EP3194091B1 - Method for producing a flat spiral spring, and bending device for producing same - Google Patents

Description

The invention relates to a method for producing a band spring, in particular a spring plate for covering a cooling space of a piston of internal combustion engines, which is designed as at least one annular disk-shaped segment and a bending device for their production.

From the DE 42 08 037 C2 the production of a consisting of two or more segments disc spring is known, which is used as a cover of a cooling chamber for pistons of internal combustion engines. This two-part plate spring closes a cooling oil ring channel which is open toward the piston skirt and is supported on annular channel boundary walls. As a result, a closed cooling oil space is formed, with corresponding holes being provided in the plate spring for the supply and removal of the cooling oil, or the butt joints of the two segments of the plate spring are made correspondingly large. Such segments of the diaphragm spring are individually punched out of a band-shaped material, then set up with a tool and then subjected to a setting process and a subsequent annealing process. The punching of such segments from a band-shaped material has the disadvantage that a considerable waste is produced.

From the JP 2002-307121 A1 a bending device is known, through which a spiral-shaped corrugated spring is produced from a wire-shaped material. The wire-shaped material is bent in an annular disk-like manner, with a drum engaging on the inside of the wire-shaped material and two deflecting devices arranged at a distance from one another being provided at 90 ° apart from the wire-shaped material. Furthermore, offset by another 90 ° offset on the outer circumference further bending devices to align the wire-shaped material wave-shaped. The inner drum and the outer ones Deflection devices are of the same size in diameter, wherein their distance from one another determines the bending radius of the wire-shaped material. This arrangement has the disadvantage that the wire-shaped material has to be of high quality, ie very homogeneous, in order to achieve sufficient bending and alignment of the wire-shaped material.

The JP S55 75818 A , which forms the basis for the preamble of claims 1 and 14, discloses a bending device for producing an annular disc-shaped element, in which a band-shaped material is clamped by a clamping claw on a spiral guide plate and then bent helically around a drum. Following this bending process, the helix is cut into individual ring-shaped segments.

From the DE 17 52 683 B1 shows a bending device for producing helical rings from a wire, in which a trapezoidal in cross-section wire is guided within a helical bending channel around a mandrel and bent helically. In this case, the bending channel is formed by a groove on the mandrel and a bending ring bounding the outer periphery of the bending channel, so that the wire is guided completely in the circumferential groove during the bending operation.

The US 3 729 968 A discloses a bending device in which a band-shaped material is bent by a die helically around a rotatable mandrel. For this purpose, the die on a spiral-shaped guide channel for the band-shaped material, wherein an end portion of the band-shaped material is clamped in a retaining slot on a rotatable drive ring, so that the band-shaped material by rotation of the drive ring and an axial movement of the mandrel spirally bent around the mandrel or is pulled.

From the WO 2006/018313 A1 is a bending device for producing an annular disc-shaped element, in which the deflection of the band-shaped material is effected by a disc-shaped guide plate. For this purpose, the guide plate has a depression which is delimited by a radial circumferential wall. Through this will be the band-shaped material is bent in a circle around a mandrel during a rotation of the plate.

The US 3,608,347 A discloses a bending device for producing annular disk-shaped elements for flanges of pipes. This bending device has a central drum-shaped support element and a plurality of supporting elements arranged thereon. To produce the annular disk-shaped element, a band-shaped material is bent around the central support element, in that the support elements assigned to the central support element form a radial guide for the band-shaped material. Subsequent to the forming process, the formed strip-shaped material is cut into individual ring-shaped segments.

The invention has for its object to provide a method for producing a band spring, which is designed as an annular disc-shaped segment and allows dimensionally accurate production of the segments and a reduction of the crop.

This object is achieved by a method having the features of claim 1. Further advantageous embodiments are specified in the further claims.

