Automatic coating and spin drying apparatus

Automatic coating and drying apparatus wherein a stream of parts or elements is directed from above into an upright perforated basket spinning at low speed, and are simultaneously sprayed with a coating solution. When the basket is full, the loading and spraying cycles are terminated, and the basket is spun at high speed to throw excess solution off of the parts. The basket may be rotated to a position opening downwardly such that the parts spill therefrom into a suitable bin, after which the basket may be returned to the upright position so that the entire cycle may be repeated.

The present invention relates to spin drying apparatus and, more 
specifically, to automatic apparatus for both coating and spin drying a 
plurality of individual parts or elements. 
In prior art apparatus and techniques for coating and drying a plurality of 
individual elements such as machine parts, a number of steps are involved, 
such as loading the parts into a perforated basket and shaking the basket 
to distribute the load, dipping the loaded basket into a tank of coating 
solution to wet the parts, placing the dipped basket into a spinning 
apparatus to dry the parts, and emptying the basket after the parts have 
been spun dry. Most or all of these steps require manual intervention and 
the use of a chain hoist or the like. It is a general object of the 
present invention to provide an apparatus which automatically performs 
most or, preferably, all of the foregoing functions without manual 
intervention.

Referring to the drawings, a presently preferred embodiment 10 of the 
invention comprises a generally cylindrical basket 24 having an open top 
23, and side and bottom walls 25, 27 of perforated sheet metal or suitable 
screen material. Basket 24 has a shaft 26 extending coaxially therethrough 
and rigidly coupled to basket bottom wall 27. A lower end of shaft 26 
extends from basket bottom 27 through a bearing block 22 of Teflon or 
other suitable material which supports basket 24 in the upright basket 
position illustrated in FIGS. 1 and 3. Block 22 is located on a support 
plate 18 within an enclosure defined laterally by sections 20 of angle 
iron or the like welded or fastened to the support plate. 
An open hollow tank 12 has side walls 13 which coaxially surround side wall 
25 of basket 24, and an outwardly dished bottom wall 14 with a drain 16 
formed at the nadir thereof. Support plate 18 bridges drain 16 in bottom 
wall 14 and has ears 19 at either end welded to wall 14, such that basket 
24 may spin about its axis within tank 12. An axially spaced pair of 
inverted channels 28,30 extend entirely around the inside of tank side 
walls 13. Tank 12 is mounted within a protective enclosure or wall 31 by 
pins 32,34 (FIG. 3) received by suitable bearings 33,35. Pin 34 extends 
through bearing 35 and wall 31, and is operatively connected to an 
electrical motor 36 through a gear reducer 37 and a coupler 39. Gear 
reducer 37 and motor 36 are mounted and held in fixed position by a 
bracket 38 on wall 31 to pivot tank 12 about the axis of pins 32,34 
perpendicularly to the axis of basket 24. Motor 36 is connected to a 
suitable control circuit 40 or the like shown schematically in FIG. 3. 
As best seen in FIGS. 3 and 4, tank pivot pin 32 extends through bearing 33 
and enclosure wall 31. An arm 100 is mounted to the outer end of pin 32 by 
a bolt 102 and extends radially therefrom to terminate in a generally 
triangular foot 104 best seen in FIG. 4. A first limit switch 106 is 
mounted to enclosure 31 by a bracket 108 (FIG. 3) and has a switch arm 110 
extending therefrom. Switch arm 110 is spring-biased to a normal position 
(110a in FIG. 4) and is moved to an actuated position (110 in FIG. 4) by 
abutment with one side 111 of foot 104 in the upright or vertical position 
of tank 12 and basket 24. A second limit switch 112 is mounted by a 
bracket 114 to enclosure wall 31 and has an actuator arm 116 extending 
therefrom. Switch arm 116 is spring-biased to a normal position (116a in 
FIGS. 3 and 4) and is moved to an actuated position (116 in FIG. 4) by 
abutment with a second side 118 (FIG. 4) of foot 104 in the dump position 
of tank 12 and basket 24, as will be described hereinafter. Switches 106, 
112 are electrically connected to dump control circuit 40 (FIG. 3). 
