Patent Publication Number: US-2018045241-A1

Title: Sliding bearing manufacturing method and sliding bearing

Description:
TECHNICAL FIELD 
     The present invention relates to technology regarding a sliding bearing manufacturing method, and relates to technology regarding a method of manufacturing a sliding bearing in which half members, which are obtained by dividing a cylinder into two parts along a line parallel with the axial direction, are arranged in a vertical arrangement. 
     BACKGROUND ART 
     Conventionally, a sliding bearing having a halved structure, in which two members obtained by dividing a cylinder are arranged together, is known as a bearing for supporting the crank shaft of an engine, but there is a problem of high friction due to the high viscosity of oil when the temperature is low. In view of this, a bearing is known in which a clearance portion (groove) is formed over the entire circumference of each of the two axial end portions of the bearing (e.g., see Patent Document 1). 
     CITATION LIST 
     Patent Document 
     Patent Document 1: JP 2003-532036A 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, with the conventional bearing provided with grooves, it is not possible to achieve both an increase in the amount of oil drawn in and suppression of the amount of oil that leaks from the two axial end portions. An improved friction reduction effect cannot be expected. 
     In view of this, the present invention was achieved in light of the foregoing problem and provides a sliding bearing that can suppress the total amount of outflow oil and can obtain an improved friction reduction effect. 
     Solution to Problem 
     In light of the above-described problem to be solved by the present invention, the following describes a solution for this problem. 
     Specifically, according to an aspect of Claim  1 , there is provided a sliding bearing manufacturing method of the present invention is a method of manufacturing a sliding bearing in which half members are arranged in a vertical arrangement, the half members being obtained by dividing a cylinder into two parts along a line parallel with the axial direction and having a metal layer and a lining layer provided on an inner circumferential surface of the metal layer, the manufacturing method including: a first step of providing a groove in an axial end portion of the half member on a lower side, the groove extending in a circumferential direction on a downstream side in a rotation direction, wherein in the first step, a depth of the groove is set smaller than a result of subtracting a sum of a tolerance of a thickness of the lining layer and a tolerance of the depth of the groove from the thickness of the lining layer. 
     According to an aspect of Claim  2 , the manufacturing method includes a second step of providing a peripheral edge part in the axial end portion of the half member on the lower side, the peripheral edge part being located outward in an axial direction relative to the groove, wherein in the second step, an inner circumferential surface of the peripheral edge part is on an inner circumferential side relative to a bottom surface of the groove. 
     According to an aspect of Claim  3 , there is provided a sliding bearing manufactured by the above-described manufacturing method. 
     Advantageous Effects of Invention 
     The present invention achieves effects such as the following. 
     Specifically, the groove is provided so as to not impair the generation of oil film pressure, thus making it possible to obtain a friction reduction effect while also reducing the frictional area, and also making it possible to suppress the total amount of outflow oil. Also, the depth of the groove is set smaller than the result of subtracting the sum of the tolerance of the thickness of the lining layer and the tolerance of the depth of the groove from the thickness of the lining layer, and therefore when forming the groove using a cutter such as a circular saw, it is possible to prevent the cutter from coming into contact with the metal layer that is harder than the lining layer, thus extending the lifetime of the cutter. Also, by providing the groove in only the lining layer that has a hardness capable of being press-molded, it is possible to form the groove by press-molding. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a front view of a sliding bearing according to an embodiment of the present invention. 
         FIG. 2(A)  is a plan view of half members that constitute the sliding bearing according to the present invention.  FIG. 2(B)  is a cross-section value of the same taken along II(B)-II(B).  FIG. 2(C)  is a cross-sectional view of the same taken along II(C)-II(C). 
         FIG. 3  is a flowchart showing a half member manufacturing method according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Next, embodiments of the invention will be described. Note that  FIG. 1  is a front view of a sliding bearing  1 , upward and downward in the figure being considered to be the up-down direction, and the front direction and the back direction in the figure being considered to be the axial direction (front-rear direction). 
