CN121407086A - Laser cladding method for conveying plate on surface of shaft part - Google Patents

Abstract

The invention discloses a plate feeding laser cladding method for the surface of a shaft part, which is characterized in that a milling cutter, a laser cladding head and a milling cutter are sequentially called by an automatic tool changing system on a turning and milling composite machine tool platform to complete the whole flow of pretreatment-cladding-post treatment of the surface of the shaft part. The cladding process adopts a plate feeding type process, a prefabricated formed sheet strip is fed to the surface of a processing shaft through a conveying roller and a guide roller at a specific angle, and a laser beam is formed into a homogenized rectangular light spot matched with the width of the sheet through a high-precision micro lens array, and the homogenized rectangular light spot irradiates a plate-shaft contact area to realize synchronous melting and metallurgical bonding. The invention greatly improves single-channel cladding width and efficiency by feeding plate cladding, avoids multi-channel lap joint defects, ensures high bonding strength and final dimensional accuracy of a cladding layer by optical-mechanical-control integrated integration, and realizes high-efficiency and high-quality integrated laser surface modification of shaft parts.

Description

Laser cladding method for conveying plate on surface of shaft part

Technical Field

The invention relates to the technical field of surface strengthening of metal shaft parts, in particular to a laser cladding method for a surface plate feeding of a shaft part.

Background

With the development of industrial equipment to high performance, long service life and light weight, shaft parts (such as a transmission shaft, a roller, a crankshaft and the like) are taken as key moving parts and often fail due to abrasion, corrosion, fatigue and the like. As a high-precision additive manufacturing/remanufacturing method, the laser cladding technology is used for synchronously cladding alloy powder on the surface of a substrate through a high-energy laser beam to form a metallurgically bonded functional coating, so that a workpiece can be effectively protected from corrosion and abrasion. The method can not only remarkably prolong the service life of parts and improve the reliability of equipment, but also bring remarkable economic, social and ecological environmental benefits.

When the traditional laser cladding has low linear speed (< 5 m/min), and high-speed cladding (the linear speed is increased to 20-50 m/min) is adopted for improving the efficiency, small light spots and high power density are generally required, so that the single-channel cladding width is narrow, multiple overlapping is required to cover a wider surface area, and the overlapping area is easy to have the problems of uneven tissue, component segregation, concentrated residual stress and the like due to heat circulation superposition, so that the problems become weak links of coating performance.

In addition, the conventional process generally includes a plurality of independent processes such as "turning (blanking) →laser cladding (moving to a dedicated apparatus) →grinding/milling (finishing)". The workpiece is clamped and positioned for multiple times among different devices, so that the production beat is long, repeated positioning errors are introduced, and the combination precision of the cladding layer and the substrate and the size precision of a final finished product are affected.

Therefore, the invention provides a laser cladding method for feeding a plate on the surface of a shaft part, which aims to improve the processing efficiency, avoid the problems of uneven structure and performance defect caused by a lap joint area and realize high-efficiency and high-quality wide laser cladding processing.

Disclosure of Invention

In order to solve the problems of low cladding efficiency, uneven tissue performance and performance defects of a lap joint area, precision loss caused by multi-working-procedure circulation and the like in the traditional laser cladding technology, the invention provides a shaft part surface plate feeding laser cladding method, which adopts a prefabricated thin plate as a cladding material, utilizes a beam shaping technology to generate homogenized rectangular light spots matched with the thin plate in size, realizes larger-area cladding in a single rotation period of a main shaft, not only remarkably improves cladding processing efficiency, but also reduces cladding lap joint times, thereby effectively avoiding the problems of uneven tissue and performance defects caused by lap joint areas.

In order to achieve the above purpose, the present invention adopts the following technical scheme:

the invention provides a laser cladding method for a surface plate feeding of a shaft part, which comprises the following steps:

S1, surface pretreatment:

precisely milling the surface of a machining shaft clamped on a main shaft of a machine tool by using a milling cutter, removing surface defects and obtaining a clean surface with preset roughness;

S2, guiding and positioning the thin plate:

Selecting a metal sheet strip with the width of 15-40mm and the thickness of 0.2-1mm, leading the sheet strip out of a unreeling disc, conveying the sheet strip through a driving roller and a guide roller, enabling the sheet strip to continuously contact at an inclined angle of 20-45 degrees and pressing the sheet strip against the surface of a processing shaft processed in the step S1;

S3, shaping laser beams:

The laser beam is shaped through a high-precision micro lens array system, the system drives a precision displacement platform through a servo motor, the position of a micro lens on a z axis is adjusted, the laser beam is precisely controlled, and homogenized light beams with the lengths of 15-40mm and the widths of 0.5-3mm are obtained;

S4, laser plate feeding cladding:

Starting a machine tool spindle to drive a processing shaft to rotate at a constant speed, simultaneously starting a plate feeding mechanism to convey the thin plate strip at a constant speed, and focusing and irradiating the laser beam shaped in the step S3 on a contact area between the outer surface of the thin plate strip and the surface of the processing shaft to enable the thin plate strip to be melted on the surface of the processing shaft to form a cladding layer;

s5, cladding post-treatment:

And (3) precisely milling the surface of the cladding layer formed in the step S4 by using a milling cutter, removing the oxide layer and meeting the requirements of final size and surface roughness.

