Patent Application
20200010986
The invention relates to a braiding machine for producing a braid and a method of producing a braid.
The term “braids” herein refers in particular to round braids, i.e. braids of a tubular shape. Braids are characterized generally by oppositely-applied strands, for example threads or single wires, which recurrently cross over each other. There are textile braids and also metallic braids. Such braids are used for structural elements made of composite materials, for example hoses or in particular also cables. Of particular importance are the metallic round braids that serve as shields for electrical cables.
To produce such braids cost-effectively, high working speeds are required. Yet particularly in the case of shieldings for cables, there are increasing technical requirements for precision and, in particular, for cleanliness. Shielding braids are used, for example, in data lines for high-frequency signal transmission. The data transmission rates that can be achieved depend in part on the quality of the shielding.
Two different types of braiding machines—also known as braiders—are typically used to produce shielding braids for cable production. In what are known as high-speed weavers, two baskets, each respectively having a plurality of reel supports, circulate opposite each other. The intersections of the individual wires are generated by lever arms that are operated over a mechanical curved path.
In what are known as bobbin braiders, two groups of reel supports circulate. An apparatus consisting of slotted, rotating discs ensures that the paths undergo the desired degree of interweaving.
In contemporary braiding machines, process speeds of about 150 revolutions of the reel supports per minute are achieved. This high rotational speed generates high centrifugal forces on the reel supports, and the holders for the reel supports must absorb these forces. The moving components also give rise to sliding friction at many points. The sliding of the components moving relative to each other usually requires lubrication. The problem here is that parts of the lubricant are also introduced into the braid, which negatively impacts braid quality, especially for electrical shielding. Overall, the conventional braiding machines described are mechanically very cumbersome.
On this basis, the object of the invention is to make possible the production of braids, in particular metallic shielding braids, of high quality.
According to the invention, the object is accomplished by means of a braiding machine for producing a braid, in particular a preferably metallic round braid. The braiding machine comprises at least two reel supports and a control device for controlling the braiding process. The reel supports may be moved on at least two and preferably exactly two predetermined paths, and each reel support may be driven individually via an electromagnetic drive. For the electromagnetic drive, first magnets are distributed along the predetermined paths, and at least one second magnet is arranged in a respective reel support. The first magnets and/or second magnets are electromagnets that may be controlled in such a way that continuous magnetic fields may generate propulsion along the predetermined path for the respective reel support. Thus, by means of the continuous magnetic fields, the reel supports undergo acceleration, in particular positive and/or negative acceleration (braking) or also movement at constant speed. The control device is also designed in such a way that the reel supports are moved along the predetermined paths during operation by means of the continuous magnetic fields.
Each respective reel support has in particular exactly one reel from which exactly one braided strand, in particular one wire, is unwound. Alternatively, a reel support also has a plurality of reels. The particular advantage of propulsion via continuous magnetic fields is apparent in the fact that in this way, the mechanical friction from the propulsion of the reel supports may be at least significantly reduced compared to conventional braiding machines, so that lubricant may at least be reduced or avoided relative to conventional braiding machines. This reduces or eliminates the risk that portions of the lubricant may be introduced into the braid and thus degrade its quality.
Another important aspect that arises from this drive concept with continuous alternating magnetic fields is that the individual reel supports are individually guided along the respective path.
The two paths are closed and cross several times. The reel supports on the two paths are driven in opposite directions; that is, the reel supports are for example guided clockwise on the first path and counterclockwise on the second path. The two paths are preferably approximately circular, deviating from the basic movement of a circular path. In particular, the paths are wave-shaped, for example sinusoidal. The paths are therefore formed of a plurality of curved sections that are alternately curved convexly and concavely. Straight sections are preferably arranged between two curved sections. Each respective path has in particular at least three convexly-curved sections and three concavely-curved sections. In particular, each path respectively has at least four or exactly four convexly- and concavely-curved sections. The curved sections are in particular arranged to be evenly distributed, so that the respective path is rotationally symmetric around a central axis. The convexly- or concavely-curved sections each respectively have an angular distance of 360°/n to each other, where n is the number of convexly- or concavely-curved sections. Thus, with four concavely-curved and four convexly-curved sections, a 90° rotational symmetry is achieved. The two paths have the same central axis. They intersect in particular 2n times.
