A roll repair system and method

Abstract

A roller repairing system and method, comprising: an induction heating coil; a copper pipe having a through cooling channel inside, the two ends of the cooling channel extending to the outside of the induction heating coil and being connected with an external cooling liquid supply device through a connecting piece respectively; a refractory lining arranged outside the induction heating coil to form a cavity capable of accommodating an old roller, an annular gap being formed between the inner wall of the refractory lining and the outer wall of the old roller, and the annular gap being filled with alloy powder; and an alloy powder compaction unit comprising a ring plate and a plurality of nozzles, the nozzles being communicated with an external alloy powder conveying device through conveying pipes, and the ring plate being capable of moving up and down along the annular gap through a lifting unit. The ring plate of the present application can move smoothly in the gap, and the nozzles can spray alloy powder into the annular gap, solving the problems of uneven manual filling and insufficient density. Through layer-by-layer spraying and compaction, it is ensured that the alloy powder is highly dense and uniformly distributed before melting.

Description

Technical Field

[0001] This invention relates to the field of roll repair technology, specifically to a roll repair system and repair method. Background Technology

[0002] Rolls are critical large-scale workpieces in industries such as metallurgy and steel rolling. They operate under prolonged conditions of high temperature, high pressure, and abrasion, making their surfaces highly susceptible to defects such as fatigue cracks, spalling, and wear. To reduce production costs and extend roll service life, techniques such as welding, thermal spraying, and laser cladding are commonly used for roll repair. However, existing welding techniques result in large heat-affected zones, easily causing roll deformation or cracking; thermal spraying coatings have low bonding strength with the substrate and are prone to peeling; and laser cladding equipment is expensive and has low repair efficiency.

[0003] In recent years, the repair technology using induction heating combined with alloy powder has gradually attracted attention. This technology uses an induction coil to generate an alternating magnetic field, causing the surface of the roll and a pre-placed alloy powder layer to heat up and melt, forming a metallurgically bonded repair layer. However, in practical applications, the induction coils of existing induction heating repair devices require water cooling when operating in high-temperature environments, but the bond between the coil and the refractory material is often not tight enough, leading to heat loss or coil damage. Secondly, the filling of alloy powder is mostly done manually or by simple spraying, making it difficult to ensure that the powder is evenly distributed in the annular gaps, and the density of the powder layer is insufficient, which may lead to defects such as porosity and looseness after melting. Summary of the Invention

[0004] To address the technical problems existing in the background art, the present invention provides a roll repair system and repair method.

[0005] The technical solution of this invention is as follows: A roll repair system, comprising: The induction heating coil is made by winding a spiral copper tube. Both ends of the induction heating coil are electrically connected to an external power supply device. The inside of the copper tube is provided with a through cooling channel. Both ends of the cooling channel extend to the outside of the induction heating coil and are connected to an external coolant supply device through connectors. A refractory lining is provided on the outside of the induction heating coil to form a cavity that can accommodate the old roller. An annular gap is formed between the inner wall of the refractory lining and the outer wall of the old roller, and the annular gap is filled with alloy powder. The alloy powder compaction unit includes an annular plate and multiple nozzles, which are connected to an external alloy powder conveying device via conveying pipes. The thickness of the annular plate is adapted to the annular gap, and a lifting unit is provided on the outside of the annular plate, which can move up and down along the annular gap through the lifting unit. The annular plate has multiple mounting holes running through it along its axial direction. Multiple nozzles are installed in the mounting holes, with the nozzle openings facing downwards and located at the bottom of the mounting holes. The delivery pipe includes a rigid pipe and a flexible pipe that are connected to each other. The lower part of the rigid pipe is installed in the mounting hole and its lower end is connected to the nozzle. One end of the flexible pipe is connected to the alloy powder delivery device.

[0006] Preferably, two sets of lifting units are symmetrically arranged on the outer side of the refractory lining. Each lifting unit includes a lead screw and a nut that cooperates with it. The nut is connected to the annular plate for transmission.

