Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
  • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
  • H01F41/02—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets
  • H01F41/04—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties for manufacturing cores, coils, or magnets for manufacturing coils
  • H01F41/06—Coil winding
  • H01F41/094—Tensioning or braking devices

Definitions

• the invention relates to the technical field of machines for making electrical windings, for example in the field of production of stators or rotors of electric motors, or other components.
• Winding machines are commonly equipped with a device called “wire-tensioner” which has the task of maintaining a proper traction of the conductor wire, necessary to feed the element responsible for forming the coils and make it work correctly.
• the wire-tensioning devices of the prior art comprise: a braked pulley and a vertically tilting arm.
• the pulley is braked by a suitable device, typically a hysteresis brake.
• the tilting arm carries an end pulley; the conductor wire winds around the braked pulley and then around the pulley of the tilting arm, from which it descends towards the winding device.
• the position of the arm is read by an appropriate sensor, for example a Hall sensor, and the brake is controlled so that the braking torque on the pulley is a function of the arm position.
• the arm position is read on a scale from 0 to 100; the system is set to keep the arm in an optimal range, for example 50-60; the brake is powered with 0 to 24V depending on the arm position.
• variations in the wire traction determine a lowering or raising of the arm and, consequentially, an increase or decrease of braking torque, creating a self-regulating servo system.
• the purpose of the wire-tensioning device is to maintain a tension force on the wire as constant as possible because non-uniformities in wire tension can cause imperfections in the geometry of the winding and compromise its performance. This result, however, is difficult to achieve and represents a technological challenge.
• Needle winders feature coils formed by a needle with alternating movement on the vertical axis, and are used to make windings in narrow spaces or on pole pieces directed towards the inside of a core, as in external stators of electric motors. Maintaining a constant wire tension in a needle winder is made difficult by the movement of the needle itself, which continuously subjects the wire to traction and release.
• wire-tensioning devices can operate satisfactorily only within a certain range of tension and wire diameter.
• the mass per unit length and, therefore, the inertia of the wire depend on the wire diameter.
• wire gauge we speak of "wire gauge”.
• a large diameter wire requires a greater braking torque than a small diameter wire, while a small diameter wire requires less braking power but fast response and, therefore, low inertia.
• a brake sized for a small wire is not powerful enough to work with a large diameter wire, but after all, a brake sized for large diameter wires has inertia that makes it unsuitable to work with small wires.
• a wire-tensioning device regardless of the complexity or degree of sophistication, has a defined working range (wire traction range) and often, depending on the conductor wire diameter, it may have to operate near the low or high limit of this range, which is not optimal.
• the invention aims to improve the known art of wire-tensioning devices in winding machines for electrical windings.
• the invention aims to increase the flexibility of the wire-tensioning devices, allowing to operate in optimal conditions with different traction values.
• the goals are achieved with a wire-tensioning device according to the claims.
• the idea behind the invention is to create a modular device with a plurality of braked pulleys and respective braking devices sized to operate with different traction values and, therefore, suitable for wires of different gauge and diameter.
• the braking torque and inertia of the braking devices, as well as the dimensions of the pulley, can be adapted for a specific traction range and/or diameter of the conductor wire.
• a device according to the invention provides different pulleys with different braking action.
• the resulting advantage is greater flexibility and less time to set up the machine according to the characteristics of the conductor wire.
• the wire-tensioner can always operate in an optimal range and it achieves the desired effect of keeping the wire traction substantially constant.
• Another aspect of the invention is a method for controlling the tension of a conductor wire in a winding machine for making electrical windings, according to the appended claims.
• a wire-tensioning device is arranged to deliver a conductor wire with a controlled tension force.
• tension indicates the force present on the wire, conventionally expressed in grams; for example, in common applications, this force is approximately between 100 g and 500 g (approximately 1 - 5 N).