The technical scheme is adopted:

In step S2, the thickness of the sheet metal strip is controlled within the range of 0.2-1mm in order to ensure that the molten pool is continuous when the sheet is melted. The thickness of the thin plate is too small, the molten pool surface tension formed by melting the thin plate can enable the molten pool to be aggregated into liquid drops, the liquid drops cannot be spread like a plate, the thin plate is too thick, the thin plate is required to be melted by higher laser energy, a heat affected zone can be expanded due to huge laser energy, and when the thin plate strip is made of high-reflection materials such as copper and aluminum, the laser energy absorptivity is lower, and heat absorption is more difficult to melt.

The sheet strip is controlled to be continuously contacted and pressed against the surface of the processing shaft processed in the step S1 at an inclined angle of 20-45 degrees, if the inclined angle is too large, normal operation of the laser head is interfered, and when the inclined angle is too small, the laser head is easily damaged by reflection during cladding of high-reflectivity materials, and a molten pool formed by melting the sheet material can be caused to flow away along the sheet.

Further, the milling cutter in the step S1 and the step S5 and the laser cladding head in the step S4 are integrated in an automatic cutter changing system of the processing machine tool to be automatically switched. In use, the current machining head is automatically switched to a milling cutter (a hard alloy end mill with a four-edge design and a diameter of 12 mm) or a high-power semiconductor laser cladding head (wavelength 1064 nm) by an automatic tool changing system of a machining machine tool.

Further, in the step S3, the laser power range is 8-16kW, the surface linear speed of the processing shaft is 20-60mm/S, the plate feeding speed of the thin plate strip is 20-60mm/S, and the plate feeding speed of the thin plate strip is more than or equal to the surface linear speed of the processing shaft so as to ensure that a molten pool formed by melting the thin plate strip is continuous under laser irradiation. Preferably, the surface linear velocity of the processing shaft is less than or equal to 50mm/s.

The laser power is controlled within the range of 8-16kW, so that the problem that the heat affected zone of the shaft body is too large after cladding due to too high laser power or the thin plate cannot be melted and cannot be added due to too low laser power is avoided.

Further, under the above parameters, the scanning speed of the laser cladding head affects the lap rate of cladding, and therefore, the scanning speed of the laser cladding head is set to 2-8mm/s.

Further, in step S2, the curl radius of the curled sheet band disc is 150mm or more to prevent plastic deformation. When the thin plate strip is copper strip, the thickness is 0.2-1mm, and when the thin plate strip is copper strip, aluminum strip and other high-reflection materials, the thickness is 0.2-0.5mm.

Preferably, in step S3, the homogenized beam is obtained by adjusting the x-direction divergent cylindrical microlens, the x-direction focusing cylindrical microlens, the y-direction divergent cylindrical microlens, and the y-direction focusing cylindrical microlens, and the spot energy distribution uniformity is not less than 95%. Secondly, the spot size is equivalent to the size of the thin plate so as to ensure that the thin plate strip for cladding is completely under laser irradiation, and if the thin plate strip for cladding is selected to be made of high-reflection materials such as copper and aluminum, the width of the homogenized beam is reduced to 0.5-1mm in order to obtain larger laser energy density.

Further, in the step S1, the milling cutter removes a rust layer with the thickness of 0.1-0.3mm on the surface of the shaft, repairs surface defects such as pits with the depth of less than or equal to 0.5mm, and the surface roughness Ra of less than or equal to 3.2 mu m after treatment.

Preferably, the milling cutter is started at a spindle speed of 800rpm (1000 rpm for steel and 1200rpm for copper for aluminum) and precision milling of the machined shaft surface is performed at a cutting depth of 0.2 mm. In the milling process, a down milling mode is adopted, the feeding speed is set to be 150mm/min, the cutting depth of the milling cutter is set to be 0.1-0.2mm, so that the defects of rust, pits and the like on the surface of a processing shaft are removed, and if the surface of the processing shaft still has rust, the cutting depth can be properly increased.

Further, in the step S5, the cutting depth is 0.1-0.2mm, the oxide layer generated after laser cladding is removed, the total milling depth is not more than 20% of the thickness of the cladding layer, and the surface roughness Ra is less than or equal to 1.6 mu m after treatment. In the processing process, the numerical control system monitors cutting force fluctuation in real time, and if abnormal vibration (such as cutter abrasion or uneven cladding layer) is detected, the feeding rate is automatically adjusted or an alarm is triggered, so that the processing quality is ensured to be stable.

Preferably, the milling cutter main shaft rotates at 1200rpm (1400 rpm for steel and 1800rpm for aluminum and 1800rpm for copper), is axially fed along the machining shaft in a down milling mode, the cutting depth is 0.15mm, the feeding speed is 200mm/min, and the milling depth of the milling cutter during post-treatment is controlled within 0.2mm, so that the cladding layer is prevented from being synchronously removed while the surface oxide layer is removed.

Compared with the prior art, the invention has the following beneficial effects:

(1) Compared with the traditional high-speed laser cladding, the invention selects the plate feeding cladding and the rectangular light spots, has higher cladding efficiency, realizes the cladding with larger area in the single rotation period of the main shaft, not only remarkably improves the processing efficiency, but also greatly reduces the lap joint times of the cladding layers (greatly reduces the cladding covered way times required for reaching the same coverage rate), thereby effectively avoiding the problems of uneven tissue and weak performance area caused by multiple lap joints.

(2) The sheet strip is a prefabricated solid material, the utilization rate is close to 100%, the problems of powder scattering or unsmooth wire feeding are avoided, the rectangular homogenized light spot energy is uniformly distributed, the defects of overheat in the center and insufficient melting of the edge of a Gaussian light spot are avoided, the heat input is more controllable, the dilution rate is lower (controllable is 5% -15%), and the heat affected zone of a matrix is smaller.

