Lubrication – Slide-bearing lubrication
Reexamination Certificate
2000-02-25
2002-04-02
Bucci, David A. (Department: 3682)
Lubrication
Slide-bearing lubrication
C074S089440, C074S424840
Reexamination Certificate
active
06364058
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a lubricant supply device for supplying lubricant to a screw shaft of a rolling-member screw apparatus such as a ball screw.
2. Description of the Related Art
A rolling-member screw apparatus such as a linear motion rolling guide apparatus and a ball screw apparatus is known as a linear motion apparatus in which a sliding member can move relative to a track shaft through rolling members such as balls that are disposed between them.
The linear motion rolling guide apparatus can guide a movable member such as a table on a stationary member such as a bed or a saddle. The linear motion rolling guide apparatus comprises a guide rail, a movable block and a plurality of balls. The guide rail is mounted on the stationary member and has ball running grooves formed thereon, which extend in the longitudinal direction of the guide rail so as to serve as rolling-member running surfaces. The movable block has ball circulation passages formed therein, which include loaded ball running grooves serving as loaded rolling-member running surfaces corresponding to the ball running grooves of the guide rail. The movable block is fitted to the guide rail so as to be capable of making a relative motion of the former to the latter. The balls are received in the ball circulation passages in the form of trains so as to serve as the rolling members that can be circulated along with the relative motion of the movable block to the guide rail. A linear motion of the movable block supporting the movable member can be made along the guide rail along with the endless circulation of the balls.
The applicant has proposed a lubricant supply device for lubricating the guide rail of the above-described linear motion rolling guide apparatus in Japanese Patent Application No. H9-305,861. The lubricant supply device comprises a casing, an application member, an absorbent body and an oil supply adjusting plate. The casing is mounted on a sliding member. The application member is received in the casing so as to come into contact with the guide rail to apply lubricant on the guide rail. The absorbent body is received together with the application member in the casing so as to supply the lubricant to the application member. The oil supply adjusting plate locates between the absorbent body and the application member so as to supply the absorbent body to the application member.
When the sliding member moves on the guide rail, the lubricant is applied from the application member to the guide rail. When an amount of lubricant absorbed by the application member is gradually decreased, the lubricant absorbed by the absorbent body is supplied through the oil supply adjusting plate to the application member by capillary action. Accordingly, a prescribed amount of lubricant is always absorbed by the application member, thus making it possible to stably supply a prescribed amount of lubricant to be applied on the guide rail from the application member.
The rolling-member screw apparatus such as a ball screw falls under the category of the linear motion apparatus, like the above-described linear motion rolling guide apparatus. However, the rolling-member screw apparatus has specific structures that the track shaft is formed into a screw shaft provided with a rolling-member running groove having a spiral shape, the sliding member is formed into a nut member, which engages with the screw shaft and has on its inner peripheral surface a rolling-member running groove having a spiral shape, corresponds to the rolling-member running groove of the screw shaft, and rolling members such as balls run in the spiral rolling-member running groove along with the relative rotation of the screw shaft to the nut member so that the relative linear motion of the nut member to the screw shaft can be made.
There has conventionally been a demand for development of the lubricant supply device, which is the most suitable for the rolling-member screw apparatus having the above-mentioned specific structures. However, such a lubricant supply device has not as yet been developed.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide a lubricant supply device, which is suitable for the rolling-member screw apparatus having the specific structures.
In order to attain the aforementioned object, a lubricant supply device of the present invention, which is to be fitted to a nut member engaging with a screw shaft through rolling members to supply lubricant to said screw shaft along with a relative rotational motion of said nut member to said screw shaft and comprises:
an application member for applying the lubricant on said screw shaft, said application member having at least one tongue portion, which is capable of coming into contact with at least one of rolling-member running surface of said screw shaft, a number of said at least one tongue portion being identical with or larger than a number of said rolling-member running surface;
a lubricant storage member for supplying the lubricant to said application member; and
a control device for controlling an amount of the lubricant supplied from said lubricant storage member to said application member.
According to the first device of the present invention described above, the relative rotation of the screw shaft to the nut member is made so that the lubricant is applied from the tongue portion of the application member on the surface of the rolling-member running surface of the screw shaft. The control device controls an amount of lubricant supplied from the lubricant storage member to the application member. Consequently, there is no serious change in an amount of lubricant supplied from the lubricant storage member to the application member even after a lapse of time so that a prescribed amount of lubricant can always be applied from the application member on the screw shaft. It is therefore possible to apply a minimum amount of lubricant on the screw shaft for a long period of time.
The tongue portion of the first device of the present invention, which is mounted on the nut member, can move along the spiral rolling-member-running surface along with the relative rotation of the nut member to the screw shaft. The number of the tongue portion is identical with or larger than the number of the rolling-member running surface. Accordingly, the spiral rolling-member running surface of the screw shaft can be lubricated over its entire length, irrespective of the number of the rolling-member running surface.
As the application member, there may be used material, which can smoothly apply the lubricant absorbed therein on the screw shaft, for example, oil absorbent material, which is formed of fiber-entangled body such as felt, or of sintered resin. The oil absorbent material preferably has a lower porosity than that of the other absorbent body described below, which serves as the lubricant storage member.
With respect to the lubricant storage member, any structural component, which can preserve in its inside a large amount of lubricant supplied to the application member, may suffice. As the lubricant storage member, there may be used for example either a tank having in its inside a storage chamber for receiving the lubricant, or oil absorbent material including fiber-entangled body such as felt, sintered resin or sponge by which the lubricant is actually absorbed. The oil absorbent material preferably has a higher porosity than that of the absorbent body described above, which serves as the application member.
With respect to the control device, any structural component, which can control an amount of lubricant supplied from the lubricant storage member to the application member, may suffice. As the control device, there may be used for example oil absorbent material, which is formed of fiber-entangled body such as felt, or of sintered resin. The oil absorbent material preferably has a porosity, which is middle between the high porosity of the oil absorbent material for the application member and the low porosi
Fujitsuna Mieko
Honma Mitsuaki
Nishide Tetsuhiro
Bucci David A.
Kim Chong H.
THK Co. Ltd.
Young & Thompson
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