A laser cladding repair method for large road maintenance machinery wear parts

Abstract

The application discloses a laser cladding repair method for large road maintenance machinery wear parts, and relates to the technical field of laser repair, which comprises the following steps: obtaining a pick head wear profile, installing a side and a work line, determining a partial wear and a ballast departure direction; determining whether it is suitable for original shape recovery, generating a compensation cladding path if it is suitable, forming a toughness transition layer, a wear-resistant main layer and an anti-peeling edge band in partitions if it is not suitable, and arranging a molten pool along the ballast departure direction and reserving a ballast shallow guiding line. Before laser cladding, whether it is suitable for original shape recovery is determined according to the pick head partial wear direction, the ballast departure direction, whether a groove enters a root transition area and edge peeling, so that simple repair welding or equal-thickness cladding on a complex partial wear area is avoided, and thus the risk of edge peeling, root cracking and wear layer failure after repair is reduced.

Description

Technical Field

[0001] This invention relates to the field of laser repair technology, and in particular to a laser cladding repair method for worn parts of large road maintenance machinery. Background Technology

[0002] Large track maintenance machinery is essential equipment in railway line maintenance. Among them, tamping machines use tamping picks to insert into the ballast bed and clamp, vibrate, and compact the ballast to restore the support state of the ballast bed under the sleepers. During operation, the tamping pick's blade is subjected to impact, compression, and friction with the ballast for a long time, especially in areas with changes in track structure such as turnout areas, small-radius curve areas, and bridge-tunnel transition sections. The stress direction of the ballast is complex, and the surface of the tamping pick's blade is prone to problems such as uneven wear grooves, edge peeling, localized spalling, and wear in the root transition area.

[0003] When existing tamping picks wear out, they are usually repaired by replacing the entire pick, welding, or laser cladding. Replacing the entire pick is costly, welding requires a large heat input and can easily lead to coarse, deformed, or cracked repair layers. Although laser cladding can form a wear-resistant layer on the worn surface, conventional repair methods mostly aim to restore the original shape, that is, to compensate for the depth of the wear depression and then process it to make it close to the original contour.

[0004] However, for the tamping pick's foot after work in turnout areas, small-radius curve areas, or bridge-tunnel transition sections, the wear is often not simple uniform wear, but rather asymmetrical wear related to the tamping pick's installation side, track type, and ballast flow direction. When the wear groove direction is inconsistent with the ballast departure direction, or when the wear groove has extended to the transition area at the pick's foot root and there is continuous spalling at the groove edge, if the repair layer is restored to the original shape with equal thickness, the repair layer edge may be re-exposed to the ballast impact and abrasion direction, easily forming a new spalling starting point in subsequent work. At the same time, if a high-hardness wear-resistant layer is directly formed in the transition area at the pick's foot root, it may also reduce the toughness of the root under bending loads, leading to cracking or local detachment of the repair layer. Therefore, we propose a laser cladding repair method for worn parts of large track maintenance machinery. Summary of the Invention

[0005] The purpose of this invention is to provide a laser cladding repair method for worn parts of large road maintenance machinery, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for laser cladding repair of worn parts of large road maintenance machinery, comprising:

[0007] Obtain the wear profile, installation side and corresponding working line type of the pick, and determine the wear direction of the pick surface and the ballast departure direction;

[0008] Based on the relationship between the wear direction and the ballast departure direction, whether the wear groove extends to the transition area at the root of the pick, and whether there is continuous peeling at the edge of the groove, it is determined whether the area to be repaired is suitable for restoration according to its original shape.

[0009] When the judgment result is that it is suitable to restore the original shape, a compensation cladding path corresponding to the envelope surface of the original shape is generated.

[0010] When the judgment result is that it is not suitable to restore the original shape, impact-resistant reconstruction repair is performed, and the area to be repaired is divided and formed into a tough transition layer, a wear-resistant main layer and an anti-stripping edge band respectively.

[0011] When performing impact-resistant reconstruction repair, the lap edge of the sluice is arranged along the direction of ballast departure, and shallow guide lines are retained along the ballast on the repair surface.

[0012] Preferably, the determination of the wear direction and the ballast departure direction includes: registering the three-dimensional contour of the worn tamping pick with the original outer shape envelope of the unworn tamping pick of the same model, extracting the continuous distribution line of the lowest point of the wear groove, and determining the main departure direction of the ballast on the tamping pick surface in combination with the tamping pick installation side and the type of work line; when the continuous distribution line of the lowest point of the wear groove is deviated relative to the ballast departure direction, the deviated direction is taken as the wear direction.

[0013] Preferably, the types of work lines include at least turnout areas, small-radius curve areas, and bridge-tunnel transition sections; for tamping picks after work in turnout areas, the lateral flow correction direction of ballast is determined according to the corresponding switch rail side or main rail side; for tamping picks after work in small-radius curve areas, the ballast offset correction direction is determined according to the corresponding inner rail side or outer rail side; for tamping picks after work in bridge-tunnel transition sections, the ballast impact correction direction is determined according to the direction of change in track bed stiffness, and the ballast departure direction is corrected using the correction direction.

