阅读说明：本技术 平板弹簧、特别是盘形弹簧或波纹弹簧 (Flat spring, in particular disc spring or wave spring ) 是由 皮特·布赫哈根 于 2020-03-16 设计创作，主要内容包括：本发明涉及一种平板弹簧(1),特别是盘形弹簧(1a)或波纹弹簧(1b),其具有由低合金钢构成的弹簧体(2),所述低合金钢具有大于0.35重量％的且最高为0.75重量％的碳含量。根据本发明,钢包含0.3重量％至0.9重量％的锰(Mn)作为合金元素。根据本发明,钢还包含重量份额为0.3重量％至1.5重量％的铬(Cr)作为合金元素。根据本发明,钢还包含0.1重量％至0.6重量％的钼(Mo)作为合金元素。根据本发明,钢还包含大于0.4重量％和至多8重量％的镍(Ni)作为合金元素。以这种方式构成的平板弹簧相对于传统的平板板簧具有改进的强度,并且相对于由常规弹簧钢构成的弹簧没有韧性损失。(The invention relates to a flat spring (1), in particular a cup spring (1a) or a bellows spring (1b), having a spring body (2) consisting of a low-alloy steel having a carbon content of more than 0.35 wt.% and at most 0.75 wt.%. According to the invention, the steel contains 0.3 to 0.9 wt.% of manganese (Mn) as alloying element. According to the invention, the steel also contains chromium (Cr) as an alloying element in a proportion by weight of 0.3 to 1.5 wt.%. According to the invention, the steel also comprises 0.1 to 0.6 wt.% of molybdenum (Mo) as an alloying element. According to the invention, the steel also comprises more than 0.4% by weight and at most 8% by weight of nickel (Ni) as alloying element. The flat spring formed in this way has improved strength compared to conventional flat leaf springs and no loss of toughness compared to springs formed from conventional spring steel.)

1. A flat spring (1), in particular a disk spring (1a) or a wave spring (1b), having a spring body (2) made of a low-alloy steel,

the low alloy steel has a carbon content of greater than 0.35 wt% and up to 0.75 wt%,

-wherein the steel comprises 0.3 to 0.9 wt.% manganese (Mn) as alloying element,

-wherein the steel further comprises chromium (Cr) as an alloying element in a weight share of 0.3 to 1.5 wt. -%, preferably 0.4 to 0.7 wt. -%,

-wherein the steel further comprises 0.1 to 0.6 wt.% of molybdenum (Mo) as alloying element,

-wherein the steel further comprises more than 0.1 wt% and at most 8 wt% of nickel (Ni) as alloying element.

2. The flat spring as claimed in claim 1,

it is characterized in that the preparation method is characterized in that,

the proportion by weight of the steel not formed by the alloying elements is formed by iron (Fe), carbon (C) and impurities resulting from the melting.

3. The flat spring according to claim 1 or 2,

it is characterized in that the preparation method is characterized in that,

the proportion by weight of all alloying elements of the steel is at most 5% by weight, preferably at most 3.7% by weight.

4. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the flat spring comprises at least one of the following components as an alloy element:

-vanadium (V);

-titanium (Ti);

-tungsten (W);

-niobium (Nb).

5. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

-the steel comprises at least one of the alloying elements vanadium (V), titanium (Ti), tungsten (W) and niobium (Nb),

-wherein a (first) acceptable sum (S1) of the weight share (in weight%) of the alloying elements (V, Ti, W, Nb) and of chromium (Cr) also present in the steel is formed by the sum of the weight share of chromium (Cr) and three times the weight share of the other four alloying elements (V, Ti, W, Nb) as long as these alloying elements are present in the steel,

-wherein the (first) acceptable sum (S1) is from 0.3 wt% to 1.5 wt%, preferably from 0.4 wt% to 0.7 wt%.

6. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the steel contains 0.1 to 0.3 wt% of molybdenum (Mo) as an alloying element.

7. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the steel contains 0.4 to 2 wt.%, preferably 0.5 to 1 wt.% of nickel (Ni) as an alloying element.

8. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the steel contains silicon (Si) as an alloying element up to 0.3 wt.%.

9. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the steels each have a weight fraction (x) of 0< x <0.2 wt.%, preferably 0< x <0.1 wt.%:

-vanadium (V); and/or

-titanium (Ti); and/or

-tungsten (W); and/or

-niobium (Nb).

10. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

-the (second) sum of the acceptable (S2) weight shares (% by weight) of the alloying elements silicon (Si), manganese (Mn), chromium (Cr), nickel (Ni), tungsten (W), vanadium (V), titanium (Ti), niobium (Nb) and molybdenum (Mb) is calculated as follows:

s2 ═ Si + Mn + Cr + Ni + W + (V + Ti + Nb-Mo) × 3); and is

-said (second) acceptable sum (S2) is less than 3 wt%, preferably less than 2 wt%.

11. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the low alloy steel is tempered, preferably bainitic.

12. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the steel is tempered to a strength above 1700 MPa.

13. The flat spring according to one of the preceding claims,

it is characterized in that the preparation method is characterized in that,

the carbon content of the steel is greater than 0.55 wt.%.

Technical Field

The invention relates to a flat spring, in particular a disk spring or a wave spring.

Background

Flat springs are usually made of standard material, so-called flat material. In order to shape the spring, so-called embossing, the material used needs to have sufficient deformability. After the forming process is performed, the spring is tempered to produce the desired spring elastic properties.

The DIN standard DIN EN 10132-4 provides the selection of the main hypoeutectoid, carbon and low-alloy steels of the Si to CrV group as materials suitable for flat springs. In order to improve the properties of flat springs, in particular with regard to load-bearing capacity, relaxation resistance and dynamic service life, the springs can be tempered to a higher strength, thermally pretreated and given special surface properties, for example by shot peening, smoothing or deep rolling.

However, the above measures cannot be combined arbitrarily, since, for example, higher strengths lead to higher load capacities, but also to a reduction in the service life owing to the embrittlement associated with conventional plant processes.

Disclosure of Invention

The object of the invention is to show a new way of developing a flat spring. In particular, the aim is to produce a flat spring with improved strength without limiting the toughness.

Said object is achieved by a flat spring according to independent claim 1. Preferred embodiments are the subject of the dependent claims.

The basic idea of the invention is therefore to use low-alloy steels with the alloying elements manganese (Mn), chromium (Cr), vanadium (V), molybdenum (Mo) and nickel (Ni), which are each contained in a defined proportion by weight, as the material of the flat springs.

Experimental studies have shown that the basic spring properties, such as fatigue strength, service life, relaxation resistance and load-bearing capacity, can be significantly improved in flat springs of this type. In particular, flat springs with a strength of up to 2100MPa can be technically realized by the material composition according to the invention.

The flat spring according to the invention, in particular a cup spring or a bellows spring, comprises a spring body consisting of a low-alloy steel having a carbon content of more than 0.35 wt.% and at most 0.75 wt.%. According to the invention, the steel contains 0.3 to 0.9% by weight of manganese as alloying element. According to the invention, the steel also contains chromium as an alloying element in a proportion of 0.3 to 1.5% by weight. Furthermore, according to the invention, the steel also contains 0.1 to 0.6 wt.% molybdenum as an alloying element. Furthermore, the steel also contains more than 0.4% by weight and up to 8% by weight of nickel as alloying element.

In the flat spring according to the invention, suitable compressive residual stresses can be introduced by shot peening, smoothing or deep rolling, so that the spring properties thereof are positively influenced.

In a preferred embodiment, the proportion by weight of the steel not formed by the alloying elements is formed by iron (Fe). As regards its contribution to the total weight of the steel, the alloying elements are supplemented by iron to form the steel. In addition to iron and alloying elements, the steel can also contain small amounts of impurities, which however preferably represent at most 0.1 wt.% of the total weight of the steel.

According to a preferred embodiment, the proportion by weight of all alloying elements in the steel is at most 5% by weight, preferably at most 3.7% by weight.

According to a further preferred embodiment, the flat spring comprises as alloying elements at least one of the following components: vanadium (V), titanium (Ti), tungsten (W), niobium (Nb).

