Bearing member manufacturing method

Abstract

A bearing member manufacturing method manufactures a bearing member 20 formed of a light-metal-base material and capable of stably supporting a rotational shaft at a reduced manufacturing cost. The bearing member manufacturing method manufactures a bearing member 20 including a bearing body 21 formed of a first material, a light-metal-base material, and a bearing part 22 formed of a light-metal-base material different from that forming the body part 21, the bearing part 22 having a bearing surface 23 and bonded to the body part 21. A first workpiece 30 having a cylindrical inside surface 30 a serving as the bearing surface 23 is placed in a mold 50. The molten first material is poured into a cavity 56 surrounding the first workpiece 30 to cast a second workpiece 32. The first workpiece 30 and the second workpiece 32 are bonded metallurgically along the interface between the first work-piece 30 and the second workpiece 32 to form a primary workpiece 34 in the form of a semifinished workpiece 33. The semifinished workpiece 33 is divided into haves along a center plane P 2 including the center axis L 2 of the inside surface 30 a. Thus, two secondary workpieces 35 to be finished in the two bearing members 20 are obtained by cutting the single semifinished workpiece 33.

What is claimed is:  
     
         1 . A bearing member manufacturing method of manufacturing a bearing member having a body part formed of a first material of a light alloy, and a bearing part formed of a second material of a light-alloy-base material different from that forming the body part, said bearing part having a bearing surface of a semicircular cross section and integrally combined with the body part, said bearing member manufacturing method comprising: 
 a casting step of forming a primary workpiece having at least one semifinished workpiece including one first workpiece having a cylindrical inside surface serving as the bearing surface, and one second workpiece by integrally combining the first workpiece and the second workpiece in a mold by casting; and    a dividing step of dividing the primary workpiece removed from the mold into halves along a center plane including a center axis of the inside surface to obtain two secondary workpieces for forming two bearing members.    
     
     
         2 . The bearing member manufacturing method according to  claim 1  further comprising a first workpiece forming step for forming the cylindrical first workpiece of the second material, 
 wherein the casting step includes a casting step of placing at least one of the first workpiece formed by the first workpiece forming step in the mold, pouring the molten first material into the mold and metallurgically bonding together the first workpiece and the second workpiece along the interface between the first workpiece and the second workpiece.  
 
     
     
         3 . The bearing member manufacturing method according to  claim 2 , further comprising a step of providing a cavity for forming the second workpiece around the first workpiece in the mold and a step of pouring the molten first material into the cavity through parts of the mold corresponding to four corners of the semifinished workpiece having a substantially square shape as viewed along the center axis.  
     
     
         4 . The bearing member manufacturing method according to  claim 3 , wherein the molten first metal is poured into the cavity so as to flow in a swirling current in the cavity.  
     
     
         5 . The bearing member manufacturing method according to  claim 1 , wherein an aluminum alloy is used as the first material, and an aluminum alloy having a high silicon content is used as the second material.  
     
     
         6 . The bearing member manufacturing method according to  claim 1 , further comprising: 
 a casting step of forming a primary workpiece including a predetermined number of semifinished workpieces axially arranged such that at least second workpieces included in the semifinished workpieces are continuously arranged in a direction parallel to the center plane, and    a dividing step of dividing the primary workpiece along a plane perpendicular to the direction perpendicular to the center plane of the primary workpiece into the predetermined number of semifinished workpieces.    
     
     
         7 . The bearing member manufacturing method according to  claim 1 , further comprising: 
 a casting step of forming the primary workpiece including a predetermined number of semifinished workpieces arranged in a direction perpendicular to the center axis included in the center plane such that the second workpieces are continuously arranged in a direction perpendicular to the center axis in the center plane, and    a dividing step of dividing the primary workpiece along a plane perpendicular to the direction perpendicular to the center axis in the center plane into the predetermined number of semifinished workpieces.