MXPA00009627A - Apparatus for the production of pocketed coil springs - Google Patents

Abstract

There is described apparatus for the production of pocketed coil springs. The apparatus comprises a coiling section in which a coil is formed from wire (1) fed to the coiling section, said coiling section comprising coiling elements (2, 3, 4, 5) whose position and/or orientation determines the form of said coil, and an encapsulation section in which the coil is inserted between juxtaposed sheets of material and in which the sheets of material are joined together to form a pocket enclosing the coil. The apparatus further comprises programmable control means (8) operably linked to said coiling elements (2, 3, 4, 5) in such a way as to control the position and/or orientation of the coiling elements (2, 3, 4, 5).

Description

APPARATUS FOR THE PRODUCTION OF SPIRAL SPRINGS IN CAVIDADES DESCRIPTIVE MEMORY This invention relates to an apparatus and methods for the production of spiral spring cavities, and spring assemblies in cavities. Coil springs in cavities, that is to say the series of springs included within fabric cavities that are joined in their side seams, have a wide use in the elaboration of mattresses, cushions and the like. The devices for the production of spiral springs in cavities generally comprise two sections: a winding unit where the spiral is formed and an encapsulation section where the spiral is inserted between two layers of material that are joined together to form a spiral. cavity where the spring is included. Wire winding is commonly achieved by the interaction of three components: feeder cylinders that push the wire through the furler, a so-called "finger" that regulates the diameter of the spring when it is formed and a so-called "separator" that controls the separation. The relative movements of these components define the pattern of the spring that is forming.

Conventionally, synchronization is achieved by a complex arrangement of gears and cams, making the readjustment between one product and another a long operation that requires high levels of training and experience. As a result, the starting economic resources are high and the response to special customer requirements is low. The development of new spring designs is difficult, often depends on the creation of new cam profiles on a trial and error basis. In addition, the maximum length of the spring that can occur frequently is very limited. The encapsulation section depends on the insertion of fully compressed springs between the sheets of material, commonly a folded sheet of non-woven fabric, which is subsequently stitched or welded to produce the springs in individual cavities. The synchronization of this section also depends on mechanical devices such as cams, welds and clutches, which require a readjustment between products, resulting in a loss of productivity and high maintenance cost. Now improvements have been developed in the apparatuses and methods for the production of coil springs in cavities that superimpose or mitigate substantially the aforementioned drawbacks. According to a first aspect of the invention, the apparatus for the production of spiral springs in cavities comprises a winding section in which a spiral is formed from the feeding of a wire towards the winding section, said winding section comprises winding elements whose position and / or orientation determines the shape of said spiral, and an encapsulation section wherein the spiral is inserted between sheets of juxtaposed material which are joined together to form a cavity where the spiral is included, in wherein said apparatus further comprises programmable control means operably linked to said winding elements to thereby control the position and / or orientation thereof. The apparatus according to the invention is useful mainly because the programmable control means can synchronize all the operations of the apparatus, thus eliminating the change of gears, cams, clutch, etc. The time of change between products is reduced to seconds instead of hours, with consequent benefits for productivity and response, better quality, lower quantities of starting material and a reduced work in inventories in advance. The development of new products and extensions of the product scale can be achieved much more easily without any significant loss of material or time. In accordance with another aspect of the invention, there is a method for producing spiral springs in cavities, whose method comprises the steps of: a) establishing the positions and / or orientations of the winding elements in the winding section of the apparatus in accordance with a first aspect of the invention, b) feeding the wire through the winding section winding so as to form a spiral, c) separating said spiral from said wire, d) compressing said spiral, e) inserting said spiral between sheets of juxtaposed material, and f) joining said sheets of materials to encapsulate said spiral. The programmable control means preferably comprises a programmable logic controller by which computer numerical control (CNC) of the winding section is achieved. Preferably, the logic controller drives a drive means, most preferably servomotors, by means of which the positions and / or orientations of the winding elements can be modified. Preferably, control of the winding unit is exerted by three servomotors: one for the wire feed cylinders, one for the winding element ("finger") that controls the diameter of the spring and one for a winding element (" separator ") that controls the separation of the spring.