By feeding a band-shaped material into a circumferential groove in a drum having a contact surface, and the abutment surface in the drum is oriented at an angle to the longitudinal axis of the drum, so that upon bending and simultaneously setting up the band-shaped material, an inner side wall of the band-shaped material comes to flat contact with the contact surface, or the band-shaped material is fed to a two-part drum with a lower part and a top, wherein on the lower part a shoulder is incorporated as part of a circumferential groove, and a second part of the groove formed by a contact surface of the upper part is, and the upper part is positioned at an angle to the lower part, wherein an axis of rotation of the upper part is arranged at a different angle to the axis of rotation of the lower part. As a result, the engaging on the contact surface of the drum narrow side of the band-shaped material along a predetermined Wrap angle led to the contact surface. Such a manufacturing method uses the entire web width of the band-shaped material for the production of annular disk-shaped segments. By cutting the bent strip-shaped material to a circumferential angle of the segments is determined. For the production of such annular disk-shaped segments, the thickness of the strip-shaped material determining side wall is guided along the contact surface on the lateral surface of the drum and bent by means of at least one deflection of a running in the transport direction or in the X direction of the strip-shaped material rectilinear portion. This bending, which takes place about the vertical axis or Z-axis of the band-shaped material, furthermore has the advantage that the rolling direction of the band-shaped material extends along the annular disk-shaped segment, whereby also improved spring properties and increased strength are achieved.

Preferably, an upper or lower side or both sides of the band-shaped material for aligning the band-shaped material during the bending process along the contact surface of the lateral surface of the drum are guided and aligned by at least one guide element. By the at least one guide element, a deflection of the material can be prevented during the bending of the strip-shaped material about the Z-axis and a forced guidance of the strip-like material along the drum for introducing the bending radius.

According to a first embodiment, the at least one guide element is aligned at right angles to the axis of rotation of the drum or extends in a plane perpendicular to the axis of rotation. As a result, only a bending of the band-shaped material about the Z-axis takes place. The diameter of the drum determines the bending radius of the band-shaped material about the Z-axis.

Alternatively, the at least one guide element is aligned with its guide surfaces inclined relative to an XY plane, the is aligned perpendicular to the axis of rotation or Z-axis of the drum to allow during the bending process of the strip-shaped material to an annular disk-shaped segment at the same time setting up the annular disk-shaped segment. This allows two process steps - the bending and the erection of the ringscheibenfömigen segment - carried out simultaneously.

The band-shaped material is cut to form the segment depending on the required circumferential angle of the band spring. This circumferential or wrap angle can be determined as a function of the number of individual segments of band springs for the application. For example, wrapping angles of about 180 ° can be provided when using two segments of the band spring. Likewise, wrapping angles of at least 60 ° can also be provided. For example, the wrap angle at 120 ° when using, for example, three mutually associated band spring segments. In some cases, wrap angles of greater than 180 ° and a further wrap angle of less than 180 ° can also be formed, which is preferably complementary to the segment with a wrap angle greater than 180 °.

An alternative embodiment of the method provides that the band-shaped material is wound several times around the drum and produced as a spiral. The individual segments can be cut from the spiral either after the spiral has been completely removed from the drum or when the spiral is released from the lateral surface of the drum.

A first embodiment of the method provides that the drum has a bearing surface lying in the lateral surface. This is the simplest embodiment of the bending device and allows the side wall of the band-shaped material to roll on the lateral surface or support during the bending process and forcibly bending the band-shaped material during the bending process by at least one guide element and at least one deflecting element to the drum becomes.

Alternatively, the contact surface is introduced into the lateral surface of the drum of the bending device and recessed and preferably provided a circumferential groove in which an edge of the band-shaped material adjacent to the side wall of the strip material is guided during the bending operation. This circumferential groove can be provided both in an orientation of the band-shaped material to the drum in an XY plane perpendicular to the Z-plane or axis of rotation of the drum and in a plane inclined relative to the XY plane.

Preferably, in an inclined guidance of the strip-shaped material to the lateral surface of the drum is provided that the contact surface of the groove is adjusted and aligned at the installation angle of the strip-shaped material for the production of the segment, so that the side surface can be supported on the base of the groove.

In a further embodiment of the method, in which the band-shaped material bent around the Z axis and guided in an XY plane is cut as a segment, this is introduced into a tool, in particular a bending or setting tool, in order to erect the segment. As a result, a bias voltage can be introduced into the segment for a specific spring characteristic.