In addition, expediently, the two paths are designed identically to each other, apart from being rotated around the central axis by a twist angle so that they are not congruent. The twist angle here is smaller than the angular distance between two convexly- or concavely-curved sections. A maximum outer diameter (path diameter) of a respective predetermined path is typically between 1.0 and 2.0 m, preferably typically between 1.0 and 1.5 m. Depending on the application, smaller or larger maximum diameters may also be realized.
With the magnetic drive, speeds in the range of 100 to 150 revolutions per minute for a respective reel support are preferably achieved, and are adjusted accordingly via the control device. A respective reel support thus runs around the central axis 100 to 150 times per minute.
The curved paths, i.e. the circumferential direction as well as the curved sections, define a travel surface within which the reel supports travel.
The braiding machine is designed in such a way that, in order for the configuration to be as friction-free as possible, the reel supports are guided along the respective predetermined path while suspended during operation. The electromagnetic drive therefore not only generates the propulsion, but also lifts the reel supports perpendicularly to the travel surface by a magnetic force, so that the supports are guided—similarly to a suspension railway—while suspended in air, and in particular without mechanical contact. This decisively reduces the mechanical load and, in particular, avoids mechanical friction effects during guiding of the reel supports.
In a preferred configuration, it is also envisioned that the reel supports are driven and guided without the use of lubricant. Accordingly, the braiding machine—at least in the area of the reel supports does not use any lubricants at all. This guarantees a high quality of the braids.
In principle, it is possible to guide the reel supports along the predetermined paths by the generated magnetic forces alone, without any mechanical guidance.
So as to afford the most robust and reliable configuration possible, the predetermined paths are preferably formed by rails along which the reel supports are guided. Accordingly, in this respect, there is a certain degree of mechanical constraint. Due to the suspension principle, however, mechanical contact between the reel support and the rail is avoided. At the same time, this mechanical constraint ensures high process reliability and secure guidance of the reel supports even at high speeds. In case of malfunctions, the reel support remains on the predefined path.
The at least two predetermined paths, along which the reel supports run in opposite directions, preferably lie generally within the travel surface. This travel surface is for example a common plane or also a common curved surface. Because the course is wave-shaped, the paths cross several times. The same applies to the rails of at least two paths. These paths cross at a plurality of intersections. Preferably, the rails run straight at the intersections and have interruptions at the intersections. The interruption ensures that the reel supports may cross the rail of the respective other path. The straight course at the intersections also ensures that no radial centrifugal forces act in these areas where the interruptions are present, thus ensuring reliable guidance.
In a preferred configuration, the rails have a curve banking on at least one part and preferably on all curved sections. In the area of the curved sections, a respective section of the rail is therefore inclined with respect to a horizontal plane, so that centrifugal forces are absorbed by this curve banking. At least some of the centrifugal forces that occur are therefore absorbed by the travel surface perpendicular to the course of the path. The radial centrifugal force component acting on the rails is therefore at least reduced or eliminated.
In an expedient refinement, the paths and thus the rails are arranged running alongside the inner surface of a cone or cylinder. The reel supports therefore run circumferentially along the inner surface. The centrifugal forces are absorbed with respect to the horizontally-inclined, in particular vertically-oriented inner surface.
In the preferred configuration, at least a part of the magnets is also arranged in such a way, and is controlled during operation with the aid of the control device in such a way, that centrifugal forces acting on the reel supports during operation are at least partially magnetically compensated. The term “magnetic compensation” herein signifies that the magnetic fields that the magnets generate exert a magnetic force on the reel supports, and this magnetic force counteracts the respective centrifugal force. To this end, magnetic pairs are preferably generally arranged on the outside and inside of the path, and exert a magnetic force on the respective reel support in the radial direction—as appropriate—directed either inward or outward (depending on the path's current course).
Expediently, the reel supports on the respective rail are guided in such a way that a mechanical axial form-locking is formed in an axial direction, i.e. perpendicularly to the travel surface within which the respective path runs. At the same time, expediently, a radial mechanical form-locking is also formed. The respective reel support may therefore not reach from the rail. The support is held in this position by a form-locking that acts in two directions.
To this end, the rail expediently has a rail head and the reel supports have a reel foot. The rail head and reel foot alternately grip each other in a rear grip area. Both the axial and the radial form-locking are formed by the rear grip area. Expediently for this purpose, one of these two components, preferably the rail head is approximately T-shaped when viewed in cross-section and the other component, preferably the reel foot, is bow-shaped, especially approximately C-shaped, so as to grip the T-shaped head.
