 
movement which includes a rigid base with a horizontal table resiliently 
supported on the base by coil springs and a trough containing particulate 
treating material is secured to the table. Vibratory movement is imparted 
to the table, and therefore to the trough, by means of an eccentric drive 
arrangement located in the base below the table. The elongated trough has 
an upstream end wall, spaced apart side walls, a concave floor, and is 
open at the downstream end. A perforated platform is located at the open 
downstream or outlet end of the trough to separate particulate media 
exiting the trough from the treated articles also exiting the trough. The 
separated media is returned to the upstream end of the trough through an 
inlet chute for reuse in the treatment of further articles placed in the 
trough. 
U.S. Pat. No. 3,336,701 issued on Aug. 22, 1967 shows a elongated, 
downwardly inclined container box containing an abrasive particulate 
material. The elongated, sloped container box is suspended on air cushions 
on fixed legs. Vibration is imparted to the container box by means of 
driven shafts and eccentric weights located beneath the container box. 
Articles to be finished are loaded into the container box by a chute 
located at the elevated container end. The lower end of the container box 
includes a lip over which finished articles and particulate treating 
material overflow from the container box. A screen arrangement is 
positioned beneath the container lip outside the container box for 
separating finished articles from the abrasive particulate material. The 
particulate material passes through the screen onto a recycling conveyor 
which returns particulate material back to the container box for reuse. 
U.S. Pat. No. 4,258,505 issued on May 31, 1981 shows another apparatus for 
cleaning a workpiece with abrasive particulate material which includes a 
closed vessel. A grate is located within the vessel above the vessel 
floor. A bed of abrasive material is located above and supported on the 
grate, and the volume beneath the grate forms a plenum chamber. Compressed 
air is introduced into the plenum chamber and passes upwardly through the 
grate to maintain the abrasive material in a fluid and agitated state. The 
two end walls of the vessel are formed with openings through which a 
continuous elongated workpiece is moved through the bed of abrasive 
material. In addition, air conduits are located through the bed of 
abrasive material next to the path of the elongated workpiece passing 
through the abrasive material bed. These air conduits have nozzles 
oriented to direct compressed air streams against the surface of the 
workpiece moving through the abrasive material bed. The air issuing from 
these nozzles pick up particles from the fluidized bed and propels the 
abrasive particles at high velocity against the surface of the workpiece. 
A mixture of air and abrasive material rising from the abrasive bed is 
removed from the vessel through an exhaust duct to a separator device. The 
separator device separates particulate material from the air. The 
separated particulate material is returned to the vessel for reuse, and 
the separated air is exhausted to the atmosphere. 
U.S. Pat. No. 4,586,293 issued on May 6, 1986 shows a vibratory surface 
treating apparatus and method wherein a reservoir containing a bed of 
surface treating media is vibrated to fluidize and agitate the bed of 
surface treating media and workpieces to be surface treated are caused to 
move through the bed of surface treating media under the influence of the 
vibrations imparted to the reservoir. In another embodiment, this patent 
shows an endless belt conveyor system submerged within the bed of surface 
treating media for moving the workpieces through the media bed. 
U.S. Pat. No. 4,662,425 issued on May 5, 1987 shows a batch type vibratory 
scrubbing apparatus which includes a container filled with particulate 
scrubbing media and vibratory generators for vibrating the container and 
scrubbing media. A part or casting structure is suspended by a chain above 
the container, and a part or casting is fastened to the bottom end of the 
support structure. Additional vibration generators are connected to the 
support structure. In operation, the support structure with the part or 
casting attached is lowered to locate the part or casting into the 
vibratory particulate media. The support structure is then raised to 
remove the part or casting from the particulate media. 
SUMMARY OF THE INVENTION 
The present invention provides a method and an apparatus for the continuous 
surface treating of workpieces. 
The present invention further provides a method and apparatus for the 
continuous surface treating of workpieces which can be intermixed of 
workpieces of various different sizes and shapes without any modification 
to the method or apparatus. 
The present invention further provides a method and apparatus of the class 
described wherein the exterior surface and any open internal voids of the 
workpiece are concurrently surface treated. 
