JPH03166353A - Strip immersion device for hot dip galvanizing bath - Google Patents

Abstract

PURPOSE:To uniformize the profile of an immersion roll and to prolong the service life of the roll by providing a driving device for sliding a support roll in a Zn bath and making a strip sheet slidable in a width direction. CONSTITUTION:A support roll 10 is attached to the inside of a Zn bath tank 13 used for galvanizing a strip 11 so that the support roll 10 is freely rotatable and in contact with the strip 11 surface. Further, a slide base 5 is allowed to slide by means of a motor 14 for driving the slide base in the sheet-width direction of the strip 11, and the support roll 10 supported by the above slide base 5 is allowed to slide in the sheet-width direction of the strip 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an immersion device for a hot-dip galvanizing bath in a continuous galvanized steel sheet manufacturing line.

[Conventional technology]

Generally, hot-dip galvanized steel sheets are produced by cleaning the surface of the steel material by deoxidizing, pickling, washing with water, etc., and then subjecting it to a flux treatment to make it easier for the plating to adhere to it, and then immersing it in a hot-dip galvanizing bath. This is a steel plate that has a zinc coating layer formed by the reaction between zinc and zinc, and is the most commonly and widely used anticorrosion treatment among metal coating methods for corrosion protection in recent years.

Specifically, as shown in FIG. 4, for example, a strip 22 that has been subjected to the galvanizing pretreatment as described above is placed in a snout 21 whose tip is immersed in a molten zinc bath 24.
is introduced into the molten zinc bath 24 without being exposed to the atmosphere. The strip 22 immersed in the molten zinc bath 24 is turned upward by a sink roll 27 provided in the bath, and is guided by support rolls 25 and 26 provided on the front and back sides of the strip 22 in the bath. while being pulled upwards. After removing the bath from the molten zinc 24, the slit nozzle 2 provided on the front and back sides of the strip 22
Excess zinc adhering to the front and back surfaces of the strip 22 is squeezed out by the high pressure gas injected by the strips 8 and 29.

In this case, the sink roll 27 provided in the zinc bath 24 is essential for changing the direction of the strip 22, but the support rolls 25 and 26 may actually be provided only on one side of the front and back sides of the strip 22. be. However, in general, as the speed of galvanizing lines increases, strip 22 is
In many cases, there are two rolls on the front and back sides of the roll.

Further, the sink roll 27 is generally not driven, and the support rolls 25 and 26 are connected to the strip 22.
Since the contact area with the zinc bathtub 23 is small, it is often driven by a motor installed outside the zinc bathtub 23, and the dross caught between the support rolls 25, 26 and the strip 22 is transferred to the strip 22. To prevent the strip from sticking, the rotational speed of the support rolls 25 and 26 is set at the same speed as the strip 2.
It is often set slower than line speed 2. From then on,
When referring to both sink roll and support roll,
This will be referred to as a dipping roll in a broad sense.

The above is a detailed explanation of the conventional hot-dip galvanizing bath immersion device in a continuous galvanizing line.In this case, the support roll mentioned above is driven as a slave, and the rotation speed of the support roll is set to be slower than the line speed of the strip. Due to the wear and tear caused by
For example, as shown in FIG. 2(a), it is known to form a diameter-changing portion whose diameter changes in the length range from the minimum width to the maximum width of the strip.

This abnormal profile (diameter change condition) of the support roll can cause quality defects such as edge bending of the strip, difficulty in adjusting the amount of zinc coating, and flatness defects that remain even after being wound into a product. This was a contributing factor. In addition, when a material such as pure iron, which is easily worn out, is used as the dipping roll, it is necessary to replace it every 4 to 5 days.

Therefore, in recent years, several methods have been disclosed to solve this problem. In general, it is considered that the shortest way to solve the problem is to make the support rolls made of materials that are less likely to wear out. A method is disclosed. Furthermore, Japanese Patent Publication No. 58-25468 discloses a method in which a support roll is thermally sprayed with Cr-C or Tt-C.

[Problem to be solved by the invention]

However, even with the above-mentioned known method, the desired effect cannot be achieved, as will be described later, particularly in the production of alloyed hot-dip galvanized steel sheets.