(3) According to the invention, the lathe and the high-speed laser cladding are integrated on one device, the whole process flow (pretreatment-cladding-post treatment) is finished under the same coordinate system of a turning and milling compound machine tool, and the workpiece is clamped once, so that repeated positioning errors caused by multi-device and multi-working-flow are thoroughly eliminated, meanwhile, the laser cladding and milling are finished under the unified coordinate system, the bonding strength and the dimensional precision of the cladding layer and the substrate are ensured, and the efficient and high-quality laser processing is achieved.

(4) The micro-lens array can flexibly adjust the rectangular light spot size so as to adapt to thin plate strips with different widths, and the numerical control system cooperatively controls the spindle rotation speed, the plate feeding speed, the laser power and the milling parameters, so that the process window is wide, the stability is good, and the micro-lens array is suitable for shaft parts with different diameters and different materials.

Drawings

The invention will be described in further detail with reference to the drawings and the specific embodiments.

FIG. 1 is a schematic diagram of a laser cladding process for machining a surface of a shaft;

FIG. 2 is a schematic diagram of a laser feeding plate cladding process according to the present invention;

FIG. 3 is a schematic diagram of the working principle of the optical path inside the laser cladding head in the present invention;

Wherein, the specific reference numerals are as follows:

the laser cladding device comprises a machine tool spindle 1, a machining shaft 2, a thin plate strip 3, a disc tool magazine 4, a laser cladding head 5, a milling cutter 6, a thin plate belt disc 7, a driving roller 8, guide rollers 9,x, an x-direction focusing cylindrical microlens 10, an y-direction diverging cylindrical microlens 12 and an y-direction focusing cylindrical microlens 13.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

The invention provides a laser surface plate feeding cladding method for shaft parts, which is shown in fig. 1 and 2 and comprises the following steps:

(1) The surface pretreatment of the processing shaft, namely, the processing shaft 2 is clamped on a main shaft 1 of a machine tool, the current processing head is switched to a hard alloy end milling cutter 6 through an automatic cutter changing system of the machine tool, the milling cutter 6 has a four-blade design, the diameter is 12mm, and the cutter changing process automatically completes cutter changing and cutter length compensation through a disc cutter magazine 4. Subsequently, the milling cutter 6 is started, and the surface of the machining shaft 2 is precision milled while being cooled and lubricated with the cutting fluid. The rust layer with the thickness of 0.1-0.3mm on the surface of the processing shaft 2 is removed by the process, and surface defects such as pits with the depth of not more than 0.5mm are repaired, so that the surface roughness of the processing shaft 2 reaches the technical requirement of Ra3.2mu m.

Specifically, the milling cutter 6 is started at a spindle rotation speed of 800rpm (1000 rpm for steel and 1200rpm for copper) and precision-mills the surface of the machining shaft 2 at a cutting depth of 0.2 mm. In the milling process, a down milling mode is adopted, the feeding speed is set to be 150mm/min, the cutting depth of the milling cutter 6 is set to be 0.1-0.2mm, so that the defects of rust, pits and the like on the surface of the machining shaft 2 are removed, and if the surface of the machining shaft 2 still has rust, the cutting depth can be properly increased.

(2) The guiding and positioning of the cladding sheet, namely selecting a sheet strip 3 with the width of 15-40mm and the thickness of 0.2-1mm, mounting the sheet strip 3 on a sheet strip disc 7, driving a driving roller 8 by using a servo motor, conveying the strip to a guiding roller 9, adjusting the relative positions of the guiding roller 9 and the driving roller 8, and enabling the sheet strip 3 to be contacted with the surface of a turned processing shaft 2 at a space included angle of 20-45 degrees.

In particular, the coil of coiled strip has a coiling radius of greater than or equal to 150mm to prevent plastic deformation. Secondly, the thickness of the selected thin plate strip 3 is related to the reflectivity of the material, and is 0.2-1mm for steel strips and 0.2-0.5mm for high-reflectivity materials such as copper and aluminum.

(3) And (3) regulating and shaping the laser beam, namely shaping the laser beam through a high-precision micro lens array system, driving a precision displacement platform through a servo motor, adjusting the position of a micro lens on a z axis, and realizing precise control on the laser beam to obtain a homogenized beam with the length of 15-40mm and the width of 0.5-3 mm.

Specifically, as shown in fig. 3, the homogenized beam can be obtained by adjusting the x-direction divergent cylindrical microlens 10, the x-direction focusing cylindrical microlens 11, the y-direction divergent cylindrical microlens 12 and the y-direction focusing cylindrical microlens 13, and the uniformity of the spot energy distribution is not less than 95%. Secondly, the spot size is equal to the size of the sheet strip 3 to ensure that the sheet strip 3 for cladding is completely under laser irradiation, and if the sheet strip 3 for cladding is selected to be made of high-reflectivity materials such as copper and aluminum, the width of the homogenized beam should be reduced to 0.5-1mm in order to obtain larger laser energy density.

(4) And (3) laser plate feeding cladding, namely switching the current processing head to a high-power semiconductor laser cladding head 5 (wavelength 1064 nm) through an automatic tool changing system of a machine tool. After the switching is completed, the machine tool spindle 1 rotates at a low speed, and the linear speed of the surface of the machining shaft 2 is ensured to be stable. Meanwhile, a servo motor of the plate feeding mechanism drives a driving roller 8 to convey the cladding sheet at a constant speed so as to be always in contact with the surface of the processing shaft 2.

