CN107287590A - Laser Direct Structuring Coaxial Powder Feeding Nozzle with Active Adjustment of Coaxial Powder - Google Patents

Abstract

The invention discloses a laser direct forming optical powder active adjustment coaxial powder feeding nozzle, relates to the field of additive manufacturing, and particularly relates to a laser direct forming optical powder active adjustment nozzle. The coaxial powder feeding nozzle of laser direct forming's powered active adjustment includes: the device comprises a laser defocusing amount adjusting mechanism, a connecting sleeve and a powder defocusing amount adjusting mechanism; the laser defocusing amount adjusting mechanism is arranged at the upper part of the inner side of the connecting sleeve; the powder defocusing amount adjusting mechanism is arranged in the middle and at the lower part of the outer side of the connecting sleeve. The invention has the characteristics of novel structure, simple and convenient processing, convenient use, independent adjustment of light spots and powder spots, realization of size matching of the light spots and the powder spots and the like, and belongs to a novel laser direct-forming light powder active adjustment coaxial powder feeding nozzle which integrates economy and practicability.

Description

Laser Direct Structuring Coaxial Powder Feeding Nozzle with Active Adjustment of Coaxial Powder

technical field

The optical powder active adjustment coaxial powder feeding nozzle for laser direct forming according to the present invention relates to the field of additive manufacturing, and specifically relates to an active optical adjustment nozzle for laser direct forming.

Background technique

With the increasingly urgent demand for precision and complex parts in the aerospace, nuclear energy, and ocean engineering manufacturing industries, the emerging additive manufacturing technology is developing rapidly in the manufacture of complex parts due to its flexibility and high efficiency. The existing metal laser additive manufacturing mainly has the following three methods: powder spreading type, coaxial powder feeding type and side shaft powder feeding type. Compared with the other two methods, the coaxial powder feeding type is flexible, fast, and Good quality and other advantages. The efficiency and quality of laser coaxial powder-feeding additive manufacturing depend on laser process parameters such as laser power and spot size, and gas-powder flow process parameters such as powder tube angle and powder spot size. However, when the laser spot size is larger than the powder spot size, the energy density will be too large, and defects such as pores are likely to occur, which will affect the quality of additively manufactured parts; when the laser spot size is smaller than the powder spot size, the air powder flow will not be completely transported Melt pool, powder utilization rate is low, reducing the efficiency of additive manufacturing.

At present, the existing coaxial powder feeding nozzles are divided into multi-channel coaxial powder feeding nozzles and conical ring type coaxial powder feeding nozzles. The coaxial powder feeding nozzle can adjust the laser spot size by adjusting the laser defocus, but the structure of the inner flow channel in this design is complex, the uniformity and convergence of the air and powder flow at the nozzle outlet are poor, and the air and powder flow angle cannot be adjusted according to the Spot Size adjusts the size of powder spots. The patent of American General Company (US7358457) adopts multi-channel coaxial powder feeding nozzle, and its shielding gas structure is ingeniously designed, but the small gradient holes in the powder tube of this design are difficult to process, and the incident angle of the powder tube cannot be adjusted, so the applicability is limited. The angle-adjustable four-tube coaxial powder feeding nozzle (CN1025540371A) used by Xi'an Jiaotong University for laser direct forming solves the problem that the angle of the powder tube cannot be adjusted. The size of the powder spots can be adjusted by adjusting the defocus of the powder, but it cannot The size of the light spot is adjusted by the size, the structure is complex, and the angles of the four powder tubes cannot be adjusted simultaneously. To sum up, the existing coaxial powder feeding nozzles cannot realize the active adjustment of the powder defocus amount and the laser defocus amount at the same time, and cannot adapt to the requirements of the manufacturing characteristics of the parts, resulting in a mismatch between the spot size and the powder spot size, resulting in powder material Waste, affecting the quality of additively manufactured parts and reducing processing efficiency. Therefore, how to actively adjust the powder defocusing amount of the coaxial powder feeding nozzle and the laser defocusing amount is an urgent problem to be solved in the development of coaxial powder feeding additive manufacturing technology.