A pair of flanges 42, 44 extend upwardly and outwardly from opposed side 
walls 13 at the open end of tank 12 to guide elements or parts into and 
out of basket 24 as will be described hereinafter. The other pair of 
opposite tank side walls extend upwardly at 46 and are connected to each 
other by an open tie bar 50. Shaft 26 extends through tie bar 50 and is 
rotatably coupled thereto by a pair of flange bearings 120, 122 
respectively internally mounted to the upper and lower walls 124, 126 of 
tie bar 50. A pair of collars 128, 130 encompass shaft 26 and abut the 
inner races of bearings 120, 122 to assist the bearings in providing axial 
or thrust support of basket 24 in the respective dump (FIG. 2) and upright 
(FIGS. 1 and 3) positions of tank 24. A motor 54 is carried by a bridge 56 
mounted on tie bar 50 and is connected directly to shaft 26 by a coupler 
55. In accordance with one important aspect of the present invention, 
motor 54 preferably comprises a variable speed hydrostatic drive motor 
connected by hydraulic lines 58 to a constant speed variable volume 
lever-controlled pump schematically illustrated at 60 (FIG. 1). For 
purposes to be described in detail hereinafter, pump 60 is connected to a 
speed control circuit 62 having means such as a switch 64 for placing 
control circuit 62 in alternate stop, low speed and high speed modes of 
operation. Preferably, speed control 62 further includes suitable means 
(not shown) for adjusting the level of the high and low motor running 
speeds. In one working embodiment of the invention, a five horsepower 
motor 54 and a corresponding pump 60 were purchased as a "K7 Series" 
combination from Kubik Hydraulics, Inc. of Troy, Mich. 
A safety hood 66 is carried by wall 31 around motor 54 and the open ends of 
basket 24 and tank 12. Hood 66 projects outwardly from wall 31 such that 
motor 54 may be rotated conjointly with tank 12 and basket 24, as 
illustrated at 68 in FIG. 2. Hydraulic lines 58 are clamped as at 70 (FIG. 
3) to the inside of enclosure 31 near the axis of pins 32,34 so that the 
hydraulic lines may follow motor 54 without snagging. 
A nozzle 72 is mounted on hood 66 above basket 24 and directed downwardly 
to spray coating solution over parts loaded into the basket. Nozzle 72 is 
connected by a suitable conduit 74 through a pump schematically 
illustrated at 76 (FIG. 1) to a coating solution supply (not shown). 
Preferably such solution supply includes means positioned beneath drain 16 
to recirculate solution dripping from or spun off of the coated parts. 
Pump 76 is connected to a control circuit 78 (FIG. 1) to actuate the pump 
and nozzle only when parts are being loaded into basket 24. 
A funnel opening 80 is provided in hood 66 above the open end of basket 24. 
An elongated ramp or chute 82 has a sloping upper surface which terminates 
at its lower end adjacent funnel opening 80. A pneumatic vibrator 84 (FIG. 
1) is rigidly coupled to chute 82 and connected to a control circuit 86. 
The angle of chute 82 with respect to the horizontal preferably is 
selectively adjusted at slightly less than the angle of repose of the 
particular parts or elements which are to be loaded into basket 24, such 
that parts loaded on the upper end of chute 82 will lie at rest on the 
chute until vibrator 84 is activated, at which time the parts migrate down 
the cute upper surface and fall in a relatively steady trickle or stream 
into basket 24. A chute angle of between ten and fifteen degrees has been 
found adequate for most small machine parts. Funnel 80 cooperates with 
flange 42 to guide falling parts into the basket. 
Operation of the invention proceeds as follows. Parts or elements to be 
coated are first loaded by suitable means onto the upper region of chute 
82. For example, a bin of parts may be lifted and tipped to spill parts 
onto the chute which may be ten to fifteen feet in total length. With tank 
12 and basket 24 in the upright positions shown in FIGS. 1 and 3 and in 
phantom in FIG. 4, vibrator 84 is then actuated by control circuit 86 to 
provide a steady trickle of parts into basket 24 as hereinabove described. 
