Patent Publication Number: US-2018050421-A1

Title: Hybrid Laser Cladding System

Description:
TECHNICAL FIELD 
     The present disclosure generally relates to laser cladding and, more specifically, to a hybrid laser cladding system that is capable of both powder feeding and wire feeding. 
     BACKGROUND 
     Laser cladding is a surface treatment technology used in many industries such as construction, agriculture, mining, automotive, marine, power generation, and aerospace industries. As a method of hardfacing, laser cladding may be used to apply a cladding layer that enhances various mechanical and/or chemical properties of a base material, such as the wear, erosion, abrasion, impact, corrosion, and/or oxidation resistance of the base material. In such applications, the base material/substrate surface may be metallic, and the applied cladding layer may include hard particles immersed in a metallic matrix or binder to provide an extremely hard and wear-resistant surface. 
     In a laser cladding operation, a laser may be projected onto the surface of the substrate, causing a thin layer of the substrate surface to melt and produce a localized “melt pool”. The cladding layer metal matrix/hard particles may be fed into the laser beam and melt pool to cause the cladding layer material to at least partially melt and combine with the melt pool at the substrate surface. Upon resolidification, the cladding layer may be fused to the substrate surface with a strong metallurgical bond. 
     Currently, the cladding layer material is fed into the melt pool/laser beam in either powder or wire form through a laser cladding nozzle. For example, U.S. Patent Application Number 2006/0065650 discloses a laser cladding nozzle having a hollow central projection for conveying the laser out of the nozzle through an opening, as well as powder channels that feed powdered cladding material out through the opening of the nozzle to the substrate surface. In other nozzle designs, a wire channel may be used instead of a powder channel to feed the cladding material in wire form onto the substrate surface. 
     The selection of powder or wire feeding is often determined by the material form availability, the material chemistry, the shape and size of the part, among various other considerations. However, powder and wire feeding are both associated with distinct advantages and disadvantages. For instance, wire feeding cannot support more than about 30-35% volumetric fraction of hard particles due to the limiting holding capacity of the wire. In addition, wire feeding is unidirectional, and may result in irregular cladding layer thicknesses due to poor detachment of the wire from the melt pool as may occur, for example, when applying the cladding layer by rastering. In contrast, powder feeding can support a high volumetric fraction of hard particles, and spreads on the substrate surface to provide multidirectional deposition. Moreover, powder feeding does not involve wire detachment and, therefore, may provide a smooth surface with an even thickness. On the other hand, powder feeding may be limited by material form availability, powder material chemistry, as well as the shape and size of the part to be treated. 
     Thus, a laser cladding nozzle configured for only one of powder or wire feeding may not be optimal for many applications. Accordingly, there is a need for improved laser cladding system designs. 
     SUMMARY 
     In accordance with one aspect of the present disclosure, a hybrid laser cladding nozzle configured to both powder feed and wire feed a cladding layer onto a substrate surface is disclosed. The hybrid laser cladding nozzle may comprise a central laser channel configured to project a laser beam onto the substrate surface to produce a laser beam spot thereon. The hybrid laser cladding nozzle may further comprise a powder channel coaxial to the laser channel that is configured to feed a powder material onto the laser beam spot, and at least one wire channel laterally disposed with respect to the central laser channel and the powder channel. The wire channel may be configured to feed a wire onto the laser beam spot. The laser beam spot may be configured to melt the powder material and the wire to produce the cladding layer on the substrate surface. 
     In accordance with another aspect of the present disclosure, a hybrid laser cladding system for depositing a cladding layer onto a surface of a substrate by powder feeding and wire feeding is disclosed. The hybrid laser cladding system may comprise a fixture configured to support the substrate, and a laser cladding head having a laser cladding nozzle that includes nozzle tip with a nozzle opening and a wire opening. The laser cladding nozzle may further include a central laser channel configured to project a laser beam through the nozzle opening onto the surface of the substrate to produce a laser beam spot on the surface. In addition, the laser cladding nozzle may further include a powder channel coaxial to the laser channel that is configured to feed a powder material onto the laser beam spot through the nozzle opening, and at least one wire channel laterally disposed with respect to the laser channel and the powder channel that is configured to feed a wire onto the laser beam spot through the wire opening. The laser beam spot may be configured to melt the powder material and the wire to produce the cladding layer on the surface of the substrate. The hybrid laser cladding system may further comprise a laser power supply configured to produce the laser beam, and a hot wire supply configured to preheat the wire in the wire channel. 
