EP3137236A1 - A cooling system for a dry drawing capstan - Google Patents

A cooling system for a dry drawing capstan

Info

Publication number
EP3137236A1
EP3137236A1 EP15718161.1A EP15718161A EP3137236A1 EP 3137236 A1 EP3137236 A1 EP 3137236A1 EP 15718161 A EP15718161 A EP 15718161A EP 3137236 A1 EP3137236 A1 EP 3137236A1
Authority
EP
European Patent Office
Prior art keywords
capstan
cooling system
flaps
coolant
wall
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP15718161.1A
Other languages
German (de)
French (fr)
Other versions
EP3137236B1 (en
Inventor
Erwin Vereecken
Hendrik Van Hoecke
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Bekaert NV SA
Original Assignee
Bekaert NV SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Bekaert NV SA filed Critical Bekaert NV SA
Priority to PL15718161T priority Critical patent/PL3137236T3/en
Publication of EP3137236A1 publication Critical patent/EP3137236A1/en
Application granted granted Critical
Publication of EP3137236B1 publication Critical patent/EP3137236B1/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES, PROFILES OR LIKE SEMI-MANUFACTURED PRODUCTS OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C1/00—Manufacture of metal sheets, wire, rods, tubes or like semi-manufactured products by drawing
    • B21C1/02—Drawing metal wire or like flexible metallic material by drawing machines or apparatus in which the drawing action is effected by drums
    • B21C1/14—Drums, e.g. capstans; Connection of grippers thereto; Grippers specially adapted for drawing machines or apparatus of the drum type; Couplings specially adapted for these drums

Definitions

  • the invention relates to a cooling system adapted for use in a wire
  • drawing bench more particularly a dry drawing bench whereof the drawing capstans must be cooled during use.
  • the invention equally relates to a wire drawing bench provided with such cooling system and the
  • the invention relates to a method for cooling a dry drawing capstan.
  • metal wire drawing a metal wire e.g. made of steel, copper, aluminium or like metals, is pulled through successively smaller orifices made of hard metal drawing dies.
  • the drawing dies are mounted to a drawing bench in sturdy die holders to prevent the dies from moving with the wire.
  • the wire is pulled through the die by a drum, in the field known as 'a drawing capstan' or 'capstan' in short, around which a few turns of wire are wound in order to grip the wire. After the few turns, the wire leaves the capstan and is guided to the next drawing die and ultimately to the take-up spool.
  • the wire has to be lubricated in order to decrease the friction between the wire and the die during drawing.
  • a lubricant in the form of a powder or a gel one refers to 'dry drawing' as opposed to wet wire drawing wherein the dies, the capstans and the wire are submerged in a liquid lubricant.
  • the cooling is done from the inside of the capstan by spraying a coolant on the inner wall of the capstan and recovering the coolant in a sump below the capstan.
  • air cooling is many times used where air is blown on the wires at the sill of the capstan from a gap surrounding the capstan.
  • the sill of the capstan is a collar at the foot of the capstan that pushes the already present windings upward. At the sill the wire is hottest.
  • JP8281317A describing a drawing capstan wherein a stationary, inner cylinder is introduced having vanes at the top that directionally inject cooling water in the gap between the cylinder and the inside surface of the capstan.
  • EP0752287 describes a capstan with a fluid cooling unit, the latter comprising at least one circular sector that is located close to the internal lateral surface of the body and is connected to the fixed frame of the drawing bench. At least on nozzle proximate to the outer surface of the sector is present so as to form a jacket of cooling fluid that flows over the internal lateral surface of the body.
  • the circular sector is provided with helically oriented fins that agitate the cooling fluid on the internal lateral surface.
  • a relatively large service opening must be provided at the top of the capstan in order to mount and align the circular sectors.
  • US4050282 describes an inner cooling system wherein the inner insert has vertical, axially extending ribs dividing the gap between insert and capstan in a plurality of individual chambers.
  • the ribs are situated at freely tensioned arch or curved sections of the annular shaped inner insert.
  • the axially extending ribs end with a small play of less than 0.5 mm, preferably less than 0.2 mm in front of the inner surface of the capstan so that possible foreign material deposits are permanently carried off by the rotating drawing die drum.
  • One of the problems that aggravate the cooling capacity of a capstan is indeed the formation of a rust layer on the inside of the capstan. As the rust layer forms, the cooling capacity of the inner cooling system is reduced. This decrease in cooling capacity many times goes unnoticed as the coolant flow is kept constant.
  • narrow gap cooling (such as in the prior art 'A' and 'C') is that - as the coolant is dragged by the capstan and held stationary by the inner drum - the viscosity of the coolant leads to stirring losses occurring at high drawing speeds. This has a large impact on the power needed to drive the capstan.
  • the primary object of the invention is therefore to provide a cooling system for a wire drawing capstan of a dry drawing bench that ensures an efficient cooling at constant coolant supply with a low power use.
  • the inventors sought and found a cooling system that removes the internal rust formed in a controlled way and at the same time ensures an adequate cooling of the capstan while using less power.
  • the cooling system is simply mountable and allows some leeway when mounted. Also no fine tuning to the cooling system is needed once mounted inside the capstan. Therefore the cooling system can easily be retrofit on existing dry drawing machines with very little to no adaptations of the capstan.
  • Another object of the invention is to provide a drawing bench adapted with the improved cooling system. Also a method is provided to cool a capstan of a dry drawing bench.
  • a cooling system for a capstan of a wire drawing bench is presented.
  • the capstan is mounted rotatable to the drawing bench.
  • the capstan has an inner wall with a surface of revolution over at least part of the axial length of the wire drawing capstan.
  • the cooling system is to be mounted stationary to the wire drawing bench inside of said capstan.
  • the cooling system specifically comprises a carrier and a number of
  • deflectable flaps With a 'deflectable flap' is meant a sheet of material that at one of its edges, sides or ends is mounted to the carrier: the 'carrier edge'.
  • the other, opposite edge, side or end of the deflectable flap is pressable, i.e. has the ability to be pressed, against the surface of the inner wall of the capstan in which the cooling system is to be mounted and will be called the 'pressed edge'.
  • the mounting of the deflectable flaps is such that, during use, the flaps are deflected in the direction of rotation of the capstan. The deflection breaks the direct contact between the pressed edge and the inner wall of the capstan. When the rotation of the capstan is stopped the pressed edge contacts the inner wall of the capstan.
  • the flaps when mounted, form an acute wedge angle with the surface of the inner wall.
  • the wedge angle is the angle between the deflectable flap and the surface of the inner wall in the plane perpendicular to the contact line.
