WO2009039753A1 - Method for feeding wire in laser and cladding and in-laser wire feeder - Google Patents

Abstract

An in-laser wire feeder using a method for feeding wire in laser and cladding is provided. A laser beam (11) emitted from a laser apparatus is transformed into an annular light beam (15) by a conic mirror (24) and is focused into an annular conic light beam (16) by an annular focusing mirror (28). A conic hollow lightless area (17) is formed in the annular conic light beam (16). A tube (18,18') of the wire feeder is mounted in the lightless area (17) and coaxial with the annular conic light beam (16). A wire (14) is transferred coaxially and vertically into a molten bath on a machined surface in the center of the annular conic light beam (16) in operation, to realize to coaxially feed the wire in laser. Each direction of feeding wire in laser is consistent and is not effected by scanning directionality and unfocusing fluctuation. The coupling between the laser and the wire is continuously stable. The quality of crucible zone is high. The method and device can be used in laser cladding of metal material, fast molding of three-dimensional entity, laser weld and special connection, and laser repair and laser reproduction, etc.

Description

 Laser light inner wire feeding method and optical inner wire feeding device

 The invention belongs to the field of laser processing, and particularly relates to a laser cladding forming manufacturing process method and a device for realizing the same. Background technique

 In the advanced laser processing and forming manufacturing technology, there is a key technology, that is, the laser and the material to be melted are synchronously transmitted to the processing and forming position, and the metal material is continuously, accurately and uniformly put into the processing surface and the scanning motion is performed according to a predetermined trajectory. Within the spot, precise coupling of the light material is achieved. The material converts light energy and thermal energy in the beam, instantly melts and forms a molten pool, and completes the metallurgical process of rapid melting and solidification of the material. Most of the current feeding methods at home and abroad are synchronous powder feeding. The earliest method was vertical laser beam irradiation, and the powder feeding tube was tilted sideways from one side. The side-by-side feeding attitude varies with the scanning direction, and the scanning direction has a great influence on the scanning quality. The more advanced powder feeding devices include US patent (US5961862) and European patent (W0200502815 1). The basic structure adopts a structural scheme of uniformly arranging multiple powder feeding nozzles on the periphery of the laser beam, which can be called "out-of-optical coaxial". Send powder". The external coaxial powder feeding has the same powder feeding attitude in all directions, eliminating the influence of the scanning directivity, but at the same time bringing a new problem that the multiple powder bundles are difficult to converge at one point and coincide with the beam focus.

There are some shortcomings in the powder feeding method, which are difficult to control the powder feeding and uniformity, and the powder utilization rate is low. The powder in the semi-molten state which is emitted outside the beam easily adheres to the surface of the molded part, affecting the surface. Quality and so on. In contrast, wire feeding can avoid some of the problems associated with powder feeding. Wire feeding has the advantages of easy realization of precise control, high feeding precision, high material utilization rate, no divergence, high energy utilization rate, no pollution to the environment, low cost and other obvious advantages. However, at present, there are still many problems in the wire feeding and cladding process which have not been well solved, and it is not possible to realize multi-channel surrounding beam for multi-channel coaxial wire feeding like the optical external coaxial powder feeding. As shown in FIG. 1, in the conventional laser wire feeding or welding method, the laser beam 11 emitted by the laser is focused by the focusing mirror 110 into a cone beam 12, and the wire feeding tube and the spinning nozzle 13' can only The wire 14 fed by the spinneret 13' can only be tilted into the laser beam when the angled beam 12 is tilted at an angle. Generally, the wire needs to be adjusted to intersect the beam at the spot position before processing (Reference: 1, King to the Lord Edited. China Materials Engineering Dictionary Volume 25. Beijing: Chemical Industry Press, 2006; 2, Zuo Tiewei Editor-in-Chief. 21st Century Advanced Manufacturing - Laser Technology and Engineering. Beijing, Science Press, 2007, 5;