     In accordance with another aspect of the present disclosure, a wear component having a body with a metallic surface and a cladding layer deposited on the surface is disclosed. The cladding layer may be deposited on the surface of the wear component by a method comprising aligning a laser cladding nozzle with the surface, wherein the laser cladding nozzle includes a laser channel, a powder channel coaxial to the laser channel, and at least one wire channel laterally disposed with respect to the laser channel and the powder channel. The method may further comprise projecting a laser beam through the laser channel onto the surface of the component to produce a laser beam spot, and the laser beam spot may at least partially melt the surface to produce a melt pool at the laser beam spot. In addition, the method may further comprise feeding a wire through the wire channel onto the laser beam spot to melt the wire into the melt pool, and feeding a powder material through the powder channel onto the laser beam spot to melt the powder material into the melt pool. The wire may include a metal matrix, and the powder material may include hard particles. The method may further comprise allowing the melt pool to resolidify at the surface of the component to provide the cladding layer. 
     These and other aspects and features of the present disclosure will be more readily understood when read in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic representation of a portion of a machine having wear components, constructed in accordance with the present disclosure. 
         FIG. 2  is a side view of one of the wear components of  FIG. 1  shown in isolation, constructed in accordance with the present disclosure. 
         FIG. 3  is a cross-sectional view through the section  3 - 3  of  FIG. 1 , constructed in accordance with the present disclosure. 
         FIG. 4  is a schematic representation of a hybrid laser cladding system, constructed in accordance with the present disclosure. 
         FIG. 5  is a cross-sectional view of a hybrid laser cladding nozzle of the laser cladding system of  FIG. 4 , constructed in accordance with the present disclosure. 
         FIG. 6  is a cross-sectional view similar to  FIG. 5 , but having a plurality of wire channels, constructed in accordance with the present disclosure. 
         FIG. 7  is a cross-sectional view similar to  FIG. 5 , but having a laterally disposed powder channel, constructed in accordance with the present disclosure. 
         FIG. 8  is a cross-sectional view similar to  FIG. 5 , but having a coaxial wire channels and a laterally disposed powder channel, constructed in accordance with the present disclosure. 
         FIG. 9  is a cross-sectional view similar to  FIG. 5 , but having a coaxial wire channels, constructed in accordance with the present disclosure. 
         FIG. 10  is a bottom view of the nozzle of  FIG. 5 , illustrating a nozzle opening and a wire opening, constructed in accordance with the present disclosure. 
         FIG. 11  is a bottom view similar to  FIG. 10 , but having four wire openings distributed around the nozzle opening, constructed in accordance with the present disclosure. 
         FIG. 12  is a bottom view similar to  FIG. 10 , but having three wire openings distributed around the nozzle opening, constructed in accordance with the present disclosure. 
         FIG. 13  is a flowchart depicting a series of steps that may be involved in using the hybrid laser cladding system to fabricate a wear component having a cladding layer applied to a surface of the component, in accordance with a method of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to the drawings, and with specific reference to  FIG. 1 , a machine  10  having a plurality of wear components  12  is shown. As a non-limiting example, the machine  10  may be a cold planer, and the wear components  12  may be picks  14  displayed on a rotating drum  16  that grind and remove a paved surface  18  prior to application of a new layer of pavement. If the wear component  12  is a pick  14  for a cold planer machine, it may include a wear-resistant tip  20  and a bolster  22  for supporting the tip  20 , as shown in  FIG. 2 . The bolster  22  may include a cladding layer  23  applied to its surface that contains hard particles for increasing the wear resistance of the component  12 . However, it will be understood that the wear component  12  may be many other types of engagement tools subject to wear such as, but not limited to, an electric or non-electric shovel, as well as various cutting or abrading tools, rotating blades, and scraping structures that may be hand-held or associated with a machine. 