  • the contact line is that line where the pressed edge and the inner wall meet at standstill.
  • the wedge angle is acute along the contact line.
  • the contact line is preferably uninterrupted i.e. at standstill the pressed edge contacts the inner wall of the capstan over the complete length of the flap. No substantial gaps are present between the pressed edge and the inner wall.
  • the inner wall that is contactable with the one or more flaps has a surface that is a surface of revolution over at least a part of the axial length of the capstan. Outside that part the surface does not need to be a surface of revolution for example there where spokes are present to mount the capstan to the drive axis.
  • a 'surface of revolution' is a surface formed by rotating a plane curve around an axis in the plane.
  • the axis of revolution of that surface substantially coincides with the axis of rotation of the capstan.
  • the curve can be any plane curve, it is preferably a simple, smooth curve such as a substantially straight line.
  • the surface of revolution is then conical, or when the line is parallel to the axis of rotation, a cylinder.
  • the surface of the inner wall is smooth i.e. there are no circumferential grooves or ridges present as is sometime customary (see e.g. EP 0752287).
  • the carrier on which the deflectable flaps are mounted can be a flange with uprights to which one edge of the flap is mounted.
  • the carrier can be the bushing wherein the drive axle of the capstan turns.
  • the coolant can be any fluid suitable for the purpose.
  • it can be a gas such as forced air.
  • a separate coolant supply means may not be necessary and in theory the capstan could be cooled by the air present inside the capstan.
  • water as coolant possibly including detergents to prevent foam building or corrosion formation -will be preferred as it is cheap and readily available but also has a good cooling capacity.
  • cooling system also has
  • the coolant supplies are directed and can spray the coolant on the surface of the inner wall, or solely on the flaps or towards both.
  • the coolant supplies are oriented to inject coolant into the acute wedge angle between the deflectable flap and the inner wall.
  • the number of coolant supplies may be different from the number of flaps, for example two supplies per flap.
  • the coolant supplies may be provided on the internal non-rotating part of the drawing bench such as for example the bushing of the drive axle or may be attached to the carrier which is more preferred as then the direction of the spraying can be set on the carrier together with the mounting of the flaps. More preferred is that each flap has its own associated coolant supply that is possibly situated in the upper half of the flap.
  • deflectable flaps to the surface of the inner wall is such that:
  • 'contact line pressure' is meant the total force by which the flap is pushed against the inner wall divided by the length of the contact line.
  • the working of the cooling device is based on the transition from a
  • boundary lubrication regime to a hydrodynamic lubrication: At low speeds (and/or at high contact line pressures), the microaspe ties of the contacting surfaces are rubbing, scraping one another as the thickness of the coolant film is smaller than the maximum roughness of either the surface of the inner wall or the pressed edge.
  • This is the boundary lubrication regime and it is characterised by a high coefficient of friction, i.e. a high energy loss, and increased wear of the contacting surfaces.
  • this regime is generally abhorred, in this case it is favoured at least for a controlled period of time i.e. during ramp up to regime speed and ramp down to full stop. During those short periods the pressed edges of the flaps will scrape the surface of the inner wall and thereby remove any foreign material such as for example rust or other deposits that may have formed and inhibit the cooling of the capstan.
  • the lubrication regime goes through a transition from boundary lubrication to hydrodynamic lubrication.
  • the transition between the different regimes is generally described by a Stribeck curve wherein the friction between flaps and inner wall is plotted as a function of the dimensionless bearing characteristic number that is equal to (the viscosity of the coolant ⁇ velocity / contact line pressure).
  • the viscosity of the coolant and the contact line pressure are such that the transition from boundary lubrication to hydrodynamic regime best occurs between 200 and 600 m/min.
  • a further important design parameter is the acute wedge angle.
  • this wedge angle is within the range 0° - zero included - and smaller than 45° over the length of the contact line.
  • the tribology involved is similar to the one of a slipper bearing where it is known that the maximum pressure exerted by the fluid on the flap increases inversely with the wedge angle leading to high forces on the flap at low angles i.e. the flap is very easily lifted when the wedge angle is small. Low or zero angles are obtained when the curve followed by the inside of the flap tangents to the surface of revolution of the inner wall at the pressed edge of the flap (zero and first derivative of flap curve and surface are equal at the edge).
  • the 'inside of the flap' is the side towards the acute wedge angle.
  • the number of flaps is between one and twenty four. At sufficiently high speeds one flap may suffice as the coolant not only is distributed by the action of the flap but is also held against the inner wall by the centrifugal forces due to the rotation of the capstan.
  • the flaps are rigid and cannot easily be bent. They are mounted at the carrier edge with a hinge to the carrier in order to make the flap deflectable. To make the flap pressable against the inner wall of the capstan, a spring is mounted between the carrier and the flap.
  • a spring can be a blade spring or a helical spring or can be made of any other resilient material such as a rubber spring or an air-spring.
  • the hinge and spring can be combined in a single flexing strip of material for example a spring steel strip.
  • the steel of such strip has a high yield stress in order to resist deformation and easily return to its original shape.
  • the flap itself is flexible but the carrier edge is rigidly mounted to the carrier.
  • the flap then generates the pressure against the inner wall due to its bending.
  • the flap may be made of a suitable, flexible material such as metal.
  • Preferred metals are for example stainless steel, or spring steel, aluminium (Duralumin) or copper alloys. A high yield point of the metal is preferred for resilience.
  • Alternative materials such as high performance plastic like polyamide, polyurethane or even vulcanised rubber can be considered.
  • the contact line pressure exerted by the flap on the surface of the inner wall is by preference between 10 and 1000 N/m, or between 15 and 500 N/m or even between 20 and 200 N/m. These ranges go together with the wedge angle. For example with a small wedge angle a high contact line pressure can be used, while with a larger wedge angle, a lower contact line pressure must be applied in order to allow the flap to skid on the coolant.
  • the flaps are provided with a landing zone at the pressed edge i.e. the edge that is pressable against the inner wall of said capstan.
  • the landing zone is that zone at the pressed edge of the flap that makes contact with the inner surface of the stationary capstan, not only over a line, but over a certain width. I.e. the landing zone follows the shape of the surface. This landing zone may form during prolonged use as the scraping of the flap with the surface of the inner wall will gradually form the edge of the flap in the shape of the surface of the inner wall. Alternatively, the landing zone may be provided at the edge of the flap ab initio.
  • the landing zone can be provided in the form of a replaceable wear part for example of metal or plastic that can be clipped, slid or fastened to the end of the flap.
  • this landing zone may be provided with a wear resistant and/or abrasive coating.
