EP0799647A1 - Device for coating a wire with a lubricant - Google Patents

Abstract

Equipment for coating a wire with lubricant, comprising lubricant container (1), an applicator felt (9) in continuous contact with the running wire (5) and a metering device conveying a controlled volume of lubricant from the container (1) to the felt (9). The metering device (12) has at least one pin (15) with a recess (24), which dips at controlled intervals into the lubricant in the container (1) and lifts into touch with the applicator felt (9) so that an approximately equal amount of lubricant is absorbed by the felt (9) at each contact.

Description

It is known that wires, such as electro-insulated winding wires for the production of electrical engineering products, must have good sliding properties so that they can be positioned easily and precisely in the production of windings. In addition, the sliding properties of the wire are intended to protect the electrical insulation layer during processing.

Various methods are known for lubricating wires. Paraffin waxes or paraffin oils are mainly used as lubricants. In the case of waxes, these are applied to the wire, which is still warm, in the form of a melt or a solution in gasoline or another organic solvent. When using solutions, the solvent must be evaporated, which results in economic losses due to solvent losses and considerable pollution of the air in the work area.

Another known method uses aqueous emulsions or dispersions of the paraffins instead of solutions of the paraffins, thereby avoiding the emission of organic solvents, but metering the emulsions with the aid of a felt is difficult. Such methods are therefore not suitable for applying precisely defined amounts of paraffin to the wire surface. They also require an additional drying process.

Devices for solvent-free lubricant application to wires with a lubricant reservoir, an application felt, in contact with which the wire to be coated runs continuously, and a metering device, which conveys a controlled amount of lubricant in liquid form from the lubricant reservoir to the application felt, are known. The problem of such devices is usually the metering device. As such, it is known to use valves operated with solenoid coils or electromagnetically or pneumatically driven piston pumps. Metering devices of this type, which have to convey very small amounts of the liquid lubricant from the lubricant reservoir to the application felt, are extremely sensitive to solid dirt particles, such as scale, which is inevitable when the coating system changes dimensions or comes to a standstill and can fall into the lubricant reservoir.

From DE-A-4 134 070 a device for coating a wire with a lubricant is known, in which the lubricant is applied by means of a strand of material wrapped around the wire, which has been soaked with the lubricant and at a lower feed rate than the one to be coated Wire is advanced. This known device requires, in particular when retrofitting slow systems, relatively high investment costs and is difficult to adapt to systems with very small wire spacings (harp system). Compared to this known device, the melting devices discussed at the outset have the advantage that they enable a very compact design.

The object underlying the invention was to obtain a device for coating a wire with a lubricant, in particular in the form of a melt, which has the simplest possible construction and is insensitive to solid dirt particles.

According to the invention, this object is achieved with a device for coating a wire a lubricant reservoir, an application felt, in contact with which the wire to be coated runs continuously, and a metering device, which conveys a controlled amount of lubricant liquid from the lubricant reservoir to the application felt, and this device is characterized according to the invention in that the metering device has at least one metering pin has a recess and immerses at regular intervals alternating with the recess on the one hand in the lubricant liquid in the lubricant reservoir and on the other hand touches the application felt so that a substantially equal amount of lubricant is sucked into the application felt with each touch.

After filling the recess with the liquefied or dissolved lubricant, the metering pen is expediently held firmly and in contact with the application felt for a long time in order to suck the entire amount of lubricant from the recess into the application felt, although it would also be sufficient to solve the task. if at each touch only a portion of the amount of lubricant received in the recess is transferred to the application felt, provided that this amount of transfer is substantially the same with each touch to maintain a constant concentration of lubricant in the application felt.

The device is particularly suitable for the solvent-free application of lubricant, for example using a wax melt. The device makes use of the surface tension of the solution or, in particular, the melt of the lubricant, without the need for valves for the metering, in order to use the recess on the metering pin, the volume of which is precisely predetermined, to precisely measure the amount of lubricant from the lubricant reservoir at a predetermined interval to be transferred to the order felt.

