Device for receiving and unwinding continuous material

Abstract

Device for receiving and unwinding continuous material with a base (1), a wave provided for therein (3), a rotating element (7) mounted so as to be rotatable about a shaft axis (5) relative to the base (1), an adjusting element (9) designed to apply a preload force to a lever arrangement (11), wherein the lever arrangement (11) is pivotably mounted on a lever axis (13) outside the shaft axis (5), and comprises an arm (15), a deflecting element (17) designed to guide the continuous material and provided on the arm (15) at a distance from the lever axis (13), and at least two brake elements (19), wherein the at least two brake elements (19) are designed to interact with the rotation element (7) according to the principle of an electrodynamic brake, wherein the at least two brake elements (19) are held movable perpendicular to the shaft axis (5) and can be brought into operative contact with the rotation element (7) from different sides by a movement of the lever arrangement (11).

Description

[0001] The invention relates to a device for receiving and unwinding continuous material, for example a thread, a fiber, a wire, a tape or the like, from a spool, wherein a tension in the continuous material remains essentially constant during operation after adjustment by an adjusting element, regardless of the winding radius of the spool.

[0002] Various devices are known from the prior art that implement the voltage control in the drawn-off continuous material using a delay unit based on the principle of an eddy current brake.

[0003] DE 10 2007 022 883 A1 describes a device for receiving and unwinding continuous material, in particular drawn wire material, from a spool, comprising a housing, a mandrel or shaft rotatably mounted therein for receiving a spool, a disk provided thereon, and a swivel arm mounted at a distance from a mandrel axis, the swivel arm having a deflecting element, for example a dancer roller, at one end and at least one magnet holder at the other end, wherein the magnet holder is designed so that it can be brought into operative contact with the disk during the unwinding of the continuous material according to the principle of an electrodynamic brake – a so-called eddy current brake. A disadvantage of this arrangement is that the force vectors generated by the braking process and the changing center of gravity of the swivel arm have a disruptive effect on the voltage control.

[0004] EP 2 509 904 B1 is a self-compensating tension control device for controlling the dispensing of filament material from a spool, comprising a stationary holder, a spindle assembly, a conductive element rotatable with the spindle assembly, a magnetic element supported by the stationary holder, and a linear or rectilinear mechanism designed to bring the rotatable element into linear operative contact with the magnetic element. Due to the rectilinear mechanism, the center of gravity of the spindle assembly and the braking force vectors have no significant influence on the tension control.Self-regulation is achieved through a linear movement of the following device elements: the rectilinear mechanism, the spindle arrangement, the conductive element, a bearing, and the coil, which together exhibit considerable inertia, making this voltage control device unsuitable for following rapid and minor fluctuations in preload.

[0005] Therefore, there is a need for a device for receiving and unwinding continuous material that enables precise and stable tension regulation, which is essentially free from disturbances caused by braking force vectors or the center of gravity of the lever arrangement.

[0006] The aim of the invention is to provide a device for receiving and unwinding continuous material, which is designed in such a way that the self-regulation of the tensile or prestressing force of the unwound continuous material is essentially free from disturbances.

[0007] The objective is achieved by the device according to claim 1 or claim 5. Further advantageous embodiments and developments of the invention can be found in the dependent claims.

[0008] In particular, this objective is achieved by a device for receiving and unwinding continuous material, comprising: a base, a shaft provided thereon, a rotating element rotatably mounted about a shaft axis relative to the base, an adjusting element designed to apply a preload force to a lever arrangement pivotably mounted on a lever axis outside the shaft axis, and an arm, a deflecting element designed to guide the continuous material and provided on the arm at a distance from the lever axis, and at least two braking elements, wherein the at least two braking elements are designed to engage with the rotating element according to the principle of an electrodynamic brake or...The eddy current brake is designed to work together, with the at least two braking elements being held movable perpendicular to the shaft axis and being brought into operative contact with the rotating element from different sides by moving the lever arrangement. This design enables precise and stable voltage regulation that is decoupled from disruptive braking force vectors. It should be noted that the movement of the two braking elements need only have one component perpendicular to the shaft axis, but is not limited to movement exclusively perpendicular to this shaft axis.

[0009] According to a further preferred embodiment, at least two braking elements with magnet carriers and magnets held by these carriers are provided and designed such that, when the lever assembly is moved from opposite sides, preferably symmetrically, they can be brought into operative contact with the rotating element in a pincer-like motion. This leads to a reduction or elimination of disruptive torques on the lever assembly caused by the braking forces.

