Acid Pickling Device
Technical Field
This invention relates to an acid pickling device for washing and removing oxide scale,
formed on the surface of a strip plate, by acid pickling.
Background Art
Fig. 4 is a perspective side view of a conventional acid pickling device, and Fig. 5 is a
sectional view taken on line V-V in Fig. 4.
In the conventional acid pickling device, as shown in Figs. 4 and 5, an acid pickling tank
101, which is open upwards, is filled with an acid liquid L for acid pickling of a strip
steel plate S. A lid 102 is attached to the top of the acid pickling tank 101 to form an inlet
portion 103, and an outlet portion 104. To the inlet portion 103 and the outlet portion
104, aerial deflector rolls 105, 106 and immersion deflector rolls 107, 108 are attached,
respectively.
From a lower surface of the lid 102, a hook 109 is suspended. From the hook 109, a
ceiling plate 111 is suspended via an engaging stop 110. From the ceiling plate 111, a
bottom plate 113 is suspended via connecting plates 112 located at both side parts. On a
lower surface of the ceiling plate 111, many immersion guide rolls 115 rotatable via
bearing portions 114 are mounted along a direction of travel of the strip steel plate S. On
an upper surface of the bottom plate 113, many skids 116 are attached at positions
opposed to the immersion guide rolls 115.
Thus, the strip steel plate S is guided by the aerial deflector roll 105 and the immersion
deflector roll 107 at the inlet portion 103 into the acid liquid L in the acid pickling tank
101, and travels, while being guided, between the immersion guide rolls 115 and the
skids 116. At this time, oxide scale formed on the surface of the strip steel plate S is
washed with the acid liquid L and removed thereby. Then, the strip steel plate S is
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guided by the immersion deflector roll 108 and the aerial deflector roll 106 at the outlet
portion 104, and delivered to the outside of the acid pickling tank 101.
Such a conventional acid pickling device is disclosed, for example,, in Japanese
Unexamined Patent Publication No. 5-78870 (No Indian Patent Available).
With the foregoing conventional acid pickling device, the acid liquid L is filled into the
acid pickling tank 101 which is open upwards, and the lid 102 is attached to the top of
the acid pickling tank 101. Thus, the surface area of the acid liquid L in the acid
pickling tank 101 is so wide that a loss of an acid becomes great as a result of
evaporation. Consequently, the washing and removal of the oxide scale on the strip
steel plate S by acid pickling are performed insufficiently.
Furthermore, the strip steel plate S travels, while being guided, between the immersion
guide rolls 115 and the skids 116 in the acid pickling tank 101. Hence, as the strip steel
plate S moves, the acid liquid L follows, and a flow of the acid liquid L toward a
downstream side in the direction of travel of the strip steel plate S occurs. This makes
the surface of the acid liquid L beside the outlet portion 104 high, causing an overflow
of the acid liquid L from the outlet portion 104 to the outside of the acid pickling tank
101. Besides, the many immersion guide rolls 115 and skids 116 that guide the travel of
the strip steel plate S in the acid liquid L are suspended from and supported by the lid
102. Thus, a head weight acts on the lid 102, and may damage it.
The present invention attempts to solve the above problems. Its object is to provide an
acid pickling device which suppresses a loss of an acid by decreasing a free surface of
an acid liquid in an acid pickling tank, and prevents an overflow to the outside of the
tank, thereby making acid pickling of a strip plate efficient.
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Disclosure of the Invention
The present invention is an acid pickling device for acid pickling a strip plate by
causing the strip plate to travel in an acid pickling tank filled with an aeid liquid while
guiding the strip plate by an immersion guide roll and a skid, wherein an acid pickling
tank lid for covering a top of the acid pickling tank is disposed such that a central part
of the acid pickling tank lid is located at a lower position than a liquid level of the acid
liquid in the acid pickling tank to cover a free surface of the acid liquid.
Thus, the surface area of the acid liquid in the acid pickling tank is narrower than in the
earlier technology, thereby suppressing a loss of an acid due to evaporation, and
ensuring reliable washing and removal of oxide scale on the strip plate by acid pickling.
Moreover, the free surface of the acid liquid in the acid pickling tank is forcibly
restrained, so that the liquid level of the acid liquid is held constant, thus preventing an
overflow of the acid liquid to the outside of the tank. Consequently/ the acid pickling of
the strip plate can be performed efficiently.
