Metal powder delivery tube for powder feeding laser coaxial and lateral processing heads

Abstract

The present invention relates to the field of laser additive manufacturing and remanufacturing technology, and more specifically to a metal powder delivery tube for a powder-feeding laser coaxial and lateral processing head, comprising: a glass inner tube; a metal tube shell, arranged on the outside of the glass inner tube; and a dielectric layer, arranged between the glass inner tube and the metal tube shell; wherein the axis of the glass inner tube coincides with the axis of the metal tube shell, and the inner wall of the glass inner tube is smooth, forming a powder delivery channel for conveying metal powder. The powder delivery tube structure shown in the present invention adopts a copper tube as a tube body and a glass tube as an inner liner in a composite manner. The copper tube can protect the glass tube, and at the same time, the copper tube can absorb heat and conduct the heat through the water cooling system of the processing head; in addition, the smooth and wear-resistant characteristics of the glass surface are fully utilized, so that the metal powder beam ejected from the powder tube can remain in a straight line over a long distance and almost does not disperse, and can accurately coincide with the laser spot.

Description

Technical Field

[0001] The present invention relates to the technical field of laser additive manufacturing and remanufacturing, and in particular to a metal powder conveying tube for a powder-feeding laser coaxial and lateral processing head. Background Art

[0002] In additive manufacturing or laser cladding, the laser emitted by a coaxial optical in-feed or side-axis delivery processing head interacts with the substrate to form a molten pool. At the same time, metal powder is transported to the front end of the laser processing head through a plastic or polymer pipeline using an inert gas such as argon or nitrogen as a carrier, and is ejected into the molten pool by a metal powder delivery pipe.

[0003] Currently, copper or brass tubes are commonly used to manufacture metal powder delivery tubes. However, due to their rough inner walls, the sprayed powder has poor convergence, affecting printing accuracy and significantly wasting powder. Even after polishing, the soft copper material quickly wears away under the flow of metal or alloy powder particles. Coating the inner wall is expensive and difficult to manufacture, making it impractical. To reduce costs, improvements to delivery tubes are crucial. Summary of the Invention

[0004] The present invention provides a metal powder delivery tube for a powder-feeding laser coaxial and lateral processing head, comprising:

[0005] Glass inner tube;

[0006] A metal tube shell is arranged on the outside of the glass inner tube;

[0007] a dielectric layer, disposed between the glass inner tube and the metal shell;

[0008] The axis of the glass inner tube coincides with the axis of the metal tube shell, and the inner wall of the glass inner tube is smooth, forming a powder feeding channel for conveying metal powder;

[0009] The end where the metal powder is fed out of the glass inner tube is defined as the powder outlet end, and the end where the metal powder is fed into the glass inner tube is defined as the powder delivery end. The end plane of the powder outlet end of the glass inner tube is located on the side of the end plane of the powder outlet end of the metal tube shell close to the powder delivery end.

[0010] The dielectric layer includes a heat-insulating medium section and a heat-conducting medium section, wherein the heat-insulating medium section is arranged on the outer wall of the glass inner tube and is located between the glass inner tube and the metal tube shell, so that an annular gap is formed between the glass inner tube and the metal tube shell, and the two are separated from each other;

[0011] The heat-conducting medium section is arranged in the annular gap and extends from the powder outlet end of the glass inner tube toward the powder feeding end of the glass inner tube, so that within the range between any two heat-insulating medium sections, heat is conducted from the glass inner tube to the metal tube shell via the heat-conducting medium section.

[0012] As an optional implementation, the thermal conductivity of the heat-insulating medium section is 0.1-0.4 W / mK, and the thermal conductivity of the heat-conducting medium section is 0.8-5 W / mK.

[0013] As an optional embodiment, the heat-insulating medium section is constructed as an annular heat-insulating sleeve, which is sleeved on the outer wall surface of the glass inner tube. The lower end surface of the annular heat-insulating sleeve at the powder outlet end of the glass inner tube is aligned with the end surface of the powder outlet end of the glass inner tube.

