DE-102018204636-B4 - Chain

DE102018204636B4DE 102018204636 B4DE102018204636 B4DE 102018204636B4DE-102018204636-B4

Abstract

chain comprising several pairs of outer links, each connected by two pins, and several pairs of inner links, each connected by two sockets alternately connected to each other, the pins being loosely fitted in the sockets, at least one of the pin, bushing, inner link and outer link is a chain component of a power transmission chain for industrial use, wherein the chain component comprises the following: a steel base material; and a chromium nitride layer formed on an outer side of the steel base material and containing iron in a wt.% of 1 or more and 45 or less, wherein the chromium nitride layer of the chain component has an iron concentration distribution that gradually decreases from a surface of the steel base material outwards, and wherein the chromium nitride layer of the chain component has a chromium and nitrogen concentration distribution that gradually decreases from an outer side to a surface of the steel base material.

Inventors

Misa Asada
Takashi Kawata
Tomoaki Nakayasu
Kota Yoshimoto
Nobuhiro Uchida
Masanori Yokoyama

Assignees

TSUBAKIMOTO CHAIN CO.

Dates

Publication Date: 20260513
Application Date: 20180327
Priority Date: 20170328

Claims (7)

A chain comprising several pairs of outer links, each connected by two pins, and several pairs of inner links, each connected by two bushings alternately connected to one another, the pins being loosely fitted in the bushings, at least one of the pin, bushing, inner link, and outer link being a chain component of a power transmission chain for industrial use, the chain component comprising: a steel base material; and a chromium nitride layer formed on an outer side of the steel base material, containing iron in a wt.% of 1 or more and 45 or less, the chromium nitride layer of the chain component having an iron concentration distribution that gradually decreases from a surface of the steel base material outwards, and the chromium nitride layer of the chain component having a chromium and nitrogen concentration distribution that gradually decreases from an outer side to a surface of the steel base material.
chain after Claim 1 , wherein the chromium nitride layer of the chain component contains: 45 wt.% or more and 90 wt.% or less chromium, and 5 wt.% or more and 25 wt.% or less nitrogen, based on a total of 100 wt.%.
Chain after one of the Claims 1 until 2 , wherein the chromium nitride layer of the chain component has a thickness of 2 µm or more and 30 µm or less.
Chain comprising several pairs of outer plates, each connected by two pins, and several pairs of inner plates, each connected by two bushings, each bushing having a roller mounted thereon, which are alternately connected to one another, the pins being loosely fitted in the bushings, at least one of the pin, bushing, inner plate, outer plate and roller being a chain component of a power transmission chain for industrial use, the chain component comprising: a steel base material; and a chromium nitride layer formed on an outer side of the steel base material and containing iron in a wt.% of 1 or more and 45 or less, whereby the chromium nitride layer of the chain component has an iron concentration distribution that gradually decreases from a surface of the steel base material outwards, and whereby the chromium nitride layer of the chain component has a chromium and nitrogen concentration distribution that gradually decreases from an outer side to a surface of the steel base material.
Chain after one of the Claims 1 until 4 , wherein at least one of the pin and bushing is a chain component of a power transmission chain for industrial use, the chain component comprising: a steel base material; and a chromium nitride layer formed on an outer side of the steel base material and containing iron in a wt.% of 1 or more and 45 or less; and a gap between the pin and bushing of 30 µm to 120 µm.
Chain comprising: several inner plates, each having a pair of V-shaped toothed plates at one end in a direction of the short side, and a pair of front and rear pin openings, the inner plates being pivotably connected to one another by pins inserted into the pin openings and arranged in a width direction of the chain such that one toothed plate of each inner plate overlaps the other toothed plate of another adjacent inner plate; and guide plates arranged on both outer sides in the width direction, through which the pins are firmly inserted, at least one of which, the pin, the inner plate and the guide plate, is a chain component of a power transmission chain for industrial use, the chain component comprising: a steel base material; and a chromium nitride layer formed on an outer side of the steel base material and containing iron in a wt.% of 1 or more and 45 or less, wherein the chromium nitride layer of the chain component has an iron concentration distribution that gradually decreases from a surface of the steel base material outwards, and wherein the chromium nitride layer of the chain component has a chromium and nitrogen concentration distribution that gradually decreases from an outer side to a surface of the steel base material.
