Spring, method for producing a spring, assembly comprising a spring, method for producing an assembly, and spring clamp

Abstract

The invention relates to a spring (1), in particular for use in a spring clamp (20), wherein the spring (1) consists of a spring steel. The aim of the invention is to provide a spring which has improved properties and which is simultaneously particularly simple to manufacture. This is substantially achieved in that the spring (1) has a first region (4) and a second region (5), and the spring (1) has a higher degree of hardness in the first region (4) than in the second region (5).

Description

[0001] Spring, method for producing a spring, assembly comprising a spring, method for producing an assembly and spring clamp

[0002] The invention relates to a spring, particularly suitable for use in a spring-loaded terminal, wherein the spring consists at least in regions of a spring steel.

[0003] The invention also relates to a method for producing a spring.

[0004] Furthermore, the invention relates to an assembly comprising a spring according to the invention and a further component.

[0005] The invention also relates to a method for producing an assembly.

[0006] Finally, the invention relates to a spring-loaded terminal having at least one spring designed according to the invention.

[0007] It is known from the prior art to use single- or multi-bent springs in spring-loaded terminals, for example, in through-type terminals or terminal blocks or connectors. The spring force is used to secure a conductor to be connected, for example, to a busbar.

[0008] Springs used in spring-loaded terminals are constantly exposed to recurring loads during operation. In particular, the alternation between deflection and relaxation of a spring places stress on the spring, which can result in a deterioration of the spring properties and thus a reduction in the quality of the electrical connection.

[0009] According to one design of a spring-loaded terminal, the spring is deflected or compressed for operation, and the conductor to be connected is inserted into the spring-loaded terminal through a conductor insertion opening. The spring and the conductor are then arranged in the spring-loaded terminal in such a way that the conductor is fixed to a busbar by the spring force.

[0010] To withstand these deflection-induced loads, it is known from the prior art to increase the hardness of such springs by means of furnace heat treatment. Such heat treatment improves, on the one hand, the settling behavior—that is, the degree of permanent deformation under constantly recurring and / or high loads on the spring—and, on the other hand, the spring's spring-force effect.

[0011] The disadvantage of furnace heat treatment is that it is very complex and, in particular, time-consuming. Typically, springs for this application are kept at the elevated temperature for a period of approximately two hours.

[0012] Based on the prior art described above, the object of the invention is to provide a spring that has improved properties and is, at the same time, particularly easy to manufacture. Furthermore, the object of the invention is to provide a method for producing a spring according to the invention.

[0013] Furthermore, it is an object of the invention to provide an assembly comprising a spring according to the invention and a method for producing such an assembly, wherein the assembly has improved properties and at the same time is particularly easy to produce.

[0014] Finally, it is an object of the invention to provide a spring-loaded terminal which has improved quality in operation.

[0015] Improved properties of a spring include, in particular, improved setting behavior and improved spring-force effect.

[0016] According to a first teaching of the present invention, the above-mentioned object is achieved by a spring as described above in that the spring has a first region and a second region, wherein the spring has a higher hardness in the first region than in the second region.

[0017] Particularly preferably, the first region of the spring is the region which is subjected to the highest load during use of the spring.

[0018] According to the invention, it was recognized that an improvement in the product performance of a spring, i.e., an improvement in the setting behavior and an improvement in the spring-force effect, can be achieved even if the spring has a particularly high hardness only locally, especially in the area of ​​highest load. Even local hardening of the spring results in an overall improvement in the properties such that the spring can be used long-term without any loss of quality.

[0019] Local hardening of the spring in at least one area reduces the overall settling behavior of the spring. Multiple deflections or stresses on the spring result in particularly low permanent deformation. Furthermore, the spring force during the deflection of the spring is particularly high. Since the spring force of the spring establishes an electrical connection during operation, improving the spring force during operation increases the reliability of the electrical connection by using a spring-loaded terminal with the spring designed according to the invention.

[0020] A spring with locally varying hardness also has the advantage of being particularly hard in the area of ​​maximum load, and thus able to withstand high loads. On the other hand, the areas subject to deflection can have a lower hardness, so that these areas can be actuated or deflected with less force.

