MXPA96002573A - Tubes for the manufacture of stabilizers and the manufacture of stabilizers from such tu - Google Patents

Abstract

The present invention relates to the use of a steel alloy for tubes for the manufacture of stabilizers for motor vehicles, a stabilizer from such a steel alloy as well as the processes for the manufacture of stabilizers. From the requirements of the mechanical properties, where should be the resistance and the traction of Rm 1100 N / mmýa 1600 N / mmý, and the limits of expansion 0.2% Rpo, 2 900 N / mmýa 1300 N / mmýy the dilation of A5 break between 6% and 15% as well as for the economic manufacture of stabilizers is carried out the use of the steel alloy for tubes for the production of stabilizers, which consists of percent by weight of carbon (C) 0.18% to 0.30 Silicon (Si) 0.10% to 0.50%; Manganese (Mn) 1.10% to 1.80%; Phosphorus (P) max. 0.025%; Sulfur (S) max. 0.025%, Titanium (Ti) 0.020% to 0.050%, Boron (B) 0.0005% to 0.005%, Aluminum 0.010% to 0.050%, the rest iron including pollutants conditioned from the smelting. The proposed initial material satisfies the requirements of the mechanical properties. A part is characterized by a good moldability a simple improvement and its tenacity behavior. Since the material is weldable, it can also be used in the use for seamless pipes also for the production of welded longitudinal seam pipes, which for the intended purpose of use are also suitable as an initial product for the stabilizers

Description

TUBES FOR THE MANUFACTURE OF STABILIZERS AND THE MANUFACTURE OF STABILIZERS FROM SUCH PIPES FIELD OF THE INVENTION The present invention relates to the use of an alea¬ steel for tubes for the manufacture of stabilizers for motor vehicles, a stabilizer from such steel alloy as well as the procedures for the manufacture of the stabilizers. BACKGROUND OF THE INVENTION The stabilizers are components that are used in the automotive technique to reduce the inclination of the body curve and to influence the driving behavior itself, for example for the reduction of overconduction. These make it more rigid with a one-sided load to the muelleo, for example when happening on obstacles in a single side. The stabilizers are configured primarily as torsion bars that are placed in the main portion of the vehicle in a direction transverse to the direction of travel of the vehicle and which are inserted through a U-shaped arm in the wheel supports. For stabilization the strength of resistance of the material against the rotation is used. The ends of the stabilizer are in each case rigidly connected to one end of the shaft and function as lever arms. In the event that the structure of the vehicle when moving along a curve tilts to one side due to the centrifugal force, then the wheel inside the curve, muellea with more intensity than the outside. The stabilizer twists with this and presents due to its spring force an opposition to the lateral inclination. Stabilizers of the common type are manufactured to date mainly from full bars. There are in straight and folded presentations. Thus, for example, WO 93/18189 describes the production of cut-off bars, that is to say, rotational stabilizers from high-strength steels. Here the introduction of steel with a course oriented to the attached structure takes place. The transformation is carried out either under hot conditions under a recrystallization temperature or under a cold temperature of 149 ° C. The steels described therein have an elongation limit Re of at least 620 N / mm2 and a resistance to Rm traction of at least 827 N / mm2 These have a carbon content of 0.3% to 1%, manganese of 2% to 2.5% and up to 0.35% of vanadium The bars used for the manufacture of stabilizers are molded in The tendency is to produce the stabilizers from tubes, based on the reduction of weight, the advantage is that with a tube, a more convenient behavior of the moment of resistance to torsion in relation to the mass of the In comparison with the complete bar, in the optimum ratio for the torsion of the thickness of the wall in relation to the diameter of the tube, the materials of use must have retaining the outer diameter proportio The elongation limit and the tensile strength multiplied by a factor of approximately 1.4 are used or used in the construction of the vehicles. In addition, to achieve a long-term exchange rigidity, the surface quality of the outer and inner areas of the tubes used is of the utmost importance. The best surface quality is presented by welded longitudinal seam pipes from rolled steel bands. This prevents the defects that occur in seamless pipes as pleats. The steels used for a long time for tubes for the manufacture of stabilizers have a high carbon content and partly have a very low toughness. The low tenacity of the steels occurs especially in the seamless tubes, preferably due to the lower surface quality in a negative way on the resistance to prolonged change. To achieve a greater tenacity with the required resistance, quality improvement procedures are necessary with high temperatures of approximately 600 ° C. Through the high temperatures of origin it is, nevertheless necessary, that the stabilizers during the original process to avoid the deformation are tensed in special devices. This expense, however, leads to an increase in production costs. Therefore most of the steels used so far are difficult to weld. Due to the previous one, the use of longitudinal ribbed welded pipes is difficult but completely impossible, although this is desirable in view of the best surface quality. DESCRIPTION PE THE INVENTION The invention therefore presents the objective of providing a steel-alloy for the tubes, which in their mechanical properties presents the high requirements for the manufacture of stabilizers. Additionally the invention seeks an economical manufacture of qualitative high value stabilizers from such tubes. The technical part of the alloy of this objective is solved through the use of the alloy provided in claim 1. An advantageous configuration for the use of the obtained alloy is indicated in claim 2.

