DE29600917U1 - Linear ball guide reinforced with regard to pressure - Google Patents

Description

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Linear ball guide reinforced with regard to compressive stress

The invention relates to a linear ball guide, in particular a linear ball guide reinforced with respect to compressive stress with four rows of ball bearings.

Linear ball guides have long been used in precision machinery and instruments. The linear ball guides on the market today can be roughly classified according to the number of rows of ball bearings into 2-row, 4-row and 6-row linear ball guides, with 4-row being the most common. The 4-row linear ball guides commonly used today can essentially be divided into three categories.

In the first category (see Fig. 15), the load directions of the adjacent rows of balls 11 are perpendicular to each other and the extension lines of the load directions of the laterally adjacent rows of balls 11, 12 cross each other on the side of the guideways facing the guide body at point A.

In the second category (see Fig. 16), the load directions of the adjacent rows of balls 13 are perpendicular to each other, but the extension lines of the load directions of the adjacent rows of balls 13, 14 on the sides cross each other on the side of the guideways facing away from the guide body at point B.

In the third category (see Fig. 17), the load directions of the upper two rows of balls 15 are the same, namely in the vertical direction, and the load directions of the lower rows of ball bearings on both sides 16 form a 120° angle with the upper rows of ball bearings and cross each other approximately between the upper rows of balls.

The conventional linear ball guides of the first and second categories have in the four horizontal and

The sliding piece 1 has the same load capacity in vertical directions, even when subjected to upward tensile force.

In general, the guide rarely has to absorb a pure upward tensile force; usually the greatest value of the upward tensile force to be absorbed is smaller than the downward compressive force: the sliding piece is mainly exposed to downward and lateral pressure.

Unfortunately, when the load from above is equal to that from the side, the allowable load of the linear ball guides of these two categories is only 70% of the allowable side load.

Linear ball guides of the third category have very good load capacity under downward pressure and can also withstand some lateral pressure well; however, due to the lower rigidity under lateral stress, the accuracy of the position of the slider becomes poor, and the guide rail 7 and the slider 1 of this category require at least two processing axes during polishing, which not only makes the manufacturing machine more complicated, but also makes the correct positioning of the two axes quite difficult.

Fig. 17 shows a conventional linear ball guide of the third category. Although this has a very good load-bearing capacity under pure downward pressure, the lateral rigidity is inadequate and cannot satisfactorily meet the requirements of the machine under heavy lateral loads, and polishing is relatively difficult to carry out when manufacturing the guide of the third category. Fig. 18 shows that 3 machining axes are needed to polish the guideways; due to the two grooves of the ball rows u at the top and the two lateral grooves of the ball rows s, adjustment at the corresponding point is not easy and often leads to the

The load direction of the guide balls after assembly does not point in the originally planned directions.

The aim of the invention is to create a linear ball guide which is reinforced with regard to compressive stress and whose load directions for the upper two rows of balls form an angle of approximately 60°, while the extension lines of the load directions cross each other under the sliding piece.

The load directions of the two lower lateral rows of ball bearings form an angle of around 30° with the horizontal and an angle of around 90° with the load directions of the upper rows of ball bearings. Initial tests have shown that with pure pressure loading from above, the load capacity increases by around 22% compared to guides in the first and second categories and the rigidity increases by around 40%. With simultaneous loading from above and the sides, and when the load direction and the vertical form an angle between 0° and 80°, the load capacity is increased by approx.

3.7% to 22%. When pulling upwards, the guide according to the invention is comparable to a guide of the third category, i.e. the load capacity is significantly lower than that of the guides of the first and second categories.

Another object of the invention is to provide a linear ball guide as described above, reinforced with respect to pressure stress, in which the rotation system of the balls can be improved. Projecting arcuate running surfaces are arranged on end plates and guide segments, and a circular counterbore is arranged at both ends of the rotation openings and the ball grooves of the slider, whereby when the end plates and the guide segments are mounted on the slider, the arcuate running surfaces on the end plates and the guide segments engage precisely in the circular counterbores of the slider. Because the rotation openings and the circular counterbores can be manufactured precisely during production, very precise positioning of end plates and guide segments can be achieved by means of these circular counterbores.

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can be achieved and the rotation of the balls can be made easier. In order to facilitate the entry of the balls of the ball groove into the connecting piece, which connects the ball groove and the rotation channel , projections of the end plates on the connecting piece side can be introduced into the sliding piece during assembly so that the balls can run easily at the transition between the ball grooves and the connecting piece.