[0021] Furthermore, the spring according to the invention has the advantage that local hardening can also be performed using other treatment methods that are less time-consuming than furnace heat treatment. For example, local heat input can be achieved by laser hardening. This has the advantage that a spring with improved properties can be produced particularly quickly, efficiently, and also individually with regard to the treatment parameters and thus with regard to the desired hardness levels.

[0022] For example, the spring in the first region has a hardness greater than 500 HV, preferably greater than 510 HV, and more preferably greater than 520 HV. Particularly preferably, the hardness in the first region is approximately 540 HV.

[0023] According to one embodiment, the hardness in the second region is approximately 500 HV, preferably the hardness has a value that is less than 500 HV.

[0024] The aforementioned values ​​also depend, in particular, on the material from which the spring is made. According to the invention, the spring is formed, at least in part, from spring steel. Preferably, the spring consists entirely of spring steel. The use of spring steel ensures both particularly high strength and high elasticity of the spring.

[0025] Particularly preferably, the first region is realized by a surface heat input. If the heat input is achieved by laser hardening, the surface heat input continues into the spring in such a way that the spring cross-section in the irradiated area is completely heated. As a result, a structural transformation, which results in increased hardness, can be realized across the entire spring cross-section in the irradiated area.

[0026] Alternatively, the first area is realized by a linear heat input.

[0027] For example, the line can form an outline of a defined area.

[0028] According to an alternative embodiment, the first region is realized by a point-like heat input. According to this embodiment, the first region, which is characterized by increased hardness, is very limited locally.

[0029] According to a further preferred embodiment of the spring, the spring has at least one spring arc. If the spring is used in a spring-loaded terminal, the at least one spring arc is the region of the spring that is subjected to maximum load upon deflection of the spring. Therefore, the first region of the spring is particularly preferably arranged in the region of the spring arc. For example, the first region can correspond to the spring arc. Furthermore, the first region can also correspond to a partial region of the spring arc.

[0030] According to one embodiment, the spring arch has a vertex, wherein the first region of the spring comprises the vertex of the spring arch.

[0031] If the spring arch has a circular cross-section, the apex refers to the point of the spring arch that is located centrally between the two spring legs that adjoin either side of the spring arch. According to a particularly preferred embodiment, the spring has precisely a first region that has a higher hardness, wherein this region is located in the region of the spring arch. The remaining part of the spring forms the second region, whose hardness is lower than the hardness in the first region. This embodiment has the advantage that the spring is easy to deflect due to its low hardness and, moreover, has good product performance due to the high hardness in the region of the spring arch.

[0032] When it is said that the first region is arranged in the region of the spring arch, this means that the first region is arranged in a region which has a curvature in cross-section.

[0033] According to a further embodiment of the spring, the first region can comprise both the spring arch and, in addition, at least a partial region of the legs adjoining the spring arch.

[0034] According to a further advantageous embodiment, the spring is hardened in the first region after forming, and the spring is not hardened in the second region after forming. When it is stated that the spring is not hardened in certain regions, this means that the spring has not been subjected to any further hardening after forming, for example, after a bending process. Hardening during the manufacturing process of a semi-finished product made of spring steel is not precluded by the aforementioned embodiment.

[0035] Due to the locally applied heat treatment, the spring has, according to one design, tempering colors locally, i.e. in the heat-treated area.

[0036] According to a further embodiment, the spring has at least two regions, namely at least a first region and a third region, in which the spring has a higher hardness than in the second region.

[0037] The hardness can be the same in the at least two regions of higher hardness. For example, the spring can be heat-treated in the first region using laser hardening, and in the third region using the same parameters. Preferably, the second region still forms the region of the spring with a lower hardness, especially since this region was not heat-treated after forming.

[0038] Alternatively, the hardness can also vary in the at least two areas of increased hardness. For example, the spring can be heat-treated using laser hardening in the first area and heat-treated in the third area using different parameters. According to this design, the spring has at least three different degrees of hardness. Especially in combination with laser hardening, springs with individually adjusted hardness ranges for different applications can be produced particularly easily.