According to a further embodiment of the method, the bent and erected from the band-shaped material segment is introduced into at least one punching tool, in which a contour, in particular a final contour of the segment, is punched out. Subsequently, in a further tool a Plandrücken the established segment can be performed or vice versa. Preferably, a follower tool is provided to reduce the handling of the individual segments and to maintain an exact positioning of the segments in the tool. In a punching tool, it is preferable to carry out both a flat back and a simultaneous punching into a final contour.

In a subsequent method step, the contoured segment can be cured in the event that the band-shaped material is provided as a so-called soft band. In the event that that belt-shaped material consists of a tempered material, can be provided immediately and not only after curing tempering or tempering of the material on which a subsequent surface coating or coating of the surface can take place. Such surface treatments may be, for example, oils, phosphates or the like.

In the method for producing the band spring, a material which is rectangular in cross-section or trapezoidal, in particular slightly trapezoidal, is preferably supplied.

In this method of manufacturing the band spring, the band-shaped material is preferably set at a ratio of a width to a thickness equal to or greater than 3. As a result, no compressions can occur during the bending process at the inner diameter and no cracks at the outer diameter.

The object underlying the invention is further provided by a bending device for producing a band spring, which is at least designed as annular disc-shaped segment, in particular for carrying out the method described above, wherein a drum recessed with a contact surface is provided opposite the lateral surface for a narrow side of the band-shaped material and at least one deflection device, which is adjustable at a distance from the drum, wherein the distance corresponds to the width of the band-shaped material and the contact surface of the drum has a radius which corresponds substantially to the inner radius of an annular disc-shaped segment to be bent, dissolved, with a circumferential groove is provided in the drum, which has a bearing surface, and the contact surface is aligned in the drum at an angle to the longitudinal axis of the drum, so that when bending and simultaneously setting up the band-shaped material in nere side wall of the band-shaped material for planar contact with the contact surface comes, or the drum is formed in two parts with an upper part and a lower part and on the lower part a shoulder is incorporated as part of a circumferential groove and a second part of the groove formed by a contact surface of the upper part is, and the top in is positioned at an angle to the lower part and a rotational axis of the upper part is arranged at a different angle to the rotational axis of the lower part. This bending device has the advantage that the curved, band-shaped material is guided with its inner narrow side along the drum, whereby a more precise introduction of the radius is made possible. Due to the at least one deflection device which is associated with the drum, a guidance of the strip-shaped material along the drum is made possible even with increasing wrap angle of the strip-shaped material. As a result, a widening of the curved band-shaped material is prevented. Thereby, the drum can be formed as a cylindrical body. Alternatively, the contact surface can be recessed with respect to the lateral surface of the drum and preferably a peripheral groove can be formed in the lateral surface. As a result, at least one edge region of the band-shaped material adjoining the narrow side can be guided through the drum so that the inner circumference of the band-shaped material can not escape in or against a Z-axis of the drum. By the longitudinal axis of the drum aligned at an angle contact surface can during the bending of the annular disk-shaped segment, a further step, the installation of the segment, are integrated. Due to the two-part design of the drum, a simplification in the production of different thicknesses of the strip-shaped material can be made possible by the distance between the upper part and the lower part is adjustable.

Furthermore, the depth of the groove in the drum is adapted to the width of the band-shaped material, wherein at least 50% of the width of the band-shaped material is received in the groove. As a result, a groove guidance of the strip-shaped material can take place through the drum, whereby additionally guide elements for aligning the strip-shaped material with the drum can be dispensed with.