[0007] To facilitate support of the rigid pipe, a reinforcing pipe is fitted on the outside of the rigid pipe section located above the annular plate. The reinforcing pipe is installed corresponding to the rigid pipe, and the upper parts of multiple reinforcing pipes are connected by an annular connecting plate.

[0008] Furthermore, connecting seats are symmetrically arranged on both sides of the outer side of the annular connecting plate, and connecting plates are connected to the connecting seats and connected to nuts.

[0009] The connecting seat is used to connect the connecting plate. After the alloy powder is sprayed from the nozzle, the angle of the annular plate can be manually rotated at a small angle to make the positions of each nozzle staggered, which facilitates the compaction of the alloy powder. Specifically, the connecting seat is an arc-shaped connecting seat. The outer side of the connecting seat has an arc-shaped adjustment groove that matches the curvature of the annular plate. The end of the connecting plate away from the nut is slidably set in the arc-shaped adjustment groove.

[0010] The specific structure of the annular plate is as follows: the annular plate includes a plate body and an annular pressure plate that can be detachably set on its lower end face. The annular pressure plate is coaxial with the plate body, and the mounting hole penetrates through the plate body and the annular pressure plate.

[0011] Furthermore, the lower end face of the nozzle is located within the plate body and is positioned close to the upper end face of the annular pressure plate.

[0012] Preferably, the two ends of the induction heating coil are electrically connected to the output end of the power supply device via flexible cables or conductive copper busbars.

[0013] To facilitate lifting of the steel pipe, the copper pipe has a rectangular cross-section, and the pitch of the induction heating coil is 5mm to 20mm.

[0014] A method for repairing a rolling mill roll, using a rolling mill roll repair system, includes the following steps: S1. The surface of the old roller to be repaired is machined to form a repair base surface; S2. The spiral copper tube is wound to form an induction heating coil, and refractory material is laid on the outside of the induction heating coil to form a refractory lining covering the outside of the induction heating coil. S3. Place the old roller inside the refractory lining using a hoisting device, so that an annular gap is formed between the inner wall of the refractory lining and the repair base surface of the old roller. S4. Alloy powder is filled into the annular gap through the alloy powder compaction unit; S41. Control the lifting unit to move the annular plate down to the preset position at the bottom of the annular gap, and control the alloy powder conveying device to spray alloy powder into the annular gap through the nozzle; S42. Close the nozzle and control the lifting unit to move the ring plate down to the preset height to compact the alloy powder; S43. Control the lifting unit to move the ring plate up to the preset height, rotate the ring plate to the preset small range angle, and open the nozzle to spray alloy powder into the annular gap; S44. Repeat steps S42 to S43 until the alloy powder fills the annular gaps. S5. Circulate coolant into the induction heating coil and simultaneously pass medium frequency current into the induction heating coil to generate an alternating magnetic field, which induction heats the alloy powder in the annular gap and the surface of the old roller, causing the alloy powder to melt and form a metallurgical bond with the repair base surface of the old roller. S6. Stop heating and wait for the old roll to cool down before reheating the repair layer to eliminate internal stress. S7. The old roller after reheat treatment is machined to achieve the preset size and surface finish.

[0015] The beneficial effects of this invention are as follows: The induction heating coil is made of copper tube with a rectangular cross section and has a through cooling channel inside. During operation, circulating coolant can be introduced to effectively remove the Joule heat generated by the coil itself and prevent the coil from overheating and being damaged. The refractory lining tightly covers the outside of the induction heating coil to form an integrated structure, which reduces the air gap caused by loose bonding in traditional structures. This allows the heat generated by the coil to be efficiently conducted to the rolls and alloy powder layer, reducing heat loss and local overheating problems. The thickness of the annular plate is matched with the annular gap, allowing it to move smoothly within the gap. Multiple nozzles are evenly distributed circumferentially, which can spray alloy powder into the annular gap, solving the problems of uneven filling and insufficient density in manual filling. Through layer-by-layer spraying and compaction, it is ensured that the alloy powder reaches a high degree of density and uniform distribution before melting. The arc-shaped adjustment groove on the connecting seat slides with the connecting plate, allowing for slight circumferential misalignment of the ring plate during single or multiple filling and compaction cycles through manual fine-tuning. This ensures that the starting positions of each spraying and compaction are staggered, reducing the compaction dead angles that may occur during fixed-position operations. Attached Figure Description