[0039] For example, the spring has two spring arches, with the first region being arranged in the region of the first spring arch and the third region being arranged in the region of the second spring arch. According to a second teaching of the present invention, the object set out above is achieved by a method described above for producing one of the previously described springs, in that the method comprises the following steps:

[0040] - Production of a spring cut part and forming the spring cut part into a spring, in particular using a punching and bending process

[0041] - subsequently hardening at least a first region of the spring by local heating, in particular by means of laser hardening.

[0042] The method has the advantage that the spring can be specifically hardened, for example, at the point exposed to the greatest stress during operation, thereby increasing the overall performance of the spring. The spring is designed according to one of the configurations described above.

[0043] According to a first embodiment of the method, the spring is heated locally to a temperature between 200°C and 400°C during hardening, at least in the first region.

[0044] To achieve maximum hardness, the spring is heated locally in at least the first area to a temperature of approximately 400 °C.

[0045] The heat input locally heats the spring to such an extent that the hardness of the spring steel in the first area increases due to a structural transformation. The heat input essentially penetrates the spring steel at the irradiated point, allowing a complete structural transformation to occur in the irradiated area.

[0046] If hardening is carried out by laser hardening, the irradiation time of the spring with the laser beam is preferably between 0.1 and 1 s, particularly preferably between 0.2 and 0.6 s. For example, the laser for hardening the spring can be designed as a diode laser.

[0047] The heat input can generally be point-shaped, linear or surface-shaped.

[0048] According to a preferred embodiment, the laser irradiates the first region in a point-like manner. When it is said that the laser irradiates the first region in a point-like manner, this means that neither the laser beam nor the spring are moved during hardening. The extent of the point-like heat input corresponds to the beam diameter of the laser beam.

[0049] Alternatively, the laser beam can irradiate or traverse the first area in a linear fashion. In particular, the laser beam can traverse the outline of a defined area.

[0050] According to a further embodiment of the method, the laser beam irradiates the spring in the first area. For example, if both the spring arc and the adjacent legs are being hardened, the laser beam can sequentially pass over the legs and the spring arc.

[0051] If the spring has two or more regions that are hardened by applying heat, these regions are preferably heat-treated sequentially. The at least two regions can be treated with the same laser parameters. Alternatively, the at least two regions can also be treated with different laser parameters. Treatment with different laser parameters, such as different laser power, results in the at least two regions subsequently having different degrees of hardness.

[0052] According to a particularly preferred embodiment, the method for producing a spring comprises a production line. After the manufacturing step and the forming step, the spring is immediately hardened, preferably by laser hardening, and is then immediately available for assembly.

[0053] In detail, a lengthy furnace heat treatment followed by a subsequent cooling process can be avoided. This process has the advantage that the production of a hardened spring can be carried out particularly quickly. On the other hand, by adjusting laser parameters, it is particularly easy to produce individually manufactured springs for various applications.

[0054] According to a third teaching of the present invention, the object set out at the outset is achieved by an assembly comprising at least one spring according to one of the previously described embodiments and further comprising at least one further component, in particular a busbar, wherein the at least one spring and the at least one further component are connected to one another in a form-fitting and / or force-fitting and / or material-fitting manner.

[0055] The assembly according to the invention has the advantage that the assembly has improved overall product performance due to the locally hardened spring. Thanks to improved settling behavior and an improved spring-force effect, the assembly can be used for a particularly long time without any loss of quality.

[0056] In principle, the spring and the at least one further component can be connected to one another in a form-fitting and / or force-fitting and / or material-fitting manner. For example, the at least one spring and the at least one further component can be locked together.

[0057] According to a particularly preferred embodiment, the additional component is designed as a busbar. For example, the assembly comprises two springs and a busbar, with the springs having a higher hardness locally in the area of ​​maximum load. According to a fourth teaching of the present invention, the object set out above is achieved by a method described above for producing a previously described assembly, in that the method comprises the following steps:

[0058] - Production of at least one spring cut part and preferably at least one further component cut part,

[0059] - forming the at least one spring cut part into at least one spring and preferably forming the at least one further component cut part into at least one further component, in particular by means of a punching and bending process,

[0060] - connecting the at least one spring and the at least one further component during or after the manufacturing step or the forming step and

[0061] - subsequent hardening of the at least one spring in at least the first region by local heating, preferably by means of laser hardening.

