Braiding machine

Abstract

The present invention relates to a braiding machine and a method for controlling a braiding machine of this kind. An exemplary embodiment of the braiding machine has a plurality of braided-material carriers, a drive and a control device. The plurality of braided-material carriers are arranged around a common braiding centre of the braiding machine and are each designed to carry a braided material that is to be braided in the common braiding centre. The drive is designed to drive the plurality of braided-material carriers such that they move around the common braiding centre. The control device is designed to control the drive such that a centrifugal force acting on at least one of the braided-material carriers remains nearly constant.

Claims

1. A braiding machine, having: a first set of braiding-material carriers, which are arranged at a first uniform radial distance from a common braiding centre of the braiding machine around the common braiding centre of the braiding machine and are each designed to carry a braiding material to be braided in the common braiding centre; a second set of braiding-material carriers, which are arranged at a second uniform radial distance from the common braiding centre of the braiding machine around the common braiding centre of the braiding machine and are each designed to carry a braiding material to be braided in the common braiding centre; a drive, which is designed to drive at least the first set of braiding-material carriers such that they move around the common braiding centre; a control device, which is designed to control the drive by adjusting an adjustable angular velocity or velocity around the common braiding centre such that during a braiding process, a centrifugal force acting on at least one of the braiding-material carriers remains at least nearly constant; and at least one unbalance sensor, which is designed to determine an imbalance of at least the first set of braiding-material carriers on rotation around the common braiding centre; wherein the control device is designed to take account of the determined imbalance in the control of the drive.

2. The braiding machine according to claim 1, wherein the drive is designed to drive at least the first set of braiding-material carriers such that they rotate around the common braiding centre at an adjustable speed, and the control device is designed to adjust the adjustable speed to an adjusted speed such that a centrifugal force acting on at least one of the braiding-material carriers remains at least nearly constant.

3. The braiding machine according to claim 2, wherein the control device is designed to control the drive of the braiding machine such that at least the first set of braiding-material carriers rotate around the common braiding centre at the adjusted speed.

4. The braiding machine according to claim 2, wherein the control device is designed to adjust the adjustable speed repeatedly during a braiding process.

5. The braiding machine according to claim 1, wherein the control device is designed to control the drive such that a centrifugal force acting maximally on at least one of the braiding-material carriers remains at least nearly constant.

6. The braiding machine according to claim 1, wherein the control device is designed to control the drive as a function of the mass of at least one of the braiding-material carriers carrying the braiding material.

7. The braiding machine according to claim 1, wherein the control device is designed to control the drive as a function of the mass of the braiding-material carrier with the greatest mass of at least the first set of braiding-material carriers.

8. The braiding machine according to claim 1, further having at least one sensor, which is designed to detect a filling level of at least one of the braiding-material carriers with braiding material.

9. The braiding machine according to claim 8, wherein the at least one sensor is designed to detect a filling level of the at least one braiding-material carrier repeatedly during a braiding process.

10. The braiding machine according to claim 8, wherein the control device is designed to deduce the mass of the at least one braiding-material carrier from the detected filling level of the at least one braiding-material carrier.

11. The braiding machine according to claim 2, wherein the control device is designed to adjust the adjustable speed such that the adjustable speed rises linearly during a braiding process.

12. The braiding machine according to claim 11, wherein the adjustable speed rises linearly during a braiding process as a function of a fixed setting in the braiding machine.

13. The braiding machine according to claim 11, wherein the adjustable speed rises linearly during a braiding process as a function of the mass of at least one of the braiding-material carriers.

14. The braiding machine according to claim 11, wherein the adjustable speed rises linearly during a braiding process as a function of the filling level of at least one of the braiding-material carriers.