[0014] As an optional embodiment, the thermal insulation medium section includes at least a first annular thermal insulation sleeve located at the powder outlet end of the glass inner tube and a second annular thermal insulation sleeve located at the powder delivery end of the glass inner tube, both of which adopt the same structure and size design.

[0015] As an optional embodiment, the annular thermal insulation sleeve comprises a heat-resistant polymer material, for example, the first annular thermal insulation sleeve and the second annular thermal insulation sleeve are both made of a heat-resistant polymer material. The annular thermal insulation sleeve is bonded to the glass inner tube and the metal tube shell by a thermosetting material.

[0016] As an optional embodiment, the heat-conducting medium segment includes a heat-conducting silicone layer, and the heat-conducting silicone layer is filled between the outer wall of the glass inner tube and the inner wall of the metal tube shell.

[0017] As an optional embodiment, the distance between the end plane of the powder outlet end of the glass inner tube and the end plane of the powder outlet end of the metal shell is 1-2 mm.

[0018] As an optional embodiment, the glass inner tube includes a silicate glass tube or a quartz glass tube, and the metal tube shell includes a copper tube or a brass tube.

[0019] As an optional embodiment, the inner diameter of the glass inner tube is 1 mm±0.1 mm, 1.5 mm±0.1 mm, 1.7 mm±0.1 mm or 2 mm±0.1 mm.

[0020] As an optional embodiment, the inner hole at the powder outlet end of the metal shell is provided with a bell-shaped rounded corner.

[0021] Compared with the prior art, the metal powder delivery tube for the powder feeding type laser coaxial and lateral processing head of the present invention has the following advantages:

[0022] 1. The powder feed tube structure of the present invention utilizes a copper tube as the tube body and a glass tube as the inner liner. The copper tube protects the relatively fragile glass tube and absorbs a large amount of heat, which is then transferred through the processing head's water cooling system. This prevents the glass tube from cracking due to uneven heating in a short period of time or softening due to heat accumulation over long periods of time. Furthermore, the smooth and wear-resistant surface of the glass is fully utilized to ensure that the metal powder beam ejected from the powder tube remains straight over a long distance with minimal dispersion, allowing it to precisely overlap with the laser spot.

[0023] 2. Heat insulation layer and heat conduction layer are set between the glass tube and the copper tube according to different areas, which can reduce the overall temperature of the powder feeding tube while keeping the temperature of the powder feeding tube balanced and not easy to break;

[0024] 3. Since the reduction of surface powder adhesion and nodules will reduce the probability of secondary remelting defects, thereby improving the quality of the overall printed part or cladding layer, the metal powder delivery tube design of the present invention avoids the phenomenon of powder adhesion on the cladding layer surface through precise control of the powder convergence point and the laser spot, reducing the formation of nodules and facilitating the overall workpiece forming control;

[0025] 4. Due to the improvement of powder convergence, the utilization rate of powder and printing efficiency can be improved, and the cost of additive manufacturing can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For the sake of clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example and with reference to the accompanying drawings, in which:

[0027] Figure 1 It is a schematic structural diagram of a metal powder delivery tube for a powder-feeding laser coaxial and lateral processing head shown in the present invention;

[0028] Figure 2 This is a half-section structural diagram of the powder inlet end of the conveying pipe shown in the present invention;

[0029] Figure 3 This is a half-section structural diagram of the powder outlet end of the conveying pipe shown in the present invention;

[0030] Figure 4 Schematic diagram of the distribution of the heat insulating medium segment and the heat conducting medium segment on the outer wall of the glass tube shown in the present invention;

[0031] Figure 5a It is a schematic diagram of metal tube powder feeding in the prior art;

[0032] Figure 5b This is a schematic diagram of the glass inner tube powder feeding method shown in the present invention.

[0033] Figure 6 Schematic diagram of heat conduction at the powder outlet end of the conveying pipe shown in the present invention;

[0034] Figure 7a This is a schematic diagram of powder spraying before the metal powder delivery pipe is improved;

[0035] Figure 7b Schematic diagram of powder spraying of the delivery pipe shown in the present invention. DETAILED DESCRIPTION

[0036] In order to better understand the technical content of the present invention, specific embodiments are given and described below with reference to the accompanying drawings.