Specifically, the rotation speed and the shaft diameter of the lathe spindle are related to the laser cladding speed, and the cladding layer is poorly bonded when the laser cladding speed is too high, and the thermal influence on the substrate of the shaft 2 to be processed is too large when the cladding speed is too low, so that the shaft surface linear speed of the shaft 2 to be processed after the pretreatment of the lathe tool is 20-60mm/s due to the different lathe spindle speeds of materials with different shaft diameters. For example, the spindle diameter is 20-40mm, the turning speed range of the lathe spindle is 10-20rpm, the spindle diameter is 30-50mm, and the turning speed range of the lathe spindle is 5-15rpm. In order to ensure that the thin plate strip 3 melts under the laser irradiation, the laser power setting range is 8-16kW, and the plate feeding speed is not less than the surface linear speed of the shaft 2 to be processed, so as to ensure that a molten pool formed by melting the thin plate strip 3 is continuous under the laser irradiation, and the plate feeding speed is 20-60mm/s.

It should be noted that, under the above parameters, the scanning speed of the laser cladding head 5 affects the lap rate of cladding, so the scanning speed of the laser cladding head 5 should be set according to 15-30% of the lap rate of cladding.

(5) And (3) carrying out surface post-treatment on the machining shaft, namely switching the current laser cladding head 5 into a hard alloy four-edge end mill 6 through an automatic tool changing system of a machine tool, automatically completing the tool changing process by a disc tool magazine 4, and executing tool length compensation and cladding layer thickness compensation so as to ensure machining precision. During milling, water soluble cutting fluid is used for cooling and lubricating simultaneously to reduce tool wear and prevent secondary oxidation. The milling target is to remove an oxide layer (the thickness is about 0.1-0.2 mm) generated after laser cladding, and ensure that the surface roughness after processing is less than or equal to Ra1.6mu.m, so that the surface of the shaft part meets the finishing requirement. In the processing process, the numerical control system monitors cutting force fluctuation in real time, and if abnormal vibration (such as cutter abrasion or uneven cladding layer) is detected, the feeding rate is automatically adjusted or an alarm is triggered, so that the processing quality is ensured to be stable.

Specifically, the spindle of the milling cutter 6 rotates at 1200rpm (1400 rpm for steel and 1800rpm for copper) and is fed axially along the machining shaft 2 by a down milling mode, the cutting depth is 0.15mm, the feeding speed is 200mm/min, and the milling depth of the milling cutter 6 during post-treatment is controlled within 0.5mm, so that the cladding layer is prevented from being synchronously removed while the surface oxide layer is removed.

Example 1

In this embodiment, the processing shaft surface plate feeding laser cladding includes the following steps:

(1) The surface pretreatment of the machining shaft comprises the steps of selecting a shaft to be machined with the diameter of 50mm, using 45 steel as a material, using an automatic tool changing system to switch a machining head to a milling cutter, setting the rotation speed range of a machine tool main shaft to be 20rpm, starting the milling cutter main shaft at the rotation speed of 800rpm, and precisely milling the surface of the machining shaft at the cutting depth of 0.2 mm. In the milling process, a down milling mode is adopted, the feeding speed is set to be 150mm/min, and the cutting depth of the milling cutter is set to be 0.1-0.2mm so as to remove defects such as rust, pits and the like on the surface of a processing shaft.

(2) Guiding and positioning a cladding sheet, namely selecting a 316 sheet strip with the width of 20mm and the thickness of 0.5mm, driving a driving roller by using a servo motor, conveying the strip to the guiding roller, adjusting the relative positions of the guiding roller and the driving roller, and enabling the strip to contact the surface of a turned processing shaft at a space included angle of 30 degrees.

(3) And regulating and shaping laser beams, namely regulating the spatial positions of the x-direction divergent cylindrical micro lens, the x-direction focusing cylindrical micro lens, the y-direction divergent cylindrical micro lens and the y-direction focusing cylindrical micro lens on the z axis to obtain homogenized beams with the length of 20mm and the width of 3 mm.

(4) And (3) laser plate feeding cladding, namely switching a processing head into a laser cladding head by using an automatic tool changing system, irradiating a laser spot focus on a contact area between the outer surface of the sheet strip and the surface of a processing shaft, wherein the laser power is set to be 12kW, the scanning speed of the laser cladding head is 4mm/s, the rotating speed of a machine tool spindle is 15rpm, and the plate feeding speed is 40mm/s. A cladding layer of 0.5mm thickness was obtained on the machined shaft surface.

(5) And (3) carrying out surface post-treatment on the machining shaft, namely switching the machining head into a milling cutter by using an automatic tool changing system, and performing tool length compensation and cladding layer thickness compensation to ensure machining precision. During milling, water soluble cutting fluid is used for cooling and lubricating simultaneously to reduce tool wear and prevent secondary oxidation. The milling target is to remove an oxide layer (the thickness is about 0.2 mm) generated after laser cladding, and ensure that the surface roughness after processing is less than or equal to Ra1.6mu.m, so that the surface of the shaft part meets the finish machining requirement.

The thickness of the 316 coating finally prepared on the surface of the processing shaft in the embodiment is 0.3mm, the dilution rate is 10%, and the interface bonding strength reaches 280Mpa.

Wherein, the dilution ratio = [ matrix penetration amount/(cladding material addition amount+matrix penetration amount) ] × 100%.

The interface bonding strength test standard is GB-T44990-2024.

