Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION
The sonic treatment of sheet material immersed in a treating
liquid for its cleaning, pickling, phosphating, or the like, is known;
5 however, usually the sonic vibraffons have been directed against
and relatively close to the large flat surfaces of the sheet material,
such as disclosed in the following U.S. patents:
Name No. Date Class
Engelhardt2,894,860~uly 14, 1959 134/1
Osterman, Jr.3,066,084November 17, 1962 134/1
et al
Tardoskegyi3,123,084March 3, 1964 134/1
Sasaki 3,240,963 March 15, 1966 134/1
Thus, when larger sheets were to be treated, more sonic vibrators were
used to cover their larger surface.
Nevertheless, Figs. 7 and 8 of Massa U.S. Patent No. 2,7û2,260
issued February 15, 1955 and found in U.S. Class 134 subclass 1 does
show sonic vibrators along the edges of a shallow tank for treating a
continuous web, but no means for supporting and directing the web or
even treating separate successive sheets are shown.
If the material to be sonically and liquid-treated is not a web,
but separate pieces, the pieces are usually suspended in a tank and/or
given a batch-type of treatment, the tanks for which are relatively
deep and thus requirè a large volume of treating liquid, such as shown
in the following U.S. patents:
Name No. Date Class
Hightower et al 3,033,710 May 8, 1962 134/1
Mobius et al3,449,163 June 10, 1969 134/1
~acke et al2,950,725 August 30, 1960 134/1
Brech 3,596,883 August 3, 1971 134/184
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~ v.;
Since it has been considered more effective to place the sonic
vibrators as close to the material being treated as possible, the
vibrators often have been placed in the treating liquid in the tanks,
including their necessary electrical connections, all of which requires
5 expensive protective shielding. Although vibrators have been
placed outside of tanks, they are usually placed in false bottoms in
the tanks as disclosed in the above mentioned Tardoskegyi and
~acke et al patents, or the vibrators have been placed on the bottoms
of the tanks as disclosed in the following U.S. patents:
Name No. Date Class
Camp 3,058,014 October 9, 1962 310/8.7
Cook 3,371,233 February 27, 1968 310/8.1
Brech 3,596,883 August 3, 1971 134/184
Morita 3,730,489 May 1, 1973 134/184
The use of conveyors which move through reactive liquids in
treating tanks is also known, even in ultrasonic cleaning liquid tanks
as shown in Branson U.S. Patent No. 3,222,221 issued December 7,
1965 found in Class 134 subclass 1, but the conveyors do not pass
through the sonically vibrated liquid. Also a conveyor resistant to
treating liquid is shown in Millard IJ.S. Patent No. 1,656,528 issued
January 17, 1928 found in Class 134 subclass 124, but such a conveyor
is not for or used in combination with sonic treating.
Several of the above mentioned patents, such as Engelhardt
U.S. Patent No. 2,894,860 issued ~uly 14, 1959; Osterman, ~r. et al
U.S. Patent No. 3,066,084 issued November 17, 1962 and Sasaki
U.S. Patent No. 3,240,963 issued March 15, 1966 disclose the sonic
30 treating of a web of sheet material from a coil, but no reference of
record was found in which either sheets or webs from coils were
supported during and in sonically vibrated liquids.
SUMMARY OF THE IN~IENTION
Generally speaking, the process or method of this invention
comprises supporting and passing sheet material to be treated with
5 their planes horizontal through a coplanar transversely horizontally
sonically vibrating liquid, vibrated by vibrators along the parallel
sides of the shallow tank containing the liquid. The sheet material
may comprise a continuous relatively thin web or strip or may
comprise individual separate sheets or plates, such as of metal or
10 steel, which sheet material is to be cleaned in a pickling,
phosphaffng, or solvent liquid solution. However, other liquid
treaffng processes than cleaning may be improved by the process
and apparatus of this invention.
A specific and preferred embodiment of an apparatus for
carrying out this invention comprises a relatively shallow
rectangular horizontal tank spaced from the floor such as by legs
and filled with the treating liquid to a depth of preferably less
than a foot. The liquid may be introduced into the tank through
20 a duct from above the top of the tank and the tank bottom may
be provided with a valved outlet duct for circulaffng, draining
and/or changing the liquid in the tank. Temperature control
means, including a heat exchanger, may be placed in the path
of liquid circulated through the tank for maintaining its
25 temperature.
There are provided along the two opposite parallel shallow
sides of the tank, substantially the depth of the liquid in the
tank, two series of sonic vibrator units bolted on transversely
30 staggered openings in the sidewalls of the tank. These units
each have a treating-liquid-resistant sonic vihration transmitting
plate, such as of stainIess steel or Monel metal, which is bolted
over the holes and against the outside of the sidewalls. The
sonic vibrators are integrally attached to the outside of these
35 plates for transmitting their vibraffons through these plates into
and through the liquid in the tank forming a horizontally sonically
vibrated treating liquid. Thus, the sonic vibrators are all outside
of the tank and treating liquid in it, and their electrical operaffng
and control connections are easily accessible and do not have to be
shielded from any chemically reactive treating liquid.