In order to achieve the desired magnetic compensation of the centrifugal forces, a second magnet is respectively arranged on the inside and also on the outside of the reel support in the rear grip area. The respective second magnet interacts with the first magnets that are arranged distributed along the path, so that a desired magnetic force may be established for centrifugal force compensation. In the rear grip area, accordingly, there is generally an internal second magnet as well as an external second magnet arranged on the reel support. As a result, the radial centrifugal forces may be compensated efficiently.
Corresponding to the internal and external second magnets, first magnets are arranged along the path, i.e. on the rail head along rails, which interact with the internal and external second magnets. These first magnets thus make up the internal and external first magnets. The first magnets are opposite the internal and external second magnets and form a respective magnet pair with these when the reel support is at the position of the respective first magnet. These internal and external magnet pairs are preferably used in addition to the propulsion, i.e. in particular also for the positive and/or negative acceleration.
Because of the wave-shaped course of the path, the direction of the centrifugal forces varies continuously. Expediently, the respective electromagnets, i.e. preferably the first magnets, which run along the paths, are controlled differently during operation as a function of the course of the predetermined path and as a function of the position at which the respective reel support is currently located, so that different magnetic forces are generated in a location-dependent manner at different points on the path in order to compensate for centrifugal forces or also other forces, such as for example tilting moments.
To ensure that the reel support is reliably guided along the rail, the reel support should have a certain length in the direction of the path. However, the length is limited due to the multiplicity of curved sections, some having narrow radii of curvature. Accordingly, a preferred configuration envisions that the reel support has a plurality of articulated, interconnected foot elements. As a result, for the purpose of reliable guidance, the reel support is made as long as possible, and the reel support may also be bent in a certain way so that it may also pass through narrow radii of curvature without mechanical contact between the reel support and the rail. Each respective foot element in this case has a reel foot that embraces the rail head. Expediently, in addition, inner and outer second magnets are arranged inside each of these foot elements.
To form braids, in particular metallic shielding braids, typically 8, 16, 24 or 36 wires are braided together. Because each reel support respectively has one reel with one wire respectively arranged therein, this arrangement requires that the number of reel supports corresponds to the number of reel wires used for the braid. In order to achieve this, therefore, at least two and particularly preferably at least 4 reel supports are guided on each of the at least two predetermined paths. Expediently, exactly two paths are formed. In the variant with exactly two paths, therefore, 4, 8, 12 or even 18 reel supports are guided on each path.
In an expedient configuration, a respective reel support is also equipped with an electromotive reel brake. In comparison to mechanical brakes, this allows defined control of the braking force acting on the respective wire and thus an improved, defined guidance of the wire. Expediently, the reel brake draws energy from the generated magnetic fields contactlessly, for example inductively. Alternatively, a conventional mechanical reel brake may also be furnished.
An exemplary embodiment is explained in greater detail below with reference to the drawings. The respective drawings show the following, in some cases in greatly simplified representations:
In the drawings, parts that have the same effect are assigned the same reference signs.
The braiding machine 2 shown in
The two paths 6A, 6B are designed as circumferentially closed wave-shaped paths. In the exemplary embodiment, the paths each respectively have four outwardly-curved convex sections 18A and four inwardly-curved concave sections 18B corresponding thereto. The respective curved sections 18A, 18B are evenly distributed with the same angular distance to each other. The two paths 6A, 6B are identical to each other, apart from being arranged opposite each other by a twist angle a around a central axis 20. The twist angle a is 45° in the exemplary embodiment and is 360/2n in general, where n is the number of convexly or concavely curved sections 18A, 18B (in the exemplary embodiment, n=4).
The two paths 6A, 6B are inside a travel surface 22, which in the exemplary embodiment of
The exemplary embodiment depicts a total of eight reel supports 4, four reel supports 4 being arranged on each respective path 6A, 6B. In operation, the reel supports 4 of one path 6A run opposite the direction of the reel supports 4 of the other path 6B. Due to the wave-shaped course, the paths 6A, 6B intersect at intersections 24.
By moving the individual reel supports 4 oppositely during the braiding process with a plurality of alternating intersections, the desired braiding 14 is formed. The motion sequence is based on the motion sequence of a conventional bobbin braiding machine. The resulting braid 14 is continuously pulled upward by means of the pull-off apparatus 12. Due to the pulling force exerted in that process, the individual wires 10 are forcibly unwound from the spools 8. A reel drive is not required and is not furnished in the exemplary embodiment. However, a reel drive may be furnished to support the pull-off force.