  • a wear resistant and/or abrasive coating may for example comprise abrasive and/or wear resistant particles such as quartz, silicon carbide, cubic boron nitride or tungsten carbide and the coating maybe applied by means of painting, or cladding, such as laser cladding.
  • the abrasive and/or wear resistant particles can be incorporated into the replaceable wear part.
  • the function of the coating or wear part is on the one hand to ensure that the surface of the inner wall is properly cleaned and scraped and on the other hand to prevent too fast abrasion of the flap edge.
  • the surface roughness of the wear part or coating also helps to agitate the coolant film and to improve the cooling of the system.
  • the flaps are mounted substantially parallel with the axis of rotation of the capstan. More specifically: the contact line is substantially in a plane comprising the axis of rotation of the capstan.
  • the flaps can be inclined with respect to the axis of rotation of the capstan. I.e. the line where said flap and said surface meet is substantially in a plane making an inclined angle to the axis of rotation of the capstan.
  • the inclination is such that during rotation of the capstan the coolant is driven upward, opposite to the direction of gravitation. In this way the downward flow of the fluid is somewhat countered, and a more even coolant distribution on the inner wall can be obtained.
  • This inclination angle may be between 1 ° up to even 60° more preferably between 1 ° and 20° or between 5° and 15.
  • Particularly preferred embodiments are when the surface of revolution of the inner wall is a frusto conus or a cylinder.
  • the contact line will be a straight line inclined to the capstan axis (conus) or will be a straight line parallel to the capstan axis (cylinder).
  • the contact line will be part of an ellipse irrespective whether the surface of revolution is a frusto cone or a cylinder.
  • a frusto cone is a cone where the top above a plane making an angle to the axis of the cone has been removed.
  • the combination of a cooling system and a capstan is provided.
  • the cooling system is the cooling system as described according the first aspect of the invention.
  • the capstan is adapted to co-work with the cooling system in that the radius and surface of revolution of the inner wall of the capstan results in the correct contact line pressure and wedge angle as described before.
  • the outer diameter of a capstan is generally between 200 mm to 1200 mm, but mostly between 380 mm to 620 mm.
  • the capstan can easily be mounted on the cooling system as the flaps can be made to deflect radially inwardly as the capstan is lowered over the already mounted cooling system.
  • One single cooling system can be used within a range of capstan diameters as long as the conditions for wedge angle and contact line pressure are met.
  • the mounting of the cooling system does not require high concentricity requirements as the flaps will adjust their inclination position once the coolant film has formed. Some eccentricity may even add to the agitation of the coolant. This is a big advantage compared to prior art systems that had to be mounted very precisely and needed post adjustment after mounting.
  • the inventive cooling system can therefore be easily retrofit to existing installations provided the inner wall of the capstan has a smooth surface of revolution. No fine tuning is needed to the cooling system once it is mounted inside the capstan.
  • the inner wall of the capstan has a recessed surface of revolution wherein the flaps of the cooling system run. Such a recessed surface helps to keep the coolant where it is needed: that circumferential region where the hot wire contacts the capstan.
  • a wire drawing bench comprising at least one cooling system according any of the above described is claimed. Furthermore, a wire drawing bench with at least one specified combination of capstan and cooling system is also claimed. Subsequent capstans on a wire drawing bench run at progressively higher
  • the cooling system and capstan combination are particularly energy saving at higher run speeds, the combination can be advantageously used for the capstans running at those higher speeds.
  • a method to cool the capstan of a wire drawing bench comprises the following steps: • Providing a wire drawing bench having one or more rotatable capstans mounted thereon;
  • At least one of the capstans has an inner wall that is a surface of revolution over at least a part of the axial length of the capstan;
  • the flaps are deflected in the direction of intended rotation of the capstan, thereby forming a wedge angle between the flap and the surface of revolution at the other edge.
  • the wedge angle is an acute angle.
  • the supply of coolant can be left on during the ramp up and ramp down of the capstan, such that the flaps scrape the surface of the inner wall in the presence of coolant.
  • Figure 1 describes a capstan of a wire drawing bench with a prior art
  • Figure 2a describes a first embodiment of the cooling system and capstan in a wire drawing bench according the invention in a cross section comprising the axis of rotation of the capstan.
  • Figure 2b shows a cross section in plane ⁇ - ⁇ of Figure 2a of the first
  • Figure 3a shows a cross section in a plane perpendicular to the axis of rotation of the capstan of a second embodiment of the invention
  • Figure 3b is an enlargement of part of the cooling system of the second embodiment.
  • Figure 4 is a cross section perpendicular to the axis of rotation of the
  • capstan of the cooling system according a third embodiment of the invention.
  • Figure 5 is a side view of a fourth embodiment of the inventive cooling system and the associated capstan.
  • a reference key list is provided at the end of the description.
  • FIG. 1 Indicated with 100 in Figure 1 is a capstan of a wire drawing bench with a prior art cooling system.
  • bench 1 14 different capstans are mounted in a row, with drawing die holders (not shown) in between.
  • the capstan 102 is secured to an axle 120 by means of a fixing bolt 124.
  • the axle 120 is rotatably mounted on bearing 126 on top of the axle bushing 122.
  • the axle 120 is driven by a motor (not shown) at the speed required by the drawing process.
  • Inside of the capstan a cylindrical internal coolant retaining wall 107 is mounted thereby leaving a small gap between retaining wall 107 and capstan 102. Coolant is supplied through coolant feed 1 10 in the direction indicated by the flow arrows 1 16 into this gap.
  • a coolant seal 105 is present at the bottom of the capstan to prevent the coolant from leaking out of the gap.
  • the coolant after flowing over the internal coolant retaining wall, is collected at the bottom of the drawing capstan and extracted through coolant extraction tube 1 12.
  • the entering hot wire 106 pushes the already present loops of wire up by the action of the sill 108. After having made some loops the cooled wire 106' leaves the capstan to enter the next drawing die or to be wound on a spool.
  • FIG 2b shows a cross section of the cooling system and capstan along plane indicated ⁇ - ⁇ in Figure 2a.
  • hot wire 206 enters the capstan at the sill 208 and is pushed upward until it at 206' leaves the capstan 202 in a cold state.
  • the capstan 202 is fixed by fixing bolt 224 on an axle 220 that is rotatably mounted in an axle bushing 222 through bearing 226 on a bench 214.
  • the cooling system that is based on a carrier ring 223 whereon posts or uprights - three in this case - 213 are fixed. To the each of the posts 213 a flap 204 is mounted.
  • the coolant is distributed to three coolant feed tubes 218 that spray coolant on the inner wall of the capstan 202 through nozzle 21 1 .
