Method for manufacturing joined member and apparatus for manufacturing the same

Abstract

To provide a method and apparatus for manufacturing a joined member that inhibit occurrence of cracks in a joined member even when the joined portion is quenched when members are welded together. The method includes placing the first member D and the second member E with a joint target portion Df and a joint target portion Ef being in contact with each other, welding the joint target portions by heating, subjecting the first member D after the welding to a process for inhibiting occurrence of cracks, and tempering a portion where the first and second members have been welded to each other by electromagnetic heating. The apparatus includes a first electrode 11 to contact with the first member D; a second electrode 12 to contact with the second member E; and an induction heating coil 23 for performing induction heating of a portion where a joint target portions Df and Ef have been contacted and joined to each other, and the induction heating coil 23 is placed between the two electrodes 11 and 12 when the induction heating is performed.

1 . A method for manufacturing a joined member by joining a first member formed of a metal material having a possibility of undergoing quenching and a second member formed of a metal material, the method comprising:
 a contact-placing step of placing the first member and the second member with a joint target portion of the first member and a joint target portion of the second member being in contact with each other;   a welding step of welding the joint target portions of the first member and the second member by heating;   a crack-inhibition step of subjecting the first member after the welding step to a process for inhibiting occurrence of cracks;   an electromagnetic heating step of tempering a portion where the first member and the second member have been welded to each other by electromagnetic heating;   wherein the welding step is a step of performing resistance welding of the joint target portions of the first member and the second member with simultaneous application of pressure; and   wherein the crack-inhibition step includes heating the portion where the first member and the second member have been welded to each other, by passing an electric current therethrough in order to achieve preliminary tempering.   
     
     
         2 . The method for manufacturing a joined member according to  claim 1 ,
 wherein the electromagnetic heating step is achieved by induction heating using an induction heating coil, and the electromagnetic heating step includes: placing the induction heating coil in a vicinity of a first edge forming an outer circumference of a joint surface between the first member and the second member; and tempering the joint surface on a side of an opposite edge opposed to the first edge first and then tempering the joint surface on a side of the first edge with an output from the induction heating coil reduced to a level lower than that used to temper the joint surface on the side of the opposite edge.   
     
     
         3 . The method for manufacturing a joined member according to  claim 1 ,
 wherein the electromagnetic heating step is achieved by induction heating using induction heating coils, and the electromagnetic heating step includes: placing one of the induction heating coils in a vicinity of a first edge forming an outer circumference of the joint surface between the first member and the second member and the other in a vicinity of an opposite edge opposed to the first edge of the joint surface, and tempering the joint surface on the side of the first edge with the induction heating coil placed in the vicinity of the first edge and tempering the joint surface on the side of the opposite edge with the induction heating coil placed in the vicinity of the opposite edge.   
     
     
         4 . A method for manufacturing a joined member by joining a first member formed of a metal material having a possibility of undergoing quenching and a second member formed of a metal material, the method comprising:
 a contact-placing step of placing the first member and the second member with a joint target portion of the first member and a joint target portion of the second member being in contact with each other;   a welding step of welding the joint target portions of the first member and the second member by heating;   a crack-inhibition step of subjecting the first member after the welding step to a process for inhibiting occurrence of cracks; and   an electromagnetic heating step of tempering a portion where the first member and the second member have been welded to each other by electromagnetic heating;   wherein the electromagnetic heating step is achieved by induction heating using an induction heating coil, and the electromagnetic heating step includes: placing the induction heating coil in a vicinity of a first edge forming an outer circumference of a joint surface between the first member and the second member; and tempering the joint surface on a side of an opposite edge opposed to the first edge first and then tempering the joint surface on the side of the first edge with an output from the induction heating coil reduced to a level lower than that used to temper the joint surface on the side of the opposite edge.   
     
     
         5 . A method for manufacturing a joined member by joining a first member formed of a metal material having a possibility of undergoing quenching and a second member formed of a metal material, the method comprising:
 a contact-placing step of placing the first member and the second member with a joint target portion of the first member and a joint target portion of the second member being in contact with each other;   a welding step of welding the joint target portions of the first member and the second member by heating;   a crack-inhibition step of subjecting the first member after the welding step to a process for inhibiting occurrence of cracks; and   an electromagnetic heating step of tempering a portion where the first member and the second member have been welded to each other by electromagnetic heating;   wherein the electromagnetic heating step is achieved by induction heating using induction heating coils, and the electromagnetic heating step includes: placing one of the induction heating coils in a vicinity of a first edge forming an outer circumference of the joint surface between the first member and the second member and the other in a vicinity of an opposite edge opposed to the first edge of the joint surface, and tempering the joint surface on the side of the first edge with the induction heating coil placed in the vicinity of the first edge and tempering the joint surface on the side of the opposite edge with the induction heating coil placed in the vicinity of the opposite edge.   
     