Most preferably, the control means stores a number of arrangements or tables of data that determine the position of the finger and spacer shafts (slaves) in relation to the position of the axis of the feeder cylinder (master), for each spring profile. Suitable boards can be prepared for each type of spring to be manufactured, and the appropriate board can be selected before beginning any particular type of spring. Each table can consist of many data points, for example several thousand data points, resulting in complete control of the spring to be formed. To facilitate the creation and modification of the tables, they can be created using a computer spreadsheet. This also allows the visualization of a graphic representation of the movements of the axes relative to each axis before downloading the table to the logic control. The use of spreadsheets allows total flexibility in the desired spring profile, for example for improvement purposes. However, for established spring designs, they can be adapted simply to feed the desired separation data and diameter (s). Any additional spring parameters, for example, the number of convolutions or diameter modifications, can be fed directly through the control board. This improves the changes and allows a simple correction for the variation in wire properties, etc.

After having formed each spring, the servomotor of the feed cylinder shaft preferably stops completely to allow the wire to be cut, for example by means of a pneumatic cutter. This is in contrast to a traditional winding machine where, due to the inertia of the system, the movement of the wire pauses by moving the cylinders apart from each other, while continuing to rotate. This requires considerably more parts that move and that may present some mechanical failure. The apparatus of the present invention makes it possible to achieve higher production speeds than a conventional reel. By producing longer springs, this higher speed can lead to instability in the spring, while it is being formed, which can result in high machine speeds. This problem can be reduced or eliminated by decreasing the excessive oscillations of the springs. This can be achieved by providing magnetic means at the exit of the winding unit. The magnetic medium couples the spring when it leaves the winding unit, thus decreasing the number of oscillations of the spring allowing the production of springs of greater length. At the time, this allows the development of an assembly of springs in cavities of greater depth to provide greater comfort to users of mattresses or similar that incorporate such assemblies. It is believed that the provision of such magnetic means at the exit of the reel is novel and represents a further aspect of the invention.

Preferably, the magnetic means comprises one more electromagnets, preferably the spring is mechanically removed from the magnetic medium when transporting it to the encapsulation section. The invention allows the production of longer springs, and therefore spring assemblies in cavities deeper than what had been possible until today. Thus, in accordance with another aspect of the invention, a spring assembly is provided in cavities having a depth of 20 cm or more. The depth of the cavities can be up to 30 cm or even more in some applications, the typical depths being approximately 21 cm, 24 cm and 25 cm. Because the springs in such spring assemblies are limited within the cavity in a somewhat compressed state, the length of the same spring, in an uncompressed condition, will be more or less greater than the depth of the cavity. A spring for use in a 21 cm deep cavity can, for example, have a non-compressed depth of approximately 25 cm. Preferably, the programmable control means is also operably linked to the encapsulation section, in particular to the control of material movement through said unit. Preferably, a servo motor additionally controls the movement of the material, the increase of such motor corresponding to the depth of the desired cavity, which can therefore be adjusted automatically to adapt the diameter of the spring.

The means by which the springs are transferred to the encapsulation unit and inserted between the sheets of material may be conventional in general. Preferably, the springs are loaded in successive radial arms of a rotation wheel. The springs are preferably compressed mechanically as they are conveyed to the encapsulation section so that they are substantially completely compressed by inserting them between the sheets of material. Most preferably, the compressed spring is transferred to a tilting cartridge within which they are conveyed to the encapsulation sections. The material in which the cavities are formed can have any suitable shape. For example, the material can be a woven or non-woven fabric. The cavities in the fabric can be formed of any suitable means. Such means include stitching, but it is preferred to form the cavities by heat sealing two sheets of material. For this reason, it is preferred that the material be a thermoplastic fabric, and in particular a non-woven thermoplastic material. A suitable material is a non-woven polypropylene. Most preferably, the two sheets of material are formed by folding a single sheet having a width approximately twice the desired depth of the cavities. In such a case, each cavity is defined between two transverse welds and a longitudinal weld that closes the open end of the cavity through which the spring has been inserted.

