For the surfacing repair work of rolls, many rolling mills are generally commissioned by the surfacing factory. However, due to the shortcomings of entrusted processing, such as many intermediate links, long repair cycle and high cost, these rolling mills need to increase the inventory of roll spare parts to ensure production. How to simplify the roll repair surfacing process and reduce the cost is a meaningful research topic. We will introduce our approach below.
First, the implementation of short process surfacing repair process
The short process surfacing repair process has the characteristics of short repair cycle, less surfacing process and high repair efficiency. The specific approach is as follows.
1. Use the equipment of the roller assembly workshop to set up a small surfacing station in the workshop to avoid problems in the turnover process.
2. The application of surfacing and heat treatment integrated roll surfacing device is carried out for repair. Figure 1 shows the appearance of the device. Its working principle is the basic structure and function of the integrated surfacing machine and the heat treatment furnace, so that the three processes of preheating, surfacing and heat treatment in the roll surfacing process are concentrated. The process is as follows.
(1) Before the overlay welding, the front furnace body and the rear furnace body of the surfacing device are separated along the track. A journal protection ring is mounted on the workpiece, and the workpiece is hoisted to the roller frame (the workpiece roll can be continuously rotated on the wheel frame by the transmission); the separated furnace body is closed and fixed, and the main body of the roller is enclosed in the furnace. It is required that the gap between the through hole and the roll neck at both ends of the furnace body be as small as possible (about 5 mm) to improve the sealing property of the furnace; the weld cover is plugged with the furnace cover; and the electric heater is slowly preheated by the electric current.
(2) During surfacing, the front lower furnace body is de-energized and moved forward along the track; the lower lower furnace body is de-energized and properly moved backward; the furnace cover plugged in the surfacing tank is removed; the welding head enters the surfacing tank Surfacing welding is performed on the rolls. During the surfacing process, the front upper and lower upper furnaces are always energized to ensure the interlayer temperature of the roll surfacing.
(3) The method of interlayer heat treatment or final heat treatment is the same as that of preheating, and the heat treatment procedure is set as required. After the final heat treatment, the rolls were slowly cooled to room temperature. The furnace body is further separated along the track, and the rolls are hoisted to the lathe and the grinding machine for processing, and the entire surfacing repair process is completed.
3. Application practice.
Meishan Iron & Steel Co., Ltd. began to independently develop roll surfacing equipment and surfacing welding technology in 1998. In August 2002, a roll surfacing station was set up in the grinding roll assembly workshop of the company's hot rolling mill. The stacking and heat treatment integrated roll surfacing device was used for the φ1280mm rough rolling work roll, φ1 380mm support roll, φ1 380mm. The VSB large vertical roller was repaired by surfacing and was very successful. Fig. 2 is a photograph of the scene of the φ1280mm rough rolling work roll of the integrated roll surfacing device of Meishan Iron and Steel Co., Ltd. The main technical parameters of the device are as follows.
Top platform size: front platform 4 200 × 2 000mm, rear platform 4 200 × 3 000mm;
Furnace size: φ1 700 × 2 700mm;
Furnace lining material and thickness: B type high aluminum silicate refractory fiber thickness 160~200mm;
Rated temperature, voltage, power: 700 ° C, 380 V, 300 k W (adjustable);
Electric heating element connection: 10 Y-shaped connections, three in front of the furnace and three in the upper part, two in front of the furnace and two in the lower part.
The rotational power of the roller and the traveling mechanism of the welding trolley use variable frequency speed regulation. The surfacing method adopts double head, filament and spiral automatic submerged arc welding. Due to the high temperature of the surfacing groove and the large distance between the surfacing platform and the roll surface, the welding head has been structurally improved (Fig. 3) to ensure welding stability and operability.
The integrated roll surfacing device has the basic functions of a surfacing machine and a heat treatment furnace. It requires only about 30% of a surfacing machine, a set of interlayer insulation equipment, and a trolley type heat treatment furnace. It has the advantages of combined structure, compact structure, full fiber lining, tracked far-infrared ceramic sheet electric heating, multi-point independent temperature control, wide furnace top working platform, less equipment occupation, and investment saving. In the roll surfacing repair, only two liftings are required before and after the process, and the process is extremely simple.
Second, the effect
Using short-flow surfacing repair method, two DZ1250 submerged arc welding machines and two improved surfacing heads are used for surfacing welding. It takes only 20 days to repair a φ1280mm rough rolling work roll, which is less than the external surfacing welding. 1 month.