15. A method for controlling a braiding machine, wherein the braiding machine has a first set of braiding-material carriers, a second set of braiding-material carriers, a drive, a control device, and at least one unbalance sensor, which is designed to determine an imbalance of at least the first set of braiding-material carriers on rotation around the common braiding centre, wherein the control device is designed to take account of the determined imbalance in the control of the drive, wherein the first set of braiding-material carriers are arranged at a first uniform radial distance from a common braiding centre of the braiding machine around the common braiding centre of the braiding machine and are each designed to carry a braiding material to be braided in the common braiding centre, wherein the second set of braiding-material carriers are arranged at a second uniform radial distance from the common braiding centre of the braiding machine around the common braiding centre of the braiding machine and are each designed to carry a braiding material to be braided in the common braiding centre, wherein the method has the steps: driving of at least the first set of braiding-material carriers such that they move around the common braiding centre; and controlling of the drive by adjusting an adjustable angular velocity or velocity around the common braiding centre such that during a braiding process, a centrifugal force acting on at least one of the braiding-material carriers remains at least nearly constant.

16. The braiding machine according to claim 2, wherein the control device is designed to adjust the adjustable speed continuously during a braiding process.

17. The braiding machine according to claim 8, wherein the at least one sensor is designed to detect the filling level of the least one braiding-material carrier continuously during a braiding process.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is to be explained further by means of figures. These figures show schematically:

(2) FIG. 1a a braiding machine known from the prior art;

(3) FIG. 1b a curve of centrifugal force and speed in the braiding machine from FIG. 1a;

(4) FIG. 2 a first exemplary embodiment of a braiding machine;

(5) FIG. 3 a flow chart of an exemplary embodiment of a method for controlling the braiding machine from FIG. 2;

(6) FIG. 4 a second exemplary embodiment of a braiding machine;

(7) FIG. 5a a curve of machine speed and centrifugal force in a braiding machine from FIGS. 2 and 4;

(8) FIG. 5b a comparison of the centrifugal force of the braiding machine from FIG. 1 and the centrifugal force of the braiding machines from FIGS. 2 and 4;

(9) FIG. 5c a comparison of the speed of the braiding machine from FIG. 1 with the speed of a braiding machine from FIGS. 2 and 4; and

(10) FIG. 5d the productivity increase in percent when using a braiding machine from FIGS. 2 and 4 as compared with a braiding machine from FIG. 1.

DETAILED DESCRIPTION

(11) Specific details are set out in the following, without being restricted to these, in order to supply a complete understanding of the present invention. However, it is clear to a person skilled in the art that the present invention can be used in other exemplary embodiments, which may diverge from the details set out below.

(12) It is also clear to the person skilled in the art that the explanations set out below can be/become implemented using hardware circuits, software means or a combination thereof. The software means can be connected to programmed microprocessors or a general calculator, computer, an ASCI (application specific integrated circuit) and/or DSPs (digital signal processors). It is also clear that even if the following details are described in relation to a method, these details can also be realised in a suitable equipment unit, a computer processor or a memory connected to a processor, wherein the memory is provided with one or more programs that carry out the method when they are executed by the processor.

(13) FIG. 1a shows a schematic representation of a braiding machine 1 according to the prior art. The braiding machine 1 has a plurality of bobbins 2, eight in the example shown, as an example of braiding-material carriers. Each of these bobbins 2 serves as a carrier for braiding material to be braided by means of the braiding machine 1 in a braiding centre 3. During operation of the braiding machine 1, the braiding material is supplied radially inwards by each bobbin 2 to the braiding centre 3 of the braiding machine 1. The braiding centre 3 can also be termed the braiding axis of the braiding machine and correspond to the longitudinal axis of the braiding machine 1 or lie parallel to this. According to the example from FIG. 1, the braiding centre 3 corresponds to the centre point of the circular track on which the bobbins 2 move around the braiding centre 3. In operation the bobbins 2 rotate at constant speed around the braiding centre/the braiding axis 3. The braiding material supplied is braided together in a manner known from the prior art by the rotation of the bobbins 2 around the rotating and braiding centre 3 and the removal of the respective braiding material along the braiding centre 3.

(14) According to the schematic representation from FIG. 1a, the bobbins 2 are carried by a bobbin carrier 2a. By rotation of the bobbin carrier 2a and thus movement of the bobbins 2 around the common braiding centre 3, a braiding process can be carried out. In addition, an immobile bobbin (not shown) can be provided, so that the braiding material provided by the plurality of bobbins 2 and the braiding material provided by the immobile bobbin are braided with one another in a known manner. Alternatively it is conceivable for the plurality of bobbins 2 to be arranged on a first bobbin carrier 2a, for example an upper ring, and for other bobbins 2 to be arranged on a second bobbin carrier (not shown), for example a lower ring. In this case a braiding process can take place in a known manner by opposed movement, e.g. opposed rotation, of the two common bobbin carriers, for example.

