Joining joint to be joined to resin, method for manufacturing joining joint, and joining structure between metal and resin

Abstract

Provided is a joining structure between metal and resin which has improved junction strength. A joining joint has a hand-drum shape having a constricted portion constricted between both of the bottom surfaces by forming a groove-shaped recess in a circumferential direction of a substantially cylindrical side surface made of metal. Upper and lower end portions of the side surface and the recess form a rough concavo-convex shape, and the side surface including the recess becomes a junction surface. On the junction surface, a fine concavo-convex shape with arithmetic average roughness Ra of 10 to 300 μm is formed. By forming the rough concavo-convex shape and the fine concavo-convex shape on the junction surface, the joining joint makes strong joining to resin.

1 . A joining joint made of metal, having a junction surface to be joined to resin on a surface, and having a fine concavo-convex shape formed on the junction surface, where arithmetic average roughness Ra of the fine concavo-convex shape is 10 to 300 μm. 
     
     
         2 . The joining joint according to  claim 1 , wherein a groove-shaped recess is formed on the junction surface. 
     
     
         3 . The joining joint according to  claim 2 , wherein the junction surface has a substantially cylindrical shape serving as a side surface, and the recess is formed in a circumferential direction of the side surface. 
     
     
         4 . The joining joint according to  claim 3 , wherein a cross section in a radial direction of a constricted portion formed of the recess in the circumferential direction is substantially polygonal. 
     
     
         5 . A method for manufacturing the joining joint according to  claim 1 , wherein
 a fine concavo-convex shape is formed on a surface of a casting mold for casting the joining joint by forming the casting mold of coarse aggregate, and   a fine concavo-convex shape is formed on a surface of the joining joint casted from the casting mold.   
     
     
         6 . The method for manufacturing the joining joint according to  claim 5 , wherein an average grain size (median diameter d50) of the aggregate is 200 to 2000 μm. 
     
     
         7 . A joining structure between metal and resin, comprising:
 the joining joint according to  claim 1 ; and   a resin bracket that covers the junction surface of the joining joint, and is formed of resin for fixing the joining joint as a matrix.