EP2993531A1 - Method for shaping a spring - Google Patents

Abstract

Method for forming a mechanical spring, in particular a spiral spring (1), comprising the steps of i) providing the spring, in particular a spiral spring (1), comprising at least one curve section (100) provided with at least one bending section (1000); thereafter ii) locally heating at least the bending portion (1000) to a first temperature T 1 which is in a half-warming temperature range of the material of the bending portion (1000); and iii) moving the bending section (1000) to introduce a predetermined curve shape into the curve section (100), the movement according to step iii) occurring after or during step ii) and being a warm forging, or wherein the movement after step iii) is timed before step ii) takes place.

Description

TECHNICAL AREA

The present invention relates to a method for forming a spring, in particular a spiral spring for a mechanical movement, according to the preamble of claim 1, a deformed by this method spring and a movement comprising such a spring.

STATE OF THE ART

It is known to provide spiral bending springs for mechanical movements by forming partially with a certain curve shape. The EP 0 911 707 teaches that a raw spiral fixed by heat treatment can be provided with an end curve introduced by cold deformation of the spiral outer coil. For this purpose, with a tool kinks are inflected in the course of the outer spiral of the spiral to be deformed, so that increases the winding distance between the outermost passages in the region of the end curve. The thus cold-worked section is then freed from internal stresses by a thermal aftertreatment. This procedure is time consuming.

PRESENTATION OF THE INVENTION

It is an object of the present invention to provide an improved method for forming a mechanical spring, in particular a spiral spring for a movement, preferably for producing a final curve.

1. i) Bereitstellen der Feder, wobei die Feder einen zur Umformung vorgesehenen Kurvenabschnitt mit mindestens einem Biegeabschnitt umfasst; danach
2. ii) lokale Erwärmung zumindest des Biegeabschnitts, vorzugsweise des ganzen Kurvenabschnitts, auf eine erste Temperatur T ₁, wobei die erste Temperatur T ₁, oberhalb der Raumtemperatur und unterhalb einer Rekristallisationstemperatur T _RK eines Materials des Biegeabschnitts liegt; und
3. iii) Bewegung des Biegeabschnitts, vorzugsweise des ganzen Kurvenabschnitts, zwecks Einbringens einer vorbestimmten Kurvenform in den Kurvenabschnitt,

wobei die Bewegung gemäss Schritt iii) zeitlich nach oder während Schritt ii) erfolgt und eine Halbwarmumformung ist, oder
wobei die Bewegung nach Schritt iii) zeitlich vor Schritt ii) erfolgt.This object is solved by the features of claim 1. Accordingly, a method for forming a mechanical spring, in particular a spiral spring for a movement, specified, comprising the steps:

1. i) providing the spring, wherein the spring comprises a curve section provided with at least one bending section; after that
2. ii) locally heating at least the bending section, preferably the entire curve section, to a first temperature T ₁ , wherein the first temperature T _{1 is} above room temperature and below a recrystallization temperature T _{RK of} a material of the bending section; and
3. iii) movement of the bending section, preferably of the whole curve section, for the purpose of introducing a predetermined curve shape into the curve section,

wherein the movement according to step iii) takes place after or during step ii) and is a warm forging, or
wherein the movement after step iii) takes place before step ii).

In this case, the first temperature T ₁ lies in the half-warm forming region of at least the material of the bending section. The warm forging area joins the hot forming area on the cold side. T ₁ is therefore at least as high as the material-dependent restoration temperature. A typical warm forging temperature T ₁ , for common coil springs is, for example, 300 ° C to 500 ° C. T ₁ is therefore above the room temperature of 20 ° C and below the recrystallization temperature T _{RK of} the material of the bending section. T ₁ is preferably above 100 ° C., the material is thus warmed, and / or T ₁ , is in a range of 30% of the recrystallization temperature T _RK in ° C of the material of the bending section up to this recrystallization temperature T _RK in ° C, preferably in a range of 50% of this recrystallization temperature T _RK in ° C up to 90% of this recrystallization temperature T _RK in ° C. An explanatory calculation example below: 50% of (T _RK = 1000 ° C) is: 500 ° C.

It is particularly preferred if the temperature T ₁ is 50% to 70%, in particular about 60% to 65% of T _RK in ° C.

The "recrystallization temperature T _RK " is a material-dependent temperature, is about 900 ° C to 1100 ° C for common spirals and can be determined, for example, by measuring the temperature dependence of the relative electrical resistance or the heat capacity. For the rough determination of T _RK : T _RK is 40% to 50% of the melting temperature of the material in ° C.

Preferably, the half-warm forming of the bending portion is performed for introducing a predetermined waveform into the curved portion while the bending portion is maintained at the temperature T ₁ . Preferably, the temperature T _{1 is} kept constant for 0.1 second to 100 seconds, preferably for 0.5 seconds to 30 seconds, in particular for 0.5 seconds to 5 seconds.

