Double-shielding-gas additive machining method and laser head

Abstract

The invention relates to the field of laser additive machining, in particular to a double-shielding-gas additive machining method and a laser head, and the double-shielding-gas additive machining method comprises the following steps that S100, inner-layer shielding gas is opened, and the inner-layer shielding gas is output to an additive area; s200, a laser output head is started, a powder feeder is started, and powder is fed to the material adding area; s300, the additive machining head is controlled to move relative to the workpiece or the additive base according to the set path; and S400, the outer-layer protective gas is opened, the outer-layer protective gas is sprayed to the exterior of the current additive area, oxidation of materials in the additive area can be prevented, and the laser additive machining effect is improved. The double-shielding-gas additive machining laser head comprises the base, the wire feeding unit and the multiple coaxial powder feeding laser output heads, the coaxial powder feeding laser output heads are provided with the inner-layer protection gas pipes and the outer-layer protection gas channels, and the double-shielding-gas additive machining method can be achieved.

Description

Technical Field

[0001] The present application relates to the field of laser additive processing, and more particularly to a dual-shielding-gas additive processing method. In addition, the present application also relates to a dual-shielding-gas additive processing laser head. Background Art

[0002] Laser is a type of light emitted by stimulated atoms. It has the characteristics of good directionality, high brightness, good monochromaticity, and high energy density. It is currently widely used in industrial production, communications, information processing, medical treatment, military, and scientific research.

[0003] Laser processing is a processing method that utilizes the high energy contained in lasers and the photothermal effect of lasers. It mainly includes laser welding, laser cutting, surface strengthening, laser marking, laser additive manufacturing, etc. It does not require direct contact with the material, has a fast processing speed, and small surface deformation. Different laser wavelengths correspond to the processing of different materials, and it has great adaptability. When performing laser additive processing, the wire or powder of the additive material is usually transported to the additive area, and is melted and combined with the substrate in the additive area through high-energy laser irradiation. Under the irradiation of high-energy lasers, the material in the additive area is in a high-temperature molten state. Once it comes into contact with oxygen in the air, it will cause rapid oxidation of the material. Therefore, during laser additive processing, a protective gas is usually output in the additive area to isolate oxygen and protect the material in the additive area at high temperature.

[0004] When performing laser additive processing, the laser channel, wire feeding channel or powder feeding channel on the laser head is usually used to output protective gas to the laser outlet, so that the protective cover covers the additive area and protects the high-temperature material in the additive area. However, during the laser additive processing process, the additive laser head usually moves continuously along the set path on the base material. When the laser head leaves, the protective gas in the original additive area gradually dissipates, while the temperature of the area is still high, which easily leads to oxidation of the high-temperature material. Existing laser additive processing methods usually use the method of increasing the output flow rate of the protective gas to deal with it. By increasing the output flow rate of the protective gas, on the one hand, the coverage range of the protective gas can be increased, and on the other hand, the airflow of the protective gas can be used to cool the additive area, so that the additive area leaves the protective gas coverage area at a lower temperature. However, a higher protective gas flow rate is likely to affect the transportation of the additive material powder and reduce the utilization rate of the powder material. At the same time, the high flow rate of protective gas can also cool the laser irradiation area, affecting the temperature of the molten pool formed by laser irradiation and the effect of additive processing. Summary of the invention

[0005] In order to prevent oxidation of materials in the additive area and improve the effect of laser additive processing, the present application provides a dual-shielding gas additive processing method and a laser head.

[0006] The dual-shielding gas additive processing method provided in this application adopts the following technical solution: A double-shielding-gas additive processing method comprises the following steps: S100, opening an inner layer of shielding gas, and outputting the inner layer of shielding gas to an additive area; S200, opening a laser output head, and opening a powder feeder, and feeding powder to the additive area; S300, controlling the additive processing head to move along a set path relative to a workpiece or an additive base; S400, opening an outer layer of shielding gas, and spraying the outer layer of shielding gas to the outside of the current additive area.

[0007] By adopting the above technical solution and the method of outputting the inner layer of protective gas to the additive area, the inner layer of protective gas can cover the additive area while having a small impact on the additive powder conveying path, ensuring that the molten pool formed by laser irradiation is located within the coverage of the inner layer of protective gas, thereby protecting the high-temperature material in the molten pool area. By using the method of spraying the outer layer of protective gas outside the current additive area, the outer area of ​​the current additive area can be cooled without affecting the additive powder conveying path, prompting the previous additive area to cool down quickly after the laser head leaves, and using the outer layer of protective gas to form a covering protection in a larger range outside the current additive area, ensuring that the previous additive area can be effectively protected by the outer layer of protective gas before it is fully cooled down, while preventing the oxidation of the material in the additive area, reducing the temperature between the additive layers, preventing the growth of grains, and helping to improve the effect of laser additive processing.