[0037] The present invention proposes a metal powder delivery tube for a powder-feeding laser coaxial and lateral processing head, which is used for powder feeding processing of metal additive manufacturing printing equipment, and is particularly suitable for laser additive and remanufacturing powder feeding of coaxial optical powder feeding processing heads and lateral powder feeding processing heads. Since the powder feeding tubes in the prior art usually adopt copper tubes, the inner wall of the metal pipe is easily worn by metal powder, resulting in an uneven surface of the inner wall of the powder feeding tube, resulting in the powder aggregation degree of the powder feeding not reaching the ideal state.

[0038] The present invention aims to propose a powder feeding tube for a coaxial optical internal powder feeding processing head and a lateral powder feeding processing head, which increases the convergence of metal powder sprayed from the powder feeding tube, can feed most of the powder into the molten pool, effectively improves the utilization rate of the powder, and saves production costs. At the same time, the efficient utilization of powder also avoids the phenomenon of powder sticking to the surface of the cladding layer, reduces the generation of nodules, and is beneficial to the overall forming control of the workpiece. Due to the reduction of surface powder sticking and nodules, the probability of defects caused by secondary remelting is reduced, thereby improving the quality of the overall cladding layer.

[0039] The metal powder delivery tube for the powder-feeding laser coaxial and lateral processing head proposed in an exemplary embodiment of the present invention adopts a double-layer design with inner and outer separations. The inner tube is a glass tube, and the outer tube is designed with a metal tube such as a copper tube. The inner wall of the inner glass tube is smooth, and the outlet end has an end face perpendicular to the inner wall. The axis of the glass inner tube coincides with the axis of the metal outer tube. The inner wall of the glass inner tube is smooth, forming a powder delivery channel for conveying metal powder, which can make the effective convergence length of the powder reach 25 to 35 mm. For the coaxial light powder feeding processing head, it can ensure that the convergence point of the metal powder ejected from each tube is on the same axis as the laser spot; for the lateral powder feeding processing head, it can ensure that the end of the metal powder beam accurately coincides with the laser spot.

[0040] Combine Figure 1-3 The metal powder delivery tube for the powder feeding type laser coaxial and lateral processing head of the embodiment shown comprises a glass inner tube 5, a metal tube shell 1 and a dielectric layer. The metal tube shell 1 is arranged outside the glass inner tube 5 for heat shielding and increasing the strength of the powder delivery tube.

[0041] The metal tube shell 1 is configured to use a metal round tube with good thermal conductivity, such as copper or stainless steel. The copper tube is taken as an example below. As an optional embodiment, the metal tube shell 1 may use a red copper tube or a brass tube.

[0042] In a specific embodiment, the copper tube has a length of 80 to 120 mm, an outer diameter of 5 mm, and an inner diameter of 2 to 3 mm. An external thread is provided at the powder inlet 4 of the shell to cooperate with a fastening nut 2 to fix the metal powder delivery tube.

[0043] The copper tube is installed on the processing head and connected to the water cooling system of the processing head to absorb the heat of the copper tube and cool it down.

[0044] The end where the metal powder is discharged from the glass inner tube 5 is defined as the powder discharge end 4, and the end where the metal powder is fed into the glass inner tube 5 is defined as the powder feeding end 3. The end plane of the powder discharge end of the glass inner tube 5 is indented inside the end plane of the powder discharge end of the metal tube shell.

[0045] As an optional embodiment, the inner hole of the powder outlet end 4 of the metal tube shell 1 is provided with a bell-shaped rounded corner, and the outer wall is also provided with a rounded corner. In this way, the laser beam reflected on the end face of the copper tube can be dispersed and the radiation heat of the reflected laser can be reduced.

[0046] Furthermore, in order to ensure that the powder feeding tube can be installed in the correct position, the axis of the glass inner tube 5 coincides with the axis of the metal tube shell 1. In this way, the axis position of the glass inner tube 5 can be controlled by controlling the axis position of the metal tube shell 1, so that the powder feeding direction can be precisely controlled.