  • the inner wall of the capstan 202 has a surface of revolution 203 at least over an axial length 'L' where contact is made to the flaps 204.
  • the edge of the flap 204' contacting the surface is indicated by line 'A' in Figure 2a. Note that in this embodiment the line 'A' is in a plane comprising the rotation axis of the capstan.
  • the coolant is caught in a sump 217 that is mounted to the bench 214 and drained through the coolant extraction 212. As no sealing ring is needed anymore, there is no power loss due to friction of such seal.
  • each flap 204 is made of a flexible material that is rigidly connected to the carrier at their post 213.
  • the flaps are for example made of stainless steel sheet of 0.8 to 1 .0 mm thick.
  • An alternative material is aluminium sheet of 1 .5 mm .
  • the flaps are deflected, at least during use, in the rotation direction 219 of the capstan.
  • the angle that forms at the other edge of the flap where the flap meets the surface of revolution of the internal wall is the wedge angle 'a' which is in this case about 15°.
  • the total force by which the flap presses against the inner wall of the capstan 202 is between 20 to 30 newton over a length of 20 cm.
  • This combination of contact line pressure and wedge angle makes the flap skid on water coolant from a speed of about 100 m/min onward. Below that speed the water coolant film breaks and the edge 'A' of the flap scrapes the inner wall of the capstan, thereby removing and cleaning any deposits - such as rust - that may have formed. In addition to that the flaps help to reduce the speed of the capstan, i.e. act as an additional brake.
  • FIG. 3a and the enlargement Figure 3b show a second embodiment of the invention.
  • the cooling system consists of a carrier made of a ring 323 on which uprights 313, 313', 313" are fixed.
  • the flaps 304, 304' and 304" are rigid. They can be made of grey cast steel of 3 mm thick. Grey cast iron resists abrasion well and acts as a grinding stone to better clean the surface of the inner wall. To make them
  • each flap is connected to the upright 313 with a hinge 309 at the carrier edge of the flap.
  • a steel blade spring 315, 315" is mounted between the upright 313, 313', 313" and the associated flap.
  • the coolant nozzles 31 1 are mounted midways the flaps and spray coolant directly on the inner wall of the capstan.
  • FIG. 3b shows what happens when the capstan 302 is turning and coolant is fed. Under the action of the spring 315", the flap 304" is pushed against the inner wall surface 303 of the capstan, thereby forming the wedge angle 'a'. During rotation at normal operating speed, in direction 319, the wedge angle together with the pressure on the flap results in skidding of the flap on the coolant and a coolant film 327 forms. When the capstan slows down - or alternatively during ramp up - the film 327 does not form and the edge of the flap is running against the inner wall of the capstan at the landing zone 325. The landing zone 325 will closely follow the rounding of the capstan due to the wear at the edge.
  • FIG. 4 shows a third embodiment of the cooling system 401 .
  • the carrier is a steel tube 413 of thickness 2.5 mm out of which the six flaps 404, 404', 404", 404"', 404"", 404 are laser cut and then plastically bend to a circumscribed circle larger than the inner diameter of the capstan.
  • the tube is mounted to ring 423. After insertion into the capstan, the flaps will take the shape as indicated.
  • Each of the flaps has a landing zone 425 that is tangential to the inner surface of the capstan. The wedge angle is therefore close to 0°.
  • the landing zone ends in Vulkollan® a high performance elastomer of Bayer. Alternatively, the end is coated with an abrasive and wear resistant layer of bronze.
  • Each flap is fed with coolant distributed from coolant feed 410 by tubes 418 ending in individual nozzles 41 1 for each of the flaps. The nozzles spray coolant between the inner surface of the capstan and the flap. As the wedge angle is so small, the flaps will skid already at very low speeds onward (from about 20 m/min ) thereby reducing the friction to the inner wall. In order to remove deposits from the inner wall it is therefore necessary to start and stop the machine dry - i.e. without supply of coolant - in order to remove the deposit.
  • Figure 5 shows a further embodiment of the invention according the
  • the line 'A' where the flap 504 and the inner surface of revolution 503 of the capstan 502 meet is in a plane making an inclined angle ' ⁇ ' to the axis of rotation of the capstan.
  • the inclined angle is such that coolant fed from nozzle 51 1 is driven upward, against the action of gravitation when the capstan is turning in direction 519.
  • the flexible flap 504 is rigidly mounted to post 513 that on its turn is mounted to ring 523.
  • the surface of revolution 503 is recessed in the inner wall of the capstan 502 over the axial length 'L'. This in order to retain the coolant better there where it is needed.
  • the hundred number refers to the related figure 'x'.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metal Extraction Processes (AREA)
  • Heat Treatment Of Strip Materials And Filament Materials (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

The capstan (202) cooling system is based on deflectable flaps (204) that are pressable against the inner surface of the capstan. The cooling system has the advantage that the flaps (204) skid on the coolant film at the operational speed and scrape the inner surface of the capstan (202) at start or stop speeds. In this way the inner surface of the capstan is cleaned from rust and other debris. At the operational speed, as the flaps skid on the coolant, there is very little loss in power due to friction.

Description

Title: A cooling system for a dry drawing capstan.
Description
Technical Field
[0001 ] The invention relates to a cooling system adapted for use in a wire
drawing bench, more particularly a dry drawing bench whereof the drawing capstans must be cooled during use. The invention equally relates to a wire drawing bench provided with such cooling system and the
combination of the cooling system and a capstan adapted for use with said cooling system. Further, the invention relates to a method for cooling a dry drawing capstan.
Background Art
[0002] In metal wire drawing, a metal wire e.g. made of steel, copper, aluminium or like metals, is pulled through successively smaller orifices made of hard metal drawing dies. The drawing dies are mounted to a drawing bench in sturdy die holders to prevent the dies from moving with the wire. The wire is pulled through the die by a drum, in the field known as 'a drawing capstan' or 'capstan' in short, around which a few turns of wire are wound in order to grip the wire. After the few turns, the wire leaves the capstan and is guided to the next drawing die and ultimately to the take-up spool. Of course the wire has to be lubricated in order to decrease the friction between the wire and the die during drawing. When the lubrication is by means of a lubricant in the form of a powder or a gel one refers to 'dry drawing' as opposed to wet wire drawing wherein the dies, the capstans and the wire are submerged in a liquid lubricant.
[0003] At each drawing die, the wire is plastically deformed thereby generating a large amount of heat. While in wet wire drawing this heat is easily transferred to the liquid lubricant, in dry drawing this is not possible.