[0062] The method has the advantage that the at least one spring and the further component can be connected to one another in a state in which the at least one spring is not yet hardened. Because the at least one spring is not yet hardened during the connection process, the at least one spring and the further component can be connected to one another particularly easily.

[0063] Because the at least one spring is only locally hardened and the heat input has no or only a minor effect on the other component, the at least one spring can also be connected to components that cannot tolerate such heat input. For example, the other component could be a busbar. Such a busbar is typically made of tinned copper, which cannot tolerate heat input of approximately 400°C.

[0064] The at least one spring and the at least one further component can be connected to one another in a form-fitting and / or force-fitting and / or material-fitting manner.

[0065] According to a further teaching of the present invention, the object set forth at the outset is achieved by a spring-loaded terminal as described above, wherein the spring-loaded terminal comprises at least one spring according to the previously described embodiments, at least one busbar, and at least one housing. The housing has at least one conductor insertion opening through which a conductor can be inserted into the housing. Furthermore, the at least one spring is designed and arranged in the housing in such a way that it fixes an inserted conductor to the busbar.

[0066] For example, the spring is deflected before or during the insertion of the conductor and subsequently pulls or pushes the conductor against the busbar. The spring-loaded terminal can be designed as a series terminal, a through terminal, or even a plug-in connector. This list is not exhaustive. Any other conventional spring-loaded terminal with the same or similar functionality is also suitable within the scope of the present invention.

[0067] There are now numerous possibilities for designing and developing the spring according to the invention, the assembly according to the invention, the method according to the invention, and the spring-loaded terminal according to the invention. Reference is made to the patent claims subordinate to the independent patent claims and to the following description of preferred embodiments in combination with the drawings.

[0068] The drawing shows:

[0069] Fig. 1 an embodiment of a spring,

[0070] Fig. 2 schematically shows an embodiment of a structure for laser hardening a spring,

[0071] Fig. 3 to 5 schematically show differently hardened areas of a spring arch,

[0072] Fig. 6 shows an embodiment of a method for producing a spring,

[0073] Fig. 7 shows a method for producing an assembly and

[0074] Fig. 8 shows an embodiment of an assembly and a spring-loaded terminal.

[0075] Fig. 1 shows an embodiment of a spring 1 that can be used in a spring terminal 20. The spring 1 has a spring bend 2 and an insertion opening 3 through which a conductor can be inserted into the spring terminal 20 in the assembled state.

[0076] In the illustrated state, spring 1 is deflected, i.e., loaded. The spring arc 2 is the area of ​​spring 1 subject to maximum load. In the remaining area of ​​spring 1, the load caused by the deflection has a lesser effect. To withstand the loads caused by the recurring deflections, spring 1 has a first area 4 and a second area 5, with the hardness of spring 1 being higher in the first area 4 than in the second area 5.

[0077] In the illustrated embodiment, the first region 4 corresponds to the spring arch 2. The second region 5 corresponds to the remaining part of the spring 1.

[0078] Spring 1 is therefore hardened locally in the area subject to maximum load and thus has different degrees of hardness overall.

[0079] Overall, the spring 1 exhibits improved setting behavior and an improved spring-force effect due to the local hardening, so that the spring 1 can be used for a particularly long time without any loss of quality. Fig. 2 shows a schematic exemplary embodiment of a structure for the local laser hardening of a spring 1 and an assembly 7 comprising a spring 1 and a busbar 6. The spring 1 and the busbar 6 are connected to one another as an assembly 7.

[0080] In addition, the spring 1 has a spring arch 2, which in the illustrated embodiment is hardened as the first region 4 of the spring 1. Also shown is a laser 8, whose laser beam 9 briefly heats the first region 4, i.e., the region of the spring arch 2, so that a structural transformation occurs in the irradiated region, resulting in a local increase in hardness.

[0081] The illustrated structure has the advantage that the individual components of the assembly 7 can first be connected and then only the spring 1 is locally hardened without the heat input having an effect on the busbar 6.