[0047] The inner wall of the glass inner tube 5 is smooth, forming a powder feeding channel for conveying metal powder. According to the specifications of the glass inner tube 5, the effective powder gathering length can reach 25 to 35 mm.

[0048] Combine Figure 2 As shown, the end plane of the powder outlet end 4 of the glass inner tube 5 is located on the side of the end plane of the powder outlet end 4 of the metal tube shell 1 close to the powder feeding end 3.

[0049] In this way, the end of the glass inner tube 5 is retracted inside the metal tube shell 1 and is not easily impacted by the outside. At the same time, the heat radiation energy of the molten pool to the end of the glass inner tube 5 is reduced.

[0050] As an optional embodiment, the angle between the end plane of the powder outlet end 4 of the glass inner tube 5 and the inner wall surface of the glass inner tube 5 is a right angle.

[0051] Combine Figure 5a As shown, the powder outlet port 12 of the metal tube 10 in the prior art is generally rounded. Especially after the powder enters from the powder inlet port 11, the powder outlet port 12 is worn by the metal powder for a long time, and the rounded corners will increase, and the restraint on the discharged powder will decrease, and the discharged powder will form a diffused powder feeding range 101. Figure 5b As shown, the angle between the end plane of the glass inner tube 5 and the inner wall of the tube is a right angle, which has a strong constraint on the powder. After the powder enters the glass tube from the powder inlet 51, it is ejected from the glass tube powder outlet 52, forming a constrained powder feeding range 101, which can increase the effective convergence length, so that the metal powder beam ejected from the powder tube can remain in a straight line over a long distance with almost no dispersion, and can accurately overlap with the laser spot.

[0052] Combine Figure 7a As shown, the powder spraying in the prior art has high dispersion and weak convergence. Figure 7b The metal powder feeding tube of the present invention is improved so that the effective gathering length of the metal powder is increased.

[0053] In the above-mentioned embodiment, the glass inner tube 5 includes a silicate glass tube or a quartz glass tube.

[0054] Optionally, the material used for the glass inner tube 5 is selected according to the laser power. When the laser power is higher than 2500W, a silicate glass tube is used; when the laser power is lower than 2500W, a quartz glass tube with higher purity is used.

[0055] As an optional embodiment, the inner diameter of the glass inner tube is 1-2 mm.

[0056] In particular, when the particle size of the powder transported in the powder feeding channel is 45-105 μm, the inner diameter of the glass inner tube 5 is 1±0.1 mm; when the particle size of the powder transported in the powder feeding channel is 45-150 μm, the inner diameter of the glass inner tube 5 is 1.5±0.1 mm; when the particle size of the powder transported in the powder feeding channel is 45-250 μm, the inner diameter of the glass inner tube 5 is 1.7±0.1 mm; when the particle size of the powder transported in the powder feeding channel is 45-300 μm, the inner diameter of the glass inner tube 5 is 2±0.1 mm.

[0057] In a specific embodiment, a glass inner tube can be selected based on the type and particle size of the powder being conveyed. For example, the inner diameter of the glass inner tube 5 is 1.0 to 2.0 mm (±0.1 mm), the wall thickness is 0.1 mm to 1 mm, and the length is not less than 30 mm and does not exceed the length of the metal shell 1. The powder outlet end of the glass inner tube 5 is always fixed, located 1 to 2 mm inward from the plane of the powder outlet end of the metal shell 1, while the other end is not fixed.

[0058] As an optional embodiment, the medium layer includes a heat-insulating medium segment 6 and a heat-conducting medium segment 7 .

[0059] As shown in the figure, the heat insulating medium section 6 is arranged on the outer wall of the glass inner tube 5 and located between the glass inner tube 5 and the metal tube shell 1, so that an annular gap is formed between the glass inner tube and the metal tube shell, and the two are separated from each other.