3. Waheed UI Haq Syed, Lin Li. Effects of wire feeding direction and location in multiple layer diode laser direct metal deposition. Applied Surface Science, 24 March 2005). The biggest drawback of the single-sided ribbon feeding is that the wire is inclined into the molten pool, and the heat of the beam, the heat transfer of the molten pool and the radiation are asymmetric and uneven. Especially when the directional change inevitably occurs in the cladding, that is, when the laser beam is scanned in different directions with respect to the processing surface during processing, the beam and the wire have different orientations and postures relative to the scanning motion direction, and the filament is melted and The effect of the heat and force of the molten pool will change, so that the size, shape and surface roughness of the melted channel will be greatly changed, and even the intermittent process of the melting process will occur. There is no directional influence on the single-layer or multi-layer cladding surfacing of the ordinary single-direction scanning in the side wire, because the feeding azimuth angle does not change, and the complex surface surfacing, especially the three-dimensional direct rapid forming process In fact, since the scanning trajectory and direction are constantly changing, the influence is very prominent, and the continuity of the cladding or the quality of the melt is difficult to ensure. In addition, the wire feeding point must be coincident with the beam focus position at the surface of the workpiece at the time of cladding, and the intersection point should be limited to the next small area on the surface of the molten pool, but if the intersection is in the processing relative to the machined surface ( Or the molten pool) There are fluctuations and changes in the upper and lower positions (inevitably in the multi-layer accumulation), the thermal action of the wire will change again, and the melting process of the wire may be intermittent, the front part of the wire is bent, the light and the wire Intermittent alignment and misalignment, so that the continuity of the cladding process and the quality of the melt are very sensitive to small changes in the relative position between the focus and the machined surface. In addition, the laser cladding process often needs to transport an inert protective gas around the molten pool to blow the hot flame, slag, etc. generated by the cladding, thereby protecting the lens of the cylinder from contamination, and the molten pool is not oxidized. In the prior art lateral wire feeding device, due to the structural limitation, the shielding gas can only be blown laterally, the blowing pressure on the molten pool is not uniform, the airflow is disordered, and the protection effect is poor. Summary of the invention

There is a need for a new wire feeding process and a device for realizing the same, which can realize coaxial wire feeding with a beam, and eliminate the influence of scanning directivity; there is no problem that wire gathering is difficult, and beam focus is difficult to overlap. Insensitive to factors such as the volatility of the focus of the workpiece relative to the plane position of the workpiece, The process is more stable; the wire is surrounded by the light beam, and the wire is unilaterally heated to surround the wire, and the wire is uniformly surrounded by 3⁄4, so that the 苴 is 3⁄4, solidified uniformly and melted more easily, and the microstructure of the cladding layer can be improved.

 The laser light internal wire feeding method of the invention is: cutting and transforming a laser beam emitted by a laser into a ring beam by using a light dividing principle, and then focusing the ring beam into a ring cone: a beam, which is generated in the ring cone beam a conical hollow matte zone, a single wire is placed in the dull zone and coaxial with the ring-cone beam, the wire is fed by the wire feed tube, and is output through the spinneret at the lower end. The focus of the beam is surrounded by the lower portion of the cone-shaped beam and then heated and melted under the action of illumination and heat transfer of the processing surface to sag into the molten pool, and the surface of the substrate to be cladding is adjusted to the focus. In the vicinity, the wire melted into the molten pool surface of the substrate forms a molten pool together with the partially melted surface material of the substrate, and the melt in the molten pool forms a melting channel along with the relative dynamic solidification of the light beam and the substrate.

 A protective gas passage is disposed in the wire feeding tube: the shielding gas transported by the protective gas passage surrounds the wire material under the nozzle to form an air curtain and is coaxially sprayed to the molten pool, and the protective gas passage is coaxial with the spinneret and the ring-shaped cone beam line.

 The laser light inner wire feeding method of the invention realizes the laser light inner wire feeding device by special laser light internal feeding device, including a cylinder body, a reflection, a sending nozzle, and the like, and a light inlet port is arranged above the partial cylinder body, and a light exit port is arranged below The reflection is a conical mirror that can cut and convert the incident beam into a ring beam, and the focusing mirror is a ring-shaped reflection focusing mirror that can reflect the ring beam into a cone-shaped beam, the conical mirror and the annular reflection focusing mirror and the body The entrance and exit ports are coaxial. The conical mirror is fixed to the center of the cylinder, and its mirror surface faces the entrance pupil. The annular reflection focusing mirror is fixed on the inner wall of the cylinder, and the mirror surface and the cone reflection: the mirror surface of the mirror is opposite to the lower portion of the cylinder. a single wire feeding tube is inserted from the outside of the cylinder into the nozzle of the end of the wire feeding tube in a conical hollow matt region of the ring-shaped cone beam, and the nozzle and the ring-shaped beam coaxial line are sprinkled out. Position close to the focus of the ring cone beam.