     The material construction of the wear component  12  is depicted in  FIG. 3 . The wear component  12  may include a body or substrate  24  that is formed from a metallic material such as a metal, a metal alloy, or a metal composite material. Applied to a surface  26  of the substrate  24  may be the cladding layer  23  that serves to enhance the wear resistance of the component  12 . The cladding layer  23  may have a thickness ranging from about 0.1 millimeters (mm) to about 10 mm, although the thickness may deviate from this range in some circumstances. The cladding layer  23  may be a composite material that includes one or more hard particles immersed in a metal matrix. As used herein, a “hard particle” is substance having a Vickers hardness of more than about 700 and a size of less than about 3 mm. For instance, the hard particles may be selected from various carbide particles, such as tungsten carbide or chromium carbide, as well as various boride particles, nitride particles, diamond pellets, or combinations thereof. The metal matrix may function as a binder between the surface  26  and the hard particles. Suitable metal matrix compositions may be selected from a range of metals and metal alloys including, but not limited to, iron, nickel, cobalt, titanium, aluminum, alloys of the any of the aforementioned metals, and combinations thereof. 
     Turning to  FIG. 4 , a hybrid laser cladding system  29  that may be used to deposit the cladding layer  23  onto the substrate surface  26  is shown. The hybrid laser cladding system  29  may be configured to apply the cladding layer  23  by either or both of powder feeding and wire feeding. The laser cladding system  29  may include a laser cladding head  30  having a hybrid laser cladding nozzle  32 . The hybrid laser cladding nozzle  32  may be configured to project a laser beam  36  onto the substrate surface  26 , as well as to feed the cladding layer material onto the surface  26  in either or both of powder form and wire form (i.e., as one or more wires  38 ). By co-feeding both wire and powder, the system  29  may be capable of high deposition rates of at least 20 pounds per hour or more. 
     The system  29  may further include a fixture  34  for supporting the substrate  24 , a powder feeder  40  for supplying powder material to the nozzle  32  via one or more supply conduits  42 , as well as one or more wire feeders  44  for feeding the wire(s)  38  to the nozzle  32 . Connected to the cladding head  30  may also be a laser power supply  46  which serves as an energy source for producing the laser beam  36 . Furthermore, the system  29  may also include a hot wire power supply  48  in connection with the cladding head  30  to preheat the wire(s)  38 , such as by resistive heating, to a temperature below its melting point prior to deposition on the substrate surface  26 . Preheating of the wire(s)  38  in this way may reduce the energy input required by the laser beam  36  to melt the wire(s)  38 . 
     Optionally, a controller  50  may be in electrical communication with one or more of the wire feeder(s)  44 , the powder feeder  40 , the laser cladding head  30  (and the nozzle  32 ), the laser power supply  46 , the hot wire power supply  48 , and the fixture  34  for automated control thereof. Namely, the controller  50  may control numerous parameters of the laser cladding operation such as the laser power via the laser power supply  46 , the preheated temperature of the wire(s)  38  via the hot wire power supply  48 , the rate of powder and wire feeding through the powder feeder  40  and the wire feeder(s)  44 , respectively, as well as the movement of the fixture  34 /substrate  24  relative to the nozzle  32 . Moreover, the controller  50  may control whether the system  29  deposits the cladding layer  23  by powder feeding, wire feeding, or by a combination of powder and wire feeding by activating and deactivating the powder feeder  40  and the wire feeder(s)  44  accordingly. In alternative arrangements, the laser cladding system  29  may be manually controlled. For example, the system  29  may include one or more user-actuatable switches  52  that permits a user to select between powder feeding, wire feeding, and a combination of powder feeding and wire feeding. Likewise, the system  29  may also include various other switches/controls that enable a user to select the laser power, the feed rates of the powder feeder  40  and the wire feeder(s)  44 , and the movement of the head  30 /nozzle  32  with respect to the fixture  34 /substrate  24 . 
     In operation of the laser cladding system  29 , the laser beam  36  may be projected onto the substrate surface  26  through the nozzle  32  to produce a laser beam spot  54  on the surface  26 . The laser beam spot  54  may at least partially melt a thin layer of the surface  26 , producing a melt pool  56 . As the laser beam  36  is projected onto the surface  26 , the cladding layer material (as a powder material and/or as one or more wires  38 ) may be fed into the laser beam spot  54  and the melt pool  56  through the nozzle  32 , allowing the cladding layer material to at least partially melt and combine with the melt pool  56 . Upon resolidification, the cladding layer  23  may be fused with the surface  26  of the substrate  24  with a strong metallurgical bond therebetween. The fixture  34 /substrate  24  and the nozzle  32  may be moved with respect to each other to cover the desired area of the surface  26  with the cladding material and/or to build up the thickness of the cladding layer  23 . In some arrangements, the fixture  34 /substrate  24  may be moved relative to the nozzle  32  with the nozzle  32  held stationary. In other arrangements, the nozzle  32  may be moved relative to the fixture  34 /substrate  24  while the fixture  34  and the substrate  24  are held stationary. 