• Figur 1a eine schematische Ansicht von oben auf zwei Bandfedern,
• Figur 1b eine schematische Schnittansicht entlang der Linie I-I in Figur 1a,
• Figur 2a eine perspektivische Ansicht eines bandförmigen Materials zur Herstellung einer Bandfeder,
• Figur 2b eine schematische Seitenansicht einer alternativen Ausführungsform zu Figur 2a,
• Figuren 2c bis 2e schematische Ansichten von Verfahrensschritten zur Herstellung der Bandfeder gemäß den Figuren 1a und 1b,
• Figur 3 eine schematische Seitenansicht des Verfahrensschritts gemäß Figur 2d,
• Figur 4 eine weitere schematische Seitenansicht einer alternativen Ausführungsform zu Figur 3,
• Figur 5 eine schematische Seitenansicht einer weiteren alternativen Ausführungsform zu Figur 3,
• Figur 6 eine schematische Seitenansicht einer weiteren alternativen Ausführungsform zu Figur 3,
• Figur 7 eine schematische Ansicht einer weiteren alternativen Ausführungsform zu Figur 6,
• Figur 8 eine schematische Ansicht einer weiteren alternativen Ausführungsform zu Figur 7,
• Figur 9 eine schematische Ansicht einer weiteren alternativen Ausführungsform zu Figur 3 und
• Figur 10 eine schematische Ansicht einer alternativen Ausführungsform einer Trommel für eine Biegeeinrichtung.

The invention and further advantageous embodiments and developments thereof are described in more detail below with reference to the examples shown in the drawings and explained. The The description and the drawings to be taken features can be applied individually according to the invention or to several in any combination according to the invention. Show it:

• FIG. 1a a schematic view from above of two band springs,
• FIG. 1b a schematic sectional view taken along the line II in FIG. 1a .
• FIG. 2a a perspective view of a strip-shaped material for producing a ribbon spring,
• FIG. 2b a schematic side view of an alternative embodiment to FIG. 2a .
• FIGS. 2c to 2e schematic views of process steps for the production of the band spring according to the FIGS. 1a and 1b .
• FIG. 3 a schematic side view of the method step according to Figure 2d .
• FIG. 4 another schematic side view of an alternative embodiment FIG. 3 .
• FIG. 5 a schematic side view of another alternative embodiment to FIG. 3 .
• FIG. 6 a schematic side view of another alternative embodiment to FIG. 3 .
• FIG. 7 a schematic view of another alternative embodiment to FIG. 6 .
• FIG. 8 a schematic view of another alternative embodiment to FIG. 7 .
• FIG. 9 a schematic view of another alternative embodiment to FIG. 3 and
• FIG. 10 a schematic view of an alternative embodiment of a drum for a bending device.

In FIG. 1a is a schematic view from above of two band springs 11, which are each formed as an annular disk-shaped segment 12. The two band springs 11 may form an annular disc in their arrangement to each other, for example can be used as a cover of a cooling oil groove on a piston for internal combustion engines. In this case, the respective ends of the band springs 11 can form a gap in the arrangement in the cooling oil channel to allow an addition or discharge of the cooling liquid or an oil.

In FIG. 1b is a schematic sectional view taken along the line II in FIG FIG. 1a which shows that the segments 12 are set up in the exemplary embodiment. This means that an inner diameter 14 is outside or above a support plane of the outer diameter 15 of the segments 12, so that the segments 12 have a plate spring-shaped arrangement. These segments 12 are preferably formed annular disk-shaped. The wrap angle of the segments 12 is dependent on the number of segments to be used and the areas to be covered. The segments 12 may have specifically shaped end portions 16 which are adapted to the installation situation to lie flush against each other or to form a gap of predefined width. Likewise, these on the outer or inner diameter correspondingly adapted contours or within the segment surface, for example, have holes 17 or other entries, punched holes, contours or the like. The segment 12 has an upper side 18 and a lower side 19. These are bounded on the inner diameter 14 by an inner side wall 20 and on the outer diameter 15 by an outer side wall 21.

These segments 12 are preferably made of a band-shaped material 23, which has an example in FIG. 2a illustrated rectangular cross-section comprises. Such band-shaped materials are preferably produced by rolling. It is provided that a width b comprises a multiple of a thickness or height h. At least the ratio b / h ≥ 5, in particular b / h ≥ 10. The band-shaped material 23 may be formed as a roll or in the form of individual strips. To simplify the following explanations, reference is made to the US Pat FIG. 2a represented coordinate system reference taken, wherein the orientation of the coordinates may be different from the illustrated spatial directions.