Therefore in dry drawing the die holder is cooled. To some degree cooling of the wire can be increased by increasing the number of turns around the capstan, but this only reduces the wire exit temperature and does not improve the cooling of the entering windings. Hence, the capstan receiving the hot wire must be cooled too. Not or insufficient cooling results in inferior wire quality. The cooling of capstans is therefore a known problem in the design of dry drawing benches.
Usually the cooling is done from the inside of the capstan by spraying a coolant on the inner wall of the capstan and recovering the coolant in a sump below the capstan. Alternatively and additionally, air cooling is many times used where air is blown on the wires at the sill of the capstan from a gap surrounding the capstan. The sill of the capstan is a collar at the foot of the capstan that pushes the already present windings upward. At the sill the wire is hottest.
Some alternate solutions and improvements that have been documented are:
A. JP8281317A describing a drawing capstan wherein a stationary, inner cylinder is introduced having vanes at the top that directionally inject cooling water in the gap between the cylinder and the inside surface of the capstan.
B. EP0752287 describes a capstan with a fluid cooling unit, the latter comprising at least one circular sector that is located close to the internal lateral surface of the body and is connected to the fixed frame of the drawing bench. At least on nozzle proximate to the outer surface of the sector is present so as to form a jacket of cooling fluid that flows over the internal lateral surface of the body. The circular sector is provided with helically oriented fins that agitate the cooling fluid on the internal lateral surface. A relatively large service opening must be provided at the top of the capstan in order to mount and align the circular sectors.
C. US4050282 describes an inner cooling system wherein the inner insert has vertical, axially extending ribs dividing the gap between insert and capstan in a plurality of individual chambers. The ribs are situated at freely tensioned arch or curved sections of the annular shaped inner insert. The axially extending ribs end with a small play of less than 0.5 mm, preferably less than 0.2 mm in front of the inner surface of the capstan so that possible foreign material deposits are permanently carried off by the rotating drawing die drum. [0006] One of the problems that aggravate the cooling capacity of a capstan is indeed the formation of a rust layer on the inside of the capstan. As the rust layer forms, the cooling capacity of the inner cooling system is reduced. This decrease in cooling capacity many times goes unnoticed as the coolant flow is kept constant.
[0007] Another problem that occurs with cooling systems that are based on
narrow gap cooling (such as in the prior art 'A' and 'C') is that - as the coolant is dragged by the capstan and held stationary by the inner drum - the viscosity of the coolant leads to stirring losses occurring at high drawing speeds. This has a large impact on the power needed to drive the capstan.
Disclosure of Invention
[0008] The primary object of the invention is therefore to provide a cooling system for a wire drawing capstan of a dry drawing bench that ensures an efficient cooling at constant coolant supply with a low power use. The inventors sought and found a cooling system that removes the internal rust formed in a controlled way and at the same time ensures an adequate cooling of the capstan while using less power. Furthermore the cooling system is simply mountable and allows some leeway when mounted. Also no fine tuning to the cooling system is needed once mounted inside the capstan. Therefore the cooling system can easily be retrofit on existing dry drawing machines with very little to no adaptations of the capstan. Another object of the invention is to provide a drawing bench adapted with the improved cooling system. Also a method is provided to cool a capstan of a dry drawing bench.
[0009] According a first aspect of the invention a cooling system for a capstan of a wire drawing bench is presented. The capstan is mounted rotatable to the drawing bench. The capstan has an inner wall with a surface of revolution over at least part of the axial length of the wire drawing capstan. The cooling system is to be mounted stationary to the wire drawing bench inside of said capstan.
[0010] The cooling system specifically comprises a carrier and a number of
deflectable flaps. With a 'deflectable flap' is meant a sheet of material that at one of its edges, sides or ends is mounted to the carrier: the 'carrier edge'. The other, opposite edge, side or end of the deflectable flap is pressable, i.e. has the ability to be pressed, against the surface of the inner wall of the capstan in which the cooling system is to be mounted and will be called the 'pressed edge'. The mounting of the deflectable flaps is such that, during use, the flaps are deflected in the direction of rotation of the capstan. The deflection breaks the direct contact between the pressed edge and the inner wall of the capstan. When the rotation of the capstan is stopped the pressed edge contacts the inner wall of the capstan.
[001 1 ] Preferably, when mounted, the flaps form an acute wedge angle with the surface of the inner wall. The wedge angle is the angle between the deflectable flap and the surface of the inner wall in the plane perpendicular to the contact line. The contact line is that line where the pressed edge and the inner wall meet at standstill. The wedge angle is acute along the contact line. The contact line is preferably uninterrupted i.e. at standstill the pressed edge contacts the inner wall of the capstan over the complete length of the flap. No substantial gaps are present between the pressed edge and the inner wall.
[0012] The inner wall that is contactable with the one or more flaps has a surface that is a surface of revolution over at least a part of the axial length of the capstan. Outside that part the surface does not need to be a surface of revolution for example there where spokes are present to mount the capstan to the drive axis. A 'surface of revolution' is a surface formed by rotating a plane curve around an axis in the plane. Here, the axis of revolution of that surface substantially coincides with the axis of rotation of the capstan. Although the curve can be any plane curve, it is preferably a simple, smooth curve such as a substantially straight line. The surface of revolution is then conical, or when the line is parallel to the axis of rotation, a cylinder. Preferably the surface of the inner wall is smooth i.e. there are no circumferential grooves or ridges present as is sometime customary (see e.g. EP 0752287).
[0013] The carrier on which the deflectable flaps are mounted can be a flange with uprights to which one edge of the flap is mounted. Alternatively, the carrier can be the bushing wherein the drive axle of the capstan turns. [0014] The coolant can be any fluid suitable for the purpose. For example it can be a gas such as forced air. In that case a separate coolant supply means may not be necessary and in theory the capstan could be cooled by the air present inside the capstan. Of course mostly water as coolant - possibly including detergents to prevent foam building or corrosion formation -will be preferred as it is cheap and readily available but also has a good cooling capacity.
[0015] Therefore in another preferred embodiment the cooling system also
includes one or more coolant supplies for feeding coolant. The coolant supplies are directed and can spray the coolant on the surface of the inner wall, or solely on the flaps or towards both. Preferably the coolant supplies are oriented to inject coolant into the acute wedge angle between the deflectable flap and the inner wall. The number of coolant supplies may be different from the number of flaps, for example two supplies per flap. The coolant supplies may be provided on the internal non-rotating part of the drawing bench such as for example the bushing of the drive axle or may be attached to the carrier which is more preferred as then the direction of the spraying can be set on the carrier together with the mounting of the flaps. More preferred is that each flap has its own associated coolant supply that is possibly situated in the upper half of the flap.
