Method for suppressing Bernoulli negative pressure effect in high-speed rotating area of rolls of cold rolling temper mill

Abstract

The present invention provides a method for suppressing the Bernoulli negative pressure effect in the high-speed rotation area of the rolls of a cold rolling temper mill, which includes the following steps: arranging a spraying device on the inlet side of the mill housing; making the spraying direction of the spraying device have a certain angle with the strip rolling horizontal line; spraying gas and / or liquid with a certain pressure onto the surfaces of the intermediate roll and the backup roll through the nozzles of the spraying device, so as to balance the air pressure in each section area of the surfaces of the intermediate roll and the backup roll. Under the action of the spraying pressure, the tempering liquid blows and washes away the stains on the surface of the backup roll, preventing the accumulation of dirt, effectively solving the problem of irregular multi-strip stains often appearing in the middle of the strip surface in the width direction after tempering by the temper mill, and eliminating the problem of the degradation of the strip surface quality after tempering caused by this defect.

Description

Technical Field

[0001] The present invention relates to the field of strip rolling production, and particularly to a method for suppressing the Bernoulli negative pressure effect in the high-speed rotation area of the rolls of a cold rolling temper mill. Background Art

[0002] During the production of a cold rolling temper mill, multiple irregular stains often appear in the middle of the strip width direction, ultimately resulting in the degradation of the surface quality of the strip after tempering.

[0003] In summary, the following problems exist in the prior art: the surface quality of the strip after tempering is poor. Summary of the Invention

[0004] The purpose of the present invention is to solve the problem of poor surface quality of the strip after tempering.

[0005] To this end, the present invention proposes a method for suppressing the Bernoulli negative pressure effect in the high-speed rotation area of the rolls of a cold rolling temper mill, including the following steps:

[0006] A spraying device is arranged on the inlet side of the mill housing;

[0007] The spraying direction of the spraying device forms a certain angle with the strip rolling horizontal line;

[0008] Gas and / or liquid with a certain pressure is sprayed onto the surfaces of the intermediate roll and the backup roll through the nozzles of the spraying device, so that the air pressure in each section area of the surfaces of the intermediate roll and the backup roll is balanced, to suppress the negative pressure area or make the negative pressure area become a positive pressure area, which is beneficial to the discharge of dirt and prevent the accumulation of dirt.

[0009] Specifically, the spraying device is provided with multiple equally spaced nozzles, and the angle between the nozzles of the spraying device and the rolling direction of the strip is 30° to 35°.

[0010] Specifically, a liquid-gas hybrid purging device for the intermediate roll and the backup roll is added on the inlet side of the mill, and compressed air and tempering liquid are mixed into a liquid-gas mixture and sprayed onto the surfaces of the intermediate roll and the backup roll.

[0011] Specifically, the spraying coverage areas of adjacent nozzles have an overlapping part, and the spraying fan angle of the nozzles is controlled to be 50°.

[0012] Specifically, the spraying device includes a movable crossbeam, and the nozzles are arranged on the movable crossbeam, and the movable crossbeam moves along the length direction of the roll to spray the roll surface.

[0013] Specifically, the spraying device includes a fixed crossbeam, and multiple nozzles are arranged on the fixed crossbeam to spray the roll surface.

[0014] Specifically, the spacing of the distribution of the nozzles is controlled to be 79 mm.

[0015] Specifically, the horizontal distance between the plumb line of the injection nozzle and the plumb line of the roll surface on the inlet side of the support roll is controlled to be 251 ± 15 mm.

[0016] Specifically, an injection device is arranged on the inlet side of the rolling mill to inject leveling liquid with a certain pressure onto the surfaces of the intermediate roll and the support roll, so as to inhibit the generation of a negative pressure zone on the surfaces of the intermediate roll and the support roll or change the negative pressure zone into a positive pressure zone.

[0017] Specifically, an injection device is arranged on the inlet side of the rolling mill to inject a liquid-gas mixture of compressed air and leveling liquid with a certain pressure onto the surfaces of the intermediate roll and the support roll, so as to inhibit the generation of a negative pressure zone on the surfaces of the intermediate roll and the support roll or change the negative pressure zone into a positive pressure zone.