In FIG. 2b an alternative embodiment of a cross section for a band-shaped material 23 is shown, which as well as the in FIG. 2a shown material - can find use. In this cross section, this is only slightly trapezoidal, so that an inner side 20 is thinner than the outer side 21 is formed.

To produce the band spring 11 is made of a strip-shaped material 23 according to Figure 2a or 2b a bending device 27 is provided, which in a plan view and in individual steps in the Figures 2c, 2d and 2e in a side view as well as in FIG. 3 is shown.

The bending device 27 comprises a drum 29 which is rotatably driven about a preferably fixed axis of rotation 31. This axis of rotation 31 may be aligned in the Z direction. Spaced apart from the drum 29, at least one deflecting device 32 is provided, which is designed, for example, as a roller or roller and is preferably also rotatable about a rotation axis parallel to the axis of rotation 31. The bending device 27 further comprises at least one guide element 33 with at least one sliding surface 34, which serves to guide and align the strip-shaped material 23 to the contact surface 37 of a lateral surface 36 of the drum 29. In this case, the guide element 33 may have fixed sliding surfaces 34. Alternatively, the sliding surfaces 34 may also be formed by rollers or rollers that are rotatable or circumferential.

Hereinafter, the production of a segment 12 according to the FIGS. 1a and 1b further discussed:
In a first method step according to Figure 2c the strip-shaped material 23 is tangentially fed to a lateral surface 36 of the drum 29. An inner side wall 20 comes to rest against the contact surface 37 of the lateral surface 36 of the drum 29. The upper and lower sides 18, 19 of the band-shaped material 23 are aligned perpendicular to the axis of rotation 31. In the presentation according to Figure 2c For example, the axis of rotation 31 may be the Z axis, but also aligned in an XY plane his. The drum 29 may preferably be rotatably driven by a drive. At the same time the band-shaped material 23 is further promoted according to arrow A, so that it is bent over the deflecting device 32 about its vertical axis or Z-axis and the inner side wall 20 continues to come to rest on the lateral surface 36. The inner side wall 20 is thereby compressed, and an outer side wall 21 is thereby stretched. The radius of curvature or bending radius of the segment 21 is dependent on the material, the thickness and / or the width of the band-shaped material. For fixing and alignment of the band-shaped material 23 to the drum 29, for example, a guide member 33 is provided so that the band-shaped material, as for example in FIG. 3 is shown, with the side surface 20 rests against the lateral surface 36 and the band-shaped material 23 about the narrow side - that is, the inner side wall 20 - is bent. Upon further feeding of the strip-shaped material 23 according to FIG. 2e For example, a further bending of the band-shaped material 23 about the Z-axis, so that, for example, a 180 ° bend is achieved. The number and arrangement of the deflection devices 32 and / or the guide elements 33 is dependent on the bending radius, the material used, the material width and / or other parameters.

After a front end of the band-shaped material 23 comprises a sufficient wrap angle, a cut is made in the region of the feed of the strip-shaped material 23 to the drum 29 in order to cut the segment 12.

Alternatively, the length of the band-shaped material 23 may be predetermined, so that individual strips of the band-shaped material 23 are supplied to the predetermined length of the bending device 27 and a separation of the segment 23 may be omitted from the band-shaped material.

A further alternative embodiment provides that a band-shaped material 23 is supplied and the band material bent around the drum 29 forms helically or helically around the drum 29 and is discharged upward or downward, so that either when taking out the spiral relative to the lateral surface 36, a cutting operation takes place or after the complete removal of the spiral from the drum 29, the segments 12 are cut.

In this first embodiment of the drum 29 of the bending device 27 is provided that this has a flat, or smooth outer surface 36 and the contact surface 37 is located in the lateral surface 36, as shown in FIG. 3 is shown. A contact surface 37 determining radius R of the drum 29 corresponds to an inner radius r _{i of} the segment 12, as shown for example in the FIGS. 2e and 1a is shown. In the embodiment according to FIG. 3 the radius R of the lateral surface 36 corresponds to the radius of the abutment surface 37.