     The hybrid laser cladding nozzle  32  is shown in cross-section in  FIG. 5 . As shown, the laser cladding nozzle  32  may include a central laser channel  58  that projects the laser beam  36  onto the substrate surface  26  through a nozzle opening  60  at a tip  62  of the nozzle. An optical focusing device, such as one or more lenses  64 , may be disposed in the laser channel  58  for focusing the laser beam  36  on the substrate surface  26 . In addition, coaxial to the central laser channel  58  may be one or more powder channels  65  that feed a powder material  68  into the laser beam  36  and the melt pool  56  through the nozzle opening  60 . Furthermore, as will be understood by those with ordinary skill in the art, an inert carrier gas such as argon, nitrogen, or helium may be used to carry the powder material  68  through the powder channel  65  and into the melt pool  56 . 
     Laterally disposed with respect to the laser channel  58  and the powder channel  65  may be a wire channel  70  that feeds one or more wires  38  into the laser beam  36  and the melt pool  56 . The wire  38  may exit the wire channel  70  and the nozzle  32  through a wire opening  72  at the tip  62  that is separate from the nozzle opening  60 . To allow multidirectional wire feeding, the nozzle  32  may optionally include a plurality of wire channels  70  laterally distributed around the laser channel  58  and the powder channel  65 , and each of the wire channels  70  may be configured to feed its respective wire(s)  38  through a separate wire opening  72  surrounding the nozzle opening  60  (see  FIG. 6  and further details below). 
     In other alternative arrangements, the nozzle  32  may include a laterally disposed powder channel  65  in addition to or in place of the coaxial powder channel, as shown in  FIG. 7 . As yet another alternative, one or more wire channels  70  may be coaxial to the laser channel  58  and one or more powder channels  65  may be laterally disposed, as shown in  FIG. 8 . In another arrangement, both the powder channel  65  and one more wire channels  70  may be coaxial to the laser channel  58 , as shown in  FIG. 9 . Variations such as these also fall within the scope of the present disclosure. 
     As will be understood by those with ordinary skill in the art, the nozzle  32  may also include additional features such as one or more cooling channels for cooling the nozzle  32 , and/or one or more shielding gas channels for shielding the laser beam  36  and the powder and/or wire cladding material with an inert gas as it is projected to the substrate surface. 
     The hybrid laser cladding nozzle  32  disclosed herein offers many advantages over laser cladding nozzles of the prior art that are limited to either powder feeding or wire feeding. By combining powder feeding and wire feeding, the laser cladding nozzle  32  disclosed herein offers the opportunity to blend cladding materials available in powder and wire form. For instance, as wire feeding alone has a low capacity for hard particles, a cladding layer  23  with a high hard particle content (more than about 35% by volume) may be produced by co-depositing or subsequently depositing hard particles in powder form. Moreover, powder feeding may be leveraged during or after wire deposition to smoothen out and improve the thickness uniformity of an uneven surface caused by poor wire detachment from the melt pool. Powder feeding may also be leveraged to provide multidirectional deposition of the cladding materials that cannot be realized with single wire feeding alone. Multidirectional deposition may also be realized by feeding the wires  38  onto the surface through multiple wire channels  70  laterally distributed around the laser channel  58 , as described above. 
     Turning now to  FIG. 10 , the nozzle tip  62  of the nozzle  32  of  FIG. 5  is shown. If the nozzle  32  includes a single wire channel  70 , the nozzle tip  62  may have one wire opening  72  through which the wire  38  exits the wire channel  70  and the nozzle  32 . The wire opening  72  may be located radially outward of the nozzle opening  60  through which the laser beam  36  and the powder material  68  exit the nozzle. Alternatively, if the nozzle  32  includes a plurality of wire channels  70 , the nozzle tip  62  may have a separate wire opening  72  for each of the wire channels  70 . For example, the nozzle  34  may have four wire channels  70  equally spaced and laterally distributed around the laser channel  58  and the powder channel  65 , and the nozzle tip  62  may have four wire openings  72  equally distributed around the nozzle opening  60 , as shown in  FIG. 11 . In this arrangement, the wire openings  72  may be spaced by about 90° from each other around the nozzle opening  60 . In another alternative arrangement, the nozzle  32  may have three wire channels  70  equally distributed around the laser channel  58  and the powder channel  65 , such that the tip  62  includes three wire openings  72  equally distributed (by about 120°) around the nozzle opening  60  (see  FIG. 12 ). It will be understood that the nozzle tip arrangements depicted in  FIGS. 10-12  are non-limiting examples, and that the nozzle  32  may have any number of wire channels  70  and wire openings  72 . Furthermore, in some cases, the wire channels  70 /wire openings  72  may be unequally spaced or asymmetrically positioned about the nozzle  32  and the nozzle tip  62 . 