[0008] In a specific implementation scheme, step S400 includes the following steps: S410, turning on the gas source of the outer layer shielding gas; S420, obtaining the moving direction of the additive processing head; S430, controlling the outer layer shielding gas to be sprayed from behind the moving direction of the additive processing head.

[0009] By adopting the above technical solution and utilizing the method of spraying the outer layer of protective gas behind the moving direction of the additive processing head, the outer layer of protective gas can be sprayed more onto the previously additive area on the additive processing substrate, that is, the area where the temperature has not been sufficiently reduced, thereby ensuring that the protective gas is concentrated in the high-temperature area on the substrate, thereby improving the cooling and protective effects of the outer layer of protective gas.

[0010] In a specific possible implementation, in step S420, the moving direction of the additive processing head is determined by using a temperature sensor to detect the temperature of different parts of the periphery of the current additive area.

[0011] By adopting the above technical solution and using the method of setting multiple temperature sensors in different directions around the additive laser head, it is possible to detect the temperature of the current additive area after the laser head moves, that is, the temperature of the substrate area in different directions around the laser head area. The area with higher temperature is the rear area in the moving direction of the additive processing head, and it is advisable to spray the outer layer of protective gas in this area.

[0012] In a specific possible implementation scheme, step S400 further includes the step: S440, controlling the injection flow rate of the outer layer shielding gas according to the temperature behind the moving direction of the additive processing head detected by the temperature sensor.

[0013] By adopting the above technical solution, a temperature sensor is used to monitor the temperature value behind the moving direction of the additive processing head. When the temperature value is high, the flow rate of the outer protective gas is increased to improve the cooling effect of the area behind the moving direction of the additive processing head, and the coverage of the outer protective gas is increased to form a more effective protection for the higher temperature area; when the temperature value is changed, the flow rate of the outer protective gas is reduced to reduce the unnecessary consumption of the outer protective gas, so that the cooling and protection effects of the outer protective gas can be adapted to actual needs.

[0014] In a specific possible implementation manner, in step S430, the spraying direction of the outer layer of shielding gas deviates from the direction of the current additive area.

[0015] By adopting the above technical solution, by spraying the outer layer of protective gas in a direction deviating from the current additive area, that is, the area with the highest temperature, the tail flow of the outer layer of protective gas can be prevented from flowing to the current additive area. While increasing the flow rate and flow rate of the outer layer of protective gas and the cooling effect of the outer layer of protective gas, the influence of the outer layer of protective gas on the inner layer of protective gas in the current additive area is reduced, so that the inner layer of protective gas can better cover the current additive area, thereby effectively protecting the additive area in a high temperature state.

[0016] In a specific implementation manner, the discharge flow rate of the inner layer shielding gas is lower than the injection flow rate of the outer layer shielding gas, and the discharge flow rate of the inner layer shielding gas is lower than the injection flow rate of the outer layer shielding gas.

[0017] By adopting the above technical scheme, using an inner layer shielding gas with a low velocity and a low flow rate is beneficial to the aggregation of the inner layer shielding gas in a smaller area of ​​the current additive area, thereby reducing the consumption of the inner layer shielding gas; using an outer layer shielding gas with a high velocity and a large flow rate is beneficial to improving the cooling effect of the outer layer shielding gas and facilitating the coverage of the outer layer shielding gas over a larger range.

[0018] In a specific implementation manner, the inner layer protective gas is an inert gas, and the outer layer protective gas is liquid nitrogen.

[0019] By adopting the above technical scheme, inert gas is used as the inner protective gas, which can effectively isolate the oxygen in the air and prevent the inner protective gas itself from reacting with the high-temperature material in the additive area; liquid nitrogen is used as the outer protective gas, and the low temperature of the liquid nitrogen can be used to improve the cooling effect of the outer protective gas. The additive material can also be subjected to low-temperature treatment behind the current additive area, promoting the nucleation of the alloy melt grains of the additive material and the rapid growth of the grains, thereby improving the organizational properties of the material.