chain after Claim 6 , wherein at least one of the pin and the inner link is a chain component of a power transmission chain for industrial use, the chain component comprising: a steel base material; and a chromium nitride layer formed on an outer side of the steel base material and containing iron in a wt.% of 1 or more and 45 or less; and a gap between the pins and the pin openings in the inner links in sliding contact with the pins of 30 µm to 120 µm.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention The present invention relates to a chain comprising chain components. These chain components are chain parts such as pins, bushings, chain links, and rollers, which constitute power transmission chains for industrial use, such as roller chains and toothed chains, which are used, for example, as automotive timing chains. 2. State of the art It is known that a chromium nitride layer formed on a metal surface improves the metal's wear and corrosion resistance. The deposition of chromium nitride layers is therefore widely used in practice to extend the service life of machine parts, metal molds, tools, and the like. Chromium nitride layers are generally formed by physical vapor deposition (PVD) processes, such as ion plating or sputtering. In the former, nitrogen gas is introduced into a vacuum chamber while a base material is bombarded with vaporized and ionized chromium. In the latter, a high voltage is applied between a target and a substrate to generate a glow discharge, causing argon ions from the plasma to collide with the target surface and eject chromium atoms, which are then deposited onto the substrate. One problem with chromium nitride coatings formed by a PVD process was that, when used as a surface treatment coating for highly stressed sliding components of a chain, the coating would easily peel off the metal base material, such as steel, and it was difficult to make the coating adhere to the surface of the base material and bond with it in such a way that it would hardly peel off. PVD also results in the occasional formation of droplets on the surface. When droplets are present, surface roughness increases, and cracks begin to form from the droplets, reducing wear resistance. Although droplets can be removed by polishing, openings remain where the droplets were. When a load is applied, these openings enlarge and merge, preventing any improvement in wear resistance. Due to the cracks and deterioration of wear resistance that occur in PVD processes, the layer thickness could not be increased to extend the service life. Another problem was that if the material being processed was porous, it was difficult to form a layer on the inner surfaces of the pores. An example of the machine parts mentioned above are pins used in the timing chains of vehicle engines. Examples of timing chains include roller chains, bushing chains, toothed chains, and the like. A roller chain has rollers attached to cylindrical bushings, which are pressed at both ends into bushing openings of a pair of inner plates, whereas pins fitting into the bushings are pressed at both ends into pin openings of a pair of outer plates located on both outer sides of the pair of inner plates. Bushing chains do not have rollers. In conventional timing chains, the steel base material of the pins would undergo a chrome plating treatment to improve the wear resistance of the bushings and pins. However, timing chains used with a lot of old engine oil inside the vehicle's engine compartment were prone to wear on pins and bushings, which is why their lifespan tended to be short. Furthermore, soot produced during the engine's combustion process, which mixed with the engine oil, posed a risk of increasing the coefficient of friction of the pins and bushings or accelerating wear despite the coating, as lubricating oil containing soot could penetrate between components such as pins and bushings of the timing chain, which runs at high speed under high load, and the soot, being a hard substance, could damage the coating between the pins and bushings. Accordingly, a surface treatment was desired that would improve the wear resistance of chains. The Japanese patent application with the publication number JP H11 - 29 848 A Disclosures a method for forming chromium nitride layers as a solution to the problems associated with the deposition of chromium nitride layers on metal surfaces, namely layer separation due to temperature stress over time (heat history) and poor adhesion to the base material. After chromium plating of the surface of a metal material, the chromium-plated surface is cleaned and activated by heating the metal material in a reactive gas containing halogen compounds or halogens, prior to nitriding the chromium-plated surface by applying heat in a nitriding atmosphere. DE 20 2006 020 978 U1 , DE 10 2012 016 027 A1 , WO 2014/ 019 699 A1 , DE 10 2013 222 244 A1 , DE 10 2004 012 463 A1 , DE 602 13 779 T2 , DE 698 38 575 T2 , US 2012 / 0 325 673 A1 and WO 2012/151 603 A1 represent further relevant prior art for the present application. SUMMARY OF THE INVENTION The process of forming chromium nitride layers according to the Japanese patent application with publication no. JP H11 - 29 848 A This involves a very complex process in which industrial chromium plating is carried out on a base material such as steel, followed by a special chromium coating such as a highly corrosion-resistant, crack-free