TUBULAR STABILIZER BAR FOR A VEHICLE CHASSIS, AND VEHICLE CHASSIS COMPRISING THE TUBULAR STABILIZER BAR

Abstract

The present invention relates to a tubular anti-roll bar for a vehicle chassis, produced from a metal tubular body, comprising a torsion spring portion, two limbs bent off from the torsion spring portion and a bending portion, arranged between the torsion spring portion and the respective bent limb and having an inside bending radius (IB) and an outside bending radius (OB), wherein the tubular anti-roll bar has a structure with grains with a grain size distribution and an average grain size, wherein the structure has a ratio between the average grain size in the bending portion of the inside bending radius (IB) in relation to the average grain size in the torsion spring portion in the range of 73% to 77%.

Claims

1.-8. (canceled)

9. A tubular anti-roll bar for a vehicle chassis comprising: a torsion spring portion; two limbs bent off from the torsion spring portion; and a bending portion, arranged between the torsion spring portion and the respective bent limb having an inside bending radius (IB) and an outside bending radius (OB), having a structure with grains with a grain size distribution and an average grain size, wherein the structure has a ratio between the average grain size in the bending portion of the inside bending radius (IB) in relation to the average grain size in the torsion spring portion in the range of 70% to 99%.

10. The tubular anti-roll bar of claim 1, wherein the metal tubular body comprises a manganese-boron-steel composite with a carbon content in the range of 0.2% by weight to 0.42% by weight in relation to the total weight of the manganese-boron-steel composite.

11. The tubular anti-roll bar of claim 1, wherein the average grain size in the bending portion in the outside bending radius (OB) is greater than in the inside bending radius (IB).

12. The tubular anti-roll bar of claim 1, wherein the bending portion has a bending angle between the torsion spring portion and the respective bent limb in the range of 30? to 105.

13. The tubular anti-roll bar of claim 1, wherein the tubular anti-roll bar is tempered by electrical resistance heating, wherein the torsion spring portion, the two limbs bent off from the torsion spring portion and the bending portion arranged between the torsion spring portion and the respective bent limb are tempered at the same time.

14. The tubular anti-roll bar of claim 1, wherein the structure of the tubular anti-roll bar includes a martensitic structure.

15. A vehicle chassis comprising the tubular anti-roll bar of claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The tubular anti-roll bar according to the invention is explained with the aid of the drawings.

[0016] FIG. 1 shows a plan view of a tubular anti-roll bar according to the prior art in a schematic representation,

[0017] FIG. 2 shows a longitudinal section through a bending portion of a tubular anti-roll bar according to embodiments of the invention in a schematic representation,

[0018] FIG. 3 shows a cross section through a bending portion of a tubular anti-roll bar according to embodiments of the invention in a schematic representation,

[0019] FIG. 4 shows a cross section through a torsion spring portion of a tubular anti-roll bar according to embodiments of the invention in a schematic representation.

[0020] In FIG. 1, a plan view of a tubular anti-roll bar 1 having a torsion spring portion 2 and two bent limbs 3, 3, which end in end portions 5, 5 (illustrated by dashed lines), is shown in a schematic representation according to the prior art. A respective bending portion 4, 4 (demarcated by dashed lines) is shown in the region between the torsion spring portion 2 and the limbs 3, 3, which are each bent off from the torsion spring portion 2 at a respective bending angle ? (as shown by dashed lines). An inside bending radius IB and an outside bending radius OB are shown on the respective bending portion 4, 4. The torsion spring portion is shown by dashed lines according the arrangement of a section N, N at distances D, D.

[0021] A longitudinal section through a bending portion 4, 4 of the tubular anti-roll bar 1 is shown in a schematic representation in FIG. 2, with the bending angle ? and the inside bending radius IB and the outside bending radius OB. Sampling points are shown in framed squares numbered 1 to 6. Sections M-M and NN are shown in a schematic representation.

[0022] In FIG. 3, the section M-M through a bending portion 4, 4 of the tubular anti-roll bar 1 is shown in a schematic representation, with the inside bending radius IB and the outside bending radius OB and a left bending radius LB and a right bending radius RB. The respective sampling points are shown in framed squares numbered 1 to 3.