It is also conceivable that after reaching a certain temperature T _1, the energy supply in the bending section is increased, reduced or interrupted.

The warm forging causes no or less internal stresses and / or no or less undesirable magnetic properties in the deformed portion, i. the bending section, are introduced, as would be introduced by the cold forming and are eliminated in the prior art by downstream tempering.

For example, a typical heating may occur within 1 second to 10 seconds, in particular within 2 seconds. Depending on the material, the energy supply, for example the current supply, can be adapted accordingly. Cooling after heating can also be controlled, for example by reducing the energy supply in a controlled manner.

For example, in a typical material used for common coil springs, PE 4000 has the following percent mass distribution: 38% -40% nickel, 7% -8.5% chromium, <1% beryllium, <1% titanium, <1% manganese, < 1% silicon, wherein a mass percentage of the parts of beryllium, titanium, manganese and silicon together is between 0% and 2%, and the balance is iron, T _{1 is} in the range of 300 ° C to 750 ° C, especially in the range from 550 ° C to 700 ° C or in the range of 550 ° C to 650 ° C, and preferably at 600 ° C to 620 ° C.

Preferably, the spring or the curve portion or the bending portion in step ii) only during 0.1 second to 60 seconds, preferably only for 0.5 second to 10 seconds, preferably only for 0.5 seconds to 5 seconds and especially only for 0.5 seconds to 3 seconds or during Held for 1 to 2 seconds at the first temperature T ₁ and then cooled.

T ₁ is preferably, depending on the material and spring dimensions, chosen so high that the desired effects, in particular a reduction of introduced by the forming magnetic effects or a restoration or relaxation of the Material occurs within the selected time interval. The restoration time at T ₁ is advantageously so short that a minimum or no scale formation or precipitation of intermetallic particles occurs. Moreover, it can be avoided that the material of the spring is too soft. In addition, short times are also advantageous in that an efficient forming process is possible.

It is also possible here to use paramagnetic alloys such as, for example, Nb-Ti alloys. Preferably, the material of the bending portion or the curve portion is a nickel-iron alloy and / or the first temperature T ₁ in the range of 300 ° C to 750 ° C, preferably in the range of 450 ° C to 700 ° C, preferably in the range of 550 ° C to 650 ° C, more preferably in the range of 600 ° C to 620 ° C, and especially at 610 ° C. The bending section or the curve section is therefore heated to the temperature T ₁ before, during or after the movement step which brings the section from the starting position into the desired end position.

The moving step may be a forming step in the sense of warm forging or a deformation or deformation occurring at temperatures below T ₁ , after or during which the bending section is heated until it reaches T ₁ and then, after the movement, held there until the built-up internal stresses in the bent material have degraded and a permanent deformation is completed.

Between heating or semi-warming, it may be provided that the temperature is kept stable by continued constant supply of energy. Heating may also be continued after warm forging to give the material even more time to relax. It is thus possible that the temperature is kept constant at T ₁ during a period of 1 minute to 3 hours after the forming.

It is also conceivable that the temperature of the bending section after reaching T _{1 is} not stabilized, but that after reaching T ₁ quickly makes the transformation, while the heated areas, for example, the spiral belt cool off by itself, but so that the Temperature during the forming is still so high that a warm forging takes place in the context of the present invention, thus resulting in a permanently deformed spring. In this case, it is also possible to provide the heating so strongly above a minimum forming temperature for warm forging in the sense of the present invention, that such cooling during the Preparation for forming specifically involved in the process and it is ensured that the material during the forming is so warm that a warm forging takes place in the context of the present invention.

The invention is based on the finding that a waveform freed of undesired internal stresses and / or magnetic effects instead of two individual working steps (cold forming step and subsequent heat treatment step for relaxation of the material) by means of a half-warm forming or heating of the bending section to T ₁ during the forming step in a spring, in particular in a raw spiral, is einformbar. The forming step comprises the warm forging or the deformation taking place at a temperature below T ₁ as a movement step and the subsequent heat treatment at the temperature T ₁ .

The inventive method, the construction of such internal stresses or undesirable magnetic properties is largely prevented.

Preferably, the spring is a coil spring. By the term "coil spring" is meant a coil spring wound from a spiral spring, in particular a balance spring. The coil spring may extend in one plane (e.g., flat spiral) or in a plurality of planes offset along the axis of the spiral (e.g., a Breguet coil or a cylindrical coil spring). It is, for example, usable as part of the oscillatory system of a mechanical movement. It is also conceivable that this method is used for the forming of other mechanical springs.

wobei

• D: äusserer Durchmesser der Spiralfeder [in: mm],
• d: innerer Durchmesser der Spiralfeder [in: mm]; und
• C: C = (E · h · e³)/(12 · 1) [in: dyn · cm] mit
  • E: Elastizitätsmodul der Spiralfeder [in: N/mm²];
  • h: Höhe des Spiralfederbands [in: mm];
  • e: Dicke des Spiralfederbands [in: mm]; und
  • 1: Länge des Spiralbandes [in: mm].

