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

Abstract

Described and illustrated is a spring (1), particularly for use in a spring-loaded terminal (20), wherein the spring (1) is made of spring steel. The object of specifying a spring which has improved properties and which is, at the same time, particularly easy to manufacture is essentially achieved in that the spring (1) has a first region (4) and a second region (5), wherein the spring (1) has a higher hardness in the first region (4) than in the second region (5).

Description

The invention is based on a spring, in particular suitable for use in a spring force clamp, wherein the spring consists at least in regions of a spring steel.The invention also relates to a method for producing a spring.The invention further relates to an assembly comprising a spring according to the invention and a further component.The invention also relates to a method for producing an assembly.Finally, the invention relates to a spring force clamp which has at least one spring designed according to the invention.It is known from the prior art to use single or multiple bent springs in spring force terminals, for example in through terminals or terminal blocks or also plug connectors. In this case, the spring force is used to fix a conductor to be connected, for example, to a busbar.Springs used in spring force clamps are exposed to continuously recurring loads during operation. In particular, the change between the deflection and the relaxation of a spring loads the spring, which can result in a deterioration of the spring properties and thus in a decline of the quality of the electrical connection.According to one embodiment of a spring force clamp, the spring is deflected or compressed for operation and the conductor to be connected is inserted into the spring force clamp through a conductor insertion opening. The spring and the conductor are now arranged in the spring force clamp in such a way that the conductor is fixed to a busbar by the spring force.In order to withstand these loads caused by the deflection, it is known from the prior art to increase the hardness of such springs by means of a furnace heat treatment. Such a heat treatment improves, on the one hand, the setting behavior, i.e. the extent of the permanent deformation in the case of continuously recurring and / or high loads of the spring, and, on the other hand, the spring-force effect of the spring.The disadvantage of the furnace heat treatment is that it is very complicated, in particular time-consuming. Springs for the stated application are usually kept at the elevated temperature for a period of about 2 hours.Proceeding from the state of the art presented, it is the object of the invention to specify a spring which has improved properties and which at the same time is particularly simple to produce.In addition, it is an object of the invention to specify a method for producing a spring according to the invention.In addition, it is an object of the invention to specify 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 simple to produce.It is a further object of the invention to provide a spring clip which has improved operational quality.Improved properties of a spring are to be understood in particular as an improved setting behavior and an improved spring-force action.According to a first teaching of the present invention, the aforementioned object is achieved by a spring described at the beginning 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.Particularly preferably, the first region of the spring is the region which is subjected to the highest load during use of the spring.According to the invention, it has been recognized that an improvement in the article 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, in particular in the region of the highest load. Local hardening of the spring also results overall in an improvement in the properties in such a way that the spring can be used in the long term without loss of quality.Local hardening of the spring in at least one region reduces the setting behavior of the spring as a whole. Multiple deflection or loading of the spring results in a particularly low permanent deformation. Furthermore, the spring force is particularly high when the spring is deflected. Since an electrical connection is produced by the spring force of the spring during operation, an improvement in the spring force during operation increases the safety of the electrical connection by a spring force clamp having the spring designed according to the invention.A spring with locally different hardness has the further advantage that, on the one hand, it is particularly hard, in particular in the region of maximum load, and can therefore withstand high loads. On the other hand, for example, the regions which are deflected can have a lower hardness, so that these regions can be actuated or deflected with less force exertion.Furthermore, the spring according to the invention has the advantage that local curing can also be carried out with other treatment methods which are less time-consuming than an oven heat treatment. For example, a local heat input can be effected by means of laser curing. This has the advantage that a spring with improved properties can be produced particularly quickly, efficiently and also individually with respect to the treatment parameters and thus with respect to the desired degrees of hardness.For example, the spring has a hardness in the first region that is greater than 500 HV, which is preferably greater than 510 HV, which is further preferably greater than 520 HV. Particularly preferably, the hardness in the first range is