The welding of the two sheets of the material can be carried out in any suitable way. However, it is preferred to use ultrasonic welding. The welds are preferably interrupted rather than continuous, and are therefore most preferably formed using ultrasonic welding arms with appropriately formed edges, eg, crenellated, low. It is particularly preferred that each transverse weld be formed by a plurality, very preferably very much a pair of crenellated welding arms, and in particular by a plurality of welding arms disposed side by side, that is, with their lower edges disposed collinearly. It is believed that this arrangement is novel and represents a further aspect of the present invention, as well as a method of producing spiral springs in cavities using such an arrangement. It allows the production of significantly deeper cavity units, while maintaining a set of reserves, etc. In addition, wear of the arm for welding caused by misaligned springs could occur, this will be restricted to the adjacent ends of the two arms, which in turn can be turned 180 °, avoiding the need to polish them again. The transverse welds must be formed separately from the center of the springs, since they are introduced into the encapsulation section, which is equal to a whole number of cavity widths plus half the width of the cavity. Since the cavity width can be changed to accommodate a different type of spring, it is preferred that the position of the welds be adjustable to meet this requirement. In this way, means are preferably provided for modifying the position of the placement of the transverse welding means relative to the insertion point of the springs in the encapsulation unit. In general, if the welds will form at a distance of (n + 0.5) times the width of the cavity (where n is an integer), then the position of the welding means needs to be adjustable on a scale of (n + 0.5 ) times the difference between the smallest and largest widths of the cavity that will form. For example, if the cavity width varies between 8 and 10 cm, and the welds are formed with a width of 2.5 cm cavity from the point of encapsulation of the springs, then the welding medium should be moved on a scale of minus 5 cm The welding means can be slidably mounted on suitable guide rails and can be operated by a suitable rack and pinion mechanism or the like. The required position of the welding means can be calculated automatically by means of control, and the position of the welding means can be modified automatically, or the required position can be deployed and the welding means placed manually. The fixed anvil on which the arm, or each of the welding arms presses the material is preferably provided with a surface coating that acts as a buffer for the welding arm, leading to more consistent welding and allowing the use of fabrics lighter than in other cases. Again, such an arrangement is believed to be novel and represents a further aspect of the invention. The surface coating is preferably a tape applied to the surface of the anvil. Most preferably, the tape is a polytetrafluoroethylene (PTFE) tape. The cavities are preferably completed by longitudinal welds formed by a welding arm disposed in parallel relative to the travel direction of the fabric. Most preferably, the material is withdrawn through the encapsulation section by means of cylinders. It is preferred that the material passes between a pair of cylinders arranged horizontally, one of which is driven by a servomotor controlled by the control means. Such cylinders are preferably located downstream of the welding means. Most preferably, the cylinders have rubberized surfaces to improve the engagement of the cylinders with the fabric. Other components of the apparatus, down the arms for welding, can generally be conventional. Such components may include a spindle wheel that rotates transverse to the travel direction of the completed cavities and functions to orient the springs as they expand into the cavities.

