Control method of hot rolling and rough rolling descaling system

Abstract

The invention particularly relates to a control method of a hot rolling and rough rolling descaling system, and belongs to the technical field of hydraulic descaling for the surface of a workpiece connected with a metal rolling mill. According to the method, judgment is carried out through a descaling water consumption function to find the time te when the frequency of a descaling pump in the hot rolling and rough rolling descaling system is reduced to stop water supply, and then the descaling water consumption amount b between the time te when the frequency of the descaling pump is reduced to stop water supply and a period time T is calculated; and judging according to the descaling water consumption amount b and the water supplementing amount S of the energy accumulator, and obtaining the time when the different descaling pumps start to supply water again at the normal frequency according to different judgment results. By means of the method, the appropriate water supply reducing and stopping time period of the descaling pump can be accurately found out, the descaling water pumped out by the descaling pump meets the slab descaling requirement and is not wasted at the same time, and the waste problem caused by surplus descaling water in the prior art is avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to a control method of a hot roughing descaling system, and belongs to the technical field of hydraulic descaling for workpiece surface used in connection with a metal rolling mill (B21B45 / 08). BACKGROUND

[0002] At present, the hot descaling system is gradually developing from a roughing and finishing shared descaling system to a roughing and finishing separated and nearby arrangement direction, so as to reduce the pressure loss caused by long distance transmission. The existing separated hot roughing descaling system comprises a hot roughing descaling machine, an accumulator and a roughing descaling control device; wherein the hot roughing descaling machine mainly comprises a descaling pump, a descaling motor and the like. The descaling pump and the motor are matched, and the descaling pump model is determined, and then the corresponding motor is matched. The accumulator is used to store the high-pressure descaling water by using the gap without descaling on site. When the descaling is carried out on site, the stored high-pressure water is used as the supplement of the descaling pump, so as to maintain the stability of the pressure. The roughing descaling water consumption is in a pulse mode, and the average consumption level is not high, but the stage consumption is large. Before the slab enters the hot roughing descaling machine, the roughing descaling control device calculates the flow and descaling time period of each descaling point in the hot roughing descaling machine according to the specification of the slab. When the normal production is carried out, the descaling capacity of the descaling pump is configured to work in the maximum power all the time.

[0003] Most of the descaling points on the existing hot roughing descaling machine generally require a flow less than the rated flow of the descaling pump, and only a small part of the descaling points require a flow greater than the rated flow of the descaling pump in the descaling time period. The accumulator can provide additional high-pressure water for the small part of the descaling points to supplement, so as to meet the flow requirement of the descaling point in the descaling time period. Since the descaling pump is always working in the rated flow all the time, the descaling water pumped out of the other descaling points except the descaling point is excessive, and the excessive water is received and stored by the accumulator. However, the volume of the accumulator is limited, and the excessive water exceeding the volume of the accumulator can only be discharged, which causes a lot of energy waste. SUMMARY

[0004] The technical problem to be solved by the present application is how to reduce the excessive water pumped out of the descaling pump.

[0005] The technical solution provided by the present application is a control method of a hot roughing descaling system, wherein the hot roughing descaling system comprises a hot roughing descaling machine, an accumulator and a roughing descaling control device, the hot roughing descaling machine comprises a descaling pump and a variable frequency motor, and the method comprises the following steps:

[0006] Step 1: Set up m descaling points sequentially, from the first descaling point to the second descaling point up to the mth descaling point; where m is a natural number greater than 2; define the slab travel time t as the slab travels within the hot rolling roughing descaling mill; define the time between the head of the i-th slab reaching the first descaling point and the head of the (i+1)-th slab reaching the first descaling point as the slab entry cycle time T of the i-th slab entering the hot rolling roughing descaling mill. i The i is a natural number greater than or equal to 1 and less than or equal to n;