The present invention also concerns the acid pickling device, wherein the immersion
guide roll is provided on the acid pickling tank lid, and the skid is provided on a
support block installed at a bottom of the acid pickling tank.
Thus, there is no need to suspend heavy materials from the lid, so that the lid can be
decreased in rigidity, and can be made light-weight.
The present invention also concerns the acid pickling device, wherein the support block
is provided with a bottom plate positioned below the skid and extending along a
direction of travel of the strip plate.
Thus, as the strip plate moves in the acid pickling tank, the acid liquid follows, and is
flowed downstream in the travel direction. As a result, the acid liquid is circulated, and
becomes no more stagnant.
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The present invention also concerns the acid pickling device, wherein a plurality of the
immersion guide rolls and a plurality of the skids are provided, with predetermined
spacing, in a direction of travel of the strip plate, the support block is provided with a
bottom plate positioned below the skid and extending along the direction of travel of
the strip plate, and the bottom plate is provided with acid liquid passages each located
between the adjacent skids.
Thus, as the strip plate moves in the acid pickling tank, the acid liquid follows,
generating a flow toward a downstream side in the travel direction.
However, the flow of the acid liquid is circulated in the acid pickling tank through the
acid liquid passages, thus eliminating stagnation of the acid liquid, and releasing the
liquid pressure. Hence, it does not take place that the surface of the acid liquid
suddenly becomes high, causing an overflow to the outside of the tank. In addition, the
pressure imposed on the lid is also decreased, thus enabling the lid to be decreased in
strength and be rendered light-weight.
The present invention also concerns the acid pickling device, wherein the acid liquid
passages are each provided between the adjacent skids and upstream in the direction of
travel of the strip plate.
Namely, the acid liquid passages are positioned just behind the site of passage of the
strip steel plate between the immersion guide rolls and the skids. Thus, the static
pressure of the acid liquid on the exit side progressively increases compared with the
entrance side for the strip plate in the acid pickling tank. Hence, the acid liquid is
agitated, and its circulation can be promoted.
The present invention also concerns the acid pickling device, wherein a plurality of the
immersion guide rolls and a plurality of the skids are provided, with predetermined
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spacing, in a direction of travel of the strip plate, and communication holes for the acid
liquid are provided in the support blocks that support the skids.
Thus, as the strip plate moves in the acid pickling tank, the acid 'liquid follows,
generating a flow toward a downstream side in the travel direction. However, the flow
of the acid liquid is circulated in the acid pickling tank through the communication
holes, thus eliminating stagnation of the acid liquid, and releasing the liquid pressure.
Hence, it does not take place that the surface of the acid liquid suddenly becomes high,
causing an overflow to the outside of the tank. In addition, the pressure imposed on the
lid is also decreased, thus enabling the lid to be decreased in strength and be rendered
light-weight.
Brief Description of the Drawings
Fig. 1(a) is a schematic side view of an acid pickling device according to a first
embodiment of the present invention. Fig. 1 (b) is a graph showing the static pressure
distribution of an acid pickling liquid of the acid pickling device. Fig. 2 is a sectional
view taken on line II-II in Fig. 1 (a) . Fig. 3 (a) is a schematic side view of an acid
pickling device according to a second embodiment of the present invention. Fig. 3(b) is
a graph showing the static pressure distribution of an acid pickling liquid of the acid
pickling device. Fig. 4 is a schematic side view of a conventional acid pickling device.
Fig. 5 is a sectional view taken on line V-V in Fig. 4.
Best Mode for Carrying Out the Invention
A first embodiment of the present invention will now be described in detail by
reference to the accompanying drawings.
In an acid pickling device of the first embodiment, as shown in Fig. 1 (a) and Fig. 2, an
acid pickling tank 11, which is open upwards, is filled with an acid liquid L for acid
pickling of a strip steel plate S. A lid 12 is attached to an upper opening of the acid
pickling tank 11 to form an inlet portion 13, and an outlet portion 14. The lid 12 has an
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outer peripheral, flange portion 12a fitted liquid-tight into a receiver portion 11a formed
at a side part of the acid pickling tank 11, and has a central part forming a covering
portion 12b which is concave downwardly. The covering portion 12b enters the acid
liquid L in the acid pickling tank 11, and lies below the liquid level of the acid liquid.