A means for supporting and conveying the sheets to be treated
5 horizontally through this horizontally~ sonic vibrating liquid from one
end of the tank to the other-, may comprise a plurality of parallel
sprocket chains which are supported by skid strips along the bottom
of the tank and suspended at their ends from sprocket wheels whose
peripheries project above the upper edge of the ends of the tank.
10 These sprocket wheels may be of a sufficient diameter so that the
chains on their return reaches extend underneath the tank between
the supporting legs for the tank. These sprocket wheels preferably
are driven by a hydraulic motor, either connected directly to their
shaft or by another sprocket or gear-driving mechanism. The
15 sprocket chains are preferably made of a treating-liquid-resistant
material, including plastic such as a high-molecular weight
polyethylene .
Since the sonic vibrating layer of treating liquid materially
20 increases the reactivity of the liquid on the sheet material being
treated, the temperature, concentration, and time of passage of
the sheet material through the liquid can be decreaæd
correspondingly to obtain at least the same amount of and usually
a better treating effect than can be obtained without sonic
25 vibrations. Thus, if a corrosive acid, such as hydrochloric acid
is employed for the pickling of steel sheets, the temperature of
the treating liqùid acid may be sufficiently low so that the danger
from fumes thereof and loss of acid is materially reduced, as well
as the energy required for maintaining an effective treating
30 temperature. Furthermore, the concentration of the acid in the
liquid also may be reduced, and unexpectedly the cleaning of the
plates is improved above that which can be obtained even at higher
temperatures and concentrations of acid.
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More particularly, the present invention relates to a
sonic treating apparatus for sheet metal, comprising a shallow
ta:nk of treating liquid ha~ing parallel sidewalls; a plurality
of sonic vibrators rn~ *-on and outside the parallel sidewalls
to produce a horizontally vibrating liquid in the tank; and a
plastic sprocket chain conveyor resistant to the treating
liquid for moving and supporting continuously the sheet material
to be treated in the tank horizontally through and transversely
to the horizontally vibrating liquid in the tank between the
sonic vibrators, with opposite edges of the sheet being adjacent
the parallel sidewalls and the vibrators.
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Objects and Advantages
Accordingly, it is an object of this invention to produce a
simple, effective, efficient, rapid, economic, anti-polluting, highly
versatile, sonic-vibrated liquid treating apparatus for sheet material.
Another object is to produce such an apparatus which is
conffnuous, uses less treating liquid, produces a cleaner or better
treated product, operates at a lower temperature, requires less
energy and power than previously known sonic vibrating treating
liquid processes and apparati. Since it takes about 3. 5 watts per
cubic centimeter of liquid in order to do an adequate job of sonic
vibrating, the less liquid employed, the less watts and power is
required .
Another object is to clean separate metal sheets or a
continuous web of metal by directing sonic vibrations along two
opposite parallel sides of the sheet to remove bubbles and to loosen
oxides and scale from its surface, as well as to remove sharp edges
from the surface, thus producing a smoother sheet product.
More specifically it is an object of this invention to pickle
steel sheets in a hydrochloric acid solution below about 170Q F.
with an acid concentration less than about 12% by weight at a rate
of at least about 50 tons of steel per hour. The advantage of
sonic pickling with hydrochloric acid instead of sulfuric acid is
that one can treat at a lower temperature and thus less fumes
escape. Usually to prevent fumes from escaping, less volatile
sulfuric acid is used in a dipping process, but then this has the
disadvantage of the disposal of the spent sulfuric acid, which is
more difficult to regenerate than spent hydrochloric acid.
Another specific object is that by this process and apparatus
a phosphate-treating of sheets can be performed effectively without
spraying the phosphate on the steel, and thus avoid any clogging
of the nozzles of the sprayers.
,
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1;~6~
BRIEF DESCRIPTION OF THE VIEWS
The above mentioned and other features, objects and advantages,
and manners of attaining them are described more specifically below by
5 reference to embodiments of this invention shown in the accompanying
drawings, wherein:
FIG. I is a schematic perspective view of an embodiment
of a treating tank and conveyor for supporting and passing sheet
10 material through a horizontal sonically vibrated liquid in the tank;
FIG. II is a slightly enlarged vertical section through the
right end of the tank shown in Fig. I, or taken along line II-II of
Fig. III, adapted for treating a conffnuous coil, web, or strip of
15 material;
FIG. III is a further enlarged vertical cross-section taken
along line III-III of Fig. II showing separate sheets of material passing
through the tank and supported by the conveyor; and
FIG. lV is a further enlarged vertical section through one
of the sonic vibrator units bolted to the righthand sidewall of the tank
shown in Fig. III.