The depression on the metering pin can be designed in a wide variety of ways and can be, for example, a blind hole, an open simple slot or an open cross-slot. The device can be designed particularly simply and inexpensively if the dosing pins are conventional lens or round-head screws, flat-head screws or Allen screws, the slots and blind holes in the screw head of which serve as recesses in the dosing pins. Lentil or round heads or Allen screw heads are particularly suitable. Flat heads can sometimes be problematic due to the formation of a molten wax meniscus.

The arrangement of the recess on the dosing pen is not critical per se, as long as it is ensured that the recess is completely submerged in the lubricant liquid when immersed in it. However, it is useful to deepen the area in the area of a free end of the Arrange dosing pin, as this makes it easier to submerge in the lubricant liquid and to dab onto the application felt.

The alternating immersion of the recess on the dosing pen in the lubricant liquid and the dabbing on the application felt in order to suck the lubricant liquid from the recess in the application felt is expediently carried out with the aid of a lever and a synchronous motor, expediently a low-voltage psychronic motor. The speed determines the time interval between the immersion of the free lever end with the recess in the lubricant liquid, and the combination of the immersion frequency with the dimension of the recess results in the lubricant metering of the application felt.

Of course, several dosing pins can be provided per lubricant reservoir, which are immersed in the lubricant liquid either simultaneously or in succession. For example, the lever can carry a row of metering pins arranged next to one another and connected to one another, the free ends of which, with the depressions, simultaneously immerse in the lubricant liquid in the lubricant reservoir.

A major advantage of the device according to the invention is that it has a simple, inexpensive and insensitive design and that even substantial amounts of solid particles in the lubricant liquid, such as in the wax melt, practically do not impair the dosage. Tinder deposits in the lubricant reservoir and can be removed for occasional maintenance without the risk of tinder particles clogging passages such as valves or the like.

Since, as a rule, about 1 to 10 mg / min of melted or dissolved lubricant should be transferred to the application felt in order to obtain the desired amount of lubricant on the wire to be coated, it is advisable to adjust the volume of the recess per metering pin in the range from 0.001 to 0. Hold 01 cm ³ . Smaller volumes can cause problems with suction through the application felt due to the capillary action. Larger volumes can be problematic in keeping the liquid in the well when it emerges from the lubricant liquid.

Since the device according to the invention is preferably intended for solvent-free lubricant application, a lubricant melt, such as wax melt, is preferably used, so that it is expedient to heat both the lubricant reservoir and the application felt in such a way that premature solidification of the lubricant melt is prevented. To a To enable continuous work over a longer period of time, it is expedient to supply lubricant liquid in the form of a solution, in particular a melt, to the lubricant reservoir continuously or intermittently, and thus to keep the level of lubricant in the lubricant reservoir essentially the same. The contact of the application felt with the lubricant-filled recess of the dosing pen is expediently every 0.5 to 10 min, preferably every 1 to 3 min. The frequency required depends on the desired application quantity, the speed of the wire to be coated, the capacity of the recess on the dosing pen and other device parameters.

The dosing need only a very small width dimension, which not only enables a compact system, but also makes a small wire spacing possible with harp systems, so that the devices according to the invention are particularly suitable for such harp systems for coating a plurality of wires running parallel to one another.

The application felt suitably has a volume of 1 to 10 cm ³ per metering pen and depending on the wire to be coated. If there is an order felt for several wires, multiply the volume by the number of wires. The application felts have to be replaced from time to time, which can be accelerated if the felts are pre-impregnated with the lubricant and calibrated to approximately the equilibrium level by pressing.