[0082] In the illustrated embodiment, the busbar 6 is made of tinned copper and is therefore not suitable for heat input in the range of 400°C. Since the heat input and thus the hardening of the spring 1 only occurs locally, the fact that the busbar 6 cannot be exposed to such heat input is not disadvantageous.

[0083] As a result, the assembly 7, treated as shown, comprising a busbar 6 and a spring 1, has an improved product performance, in particular an improved setting behavior and an improved spring force effect, due to the hardening process in the area of ​​the highest load on the spring 1.

[0084] Figs. 3 to 5 each show embodiments of a locally hardened spring 1, wherein the first region 4, which has an increased hardness, is designed differently in each case.

[0085] In Fig. 3, the first region 4 results from the fact that the spring arch has been heated across its entire surface. In the illustrated embodiment, the spring arch 2 is essentially completely hardened.

[0086] In Fig. 4, the spring arch 2 has been heated in a point-like manner, resulting in the locally very limited first region 4 in the region of the apex 10 of the spring arch 2.

[0087] In Fig. 5, the hardening is carried out linearly, with the line forming the contour of a defined area.

[0088] All three embodiments have the advantage that the spring 1 has an overall reduced setting behavior and an improved force-spring effect and is also particularly easy to manufacture.

[0089] Fig. 6 shows an embodiment of a method 11 for producing a spring 1, wherein the spring 1 is designed as shown in Fig. 1.

[0090] In a first step 12, a spring blank is punched out of spring steel. In a second step 13, the spring blank is bent into the shape required for the application of spring 1.

[0091] In a next step 14, the spring 1 is hardened locally, at least in the first region 4, for example by means of laser hardening.

[0092] The spring 1 thus produced is then immediately available for assembly. This makes the process described particularly efficient, as the improved spring 1 can be made available particularly quickly.

[0093] Fig. 7 shows an embodiment of a method 15 for producing an assembly 7 from a spring 1 and a busbar 6.

[0094] In a first step 16, a spring cut part and a busbar cut part are each punched out from a semi-finished product.

[0095] In a next step 17, the spring cut part is formed into a spring, and the conductor rail cut part is formed into a conductor rail. In a further step 18, the spring 1 and the conductor rail are connected to each other in a form-fitting manner.

[0096] In a subsequent step 19, the spring 1 is hardened locally, for example by means of laser hardening, in the area which is exposed to the maximum load during operation.

[0097] The method has the advantage that the assembly can be particularly easily connected to one another in a state in which the individual components, in particular the spring, do not yet have increased hardness values.

[0098] Through the subsequent local heat treatment, the overall performance of the article can be increased, so that the manufactured assembly 7 is, on the one hand, particularly easy to manufacture, in particular to connect with each other, and at the same time has improved properties that guarantee long-term use without loss of quality.

[0099] Fig. 8 shows an embodiment of a spring-loaded terminal 20 in the form of a simple through-type terminal, comprising two locally hardened springs 1 and a busbar 6. The assembly comprising the springs 1 and the busbar 6 is arranged in a housing 21. The housing 21 has two conductor insertion openings 22 through which the conductors to be connected can be inserted into the spring-loaded terminal 20.

[0100] To do this, the springs 1 are first deflected, for example, by a screwdriver that can be inserted into the openings 23. Once the springs 1 are deflected, the conductors to be connected can be inserted into the conductor insertion openings 22 and further through the insertion openings 3 of the springs 1.

[0101] If the screwdrivers are subsequently removed, the springs 1 secure the conductors to the busbar. Due to their particularly high spring force effect, the electrical connection between two conductors, as described above, is particularly secure. Furthermore, due to their local hardening, the springs 1 can withstand the stresses they are exposed to due to recurring deflection particularly well. In detail, the springs exhibit particularly low settling behavior.

[0102] Thanks to improved spring setting properties and improved spring-force effect, the spring-loaded terminal 20 can be used for a particularly long time without any loss of quality.