[0018] Through on-site investigation and analysis, the inventor found that when the four-high and six-high skin pass mills in Liuzhou Iron and Steel Cold Rolling Plant were designed, there was only leveling liquid injection at the work roll gap, and its main function was to inject leveling liquid to lubricate the rolls and clean the strip surface. The raw material of the flattened strip is a steel coil after bell-type annealing. There is no surface cleaning process such as degreasing before the steel coil enters annealing or skin passing. To a certain extent, there are carbon deposits on the surface of the strip after annealing (trace amounts in the continuous annealing and galvanizing units). When the skin pass mill is rolling, only the leveling liquid injection at the work roll gap cannot effectively wash away the carbon deposits. The residual part of the carbon deposits after being injected with the leveling liquid will be replicated onto the surface of the work roll, and then onto the surfaces of the upper intermediate roll and the upper support roll (this does not occur for the lower intermediate roll and the lower support roll because all the leveling liquid injected in the rack flows downward and passes through the surfaces of the lower rolls and then enters the pit, and the liquid volume passing through each surface of the lower rolls is sufficient). During the high-speed rotation of the rolls, according to the "Bernoulli principle", a local negative pressure zone will be formed in the middle of the roll length direction relative to both ends, and the dirt accumulated on the roll surface will gather towards the negative pressure zone. The dirt in the negative pressure zone on the work roll surface is replicated to the intermediate roll and the support roll. When the dirt on the surfaces of the intermediate roll and the support roll in the negative pressure zone accumulates to a certain extent and is not cleaned, it will in turn be replicated onto the work roll surface. With the continuous increase and continuous occurrence of the dirt amount, the leveling liquid injection ability of the work roll is not sufficient to clean these accumulated residual dirt from the work roll surface, and the dirt will be replicated onto the strip surface again, resulting in multiple irregular stains in the middle of the strip width direction, and ultimately leading to the degradation of the surface quality of the flattened strip.

[0019] The present invention suppresses the negative pressure zone formed in the middle region of the roll length direction due to the "Bernoulli principle" during the high-speed rotation of the roll by spraying liquid and blowing air on the surfaces of the intermediate roll and the backup roll. The present invention manufactures a special spraying and cleaning device for the dirt on the surface of the backup roll according to the space on the inlet side of the rolling mill stand. The spraying liquid takes the tempering liquid from the main tempering liquid pipeline. The spraying beam of the backup roll has a certain spraying angle with the rolling horizontal line, and there are requirements for the number and distribution distance of the nozzles, so as to ensure that the tempering liquid sprayed by the nozzles can cover and spray onto the surface area of the upper backup roll at a certain angle. Under the action of the spraying pressure, the generation of the negative pressure zone is suppressed, and the dirt on the surface of the backup roll is blown and washed away by means of the tempering liquid to prevent the accumulation of dirt. The opening button of the spraying liquid is implanted in the first-level computer screen for the operator to operate, and it can realize automatic spraying and manual spraying switching when needed according to the change of the unit speed.

[0020] The beneficial effects are as follows: At present, the method for removing dirt on the intermediate roll and backup roll of this temper mill and the spraying device can effectively suppress the negative pressure zone formed during the high-speed rotation of the roll in the stand in the cold rolling strip mills with widths of 1550mm, 1450mm, and 1250mm, the temper mills in the continuous annealing units, and the temper mills in the galvanizing units, achieving the effect of avoiding the accumulation of dirt, thereby eliminating the dirt defects on the surface quality of the strip steel. According to the spraying liquid method and the on-site actual situation, the designed spraying beam can effectively spray the tempering liquid onto the surface area of the upper backup roll at a predetermined angle and spraying pressure. Under the action of the spraying pressure, the tempering liquid blows and washes away the dirt on the surface of the backup roll to prevent the accumulation of dirt, effectively solving the problem of irregular multiple stripes often appearing in the middle of the strip steel surface in the width direction after tempering by this temper mill, and eliminating the problem of the degradation of the surface quality of the strip steel after tempering caused by this defect. The method for removing dirt on the intermediate roll and backup roll of this temper mill and the spraying device are simple and easy to implement, with strong replicability, creating considerable economic benefits. Brief Description of the Drawings