The present invention is explained in more detail below using exemplary embodiments in conjunction with the drawings:

Fig. 1 is a schematic representation of a linear ball guide according to an embodiment of the invention; 15

Fig. 2 shows a comparison of the load capacity of linear ball guides of the invention and of 4-row linear ball guides of the first and second categories;

Fig. 3 is a schematic representation of the polished guideways according to an embodiment of the invention;

Fig. 4 is a perspective view of an embodiment of the invention;
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Fig. 5 is a perspective view of the slider according to an embodiment of the invention;

Fig. 6 is a perspective view of an end plate according to an embodiment of the invention;

Fig. 7 is a perspective view of a guide segment according to an embodiment of the invention;

Fig. 8 is a perspective view of the top of a ball housing according to an embodiment of the invention;

Fig. 9 is a perspective view of a side part of a

Ball housing according to an embodiment of the invention;

Fig. 10 is a front view of a slider according to an embodiment of the invention;
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Fig. 11 is a front view of a slider with housing top and housing sides of the ball housing according to an embodiment of the invention;

Fig. 12 is a perspective view of an end plate with inserted guide segments according to an embodiment of the invention;

Fig. 13 is a perspective view of the slider with inserted guide segments according to an embodiment of the invention;

Fig. 14 is a partial view of the slider with the end plate inserted according to an embodiment of the invention; 20

Fig. 15 is a schematic diagram of a conventional linear ball guide of the first category;

Fig. 16 is a schematic diagram of a conventional linear ball guide of the second category;

Fig. 17 is a schematic diagram of a conventional third category linear ball guide;

Fig. 18 is a schematic diagram of the polished guideways of a conventional third-category linear ball guide;

Fig. 19A is a schematic representation of the load when pressure is applied directly from above to the slider according to an embodiment of the invention;

Fig. 19 B is a square diagram of the load at

direct pressure from above on the slider of conventional linear ball guides of the first and second categories.

Fig. 1 and Fig. 4 show a 4-row linear ball guide according to the invention which is reinforced with respect to compressive stress and which has: a guide rail 7, a sliding piece 1, two end plates 2, eight guide segments 3, a housing upper part 4, two housing side parts 5, two covers 8 and several balls. The profile of the guide rail 7 is narrow in the middle area, the underside of the guide rail is flat; on the upper side of the guide rail, which protrudes on both sides, there are arched ball grooves above and below, the radius of which is slightly larger than the radius of the balls. The loading directions of the two rows of balls 17 on the upper side of the guide rail 7 form an angle Ol of approximately 60°, the extension lines of the loading directions intersect below the guide rail at point C. The 0 loading directions of the two lower lateral rows of balls 18 form an angle 03 of approximately 30° with the horizontal and an angle 02 of approximately 9 0° with the loading directions of the upper rows of balls 17.

If pure pressure is exerted on the slider 1 from above, only the two rows of balls 17 on the top of the guide rail 7 are loaded, because the loading directions of the balls and the pressure direction form half the angle 01, namely about 30° (see Fig. 19 A). Therefore, according to the sine law, the permissible load in the running surface for the entire guide is 1.73 times the permissible vertical load of a row of balls. Compared to conventional guides of the first and second categories (see Fig. 19 B), the load capacity of the device according to the invention is about 22% higher; if the loading direction and the vertical pressure load form an angle of 30°, the permissible load capacity is about 1.074 times that of a row of balls due to three loadable rows of balls; compared to conventional guides of the

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In the first and second categories, the load capacity is approximately 4% higher (if geometric factors are taken into account, the load capacity can be increased by a further factor, i.e. by including a shape coefficient. The shape coefficient shows the comparative value of the load of the curve radius Ra of the ball grooves and the ball diameter Dw and is Ra/Dw).

For permissible load capacities at other angles, see Fig. 2. The solid lines show the load capacity range of the present invention, the dashed lines show the load capacity range of conventional guides of the first and second categories, the x-axis indicates the horizontal, the y-axis the vertical. When loaded from above and sides and within an angle of 0° to 80° formed by the loading direction with the vertical, the load capacity is increased by approximately 3.7% to 22%.

With pure pressure from above, the stiffness of the guide is related to various factors: ball diameter, number of loaded balls, preload, load direction of the balls, material and shape coefficient. If only the load direction of the balls is examined, the stiffness is increased by 40% compared to guides in the first and second categories. A disadvantage of conventional linear ball guides is their low stiffness, and with improved stiffness, the use of linear ball guides could be increased, especially in industry.

Fig. 3 is a schematic representation of the profile of a polished guide rail according to the invention; it requires only two machining axes, the correct positioning of the axes can be controlled more precisely, and thus costs can be reduced.

See Fig. 4, 9, 10 and 11. Fig. 4 shows a perspective view of a guide according to the invention. In order to improve the rotation system of the balls, the invention offers a new design for the rotation system: End plates 2

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(Fig. 6) and guide segments 3

(Fig. 7) each have an arcuate wall 2a and 3a on the top; on the slider 1 (Fig. 5), circular recesses Ie and If are machined at both ends of the rotation channels Id and the corresponding ball grooves Ic, whereby when assembling the end plates 2, guide segments 3 and slider 1, the arcuate walls 2a and 3a on the end plates 2 and guide segments 3 engage precisely in the corresponding circular recesses Ie and If of the slider 1. Because the rotation channels Id and the circular recesses Ie and If can be precisely manufactured during manufacture and the end plates 2 and the guide segments 3 are positioned by means of the circular openings Ie and If, the guide can be assembled precisely and the rotation of the balls can be improved (see Fig. 12, 17 and 18).

