| In this paper, the XK6336CNC rocker milling machine was modified as awithdrawing type friction stir welding machine, the original machine frame andworkbench were retained, the B axis rotating device, Z axis CNC slide seat and theWithdrawing type milling head with the retractable pin tool were redesigned. TheADAPT friction stir welding machine has a6degrees-of-freedom and5-axis linkagecontrol system after refitted. The6degrees of freedom were the axis of workbenchlateral movement (X axis), the axis of workbench longitudinal movement (Y axis), theaxis of the milling head telescopic movement (Z axis), the axis of the pin tooltelescopic movement (Z axis), the axis of the milling head rotary movement (B axis),the axis of the NC rotary table rotary movement (C axis). The5linkage control axesare X, Y, Z, B and C. The Withdrawing type friction stir welding machine canachieve the following welding procedure test.(1) The lines, circles and curves weldsin the XY plane.(2) The girth weld and the fluctuation weld in XZ plane.(3) Theweld of materials with variation in thickness.(4) Eliminated the keyhole in the end ofthe weld.(5) The keyless hole of friction stir spot welding.According to the process parameters of FSW and the forces of the cylindricaltool in the FSW process, the basic parameters of the6axes and mechanical indicatorof machine were determined. The6mm thick plates of7075(T6) aluminum alloyswere welded by friction stir welding, while the maximum, mean and variation curveof the axial and radial forces of the cylindrical tool to during the welding process weremeasured. The bearing friction torque of the cylindrical tool was calculated. Themechanical indicators of machine were obtained from the forces and torques of thecylindrical tool to multiplied by1.5to1.8times of safety factor. Mechanicalindicators of machine were showing as follows: the maximum and average axial forceof the cylindrical tool were25kN and12.5kN, the maximum and average radial forceof the cylindrical tool were2.5kN and1.25kN, the maximum and average frictiontorque of the cylindrical tool were50Nm and20Nm, the maximum and average axialforce of the cylindrical pin tool were6.5kN and2.7kN, the maximum and averagefriction friction torque of the cylindrical tool were5Nm and2.5Nm.According to the mechanical indicators of machine, the feasibility of the retainpart of the original milling machine was checked, and the B axis rotating device, Z axis CNC slide seat and the withdrawing type milling head were redesigned. The stirpin withdrawing device was added in the withdrawing type milling head on the basisof motorized spindle, which can adjust the length of the stir pin in the welding process,and can be used to welding of materials with variation in thickness, eliminating thekeyhole in the end of the weld and realizing the keyless hole of friction stir spotwelding. Z axis CNC slide seat drag the milling head to up and down, which torealizing the inserted and exited in the workpiece of the stir pin. The B axis rotatingdevice control Z axis CNC slide seat and the milling head to rotate around the Y-axis,which to achieved the inclination of the milling head and the workpiece. and the girthworkpiece and the fluctuation weld can be welded in the X Z vertical plane by theassociated movement of X, Y, Z and B axis.After the assembly of all parts, geometric accuracy and motion accuracy of thewithdrawing type friction stir welding machine was detected by using a laser tracker.The results shown that the geometric accuracy and motion accuracy of eachmovement axis (were) meet the technical requirements. The friction stir weldingprocess was used to verify the functional requirements of the machine, the lines,circles and curves welds were completed at present. |
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