[0021] Figure 1 is a schematic structural diagram of the spraying beam provided by an embodiment of the present invention;

[0022] Figure 2 is a schematic working layout diagram of the spraying device provided by an embodiment of the present invention;

[0023] Figure 3 is a schematic structural diagram of the first embodiment of the spraying beam provided by an embodiment of the present invention.

[0024] Explanation of the reference numerals in the drawings:

[0025] 1. First ball valve; 2. Solenoid valve; 3. Second ball valve; 4. Stainless steel pipe; 5. High-pressure rubber hose; 6. Spraying beam; 7. Spraying nozzle; 11. Upper backup roll; 12. Upper work roll; 13. Lower work roll; 14. Lower backup roll. Detailed Embodiment

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0027] During the high-speed rotation of the rolls of a four-high (six-high) temper mill, a negative pressure area is formed in the middle region of the roll length direction due to the "Bernoulli principle". It is necessary to suppress the Bernoulli negative pressure effect.

[0028] In the embodiments of the present invention, as Figure 1 , a method for suppressing the Bernoulli negative pressure effect in the high-speed rotation area of the rolls of a cold rolling temper mill is provided, including the following steps:

[0029] A spraying device is arranged on the inlet side of the rolling mill stand;

[0030] The spraying direction of the spraying device forms a certain angle with the horizontal line of strip rolling;

[0031] Gas and / or liquid with a certain pressure is sprayed onto the surfaces of the intermediate roll and the backup roll through the nozzles of the spraying device, so that the air pressure in each section area of the surfaces of the intermediate roll and the backup roll is balanced. The effect of avoiding the accumulation of dirt is achieved, thereby eliminating the dirt defects on the strip surface quality.

[0032] Gas and / or liquid with a certain pressure is sprayed onto the surfaces of the upper backup roll 11 and the upper work roll 12 through the nozzles of the spraying device, so that the air pressure in each section area of the surfaces of the intermediate roll and the backup roll is balanced, and the accumulation of dirt is avoided.

[0033] The spraying device includes a spraying beam 6, on which a plurality of nozzles 7 are distributed. An inlet end is opened in the middle of the spraying beam 6 and is butted with a high-pressure rubber hose 5. The high-pressure rubber hose 5 is connected to a stainless steel pipe 4. The stainless steel pipe 4 is in an L shape. A first ball valve 1, an electromagnetic valve 2, and a second ball valve 3 are sequentially arranged on the stainless steel pipe 4 along the spraying direction.

[0034] Make fixed brackets for the ends of the support roll spray beams on both sides of the housing inside the frame to install and fix the fabricated spray beams. The length of the spray beam is c, and the support roll spray beam with c being 1788 mm, material: SS304, nominal diameter: φ38 mm. Open a flatting liquid inlet end in the middle of the beam, the connector nominal diameter: M24×1.5, thread length 25 mm, total length of the connector: 50 mm, for docking with a standard high-pressure rubber hose (model: 13ⅠH-1500). On the side opposite to the flatting liquid inlet end of the beam, evenly distribute the liquid outlet ends of the flatting liquid nozzles at 79 mm intervals, the end nominal diameter: DN10, for connecting to a standard nozzle (spray nozzle), model of a certain factory: H1 / 8VV-SS304-5002, basic technical parameters: thread G1 / 8, equivalent spray hole diameter 0.91 mm, flow rate 0 - 1.0 L / min, spray angle δ is 50°.

[0035] Lead out a hard pipe for the flatting liquid outlet from the main flatting liquid pipe, and successively connect on the hard pipe: ball valve - solenoid valve - ball valve - rubber hose - flatting liquid inlet end of the support roll spray beam. Ball valve model: Q11F-16P, solenoid valve model: ZCZP-25S.