[0007] Based on the specifications of the n slabs to be descaled, calculate sequentially the first estimated descaling flow rate Q1 and the first estimated descaling start time for the n slabs at the first descaling point. and the first expected end time of descaling The second estimated descaling flow rate Q2 at the second descaling point, and the second estimated descaling start time. Second expected end time of descaling The expected descaling flow rate Q to the m-th descaling point m The estimated start time of descaling for the mth time. and the expected end time of descaling for the mth time The n is a natural number greater than or equal to 1;

[0008] The first estimated start time for descaling By the first expected end time of descaling The time period between these points is defined as the first expected descaling time period. The first estimated end time of descaling By the second expected start time of descaling The time period between these points is defined as the first expected non-descaling time period. Repeat the above definition process to define the second expected descaling time period in sequence. Expected descaling time up to the mth period Second expected non-descaling period The expected non-descaling period up to the m-1th time period

[0009] The estimated descaling flow rates of the first slab over m estimated descaling time periods and m-1 estimated non-descaling time periods are collected to form the first estimated descaling flow rate function Q. 1 (T c ,T f As shown in equation (1),

[0010]

[0011] Repeat the above steps to sequentially form the second expected descaling water flow function Q for the second slab. 2 (T c ,Tf ) to the nth slab in the nth predicted descaling water flow function Q n (T c , T f ) ;

[0012] According to the first predicted descaling water flow function Q 1 (T c , T f ) to the nth predicted descaling water flow function Q n (T c , T f ), the first descaling water consumption function f 1 (T1) of the first slab in the slab entry period time T1 of the first slab is calculated in turn, and the nth descaling water consumption function f n (T n ) of the nth slab in the slab entry period time Tn of the nth slab is calculated in turn.

[0013] Step 2: When the i-th slab is ready to be descaled by the hot roughing descaling machine, the descaling pump supplies water at a normal frequency when the slab walking time t of the i-th slab is 0 in the slab entry period time T i of the i-th slab.

[0014] When the descaling water consumption function f i (T i ) of the i-th slab first satisfies the following formula (2), the time is recorded as the time t e at which the descaling pump stops supplying water at a reduced frequency.

[0015] f i (T i ) < c * k1 (2)

[0016] In formula (2), c is the rated flow of the descaling pump, k1 is the first flow coefficient, and is an empirical value.

[0017] When the slab walking time t of the i-th slab is equal to the time t e at which the descaling pump stops supplying water at a reduced frequency, the descaling pump stops supplying water at a reduced frequency, and the predicted descaling water consumption b in the remaining time of the descaling pump in the slab entry period time T i of the i-th slab is calculated according to the following formula (3),

[0018]

[0019] Step 3: The slab walking time t of the i-th slab is equal to the time t e at which the descaling pump stops supplying water at a reduced frequency.The replenishment amount S of the accumulator is calculated, and the time t at which the descaling pump starts to supply water at the normal frequency is calculated according to the following formula (4) w ,

[0020] t w = T i -(k2*(S max -S+b)) / c (4)

[0021] In formula (4), k2 is a second flow coefficient, which is an empirical value; S max is the maximum replenishment amount of the accumulator;

[0022] When the slab running time t of the i-th slab is equal to the time t at which the descaling pump starts to supply water at the normal frequency w , the descaling pump starts to supply water at the normal frequency again.

[0023] Further, the control method of the hot roughing descaling system further comprises the following steps:

[0024] Step 4: The consumption time t of the accumulator is calculated according to the following formula (5) n

[0025]

[0026] When the replenishment amount S of the accumulator and the consumption time t of the accumulator n both satisfy the requirement of the following formula (6), the time at which the descaling pump is restarted is changed from t w in step 3 to

[0027]

[0028] In formula (6), is a first time allowance, which is an empirical value; t0 is the maximum replenishment time of the accumulator;

[0029] When the slab running time t of the i-th slab is equal to , the descaling pump starts to supply water at the normal frequency again.