[0010] Preferably, the at least two braking elements are mutually interconnected, such that the movement of one braking element results in a preferably opposite movement of the other. This ensures a synchronized and effective pincer-like movement of the braking elements.

[0011] Preferably, a first brake element is rigidly connected to the arm, while a second brake element is connected to the arm via a partial toothing or via a tab and a control disc. This arrangement enables a simple and robust realization of the symmetrical movement of the brake elements.

[0012] Preferably, the rotating element is rotatably mounted on the shaft. This ensures a direct coupling of the rotating element to the coil rotation.

[0013] Furthermore, it is preferred that the center of gravity of the lever assembly is located essentially on the lever axis during operation. This minimizes disruptive torques on the lever assembly caused by gravity.

[0014] A pneumatic cylinder is also preferred as the adjusting element. This allows for sensitive and precise adjustment of the preload force.

[0015] Furthermore, the braking elements are preferably designed to encompass the rotating element in a U-shape with respect to the axis of rotation. This maximizes the contact area and increases the power density of the brake.

[0016] A deflection element is preferably a deflection roller. The use of a deflection roller reduces friction and residual stresses in the continuous material during deflection.

[0017] The invention can be better understood with reference to the following drawings and description. The components in the figures are not necessarily to scale; instead, emphasis is placed on illustrating various preferred embodiments of the invention. Fig. 1A and Fig. Figure 1B shows a side view of a pre-tensioning device according to the invention and a representation of the force vectors as a function of the position of the magnet. Fig. Figure 2 shows a perspective view of the pre-tensioning device according to the invention with a coil attached to it, schematically showing the change in the coil radius by unwinding the continuous material. Fig. 3A and Fig. Figure 3B shows perspective views of the arrangement of the brake elements and the lever arrangement of a second embodiment in two different lever positions. Fig. Figure 4 shows a perspective view of a first embodiment of the lever arrangement according to Fig. 3. Fig. Figure 5 shows a perspective view of a second embodiment of the lever arrangement according to Fig. 3.

[0018] The invention is described in detail below with reference to the accompanying figures.

[0019] How Fig. 1 and Fig. As can be seen from Figure 2, in a first preferred embodiment the device comprises a base 1 on which a shaft 3, which here is designed as a mandrel, is rotatably mounted. The shaft 3 is designed to accommodate a coil, so that when the coil rotates during the unwinding of continuous material, a rotating element 7 rotates with it.

[0020] A rotationally fixed element 7 is provided on shaft 3. The rotational element 7 can, for example, be designed as a disc or drum made of a conductive material suitable for electrodynamic braking by eddy currents. The rotational element 7 can, for example, be made of copper, aluminum, iron, or a suitable alloy.

[0021] A lever assembly 11 is rotatably mounted about the lever axis 13 at the base 1 by means of a lever shaft or axis 13 at a distance from a shaft axis of the shaft 3. The lever assembly 11 comprises an arm 15, a deflection element 17, and a brake element 19, which are rigidly connected to one another.

[0022] The deflection element 17 is designed to guide the continuous material and is provided at a distance from the lever axis 13 on the arm 15.

[0023] At the in Fig. 1A and Fig. In the device shown in Figure 1B, the braking element 19 is designed as a magnetic carrier 21 with a magnet 23, which can interact with the conductive rotating element 7 and together they form an eddy current brake. During operation, the rotating element 7 is set into rotation by unwinding the continuous material from a coil mounted on the shaft 5. The faster the rotation, the stronger the eddy current brake action.

[0024] The adjusting element 9, for example a pneumatic cylinder, is provided for adjusting the preload and acts on the lever arrangement 11.

[0025] The only adjustable parameter is a specific air pressure in the system, which, however, only needs to be set once to the desired preload and should not change during the process afterwards.

[0026] At the in Fig. In the embodiment shown in Figure 2, the base 1 has two receptacles for axles or shafts. In one receptacle, the shaft 3 is mounted with the rotationally secure rotating element 7 as an eddy current disk. The shaft 3 tapers towards the viewer to a mandrel. The shape of the shaft 3 can be customized according to user requirements.