[0016] In the attached diagram: Figure 1 This is a structural diagram; Figure 2This is a top view; Figure 3 for Figure 2 A schematic diagram of the AA-direction cross-section structure; Figure 4 for Figure 3 Enlarged structural diagram at point A in the middle; Figure 5 This is a front view; Figure 6 This is a schematic diagram of the structure of the induction heating coil and the alloy powder compaction unit; The components represented by the various reference numerals in the diagram are: 1. Induction heating coil; 11. Water inlet pipe; 12. Water outlet pipe; 13. Conductive copper busbar; 2. Refractory lining; 3. Old roller; 4. Annular gap; 5. Alloy powder compaction unit; 51. Annular plate; 511. Plate body; 512. Mounting hole; 513. Annular pressure plate; 52. Nozzle; 53. Conveying pipe; 531. Rigid pipe; 532. Flexible hose; 6. Lifting unit; 61. Lead screw; 62. Nut; 7. Reinforcing pipe; 8. Annular connecting plate; 9. Connecting seat; 91. Arc-shaped adjusting groove; 10. Connecting plate. Detailed Implementation

[0017] Example 1 See Figure 1 , Figure 2 and Figure 5 As shown, a roll repair system includes an induction heating coil 1, a refractory lining 2, and an alloy powder compaction unit 5.

[0018] See Figure 3 and Figure 6 As shown, the induction heating coil 1 in this embodiment is formed by winding a spiral copper tube. The two ends of the induction heating coil 1 are electrically connected to an external power supply device, that is, the two ends of the induction heating coil 1 are electrically connected to the output end of the power supply device through a flexible cable or a conductive copper busbar 13. A through cooling channel is provided inside the copper tube. The two ends of the cooling channel are provided with a water inlet pipe 11 and a water outlet pipe 12. The water inlet pipe 11 and the water outlet pipe 12 extend to the outside of the induction heating coil 1. The water inlet pipe 11 and the water outlet pipe 12 are respectively connected to an external coolant supply device through connectors. A conductive copper busbar 13 is provided on the outside of both the water inlet pipe 11 and the water outlet pipe 12.

[0019] A refractory lining 2 is disposed on the outside of the induction heating coil 1, forming a cavity capable of accommodating the old roll. An annular gap 4 is formed between the inner wall of the refractory lining 2 and the outer wall of the old roll 3, and the annular gap 4 is filled with alloy powder. In this embodiment, the old roll 3 refers to the roll to be repaired.

[0020] See Figure 4As shown, the alloy powder compaction unit 5 includes an annular plate 51 and multiple nozzles 52. The nozzles 52 are connected to an external alloy powder conveying device through a conveying pipe 53. The conveying pipe 53 includes a rigid pipe 531 and a flexible pipe 532 that are connected to each other. The lower part of the rigid pipe 531 is installed in the mounting hole 512, and its lower end is connected to the nozzle 52. One end of the flexible pipe 532 is connected to the alloy powder conveying device.

[0021] It should be noted that the coolant supply device, alloy powder conveying device, and power supply device in this embodiment are all existing technologies and will not be described in detail. The alloy powder conveying device can be a precision powder feeder suitable for metal powders; the power supply device uses a medium-frequency induction heating power supply, such as the Puchuan Technology PI550-I series-3 or Invt MF100 series-9, which are commercially available products. This type of power supply has functions such as automatic frequency tracking, constant current and constant voltage control, and overcurrent and overvoltage protection, with an output frequency range covering 500Hz-10kHz, which can meet the process requirements of this system for induction heating of alloy powder and rolls.