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DETAILED DES~RIPTION OF PREFERRED EMBODIMENTS
In the figures there is shown a shallow rectangular tank 10
having two longer parallel sides 11 and 12, two end walls 13 and 14,
5 and a bottom 15. The tank 10 is provided with an interior rubber
or other treating-liquid-resistant coating 25 and may also be
provided with a cover 16 (see Figs. II, III and IV) which may be
removable. The tank 10 may be suspended above the floor by legs
17 between the floor and bottom 15 of the tank.
The treating liquid 20 may be introduced into the top of the
tank through a valved duct such as 18 shown in Fig. I, and the
bottom of the tank may be provided with one or more drain valved
ducts 19. For maintaining the temperature of the liquid 20, it may
be circulated from duct 19 to duct 18 through ducts 21 and 22 and
a heat exchanger 23 by means of a circulating pump 24. These
ducts, pump and heat exchanger are made of or lined with a
treating ]iquid-resistant material. The heat exchanger may be
heated by another fluid such as steam introduced therein through
20 a valved duct 26.
Along opposite parallel sides of the tank 10 in the walls 11
and 12 are provided a series of sonic vibrators 31 and 32, respectively,
integrally mounted to treating liquid-resistant metal plates 33 (see
25 Figs. III and IV), such as of stainless steel or Monel metal. These
plates 33 cover the apertures 27 and 28 in sidewalls 11 and 12,
respectively, of the tank 10. These apertures 27 and 28 are
preferably located close to the bottom 15 and lower edges of the
sidewalls 11 and 12 and spaced inwardly from each end wall 13 and 14
30 of the tank so that the apertures 27 and ~8 are staggered with
respect to each other on opposite sides of the tank. The treating
liquid 20 has its upper level 29 just above the top of apertures 27
and 28 so that the vibrators 31 and 32 produce horizontally vibrating
liquid particles across the tank 10. The sonic vibrators 31 and 32
1~6~jl2~
are connected via electrical manifold conduits 35 (see Fig~ I) to a
control panel box 36 supplied by electrical energy through a
conduit 37~ These sonic vibrators 31 and 32 are preset to vibrate
at a frequency between about 20 and 27 kilohertz, and preferably
at about 25 kilohertz~ One of the advantages of this invention is
that all of the electrical connections are outside of the tank 10
and of the treating liquid 20, and therefore do not have to be
fluid-insulated and shielded to be resistant to this treating liquid.
Furthermore, since all of the electrically operated sonic vibrators
31 and 32 are outside the tank, they may be easily replaced and
repaired or removed by removing the bolts 36 that connect their
flanged housings 37 and plates 33 to the sidewalls 11 and 12 of
the tank 10 and against a gasket which may be an extension of the
rubber lining coating 25 of the inside of the tank 10 surrounding
the apertures 27 and 28 (see Fig. IV).
For supporting, passing, conveying and/or conducting the
sheet material P or S through the horizontally vibrating treating
liquid 20 in the tank 10, there is provided a conveyor means 40
comprising a plurality of parallel sprocket chains 41, 42 and 43 which
pass around large sprocket wheels 45, 47, 49 adjacent the end wall
13 of the tank, and correspondingly respectively aligned sprocket
wheels 44, 46, 48 adjacent the opposite end wall 14. The diameter
of these wheels is preferably larger than the height of the walls
13 and 14 of the tank 10, so that the return reaches of the
sprocket chains 41, 42 and 43 may pass underneath the tank 10
in the space provided by the legs 17 between the tank's bottom 15
and the floor. The links of these sprocket chains 41, 42 and 43, and
preferably also the sprocket wheels 44 through 49 are made of a
30 materiaI which resists the treating soluffon 20, such as a high
molecular weight polyethylene plastic. The links are pinned
together by plastic pins 51 which engage corresponding pins 52
on the sprocket wheels 44 through 49 (see Figs~ II and III) for
positively moving the chains 41, 42, and 43. The parallel shafts
53 and 54 a~ opposide ends of the tank 10, to which the sprocket
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l-~t6~
wheels 44, 4B, and 48 are respectively keyed, may be supported by
brackets 55. Preferably shaft 54 is driven by a hydraulic motor 60
(see Fig~ I) having inlet and outlet ducts 61 and 62, respectively~
It is advantageous, however, that the speed of the shaft 54 and
conveyor 40 be infinitely variable in order to provide ffir different
treating times, depending upon the concentration and temper~ture
of the treating liquid, as well as the type of sheet material P or S
being treated. Thus, the speed of the hydraulic motor 60 may be
varied infinitely by controlling the valve 66 in its input duct 61.