In general, in the hot-dip zinc bath of an alloyed hot-dip galvanizing production line, the aluminum concentration in the zinc bath must be lower than that in normal hot-dip galvanizing production in order to promote alloying. In this case, Fe eluted from the strip or support roll reacts with A1 in the molten zinc to form an Fe-AI alloy and floats on the zinc bath to form top dross. It becomes a Zn alloy and becomes dross floating in the zinc bath. This dross is
The dross adheres to the surface of the support roll and grows, but since the dross is abraded away only in the part where the strip passes, as shown in Figure 2(b), the dross adheres to only the ends of the support roll. As the diameter continues to increase,
It shows a profile similar to a state in which the diameter of the support roll is relatively reduced due to wear.

Therefore, the object of the present invention is to provide a hot-dip galvanizing bath that can uniformize the profile of a roll dipped in a zinc bath, thereby extending the life of the dipped roll, and thereby stably obtaining high-quality hot-dip galvanized steel sheets. An object of the present invention is to provide an immersion device.

[Means to solve the problem]

The present invention for solving the above problems preferably includes a dipping device for a hot-dip galvanizing bath in a continuous hot-dip galvanizing production line, which preferably includes a drive device for sliding a support roll in the zinc bath in the width direction of the strip plate. is synchronized with the slide of the support roll,
The sink roll in the zinc bath is also characterized by being equipped with a drive device for sliding it in the width direction of the strip plate.

[Effect]

The operation of the present invention will be explained with reference to FIGS. 5(a) and 5(b).

Figure 5(a) shows the diameter profile when using a support roll made of easily worn material such as pure iron.
b) shows the diameter profile when using a support roll made of a material that is not easily worn and is thermally sprayed with CrC or the like. In the figure, the diameter profile when sliding is shown by a solid line, and the diameter profile when not sliding is shown by a two-dot chain line.

In the present invention, a strip dipping device for a hot-dip galvanizing bath is equipped with a drive device for sliding the support roll in the width direction of the strip plate, and this drive device allows the support roll to be kept in contact with the strip, and to control the strip dipping at all times or at appropriate times. It can be slid in the board width direction. Therefore, the diameter profile is as shown in FIG. 5(a). When sliding, the center part is always in contact with the strip, so although the diameter of the center part of the roll is somewhat smaller than other parts, each part of the body of the support roll is in contact with the strip over a wide range. As a result, the wear range expands in the strip width direction and its slope becomes gentler, making the diameter profile uniform.

Furthermore, even when using a roll made of a material that is hard to wear, as shown in Figure 5(b), by sliding the support roll, the area where the dross is attached can be pushed toward the end of the roll, allowing the strip to be removed. It is possible to prevent dross from adhering to the passage area, and the diameter profile of this area is made uniform.

Further, even in this case, by increasing the amount of slide of the support roll, it is possible to completely prevent the adhesion of dross.

Furthermore, by sliding the sink roll in synchronization with the slide of the support roll, it is possible to prevent the generation of strip wrinkles and squeezing defects due to stress in the diagonal direction of the strip, which will be described later.

[Specific configuration of the invention]

The present invention will be explained in detail based on a specific example of a support roll drive device shown in FIG.

A zinc bath 13 is formed by excavating the floor l, and the strip 11 is immersed in this zinc bath 13 to be galvanized.

Close to the surface side of the strip 11, in the width direction of the strip,
A slide stand 5 is suspended horizontally so as to straddle this zinc bathtub 13. This slide stand 5 is supported on both banks by
These rails 6, 6 are provided with a protruding line 6a along the width direction of the strip plate.
A groove 5a formed on the lower surface of the slide table 5 is fitted to the slide table 5, so that the slide table 5 can slide on the rails 6, 6 only in the width direction of the strip l1.

With respect to the slide base 5 configured in this way, the π-shaped support roll supporting frame 8 is attached to the horizontal member 8b.
Both ends of the slide base 5 and the protruding portion 5c of the slide base 5 are fixed by fastening with fixing bolts 9, 9,
A support roll 1 is attached to the tip of the vertical member 8a suspended from both sides of the horizontal member 8b by support roll bearings 12.
o is rotatably mounted in contact with the surface of the strip 11. This support roll 10 is driven by a support roll drive motor 2 installed on the left side of the slide table 5 via a drive shaft 4 . The drive shaft 4 is connected to the output shaft 2a of the support roll drive motor 2 and the universal joint 3.
Similarly, it is connected to the rotating shaft of the support roll 10 through the universal joint 7, so that the rotation of the output shaft 2a of the support roll drive motor 2 is smoothly transmitted to the support roll IO.