[0030] Beneficial effects: The method in the present application finds the time t at which the descaling pump of the hot roughing descaling system stops supplying water at the reduced frequency through the descaling water consumption function f(T) e , and then calculates the time t at which the descaling pump stops supplying water at the reduced frequency eThe descaling water consumption b during a given cycle time T is determined based on the descaling water consumption b and the replenishment water S of the accumulator. Different determination results lead to different times when the descaling pump resumes water supply at its normal frequency. The method of this invention accurately identifies the appropriate time period for reducing or stopping water supply from the descaling pump, ensuring that the descaling water pumped meets the descaling requirements of the slab without waste, thus avoiding the waste problem caused by excess descaling water in existing technologies. Detailed Implementation

[0031] The control method of a hot-rolled roughing descaling system of the present invention will be further described below with reference to specific embodiments.

[0032] Example 1

[0033] This embodiment discloses a control method for a hot-rolled roughing descaling system. The hot-rolled roughing descaling system includes a hot-rolled roughing descaling machine, an accumulator, and a roughing descaling control device. The hot-rolled roughing descaling machine includes a descaling pump and a variable frequency motor. The method includes the following steps:

[0034] Step 1: Sequentially set up m descaling points on the hot rolling roughing descaling mill, from the first descaling point to the second descaling point, up to the mth descaling point; m is a natural number greater than 2. Define the slab travel time t as the slab moves within the hot rolling roughing descaling mill. Define the time between the head of the i-th slab reaching the first descaling point and the head of the (i+1)-th slab reaching the first descaling point as the slab entry cycle time T of the i-th slab entering the hot rolling roughing descaling mill. i i is a natural number greater than or equal to 1 and less than or equal to n;

[0035] The roughing descaling control device calculates the first estimated descaling flow rate Q1 and the first estimated descaling start time of the n slabs at the first descaling point according to the specifications of the n slabs to be descaled. and the first expected end time of descaling The second estimated descaling flow rate Q2 at the second descaling point, and the second estimated descaling start time. Second expected end time of descaling The expected descaling flow rate Q to the m-th descaling point m The estimated start time of descaling for the mth time. and the expected end time of descaling for the mth time n is a natural number greater than or equal to 1;

[0036] The first estimated start time for descaling By the first expected end time of descaling The time period between these points is defined as the first expected descaling time period. The first estimated end time of descaling By the second expected start time of descaling The time period between these points is defined as the first expected non-descaling time period. Repeat the above definition process to define the second expected descaling time period in sequence. Expected descaling time up to the mth period Second expected non-descaling period The expected non-descaling period up to the m-1th time period

[0037] The estimated descaling flow rates of the first slab over m estimated descaling time periods and m-1 estimated non-descaling time periods are collected to form the first estimated descaling flow rate function Q. 1 (T c ,T f As shown in equation (1),

[0038]

[0039] Repeat the above steps to sequentially form the second expected descaling water flow function Q for the second slab. 2 (T c ,T f The expected descaling water flow rate function Q to the nth slab n (T c ,T f );

[0040] The roughing descaling control device is based on the first predicted descaling water flow function Q. 1 (T c ,T f The expected descaling flow rate function Q up to the nth digit n (T c ,T f ) Calculate the first descaling water consumption function f of the descaling pump during the first slab's entry cycle time T1. 1 (T1) The descaling water consumption function f of the descaling pump during its own slab entry cycle time Tn from the nth slab. n (T n );

[0041] Step 2: When the i-th slab is ready to enter the hot rolling roughing descaling mill, the slab enters the cycle time T of the i-th slab. i Inside, when the slab travel time t of the i-th slab is 0, the descaling pump supplies water at the normal frequency;

[0042] When the descaling water consumption function f of the i-th slab i (T i When equation (2) is satisfied for the first time, record this moment as the time t when the descaling pump stops supplying water at a reduced frequency. e ,

[0043] f i (T i )<c*k1 (2)

[0044] In equation (2), c is the rated flow rate of the descaling pump, and k1 is the first flow coefficient, which is an empirical value and ranges from 0.5 to 0.8.

[0045] When the slab travel time t of the i-th slab is equal to the time t when the descaling pump reduces its frequency and stops supplying water... e When the descaling pump reduces its frequency and stops supplying water, the descaling pump's cycle time T for the i-th slab is calculated according to the following formula (3). i The estimated descaling water consumption b during the remaining time within the period.