Die vorliegende Erfindung betrifft vorzugsweise Spiralfedern mit einer CGS-Nummer im Bereich von 0.05 bis 35, insbesondere im Bereich von 0.25 bis 15.The coil springs can be classified in terms of their size in "CGS" classes. The CGS number of a spiral can be calculated as follows: $$\mathrm{CGS}=\mathrm{C}\cdot \left({\mathrm{D}}^{\mathrm{2}}-{\mathrm{d}}^{\mathrm{2}}\right)\left[\mathrm{in}:\mathrm{dyn}\cdot {\mathrm{<figure-callout\; id="3"\; label="cm"\; filenames="imgf0003.png"\; state="\{\{state\}\}">cm</figure-callout>}}^{\mathrm{3}}\right].$$

in which

• D: outer diameter of the coil spring [in: mm],
• d: inner diameter of the coil spring [in: mm]; and
• C: C = (E · h · e ³⁾ / (12 · 1) [in: dyn · cm] with
  • E: elastic modulus of coil spring [in: N / mm ² ];
  • h: height of the coil spring band [in: mm];
  • e: thickness of the spiral spring band [in: mm]; and
  • 1: length of the spiral band [in: mm].

The present invention preferably relates to coil springs having a CGS number in the range of 0.05 to 35, in particular in the range of 0.25 to 15.

By the term "deformation" is meant a production-related deformation of a workpiece, wherein by introducing a bending moment into the material portion to be formed in combination with a heating, a plastic and permanent deformation of this portion is produced.

By "cold forming" at temperatures in the range of room temperature, ie around 20 ° C, disturbances are introduced into the crystal lattice, resulting in undesirable internal stresses in the material. These stresses can be cured by a subsequent heat treatment of the disturbed material structure. This heating creates a relaxation and restoration of the internal structure (relaxation annealing).

By the term "hot working" is meant forming of a portion of the workpiece, wherein the portion to be formed during the forming process is at a temperature above the recrystallization temperature of the material of that portion. Since the recrystallization is a thermally activated process which can be described by an Arrhenius equation, the decomposition of internal stresses takes place even below the critical temperature, the recrystallization temperature T _RK .

According to the method according to the invention, the section to be reshaped can now be heated to the first temperature T ₁ before the deformation. Alternatively, the bending portion may be elastically deformed to assume the desired final shape and then heated to the first temperature T ₁ . Another possibility is that the movement into the final shape and the heating to T _{1 are} carried out in parallel, whereby the two processes do not necessarily have to take the same time.

Typical processing times of the warm forging or the deformation are 0.1 seconds to 100 seconds, in particular 0.5 seconds to 5 seconds. Typical times the heating to T ₁ be about 0.1 second to 100 seconds, more preferably about 2 seconds to 5 seconds. This depends on the cross section or the amount of material, the material composition and the corresponding energy input.

In the inventive deformation occur less magnetic and / or structural disturbances than in the cold forming, since the material already during and after the forming step, ie during cooling, recovered (or. restored). Moreover, lower forces are used for the inventive deformation than for the cold forming of the same material. Furthermore, with the method according to the invention, a more accurate deformation than in the case of hot deformation is possible because the material is less soft.

The curved section is preferably a section of the spiral spring, that is to say a part of the spiral belt, preferably an outer end curve of the spiral spring. The curve portion is the portion which is moved by the deformation with respect to the spiral center. The bending portion is the portion of the curved portion which is plastically deformed. The bending section can extend over the entire curve section or make up only a part of the curve section. It is also possible for a plurality of identical or different bending sections to be arranged in the curved section.

It is preferred if the spring is a spiral spring and the curved portion is an end curve of the spiral spring. Thus, for example, a flat end curve can be formed in a flat coil spring. A Breguet coil may also be formed by the bending section forming a transition of the spiral band from a plane of the coil spring to an axially offset plane. The curve section can therefore also have a vertical bend on.

The cooling step can be performed passively by allowing to cool to room temperature or actively by known heat dissipation techniques.

In a development of the method, the spring is treated before step i) with a further heat treatment.

In the case of an Fe-Ni alloy, for example, for about 60 minutes to 180 minutes, in particular for 120 minutes fixed at a fixing temperature which is higher than T ₁ , preferably also higher than T _RK and depending on the material, for example. In the field from 550 ° C to 700 ° C, especially from 610 ° C to 640 ° C, or at 620 ° C. This fixation is preferably but not necessarily carried out under vacuum or protective atmosphere of, for example, argon and / or nitrogen at a pressure of less than 10 bar. In this way, any internal stresses which exist before the deformation of a curve section according to the invention are removed from the material structure.