[0023] In FIG. 4, the section N-N through a torsion spring portion 2 of the tubular anti-roll bar 1 is shown in a schematic representation. Sampling points are shown in framed squares numbered 1 to 3.

EXAMPLES

1 Grain Size Determination

1.1 Test Parameters

[0024]

TABLE-US-00001 Sampling Limb radius 1 transverse Limb radius 1 longitudinal Back region Microscope Leica Aristomet Software dhs image database, module for grain size determination by PixelFerber Standard DIN/ASTM Method Circular section method

1.2 Operating Procedure

[0025] Sampling took place in the first limb radius of the left side. To this end, two tubular anti-roll bars were provided for each resistance heating method. Therefore, a transverse ground section and a longitudinal ground section could be removed in each case. As reference, a transverse ground section was moreover removed in the neutral back region. The sampling/sample preparation is described in note form below: [0026] Remove the depicted cutting points M-M, N-N (distance D, D>50 mm) with a band saw, [0027] Pre-grind the coarse cutting surface using a belt sander, which has sandpaper with grain size 80, [0028] Further wet-grind by hand with sandpaper with grain sizes 120, 220, 500, 1200. After each sandpapering, the surface of the sample should be thoroughly cleaned to avoid dirt being transferred to the next, finer sandpaper. [0029] Polish the ground surfaces with a suitable polishing cloth and 3 ?m diamond suspension. Polishing takes place until a reflective surface appears.

[0030] A martensitic structure is present in the tempered tubular anti-roll bars, and it is therefore advisable to subject the polished samples to heat treatment. This is intended to oxidize the grain boundaries and facilitate etching of the grain boundaries. Possible furnace settings may be applied as follows: [0031] Temperature: 480-550? C., [0032] Holding time: 80-100 min.

[0033] After the heat treatment, the sample may be quenched directly in water. The polished surface now has an oxide layer which is carefully removed by polishing.

[0034] PLEASE NOTE: Complete removal of the oxide layer is advisable !

[0035] When generating the grain boundaries, repeated polishing and etching may be necessary. The effective range of oxidation through heat treatment is very superficial and could be evened out by too strong polishing.

[0036] Two approved agents may be used for the etching. [0037] Bechtet-Beaujard is brought to a temperature of 60-70? ? C. The sample is etched for 15-20 min, [0038] Heating is not required with the etchant HA. The sample is also etched for 15-20 min here.

[0039] After etching, the acid is thoroughly removed from the sample using water. The surface appears copper or black, depending on the etchant. This layer is removed using ethanol and a cotton swab, applying strong pressure. Then, clean with water again, remove the water using ethanol and dry the sample in an air flow.

[0040] The sample may now be observed under the microscope. If the result is not yet satisfactory, the polishing and etching are repeated until the grain boundaries are visible.

[0041] Suitable magnification should be selected to capture images of the grain boundaries. PLEASE NOTE: In this report, a consistent magnification was selected to enable comparison of the longitudinal ground sections.

[0042] If an image is captured with the desired magnification, the grain size is determined using the circular section method of DIN EN ISO 643. This should be established manually depending on the image quality.

1.3 Summary of the Test Results in the Transverse Ground Section

[0043]

TABLE-US-00002 Electrical resistance Electrical resistance heating method 1 heating method 2 Testing point/ Average Average grain size Measurement value Measurement value Back 12.53/11.02/10.23 11.26 9.98/9.64/11.32 10.31 SR1 Inside 8.08/8.24/8.32 8.21 6.89/7.29/7.13 7.10 bending radius SR1 Outside 11.58/11.02/11.09 11.23 11.40/11.49/11.58 11.49 bending radius SR1 left 9.87/10.28/9.46 9.87 9.27/8.67/10.03 9.32 SR1 right 9.92/10.08/9.92 9.97 9.64/10.03/9.92 9.86

1.4 Comparison of the Grain Size in the Inside Bending Radius

[0044] Images were captured at 200? magnification at 3 points (c.f. FIG. 2, for example) in the region of the inside bending radius

TABLE-US-00003 Arrangement/grain size 1 2 3 ELECTRICAL 8.08 8.24 8.32 RESISTANCE HEATING METHOD 1 ELECTRICAL 6.89 7.29 7.13 RESISTANCE HEATING METHOD 2

1.5 Comparison of the Grain Size in the Outside Bending Radius

[0045] Images were captured at 500? magnification at 3 points (c.f. FIG. 2, for example) in the region of the outside bending radius

TABLE-US-00004 Arrangement/grain size 1 2 3 ELECTRICAL 11.58 11.02 11.09 RESISTANCE HEATING METHOD 1 ELECTRICAL 11.40 11.49 11.58 RESISTANCE HEATING METHOD 2

1.6 Comparison of the Grain Size in the Left/Right Transition Regions

[0046] Images were captured at 500? magnification at 3 points in each case (c.f. FIG. 2, for example) in the left and right transition region.

