Profiled bar, and vehicle spring produced therefrom

Abstract

A vehicle spring for a spring system, includes a spring body (20) and is produced, in particular rolled, from a profiled bar (1) made of a flat steel bar, in particular spring steel, in a hot deformation process. The profiled bar (1) or the spring body (20) has at least one material recess (6) which is provided over the length of the profiled bar or the spring body at least in some regions. The cross-sectional shape of the profiled bar (1) can be the same over the entire length of the profiled bar, whereas the cross-sectional shape in the spring body (20) can vary over the length of the spring body.

Claims

1. A method for producing a vehicle spring comprising the steps of providing a profiled bar having a longitudinal axis, a transverse axis (z) that runs crosswise to the longitudinal axis and that corresponds to the neutral fiber, and an axis (v) that runs at right angles to the transverse axis (z) from the bottom to the top of the profiled bar, the profiled bar also having a planar cross section perpendicular to the longitudinal axis thereof, the planar cross section defining a trapezoid over the entire length of the profiled bar, the trapezoid having a top side, a bottom side, a first narrow side and a second narrow side, each side defining a flat segment, each of the said first and second narrow sides extending between the top and bottom sides, a portion of one of the top side and the bottom side and the neutral fiber extending in parallel to one another, the first narrow side defining a first material recess and the second narrow side defining a second material recess, each material recess having a depth, the first material recess and the second material recess extending over the entire length of the profiled bar; heating the profiled bar to a temperature of approximately 800 to 1200 C.; rolling the profiled bar to change the depth and the width of the first material recess and the second material recess over the length of the profiled bar; modifying the first longitudinal end portion for direct or indirect attachment to a vehicle chassis; and modifying the second longitudinal end portion for direct or indirect attachment to a vehicle chassis.

2. The method of claim 1 wherein the first material recess overlaps the transverse axis (z) of the elongated profiled bar.

3. The method of claim 1 wherein the flat segment of the first narrow side and the flat segment of the second narrow side run continuously from a location below the neutral fiber to a location above the neutral fiber.

4. The method of claim 1 wherein the flat segment of the first narrow side and the flat segment of the second narrow side extend from a location adjacent the bottom side to a location adjacent the top side.

5. The method of claim 1 wherein the flat segment of the bottom side extends over the entire length of the elongated spring body.

6. The method of claim 1 wherein the cross-section of the elongated spring body is symmetric to the axis (V).

7. The method of claim 1 wherein the step of modifying the first longitudinal end portion or the step of modifying the second longitudinal end portion includes rolling at least one end portion to form a lug.

8. The method of claim 1 wherein the vehicle spring is a parabolic spring with the elongated spring body having a parabolic portion.

9. The method of claim 1 wherein the vehicle spring is a parabolic spring with the elongated spring body having a parabolic portion within which the first material recess is positioned.

10. The method of claim 1, further including the step of cutting the profiled bar to a length that presents the first longitudinal end portion and the second longitudinal end portion for direct or indirect attachment to the vehicle chassis.

11. The method of claim 10 wherein the step of cutting the profiled bar precedes the step of heating the profiled bar.

12. The method of claim 1, wherein the profiled bar is comprised of EN 10092, BS 970-2, EN10089 or EN 10083 spring steel.

Description

(1) Preferred and advantageous embodiments of the invention follow from the description below with reference to the attached drawings, in which preferred embodiments are depicted.

(2) Here:

(3) FIGS. 1 to 5 show known cross-sectional shapes of profiled bars for vehicle springs that are made of hot-deformable steel;

(4) FIGS. 6 to 11 show embodiments of profiled bars for a vehicle spring according to the invention in cross-section;

(5) FIG. 12 shows a first embodiment of a bar spring according to the invention with a rolled lug;

(6) FIG. 13 shows a second embodiment of a bar spring according to the invention with a lug introduced into the spring body; and

(7) FIG. 14 shows an embodiment of a parabolic spring according to the invention.