In view of the problems existing in the above-mentioned prior art, it is very necessary to study and design a new type of laser direct structuring optical powder active adjustment coaxial powder feeding nozzle, so as to overcome the existing problems in the prior art.

Contents of the invention

In view of the problems existing in the above-mentioned prior art, the object of the present invention is to study and design a new type of laser direct forming optical powder active adjustment coaxial powder feeding nozzle. It is used to realize the active adjustment of powder defocus and laser defocus at the same time to meet the requirements of parts manufacturing characteristics, realize the matching of spot size and powder spot size, save powder materials, improve the quality of additively manufactured parts, and improve processing efficiency.

Technical solution of the present invention is realized like this:

The optical powder active adjustment coaxial powder feeding nozzle for laser direct forming according to the present invention is characterized in that the optical powder active adjustment coaxial powder feeding nozzle for laser direct forming includes: a laser defocus adjustment mechanism, a connecting sleeve and the powder defocus adjustment mechanism; the laser defocus adjustment mechanism is installed on the inner upper part of the connecting sleeve; the powder defocus adjustment mechanism is installed on the outer middle and lower part of the connecting sleeve;

The inner middle part of the connection sleeve of the present invention is processed with a mounting platform, and the outer middle part is processed with an upper ring platform and a lower ring platform; a through hole is processed on the upper ring platform, and a mounting hole is processed on the lower ring platform, and the through hole and the mounting hole Coaxial processing;

The laser defocus adjustment mechanism described in the present invention includes: a lens, a mirror base, an adjustment screw sleeve and a protective mirror; the adjustment screw sleeve is threadedly connected to the top of the connecting sleeve and can rotate freely; the lens is installed on the inner ring on the upper part of the mirror base On the stage, the mirror base and the adjusting screw sleeve are connected through threads, and the rotation of the adjusting screw sleeve drives the mirror base and the lens to move vertically up and down, adjusting the defocus of the laser to adjust the size of the spot; the protective mirror is installed on the mounting table inside the connecting sleeve ;

The powder defocus adjustment mechanism of the present invention includes: a planetary gear set, a cam linkage mechanism, a transmission shaft, a powder pipe, and a nozzle water cooling jacket; the planetary gear is assembled on the outer wall of the connecting sleeve and the upper ring platform; On the lower ring platform, the transmission shaft passes through the through hole on the upper ring platform to connect the planetary gear set and the cam linkage mechanism, and the bottom of the transmission shaft is installed in the installation hole of the lower ring platform; the planetary gear set includes: outer gear sleeve and the gear set; the outer gear sleeve is set on the connecting sleeve and placed on the upper ring platform; the gear set is composed of two gears, the gears are assembled on the transmission shaft, placed on the upper ring platform, and meshed with the outer gear sleeve; The cam link mechanism includes: a cam, a cam link and a slide block; the cam is mounted on the transmission shaft and placed on the lower ring platform, and one end of the cam link is connected with the cam; the slide block is mounted on the cam link. The gear set is driven to rotate by rotating the outer gear sleeve, and the cam is rotated synchronously through the transmission shaft. The cam connecting rod follows the rotation of the cam, driving the powder tube to rotate around the hinge, and adjusting the defocusing amount of the powder to adjust the size of the powder spot; the angle of the powder tube and the mirror seat The height can be adjusted independently, so as to realize the active adjustment of the laser defocus amount and the powder defocus amount, and realize the matching of the spot size and the powder spot size; the nozzle water cooling sleeve is installed at the bottom of the connecting sleeve; the bottom of the powder tube is hinged with the powder tube through a hinge, The upper part is connected with the cam linkage.

There are four powder pipes and cams in the present invention, which are evenly distributed around the connecting sleeve 4, the rotation angle of the cam is 360°, and the angle between the powder pipe and the vertical direction changes with the rotation of the cam.

The powder tube of the present invention is provided with an outer protection gas channel and a gas powder flow channel, both of which are parallel to the axis of the powder tube. The bottom of the powder pipe is hinged with the nozzle water cooling jacket, and the top is connected with the slider.

The nozzle water cooling jacket of the present invention is provided with a cooling flow channel inside; the lower part has the cooling flow channel inlet, and the upper part has the cooling flow channel outlet.

