ROLLING ELEMENT CAGE

Abstract

A rolling element cage for a linear guide system includes two receiving portions and a connecting portion connecting the two receiving portions, wherein each of the two receiving portions includes two extended top surfaces. The two receiving portions each include a plurality of apertures. Each aperture includes a side surface connecting the two top surfaces. At least one of a plurality of bearing rolling elements is receivable in each of the plurality of apertures of the rolling element cage, so that the side surface of the aperture or a transition between one of the two top surfaces and the side surface can be brought into contact with a rolling element surface of the bearing rolling element which is receivable in the aperture. The transition between one of the two top surfaces and the side surface includes, at least in sections, a broken edge, an edge including a chamfer or a rounding.

Claims

1. A rolling element cage for a linear guide system comprising two receiving portions and a connecting portion connecting the two receiving portions, wherein each of the two receiving portions comprises two extended top surfaces, wherein the two receiving portions each comprise a plurality of apertures, wherein each aperture comprises a side surface connecting the two top surfaces, wherein at least one of a plurality of bearing rolling elements is receivable in one of the plurality of apertures of the rolling element cage, so that the side surface of the aperture or a transition between one of the two top surfaces and the side surface can be brought into contact with a rolling element surface of the bearing rolling element receivable in the aperture, and wherein the transition between one of the two top surfaces and the side surface comprises, at least in sections, a broken edge, an edge comprising a chamfer or a rounding.

2. The rolling element cage according to claim 1, wherein the rolling element cage consists of sheet metal.

3. The rolling element cage according to claim 1, wherein the rolling element cage is obtainable by a method comprising air blasting the rolling element cage with a solid blasting medium.

4. The rolling element cage according to claim 1, wherein the rolling element cage is obtainable by a method comprising vibratory grinding of the rolling element cage.

5. The rolling element cage according to claim 1, wherein the rolling element cage is obtainable by a method comprising embossing the transition between the side wall surface and the top surface with a forming tool, so that the rounding is formed, wherein a course of the rounding is predetermined by a shape of the forming tool, or by a chip removing method.

6. The rolling element cage according to claim 1, wherein the rolling element cage is manufactured from brass or bronze.

7. A linear guide system comprising a first rail element comprising two first running surfaces, a second rail element comprising two second running surfaces, the rolling element cage according to claim 1, and a plurality of bearing rolling elements, wherein at least one of the plurality of bearing rolling elements is received in one of the plurality of apertures of the rolling element cage, wherein the side surface of the aperture or the transition between one of the two top surfaces and the side surface is in contact with a rolling element surface of the bearing rolling element received in the aperture, and wherein the rolling element cage positions the plurality of bearing rolling elements between the first running surfaces of the first rail element and the second running surfaces of the second rail element, so that the first rail element and the second rail element are supported against each other in such a way that the first rail element and the second rail element are linearly displaceable relative to each other in and against a pull-out direction.

8. The linear guide system according to claim 7, wherein at least one of the plurality of bearing rolling elements is a bearing ball, wherein the bearing ball comprises a plurality of planes of symmetry, wherein the plurality of planes of symmetry include a straight line extending through the centre of the bearing ball and perpendicular to the pull-out direction, wherein either the chamfer is straight, convexly curved or concavely curved in at least one of the plurality of planes of symmetry or the rounding is convexly curved or concavely curved in at least one of the plurality of planes of symmetry.

9. The linear guide system according to claim 7, wherein the rolling element cage comprises a thickness which is at least 5% of the radius of the bearing rolling element.

10. The linear guide system according to claim 7, wherein the rolling element cage is manufactured from a material comprising a smaller hardness than a material from which at least a plurality of the bearing rolling elements is manufactured.

11. The linear guide system according to claim 7, wherein the linear guide system comprises a plurality of bearing rolling elements and a plurality of lubricant rolling elements, wherein the lubricant rolling elements comprise or consist of a lubricant and wherein the bearing rolling elements are made of a material comprising a larger hardness than the lubricant of the lubricant rolling elements.

12. A method for manufacturing a rolling element cage for a linear guide system comprising providing a material section, wherein the material section defines two receiving portions and a connecting portion of the rolling element cage connecting the two receiving portions, wherein each of the two receiving portions comprises two extended top surfaces, wherein the two receiving portions each comprise a plurality of apertures, wherein each aperture comprises a side surface connecting the two top surfaces, and wherein a transition is formed between each of the two top surfaces and the side surface; and machining a transition between one of the two top surfaces and the side surface so that the transition comprises at least in sections a broken edge, an edge comprising a chamfer or a rounding.

