US-20260126080-A1 - Pin Bushing and Method of Manufacturing the Same

US20260126080A1US 20260126080 A1US20260126080 A1US 20260126080A1US-20260126080-A1

Abstract

The present disclosure provides a pin bushing and a method of manufacturing the same. The pin bushing comprises a first axial section, a second axial section and an intermediate section, the first axial section and the second axial section are located at both ends of the pin bushing in the axial direction, the intermediate section is disposed between the first axial section and the second axial section, the intermediate section has an intermediate radially outer portion and an intermediate radially inner portion, and hardness values of the first axial section, the second axial section and the intermediate radially outer portion are greater than that of the intermediate radially inner portion.

Inventors

Baojie AI
Pai Peng
Kun Yan
Guozhi XIAN

Assignees

CATERPILLAR INC.

Dates

Publication Date: 20260507
Application Date: 20230928
Priority Date: 20221012

Claims (15)

1 . A pin bushing, wherein the pin bushing comprises a through-hole running through the pin bushing in an axial direction of the pin bushing, a first axial section, a second axial section and an intermediate section disposed around the through-hole, the first axial section and the second axial section are located at both ends of the pin bushing in the axial direction, the intermediate section is disposed between the first axial section and the second axial section, the intermediate section has an intermediate radially outer portion and an intermediate radially inner portion in a radial direction of the pin bushing, the intermediate radially inner portion has a radially inward surface, the radially inward surface encloses a portion of the through-hole, wherein hardness values of the first axial section, the second axial section and the intermediate radially outer portion are greater than that of the intermediate radially inner portion.
2 . The pin bushing according to claim 1 , wherein the pin bushing is made of a carbon steel material.
3 . The pin bushing according to claim 1 , wherein a structure of the first axial section, the second axial section, and the intermediate radially outer portion is martensitic, and a structure of the intermediate radially inner portion is pearlite and ferrite.
4 . The pin bushing according to claim 1 , wherein a shape of the pin bushing satisfies at least one of the following: an outer surface of the pin bushing is cylindrical and an inner surface of the pin bushing is cylindrical.
5 . The pin bushing according to claim 4 , wherein a depth of each portion of the intermediate section satisfies at least one of: a depth of the intermediate radially outer portion is in a range of 40%-60% of an overall wall thickness of the pin bushing, and a depth of the intermediate radially inner portion is in a range of 60%-40% of the overall wall thickness of the pin bushing.
6 . The pin bushing according to claim 5 , wherein an axial length of the intermediate radially inner portion is in a range of 40%-60% of an overall axial length of the pin bushing.
7 . The pin bushing according to claim 6 , wherein the intermediate radially inner portion has rounded corners at both ends in the axial direction.
8 . The pin bushing according to claim 1 , wherein hardness values of portions of the first axial section in the radial direction are all greater than that of the intermediate radially inner portion, and hardness values of portions of the second axial section in the radial direction are all greater than that of the intermediate radially inner portion.
9 . The pin bushing according to claim 8 , wherein the hardness values of the first axial section, the second axial section and the intermediate radially outer portion are in a range of HRC55-HRC60, and the hardness value of the intermediate radially inner portion is less than or equal to HRC35.
10 . The method of manufacturing the pin bushing according to claim 1 , wherein the method comprises the following steps of: preliminarily forming the pin bushing; performing induction heating on the preliminarily-formed pin bushing, the step further comprising: moving an induction coil in the axial direction of the pin bushing; adjusting at least one of a feeding rate, an output power and an induction frequency of the induction coil depending on a relative position between the induction coil and the pin bushing such that the first axial section and the second axial section are heated entirely from outside to inside in the radial direction of the pin bushing, the intermediate radially outer portion is heated, and the intermediate radially inner portion is not heated or is heated to a lesser extent than the intermediate radially outer portion; and cooling and quenching the first axial section and second axial section and the intermediate radially outer portion.
11 . The method according to claim 10 , wherein the feeding rate of the induction coil at the first axial section and the second axial section is less than that of the induction coil at the intermediate section.
12 . The method according to claim 10 , wherein the output power of the induction coil at the first axial section and the second axial section is greater than that of the induction coil at the intermediate section.
13 . The method according to claim 10 , wherein the induction frequency of the induction coil at the first axial section and the second axial section is lower than that of the induction coil at the intermediate section.
14 . The method according to claim 11 , wherein the feeding rate of the induction coil at the intermediate section is 2-2.5 times that of the induction coil at the first axial section and the second axial section.
15 . The method according to claim 12 , wherein the output power of the induction coil at the first axial section and the second axial section is 1.1-1.5 times that of the induction coil at the intermediate section.