[0020] The dual-shielding gas additive processing laser head provided in this application adopts the following technical solution: A dual-shielding gas additive processing laser head comprises a base, a wire feeding unit and a plurality of coaxial powder feeding laser output heads, wherein the wire feeding unit and the plurality of coaxial powder feeding laser output heads are fixed on the base, and the plurality of coaxial powder feeding laser output heads are coaxially arranged around the wire feeding unit, and the coaxial powder feeding laser output head comprises a laser introduction channel, a collimating and focusing lens group, an annular powder feeding channel, a powder material input pipe, an inner layer protective air pipe and an outer layer protective air duct, wherein the collimating and focusing lens group is arranged in the laser introduction channel, the annular powder feeding channel is arranged on the periphery of the laser introduction channel, the powder material input pipe is connected with the annular powder feeding channel, the inner layer protective air pipe is connected with the laser introduction channel and opens at a position where the collimating and focusing lens group is located or at a side of the collimating and focusing lens group away from the laser introduction channel outlet, and the outer layer protective air duct is arranged on a side of the annular powder feeding channel away from the laser introduction channel, so as to realize the dual-shielding gas additive processing method provided by the present application.

[0021] By adopting the above technical solution, by using the inner protective gas pipe connected to the part of the laser introduction channel where the collimating and focusing lens group is located or the part of the collimating and focusing lens group away from the laser introduction channel outlet, the inner protective gas can be output to the additive area through the outlet of the laser introduction channel, so that the inner protective gas always covers the current additive area of ​​the laser processing head, and the inner protective gas flow can be used to cool the collimating and focusing lens group to prevent the abnormal increase of the temperature of the collimating and focusing lens group. By using the outer protective gas duct set on the side of the annular powder feeding channel away from the laser introduction channel, the outer protective gas can be output from the side of the annular powder feeding channel away from the laser introduction channel outlet, and while the high-speed jetted outer protective gas is used to improve the cooling effect, the high-speed gas flow of the outer protective gas on the laser introduction channel outlet area, that is, the current additive area, is reduced, and while preventing the oxidation of the material in the additive area, the effect of laser additive processing is improved.

[0022] In a specific possible implementation manner, the outlet direction of the outer protective airway deviates from the direction of the outlet of the laser introduction channel.

[0023] By adopting the above technical solution and utilizing an outer protective gas passage whose outlet direction deviates from the outlet direction of the laser introduction channel, it is possible to ensure that the spray direction of the outer protective gas is away from the input direction of the additive material powder, thereby preventing the outer protective gas flow from affecting the powder conveying path, thereby improving the utilization rate of the powder material, and improving the effect and efficiency of additive processing.

[0024] In a specific possible implementation mode, a temperature sensor is provided near the outlet of the outer protective airway, and flow control valves are provided on both the inner protective air pipe and the outer protective airway.

[0025] By adopting the above technical solution, using a temperature sensor arranged near the outlet of the outer protective air duct, it is possible to detect the moving direction of the laser head during additive processing, and control the flow control valve on the outer protective air duct at the corresponding position according to the temperature of the previous additive area behind the moving direction of the laser head, thereby controlling the outer protective gas to be sprayed through the outer protective air duct at the corresponding position and controlling the spray flow rate of the outer protective gas.

[0026] In summary, the present application includes at least one of the following beneficial technical effects: 1. By outputting the inner layer shielding gas in the additive area, the inner layer shielding gas can be concentrated and covered in the additive area, isolating the oxygen in the air in the additive area, preventing the material in the additive area from contacting with oxygen and oxidizing under high temperature, and reducing the influence of the inner layer shielding gas on the additive material powder, thereby improving the utilization rate of the additive material powder and the uniformity of its distribution in the additive area, and improving the additive effect and the efficiency of additive processing.

[0027] 2. By cooling the previously added area outside the additive area and forming a larger outer layer of shielding gas distribution range outside the additive area, the previously added area that has not been fully cooled is protected, thereby effectively protecting the previously added area after the laser head moves away, and reducing the impact of the outer layer of shielding gas flow on the inner layer of shielding gas and additive material powder, thereby ensuring the quality of additive processing.

[0028] 3. By setting temperature sensors on multiple coaxial powder feeding laser output heads around the laser head, it is possible to not only detect the location of the previous additive area and spray the outer layer of protective gas to cool and protect the previous additive area in a targeted manner, but also automatically adjust the flow rate of the outer layer of protective gas cooling airflow according to the temperature value detected by the temperature sensor to ensure the cooling effect of the previous additive area.

[0029] 4. By using liquid nitrogen as the outer protective gas, the material in the previous additive area can be treated at low temperature, promoting the nucleation of the alloy melt grains of the additive material and the rapid growth of the grains, thereby improving the organizational properties of the additive material. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flowchart of an embodiment of the dual-shielding gas additive processing method of the present application.

[0031] Figure 2 This is a flowchart of opening the outer layer of shielding gas in one embodiment of the dual shielding gas additive processing method of the present application.

