Connecting rod and manufacturing method thereof

Patent metadata

Field	Value
Publication number	US-10161439-B2
Application number	US-201615564034-A
Country	US
Kind code	B2
Filing date	Mar 9, 2016
Priority date	Apr 16, 2015
Publication date	Dec 25, 2018
Grant date	Dec 25, 2018

Abstract

Provided is a connecting rod which can be manufactured without increasing the cost, and is provided with an effectively strengthened rod portion. The rod portion includes a pair of ribs (21) extending in parallel to each other in cross sectional view, and a web (22) connected between substantially vertically middle parts of the ribs. Each rib includes a rib root portion (23) located in a vertically central part thereof in cross sectional view, and a pair of rib tip portions (24) located at both vertical ends thereof, and each rib tip portion has a higher hardness than the web by 40 HV or more, and the rib root portion has a higher hardness than the web by 30 HV or more.

First claim

The invention claimed is:

1. A method of manufacturing a connecting rod made of metal and having a big end, a small end, and a rod portion connecting the big end to the small end and having a substantially H-shaped cross section, wherein the rod portion includes a pair of ribs extending in parallel to each other in cross sectional view, and a web connected between substantially vertically middle parts of the ribs, the method comprising;
a first step of hot forging steel material into an intermediate workpiece, and air cooling the intermediate workpiece; and
a second step of forging the intermediate workpiece by clamping the same between an upper die assembly and a lower die assembly to make a pair of rib tip portions located at both vertical ends of each rib in cross sectional view have a higher hardness than the web by 40 HV or more, and to make a rib root portion located at a vertically middle portion of each rib in cross sectional view have a higher hardness than the web by 30 HV or more.

2. The method of manufacturing a connecting rod according to claim 1 , wherein the intermediate workpiece is cold forged in the second step.

3. The method of manufacturing a connecting rod according to claim 2 , wherein in the second step, the intermediate workpiece is cold forged by using the upper die assembly and the lower die assembly which are configured such that a height of each rib of the connecting rod after forging is reduced compared to a height of each rib of the intermediate workpiece, a thickness of each rib of the connecting rod after forging is increased compared to a thickness of each rib of the intermediate workpiece, a spacing between the two ribs of the connecting rod after forging is increased compared to a spacing between the two ribs of the intermediate workpiece, and a width of the rod portion of the connecting rod after forging is increased compared to a width of the rod portion of the intermediate workpiece.

4. The method of manufacturing a connecting rod according to claim 3 , wherein in the second step, the lower die assembly provided with a pair of side walls projecting upward beyond vertically middle points of the respective ribs after forging is used so that the vertically middle portions of the ribs of the intermediate workpiece are restrained from outside by the lower die assembly when a forging load is applied, and the lower die assembly and the upper die assembly configured to create a gap between an inner surface of the lower die assembly and an outer surface of a lower part of each rib, and a gap between an inner surface of the upper die assembly and an outer surface of an upper part of each rib when the forging load is applied are used to cold forge the intermediate workpiece.

5. The method of manufacturing a connecting rod according to claim 2 , further comprising a third step of heating the connecting rod and then annealing the connecting rod by air cooling following the second step.

6. The method of manufacturing a connecting rod according to claim 3 , further comprising a third step of heating the connecting rod and then annealing the connecting rod by air cooling following the second step.

7. The method of manufacturing a connecting rod according to claim 4 , further comprising a third step of heating the connecting rod and then annealing the connecting rod by air cooling following the second step.

8. The method of manufacturing a connecting rod according to claim 1 , further comprising a third step of heating the connecting rod and then annealing the connecting rod by air cooling following the second step.

Assignees

• Honda Motor Co Ltd

Inventors

• Matsuda Hideki
• Iwasaki Yasuyuki
• Hayashi Hiroshi

Classifications

• F16J1/16

  with gudgeon-pin; Gudgeon-pins · CPC title

• F16C9/045

  the bearing cap of the connecting rod being split by fracturing · CPC title

• F16C2360/22

  Internal combustion engines · CPC title

• F16C7/023 Primary

  for piston engines, pumps or the like · CPC title

• B21D37/16

  Heating or cooling · CPC title