The forming according to the present invention may, but need not under vacuum or protective atmosphere of, for example, argon and / or nitrogen at a pressure be made of less than 10 bar.

The bending section, preferably the whole curve section or the entire spring, can be subjected to a further heat treatment after step iii), in which the bending section, preferably the entire curve section or the entire spring, preferably for 1-24 hours to 200 ° C to 400 ° C, in particular to 300 ° C, is maintained.

The curve portion may be equal to or less than two turns, and preferably between a quarter and a half turn, preferably an outer, in particular outermost, turn of the coil spring.

In order to fix the curve section for the movement, ie for the warm forging or the deformation taking place at a temperature below T ₁ , the latter can have at least one first and second gripping section. These gripping sections are then determined in each case. Preferably, these gripping portions are each introduced into a holding element, wherein at the half-warm deformation of at least one of the holding elements is moved to cause the deformation of the bending portion. The determination of the gripping portions in the holding elements can take place by positive engagement or clamping. In principle, a determination along the spiral belt is not necessary, but can be realized by clamping by means of the holding elements. The determination in the radial direction, ie away from the axis of the spiral, can be accomplished by a positive connection, for example. By inserting into a slot or by clamping.

The holding elements preferably have a recess, in particular a slot or a through hole, for introducing the gripping sections. Preferably, both a spatial position and a rotational position with respect to at least one, preferably all three each perpendicular to each other spatial axes can be controlled.

Particularly preferred are holding elements, which are designed as pins. These pins can be suitable by heat conduction and / or for energization. These pins can be detected on a device causing the movement and have a free end with the slot or through-hole. It is also conceivable that a holding element is provided by a pin and another holding element by a tool.

Preferably, the holding elements are electrically conductive and in electrical contact with the preferably electrically conductive spring. So can about the holding elements the energization takes place without additional contacts must be attached. In addition, it is ensured that the current is passed through the corresponding Bestromungsabschnitt the spring. Moreover, the heating can preferably be generated directly by electrical or thermal conduction via these holding elements in the spiral band.

The movement of the at least one retaining element can be effected by changing a rotational position of the retaining element. Alternatively or additionally, the movement may be characterized by a displacement of the retaining element in and / or parallel to a plane of the spring and / or to outside the plane of the spring.

Depending on the desired curve shape, two holding elements can thus be provided, with one or both holding elements being moved for deformation. This movement may be a spatial displacement or rotation about any axis or a plurality of rotations about different axes. The movement can also be a superposition of several such movements. The provision of such holding elements is advantageous because the shape of the curve is thus formed by a movement step; it does not have to be made in two places temporally shifted a kink with a tool, as is done in the prior art, for example. When forming a flat end curve, but it is simply at least one of the holding elements moves so that the waveform introduced after completion of this movement is.

There may be other movable or immovable holding elements to guide the forming generating movement of the blade. It is possible to provide more than two holding elements, with one, two, three or all moving, or some moving and the others not being moved. Thus, for example, two outer of three provided holding elements can be displaced and preferably additionally rotated, while the third holding element located between the two outer holding elements is not moved and stabilizes the movement of the spiral located in the forming.

Preferably then middle holding elements are provided electrically insulating and heat-insulating, so that no voltage or temperature drop due to the middle holding elements occurs.

Moreover, it is conceivable that the holding elements are not moved, but that the deformation comes about by the clamping of the spring in the prepositioned holding elements.

The retaining elements may receive the respective gripping portion at a predefined rotational position relative to an axis transverse to the longitudinal extent of the gripping portion along the spring. For example. the gripping section can be received without additional bending of the spring. It is also conceivable that the orientation of the substantially straight through-hole or slot is at an angle to the longitudinal course of the gripping portion and the spiral band must be bent into the through hole or the slot.

Preferably, the heating to the first temperature T _{1 is} generated by electrical energization of the bending section, in particular of the curved section. Alternative heating methods would be, for example, irradiation with electromagnetic radiation or a contact heat transfer. The current flow generates the corresponding heating due to the material resistance. The energization is done by means of direct or alternating current. DC is preferred. For this purpose, the holding elements are electrically conductive, wherein an electrical voltage across at least one, preferably at least two of the holding elements is applied. An amperage may be in the range of 0.001 ampere and 10 amperes, preferably in the range of 0.01 ampere to 1 ampere, and a voltage, preferably a dc voltage, in the range of 0.1 volt to 25 volts, in particular in the range of 1 volt to 10 volts.

It is also possible to apply an equivalent, material-dependent alternating voltage for supplying energy for the purpose of heating to T ₁ at the energizing section.

