Pivot bearing provided on support structures formed of shaped bars

A pivot bearing comprises a shaped bar having an outer circumferential surface provided with two oppositely arranged, longitudinally extending notches, and a sleeve arranged on the shaped bar and having an externally cylindrical surface and an inner circumferential surface facing the outer circumferential surface of the shaped bar and provided with two oppositely arranged longitudinally extending notches. The longitudinally extending notches of the shaped bar are in alignment with the longitudinally extending notches of the sleeve to form two pairs of notches, and cylindrical pins are arranged in the two pairs of notches.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention is related to a pivot bearing provided on support
 structures formed of shaped bars, which, in particular, is secured to and
 moved by robot arms, and which is used for attaching tools, such as
 clamping, suction, gripping equipment and/or the like tools.
 2. Description of the Prior Art
 Shaped bars of the afore-described type are used for assembling support
 structures which, in turn, are especially intended for attachment to robot
 arms and for securing tools such as clamping, suction and gripping
 equipment and/or other working equipment.
 The shaped bars intended for the afore-described purposes that are
 interconnected by corresponding clamping elements correspondingly
 conforming in profile, as a rule, are profiles of octagonal configuration
 which, in turn, are normally provided with not less than two radially
 opposite notches. Bars of octagonal profiles are preferably used for the
 afore-mentioned purposes to enable the clamping elements of conforming
 profiles to be mounted in eight different orientations to the shaped bars,
 depending on the orientation in which the tools referred to in the
 afore-going by way of example, are to be seated on the support structure,
 and, furthermore, depending on the orientation intended for crossing
 shaped bars held by the same clamping element. No direct and stepless
 adjustment of orientation of tools of the afore-described type relative to
 shaped bars of polygonal configuration of the afore-mentioned type,
 through a clamping element, hitherto, has been possible so that a special
 configuration of the clamping elements has been required to the effect
 that they had to be combined with a pair of turntables in the event that a
 stepless displacement was desired, with such a procedure involving
 substantial efforts.
 For further details regarding special clamping elements adapted to be
 mounted to shaped bars, reference is made to U.S. Pat. No. 4,032,245.
 However, UK Patent Application GB 2 275 737 A also teaches support
 structures of this type wherein the support bars are made of cylindrical
 sectional tubes. As the shaped bars irrespective of whether they are of a
 cylindrical or polygonal configuration, are of drawn material, inevitable
 inaccuracies will occur which are likely to result in inaccuracies of
 adjustment of attached tools of the afore-mentioned type. Moreover, it is
 not possible to safeguard a torque-resistant seat in all radial
 orientations by clamping alone.
 OBJECTS AND SUMMARY OF THE INVENTION
 It is, therefore, a primary object of the present invention to provide a
 new and improved pivot bearing on shaped bars of this type that can be
 precisely centered relative to the longitudinal axis of the shaped bars in
 an easy way and by simple means.
 Another object of the present invention is to provide a pivot bearing which
 can be mounted in a torque-resistant way on the respective sectional bar.
 An additional object of the present invention is to provide a pivot bearing
 that can be mounted to the sectional bar concerned.
 A still further object of the present invention is to provide a pivot
 bearing which is so dimensioned that an item to be attached thereto also
 in the axial direction can be adjusted and fixed.
 The afore-going and other objects are attained in accordance with one
 aspect of the present invention through the provision of a pivot bearing
 which comprises a sleeve at least externally of a cylindrical
 configuration which on the inner circumferential face thereof is provided
 with two diametrically opposed notches and at least two notches arranged
 diametrically opposite the outer circumferential face of the sectional bar
 concerned which are in alignment with the notches of the sleeve, with
 cylindrical pins in abutment with the faces of the notches being arranged
 in the pairs of notches.
 The term "pivot bearing" in the present context, obviously, does, not refer
 to an element about which another element is to permanently rotate; it
 rather means an internal stationary bearing for an element to be mounted
 thereon which can be fixed to the said "pivot bearing" in any desired
 radial position.
 Accordingly, with the sleeve at least externally of a cylindrical
 configuration, a torque-resistant pivot bearing is associated to the
 respective sectional bar, at the desired point of attachment, to which is
 then directly pushed a corresponding inner cylindrical adapter which can
 be steplessly fixed in any desired radial orientation to the sleeve or to
 the pivot bearing of the present invention yet to be explained in greater
 detail hereinafter.
 The tool desired to be attached at this point can be suitably fixed to such
 an adapter.
 As such support clamps carried by robot arms and being movable in all
 directions require the best possible accuracy of position for the tools
 attached thereto, also the sleeve must be precisely centered relative to
 the longitudinal axis of the sectional bar; this centering requirement is
 complied with, in a simple way, by the notches of the invention and the
 cylindrical pins. The said pins not only insure torque-resistance of the
 sleeve but especially also an accurate centering of the sleeve relative to
 the axis of the sectional bar. As, in addition, sectional bars of this
 type for the afore-described purpose of providing robot-supported and
 robot-moved supports, as a rule, and, in particular, in polygonal
 cross-sections, are also provided, as mentioned before, with not less than
 two groves of the type suggested by the present invention, an advantageous
 embodiment of the pivot bearing resides in that the sleeve is provided
 with two radially inward bridges arranged radially opposite and fitting in
 grooves of the sectional bars and being in engagement therewith, with the
 grooves and bridges being arranged in staggered relationship to the pairs
 of notches. Accordingly, in this form of embodiment, it is especially the
 bridges of the sleeve that contribute, with advantgage, to the torque
 resistance.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 FIGS. 1, 2 are sectional views of typical shaped bars 1 of octagonal
 configuration of the type as used for the assembly of support structures
 arranged on robot arms. A support structure of this type is shown in FIG.