[0032] Figure 3 It is a schematic diagram of an embodiment of a dual-shielding gas additive machining laser head of the present application.

[0033] Figure 4 This is a schematic diagram of the structure of a coaxial powder feeding laser output head in one embodiment of a dual-shielding gas additive machining laser head of the present application.

[0034] Explanation of the reference numerals: 1. base; 2. wire feeding unit; 3. coaxial powder feeding laser output head; 31. laser introduction channel; 32. collimating and focusing lens group; 33. annular powder feeding channel; 34. powder material input pipe; 35. inner layer protective air pipe; 36. outer layer protective airway; 37. optical fiber plug. DETAILED DESCRIPTION

[0035] The specific implementation of the present application is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present application, and is not used to limit the present application.

[0036] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "disposed" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0037] An embodiment of the dual-shielding gas additive processing method of the present application is as follows: Figure 1 As shown, the following steps are included: S100, open the valve on the inner protective gas delivery pipeline, so that the inner protective gas is delivered to the workpiece to be processed or the area on the additive base opposite to the additive processing head through the connection, that is, the area where additive processing is to be performed. The valve on the inner protective gas delivery pipeline can be a manually opened and closed valve, or an electrically controlled electromagnetic switch valve. The connecting channel can be set inside the additive processing head, or it can be set outside the additive processing head.

[0038] S200, turn on the laser output head, emit laser light to the workpiece to be processed or the additive area of ​​the additive base, and turn on the powder feeder to deliver additive material powder to the additive area through the powder feeding pipeline. It should be noted that the time of turning on the laser output head can be slightly earlier than the time of turning on the powder feeder, or slightly later than the time of turning on the powder feeder, or at the same time as the time of turning on the powder feeder.

[0039] S300. Start the motion control device so that the additive processing head moves along a set path relative to the workpiece to be processed or the additive base. Specifically, the workpiece to be processed or the additive base can be kept stationary while the additive processing head is controlled to move; the workpiece to be processed or the additive base can be controlled to move while the additive processing head is kept stationary; the workpiece to be processed or the additive base can also be controlled to move and the additive processing head can be kept stationary; the workpiece to be processed or the additive base and the additive processing head can also be controlled to move simultaneously in different forms of motion. In this specification, unless otherwise specified, "movement of the additive processing head" may refer to any of the three above-mentioned modes of motion. Depending on the shape of the additive area and the additive path, the form of movement may be rotation, translation, or a combination of the two. The movement is usually carried out under the control of a numerical control system and driven by different motion drive mechanisms.

[0040] S400, open the valve on the outer layer shielding gas delivery pipeline, so that the outer layer shielding gas is output through the delivery channel set on the additive processing head, and sprayed on the peripheral part of the current additive area on the workpiece to be processed or the additive base, and spray the outer layer shielding gas on the area that was previously processed and has deviated from the current additive area after the additive processing head moves. In the area that was previously processed, the molten pool formed by laser irradiation has just solidified, and the substrate and additive material still have a relatively high temperature. Due to the movement of the additive processing head, the previous additive area has deviated from the additive area of ​​the additive processing head, that is, deviated from the area covered by the inner layer shielding gas. The substrate and additive material with a higher temperature are easily oxidized by contact with air. Spraying the outer layer shielding gas to the peripheral area of ​​the previous additive area can not only use the outer layer shielding gas flow to cool the previous additive area, causing the temperature of the area to drop rapidly, but also use the outer layer shielding gas to continue to isolate the air in the previous additive area, reducing the contact between the material in the area and the oxygen in the air.

[0041] In some embodiments of the dual shielding gas additive processing method of the present application, Figure 2 As shown, the operation of opening the outer layer of protective gas in step S400 and spraying the outer layer of protective gas to the outside of the current additive area specifically includes the following steps: S410, opening the gas source of the outer layer shielding gas so that the outer layer shielding gas is delivered to the additive processing head.

[0042] S420, obtaining the moving direction of the additive processing head. The moving direction of the additive processing head can be obtained from a control signal for controlling the movement of the additive processing head, or can be obtained from a corresponding sensor disposed on the additive processing head.

[0043] S430, control the outer layer of protective gas to be sprayed from the rear of the moving direction of the additive processing head. Specifically, multiple outer layer of protective gas delivery pipelines can be set in different directions around the additive processing head, and a control switch is set on each outer layer of protective gas delivery pipeline. After the moving direction of the additive processing head is obtained, the control switch on the outer layer of protective gas delivery pipeline behind the moving direction is controlled to be turned on. The rear of the moving direction of the additive processing head is exactly the previous additive area on the workpiece to be processed or the additive base, that is, the area with higher temperature. Spraying the outer layer of protective gas to this area can make the outer layer of protective gas be concentratedly sprayed to the previous additive area on the workpiece to be processed or the additive base, radially targeted cooling and protection, and the utilization rate of the outer layer of protective gas is higher.