• the wire is dragged by the winding machine, and the wire-tensioner according to the invention regulates the tension of the wire by means of the braking torque on the pulleys.
• the device comprises a tilting arm that carries an idler pulley for the conductor wire; a first braked pulley adapted to accommodate the conductor wire and associated with a first braking device; at least a second braked pulley also adapted to accommodate the conductor wire and associated with a second braking device.
• the second braking device is controlled independently of the first braking device, and the maximum braking torque deliverable by the second braking device is greater than the maximum braking torque deliverable by the first braking device.
• the second braking device having greater torque and typically greater inertia, is consequently suitable for a conductor wire with large diameter, while the first braking device, less powerful but with less inertia, is suitable for small diameter wires.
• said arm tilts relative to a pin or fulcrum with horizontal axis, therefore it moves on a vertical plane.
• Said first and second braking devices preferably comprise an electromagnetic induction brake.
• a wire-tensioning device generally comprises an elastic return system of the tilting arm.
• the elastic reaction of said system is adjustable.
• the tilting arm is connected to at least two elastic return devices, and at least one of said two elastic return devices can be activated or deactivated on command, to vary the elastic response of the tilting arm with respect to the tension values of the wire.
• Said elastic return devices are preferably air springs.
• an air spring comprises a cylinder and a rod with one end pivoted to the tilting arm.
• An air device is preferred as it is easily activated or deactivated by providing or interrupting a feed of compressed air.
• a plurality of air springs can be provided which are connected to a common compressed air inlet, in which the feed to the air springs can be activated or deactivated via solenoid valves.
• the wire-tensioner according to the invention can be implemented as a modular system, comprising different wire-tensioning modules with different braking effect.
• Each wire-tensioning module preferably comprises a respective braked pulley, adapted to accommodate a conductor wire, and a respective braking device associated with said pulley.
• the tilting arm can be alone in a system with multiple modules, that is, providing a main module equipped with tilting arm, and further additional modules equipped with braking system calibrated for a specific traction range.
• a preferred embodiment has two modules, but embodiments with a higher number of modules are possible.
• a method for controlling the wire tension using the modular device according to the present invention includes winding the conductor wire around a pulley selected based on the torque of the respective braking device, depending on the desired traction and/or on the diameter of the wire itself.
• the conductor wire is dragged by a winding machine located downstream of the wire-tensioning device, and the tension of the wire is controlled by regulating the braking torque delivered by the braking device of the pulley around which the wire is wound, so that said pulley works as a braking pulley, counteracting the dragging of the wire and thus regulating the tension of the wire itself.
• the conductor wire, exiting the pulley selected as braking pulley, can also be wound around another pulley whose braking effect is deactivated, so that said pulley works as an idler pulley towards the tilting arm.
• the brake associated with said idler pulley can be activated to provide additional braking action.
• the first braked pulley i.e. the pulley with the least braking torque
• the first braked pulley is positioned so that the direction of the conductor wire exiting said pulley is aligned with the idler pulley of the tilting arm (also called compensation arm). More in particular, the exiting direction from said pulley is coplanar or substantially coplanar, in a vertical plane, with the direction of entry around the idler pulley of the arm.
• Fig. 1 shows a wire-tensioning device 1 comprising a first module 101 and a second module 102 (two-way device).
• Device 1 comprises a tilting arm 103 (also called “compensation arm") which is in this example associated with module 101.
• Said arm 103 carries an idler pulley 104 for the conductor wire.
• One further idler pulley 105 is fixed to the frame of module 101.
• the device comprises a first braked pulley 106 and a second braked pulley 206, being part of the first module 101 and second module 102, respectively.
• the pulleys have a groove 116, 216 adapted to accommodate the conductor wire, preferably the groove is lined with a rubber or similar material adapted to reduce slippage between the wire and the pulley ("rubberized" pulley).
• Pulley 106 rotates around axis A-A and pulley 206 rotates around axis B-B.
• Arm 103 tilts with respect to a pin 107 and is provided with a Hall sensor to read the position of arm 103 (angle formed by the arm with respect to a reference); an air spring 108 is fixed to the arm 103 and is operable via a compressed air inlet 109.
