DE2318884C2 - Device for keeping the wire tension constant in winding machines - Google Patents

Description

15th

The invention relates to a device for holding conitant the wire tension of a thin winding wire when winding electrical coils, in particular Microphone vibrating coil, in which the winding wire from a supply reel via a wire guide, a Wire guide roller and a spring-mounted deflection roller is guided to the winding device, the of the winding wire at least tr'wise wrapped wire guide roller braked with adjustable force will.

Such a device is known from CH-PS 3 99 858.

It is well known that with thin wires that have a low tensile strength, the Can let the supply reel stand still during the winding process, the winding wire axially from the supply reel is drawn. When starting the winding machine, it is then permissible to set it to a high working speed very quickly to accelerate. The supply reel does not have to be accelerated here as it is with tangential unwinding will. Nevertheless, this method is not sufficient to produce particularly thin wires, such as those used for. B. to manufacture of microphone voice coils are used to process.

It is also known that in winding machines an attempt is made to achieve a constant winding force, that a friction brake dependent on the tensile force of the winding wire is controlled in its strength. Most of time a band brake is used for this, which, similar to Prony's bridle, is more or less strong the circumference of a wheel is pressed (CH-PS 2 04 814). This wheel is then also the leading role of the winding wire, which is wound onto it without slipping with the force that the band brake determined on this wheel.

In the method of the type mentioned at the outset, bo the winding force measured with a pulley on a movable lever system. Due to the mechanical position of the lever system, the strength the braking force can be adjusted. With this method there is a constant tensile force of the winding wire to achieve as long as the winding machine works at constant speed, but not in that Moment in which the machine z. B. starts Because between static and sliding friction changes the coefficient of friction generally doubles. During the transition from static friction to dynamic friction the braking force is therefore also about double. Particularly thin wires then often break when they start up the winding machine. Another disadvantage is usually that the winding wire before it goes into the tension regulator runs, must be braked. This is generally done using two strips of felt, each with a put some pressure on each other. The winding wire that runs through the Frictional heat can be heated so much that a wire insulation made of thermoplastic material can melt. When the winding machine is stopped, this winding wire then sticks in the felt brake and will tear every time it is restarted.

Another disadvantage of this arrangement is the mutual reaction of the lever position and Braking force The relatively high braking force when starting the winding machine (static friction) leaves the force swing the measuring lever with the umienkroiie, so that the braking force, which depends on the lever position, is set accordingly small. Of the The wire to be wound up is now released after an initial large braking. The force measuring lever swings back because the braking force has decreased. The braking force increases for the same reason again and the wire to be withdrawn from the braking device moves the force-measuring pulley again so. that the braking force is reduced Speak traction. Very fine and thin wires keep these initial fluctuations in braking force i. a. not out and tear.

In contrast, the subject of the application is based on the task of pulling the wire between stationary and to keep the winding machine running constant and thus a tearing of even the thin one To prevent wire. This uptake is according to the invention solved in that one or more ball bearings are axially braced as a carrier of the wire guide roller and the counterpressure is taken up by a further ball bearing carried by the wire guide roller is in such a way that the braking force of the wire guide roller is braced axially solely by the one or more Ball bearing is adjustable.

The basic idea of the invention is therefore instead of static or sliding friction to use rolling friction, which has a practically constant Rc-ibungswert.

In known devices for keeping constant oes wire tension of a winding wire when winding electrical coils (DE-OS 20 25 887 or DE-GM 17 64 625) is also a ball bearing that the Wire guide roller is axially braced. But here only for the purpose of creating an axial leverage the wire guide roller acting as a rotating friction pulley transferred to. The changing rolling resistance of the ball bearing used in this way has for the Adjustment of the braking force is irrelevant,

The figure shows an exemplary embodiment of the invention shown. Here, an axially braced high shoulder ball bearing is used (11) used as a carrier of the guide roller (2) for the thin winding wire (9) The strength of the axial tensioning pressure can be adjusted within fine limits via a knurled screw (3) and the compression spring (4) can be set by hand. The counterpressure is taken up by a disk groove bearing (5) which, together with the

Schuker bearing (1) is pressed into the guide roller (2). The more the ball bearing (1) is axially tensioned by the spring (4), the greater the rolling resistance and the greater the force required by the winding wire (9) to rotate its guide roller (2) required At no moment does a transition from static friction to smaller sliding friction occur. A similar unwinding process with constant inhibition is guaranteed at all times.

The advantage of a constant rolling resistance for ι ο the bearing (1) of the guide roller (2) can thereby be fully can be transferred to the winding wire by wrapping it fully around the guide roller from /? = 360 ° and a coefficient of friction between winding wire (plastic-wrapped copper wire) and guide roller (e.g. made of hard rubber) of μ = 0.6, the driving ability of the guide roller is calculated according to the Eytelwein equation (see H. Haeder, "Konstruieren und Rechnen", §173b, R. C. Schmidt & Co - Verlag, Berlin, 1948) to 2u

- ^ - = 1.1165 -e ^r "" = 47.5

Here Si means the force with which the winding wire must be pulled on the circumference of the guide roller (2) while it runs onto the guide roller with a reverberant force & c is the groove factor that depends on the shape of the groove in the guide roller the frictional force increases Only with such a flat surface it is 1, otherwise it is always greater than 1. In the above calculation it was set equal to 1.

If the frictional force of the clamped ball bearing (1) on its circumference is less than 47 times the restraining force S> by the device (6), the wire (9) does not slip on the guide roller (2). The winding force is then exclusively determined by the rolling resistance or the inhibition of the ball bearing (1). In such a case, the wire guide between the two braking felt disks (6) can be set so weak that the wire does not heat up when passing through. There is thus no longer any fear of sticking a winding wire insulated with thermoplastic material when the winding machine is stopped. If the restraining force between the two felt strips is still too great, the wrap angle β or the groove factor c can be increased at this point to avoid excessive frictional heat. Before the winding wire is finally fed to the winding machine, rrr Z it still run over the deflection roller (7}. With its spring-loaded mounting (8), this deflection allows the winding wire to yield at high acceleration of the winding machine. This yielding gives the guide roller ( 2) with the ball bearings (1) and (5) enough time to reach the operating speed as well. This reduces the necessary acceleration force that has to overcome the moment of inertia of the guide roller when starting. It also effects a corresponding compensation when the machine is stopped .

1 sheet of drawings

Claims (1)

Claim: Device for keeping the wire tension of a thin winding wire constant when winding electrical coils, in particular microphone voice coils, in which the winding wire of a Supply reel over a wire guide, a wire training roll and a spring-mounted deflection roller is guided to the winding device, wherein the Wire guide roller at least partially wrapped by the winding wire with adjustable force is braked, characterized in that one or more ball bearings (1) as a carrier of the Wire guide roller (2) are axially tensioned and the counterpressure from another, from the wire guide roller (2) supported ball bearing (5) is added, so that the braking force of the wire guide roller (2) can be adjusted solely by the axially tensioned ball bearing (1) 10