Surfacing repair device for large Cr5 steel hot-rolled supporting roll

Abstract

The utility model belongs to the technical field of roller repairing, and particularly relates to a large Cr5 steel hot rolling supporting roller surfacing repairing device, which comprises a multi-head submerged arc welding machine and a supporting roller supporting seat, and is characterized in that three welding guns are arranged along the same advancing line and synchronously move, a heat preservation cover is arranged on the supporting roller supporting seat and is of a box-shaped structure with an upper cover and a lower cover, and the upper cover and the lower cover are arranged on the supporting roller supporting seat. A plurality of cover plates are symmetrically arranged on the top of the upper box cover in the axial direction of the supporting roller, each cover plate is connected with the upper box cover through a bayonet, and a heating plate is arranged in the lower box body along the inner wall. And the multi-head submerged arc welding gun performs reciprocating welding according to the same advancing line, and the surfacing sequences of every two adjacent surfacing layers are opposite. Compared with the prior art, the multi-head welding machine has the advantages that due to the surfacing sequence design of the multi-head welding machine, the number of arcing points and arcing stopping points is reduced, the defects of incomplete penetration of the arcing points, arc crater cracks, air holes and the like of the arcing stopping points are reduced, and the welding defects of a surfacing repairing layer of the hot rolling supporting roller are remarkably reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of roll repair, and particularly relates to a surfacing repair device for a large-sized hot-rolled support roll made of Cr5 steel. Background Art

[0002] To adapt to the development of hot-rolled strip mills towards large-scale, high-speed, and automated directions, the requirements for the working layer of the large support rolls used in the mills are getting higher and higher: relatively high (≥68HSD) and uniform hardness and microstructure, meeting uniform wear resistance, as well as corrosion resistance to high temperatures and lubricating or cooling media during the hot-rolling process; good toughness, meeting the anti-fatigue performance of withstanding high rolling forces and peak loads, and avoiding cracks and spalling on the working layer of the roll surface. Based on the above characteristic requirements, the forged steel material of the Cr5 alloy series has become the main choice for the support rolls of current hot-rolled strip mills. Cr5 steel is developed on the basis of Cr4 steel and is a new generation of steel for support rolls developed by increasing the Cr content and correspondingly adjusting other alloying elements, having better hardenability, wear resistance, and compressive strength and other comprehensive service performances.

[0003] China is the world's largest steel producer, with a large annual consumption of large-sized Cr5 forged steel support rolls. The surfacing repair of support rolls is of great significance. Currently, the research and application of the surfacing repair technology for large-sized hot-rolled support rolls are mainly in China. However, the domestic surfacing repair technology for large-sized hot-rolled support rolls mainly focuses on Cr3 and Cr4 steel support rolls, and the hardness of the surfacing layer is generally between 50 and 62HSD. Cr5 steel has a large carbon equivalent and poor weldability, and there are great difficulties in the surfacing repair technology for its Cr5 forged steel support rolls, and the quality stability of its repair layer is still difficult to guarantee.

[0004] The literature ("Research on the Technology of Multi-head Submerged Arc Surfacing for Hot-rolled Support Rolls", Master's Thesis of Northeastern University, 2019) discloses the multi-head surfacing sequence of hot-rolled support rolls, that is, evenly distributing four welding torches at four positions on the roll surface and welding in the order from left to right. This surfacing sequence will cause an increase in the number of starting points and stopping points of the arc. There are defects such as incomplete penetration at the starting point and arc pit cracks and pores at the stopping point. This surfacing sequence brings potential welding defects in the repair layer and is not conducive to ensuring the stability of the welding quality of the repair layer. Content of the Utility Model

[0005] The purpose of the utility model is to provide a surfacing repair device for a large-sized hot-rolled support roll made of Cr5 steel, overcoming the deficiencies of the prior art, adopting the surfacing sequence design of a multi-head welding machine, reducing the welding defects of the surfacing repair layer, improving the temperature retention performance during the surfacing process of the support roll, and further ensuring the stability of the welding quality of the repair layer.

[0006] To achieve the above purpose, the utility model is realized through the following technical solutions:

[0007] A surfacing repair device for a large-sized hot-rolled support roll made of Cr5 steel, comprising a multi-head submerged arc welding machine and a support roll support seat. The support roll support seat is located below the cross beam of the multi-head submerged arc welding machine. The multi-head submerged arc welding machine has three welding torches, and the three welding torches reciprocate along the cross beam under the drive of the multi-head submerged arc welding machine. A servo drive mechanism is provided on the support roll support seat, and the hot-rolled support roll rotates at the minimum pitch on the support roll support seat until a surfacing layer is formed on the entire surface of the support roll. It is characterized in that the three welding torches are arranged along the same travel route and move synchronously, and the distance between adjacent welding torches is 300-350 mm. A heat preservation cover is provided on the support roll support seat. The heat preservation cover is a box-shaped structure with upper and lower openable lids. Along the axial direction of the support roll, multiple cover plates are continuously arranged on the top of the upper box cover. Each cover plate is connected to the upper box cover through a bayonet. Along the inner wall of the lower box body, a heating plate is provided. On one side of the lower box body, a recovery port is provided, and a heat insulation sealing plate is provided at the recovery port. The bottom of the lower box body is inclined towards the recovery port.