[0022] The thickness of the annular plate 51 is adapted to the annular gap 4. A lifting unit 6 is provided on the outer side of the annular plate 51, and the annular plate 51 can move up and down along the annular gap 4 through the lifting unit 6. The annular plate 51 is provided with multiple mounting holes 512 through its axial direction, and multiple nozzles 52 are installed in the mounting holes 512 respectively. The nozzles 52 open downward and are located at the lower part of the mounting holes 512.

[0023] See Figure 1 and Figure 5 As shown, two sets of lifting units 6 are symmetrically arranged on the outer side of the refractory lining 2. Each lifting unit 6 includes a lead screw 61 and a nut 62 that cooperates with it. The nut 62 is connected to the annular plate 51 through a transmission connection. The annular plate 51 is driven to rise and fall by two sets of symmetrically arranged ball screws 61, which ensures the horizontality and smoothness of the annular plate 51 during its up and down movement.

[0024] See Figure 1 As shown, to facilitate support for the rigid pipe 531, a reinforcing pipe 7 is fitted around the outer side of the rigid pipe 531 section located above the annular plate 51. The reinforcing pipe 7 is correspondingly arranged with the rigid pipe 531, and the upper parts of multiple reinforcing pipes 7 are connected by an annular connecting plate 8. In this embodiment, the reinforcing pipe 7 enhances the bending stiffness of the rigid pipe 531, preventing bending deformation due to stress during long-term reciprocating lifting and lowering. The annular connecting plate 8 connects multiple reinforcing pipes 7 into a whole, further improving structural stability, ensuring synchronous movement of each nozzle 52, and guaranteeing uniformity of filling and compaction.

[0025] Connecting seats 9 are symmetrically arranged on both sides of the outer side of the annular connecting plate 8. Connecting plates 10 are connected to the connecting seats 9 and are connected to nuts 62. The connecting seats 9 are used to movably connect the connecting plates 10, so that after the alloy powder is sprayed from the nozzles 52, the angle of the annular plate 51 can be manually rotated at a small angle to make the positions of the nozzles 52 staggered, which facilitates the compaction of the alloy powder. Specifically, the connecting seats 9 are arc-shaped, and the outer side of the connecting seats 9 has an arc-shaped adjustment groove 91 that matches the curvature of the annular plate 51. The end of the connecting plate 10 away from the nut 62 is slidably set in the arc-shaped adjustment groove 91. It should be noted that during multiple filling and compaction processes, by manually adjusting the position of the connecting plates 10 in the arc-shaped adjustment groove 91, the annular plate 51 can rotate at a small angle relative to the previous spray position before each descent for compaction, thereby changing the circumferential position of the nozzles 52. This avoids uneven powder accumulation or compaction dead corners caused by spraying and compacting in the same position for a long time, and further improves the uniformity and density of the alloy powder distribution in the annular gap 4.

[0026] See Figure 4 and Figure 5 As shown, the annular plate 51 includes a plate body 511 and an annular pressure plate 513 detachably mounted on its lower end face. The annular pressure plate 513 is coaxial with the plate body 511, and the mounting hole 512 penetrates through the plate body 511 and the annular pressure plate 513. Adopting a split structure, the annular pressure plate 513, as the compaction working surface that directly contacts the alloy powder, is prone to wear during use. The detachable design facilitates the replacement of the annular pressure plate 513 separately without replacing the entire annular plate 51, reducing maintenance costs and downtime.

[0027] The lower end face of the nozzle 52 is located inside the plate body 511 and is positioned close to the upper end face of the annular pressure plate 513. This arrangement ensures that during the compaction process under the annular plate 51, the nozzle 52 will not come into contact with or be compressed against the already compacted alloy powder layer, preventing clogging or damage to the nozzle 52. Simultaneously, it guarantees that the lower end face of the annular plate 51 can be compacted as a complete plane, resulting in a flat and dense powder layer.