[0044] In a preferred embodiment of the dual-shielding gas additive processing method of the present application, Figure 2 As shown, in step S420, multiple temperature sensors are set at different positions around the additive processing head, and the temperature of the workpiece in different directions around the current additive area is detected simultaneously by multiple temperature sensors. Behind the moving direction of the additive processing head, that is, in the direction opposite to the moving direction of the additive processing head, is the area on the workpiece that has just been additively processed, that is, the previous additive area. This area has been irradiated by high-energy lasers during additive processing to reach a high temperature that can melt the additive material, and therefore has a higher temperature. By comparing the workpiece temperatures detected by the temperature sensors at different positions around the additive processing head, the direction opposite to the direction where the temperature sensor with the highest temperature is located is determined as the moving direction of the additive processing head.

[0045] As a specific implementation of the dual-shielding gas additive processing method of the present application, Figure 2 As shown, step S400 also includes the step: S440, controlling the injection flow rate of the outer layer shielding gas according to the temperature behind the moving direction of the additive processing head detected by the temperature sensor. The temperature behind the moving direction of the additive processing head is the temperature of the previous additive area, and is also the highest temperature detected by the multiple temperature sensors.

[0046] The higher the temperature in this area, the easier it is for the base material and additive material to be oxidized by contact with air, so they need to be cooled more quickly and better isolated from the air. At this time, it is necessary to increase the injection flow of the outer layer of shielding gas, use a larger outer layer of shielding gas flow to cool the workpiece, improve the cooling effect of the workpiece, and make the temperature of the workpiece drop at a faster rate; at the same time, the larger flow of outer layer of shielding gas can better isolate the air outside the area.

[0047] The lower the temperature in this area, the slower the reaction of the base material and the additive material with oxygen, and the lower the requirement for isolation from oxygen in the air. At this time, reducing the injection flow of the outer layer of protective gas, reducing the cooling rate of the previous additive area, and reducing the degree of isolation between the workpiece and the air outside the area can reduce the consumption of the outer layer of protective gas and reduce the cost of additive processing.

[0048] In some embodiments of the dual-shielding gas additive processing method of the present application, in step S430, the outer layer of shielding gas is sprayed in a direction that deviates from the current additive area. Specifically, the spraying direction of the outer layer of shielding gas can be in the direction opposite to the moving direction of the additive processing head, or in the direction perpendicular to the moving direction of the additive processing head, or obliquely to the side and rear of the moving direction of the additive processing head. In this way, it is possible to prevent the high-speed airflow of the outer layer of shielding gas from flowing in the direction of the powder outlet of the additive processing head, changing the flow direction of the additive material powder, causing the distribution position of the additive material powder on the workpiece to shift, reducing the utilization rate of the additive material powder, and even affecting the transportation of the additive material powder to the workpiece, resulting in the inability to perform additive processing normally. It is also possible to prevent the fast airflow of the outer layer of shielding gas from dispersing the inner layer of shielding gas covering the current additive area, thereby ensuring the effect of the inner layer of shielding gas isolating the air.

[0049] In some embodiments of the dual-shielding gas additive processing method of the present application, the discharge flow rate of the inner shielding gas is lower than the injection flow rate of the outer shielding gas. A lower flow rate is conducive to the gathering of the inner shielding gas in the current additive area, improving the effect of the inner shielding gas isolating oxygen; while a higher flow rate is conducive to the outer shielding gas contacting with the material in the previous additive area, which is conducive to improving the heat transfer rate between the workpiece material and the gas flow.

[0050] At the same time, the discharge flow rate of the inner layer of protective gas is lower than the injection flow rate of the outer layer of protective gas. The inner layer of protective gas mainly plays an isolating role, and the lower flow rate also makes the loss of the inner layer of protective gas slower. The lower discharge flow rate can ensure the effective coverage of the inner layer of protective gas in the current additive area. The outer layer of protective gas needs to start the dual functions of cooling and protection. The larger injection flow rate can improve the heat dissipation effect of the outer layer of protective gas. At the same time, the larger injection flow rate can also make up for the impact of the faster injection flow rate on the stability of the outer layer of protective gas, ensuring that there is sufficient outer layer of protective gas coverage in the previous additive area to form an effective oxygen isolation protection.

