| Aiming at the problem that the sprocket of the scraper conveyor wears too fast in the working process,it is proposed to add a certain thickness layer with high hardness and wear resistant to the surface of the chain socket by using the arc additive manufacturing technology.By comparing the current researches on various arc additive processes,CMT(Cold Metal Transfer)technology with low heat input and large deposition rate is determined as the process method,and robot is used to realize the automated stacking process.The CMT additive manufacturing system was set up,and including: 6 DOF arc welding robot,CMT welding system,computer with parameter collection,etc.The robot and the welding system communicate through the Rob5000 module,and Motocom32 is used for communication between the computer and the robot.According to the technological requirements,the corresponding fixtures and preheating devices were designed.The test material is 42 Cr Mo steel commonly used in sprockets,and the welding material is GFC-103 wear-resistant flux-cored wire.The CMT additive manufacturing process experiment was carried out,and the rules of wire feed speed,the ratio of welding speed and wire feed speed,preheating temperature and macro forming of the overlay,dilution rate,interface bonding strength and hardness of the overlay were studied.The results show that,In the case of no cracks,choosing a lower preheating temperature and wire feed speed and a higher welding speed is more conducive to obtaining an excellent combination of forming quality and performance indicators.On this basis,small heat input process tests were carried out for the flat,horizontal,and vertical positions of the chain socket stacking process respectively,and the optimal forming specification suitable for the chain socket curved surface was determined.At the same time,according to the influence of uneven edge and the arc initiation and quenching on the forming,a processing scheme of contour offset scanning path and bow-shaped scanning path were proposed.The CMT additive path planning technology of the chain-socket curved surface is studied.According to the principle of discrete stacking,the layered design of the additive area was first carried out,and compared the plane layering and surface layering.The contour change of each layer obtained by the surface layer is smoother,the surface shape is regular,and the problem of flow and collapse would not occur during the additive process.After obtaining the surface of each layer,the vertical filling paths,the horizontal filling paths and the offset contour path planning were carried out on the surface respectively.The obtained path points are smooth and continuous,which adapts well to the contour of the surface.On the basis of obtaining the welding gun's walking path,it is necessary to determine the attitude information of the welding gun at each path point.By comparing the different situations,it was found that during the longitudinal filling process,when the circumferential plane of the sprocket is placed parallel to the robot body and the welding torch walks in an advancing manner,the joints of the robot change smoothly without mutation.Similarly,when horizontal filling and offset contour scanning are performed,and the relative position of the sprocket and the posture of the robot are similar to the vertical filling,there is no singular point in each joint of the robot,and the stacking process is stable.The obtained posture information is converted into a robot code program,which is imported into the robot control cabinet to verify the actual chain nest.The results show that the surface of the cladding layer keeps the shape of the surface,the interior is even and flat,the edges are adapted to the surrounding contours,and there is no situation beyond the contour edges.It is verified that the obtained path planning algorithm and CMT cladding process can be applied to the additive manufacturing of the chain surface process. |
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