     INDUSTRIAL APPLICABILITY 
     In general, the teachings of the present disclosure may find applicability in many industries including, but not limited to, industries using components with cladding layers. More specifically, the teachings of the present disclosure may be applicable to any industry relying on laser cladding to produce wear-resistant cladding layers on wear components. 
       FIG. 13  shows a series of steps that may be involved in applying the cladding layer  23  to the wear component  12  using the laser cladding system  29 . The head  30 /nozzle  32  of the system  29  may be aligned with the surface  26  of the substrate  24 , and the laser beam  36  may be projected through the laser channel  58  to produce the laser beam spot  54  on the surface  26  according to the blocks  80  and  82 . The laser beam spot  54  may at least partially melt the surface  26  of the substrate  24  to produce the melt pool  56 . During the block  82 , one or more preheated wires  38  may be fed into the laser beam spot  54  through one or more of the wire channels  70  according to a block  84 . The wire(s)  38  may contain the metal matrix and a low content of hard particles (less than about 35% by volume), and may melt and blend with the melt pool  56 . To build up the hard particle content beyond the holding capacity of the wire(s)  38 , the powder material  68  containing hard particles may be fed through the powder channel  65  into the laser beam spot  54 /melt pool  56  according to a block  86 . Optionally, the powder material may also contain a metal matrix of a same or different composition as the metal matrix of the wire(s)  38 . The blocks  84  and  86  may be carried out simultaneously, or separately. As a non-limiting example, the cladding layer  23  may be fabricated by first applying the wire(s)  38  to the surface  26  through the wire channel  70  (block  84 ), followed by one or more final passes with the powder material  68  through the powder channel  65  (block  86 ) to boost the hard particle content in the melt pool  56 . Following application of the powder material  68  and the wire(s)  38 , the melt pool  56  may be permitted to cool and resolidify to provide the cladding layer  23  fused and bonded to the surface  26  of the substrate  24  (block  88 ). It will be understood that the method of  FIG. 13  may be adapted to blend other types of powder and wire compositions as well. For instance, different metal matrices and/or hard particles may be blended via deposition through different wire channels  70  and/or the powder channel  65 . Alternatively, it may be adapted to improve the thickness uniformity and/or the smoothness of a cladding layer deposited by rastered wire deposition by using simultaneous or subsequent powder feeding. Many other adaptations such as these are also encompassed within the scope of this disclosure. 
     The hybrid laser cladding system disclosed herein permits deposition of cladding layers via either or both of powder feeding and wire feeding. Simultaneous powder feeding and wire feeding may allow for higher deposition rates than can be achieved with just powder or wire feeding alone. In addition, as disclosed herein, the hybrid laser cladding system may be used to deposit cladding layers with hard particle contents well above the holding capacity of wire (about 35% by volume) by allowing the simultaneous or subsequent deposition of hard particles in powder form. Thus, the wear-resistance and/or abrasive properties of the resulting cladding layers may be significantly improved over cladding layers fabricated by wire feeding alone. Alternatively or in combination with this, compositional gradients in the cladding layer may be produced with the hybrid nozzle by gradually increasing the feeding rate of the powder or wire material. Moreover, multidirectional deposition may be achieved by either or both of powder feeding and wire feeding though multiple wire channels distributed around the nozzle. The hybrid nozzle also allows rough and uneven surfaces caused by wire feeding to be corrected with simultaneous or subsequent powder feeding. Further, components having distinct core and surface composition may be fabricated using by first building the core of the component by wire feeding, and then depositing an outer layer of distinct composition by powder feeding. Many possibilities such as these may be envisioned. It is expected that the technology disclosed herein may find wide industrial applicability in a wide range of areas such as, but not limited to, additive manufacturing, road construction, construction, agriculture, mining, automotive, marine, power generation, and aerospace applications.