Bearing unit with tolerance compensation, and workpiece positioner

Abstract

In a bearing unit (5), having a bearing pin (1) and a bore (9) receiving the bearing pin, the invention proposes that the bearing pin has a bulged region (4) and the bore is designed cylindrically or prismatically such that the bulged region of the bearing pin is received in the bore with little or no play. The invention also proposes a workpiece positioner having a workpiece receptacle which is configured to hold a workpiece, wherein the workpiece receptacle has a bearing unit according to one of the preceding claims.

Description

[0001] "Bearing unit with tolerance compensation and workpiece positioner"

[0002] Description:

[0003] The invention relates to a bearing unit according to the preamble of claim 1 and to a workpiece positioner with such a bearing unit.

[0004] A generic storage unit is well known in practice. Workpiece positioners known as rotary and reversible positioners hold a workpiece to be machined on a single column, so this workpiece positioner has a workpiece holder, namely the point or assembly at which the workpiece is contacted and held. In a so-called double-column rotary positioner, such as the one offered under the designation "Hand-controlled workpiece positioner, type S40" by Wilhelm Severt Maschinenbau GmbH in Vreden, two columns are spaced apart, so this workpiece positioner has two workpiece holders. Long workpieces can be held between the two workpiece holders of the two columns.To minimize workpiece distortion in the event of asynchronous movements, the workpiece holders feature generic bearing units that enable movement around three spatial axes: A cylindrical bearing pin is mounted so it can rotate freely around its longitudinal axis. A bore that accommodates the bearing pin is tapered, meaning its cross-section expands towards both ends compared to the center, where it has its smallest diameter. Assuming that the bearing pin extends horizontally, the bearing pin can also tilt horizontally and vertically within the bore, thus also performing slight rotational movements. As a result, the bearing unit enables rotational movements around all three spatial axes.Unlike a pillow block bearing, where the bore is arranged in a single component, the bores can be implemented in two bearing shells in practice, which can be precisely adjusted to the respective bearing pins and connected to each other to compensate for tolerances. For example, the two bearing shells can be connected to each other using two clamping screws located on either side of the bore, which are fixed and non-adjustable. This design of the bearing unit is known in practice as a "snap-fit ​​bearing."

[0005] Generic bearing units have proven themselves in practice and are economical to manufacture. Due to constraints on larger angles, they require a large clearance in the respective fit. Due to the inherent design principle, the center of rotation shifts during the aforementioned tilting movements when the bearing pin is not only rotated about its longitudinal axis but also tilts horizontally or vertically. This necessitates greater bearing clearance and a change in the lever arm, thus increasing the complexity of the mathematical position determination.

[0006] The invention is based on the object of improving a generic bearing unit such that it enables precise, low-play guidance of the bearing pin and simple mathematical determination of the bearing. Furthermore, the invention is based on the object of specifying a workpiece positioner that enables the workpiece to be held to be supported with as little play as possible while allowing free movement around all three spatial axes.

[0007] This object is achieved by a bearing unit according to claim 1 and by a workpiece positioner according to claim 5. Advantageous embodiments are described in the subclaims.

[0008] In other words, the invention proposes to reverse the relationship between curvature and straightness: compared to the generic prior art, the bore, as proposed, does not have a curved cross-section, but rather a straight, constant cross-section, having either a cylindrical or a polygonal cross-section with a constant geometry, namely a prismatic cross-section. Due to the constant cross-section, the bore can be manufactured particularly easily in a single workpiece, for example, a housing. Alternatively, however, as with the known generic bearing units, the bore can be divided into two parts in the form of two bearing shells, each of which forms a partial circumference of the bore.

[0009] Furthermore, in comparison to the generic state of the art, the bearing pin does not have a straight cross-section, namely not a cylindrical cross-section, but a cross-section with a spherical area. This spherical area is accommodated in the bore with as little play as possible, so that a linear contact surface results between the bearing pin and the bore if the bore is cylindrical. However, if the bore has a polygonal cross-section, several point contacts result, corresponding to the number of surfaces in the cross-section of the bore. The spherical area of ​​the bearing pin is designed in one embodiment as a section of a spherical surface, so that regardless of the movements of the bearing pin in the bore, the initially set play between the bearing pin and the bore is always maintained unchanged.

[0010] The design of the bearing unit according to the invention enables a rotational movement about three spatial axes that are perpendicular to one another: the bearing pin can rotate about its longitudinal axis in the bore, and the bearing pin can pivot about two axes that are perpendicular to it and to one another, which are referred to as tilting movements and are limited by the bearing pin coming to one end of the bore and resting there against a respective housing part or a bearing shell.

[0011] In an alternative embodiment, however, it may be provided to deliberately limit the movement of the bearing pin around one of these three spatial axes. For this purpose, both the bore and the bearing pin interact to have a cross-section that deviates from circular, for example, in the form of a notch on one component and a rib on the other, with the rib engaging the notch.

[0012] Even if a bearing pin which does not have a circular cross-section is accommodated in a prismatic bore with a polygonal cross-section, but should also have a polygonal cross-section adapted to the bore, mobility around one of the three spatial axes can be prevented, namely around the longitudinal axis of the bearing pin.

[0013] Such a design with deliberately restricted mobility can be advantageous for certain applications of the storage unit.