A respective reel support 4 also has—in a manner not otherwise shown herein—a mechanical or electromotive brake, which may be used to slow down the reel 8 and thus slow the unwinding of the wire 10, so that a defined pulling force may be set. The braking force may be varied by controlling the electromagnetic brake accordingly.
The individual reel supports 4 are individually driven along the paths 6A, 6B respectively by means of an electromagnetic drive, so that they travel along the respective path 6A, 6B at the desired speed.
This electromagnetic drive 26 is based on the concept of the magnetic levitation train and is illustrated by
To form the electromagnetic drive 26, first magnets 28 are generally arranged distributed along the respective path 6A, 6B. These magnets are designed in particular as electromagnets. Second magnets 30 are respectively arranged on the reel support 4, and are preferably designed as permanent magnets. The first magnets 28, which are designed as electromagnets, are controlled during operation in such a way that a continuous (alternating) magnetic field is generated along the respective path 6A, 6B. Control is done by means of the control device 16, which controls the respective first magnets 28 in a suitable way to generate the continuous magnetic field. In this case, the first magnets 28 undergo continuous reversals in polarity. This continuous magnetic field generates a magnetic driving force in the desired direction of motion along the path 6A, 6B.
The first and second magnets 28, 30 are arranged opposite each other and their magnetic force has an axial force component oriented in the axial direction 32. The term “axial direction 32” herein refers generally to the surface normal of the travel surface 22. Due to the axial force component, the reel support 4 is also raised slightly in the axial direction 32, so that it runs along the predetermined path 6A, 6B while suspended and without mechanical contact. Accordingly, in particular, no mechanical friction forces occur (apart from air friction). The use of lubricants is avoided altogether.
A gap 42 is formed between the rail head 36 and the reel foot 38 so that the reel foot 38 may be guided to the rail head 36 without contact. At the same time, a form-locking is formed both in the axial direction 32 and in the radial direction 50.
As may be seen from
A plurality of internal first magnets 28A and a plurality of external first magnets 28B are arranged in turn along the rail 34, corresponding to the internal and external second magnet 30A, 30B. These first magnets in turn are likewise electromagnets. These magnets are preferably used supplementarily to the generation of propulsion.
Their main purpose is to exert additional magnetic holding forces on the reel support 4 so that it is guided on the rail 34 in as contact-free a manner as possible in all situations. In particular, they serve to exert magnetic counterforces against tilting moments and in particular against centrifugal forces. They are usually oriented in a radial direction 50. The term “radial direction” herein means the direction that is perpendicular to the path 6A, 6B, but is within the travel surface 22.
Because the path 6A, 6B is wave-shaped, the centrifugal forces vary in the radial direction 50 as a function of the respective current position of the reel support 4. The internal and external first magnets 28A, 28B are therefore controlled as a function of the current position of the respective reel support 4, in order to compensate for these centrifugal forces in particular, so that the magnetic fields generated at the current position compensate for the currently-occurring forces. The magnetic forces generated in the area of the internal and external second magnets 30A, 30B and acting on the reel support 4 therefore vary depending on position, and different magnetic forces act on the inner side 46 and outer side 48 depending on the position.
To enable the reel support 4 to be guided as well as possible and while also being able to pass through the narrow radii of curvature in the area of the curved sections 18A, 18B without contact, a respective reel support 4 has a plurality of foot segments 52, which are interconnected in a hinged manner. These segments thus form a kind of link chain. The individual foot segments 52 have a slight distance to each other, so that they may be slightly tilted against each other via their articulated connection, as shown in
The length of a respective reel foot 38 and in particular of a respective foot segment is greater than the slots to be bridged in the area of the intersection 54, so that a respective foot segment 52 is also reliably guided in the intersection area.
Due to the many curved sections 18A, 18B and the high speeds, the centrifugal forces in these sections are high. In order to accommodate these at least partially, a curve banking 56 is formed at a respective section 18A. 18B, as is illustrated in a greatly simplified manner by
According to an additional configuration, the paths 6A, 6B run completely on an inner surface 58, as
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2017 202 632.4 | Feb 2017 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2018/053224 | 2/8/2018 | WO | 00 |