(8) In FIGS. 1 to 5, cross-sectional shapes of profiled bars 1 that are made of flat-bar steel and that are known to date are depicted, namely a natural-edged profile (FIG. 1), a profile with semi-circular narrow sides (FIG. 2), a profile with rounded edges (FIG. 3) and a basket-arch profile (British Standard) (FIG. 4). FIG. 5 shows in cross-section a hot-deformable profiled bar 1 for finned leaf springs.

(9) The hot-deformable profiled bars 1 depicted in FIGS. 1 to 3 correspond to DIN EN 10092-1. FIG. 4 shows a hot-deformable profiled bar 1 that is made of flat-bar steel with a cross-sectional shape according to British Standard BS 970-2:1988 b. The hot-deformable profiled bar 1 depicted in FIG. 5 corresponds to DIN EN 10092-2. The profiled bars 1 have a top 2, a bottom 3 and two narrow sides 4, 5. Furthermore, in FIGS. 1 to 4, the width b, the height h, and the transverse axis z (this also corresponds to the neutral fiber defined with respect to the bending stress) of the profiled bars 1 as well as radii of curvature r are indicated. According to FIGS. 1 to 4, the profiled bars 1 have no material recess over their length. Also, the profiled bar 1 depicted in FIG. 5 has no material recess over its length, since in the finned area, all material is present, and the material is also not displaced in the longitudinal direction.

(10) In contrast to the known profiled bars 1, a profiled bar 1 according to the invention has at least one material recess 6. Thus, the weight of a hot-rolled vehicle spring can be reduced by the starting material, whereby the force absorption and the springy action of the vehicle spring are not impaired.

(11) By way of example, a profiled bar 1 (in particular that is made of flat-bar steel) is depicted in FIG. 6, which bar (starting from a known profiled bar 1 according to FIG. 3) in its two narrow sides 3, 4 in each case has a material recess 6 with a width B and a depth T. The material that is otherwise present on the narrow sides 4, 5 (as in, e.g., FIG. 3) is displaced in the profiled bar 1 according to FIG. 6 along its longitudinal direction and is no longer present in the profiled bar 1. In the embodiment depicted in FIG. 6 and in FIG. 7, the profiled bar 1 has an I-profile with a material recess 6 that is arc-shaped in cross-section. The depth T of the material recess 6 continuously increases first over its width B and then continuously decreases again.

(12) A difference between the embodiments depicted in FIGS. 6 and 7 is that the bottom 3 of the profiled bar 1 according to FIG. 7 is less wide than its top 2.

(13) In the embodiment depicted in FIG. 8, the profiled bar 1 has a U-profile that is open downward with a material recess 6 that is arc-shaped in cross-section, i.e., the material recess 6 is provided in the bottom 3.

(14) In the embodiment depicted in FIG. 9, the profiled bar 1 has an essentially trapezoidal cross-sectional shape with rounded edges. The material recess 6 runs from the upper area of the profiled bar 1 in a straight line to the bottom 3, whereby the depth T of the material recess 6 continuously increases over its width B. The material recess 6 is provided in two narrow sides 4, 5 as well as in the bottom 3.

(15) In the embodiment depicted in FIG. 10, the profiled bar 1 has a T-profile with a material recess 6 that is wave-shaped in cross-section. Also, in this embodiment, the depth T of the material recess 6 increases continuously over its width in the direction toward the bottom 3.

(16) In the embodiment depicted in FIG. 11, material recesses 6 are provided in the two narrow sides 4, 5, which recesses are shaped similar to those in FIG. 9. Moreover, a material recess 6 is provided in the bottom 3, which recess is shaped similar to that in FIG. 8.

(17) A feature that all depicted embodiments of profiled bars 1 according to the invention have in common is that the profiled bar 1 has a transverse axis z that runs crosswise to its longitudinal axis (the latter can correspond to the neutral fiber) as well as an axis V that runs at right angles to the transverse axis z and that the cross-sectional shape is symmetric to the axis V. Furthermore, all embodiments shown have in common the fact that the material recess 6, relative to an imaginary cross-sectional surface that is formed by the width b and the height h of the profiled bar 1 (depicted in hatching in FIGS. 6 to 11), extends into the profiled bar 1. Relative to the imaginary cross-sectional surface, formed by the width b and the height h of the profiled bar 1, edge areas can be defined by the height h and the width b in the area of the corners (these can also be rounded corners), as well as central areas. Within the framework of the invention, the material recess 6 is a depression of width b and/or height h of the profiled bar 1 in at least one central area. In particular, it can be provided that at least one material recess 6 runs in the area and in particular along the transverse axis z and/or in the area and in particular along the axis (V).