The wire feeding tube is formed into a double-layered casing structure, wherein the middle pipe is used for conveying the wire, and the sandwich pipe is for protecting the gas passage. When the wire feeding tube reaches the hollow region from the outside of the ring-shaped cone beam, it needs to cross the beam locally to avoid the wire feeding tube from reflecting light and overheating. The light-incident surface of the feeding tube is coated with a light-absorbing material and a cooling channel absorption beam is disposed inside the wire feeding tube. . Since the wire feeding area of the wire feeding tube is small, The conical mirror is secured by at least one rib attached to the inner wall of the barrel. The wire feeding tube can enter from the upper part of the cylinder, pass through the gap between the conical mirror and the annular reflecting focusing mirror, and after reaching the back of the conical mirror, turn into a coaxial line with the beam; or enter from the lower part of the middle part of the barrel to reach The back of the conical mirror turns to be coaxial with the beam. Because the ribs are in the light-irradiated area, in order to prevent the ribs from reflecting light and overheating, the glazing surface is coated with a light absorbing material, and a cooling channel is provided inside to absorb heat. Since the glazing has a small area of illumination, its loss of beam energy is negligible.

光束再进行反射并聚焦， 形成一环锥形光束。 此环锥形光束中部 形成了 锥形中空无光区。 单根送丝管即可由筒体上部或中部侧面进入此 无光区内，， 实现从激光束内部送丝， 即所谓 "光内送丝"。 The working principle of the laser light inner wire feeding device is as follows: The laser beam emitted by the laser enters the cylinder from the light entrance port and is incident on the mirror surface of the central conical mirror of the cylinder body. The conical mirror surface cuts and reflects the light beam, and transforms the shaped beam into the ring shape. On the mirror surface of the focusing mirror, the ring is reversed: the focusing mirror will be incident

The beam is then reflected and focused to form a ring-shaped cone of light. A cone-shaped hollow matte region is formed in the middle of the ring-shaped cone beam. A single wire feeding tube can enter the light-free area from the upper or middle side of the cylinder, and realize the wire feeding from the inside of the laser beam, that is, the so-called "in-light wire feeding".

化时， 光束和丝材相对扫描运动方向的方位和姿态完全相 同， 丝材的熔融和熔池的热作用和力作用过程理论上不发生变化， 完全消 除了扫描方向性带来的影响。 另一方面， 光束相对熔池上下波动产生离焦 时， 丝材可始终对准光斑和熔池的中心， 光斑和丝材不会错位。 这样， 丝 材与熔池受热作用的方式保持不变， 使热作用保持均匀、 稳定。 在扫描光 束相对加工面三维位置变化影响下， 丝材与熔池之间的作用力恒为正向， 丝材不造成偏歪， 有利于熔池驱动力均衡和熔体流动对称。 同时， 丝材下 段和加工表面始终受到均匀对称的激光辐照和熔池的热作用， 均匀的受热 和凝固过程可大大提高熔道质量。 本发明可克服现有侧向送丝激光熔覆工 艺方法带来的进丝和方位复杂； 进丝方位变化造成热作用方式和堆积质量 差距大、 不稳定； 三维扫描加工时熔层方向性缺陷明显； 离焦易造成光、 丝错位， 熔融不连续， 熔道质量不稳定等诸多不足。 The laser light inner wire feeding method and the optical inner wire feeding device of the invention can: achieve the following beneficial effects: a hollow annular focused beam is obtained by optical path transformation, and the wire feeding tube is placed in a hollow portion of the focusing beam and coaxial with the beam, processing The center wire and the focused beam are forwardly fed into the center of the spot, and the wire is always uniformly surrounded by the ring beam. During the cladding process, no matter how the relative direction of movement of the wire and beam relative to the machined surface (melt pool) changes, such as when the beam is scanned in a three-dimensional cladding process

When the beam and the wire are in the same orientation and posture with respect to the scanning motion direction, the melting of the wire and the thermal action and the force action of the molten pool do not theoretically change, completely eliminating the influence of the scanning directivity. On the other hand, when the beam is fluctuating from the upper and lower sides of the molten pool, the wire can always be aligned with the center of the spot and the molten pool, and the spot and the wire are not misaligned. In this way, the way in which the wire and the molten pool are heated is kept constant, so that the heat effect is kept uniform and stable. Under the influence of the three-dimensional position change of the scanning beam relative to the processing surface, the force between the wire and the molten pool is always positive, and the wire does not cause hemiplegia, which is beneficial to the balance of the driving force of the molten pool and the symmetry of the melt flow. At the same time, the lower part of the wire and the machined surface are always subjected to uniform symmetrical laser irradiation and the heat of the molten pool, and the uniform heating and solidification process can greatly improve the quality of the melt. The invention can overcome the complicated wire feeding and orientation caused by the existing lateral wire feeding laser cladding process method; the change of the wire orientation causes a large difference between the heat action mode and the stacking quality, and is unstable; the directional defect of the molten layer during the three-dimensional scanning process Obvious; defocusing easily causes light, The wire is misplaced, the melting is discontinuous, the quality of the melt is unstable, and so on.