13. The method according to claim 12, wherein the machining of the transition comprises at least one step selected from air blasting the material section comprising a solid blasting medium, vibratory grinding of the material section, embossing the transition between the side wall surface and the top surface with a forming tool so that the rounding is formed, wherein a course of the rounding is predetermined by a shape of the forming tool, and machining the transition between the side wall surface and the top surface.

14. The method according to claim 13, wherein providing the material section comprises the steps of providing a strip from a metal sheet and cutting or punching out the plurality of apertures.

15. The method according to claim 14, wherein after cutting out or punching out the plurality of apertures, the transition between the side wall surface and the top surface is embossed with a forming tool and after embossing, the receiving portions are bent relative to the connecting portion.

Description

[0072] Further advantages, features and possible applications of the present invention become apparent from the following description of an embodiment and the associated figures. In the figures, like elements are designated by identical reference numbers.

[0073] FIG. 1 is a side view of a sheet metal strip for a ball cage according to an embodiment of the present invention.

[0074] FIG. 2 is a top view of the sheet metal strip of FIG. 1.

[0075] FIG. 3 is an enlarged side view of the sheet metal strip cut along the line C-C of FIG. 2.

[0076] FIG. 4 is an enlarged view of the area marked with the letter F in FIG. 3.

[0077] FIG. 5 is an isometric view of an embossing die.

[0078] FIG. 6 is an isometric view of a mould complementary to the embossing die of FIG. 5.

[0079] FIG. 7 is a top view of the sheet metal strip of FIGS. 1 to 4 after embossing.

[0080] FIG. 8 is an enlarged side view of the sheet metal strip of FIG. 7, cut along the line E-E.

[0081] FIG. 9 is an enlarged view of the area marked with the letter G in FIG. 8.

[0082] FIG. 10 is an isometric view of the ball cage after bending the sheet metal strip of FIGS. 7 to 9.

[0083] FIG. 11 is a top view of the ball cage of FIG. 10.

[0084] FIG. 12 is an enlarged side view of the ball cage of FIG. 11, cut along the line H-H.

[0085] FIG. 13 is an enlarged view of the area marked with the letter J in FIG. 12.

[0086] FIG. 14 is an isometric view of the ball cage of FIGS. 10 to 13 with bearing balls mounted on it.

[0087] FIG. 15 is a sectional side view of the ball cage with the bearing balls along the line K-K of FIG. 14.

[0088] FIG. 16 is an isometric representation of a linear guide system comprising the ball cage and the bearing balls of FIGS. 14 and 15.

[0089] FIG. 17 is an enlarged view of an area of an alternative embodiment of the sheet metal, which is marked with the letter G in FIG. 8.

[0090] FIGS. 1 to 4 show a sheet metal strip 1 for manufacturing a rolling element cage according to the invention in the form of a ball cage 21. The sheet metal strip 2 shown not only provides the starting material for the ball cage 21 according to the invention, but also illustrates the prior art.

[0091] The finished ball cage 21 is later formed from the sheet metal strip 1 by bending two receiving portions in the form of receiving legs 2, 3 opposite a connecting portion in the form of a cage back 4. Apertures 5 open towards the edge are provided in the receiving legs 2, 3 to accommodate the rolling elements in the form of bearing balls 16. The apertures 5 accommodate the bearing balls 16. The apertures 5 are open towards the edge of the sheet 1, but surround the balls by more than 180 degrees.

[0092] In the embodiment shown, the apertures 5 are punched into the sheet metal of the ball cage 21. As a result of the punching, the side surfaces 6 of the apertures and the top surfaces 7 and 8 are essentially at right angles to each other. This can be clearly seen in the enlarged view of FIG. 4. The right-angled edges of the apertures, where the side surfaces 6 intersect with the top surfaces 7, 8, are labelled by reference number 9.

[0093] It has been shown that such right-angled edges 9 lead to increased noise when the bearing balls 16 roll between the running surfaces of the first and second rail elements when the bearing balls 16 come into contact with these edges 9.