[0103] Reference symbol

[0104] 1 spring

[0105] 2 spring bows

[0106] 3 insertion opening

[0107] 4 First area

[0108] 5 Second area

[0109] 6 Busbar

[0110] 7 Assembly

[0111] 8 lasers

[0112] 9 Laser beam

[0113] 10 vertex

[0114] 11 Method for producing a spring

[0115] 12 punching the spring

[0116] 13 Bending the spring

[0117] 14 Local hardening of the spring

[0118] 15 Methods for manufacturing an assembly

[0119] 16 Punching the spring and the busbar

[0120] 17 Bending the spring and the busbar

[0121] 18 Form-fitting connection of the spring and the busbar

[0122] 19 Local heating of the spring

[0123] 20 spring-loaded terminals

[0124] 21 housings

Claims

Patent claims 1. Spring (1), in particular for use in a spring-loaded terminal (20), the spring (1) consisting at least in some areas of a spring steel, characterized in that the spring (1) has a first area (4) and a second area (5), the spring (1) having a higher hardness in the first area (4) than in the second area (5).

2. Spring (1) according to claim 1, characterized in that the spring in the first region (4) has a hardness which is greater than 500 HV, which is preferably greater than 510 HV, which is further preferably greater than 520 HV.

3. Spring (1) according to claim 1 or 2, characterized in that the hardness in the second region (5) is approximately 500 HV, preferably the hardness has a value which is less than 500 HV.

4. Spring (1) according to one of claims 1 to 3, characterized in that the first region (4) is realized by a planar or linear or punctiform heat input.

5. Spring (1) according to one of claims 1 to 4, characterized in that the spring (1) has at least one spring arch (2) and that the first region (4) of the spring (1) is arranged in the region of the at least one spring arch (2).

6. Spring (1) according to claim 5, characterized in that the spring arch (2) has a vertex (10) and that the first region (4) comprises the vertex of the spring arch.

7. Spring (1) according to one of claims 1 to 6, characterized in that the spring (1) has been hardened in the first region (4) after forming and that the spring (1) has not been hardened in the second region (5) after forming.

8. Spring (1) according to one of claims 1 to 7, characterized in that the spring (1) has more than one region (4) in which the spring (1) has a higher hardness than in the second region (5).

9. Method (11) for producing a spring (1) according to one of claims 1 to 8, characterized in that the method (1) comprises the following steps: - Production (12) of a spring cut part and forming (13) of the spring cut part into a spring (1), in particular using a punching and bending process - subsequently hardening at least a first region (4) of the spring (1) by local heating (14), in particular by means of laser hardening.

10. Method (11) according to claim 9, characterized in that the spring (1) is heated locally to a temperature between 200°C and 400°C during hardening, at least in the first region (4).

11. Method (11) according to one of claims 9 or 10, characterized in that the heat input is point-shaped, linear or planar.

12. Method (11) according to one of claims 9 to 11, characterized in that the method (11) comprises a production line, wherein after the manufacturing step (12) and the forming step (13) the spring (1) is directly hardened (14), preferably by means of laser hardening, and is then immediately available for assembly.

13. Assembly (7), comprising at least one spring (1) according to one of claims 1 to 8 and further comprising at least one further component, in particular a busbar (6), wherein the at least one spring (1) and the at least one further component are connected to one another in a form-fitting and / or force-fitting and / or material-fitting manner.

14. Method (15) for producing an assembly (7) according to claim 13, characterized in that the method (15) comprises the following steps: - Production (16) of at least one spring cut part and preferably at least one further component cut part, - forming (17) the at least one spring cut part into at least one spring (1) and preferably forming the at least one further component cut part into at least one further component, in particular by means of a punching and bending process, - connecting (18) the at least one spring (1) and the at least one further component during or after the manufacturing step or the forming step and - subsequent hardening (19) of the at least one spring (1) in at least the first region (4) by local heating, preferably by means of laser hardening.

15. Spring-loaded terminal (20) comprising at least one spring (1) according to one of claims 1 to 8, at least one busbar (6) and at least one housing (21), wherein the housing (21) has at least one conductor insertion opening (22) through which a conductor can be inserted into the housing (21) and wherein the at least one spring (1) is designed and arranged in the housing (21) in such a way that it fixes an inserted conductor to the busbar (6).

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