approximately 540 HV.According to one configuration, the hardness in the second region is approximately 500 HV, preferably the hardness has a value which is less than 500 HV.The aforementioned values are also dependent in particular on the material from which the spring is produced. According to the invention, the spring is formed at least in regions from a spring steel. Preferably, the spring is made entirely of spring steel. By using spring steel, both a particularly high strength and a high elasticity of the spring can be ensured.Particularly preferably, the first region is realized by a flat heat input. If the heat input takes place by means of laser hardening, the heat input introduced to the surface into the spring continues in such a way that the spring cross section in the irradiated region is completely heated. As a result, a structure transformation, which results in an increased hardness, can be realized over the complete spring cross section in the irradiated region.Alternatively, the first region is realized by a linear heat input. For example, the line may form an outline of a defined surface.According to an alternative embodiment, the first region is realized by a punctiform heat input. According to this embodiment, the first region, which is distinguished by an increased hardness, is very limited locally.According to a further preferred embodiment of the spring, the spring has at least one spring curve. If the spring is used in a spring force clamp, the at least one spring arc is the region of the spring which is loaded to a maximum extent when the spring is deflected. It is therefore particularly preferred for the first region of the spring to be arranged in the region of the spring arch. For example, the first region may correspond to the spring arc. In addition, the first region can also correspond to a partial region of the spring bow.According to one configuration, the spring bow has an apex, wherein the first region of the spring comprises the apex of the spring bow.If the spring curve has a circular arc-shaped cross section, the vertex is the point of the spring curve that is arranged centrally between the two spring legs that connect to the two sides of the spring curve.According to a particularly preferred embodiment, the spring has exactly one first region which has a higher hardness, wherein this region is arranged in the region of the spring arch. The remaining part of the spring forms the second region, the hardness of which is lower than the hardness in the first region. This configuration has the advantage that the spring is easily deflectable due to the low hardness and, moreover, has a good article performance due to the high hardness in the region of the spring arch.If it is said that the first region is arranged in the region of the spring curve, this means that the first region is arranged in a region which has a curvature in cross section.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.According to a next advantageous embodiment, the spring has been hardened in the first region after the forming and the spring has not been hardened in the second region after the forming. If it is stated that the spring is not cured in regions, this means that the spring has not been subjected to any further curing after the forming, i.e. for example after a bending process. Hardening within the scope of the manufacturing process of a semi-finished product made of spring steel is not excluded by the above-mentioned embodiment.Due to the locally introduced heat treatment, the spring according to one embodiment has tempering colors locally, i.e. in the heat treated region.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.The hardness in the at least two regions of higher hardness can be equally high. For example, the spring can be heat-treated by laser hardening in the first region and in the third region by means of the same parameters. Preferably, the second region still forms the region of the spring which has a lower hardness, in particular since this region has not been heat-treated after the forming.Alternatively, the hardness in the at least two regions of increased hardness can also be of different levels. For example, the spring can be heat-treated by laser hardening in the first region and in the third region by means of different parameters. According to this embodiment, the spring has a total of at least three different degrees of hardness. In particular in combination with curing by means of a laser, springs with individually set hardness ranges can therefore be produced particularly easily for different applications.For example, the spring has two spring arches, wherein the first region is arranged in the region of the first spring arch and wherein the third region is arranged in the region of the second spring arch.According to a second teaching of the present invention, the object set out at the beginning is achieved by a method described at the beginning for producing one of the springs described above in that the method has the following steps:producing a spring cut part and forming the spring cut part into a spring, in particular using a punching-bending methodsubsequently curing at least a first region of the spring by local heating, in particular by laser curing.The method has the advantage that the spring can be cured in a targeted manner, for example at the location which is exposed to the greatest load during operation, as a result of which the overall article performance of the spring can be increased. The spring is configured according to one of the above-described configurations.According to a first embodiment of the method, the spring is locally