Joints and connections – Articulated members – Pivoted
Reexamination Certificate
1999-09-08
2001-11-13
Kim, Harry C. (Department: 3629)
Joints and connections
Articulated members
Pivoted
C403S114000
Reexamination Certificate
active
06315486
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a joint having a pin which carries an element that is received via a rolling bearing for pivoting in an associated housing.
BACKGROUND OF THE INVENTION
If the element that receives the pin is spherical in shape and pivotable in a socket, these joints are called ball-and-socket joints. Such a rolling bearing-mounted ball-and-socket joint is known from U.S. Pat. No. 2,971,770. The pin is rotatably secured by a ball bearing to the flat undersurface of the spherical element which is mounted with its semispherical surface through a plurality of small bearing balls for pivoting in a spherical recess. Ball-and-socket joints of this type are used in the field of front wheel suspensions of automotive vehicles. The drawback of these rolling bearing-mounted ball-and-socket joints is, on the one hand, that due to the pointwise contact of the spherical element with a plurality of small bearing balls, high Hertzian stresses occur and, on the other hand, these joints possess an inadequate rigidity.
However, in addition to the automotive industry, other uses are also conceivable in which a low rigidity of the joints is undesirable. This is the case in the sector of machine tools when omnidirectionally orientable joints are used for the positioning of tools. In this case, joints are required that can effect a pin-point positioning of a tool.
SUMMARY OF THE INVENTION
It is therefore the object of the invention to create a rolling bearing-mounted joint which avoids the drawbacks of prior art ball-and-socket joints while at least attaining their angles of pivot.
The invention achieves this object by a pin (
1
) that is received by an inner member (
2
), this inner member (
2
) is received via rolling bearings (
4
,
5
,
19
,
20
) arranged on its outer peripheral surface for pivoting about its rotational axis (
3
) in a center member (
6
), this center member (
6
) is received offset at 90° to the rotational axis (
3
) of the inner member (
2
) via rolling bearings (
9
,
10
) arranged on its outer peripheral surface for pivoting about its rotational axis (
7
) in a housing body (
8
), and the housing body (
8
) is mounted offset at
900
to the rotational axis (
3
) of the inner member
92
) and to the rotational axis (
7
) of the center member (
6
) in a flange ring (
12
) via rolling bearings (
13
,
14
,
18
) arranged on its outer peripheral surface for rotation about its rotational axis (
15
), the rotational axis (
3
,
7
,
15
) of the inner member (
2
), the center member (
6
) and the housing body (
8
) starting from a common point.
The technical improvement that can be attained with the inventive configuration of the joint resides particularly in its high rigidity and the resulting high positioning precision.
The rolling bearings provided between the individual components of the joint advantageously guarantee a comparatively low frictional resistance and thus also a low pivoting resistance while, at the same time, at least the pivoting ability of a conventional ball-and-socket joint is attained.
The center member has a disc-shaped configuration and is pivotally mounted with the help of two opposing angular needle bearings arranged back-to-back. By angular needle bearings is meant that the effective direction of the force of pressure applied to each rolling element is inclined relative to the longitudinal axis of the pin. Due to their radial compactness, the used needle bearings guarantee a particularly space-saving spatial arrangement.
The different configurations of the inner member which receives the pin are as follows. In one case, the inner member is disc-shaped and mounted with the help of two opposing angular needle bearings arranged face-to-face, or the inner member is spherical in shape and mounted with the help of two angular needle bearings arranged back-to-back.
The housing body which receives the inner member and the center member is mounted for rotation i the flange ring with the help of a cross roller bearing or by two opposing angular needle bearings arranged face-to-face. Both types of mounting are equally feasible.
According to a further feature of the invention, the rolling bearings are pre-stressed. This pre-stress prevents a radial displacement of the components of the joint arranged in one another so that a particularly high positioning precision can be achieved.
The housing body, the center member and the inner member are each made of two pieces and joined together by fixing screws to form a unit. Thus two-piece configuration assures the easy assembly of the rolling bearing-mounted joint.
Finally, the rolling bearing-mounted joint is used in machine tools of the hexapod system. These machine tools of a new generation are known to the person skilled in the art and, in contrast to conventional machine tools, they move small masses. The result of this is that higher adjusting speeds are reached and, particularly, the rigidity between the frame and the tool holder is very high. Such a machine tool can comprise a plurality of arms which are articulated at one end on a frame and at the other end, on a tool holder. The rolling bearing-mounted joints of the invention can be used advantageously in this type of machine tools.
The invention will now be described more closely with reference to the following examples of embodiment.
REFERENCES:
patent: 1959563 (1934-05-01), Baker
patent: 2641492 (1953-06-01), Flumerfelt
patent: 2971770 (1961-02-01), Wagner
patent: 3068032 (1962-12-01), Van Winsen
patent: 4459122 (1984-07-01), Rehfeld
patent: 4986689 (1991-01-01), Drutchas
patent: 4995755 (1991-02-01), Hyodo et al.
patent: 6071031 (2000-06-01), Bailey
patent: 8990033 (1953-03-01), None
patent: 3605583 (1986-08-01), None
patent: 19617880 (1996-10-01), None
Bierman, Muserlian and Lucas
Ina Walzlager Schaeffler OHG
Kim Harry C.
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