EP0116498A1 - Wire cooling device for wire drawing machine - Google Patents

Abstract

Wire cooling device for a wire drawing machine comprising a capstan for pulling the wire passing through a die, characterized in that it consists of a plurality of slots or grooves (6, 9), formed in the external wall of the capstan, supplied one (6) with coolant and used to bring this liquid into contact with the wire which is wound on the capstan and whose contiguous turns (4a) form a jacket external to the capstan in which the coolant circulates; the others (9) supplied with pressurized air intended for the recovery and evacuation of the coolant.

Description

The present invention relates to a wire cooling device for a wire drawing machine.

The reduction in cross section of a metal wire by drawing, that is to say by pulling through a die by means of a winding capstan, like any mechanical deformation process, generates heat which has the effect to increase the temperature of the drawn wire and of the tools in contact with this wire. This increase in temperature modifies the mechanical characteristics of the wire. This modification is all the more harmful since the drawn wires are made of steel with a higher carbon content and it reveals well-known aging phenomena.

This is particularly so with regard to drawing machines of the "dry" type where the lubricant used to facilitate the drawing is a powdery and dry product having no cooling role.

In order to limit the heating of the wire and to keep it within acceptable limits from a metallurgical point of view, modern wire drawing machines are provided with wire cooling devices which are basically of two kinds: indirect cooling devices and direct cooling devices.

Indirect cooling consists of cooling by circulation of liquid the tools in contact with the wire, that is to say the die and the traction capstan. The residence time of an elementary slice of wire in the die being extremely short, this cooling is very limited. On the other hand, the capstan allows a large number of turns to be stored, thereby increasing the contact surface between the hot wire and the cooled capstan. This cooling is therefore more effective but is limited by its principle of heat exchange on the one hand, and by the purely linear contact between the round wire and the cylindrical capstan on the other hand.

• - à air : un soufflage autour du cabestan crée une chemise d'air ascendant et refroidit le fil accumulé sur le cabestan. Ce procédé est fré- quemment employé de pair avec le refroidissement intérieur par liquide du cabestan décrit ci-dessus. Il convient de noter que son efficacité est d'autant plus grande que le fil est d'un diamètre plus faible. Ses limites sont évidentes du fait de la faible chaleur spécifique de l'air. Les principaux inconvénients de cette façon de procéder sont le bruit et le brassage polluant des savons et résidus de savon de tréfilage toujours présents sur la machine,
• - par liquide : plusieurs systèmes existent et consistent à arroser le fil pendant son parcours entre la sortie de la filière et le point de tangence avec la chasse du cabestan.

Direct cooling can be considered alone or in addition to indirect cooling and it is of two types:

• - with air: a blowing around the capstan creates an ascending air jacket and cools the wire accumulated on the capstan. This process is frequently used in conjunction with internal liquid cooling of the capstan described above. It should be noted that its effectiveness is all the greater the smaller the wire. Its limits are obvious due to the low specific heat of the air. The main drawbacks of this procedure are the noise and polluting mixing of the soaps and wire drawing soap residues still present on the machine,
• - by liquid: several systems exist and consist in watering the wire during its course between the exit of the die and the point of tangency with the hunting of the capstan.

These systems are not very effective on fast machines, because, given the small space available, the residence time of the wire in these systems is between a few tenths and a few hundredths of a second. In addition, in the event of breakage of the wire, the coolant may pass through the die and mix with the wire drawing soap located upstream of the die. It should also be noted that these systems usually require considerably longer threads and make it more difficult to thread the machine.

Another method consists in spraying the cooling liquid from the outside directly onto the turns of wire accumulated on the capstan, which makes it possible to obtain a longer exposure of the wire to cooling. Such a system would be effective but the runoff and centrifugation of liquid and the humid atmosphere surrounding the machine are practically not acceptable.

The production of a wire drawing machine being a function of its speed, the wire drawing machines are looking for more and more fast machines but as the heating is also a direct function of the speed one encounters a problem difficult to solve.

This problem is solved, in accordance with the invention, by making slots or grooves in the external wall of the capstan, each supplied with coolant, serving to bring this liquid into contact with the wire which is wound on the capstan and whose turns, contiguous, form a liner external to the capstan in which the coolant circulates, the others supplied with pressurized air intended for the recovery and evacuation of the coolant.

According to the invention, the outer wall of the capstan has other slots or grooves also connected to the source of pressurized air and intended to regulate the circulation of the coolant in the liner created.

The various characteristics and advantages of the invention will emerge from the description which follows of one of its possible embodiments. It is clearly stated that this is only an example and that all other provisions could be adopted without departing from the scope of the invention.

• Fig. 1 une vue schématique en élévation d'une machine à tréfiler dont le cabestan présente le dispositif suivant l'invention,
• Fig. 2 une vue en coupe à échelle agrandie, par un plan axial, de ce cabestan.

During this description, reference is made to the attached drawings which show:

• Fig. 1 is a schematic elevation view of a wire drawing machine, the capstan of which has the device according to the invention,
• Fig. 2 a sectional view on an enlarged scale, by an axial plane, of this capstan.