heated to a temperature between 200° C. and 400° C. during the curing at least in the first region.To achieve a maximum hardness, the spring is locally heated to a temperature of approximately 400° C. in at least the first region.As a result of the heat input, the spring heats up locally in such a way that the hardness of the spring steel in the first region increases as a result of a structure transformation. The heat input penetrates the spring steel at the irradiated location substantially completely, so that a complete structure transformation can also take place in the irradiated region.If the curing is carried out by means of laser curing, the irradiation time of the irradiation 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 curing the spring can be designed as a diode laser.The heat input can basically take place in a punctiform or linear or planar manner.According to a preferred embodiment, the laser irradiates the first region in a punctiform manner. If it is said that the laser irradiates the first region in a punctiform manner, this means that neither the laser beam nor the spring are moved during the curing. The extent of the heat input introduced in punctiform fashion corresponds to the beam diameter of the laser beam.Alternatively, the laser beam can irradiate or travel linearly over the first region. In particular, the laser beam can travel along an outline of a defined surface.According to a next embodiment of the method, the laser beam irradiates the spring in the first region in a planar manner. If, for example, both the spring bow and the legs adjoining the spring bow are hardened, then the laser beam can successively traverse the legs and the spring bow.If the spring has two or more regions which are hardened by means of a heat input, these regions are preferably heat-treated successively. In this case, 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. A treatment with different laser parameters, such as with different laser power, for example, has the result that the at least two regions subsequently have different degrees of hardness.According to a particularly preferred embodiment, the method for producing a spring comprises a production line. After the production step and the forming step, the spring is hardened directly, preferably by means of laser hardening, and is then directly available for assembly.In detail, a long-lasting furnace heat treatment with a subsequent cooling process can be avoided. This method has the advantage that the production of a hardened spring can be carried out particularly quickly on the one hand. On the other hand, by adapting laser parameters, it is possible in a particularly simple manner to produce springs produced individually for different applications.According to a third teaching of the present invention, the object set out at the beginning is achieved by an assembly comprising at least one spring according to one of the embodiments described above 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 positive-locking and / or non-positive-locking and / or firmly-bonded manner.The assembly according to the invention has the advantage that the assembly overall has improved article performance in that the spring is locally cured. Due to an improved setting behavior and due to an improved spring-force effect, the assembly can be used for a particularly long time without loss of quality during operation.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 materially integral manner. For example, the at least one spring and the at least one further component can be latched to one another.According to a particularly preferred embodiment, the additional component is designed as a busbar. For example, the assembly has two springs and one busbar, wherein the springs have a higher hardness locally in the region of the maximum load.According to a fourth teaching of the present invention, the object set out at the beginning is achieved by a method described at the beginning for producing a previously described assembly, characterized in that the method comprises the following steps:producing at least one spring cut part and preferably at least one further component cut part,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 method,connecting the at least one spring and the at least one further component during or after the production step or the forming step, andsubsequently curing the at least one spring in at least the first region by local heating, preferably by means of laser curing.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 cured. Because the at least one spring is not yet hardened during the connection, the at least one spring and the further component can be connected to one another particularly easily.Because the at least one spring is hardened only locally and the heat input does not affect the further component, or does not significantly affect the further component, the at least one spring can also be connected to components which do not withstand such heat input. For example, the further component can be a busbar. Usually, such a busbar consists of tin-plated copper, which does not withstand a heat input of approximately 400 DEG C.