The material of the nozzle water-cooling jacket of the present invention is copper, the material of the connecting sleeve is stainless steel, and the nozzle water-cooling jacket and the connecting sleeve are manufactured by multi-material additive manufacturing or welding to ensure sealing and cooling effects.

The connecting sleeve of the present invention is provided with a protective gas inlet, through which the protective gas is passed through to prevent dust from affecting the optical path.

Scales are provided on the outside of the cam connecting rod and the mirror base in the present invention to precisely adjust the angle of the powder pipe and the height of the mirror base.

The present invention tests the relationship between the size of the powder spot and the angle of the powder tube, the relationship between the size of the light spot and the height of the lens holder before installing the nozzle, and adjusts the defocusing amount of the laser and the defocusing amount of the powder according to the actual situation, so as to realize the matching of the size of the powder spot and the light spot size.

The use process of the present invention is simple and easy:

By adjusting the rotation of the screw sleeve, the lens on the mirror base moves vertically, and the laser defocus is adjusted to adjust the spot size; by rotating the outer gear sleeve, the gear set is driven to rotate, and the cam is rotated synchronously through the transmission shaft, and the cam connecting rod follows the cam movement. Drive the powder tube to rotate around the hinge, adjust the powder defocusing amount to adjust the powder spot size; the powder tube angle and the height of the lens holder can be adjusted independently, so as to realize the active adjustment of the laser defocusing amount and powder defocusing amount, and realize the spot size and powder Spot size matching.

Cooling water enters from the cooling water inlet, passes through the cooling flow channel, and flows out from the cooling water outlet to cool the nozzle water cooling jacket to ensure long-term operation of the nozzle.

The shielding gas enters from the shielding gas inlet to prevent the influence of dust on the optical path; at the same time, the shielding gas enters from the outer shielding gas channel, which can not only improve the convergence of the gas powder flow but also prevent the oxidation of the molded parts.

Advantage of the present invention is obvious, mainly shows in:

1. Because the powder material and particle size affect the gas-powder flow convergence, the nozzle of the present invention can adjust different incident angles for different powders, and has strong applicability. The adjustment of the powder pipe angle can provide a reasonable solution for the selection of subsequent process parameters. Through the connecting rod The upper scale can accurately adjust the angle of the powder pipe.

2. The synchronous rotation of the four powder pipes can be realized only by rotating the outer gear sleeve, which is convenient and fast. The fastening screws on the outer gear sleeve can be used to fix the whole mechanism, which can make the position of the whole mechanism stable and reliable.

3. Rotate the adjusting screw sleeve to make the lens rise or fall with the lens holder through threaded connection, and control the height of the rise and fall through the scale on the lens holder. This method is fast and stable, and the laser defocus amount can be adjusted at any time.

4. After adjusting the height of the mirror base, the defocusing amount of the laser will change in the vertical direction, and the defocusing amount of the powder will be adjusted at the same time, so that the two can be actively adjusted, which is more conducive to adjusting the manufacturing process parameters of the parts, improving efficiency and reducing costs.

5. The powder pipe of this design is not easy to block powder, has a long service life, and the powder pipe is easy to replace, without having to replace the entire nozzle, reducing the replacement cost.

6. The design of the powder pipe is composed of a gas-powder flow channel and an outer protective gas channel. The role of the gas-powder flow channel is to transport the powder to the molten pool. The function of the protective gas channel is to improve the convergence of the gas-powder flow and prevent the oxidation of the formed parts, improving the forming process. piece quality.

7. The material of the nozzle water cooling sleeve is copper, and the material of the connecting sleeve is stainless steel. The heat source of the nozzle mainly comes from the thermal radiation of the metal powder molten pool, and the radiation absorption rate of copper is small. Using copper as the material of the nozzle water cooling jacket can minimize the influence of thermal radiation on the nozzle. The thermal conductivity of stainless steel is small, and the cooling water channel is insulated in the middle, thus greatly reducing the influence of heat sources on the lens and laser.

8. Using a variety of material additive manufacturing methods, the additive manufacturing of copper water cooling sleeves and stainless steel connecting sleeves can not only improve the sealing performance of the nozzle, but also reduce the design and use of threads and sealing rings.