The invention claims here the recognition, that for the manufacture of stabilizers from tubes with high requirement of mechanical properties, it is necessary an initial material, which presents according to the original temperature, tensile strength Rm of 1100 to 1600 N / mm2, expansion limits of 0.2% Rpo'2 from 900 to 1300 N / mm2 and an A5 rupture expansion from 6 to 15%. The essential advantage of the steel alloy of the present invention is that the proposed alloy is produced in opposition to the use of the known alloys, from which the stabilizers are manufactured, which reach the values of resistance to the traction, limit of elongation and expansion of rupture and that through it in additional form only with the use of a single alloy it is possible to cover a wide bandwidth of the mechanical characteristics required. The components of the alloy have been determined for this individually. Although it is a mild carbon-poor steel, the carbon portion guarantees sufficient strength and hardness. The silicon portion determines the tensile strength and the elongation limit, where the tenacity properties are affected only modestly. Manganese increases the strength of the steel alloy in the same way, with which the rupture dilation is reduced insignificantly. Due to the above, manganese has a convenient effect on weldability. In conjunction with the carbon portion, it has an effect of improving the welding resistance. The titanium portion is mainly used for stabilization against intercrystalline corrosion. Boron improves the hardness of course and increases the strength of the core. Even the addition of aluminum supports fine grain formation. Therefore, good moldability and weldability are obtained. This presents the advantage that, apart from the use of seamless tubes, it is also possible to use the most suitable longitudinal seam welded tubes for the intended purpose of use. It should also be mentioned that the steel alloy of the present invention has, in comparison with the known steels, better properties in relation to the toughness, which makes possible an increase in the simplest quality. For example, it is possible to work with lower tempering temperatures. The steel alloy of the present invention is economical. Tubes of such steel alloy can be obtained in previously available facilities for the manufacture of complete material stabilizers without problems. The breeding facilities are here previously available. For production lines of new installation there is in fact a reduction in the expense, since the tempering executed after the hardening can be carried out at temperatures lower than those common up to now. Due to this, tension devices are not required that must avoid deformation in the tempering process. The stabilizers according to claim 3 have a lower weight as opposed to the known stabilizers of complete material. The strong loads in the use in the vehicles resist these stabilizers reliably. A solution of the portion of the method of the objective of this invention is observed at the points of importance of claim 4. Here it is possible to obtain seamless tubes as welded tubes with longitudinal seam. These lay down normally. This is carried out at a temperature just below point A J with an immediate cooling in a calm atmosphere. The annealing treatment is used, to avoid a coarse grain structure. This is especially advantageous in the longitudinal seam welding tubes, since a coarse grain structure can be present here. Technically transformed stabilizers are then manufactured from the tubes treated in this manner with the common procedures. A hardening of the stabilizers with water is included here. Hardening with water is preferably carried out on the tool itself, so that an additional take of the stabilizers for the purpose of hardening is avoided. In certain cases, an air bake can be carried out at a temperature between 200 ° C and 400 ° C, as contemplated in claim 5. The martensite structure that is produced during the hardening is partly very fragile. Therefore the stabilizers are generally tempered after hardening. .A special advantage is a temperature of approximately 250 ° C. Through the diffusion of the carbon atoms the deformation of the martensite is reduced. The friability is reduced without altering the hardness in an essential way. An extension of the stabilizers in the temper to avoid deformation is not necessary in this field of tempering temperature. If necessary, the ends of the stabilizers are stressed (claim 6). A cooling procedure is attached here. This is preferably carried out with water at temperatures above 800 ° C. Extremely advantageous, a hardening by cooling above a temperature of 920 ° C has been determined. In the case of bent stabilizers, unimproved tubes can also be used, as contemplated in claim 7. The bending is performed at a temperature above the transformation temperature, point AC3 in the iron-carbon diagram. After the bending procedure, the hardening is performed by cooling in the tool. A subsequent alignment is no longer necessary. According to the points of importance of claim 8, it is advantageous to heat the stabilizers after hardening at a temperature below the transformation temperature. The tempering temperature should therefore not exceed 350 ° C. An additional solution of the portion of the processes of the present invention as regards the object is contained in claim 9. According to it the tubes produced from the alloy of the present invention are improved, and in fact before the process of molding to form the stabilizers. An improvement after bending can be avoided. This procedure is especially pragmatic and economical.