The invention will now be described in greater detail, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of a winding unit forming part of an apparatus according to the invention; Figure 2 is a schematic view of the winding unit and the spring transfer assembly forming part of the apparatus; Figure 3 is a detailed partial view on the line III of Figure 2; Figure 4 is a schematic view of an encapsulation section forming part of the apparatus; Figure 5 is a front schematic view of a transverse ultrasonic welding arrangement forming part of the encapsulation section of Figure 4; and Figure 6 is a partial perspective view of a spring assembly in the cavities. First, with reference to Figure 1 schematically a winding unit of an apparatus according to the invention is shown and comprises three components that determine the shape of the spiral produced from the feeding of the wire 1 in the unit by conventional means. These three components are a pair of feeder cylinders 2, 3, a winding finger 4 and a separate call 5. The feeder cylinders 2,3 determine the axis along which the wire is fed to the finger 4 and the spacer 5 This is the master axis in relation to which the orientation axes (slave axes) of finger 4 and separator 5 are adjusted. The orientation of the finger 4 and the separator 5 is regulated by servomotors 6,7 which are controlled by a programmable logic controller (PLC) 8. The PLC 8 is linked in due course to a computer control panel 9. The connection of the panel Control 9 to PLC 8 may be necessary only for a time, for example to download data to PLC 8 or monitor the operation of PLC 8. At other times, for example during normal operation, such connection may be unnecessary. Figure 2 shows a transfer mechanism by means of which the spirals produced in the winding unit (generally designated in Figure 2 with the number 10) are fed into an encapsulation section described below. The transfer mechanism comprises a wheel that rotates clockwise 11 with eight arms 12 extending radially. The rotation of the wheel 11 is synchronized with the operation of the winding unit 10 so that the springs 20 produced in the winding unit 10 are automatically fed into the arms 12 while the arms 12 come out of the winding unit 10. While the wheel 11 rotates, the arms 12 carrying the springs 20 pass along longitudinal grooves in a pair of compression plates 13, 14, the space between them progressively decreasing, causing the springs 20 to compress. The end portions of the compression plates 13, 14 are arranged in parallel and horizontally so as to constitute a supply channel from which the compressed springs 20 are supplied to a tilting cartridge 15 which moves as indicated by the double arrow head. The cartridge 15 transfers the springs 20 to the encapsulation unit and in particular to the space between the two sheets of a folded sheet of a non-woven fabric 25 (shown in dashed lines). When the cartridge 15 is located between the fabric sheets 25, a pneumatically driven rod 16 is raised and engages the spring 20 through the lower sheet and a slot in the base of the cartridge 15. This rod 16 retains the spring 20 in position when the cartridge 15 is separated from the fabric 25. A pair of electromagnets 27 prevent excessive oscillations of the spring 20 when leaving the winding unit 10 and loaded on the arms 12 (see figure 3), the electromagnets are mounted on the upper parts of the upper compression plate 13, on either side of the longitudinal slot 28 running downwardly from the center of the compression plate 13. The electromagnets 27 support each spring 20 upon exiting the winding unit 10 until the corresponding arm 12 of the wheel 11 carries the spring 20. Figure 4 shows the encapsulation unit 40, operating axis of which is arranged perpendicular to that of the winding unit 10. The cloth sheet 25 is folded by conventional means (not shown) and fed through of the encapsulation unit 40 from right to left, as seen in Figure 4, and in incremented steps. The sheet 25 passes first between a pair of guide cylinders 41. A fixed spacer guide (not shown) then part the two sheets of the sheet 25 sufficiently for a spring 20 to be inserted therebetween as described above. The sheet 25 is then transported forward by an increment, so that the next spring 20 can be supplied in the space between the sheets of the sheet 25 from the next arm 12 of the wheel 11. The spring 20 is maintained in a compressed condition by a cover plate 42, which, together with the bed of the encapsulation unit 40, defines a channel through which the encapsulated springs 20 are transported. After the travel in increments of the sheet 25, the two sheets of the sheet 25 are joined by transverse welds formed by a first swingarm arm arrangement 43, which is described in detail below. An additional welding arm 44 forms a longitudinal weld that completes the encapsulation of the spring 20 A second cover plate 45 extends from the region of the first welding arm arrangement 43, after the additional welding arm 44 and also after a arrangement of the control cylinders 46, 47 acting on the fabric sheet 25 folded in such a way as to extract the sheet 25 incrementally through the encapsulation unit 40. The arrangement of the control cylinders 46, 47 comprises a cylinder driven 46 acting on the underside of the sheet 25 and a second cylinder 47 which is pneumatically pressurized in the coupling with the upper surface of the sheet 25. Both cylinders 46, 47 have rubberized surfaces, the rubberized surface of the upper cylinder 47 being partly cut to accommodate the second cover plate 45. When the encapsulated springs 20 emerge from the channel between the second cover plate 45 and the bed of the encapsulation unit 40, expand and rotate in the desired orientation, wherein the axis of the spring is transverse to the cavities, by means of a rotating spindle 48. The finished product is in the form of a series of springs included within the cavities formed in the non-woven fabric, the cavities being connected in the welding lines that define the sides of the cavities. The reciprocating movement of the first welding arrangement 43 and the additional welding arm 44 are synchronized with the operation in increments of the arrangement of the control cylinders 46, 47 again under the control of the PLC 8. As shown in Fig. 5 , the first welding arrangement 43 comprises a pair of arms for ultrasonic welding 51, 52 placed side by side. The arms 51, 52 move on a vertical axis, and the lowest point of their travel presses the fabric sheet 25 onto a corresponding pair of anvils, 53, 54. The folded sheet 25 of fabric, with a spring 20 inserted between the two blades of blade 25 travel between anvils 53, 54 and arms 51, 52, when arms 51, 52 are raised. By using two welding arms 51, 52 it is possible to achieve a greater length of welding than would be possible using only one arm, and therefore deeper cavities containing longer springs can be formed. The lower edge of each arm 51, 52 is crenellated. After each trip in increments of the sheet 25, the arms 51, 52 lower and compress the two sheets of sheet 25 together and join the two sheets in a weld. Due to the crenellated shape of the lower edge of each arm 51, 52, the weld is in the form of an interrupted line, rather than a continuous one. It has been found that it confers a greater resistance to tension in the series of springs in finished cavities. The upper surface of each of the anvils 53, 54 has a strip of polytetrafluoroethylene tape 55, 56. This cushions the contact of the welding arms 51, 52 with the fabric 25 and leads to a formation to a further welding formation. consistent and allows the use of lighter weight fabrics than could be presented in other cases. Finally with reference finally to Figure 6, a cavity spring assembly 60 comprises series of cavity springs as they emerge from the encapsulation unit 40 arranged side by side and clamped to form a generally rectangular assembly. The series of springs can be fixed to each other by any suitable means, for example by glue, seam or mechanical fasteners. The depth d of the assembly 60 can be substantially greater than that of the conventional cavity spring assemblies.