     First, half members  2  that constitute sliding bearing  1  according to the present invention will be described with reference to  FIGS. 1 and 2 . 
     Sliding bearing  1  is a cylindrical member, and is applied to a sliding bearing structure for crank shaft  11  of an engine as shown in  FIG. 1 . Sliding bearing  1  is constituted by two half members  2 . Two half members  2  are shaped as portions obtained by dividing a cylinder into two portions along a line parallel with the axial direction, and have a semicircular cross-section. In the present embodiment, half members  2  are arranged in a vertical direction, and the mating faces thereof are arranged in a horizontal arrangement. In the case where crank shaft  11  is supported by sliding bearing  1 , a predetermined gap is formed, and lubricating oil is supplied to this gap through an oil passage that is not illustrated. 
       FIG. 2(A)  shows the upper and lower half members  2 . Note that in the present embodiment, the rotation direction of crank shaft  11  is considered to be the clockwise direction in a front view as shown by the arrow in  FIG. 1 . Also, a bearing angle ω is defined so that it is 0 degrees at the position at the right end in  FIG. 2(B) , and bearing angle ω increase along the counter-clockwise direction in  FIG. 2(B) . In other words, in  FIG. 2(B) , the bearing angle ω is defined as 180 degrees at the position at the left end, and the bearing angle ω is defined as 270 degrees at the position at the lower end. 
     A groove extending in the circumferential direction is provided in the inner circumferential face of upper half member  2 , and a circular hole is provided in the center. Also, the mating face of upper half member  2  is arranged in the horizontal direction. As shown in  FIG. 2(C) , half member  2  has metal layer  21  and lining layer  22 . 
     Grooves  3  are formed in axial end portions of the inner circumferential face of lower half member  2 . 
     Also, peripheral edge part  2   a  that forms the outward surface, in the axial direction, of groove  3  is formed such that a height h from the outer circumferential surface of half member  2  is smaller than a height D from the outer circumferential surface of half member  2  to the abutting surface. In other words, peripheral edge part  2   a  on the outward side in the axial direction is formed so as to be lower than the abutting surface that abuts against crank shaft  11 . 
     Grooves  3  will be described below with reference to  FIGS. 2(B) and 2(C) . 
     Grooves  3  are provided in lower half member  2 . In the present embodiment, two grooves  3  are provided in parallel in the axial direction. Specifically, a groove  3  extends in the circumferential direction from a position (where bearing angle ω is ω 1 ) separated from the mating face on the downstream side in the rotation direction of crank shaft  11  (where bearing angle ω is 180 degrees), to a bearing angle ω 2  in the positive direction (counter-clockwise direction) of the bearing angle ω. In lower half member  2 , the mating face on the right side in  FIG. 2(B)  is the mating face on the upstream side in the rotation direction, and the mating face on the left side in  FIG. 2(B)  is the mating face on the downstream side in the rotation direction. 
     The width of groove  3  is denoted as w, as shown in  FIG. 2(C) . 
     Also, a depth d of groove  3  is smaller than the height D from the outer circumferential surface of half member  2  to the abutting surface. 
     Also, peripheral edge part  2   a  is higher than a bottom surface  3   a  of groove  3 , and therefore is a wall for preventing the re-leakage of oil that has leaked from the sliding face to the axial end portion or oil that has been sucked back in, thus making it possible to suppress the amount of leaked oil. Accordingly, the amount of oil drawn in at a low temperature in particular increases, and it is possible to improve a friction reduction effect due to a quick temperature rise. 
     Also, due to peripheral edge part  2   a  being lower than the surrounding abutting surface that abuts against crank shaft  11 , even if crank shaft  11  becomes inclined and is contact with only the end portion on one side in the axial direction (one-side contact state), it is possible to suppress opportunities for contact between peripheral edge part  2   a  and crank shaft  11 , thus making it possible to prevent damage to peripheral edge part  2   a.    