Description

FIELD The present disclosure relates to a track pin bushing for used in the field of construction machinery, and particularly to a pin bushing and a method of manufacturing the same. BACKGROUND Construction machineries such as excavators and bulldozers are usually provided with a track. A typical track design comprises a sprocket for driving the track, a pin and a pin bushing disposed around the pin, etc. An outer circumferential surface of the pin bushing is often subject to wear because the outer circumferential surface needs to engage the sprocket and both ends of the inner circumferential surface need to engage the pin. In order to increase the service life of the pin bushing, the pin bushing is typically heat-treated during its manufacture to increase its hardness and wear resistance. However, in conventional heat treatment processes, the steps are cumbersome, energy consumption is large, and the costs are high. Accordingly, it is desirable to provide a pin bushing and a method of manufacturing the same, to at least partially address the above problems. SUMMARY An object of the present disclosure is to provide a pin bushing and a method of manufacturing the same, which can simplify the operation steps and reduce the costs while ensuring the hardness of the pin bushing. According to an aspect of the present disclosure, there is provided a pin bushing, comprising a through-hole running through the pin bushing in an axial direction of the pin bushing, a first axial section, a second axial section and an intermediate section disposed around the through-hole. The first axial section and the second axial section are located at both ends of the pin bushing in the axial direction, and the intermediate section is disposed between the first axial section and the second axial section. The intermediate section has an intermediate radially outer portion and an intermediate radially inner portion in a radial direction of the pin bushing, wherein the intermediate radially inner portion has a radially inward surface, and the radially inward surface encloses a portion of the through-hole. Wherein hardness values of the first axial section, the second axial section and the intermediate radially outer portion are greater than that of the intermediate radially inner portion. According to another aspect of the present disclosure, there is provided a method of manufacturing the above-mentioned pin bushing, the manufacturing method comprising the following steps of: preliminarily forming the pin bushing;performing induction heating on the preliminarily-formed pin bushing, the step further comprising:moving an induction coil in the axial direction of the pin bushing;adjusting at least one of a feeding rate, an output power and an induction frequency of the induction coil depending on a relative position between the induction coil and the pin bushing such that the first axial section and the second axial section are heated entirely from outside to inside in the radial direction of the pin bushing, the intermediate radially outer portion is heated, and the intermediate radially inner portion is not heated or is heated to a lesser extent than the intermediate radially outer portion; andcooling and quenching the first axial section and second axial section and the intermediate radially outer portion. According to the above-mentioned solution, a high hardness of the intermediate radially outer portion and the entirety of both ends of the pin bushing, and a relatively low hardness of the intermediate radially inner portion of the pin bushing may be achieved by performing only one heating operation of the induction heating apparatus, so that both ends and the intermediate radially outer portion of the pin bushing may have a superior wear resistance, and the intermediate radially inner portion has a better impact resistance and fatigue life, enabling the pin bushing to be well adapted for application conditions of medium-sized excavators. In addition, the solution can simplify the operation steps, significantly reduce costs and save manpower and material resources. BRIEF DESCRIPTION OF THE DRAWINGS Reference may be made to preferred embodiments shown in the figures to enable better understanding of the above and other objects, features, advantages and functions of the present disclosure. The same reference numerals in the figures denote the same parts. Those skilled in the art should appreciate that the figures are intended to schematically illustrate the preferred embodiments of the present disclosure, and not intended to impose any limitations to the scope of the present disclosure. All parts in the figures are not drawn to scale. FIG. 1 shows a cross-sectional view of a pin bushing according to some preferred embodiments of the present disclosure. FIG. 2 shows a flow chart of a method of manufacturing a pin bushing according to some preferred embodiments of the present disclosure. DETAILED DESCRIPTION OF EMBODIMENTS Specific embod