The spring may have a substantially rectangular cross-section with a long side of 50 microns to 400 microns, especially 150 microns, and a short side of 10 microns to 60 microns, especially between 20 microns and 45 microns, or 30 microns. In principle, the spring can have any desired cross section.

Instead of working with retaining elements as described above, the deformation step of the hot forging or the deformation taking place at a temperature below T ₁ can also be carried out by means of a molding tool with two pressing jaws movable relative to each other. These pressing jaws are complementary to each other. It may be that only one or both jaws are moved. The jaws may be convex-concave and / or provided with recesses and projections.

In addition, the invention provides a spring, in particular a spiral spring or a clockwork with a spiral spring.

The present invention thus makes the formation of a desired curve shape into a curve section of a spring more efficient, since no subsequent tempering is necessary any more.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1

einen Kurvenabschnitt einer Spirale, welcher in zwei Stifte eingespannt ist und in einer Ausgangslage und einer durch erfindungsgemässe Umformung erreichten Endlage dargestellt ist;

Fig. 2

eine alternative Ausgestaltung der Stifte zur Ausführung der erfindungsgemässen Umformung;

Fig. 3

die Situation nach Fig. 1, wobei die Stifte anders bewegt werden, sodass der Kurvenabschnitt eine andere Endlage einnimmt.;

Fig. 4

die Situation nach Fig. 1, wobei ein weiterer Stift zum Einnehmen einer komplexeren Endlage des Kurvenabschnitts vorgesehen ist;

Fig. 5

eine alternative Umformung mit einem Formwerkzeug mit zwei Pressbacken;

Fig. 6

die alternative Umformung nach Fig. 5 mit einem anderen Formwerkzeug; und

Fig. 7

die alternative Umformung nach Fig. 5 mit einem abermals anderen Formwerkzeug.

Preferred embodiments of the invention will be described below with reference to the drawings, which are given by way of illustration only and are not to be interpreted as limiting. In the drawings show:

Fig. 1

a curved portion of a spiral, which is clamped in two pins and is shown in a starting position and reached by forming the invention end position;

Fig. 2

an alternative embodiment of the pins for carrying out the inventive deformation;

Fig. 3

the situation after Fig. 1 in which the pins are moved differently, so that the curve section occupies a different end position;

Fig. 4

the situation after Fig. 1 wherein a further pin is provided for taking a more complex end position of the curve section;

Fig. 5

an alternative deformation with a mold with two pressing jaws;

Fig. 6

the alternative transformation after Fig. 5 with another mold; and

Fig. 7

the alternative transformation after Fig. 5 with another mold.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 shows a section of a spiral band consisting of a blade 10 which is bent to a coil spring 1. It is the undeformed, so lying in the starting position Blade 10a and the deformed, ie in the final position blade 10 to see. From now on, reference is made only to the blade 10, it is clear from the context whether this is the deformed or the undeformed. The blade 10 has a rectangular cross-sectional shape with a long side of about 150 microns and a short side of about 20 microns to 45 microns, especially 30 microns. FIG. 1 shows a plan view of the short side of the blade 10th

In the starting position, the undeformed blade 10 follows a convexly curved curve and is clamped between two pins 21, 22, which act as holding elements. These pins 21, 22 each have a slot 210, 220. The pins 21, 22 with the slots 210, 220 are dimensioned such that the undeformed blade 10 can be inserted into these slots 210, 220. The pins 21, 22 have a circular cross section, wherein a radius of this circle is 3 to 20 times the length of the short side of the blade 10. A depth of the slot 210, 220 in the direction of an axis of the respective pin 21 or 22 is 0.5 to 10 times the length of the long side of the blade 10. A slot width can be between 2 to 5 times the short side of the Kline 10th be. Other pin cross-sections (polygon, ellipse, ...) or slot dimensions may also be provided.

Functionally, the slot 210, 220 should be dimensioned such that the blade 10 can be inserted into the slot 210, 220 and can be deformed according to the invention by moving at least one of the pins 21, 22.

In a further development, the slots 210, 220 can easily clamp the blade 10. For this purpose, a clamping spring or a clamping screw, but preferably a clamping device with a clamping pliers or other clamping means may be provided (not shown).

To Fig. 1 the orientation of the straight slots 210, 220, ie the rotational position of the pins 21, 22 with respect to the pin axis, is adapted tangentially to the curve of the undeformed blade 10 in initial length. The slots 210, 220 thus run perpendicular to the axis of the pins 21, 22. According to the method according to the invention, a deformation is now introduced into the curve section 100 between the two pins 21, 22 by bending sections of the curve section, ie the bending sections 1000, to change a pitch of the coil spring 1 sections or to guide the spiral belt to another offset with respect to an axis of the coil spring 1 level.