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 materially integral manner.According to a further teaching of the present invention, the object set out at the beginning is achieved by a spring force clamp described at the beginning, wherein the spring force clamp has 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, via which a conductor can be inserted into the housing. In addition, 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.For example, the spring is deflected before or during the insertion of the conductor and subsequently pulls or presses the conductor onto the busbar. The spring force terminal can be designed as a terminal block or as a through terminal or also as a plug connector. This list is not exhaustive. Any other conventional spring clip of the same or similar function is also suitable within the scope of the present invention.There are now a large number of possibilities for configuring and developing the spring according to the invention, the assembly according to the invention, the methods according to the invention and the spring force clamp according to the invention. In this regard, reference is made to the patent claims subordinate to the independent patent claims and to the following description of preferred exemplary embodiments in combination with the drawing.In the drawing, the following are shown: FIG. 1 shows an exemplary embodiment of a spring, FIG. 2 schematically shows an exemplary embodiment of a structure for laser hardening of a spring, FIGS. 3 to 5 schematically show differently hardened regions of a spring arch, FIG. 6 shows an exemplary embodiment of a method for producing a spring, FIG. 7 shows a method for producing an assembly, and FIG. 8 shows an exemplary embodiment of an assembly and a spring force clamp.FIG. 1 shows an embodiment of a spring 1 which can be inserted into a spring force clamp 20. The spring 1 has a spring bend 2 and an insertion opening 3, through which a conductor can be inserted into the spring force terminal 20 in the assembled state.In the illustrated state, the spring 1 is deflected, i.e. loaded. The spring bow 2 is the region of the spring 1 which is loaded to the maximum extent. In the remaining region of the spring 1, the load due to the deflection has less effect. In order to be able to withstand the loads caused by the repeated deflections, the spring 1 has a first region 4 and a second region 5, wherein the hardness of the spring 1 is higher in the first region 4 than in the second region 5.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.The spring 1 is therefore hardened locally in the region which is loaded to the maximum extent and thus overall has different degrees of hardness.Overall, the spring 1 already has an improved setting behavior as a result of the local curing and an improved spring-force effect, with the result that the spring 1 can be used for a particularly long time without loss of quality during operation.FIG. 2 shows a schematic exemplary embodiment of a structure for local laser curing of a spring 1 and of an assembly 7 comprising a spring 1 and a busbar 6.In addition, the spring 1 has a spring bow 2 which, in the exemplary embodiment shown, is hardened as a first region 4 of the spring 1. Furthermore, a laser 8 is shown, the laser beam 9 of which temporarily heats the first region 4, i.e. the region of the spring bow 2, so that a structure transformation occurs in the irradiated region, which results in a local increase in the hardness.The illustrated construction has the advantage that the individual components of the assembly 7 can first be connected and then only the spring 1 is locally cured without the heat input acting on the busbar 6.In the exemplary embodiment shown, the busbar 6 is formed from tin-plated copper and is therefore not suitable for a heat input in the range of 400° C. Since the heat input and thus the hardening of the spring 1 only takes place locally, the fact that the busbar 6 cannot be exposed to such a heat input is not disadvantageous.As a result, the assembly 7 made of a busbar 6 and a spring 1 treated as illustrated has an improved article performance, in particular an improved setting behavior and an improved spring-force effect, in the region of the highest load of the spring 1 as a result of the curing process.FIGS. 3 to 5 each show exemplary embodiments of a locally hardened spring 1, wherein the first region 4, which has an increased hardness, is formed differently in each case.In FIG. 3, the first region 4 is obtained by the spring curve having been heated flat. In the exemplary embodiment shown, the spring bow 2 is substantially completely hardened.In FIG. 4, the spring bow 2 has been heated in punctiform fashion, resulting in the locally very limited first region 4 in the region of the apex 10 of the spring bow 2.In FIG. 5, the hardening is carried out linearly, the line forming the contour of a defined surface.All three exemplary embodiments have the advantage that the spring 1 overall has a reduced setting behavior and an improved force-spring effect and is furthermore particularly simple to produce.FIG. 6 shows an exemplary embodiment of a method 11 for producing a spring 1, wherein the spring 1 is designed as shown in FIG. 1.In a first step 12, a spring cut part is punched out of spring steel.In a second step 13, the spring cut part is bent into the shape necessary for the application of the spring 1.