Thus, most of a free surface of the acid liquid L in the acid pickling tank 11 is covered
with the covering portion 12b of the lid 12. To the inlet portion 13 and the outlet
portion 14, aerial deflector rolls 15, 16 and immersion deflector rolls 17, 18 are attached,
respectively.
On a lower surface of the covering portion 12b of the lid 12, immersion guide rolls 20a
to 20e are rotatably mounted by a pair of (i.e., right and left) bearing portions 19a to 19e
made of a metal (or resin, carbon or ceramic) . This plurality of immersion guide rolls
20a to 20e are arranged parallel to each other, with predetermined spacing, along a
direction of travel of the strip steel plate S. On a bottom surface of the acid pickling tank
11, a plurality of support blocks 21a to 21e are arranged parallel along the direction of
travel of the strip steel plate S. To the top of the support blocks 21a to 21 e, a bottom
plate 22 is fixed so as to connect the support blocks 21a to 21 e together. To an upper
surface of the bottom plate 22, a plurality of skids 23a to 23e are fixed at positions
opposed to the immersion guide rolls 20a to 20e.
In the support blocks 21a to 21e, acid liquid communication holes 24a to 24e, through
which the acid liquid L can flow, are formed. In the bottom plate 22, acid liquid
passages 25a to 25d, through which the acid liquid L can flow, are each formed between
the adjacent two of the skids 23a to 23e downstream in the direction of transport of the
strip steel plate S. These acid liquid passages 25a to 25d are each in a slit, circular, or
rectangular shape.
Thus, the strip steel plate S is guided by the aerial deflector roll 15 and the immersion
deflector roll 17 at the inlet portion 13, and led into the acid liquid L of the acid pickling
tank 11, where the strip steel plate S travels, while being guided, between the plurality
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of immersion guide rolls 20a to 20e and the plurality of skids 23a to 23e. On this
occasion, oxide scale formed on the surface of the strip steel plate S is washed with and
removed by the acid liquid L. Then, the strip steel plate S is guided by the immersion
deflector roll 18 and the aerial deflector roll 16 of the outlet portion 14 to the outside of
the acid pickling tank 11.
According to the acid pickling device of the present embodiment, the covering portion
12b in the central part of the lid 12 enters the acid liquid L in the acid pickling tank 11,
and lies below the liquid level of the acid liquid. As a result, most of the free surface of
the acid liquid L in the acid pickling tank 11 is covered with the covering portion. Thus,
the surface area of the acid liquid L in the acid pickling tank 11 becomes smaller than in
the earlier technology. Hence, a loss of an acid due to evaporation is decreased to
ensure the reliable washing and removal of the oxide scale formed on the strip steel
plate S by acid pickling.
In addition, as stated above, the covering portion 12b of the lid 12 enters the acid liquid
L in the acid pickling tank 11, thereby forcibly restraining the free surface of the acid
liquid L in the acid pickling tank 11, so that the liquid level of the acid liquid L, can be
kept constant.
Besides, the acid liquid communication holes 24a to 24e, through which the acid liquid
L can flow, are formed in the support blocks 21a to 21e. In the bottom plate 22, the acid
liquid passages 25a to 25d, through which the acid liquid L can flow, are formed. Thus,
when the strip steel plate S travels, while being guided, between the immersion guide
rolls 20a to 20e and the skids 23a to 23e, the acid liquid L follows the strip steel plate S
as it moves. As a result, a downstream flow of the acid liquid L in the traveling
direction of the strip steel plate S occurs. However, the acid liquid L does not wave,
since its liquid level is restrained by the covering portion 12b of the lid 12. This flow of
the acid liquid L moves downward through the acid liquid passages 25a to 25d, passes
through the communication holes 24a to 24e, and is returned to an upstream side in the
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travelling direction of the strip steel plate S. In this manner, the acid liquid L circulates
within the acid pickling tank 1.1. There is no stagnation of the acid liquid L, and the
liquid pressure is released.
