Patent Application
20100206163
The present invention relates to a wear resistance reinforcing method and a sliding structure. The present application claims priority from Japanese Patent Application No. 2007-276396 filed in Japan on Oct. 24, 2007 and the disclosure of the contents of that application is incorporated herein by reference in its entirety.
Various types of aircraft actuators are provided on a single sliding structure. An aircraft actuator slides on a bearing in a cylindrical housing and includes a piston connected with a piston rod (drive shaft). An aircraft actuator is characterized in that aircraft fuel is often used to drive the actuator rather than using working oil having dedicated lubrication characteristics. Since the weight of an aircraft must be reduced as much as possible, an actuator is frequently driven using fuel oil which is always provided in the aircraft rather than providing dedicated driving lubrication oil to the aircraft. Consequently, since an aircraft actuator is driven using aircraft fuel which has inferior lubrication characteristics in comparison with lubrication oil, the actuator sliding face tends to wear in comparison to a general actuator driven using lubrication oil.
To resolve problems associated with the above type of wear resistance, the sliding surfaces of a conventional aircraft actuator are plated by using Cr plating or nonelectrolytic Ni plating, or a film of WC—Co (tungsten carbide-cobalt) is formed on the sliding surface by using high-speed flame spraying. Film-forming techniques have attempted to form hard thin films such as chromium nitrate (CrN) or diamond-like carbon (DLC) by using chemical vapor deposition (CVD) or physical vapor deposition (PVD).
Although the present applicants have conducted a survey of prior-art literature related to wear resistance properties of aircraft actuators, a suitable solution was not identified. Patent documents 1-3 below are provided as prior-art patent literature related to the wear resistance properties of mechanical components which differ from aircraft actuators.
However, since plating methods using Cr plating or nonelectrolytic Ni plating require finishing processing of the plated surface, workability is poor, costs are high and wear resistance properties are also inferior to the spraying. Since a method forming a WC—Co film by using high-speed flame spraying requires spraying WC—Co onto an inner peripheral surface of a housing and a finishing processing of the film surface, workability is poor and costs are high. A method of manufacturing a hard film by using CVD or the like does not enable a stable hard film surface and causes unevenness in wear resistance properties.
The present invention is proposed in light of the above problems and has the object of providing a wear resistance reinforcing method and a sliding structure having improved workability of the film in order to impart wear resistance properties, in addition to, having low unevenness in wear resistance properties.
The present invention adopts the configuration hereafter to achieve the above object.
In a first wear resistance reinforcing method according to the present invention, a wear resistance reinforcing method is provided for a sliding structure including at least a pair of components in sliding relation and having a seal member on a sliding surface of a first component. A wear-resistant metal-plated film formed from a metal having a fixed reactivity with the material of the seal member is provided on a sliding surface of a second component.
Furthermore, in a second wear resistance reinforcing method according to the present invention, the first wear resistance reinforcing method is such that the seal member is formed from a fluorine resin and the second component is formed from aluminum. A plated film formed from nonelectrolytic Ni—P—B (nickel-phosphorous-boron) is formed as an underlying plated film on the surface of the second component. A plated film formed from rhodium (Rh) is formed as a wear-resistant metal-plated film on the underlying plated film.
In a third wear resistance reinforcing method according to the present invention, the sliding structure according to the first or the second wear resistance reinforcing method is an actuator in which the second component is a hollow housing and the first component is a piston connected to a piston rod and sliding freely in the housing. The piston can be displaced by a pressure difference in working oil introduced into two spaces in the housing partitioned by the piston.
A first sliding structure according to the present invention includes at least a pair of components in a sliding relation and includes a seal member on a sliding face of the first component. A wear-resistant metal-plated film formed from a metal having a predetermined reactivity with the material forming the seal member is formed on a sliding surface of the second component.
A second sliding structure according to the present invention includes the first sliding structure in which the seal member is formed from a fluorine resin and the second component is formed from aluminum. A plated film formed from nonelectrolytic Ni—P—B (nickel-phosphorous-boron) is formed as an underlying plated film on the surface of the second component and a plated film formed from rhodium (Rh) is formed as a wear-resistant metal-plated film on the underlying plated film.
A third sliding structure according to the present invention includes the first or the second sliding structure in which the second component is a hollow housing and the first component is a piston connected to a piston rod and sliding freely in the housing. The piston can be displaced by a pressure difference in working oil introduced into two spaces in the housing partitioned by the piston.
According to the present invention, the material of the seal member and the wear-resistant metal-plated film formed from a metal having a predetermined reactivity are provided on a sliding surface of the second component. As a result, the present invention is different from a conventional film forming by using a WC—Co high-speed flame spray or forming a hard thin film such as DLC by using CVD or the like. Accordingly, workability of the film in relation to imparting wear resistance properties is improved and it is possible to reduce evenness in wear resistance properties.
An embodiment of the present invention is explained referring to the figures.