On the other hand, on the right side of the slide table 5, a slide table driving motor 14 is fixed on the floor l, and its output screw shaft 13 is screwed into the screw hole 5b of the continuous part 5d at the right end of the slide table 5. are combined.

Therefore, by rotating the output screw shaft 5b of the slide table drive motor l4 in the forward and reverse directions, the slide table 5 can be freely slid in the width direction of the strip l1.

Although the driving device for a certain support roll has been described in detail above, other support rolls and sink rolls can also be slid by a similar device.

When the sink roll is slid in the same way as the support roll, the amount of wear is extremely small because the sink roll rotates in synchronization with the line speed of the strip. In addition, the diameter of sink rolls is generally much larger than that of support rolls, so in order to cause the same change in diameter as that of support rolls, several times the amount of attached dross is required.
Normally, the diameter profile of sink rolls does not seem to pose much of a problem. However, if the sink roll does not slide and is fixed, if the slide speed of the support roll is too fast, the strip will be moved diagonally between it and the sink roll due to its lateral frictional force. It is preferable to slide it in sync with the support roll, as this may cause wrinkles or squeezing.

(Example) Next, test results using the apparatus of the present invention will be described.

The test was conducted using a continuous hot-dip galvanizing production line to test 50 cold-rolled strips with a thickness of 0.4 mm and a width of 300 m.
MPM for 3 days, and the profile of the support roll was examined. The total weight of threaded steel during these three days was approximately 2
It is 00t.

The shape of the support roll was 150 w in diameter and 500 w in body length, and the material used was pure iron, which is easy to wear, on the front side of the strip, and SUS316, which is hard to wear, on the back side. The sliding stroke amount of the support roll in the width direction of the strip plate was 160 mm (±80 mm), and the sliding speed was Q, 2 mm/sec. Also, the slide was made to keep moving without stopping at the end of the stroke. On the other hand, the sink roll was slid in sync with the support roll.

The AI concentration in the hot-dip zinc was set to 0.09%, the same as in the case of normal alloyed hot-dip galvanizing, and the temperature of the zinc bath and strip was set slightly higher at 470°C to promote the generation of dross. .

The results of the test conducted under the conditions shown above are shown in FIG.

In the case of pure iron support rolls on the front side of the strip, the diameter at the center of the support roll is slightly smaller than at the ends, but the profile is approximately the same diameter, so edge bending etc. can be prevented. You can continue to use it afterwards.

In this test, the slide of the support roll was not stopped at the stroke end, but if the diameter of the end of the support roll is larger than that of the center,
By slightly stopping at the end of the stroke, it is possible to adjust the wear condition of the support roll over the length of the body.

On the other hand, in the case of the SUS 316 support roll on the back side of the strip, no dross was observed within the sliding range of the support roll, and the condition was good.

〔Effect of the invention〕

As explained in detail above, according to the present invention, the profile of the dipping roll is made uniform by sliding the dipping roll in the zinc bath in the width direction of the strip in contact with the strip at all times or at appropriate times, thereby making the dipping roll uniform. The lifespan of the rolls can be extended, thereby making it possible to stably obtain high-quality hot-dip galvanized steel sheets.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the support roll drive device according to the present invention, FIG. 2 is a diagram for explaining the abnormal profile of the support roll, FIG. 3 is a diagram showing test results in the device of the present invention, and FIG. FIG. 5 is a diagram for explaining a general strip dipping apparatus for a hot-dip galvanizing bath, and FIG. 5 is a diagram for explaining a diameter profile when using the apparatus of the present invention. ■...Floor, 2...Support roll drive motor 3,
7...Universal joint 4...Drive shaft, 5...Slide base 6...
・Rail, support roll support frame 10・
...Support roll, 11...Strip l2...
Support roll bearing, l4... - Slide table drive motor Fig. 2 (α) (b) Fig. 3 Fig. 4

Claims (2)

[Claims] (1) A strip for a hot-dip galvanizing bath, which is characterized by being equipped with a drive device for sliding a support roll in the zinc bath in the strip width direction, in a dipping device for a hot-dip galvanizing bath in a continuous hot-dip galvanizing production line. Immersion equipment. (2) The immersion device for a hot-dip galvanizing bath according to claim 1,
Furthermore, while synchronizing with the slide of the support roll,
A strip dipping device for a hot-dip galvanizing bath, characterized in that it is equipped with a drive device for sliding a sink roll in the zinc bath in the width direction of the strip plate.