Machine element or mechanism – Mechanical movements – Reciprocating or oscillating to or from alternating rotary
Patent
1996-03-21
1998-04-07
Footland, Lenard A.
Machine element or mechanism
Mechanical movements
Reciprocating or oscillating to or from alternating rotary
F16C 2904
Patent
active
057351740
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
First to sixth aspects of the present invention relate to a cylindrical pipe shaped bearing or a nearly-cylindrical pipe shaped bearing for linearly moving along a cylindrical rod shaped guide member or a nearly-cylindrical rod shaped guide member. The present invention includes a rotating motion of the bearing in the peripheral direction of the guide member. Thus, the bearing according to the present invention can actively used for a rotating motion. Alternatively, the bearing can be inevitably used for a rotating motion.
Examples of the guide member or the guide are rod shaped guide members for use with dies (such as a guide post, a sub-guide post, and a guide pin), that are used in a punching process, a bending process, a drawing process, a forging process, an injection molding process, a die casting process, a powder molding process, and so forth. Other examples are cramp shafts used in an injection molding machine and a molding machine and a guide shaft used in a press machine. Further examples are spline shafts using in an instrumenting machine, a medical machine, a scientific machine, an optical machine, a copy machine, and a printer.
The "bearing" is also referred to as a bush.
A seventh aspect of the present invention relates to a female screw that fits into a male screw. Examples of the male screw are a nut and spline nut. The spline nut is fitted into a feed screw shaft.
Eighth to eleventh aspects of the present invention relate to a linearly moving block for moving on a guide rail.
Twelfth to fourteenth aspects of the present invention relate to a guide rail for guiding a linearly moving block.
A fifteenth aspect of the present invention relates to a linearly moving block unit having a ball screw shaft rotatably pivoted and an angular nut that fits into the ball screw shaft.
RELATED ART
In the technical field of the first to sixth aspects of the present invention, metal bushes and ball retainers have been widely used as related art references.
In the technical field of the seventh aspect of the present invention, metal female screws having inner threads formed by a machining process have been used.
First Problem
A metal bush has a large frictional resistance. When the metal bush is moved, a large force is required. In addition, the metal bush tends to get scuffed and baked. Moreover, the metal bush tends to wear out, resulting in a play.
The ball retainer uses a ball bearing that has balls that point contact a moving portion. Thus, even if the number of balls of the ball bearing is increased, the total contacting area is still small. Consequently, a large pressure is applied to the ball bearing, thereby causing a guide member to be linearly scratched. Since the ball bearing is used, it may be out of lubrication. In addition, frictional heat may take place. In more extreme case, the ball bearing may get baked. Moreover, since the balls of ball retainer point contact the guide member, the ball retainer tends to have a play, thereby deteriorating the dimensional accuracy. Since the degree of freedom of the ball retainer is too large, it is difficult to adjust it. Since the frictional resistance of the conventional retainer is large, a large force is required to perform a sliding motion of a die set. Moreover, since the balls of the ball bearing are disposed in a diagonal direction, the relative motion of the guide post and the retainer tends to be performed in the diagonal direction. As a result, the motion of the bearing becomes a spiral motion including a rotating motion rather than a true linear motion. Thus, an undesired lateral force is applied to a punching cutter or the like of a die. Consequently, the cutter tends to get damaged or partially worn out.
Second Problem
Since the conventional female screw and the spline nut are composed of a metal and machine processed, they are expensive and tend to get scuffed. When the female screw and the spline nut use ball bearings, the cost thereof more increases.
In the technical field of the twelfth to fourteenth aspects of the pre
REFERENCES:
patent: 5074160 (1991-12-01), Kasuga
patent: 5302032 (1994-04-01), Niwa et al.
patent: 5454278 (1995-10-01), Kasuga
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