[0014] Preferably, determining whether the area to be repaired is suitable for restoration according to its original shape includes: determining whether the direction of wear is consistent with the direction of ballast departure, whether the wear groove enters the transition zone at the root of the pick, whether there is continuous peeling at the edge of the groove, and whether there is a local weak edge in the area to be repaired; when the direction of wear is consistent with the direction of ballast departure, the wear groove does not enter the transition zone at the root of the pick, and there is no continuous peeling at the edge of the groove, the area to be repaired is determined to be suitable for restoration according to its original shape; otherwise, the area to be repaired is determined to be unsuitable for restoration according to its original shape.

[0015] Preferably, when the area to be repaired is determined to be suitable for restoration according to the original shape, the compensation cladding path is not to fill the area to be repaired with equal thickness, but to generate a compensation path from deep to shallow with the continuous distribution line of the lowest point of the wear groove as the center, and to reduce the single-pass compensation height near the edge of the groove so that the edge of the cladding layer forms a smooth transition with the original surface of the pick.

[0016] Preferably, when the area to be repaired is determined to be unsuitable for restoration according to its original shape, the division of the root yielding zone, the ballast impact zone, and the lateral rubbing zone includes: dividing the position near the root transition zone of the pick and bearing bending load into the root yielding zone; dividing the position directly bearing ballast impact in the eccentric grinding direction into the ballast impact zone; and dividing the position on the side of the ballast away from the direction and prone to edge spalling into the lateral rubbing zone; when there is a continuous spalling boundary between the ballast impact zone and the root yielding zone, a load transfer zone is set between the two.

[0017] Preferably, the formation of the toughness transition layer, the wear-resistant main layer, and the anti-stripping edge band includes: first forming a toughness transition layer in the root yielding zone, forming a wear-resistant main layer with a hardness higher than that of the toughness transition layer in the ballast impact zone, and forming an anti-stripping edge band with a hardness between that of the toughness transition layer and the wear-resistant main layer in the lateral abrasion zone; the anti-stripping edge band crosses the edge of the wear-resistant main layer and extends into the lateral abrasion zone, so that the edge of the wear-resistant main layer is not directly exposed to the ballast departure side.

[0018] Preferably, the toughness transition layer, the wear-resistant main layer, and the anti-stripping edge band are formed by a graded cladding method. The toughness transition layer is made of alloy powder with low hard particle content, the wear-resistant main layer is made of wear-resistant alloy powder containing hard particles, and the anti-stripping edge band is made of mixed powder with hard particle content between the toughness transition layer and the wear-resistant main layer. The hard particle content is gradually increased at the load transfer zone and gradually decreased at the end of the anti-stripping edge band to avoid abrupt hardness changes at the partition boundaries.

[0019] Preferably, when performing impact-resistant reconstruction repair, the ballast impact zone is divided into multiple spaced island-shaped cladding units along the eccentric wear direction. First, the non-adjacent island-shaped cladding units are clad, and then the remaining island-shaped cladding units are backfilled. The starting and ending ends of each island-shaped cladding unit avoid the load transfer zone, and the joints of adjacent island-shaped cladding units are not located on the same straight line.

[0020] Preferably, when forming shallow guide lines along the ballast, the wear-resistant main layer is not processed into a smooth surface that completely restores the original shape. Instead, shallow lines are retained along the ballast departure direction, which are lower than the original shape envelope. After the repair is completed, the load transfer zone, the anti-stripping edge zone, and the shallow guide lines along the ballast are reviewed. If there are continuous cracks in the load transfer zone, a protruding step is formed in the anti-stripping edge zone, or the shallow guide lines along the ballast are inconsistent with the ballast departure direction, the corresponding area is re-determined as unsuitable for restoration according to the original shape and is returned to perform impact-resistant reconstruction repair.

[0021] The technical effects and advantages of this invention are as follows:

[0022] (1) Before laser cladding repair, this invention determines whether the area to be repaired is suitable for restoration to its original shape based on the wear direction of the tamping pick, the direction of ballast departure, whether the wear groove extends to the transition area at the root of the pick, and whether there is continuous peeling at the edge of the groove. Compared with the traditional method of directly welding or cladding according to the original shape, this invention can identify complex wear areas that are not suitable for restoration to their original shape, thus avoiding simply restoring the area affected by abnormal ballast impact or root load to its original shape, thereby reducing the risk of edge peeling, root cracking, or local failure of the wear-resistant layer after repair.

[0023] (2) When the area to be repaired is not suitable for restoration according to the original shape, the present invention performs impact-resistant reconstruction repair and forms a tough transition layer, a wear-resistant main layer and an anti-stripping edge band respectively, so that the position near the root of the tamping pick has a good tough transition, the position directly subjected to the impact of the ballast has a high wear resistance, and the position located on the ballast-free side has anti-stripping protection, so that the repair layer is no longer a single hardness cladding layer, but can simultaneously adapt to the root bending load, the impact wear of the ballast and the lateral abrasion and spalling, thereby improving the service stability of the tamping pick in complex working conditions such as turnout area, small radius curve area and bridge-tunnel transition section.