9. The design of protective mirror and protective gas is adopted. The protective gas prevents the influence of dust on the optical path. The protective mirror can block dust, thereby protecting the lens from being damaged and increasing the service life.

10. The invention can be used in metal and non-metal laser cladding, surface alloying, repair of damaged parts, laser metal direct forming and other fields.

The invention has the advantages of novel structure, simple processing, convenient use, independent adjustment of light spots and powder spots, and matching of light spots and powder spots, etc., and its large-scale market will definitely produce positive social benefits and significant economic benefits.

Description of drawings

The present invention has 3 accompanying drawings, wherein:

Accompanying drawing 1 is the schematic diagram of the coaxial powder feeding nozzle of the present invention that actively adjusts the light powder.

Accompanying drawing 2 is a three-dimensional schematic diagram of the coaxial powder feeding nozzle for actively adjusting the optical powder of the present invention.

Accompanying drawing 3 is the schematic diagram of active adjustment of laser defocus amount (spot) and powder defocus amount (powder spot).

In the figure: 1, lens 2, mirror base 201, inner ring platform 3, adjusting screw sleeve 4, connecting sleeve 401, installation platform 402, upper ring platform 403, lower ring platform 5, outer gear sleeve 6, fastening screw 7 , protective mirror 8, gear set 9, transmission shaft 10, cam 11, cam connecting rod 12, slider 13, protective gas inlet 14, powder pipe 15, outer protective gas channel 16, cooling flow channel 17, gas powder flow channel 18. Nozzle water cooling jacket 19, hinge 20, laser 21, gas powder flow 22, substrate.

detailed description

The specific embodiment of the present invention is shown in accompanying drawings 1 and 2. The optical powder active adjustment coaxial powder feeding nozzle for laser direct forming includes: a laser defocus adjustment mechanism, a connecting sleeve 4 and a powder defocus adjustment mechanism; The defocus adjustment mechanism is installed on the inner upper part of the connection sleeve 4; the powder defocus adjustment mechanism is installed on the outer middle and lower part of the connection sleeve 4;

The inner middle part of the connection sleeve 4 is processed with a mounting platform 401, and the outer central part is processed with an upper ring platform 402 and a lower ring platform 403; the upper ring platform 402 is processed with a through hole, and the lower ring platform 403 is processed with a mounting hole. Hole coaxial machining;

The laser defocus adjustment mechanism includes: lens 1, mirror base 2, adjusting screw sleeve 3 and protective mirror 7; the adjusting screw sleeve 3 is screwed to the top of the connecting sleeve 4 and can rotate freely; the lens 1 is mounted on the upper part of the mirror base 2 On the inner ring platform 201, the mirror base 2 and the adjusting screw sleeve 3 are threadedly connected, and the rotation of the adjusting screw sleeve 3 drives the mirror base 2 and the lens 1 to move vertically up and down to adjust the defocusing amount of the laser to adjust the spot size; the protective mirror 7 is mounted on the installation platform 401 inside the connection sleeve 4;

The powder defocus adjustment mechanism includes: planetary gear set, cam linkage mechanism, transmission shaft 9, powder pipe 14, nozzle water cooling sleeve 18; planetary gears are assembled on the outer wall of connecting sleeve 4 and upper ring platform 402; On the lower ring platform 403, the transmission shaft 9 passes through the through hole on the upper ring platform 402 to connect the planetary gear set and the cam linkage mechanism. The gear sleeve drives the gear set to rotate, and the cam rotates synchronously through the transmission shaft, and the cam connecting rod follows the cam rotation, driving the powder tube 14 to rotate around the hinge, adjusting the defocusing amount of the powder to adjust the size of the powder spot, the angle of the powder tube and the height of the mirror seat. Separate adjustment, so as to realize the active adjustment of the laser defocus amount and powder defocus amount, and realize the matching of the spot size and the powder spot size; the nozzle water cooling sleeve 18 is installed at the bottom of the connecting sleeve 4; the bottom of the powder tube 14 is connected to the powder tube through the hinge 19 14 are hinged, and the upper part is connected with the cam linkage.