(18) In the depicted profiled bars 1, the material recess 6 extends over the entire length of the profiled bar 1, whereby the cross-sectional shape of the profiled bar 1 does not change over its entire length.

(19) If a vehicle spring with a spring body 20 can be produced from the profiled bar 1, one or more features of the material recess 6 contained in the profiled bar 1 can also be present in the spring body 20. Also, the shape of the material recess in the spring body 20 (for example, width B of the material recess 6 that continuously or intermittently increases and/or decreases over the height of the spring body 20 or, for example, depth T of the material recess 6 that continuously or intermittently increases and/or decreases over the width B of the material recess 6) can already be present in the profiled bar 1. In the finished vehicle spring, mixed shapes of possible material recesses 6 or cross-sectional shapes can also be present. In the finished vehicle spring, the material recess 6 cannot run over the entire length of the spring body 20, whereby the cross-sectional shape of the material recess 6 in the spring body can change.

(20) In FIG. 12, an embodiment of a bar spring according to the invention with a spring body 20 that is made of a hot-deformed profiled bar 1 is depicted. The bar spring has a rolled lug 8 on one of its longitudinal ends 7. The other longitudinal end 9 is angled and has two boreholes 10, which are used for mounting, e.g., an air spring bellows.

(21) The spring body 20 has a through material recess 6 over a major part of its length on the two narrow sides 4, 5 and is vigorously rolled to a varying extent over its length. Because of the rolling, the width B of the material recess 6 changes over the length of the spring body 20. The depth T of the material recess 6 continuously increases and decreases again in this embodiment. In the embodiment depicted in FIG. 12, the spring body 20 has an I-profile, whereby the material recess 6 over the length of the spring body 20 has a depth T that is consistent for the most part.

(22) In FIG. 13, another embodiment of a bar spring according to the invention that consists of a hot-deformed profiled bar 1 is depicted. On one of its longitudinal ends 7, the bar spring has a molded-on lug 11. The other longitudinal end 9 is angled.

(23) The spring body 20 has a through material recess 6 over its entire length on the two narrow sides 4, 5, and is vigorously rolled to a varying extent over its length. Because of the rolling, the width B of the material recess 6 changes over the length of the spring body 20. The depth T of the material recess 6 increases and decreases to a varying extent in this embodiment. In the area of the longitudinal end 7, in which area the lug 11 is molded-on, the spring body 20 has an I-shaped profile according to the profiled bar 1 of FIG. 6. Its cross-sectional shape changes over the length of the spring body 20; e.g., in the central section of the profiled bar 1, the depth T of the material recess 6 essentially increases and decreases in stages.

(24) In FIG. 14, an embodiment of a parabolic spring according to the invention that consists of a hot-deformed profiled bar 1 is depicted. The parabolic spring has a rolled lug 8 on both ends. The spring body 20 has an I-profile viewed in cross-section, whereby the width of the material recess 6 over a portion of the length of the spring body 20 increases or decreases and remains the same over a part of the length of the spring body 20.

(25) In the FIGS. 12 to 14 (as also in particular in FIGS. 6 and 7), the spring body 20 (or profiled bar 1) has a neutral fiber, whereby the material recess 6 is a depression of width b of the profiled bar 1 over its height h in the area of and along the neutral fiber. This preferred embodiment can also hold true in the case of cross-sectional shapes that are not depicted.

(26) In summary, an embodiment of the invention can be depicted as follows:

(27) A vehicle spring for a spring system with a spring body 20 is produced in a hot-deformed manner, in particular rolled, from a profiled bar 1 that is made of flat-bar steel, in particular spring steel. The profiled bar 1 or the spring body 20 has at least one material recess 6, which is provided at least in some places over its length. The cross-sectional shape of the profiled bar 1 can be the same over its entire length; conversely, the cross-sectional shape in the spring body 20 can change over its length.