[0016] In a further preferred embodiment, the contact line pressure of the
deflectable flaps to the surface of the inner wall is such that:
• at the operational speed of the capstan - i.e. during the stationary working regime of the wire drawing bench - a coolant film forms between the flap and the surface i.e. the flap is hydrodynamically skidding on the coolant film and,
• at ramp up - i.e. when the capstan starts to rotate - or ramp down - i.e. when the capstan slows down till full stop - the flaps scrape the surface of the inner wall.
For the purpose of this application with 'contact line pressure' is meant the total force by which the flap is pushed against the inner wall divided by the length of the contact line.
[0017] The working of the cooling device is based on the transition from a
boundary lubrication regime to a hydrodynamic lubrication: At low speeds (and/or at high contact line pressures), the microaspe ties of the contacting surfaces are rubbing, scraping one another as the thickness of the coolant film is smaller than the maximum roughness of either the surface of the inner wall or the pressed edge. This is the boundary lubrication regime and it is characterised by a high coefficient of friction, i.e. a high energy loss, and increased wear of the contacting surfaces. Although this regime is generally abhorred, in this case it is favoured at least for a controlled period of time i.e. during ramp up to regime speed and ramp down to full stop. During those short periods the pressed edges of the flaps will scrape the surface of the inner wall and thereby remove any foreign material such as for example rust or other deposits that may have formed and inhibit the cooling of the capstan.
[0018] When the relative speed between flap and inner wall is gradually
increased, the lubrication regime goes through a transition from boundary lubrication to hydrodynamic lubrication.
[0019] At high speeds and/or at low contact line pressures, the pressed edge of the flap skids over the coolant and a coolant film forms against the surface of the inner wall. The thickness of the film formed is now much larger than the total roughness of both contacting surfaces of flap and inner wall. As the physical contact between these surfaces is broken, the friction between flap and inner wall is greatly diminished leading to a lower power use. Furthermore, as the water film is no longer in contact with the inner wall, stirring losses are greatly diminished and only occur when the coolant hits the flap.
[0020] The transition between the different regimes is generally described by a Stribeck curve wherein the friction between flaps and inner wall is plotted as a function of the dimensionless bearing characteristic number that is equal to (the viscosity of the coolant χ velocity / contact line pressure). For the purpose of this application, the viscosity of the coolant and the contact line pressure are such that the transition from boundary lubrication to hydrodynamic regime best occurs between 200 and 600 m/min.
[0021 ] A further important design parameter is the acute wedge angle. Preferably this wedge angle is within the range 0° - zero included - and smaller than 45° over the length of the contact line. The tribology involved is similar to the one of a slipper bearing where it is known that the maximum pressure exerted by the fluid on the flap increases inversely with the wedge angle leading to high forces on the flap at low angles i.e. the flap is very easily lifted when the wedge angle is small. Low or zero angles are obtained when the curve followed by the inside of the flap tangents to the surface of revolution of the inner wall at the pressed edge of the flap (zero and first derivative of flap curve and surface are equal at the edge). The 'inside of the flap' is the side towards the acute wedge angle. So if the angle is made sufficiently low, the flap will always lift from the surface even at moderate speeds and even at high contact line pressure. Hence, too small angles may result in insufficient scraping of the inner wall at start or stop. Therefore acute wedge angles from 1 ° to 30° or 5° to 20° or even 5° to 15°are a good choice. The acute wedge angle may vary within those ranges over the length of the contact line.
[0022] In a further preferred embodiment, the number of flaps is between one and twenty four. At sufficiently high speeds one flap may suffice as the coolant not only is distributed by the action of the flap but is also held against the inner wall by the centrifugal forces due to the rotation of the capstan.
These can easily attain 10 to 20 g ('g' being the gravitational acceleration). In order to obtain sufficient spreading of the coolant film one could consider the use of many flaps such as up to 24. Each additional flap adds to the disturbance of the coolant film thereby agitating the coolant and increasing the cooling capacity of the system. However, each flap will contribute to the drag of the coolant and therefore will increase power usage. Also more flaps add to the cost of the system. So between 2 and 6 flaps is an optimal value.
[0023] The inventors envisage two preferred designs for the flaps.
In a preferred embodiment, the flaps are rigid and cannot easily be bent. They are mounted at the carrier edge with a hinge to the carrier in order to make the flap deflectable. To make the flap pressable against the inner wall of the capstan, a spring is mounted between the carrier and the flap. Such a spring can be a blade spring or a helical spring or can be made of any other resilient material such as a rubber spring or an air-spring.
Possibly the hinge and spring can be combined in a single flexing strip of material for example a spring steel strip. The steel of such strip has a high yield stress in order to resist deformation and easily return to its original shape.
[0024] In an alternative preferred embodiment the flap itself is flexible but the carrier edge is rigidly mounted to the carrier. The flap then generates the pressure against the inner wall due to its bending. The flap may be made of a suitable, flexible material such as metal. Preferred metals are for example stainless steel, or spring steel, aluminium (Duralumin) or copper alloys. A high yield point of the metal is preferred for resilience. Alternative materials such as high performance plastic like polyamide, polyurethane or even vulcanised rubber can be considered.
[0025] The contact line pressure exerted by the flap on the surface of the inner wall is by preference between 10 and 1000 N/m, or between 15 and 500 N/m or even between 20 and 200 N/m. These ranges go together with the wedge angle. For example with a small wedge angle a high contact line pressure can be used, while with a larger wedge angle, a lower contact line pressure must be applied in order to allow the flap to skid on the coolant.
[0026] In a further preferred embodiment, the flaps are provided with a landing zone at the pressed edge i.e. the edge that is pressable against the inner wall of said capstan. The landing zone is that zone at the pressed edge of the flap that makes contact with the inner surface of the stationary capstan, not only over a line, but over a certain width. I.e. the landing zone follows the shape of the surface. This landing zone may form during prolonged use as the scraping of the flap with the surface of the inner wall will gradually form the edge of the flap in the shape of the surface of the inner wall. Alternatively, the landing zone may be provided at the edge of the flap ab initio. The landing zone can be provided in the form of a replaceable wear part for example of metal or plastic that can be clipped, slid or fastened to the end of the flap.
[0027] In a preferred embodiment this landing zone may be provided with a wear resistant and/or abrasive coating. Such coating may for example comprise abrasive and/or wear resistant particles such as quartz, silicon carbide, cubic boron nitride or tungsten carbide and the coating maybe applied by means of painting, or cladding, such as laser cladding. Alternatively, the abrasive and/or wear resistant particles can be incorporated into the replaceable wear part. The function of the coating or wear part is on the one hand to ensure that the surface of the inner wall is properly cleaned and scraped and on the other hand to prevent too fast abrasion of the flap edge. The surface roughness of the wear part or coating also helps to agitate the coolant film and to improve the cooling of the system.