For this purpose, the blade 10 is first heated to a first temperature T ₁ . In a preferred embodiment, the temperature T is increased at least in the bending region 1000 of the curve portion 100 by current introduction into the electrically conductive coil spring 1. For this purpose, an electrical voltage is applied across the curve section 100. Preferably, the pins 21, 22, which define and detect the curve portion 100, are electrically conductive, the voltage then being applied directly to the blade 10 via the pins 21, 22, followed by a current flowing due to the electrical resistance of the conductor the blade 10 is heated.

Local heating can also be generated by other conventional methods such as flame treatment or by contact heat.

The temperature T of the bending section 1000 is locally brought to the first temperature T ₁ . It is particularly preferred if the blade 10 is heated in sections so strongly that it begins to glow brown-red. Preferably, the blade 10 is not heated above 500 ° C to 600 ° C so that it does not become too soft.

As soon as the first temperature T _{1 is} reached, the curve shape is reduced by movement of at least one of the pins 21, 22 Fig. 1 by movement of the second pin 22 along the line of movement 6 in the direction of the arrow 5, molded. Here, the pin 22, depending on the desired shape, rotated and / or moved, whereby the blade 10 is transferred from the initial position to the desired end position. To Fig. 1 If the displacement is in a plane outwards, the rotation is about 20 degrees counterclockwise.

Due to the increased ductility of the heated spiral belt, lower forming forces are required for this type of warm forging than for cold forming. Since this is a warm forging with a material temperature of T ₁ , as described above. It is then no longer necessary at this point to eliminate internal stresses or undesirable magnetic properties due to the deformation by subsequent heat treatment, since the inventive method can show no or less such undesirable effects, as a cold deformation in the formed material. The energization can be carried out until immediately before the movement of the at least one pin 21, 22 or even to the completion of this movement or longer. This may depend on the material and geometry of the coil spring 1.

It is also conceivable that the retaining elements already before clamping the spring are positioned so that they hold the spring in the desired end position, wherein the spring is then deformed during clamping. Thereafter, as described above, it is heated to T ₁ .

It has been found experimentally that for a coil spring 1 with a CGS number of 0.45, a current of I = 0.1 amps at a voltage of approximately U = 0.9 volts will provide the required heating for forming. In a coil spring 1 with a CGS value of 7.5, it has been found that a current of I = 0.2 amps and a voltage of U = 2.3 volts heat the blade 10 optimally.

For the inventive method, it is therefore advantageous if, depending on the material and geometry of the blade 10, a current between 0.01 amps and 1 ampere and a voltage between 0.1 volts and 10 volts are applied to the curve section or to the reshaped curve sections of the coil spring.

• Stromstärke I=0,1 Ampere, Spannung U = 2.9 Volt;
• Stromstärke I = 0.2 Ampere, Spannung U = 2.5 Volt;
• Stromstärke I = 0.3 Ampere, Spannung U = 2.0 Volt;
• Stromstärke I = 0.4 Ampere, Spannung U = 1.8 Volt;
• Stromstärke I = 0.6 Ampere, Spannung U = 1.7 Volt;
• Stromstärke I=1.0 Ampere, Spannung U = 1.5 Volt; und
• Stromstärke I =1.2 Ampere, Spannung U =1.4 Volt.

Diese Werte sind abhängig von der Länge, dem Durchmesser und der Klinge 10 und der Stifte 21, 22.Experiments have shown that with a coil spring with a CGS number of 7.5, the following values can be used for the electrical heating:

• Current I = 0.1 amperes, voltage U = 2.9 volts;
• Current I = 0.2 amps, voltage U = 2.5 volts;
• Current I = 0.3 amps, voltage U = 2.0 volts;
• Current I = 0.4 amps, voltage U = 1.8 volts;
• Current I = 0.6 amps, voltage U = 1.7 volts;
• Current I = 1.0 amp, voltage U = 1.5 volts; and
• Current I = 1.2 amps, voltage U = 1.4 volts.

These values are dependent on the length, the diameter and the blade 10 and the pins 21, 22.

The energized sections may, for example, have a length of 2 millimeters to 20 millimeters.

In FIG. 2 are shown as holding elements two pins 23, 24, which differ in each case by the presence of a passage opening 230, 240 instead of a slot 210, 220 of the pins 21, 22. By providing the passage opening 230, 240, a controlled movement in the direction of the axis of the pin 23, 24 is possible. The gripping sections are better grasped. Such a clamping with the pins 23, 24 thus makes it possible to form a vertical bend from the plane of the spiral spring 1 into a curved section 100. The warm forging is achieved by moving the movable pin 24 in the direction of the arrow 5 from the plane of the coil spring 1. It can additionally be made a rotational movement (not shown). Again, it is so that preferably via the pins 23, 24, which are designed to be electrically conductive, perform the deformation and the recrystallization in one operation. The warm forging after FIG. 2 can be used, for example, in the production of Breguet spirals.

