A method for controlling the positioning of a slab in a furnace entry

Abstract

The application discloses a control method for slab positioning in a heating furnace. Three laser range finders are arranged in sequence along the positive direction of a furnace roller way on the same side of a pusher. The deceleration control process of the furnace roller way is started by the detection signal of the first laser range finder, and the automatic positioning of the slab is realized by the detection signals of the second and third laser range finders. The method can achieve the same positioning precision for cold slabs and bent slabs as for hot slabs, thereby avoiding the phenomenon of scraping the burner of the furnace wall, shortening the slab entering time, and saving the cost.

Description

Technical Field

[0001] This invention relates to the field of automatic control technology for steel rolling, and in particular to a control method for positioning slabs entering a heating furnace. Background Technology

[0002] In recent years, many steel mills have built two or even three heating furnaces in hot rolling mills to increase output. To improve the steel output rhythm and achieve automatic alternating feeding of slabs into the furnace, the positioning of slabs on the roller conveyor before entering the furnace is crucial. For hot slabs, which are very straight, a hot detection system can be used to delay the operation of the feeding roller conveyor, thus achieving positioning accuracy within 5 cm. However, for cold slabs or slabs that are alternately placed in the middle of the roller conveyor, the billet curvature and friction conditions are different, resulting in sudden changes in the speed of the slab on the roller conveyor. This causes the positioning accuracy to exceed the effective range. In cases where the width of some slabs is close to the width of the furnace door, the thermal expansion of the billet inevitably causes some scraping against the furnace burners. Calculating the slab position by measuring the slab speed with a laser velocimeter is very costly. If a hot and cold metal detector is installed, transmitting and receiving equipment needs to be installed on both sides of the roller conveyor. Since the temperature near the furnace door is relatively high, it increases the difficulty of maintenance. In addition, the slab vibrates a lot on the roller conveyor, causing the receiving and transmitting equipment to deviate.

[0003] Therefore, there is an urgent need for a control method for positioning the slabs entering the heating furnace, which can automatically position the slabs to achieve the same positioning accuracy as the hot slabs, thereby avoiding the phenomenon of scraping the furnace wall burners and shortening the slab entry time. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the purpose of this invention is to provide a control method for positioning slabs entering a heating furnace, which can automatically position the slabs and achieve the same positioning accuracy for cold and bent slabs as for hot slabs, thereby avoiding the phenomenon of scraping the furnace wall burners and shortening the slab entry time.

[0005] This invention provides a control method for positioning slabs entering a heating furnace. A conveyor roller conveyor and an entry roller conveyor are sequentially arranged in front of the heating furnace. The heating furnace and a pusher are respectively located on opposite sides of the entry roller conveyor. A first laser rangefinder, a second laser rangefinder, and a third laser rangefinder are sequentially arranged on the same side of the pusher along the forward running direction of the entry roller conveyor. The control method includes the following steps:

[0006] Step 1: When none of the first, second, and third laser rangefinders detect anything, the conveyor rollers and furnace entry rollers run forward at the initial speed v1.

[0007] Step 2: When the first laser rangefinder detects the slab, the conveyor rollers and furnace entry rollers begin to decelerate. When the furnace entry rollers decelerate to the target speed v2, automatic slab positioning begins.

[0008] Step 3: When neither the second nor the third laser rangefinder detects anything, the travel distance of the slab on the furnace feed roller is precisely controlled by controlling the time t1 when the motor speed is set to v2 and the time t2 when the motor speed is set to 0.

[0009] Step 4: If the first laser rangefinder and the second laser rangefinder detect the slab, but the third laser rangefinder does not, and the speed of the furnace roller conveyor is 0 for 200ms to 500ms, the automatic positioning of the slab is completed, and the process jumps to step 8.

[0010] Step 5: If the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder all detect the entry rollers and the speed of the entry rollers remains at 0 for 200ms to 500ms, control the entry rollers to run in reverse.

[0011] Step 6: By controlling the time t1 when the motor speed is set to v2 and the time t2 when the motor speed is set to 0, the reverse travel distance of the slab on the furnace feed roller is precisely controlled. When the first laser rangefinder and the second laser rangefinder detect the slab, but the third laser rangefinder does not detect it, and the speed of the furnace feed roller is 0 for 200ms to 500ms, the slab is automatically positioned and the process jumps to step 8.

[0012] Step 7: When neither the second nor the third laser rangefinder detects anything, control the furnace feed roller conveyor to run in the forward direction and jump to step 3.

[0013] Step 8: The steel pusher begins its steel pushing sequence;

[0014] Step 9: The pusher sequence is completed and the pusher leaves the furnace feed roller conveyor and retracts into position, then jump to step 1.

[0015] Furthermore, the installation positions of the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder are more than 10m away from the edge of the furnace inlet roller conveyor.