Example 2

In this embodiment, the processing shaft surface plate feeding laser cladding includes the following steps:

(1) And (3) surface pretreatment of the machining shaft, namely selecting a shaft to be machined with the diameter of 40mm, wherein the material is Q235, switching the machining head to a milling cutter by using an automatic cutter changing system, setting the rotation speed range of a main shaft to be 20rpm, starting the main shaft of the milling cutter at the rotation speed of 800rpm, and precisely milling the surface of the machining shaft at the cutting depth of 0.2 mm. In the milling process, a down milling mode is adopted, the feeding speed is set to be 150mm/min, and the cutting depth of the milling cutter is set to be 0.1-0.2mm so as to remove defects such as rust, pits and the like on the surface of a processing shaft.

(2) Guiding and positioning a cladding sheet, namely selecting a 316 sheet strip with the width of 30mm and the thickness of 0.5mm, driving a driving roller by using a servo motor, conveying the strip to the guiding roller, adjusting the relative positions of the guiding roller and the driving roller, and enabling the strip to contact the surface of a turned processing shaft at a space included angle of 30 degrees.

(3) And regulating and shaping laser beams, namely regulating the spatial positions of an x-direction divergent cylindrical micro lens, an x-direction focusing cylindrical micro lens, a y-direction divergent cylindrical micro lens and a y-direction focusing cylindrical micro lens on a z-axis to obtain homogenized beams with the length of 30mm and the width of 2 mm.

(4) And (3) laser plate feeding cladding, namely switching a processing head into a laser cladding head by using an automatic tool changing system, irradiating a laser spot focus on the contact position of the thin plate and the surface of a processing shaft, wherein the laser power is set to be 12kW, the scanning speed of the laser cladding head is 6mm/s, the rotating speed of a main shaft is 15rpm, and the plate feeding speed is 40mm/s. A cladding layer of 0.6mm thickness was obtained on the machined shaft surface.

(5) And (3) carrying out surface post-treatment on the machining shaft, namely switching the machining head into a milling cutter by using an automatic tool changing system, and performing tool length compensation and cladding layer thickness compensation to ensure machining precision. During milling, water soluble cutting fluid is used for cooling and lubricating simultaneously to reduce tool wear and prevent secondary oxidation. The milling target is to remove an oxide layer (the thickness is about 0.2 mm) generated after laser cladding, and ensure that the surface roughness after processing is less than or equal to Ra1.6mu.m, so that the surface of the shaft part meets the finish machining requirement.

The thickness of the 316 coating finally prepared on the surface of the processing shaft in the embodiment is 0.4mm, the dilution rate is 8%, and the interface bonding strength can reach 295Mpa.

Example 3

In this embodiment, the processing shaft surface plate feeding laser cladding includes the following steps:

(1) The surface pretreatment of the machining shaft, namely selecting a shaft to be machined with the diameter of 30mm, wherein the material is 40Cr, switching a machining head to a milling cutter by using an automatic cutter changing system, setting the rotation speed range of a main shaft to be 20rpm, starting the main shaft of the milling cutter at the rotation speed of 800rpm, and precisely milling the surface of the machining shaft at the cutting depth of 0.2 mm. In the milling process, a down milling mode is adopted, the feeding speed is set to be 150mm/min, and the cutting depth of the milling cutter is set to be 0.1-0.2mm so as to remove defects such as rust, pits and the like on the surface of a processing shaft.

(2) Guiding and positioning a cladding sheet, namely selecting a 316 sheet strip with the width of 20mm and the thickness of 1mm, driving a driving roller by using a servo motor, conveying the strip to the guiding roller, adjusting the relative positions of the guiding roller and the driving roller, and enabling the strip to contact the surface of a turned processing shaft at a space included angle of 30 degrees.

(3) And regulating and shaping laser beams, namely regulating the spatial positions of the x-direction divergent cylindrical micro lens, the x-direction focusing cylindrical micro lens, the y-direction divergent cylindrical micro lens and the y-direction focusing cylindrical micro lens on the z axis to obtain homogenized beams with the length of 20mm and the width of 2 mm.

(4) And (3) laser plate feeding cladding, namely switching a processing head into a laser cladding head by using an automatic tool changing system, irradiating a laser spot focus on the contact position of the thin plate and the surface of a processing shaft, setting the laser power to be 16kW, and setting the scanning speed of the laser cladding head to be 3mm/s, the rotating speed of a main shaft to be 10rpm, and the plate feeding speed to be 20mm/s. A cladding layer 1.2mm thick was obtained on the machined shaft surface.

(5) And (3) carrying out surface post-treatment on the machining shaft, namely switching the machining head into a milling cutter by using an automatic tool changing system, and performing tool length compensation and cladding layer thickness compensation to ensure machining precision. During milling, water soluble cutting fluid is used for cooling and lubricating simultaneously to reduce tool wear and prevent secondary oxidation. The milling target is to remove an oxide layer (the thickness is about 0.2 mm) generated after laser cladding, and ensure that the surface roughness after processing is less than or equal to Ra1.6mu.m, so that the surface of the shaft part meets the finish machining requirement.

The thickness of the 316 coating finally prepared on the surface of the processing shaft in the embodiment is 1mm, the dilution rate is 5%, and the interface bonding strength can reach 320Mpa.

Example 4

(1) Surface pretreatment of machining shaft

The 6061 aluminum alloy shaft with the diameter of 60mm is pretreated, the revolution speed range of the main shaft is set to be 10rpm, the main shaft of the milling cutter is started at the rotation speed of 1000rpm, and the surface of the processing shaft is precisely milled at the cutting depth of 0.2 mm. In the milling process, a forward milling mode is adopted, the feeding speed is set to 150mm/min, the cutting depth is 0.1mm, and a special cutting fluid is used for preventing a cutter from sticking to obtain a smooth surface.