An alternative embodiment of the drum 29 of the bending device 27 is shown in FIG FIG. 4 shown. In the lateral surface 36, the abutment surface 37 is introduced and thereby forms, for example, a circumferential groove 38, which is preferably adapted in the width of the height h of the band-shaped material to be processed 23, so that this band-shaped material 23 with the inner side wall 20 in this groove 38th held and caught in the edge region of the top 18 and bottom 19 of the segment 12. The depth of the groove 38 is preferably dimensioned in this embodiment such that only a narrow edge region of the top and bottom 18, 19 engages in the groove 38. The depth of the groove 38 is formed by the radius of the contact surface 37, which in turn corresponds to the inner radius r _{i of} the segment 12 to be produced. Alternatively, the groove 38 can also be formed such that the wall sections formed between the lateral surface 36 and the abutment surface 37 are also formed flat V-shaped or greatly expand starting from the abutment surface 37 to the lateral surface 3, so that, for example, no guide function the top and bottom 18, 19 of the strip-shaped material 23 is given.

In FIG. 5 is an alternative embodiment to FIG. 4 shown. The contact surface 37 of the drum 29 in this case has a depth which is at least over half the width of the strip-shaped material 23rd extends. Advantageously, a groove 38 is formed whose width corresponds to the material thickness of the material 23 or is slightly larger. In this embodiment, the guide elements 33 can be omitted, since due to the depth of the groove 38, the groove-forming edge portions form the guide elements 33. Only by the deflection device 32, the band-shaped material is held in the groove 38 of the lateral surface 36.

In FIG. 6 a further alternative embodiment of the drum 29 of the bending device 37 is shown. With this guide form is deviating too FIG. 5 The lower part 41 has a shoulder 44 on which the abutment surface 37 is provided, the shoulder 44 together with the upper part 42 again forming the groove 38. This embodiment has the advantage that, depending on the setting of the distance of a contact surface 43 on the upper part 42 to the lower part 41, the width of the groove 38 is variable.

This alternative embodiment according to FIG. 6 may also include a groove 38, which in FIG. 4 is shown and described.

In FIG. 7 a further alternative embodiment of the bending device 27 is shown, this embodiment in the construction of the two-piece drum 29 according to FIG. 6 equivalent. In this embodiment in FIG. 7 the axis of rotation 31 of the upper part 42 is arranged at a different angle to that of the lower part 41. Preferably, the upper part 42 and the lower part 41 are rotatably connected to each other by a universal joint. The upper part 42 is variable at a distance from the lower part 41 for adjusting the groove width. Thus, the upper part 42 is arranged at an angle to the lower part 41, wherein a contact surface 46 is formed on the outer edge of the upper part and engages the band-shaped material 23 and this holds down to the support surface or the support surface on the shoulder 44. In this two-part embodiment of the drum 29, in turn, the guide element 33 can be dispensed with. In addition, by this embodiment, a simple threading of the band-shaped material 23 into the groove 38, which in the region of the inclined to each other Sections of the upper part 42 and the lower part 41 is formed. Characterized in that the upper part 42 and the lower part 41 rotationally fixed and aligned at an angle to each other, this threading can be facilitated and achieved. In addition, one or more baffles 32 may be provided as in the previously described embodiments to effect the bending of the belt 23 around the Z axis.

In these embodiments described above, a segment 12 is produced, which is designed as a planar element. To take a form, as in FIG. 1b is shown, it is necessary that these segments 12 are then inserted into a tool and set up by a pressing or bending operation. In a subsequent or in a preceding step, a contour in the segments 12 is introduced by a punch, such as the end portions 16 and / or holes 17 or the like. After setting up the segment 12 is in a further tool a Plandrücken for setting the segment 12. Unless previously no contour or final contour was introduced into the segment 12, after setting up the segment, both the final contour and the Plandrücken in one step a punching and setting tool are introduced.

In subsequent work steps, tempered or tempered and surface treatment and / or surface coating for the completion of the segment can be carried out as a strip-shaped material 23 in a tempered material. If a soft band is used as the starting material for the band-shaped material 23, hardening takes place after setting up / punching and, subsequently, tempering and optionally a surface treatment.