FIG. 3 shows that the curve portion 100, which is delimited by the portion of the blade 10 between the two pins 21, 22, not only as a circle segment is deformable, but that by the corresponding rotational position of the slot 210, 220 of the pins 21, 22 another curve shape can be introduced into the coil spring 1. With the method according to the invention, therefore, a multiplicity of curve shapes can be introduced into the spirals, the position of the pin 21, 22 in the space and / or the axial rotational position of the pin 21, 22 being regulated.

FIG. 4 shows an embodiment of the method, wherein only one pin 21 remains at rest and whose two pins 22, 25 are moved. The rotational positions of the pins 22, 25 are controlled in moving the pins 22, 25 in the plane along the displacement paths 61, 62, 63 so that a desired waveform results from the warm forging. Again, it is a method of warm forging, that is, the blade 10 is in the forming at a temperature T ₁ as described above. By providing more than two pins 21, 22, 25, it is possible to introduce more complex waveforms in the spiral 1.

FIG. 5 shows an alternative embodiment which does not require the use of pins 21-25. However, the pins 21-25 can also be used here to better perform the warm forging. Again, the blade 10 is heated to the first temperature T ₁ , in which case a mold 3 with a first pressing jaw 31 and a second pressing jaw 32 are used. The pressing jaws 31, 32 have complementarily shaped, mutually associated first and second pressing surfaces 310 and 320, which after Fig. 5 are round. By pressing the warm bending portion 1000 of the blade 10, the warm forging is effected. By providing such molds, it is possible to have more complex structures which are not possible in the room due to the displacement of the blade 10 engaging pins 21-25. For heating, the jaws 31, 32 may be correspondingly hot, or again a current is passed through the curve section 100. For the introduction of electricity again pins or other contact elements can be used.

FIG. 6 shows a further embodiment of the inventive method, wherein the heated blade 10 is also inserted between two pressing jaws 33, 34 of a further mold 3. In contrast to the jaws 31, 32 after Fig. 5 have these jaws 33, 34 differently shaped third and fourth pressing surfaces 330 and 340, respectively. The third pressing surface 330 has a recess 331; the fourth pressing surface 340 has a pressing protrusion 341 formed to engage the recess 331. With such a mold 3 after Fig. 6 Relatively small structures can be introduced into the warm blade 10. By this type of deformation according to FIG. 6 For example, it is possible to locally limit the stiffness of the coil spring 1 by introducing structures which are limited to a short section of the blade 10. Short here means a length of up to half a turn or 0.5- to 5-fold, in particular about 2 times the short side of the cross section of the blade 10. Thus, for example, various adjoining sections of the blade 10 by various forms in one certain configuration can be brought so that desired effects on the stiffness of the blade 10 can be achieved.

FIG. 7 shows a further structure, which can be introduced by the pressing surfaces 350, 351 in a warm curve portion 100 of the coil 1.

The spiral spring 1 can therefore be produced in particular by forming the spiral band 10 into a spiral spring 1 and fixing it at 600 ° C. to 630 ° C. for about two hours in vacuo. Thereafter, a half-warm forming of the raw spiral spring 1 is performed, wherein at the half-warm forming at least the bending portion 100 to the first temperature T ₁ , preferably at about 500 ° C, is heated. Alternatively, the coil spring 1 can be elastically deformed so that it assumes a desired end position, whereupon the coil spring 1, that at least the bending portion is heated to T ₁ 1000 and so takes place forming. It is also conceivable that the movement of the spring is made from a starting position into the end position parallel to the heating to T ₁ .

After this transformation, at most a further thermal treatment can be carried out. LIST OF REFERENCE NUMBERS 1 spiral bending spring 10a Blade in starting position 3 mold 10 Blade in end position 31 first pressing jaw 121 first gripping section of FIG. 10 310 first pressing area of 31 122 second gripping section of FIG. 10 32 second pressing jaw 125 fifth gripping section of 10 320 second pressing area of 32 100 curve section 33 third pressing jaw 1000 bending section 330 third pressing area of 33 331 recess 21 first pen 34 fourth pressing jaw 210 first slot in 21 340 fourth pressing area of 34 22 second pen 341 bending edge 220 second slot in 22 350 fifth pressing surface 23 third pin 351 sixth pressing surface 230 third slot in 23 24 fourth pen 5 movement direction 240 fourth slot in 24 25 fifth pen 6, 61, 62, 63 line of movement 250 fifth slot in 25

Claims (15)