[0027] Also in Fig. Figure 1A shows a unit consisting of the lever assembly 11 and a magnetic carrier 21, which are positioned relative to each other on the lever axis 13 in a rotationally fixed manner. The lever assembly 11 carries a deflection element 17, for example, a deflection roller or dancer roller, over which the continuous material, such as a wire, a textile thread, or a ribbon, is drawn. The length and diameter of the deflection roller 17 are adapted to the application. The adjusting element 9 exerts a generally constant force on the lever arm 15.

[0028] As explained, the magnet 21 and the rotating element 7 form an eddy current brake. A braking torque acts against the rotation of the rotating element 7, and thus of the coil. This braking torque depends on the strength of the magnetic field in which the eddy current disk, i.e., the rotating element 7, moves. When the lever assembly 11 is pushed to the right by the adjusting element 9 to its maximum stroke, the magnet 21 covers the rotating element 7 to its maximum extent, and the braking torque is therefore at its maximum. The brake is engaged. When the lever arm 15 is pushed to the left against the adjusting element 9, the overlap decreases, and the brake opens until the minimum overlap or minimum torque is reached.

[0029] During operation, the spool is fixed to shaft 3. The spool is loaded with a continuous material, such as wire, thread, tape, or similar. The method of securing the spool depends on the application and the material. The continuous material is unwound to the left via the deflecting element 17 at the end of the lever assembly 11, causing the spool to rotate clockwise in a top view.

[0030] The adjusting element 9 exerts a clockwise torque on the lever assembly 11, while the continuous material exerts a counterclockwise torque on the lever assembly 11 via the deflecting element 17. Once a tension is set in the continuous material to be drawn off, the air pressure should remain constant, for example in the case of an adjusting element in the form of a pneumatic cylinder 9, and further control technology should essentially be unnecessary.

[0031] The tension in the continuous material and the resulting torque depend on the braking resistance of the rotating element 7 in the magnet 21. When the lever assembly is pulled to the left against the adjusting element 9, the brake opens and the braking torque decreases. Ideally, equilibrium is reached when the resulting torque in the lever assembly 11, generated by the continuous material on the deflecting element 17, equals the resulting torque from the adjusting element 9.

[0032] The behavior and, in particular, the effect of eddy current brakes are known to depend on the rotational speed.

[0033] The tension of the endless material therefore depends not only on the braking torque acting on the coil, but also on the remaining diameter of the winding of the endless material on the coil, from which it is drawn off, as is the case in Fig. 2 is shown.

[0034] This diameter decreases during the process, which, with a constant unwinding speed of the continuous material, increases the rotational speed of the spool and thus of the rotating element 7. With a constant braking torque, the shortened radius over which the wire is unwound would increase the tension in the wire.

[0035] The force of the adjusting element 9 is independent of the fact that there are only two torques in the lever arrangement 11, one resulting solely from the tension of the continuous material and one resulting from the adjusting element 9. In this case, with constant air pressure, exactly the same tension would always be generated on the continuous material, regardless of the pull-off speed in the working area and / or the amount of wire on the spool.

[0036] The tension of the continuous material itself corresponds to the input value of the adjusting element 9. However, with constant tension of the continuous material, shifting force vectors of varying strength, depending on the lever position and the remaining amount of continuous material on the spool, influence the translation of this measured value.

[0037] If the center of mass of the lever assembly 11 is not located exactly on the lever axis 13, then an additional torque results due to gravity, depending on the position of the lever assembly 11. Therefore, the center of mass is preferably located as close as possible to the lever axis 13 in order to minimize the torque.

[0038] Furthermore, the deceleration of the rotating element 7 generates force vectors that act in the opposite direction to the direction of motion of the rotating element 7, i.e., they act at the magnetic center of mass of the brake magnet and are tangentially aligned there. These force vectors can be combined into a single vector A, as shown in Fig. This is shown in Figure 1B. This total force vector A acts tangentially to a circle that is smaller than the rotation element 7 and depends on the magnetic center of mass of magnet 21 when it engages with the rotation element 7. Depending on the intersection of magnet 21 and the rotation element 7, this point of contact of the total force vector A moves across the rotation element 7, whereby the angle with respect to the vertical also changes.

[0039] The effect can be visualized by imagining magnet 21 as a mosaic of many small individual magnets. Each of these individual magnets generates a force vector during braking, which acts on the lever arrangement 11. The total force vector is formed by the sum of all these individual force vectors. However, only those (imaginary) individual magnets that are actually engaged with the rotating element 7 contribute a force vector. When the eddy current brake opens, i.e., when the area of ​​overlap between magnet 5 and the rotating element 7 becomes smaller, the point of application of the total force vector A shifts because the position of magnet 5 itself changes, and because some of the (imaginary) individual magnets in the outer region of magnet 5 no longer contribute to the total force vector.