In FIG. 8 is an alternative embodiment of the bending device 27 to FIG. 7 shown. In this embodiment, the abutment surface 43 is inclined on the shoulder 44 of the lower part 41 and the contact surface 46 or contact surface of the upper part 42 or the angular orientation of the upper part 42 to the lower part 41 adapted thereto. This can help in the formation of a annular disk-shaped segment 12 at the same time a setting up of the annular disk-shaped segment 12 can be achieved, so that in comparison to the above under FIG. 7 described method can be saved one step.

In FIG. 9 an alternative embodiment of the drum 29 of the bending device 27 is shown, which allows an alternative method for producing the band spring 11. The supply of the strip-shaped material 23 according to Figure 2c also takes place in the drum 29 according to FIG. 8 , Also the further steps described in the Figures 2d and 2e such as FIG. 3 take place in this embodiment, wherein in the steps according to the Figures 2d and 2e in a drum 29 according to FIG. 8 at the same time for setting up the strip-shaped material 23 about the Z-axis, a setting up of the strip-shaped material 23 is achieved. For this purpose, for example, the at least one guide element 33 with its sliding surfaces 34 is not aligned at right angles to the axis of rotation 31, but at an angle thereto, which is determined by the degree of desired placement of the segment 12, ie by the distance of the height of the inner diameter 14 relative to a support surface of the outer diameter 15. It is preferably provided in the simultaneous bending and erection that in the lateral surface 36 of the drum 29, a circumferential groove 38 is introduced to allow a secure support and guidance of the inner side wall 20 of the band-shaped material 23. In this case, the groove 38 preferably has a base surface 49, which allows the inner side surface 20 preferably rests flat against the base surface 49 and is supported thereon. This base 49 is thus inclined relative to the parallel orientation to the axis of rotation by the angle by which the sliding surfaces 34 are inclined relative to a perpendicular orientation to the axis of rotation.

In the FIG. 9 illustrated drum 29 may also be formed in two parts with a lower part 41 and an upper part 42, wherein the parting plane analogous to that in FIG. 6 can lie.

In FIG. 10 an alternative embodiment of a drum 29 is shown. This drum 29 has in the lateral surface 36 a contact surface 37, which is aligned parallel to the longitudinal axis and extending in a plane perpendicular to the longitudinal axis of the drum 29. Based on this, the contact surface 37 spirals upwards. By such a drum 29, a band spring can be made with several turns as a spiral belt spring. Once the topmost turn leaves the drum 29, it can be cut off. In this case, the cut can also be made only after the lead out of the desired number of turns with respect to the top of the drum 29.

By the method according to the invention, the waste in the production of the segments 12 for the strip spring 11 is considerably minimized, since the entire bandwidth is used to form the segment 12 and thus a considerable cost savings is associated.

Claims (15)

1. Method for producing a leaf spring, in particular a spring steel sheet for covering a cooling chamber of a piston of internal combustion engines, which is at least formed as a washer-shaped segment (12)

   - in which a band-shaped material (23) is fed into a bending device (27) which comprises at least one drum (29) which rotates around an axis of rotation (31),

   - in which the band-shaped material (23) is fed in in a tangential orientation to the shell surface (36) of the drum (29), so that a side wall (20) that determines the thickness of the band-shaped material (23) is in contact at least in sections with a contact surface (37) on the shell surface (36) of the drum (29),

   - in which the contact surface (37) of the drum (29) comprises a radius which substantially corresponds to an inner radius of the band-shaped material to be bent (23) to the segment (12), and

   - in which at least one diverting mechanism (32) is orientated at a distance to the drum (29), so that the band-shaped material (23) is forcibly guided between the drum (29) and the diverting mechanism (32), and by means of which the band-shaped material (23) of the drum (29) is subsequently bent,
   characterised in that the band-shaped material (23)

   - is feeded to a circumferential groove (38) in the drum (29) which comprises the contact surface (37) and the contact surface (37) is orientated in the drum (29) at an angle to the longitudinal axis (31) of the drum (27), so that when the band-shaped material (23) is bent and simultaneously raised, the inner side wall (20) of the band-shaped material (23) comes into flat contact with the base (37), or