[0036] Connect a flexible hose to the flatting liquid inlet end of the support roll spray beam, for the purpose of unrestricted subsequent adjustment of the spray beam angle. One end of the flexible hose is connected to the flatting liquid inlet end of the support roll spray beam, and the other end is connected to the hard pipe led out from the main flatting liquid pipe, with the maximum pressure of the main flatting liquid pipe being 4.0 bar.

[0037] The spraying device is provided with multiple spray nozzles distributed at equal distances. Control the spacing d between the distributions of the spray nozzles, and d is 79 mm. As Figure 3 shown, the spraying length of the spraying device is b, and b can be 1550 mm, 1450 mm, 1250 mm.

[0038] Make the angle β between the spray nozzles of the spraying device and the direction of the rolling strip steel be 30° - 35°, and the preferred angle β is 30°.

[0039] There is an overlapping part in the spraying coverage areas of adjacent spray nozzles, and the spraying fan angle δ of the spray nozzles is controlled to be 50°.

[0040] The spraying device includes a movable cross beam, and the spray nozzles are arranged on the movable cross beam. The movable cross beam moves along the length direction of the roll to spray the roll surface.

[0041] The spraying device includes a fixed cross beam, and multiple spray nozzles are arranged on the fixed cross beam to spray the roll surface.

[0042] Control the horizontal distance a between the plumb line of the spray nozzle and the plumb line of the roll surface on the inlet side of the support roll to be a, and a is 251 ± 15 mm.

[0043] An injection device is arranged on the entrance side of the rolling mill to inject leveling liquid with a certain pressure onto the surfaces of the intermediate roll and the backup roll, suppressing the generation of a negative pressure area on the surfaces of the intermediate roll and the backup roll or changing the negative pressure area into a positive pressure area, achieving the effect of avoiding dirt accumulation, and thus eliminating the dirt defects on the strip surface quality.

[0044] An injection device is arranged on the entrance side of the rolling mill to inject a liquid-gas mixture of compressed air and leveling liquid with a certain pressure onto the surfaces of the intermediate roll and the backup roll, suppressing the generation of a negative pressure area on the surfaces of the intermediate roll and the backup roll or changing the negative pressure area into a positive pressure area, achieving the effect of avoiding dirt accumulation, and thus eliminating the dirt defects on the strip surface quality.

[0045] The technical solution of the present invention is as follows:

[0046] The application method is: Compile an automatic / manual injection program for the backup roll injection and implant it into the rolling program system. A switching button for the backup roll injection mode: automatic / manual mode is developed and set on the main screen of the first-level leveling liquid system during rolling. A backup roll injection start button is newly added on the operation console.

[0047] When in the automatic function, it is realized that: after selecting the backup roll injection mode as the automatic mode on the system screen, when the rolling mill unit speed is greater than 0.8 m / s during rolling (variable and adjustable by the main operator console as required), the solenoid valve on the backup roll injection branch of the leveling liquid system opens and closes after 40 seconds (variable and adjustable by the main operator console as required). Considering the problem of controlling the leveling liquid residue, during the tailing speed reduction section, the program automatically identifies that the rolling speed enters the tailing section, and the automatic injection function is not automatically put into operation. When in the manual function, it is realized that: according to the production status requirements, when using manual injection, after selecting the backup roll injection mode as the manual mode on the system screen, press the newly added backup roll injection start button on the operation console, and the leveling liquid is injected and stops when pressed again.