 In the in-light wire feeding scheme, it is convenient to realize the integration of the light, the wire and the shielding gas integrally, so that the inert shielding gas surrounds the wire to form a protective air curtain to be blown vertically to the surface of the molten pool. Compared with the prior art lateral blowing shielding gas, the vertical coaxial blowing airflow is easy to form a laminar flow, and the blowing pressure to the molten pool is uniform, and the protection effect is good. DRAWINGS

 1 is a conventional laser cladding technology optical external wire feeding method

2 is a view showing the original method of laser cladding optical internal wire feeding according to the present invention;

 Figure 3 is a structural view of a laser cladding optical internal wire feeding device;

 Figure 4 is a wire feeding tube diagram of a double-layered casing structure;

 Fig. 5 is a structural view of the laser cladding optical inner wire feeding device when the wire feeding tube enters from the middle of the cylinder. In the figure: 1 1 - a laser beam emitted by a laser; 12 - 1 optical external wire to focus the cone beam; 13 - a light inside the inner wire feeding device nozzle; 13 ' - light delivery Wire device nozzle; 14 - wire; 15 - a ring of circular beam; 16 - ring cone beam; 17 - cone hollow beam; 18, 18, one - one Send wire tube; 181 - wire feeding tube cooling channel; 182 - wire feeding tube face; 19 a focus; 2200 - protective air curtain; 21 - light port; 22 - tube Body; 23 - ribs; 231 - rib cooling water channel; 232 - ribs face; 24 - cone mirror; 26 - light exit; 28 - ring reflection focusing mirror; 31 - wire feeding Pipe intermediate pipe; 32 - wire feeder pipe. 100——substrate 1 10——focusing mirror

 Application Example 1:

Refer to Figures 2 and 3. As shown in FIG. 3, the laser light inner wire feeding device has a light inlet port 21 above the cylinder 22 and a light exit port 26 below, and the light entrance port 21 and the light exit port 26 are coaxial. The center of the cylinder 22 is uniformly designed with three ribs 23 connected to the inner wall of the cylinder 22. The rib 23 is fixed with a conical mirror 24, and the conical mirror of the conical mirror 24 faces the entrance port 21 and is coaxial with the line. The conical mirror 24 cuts and reflects the incident laser beam 11 into a circular beam 15. An annular reflection focusing mirror 28 is also mounted on the inner wall of the cylinder 22 coaxially with the conical mirror 24, the mirror surface of which faces the conical mirror 24. Circumferential mirror 24 reflection ring The shaped beam 15 is incident on the annular reflecting focusing mirror 28, and is reflected by the annular reflecting focusing mirror 28 to be focused into a conical cone focusing beam 16, and a conical hollow matte region 17 and a focus 19 are formed in the conical cone focusing beam 16, the focus 19 is outside the light exit 26. A single wire feeder 18 is inserted from the outside of the barrel 22, passes through the gap between the conical mirror 24 and the annular reflection focusing mirror 28, reaches the back surface of the conical mirror 24, and is rotated coaxially with the ring-cone beam 16, so that the wire is fed. A spinneret 13 at the end of the tube 18 is placed in the conical hollow matte zone 17 of the ring-shaped cone beam 16 and is coaxial with the ring-shaped cone beam 16. The outlet end of the spinneret 13 is located near the focus 19 of the annular cone beam 16. The wire 14 is fed from the wire feed tube 18, output through the spinneret 13 at the lower end of the wire feed tube 18, surrounded by the lower portion of the ring-shaped cone beam 16 near the focus 19, and then illuminated to the surface of the substrate 100. The molten pool heat conduction, heat radiation, etc. are heated and continuously melted to enter the molten pool vertically, and the surface of the substrate 100 to be clad is adjusted to the vicinity of the focus 19, and the molten material is melted into the molten pool and partially melted. The substrate skin materials together form a molten pool, and the melt in the molten pool continuously solidifies as a result of the relative movement of the light beam 16 and the substrate 100 to form a melt channel.