[0040] In the lever arrangement 11, a second force vector B acts against this total force vector A, which, via its distance to the lever axis 13, causes a torque on the lever arrangement 11.

[0041] To compensate for this effect, the invention provides for a special design of the magnet 5 in its shape.

[0042] Preferably, the ideal operating position of the magnet is in the range between the fully closed eddy current brake (1st endpoint) and the fully released eddy current brake (2nd endpoint). However, the grounding capability is not limited to this. The main advantages of the invention are achieved when the operating positions each mark 80%, 60%, or 30% of the fully closed or fully open eddy current brake, respectively.

[0043] The magnet is now shaped such that an effective axis of a total force vector A acting on the braking element 19 by the electrodynamic principle runs essentially through the lever axis 13 in all working positions, i.e., over an entire working range, between a first working position and a second working position of the lever arrangement 11.

[0044] The point of application of this total force vector A, i.e., the effective magnetic center of gravity of magnet 5 when it engages with the rotating element 7, will move relative to the rotating element 7 as magnet 21 moves. This movement depends, firstly, on the movement of magnet 21 itself. Secondly, the position of the effective magnetic center of gravity on magnet 21 changes due to the degree of overlap between the rotating element 7 and magnet 21. Taking these two elements of movement of the effective magnetic center of gravity into account, the shape of magnet 5 and its position-dependent magnetization must now be selected such that a tangent to an imaginary circle around shaft 3 through this effective magnetic center of gravity points to the lever axis 13 within the planned operating range of the eddy current brake.

[0045] In other words, the eddy current brake exerts a force on magnet 5, which, in the example shown, causes it to Fig. 1B essentially pulls to the right and downwards. This force should be directed such that it does not cause a torque of the lever arrangement 11 about the lever axis 13. This is the case when the force acts through the lever axis 13 itself.

[0046] Several approaches are possible to achieve this effect. Firstly, the magnet itself can be geometrically shaped in such a way that the effective magnetic center of gravity moves outwards and to the right when the eddy current brake is opened, so that the outwards movement is accompanied by a change in the tangential angle due to the movement to the right, which results in the total force vector A being further aligned with the lever axis 13.

[0047] Or, assuming that the shaft 3 lies at the origin of a chosen coordinate system, and that the lever shaft 13 lies on the chosen x-axis, then the effective magnetic center of mass must be subject to the following condition: A(r)=(r2b,±r1−r2b2) follow, where b denotes the position of the lever shaft 13 on the selected x-axis, and where r is the radius of the circle around the shaft 3 on which the effective magnetic center of gravity lies.

[0048] The invention is not limited to generating the path of the effective magnetic center of gravity through the geometry of the magnet. It is also possible to magnetize different areas of the magnet 5 with different strengths, so that the effective magnetic center of gravity moves along the curve determined by the formula above when the eddy current brake is opened or closed.

[0049] However, the above solution requires precise manufacturing of the magnet and precise positioning of the magnet on the lever assembly 11.

[0050] The second embodiment of the invention, as described in the Fig. 3A and Fig. Figure 3B avoids some of the challenges of the first embodiment. Here, at least two braking elements, namely a first braking element 19a and a second braking element 19b, are connected to the lever assembly 11. In this example, each of the two braking elements 19a and 19b has two magnet carriers 21, each of which has at least one magnet 23. An adjusting element 9, which in this example is also a pneumatic cylinder 31, is designed to exert a preload force on the lever assembly 11. If the stress in the continuous material falls below this preload due to operational reasons, the first braking element 19a engages with the rotating element 7 from below and the second braking element 19b engages with it from above.

[0051] In this embodiment, the lower, first brake element 19a is similar to the first embodiment made of Fig. 1, rigidly connected to the arm 15 of the lever assembly 11. A second, upper brake element 19b, however, is connected via a tab 25 and a control disc 27 (see Fig. 4) or via a partial gear 29 (see Fig. 5) movably connected to the arm 15 of the lever arrangement 11. The second brake element 19b is also held at the base 1 via a third shaft 35.

[0052] Fig. Figure 3B shows - now together with the rotating element 7 - this embodiment in the open position.