The planetary gear set includes: an external gear sleeve 5 and a gear set 8; the external gear sleeve 5 is set on the connecting sleeve 4 and placed on the upper ring platform 402; the gear set 8 is composed of two gears, and the gear set 8 is installed on the transmission shaft 9, placed on the upper ring platform 402, and meshed with the outer gear sleeve 5.

The cam link mechanism includes: a cam 10, a cam link 11 and a slider 12; the cam 10 is installed on the transmission shaft 9 and placed on the lower ring platform 403, and one end of the cam link 11 is connected with the cam 10; the slider 12 is installed on the cam link 11.

The bottom of powder pipe 14 is hinged with nozzle water cooling jacket 18 through hinge 19, and the top is connected with slide block 12.

The powder pipe 14 is provided with an outer protective gas channel 15 and a gas powder flow channel 17; the protective gas enters from the outer protective gas channel 15, which can not only improve the convergence of the gas powder flow but also prevent the oxidation of the molded part. .

The inside of the nozzle water cooling jacket 18 is provided with a cooling flow channel 16; the lower part has a cooling flow channel inlet, and the upper part has a cooling flow channel outlet; the cooling water enters from the cooling water inlet, passes through the cooling flow channel 16, and flows out from the cooling water outlet. 18 for cooling to ensure long-term work of the nozzle.

The nozzle water cooling jacket 18 is made of copper, the connecting sleeve 4 is made of stainless steel, and the nozzle water cooling jacket 18 and the connecting sleeve 4 are manufactured by multi-material additive manufacturing or welding to ensure sealing and cooling effects.

There are four powder pipes 14 and cams 10, which are evenly distributed around the connecting sleeve 4. The rotation angle of the cam 10 is 360°, and the angle between the powder pipe 14 and the vertical direction changes with the rotation of the cam.

A shielding gas inlet 13 is provided on the connection sleeve 4, and the shielding gas is passed through the shielding gas inlet 13 to prevent dust from affecting the optical path.

Scales are provided on the outside of the cam connecting rod 11 and the outside of the mirror holder 2 to precisely adjust the angle of the powder pipe and the height of the mirror holder.

Before installing the nozzle, test the relationship between the size of the powder spot and the angle of the powder tube 14, the relationship between the size of the light spot and the height of the mirror holder 2, and adjust the defocusing amount of the laser and the defocusing amount of the powder according to the actual situation, so as to achieve the matching of the size of the powder spot and the light spot size.