     By providing grooves  3  according to the present embodiment, the FMEP reduction amount increases. In particular, the FMEP reduction amount increases in the low engine rotation speed range. Here, FMEP refers to a value for examining the friction tendency, and when the FMEP reduction value increases, friction decreases. For example, when the engine is started at a low temperature for example, the FMEP reduction amount increases, and friction decreases. 
     Next, a method of manufacturing lower half member  2  of sliding bearing  1  will be described with reference to  FIG. 3 . 
     The method of manufacturing lower half member  2  includes a lining layer configuration step S 10  of providing lining layer  22  on metal layer  21 , a molding step S 20  of molding lining layer  22  and metal layer  21  into a semicircular shape, a groove configuration step S 30  that is a first step for forming groove  3 , a peripheral edge part configuration step S 40  that is a second step for forming peripheral edge part  2   a , and a coating layer configuration step S 50  of forming a coating layer (not shown in the figures) on the surface of lining layer  22 . These steps will be described in detail below. 
     In the lining layer configuration step S 10 , lining layer  22  is provided on metal layer  21 . More specifically, lining layer  22  is provided on metal layer  21  by performing rolling processing on metal layer  21  and lining layer  22 . Here, metal layer  21  is constituted by a material made of metal, for example is constituted by an iron-based material. Also, lining layer  22  is constituted by a material made of a metal having a lower hardness than metal layer  21 , for example is constituted by an aluminum-based material. 
     Next, in the molding step S 20 , metal layer  21  and lining layer  22  are molded into a semicircular shape. More specifically, metal layer  21  and lining layer  22  are molded into a semicircular shape by performing press molding. 
     Next, in the groove configuration step S 30 , groove  3  is formed. Then, in the peripheral edge part configuration step S 40 , peripheral edge part  2   a  is formed. 
     As a method of forming groove  3  and peripheral edge part  2   a  according to a first embodiment, the following describes a method of forming groove  3  and peripheral edge part  2   a  by cutting processing. 
     This cutting processing is performed by a cutter such as a circular saw. In the groove configuration step S 30 , groove  3  is formed to have a depth d that is less than the result of subtracting the sum of a tolerance a 1  of the thickness of lining layer  22  and a tolerance a 2  of the depth of groove  3  from a thickness h 1  of lining layer  22 . For example, letting h 1  be the thickness of lining layer  22 , a 1  be the tolerance of the thickness of lining layer  22 , d be the depth of the groove, and a 2  be the tolerance of the depth of groove  3 , the depth d of groove  3  is represented by d&lt;h 1 −(a 1 +a 2 ). 
     According to this configuration, the depth d of groove  3  is less than the thickness h 1  of lining layer  22 , and therefore when forming groove  3 , the cutter does not come into contact with metal layer  21 , thus making it possible to extend the lifetime of the cutter. 
     Also, in the peripheral edge part configuration step S 40 , an inner circumferential surface  2   c  of peripheral edge part  2   a  is formed on the inner circumferential side relative to the bottom surface  3   a  of groove  3 , and therefore peripheral edge part  2   a  is also formed inside lining layer  22 . Accordingly, the cutter does not come into contact with metal layer  21  when forming peripheral edge part  2   a , thus making it possible to extend the lifetime of the cutter. 
     As a method of forming groove  3  and peripheral edge part  2   a  according to a second embodiment, the following describes a method of forming groove  3  and peripheral edge part  2   a  by press processing. 
     Press processing is performed using a compression presser. In the groove configuration step S 30 , groove  3  is formed to have a depth d that is less than the result of subtracting the sum of the tolerance a 1  of the thickness of lining layer  22  and the tolerance a 2  of the depth of groove  3  from a thickness h 1  of lining layer  22 . 