[0046]

[0047] Step 3: Collect the slab travel time t of the i-th slab, which is equal to the water supply stop time t when the descaling pump reduces its frequency. e The water replenishment amount S of the accumulator is calculated, and the time t when the descaling pump resumes water supply at the normal frequency is calculated according to the following formula (4). w ,

[0048] t w =T i -(k2*(S max -S+b)) / c (4)

[0049] In equation (4), k2 is the second flow coefficient, which is an empirical value. It mainly considers factors such as the decrease in efficiency of the accumulator and descaling pump, and its value ranges from 1.1 to 1.2; S max This is the maximum water replenishment capacity of the accumulator;

[0050] When the slab travel time t of the i-th slab is equal to the time t of restarting water supply at the normal frequency... w At that time, the descaling pump resumes water supply at the normal frequency.

[0051] The following example uses the roughing descaling process on the 1422 hot rolling production line. The roughing descaling pump has a rated pressure of 25 MPa and a flow rate of 320 m³ / h. 3 / h(0.0889 meters) 3 / second), the maximum water replenishment capacity of the accumulator Smax = 4.31 (m³) 3 Assuming that when rolling a 2.3*1013 SAE1017 slab with dimensions of 230*1060*92350, the slab's cycle time T1 = 120 seconds; the first flow coefficient k1 is 0.6; and the second flow coefficient k2 is 1.2.

[0052] Step 1: Set the first descaling point, the second descaling point to the seventh descaling point in sequence on the hot roughing descaling machine, and calculate the predicted descaling flow of the first slab at the seven descaling points, seven predicted descaling time periods T c and six predicted non-descaling time periods T f , as shown in Table 1 below,

[0053]

[0054] Table 1

[0055] Collect the predicted descaling flow of the first slab through the seven predicted descaling time periods and the six predicted non-descaling time periods to form a first predicted descaling water flow function Q 1 (T c ,T f ), and the roughing descaling control device calculates a first descaling water consumption function f 1 (T1) of the descaling pump for the first slab within its slab entry period time T1 according to the first predicted descaling water flow function Q c (T f ,T 1 ), as shown in the following formula,

[0056]

[0057] Step 2: When the first slab is ready to enter the hot roughing descaling machine, at the slab walking time t of the first slab equal to the start time tcj1 of the first non-descaling time period T f1 , i.e. t = 13 seconds, the first descaling water consumption function f 1 (T1) first satisfies formula (2),

[0058] f(t = Tf1 = 13) = 0 < c * k1 = 0.0889 * 0.6 = 0.533

[0059] The descaling pump reduces the frequency and stops supplying water, and at this time, the predicted descaling water consumption b of the descaling pump within the remaining time (i.e. [13, 120]) of the slab entry period time T1 is calculated according to formula (3),

[0060]

[0061] Step 3: Collect the replenishment amount S = 4.11 (m 3 ) of the accumulator when the slab walking time t of the first slab is equal to the stop water supply working time t e when the descaling pump stops supplying water at reduced frequency, and calculate the time t w when the descaling pump starts supplying water at normal frequency within the slab entry period time T1 of the first slab according to formula (4),

[0062] t w = T - (k2 * (S max + b)) / c = 120 - 1.2 (4.31 - 4.11 + 2.97) / 0.0889 = 77.2 seconds

[0063] When the first slab walking time t is equal to the moment of restart of the descaling pump t w = 77.2, the descaling pump continues to work with normal frequency water supply.

[0064] Example Two

[0065] The control method of the hot roughing descaling system in this embodiment further comprises the following steps on the basis of Example One:

[0066] Step 4: Calculate the consumption time t of the accumulator according to the following formula (5) n

[0067]

[0068] When the accumulator water supply amount S and the accumulator consumption time t n both meet the requirements of the following formula (6), the moment of restart of the descaling pump is changed from t w in Step 3 to

[0069]

[0070] In formula (6), is the first time allowance, which is an empirical value and mainly prevents insufficient water supply of the accumulator, and the value range is 2-10 seconds; t0 is the maximum water supply time of the accumulator;

[0071] When the slab walking time t of the i-th slab is equal to , the descaling pump is restarted with normal frequency water supply.