[0008] Further, a handle is provided on the cover plate, and the cover plate can be opened or buckled through the handle.

[0009] Further, the width of the cover plate is 500-650 mm.

[0010] Further, the heating plate is an electric heating plate or a gas spray gun.

[0011] Further, the distance between the edges of the two end shoulders of the support roll and the inner wall of the heat preservation cover is ≥200 mm.

[0012] Further, the connection between the heat preservation cover and the support roll support seat is detachable.

[0013] Further, a rock wool heat preservation layer with a thickness of more than 50 mm is provided on the inner side of the cover plate.

[0014] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0015] 1) The present utility model adopts the surfacing sequence design of a multi-head welding machine and a reciprocating welding method, reducing the number of starting points and stopping points of the arc, thereby reducing the technical problem in the industry that there is incomplete penetration commonly existing at the starting point and there are defects such as crater cracks and pores at the stopping point, and significantly reducing the welding defects of the surfacing repair layer of the hot-rolled support roll.

[0016] 2) The heat preservation cover with a heat preservation function can be locally opened according to the position of the welding torch, maximizing the temperature retention performance of the support roll during the surfacing process, thereby achieving the purpose of further ensuring the welding quality stability of the repair layer. Description of the Drawings

[0017] Figure 1 is a schematic structural diagram of the first implementation state of the present utility model;

[0018] Figure 2 It is a schematic structural diagram of the second implementation state of the present utility model;

[0019] Figure 3 It is a schematic structural diagram of the insulation box in the utility model embodiment;

[0020] Figure 4 It is a schematic diagram of the state of the support roller in the lower box body in the utility model embodiment, and the upper box cover is not shown;

[0021] Figure 5 It is a schematic structural diagram of the cover plate installation in the utility model embodiment.

[0022] In the figure: 1 - submerged arc welding machine with multiple heads, 2 - support roller support seat, 3 - welding torch, 4 - cross beam, 5 - support roller, 6 - heat insulation cover, 7 - cover plate, 8 - bayonet, 9 - upper box cover, 10 - lower box body, 11 - heating plate, 12 - recovery port, 13 - handle. Specific implementation manners

[0023] Next, the technical solutions of the present utility model will be clearly and completely described in conjunction with specific embodiments. Obviously, the described embodiments are part of the embodiments of the present utility model, rather than all of the embodiments.

[0024] In order to more clearly illustrate the specific implementation manners of the present utility model or the technical solutions in the prior art, the specific embodiments required for use in the description of the specific implementation manners or the prior art will be briefly introduced below. Obviously, the specific embodiments described below are some implementation manners of the present utility model. For those of ordinary skill in the art, without creative efforts, other specific embodiments can also be obtained based on these specific embodiments.

[0025] Generally, the components of the embodiments of the present utility model described and shown in the specific embodiments here can be arranged and designed in countless different configurations. Therefore, the following detailed description of the embodiments of the present utility model provided in the specific embodiments is not intended to limit the scope of the claimed present utility model, but merely represents the selected embodiments of the present utility model.

[0026] See Figures 1-5, is a schematic structural diagram of an embodiment of a surfacing repair device for a large-sized hot-rolled support roll made of Cr5 steel of the present utility model, including a multi-head submerged arc welding machine 1 and a support roll support seat 2. The support roll support seat 2 is located below the cross beam 4 of the multi-head submerged arc welding machine 1. The multi-head submerged arc welding machine 1 has three welding torches 3, and the three welding torches 3 reciprocate along the cross beam 4 under the drive of the multi-head submerged arc welding machine 1; a servo drive mechanism is provided on the support roll support seat 2, and the servo motor drives the support roll 5 to rotate on the support roll support seat 2 through a toothed belt. The hot-rolled support roll 5 rotates and positions at the minimum pitch on the support roll support seat 2 until a surfacing layer is formed on the entire surface of the support roll 5. The three welding torches 3 are arranged along the same travel line and move synchronously, and the distance between adjacent welding torches 3 is 300 mm; a heat preservation cover 6 is provided on the support roll support seat 2. The heat preservation cover 6 is a box-shaped structure with upper and lower openable covers. Along the axial direction of the support roll 5, a plurality of cover plates 7 are continuously arranged on the top of the upper box cover 9. Each cover plate 7 is connected to the upper box cover 9 through a bayonet 8. A handle 13 is provided on the cover plate 7, and the cover plate can be opened or buckled through the handle 13. The width of the cover plate 7 is 650 mm.

[0027] During the surfacing process, the cover plate 7 at the corresponding position where the multi-head submerged arc welding torch 3 arrives is opened to expose the surfacing area, and the cover plates 7 at other positions are in the closed state. As the multi-head submerged arc welding torch 3 moves, the cover plates 7 can be opened or closed orderly according to needs, which can minimize heat dissipation to the greatest extent.

