Design And AppliedResearch On Powder Feeding Device For Laser Cladding

Laser cladding, as a kind of surface modification techniques, can be used to fabricate high performance alloy coating on material surface or repair the partial of parts in remanufacturing industry. With the development of control and computer technology, laser cladding technology turns to be more intellectualized and automatic, meanwhile, a three-dimension (3D) movement laser cladding technology has been utilized to fabricate metal components instead of its ancestors such as1D and2D laser cladding. The rapid prototyping of metal material technology is a novel laser application technology, which is upgrade on the basis of laser cladding technology.Normally, there are two main powder feeding mechanisms applying in laser cladding technique, donated pre-placing and synchro delivery method respectively. Laser cladding with the latter way means that the cladding layer can be formed by alloy powders feeding from delivery device and then injected into laser induced melt pool simultaneously, which will generate metallurgical bonding interface between substrate and cladding layer. Comparing with cladding layer fabricated by pre-placing way, synchro delivery method is more flexible to prepare lower dilution cladding layer. Moreover, the factors affecting quality of cladding layer are not only including properties of powders, laser power and scanning speed, but also having relationship with precision, stability and continuity of feeding device. Therefore, it is important for a laser cladding system to have a suitable feeding device with excellent properties.In this experiment, on based of mechanical theory, a self-made powder feeding device with mechanical transmission and motor control system was designed and manufactured. In order to observe mobility of alloy powders in an operating device, transparent organic glasses were used to manufacture thread and shaft sleeve. The stability and accuracy of devicewere checked in different situations based on influences of thread spindle with different thread profile and diameter. Then Fe50powders were used as raw materials, cladding layers were prepared on A3substrate by FD-Light laser with self-made powder feeding device, what’s more, aiming at exploring the influence of process parameters for layer’s quality, a investigation had been completed on samples fabricated by different laser power, scanning speed and powder feeding speed. And OM, micro-hardness tester, and DPI-5dye penetration inspection were applied to characterize the size, macro-appearance, crack and micro-hardness of samples in this experiment.The conclusions are shown as follows according to results:the powder feeding device has good stability, continuity, accuracy and adjustability. Additionally, powder feeding speed has a linear relation with revolution of motor, but is irrelevant to parameter of thread spindle; the feeding amount of powder per unit time increases as the diameter of thread spindle ascends, and with the same rotary speed of motor, powder feeding speed of saw-tooth thread spindle is faster than that with standard one; the width, height and micro-hardness of cladding layers can be varied with laser power, scanning speed and powder feeding speed, and interestingly, with a stable laser power and scanning speed, micro-hardness of cladding layer obtain maximum when rotary speed is400r/min.