[0028] In a further embodiment the flaps are mounted substantially parallel with the axis of rotation of the capstan. More specifically: the contact line is substantially in a plane comprising the axis of rotation of the capstan.
[0029] Alternatively, the flaps can be inclined with respect to the axis of rotation of the capstan. I.e. the line where said flap and said surface meet is substantially in a plane making an inclined angle to the axis of rotation of the capstan. Advantageously the inclination is such that during rotation of the capstan the coolant is driven upward, opposite to the direction of gravitation. In this way the downward flow of the fluid is somewhat countered, and a more even coolant distribution on the inner wall can be obtained. This inclination angle may be between 1 ° up to even 60° more preferably between 1 ° and 20° or between 5° and 15.
[0030] Particularly preferred embodiments are when the surface of revolution of the inner wall is a frusto conus or a cylinder. When the flap is in the plane comprising the axis of the capstan, the contact line will be a straight line inclined to the capstan axis (conus) or will be a straight line parallel to the capstan axis (cylinder). In case the flaps are inclined with respect to axis of the capstan, the contact line will be part of an ellipse irrespective whether the surface of revolution is a frusto cone or a cylinder. A frusto cone is a cone where the top above a plane making an angle to the axis of the cone has been removed.
[0031 ] According a second aspect of the invention, the combination of a cooling system and a capstan is provided. The cooling system is the cooling system as described according the first aspect of the invention. The capstan is adapted to co-work with the cooling system in that the radius and surface of revolution of the inner wall of the capstan results in the correct contact line pressure and wedge angle as described before. To put things in perspective: the outer diameter of a capstan is generally between 200 mm to 1200 mm, but mostly between 380 mm to 620 mm.
[0032] The capstan can easily be mounted on the cooling system as the flaps can be made to deflect radially inwardly as the capstan is lowered over the already mounted cooling system. One single cooling system can be used within a range of capstan diameters as long as the conditions for wedge angle and contact line pressure are met. Also the mounting of the cooling system does not require high concentricity requirements as the flaps will adjust their inclination position once the coolant film has formed. Some eccentricity may even add to the agitation of the coolant. This is a big advantage compared to prior art systems that had to be mounted very precisely and needed post adjustment after mounting. The inventive cooling system can therefore be easily retrofit to existing installations provided the inner wall of the capstan has a smooth surface of revolution. No fine tuning is needed to the cooling system once it is mounted inside the capstan.
[0033] In a further preferred embodiment, of this combination, the inner wall of the capstan has a recessed surface of revolution wherein the flaps of the cooling system run. Such a recessed surface helps to keep the coolant where it is needed: that circumferential region where the hot wire contacts the capstan.
[0034] According a third aspect of the invention a wire drawing bench comprising at least one cooling system according any of the above described is claimed. Furthermore, a wire drawing bench with at least one specified combination of capstan and cooling system is also claimed. Subsequent capstans on a wire drawing bench run at progressively higher
circumferential speeds as the wire diameter is reduced. As the cooling system and capstan combination is particularly energy saving at higher run speeds, the combination can be advantageously used for the capstans running at those higher speeds.
[0035] According a fourth aspect of the invention a method to cool the capstan of a wire drawing bench is described. The method comprises the following steps: • Providing a wire drawing bench having one or more rotatable capstans mounted thereon;
• At least one of the capstans has an inner wall that is a surface of revolution over at least a part of the axial length of the capstan;
• Providing one or more flaps at the inside of the at least one capstan whereby the flaps are deflectable and
whereby the flaps are at one of their edges mounted to a stationary part inside of said capstan, and
whereby the flaps at their other edge are pressable against the surface of revolution of the inner wall of the capstan;
Characterised in that,
during use, the flaps are deflected in the direction of intended rotation of the capstan, thereby forming a wedge angle between the flap and the surface of revolution at the other edge. The wedge angle is an acute angle.
[0036] Another advantageous manner of implementing the method further
comprises the step of:
• Supplying coolant to the flaps and/or the surface such that a coolant film forms between the flaps and the surface at the operational speed of the capstan.
The supply of coolant can be left on during the ramp up and ramp down of the capstan, such that the flaps scrape the surface of the inner wall in the presence of coolant.
[0037] In an additional embodiment of the method the following step is added:
• Switching off the supply of coolant during ramp up or ramp down of the capstan, whereby the flaps scrape the surface of the inner wall.
[0038] The additional features of the embodiments according the first, second and third aspect of the invention, can likewise be implemented into the inventive method. Brief Description of Figures in the Drawings
[0039] Figure 1 describes a capstan of a wire drawing bench with a prior art
cooling system.
[0040] Figure 2a describes a first embodiment of the cooling system and capstan in a wire drawing bench according the invention in a cross section comprising the axis of rotation of the capstan.
[0041 ] Figure 2b shows a cross section in plane Ί-Γ of Figure 2a of the first
embodiment.
[0042] Figure 3a shows a cross section in a plane perpendicular to the axis of rotation of the capstan of a second embodiment of the invention
[0043] Figure 3b is an enlargement of part of the cooling system of the second embodiment.
[0044] Figure 4 is a cross section perpendicular to the axis of rotation of the
capstan of the cooling system according a third embodiment of the invention.
[0045] Figure 5 is a side view of a fourth embodiment of the inventive cooling system and the associated capstan.
[0046] A reference key list is provided at the end of the description.
Mode(s) for Carrying Out the Invention
[0047] Indicated with 100 in Figure 1 is a capstan of a wire drawing bench with a prior art cooling system. On bench 1 14 different capstans are mounted in a row, with drawing die holders (not shown) in between. The capstan 102 is secured to an axle 120 by means of a fixing bolt 124. The axle 120 is rotatably mounted on bearing 126 on top of the axle bushing 122. The axle 120 is driven by a motor (not shown) at the speed required by the drawing process. Inside of the capstan a cylindrical internal coolant retaining wall 107 is mounted thereby leaving a small gap between retaining wall 107 and capstan 102. Coolant is supplied through coolant feed 1 10 in the direction indicated by the flow arrows 1 16 into this gap. At the bottom of the capstan a coolant seal 105 is present to prevent the coolant from leaking out of the gap. The coolant, after flowing over the internal coolant retaining wall, is collected at the bottom of the drawing capstan and extracted through coolant extraction tube 1 12. The entering hot wire 106 pushes the already present loops of wire up by the action of the sill 108. After having made some loops the cooled wire 106' leaves the capstan to enter the next drawing die or to be wound on a spool.