[0024] (3) In the impact-resistant reconstruction repair, the lap edge of the slab is arranged along the ballast departure direction, and shallow guide lines are retained on the repair surface. This allows the fine ballast fragments that enter the tamping surface during subsequent tamping operations to be discharged along the ballast departure direction, reducing their retention at the edge of the wear-resistant main layer, near the anti-stripping edge, or at the joint of the cladding layer. As a result, the present invention not only improves the wear resistance and anti-stripping performance of the repair layer itself, but also reduces the repeated impact and cutting of the ballast on the cladding layer boundary by the repair surface morphology, further extending the service life of the tamping pick after repair. Attached Figure Description

[0025] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention, but do not constitute a limitation thereof. In the drawings:

[0026] Figure 1 This is a flowchart for determining the applicability of the prototype restoration method of the present invention;

[0027] Figure 2 This is a flowchart of the impact-resistant reconstruction and repair partitioning process of the present invention;

[0028] Figure 3 This is a flowchart of the verification process for the parallel ballast melt channel and shallow guide texture of the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides, for example Figures 1-3 The method shown is a laser cladding repair method for worn parts of large road maintenance machinery, comprising:

[0031] Obtain the wear profile, installation side and corresponding work line type of the pick blade, and determine the wear direction of the pick blade surface and the ballast departure direction;

[0032] Based on the relationship between the direction of wear and the direction of ballast departure, whether the wear groove extends to the transition area at the root of the pick, and whether there is continuous peeling at the edge of the groove, it can be determined whether the area to be repaired is suitable for restoration according to its original shape.

[0033] When the judgment result is that it is suitable to restore the original shape, a compensation cladding path corresponding to the envelope surface of the original shape is generated.

[0034] When the judgment result is that it is not suitable to restore the original shape, impact-resistant reconstruction repair is performed, and the area to be repaired is divided and formed into a tough transition layer, a wear-resistant main layer and an anti-stripping edge band respectively.

[0035] When performing impact-resistant reconstruction repair, the lap edge of the sluice is arranged along the ballast departure direction, and shallow guide lines are retained along the ballast on the repair surface;

[0036] In one embodiment, the worn component of the large track maintenance machinery is the tamping pick of a tamping machine. Before repair, the wear profile, installation side, and corresponding work line type of the tamping pick are obtained. The wear profile can be obtained through three-dimensional scanning, profile measurement, or image reconstruction to reflect the groove depth, groove extension direction, edge spalling position, and wear state of the root transition zone on the pick surface. The installation side is used to distinguish the position of the tamping pick on the left, right, inner rail side, outer rail side, switch rail side, or basic rail side in the tamping device. The corresponding work line type is used to distinguish whether the tamping pick is mainly used in the turnout area, small radius curve area, bridge-tunnel transition section, or ordinary straight section. Since the flow direction of ballast after being squeezed by the tamping pick is different in different line types, the main departure direction of the ballast on the pick surface can be determined by combining the installation side and the work line type.

[0037] In practical implementation, the point spacing of the 3D scanning equipment can be 0.05mm-0.20mm, and the single-point measurement accuracy is no greater than 0.03mm. When registering the 3D contour of the worn tamping pick with the original shape envelope, the root mean square error after registration is no greater than 0.10mm. If it exceeds this error range, the attitude correction is re-performed or the wear contour is re-acquired. By limiting the scanning accuracy and registration error, it can be ensured that the determination of the continuous distribution line of the lowest point of the wear groove, the invasion state of the root transition zone, and the compensation cladding path is repeatable.

[0038] After obtaining the wear profile, the distribution of wear grooves on the surface of the pick is extracted, and the direction of eccentric wear is determined. Specifically, the continuous distribution direction of the lowest point of the wear groove can be taken as the direction of eccentric wear, or the eccentric direction of the wear groove relative to the normal insertion direction of the pick or relative to the original shape envelope surface can be taken as the direction of eccentric wear. Subsequently, the direction of eccentric wear is compared with the direction of ballast departure, and it is further determined whether the wear groove extends to the root transition zone of the pick and whether there is continuous spalling at the edge of the groove. The root transition zone of the pick refers to the transition area where the pick connects to the tamping pick body and bears the concentrated bending load. The continuous spalling phenomenon refers to the formation of continuous chips, gaps, or crack extension marks along a certain length direction at the edge of the groove, rather than a single isolated point defect.

[0039] In specific implementation, the transition zone at the root of the pick can be determined according to the transition fillet or transition slope at the connection between the pick and the main body of the pick. Its range is an area extending 8mm-25mm from the tangent point of the transition fillet or the starting point of the transition slope towards the working surface of the pick. When the continuous distribution line of the lowest point of the wear groove enters this range, or when the edge of the groove is less than 2mm from the boundary of this range, it is determined that the wear groove extends to the transition zone at the root of the pick.

[0040] In practice, continuous peeling can be determined by the length of the defect at the edge of the trench. When there are pieces, gaps or cracks extending continuously along the same boundary direction at the edge of the trench, or when there are three or more adjacent defects and the distance between adjacent defects is not greater than 1 mm, it is determined that there is continuous peeling. The local weak edge refers to the edge of the area to be repaired having a remaining thickness of less than 60% of the thickness of the adjacent complete area, or an open crack, raised edge or suspended edge with a length of not less than 3 mm at the edge.

[0041] When the direction of wear is basically consistent with the direction of ballast departure, the wear groove does not extend to the transition area at the root of the pick, and there is no continuous peeling at the edge of the groove, it indicates that the area to be repaired is mainly normal wear or local shallow groove wear. After repair, the direction of ballast action is basically consistent with the original shape design direction. At this time, it can be determined that the area to be repaired is suitable for restoration according to the original shape. For this type of area, a compensation cladding path is generated based on the original shape envelope of the same model of unworn pick, so that the cladding layer can restore the original shape of the pick after filling the wear depression, ensuring that the original working form is maintained when the tamping pick is inserted, clamped and squeezed.