worin

M

= Gleitmittelmenge pro Quadratmeter Drahtoberfläche in mg/m²

t

= Minuten pro Hub der Hebeldosierstifte

m

= Masse Gleitmittel pro Hub

V

= Drahtablaufgeschwindigkeit in m/min

D

= Drahtdurchmesser in Millimeter

To calculate the lubricant application, the amount of lubricant that can be transferred to the application felt with each touch is first determined by dipping the metering pen used onto a felt that has not yet been saturated with lubricant. For example, when using a pan head screw with an M3 cross recess, approx. 5 mg is transferred per touch, with a slotted screw M3 approx. 3 mg. The amount of lubricant applied to the wire when using a solvent-free lubricant melt is then calculated using the following equation: $$\text{M =}\frac{\text{mx 1000}}{\text{tx V x D x π}}$$

wherein

M

= Amount of lubricant per square meter of wire surface in mg / m ²

t

= Minutes per stroke of the lever dosing pins

m

= Mass of lubricant per stroke

V

= Wire run-off speed in m / min

D

= Wire diameter in millimeters

In an application example, a 0.5 mm copper wire is coated at 150 m / min. The dosing pen delivers 5 mg wax per stroke to the application felt. The dosing pen makes a stroke every 2 min. The result is a lubricant coating of approx. 13 mg / m ² .

The dosing pins can touch the application felt from any direction in order to suck the lubricant liquid from the recess of the dosing pen into the felt. For example, the dosing pen can touch the application felt from above, from below or from the side. In terms of design, however, it is probably the simplest to arrange the lubricant reservoir below the application felt and to let the dosing pen touch the felt from below.

Problems sometimes occur with the device according to the invention when the application felts can no longer compensate for a decreasing pressure on the wire to be coated by abrasion on their surface, since their resilience is limited. This means that the application felts often have to be renewed in such cases, as every few days.

Another problem can arise when coating colder wires. When the wire temperature is so far below the melting point of the lubricant that the thermal conductivity of the felts is no longer sufficient to compensate for the energy extracted from the felt, a tube of solidified lubricant forms around the wire, so that penetration to the surface of the wire is prevented . This problem often occurs in practice with wire coating machines with a vertical arrangement of the furnace, in which the furnace exit is usually several meters above the level for the operating personnel. The problems of lubricant application to the cold wire can also occur in processes which start with lubricant solutions, because evaporation of the solvent around the felt can cause oversaturation of the solution and thus blockage of the felt around the wire.

To eliminate any problems that may arise, it is preferred that the device according to the invention has a device for heating the wire to be coated in the area of the application felt, expediently in the area in which the running wire is in contact with the application felt. It is particularly preferred if the wire heating device is a device that generates frictional heat on the surface of the running wire, since this avoids an additional heat source from the outside. The heat generated on the surface of the wire is to compensate for the outflow of energy into the wire to such an extent that solidification of the lubricant is avoided.

A particularly simple and therefore advantageous embodiment of this feature of the device according to the invention is that the friction heat generating device is a flexible strand of material surrounding the wire in the area of the application felt in the form of at least one loop and pressed onto the wire surface under tension. By pressing onto the wire surface, frictional heat is generated during the continuous passage of the wire through the material strand loop. The amount of frictional heat generated can be controlled by the number of loops of the strand of material surrounding the wire, the contact pressure, the thickness and the material of the strand of material.

For example, a braided strand, such as is available in the textile sector, such as made of viscose, can be considered as the strand of material. For example, this is a round braided hollow strand made of cotton from 21 individual cores, which in turn consist of a yarn made of two twisted threads with a weight of 24 mg / m. Of course, numerous other materials can also be used.

The strand of material is arranged stationary, whereby it usually wraps around the running wire several times. Expediently, the strand of material can be fastened shortly before the beginning of the contact between the running wire and the application felt, with a weight attached to the other end of the strand of material after the strand of material and the wire exiting the application felt in order to apply a tensile force and thus a contact pressure to get the surface of the wire.

For example, at a wire temperature of 30 ° C, a painting speed of 30 m / min, a wire diameter of 1 mm and a wax melting temperature of 80 ° C, a five times looping and loading with a weight of 200 g is sufficient to ensure constant complete wetting.