[0051] In some embodiments of the dual-shielding gas additive processing method of the present application, the inner shielding gas generally uses various inert gases, such as helium, argon or nitrogen, etc. The chemical activity of inert gases is relatively poor and will not chemically react with the base material or additive material at high temperature. Using inert gas to isolate the air can effectively protect the base material and additive material at high temperature.

[0052] Liquid nitrogen is used as the outer protective gas. Liquid nitrogen is formed by liquefying nitrogen at low temperature. Liquid nitrogen has low chemical activity and lower temperature. It can quickly cool the previous additive area and cold-treat the high-temperature material after additive processing, causing the material's lattice to change. It can also promote the nucleation of the additive material alloy melt grains and the rapid growth of the grains, effectively improving the material's organizational properties.

[0053] Compared with the existing method of using liquid nitrogen to cool the additive area, the liquid nitrogen in the present application is transported to the previous additive area that deviates from the current additive area. On the one hand, it avoids the influence of the liquid nitrogen gas flow on the additive material powder transportation path and ensures the utilization rate of the additive material powder. On the other hand, it separates the laser heating area and the liquid nitrogen cooling area from each other, reducing the mutual influence between the heating effect and the cooling effect, while maintaining the additive processing effect and the cold treatment effect of the additive material.

[0054] An embodiment of the dual-shielding gas additive processing laser head of the present application is as follows: Figure 3 and Figure 4 As shown, it includes a base 1, a wire feeding unit 2 and a plurality of coaxial powder feeding laser output heads 3. The base 1 is the installation base of other components in the additive processing laser head, which ensures the positional relationship between other components. The wire feeding unit 2 and the plurality of coaxial powder feeding laser output heads 3 are fixed on the base 1, wherein the wire feeding unit 2 is installed in the middle position of the base 1 and is vertically arranged with the middle part of the base 1. A wire feeding channel is arranged inside the wire feeding unit 2, and the wire feeding unit 2 can slowly transport the additive material wire to the laser irradiation area at the end of the additive processing laser head, and use a high-energy laser to melt the additive material wire and the matrix material of the workpiece to be processed or the previously additive material at the same time to perform additive processing.

[0055] The coaxial powder feeding laser output head 3 is arranged on the base 1 and is located on the same circumference of the wire feeding unit 2, and is coaxially arranged with the wire feeding channel of the wire feeding unit 2. Multiple coaxial powder feeding laser output heads 3 can simultaneously set laser beams to the additive area, and multiple laser beams heat the additive material at the same time, or heat the base material and the additive material at the same time, which can increase the size and depth of the molten pool formed by laser irradiation in the additive area, and can melt more additive materials; at the same time, multiple coaxial powder feeding laser output heads 3 can also form multiple powder feeding channels for feeding powder to the additive area, and transport more additive material powder to the additive area. In this way, the processing efficiency of additive processing can be effectively improved.

[0056] like Figure 4As shown, the coaxial powder feeding laser output head 3 includes a laser introduction channel 31, a collimating and focusing lens group 32, an annular powder feeding channel 33, a powder material input pipe 34, an inner layer protective air pipe 35 and an outer layer protective air channel 36. The laser introduction channel 31 is arranged at the center of the coaxial powder feeding laser output head 3, and runs through both ends of the coaxial powder feeding laser output head 3. An optical fiber plug 37 is arranged at one end of the laser introduction channel 31, and the optical fiber plug 37 is used to guide the laser beam into the laser introduction channel 31, and output through the other end of the laser introduction channel 31, and irradiate the workpiece for additive processing. The optical fiber plug 37 can use various existing suitable products, and usually SMA905, D80, QCS, QBH, etc. can be used.

[0057] The collimating and focusing lens group 32 is arranged in the laser introduction channel 31, which includes a collimating lens group and a focusing lens group. The collimating lens group collimates the laser beam introduced through the optical fiber plug 37 so that the laser rays in the laser beam are parallel to each other; the focusing lens group focuses the parallel laser beam so that it irradiates the workpiece within a set range, melting the workpiece substrate and the additive material to form a molten pool.

[0058] The annular powder feeding channel 33 is arranged at the periphery of the laser introduction channel 31 and is coaxially arranged with the laser introduction channel 31. The additive material powder can be uniformly transported to the molten pool area formed by laser irradiation through the annular powder feeding channel 33, melted in the molten pool under high-energy laser irradiation, and reliably combined into the base material to form additive processing on the base material.