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.Subsequently, the spring 1 produced in this way is directly available for assembly. The method illustrated is thus particularly efficient, since the improved spring 1 can be made available particularly quickly.FIG. 7 shows an exemplary embodiment of a method 15 for producing an assembly 7 from a spring 1 and a busbar 6.In a first step 16, a spring cut part and a busbar cut part are each stamped out of a semi-finished product.In a next step 17, the spring cut part is transformed into a spring and the busbar cut part is transformed into a current rail.In a further step 18, the spring 1 and the current rails are connected to one another in a form-fitting manner.In a subsequent step 19, the spring 1 is hardened locally, for example by laser hardening, in the region which is exposed to the maximum load during operation.The method has the advantage that the assembly can be connected to one another particularly easily in a state in which the individual components, in particular the spring, do not yet have increased hardness values.The article performance can be increased overall by the subsequent local heat treatment, such that the produced assembly 7 is particularly easy to produce, in particular to connect to one another, on the one hand, and at the same time has improved properties which guarantee long use without loss of quality.FIG. 8 shows an embodiment of a spring force clamp 20 in the form of a simple through clamp, which has two locally hardened springs 1 and a busbar 6. The assembly of the springs 1 and the busbar 6 are arranged in a housing 21. The housing 21 has two conductor insertion openings 22, via which the conductors to be connected can be inserted into the spring-loaded terminal 20.For this purpose, the springs 1 are first deflected, for example by a screwdriver which can be inserted into the openings 23. When 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.If the screwdrivers are subsequently removed again, the springs 1 fix the conductors in each case to the busbar. Due to its particularly high spring-force effect, the electrical connection of two conductors realized as described above is particularly reliable. Furthermore, the springs 1 can withstand the loads to which they are exposed by a repeated deflection particularly well on account of their local hardening. In detail, the springs have a particularly low setting behavior.Due to an improved setting behavior of the springs and due to an improved spring-force effect, the spring-force clamp 20 can be used for a particularly long time without loss of quality.Reference numerals denote reference numerals1 Spring 2 Spring curve 3 Insertion opening 4 First region 5 Second region 6 Busbar 7 Assembly 8 Laser 9 Laser beam 10 Apex 11 Method for producing a spring 12 Punching of the spring 13 Bending of the spring 14 Local hardening of the spring 15 Method for producing an assembly 16 Punching of the spring and the busbar 17 Bending of the spring and the busbar 18 Form-fitting connection of the spring and the busbar 19 Local heating of the spring 20 Spring force clamp 21 Housing

Claims

Spring (1), in particular for use in a spring force clamp (20), wherein the spring (1) consists at least in regions of spring steel, characterized in that the spring (1) has a first region (4) and a second region (5), wherein the spring (1) has a higher hardness in the first region (4) than in the second region (5).Spring (1) according to claim 1, characterised in that the spring has a hardness in the first region (4) which is greater than 500 HV, which is preferably greater than 510 HV, which is further preferably greater than 520 HV.Spring (1) according to claim 1 or 2, characterised 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.Spring (1) according to one of Claims 1 to 3, characterized in that the first region (4) is realized by a flat or linear or punctiform heat input.Spring (1) according to one of Claims 1 to 4, characterized in that the spring (1) has at least one spring bend (2), and in that the first region (4) of the spring (1) is arranged in the region of the at least one spring bend (2).Spring (1) according to Claim 5, characterized in that the spring curve (2) has an apex (10), and in that the first region (4) comprises the apex of the spring curve.Spring (1) according to one of Claims 1 to 6, characterized in that the spring (1) has been cured in the first region (4) after the forming and in that the spring (1) has not been cured in the second region (5) after the forming.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).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-bending method - subsequent curing of at least one first region (4) of the spring (1) by local heating (14), in particular by means of laser curing.Method (11) according to claim 9, characterised in that during the hardening, the spring (1) is locally heated to a temperature between 200°C and 400°C at least in the first region (4).Method (11) according to either of Claims 9 and 10, characterized in that the heat input takes place in punctiform or linear or planar fashion.Method (11) according to one of Claims 9 to 11, characterized in that the method (11) comprises a production line, wherein after the production step (12) and the forming step (13) the spring (1) is cured (14) directly, preferably by means of laser curing, and is then available directly for assembly.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 positive-locking and / or non-positive-locking and / or firmly-bonded manner.Method (15) for producing an assembly (7) according to claim 13 characterised in that the method (15) comprises the following steps: - production (16) of at least one spring cut part and preferably of at least one further component cut part, - forming (17) of the at least one spring cut part into at least one spring (1) and preferably forming of the at least one further component cut part into at least one further component, in particular by means of a punching-bending method, - connection (18) of the at least one spring (1) and of the at least one further component during or after the production 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.Spring force clamp (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) via 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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