As shown in Figure 3a, the distance between the outlet of the powder pipe 14 and the centerline of the nozzle is d, and the angle between the outlet of the powder pipe 14 and the centerline of the nozzle is _θ1 . θ ₁ and the distance d between the outlet of the powder tube 14 and the centerline of the nozzle remain unchanged, the laser defocus becomes smaller, and the spot size of the laser 20 reaching the substrate 22 is smaller than the powder spot size of the gas-powder flow 21 reaching the substrate 22. It is necessary to connect the powder tube 14 and the nozzle Change the included angle of the center line to θ ₂ to adjust the defocusing amount of the powder, and at the same time adjust the substrate 22 upwards by △h, as shown in part c of Figure 3, actively adjust the defocusing amount of the laser and the defocusing amount of the powder, so as to achieve the spot size and powder spot Size matching.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, all those skilled in the art are within the technical scope disclosed in the present invention, according to the technology of the present invention Any equivalent replacement or change of the scheme and the concept of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A light powder active adjustment coaxial powder feeding nozzle for laser direct forming, characterized in that the light powder active adjustment coaxial powder feeding nozzle for laser direct forming comprises: a laser defocus adjustment mechanism, a connecting sleeve ( 4) and the powder defocus adjustment mechanism; the laser defocus adjustment mechanism is installed on the inner upper part of the connecting sleeve (4); the powder defocus adjustment mechanism is installed on the outer middle and lower part of the connecting sleeve (4); The inner middle part of the connecting sleeve (4) is processed with a mounting platform (401), and the outer middle part is processed with an upper ring platform (402) and a lower ring platform (403); the upper ring platform (402) is processed with a through hole, and the lower A mounting hole is processed on the ring platform (403), and the through hole is coaxially processed with the mounting hole; The laser defocus adjustment mechanism includes: a lens (1), a mirror holder (2), an adjustment screw sleeve (3) and a protective mirror (7); the top thread of the adjustment screw sleeve (3) and the connecting sleeve (4) connected, and can rotate freely; the lens (1) is installed on the inner ring platform (201) on the top of the mirror base (2), the mirror base (2) and the adjusting screw sleeve (3) are connected by threads, and the adjusting screw sleeve (3) ) rotation drives the mirror base (2) and the lens (1) to move vertically up and down; the protective mirror (7) is installed on the mounting table (401) inside the connecting sleeve (4); The powder defocus adjustment mechanism includes: a planetary gear set, a cam linkage, a transmission shaft (9), a powder pipe (14), and a nozzle water cooling sleeve (18); the planetary gear is assembled on the outer wall of the connecting sleeve (4) and On the upper ring platform (402); the cam link mechanism is installed on the lower ring platform (403), and the transmission shaft (9) passes through the through hole on the upper ring platform (402) to connect the planetary gear set and the cam link mechanism , the bottom of the transmission shaft (9) is installed in the mounting hole of the lower ring platform (403); the nozzle water cooling sleeve (18) is installed at the bottom of the connecting sleeve (4); the bottom of the powder pipe (14) is connected to the powder by the hinge (19) Pipe (14) is hinged, and the upper part is connected with cam linkage. 2. The optical powder active adjustment coaxial powder feeding nozzle for laser direct structuring according to claim 1, characterized in that the planetary gear set includes: an outer gear sleeve (5) and a gear set (8); The gear sleeve (5) is sleeved on the connecting sleeve (4) and placed on the upper ring platform (402); the gear set (8) is composed of two gears, and the gear set (8) is installed on the transmission shaft (9). Place it on the upper ring platform (402), and mesh with the outer gear sleeve (5). 3. The optical powder active adjustment coaxial powder feeding nozzle for laser direct structuring according to claim 1, characterized in that the cam linkage mechanism includes: a cam (10), a cam linkage (11) and a slide block (12); the cam (10) is installed on the transmission shaft (9) and placed on the lower ring platform (403), and one end of the cam connecting rod (11) is connected with the cam (10); the slide block (12) is installed on on the cam link(11). 4. The optical powder active adjustment coaxial powder feeding nozzle for laser direct structuring according to claim 1, characterized in that the bottom of the powder pipe (14) is connected with the nozzle water cooling jacket (18) through the hinge (19) Hinged, the top is connected with slide block (12). 5. The optical powder active adjustment coaxial powder feeding nozzle for laser direct structuring according to claim 4, characterized in that the powder pipe (14) is provided with an outer protective gas channel (15) and a gas powder circulation Road (17) is all parallel to the powder pipe (14) axis. 6. The optical powder active adjustment coaxial powder feeding nozzle for laser direct structuring according to claim 1, characterized in that the nozzle water cooling jacket (18) is provided with a cooling channel (16) inside; the lower part has a cooling channel (16). The inlet of the runner, and the outlet of the cooling runner on the upper part. 7. The optical powder active adjustment coaxial powder feeding nozzle for laser direct forming according to claim 1, characterized in that the material of the nozzle water cooling jacket (18) is copper, and the material of the connecting sleeve (4) is Stainless steel, nozzle water cooling sleeve (18) and connection sleeve (4) adopt multi-material additive manufacturing or welding to ensure sealing and cooling effect. 8. The optical powder active adjustment coaxial powder feeding nozzle for laser direct structuring according to claim 5, characterized in that the powder pipes (14) and the cams (10) are 4, evenly distributed in the connecting Around cover (4), cam (10) rotation angle is 360 °, and the angle of powder pipe (14) and vertical direction changes with cam rotation. 9. The optical powder active adjustment coaxial powder feeding nozzle for laser direct structuring according to claim 7, characterized in that the connecting sleeve (4) is provided with a protective gas inlet (13), and the protective gas inlet (13) Pass the protective gas to prevent dust from affecting the optical path. 10. The optical powder active adjustment coaxial powder feeding nozzle for laser direct forming according to claim 3, characterized in that the outside of the cam connecting rod (11) and the outside of the mirror holder (2) are provided with scales, with To precisely adjust the angle of the powder pipe and the height of the mirror holder.