[0059] One end of the powder material input pipe 34 is connected to the annular powder feeding channel 33, and the other end is connected to a powder feeder (not shown in the figure). The powder feeder drives the set flow rate of additive material powder to enter the powder material input pipe 34, and enter the annular powder feeding channel 33 through the powder material input pipe 34. It is also possible to set multiple powder material input pipes 34 at different positions around the annular powder feeding channel 33, and to simultaneously transport the additive material powder into the annular powder feeding channel through the multiple powder material input pipes, thereby improving the uniformity of the distribution of the additive material powder in the annular powder feeding channel 33.

[0060] One end of the inner protective gas pipe 35 is connected to the laser introduction channel 31, and the other end is connected to the inner protective gas source (not shown in the figure). The inner protective gas pipe 35 can also be provided with an inner protective gas control valve (not shown in the figure), and the inner protective gas pipe 35 can be controlled by the control valve to control the opening and closing of the inner protective gas pipe 35 and the flow rate of the inner protective gas. The connection end of the inner protective gas pipe 35 and the laser introduction channel 31 is opened at the location of the collimating and focusing lens group 32, or at the location of the collimating and focusing lens group 32 away from the outlet of the laser introduction channel 31, so that the inner protective gas flows through the collimating and focusing lens group 32, and then flows to the outlet of the laser introduction channel 31, and flows out through the outlet of the laser introduction channel 31, occupying the molten pool formed by the laser beam irradiation and its surrounding area. When the inner protective gas flows through the collimating and focusing lens group 32, it can take away the heat generated by the laser irradiation on the collimating and focusing lens group 32, forming a cooling effect on the collimating and focusing lens group 32.

[0061] The outer protective air channel 36 is arranged on the side of the annular powder feeding channel 33 away from the laser introduction channel 31. Specifically, the outer protective air channel 36 can be arranged in the side wall of the annular powder feeding channel 33, or can be attached to the outer surface of the side wall of the annular powder feeding channel 33 in the form of an independent pipeline. One end of the outer protective air channel 36 is connected to the outer protective air source (not shown in the figure) through a pipeline, and the other end extends to the area adjacent to the powder outlet of the annular powder feeding channel 33, and the outer protective air is transported to the peripheral area of ​​the powder feeding area of ​​the annular powder feeding channel 33. The outer protective air is used to cool the periphery of the additive area and provide isolation protection for a larger area around the additive area. An outer protective air control valve (not shown in the figure) is arranged on the outer protective air channel 36 or its air supply pipeline. The control valve can control the on-off of the outer protective air supply channel and the flow rate of the outer protective air.

[0062] By simultaneously delivering the inner layer protective gas through the laser introduction channels 31 of multiple coaxial powder feeding laser output heads 3, it is possible to use the laser introduction channels 31 of each coaxial powder feeding laser output head 3 to deliver a smaller flow of inner layer protective gas, gather more inner layer protective gas in the additive area, improve the protective effect of the inner layer protective gas, and reduce the impact of the flow of the inner layer protective gas on the delivery of the additive material powder. By setting the outer layer protective gas channel 36 outside the annular powder feeding channel 33 on multiple coaxial powder feeding laser output heads 3, the outer layer protective gas can be delivered to multiple different positions around the additive area, cooling different areas around the additive area and providing isolation protection.

[0063] The dual-shielding gas additive processing laser head of the present application can realize any dual-shielding gas additive processing method provided in the present application.

[0064] In some embodiments of the dual-shielding gas additive processing laser head of the present application, such as Figure 3 and Figure 4 As shown, the outlet end of the outer protective gas channel 36 is bent toward one side of the extension direction of the outer protective gas channel 36, so that the outlet direction deviates from the outlet direction of the laser introduction channel 31. Generally, the outlet end of the outer protective gas channel 36 is bent toward a side away from the side wall of the annular powder feeding channel 33, so that the outer protective gas flows toward an area away from the outlet of the annular powder feeding channel 33, that is, away from the additive area.

[0065] The outlet end of the outer protective air duct 36 can also be bent in the tangential direction of the side wall of the annular powder feeding channel 33, so that the outflow direction of the outer protective gas can deviate from the additive area, preventing the outer protective gas flow from affecting the powder feeding path.

[0066] Of course, different outlet directions of the outer layer protective air duct 36 can also be formed by closing the end of the outlet end of the outer layer protective air duct 36 and opening air outlet holes in different directions of the side wall of the end.

[0067] In a preferred embodiment of the dual-shielding gas additive machining laser head of the present application, a temperature sensor is provided near the outlet of the outer-layer shielding gas channel 36. The temperature sensor is usually provided on the outer side wall of the annular powder delivery channel 33 near the outlet of the outer-layer shielding gas channel 36 and points to the outlet direction of the outer-layer shielding gas channel 36. The inner-layer shielding gas control valve provided on the inner-layer shielding gas pipe 35 or its gas supply pipeline and the outer-layer shielding gas control valve provided on the outer-layer shielding gas channel 36 or its gas supply pipeline are both flow control valves.