More particularly, the present invention in one embodiment provides a 
method of surface treating workpieces comprising the steps of vibrating a 
bed of a surface treating media sufficiently for fluidizing the bed of 
surface treating media, suspending workpieces from above the fluidized bed 
of surface treating media such that the workpieces are submerged in the 
fluidized bed of surface treating media, and continuously conveying the 
workpieces through the fluidized bed of surface treating media. 
The present invention further provides an apparatus for surface treating 
workpieces, comprising means defining a reservoir for containing a bed of 
surface treating media, vibrating means for imparting a vibratory force to 
the reservoir defining means for fluidizing the bed of surface treating 
media in the reservoir, conveyor means located above the reservoir, and 
means for suspending the workpieces from the conveyor means such that the 
workpieces are submerged in the bed of surface treating media in the 
reservoir means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
With reference to FIGS. 1 and 2, there is shown an apparatus of the present 
invention, generally denoted as the numeral 10, for surface treating 
workpieces 12. The workpieces to be surface treated can be virtually any 
article of manufacture. Examples of the types of surface treatment for 
which the apparatus 10 can be used include, but are not limited to, 
deburring, polishing, burnishing and cleaning of the workpieces. 
The apparatus 10 includes an elongated housing, generally denoted as the 
numeral 14, which comprises a floor 16, two spaced apart generally 
parallel side walls 18 and 20, and two spaced apart generally parallel end 
walls 22 and 24. The floor 16, side walls 18, and 20, and parallel end 
walls 22 and 24 cooperate to define a workpiece treating media reservoir 
26. 
The end wall 22 constitutes the workpiece entrance end of the reservoir 26 
and the other end wall 24 constitutes the workpiece exit end of the 
reservoir 26. The reservoir 26 is filled with a bed of appropriate 
workpiece surface treating media 28. It is presently contemplated that the 
surface treating media 28 will be particulate material, or particulate 
material and liquid. The exact nature of the surface treating media will, 
of course, depend upon the type of surface treatment to be carried out, 
and upon the material of the workpieces 12. By way of example, the 
particulate material could be sand, stone, steel shot, and the liquid 
could be an oil or a solvent such as water. 
The apparatus 10 further includes vibrating means, generally denoted as the 
numeral 30, for causing the housing 14, and therefore the bed of surface 
treating media 28, to vibrate. The vibratory forces created by the 
vibratory means 30 have an amplitude and frequency sufficient to overcome 
the settling velocity of the media 28 due to gravity so that the media 28 
is fluidized, that is so that the media 28 has a low resistance to flow. 
The vibrating means 30 can be virtually any known or otherwise convenient 
device such as, for example, an eccentric drive arrangement, or rotating 
unbalanced mass device. Even further, the vibrating means 30 can be of the 
variable frequency type which provides for selectively varying the 
frequency of the force generated thereby from a minimum to a maximum so 
that the frequency of the generated forces can be changed as the type of 
surface treating media, workpiece material, or surface treating parameters 
may change. In addition, the vibrating means 30 can impart only a vertical 
force vector to the housing 14, or impart both a vertical force vector 
component and a horizontal force vector component to the housing 14. 
The housing 14 is preferably mounted on vibration isolation means 32 to 
isolate the vibrating housing 14 from its environment. Various isolation 
means are well known and include, but are not limited to gas filled bags, 
liquid filled devices, resilient pads and leaf springs. As shown in FIG. 
1, the housing 14 is isolated from the floor 34 of a facility in which it 
is placed by isolation means in the form of coil springs. 
The apparatus 10 further includes a powered overhead workpiece moving or 
conveying means, generally denoted as the numeral 36, located over the 
housing 14 extending along the longitudinal axis of the housing 14. The 
conveyor means 36 descends at the entrance end 22 of the housing 14 to a 
lower elevation above the bed of surface treating media 28, transverses 
the housing 14 at this lower elevation, and ascends at the exit end 24 of 
the housing 14. Workpiece suspension means, generally denoted as the 
numeral 38 depend from the overhead workpiece conveying means 36 at spaced 
apart intervals therealong and are affixed thereto for movement with the 
conveying means 36. Workpiece supporting means, generally denoted as the 
numeral 40, is located at the distal end of the workpiece suspension means 
38 for affixing the workpieces to be treated to the suspension means 38 
and, therefore, to the conveying means 36 so that the workpiece 12 moves 
with the conveying means 36. The suspension means 38 is of a sufficient 
depending length so that the workpiece 12 attached at its distal end will 
be above the elevation of the housing 14 as the conveying means 36 carries 
the workpieces 12 to and from the housing 14 but will be submerged in the 
bed of surface treating media 28 in the reservoir 26 as the conveying 
means 36 transverses the housing 14. As shown, the conveying means 36 is a 
continuous monorail conveyor of the carousel type so that suspension means 
38 are continuously moving through the reservoir 26. Also as shown, the 
suspension means 38 are rigid members, for example, steel I-beams or the 
like. The design of the supporting means 40 will depend upon the physical 
configuration and material properties of the workpiece 12, but is 
illustrated as a clamp arrangement gripping opposite lateral sides of the 
workpieces 12. 