[0028] Heating plates 11 are provided along the inner wall of the lower box body 10. A recovery port 12 is provided on one side of the lower box body 10. A heat insulation sealing plate is provided at the recovery port 12. The bottom of the lower box body 10 is inclined towards the recovery port 12 to facilitate the recovery of the welding flux and slag shell.

[0029] The heating plate 11 is an electric heating plate or a gas spray gun, which can heat the inside of the heat preservation cover 6 during the surfacing process to maintain the temperature of the support roll from decreasing. A rock wool heat preservation layer with a thickness of more than 50 mm is provided on the inner side of the cover plate 7, which helps to further improve its heat preservation performance. The heat preservation cover 6 is detachably connected to the support roll support seat 2, and the heat preservation cover 6 can be removed for maintenance or cleaning.

[0030] The distance between the edges of the two ends of the roll shoulders of the support roll 5 and the inner wall of the heat preservation cover 6 is ≥200 mm, which ensures the uniformity of the temperature of the roll shoulders and the center area of the roll surface of the support roll 5, and avoids the hardening of the surfacing layer and the softening of the lap zone due to the too fast heat dissipation of the roll shoulders.

[0031] In the embodiment of the surfacing repair device for a large-sized hot-rolled support roll made of Cr5 steel of the present utility model, during the surfacing repair operation, the multi-head submerged arc welding torch 3 welds reciprocally along the same travel route. The surfacing machine head A starts arc at the left end of the roll surface and travels towards the right end of the roll surface for surfacing. After the head A travels a certain distance for surfacing, the head B starts arc at the left end position of the roll surface and travels towards the right end of the roll surface for surfacing. After the head B travels a certain distance for surfacing, the head C starts arc at the left end position of the roll surface and travels towards the right end of the roll surface for surfacing. After the multi-head submerged arc welding torch 3 reaches the other end of the support roll 5, it stops arc in sequence. The support roll 5 rotates by a indexing angle, and the multi-head submerged arc welding torch 3 moves reversely along the surface of the support roll 5 until the surfacing layer covers the entire roll surface. Repeat the above reciprocating operation until the thickness of the repair layer of the support roll 5 meets the requirements. This design of the surfacing sequence can reduce the welding starting points and stopping points, and reduce defects such as incomplete penetration at the starting points and crater cracks at the stopping points. To ensure the overall strength of the support roll, whenever the thickness of the surfacing layer reaches ~25 mm, stop welding and conduct a heat treatment at a temperature of 500 ± 10 °C for 10 - 16 h; when the thickness of the surfacing layer reaches the target value, stop welding and conduct a post-weld heat treatment at a temperature of 520 ± 10 °C for 20 - 24 h.

[0032] Although the embodiments of the present utility model have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present utility model. The scope of the present utility model is defined by the appended claims and their equivalents.

Claims

1. A Cr5 steel large hot-rolled support roller surfacing repair device, comprising a multi-head submerged arc welding machine and a support roller support seat, the support roller support seat is located below the crossbeam of the multi-head submerged arc welding machine, the multi-head submerged arc welding machine has three welding guns, and the three welding guns reciprocate along the crossbeam under the drive of the multi-head submerged arc welding machine; a servo transmission mechanism is provided on the support roller support seat, and the hot-rolled support roller rotates on the support roller support seat according to the minimum indexing until a surfacing layer is formed on the surface of the support roller, characterized in that: Three welding guns are arranged along the same travel route and move synchronously, and the spacing between adjacent welding guns is 300-350mm; a heat-insulating cover is provided on the support seat of the supporting roller, and the heat-insulating cover is a box-shaped structure with upper and lower covers. A plurality of cover plates are continuously arranged along the axial direction of the supporting roller on the top of the upper box cover, and each cover plate is connected to the upper box cover by a bayonet. A heating plate is provided on the inner wall along the inner side of the lower box body, and a recovery port is provided on one side of the lower box body, and a heat-insulating sealing plate is provided at the recovery port, and the bottom of the lower box body is inclined toward the recovery port.

2. The Cr5 steel large hot rolling support roller surfacing repair device according to claim 1 is characterized in that: The cover plate is provided with a handle, through which the cover plate can be opened or closed.

3. The Cr5 steel large hot rolling support roller surfacing repair device according to claim 1 is characterized in that: The width of the cover plate is 500-650 mm.

4. The Cr5 steel large hot rolling support roller surfacing repair device according to claim 1 is characterized in that: The heating plate is an electric heating plate or a gas spray gun.

5. The Cr5 steel large hot rolling support roller surfacing repair device according to claim 1 is characterized in that: The distance between the roller shoulder edges at both ends of the support roller and the inner wall of the heat preservation cover is ≥200mm.

6. The Cr5 steel large hot rolling support roller surfacing repair device according to claim 1 is characterized in that: The heat-insulating cover is detachably connected to the supporting roller support seat.

7. The Cr5 steel large hot rolling support roller surfacing repair device according to claim 1 is characterized in that: A rock wool insulation layer with a thickness of more than 50 mm is provided on the inner side of the cover plate.

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