[0068] Typically, both the inner layer protective gas control valve and the outer layer protective gas control valve use flow control solenoid valves, and the temperature sensor and the flow control solenoid valve are connected to the controller of the additive processing equipment. The controller can control the valve opening size of the inner layer protective gas control valve as required, thereby controlling the gas supply flow of the inner protective gas; the controller can control the on-off or valve opening size of the outer layer protective gas control valve according to the workpiece temperature of the area pointed to by the outlet of the outer layer protective gas duct 36 detected by the temperature sensor, thereby controlling the output of the outer layer protective gas from the outer layer protective gas duct 36 in the area with higher temperature, and controlling the flow size of the output outer layer protective gas, thereby forming an accurate control of the cooling effect of the outer layer protective gas.

[0069] In the description of the present application, the description with reference to the terms "one embodiment", "specific embodiment", "preferred embodiment", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0070] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A double-shielding gas additive processing method, characterized in that: The steps include: S100, opening the inner layer protective gas, and outputting the inner layer protective gas to the additive area; S200, turning on the laser output head and the powder feeder to feed powder to the additive area; S300, controlling the additive processing head to move along a set path relative to the workpiece or the additive base; S400, turning on the outer layer of protective gas, and spraying the outer layer of protective gas to the outside of the current additive area.

2. The double-shielding gas additive processing method according to claim 1, characterized in that: Step S400 includes the following steps: S410, opening the gas source of the outer protective gas; S420, obtaining a moving direction of the additive processing head; S430, controlling the outer layer of protective gas to be sprayed from behind the moving direction of the additive machining head.

3. The double-shielding gas additive processing method according to claim 2, characterized in that: In step S420, the moving direction of the additive processing head is obtained by detecting the temperature of different parts of the periphery of the current additive area by a temperature sensor.

4. The double-shielding gas additive processing method according to claim 3, characterized in that: Step S400 also includes the step: S440, controlling the injection flow rate of the outer layer shielding gas according to the temperature behind the additive processing head in the moving direction detected by the temperature sensor.

5. The double-shielding gas additive processing method according to claim 2, characterized in that: In step S430, the spraying direction of the outer layer of shielding gas deviates from the direction of the current additive area.

6. The double-shielding gas additive processing method according to claim 1, characterized in that: The discharge flow rate of the inner layer protective gas is lower than the injection flow rate of the outer layer protective gas, and the discharge flow rate of the inner layer protective gas is lower than the injection flow rate of the outer layer protective gas.

7. The double-shielding gas additive processing method according to claim 1, characterized in that: The inner layer protective gas is an inert gas, and the outer layer protective gas is liquid nitrogen.

8. A dual-shielding gas additive processing laser head, characterized in that: The invention comprises a base (1), a wire feeding unit (2) and a plurality of coaxial powder feeding laser output heads (3), wherein the wire feeding unit (2) and the plurality of coaxial powder feeding laser output heads (3) are fixed on the base (1), the plurality of coaxial powder feeding laser output heads (3) are coaxially arranged around the wire feeding unit (2), the coaxial powder feeding laser output heads (3) comprising a laser introduction channel (31), a collimating and focusing lens group (32), an annular powder feeding channel (33), a powder material input pipe (34), an inner protective air pipe (35) and an outer protective air channel (36), the collimating and focusing lens group (32) being arranged in the laser introduction channel (31), the annular The annular powder feeding channel (33) is arranged on the periphery of the laser introduction channel (31), the powder material input pipe (34) is connected to the annular powder feeding channel (33), the inner layer protective air pipe (35) is connected to the laser introduction channel (31), and opens at the position where the collimating and focusing lens group (32) is located or at a side of the collimating and focusing lens group (32) away from the exit of the laser introduction channel (31), and the outer layer protective air duct (36) is arranged on a side of the annular powder feeding channel (33) away from the laser introduction channel (31), so as to realize the dual protective gas additive processing method according to any one of claims 1 to 7.

9. The dual-shielding gas additive processing laser head according to claim 8, characterized in that: The outlet direction of the outer protective airway (36) deviates from the direction of the outlet of the laser introduction channel (31).

10. The dual-shielding gas additive processing laser head according to claim 9, characterized in that: A temperature sensor is provided near the outlet of the outer protective air duct (36), and flow control valves are provided on both the inner protective air pipe (35) and the outer protective air duct (36).

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