[0072] Taking the roughing descaling of the 1422 hot rolling production line as an example, the roughing descaling pump has a rated pressure of 25 MPa and a flow of 320 m 3 / h (0.0889 m 3 / s), the maximum water supply amount Smax of the accumulator is 4.31 (m 3 ), assuming that two slabs have specifications of 230*1060*92350 and 230*1250*9500, the first slab entering period time T1 is 90 seconds; the second slab entering period time T2 is 180 seconds; the value of the first flow coefficient k1 is 0.6; the value of the second flow coefficient k2 is 1.2; the first time allowance The value of the first predicted descaling time period T

[0073] Step 1: sequentially set the first descaling point, the second descaling point to the seventh descaling point in sequence on the hot roughing descaling machine, sequentially calculate the predicted descaling flow of the first slab at the seven descaling points, the seven predicted descaling time periods T c and six predicted non-descaling time periods T f As shown in Table 1 below,

[0074]

[0075]

[0076] Table 1

[0077] sequentially calculate the predicted descaling flow of the second slab at the seven descaling points, the seven predicted descaling time periods T c and six predicted non-descaling time periods T f As shown in Table 2 below,

[0078]

[0079]

[0080] Table 2

[0081] According to the data in Table 1, the predicted descaling flow of the first slab passing through the seven predicted descaling time periods and the six predicted non-descaling time periods is collected to form a first predicted descaling water flow function Q 1 (T c ,T f ), according to the data in Table 2, the predicted descaling flow of the second slab passing through the seven predicted descaling time periods and the six predicted non-descaling time periods is collected to form a second predicted descaling water flow function Q 2 (T c ,T f );

[0082] The roughing descaling control device calculates the second descaling water consumption function f 2 (T2) of the descaling pump of the second slab within the slab entry cycle time T2 of the second slab itself according to the first predicted descaling water flow function Q 1 (T c ,T f ), the second predicted descaling water flow function Q 2 (T c ,T f ), the slab entry cycle time T1 of the first slab and the slab entry cycle time T2 of the second slab, as shown in the following formula,

[0083]

[0084] Step 2: When the second slab is ready to enter the hot roughing descaling mill, at the slab running time t of the second slab equal to 14 seconds within the slab entry period time T2 of the second slab, the second descaling water consumption function f 2 (T2) first satisfies formula (2),

[0085] f 2 (T2=t=14)=0

[0086] The descaling pump stops supplying water at the reduced frequency, at which time the expected descaling water consumption b of the descaling pump within the remaining time (i.e., [14, 180]) of the slab entry period time T2 of the second slab is calculated according to formula (3),

[0087]

[0088] Step 3: The slab running time t of the second slab is collected at the stop supplying water working time t of the descaling pump stopping supplying water at the reduced frequency e The accumulator replenishment amount S=4.05 (m 3 The time t w of the descaling pump supplying water at the normal frequency within the slab entry period time T2 of the second slab is calculated according to formula (4), w t max =T2-(k2*(S

[0089] Step 4: The consumption time t n =62.6 of the accumulator within the slab entry period time T2 of the second slab is calculated according to formula (5),

[0090]

[0091] Since the accumulator replenishment amount S and the accumulator consumption time t n both satisfy the requirements of formula (6), the time of restarting the descaling pump changes from t w =59.86 seconds in Step 3 to

[0092]

[0093] When the slab running time t of the second slab is equal to , the descaling pump starts to supply water at the normal frequency.