[0042] When the direction of wear intersects or is significantly inconsistent with the direction of ballast departure, or when the wear groove has extended to the transition zone at the root of the pick, or when there is continuous spalling at the edge of the groove, it indicates that the wear in this area is not simply material loss, but is related to abnormal impact, lateral abrasion, or concentrated load at the root of the ballast. If compensation cladding is still performed according to the original shape, the edge of the repair layer may again be located on the impact or abrasion path of the ballast, which is likely to form a new spalling starting point in subsequent operations. If a high-hardness wear-resistant layer is formed directly in the transition zone at the root of the pick, it may also reduce the toughness of this area when subjected to bending loads. Therefore, this type of area is deemed unsuitable for restoration according to the original shape and impact-resistant reconstruction repair is performed.

[0043] During impact-resistant reconstruction repair, the area to be repaired is divided into different functional zones based on its location and stress characteristics on the ballast foot, forming a tough transition layer, a wear-resistant main layer, and an anti-stripping edge zone. The tough transition layer is located near the root of the ballast foot to mitigate the hardness difference between the cladding layer and the ballast foot substrate, and to improve the crack resistance of the root area under vibration and bending loads. The wear-resistant main layer is located at the location directly subjected to ballast impact and extrusion wear to improve the wear resistance of the ballast-facing surface of the ballast foot. The anti-stripping edge zone is located on the side away from the ballast or at the edge of the wear-resistant main layer to cover or bridge the edge of the wear-resistant main layer, preventing the high-hardness wear-resistant area from directly forming exposed steps, thereby reducing the possibility of ballast spalling when scourds along the edge.

[0044] Furthermore, during the impact-resistant reconstruction and repair process, the overlapping edges of the cladding channels are arranged along the direction of ballast departure; that is, the overlapping edges between the cladding channels do not laterally obstruct the movement of the ballast, but rather follow the discharge direction of the ballast on the pick's palm surface as much as possible; in this way, the positive impact and cutting of fine ballast fragments on the overlapping edges of the cladding channels can be reduced, and the risk of the overlapping edges of the cladding layer becoming crack initiation or spalling start point can be reduced.

[0045] After repair, shallow guide lines along the ballast are retained on the surface of the pick. These shallow guide lines are shallow lines that extend along the direction of ballast departure and are lower than the original shape envelope or the highest surface of the wear-resistant main layer. These shallow lines are not deep grooves that affect the tamping operation, but rather surface micromorphology used to guide the fine ballast fragments out in a predetermined direction. By retaining these shallow guide lines along the ballast, the retention of ballast particles at the edge of the wear-resistant main layer, near the anti-stripping edge, or at the lap joint can be reduced, thereby reducing the repeated impact of ballast on the boundary of the cladding layer during subsequent operations.

[0046] Through the above embodiments, the present invention does not simply repair and restore the original shape of the worn area of ​​the tamping pick, but first determines whether it is suitable for restoration based on the actual wear direction, ballast movement direction, root wear state, and edge spalling state; for areas suitable for restoration, a compensation cladding path corresponding to the original shape envelope is adopted to ensure the working form of the tamping pick; for areas unsuitable for restoration, an impact-resistant reconstruction repair is adopted, so that the repair layer has a division of labor in terms of root toughness, ballast wear resistance, and edge spalling resistance;

[0047] Therefore, this invention can prevent the complex wear-prone areas from peeling or cracking again after being simply restored to their original shape. It can enable the transition area at the root of the tamping pick, the ballast impact area, and the ballast departure side to obtain a more suitable cladding structure. Furthermore, it can guide the ballast out through the cladding direction and the shallow guide lines along the ballast, reducing the repeated impact of the ballast on the boundary of the cladding layer. This improves the wear resistance, spalling resistance, and service stability of the repaired tamping pick in complex line conditions such as turnout areas, small radius curve areas, and bridge-tunnel transition sections.

[0048] The determination of the wear direction and the ballast departure direction includes: registering the three-dimensional contour of the worn tamping pick with the original outer envelope of the unworn tamping pick of the same model, extracting the continuous distribution line of the lowest point of the wear groove, and determining the main departure direction of the ballast on the tamping pick surface in combination with the tamping pick installation side and the type of work line; when the continuous distribution line of the lowest point of the wear groove is deviated from the ballast departure direction, the deviated direction is taken as the wear direction;

[0049] In one implementation, the surface contour of the worn tamping pick is first obtained through 3D scanning. This contour is then registered with the original shape envelope of an unworn tamping pick of the same model to eliminate measurement posture differences. After registration, the point with the greatest depth in the wear groove is extracted, and multiple lowest points are connected to form a continuous distribution line. This continuous distribution line is used to characterize the actual wear development direction on the tamping pick surface. Simultaneously, based on the installation side of the tamping pick in the tamping device and its corresponding operating line type, the main departure direction of the ballast on the tamping pick surface is determined. For example, in the turnout area, the lateral flow direction of the ballast can be determined by combining the switch rail side or the main rail side; in the small radius curve area, the ballast offset direction can be determined by combining the inner rail side or the outer rail side. When the continuous distribution line of the lowest point of the wear groove is skewed relative to the ballast departure direction, this skewed direction is taken as the wear direction. In this way, it is possible to avoid judging the wear state solely based on the groove depth, but rather to associate the wear pattern with the actual ballast movement direction, providing a basis for subsequent judgment on whether it is suitable to restore according to the original shape, thereby improving the accuracy of the repair strategy selection.

