WO1997047217A1

WO1997047217A1 - Telescopic guide

Info

Publication number: WO1997047217A1
Application number: PCT/EP1997/003083
Authority: WO
Inventors: Karl Heinz Strauss
Original assignee: Herbert Grüttner GmbH & Co. KG
Priority date: 1996-06-12
Filing date: 1997-06-12
Publication date: 1997-12-18
Also published as: DE19623437A1; DE19623437C2

Abstract

The invention relates to a telescopic guide (10) with a metal polygonal outer tube (12) and a ball bearing cage (18) with at least two rows of balls (16) which roll in three different corners of the outer tube (12). A metal inner tube (14) is guided by the balls (16) in the outer tube (12) and has in the peripheral regions thereof in which the balls (16) roll, a convex cross-section. The size of the balls (16) is such that when they roll in, they cause plastic deformation of the surface of the inner tube (14) and, consequently, produce guide grooves (24) in said inner tube (14).

Description

TELESCOPIC GUIDE

The invention relates to a telescopic guide according to the preamble of claim 1, which is used for example for height-adjustable tables.

A conventional telescopic guide of this type, which is manufactured and sold by the applicant, has an outer tube made of metal with a rectangular cross-section, in which an inner tube made of metal is guided by means of running balls and also has a rectangular cross-section. The balls are held in a ball cage in such a way that they form four rows of balls in the four inner corners of the outer tube. The longitudinal edges of the inner tube are drawn inwards so that they form guide grooves for the running balls. In this way, a torsion-proof guidance of the inner tube in the outer tube is achieved. The running balls are each supported with two points of their surface on the outer tube and with another two points in the guide groove formed by the inner tube and are dimensioned such that the inner tube is guided in the outer tube with virtually no play.

For the telescope guide to function properly, it is essential that the profiles of the inner tube and the outer tube have narrow dimensional tolerances. Precision tubes are therefore used, which are drawn through appropriate dies to maintain the desired profile shapes and dimensions. This results in high manufacturing costs, especially for the relatively complicated shaped inner tube. Nevertheless, due to the inevitable dimensional tolerances, there is often some play in the inner tube in the outer tube. This play must be compensated for in a relatively cumbersome manner by using balls with a suitably adapted diameter during assembly.

FR 1 278 851 discloses telescopic guides with an outer tube which is square in cross section and a round inner tube. The running balls are guided here without a ball cage in only two diagonally opposite inner corners of the outer tube, so that dimensional tolerances can be compensated for by the square outer tube being elastically deformed into a slightly diamond-shaped cross section. This principle can also be reversed by using a rigid outer tube and an elastically deformable inner tube. Grooves are incorporated in the round tube, which the Giving guidance balls. However, the guidance stability that can be achieved in this way is not sufficient for many practical applications. The manufacturing outlay is also still relatively high since the grooves have to be machined into the round tube.

The object of the invention is to provide a telescopic guide of the type mentioned at the outset, which can be produced inexpensively and yet permits stable, low-play and twist-free guidance of the inner tube in the outer tube.

This object is achieved by a telescopic guide with the features specified in claim 1.

According to the invention, the inner tube has a convexly rounded cross section in the peripheral regions at which the running balls roll. The running balls are dimensioned such that they plastically deform the surface of the inner tube when they run in, thereby creating flat guide grooves in the inner tube.

Since the inner tube can have a very simple profile shape and, for example in the case of a square or round outer tube, can simply be formed by a round tube, a considerable reduction in the production costs is achieved. In addition, inexpensive welded and non-tightened pipes can be used for the inner pipe and the outer pipe, for example pipes according to DIN 2395 for the outer pipe and according to DIN 2394 for the inner pipe. This results in a further considerable cost saving. The larger dimensional tolerances compared to the prior art are compensated for when the telescopic guide is run in, in that the running balls plastically deform the surface of the inner tube and thereby create guide grooves themselves. These guide grooves also ensure that the inner tube is secured against twisting, which is completely sufficient for most practical applications, for example for a height-adjustable table supported on two telescopic columns.

Since the inner tube is supported at least three points on its circumference by the balls guided in a ball cage and / or the inner corners of the outer tube, a high degree of guidance stability is achieved, so that the Telescopic guide can absorb high lateral forces in every direction. The at least three-point support of the inner tube, in combination with the convex shape of the inner tube, also makes a significant contribution to ensuring that the pressure exerted on the inner tube by the running balls as the telescopic guide does not give in to the wall of the inner tube and thus to one Changing the overall cross-sectional shape leads only to the formation of shallow grooves in the surface of the inner tube. Another important fact that enables this deformation behavior is that the running balls are supported on the inner tube at a single point, so that the deformation forces are concentrated on one point.