[0053] By moving the lever arrangement 11, the two brake elements 19a and 19b are moved further over the rotating element 7 with a pincer-like movement, whereby this experiences a braking force without contact and without wear according to the principle of an electrodynamic eddy current brake, which acts on the coil via the rotationally fixed connection to the shaft 3.

[0054] The braking force vectors of the two braking elements 19a and 19b, resulting from the double enclosure of the rotating element 7, act in opposite directions and cancel each other out. This eliminates a resulting torque on the lever assembly 11, thereby increasing the precision of the tension regulation.

[0055] The effective surface formed in the available installation space between the brake elements 19a, 19b and the rotating element 7 is also enlarged compared to the prior art, resulting in a higher power density and increased precision.

[0056] Fig. Figure 4 shows the connection between the upper brake element 19b and the lever assembly 11 in greater detail. The movement of the lever assembly 11 about the lever axis 13 exerts a force on the tab 25 and the control disc 27, which causes a corresponding rotation of the second brake element 19b about the third shaft 35. Preferably, the assembly is designed such that the two movements of the brake elements 19a and 19b are mirror-symmetrical.

[0057] Fig. Figure 5 shows an alternative to the tab 25 and control disc 27 in the form of a partial toothing 29.

[0058] In a preferred embodiment, the lever arrangement 11 is designed such that its center of gravity is located essentially on the lever axis 13, so that when the lever arrangement 11 is rotated, no disturbing moment caused by gravity acts on the tension regulation via the lever arrangement 11.

[0059] The invention has been described using one or two magnets 23. However, the invention is not limited to this. It is also possible to install several magnets 23 in each of the brake elements 19. The brake elements 19 can also encompass the rotating element 7 in a U-shape – i.e., on its front and back sides as shown in the figures – so that when the eddy current brake is engaged, magnets 23 are arranged on both sides of the rotating element 7 in the direction of the shaft 3.

[0060] Advantages of the invention are: • Stable and precise tension regulation: By compensating for or neutralizing disruptive torques, high accuracy is achieved in regulating material tension. • Low susceptibility to interference: The device is largely insensitive to external influences such as changing braking force vectors or shifts in the center of gravity. • Wear-free and clean: The electrodynamic eddy current braking is contactless, which minimizes wear and enables dust-free working environments. • High power density: The U-shaped grip of the rotating element by the braking elements allows for a larger effective area and thus a more efficient braking effect in a compact design. • Adaptability: The use of deflection rollers and a pneumatic cylinder as an adjustment element allows for flexible adaptation to different continuous materials and applications.

[0061] The present invention is not limited to the embodiments described above. Rather, the scope of protection of the invention is defined exclusively by the accompanying patent claims. The foregoing description and the accompanying drawings serve only to facilitate understanding of the invention and to illustrate preferred embodiments.

[0062] The features described in the individual claims can be combined with one another as appropriate, insofar as technically feasible, to create further advantageous embodiments of the invention. In particular, features of dependent claims can be combined with the features of the independent claim as well as with features of other dependent claims to realize additional aspects and advantages of the invention. Such combinations are also to be considered part of the present invention.

[0063] Where the description and the following claims state that a movement occurs perpendicular to an axis or shaft, this is to be understood as meaning that the movement of the respective element has at least one component that runs perpendicular to the axis. The movement itself is not strictly limited to a plane perpendicular to the respective axis or shaft.

[0064] Insofar as it is set out in the description and the following claims that the center of gravity of the lever arrangement 11 is arranged on the lever axis 13, the person skilled in the art understands that small deviations are tolerable insofar as they do not have a disturbing influence on the preload when the relative position of the lever arrangement 11 changes.

[0065] Insofar as it is set out in the description and the following claims that the effective axis of the braking force vector A runs through the lever axis 13 between a first working position and a second working position of the lever arrangement 11, the person skilled in the art understands that small deviations are tolerable insofar as they do not have a disturbing influence on the preload when the relative position of the working position changes by opening or closing the brake. REFERENCE MARK LIST 1 Base 3rd wave 5 Shaft axis 7 Rotational element 9 Adjustment element 11 Lever arrangement 13 Lever axle 15 Arm 17 Deflection element 19 Brake element 19a First brake element 19b Second brake element 21 magnetic carriers 23 Magnet 25 tabs 27 Control disc 29 partial gearing 31 pneumatic cylinders 33 Pulley 35 third wave A Total force vector B Lever vector QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2007 022 883 A1

[0003] EP 2 509 904 B1

[0004]

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