(2) Guiding and positioning of cladding sheet

A4043 aluminum alloy sheet with the width of 15mm and the thickness of 0.3mm is selected, and the strip contacts the axial surface at a small included angle of 20 degrees, so that the reflection of the high-reflection material on laser is reduced.

(3) Laser beam steering and shaping

In order to cope with high reflectivity, the width of the light spot is compressed to 1mm, and the length is kept to 15mm, so that the energy density is greatly improved, and the aluminum alloy is promoted to be rapidly absorbed and melted.

(4) Laser plate feeding cladding

The high laser power of 16kW is adopted to overcome high reflection, the spindle rotating speed is 10rpm, the plate feeding speed is 35mm/s, the laser scanning speed is 5mm/s, and cladding is rapidly completed to reduce heat input.

(5) Surface finishing of a machining shaft

The spindle speed of the milling cutter is 1400rpm, the cutting depth is 0.1mm, and the feeding speed is 200mm/min, so that the oxide film is ensured to be removed without damaging the soft aluminum matrix.

The aluminum-silicon alloy cladding layer with the thickness of about 0.25mm is finally prepared in the embodiment, the dilution rate is controlled below 8%, and the bonding strength reaches 180MPa.

Example 5

(1) Surface pretreatment of machining shaft

The 6061 aluminum alloy shaft with the diameter of 40mm is preprocessed, a high-rotating-speed and light-cutting strategy is adopted to prevent the sticking of a cutter when milling, wherein the rotating speed of a milling cutter main shaft is 1000rpm, the rotating speed of a machine tool main shaft is set to be 15rpm, the cutting depth is 0.1mm, the feeding speed is 150mm/min, and the cutter is fully cooled.

(2) Guiding and positioning of cladding sheet

An aluminum-silicon alloy (AlSi 12) sheet strip is selected, the width is 15mm, and the thickness is 0.4mm, so that the surface hardness is improved. The plate feeding mechanism is adjusted to enable the strip to cover the axial surface stably at an included angle of 25 degrees.

(3) Laser beam steering and shaping

The laser beam is shaped into a homogenized rectangular light spot with the length of 20mm and the width of 1.2mm, the energy distribution is uniform, and the aluminum alloy is ensured to be uniformly melted.

(4) Laser plate feeding cladding

The laser cladding head is in place. The laser power was set to 12kW. The spindle speed of the machine tool was 15rpm. The plate feeding speed is set to be 35mm/s, the laser scanning speed is set to be 3.5mm/s, and cladding is completed under lower heat input, so that overheating of aluminum alloy is avoided.

(5) Surface finishing of a machining shaft

The spindle speed of the milling cutter is 1400rpm, the cutting depth is 0.1mm, and the feeding speed is 200mm/min, so that the oxide film is ensured to be removed without damaging the soft aluminum matrix.

The aluminum-silicon alloy cladding layer with the thickness of about 0.35mm is finally prepared in the embodiment, the dilution rate is about 8%, and the interface bonding strength exceeds 180MPa.

Example 6

(1) Surface pretreatment of machining shaft

And selecting a T2 pure copper shaft with the diameter of 25mm, slightly abrading and oxidizing the surface, and switching to the hard alloy end mill through an automatic tool changing system. Aiming at the characteristics of copper materials, the high rotating speed and light cutting are adopted, namely the rotating speed of a milling cutter main shaft is 1200rpm, the rotating speed of a machine tool main shaft is set to be 18rpm, the cutting depth is 0.08mm, the feeding speed is 150mm/min, and a special cutting fluid is used for obtaining a smooth surface.

(2) Guiding and positioning of cladding sheet

T2 pure copper sheet strips with the same material as the substrate are selected, the width is 15mm, and the thickness is 0.3mm. The guiding mechanism is adjusted to enable the belt material to be precisely attached to the axial surface at a space included angle of 22 degrees.

(3) Laser beam steering and shaping

In order to overcome the high reflectivity of pure copper, the laser beam is shaped into a tiny homogenized light spot with the length of 15mm and the width of 0.5mm, so that extremely high energy density is obtained, and the copper material is ensured to absorb laser energy rapidly.

(4) Laser plate feeding cladding

Switching to the laser cladding head. The laser power was set to 14kW. The spindle speed of the machine tool was 18rpm. To form a good bath, the feed plate speed was set at 26mm/s and the laser scanning speed was set at 2.6mm/s. By accurate synchronization, a low heat input copper-copper metallurgical bond is achieved.

(5) Surface finishing of a machining shaft

The milling cutter was replaced and thickness compensation was performed at 1800rpm, feed speed 200mm/min, cutting depth 0.05mm, oxide layer removal and surface finish ensured.

The example finally produced a dense pure copper cladding layer with a thickness of about 0.25 mm. The dilution rate is less than 5%, and the interface bonding strength reaches 140MPa.

Example 7

(1) Surface pretreatment of machining shaft

The 6061 aluminum alloy shaft with a diameter of 45mm was pretreated with the aim of cladding it with a pure copper functional layer. Milling parameters refer to the aluminum material characteristics, namely the rotating speed of a milling cutter main shaft is 1000rpm, the rotating speed of a machine tool main shaft is set to 16rpm, the cutting depth is 0.1mm, and the feeding speed is 150mm/min.

(2) Guiding and positioning of cladding sheet

An oxygen-free copper sheet strip is selected, the width is 12mm, the thickness is 0.25mm, and the feeding posture is precisely controlled so that the oxygen-free copper sheet strip contacts the surface of the aluminum shaft at an included angle of 20 degrees.