[0050] The types of track sections to be worked on include at least turnout areas, small-radius curve areas, and bridge-tunnel transition sections. For tamping picks after work in turnout areas, the lateral flow correction direction of ballast is determined based on the corresponding switch rail side or main rail side. For tamping picks after work in small-radius curve areas, the ballast offset correction direction is determined based on the corresponding inner rail side or outer rail side. For tamping picks after work in bridge-tunnel transition sections, the ballast impact correction direction is determined based on the direction of change in track bed stiffness, and the correction direction is used to correct the ballast departure direction.

[0051] In one implementation, the track type is used to correct the actual movement direction of the ballast on the pick surface. For tamping picks after work in turnout areas, due to the different spatial constraints of the switch side and the main rail side and the different compression directions of the ballast, the lateral flow correction direction of the ballast relative to the pick can be determined according to the position of the tamping pick on the corresponding switch side or the main rail side. For tamping picks after work in small radius curve areas, due to the different stress states of the inner rail side and the outer rail side, the ballast offset correction direction can be determined according to the position of the tamping pick on the corresponding inner rail side or the outer rail side. For tamping picks after work in bridge-tunnel transition sections, since the stiffness of the track bed changes along the track direction, the ballast impact correction direction can be determined according to the direction of stiffness change. Using the above correction directions to correct the ballast departure direction enables the ballast departure direction to be determined not only based on the geometric posture of the pick, but also in combination with the specific track conditions, thereby improving the accuracy of uneven wear identification and subsequent repair zoning, and avoiding misjudgment of the ballast impact direction in complex track environments.

[0052] The determination of whether the area to be repaired is suitable for restoration to its original shape includes: determining whether the direction of wear is consistent with the direction of ballast departure, whether the wear groove enters the transition zone at the root of the pick, whether there is continuous spalling at the edge of the groove, and whether there are local weak edges in the area to be repaired; when the direction of wear is consistent with the direction of ballast departure, the wear groove does not enter the transition zone at the root of the pick, and there is no continuous spalling at the edge of the groove, the area to be repaired is determined to be suitable for restoration to its original shape; otherwise, the area to be repaired is determined to be unsuitable for restoration to its original shape.

[0053] In one implementation, after determining the wear direction and the ballast departure direction, the applicability of restoring the original shape of the area to be repaired is assessed. Specifically, first, it is determined whether the wear direction and the ballast departure direction are consistent. If they are consistent, it indicates that the wear mainly occurs along the normal ballast discharge direction, and restoring the original shape after repair is unlikely to create a new impact blocking surface. Next, it is determined whether the wear groove enters the transition zone at the root of the pick. If the groove does not enter this area, it indicates that the area to be repaired mainly bears surface wear rather than concentrated root bending loads. Finally, it is determined whether there is continuous spalling at the edge of the groove. The system checks whether there are any weak edges in the area to be repaired to confirm whether the edge of the cladding layer has a stable bearing base. When the direction of the wear is consistent with the direction of the ballast leaving, the wear groove does not enter the transition zone at the root of the pick, and there is no continuous peeling at the edge of the groove, the area is determined to be suitable for restoration according to the original shape; otherwise, it is determined to be unsuitable for restoration according to the original shape. This judgment method can avoid simple prototype welding of areas with abnormal wear, root damage, or unstable edges, so that the subsequent repair strategy matches the actual cause of failure and reduces the risk of the cladding layer peeling off or cracking again after repair.

[0054] When the area to be repaired is determined to be suitable for restoration according to the original shape, the compensation cladding path is not to fill the area to be repaired with equal thickness, but to generate a compensation path from deep to shallow with the continuous distribution line of the lowest point of the wear groove as the center, and to reduce the single compensation height near the edge of the groove so that the edge of the cladding layer forms a smooth transition with the original surface of the pick.

[0055] In one embodiment, when the area to be repaired is determined to be suitable for restoration to its original shape, a compensation cladding path is generated based on the difference between the original shape envelope and the worn pick foot surface. This compensation cladding path does not fill the entire area to be repaired with equal thickness, but instead determines the main compensation area with the continuous distribution line of the lowest point of the wear groove as the center, and forms a cladding path from deep to shallow along the direction of groove depth change. For the central area with a larger groove depth, a larger compensation amount is set; for the position near the edge of the groove, the single-pass compensation height is gradually reduced, so that a smooth transition is formed between the cladding layer and the original surface of the pick foot. In this way, edge protrusions or local steps caused by equal thickness cladding can be avoided, reducing stress concentration and spalling starting points at the edge of the cladding layer during subsequent ballast impact, while ensuring that the shape of the repaired pick foot can be close to the original working contour, improving the repair quality and service stability of the original shape restoration area.

[0056] In practice, the center compensation height of the compensation cladding path can be determined based on the height difference between the original shape envelope surface and the lowest point of the wear groove. The single-pass compensation height near the edge of the groove is 20%-60% of the center compensation height. The overlap rate of adjacent cladding passes is 30%-50%, the single-layer cladding thickness is 0.4mm-1.2mm, and a finishing allowance of 0.2mm-0.8mm is reserved after cladding to ensure that the compensation area forms a continuous transition with the original surface of the pick and mortise after processing.