TABLE-US-00005 Arrangement/grain size at the measuring position 1 2 3 ELECTRICAL 9.87 10.28 9.46 RESISTANCE HEATING METHOD 1 Left ELECTRICAL 9.27 8.67 10.03 RESISTANCE HEATING METHOD 2 Left ELECTRICAL 9.92 10.08 9.92 RESISTANCE HEATING METHOD 1 Right ELECTRICAL 9.64 10.03 9.92 RESISTANCE HEATING METHOD 2 Right

1.7 Comparison of the Grain Sizes in the Back Region

[0047] Images were captured at 500? magnification at 3 points in each case (c.f. FIG. 3, for example) in the left and right back region

Example for the Positions on the Transverse Ground Section

[0048]

TABLE-US-00006 Arrangement/grain size at the measuring position 1 2 3 ELECTRICAL 12.53 11.02 10.23 RESISTANCE HEATING METHOD 1 ELECTRICAL 9.98 9.64 11.32 RESISTANCE HEATING METHOD 2

1.8 Comparison of the Grain Sizes in the Longitudinal Extent on the Inside Bending Radius

[0049] Images were captured at 500? magnification at 6 points (c.f. FIG. 2, for example) along the longitudinal ground section in the inside bending radius.

TABLE-US-00007 Arrangement/grain size at the measuring position 1 2 3 4 5 6 ELECTRICAL 9.58 8.50 8.23 8.59 9.33 9.46 RESISTANCE HEATING METHOD 1 ELECTRICAL 8.50 7.92 6.59 7.20 7.92 8.23 RESISTANCE HEATING METHOD 2

1.9 Comparison of the Grain Sizes in the Longitudinal Extent on the Outside Bending Radius

[0050] Images were captured at 500? magnification at 6 points (c.f. FIG. 2, for example) along the longitudinal ground section in the inside bending radius.

TABLE-US-00008 1 2 3 4 5 6 ELECTRICAL 10.67 10.59 10.23 11.33 10.37 10.87 RESISTANCE HEATING METHOD 1 ELECTRICAL 10.08 11.02 10.91 10.50 10.55 10.79 RESISTANCE HEATING METHOD 2

2 Result

[0051] From the test results, it is possible to make the following statements: [0052] In the back region, the tempering via the ELECTRICAL RESISTANCE HEATING METHOD 1 arrangement shows, on average, a grain refinement by a factor of ca. 1. [0053] In the inside bending radius, the tempering via the ELECTRICAL RESISTANCE HEATING METHOD 1 arrangement shows, on average, a grain refinement by a factor of ca. 1. [0054] The grain sizes in the outside bending region are comparable. [0055] The transition regions are comparable. Both have a mix of coarse and fine grains. [0056] In the longitudinal ground section of the inside bending radius, the tempering via the ELECTRICAL RESISTANCE HEATING METHOD 1 arrangement shows, in places, a grain refinement by a factor of ca. 2. [0057] The outside bending radii in the longitudinal ground section are comparable.

Commercial Applicability

[0058] Tubular anti-roll bars of the above-described type are used in the production of vehicles, in particular the chassis of motor vehicles.

LIST OF REFERENCE SIGNS

[0059] 1=Tubular anti-roll bar [0060] 2=Torsion spring portion [0061] 3, 3=Limb [0062] 4, 4=Bending portion [0063] 5,5=End portion [0064] IB=Inside bending radius [0065] OB=Outside bending radius [0066] ?=Bending angle [0067] LB=Left bending radius of a cross section [0068] RB=Right bending radius [0069] M-M=Section, schematic representation [0070] N-N=Section, schematic representation [0071] D, D=Distances of a section N-N from the bending portions 4, 4.