Due to the plastic yielding of the inner tube, dimensional tolerances can be compensated to a considerable extent, so that, as a rule, balls with a fixed predetermined diameter can be used and an adaptation of the ball diameter during assembly is not necessary.

The outer tube preferably has a polygonal inner cross section. Since the running balls are then supported at two points in the inner corners of the outer tube, reliable guiding of the running balls is ensured as soon as they run in, so that exactly straight guide grooves are impressed into the surface of the inner tube. If the inner tube is a run-off tube, all that needs to be done during running-in is to avoid that a torque acts on the inner tube during the axial movement.

Another advantage is that due to the single-point support of the running balls on the inner tube and the two-point support on the outer pipe, the effective rolling radius with which the running balls roll on the outer pipe is smaller than the rolling radius of the balls on the inner pipe. For a given extension path of the inner tube, the running balls cover a smaller distance relative to the outer tube than relative to the inner tube. Thus, given the range of motion of the ball cage and the running balls in the outer tube, a greater extension length of the inner tube can be achieved. Preferred exemplary embodiments are explained in more detail below with reference to the drawing.

Show it:

1 shows a first embodiment of a telescopic guide according to the invention;

FIG. 2 is an enlarged partial view of the embodiment according to FIG. 1;

3 shows a second embodiment of the telescopic guide;

Fig. 4 shows a third embodiment of the telescopic guide.

1 shows a cross section of a telescopic guide 10 which is formed by a steel outer tube 12 with a square cross section, a round inner tube 14 made of steel arranged centrally in the outer tube and four rows of running balls 16 arranged between the outer tube and the inner tube , of which only the top ball of a row can be seen. The running balls are held by a ball cage 18. The running balls 16, which are arranged in the inner corners of the outer tube 12, are each supported at two points on an inner surface 20 of the outer tube 12 and at one point on an outer surface 22 of the inner tube 14. When the telescopic guide 10 runs in, the outer surface 22 of the inner tube 14 is plastically deformed by the running balls 16 such that guide grooves 24 are created, one of which is shown more clearly in FIG. 2.

By forming the guide grooves 24, dimensional tolerances of the running balls and the inner tube can be compensated for. On the other hand, the inner tube is secured against twisting.

Since the inner tube 14 is supported at four points on its circumference by the running balls 16, very high guide stability is achieved, so that the telescopic guide 10 can absorb high transverse forces in any direction.

FIG. 3 shows a second embodiment of the telescopic guide 10, which is a rectangular outer tube compared to the embodiment according to FIG. 1 12 and has an oval inner tube 14. To support the inner tube, four rows of running balls 16 are also used, which are arranged in the inner corners of the outer tube and are each supported at two points, while the inner tube is supported at one point for each running ball. The telescopic guide in turn has a high level of guidance stability. Because of the cross-sectional shape, the inner tube 14 is already guided in a rotationally secure manner inside the outer tube 12 when it runs in.

Fig. 4 shows a third embodiment of the telescopic guide 10, in which the outer tube 12 is designed as an equilateral triangle. A round tube is again used as the inner tube 14. In comparison to the two embodiments according to FIGS. 1 and 3, however, only three running balls 16 are necessary in order to achieve high guidance stability.

In addition to the exemplary embodiments shown, other cross-sectional shapes are also conceivable, for example a hexagonal outer tube with three or six rows of running balls.

Claims

PATENT CLAIMS

1. Telescopic guide (10) with an outer tube (12) made of metal, a ball cage (18) with at least three rows of running balls (16), which roll in three different circumferential positions on the outer tube (12), and one by means of the running balls ( 16) in the outer tube (12) guided inner tube (14) made of metal, characterized in that the inner tube (14) in the peripheral areas. in which the running balls (16) roll, have a convex, rounded cross-section and that the running balls (16) are dimensioned such that they plastically deform the surface of the inner tube (14) when they run in, thereby leading to guide grooves (24) in the inner tube (14) create.

2. Telescopic guide according to claim 1, characterized in that the outer tube (12) has a polygonal inner cross section and the balls (16) roll in the corners of the outer tube.

3. Telescopic guide according to claim 1 or 2, characterized in that the running balls (16) are held in a ball cage (18).