 10, wherein the sectional bars 1 are interconnected by so-called clamping
 members KS which do not require any special description as they are known
 in the art and are of no particular interest in the present context.
 Reference is only made to the fact that the bar connectors shown in FIG. 9
 are the combination of the clamping members and turntables referred to in
 the introductory part by way of which grippers G as shown cannot be
 directly adjusted in a steplessly rotating way to the axes A of the shaped
 bars 1.
 The shaped bars 1 sectionally shown in FIGS. 1,2 are profiles octagonal in
 cross-section essentially distinguished only by their cross-sectional size
 and the number of their grooves 2. Under consideration of the overall
 stability and rigidity, respectively, of such support structures formed of
 shaped bars, the shaped bars are of a relatively thick wall strength, as
 shown, for example, relative to the respective diameter.
 The pivot bearing of the present invention to be formed of such shaped bars
 1, in reference to FIG. 3, substantially comprises a sleeve 3 at least
 externally of a cylindrical configuration and, on their internal
 circumferential face 4, being provided with two diametrically opposite
 notches 5, with at least two corresponding notches 6 being arranged
 diametrically opposite the outer circumferential face of the respectively
 shaped bar 1, which notches 6 are in alignment with the notches 5 of the
 sleeve 3. Arranged within the so formed pairs of notches 5,6, in the
 practice of the invention, are cylindrical pins 7 in abutment with the
 faces 5', 6' of the notches 5,6.
 Concerning the association of pins 7 to notches 5,6 reference is made to
 the highly schematized illustration of FIG. 8. Pins 7 in conjunction with
 notches 5,6 triangular in cross-section serve both for centering the
 sleeve 3 precisely to axis A of shaped bar 1 and, at the same time, for
 the torque-resistance of sleeve 3 vis-a-vis shaped bar 1.
 As shaped bars of the type as set out in FIGS. 1, 2 are preferably used for
 the present purposes, as previously mentioned, which are therefore
 provided with grooves 3, an advantageous development according to FIG. 4
 resides in that the sleeve 3 forming the pivot bearing of the invention is
 provided with two radially inwardly extending, radially opposing bridges 8
 fitting in grooves 2 of the shaped bar, with the grooves 2 and the bridges
 8 being arranged in staggered relationship to the pairs of notches 5,6.
 Accordingly, the torque-resistance is insured, in particular, by the
 bridges 8 engaging the grooves 2, i.e. the notches and the fitting pins 7
 in that case can be smaller dimensioned than in the form of embodiment
 according to FIG. 3.
 FIG. 4 also shows a form of embodiment in which sleeve 3 of the invention
 with the inner face 4' thereof substantially conforms to the polygonal
 cross-sectional configuration of the shaped bar 1.
 FIG. 5 is a perspective view of the arrangement of the pivot bearing and of
 the sleeve 3, respectively, seated on a shaped bar 1, at the same time
 showing an adapter AR fixed in clamping relationship on the sleeve 3, to
 which adapter a tool may then be attached. Accordingly, an adapter AR of
 this type can be fixed in any desired position to the sleeve 3. The length
 L of the sleeve 3, preferably, corresponds at least to twice its diameter
 in order to enable such an adapter AR also to be differently positioned in
 the axial direction.
 FIG. 6 shows a special form of embodiment of the sleeve 3 inasmuch as it is
 formed of two identical cup halves 3' which, as illustrated, may be
 crossed or shanked at the butt edges thereof, where they can also be
 screwed in the area of conjugated diameters D' but means of nuts 10 only
 shown in broken lines. The heads of nuts 10 must, of course, be housed in
 bores 11, i.e. the latter are not allowed to protrude beyond the outer
 circumferential face 12 of the sleeve 3.
 FIG. 7 shows another form of embodiment of the invention in which the
 shaped bar 1 is a cylindrical tube to which the sleeve 3 is to be
 associated in a precisely centered way despite the internal oversize 13
 which, also in this form of embodiment, is completed by forcing or pushing
 the two cylindrical pins 7 into the pairs of notches 5,6 also provided
 herein. The oversize 13 referred to above which may be in the order of 1
 to 2 mm, obviously, also exists between bar 1 and sleeve 3 of the other
 forms of embodiment.
 FIG. 9 discloses a sectional view taken along the line IX--IX in FIG. 5 of
 the pivot bearing, showing that the notches 5,6 extend both along the
 sleeve 3 and along the bar 1 across the entire length thereof. In order to
 prevent the pins 7 from being folded up by a length corresponding to the
 length L of the sleeve 3, within the pairs of notches with a slight press
 fit, the pins 7 relative to the length of the notches 5, in sleeve 3, are
 shorter dimensioned and are pushed from both sides into the pairs of
 notches. Moreover, an additional axial attachment of the sleeve 3 to the
 shaped bar 1 can be insured by a countersunk screw 15 as equally shown by
 FIG. 9.
 As set out in the introductory part of the description, FIG. 10 shows
 shaped bars 1 joined together by means of clamping members KS forming a
 support structure TG carried by a robot arm not shown in any detail, to
 which is attached the support structure TG by means of a centrally
 arranged connecting plate 14. As this constitutes but an example for a
 support structure TG, no pivot bearings of the type provided by the
 invention, are shown thereon.
 Obviously, numerous modifications and variations of the present invention
 are possible in the light of the above teachings. It is, therefore, to be
 understood that within the scope of the appended Claims, the invention may
 be practiced otherwise than as specifically described therein.