There also may be provided adjacent the ends of the conveyor
40, supporting bars 71 and 72 for the sheet material fed to and from
the conveyor 40~ This is particularly advantageous for supporting
and guiding the separate sheets or plates P as shown in Figs. I and
III through the sonic vibrated liquid 20. However, a web of sheet
material S as shown in Fig. II from a coil C also may be fed,
supported and guided by the conveyor 40, in which case the end
supporting bars 71 and 72 may not be required. In order to
prevent too much sagging of the reaches of the conveyor chains 41,
42 and 43 in the tank 10, there are provided supporting means
such as skids 70 located along the bottom of the tank 10 made on a
treating-liquid-resistant material, such as a frictionless-type plastic.
(See Figs. II and III)
It is to be clearly understood that other types of conveyor
means instead of the treating-liquid-resistant sprocket chains 41,
42 and 43 may be provided for supporting and moving or passing
the sheets P and S through the horizontally sonic vibrating liquid
20 without departing from the scope of this invention. Furthermore,
if sprocket chains such as 41, 42 and 43 are employed, instead of
going around large single sprocket wheels 44 through 49 at each
end of the tank 10, there may be provided a pair of vertically
spaced wheels of smaller diameter for each large single sprocket
wheel, one smaller wheel projecting slightly above the top and the
other slightly below the bottom of the tank 10.
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EXAMPLE I
Separate hot rolled high tensile steel plates 27~" wide, 88" long,
.121" thick, and weighing 81 pounds each were pickled in a shallow
5 tank or vat, similar to tank 10 in Fig. I, which tank had a width of
10', length of 24' and a depth of about 1'. It was filled to a depth
of about 8" with 8g6 by weight aqueous hydrochloric acid solution
which was maintained at a temperature of about 165 F. by circulation
through a steam-heated heat exchanger. Three parallel plastic
10 sprocket chains transported these steel plates through the hydrochloric
acid pickling solution which chains were operated at a speed of 25'
per minute. This speed enabled 14 sheets per minute to be fed
through the pickling vat, which is equivalent to about 34 tons of
steel per hour. The dip length of the conveyor in the pick]ing acid
15 was about 16~' so that the dip time for each sheet averaged about
40 seconds. The ultrasonic vibrator units along each side of the
tank, each produced 500 watts of energy during the pickling of these
sheets, and seven of these units were placed along each side of the
tank. The frequency of these ultrasonic vibrators was 25 kilohertz.
20 The resulting pickled sheets were cleaner and more rapidly pickled
than was possible with the prior art dipping of the sheets in a
sulfuric acid solution or bath.
It has been found that by the use of the above described
25 apparatus that the concentration of the acid may vary between about
6Q6 and 12% by weight and preferably about 8% by weight, and that
the temperature of the hydrochloric acid treating solution can vary
between about 110 and 170 F. and preferably between about 150
and 165 F.
It was also found that if a piece of metal foil were suspended
vertically and transversely of the horizontal vibrations in the treating
liquid in the tank at the center line between the opposite parallel
rows of supersonic vibrators, that the foil, even though it was 5'
from the vibrators, was pierced with holes by vîbrating horizontal
particles in the treating liquid.
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Z
EXAMPLE II
Similar steel sheets to those described in Example I above were
treated in the same tank in a 3% by weight aqueous solution of zinc
5 phosphate.
If the sonic vibrators were not operated, it took about one
minute for the plates in the solution to get a coating thickness of
400 milligrams per square foot at a temperature of 160 F. However,
10 when the ultrasonic vibrators were operated, it not only cleaned the
steel plates but only took 30 seconds to produce the same coating
and at a temperature of between about 130 and 145 F. Thus, the
dwell time was reduced by half and the temperature was reduced
between 15 and 30 F., thereby materially saving on the energy
15 applied, and in addiffon the quality of the product was improved.
The temperature for the phosphate coating steel plates can be
between about 160 and 200 F., and the time of treatment can be
reduced as low as about 21 seconds.
It also i8 to be understood that the treating soluffon in the
tank, although it is primarily used for cleaning sheet material, may
be for other treating processes wherein intimate contact between
the treating liquid and the surface of the sheet P or S is required,
25 which contact is augmented by sonic vibrations. The important
feature of this invention is that the sonic vibrators along the edge
of the sheet provide sufficient vibration throughout the full sheet
and the liquid 20 so as to clean relatively wide sheets P or webs S.
While there is described above the principles of this invention
in connection with specific apparatus and methods of operating the
same, it is to be clearly understood that this description is made
only by way of example and not as a limitation to the scope of this
35 invention~
!
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