[0048] At present, this method for removing stains from the intermediate roll and the backup roll of the temper mill and the injection device can effectively suppress the negative pressure area formed when the rolls rotate at high speed in the stand in cold rolling strip mills with widths of 1550 mm, 1450 mm, and 1250 mm, temper mills in continuous annealing units, and temper mills in galvanizing units, achieving the effect of avoiding dirt accumulation, and thus eliminating the dirt defects on the strip surface quality. The injection beam designed according to the liquid injection method and the on-site actual situation can effectively inject the leveling liquid onto the surface area of the upper backup roll at a predetermined angle and injection pressure. Under the action of the injection pressure, the leveling liquid blows and washes away the stains on the backup roll surface, preventing the accumulation of dirt, effectively solving the problem of irregular multiple stripes often appearing in the middle of the strip surface width direction after tempering by the temper mill, and eliminating the problem of the strip surface quality degradation caused by this defect. This method for removing stains from the intermediate roll and the backup roll of the temper mill and the injection device are simple and easy to implement, have strong replicability, and create considerable economic benefits.

[0049] Example 1:

[0050] In the present invention, as Figure 2 , during the high-speed rotation of the rolls of a four-high (six-high) skin pass mill, due to the "Bernoulli principle", a negative pressure zone is formed in the middle region in the roll length direction. Therefore, the following technical measures are taken in the present invention:

[0051] The angle between the spray nozzle of the spraying device and the direction of the rolled strip is β, and β is controlled to be 30° to 35°, and the preferred angle β is 30°. There is an overlapping part in the spray coverage area of adjacent spray nozzles, and the spray fan angle δ of the spray nozzle is controlled to be 50°.

[0052] 1. Install intermediate roll and backup roll liquid spraying devices (spraying devices) on the entrance side of the rolling mill. Generally, skin pass liquid is used as the liquid. During the production process, a liquid with a certain pressure is sprayed onto the surfaces of the intermediate roll and the backup roll to increase the ability to lubricate and clean the roll surface. At the same time, it mainly makes the air pressure in each section area of the surfaces of the intermediate roll and the backup roll relatively balanced, so as to suppress the negative pressure zone or change the negative pressure zone into a positive pressure zone, which is beneficial to the discharge of dirt, prevent the accumulation of dirt, and thus achieve the purpose of eliminating stain replication.

[0053] 2. Install intermediate roll and backup roll liquid-gas mixed purging devices (spraying devices) on the entrance side of the rolling mill. Generally, compressed air is used as the gas and skin pass liquid is used as the liquid. During the production process, a liquid-gas mixture with a certain pressure is sprayed onto the surfaces of the intermediate roll and the backup roll. While further lubricating and cleaning the roll surface, it mainly makes the air pressure in each section area of the surfaces of the intermediate roll and the backup roll relatively balanced, so as to suppress the generation of the negative pressure zone or change the negative pressure zone into a positive pressure zone, which is beneficial to the discharge of dirt, prevent the accumulation of dirt, and thus achieve the effect of eliminating stain replication.

[0054] 3. Install intermediate roll and backup roll purging devices (spraying devices) on the entrance side of the rolling mill. Generally, compressed air is used as the gas. During the production process, a gas with a certain pressure is sprayed onto the surfaces of the intermediate roll and the backup roll, making the air pressure in each section area of the surfaces of the intermediate roll and the backup roll relatively balanced, so as to suppress the generation of the negative pressure zone or change the negative pressure zone into a positive pressure zone, which is beneficial to the discharge of dirt, prevent the accumulation of dirt, and thus achieve the effect of eliminating stain replication.

[0055] 4. The above-mentioned liquid spraying, air blowing or liquid-gas mixed spraying devices can be a fixed number of nozzles carried by a cross beam in a fixed manner at a certain angle and distance, and spray (purge) onto the roll surface according to the spraying (purging) frequency; or it can be a fixed number of nozzles carried by a beam in a movable manner at a certain angle and distance, and move in the roll length direction according to the spraying (purging) frequency to spray (purge) the roll surface.

[0056] Example 2:

[0057] The technical solution provided by the present invention is as follows: By spraying liquid and blowing air on the surfaces of the intermediate roll and the backup roll, a negative pressure area formed in the middle area of the roll in the length direction during the high-speed rotation of the roll due to the "Bernoulli principle" is suppressed.

