Lubrication – Slide-bearing lubrication
Reexamination Certificate
2002-05-14
2004-03-16
Kim, Chong H. (Department: 3682)
Lubrication
Slide-bearing lubrication
Reexamination Certificate
active
06705430
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a guide unit in which a track shaft and a sliding member are engaged with each other such that they are capable of relatively reciprocating via rolling bodies such as balls or rollers of ball bearing, ball bushing, ball screw, ball spline, roller bearing or the like for linear sliding and curved sliding, and more particularly to a dust preventing structure of a guide unit for removing foreign matter adhering to the surface of the track shaft and applying lubricating performance between the track shaft and sliding member.
This kind of the guide units are used in various fields requiring a linear motion, rotary motion, a curved motion and the like and their use conditions are diversified. For example, a guide unit of linear sliding type ball bearing for use in semiconductor manufacturing apparatus is used under a very clean environment, a guide unit of machine tool is used under an environment in which coolant is used and further, a guide unit of timber processing unit is used under a condition in which dust, dirt, wooden pieces, cutting powder and the like falls thereon.
In such a guide unit, if foreign matter such as coolant and dust invades into a gap between the track shaft and sliding member, the coolant repels lubricant or foreign matter absorbs lubricant, so that lubricity between the track shaft and sliding member drops considerably. As a result, rolling bodies such as balls or rollers bearing a load between the track shaft and sliding member or the track shaft in which the rolling bodies roll and the rolling groove in the sliding member side are worn abnormally thereby the service life of the unit dropping remarkably.
Thus, in a conventional linear sliding motion ball bearing comprising a track rail (track shaft) in which a ball rolling groove is formed in the length direction thereof and a sliding base (sliding member) in which a ball infinite circulation path constituted of a load rolling groove opposing the ball rolling groove in the aforementioned track rail via a plurality of balls, a direction changing path disposed at beginning and terminal ends of the load rolling groove and a ball return path connecting these direction changing paths is formed, sealing members made of rubber or the like are attached to both ends in the traveling direction of the sliding base so that they are in firm contact with the track rail, thereby removing coolant, dust and the like adhering to the surface of the track rail in the accordance the movement of the sliding base to prevent them from invading into the interior of the sliding base.
In case where, in this kind of the guide unit, foreign matter such as welding spatter or the like adheres to the track rail, if the aforementioned sealing member makes contact with the spatter, it may be caught thereby and damaged. To avoid such an inconvenience, according to another known structure of the guide unit, a scraper member made of metal or the like is attached outside of the sealing member of the sliding base with a slight gap with respect to the track rail, so that the foreign matter such as welding spatter adhering to the track rail is scraped out by this scraper member before the sealing member comes into contact with the spatter.
Because this kind of the sealing member keeps a firm contact with the track shaft (track rail in the previous example), lubricant such as lubricating oil and grease supplied inside the sliding member (sliding base in the previous example) and adhering to the surface of the track shaft is wiped off by a sealing member at the rear side of the sliding member in the advancement direction so as to prevent the lubricant from leaking out of the sliding member (lubricant leakage preventing function).
This lubricant leakage preventing function of this sealing member exerts an effect of using lubricant supplied inside the sliding member effectively. If an attention is paid to a sealing member located at the front side in the advancement direction when the sliding member reciprocates, it comes that this sealing member moves with a firm contact with the surface of the track shaft after lubricant is wiped off, so that friction resistance increases as compared to the sealing member located at the rear side in the advancement direction. As a result, a smooth reciprocation of the sliding member is prevented and if a reciprocating stroke is extremely long, the sealing member located at the front side in the advancement direction may be damaged by a friction caused between the sealing member and the track shaft or the service life of the sealing member may be shortened extremely.
This problem occurs like a case in which a scraper member made of metal, plastics or the like is used with the sealing member. Although the scraper member is capable of removing a large foreign matter such as spatter, because it cannot be mounted in a firm contact with the surface of the track shaft, it is not capable of removing small dust or dirt and when the sliding member reciprocates, the sealing member located at the front side in the advancement direction comes into contact with the small dust or dirt, so that friction resistance increases thereby the service life being reduced.
If the guide unit is used under a condition in which use of coolant is required or under an environment in which dust, dirt, wooden pieces, cutting powder or the like falls, this problem is very conceivable because after the sealing member wipes off, a slight amount of lubricant remaining on the surface of the track shaft is washed off by those foreign matters or absorbed. This problem needs to be solved to accelerate maintenance free about lubricant in a guide unit for use under such a severe condition.
OBJECT AND SUMMARY OF THE INVENTION
Accordingly, the inventor of the present invention considered a solution of this problem earnestly. As a result, the inventor of the present invention has completed a dust preventing structure of a guide unit capable of achieving a smooth reciprocation with less friction resistance of the sliding member with respect to the track shaft, preventing foreign matter from invading inside of the sliding member even if use of the sealing member is omitted if it is not used under a severe environment and further maintaining a smooth reciprocation of the sliding member with respect to the track shaft in a long period even under a severe condition in which use of coolant is required or dust, dirt, wooden pieces, cutting powder or the like falls on the guide unit, by using the sealing member at the same time.
Therefore, an object of the present invention is to provide a dust preventing structure of a guide unit capable of achieving a smooth reciprocation of the sliding member with respect to the track shaft with less friction resistance.
Further, another object of the present invention is to provide a dust preventing structure of a guide unit capable of maintaining a smooth reciprocation of the sliding member with respect to the track shaft in a long period even under a severe condition in which use of coolant is required or dust, dirt, wooden pieces, cutting powder or the like falls on the guide unit.
To achieve the above object, according to an aspect of the invention, there is provided a dust preventing structure of a guide unit comprising a track shaft and a sliding member engaging the track shaft via a plurality of rolling bodies so that it is capable of reciprocating in a length direction thereof, wherein elastic members in firm contact with the track shaft are overlaid in the length direction of the track shaft.
Further, according to another aspect of the invention, there is provided a dust preventing structure of a guide unit comprising a track shaft and a sliding member engaging the track shaft via a plurality of rolling bodies so that it is capable of reciprocating in a length direction thereof, the dust preventing structure further comprising a lubricant pocket forming member having a concave groove portion made of elastic material for forming a lubricant pocket filled with lu
Honma Mitsuaki
Katsumata Yasuhide
Michioka Hidekazu
Saitou Yoshiaki
Arent Fox Kintner & Plotkin & Kahn, PLLC
Kim Chong H.
THK Co. Ltd.
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