Machine element or mechanism – Gearing – Teeth
Patent
1999-03-23
2000-07-18
Wright, Dirk
Machine element or mechanism
Gearing
Teeth
F16H 2522
Patent
active
060891173
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a ball screw unit comprising a screw and a nut assembly which are screw-fitted with each other through a number of balls and adapted to covert the rotary motion of a motor or the like to a linear motion at the slide portion of a machine tool or an industrial robot, and more particularly, to a tube type ball screw unit using a nut and a ball circulating cylindrical body or a side cover type ball screw unit using a nut and a pair of covers respectively fixed to both ends of the nut for the purpose of forming an endless track for the balls.
BACKGROUND TECHNOLOGY
Generally, the ball screw unit basically comprises a screw provided with a helical ball rolling groove on the outer peripheral surface thereof, a nut provided on the inner peripheral surface thereof with a helical load rolling groove held opposite to the ball rolling groove of the screw and having the same lead angle as the latter and a number of balls interposed between the load rolling groove and the ball rolling groove so as to roll while bearing a load and wherein an endless track for causing the balls to circulate therethrough is formed by constructing a nut assembly by fixing a ball circulating tubular body or a pair of covers to the nut.
Conventionally, there have been known several methods for forming the above-described ball endless track.
For example, regarding the tube type ball screw unit, there is known a tube system (Japanese Unexamined Utility Model Publication No. S49-64,672) in which as shown in FIGS. 40 and 41, ball tubes(f)(ball circulating tubular bodies) each provided on both ends thereof with tongues (g) are passed between the starting end and the terminating end of a load zone formed by a ball rolling groove(b) of a screw(a) and a load rolling groove(d) of a nut(c) such that each of balls(e) rolling within the ball rolling groove(b) of the load zone is picked up or fed into the groove (b) by the tongues (g) projecting into the groove (b) so that each of the balls(e) coming out from the terminating end of the load zone is circulated again into the starting end of the load zone through the ball tubes (f).
According to this tube system, however, when each of the balls(e) moves from the terminating end of the load zone of the endless track to the no-loaded zone thereof, the ball(e) runs against the tongue(g) of each of the tubes (f) so that the rolling ball(e) is picked up into the ball tube(f) forming the no-load zone and is then circulated again into the starting end of the load zone.
Further, as regards the side cover type ball nut and screw unit, there is known a side cover system disclosed in the U.S. Pat. No. 4,148,226 (entitled "Ball nut and screw assembly")in which as shown in FIGS. 42 through 44, a ball return hole(h) is drilled in a nut(c) along an axial direction of the outer peripheral solid portion thereof and a pair of side covers (k) are respectively fixed to both ends of the nut(c) through spacers(i) so that the progressing direction of each of balls(e) coming out of the terminating end of a load zone formed by a ball rolling groove (b) of a screw(a) and a load rolling groove(d) of the nut(c) is inclined by each of the side covers (k) and each of the spacers(i) thereby guiding the ball(e) from the terminating end of the load zone up to the outer cylindrical surface of a screw (a). Further, a change direction path(j) for guiding the ball(e) up to the ball return hole(h) of the nut(c) is formed in each of the side covers thereby forming a ball endless track.
However, this system is also constructed such that when the ball(e) moves from the terminating end of the load zone of the ball endless track to the no-load zone, the ball (e) runs against the side wall of the change direction path (j) inclined with respect to the ball progressing direction at the terminating end of the load zone, that is, from the tangential direction along the lead angle of the load rolling groove(d), so that the rolling ball(e) is picked up into the change direction path(j) forming the no-load
REFERENCES:
patent: 4148226 (1979-04-01), Benton
Ebina Shigeru
Takeda Ryuji
THK Co. Ltd.
Wright Dirk
LandOfFree
Ball screw device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ball screw device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ball screw device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2025310