Temperature field control method in laser additive manufacturing process

A control method and manufacturing process technology, applied in the direction of additive manufacturing, additive processing, process efficiency improvement, etc., can solve problems affecting the performance of components, different microstructures, etc., and achieve easy promotion, reduction of residual stress, and realization of process simple effect

Pending Publication Date: 2022-07-12
JIANGSU FEIYUE PUMP GRP
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AI-Extracted Technical Summary

Problems solved by technology

Moreover, with the progress of the additive manufacturing process, due to the accumulation of more and more heat in the formed component, the temperature gradient of the laser melt pool when the bottom of the comp...
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Method used

Before the additive manufacturing, when the laser beam is turned on but not feeding powder or wire, utilize the original laser beam in the additive manufacturing equipment to scan the substrate or the component to be repaired, and ensure that the substrate or the component to be repaired will not Melting occurs, but the temperature of the substrate or component to be repaired is increased, which reduces the temperature gradient in and around the laser melt pool during additive forming. Moreover, the consistency of the temperature gradient of the laser melt pool during the additive forming of the lower, middle and upper parts of the component can also be ensured through the inp...
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Abstract

The invention relates to the field of metal component additive manufacturing, in particular to a temperature field control method in the laser additive manufacturing process. The method comprises the following steps that firstly, metal powder for the impeller and heterogeneous nucleation refiner powder are mixed; secondly, slicing software is used for conducting slicing and scanning path area discretization planning on the digital model of the impeller component to be formed; thirdly, laser energy input is changed into discontinuous input according to a planned scanning path; and fourthly, laser additive manufacturing is conducted. In-situ preheating and resistance tape or resistance wire heating in the laser additive manufacturing process are combined together, heat preservation is conducted through heat preservation sand or heat preservation cotton, the temperature gradient in a component to be manufactured or remanufactured can be reduced, residual stress can be reduced, and regulation and control over the microstructure of a formed part can be achieved by controlling the heating temperature. The method is high in applicability, not only can be used for additive manufacturing of the metal component, but also can be used for repairing and remanufacturing of the metal component.

Application Domain

Additive manufacturing apparatusIncreasing energy efficiency

Technology Topic

RemanufacturingHeat conservation +7

Image

  • Temperature field control method in laser additive manufacturing process
  • Temperature field control method in laser additive manufacturing process
  • Temperature field control method in laser additive manufacturing process

Examples

  • Experimental program(1)

Example Embodiment

[0040] Example 1:
[0041] This embodiment adopts the control method of the temperature field provided by the present invention to carry out the laser powder feeding and additive repair and remanufacturing of the difficult-to-weld DD5 nickel-based superalloy component, and the technological process is as follows:
[0042] (1) Preparation of external heating device: The nickel-chromium resistance strip is prepared into a cylindrical heating device with a diameter of 100mm, and a layer of insulation cotton is laid around the periphery of the resistance strip, and a base is placed at the bottom of the device. This heating device is connected with a low voltage regulated power supply, and the heating rate can be adjusted by changing the voltage.
[0043] (2) Filling of thermal insulation sand: Fix the component to be repaired on the inner base of the above-mentioned cylindrical heating device, spread thermal insulation sand around the blade, and bury most of the area of ​​the component to be repaired (see figure 2 ). Two or more thermocouples can be dispersed in the insulating sand. One end of the thermocouple extends into the insulating sand, and the other end of the thermocouple is connected to the temperature controller through a wire to measure and monitor the temperature changes of different parts in real time, which is convenient for regulating the laser molten pool. temperature field. After the connection is completed, the power supply of the external heating device can be turned on to heat the insulating sand. When the temperature in the insulating sand rises to 500°C, adjust the voltage so that the temperature is at 500°C for about 20 to 30 minutes before laser additive manufacturing. In order to prevent rapid heat dissipation to the surrounding environment, a layer of thermal insulation baffle can be laid on the upper surface of the thermal insulation sand. The middle of the insulation cotton or insulation baffle must be hollowed out to expose the surface of the piece to be repaired.
[0044] (3) Use slicing software such as Magics to slice and scan the UG or CAD digital model of the three-dimensional shape of the sample to be formed. On the basis of the existing path planning, when the laser is turned on but the powder has not been sent, the related procedures of scanning the surface of the component to be repaired by the laser beam are added to preheat it in situ, so that the temperature of the upper surface of the metal component reaches 600 °C. At this point, powder feeding is started and laser additive molding is performed.
[0045] In this embodiment, the laser beam diameter is 0.8-1.2mm, the laser power is 500-1200w, the laser scanning speed is 1000-2000mm/min, the powder feeding amount is 10-20g/min, and the layer thickness is 0.2-1.0mm.
[0046] (4) Analysis of the microstructure of the obtained component: As shown in Figure 3, it can be seen from the microstructure and morphology of the additive manufacturing area of ​​the obtained component that the microstructure and dendritic spacing of the upper and lower parts of the component are the same, and there are no microcracks in the component. and other metallurgical defects. This shows that the temperature field of the laser molten pool is relatively consistent and the internal stress is also small when the upper and lower parts of the component are formed.
[0047] The results of the examples show that the method of the present invention combines the external heating source and the laser in-situ preheating, and increases the thermal insulation sand around the formed part, which can stabilize the temperature field of the component, reduce the thermal stress during the additive manufacturing process of the component, and also Ensure that the microstructure of the upper and lower parts of the component is uniform.

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