Hence, as shown in Fig. 1(a), a differential pressure Ap occurs in the acid liquid L
between its pressure at the inlet portion 13 and that at the outlet portion 14 of the acid
pickling tank 11. Hence, circulation of the acid liquid L is promoted, and it does not
occur that the surface of the acid liquid L beside the outlet portion 14 suddenly rises,
causing overflow of the acid liquid L to the outside of the acid pickling tank 11.
Moreover, the liquid pressure in the acid pickling tank 11 is released, and does not
increase. Thus, the strength of the lid 12 can be reduced.
Opposite the plural immersion guide rolls 20a to 20e suspended from the lid 12, the
plural skids 23a to 23e are fixed to the bottom plate 22 on the plural support blocks 21a
to 21 e fixed to the bottom surface of the acid pickling tank 11. Thus, there is no need to
suspend heavy materials from the lid 12, so that the rigidity of the lid 12 can be
decreased, and it can be made light-weight.
Next, a second embodiment of the present invention will be described in detail by
reference to the accompanying drawings. Members having the same functions as those
explained in the aforementioned embodiment will be assigned the same numerals or
symbols, and overlapping explanations will be omitted.
In an acid pickling device according to the second embodiment, as shown in Fig. 3(a),
an acid pickling tank 31, which is open upwards, is filled with an acid liquid L for acid
pickling of a strip steel plate S. A lid 32 is attached to an upper opening of the acid
pickling tank 31 to form an inlet portion 33, and an outlet portion 34. The lid 32 has a
central part forming a covering portion 32b which is concave downwardly. The
covering portion 32b enters the acid liquid L in the acid pickling tank 31, and lies below
the liquid level of the acid liquid. Thus, most of a free surface of the acid liquid L in the
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acid pickling tank 31 is covered with the covering portion 32b of the lid 32. To the inlet
portion 33 and the outlet portion 34, aerial deflector rolls 35, 36 and immersion deflector
rolls 37, 38 are attached, respectively.
On a lower surface of the covering portion 32b of the lid 32, immersion guide rolls 40a
to 40e are rotatably mounted by bearing portions 39a to 39e. On a bottom surface of the
acid pickling tank 31, a plurality of support blocks 41a to 41 e are arranged parallel
along the direction of travel of the strip steel plate S. To the top of the support blocks
41a to 41e, a bottom plate 42 is fixed so as to connect the support blocks 41a to 41e
together. To an upper surface of the bottom plate 42, a plurality/ of skids 43a to 43e are
fixed at positions opposed to the immersion guide rolls 40a to 40e.
In the support blocks 41a to 41e, acid liquid communication holes 44a to 44e, through
which the acid liquid L can flow, are formed. In the bottom plate 42, acid liquid
passages 45a to 45d, through which the acid liquid L can flow, are each formed between
the adjacent two of the skids 43a to 43e upstream in the direction of transport of the
strip steel plate S.
Thus, the strip steel plate S is guided by the aerial deflector roll 35 and the immersion
deflector roll 37 at the inlet portion 33, and led into the acid liquid L of the acid pickling
tank 31, where the strip steel plate S travels, while being guided, between the plurality
of immersion guide rolls 40a to 40e and the plurality of skids 43a to 43e. On this
occasion, oxide scale formed on the surface of the strip steel plate S is washed with and
removed by the acid liquid L. Then, the strip steel plate S is guided by the immersion
deflector roll 38 and the aerial deflector roll 36 of the outlet portion 34 to the outside of
the acid pickling tank 31.
According to the acid pickling device of the present embodiment, the covering portion
32b of the lid 32 enters the acid liquid L in the acid pickling tank.31, and lies below the
liquid level of the acid liquid. As a result, most of the free surface of the acid liquid L in
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the acid pickling tank 31 is covered with the covering portion. Thus, the surface area of
the acid liquid L becomes small. Hence, a loss of the acid due to evaporation is
decreased to ensure the reliable washing and removal of the oxide scale formed on the
ship steel plate S by acid pickling. In addition, the free surface of the acid liquid L in
the acid pickling tank 31 is forcibly restrained, so that the liquid level of the acid liquid
L can be kept constant.