[0057] When the area to be repaired is determined to be unsuitable for restoration according to its original shape, the division of the root yield zone, the ballast impact zone, and the lateral rubbing zone includes: the position near the root transition zone of the pick and bearing bending load is divided into the root yield zone; the position directly bearing ballast impact in the eccentric grinding direction is divided into the ballast impact zone; and the position on the side of the ballast away from the direction and prone to edge spalling is divided into the lateral rubbing zone. When there is a continuous spalling boundary between the ballast impact zone and the root yield zone, a load transfer zone is set between the two.

[0058] In one implementation, when the area to be repaired is determined to be unsuitable for restoration to its original shape, functional zoning is performed based on the area's position on the tamping head and the direction of force. Specifically, the area near the root transition zone of the tamping head and subjected to bending loads during tamping vibration is designated as the root yield zone, which is mainly used to form a repair layer with buffering and crack resistance; the area directly subjected to ballast impact, compression, and abrasive wear in the eccentric wear direction is designated as the ballast impact zone, which is mainly used to form a wear-resistant load-bearing structure; and the area located at the ballast distance... The area on the open side, which is prone to lateral shaving and edge spalling of the ballast, is designated as the lateral shaving zone. This area is mainly used to form an edge protection structure. When there is a continuous spalling boundary between the ballast impact zone and the root yielding zone, a load transfer zone is set between the two to allow the impact load and bending load to gradually transition between different functional areas. This zoning method can avoid the formation of an overly hard cladding layer directly in the root area and also avoid the edge of the wear-resistant layer being directly exposed to the ballast shaving direction, thereby reducing the risk of cracking and edge spalling of the repair layer.

[0059] The formation of the tough transition layer, the wear-resistant main layer, and the anti-stripping edge band includes: first forming a tough transition layer in the root yielding zone, forming a wear-resistant main layer with a hardness higher than that of the tough transition layer in the ballast impact zone, and forming an anti-stripping edge band with a hardness between that of the tough transition layer and the wear-resistant main layer in the lateral abrasion zone; the anti-stripping edge band crosses the edge of the wear-resistant main layer and extends into the lateral abrasion zone, so that the edge of the wear-resistant main layer is not directly exposed to the ballast departure side;

[0060] In one embodiment, after defining the root yield zone, the ballast impact zone, and the lateral abrasion zone, a tough transition layer, a wear-resistant main layer, and an anti-stripping edge layer are formed, respectively. Specifically, a tough transition layer is first formed in the root yield zone to ensure good deformation coordination during tamping vibration and bending of the pick, preventing the formation of an overly hard and brittle cladding layer at the pick root. Subsequently, a wear-resistant main layer with a hardness higher than the tough transition layer is formed in the ballast impact zone, allowing it to primarily bear the impact, compression, and abrasive wear of the ballast. Finally, in... The lateral rubbing zone forms an anti-stripping edge band with a hardness between the toughness transition layer and the wear-resistant main layer. The anti-stripping edge band extends into the lateral rubbing zone after crossing the edge of the wear-resistant main layer, so that the edge of the wear-resistant main layer is not directly exposed to the ballast departure side. Through this structure, while ensuring the wear resistance of the ballast-facing area, the risk of the edge of the high-hardness wear-resistant layer being peeled off by the lateral cutting and prying of the ballast is reduced. The root load, impact load and lateral rubbing load are respectively borne by the appropriate cladding layer, improving the overall bonding stability of the repair layer.

[0061] In specific implementation, the thickness of the toughness transition layer is 0.5mm-1.5mm, and the mass content of hard particles is 0%-8%; the thickness of the wear-resistant main layer is 1.0mm-3.0mm, and the mass content of hard particles is 20%-45%; the thickness of the anti-stripping edge band is 0.6mm-2.0mm, and the mass content of hard particles is 8%-20%. The hard particles can be one or more of tungsten carbide, titanium carbide, and chromium carbide, with a particle size of 45μm-150μm; the matrix alloy powder can be iron-based alloy powder or nickel-based alloy powder, with a powder particle size of 45μm-150μm.

[0062] The toughness transition layer, wear-resistant main layer, and anti-stripping edge band are formed by a graded cladding method. The toughness transition layer uses alloy powder with low hard particle content, the wear-resistant main layer uses wear-resistant alloy powder with hard particles, and the anti-stripping edge band uses mixed powder with hard particle content between the toughness transition layer and the wear-resistant main layer. The hard particle content is gradually increased at the load transfer zone and gradually decreased at the end of the anti-stripping edge band to avoid abrupt hardness changes at the partition boundaries.

[0063] In one embodiment, the tough transition layer, the wear-resistant main layer, and the anti-stripping edge band are formed by a graded cladding process. Specifically, alloy powder with a low hard particle content is clad in the root yielding zone to form a tough transition layer with good toughness; wear-resistant alloy powder containing hard particles is clad in the ballast impact zone to form a wear-resistant main layer that mainly withstands ballast impact and abrasive wear; and a mixed powder with a hard particle content between the tough transition layer and the wear-resistant main layer is clad in the lateral rubbing zone to form an anti-stripping edge band. As the load transfer zone approaches, the content of hard particles is gradually increased to ensure a steady increase in hardness and wear resistance from the root yield zone to the ballast impact zone. When cladding reaches the end of the anti-stripping edge zone, the content of hard particles is gradually reduced to create a gentle transition between the anti-stripping edge zone and the original surface of the pick. This method avoids stress concentration caused by sudden changes in hardness between different functional zones, reduces the risk of cracking, spalling, and peeling at the cladding boundary, and simultaneously ensures crack resistance at the pick root, wear resistance on the ballast surface, and anti-stripping performance at the lateral edges.