   - the band-shaped material (23) is feeded to the drum (29) formed in two parts with a lower part (41) and an upper part (42), wherein a ledge (44) is introduced on a lower part (41) as part of the circumferential groove (38), and a second part of the groove (38) is provided by a contact surface (46) of the upper part (42) and the upper part (42) is positioned at an angle relative to the lower part (41), wherein a rotation axis (31) of the upper part (42) is provided in an angle different to rotation axis (31) of the lower part (41).
2. Method according to claim 1, characterised in that an upper side (18), an under side (19) or both sides (18, 19) of the band-shaped material (23) are guided and orientated by means of at least one guiding element (33) for the radial orientation of the band-shaped material (23) relative to the contact surface (37) of the drum (29) .
3. Method according to claim 1, characterised in that the band-shaped material (23) is trimmed after bending around a predetermined circumferential angle of the contact surface (37) of the drum (29) for the formation of the washer-shaped segment (12) on the drum (29).
4. Method according to claim 1, characterised in that the band-shaped material (23) is wrapped around the drum (29) several times and produced as a spiral, and is then preferably cut into segments following its exit from the drum (29) or the spirals (12).
5. Method according to claim 1, characterised in that the band-shaped material (23) is fed into the drum (29) with a contact surface (37) situated in the shell surface (36).
6. Method according to claim 1, characterised in that the band-shaped material (23) is fed into the drum (29) with a contact surface (37) recessed relative to the shell surface (23), in particular in a circumferential radial groove (38) in the contact surface (37) arranged in the shell surface (36).
7. Method according to claim 6, characterised in that the contact surface (37) is orientated at an angle of less than 45° relative to the longitudinal axis (31) of the drum (29).
8. Method according to claim 3, characterised in that at least one segment (12) of the band-shaped material (23) is introduced and raised in a tool.
9. Method according to claim 1 or 8, characterised in that the segment (12) that is bent from the band-shaped material (23) and preferably raised is introduced into at least one punching tool, and an end contour of the segment (12) is punched out, and subsequently plane pressing of the raised segment (12) is carried out in an additional tool, or vice versa, or both are carried out simultaneously in the punching tool.
10. Method according to claim 9, characterised in that the segment (12) cut into its end contour is hardened.
11. Method according to claim 9, characterised in that the segment (12) cut into its end contour is tempered and/or preferably a surface annealing or surface coating procedure is carried out.
12. Method according to one of the previous claims, characterised in that a material (23) which is of a rectangular or trapezoidal shape in the cross-section is fed into the bending device (27).
13. Method according to claim 1, characterised in that the band-shaped material (23) is used with a ratio of a width to thickness of equal to or greater than 3.
14. Bending device to produce a leaf spring which is formed at least as a washer-shaped segment (12), in particular for carrying out the method according to one of the claims 1 to 13, wherein a drum (29) having a contact surface (37) recessed to the shell surface (36) of the drum (29) is provided for an inner narrow side (20) of the band-shaped material (23), to which at least one diverting mechanism (32) is assigned, the distance of which from the drum (29) is adjustable, which corresponds to the width of the band-shaped material (23), wherein the contact surface (37) of the drum (29) has a radius which substantially corresponds to the inner radius of a segment (12) to be bent, characterised in

    - that a circumferential groove (38) is provided in the drum (29) having a contact surface (37), which is positioned at an angle to the longitudinal axis (31) of the drum (29) so that when the bend-shaped material (23) is bent and simultaneously raised, the inner side wall (20) of the bend-shaped material (23) comes into flat contact with the contact surface (37), or

    - the drum is formed in two parts with a lower part (41) and a upper part (42), wherein a ledge (44) is introduced on the lower part (41) as a part of the circumferential groove (38) and a second part of a groove (38) is provided by a contact surface (46) of the upper part, which is provided flat or in an angle to the lower part (31), wherein a rotation axis (31) of the upper part (42) is provided in a different angle to the rotation axis (31) of the lower part (41).
15. Bending device according to claim 14, characterised in that the depth of the groove (38) is adapted to the width of the band-shaped material (23) so that at least 50% of the width of the band-shaped material (23) is taken into the groove (38).

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