[0014] For a workpiece positioner, in particular if it has two workpiece holders as explained at the beginning, the use of a bearing unit according to the invention represents an advantageous embodiment of the workpiece positioner because the bearing unit enables the workpiece end held there to be held with as little play as possible and in an alignable manner.

[0015] In particular, if the workpiece positioner has two workpiece holders as explained above, the use of a bearing unit according to the invention can help to avoid inadmissibly high bending forces or stresses in the workpiece in the event of asynchronicities between the two bearing units due to the mobility around all three spatial axes.

[0016] In one embodiment, such a workpiece positioner with two workpiece holders has a bearing unit according to the invention on each of the two workpiece holders, so that a particularly versatile compensation of asynchronies is possible.

[0017] Embodiments of the invention are explained in more detail below using purely schematic representations.

[0018] Fig. 1 a side view of a bearing bolt,

[0019] Fig. 2 shows a first embodiment of a bearing unit, sectioned in the longitudinal direction of a bearing pin located in the bearing unit, and

[0020] Fig. 3 is a perspective view of a second embodiment of a bearing unit with a bearing pin located therein.

[0021] Fig. 1 shows a bearing pin 1 having a flange plate 2, which forms the largest diameter of the bearing pin 1 and can be used, for example, to attach a connecting element when the bearing pin 1 is used as part of a workpiece holder and the workpiece—or at least one end of the workpiece—is to be held on the aforementioned connecting element. The entire component is referred to as a bearing pin 1, even if it is not intended as a whole to be accommodated or held in a bearing.

[0022] The actual bolt, which is supported, adjoins the flange plate 2 at a certain distance and has two minimum sections 3, where the bolt has its smallest diameter. Between the two minimum sections 3, the bearing bolt 1 has a spherical area 4, which is shaped like a spherical cutout surface.

[0023] Fig. 2 shows a bearing unit 5 with two bearing shells 6 and 7, with an upper bearing shell 6 and a lower bearing shell 7 being spaced apart by means of clamping screws 8. The two bearing shells 6 and 7 define a cylindrical bore 9 in which the bearing pin 1 is guided with minimal play.

[0024] With its spherical region 4, the bearing pin 1 creates a linear contact surface along which it rests against the two bearing shells 6 and 7. The two minimal sections 3 create an annular gap on either side of the spherical region 4 and thus a free space around the bearing pin 1 within the bore 9, so that the bearing pin 1, starting from its orientation with a horizontal longitudinal axis shown in Fig. 2, can tilt up and down in the vertical direction as well as perform tilting movements in the horizontal direction transverse to the plane of the drawing.

[0025] Fig. 3 shows a second embodiment of a bearing unit 5, wherein the upper bearing shell 6 and the lower bearing shell 7 are hinged together via a joint 10. For this purpose, a hinge pin 11 extends through sections of the two bearing shells 6 and 7. The bore 9, in which the bearing pin 1 is received, is concealed in Fig. 3 by the flange plate 2 provided with fastening screws 12 and the upper bearing shell 6, but it can be seen that the joint 10 is located on one side of the bore 9 and the only clamping screw 8 of this bearing unit 5 is on the other side of the bore 9, so that in this embodiment the play between the bearing shells 6, 7 and the bearing pin 1 can be adjusted using just a single clamping screw 8. A handle 14 is used to handle the upper bearing shell 6 and to pivot it about the joint 10 when the clamping screw 8 is loosened.

[0026] Reference symbol:

[0027] 1 bearing bolt

[0028] 2 flange plate

[0029] 3 Minimum section

[0030] 4 spherical area

[0031] 5 storage unit

[0032] 6 Upper bearing shell

[0033] 7 Lower bearing shell

[0034] 8 clamping screw

[0035] 9 Hole

[0036] 10 joint

[0037] 11 hinge pins

[0038] 12 fixing screw

[0039] 14 Handle

Claims

Claims:

1. Bearing unit (5), with a bearing pin (1) and a bore (9) receiving the bearing pin (1), characterized in that the bearing pin (1) has a spherical region (4) and the bore (9) is cylindrical or prismatic in such a way that the spherical region (4) of the bearing pin (1) is received in the bore (9) with little or no play.

2. Bearing unit according to claim 1, characterized in that the spherical region (4) is designed as a spherical cutout surface.

3. Bearing unit according to claim 1 or 2, characterized in that the bearing pin (1) is rotatably movable in the bore (9) about its longitudinal axis, and in that the bearing pin (1) is rotatably movable in the bore (9) about two further axes, which run in the manner of three spatial axes, each perpendicular to one another and to the longitudinal axis of the bearing pin (1).

4. Bearing unit according to claim 1 or 2, characterized in that the bore (9) and the bearing pin (1) have a cross-section that is complementary to one another and deviates from the circular shape, such that rotational mobility of the bearing pin (1) about a specific axis is prevented.

5. A workpiece positioner having a workpiece holder configured to hold a workpiece, the workpiece holder comprising a bearing unit (5) according to any one of the preceding claims.

6. Workpiece positioner according to claim 5, characterized by two workpiece holders arranged at a distance from one another, wherein one workpiece holder has a bearing unit (5) according to one of claims 1 to 4.

7. Workpiece positioner according to claim 6, characterized in that both workpiece holders each have a bearing unit (5) according to one of claims 1 to 4.

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