[0058] According to the space on the inlet side of the mill stand, a special spraying and cleaning device (spraying device) for the dirt on the surface of the backup roll is manufactured. The spraying liquid takes the tempering liquid from the main tempering liquid pipeline. The backup roll spraying beam has a certain spraying angle with the rolling horizontal line, and there are requirements for the number and distribution distance of the nozzles, so as to ensure that the tempering liquid sprayed out by the nozzles can cover and spray onto the surface area of the upper backup roll at a certain angle. Under the action of the spraying pressure, the generation of the negative pressure area is suppressed, and with the help of the tempering liquid, the dirt on the surface of the backup roll is blown and washed away to prevent the accumulation of dirt. The opening button of the spraying liquid is implanted in the first-level computer screen for the operator to operate, and it can realize automatic spraying and manual spraying switching when needed according to the change of the unit speed.

[0059] At present, the method for removing dirt from the intermediate roll and the backup roll of this temper mill and the spraying device can effectively suppress the negative pressure area formed during the high-speed rotation of the rolls in the mill stand in the cold rolling strip mills with widths of 1550mm, 1450mm, and 1250mm, the temper mills in the continuous annealing units, and the temper mills in the galvanizing units, achieving the effect of avoiding the accumulation of dirt, thereby eliminating the dirt defects on the surface quality of the strip steel. According to the spraying liquid method and the actual situation on site, the spraying beam is designed, and the tempering liquid sprayed out can effectively spray onto the surface area of the upper backup roll at a predetermined angle and spraying pressure. Under the action of the spraying pressure, the dirt on the surface of the backup roll is blown and washed away to prevent the accumulation of dirt, effectively solving the problem of irregular multi-strip dirt often appearing in the middle of the strip steel surface in the width direction after tempering by the temper mill, and eliminating the problem of the degradation of the surface quality of the strip steel after tempering caused by this defect. The method for removing dirt from the intermediate roll and the backup roll of this temper mill and the spraying device are simple and easy to implement, with strong replicability, creating considerable economic benefits.

[0060] The above are only schematic specific embodiments of the present invention and are not intended to limit the scope of the present invention. The various components of the present invention can be combined with each other under the condition of no conflict. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. Method for suppressing Bernoulli negative pressure effect in high-speed rotating area of cold rolling temper mill rolls, characterized in that, Including the following steps: Install a spraying device on the entrance side of the rolling mill housing; Make the spraying direction of the spraying device have a certain angle with the horizontal line of strip rolling; Spray gas and / or liquid with a certain pressure onto the surfaces of the upper intermediate roll and the upper backup roll through the nozzles of the spraying device, so that the air pressure in each section area of the surfaces of the upper intermediate roll and the upper backup roll is balanced, to suppress the negative pressure area or make the negative pressure area become a positive pressure area, which is beneficial to the discharge of dirt and prevent the accumulation of dirt; The spraying device is provided with a plurality of equally spaced nozzles, and the angle between the nozzles of the spraying device and the direction of the rolling strip is 30°-35°; There is an overlapping part in the spraying coverage area of adjacent nozzles, and the spraying fan angle of the nozzles is controlled to be 50°; The horizontal distance between the plumb line of the nozzle and the plumb line of the roll surface on the entrance side of the upper backup roll is controlled to be 251±15mm.

2. The method for suppressing the Bernoulli negative pressure effect in the high-speed rotation area of the rolls of a cold rolling temper mill according to claim 1, characterized in that The spraying device includes a movable crossbeam, and the nozzles are arranged on the movable crossbeam. The movable crossbeam moves along the length direction of the roll to spray the roll surface.

3. The method for suppressing the Bernoulli negative pressure effect in the high-speed rotation area of the rolls of a cold rolling temper mill according to claim 1, characterized in that The spraying device includes a fixed crossbeam, and a plurality of nozzles are arranged on the fixed crossbeam to spray the roll surface.

4. The method for suppressing the Bernoulli negative pressure effect in the high-speed rotation area of the rolls of a cold rolling temper mill according to claim 2, characterized in that, Control the spacing of the nozzle distribution to be 79mm.

Images