Claims (40)

NOVELTY OF THE INVENTION CLAIMS

1. An apparatus for the production of spiral springs in cavities, comprising a winding section in which a spiral is formed from a wire fed to the winding section, said winding section comprises winding elements whose position and / or orientation determines the shape of said spiral, and an encapsulation section wherein the spiral is inserted between juxtaposed sheets of material and wherein the sheets of material are joined to form a cavity enclosing the spiral, wherein said apparatus additionally comprises means of programmable control that can operate together with said winding elements to control in this way the position and / or orientation thereof.

2. The apparatus according to claim 1, further characterized in that the programmable control means comprises a programmable logic controller by means of which the numerical computer control of the winding section is achieved.

3. The apparatus according to claim 2, further characterized in that the logic controller acts with drive means by which the position and / or orientation of the winding elements can be modified.

4. - The apparatus according to claim 3, further characterized in that said drive means comprises three motors, one for the wire feed cylinders, one for the winding element that controls the diameter of the spring, and one for the winding element that controls the separation of the spring.

5. The apparatus according to any of the preceding claims, wherein the control means stores tables or data arrangements that determine the position of the axes of the winding elements with respect to the position of the axes of the feed cylinder .

6. The apparatus according to any of the preceding claims, further characterized in that one or more electromagnets are mounted at the outlet of the winding unit, said or said electromagnets are coupled to each spring when it leaves the winding unit, said The spring is mechanically removed from one or more electromagnets while said spring is transported to the encapsulation section.

7. The apparatus according to any of the preceding claims, further characterized in that the programmable control means can also be operated linked to the encapsulation section, to control the movement of the material through the encapsulation section.

8. - The apparatus according to claim 7, further characterized in that a servomotor operably linked to the programmable control means controls the movement of the material through the encapsulation section, so that said material advances in increments corresponding to the width of the cavity desired.

9. The apparatus according to any of the preceding claims, wherein further the means by which the springs are transferred to the encapsulation unit and inserted between the sheets of material comprises a rotation wheel with arms extending radially, springs formed successively being coupled by successive arms of said wheel; means for compressing the springs when transporting them towards the encapsulation section in the arms of said rotation wheel; and a tilting cartridge in which the compressed springs are supplied by said wheel and into which the compressed springs are conveyed to the encapsulation section.

10. The apparatus according to any of the preceding claims, further comprising ultrasonic welding means by which the sheets of material are joined to form cavities.

11. The apparatus according to claim 10, further characterized in that said welding means comprises longitudinal welding means arranged in parallel with the longitudinal axis of the sheets of material and transverse welding means arranged in transverse relation with respect to said axis.

12. The apparatus according to claim 10 or 11, wherein said ultrasonic welding means comprises arms for ultrasonic welding with crenellated bottom edges.

13. The apparatus according to claim 11, further characterized in that said transverse welding means comprises a pair of welding arms disposed collinearly.

14. The apparatus according to claim 12 or 13, wherein means for modifying the position of the transverse welding means on said longitudinal axis of said sheet of material are provided.

15. The apparatus according to any of claims 10 to 13, wherein in addition the ultrasonic welding means comprises arms for ultrasonic welding, at least one of which acts against a fixed anvil provided with a coating of surface that acts as a buffer for said arm for welding.

16. The apparatus according to claim 15, wherein said surface coating further comprises a tape applied to the surface of the anvil.

17. The apparatus according to claim 16, wherein said tape is a polytetrafluoroethylene tape.

18. The apparatus according to any of the preceding claims, wherein said sheets of material are extracted through the encapsulation section by means of a pair of cylinders arranged horizontally, one of which is driven by a servomotor controlled by the programmable control medium.

19. The apparatus according to claim 18, further characterized in that said cylinders have rubberized surfaces.

20. The apparatus according to any of the preceding claims, further characterized in that said encapsulation section comprises a transport means for extracting said sheets of material in increments through the encapsulation section and a welding means for welding the sheets of the material together, wherein the means of transport and the welding means are controlled by the programmable control means.

