Study On Laser Metal Additive Repair Technology For Ingot Picking

Spindle picking is one of the most important parts of cotton picker.The quality of picking ingots determines the net harvest rate of cotton.Due to the harsh working environment of ingot picking,it often fails due to the wear of hook teeth,the broken hook teeth or the broken head,resulting in frequent replacement and large demand.Laser metal additive manufacturing technology is a manufacturing technology that uses a laser as a heat source to stack molten metal layer by layer on the substrate to finally form a three-dimensional part.The technology has the advantages of small heat input,less deformation of parts,and strong material applicability and so on.It can be used to repair precision parts.This paper mainly studies the repair of ingot picking by using laser additive manufacturing technology.The main contents include:(1)The key instruments and equipment for repairing ingots and the process parameters of laser additive repair technology are studied.The orthogonal test method,micro morphology analysis method,micro hardness test method,friction test method and wear test method are designed to repair ingots.A quality characterization method for repairing ingots is put forward.(2)On the basis of analyzing the working principle of ingot picking,it is concluded that wear is the main form of ingot picking failure.Through the stress analysis,reducing the cross-sectional diameter of the spindle head can ensure the picking force,but weaken the strength of the spindle.Fracture analysis and SEM are used to study the failure mechanism of electrodeposited coating on ingot picking,and three main ingot picking products are compared,which came to the conclusion that the domestic K series coating is thin,the surface quality is poor,and the ingot is more likely to fail.Through the mechanical property test,the materials of three series of ingots are analyzed,the properties of each group of materials are numerically simulated by finite element method.Compared with the other two materials,the mechanical properties of 20 Cr ingot were worse.(3)Taking 20 Cr matrix ingot as the target,the feasibility of repairing 20 Cr with 431 alloy powder is studied.Orthogonal experiments are designed to study the effects of laser power,scanning speed and powder feeding speed on the forming of 431 alloy powder on 20 Cr matrix.The quality of the repair material is tested by microhardness and wear test.The test shows that when the laser power is 1.2k W,the scanning speed is15mm/s,and the powder feeding speed is within the range of 1.5-2.5g/min.The sample blocks obtained after the test have no cracks and pore defects on the surface,which proves that the selection of each process parameter range formulated is reasonable.Finally,the real object repair test is completed.(4)The rapid prototyping process of ingot picking is studied.The inclined groove forming process and vertical groove processing method are designed,and then the corresponding processing tools and the combined processing equipment combined with joint robot are designed.Through the field test on the repaired ingot,it is found that the wear degree of the repaired ingot is less than that of the common ingot.The cost of repair ingot picking is analyzed,and the cost should be constantly reduced in the later research.