As can be seen in FIG. 1 the wire drawing machine comprises a wire drawing capstan 1 which is presented as a cylindrical body driven in rotation by a motor 2 and a transmission 3. The lower part of the capstan 4 draws the wire 4a through the die 5 placed upstream. Several turns are formed on the capstan by the operator when threading the machine in order to obtain the capstan effect necessary for drawing and in order to cover the cooling area on the capstan. As the drawing takes place, the turns of wire go up along the capstan before going to the downstream drawing block in the case of multiple drawing machines or to the wire receiving devices in the case of the last block of multiple machines. or in the case of monoblock drawing machines.

• les fentes ou gorges 6 servent à amener le liquide de refroidissement aux spires de fil 4a qui s'enroulent sur le cabestan. Dans ce but, elles sont reliées, par des orifices 6a, à une canalisation 7 de liquide de refroidissement, eau par exemple, alimentée par un joint tournant 8, les fentes ou gorges 9, qui elles aussi débouchent à l'extérieur du cabestan et qui règnent sur une certaine hauteur, sont, à leur partie supérieure, reliées, par des orifices 10, à une alimentation Il en air comprimé par l'intermédiaire d'un joint tournant 12. A leur partie inférieure les fentes ou gorges 9 débouchent, par des orifices 13, traversant la paroi du cabestan, reliés à une canalisation (non représentée) de reprise et d'évacuation du liquide de refroidissement.

In accordance with the invention, the capstan has slots or grooves on its outer periphery opening out to the capstan and which each have their role:

• the slots or grooves 6 serve to bring the coolant to the turns of wire 4a which are wound on the capstan. For this purpose, they are connected, via orifices 6a, to a pipe 7 for coolant, water for example, supplied by a rotary joint 8, the slots or grooves 9, which also open out of the capstan and which reign over a certain height, are, at their upper part, connected, by orifices 10, to a supply Il of compressed air by means of 'a rotating joint 12. At their lower part the slots or grooves 9 open, through orifices 13, passing through the wall of the capstan, connected to a pipe (not shown) for taking up and discharging the coolant.

Above the grooves 6 are formed slots 14 supplied with pressurized air in a manner similar to that of the orifices 10 of the grooves 9, by pipes 11a coupled to the rotary joint 12. The rotary joints 8 and 12 can moreover be combined in a single double liquid-air joint.

Thanks to the arrangements according to the invention, the turns of wire 4a, in intimate contact with each other and with the capstan, by the very fact of the wire drawing effort, constitute a jacket and the liquid provided by the grooves 6 creeps into the curvilinear triangular spaces 15 formed between the periphery of the capstan and the turns of wire. This continuous space constitutes an Archimedes screw and the liquid is thus animated by an upward and rotary movement towards the upper layers of wire. This ascent is limited by the back pressure of the air coming from the slots 14. The liquid is thus forced to travel along planes sersibly perpendicular to the axis of the capstan until it is collected by the slots or grooves 9 under the action of gravity and the air injected through the orifices 10 and evacuated through the orifices 13.

According to an alternative embodiment, the orifices 10, 13 and 14 are connected by means of the pipes 11, 1aa and the rotary joint 12 to a suction system (not shown).

From the above it follows that the device according to the invention is a mixed cooling device: direct and indirect of the wire, in the sense that the wire is subjected to the direct action of the coolant, on the one hand, and that the capstan is also internally cooled by this same liquid, thus participating in the cooling of the wire. The efficiency of the device is further enhanced by the action of compressed air which not only dries the wire, but also helps the propagation of the coolant along the turns and facilitates its evacuation.

If it is necessary to perfect the drying of the wire, the device is completed by a chamber in which air circulates and traversed by the wire before its introduction into the soap maker and the die of the downstream drawing block.

The device according to the invention is, ultimately, of a higher efficiency than that of known cooling devices of which it completely overcomes all the disadvantages. It can be used alone or in conjunction with the die cooling system which, in any case, is necessary for the protection of the die itself. The device is adaptable to any drawing machine of any design, single or multi-pass.

Claims (4)

1. A wire cooling device for a wire drawing machine comprising a wire traction capstan passing through a die, characterized in that it consists of a plurality of slots or grooves (6, 9) formed in the external wall of the capstan , supplied one (6) with coolant and used to bring this liquid into contact with the wire which is wound on the capstan and whose contiguous turns (4a) form a jacket external to the capstan in which the coolant circulates , the others (9) supplied with pressurized air intended for the recovery and evacuation of the coolant. 2. Device according to claim 1, characterized in that grooves or slots (14) supplied with pressurized air are formed in the external wall of the capstan above the grooves or slots (6) supplying the coolant to the turns of wire, so as to regulate the circulation of the cooling fluid between the turns of wire and the external wall of the capstan. 3. Device according to any one of the preceding claims, characterized in that the various slots or grooves (6, 9, 14) are supplied with fluids by orifices into which open out pipes supplied with fluids by at least one rotary joint. 4. Device according to any one of the preceding claims, characterized in that the slots or grooves (9) for taking up the cooling fluid are, at their upper part, connected to a source of pressurized air and, at their part lower, through orifices (13) to a coolant discharge pipe.

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