[0016] Furthermore, the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder are sequentially installed along the forward running direction of the furnace feed roller conveyor, and the specific installation requirements are as follows:

[0017] To ensure that the slab does not scrape against the furnace wall burner after thermal expansion, the third laser rangefinder is positioned horizontally behind the burner and the distance between the third laser rangefinder and the burner is less than 5cm; the distance between the second and third laser rangefinders is less than 10cm; and the distance between the first and second laser rangefinders is less than 50cm.

[0018] Furthermore, the distance between the first laser rangefinder and the second laser rangefinder is 10cm to 40cm.

[0019] Furthermore, the target velocity v2 is equal to 0.2 to 0.5 times the initial velocity v1.

[0020] Furthermore, the times t1 and t2 in steps 3 and 6 satisfy the following relationship: t1>T1, t2>T2; where T1 is the motor starting process time and T2 is the motor braking and stopping time.

[0021] Furthermore, along the running direction of the conveyor rollers, there are multiple heating furnaces, steel pushers, and furnace feed rollers connected in sequence. Except for the last heating furnace, the other heating furnaces are equipped with three laser rangefinders to achieve automatic slab positioning. The last heating furnace is positioned by setting a baffle at the end of the furnace feed roller.

[0022] This invention discloses a control method for positioning slabs entering a heating furnace. Three laser rangefinders are sequentially installed on the same side of the pusher along the forward running direction of the furnace feed roller conveyor. The deceleration control process of the feed roller conveyor is initiated by the detection signal from the first laser rangefinder, and the automatic positioning of the slab is achieved by the detection signals from the second and third laser rangefinders. This method can achieve the same positioning accuracy for cold and bent slabs as for hot slabs, thereby avoiding the phenomenon of scraping against the furnace wall burners and shortening the slab feeding time. Furthermore, the laser rangefinders are inexpensive and easy to install, saving costs. Attached Figure Description

[0023] Figure 1 This is a flowchart of a control method for positioning a slab entering a heating furnace according to the present invention;

[0024] Figure 2 This is a partial schematic diagram of the furnace feed area in the present invention. Detailed Implementation

[0025] like Figure 1 As shown, this invention provides a control method for positioning slabs entering a heating furnace. A conveyor roller conveyor and an entry roller conveyor are sequentially arranged in front of the heating furnace. The heating furnace and a pusher are respectively located on opposite sides of the entry roller conveyor. A first laser rangefinder D1, a second laser rangefinder D2, and a third laser rangefinder D3 are sequentially arranged on the same side of the pusher along the forward running direction of the entry roller conveyor. Figure 2 As shown. The control method includes the following steps:

[0026] Step 1: When none of the first, second, and third laser rangefinders detect anything, the conveyor rollers and furnace entry rollers run forward at the initial speed v1.

[0027] In practice, the installation positions of the first, second, and third laser rangefinders are greater than 10 meters from the edge of the furnace feed roller conveyor. The first, second, and third laser rangefinders are sequentially installed along the forward running direction of the furnace feed roller conveyor, and the specific installation requirements are as follows:

[0028] To ensure that the slab does not scrape against the furnace wall burner after thermal expansion, the third laser rangefinder is positioned horizontally behind the burner and the distance between the third laser rangefinder and the burner is less than 5cm; the distance between the second and third laser rangefinders is less than 10cm; and the distance between the first and second laser rangefinders is less than 50cm, preferably between 10cm and 40cm, to ensure that the slab can decelerate to the target speed without delaying the slab positioning time.

[0029] Step 2: When the first laser rangefinder detects the slab, the conveyor rollers and furnace entry rollers begin to decelerate. When the furnace entry rollers decelerate to the target speed v2, automatic slab positioning begins.

[0030] In practice, the target speed v2 is equal to 0.2 to 0.5 times the initial speed v1, where v1 is 1 to 2 m / s.

[0031] Step 3: When neither the second nor the third laser rangefinder detects anything, the travel distance of the slab on the furnace feed roller is precisely controlled by controlling the time t1 when the motor speed is set to v2 and the time t2 when the motor speed is set to 0.

[0032] Step 4: If the first laser rangefinder and the second laser rangefinder detect the slab, but the third laser rangefinder does not, and the speed of the furnace roller conveyor is 0 for 200ms to 500ms, the automatic positioning of the slab is completed, and the process jumps to step 8.

[0033] Step 5: If the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder all detect the furnace, and the speed of the furnace feed roller is 0 for 200ms to 500ms, control the furnace feed roller to run in reverse.

[0034] Step 6: By controlling the time t1 when the motor speed is set to v2 and the time t2 when the motor speed is set to 0, the reverse travel distance of the slab on the furnace feed roller is precisely controlled. When the first laser rangefinder and the second laser rangefinder detect the slab, but the third laser rangefinder does not detect it, and the speed of the furnace feed roller is 0 for 200ms to 500ms, the slab is automatically positioned and the process jumps to step 8.

[0035] In specific implementation, the times t1 and t2 in steps 3 and 6 satisfy the following relationship: t1>T1, t2>T2; where T1 is the motor starting process time and T2 is the motor braking and stopping time.

[0036] Step 7: When neither the second nor the third laser rangefinder detects anything, control the furnace feed roller conveyor to run in the forward direction and jump to step 3.