(15) In braiding machines known from the prior art, such as the braiding machine 1, a constant speed is set. This speed is selected so that a maximum load of the braiding machines is not exceeded. Known braiding machines are often limited to a maximum speed of 175 rpm and are operated at this maximum speed. At a maximum filling level of 100% of the bobbins 2, a permitted centrifugal force of 221.43 N thus acts on each full bobbin 2. FIG. 1B illustrates how, at a constant speed (see the speed curve 4) and a filling level of 100%, the centrifugal force (see the centrifugal force curve 5) is maximal and decreases as the filling level of the bobbin 2 decreases. This means that the highest load arises with a completely full/filled bobbin 2. As the filling level of the bobbin 2 decreases, the centrifugal force and thus the load on the braiding machine 1 become steadily smaller. This has the consequence that, although braiding machines from the prior art seek to prevent overload of the braiding machine 1, they are not optimised to the desired extent for maximum productivity.

(16) FIG. 2 shows a first exemplary embodiment of a braiding machine 10. The basic structure of the braiding machine 10 is based on the structure of the braiding machine 1 from FIG. 1a, so that reference is made to the statements regarding this. The bobbin carrier 20a from FIG. 2 can thus be a common bobbin carrier for carrying out the braiding process or one of two opposed bobbin carriers, for example an upper ring or a lower ring, the other one of which is not shown in FIG. 2.

(17) The braiding machine 10 from FIG. 2 has bobbins 20 as an example of braiding-material carriers. Each of the bobbins 20 serves as a carrier for braiding material to be braided. The bobbins 20 are rotated by a drive 12 of the braiding machine 10 around a common braiding axis 30/around a common braiding centre 30, which corresponds to the centre of rotation of the bobbins 20 according to FIG. 2. In contrast to the braiding machine 1 from FIG. 1a, however, no speed is preselected and kept constant on the braiding machine 10 from FIG. 2. On the contrary, on the braiding machine 10 from FIG. 2 a centrifugal force acting on one or more of the bobbins 20 and contingent on the rotation is kept constant.

(18) The braiding machine 10 has a control device 40 and a sensor 50 for this purpose. The sensor 50 detects repeatedly, e.g. continually, the filling level of one or more of the bobbins 20. The sensor 50 is designed, for example, as a distance sensor for this. The sensor 50 can detect the respective distance to the bobbins 20 passing by, for example by means of laser. Since the filling level of the bobbins 20 constantly changes, the distance detected by the sensor 50 also changes accordingly. It is assumed below by way of example that the sensor 50 repeatedly detects the filling level of all bobbins 20. The mass of each of the bobbins 20 can be determined from this either directly by the sensor 50 or by the control device 40.

(19) Alternatively or in addition to the configuration of the sensor e.g. as a distance sensor for detecting the filling level of the bobbins 20 and the indirect determination of the mass of the bobbins 20 from the detected filling level, each bobbin 20 can be provide with a force sensor, for example. The centrifugal force acting in each case can then by measured directly by means of the force sensor. This means that, alternatively or additionally (e.g. for reasons of redundancy) to the sensor 50, a sensor can be provided at each of the bobbins 20, which directly measures the centrifugal force acting on the bobbin 20.

(20) Independently of the precise determination of the mass, the centrifugal force acting on the respective bobbin 20 can be determined by the control device 40 from the mass of a bobbin 20 with a knowledge of its radial distance r from the centre of rotation, i.e. from the braiding centre 30. From the mass of each bobbin 20 the control device can deduce the acting centrifugal force in principle for each bobbin 20. The centrifugal force F results from the angular velocity co as follows:
F=m*ω.sup.2*r

(21) The angular velocity co is directly proportional to the speed n, as the following applies:
ω=2*n

(22) Thus the following results for the connection between centrifugal force F and speed n:
F=4*n.sup.2*n.sup.2*m*r

(23) The number n (Pi) is known and constant. The mass m and centrifugal force F act in a directly proportional manner. This means that as mass decreases, the centrifugal force F acting on a body decreases in direct proportion. Due to this, in the case of a decreasing filling level and thus decreasing mass m of the bobbins 20, the speed n can be increased accordingly and the acting centrifugal force nevertheless kept constant. The control device 40 determines the speed n such that the centrifugal force F acting on the bobbins 20 remains constant. The speed n of the braiding machine 10 can thereby be increased with the decrease in the bobbin filling level. This increases productivity. Let it be stated here purely by way of example that the speed can be adjusted in a range from 150 rpm to 250 rpm or in a sub-range from this during the braiding process.