     
         6 . The method for manufacturing a joined member according to  claim 4 ,
 wherein the welding step is a step of performing resistance welding of the joint target portions of the first member and the second member with simultaneous application of pressure; and   wherein the crack-inhibition step includes maintaining the application of pressure in the welding step.   
     
     
         7 . A joined member manufacturing apparatus for manufacturing a joined member, the joined member being manufactured by joining a first member and a second member, the first member being made of a metal material having a possibility of undergoing quenching, the second member being made of a metal material, the joined member manufacturing apparatus comprising:
 a first electrode to be brought into contact with the first member;   a second electrode to be brought into contact with the second member;   an induction heating coil for performing induction heating of a portion where a joint target portion of the first member in contact with the first electrode and a joint target portion of the second member in contact with the second electrode have been contacted and joined to each other; and   a controller for controlling supply of electric current to the first electrode and the second electrode and supply of electric current to the induction heating coil;   wherein the induction heating coil is configured to be placed between the first electrode and the second electrode when the induction heating of a portion where the first member and the second member have been joined to each other is performed; and   wherein the controller is configured to pass an electric current between the first electrode brought in contact with the first member and the second electrode brought in contact with the second member, with simultaneous application of pressure to the joint target portion of the first member and the joint target portion of the second member, the joint target portions being in contact with each other, to weld the joint target portions, to temper a joint surface on a side of an opposite edge opposed to a first edge forming an outer circumference of the joint surface between the first member and the second member, with the induction heating coil being placed in a vicinity of the first edge, while maintaining the application of pressure to the joint surface, and then to temper the joint surface on a side of the first edge with an output from the induction heating coil reduced to a level lower than that used to temper the joint surface on the side of the opposite edge.   
     
     
         8 . The joined member manufacturing apparatus according to  claim 7 ,
 wherein the controller is configured to temper the joint surface on the side of the first edge forming an outer circumference of the joint surface, with an induction heating coil placed in a vicinity of the first edge, and to temper the joint surface on the side of the opposite edge opposed to the first edge, with an induction heating coil placed in a vicinity of the opposite edge, instead of being configured to temper the joint surface on the side of an opposite edge opposed to the first edge forming an outer circumference of the joint surface, with the induction heating coil being placed in the vicinity of the first edge, and then to temper the joint surface on the side of the first edge with an output from the induction heating coil reduced to a level lower than that used to temper the joint surface on the side of the opposite edge.   
     
     
         9 . A joined member manufacturing apparatus for manufacturing a joined member, the joined member being manufactured by joining a first member and a second member, the first member being made of a metal material having a possibility of undergoing quenching and formed to have a ring-like shape, the second member being made of a metal material and formed to have a circular cylindrical shape, the joined member manufacturing apparatus comprising:
 a first electrode to be brought into contact with the first member;   a second electrode to be brought into contact with the second member; and   induction heating coils for performing induction heating of a portion where a joint target portion of the first member in contact with the first electrode and a joint target portion of the second member in contact with the second electrode are contacted and joined to each other;   wherein the induction heating coils comprise a first induction heating coil wound into a circle with a diameter slightly larger than an outer diameter of the second member and a second induction heating coil wound into a circle with a diameter smaller than that of the first induction heating coil and placed below the first induction heating coil, the first induction heating coil and the second induction heating coil being configured to be placed between the first electrode and the second electrode when induction heating is performed on a portion where the first member and the second member are joined to each other.   
     
     
         10 . A method for manufacturing the joined member with the joined member manufacturing apparatus according to  claim 7 , the method comprising:
 a member placing step of placing the first member and the second member in the joined member manufacturing apparatus;   an electrode energizing step of passing an electric current between the first electrode and the second electrode; and   a coil energizing step of passing an electric current through the induction heating coil.   
     
     
         11 . The method for manufacturing a joined member according to  claim 5 ,
 wherein the welding step is a step of performing resistance welding of the joint target portions of the first member and the second member with simultaneous application of pressure; and   wherein the crack-inhibition step includes maintaining the application of pressure in the welding step.   
     
     
         12 . A method for manufacturing the joined member with the joined member manufacturing apparatus according to  claim 9 , the method comprising:
 a member placing step of placing the first member and the second member in the joined member manufacturing apparatus;   an electrode energizing step of passing an electric current between the first electrode and the second electrode; and   a coil energizing step of passing an electric current through the induction heating coil.