[0094] According to the invention, it is now provided to break these right-angled edges 9, to provide them with a chamfer or rounding them off. In the embodiment shown in FIGS. 1 to 4 and 7 to 16, the edges 9 are rounded. The transition between the side surface 6 of the aperture 5 and the top surface 7 comprises a rounding 10. In contrast, the embodiment shown in FIG. 17 has a linear chamfer 23 in the area of the transition between the side surface 6 of the aperture 5 and the top surface 7.

[0095] To form the rounding 10 of the embodiment of FIGS. 1 to 4 and 7 to 16, each aperture 5 is embossed with a tool, as shown in FIGS. 5 and 6, so that the rectangular shape of the edges 9 is replaced by a rounded shape in the transition between the top surface 7 and the side surface 6 of the aperture 5.

[0096] The tool comprises a punch 11 and a counter tool, i.e. a die 12. The punch is shown in FIG. 5, while the die 12 is shown in FIG. 6.

[0097] The punch 11 has a centring pin 13 to insert the punch 11 centred into a centring bore 14 of the die 12. The actual moulding embossing surface is designated in FIG. 5 by reference number 15. This embossing surface 15 is complementary to the rounding which the transition between the side surface 6 of the aperture and the top surfaces 7, 8 of the material of the ball cage 21 is to receive. In the embodiment shown, the embossing surface 15 is annularly concave-convex, so that the embossing surface 15 comprises a concave cross-section in each cross-sectional plane containing the axis of symmetry of the centring pin 13. During embossing, this concave cross-section leads to the convex shape of the transition between the side surface 6 and the top surface 7, which is clearly visible in FIGS. 8 to 13.

[0098] After embossing of each of the apertures 5 has been completed, the receiving legs 2, 3 are bent with respect to the ball cage back 4 so that the finished ball cage 21 shown in FIGS. 10 to 15 is formed. The enlarged illustrations in FIGS. 12 and 13 show the spherical shape of the apertures 5 between the top surface 7 and the side surface 6.

[0099] FIG. 16 shows the assembled linear guide system in the form of a telescopic rail 17, in which the ball cage 21 comprising the bearing balls 16 is installed. The telescopic rail 17 comprises a first rail element 18 and a second rail element 19. Each of the two C-shaped rail elements 18, 19 consists of a rail back 20, which connects two legs 22 to each other. The legs 22 are bent with respect to the respective rail backs 20. The legs 22 of the two rail elements 18, 19 each have running surfaces pointing towards each other. The running surfaces of the first rail element are referred to as first running surfaces 23 and the running surfaces of the second rail element are referred to as second running surfaces 24. During a relative movement of the first rail element 18 with respect to the second rail element 19, the bearing balls 16 roll between the first running surfaces 23 and the second running surfaces 24 of the two rail elements.

[0100] For the purposes of the original disclosure, it is pointed out that all features as they are apparent to a person skilled in the art from the present description, the drawings and the claims, even if they have been described specifically only in connection with certain further features, can be combined both individually and in any combination with other features or groups of features disclosed herein, unless this has been expressly excluded or technical circumstances make such combinations impossible or meaningless. A comprehensive, explicit description of all conceivable combinations of features is omitted here only for the sake of brevity and readability of the description.

[0101] Whilst the invention has been illustrated and described in detail in the drawings and the preceding description, this illustration and description is given by way of example only and is not intended to limit the scope of protection as defined by the claims. The invention is not limited to the disclosed embodiments.

[0102] Variations of the disclosed embodiments will be obvious to those skilled in the art from the drawings, the description and the appended claims. In the claims, the word comprising does not exclude other elements or steps, and the indefinite article one or a does not exclude a plurality. The mere fact that certain features are claimed in different claims does not exclude their combination. Reference numbers in the claims are not intended to limit the scope of protection.

LIST OF REFERENCE NUMBERS

[0103] 1 Sheet metal strip [0104] 2, 3 Receiving leg [0105] 4 Cage back [0106] 5 Apertures [0107] 6 Side surface [0108] 7, 8 Top surface [0109] 9 Edge [0110] 10 Rounding [0111] 11 Punch [0112] 12 Die [0113] 13 Centre pin [0114] 14 Cylinder bore [0115] 15 Embossing surface [0116] 16 Bearing balls [0117] 17 Telescopic rail [0118] 18 First rail element [0119] 19 Second rail element [0120] 20 Rail back [0121] 21 Ball cage [0122] 22 Legs [0123] 23 First running surfaces [0124] 24 Second running surfaces [0125] 25 Ball surface [0126] 26 Pull-out direction [0127] 27 Chamfer