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US-12623284-B2 - Manufacture method of bushing, bushing and excavator

US12623284B2US 12623284 B2US12623284 B2US 12623284B2US-12623284-B2

Abstract

This disclosure relates to a manufacture method of a bushing, a bushing and an excavator to alleviate the problems of insufficient lubricity and wear resistance of the bushing. The bushing includes an inner ring and an outer ring. The manufacture method of the bushing includes the following steps: grinding a first mixed powder containing Fe, Al, Ti, Cr and V, nitriding the ground first mixed powder to form a nitrogen-rich stable compound powder, and then carrying out molding by pressing and sintering the nitrogen-rich stable compound powder to form the outer ring; grinding a second mixed powder containing Fe and Mo, sulfurizing the ground second mixed powder to form a sulfurized powder containing FeS and MoS 2 , and carrying out molding by pressing the sulfurized powder to form the inner ring; and placing the inner ring in the outer ring and carrying out sintering to obtain the bushing.

Inventors

  • Guo Xu
  • Bo Chen
  • Kun Feng

Assignees

  • JIANGSU XCMG CONSTRUCTION MACHINERY RESEARCH INSTITUTE LTD.

Dates

Publication Date
20260512
Application Date
20211214
Priority Date
20211111

Claims (14)

  1. 1 . A method of manufacturing a bushing, the bushing comprising an inner ring and an outer ring, the method comprising: grinding a first mixed powder containing Fe, Al, Ti, Cr and V; nitriding the ground first mixed powder to form a nitride-containing powder, and molding the nitride-containing powder by pressing the nitride-containing powder and sintering the pressed nitride-containing powder to form the outer ring; grinding a second mixed powder containing Fe and Mo; sulfurizing the ground second mixed powder to form a sulfurized powder containing FeS and MoS 2 ; and molding the sulfurized powder by pressing the sulfurized powder to form the inner ring; placing the inner ring in the outer ring; and sintering the inner ring and the outer ring to obtain the bushing.
  2. 2 . The method according to claim 1 , wherein the first mixed powder containing Fe, Al, Ti, Cr and V comprises the following components in percentage by mass: 82% to 93% of Fe, 5.0% to 10.0% of Cr, 0.8% to 3.0% of Al, 1.0% to 3.0% of Ti, and 0.2% to 2.0% of V.
  3. 3 . The method according to claim 1 , wherein the second mixed powder containing Fe and Mo comprises the following components in percentage by mass: 85% to 97% of Fe and 3% to 15% of Mo.
  4. 4 . The method according to claim 1 , wherein the first mixed powder containing Fe, Al, Ti, Cr and V is ground for 1 h to 4 h.
  5. 5 . The method according to claim 1 , wherein the step of nitriding the ground first mixed powder comprises: nitriding the ground first mixed powder in an atmosphere of flowing NH 3 at 400° C. to 700° C. for 1 h to 4 h.
  6. 6 . The method according to claim 1 , wherein the step of molding the nitride-containing powder comprises: putting the nitride-containing powder into a bushing mold, and pressing and molding the nitride-containing powder with a pressure of 650 MPa to 800 MPa.
  7. 7 . The method according to claim 1 , wherein the second mixed powder containing Fe and Mo is ground for 1 h to 4 h.
  8. 8 . The method according to claim 1 , wherein the step of sulfurizing the ground second mixed powder comprises sulfurizing the ground second mixed powder in a sealed tank containing H 2 S gas at 540° C. to 600° C. for 1 h to 3 h.
  9. 9 . The method according to claim 1 , wherein the step of molding the sulfurized powder comprises: putting the sulfurized powder into the bushing mold, and pressing and molding the sulfurized powder with a pressure of 700 MPa to 850 MPa.
  10. 10 . The method according to claim 1 , wherein the step of placing the inner ring in the outer ring and sintering the inner ring and the outer ring to obtain the bushing comprises assembling the inner ring and the outer ring and then carrying out the sintering in a furnace capable of heating to a temperature range of the sintering with a protective atmosphere of an inert gas at 1210° C. to 1260° C. for 1 h to 3 h.
  11. 11 . The method according to claim 1 , wherein prior to the step of molding the nitride-containing powder, the method further comprises adding a third mixed powder containing Fe and Cu to the nitride-containing powder, mixing the third mixed powder and the nitride-containing powder, and ball milling the mixture including the third mixed powder for 4 h to 6 h.
  12. 12 . The method according to claim 11 , wherein the third mixed powder containing Fe and Cu comprises the following components in percentage by mass: 90% to 95% of Fe and 5% to 10% of Cu.
  13. 13 . The method according to claim 1 , further comprising carrying out vacuum oil impregnating on the sintered bushing.