A disk-shaped piston 2 (component) and a bar-shaped piston rod 3 (drive shaft) in an aircraft actuator A are housed in an connected orientation in a hollow cylindrical housing 1 (component). Working oil is introduced from an outer section into two spaces K1, K2 in the housing 1 partitioned by the piston 2. The piston 2 and the piston rod 3 can be displaced to the left and the right of the page surface by a pressure difference in the working oil. The housing 1 is formed from an aluminum alloy and the piston 2 and piston rod 3 as a component integrally formed from stainless steel.
In the housing 1, a bearing 1a and a seal member 1b are provided on a sliding surface (cylindrical surface) with the piston rod 3. In the piston 2, a bearing 2a and a seal member 2b are provided on a sliding surface (cylindrical surface) with the housing 1. The bearings 1a, 2a support the piston 2 and the piston rod 3, and reduce frictional resistance and are formed from resin. The seal members 1b, 2b prevent leakage of working oil and are formed from fluoride resin.
The aircraft actuator A configured in the above manner uses aircraft fuel (fuel oil) as a working oil.
In this type of aircraft actuator A, the bearing 1a and the seal member 1b of the housing 1 slide on a sliding surface S1 (cylindrical peripheral face) of the piston rod 3. The bearing 2a and the seal member 2b of the piston 2 slide on a sliding surface S2 (inner cylindrical peripheral face) of the housing 1.
The nonelectrolytic Ni—P—B plated film 1e is a plated film for reinforcing the parent member 1c formed from an aluminum alloy. Furthermore, the Rh (rhodium) plated film 1f corresponds to a wear-resistant metal-plated film in the present embodiment and is a plated film formed from Rh (rhodium) selected as a metal which has a predetermined reactivity with the seal member (fluoride resin).
The zincate-treated film 1d is formed by a zincate process which removes an oxidized film or the like on the surface of the parent member 1c and is known in the technical field of plating processes.
An aircraft actuator A configured in the above manner enables displacement of the piston 2 by introducing the working oil from an external portion into a space formed between the housing 1 and the piston 2. As a result, the sliding surface S2 of the housing 1 on which a wear resistance reinforcing film is formed slides on the bearing 2a and the seal member 2b having working oil interposed therebetween.
However, since aircraft oil is used as the working oil in the aircraft actuator A, the lubrication properties on the sliding face are inferior in comparison to use of a dedicated lubrication oil as the working oil. The Rh (rhodium) plated film 1f is provided in the aircraft actuator A to improve wear resistance properties with respect to the seal member 2b.
Generally, when fluoride resin undergoes friction with a hard material such as a metal, a film-shaped transfer film having a band structure is formed on the complementary frictional surface. Since the transfer film has excellent lubrication properties, an effect of reducing the frictional coefficient is obtained. However, the transfer film tends to peel from the frictional surface and repetition of peeling and formation is thought to result in wear of the fluoride resin.
In the present embodiment, when the seal member 2b (fluoride resin) slides on the sliding surface S2 of the housing 1, since Rh (rhodium) has a predetermined reactivity with fluoride (F), a fluoride compound (peeling-resistant transfer film) is formed on the surface of the Rh (rhodium) plated film 1f and thereby enables wear resistance properties with respect to the seal member 2b.
Experimental results related to wear resistance properties of the Rh (rhodium) plated film 1f of the aircraft actuator A is explained in detail hereafter.
In the test device, the liner plate L1 is fixed to the bottom of a slide tray T so that the laminated film F is the upper surface and the seal block piece L2 is disposed so that the seal member N abuts with a predetermined load on the liner plate L1. A test oil U equivalent to the aircraft fuel (working oil) is used to fill the sliding tray T. The liner plate L1 and the seal block piece L2 undergo sliding by reciprocating the slide tray T in a horizontal direction by a motor M. In the test device, all equipment except for the drive equipment including the motor M are stored in a chamber C. As shown in the figure, a nitrogen gas (N2 gas) atmosphere is created in the chamber C.
The present invention is not limited to the above embodiments and, for example, may include modified examples as described below.
(1) In the above embodiment, the present invention is applied to an aircraft actuator A. However, the present invention may be applied to respective sliding structures other than an aircraft actuator A.
(2) In the above embodiment, a nonelectrolytic Ni—P—B plated film le is adopted as a reinforcing metal film and an Rh plated film 1f is adopted as a wear-resistant metal-plated film. However, the present invention is not limited thereby. A film or surface processing other than Ni—P—B may be used as the reinforcing metal film as long as it has sufficient strength to reinforce a thin member and has a high adhesion to the parent member and the wear-resistant metal-plated film. A metal other than Rh (rhodium) may be used as the wear-resistant metal-plated film as long as it is formed from a metal having a predetermined reactivity with the seal member 2b.
According to the present invention, an wear-resistant metal-plated film formed from a metal having a predetermined reactivity with a material for a seal member are provided on a sliding surface of a second component. The present invention is different from a conventional film forming by using CVD or the like to form a hard thin film such as DLC or by using a WC—Co high-speed flame spray. As a result, the workability of the film in relation to imparting wear resistance is improved and it is possible to reduce unevenness in the wear resistance properties.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-276396 | Oct 2007 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2008/069123 | 10/22/2008 | WO | 00 | 4/20/2010 |