• Said air spring 108 essentially comprises a cylinder 130 and a rod 131 ending with an eyelet pivoted to the arm 103.
• the connection point between rod 131 and arm 103 is on the opposite side of pin 107 with respect to the idler pulley 104.
• Pulley 106 is connected to a hysteresis brake 120 mounted inside module 101.
• pulley 106 is keyed onto a shaft and brake 120 acts on said shaft.
• Pulley 206 is similarly connected to another hysteresis brake 220 mounted in module 102.
• Brake 220 is capable of delivering a greater braking torque than brake 120, for this reason, brake 220 is suitable to operate with large diameter conductor wires; brake 120 is weaker but has less inertia and, consequentially, it is suitable for small diameter wires.
• the two brakes 120, 220 are independently controlled, for example, each can be operated with a 0-24V input proportional to the position of arm 103, where the braking torque is proportional to the input voltage.
• the braking torque is with respect to the rotation around the respective axis A-A for pulley 106 and axis B-B for pulley 206.
• Fig. 2 also shows an electronic board 112 which governs the wire-tensioning device and implements the control system that allows, for example, to set the position control range of the tilting arm.
• Fig. 3 shows a variant in which device 1 is equipped with a second air spring 110, similar to spring 108 previously described. Also spring 110 is operated from inlet 109 and can be activated or deactivated by a solenoid valve 113. Air springs 108 and 110 may have identical or different characteristics. Note that said springs have a different lever arm compared to fulcrum 107 (distance between the fulcrum and the pin connecting with the rod) which influences their reaction at equal strength.
• the solenoid valve 113 allows the compressed air to be sent only to spring 108, or to both springs 108, 110. By operating only one or both air springs, the elastic reaction of arm 103 can be modified depending on the working wire diameter.
• the device illustrated can be defined as a two-way wire-tensioner, thanks to the presence of the two pulleys 106, 206 with different braking torque and, consequentially, suitable for operating in different wire diameter and/or tension force ranges. Please note that a larger number of units/modules can be provided. A preferred arrangement of the modules involves placing them side by side, as illustrated.
• a multi-module system can comprise a single tilting arm mounted on one of the modules, as in the example of the figures in which device 1 comprises only one tilting arm 103 that exits module 101; this solution is preferred for simplicity, however the invention provides variants in which several modules are equipped with a respective tilting arm.
• Fig. 4 shows use with a conductor wire 300 small in diameter.
• Wire 300 is wound around pulley 106 and subsequently around the idler pulley 105 and the pulley 104 of the tilting arm 103.
• the winding angle of the wire around pulley 106 is sufficient to ensure secure contact without slippage, preferably of at least 360°.
• pulley 206 is not working.
• Fig. 5 shows usage with a conductor wire 310 of diameter and gauge greater than wire 300.
• Wire 310 in this case is wound around pulley 206 (wire portion 311) with sufficient angle for the braking action, and pulley 106 is used only as idler pulley (wire portion 312), being vertically aligned with arm 103.
• the wire-tensioning action is exerted by brake 220 of pulley 206; brake 120 can be deactivated, in which case, pulley 106 is essentially a neutral pulley, or it can be operated, in which case, also pulley 106 can exert a limited braking action.
• the wire-tensioning device comprises a double spring, as in the variant in Fig. 3 , by working with the small diameter wire as in Fig. 4 preferably only spring 108 is operated; while working with the larger diameter wire as in Fig. 5 preferably both springs 108 and 110 are operated. By doing so, the elastic response and the cushioning effect of the tilting arm 103 are adapted to the different traction of the wire.
• the first pulley 106 is positioned so that the direction of the conductor wire exiting said pulley is substantially coplanar, in a vertical plane, with the direction of entry around the idler pulley 104 of the compensation arm 103. This is also expressed by stating that pulley 106 is aligned with the exit path or "runway" of the wire. This arrangement makes it easier to select and switch between winding with a small diameter conductor wire and winding with a greater diameter conductor wire, as the exit direction of the wire remains the same.

Landscapes

• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Tension Adjustment In Filamentary Materials (AREA)

Priority Applications (1)

Applications Claiming Priority (1)

Publications (1)

Family

ID=91470056

Family Applications (1)

Country Status (1)

Citations (3)

• 2024
  • 2024-04-17 EP EP24170832.0A patent/EP4636795A1/fr active Pending

Patent Citations (3)

Similar Documents

Legal Events