Besides, when the strip steel plate S travels, while being guided, between the immersion
guide rolls 40a to 40e and the skids 43a to 43e, the acid liquid L follows the strip steel
plate S as it moves. As a result, a downstream flow of the acid liquid L in the traveling
direction of the strip steel plate S occurs. However, this flow of the acid liquid L moves
downward through the acid liquid passages 45a to 45d, passes through the
communication holes 44a to 44e, and is returned to an upstream side in the transport
direction of the strip steel plate S. In this manner, the acid liquid L circulates within the
acid pickling tank 31. This eliminates stagnation of the acid liquid L, and releases the
liquid pressure. Hence, as shown in Fig. 3 (a) , a differential pressure Ap occurs in the
acid liquid L between its pressure at the inlet portion 33 and that at the outlet portion 34
of the acid pickling tank 31. Also, the differential pressure progressively increases
owing to a load pressure Ap+, thus promoting circulation of the acid liquid L. This is
because the acid liquid passages 45a to 45d are located at positions just behind the site
of passage of the strip steel plate S between the immersion guide rolls 40a to 40e and the
skids 43a to 43e. Thus, agitation of the acid liquid L is promoted. On the other hand, it
does not occur that the surface of the acid liquid L beside the outlet portion 34 suddenly
rises, causing overflow of the acid liquid L to the outside of the acid pickling tank 31.
Moreover, the liquid pressure in the acid pickling tank 31 is released, and does not
increase. Thus, the strength of the lid 32 can be reduced.
In each of the above-described embodiments, the central part of the lid 12 or 32 was
rendered concave downwardly to form the covering portion 12b or 32b. However, a
separate member may be provided on the lower surface of the lid 12 or 32 to form the
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covering portion 12b or 32b. Furthermore, the numbers of the immersion guide rolls
20a to 20e or 40a to 40e, and the skids 23a to 23e or 43a to 43e are not restricted to those
described in the embodiments.
Industrial Applicability
As described above, the acid pickling device of the present invention immerses a strip
plate in an acid pickling tank to wash and remove oxide scale, formed on the surface of
the strip plate, by acid pickling. This device is preferred for use in a surface treating
device for treating a continuously traveling strip plate at a high speed.
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WE CLAIM:
1. An acid pickling device for acid pickling a strip plate by causing the strip plate to
travel in an acid pickling tank filled with an acid liquid while guiding the strip
plate by an immersion guide roll and a skid, wherein
an acid pickling tank lid for covering a top of the acid pickling tank is disposed
such that a central part of the acid pickling tank lid is located at a lower position
than a liquid level of the acid liquid in the acid pickling tank to cover a free
surface of the acid liquid.
2. The acid pickling device of claim 1, wherein the immersion guide roll is provided
on the acid pickling tank lid, and the skid is provided on a support block
installed at a bottom of the acid pickling tank.
3. The acid pickling device of claim 2, wherein the support block is provided with a
bottom plate positioned below the skid and extending along a direction of travel
of the strip plate.
4. The acid pickling device of claim 2, wherein a plurality of the immersion guide
rolls and a plurality of the skids are provided, with predetermined spacing, in a
direction of travel of the strip plate, the support block is provided with a bottom
plate positioned below the skids and extending along the direction of travel of
the strip plate, and the bottom plate is provided with acid liquid passages each
located between the adjacent skids.
5. The acid pickling device of claim 4, wherein the acid liquid passages are each
provided between the adjacent skids and upstream in the direction of travel of
the strip plate.
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6. The acid pickling device of claim 2, wherein a plurality of the immersion guide
rolls and a plurality of the skids are provided, with predetermined spacing, in a
direction of travel of the strip plate, and communication holes for the acid liquid
are provided in the support blocks that support the skids.
Dated this day of

An acid pickling tank 11 is filled with an acid liquid L, and a lid 12 is attached to the
acid pickling tank 11 A central part of the lid 12 is depressed downwards to form a
covering portion 12b. The covering portion 12b is located at a lower position than the
liquid level ,of the acid liquid L in the acid pickling tank 11 to cover a free surface of the
acid liquid L. Immersion guide rolls 20a to 20e are provided on the covering portion
12b, support blocks 21a to 21e are provided at the bottom of the acid pickling tank 11,
and skids 23a to 23e are provided on the support blocks 21a to 21e via a bottom plate 22.
Thus, the free surface of the acid liquid L in the acid pickling tank 11 is decreased to
suppress a loss of an acid, and prevent an overflow of the acid liquid L to the outside of
the tank,, thereby making acid pickling of the strip steel plate S efficient.