[0028] To increase the contact area between the copper tube and the refractory lining 2 and improve heat conduction efficiency, the copper tube has a rectangular cross-section. The pitch of the induction heating coil 1 is controlled within the range of 5-20mm. This ensures that the refractory material can fully fill the gaps between the turns, forming a tight, integrated structure, while avoiding heating blind spots in the magnetic field caused by excessive pitch. This ensures that the alloy powder within the annular gap 4 is heated uniformly, thereby obtaining a high-strength repair layer. Furthermore, the inner wall formed by the rectangular cross-section of the steel tube is relatively smoother than that of the circular cross-section of the copper tube.

[0029] Example 2 Based on the roll repair system in Example 1, this example provides a roll repair method, including the following steps: S1. The surface of the old roller 3 to be repaired is machined to form a repair base surface; S2. The spiral copper tube is wound to form an induction heating coil 1, and refractory material is laid on the outside of the induction heating coil 1 to form a refractory lining 2 covering the outside of the induction heating coil 1. S3. Place the old roller 3 inside the refractory lining 2 using a hoisting device, so that an annular gap 4 is formed between the inner wall of the refractory lining 2 and the repair base surface of the old roller 3. S4. Alloy powder is filled into the annular gap 4 through the alloy powder compaction unit 5. S41, control the lifting unit 6 to move the annular plate 51 down to the preset position at the bottom of the annular gap 4, and control the alloy powder conveying device to spray alloy powder into the annular gap 4 through the nozzle 52; S42. Close nozzle 52 and control lifting unit 6 to move ring plate 51 down to preset height to compact alloy powder; S43, control the lifting unit 6 to move the annular plate 51 to a preset height, rotate the annular plate 51 to a preset small range angle, and open the nozzle 52 to spray alloy powder into the annular gap 4; S44. Repeat steps S42 to S43 until the alloy powder fills the annular gap 4. Then, control the lifting unit to move the annular plate above the induction heating coil 1. The upper end of the annular gap can be covered by the cover plate. S5. Circulating coolant is introduced into the induction heating coil 1, and medium frequency current is introduced into the induction heating coil 1 at the same time to generate an alternating magnetic field, which induction heats the alloy powder in the annular gap 4 and the surface of the old roller 3, so that the alloy powder melts and forms a metallurgical bond with the repair base surface of the old roller 3. S6. Stop heating and wait for the old roll to cool down before reheating the repair layer to eliminate internal stress. S7. The old roller after reheat treatment is machined to achieve the preset size and surface finish.

Claims

1. A roll repair system, characterized in that, include: An induction heating coil (1) is formed by winding a spiral copper tube. The two ends of the induction heating coil (1) are electrically connected to an external power supply device. The copper tube has a through cooling channel inside. The two ends of the cooling channel extend to the outside of the induction heating coil (1) and are connected to an external coolant supply device through connectors. A refractory lining (2) is provided on the outside of the induction heating coil (1) to form a cavity that can accommodate the old roller. An annular gap (4) is formed between the inner wall of the refractory lining (2) and the outer wall of the old roller (3). The annular gap (4) is filled with alloy powder. The alloy powder compaction unit (5) includes an annular plate (51) and multiple nozzles (52), which are connected to an external alloy powder conveying device through a conveying pipe (53); The thickness of the annular plate (51) is adapted to the annular gap (4), and a lifting unit (6) is provided on the outside of the annular plate (51). The annular plate (51) can move up and down along the annular gap (4) through the lifting unit (6). The annular plate (51) is provided with multiple mounting holes (512) along its axial direction, and multiple nozzles (52) are installed in the mounting holes (512) respectively. The nozzles (52) open downward and are located at the lower part of the mounting holes (512). The conveying pipe (53) includes a rigid pipe (531) and a flexible pipe (532) that are connected to each other. The lower part of the rigid pipe (531) is installed in the mounting hole (512) and its lower end is connected to the nozzle (52). One end of the flexible pipe (532) is connected to the alloy powder conveying device.