  14. 14 . The method according to claim 13 , wherein the step of vacuum oil impregnating on the sintered bushing comprises cleaning the sintered bushing, placing the cleaned bushing in a vacuum chamber, sealing and vacuuming the vacuum chamber to −750 mmHg to −650 mmHg, feeding lubricating oil into the vacuum chamber, heating up the vacuum chamber to 80° C. to 90° C., and holding the temperature for 30 min to 50 min.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a U.S. National Stage Application under 35 U.S.C. § 371 of International Patent Application No. PCT/CN2021/137789, filed on Dec. 14, 2021, which is based on and claims priority to CN application No. 202111332774.0, filed on Nov. 11, 2021, the disclosures of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD This disclosure relates to the field of engineering machinery, and in particular, to a manufacture method of a bushing, a bushing and an excavator. BACKGROUND Working devices of an excavator can achieve different actions and transmit loads through multiple hinge pairs. Pins for hinged parts mainly employ steel bushings, copper bushings and powder metallurgy oil-impregnated bushings. Insufficient lubricity and wear resistance of the bushing at a hinge point will lead to problems such as excessive wear, frequent greasing, seizing lock, excessive temperature, and abnormal noise. For some steel bushings, a machined oil storage tank, such as a splay-section, cross-section, or honeycomb oil storage tank, is adopted and then a heat treatment process such as induction quenching or carburizing and quenching is carried out. There are still some steel bushings sprayed with graphite and MoS2 as an anti-friction layer so that their wear resistance and lubricity meet the requirements. The steel bushing has defects such as low material utilization rate and complex manufacturing process. When coupled with the pin, the steel bushing is prone to locking and material transfer. Frequent greasing is required to maintain boundary lubrication conditions. The sprayed anti-friction layer is generally only a few microns thin and it only has a certain effect in the early stage of running-in without improving the lubricity. The copper bushing is made of cast brass as the base, and holes with orderly distribution and appropriate size are formed in the base, and then solid lubricants such as graphite and PTFE are embedded in the holes. The copper bushing has the dual advantages of copper alloy and solid lubricant. It can be applied under a condition of poor lubricity or a condition not suitable for greasing. The copper bushing has high material cost and low production efficiency. The processing of graphite holes damages the mechanical strength of the copper base, which causes poor impact resistance and load-bearing performance. The solid lubricant has blind distribution spots and is easy to fall off, thus reducing self-lubricating property. Powder metallurgy oil-impregnated bushings are bushings made of porous materials and store lubricating oil in pores. When the powder metallurgy oil-impregnated bushing is loaded and reaches a certain speed, the power of the oil film formed by the lubricating oil seeping out of the pores can support the load of the shaft diameter, thus avoiding the direct contact between the pin and the bushing. Although powder metallurgy oil-impregnated bushings have the advantages of energy saving, high material utilization, high product precision and stable performance, they have the disadvantages of low hardness and insufficient wear resistance and can hardly meet the harsh working conditions of engineering machinery only by lubricating oil stored in the gaps of the bushings. SUMMARY According to an aspect of this disclosure, provided is a manufacture method of a bushing, the bushing including an inner ring and an outer ring, the manufacture method of the bushing including the following steps: grinding a first mixed powder containing Fe, Al, Ti, Cr and V, nitriding the ground first mixed powder to form a nitrogen-rich stable compound powder, and then carrying out molding by pressing and sintering the nitrogen-rich stable compound powder to form the outer ring;grinding a second mixed powder containing Fe and Mo, sulfurizing the ground second mixed powder to form a sulfurized powder containing FeS and MoS2, and carrying out molding by pressing the sulfurized powder to form the inner ring; andplacing the inner ring in the outer ring and carrying out sintering to obtain the bushing. In some embodiments, the first mixed powder containing Fe, Al, Ti, Cr and V includes the following components in percentage by mass: 82% to 93% of Fe, 5.0% to 10.0% of Cr, 0.8% to 3.0% of Al, 1.0% to 3.0% of Ti, and 0.2% to 2.0% of V. In some embodiments, the second mixed powder containing Fe and Mo includes the following components in percentage by mass: 85% to 97% of Fe and 3% to 15% of Mo. In some embodiments, the first mixed powder containing Fe, Al, Ti, Cr and V is ground for 1 h to 4 h. In some embodiments, the step of nitriding the ground first mixed powder includes: nitriding the ground first mixed powder in an atmosphere of flowing NH3 at 400° C. to 700° C. for 1 h to 4 h. In some embodiments, prior to the step of molding by pressing and sintering the nitrogen-rich stable compound powder, the method further includes a step of: adding a third