21. A method for producing spiral springs in cavities, which method comprises the steps of a) adjusting the positions and / or orientations of the winding elements in the winding section of the apparatus according to any of the preceding claims, b ) feeding wire through the winding section so as to form a spiral, c) separating said spiral from said wire, d) compressing said spiral, e) inserting said spiral between juxtaposed sheets of material, and f) joining said sheets of material together to encapsulate said spiral.

22. The method according to claim 21, wherein the positions and / or orientations of the winding elements are established in accordance with an arrangement of data stored in the programmable control means.

23. A method according to claim 21 or claim 22, wherein the positions and / or orientations of the winding elements are established by servomotors that operate under control of the programmable control means.

24. A cavity spiral spring assembly produced in accordance with the method of any of claims 21 to 23.

25.- The apparatus for the production of spiral springs in cavities comprising a winding section in where a spiral is formed from wire fed to the winding section, said winding section comprises winding elements whose position / or orientation determines the shape of said winding, and an encapsulation section where the spiral is inserted between juxtaposed sheets of material and wherein the sheets of material are joined together to form a cavity enclosing the spiral, wherein said encapsulation section comprises at least one arm for ultrasonic welding disposed parallel to the longitudinal axis of the sheets of material, and a plurality of transverse welding arms arranged collinearly in transverse to the longitudinal axis of the sheet of material.

26. The apparatus according to claim 25, further characterized in that a means for changing the position of the arms for transverse welding on said longitudinal axis of said sheets of material is provided.

27. The apparatus according to claim 25 or 26, further characterized in that at least one of said arms for ultrasonic welding acts against a fixed anvil provided with a surface coating that acts as a buffer for said welding arm.

28. The apparatus according to claim 27, further characterized in that said surface coating comprises a tape applied to the surface of the anvil.

29. The apparatus according to claim 28, further characterized in that said tape is a polytetrafluoroethylene tape.

A method for producing spiral springs in cavities, said method comprises the insertion of a compressed spiral spring between juxtaposed sheets of material, and joining said sheets by means of ultrasonic welds arranged in parallel and transverse to the longitudinal axis of said sheets. sheets so that said spring is encapsulated therebetween, wherein the ultrasonic welds transverse to the longitudinal axis of said sheets are formed by a plurality of arms for ultrasonic welding with their bottom edges disposed collinearly.

31. - The apparatus according to claim 30, further characterized in that the lower edges of the welding arms are crenellated.

32.- An assembly of spiral springs in cavities produced in accordance with the method of claim 30 or claim 31.

33.- An apparatus for the production of spiral springs in cavities, comprising a winding section where it is formed a spiral from wire fed to the winding section, said winding section comprises winding elements whose position / or orientation determines the shape of said winding, and an encapsulation section wherein the spiral is inserted between juxtaposed sheets of material and wherein the sheets of material are joined together to form a cavity enclosing the spiral, wherein said encapsulation section comprises at least one arm for ultrasonic welding acting against a fixed anvil provided with a surface coating that functions as a shock absorber for said arm for welding.

34. The apparatus according to claim 33, further characterized in that said surface coating comprises a tape applied to the surface of the anvil.

35.- The apparatus according to claim 34, further characterized in that said tape is a polytetrafluoroethylene tape.

36. The apparatus according to any of claims 33 to 35 comprising at least one arm for ultrasonic welding arranged parallel to the longitudinal axis of the sheets of the material, and a pair of welding arms arranged collinearly and in transverse to the longitudinal axis of the sheets of material. 37.- The apparatus for the production of spiral springs in cavities comprising a winding section where a spiral is formed from wire fed to the winding section, said winding section comprises winding elements whose position / orientation determines the shape of said spiral, and an encapsulation section where the spiral is inserted between juxtaposed sheets of material and where the sheets of material are joined together to form a cavity enclosing the spiral, where an electromagnetic medium is provided in the output of the winding section, said electromagnetic means is coupled to the spiral to decrease the oscillation thereof. 38.- The apparatus according to claim 37, wherein said magnetic means comprises one or more electromagnets. 39.- The apparatus according to claim 37 or 38, wherein the spiral is mechanically removed from the magnetic medium while being transported from the winding section to the encapsulation section. 40.- A cavity spring assembly that has a depth of 20 centimeters or more.