2. The roll repair system according to claim 1, characterized in that, Two sets of lifting units (6) are symmetrically arranged on the outside of the fire-resistant lining (2). The lifting unit (6) includes a lead screw (61) and a nut (62) that cooperates with it. The nut (62) is connected to the annular plate (51) for transmission.

3. The roll repair system according to claim 1, characterized in that, A reinforcing tube (7) is sleeved on the outside of the rigid tube (531) located above the annular plate (51). The reinforcing tube (7) is arranged correspondingly to the rigid tube (531). The upper parts of multiple reinforcing tubes (7) are connected by an annular connecting plate (8).

4. The roll repair system according to claim 3, characterized in that, The annular connecting plate (8) has symmetrical connecting seats (9) on both sides of its outer side. A connecting plate (10) is connected to the connecting seat (9), and the connecting plate (10) is connected to the nut (62).

5. A roll repair system according to claim 4, characterized in that, The connecting seat (9) is an arc-shaped connecting seat (9). An arc-shaped adjustment groove (91) adapted to the curvature of the annular plate (51) is opened on the outer side of the connecting seat (9). The end of the connecting plate (10) away from the nut (62) is slidably disposed in the arc-shaped adjustment groove (91).

6. The roll repair system according to claim 1, characterized in that, The annular plate (51) includes a plate body (511) and an annular pressure plate (513) that is detachably disposed on its lower end face. The annular pressure plate (513) is coaxial with the plate body (511), and the mounting hole (512) penetrates the plate body (511) and the annular pressure plate (513).

7. A roll repair system according to claim 6, characterized in that, The lower end face of the nozzle (52) is located inside the plate body (511) and is positioned close to the upper end face of the annular pressure plate (513).

8. A roll repair system according to claim 1, characterized in that, The two ends of the induction heating coil (1) are electrically connected to the output end of the power supply device via a flexible cable or a conductive copper busbar (13).

9. A roll repair system according to claim 1, characterized in that, The copper tube has a rectangular cross-section, and the pitch of the induction heating coil (1) is 5 mm to 20 mm.

10. A method for repairing a rolling mill roll, using the rolling mill roll repair system according to any one of claims 1-9, characterized in that, The steps are as follows: S1. The surface of the old roller (3) to be repaired is machined to form a repair base surface; S2. The spiral copper tube is wound to form an induction heating coil (1), and refractory material is laid on the outside of the induction heating coil (1) to form a refractory lining (2) covering the outside of the induction heating coil (1). S3. Place the old roller (3) inside the refractory lining (2) using a hoisting device, so that an annular gap (4) is formed between the inner wall of the refractory lining (2) and the repair base surface of the old roller (3). S4. Alloy powder is filled into the annular gap (4) through the alloy powder compaction unit (5); S41, control the lifting unit (6) to move the ring plate (51) down to the preset position at the bottom of the annular gap (4), and control the alloy powder conveying device to spray alloy powder into the annular gap (4) through the nozzle (52); S42. Close the nozzle (52) and control the lifting unit (6) to move the ring plate (51) down to the preset height to compact the alloy powder; S43. Control the lifting unit (6) to move the ring plate (51) up to the preset height, rotate the ring plate (51) to the preset small range angle, open the nozzle (52) to spray alloy powder into the annular gap (4); S44. Repeat steps S42 to S43 until the alloy powder fills the annular gap (4). S5. Circulating coolant is introduced into the induction heating coil (1), and medium frequency current is introduced into the induction heating coil (1) to generate an alternating magnetic field, which induction heats the alloy powder in the annular gap (4) and the surface of the old roller (3), so that the alloy powder melts and forms a metallurgical bond with the repair base surface of the old roller (3). S6. Stop heating and wait for the molten old roller (3) to cool down before reheating the repair layer to eliminate internal stress. S7. The old roller (3) after reheat treatment is machined to achieve the preset size and surface finish.

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