(24) In the example from FIG. 2, the filling level of all bobbins 20 is identical purely as an example. This can occur in practice, for example, when the braiding machine 10 is first commissioned or when all bobbins 20 are exchanged at the same time and replaced by completely filled bobbins 20. In this case it is sufficient if only the filling level of one of the bobbins 20 is detected. Alternatively the filling level of all bobbins 20 can be detected. Regardless of this, it is sufficient at any rate according to this example to know the mass of one of the bobbins 20 on the part of the control device 40 and to take it into account for control. In this case, based on the determined mass m of one of the bobbins 20 and thus with sufficient accuracy the mass m of each of the bobbins 20, the control device 40 will adjust the speed n such that, as the mass m of the bobbin(s) 20 decreases, the centrifugal force F remains constant. The speed n can be determined from the above formula by the following dependence:
n.sup.2=F/(4*n.sup.2*m*r)

(25) Not only is the speed or the speed adjustment a quadratic function, but also the mass of the bobbin 20 or the loss of mass of the bobbin during production/during the braiding process (the mass and the loss of mass are proportional to n/4*(D.sup.2−d.sup.2)). D is the outer diameter of the bobbin at maximum bobbin filling. D decreases during the braiding process and is therefore not constant. d is the core diameter of the bobbin itself and is therefore constant. Thus d can also be understood as the diameter of the bobbin without fill material. In this way it is possible to determine from the known proportionality the loss of mass from the outer diameter of the bobbin 20 with the bobbin filling present in each case and the constant diameter of the bobbin 20 without fill material.

(26) Further details regarding the control of the braiding machine 10 are now described in relation to FIG. 3.

(27) In a step S302, the drive of the braiding machine 10 drives the bobbins 20 such that they move around the common braiding centre 30, e.g. rotate. They can rotate e.g. at an adjustable speed n around the braiding centre 30. In steps S304 and S306 the drive is controlled such that a centrifugal force acting on at least one of the bobbins 20 remains at least nearly constant. For this the filling level of the bobbins 20 is first detected by means of the sensor 50 in step S304. In addition, based on the respectively detected bobbin filling level, a mass of the bobbin 20 and thus of each of the at least nearly identically filled bobbins 20 is determined by the control device 40 in step S304. The determined mass of the bobbin 20 can now be used to determine an adjusted speed with the aid of the relationship
n.sup.2=F/(4*n.sup.2*m*r)

(28) From this relationship the control device 40 can directly determine the adjusted speed n in step S306, as the radial distance r to the braiding centre 30 is known and constant, the mass m has been determined and the centrifugal force F is kept constant. This means that for the latter, the previously existing value, which was selected at the start for the braiding machine 10, for example, is used.

(29) In step S302 the braiding machine 10 is driven at the adjusted speed n. Steps S302 to S306 can be repeated e.g. continually during the braiding process.

(30) A second exemplary embodiment of the braiding machine 10 is shown in FIG. 4. The braiding machine 10 from FIG. 4 is based on the braiding machine 10 from FIG. 2. Identical reference signs are used accordingly for the identical elements and the braiding machine is also described using the same reference sign. The braiding machine 10 from FIG. 4 has a slightly adapted algorithm. The braiding machine 10 from FIG. 4 can optionally also have an unbalance sensor 60. As indicated in FIG. 4, the bobbins 20 of the braiding machine 10 have a different filling level at least in some cases, purely as an example.

(31) The adapted algorithm is adjusted so that the filling level of all bobbins 20 is detected by means of the sensor 50 (this corresponds to a possible procedure from FIG. 2), but to determine the speed only the filling level of the maximally filled bobbin 20b and thus the maximal mass of all bobbins 20 is considered. Expressed another way, the adjustable speed is determined from the filling level of the bobbin 20b with the maximum filling level and thus of the bobbin 20b with the maximum mass. If one of the bobbins 20 is exchanged, the bobbin 20b of maximum mass can change.