Fig. 1

eine perspektivische Darstellung einer Drahtbeschichtungsvorrichtung nach der Erfindung mit drei Beschichtungsstationen,

Fig. 2

eine perspektivische Darstellung einer Beschichtungsstation nach der Erfindung zur gleichzeitigen Beschichtung von sechs Drähten in einem Harfensystem,

Fig. 3

eine Seitenansicht der in Fig. 2 dargestellten Beschichtungsstation,

Fig. 4a

eine Seitenansicht und

Fig. 4b

eine Draufsicht auf den Teil eines erfindungsgemäßen Dosierungsstiftes mit der Vertiefung nach einer Ausführungsform der Erfindung und

Fig. 5a

einen senkrechten Schnitt,

Fig. 5b

eine Draufsicht eines Dosierstiftes nach einer anderen Ausführungsform der Erfindung und

Fig. 6

eine Seitenansicht einer abgewandelten Beschichtungsstation nach der Erfindung.

The invention is further explained by the drawing. In this mean

Fig. 1

2 shows a perspective illustration of a wire coating device according to the invention with three coating stations,

Fig. 2

1 shows a perspective illustration of a coating station according to the invention for the simultaneous coating of six wires in a harp system,

Fig. 3

3 shows a side view of the coating station shown in FIG. 2,

Fig. 4a

a side view and

Fig. 4b

a plan view of the part of a dosing pen according to the invention with the recess according to an embodiment of the invention and

Fig. 5a

a vertical cut,

Fig. 5b

a plan view of a dosing pen according to another embodiment of the invention and

Fig. 6

a side view of a modified coating station according to the invention.

The system shown in FIG. 1 has three coating stations A, B and C running parallel to one another for coating two wires running in parallel. Each of the coating stations A, B and C has its own heated lubricant reservoir 1, in which there is liquid wax as a lubricant. The lubricant reservoir is supplied with liquid lubricant via the rectangular pipeline 2 and the reservoir 3, which is also used for felt calibration. Each coating station A, B and C has two felt holders 4 with the application felt through which the wire 5 to be coated runs. With the help of the switch box 6 with control and transformer, the temperature of the lubricant reservoir and the drive cycle can be controlled.

2 and 3, partially broken away, is a perspective view of a coating station according to another embodiment of the invention for coating six wires in a harp system. Corresponding parts are shown in FIGS. 2 and 3 with the same reference numerals as in Fig. 1.

The device has a lubricant reservoir 1 which contains melted wax as a lubricant. The lubricant reservoir 1 is refilled with lubricant in the molten state via the rectangular pipeline 2 and the opening 7. The connection between the rectangular pipe 2 and the opening 7 in the bottom of the lubricant reservoir 1 is sealed by the seal 8.

The felt holder 4 with six felts 9 is arranged above the lubricant reservoir 1, through which six wires 5 to be coated run. The felts 9 protrude with a part 10 of their lower end inward beyond the front wall 11 of the lubricant reservoir 1. In the lubricant reservoir 1, a lever 12 is rotatably arranged about an axis of rotation 13 such that the metering pins 15 attached to the band springs 14 of the lever 12 alternately dip into the lubricant melt and dab or touch the protruding part 10 of the felts 9, the being immersed in the Melt in the recesses of the metering pins 15 is transferred to the felts 9 wax quantity by sucking this wax amount through the absorbent felt from the recess of the metering pin.

In the housing 16 there is a synchronous motor 17 which drives the eccentric 18. The latter causes the movement of the lever 12 about its axis of rotation 13 in the two end positions, with the dosing pins 15 dipping into the wax melt in one end position and dabbing the protrusion 10 of the felts 9 in the other end position. In the housing 16, a thermostat 19 is also shown schematically, with the aid of which the temperature control of the entire device is carried out in such a way that the lubricant is in the liquid state until the wires 5 leave the felts 9. This means that the entire coating station shown in FIGS. 2 and 3 is arranged in an outer housing, the inner volume of which is heated by heating cartridges 33. In addition to the parts described above, FIG. 3 shows a cable duct 20, a fastening profile 21 and one of the heating cartridges 33.