[0060] The heat-conducting medium segment 7 is arranged in the aforementioned annular gap and extends from the powder outlet end of the glass inner tube 5 toward the powder feeding end of the glass inner tube, so that within the range between any two heat-insulating medium segments 6, heat is conducted from the glass inner tube 5 to the metal tube shell 1 via the heat-conducting medium segment 7.

[0061] Optionally, the thermal conductivity of the heat-insulating medium section is 0.1-0.4 W / mK, and the thermal conductivity of the heat-conducting medium section is 0.8-5 W / mK.

[0062] Combine Figure 6 As shown, since the powder outlet end 4 of the powder feeding pipe is close to the molten pool 100 (the molten pool 100 radiates heat as a heat source), and in particular the metal tube shell 1 has strong thermal conductivity, the temperature of the end of the metal tube shell 1 close to the powder outlet end 4 is high. In order to prevent the temperature from being transferred to the glass inner tube 5, a heat insulating medium section 6 is provided between the metal tube shell 1 and the glass inner tube 5.

[0063] Optionally, the heat-insulating medium segment 6 is constructed as an annular heat-insulating sleeve, which is sleeved on the outer wall surface of the glass inner tube.

[0064] As shown in the figure, the heat-insulating medium section comprises at least a first annular heat-insulating sleeve located at the powder outlet end of the glass inner tube and a second annular heat-insulating sleeve located at the powder delivery end of the glass inner tube, both of which adopt the same structure and size design.

[0065] The length of the first annular heat-insulating sleeve and the second annular heat-insulating sleeve is 5-10 mm, and can be selected according to actual needs.

[0066] As shown in the figure, the lower end surface of the annular heat-insulating sleeve located at the powder outlet end of the glass inner tube 5 is aligned with the end surface of the powder outlet end of the glass inner tube 5 .

[0067] Optionally, the annular heat-insulating sleeve may be made of a heat-resistant material, such as a heat-resistant polymer material, such as an aromatic polymer heat-resistant polymer material.

[0068] The annular heat-insulating sleeve is bonded to the glass inner tube 5 and the metal tube shell 1 by a thermosetting material, such as a thermosetting phenolic resin. The polymer material and the thermosetting phenolic resin have good bonding ability to ensure the reliability of bonding and fixing.

[0069] As an optional embodiment, the thickness of the first annular thermal insulation sleeve and the second annular thermal insulation sleeve is slightly smaller than the gap between the glass inner tube 5 and the metal tube shell 1, so as to facilitate the coating of the thermosetting adhesive layer.

[0070] During the additive manufacturing printing process, the laser beam reflected in the glass inner tube 5 causes the temperature of the glass inner tube 5 to rise. In the embodiment of the present invention, a heat conducting medium segment 7 is provided to transfer heat to the metal tube shell 1 through the heat conducting medium segment 7.

[0071] Optionally, the heat-conducting medium segment 7 includes a heat-conducting silicone layer, which is filled between the outer wall of the glass inner tube 5 and the inner wall of the metal tube shell 1 .

[0072] It should be understood that in the embodiments of the present invention, Figure 1 The metal powder delivery tube shown can be installed on a laser cladding processing head. The metal tube shell 1 is connected to the cooling system of the processing head. A first heat conduction zone 101 is formed at the end of the metal tube shell 1. A heat insulation zone 102 is formed between the metal tube shell 1 and the glass inner tube 5 near the powder outlet end 4. Further back, a second heat conduction zone 103 is formed between the metal tube shell 1 and the glass inner tube 5. The first heat conduction zone 101 and the second heat conduction zone 103 both conduct heat to the cooling system to maintain a low temperature of the powder delivery tube and ensure uniform heating of the glass inner tube 5.

[0073] In an optional embodiment, thermosetting phenolic resin is applied to the surfaces of the first annular thermal insulation sleeve and the second annular thermal insulation sleeve, and are respectively sleeved on both ends of the glass inner tube 5, and then placed in the metal tube shell 1. After the position is fixed, they are placed in an oven and baked at 200°C for 5 to 10 minutes. After the thermosetting phenolic resin is completely cured, the metal powder conveying pipe is completed.