(32) The control device 40 can use the greatest mass m_max of the determined masses m to determine the adjusted speed as follows.

(33) From the relationship
F=4*n.sup.2*n.sup.2*m_max*r
the control device 40 can determine the adjusted speed n directly, as the radial distance r to the braiding centre 30 is known and constant, the greatest mass m_max is known and the centrifugal force F is kept constant. This means that for the latter the previously existing value, which was selected at the beginning for the braiding machine 10, for example, is used.

(34) In addition, an imbalance in the braiding machine 10 can be determined by means of the unbalance sensor 60. This imbalance results from the different filling level and thus the different mass of the bobbins 20. Since the imbalance increases as the speed rises, this can be optionally monitored. The control device 40 can take account of the imbalance when adjusting the speed n. It is e.g. conceivable that it is established with the aid of the unbalance sensor 60 that a maximally permissible imbalance is exceeded if the speed determined by the control device were/is used. The control device 40 can then reduce the speed such that the maximally permissible imbalance is not exceeded.

(35) FIGS. 5a to 5d illustrate the advantages of the braiding machines 10 from FIGS. 2 and 4.

(36) As is recognisable from FIG. 5a, the centrifugal force is kept constant on the braiding machines 10 from FIGS. 2 and 4 (see the curve 110 of the centrifugal force Fk). This has the consequence that as the filling level of the bobbins 20 decreases (from 100% to 0%), the possible speed increases (see the curve 210 of the speed; rising curve illustrated by multiplication of speed n by a variable value b>1).

(37) FIG. 5b shows the curve 110 of the centrifugal force of the braiding machines 10 of FIGS. 2 and 4 compared with the curve 100 of the centrifugal force on the braiding machine 1 from FIG. 1a. It is to be recognised that the centrifugal force on the braiding machines 10 remains constant independently of the filling level of the bobbins 20 (constant centrifugal force Fk), while the centrifugal force of the braiding machine 1 decreases as the filling level decreases (decreasing curve illustrated by multiplication of centrifugal force F by a constant value a<1).

(38) In FIG. 5c, the curve 210 of the speed on the braiding machines 10 from FIGS. 2 and 4 is compared with the curve 200 of the speed on the braiding machine 1 from FIG. 1a. As is to be recognised, at the maximum filling level of 100% the speed of the braiding machines 10 is slightly below the speed of the braiding machine 1 purely as an example. Already at a filling level of approx. 85%, the two filling levels approximate to one another and are at least nearly identical. From a filling level of 80% onwards the speed of the braiding machines 10 is already greater than the speed of the braiding machine 1. For a majority of the braiding process the braiding machine 10 from FIGS. 2 and 4 can thus be operated at a higher speed than the braiding machine 1 from FIG. 1a. This increases productivity. The starting speed of the braiding machines 10 can already be at or higher than the speed of the braiding machine 1.

(39) The extent of the productivity increase results purely by way of example from FIG. 5d. The curve 300 of the productivity of the braiding machine 1 is constant regardless of the filling level of the bobbins 2, as the speed is constant. On the other hand, the curve 310 of the productivity on the braiding machines 10 rises as the filling level of the bobbins 20 decreases. At a filling level of 100% down to below 85%, the productivity of the braiding machines 10 is still slightly lower than on the braiding machine 1, but at a filling level of 85% the productivity converges. The braiding machines 10 can alternatively even start immediately at the maximum permissible speed. Thus a productivity increase would be achieved immediately (on start-up of the braiding machines 10). As the filling level decreases from under 85% to 0%, the productivity advantage of the braiding machines 10 compared with the braiding machine 1 rises ever further. Alternatively, after reaching a certain limit speed, the braiding machine 10 could be operated at a constant speed until reaching the empty status (filling level 0%). The curve 320 of productivity averaged over the braiding process shows that the averaged productivity of the braiding machines 10 is above the constant productivity of the braiding machine 1. Averaged over the entire process, a considerable increase in productivity of up to 21% can thus be achieved.