[0037] Step 8: The steel pusher begins the steel pushing sequence.

[0038] Step 9: The pusher sequence is completed and the pusher leaves the furnace feed roller conveyor and retracts into position, then jump to step 1.

[0039] The direction of the furnace door is defined as forward, and the direction away from the furnace door is defined as backward. The forward position is the position inside the furnace where the steel billet is placed into the furnace by the steel pusher, and the backward position is the position where the steel pusher is completely away from the top of the furnace entry roller. The position is determined according to the site conditions.

[0040] In practice, multiple heating furnaces, steel pushers, and furnace feed rollers can be installed along the direction of the conveyor rollers. Except for the last heating furnace, the other heating furnaces are equipped with three laser rangefinders to achieve automatic slab positioning. The last heating furnace is positioned by setting a baffle at the end of the furnace feed roller.

[0041] The above description is only a preferred embodiment of the present invention and is not intended to limit the ideas of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A control method for positioning slabs entering a heating furnace, wherein a conveyor roller conveyor and an entry roller conveyor are sequentially arranged in front of the heating furnace, and the heating furnace and a pusher are respectively arranged on both sides of the entry roller conveyor, characterized in that, A first laser rangefinder, a second laser rangefinder, and a third laser rangefinder are sequentially installed on the same side of the steel pusher along the forward running direction of the furnace feed roller conveyor. The control method includes the following steps: Step 1: When none of the first, second, and third laser rangefinders detect anything, the conveyor rollers and furnace entry rollers operate at the initial set speed. v 1. Running in the forward direction; Step 2: When the first laser rangefinder detects the slab, the conveyor rollers and furnace feed rollers begin to decelerate. The furnace feed rollers decelerate until they reach the target speed. v Automatic slab positioning begins at 2 o'clock; Step 3: When neither the second nor the third laser rangefinder detects anything, the motor speed is controlled to a set value. v 2 times t 1 and the time when the motor speed is given to 0 t 2. Precisely control the travel distance of the slab on the furnace feed roller conveyor; Step 4: If the first laser rangefinder and the second laser rangefinder detect the slab, but the third laser rangefinder does not, and the speed of the furnace roller conveyor is 0 for 200ms to 500ms, the automatic positioning of the slab is completed, and the process jumps to step 8. Step 5: If the first laser rangefinder, the second laser rangefinder, and the third laser rangefinder all detect the entry rollers and the speed of the entry rollers remains at 0 for 200ms to 500ms, control the entry rollers to run in reverse. Step 6: Set the motor speed to... v 2 times t 1 and the time when the motor speed is given to 0 t 2. Precisely control the reverse travel distance of the slab on the furnace feed roller conveyor. When the first laser rangefinder and the second laser rangefinder detect it, but the third laser rangefinder does not detect it, and the furnace feed roller conveyor speed is 0 for 200ms~500ms, the slab automatic positioning is completed, and the process jumps to step 8. Step 7: When neither the second nor the third laser rangefinder detects anything, control the furnace feed roller conveyor to run in the forward direction and jump to step 3. Step 8: The steel pusher begins its steel pushing sequence; Step 9: The pusher sequence is completed and the pusher leaves the furnace feed roller conveyor and retracts into position, then jump to step 1.

2. The control method for positioning the slab entering the heating furnace as described in claim 1, characterized in that, The installation positions of the first, second, and third laser rangefinders are more than 10m away from the edge of the furnace roller conveyor.

3. The control method for positioning the slab entering the heating furnace as described in claim 1, characterized in that, The first, second, and third laser rangefinders are sequentially installed along the forward running direction of the furnace feed roller conveyor. Specific installation requirements are as follows: To ensure that the slab does not scrape against the furnace wall burner after thermal expansion, the third laser rangefinder is positioned horizontally behind the burner and the distance between the third laser rangefinder and the burner is less than 5cm; the distance between the second and third laser rangefinders is less than 10cm; and the distance between the first and second laser rangefinders is less than 50cm.

4. The control method for positioning the slab entering the heating furnace as described in claim 3, characterized in that, The distance between the first laser rangefinder and the second laser rangefinder is 10cm to 40cm.

5. The control method for positioning the slab entering the heating furnace as described in claim 1, characterized in that, Target speed v 2 equals 0.2 to 0.5 times the initial velocity. v 1.

6. The control method for positioning the slab entering the heating furnace as described in claim 1, characterized in that, The time in steps 3 and 6 t 1 and t 2. Satisfy the following relationship: t 1> T 1, t 2> T 2; of which T 1 represents the motor start-up time. T 2 represents the motor braking stopping time.

7. The control method for positioning the slab entering the heating furnace as described in claim 1, characterized in that, Along the direction of the conveyor rollers, there are also multiple heating furnaces, steel pushers, and furnace feed rollers connected in sequence. Except for the last heating furnace, the other heating furnaces are equipped with three laser rangefinders to achieve automatic slab positioning. The last heating furnace is positioned by setting a baffle at the end of the furnace feed roller.

Images