Meishan short-process surfacing repair roll process is unique among domestic iron and steel enterprises, leading technology, won the bronze medal of the 15th National Invention Exhibition, Shanghai 2005 Excellent Utility Model Patent Award and other honors.
First, the implementation of short process surfacing repair process
The short process surfacing repair process has the characteristics of short repair cycle, less surfacing process and high repair efficiency. The specific approach is as follows.
1. Use the equipment of the roller assembly workshop to set up a small surfacing station in the workshop to avoid problems in the turnover process.
2. The application of surfacing and heat treatment integrated roll surfacing device is carried out for repair. Figure 1 shows the appearance of the device. Its working principle is the basic structure and function of the integrated surfacing machine and the heat treatment furnace, so that the three processes of preheating, surfacing and heat treatment in the roll surfacing process are concentrated. The process is as follows.
(1) Before the overlay welding, the front furnace body and the rear furnace body of the surfacing device are separated along the track. A journal protection ring is mounted on the workpiece, and the workpiece is hoisted to the roller frame (the workpiece roll can be continuously rotated on the wheel frame by the transmission); the separated furnace body is closed and fixed, and the main body of the roller is enclosed in the furnace. It is required that the gap between the through hole and the roll neck at both ends of the furnace body be as small as possible (about 5 mm) to improve the sealing property of the furnace; the weld cover is plugged with the furnace cover; and the electric heater is slowly preheated by the electric current.
(2) During surfacing, the front lower furnace body is de-energized and moved forward along the track; the lower lower furnace body is de-energized and properly moved backward; the furnace cover plugged in the surfacing tank is removed; the welding head enters the surfacing tank Surfacing welding is performed on the rolls. During the surfacing process, the front upper and lower upper furnaces are always energized to ensure the interlayer temperature of the roll surfacing.
(3) The method of interlayer heat treatment or final heat treatment is the same as that of preheating, and the heat treatment procedure is set as required. After the final heat treatment, the rolls were slowly cooled to room temperature. The furnace body is further separated along the track, and the rolls are hoisted to the lathe and the grinding machine for processing, and the entire surfacing repair process is completed.
3. Application practice.
Meishan Iron & Steel Co., Ltd. began to independently develop roll surfacing equipment and surfacing welding technology in 1998. In August 2002, a roll surfacing station was set up in the grinding roll assembly workshop of the company's hot rolling mill. The stacking and heat treatment integrated roll surfacing device was used for the φ1280mm rough rolling work roll, φ1 380mm support roll, φ1 380mm. The VSB large vertical roller was repaired by surfacing and was very successful. Fig. 2 is a photograph of the scene of the φ1280mm rough rolling work roll of the integrated roll surfacing device of Meishan Iron and Steel Co., Ltd. The main technical parameters of the device are as follows.
Top platform size: front platform 4 200 × 2 000mm, rear platform 4 200 × 3 000mm;
Furnace size: φ1 700 × 2 700mm;
Furnace lining material and thickness: B type high aluminum silicate refractory fiber thickness 160~200mm;
Rated temperature, voltage, power: 700 ° C, 380 V, 300 k W (adjustable);
Electric heating element connection: 10 Y-shaped connections, three in front of the furnace and three in the upper part, two in front of the furnace and two in the lower part.
The rotational power of the roller and the traveling mechanism of the welding trolley use variable frequency speed regulation. The surfacing method adopts double head, filament and spiral automatic submerged arc welding. Due to the high temperature of the surfacing groove and the large distance between the surfacing platform and the roll surface, the welding head has been structurally improved (Fig. 3) to ensure welding stability and operability.
The integrated roll surfacing device has the basic functions of a surfacing machine and a heat treatment furnace. It requires only about 30% of a surfacing machine, a set of interlayer insulation equipment, and a trolley type heat treatment furnace. It has the advantages of combined structure, compact structure, full fiber lining, tracked far-infrared ceramic sheet electric heating, multi-point independent temperature control, wide furnace top working platform, less equipment occupation, and investment saving. In the roll surfacing repair, only two liftings are required before and after the process, and the process is extremely simple.
Second, the effect
Using short-flow surfacing repair method, two DZ1250 submerged arc welding machines and two improved surfacing heads are used for surfacing welding. It takes only 20 days to repair a φ1280mm rough rolling work roll, which is less than the external surfacing welding. 1 month.
Meishan short-process surfacing repair roll process is unique among domestic iron and steel enterprises, leading technology, won the bronze medal of the 15th National Invention Exhibition, Shanghai 2005 Excellent Utility Model Patent Award and other honors.
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