(3) Laser beam steering and shaping

For the high reflectivity of copper, a high energy density light spot is adopted, and the light spot is shaped to be 15mm in length and 0.8mm in width, so that rapid local heating is realized.

(4) Laser plate feeding cladding

This is a process critical, employing a high power, fast scan strategy to suppress brittle phases. The laser power was set to 15kW. The spindle speed of the machine tool was 16rpm. The plate feeding speed is set to 40mm/s, and the laser scanning speed is set to 3.0mm/s.

(5) Surface finishing of a machining shaft

The copper layer is a functional layer, and the post-treatment is mainly precise and smooth. Super finish milling is required, the rotating speed is 1800rpm, the feeding speed is 200mm/min, and the cutting depth is 0.03mm.

The embodiment finally successfully prepares the compact pure copper layer with the thickness of about 0.2mm on the surface of the aluminum alloy shaft. The thickness of the brittle intermetallic compound layer is controlled within 5 mu m through a rapid process. The interface bonding strength reaches 110MPa, and the performance bonding of the dissimilar materials is realized.

Example 8

This embodiment differs from embodiment 1 in that:

the thickness of the adopted thin plate strip is 0.2mm, the laser power is 8kW, the spindle rotating speed of a machine tool is 20rpm, the plate feeding speed is 60mm/s, and the milling amount of the post-treatment of the surface of a processing shaft is 0.15mm.

The thickness of the 316 coating finally prepared on the surface of the processing shaft in the embodiment is 0.15mm, the dilution rate is 14%, and the interface bonding strength reaches 300Mpa.

Example 9

This embodiment differs from embodiment 5 in that:

The thickness of the aluminum-silicon alloy (AlSi 12) sheet strip used was 0.5mm and the laser power was 13kW.

The thickness of the aluminum-silicon alloy cladding layer finally prepared on the surface of the processing shaft in the embodiment is 0.4mm, the dilution rate is 7%, and the interface bonding strength reaches 180Mpa.

Comparative example 1

Comparative example 1 is a comparative test example of example 1 using a 2mm thick sheet, and other steps and specific parameters are the same as those of example 1.

This comparative example does not produce a surface 316 coating, specifically Bao Banhou degrees too thick, the laser melts the sheet but does not leave a micro-pool on the shaft, and 316 cannot metallurgically bond with the 45 steel shaft.

Comparative example 2

Comparative example 2 is a comparative test example of example 3 using a 1.2mm thick sheet, and other steps and specific parameters are the same as those of example 1.

This comparative example does not produce a surface 316 coating, specifically Bao Banhou degrees too thick, the laser melts the sheet but leaves a micro-pool discontinuity on the shaft, and the 316 coating has partial areas of poor bonding.

Comparative example 3

Comparative example 3 is a comparative test example of example 1 using a 0.1mm thick sheet, and other steps and specific parameters were the same as those of example 1.

The comparative example cannot prepare a surface 316 coating, specifically Bao Banhou degrees too thin, and the molten pool formed by the thin plate cannot be continuous under the processing technology that the spindle rotation speed of a machine tool is 15rpm and the plate feeding speed is 40mm/s of a shaft to be processed with the diameter of 50mm, so that a stable continuous coating cannot be left on the surface of a 45 steel shaft.

Comparative example 4

Comparative example 4 is a comparative test example of example 9 using a 0.6mm thick aluminum-silicon alloy sheet, and other steps and specific parameters were the same as those of example 9.

The aluminum-silicon alloy coating prepared in the comparative example has poor bonding, particularly, the thickness of the thin plate is thicker, and the laser melts the thin plate, but cannot leave a continuous and stable micro-molten pool on the shaft, so that the local metallurgical bonding is poor.

Comparative example 5

Comparative example 5 is a comparative test example of example 7 using a 0.15mm thick copper sheet, and other steps and specific parameters were the same as those of example 7.

The thickness of the pure copper coating prepared in the comparative example is about 0.1mm, the dilution rate is 16%, the interface bonding strength reaches 130MPa, but the higher dilution rate influences the silicon element distribution in the aluminum-silicon alloy coating, and influences the hardness and wear resistance of the coating. The increase in dilution ratio is due to the thinning of the clad sheet on the one hand and the reduction in the amount of additive on the other hand, to the increase in the portion of the laser energy that can be absorbed by the shaft, and the increase in the amount of shaft melting results in an increase in dilution ratio.

Comparative example 6

Comparative example 6 is a comparative test example of example 1, which uses a laser power of 20kW, and other implementation steps and specific parameters are the same as example 1.

The comparative example can prepare a surface 316 coating, the prepared 316 coating has a thickness of 0.3mm and a dilution rate of 40%, the interfacial bonding strength reaches 300Mpa, but an excessively high dilution rate leads to a deviation of the coating composition from the elemental composition of 316, and the corrosion resistance of the coating is reduced.

Increasing the laser power increases the dilution ratio, while the interfacial bond strength is relatively high, it is detrimental to overall performance. In the embodiment, the dilution ratio is increased on the one hand because the power of cladding is increased, the plasma of the plate is increased, the additive amount is reduced, on the other hand, the part of laser energy absorbed by the shaft body is increased, the dilution ratio is increased due to the increase of the melting amount of the shaft body, and in addition, the heat conduction speed of the steel is not as high as that of copper and aluminum, and the shaft body is easier to melt.

Comparative example 7

Comparative example 7 is a comparative test example of example 8, which uses a laser power of 5kW, and other implementation steps and specific parameters are the same as example 8.