[0064] In practice, the width of the load transfer zone is 3mm-10mm, and the content of hard particles gradually increases from 0%-8% in the toughness transition layer to 20%-45% in the wear-resistant main layer within this width range; the transition width at the end of the anti-stripping edge zone is 2mm-8mm, and the content of hard particles gradually decreases from 8%-20% to 0%-8% close to the original surface of the pick, so as to form a continuous transition in hardness and wear resistance.

[0065] In the process of performing impact-resistant reconstruction repair, the ballast impact zone is divided into multiple island-shaped cladding units distributed at intervals along the wear direction. First, the non-adjacent island-shaped cladding units are clad, and then the remaining island-shaped cladding units are backfilled. The starting and ending ends of each island-shaped cladding unit avoid the load transfer zone, and the joints of adjacent island-shaped cladding units are not located on the same straight line.

[0066] In one embodiment, during impact-resistant reconstruction repair, the ballast impact zone is divided into multiple island-shaped cladding units along the wear direction. These island-shaped cladding units are spaced apart. During cladding, non-adjacent island-shaped cladding units are selected first, leaving unclad gaps between clad areas. After the clad areas cool or the temperature drops, the remaining island-shaped cladding units are backfilled and clad. The starting and ending ends of each island-shaped cladding unit avoid the load transfer zone, preventing instability or localized heat concentration at the starting and ending points from affecting the continuity of the load transfer zone. At the same time, the joints of adjacent island-shaped cladding units are not located on the same straight line, preventing the formation of continuous weak joints along the wear direction. Through the above-mentioned spaced island-shaped cladding method, the localized heat accumulation caused by continuous cladding in the ballast impact zone can be reduced, the shrinkage stress concentration of the cladding layer can be reduced, and the path of crack or spalling along the same straight line can be blocked, thereby improving the bonding stability of the wear-resistant main layer under repeated impact and extrusion conditions of ballast.

[0067] In specific implementation, the length of the island cladding unit along the eccentric grinding direction is 8mm-25mm, the width is 3mm-8mm, and the unclad interval between adjacent island cladding units is 3mm-10mm; the seam stagger distance between two adjacent rows of island cladding units is not less than 2mm, and the distance from the starting and ending arc ends of each island cladding unit to the load transfer zone boundary is not less than 3mm. During laser cladding, the laser power can be 1.2kW-3.0kW, the scanning speed is 300mm / min-800mm / min, the powder feeding rate is 8g / min-25g / min, the spot diameter is 1.5mm-4.0mm, and the interlayer temperature is controlled at 120℃-350℃.

[0068] In the process of forming shallow guide lines along the ballast, the wear-resistant main layer is not processed into a smooth surface that fully restores the original shape. Instead, shallow lines are retained along the direction of ballast departure, which are lower than the envelope surface of the original shape. After the repair is completed, the load transfer zone, the anti-stripping edge zone and the shallow guide lines along the ballast are reviewed. If there are continuous cracks in the load transfer zone, a protruding step is formed in the anti-stripping edge zone, or the shallow guide lines along the ballast are inconsistent with the direction of ballast departure, the corresponding area is re-determined as unsuitable for restoration according to the original shape and is returned to perform impact reconstruction repair.

[0069] In one embodiment, after the impact-resistant reconstruction repair is completed, when the wear-resistant main layer is finished, it is not processed into a smooth surface that completely restores the original shape. Instead, shallow guide lines along the ballast departure direction are retained below the original shape envelope. These shallow guide lines are used to guide the fine ballast fragments out along the pick's surface, preventing ballast from remaining at the edge of the wear-resistant main layer or at the weld overlap position. After the repair is completed, the load transfer zone, the anti-stripping edge zone, and the shallow guide lines along the ballast are checked; when the load transfer zone exists... When there are continuous cracks, it indicates that the load transition is discontinuous; when the anti-stripping edge band forms a protruding step, it indicates that it may be subjected to lateral prying of the ballast; when the shallow guide lines along the ballast are inconsistent with the direction of ballast departure, it indicates that it cannot effectively guide the ballast out. At this time, the corresponding area is re-determined as unsuitable for restoration according to the original shape and returned to perform impact-resistant reconstruction repair. In this way, a closed loop of post-repair review and rework can be formed, reducing the risk of the cladding layer boundary cracking, peeling, or being repeatedly cut by the ballast.