Claims

1. A control method for a hot-rolled roughing descaling system, the hot-rolled roughing descaling system comprising a hot-rolled roughing descaling machine, an accumulator, and a roughing descaling control device, wherein the hot-rolled roughing descaling machine comprises a descaling pump and a variable frequency motor, characterized in that: Includes the following steps: Step 1: Set up m descaling points sequentially, from the first descaling point to the second descaling point up to the mth descaling point; where m is a natural number greater than 2; define the slab travel time t as the slab travels within the hot rolling roughing descaling mill; define the time between the head of the i-th slab reaching the first descaling point and the head of the (i+1)-th slab reaching the first descaling point as the slab entry cycle time T of the i-th slab entering the hot rolling roughing descaling mill. i The i is a natural number greater than or equal to 1 and less than or equal to n; Based on the specifications of the n slabs to be descaled, calculate sequentially the first estimated descaling flow rate Q1 and the first estimated descaling start time for the n slabs at the first descaling point. and the first expected end time of descaling The second estimated descaling flow rate Q2 at the second descaling point, and the second estimated descaling start time. Second expected end time of descaling The expected descaling flow rate Q to the m-th descaling point m The estimated start time of descaling for the mth time. and the expected end time of descaling for the mth time The n is a natural number greater than or equal to 1; The first estimated start time for descaling By the first expected end time of descaling The time period between these points is defined as the first expected descaling time period. The first estimated end time of descaling By the second expected start time of descaling The time period between these points is defined as the first expected non-descaling time period. Repeat the above definition process to define the second expected descaling time period in sequence. Expected descaling time up to the mth period Second expected non-descaling period The expected non-descaling period up to the m-1th time period The estimated descaling flow rates of the first slab over m estimated descaling time periods and m-1 estimated non-descaling time periods are collected to form the first estimated descaling flow rate function Q. 1 (T c ,T f As shown in equation (1), Repeat the above steps to sequentially form the second expected descaling water flow function Q for the second slab. 1 (T c ,T f The expected descaling water flow rate function Q to the nth slab n (T c ,T f ); Based on the first predicted descaling water flow function Q 1 (T c ,T f The expected descaling flow rate function Q up to the nth digit n (T c ,T f ) Calculate the first descaling water consumption function f of the descaling pump during the first slab's own slab entry cycle time T1. 1 (T1) The descaling water consumption function f of the descaling pump during its own slab entry cycle time Tn from the nth slab. n (T n ); Step 2: When the i-th slab is ready to be processed by the hot rolling roughing descaling mill, the slab enters the cycle time T of the i-th slab. i When the slab travel time t of the i-th slab is 0, the descaling pump supplies water at the normal frequency. When the descaling water consumption function f of the i-th slab i (T i When equation (2) is satisfied for the first time, this moment is recorded as the time t when the descaling pump stops supplying water at a reduced frequency. e , f i (T i )<c*k1 (2) In equation (2), c is the rated flow rate of the descaling pump, and k1 is the first flow coefficient, which is an empirical value; When the slab travel time t of the i-th slab is equal to the time t when the descaling pump stops supplying water at its reduced frequency e When the descaling pump reduces its frequency and stops supplying water, the descaling pump's cycle time T for the i-th slab is calculated according to the following formula (3). i The estimated descaling water consumption b during the remaining time within the period. Step 3: The slab travel time t of the i-th slab is equal to the water supply stop time t when the descaling pump reduces its frequency. e The amount of water replenished to the accumulator, S, is calculated, and the time t at which the descaling pump resumes water supply at the normal frequency is calculated according to the following formula (4). w , t w =T i -(k2*(S max -S+b)) / c (4) In equation (4), k2 is the second flow coefficient, which is an empirical value; S max This is the maximum water replenishment capacity of the accumulator; When the slab travel time t of the i-th slab is equal to the time t of resuming water supply at the normal frequency. w At that time, the descaling pump resumes water supply at the normal frequency.

2. The control method for the hot rolling roughing descaling system according to claim 1, characterized in that: It also includes the following steps: Step 4: Calculate the energy consumption time t of the accumulator according to the following formula (5). n When the water replenishment amount S of the accumulator and the consumption time t of the accumulator n When all requirements of equation (6) are met, the restart time of the descaling pump is determined by t in step 3. w Become In equation (6), It's the initial margin of safety, and it's based on experience. t0 is the maximum water replenishment time of the accumulator; When the slab movement time t of the i-th slab is equal to At that time, the descaling pump restarts and supplies water at the normal frequency.

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