In order to improve the entry of the balls from the ball groove into the connecting piece 2g (see Fig. 6), the projection 2h of the end plate 2 is introduced into the sliding piece 1 during assembly, and thus the balls can easily rotate in the ball groove 1c and connection 2g. Because the projection 2h must be sufficiently thick so as not to break, the middle area of the guide rail 7 has a recess 7c (see Fig. 1 and 8), which allows the projection 2h to be made thicker.

The precise matching of the circular opening Ie of the rotation channels Id and the arcuate wall 2a allows precise positioning; the loose connection of the circular counterbore If of the ball groove Ic and the projection 2h allows convenient assembly of the end plates 2 and the slider 1. Guide segments 3 (Fig. 7 ) and slider 1 (Fig. 5) are positioned by the arcuate wall 3a, and in order to prevent guide segments 3 from falling off the end plate 2, there are circular counterbores 2f (see Fig. 5) on the end plates 2, into which the circular base 3b of the guide segments 3 fits precisely, whereby end plates 2

and guide segments 3 can be fastened in the correct position.

In order to prevent the balls from falling out of the ball grooves of the slider when the slider 1 and the guide rail 7 are disassembled, the linear ball guide of the present invention has a housing upper part 4 (see Fig. 8) and two housing side parts 5 (see Fig. 9). The housing upper part 4 is fixed by means of screws through the two screw holes 4a and the screw holes Ig of the slider (see Fig. 10). The two beveled side surfaces 4b prevent the balls of the upper row 17 from falling out. The two housing side parts 5 are also fastened by means of screws through the screw holes 5c on the side parts and the screw holes lh on the slider 1 (see Fig. 10). The curved edge 5a on the housing side parts 5 prevents the balls from falling down. After the guide has been installed, the projections 5b engage exactly between the projections 2h and the projections 2b of the end plates 2 (see Fig. 6) in order to increase the stability of the housing side parts 5. Fig. 11 shows that the slanted wedge-shaped projections 2b of the housing side parts can be omitted and that recesses can be provided in the housing side parts instead.

See Fig. 4. To prevent foreign objects from entering the rotation system of the guide, there are covers 8 on the end plates 2. To improve the sliding ability of the guide, a lubricating device 9 is fixed on the cover 8 by means of a screw hole 2d on the end plate 2 (see Fig. 6) and there is a lubricating channel 2e on the end plates 2. The cover 8 is attached to the slider 1 by means of a screw 10 through a hole in the cover 8 and hole 2c on the end plate 2 in a threaded hole 1b.

Claims (3)

• ·* I 10 10 Protection claims 1. Reinforced linear ball guide with four rows of balls, which has the following characteristics: a guide rail, a sliding piece, two end plates, eight guide segments, a housing upper part, two housing side parts, two covers and several balls, characterized in that the profile of the guide rail is narrow in the middle area and the underside of the guide rail is flat; that on the upper side of the guide rail, which projects on both sides, there are curved ball grooves at the top and bottom, the radius of which is slightly larger than the radius of the balls; that the loading directions of the two upper ball grooves form an angle of approximately 60°, and the loading directions of the upper and lower ball grooves on one side each form an angle of approximately 90°;
that there are four rotation channels and four ball grooves on the sliding piece; there is a circular countersink on each of the rotation channels and the ball grooves on both sides, for which there is a corresponding curved wall on the end plates and the guide segments; there are four semicircular connecting pieces on the end plates through which the balls can run from the ball grooves into the rotation channels; these semicircular connections have a curved edge, although they do not necessarily have to be flat; end plates and connecting pieces of the rotation channels have curved walls which engage in the circular openings of the sliding piece and fix the exact position; the connections of the end plates near the ball grooves have projections which engage in the sliding piece when the end plates and sliding piece are put together; each guide segment has a circular base and corresponding circular countersunk holes are provided on the end plates, whereby the respective base of the guide segments can engage exactly in the countersunk holes of the end plates; on each 11 11 There are two curved walls on the guide segment, each of which engages in the rotation channels and the circular openings at both ends of the ball grooves of the slider; There are housing side parts on both lower sides of the slider, the curved border of which prevents the balls from falling out of the slider when the slider and the guide rail are separated; There are inclined conical projections on both ends of the housing side parts, which engage in the end plates on both sides of the slider, so that the stability of the ball housing is increased; The housing side parts are attached to the slider by means of several screws, and there are corresponding screw holes on the housing side parts and the slider; The housing top part is attached to the slider in the middle at the bottom, the two bevelled sides of which prevent the balls of the upper of the two rows from falling out; the upper part of the housing is also fixed to the sliding piece with several screws, there are corresponding screw holes on the upper part of the housing and the sliding piece; and a cover is attached to both outer sides of the end plates. 2. A compression-strengthened linear ball guide according to claim 1, characterized in that the semicircular connecting parts on the end plates are simple semicircular passages. 3. Linear ball guide reinforced with respect to compressive stress according to claim 1, characterized in that the oblique wedge-shaped projections of the housing side parts are omitted and the housing side parts are manufactured by punching.