[0070] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for laser cladding repair of worn parts of large road maintenance machinery, characterized in that, include: Obtain the wear profile, installation side and corresponding working line type of the pick, and determine the wear direction of the pick surface and the ballast departure direction; Based on the relationship between the wear direction and the ballast departure direction, whether the wear groove extends to the transition area at the root of the pick, and whether there is continuous peeling at the edge of the groove, it is determined whether the area to be repaired is suitable for restoration according to its original shape. When the judgment result is that it is suitable to restore the original shape, a compensation cladding path corresponding to the envelope surface of the original shape is generated. When the judgment result is that it is not suitable to restore the original shape, impact-resistant reconstruction repair is performed, and the area to be repaired is divided and formed into a tough transition layer, a wear-resistant main layer and an anti-stripping edge band respectively. When performing impact-resistant reconstruction repair, the lap edge of the sluice is arranged along the direction of ballast departure, and shallow guide lines are retained along the ballast on the repair surface.

2. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 1, characterized in that, The determination of the wear direction and the ballast departure direction includes: registering the three-dimensional contour of the worn tamping pick with the original outer shape envelope of the unworn tamping pick of the same model, extracting the continuous distribution line of the lowest point of the wear groove, and determining the main departure direction of the ballast on the tamping pick surface in combination with the tamping pick installation side and the type of work line; when the continuous distribution line of the lowest point of the wear groove is deviated from the ballast departure direction, the deviated direction is taken as the wear direction.

3. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 2, characterized in that, The types of work lines include at least turnout areas, small-radius curve areas, and bridge-tunnel transition sections. For tamping picks after work in turnout areas, the lateral flow correction direction of ballast is determined according to the corresponding switch rail side or main rail side. For tamping picks after work in small-radius curve areas, the ballast offset correction direction is determined according to the corresponding inner rail side or outer rail side. For tamping picks after work in bridge-tunnel transition sections, the ballast impact correction direction is determined according to the direction of change in track bed stiffness, and the ballast departure direction is corrected using the correction direction.

4. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 3, characterized in that, The determination of whether the area to be repaired is suitable for restoration to its original shape includes: determining whether the direction of wear is consistent with the direction of ballast departure, whether the wear groove enters the transition zone at the root of the pick, whether there is continuous peeling at the edge of the groove, and whether there is a local weak edge in the area to be repaired; when the direction of wear is consistent with the direction of ballast departure, the wear groove does not enter the transition zone at the root of the pick, and there is no continuous peeling at the edge of the groove, the area to be repaired is determined to be suitable for restoration to its original shape; otherwise, the area to be repaired is determined to be unsuitable for restoration to its original shape.

5. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 4, characterized in that, When the area to be repaired is determined to be suitable for restoration according to the original shape, the compensation cladding path does not fill the area to be repaired with equal thickness, but generates a compensation path from deep to shallow with the continuous distribution line of the lowest point of the wear groove as the center, and reduces the single-pass compensation height near the edge of the groove so that the edge of the cladding layer forms a smooth transition with the original surface of the pick.

6. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 4, characterized in that, When the area to be repaired is determined to be unsuitable for restoration according to its original shape, the division of the root yield zone, the ballast impact zone, and the lateral rubbing zone includes: dividing the area near the root transition zone of the pick and bearing bending load into the root yield zone; dividing the area directly bearing ballast impact in the eccentric grinding direction into the ballast impact zone; and dividing the area on the side of the ballast away from the direction and prone to edge spalling into the lateral rubbing zone; when there is a continuous spalling boundary between the ballast impact zone and the root yield zone, a load transfer zone is set between the two.

7. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 6, characterized in that, The formation of the toughness transition layer, the wear-resistant main layer, and the anti-stripping edge band includes: first forming a toughness transition layer in the root yielding zone, forming a wear-resistant main layer with a hardness higher than that of the toughness transition layer in the ballast impact zone, and forming an anti-stripping edge band with a hardness between that of the toughness transition layer and the wear-resistant main layer in the lateral abrasion zone; the anti-stripping edge band crosses the edge of the wear-resistant main layer and extends into the lateral abrasion zone, so that the edge of the wear-resistant main layer is not directly exposed to the ballast departure side.

8. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 7, characterized in that, The toughness transition layer, wear-resistant main layer, and anti-stripping edge band are formed by a graded cladding method. The toughness transition layer uses alloy powder with low hard particle content, the wear-resistant main layer uses wear-resistant alloy powder with hard particles, and the anti-stripping edge band uses mixed powder with hard particle content between the toughness transition layer and the wear-resistant main layer. The hard particle content is gradually increased at the load transfer zone and gradually decreased at the end of the anti-stripping edge band to avoid abrupt hardness changes at the partition boundaries.

9. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 8, characterized in that, When performing impact-resistant reconstruction repair, the ballast impact zone is divided into multiple spaced island cladding units along the eccentric wear direction. First, the non-adjacent island cladding units are clad, and then the remaining island cladding units are backfilled. The starting and ending ends of each island cladding unit avoid the load transfer zone, and the joints of adjacent island cladding units are not located on the same straight line.

10. The laser cladding repair method for worn parts of large road maintenance machinery according to claim 9, characterized in that, When forming shallow guide lines along the ballast, the wear-resistant main layer is not processed into a smooth surface that fully restores the original shape. Instead, shallow lines are retained along the direction of ballast departure, which are lower than the envelope surface of the original shape. After the repair is completed, the load transfer zone, the anti-stripping edge zone and the shallow guide lines along the ballast are reviewed. When there are continuous cracks in the load transfer zone, protruding steps in the anti-stripping edge zone or the shallow guide lines along the ballast are inconsistent with the direction of ballast departure, the corresponding area is re-determined as unsuitable for restoration according to the original shape and returned to perform impact reconstruction repair.

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