In a preferred embodiment, the steel comprises at least one of the alloying elements vanadium (V), titanium (Ti), tungsten (W) and niobium (Nb). In this embodiment, the (first) acceptable sum (S1) of the alloying elements (V, Ti, W, Nb) and the proportion by weight (in% by weight) of chromium (Cr) that is also mandatory in the steel is formed by the sum of the proportion by weight of chromium (Cr) and three times the proportion by weight of the other four alloying elements (V, Ti, W, Nb) as long as these alloying elements are present in the steel. If one, two or three of the four alloying elements vanadium (V), titanium (Ti), tungsten (W) and niobium (Nb) proposed in this embodiment are not contained in the steel, these alloying elements are not taken into account when calculating the (first) passing sum (S1), i.e. their weight share is assumed to be 0 wt.%. In this embodiment, the (first) acceptable sum (S1) is 0.3 to 1.5 wt%, preferably 0.4 to 0.7 wt%.

According to another preferred embodiment, the steel comprises 0.1 to 0.3 wt.% molybdenum (Mo) as alloying element. Improved hardenability in steel can be achieved with the aid of molybdenum. In addition, particularly good low-temperature toughness can be achieved. However, due to the tendency to form special carbides at higher molybdenum contents, the alloying elements should be limited to the above-mentioned range of 0.1 to 0.6 wt.%, preferably 0.1 to 0.3 wt.%.

The alloying element nickel in concentrations up to 8 wt.% significantly improves the toughness of the high strength steel. In order to be able to contribute significantly to the toughness improvement, according to a preferred embodiment, a nickel content of more than 0.4 wt.% is suggested. The nickel content preferably ranges from 0.4 to 2% by weight, particularly preferably from 0.5 to 1% by weight.

The alloying element silicon leads to an undesirably high sensitivity of the steel to edge decarburization during tempering and must therefore be limited. Therefore, according to another preferred embodiment of the invention, the steel of the flat spring comprises at most 0.3 wt.% of silicon as alloying element.

According to an advantageous development, it has proven to be particularly advantageous in terms of the achieved toughness and the achieved (permanent) strength if the residual proportion by weight of austenite lies between 2% and 10%, in particular between 2% and 5%. According to a further preferred embodiment, the (second) sum of the acceptable percentages by weight (S2) of the alloying elements silicon (Si), manganese (Mn), chromium (Cr), nickel (Ni), tungsten (W), vanadium (V), titanium (Ti), niobium (Nb) and molybdenum (Mb) is calculated as follows:

S2＝Si+Mn+Cr+Ni+W+(V+Ti+Nb-Mo)*3)。

in this embodiment, the (second) acceptable sum (S2) is less than 3 wt%, preferably less than 2 wt%.

For cost reasons, no method for adding a relatively large amount of cobalt to the steel is provided in the flat spring according to the invention, but this is possible and technically advantageous. At a maximum cobalt content of 0.1 wt.%, the desired advantageous spring properties can be achieved, while at the same time a not insignificant cost advantage is achieved in the production of the flat spring.

According to an advantageous development, the low-alloy steel is tempered, preferably bainite tempered.

Particularly preferably, the steel of the flat spring is tempered to a strength of more than 1700MPa, which in conventional spring steels results in a high probability of fracture due to loss of toughness and low fatigue strength, low service life and poor relaxation resistance.

According to a further advantageous development, the carbon content of the steel is greater than 0.55 wt.%. The carbon contained in the steel directly influences the hardenability of the steel, in particular its tempering and its solid-solution strengthening, and should therefore be contained in a weight proportion of more than 0.55 wt.% in the low-alloy steel of the flat spring described here. However, in view of the undesired special carbide precipitation for the flat springs described here, the carbon content in this embodiment should not exceed 0.75% by weight.

Further important features and advantages of the invention emerge from the dependent claims, the figures and the corresponding drawing description based on the figures.

It is to be understood that the features mentioned above and those yet to be explained below can be used not only in the respectively stated combination but also in different combinations or individually without departing from the scope of the present invention.