 The illuminating surface 232 above the rib 23 is coated with a light absorbing material, and a cooling water passage 231 is disposed inside the rib. The rib structure can effectively reduce the light-up area and reduce the light loss. The light-incident surface 182 of the wire feeding tube 18 in the cylindrical body 22 is coated with a light absorbing material, and a cooling water passage 181 is disposed inside. Since the glazing and wire feeding tubes have a small area of illumination, their loss of beam energy is negligible. Application Example 2:

 Refer to Embodiment 1 and Figure 4. In the first embodiment, the wire feed tube 18 is constructed as a coaxial double-sleeve structure. The intermediate pipe 31 is for conveying the wire, and the sandwich pipe 32 is for shielding the gas passage. The shielding gas passes through the interlayer pipe 32 and surrounds the wire 14 through the spinneret 13 to form a protective gas curtain 20 to be sprayed toward the molten pool. Application Example 3:

 Refer to Embodiment 1 or Embodiment 2 and Figure 5. In the first embodiment or the second embodiment, the wire feeding tube 18 enters from a position below the middle rib 23 of the cylindrical body 22, and reaches the back surface of the conical mirror 24 to be coaxial with the ring-shaped cone beam 16.

Claims

Claim A laser light inner wire cladding method, the main feature of which is: cutting and transforming a laser beam emitted by a laser into a ring beam by using a light splitting principle, and then focusing the ring beam into a ring-shaped beam, in the ring A conical hollow matt zone is formed in the cone beam, a single wire feeding tube is placed in the dull zone and coaxial with the ring cone beam, and the wire is fed from the wire feeding tube through the lower end of the wire feeding tube The nozzle output of the part is surrounded by the lower part of the cone-shaped beam near the focus of the beam, and then heated and melted under the action of the illumination and the heat transfer of the molten pool of the processing surface, and vertically enters the molten pool, waiting for The surface of the clad substrate is adjusted to the vicinity of the focus, and the wire melted into the molten pool of the substrate surface and the partially melted substrate surface material together form a molten pool.  2. The laser light inner wire cladding method according to claim 1, wherein: the wire feeding tube has a shielding gas passage, and the shielding gas conveyed by the shielding gas passage surrounds the wire material under the spinning nozzle to form an air curtain. The coaxial jet is sprayed to the molten pool, and the protective gas passage is coaxial with the spinneret and the ring-shaped beam.  3. A laser light inner wire feeding device for laser light inner wire feeding, comprising a cylinder body, a mirror, a focusing mirror, a wire feeding tube and a spinneret, etc., the upper side of the cylinder body has an optical entrance, and the lower part has a light exit port, wherein: the mirror is a conical mirror that can cut and convert an incident beam into a ring beam, and the focusing mirror is a ring-shaped reflection focusing mirror that can reflect and focus the ring beam into a ring-shaped beam. The conical mirror and the annular reflection focusing mirror are coaxial with the light entrance port and the light exit port of the cylinder body, the conical mirror is fixed at the center of the cylinder body, the mirror surface faces the light entrance port, and the annular reflection focusing mirror is fixed on the inner wall of the cylinder body, and the mirror surface thereof Opposite the mirror surface of the conical mirror, and facing the light exit port of the lower part of the cylinder, a single wire feeding tube is inserted from the outside of the cylinder, and the nozzle of the end of the wire feeding tube is placed in the conical hollow of the ring-shaped cone beam In the optical zone, the spinneret is coaxial with the cone-shaped beam, and the outlet of the spinneret is close to the ring of the cone-shaped beam.  4. The laser light inner wire feeding device according to claim 3, wherein: the wire feeding tube is a double-layered sleeve structure, the intermediate pipe conveys the wire material, and the sandwich pipe is a protective gas passage.  The laser light inner wire feeding device according to claim 3 or 4, wherein the conical mirror is fixed to the center of the cylinder by at least one rib, and the illuminating surface of the rib is coated with a light absorbing material, and the inside of the rib A cooling water channel is set. 6. The laser light inner wire feeding device according to claim 3 or 4, wherein: the wire feeding tube is The upper part of the cylinder enters, passes through the gap between the conical mirror and the annular reflection focusing mirror, and reaches the back of the conical mirror and then turns into a coaxial line with the beam. The feeding surface of the feeding tube is coated with a light absorbing material, and a cooling water channel is inside.  7. The laser light inner wire feeding device according to claim 5, wherein the wire feeding tube enters from a position below the middle rib of the cylindrical body, and reaches a coaxial line with the light beam after reaching the back surface of the conical mirror.