Method for forming a mechanical spring (1), in particular a spiral spring for a movement, comprising the steps: i) providing the spring (1), wherein the spring (1) comprising at least one provided for forming curve portion (100) with at least one bending portion (1000); after that ii) locally heating at least the bending section (1000), in particular the entire curve section (100), to a first temperature T ₁ , the first temperature T ₁ , above the room temperature and below a recrystallization temperature T _{RK of} a material of the bending section (1000) ; and iii) moving the bending section (1000), preferably the whole curve section (100), for introducing a predetermined curve shape into the curved section (100), wherein the movement according to step iii) takes place after or during step ii) and is a warm forging, or
wherein the movement after step iii) takes place before step ii). The method of claim 1, wherein the first temperature T _{1 is} above 100 ° C and / or in a range of 30% of the recrystallization temperature T _RK in ° C of the material of the bending section (1000) up to this recrystallization temperature T _RK in ° C, preferably in a range from 50% of this recrystallization temperature T _RK in ° C up to 70% of this recrystallization temperature T _RK in ° C, in particular at 60% to 65% of this recrystallization temperature T _RK in ° C. Method according to one of claims 1 to 3, wherein the material of the bending portion (1000) and the curve portion (100) is a nickel-iron alloy and / or the first temperature T _{1 is} in the range of 300 ° C to 750 ° C. , preferably in the range of 450 ° C to 700 ° C, preferably in the range of 550 ° C to 650 ° C, more preferably in the range of 600 ° C to 620 ° C. is, and in particular at 610 ° C is. Method according to one of claims 1 to 3, wherein the spring (1) or the curve portion (100) or the bending portion (1000) in step ii) only for 0.1 second to 60 seconds, preferably only for 0.5 second to 30 seconds, preferably only for 0.5 second to 5 seconds, and especially for only 2 seconds to 5 seconds of the entire curve portion (100) at the first temperature T ₁ , and then cooled. Method according to one of claims 1 to 4, wherein the spring (1) before step i) is preferably fixed for 100 minutes to 150 minutes, in particular for 120 minutes at a fixing temperature, which fixation temperature in particular in the range of 580 ° C to 630 ° C, preferably in the range of 600 ° C to 610 ° C, or higher than T ₁ . Method according to one of claims 1 to 5, wherein the bending portion (1000), preferably the entire curve portion (100) or the entire spring (1), after step iii) is subjected to a further heat treatment, wherein the bending portion (1000), preferably the entire curve portion (100) or the whole spring (1), while 1 to 24 hours, preferably 250 ° C to 350 ° C, in particular to 300 ° C, held. A method according to any one of claims 1 to 6, wherein the spring (1) is a spiral spring and / or wherein the curve portion (100) is equal to or less than a full turn, preferably equal to or less than half a turn of a preferred one outer, in particular outermost, turn of the spring (1), wherein the cam portion (100) is preferably an end curve of the spiral spring (1). A method according to any one of claims 1 to 7, wherein said cam portion (100) includes at least first and second gripping portions (121, 122; 123, 124; 125); wherein these gripping portions (121, 122; 123, 124; 125) are respectively inserted into a holding element (21, 22; 23, 24; 25), wherein during the movement of the Bending portion (1000) of at least one of the holding elements (21,22; 23,24; 25) is moved to cause the deformation of the bending portion (1000). Method according to claim 8, wherein the holding elements (21, 22; 23, 24; 25) are designed as pins. Method according to Claim 8 or 9, wherein the holding elements (21, 22; 23, 24; 25) have a recess (210, 220; 230, 240; 250), in particular a slot or through-hole, for inserting the gripping sections (121, 122, 123, 124) 125). Method according to one of the preceding claims, wherein the movement of the at least one retaining element (21, 22; 23, 24; 25) is a change of a rotational position of the retaining element (21, 22; 23, 24; 25) and / or a displacement of the retaining element (21; 21, 22, 23, 24, 25) in the room. Method according to one of claims 1 to 11, wherein the heating to the first temperature T ₁ by electrical energization of the bending portion (1000), in particular of the curved portion (100) is generated, wherein the holding elements (21,22; 23,24; 25 ) are preferably electrically conductive and an electrical voltage, preferably a DC voltage, is applied across at least one, preferably at least two of the holding elements (21,22; 23,24; 25), wherein a current strength in the range of 0.001 ampere and 10 ampere, preferably in the range of 0.01 ampere to 1 ampere and a voltage, preferably a dc voltage, in the range of 0.1 volts to 25 volts, in particular in the range of 1 volt to 10 volts. Method according to one of claims 1 to 12, wherein the spring (1) has a substantially rectangular cross section with a long side of 50 microns to 400 microns, in particular of 150 microns, and a short side of 10 microns to 60 microns, in particular between 20 microns and 45 microns, or of 30 microns. Method according to one of claims 1 to 7, wherein the movement of the bending portion (1000) by a molding tool (3) with two relatively movable pressing jaws (31,32; 33,34) is performed. Spring (1), in particular spiral spring, or clockwork with a spiral spring, this spring (1) having been transformed by a method according to one of claims 1 to 14.

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