The improvement of the tubes includes the double stage of hardening and tempering. The tube will thereby lose a great strength and a high elongation limit as well as a great tenacity before the bending procedure. Hardening consists of heating up to a hardening temperature, holding and cooling. Then it is heated again until tempering and then cooled or allowed to cool slowly. • * . If necessary, an annealing without expansion can be carried out after bending of the tubes in stabilizers, as foreseen in claim 10.

Here one can avoid transformations of structures or own tensions. Preferably, this annealing process is limited to the field of the stabilizer fold. The annealing temperature is selected in such a way that the improvement resistance of the stabilizer is not reduced. A manufacturing line for the production of stabilizers from welded tubes as well as a manufacturing line for the production of stabilizers from seamless tubes according to the methods of the present invention has been technically generalized and is depicted in the Figures 1 and 2 annexes. In relation to Figure 1 it is indicated that with the welded tubes a reduction of elongation dependent on their diameter is not necessary. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (10)

1. The use of a steel alloy for tubes for the manufacture of stabilizers for motor vehicles, especially rotation stabilizers, characterized in that it comprises in weight percent of: carbon (C) 0.18% to 0.30% silicon (Si) 0.10% to 0.50% Manganese (Mn) 1.10% to 1.80% Phosphorus (P) max. 0.025% Sulfur (S) max. 0.025% Titanium (Ti) 0.020% to 0.050% Boron (B) 0.0005% to 0.005% Aluminum 0.010% to 0.050% the rest iron including pollutants conditioned of the foundry.

2. The use of a steel alloy according to claim 1, characterized in that it consists of weight percent of: carbon (C) 0.21% to 0.26% silicon (Si) 0.15% to 0.35% Manganese (Mn) 1.20% to 1.40 % 'Phosphorus (P) max. 0.025% Sulfur (S) max. 0.025% Titanium (Ti) 0.020% to 0.040% Boron (B) 0.0020% to 0.0040% Aluminum 0.020% to 0.035% the rest iron including pollutants conditioned of the foundry.

3. Stabilizers from the steel alloy according to claim 1 or 2.

4. A process for the production of stabilizers from molded or welded tubes according to claim 1 or 2, characterized in that it consists of the following measures: a) normal annealing of the tubes; b) manufacture of the stabilizers; c) Hardening with water of the stabilizers, which is carried out especially in the tool.

5. A process according to claim 4, characterized in that an air tempering is carried out at a temperature between 200 ° C and 400 ° C.

6. A method according to one of claims 4 or 5, characterized in that the ends of the stabilizers are upset and cooled with water at temperatures above 800 ° C, especially at 920 ° C.

7. A process for the manufacture of bent stabilizers from unimproved tubes according to one of claims 1 or 2, characterized in that the bending is carried out above the point AC3 and after the bending operation the cooling is carried out in the tool.

8. A method according to claim 7, characterized in that tempering is carried out with a temperature of up to 350 ° C.

9. A process for the manufacture of bent stabilizers from tubes according to one of claims 1 or 2, characterized in that an improvement of the tubes is then carried out and these are then bent to form the stabilizers.

10. A method according to claim 9, characterized in that, after bending, stress-free annealing is carried out, preferably in the fold field. SUMMARY OF THE INVENTION The present invention relates to the use of a steel alloy for tubes for the manufacture of stabilizers for motor vehicles, a stabilizer from such a steel alloy as well as the processes for the manufacture of stabilizers. From the requirements of the mechanical properties, where the resistance and the traction must be from Rm 1100 N / mm2 to 1600 N / mm2, and the expansion limits 0.2% RpQ 2 900 N / mm2 to 1300 N / pTm2 and the Breaking dilation Ag between 6% and 15% as well as for the economic manufacture of stabilizers is carried out the use of steel alloy for tubes for the production of stabilizers, consisting of percent by weight of carbon (C) 0.18 % to 0.30% silicon (Si) 0.10% at 0.50% Manganese (Mn) 1.10% at 1.80% Phosphorus (P) max. 0.025% Sulfur (S) max. 0.025% Titanium (Ti) 0.020% to 0.050% Boron (B) 0.0005% to 0.005% Aluminum 0.010% to 0.050% the rest iron including contaminants lf- conditions of the foundry. The proposed initial material satisfies the requirements of the mechanical properties. A part is characterized by a good moldability a simple improvement and its tenacity behavior. Since the material is weldable, it can also be used in the use for seamless tubes also for the production of welded longitudinal seam pipes, which for the intended use purpose are also suitable as an initial product for the stabilizers.