In operation, at a workstation (not shown) upstream of the housing 14 
workpieces 12 to be surface treated are positioned in the workpiece 
supporting means 40 so that the overhead conveying means 36 moves a 
continuous supply of workpieces to the housing 14. As the conveying means 
36 descends, the workpieces 12 suspended therefrom submerge into the bed 
of fluidized surface treating media 28 in the reservoir 26 of the housing 
14, and are moved through the bed of surface treating media 28 in the 
longitudinal direction of the housing 14. Because the workpieces 12 are 
held in the rigid workpiece suspension means 38 there is a relative motion 
between the fluidized and vibrating surface treating media and the 
workpiece 12 resulting in a scrubbing action of the surface treating media 
on the workpieces 12. 
Now with reference to FIGS. 3 and 4, there is shown another embodiment of 
an apparatus of the present invention, generally denoted as the numeral 
110, for surface treating workpieces 12. The apparatus 110 is identical in 
most respects to the apparatus 10 of FIGS. 1 and 2, and the common 
features are denoted by identical numerals. Therefore, for the sake of 
brevity and clearness of understanding, the description of these common 
features will not be repeated. 
The difference between the apparatus 10 and the apparatus 110 resides in 
the workpiece suspension means which is denoted generally as the numeral 
138 in FIGS. 3 and 4 to differentiate it from the suspension means 38 of 
the apparatus 10 in FIGS. 1 and 2. 
The suspension means 138 is not rigid as is the suspension means 38, but 
includes a tension isolation device 142. The tension isolution device 142 
can be positioned at various locations above the workpiece supporting 
means 40. For example, the isolution device 142 could be located between 
the distal end of the suspension means and the workpiece supporting means 
40 or between the proximal end of the suspension means 38 and the 
conveying means 36. However, as shown, the suspension means 36 is divided 
into two components 36A and 367B and the isolation device 142 is located 
between and interconnecting these two suspension means components 36A and 
36B. The isolation means 142 are resilient members such as, for example, 
elastomeric bodies, pneumatic bodies, and the like. As shown, the 
isolation device 142 includes a tension spring such as coil spring. The 
isolation device 142 is selected to either cause the suspended workpiece 
12 to vibrate out of phase with the vibrating surface treating media 28, 
or alternatively, to vibrate in phase with the vibrating surface treating 
media 28 at the same frequency, but at a greater amplitude. In either of 
these operating modes, there is produced a relative motion between the 
workpiece 12 and the vibrating surface treeating media 28 which provides a 
scrubbing action of the surface treating media on the workpieces. The 
isolation device 142 can be selected so that the resonent frequency of the 
combined mass of the suspension means 38 and supporting means 40 and 
workpiece 12 closely matches the frequency of the vibrating means 30 used 
to vibrate the housing 14 and bed of surface treating media. 
In operation of the apparatus 110, when the workpieces 12 are suspended by 
the workpiece suspension means 138 in the bed of surface treating media 28 
the vibrating surface treating media 28 excites a sympathic vibration in 
the isolatiion device 142 which causes the workpiece 12 to vibrate as 
described above relative to the vibrating bed of surface treating media 28 
creating a scrubbing action of the surface treating media 28 on the 
workpiece 12. 
The foregoing detailed description is given primarily for clearness of 
understanding and no unnecessary limitations are to be understood 
therefrom for modifications will become obvious to those skilled in the 
art upon reading this disclosure and may be made without departing from 
the spirit of the invention or scope of the appended claims.