The comparative example cannot produce a surface 316 coating, specifically the feed speed is too high, the laser power is too low, the unit energy density is insufficient, and the laser cannot melt the sheet.

Comparative example 8

Comparative example 8 is a comparative test example of example 1, which uses a spindle speed of 25rpm at the time of laser fed cladding, and other implementation steps and specific parameters are the same as in example 1.

The comparative example cannot prepare a surface 316 coating, the spindle speed is too high, the surface linear speed exceeds 50mm/s, the plate feeding speed (40 mm/s) is not matched, a molten pool formed by a thin plate is taken away by a shaft instantly, a continuous and stable coating cannot be formed, and the surface roughness after processing is guaranteed, and almost all the cladding layers are removed after the surface of the shaft is processed.

Comparative example 9

Comparative example 9 is a comparative test example of example 1, which uses a spindle speed of 5rpm at the time of laser sheet feeding cladding, and the sheet feeding speed of the sheet and strip was 20mm/s, and the other steps and specific parameters were the same as in example 1.

The comparative example can prepare a surface 316 coating, the thickness of the prepared 316 coating is 0.3mm, the dilution rate is 60%, the interface bonding strength is 270Mpa, a molten pool formed by a thin plate is not taken away by a main shaft in time, the accumulation of the molten pool absorbs a large amount of laser energy, the 45 steel surface is melted by absorbing the heat of the molten pool, and the long-time accumulation of the heat influences the performance of the 316 coating.

Comparative example 10

Comparative example 10 is a comparative test example of example 7, which uses a feed plate speed of 30mm/s lower than the spindle rotation speed of 16rpm (linear speed of about 37 mm/s) during laser feed plate cladding, and in which the molten pool formed by the thin plate is instantaneously taken away by the shaft, a continuous stable coating cannot be formed, and in which the surface of the shaft is post-processed to ensure the surface roughness after processing, almost all the cladding layer is removed, and at the same time, more brittle intermetallic compounds are generated at the bonding interface due to the more absorption of laser energy by the shaft.

Although embodiments of the present 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 therein without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims (8)

1. The surface plate feeding laser cladding method for the shaft parts is characterized by comprising the following steps of:

S1, surface pretreatment:

precisely milling the surface of a machining shaft clamped on a main shaft of a machine tool by using a milling cutter, removing surface defects and obtaining a clean surface with preset roughness;

S2, guiding and positioning the thin plate:

Selecting a metal sheet strip with the width of 15-40mm and the thickness of 0.2-1mm, leading the sheet strip out of a unreeling disc, conveying the sheet strip through a driving roller and a guide roller, enabling the sheet strip to continuously contact at an inclined angle of 20-45 degrees and pressing the sheet strip against the surface of a processing shaft processed in the step S1;

S3, shaping laser beams:

regulating and shaping the laser beam in the laser cladding head to obtain a homogenized beam with the length of 15-40mm and the width of 0.5-3 mm;

S4, laser plate feeding cladding:

Starting a machine tool spindle to drive a processing shaft to rotate at a constant speed, simultaneously starting a plate feeding mechanism to convey the thin plate strip at a constant speed, and focusing and irradiating the laser beam shaped in the step S3 on a contact area between the outer surface of the thin plate strip and the surface of the processing shaft to enable the thin plate strip to be melted on the surface of the processing shaft to form a cladding layer;

s5, cladding post-treatment:

And (3) precisely milling the surface of the cladding layer formed in the step S4 by using a milling cutter, removing the oxide layer and meeting the requirements of final size and surface roughness.

2. The method for feeding the plate to the surface of the shaft part for laser cladding according to claim 1, wherein the milling cutter in the step S1 and the step S5 and the laser cladding head in the step S4 are integrated in an automatic cutter changing system of a processing machine tool for automatic switching.

3. The method for feeding the sheet metal part to the surface for laser cladding according to claim 2, wherein in the step S3, the laser power range is 8-16kW, the surface linear speed of the processing shaft is 20-60mm/S, the feeding speed of the sheet metal strip is 20-60mm/S, and the feeding speed of the sheet metal strip is equal to or higher than the surface linear speed of the processing shaft.

4. The method for feeding the plate to the surface of the shaft part for laser cladding according to claim 3, wherein the scanning speed of the laser cladding head is 2-8mm/s.

5. The method for feeding the sheet onto the surface of the shaft part according to claim 3 or 4, wherein in the step S2, the thickness of the sheet metal strip is 0.2-1mm when the sheet metal strip is a steel strip, and the thickness of the sheet metal strip is 0.2-0.5mm when the sheet metal strip is a copper strip or an aluminum strip.

6. The method for laser cladding on the surface of shaft parts according to claim 5, wherein when the thin plate strip is copper strip or aluminum strip, the width of the homogenized beam is reduced to 0.5-1mm after the laser beam is regulated and shaped.

7. The method for carrying out laser cladding on the surface of a shaft part according to claim 1, wherein in the step S1, the first milling cutter removes a rust layer with the thickness of 0.1-0.3mm on the surface of the shaft part, repairs surface defects with the depth of less than or equal to 0.5mm, and the surface roughness Ra of less than or equal to 3.2 mu m after treatment.

8. The method for feeding the plate to the surface of the shaft part for laser cladding according to claim 1, wherein in the step S5, the cutting depth is 0.1-0.2mm, the total milling depth is not more than 20% of the thickness of the cladding layer, and the surface roughness Ra is less than or equal to 1.6 μm after treatment.