     According to this configuration, the depth d of groove  3  is less than the thickness h 1  of lining layer  22 . If the depth d of groove  3  is larger than the thickness h 1  of lining layer  22 , groove  3  will need to be formed up to metal layer  21 , and the formation of groove  3  by press processing becomes difficult. If the depth d of groove  3  is set smaller than the thickness h 1  of lining layer  22 , groove  3  can be formed by press processing. 
     In the peripheral edge part configuration step S 40 , the inner circumferential surface  2   c  of peripheral edge part  2   a  is formed on the inner circumferential side relative to the bottom surface  3   a  of groove  3 , and therefore the inner circumferential surface  2   c  of peripheral edge part  2   a  is also formed inside lining layer  22 . Accordingly, peripheral edge part  2   a  can be formed by press processing. 
     Next, in the coating layer configuration step S 50 , a coating layer (not shown) is formed on the surface (inner circumferential surface) of lining layer  22 . This coating layer is constituted by a material made of a soft metal or a resin-based material. 
     As described above, a manufacturing method of the present invention is a method of manufacturing sliding bearing  1  in which half members  2  are arranged in a vertical arrangement, half members  2  being obtained by dividing a cylinder into two parts along a line parallel with the axial direction and having metal layer  21  and lining layer  22  provided on an inner circumferential surface of metal layer  21 , the manufacturing method comprising: a groove configuration step S 30  (first step) of providing a groove  3  in an axial end portion of half member  2  on a lower side, groove  3  extending in a circumferential direction on a downstream side in a rotation direction, wherein in the groove configuration step S 30 , a depth d of groove  3  is set smaller than a result of subtracting a sum of a tolerance a 1  of a thickness of lining layer  22  and a tolerance a 2  of the depth of groove  3  from the thickness h 1  of lining layer  22 . 
     According to this configuration, groove  3  is provided so as to not impair the generation of oil film pressure, thus making it possible to obtain a friction reduction effect while also reducing the frictional area, and also making it possible to suppress the total amount of outflow oil. Also, the depth d of groove  3  is set smaller than the result of subtracting the sum of the tolerance a 1  of a thickness of lining layer  22  and the tolerance a 2  of the depth of groove  3  from the thickness h 1  of lining layer  22 , and therefore when forming groove  3  using a cutter such as a circular saw, it is possible to prevent the cutter from coming into contact with metal layer  21  that is harder than lining layer  22 , thus extending the lifetime of the cutter. Also, by providing groove  3  in only lining layer  22  that has a hardness capable of being press-molded, it is possible to form groove  3  by press-molding. 
     The manufacturing method also has a peripheral edge part configuration step S 40  (second step) of providing a peripheral edge part in the axial end portion of half member  2  on the lower side, the peripheral edge part being located outward in an axial direction relative to groove  3 , wherein in the peripheral edge part configuration step S 40 , inner circumferential surface  2   c  of peripheral edge part  2   a  is on an inner circumferential side relative to bottom surface  3   a  of groove  3 . 
     According to this configuration, when forming the peripheral edge part  2  using a cutter such as a circular saw, it is possible to prevent the cutter from coming into contact with metal layer  21  that is harder than lining layer  22 , thus extending the lifetime of the cutter. Also, by providing peripheral edge part  2   a  in only lining layer  22  that has a hardness capable of being press-molded, it is possible to form the peripheral edge part  2  by press-molding. 
     INDUSTRIAL APPLICABILITY 
     The present invention is applicable to technology regarding a sliding bearing manufacturing method, and is applicable to technology regarding a method of manufacturing a sliding bearing in which half members, which are obtained by dividing a cylinder into two parts along a line parallel with the axial direction, are arranged in a vertical arrangement. 
     REFERENCE SIGNS LIST 
       1  Sliding bearing 
       2  Half member 
       2   a  Peripheral edge part 
       3  Groove 
       11  Crank shaft 
       21  Metal layer 
       22  Lining layer