In Fig. 3, the lever 12 is also shown with the dosing pins 15 in its two end positions, the end position being drawn out with immersing dosing pins 15 and the end position being shown in dashed lines with dosing pins resting on the felts 9.

4a and 4b on the one hand and FIGS. 5a and 5b on the other hand show two embodiments of dosing pins according to the invention. The embodiment of a metering pen shown in FIGS. 4a and 4b has a lens head 23 on a stem 22 with a recess 24 in the form of an open simple slot.

The embodiment shown in FIGS. 5a and 5b accordingly has a lens head 23 'on a stem 22' with a central recess 24 'in the form of a cruciform blind hole.

Standard slotted or Allen screws can be used as dosing pins. The recesses in the dosing pins for receiving the liquid lubricant can have any shape.

The modified coating station shown in FIG. 6 corresponds to that shown in FIG. 3, which is why the same reference numbers have been used for the same components.

In addition to the components discussed in connection with FIG. 3 and the support bolts denoted by 26 and the capillary tube denoted by 27, a flexible material strand 25 in the form of four loops is around the continuously running wire 5 in the area of contact between wire 5 and application felt 9 looped. One end of the material strand 25 is fixed with a clamping screw 28. At the other end of the material strand 25, a weight 29 is fastened so that the loops of the material strand surrounding the wire 5 are pressed onto the surface of the running wire and thus generate frictional heat.

6 is guided around a deflection mandrel 30 and has a clamping spring 31 at its end. In addition, a monitoring lever 32 is provided.

Claims (14)

Device for coating a wire with a lubricant with a lubricant reservoir (1), an application felt (9) in contact with which the wire (5) to be coated runs continuously, and a metering device that supplies a controlled amount of lubricant liquid from the lubricant reservoir (1) conveyed to the application felt (9), characterized in that the metering device (12) has at least one metering pin (15) which has a recess (24, 24 ') and alternates with the recess (24, 24') on the one hand at regular intervals immersed in the lubricant liquid in the lubricant reservoir (1) and, on the other hand, touches the application felt (9) such that a substantially equal amount of lubricant is sucked into the application felt (9) each time it is touched. Apparatus according to claim 1, characterized in that the recess (24, 24 ') of the metering pin (15) is a blind hole, an open simple slot or an open cross slot. Device according to claim 1 or 2, characterized in that the metering pin (15) has the recess (24, 24 ') at its free end (23, 23'). Device according to one of claims 1 to 3, characterized in that the metering pin (15) is in the form of a conventional screw. Device according to one of claims 1 to 4, characterized in that the recess (24, 24 ') of the metering pin (15) has a volume of 0.001 to 0.01 cm ³ . Device according to one of claims 1 to 5, characterized in that the metering pins (15) are fastened to a lever (12) which can be pivoted into two end positions, the metering pins (15) in one end position with their recess (24, 24 ') Immerse in the lubricant liquid in the lubricant reservoir (1) and touch the application felt (9) in the other end position. Device according to one of claims 1 to 6, characterized in that the lubricant reservoir (1) is heated. Device according to one of claims 1 to 7, characterized in that the application felt (9) is heated. Device according to one of claims 1 to 8, characterized in that a plurality of metering pins (15) are arranged on a common holder (12, 14) and each metering pin (15) is assigned an application felt (9) or a section of a common application felt. Device according to one of claims 1 to 9, characterized in that the lubricant reservoir (1) has a device (2, 7) for the continuous or intermittent supply of lubricant liquid. Device according to one of claims 1 to 10, characterized in that it has a timer device (17, 18) which results in the metering pen (15) touching the application felt (9) every 0.5 to 10 min. Device according to one of claims 1 to 11, characterized in that a device (25) heating the wire (5) to be coated is provided in the area of the application felt (9). Device according to claim 12, characterized in that the device (25) heating the wire is a frictional heat generating device on the surface of the running wire (5). Apparatus according to claim 13, characterized in that the friction heat generating device (25) is a flexible material strand surrounding the wire (5) in the area of the application felt (9) in the form of at least one loop and pressed onto the wire surface under tension.

Images