[0074] Optionally, when the glass inner tube 5 is larger than 60 mm, at least one third annular thermal insulation sleeve may be added at at least one position in the middle of the length direction of the glass inner tube 5 , and the same structural design as other thermal insulation sleeves may be adopted.

[0075] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A metal powder delivery tube for a powder feeding laser coaxial and lateral processing head, characterized in that: include: Glass inner tube; A metal tube shell is arranged on the outside of the glass inner tube; a dielectric layer, disposed between the glass inner tube and the metal shell; The axis of the glass inner tube coincides with the axis of the metal tube shell, and the inner wall of the glass inner tube is smooth, forming a powder feeding channel for conveying metal powder; The end where the metal powder is discharged from the glass inner tube is defined as the powder discharge end, and the end where the metal powder is fed into the glass inner tube is defined as the powder delivery end. The end plane of the powder discharge end of the glass inner tube is indented inside the end plane of the powder discharge end of the metal tube shell. The dielectric layer includes a heat-insulating medium section and a heat-conducting medium section, wherein the heat-insulating medium section is arranged on the outer wall of the glass inner tube and is located between the glass inner tube and the metal tube shell, so that an annular gap is formed between the glass inner tube and the metal tube shell, and the two are separated from each other; The heat-conducting medium section is arranged in the annular gap and extends from the powder outlet end of the glass inner tube toward the powder feeding end of the glass inner tube, so that within the range between any two heat-insulating medium sections, heat is conducted from the glass inner tube to the metal tube shell via the heat-conducting medium section.

2. The metal powder delivery tube for a powder feeding type laser coaxial and lateral processing head according to claim 1, characterized in that: The thermal conductivity of the heat-insulating medium section is 0.1-0.4 W / mK, and the thermal conductivity of the heat-conducting medium section is 0.8-5 W / mK.

3. The metal powder delivery tube for a powder feeding laser coaxial and lateral processing head according to claim 1, characterized in that: The heat-insulating medium section is constructed as an annular heat-insulating sleeve, which is sleeved on the outer wall surface of the glass inner tube.

4. The metal powder delivery tube for a powder feeding laser coaxial and lateral processing head according to claim 1, characterized in that: The lower end surface of the annular heat-insulating sleeve located at the powder outlet end of the glass inner tube is aligned with the end surface of the powder outlet end of the glass inner tube.

5. The metal powder conveying tube for a powder feeding type laser coaxial and lateral processing head according to any one of claims 1 to 4, characterized in that: The heat-insulating medium section at least comprises a first annular heat-insulating sleeve located at the powder outlet end of the glass inner tube and a second annular heat-insulating sleeve located at the powder delivery end of the glass inner tube, both of which are designed with the same structure and size.

6. The metal powder delivery tube for a powder feeding type laser coaxial and lateral processing head according to claim 5, characterized in that: The first annular heat-insulating sleeve and the second annular heat-insulating sleeve are both made of heat-resistant polymer materials.

7. The metal powder delivery tube for a powder feeding type laser coaxial and lateral processing head according to claim 1, characterized in that: The heat-insulating medium segment is bonded and fixed to the glass inner tube and the metal tube shell respectively by using thermosetting materials.

8. The metal powder delivery tube for a powder feeding type laser coaxial and lateral processing head according to claim 1, characterized in that: The heat-conducting medium section includes a heat-conducting silica gel layer, and the heat-conducting silica gel layer is filled between the outer wall of the glass inner tube and the inner wall of the metal tube shell.

9. The metal powder delivery tube for a powder feeding type laser coaxial and lateral processing head according to claim 1, characterized in that: The glass inner tube is a silicate glass tube or a quartz glass tube.

10. The metal powder delivery tube for a powder feeding laser coaxial and lateral processing head according to claim 1, characterized in that: The metal tube shell includes a copper tube or a brass tube.

11. The metal powder delivery tube for a powder feeding type laser coaxial and lateral processing head according to claim 1, characterized in that: The inner hole of the end of the metal tube shell located at the powder outlet end is provided with a bell-shaped chamfered corner.

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