Drawings

Preferred embodiments of the present invention are illustrated in the accompanying drawings and described in more detail in the following description.

Fig. 1, which is the only schematic illustration, shows an example of a flat spring 1 according to the invention in a sectional view, which is realized as a disk spring. Other embodiments of the flat spring 1 are also conceivable, namely, for example, a bellows spring not shown in the figures.

Detailed Description

The flat spring 1, which is embodied as a disk spring, comprises a spring body 2 made of a low-alloy steel having a carbon content of more than 0.35 wt.% and at most 0.75 wt.%. The proportion by weight of all alloying elements is up to 5% by weight, in a particularly preferred variant up to 3.7% by weight.

In the exemplary scenario of fig. 1, the steel contains 0.3 to 0.9 wt.% manganese (Mn) as alloying element. In the example of fig. 1, the steel also contains chromium (Cr) as an alloying element. In this case, chromium (Cr) is contained in a proportion by weight of 0.3 to 1.5 wt.%. The steel further comprises 0.1 to 0.6 wt.% of molybdenum (Mo) as an alloying element. Furthermore, the steel contains more than 0.1 wt.% and up to 8 wt.% of nickel (Ni) as an alloying element. The proportion by weight of the steel not formed by the alloying elements is formed by iron (Fe). In addition to iron and alloying elements, the steel may also contain small amounts of impurities, but said impurities represent at most 0.1% by weight of the total weight of the steel.

The proportion by weight of all alloying elements of the low-alloy steel is advantageously at most 5% by weight, preferably at most 3.7% by weight. Preferably, the carbon content of the steel is more than 0.55 wt.% and at most 0.75 wt.%.

Further, the steel can contain at least one of the alloying elements vanadium (V), titanium (Ti), tungsten (W) and niobium (Nb). In this variant, a (first) acceptable sum (S1) of the weight fractions (in wt.%) of the alloying elements (V, Ti, W, Nb) and also of the chromium (Cr) that is mandatory to be present in the steel is formed by the sum of the weight fraction of chromium (Cr) and three times the weight fractions of the other four alloying elements (V, Ti, W, Nb), as long as these alloying elements are present in the steel. If one, two or three of the four alloying elements vanadium (V), titanium (Ti), tungsten (W) and niobium (Nb) described in this variant are not contained in the steel, they are not taken into account when calculating the (first) acceptable sum (S1), i.e. their weight share is assumed to be 0 wt.%. In this variant, the calculation (S1) is ignored, i.e. its weight share is assumed to be 0 wt.%. In this variant, the sum of (first) passes (S1) is from 0.3 wt% to 1.5 wt%, preferably from 0.4 wt% to 0.7 wt%.

Particularly preferably, the steel contains 0.1 to 0.6 wt.% molybdenum (Mo) and/or 0.5 to 1 wt.% nickel (Ni) as alloying elements.

Optionally, the steel contains silicon (Si) as an alloying element up to 0.3 wt.%.

Preferably, the (second) sum of the acceptable percentages by weight of the alloying elements silicon (Si), manganese (Mn), chromium (Cr), nickel (Ni), tungsten (W), vanadium (V), titanium (Ti), niobium (Nb) and molybdenum (Mb) (S2) is calculated as follows: s2 ═ Si + Mn + Cr + Ni + W + (V + Ti + Nb-Mo) × 3). In this variant, the (second) acceptable sum (S2) is less than 3 wt%, preferably less than 2 wt%. The remaining or missing weight fraction of the spring body is advantageously formed by iron (Fe) and production-related impurities.

Alternatively, the steel can contain cobalt as the alloying element, but the weight proportion is at most approximately 0.1 wt.%. The steel must be suitably tempered and preferably does not contain pearlite. The low-alloy steel is particularly preferably bainite tempered. The strength of the steel is preferably greater than 1700 MPa. Advantageously, the surface has at least partially, preferably completely, a surface roughness Ra of less than 0.8 μm. The surface roughness Ra can preferably be achieved by polishing the relevant surface of the flat spring.

In the flat spring described here, the spring performance thereof can be further improved by introducing appropriate compressive residual stress by means of shot peening, smoothing or deep rolling.