At the same time, pump 76 is activated to spray parts spilling into basket 
24 with coating solution, and basket 24 is spun at a low first speed by 
motor 54 actuated through pump 60 and control circuit 62. Chute 82, nozzle 
72 and motor 54 operating at low speed, together with corresponding 
control elements, thus cooperate to spray the elements with coating 
solution as they are loaded and simultaneously to distribute the loaded 
elements within basket 24 evenly about the basket axis. 
When a sufficient number of parts are loaded, spray pump 76 and vibrator 84 
are turned off. Motor 54 is then operated at high speed by pump 60 and 
control 62 to spin dry the loaded and sprayed elements. Excess coating 
solution will be thrown off of the parts by centrifugal force through the 
perforations in the basket side wall onto tank walls 13, and will flow 
down the tank walls through drain 16. When the spinnning operation is 
completed, motor 54 is deactivated and basket 24 comes to a halt. Then 
motor 36 (FIG. 3) is activated by dump control 40 (FIG. 1) to rotate tank 
12, basket 24, motor 54 and actuator arm 100 conjointly clockwise as 
viewed in FIGS. 1 and 2 about the axis of pins 32, 34 (FIG. 3) to a 
position illustrated in FIG. 2 and in solid lines in FIG. 4 at which foot 
104 actuates switch 112. In this position, basket 24 and tank 12 open 
generally in the downward direction and the dried parts may spill 
therefrom across flange 44 into a suitable bin 90 (FIGS. 1 and 2) or the 
like. Channels 28,30 prevent solution collected on tank side walls 13 from 
flowing into bin 90. When the dumping operation is complete, the basket, 
tank, motor and actuator arm are rotated conjointly counterclockwise as 
viewed in FIGS. 1 and 2 until foot 104 actuates switch 106. Thus, arm 100 
cooperates with switches 106,112, dump control circuit 40 and motor 36 to 
position basket 24 and tank 12 in the load and dump positions. With the 
tank and basket in the upright starting position, the entire cycle as 
hereinabove described may be repeated. 
Although motor speed control 62, spray control 76, vibrator control 86 and 
dump control 40 have been illustrated schematically in FIGS. 1 and 3 as 
separate elements, such control functions are preferably carried out 
automatically at a central control station. Such station may utilize any 
of the usual machine control techniques, such as a conventional 
programmable drum and associated control relays constructed to operate the 
automatic coating and drying apparatus in the sequence hereinabove 
described. Details of such construction will be self-evident to persons 
skilled in the art. Where the several control functions are embodied in 
suitable automatic cycling means, the entire operation would require no 
intervention between the time that the parts are dumped onto chute 82 
until bin 90 is full. The necessary durations of the load, spin and dump 
cycles, the angle of chute 82 and the basket speeds during the load and 
spin cycles will depend upon the size and geometry of the parts to be 
coated, and may be determined empirically and then programmed into the 
control circuit. 
In addition to the manifest advantages of the present invention over the 
prior art multiple-step coating and drying operations hereinabove 
described, several perhaps more subtle advantages are also presented. In 
the basket drive arrangement, for example, direct coupling between drive 
motor 54 and basket 24 provides a more reliable coupling arrangement than 
do belt and pulley arrangments typical of the prior art. Moreover, such 
direct coupling is accomplished with relatively simple structure which may 
be easily and safely rotated with the tank and basket between load and 
dump position. The use of hydrostatic drive motor 54 and pump 60 provides 
rapid acceleration and deceleration between the load, spin and dump basket 
speeds. For example, basket 24 may be spun at a low first speed of ten to 
fifteen rpm to distribute parts within the basket automatically as they 
are being loaded, and then accelerated to five hundred fifty rpm, for 
example, for the drying mode of operation in about one-fourth of the time 
which would be required by a comparable electric motor. Similarly, the 
hydrostatic drive mechanism of the present invention may be rapidly 
decelerated and brought to a stop upon completion of the spin cycle, so 
that the dumping operation may proceed.