[0048] This design has some serious drawbacks in that in the coolant of the gap stirring occurs that consumes power, especially at high speeds. Moreover, at the inside of the capstan 102 that is in contact with the coolant foreign material such as rust or other deposits are formed. These deposits have a detrimental effect on the heat transfer from capstan to coolant, thereby reducing the cooling capacity of the system over time. As the cooling capacity is reduced more coolant, e.g. water, must be supplied or the quality of the wire is reduced due to insufficient cooling.
[0049] In Figure 2a a first embodiment 200 in line with the invention is shown.
Figure 2b shows a cross section of the cooling system and capstan along plane indicated Ί-Γ in Figure 2a. Again, hot wire 206 enters the capstan at the sill 208 and is pushed upward until it at 206' leaves the capstan 202 in a cold state. As previously the capstan 202 is fixed by fixing bolt 224 on an axle 220 that is rotatably mounted in an axle bushing 222 through bearing 226 on a bench 214. Different from the prior art embodiments is the cooling system that is based on a carrier ring 223 whereon posts or uprights - three in this case - 213 are fixed. To the each of the posts 213 a flap 204 is mounted. Through coolant feed 210 the coolant is distributed to three coolant feed tubes 218 that spray coolant on the inner wall of the capstan 202 through nozzle 21 1 . The inner wall of the capstan 202 has a surface of revolution 203 at least over an axial length 'L' where contact is made to the flaps 204. The edge of the flap 204' contacting the surface is indicated by line 'A' in Figure 2a. Note that in this embodiment the line 'A' is in a plane comprising the rotation axis of the capstan. The coolant is caught in a sump 217 that is mounted to the bench 214 and drained through the coolant extraction 212. As no sealing ring is needed anymore, there is no power loss due to friction of such seal.
[0050] In this particular embodiment each flap 204 is made of a flexible material that is rigidly connected to the carrier at their post 213. The flaps are for example made of stainless steel sheet of 0.8 to 1 .0 mm thick. An alternative material is aluminium sheet of 1 .5 mm . The flaps are deflected, at least during use, in the rotation direction 219 of the capstan. The angle that forms at the other edge of the flap where the flap meets the surface of revolution of the internal wall is the wedge angle 'a' which is in this case about 15°. The total force by which the flap presses against the inner wall of the capstan 202 is between 20 to 30 newton over a length of 20 cm. This combination of contact line pressure and wedge angle makes the flap skid on water coolant from a speed of about 100 m/min onward. Below that speed the water coolant film breaks and the edge 'A' of the flap scrapes the inner wall of the capstan, thereby removing and cleaning any deposits - such as rust - that may have formed. In addition to that the flaps help to reduce the speed of the capstan, i.e. act as an additional brake.
[0051 ] Figure 3a and the enlargement Figure 3b show a second embodiment of the invention. Again the cooling system consists of a carrier made of a ring 323 on which uprights 313, 313', 313" are fixed. In this embodiment the flaps 304, 304' and 304" are rigid. They can be made of grey cast steel of 3 mm thick. Grey cast iron resists abrasion well and acts as a grinding stone to better clean the surface of the inner wall. To make them
deflectable, each flap is connected to the upright 313 with a hinge 309 at the carrier edge of the flap. To press the flap against the inner wall of the capstan, a steel blade spring 315, 315" is mounted between the upright 313, 313', 313" and the associated flap. Here the coolant nozzles 31 1 are mounted midways the flaps and spray coolant directly on the inner wall of the capstan.
[0052] The detailed view Figure 3b shows what happens when the capstan 302 is turning and coolant is fed. Under the action of the spring 315", the flap 304" is pushed against the inner wall surface 303 of the capstan, thereby forming the wedge angle 'a'. During rotation at normal operating speed, in direction 319, the wedge angle together with the pressure on the flap results in skidding of the flap on the coolant and a coolant film 327 forms. When the capstan slows down - or alternatively during ramp up - the film 327 does not form and the edge of the flap is running against the inner wall of the capstan at the landing zone 325. The landing zone 325 will closely follow the rounding of the capstan due to the wear at the edge. [0053] Figure 4 shows a third embodiment of the cooling system 401 . Here the carrier is a steel tube 413 of thickness 2.5 mm out of which the six flaps 404, 404', 404", 404"', 404"", 404 are laser cut and then plastically bend to a circumscribed circle larger than the inner diameter of the capstan. By heat treating, quenching and annealing, the yield strength of the steel is greatly increased thereby forming flaps that are resilient. The tube is mounted to ring 423. After insertion into the capstan, the flaps will take the shape as indicated. Each of the flaps has a landing zone 425 that is tangential to the inner surface of the capstan. The wedge angle is therefore close to 0°. The landing zone ends in Vulkollan® a high performance elastomer of Bayer. Alternatively, the end is coated with an abrasive and wear resistant layer of bronze. Each flap is fed with coolant distributed from coolant feed 410 by tubes 418 ending in individual nozzles 41 1 for each of the flaps. The nozzles spray coolant between the inner surface of the capstan and the flap. As the wedge angle is so small, the flaps will skid already at very low speeds onward (from about 20 m/min ) thereby reducing the friction to the inner wall. In order to remove deposits from the inner wall it is therefore necessary to start and stop the machine dry - i.e. without supply of coolant - in order to remove the deposit.
[0054] Figure 5 shows a further embodiment of the invention according the
second aspect of the invention i.e. the combination of a cooling system and a capstan. In this embodiment the line 'A' where the flap 504 and the inner surface of revolution 503 of the capstan 502 meet is in a plane making an inclined angle 'β' to the axis of rotation of the capstan. The inclined angle is such that coolant fed from nozzle 51 1 is driven upward, against the action of gravitation when the capstan is turning in direction 519. The flexible flap 504 is rigidly mounted to post 513 that on its turn is mounted to ring 523. Another particular feature of this embodiment is that the surface of revolution 503 is recessed in the inner wall of the capstan 502 over the axial length 'L'. This in order to retain the coolant better there where it is needed. Reference Key list
[0055] The following references are used in the drawings. References with equal unit and ten numbers refer to parts with similar function over distinct embodiments of the different drawings.
The hundred number refers to the related figure 'x'.
Item
Cooling system and capstan
Cooling system
Capstan
Surface of revolution of inner wall of capstan Flaps
Coolant seal
Wire entering, wire exiting
Internal coolant retaining wall
Sill of capstan
Hinge of flap
Coolant feed
Coolant nozzle
Coolant extraction
Support, upright, part of carrier
Bench
Spring
Coolant flow direction
Coolant sump
Coolant feed tube
Capstan, direction of rotation during use
Capstan axle
Capstan axle bushing
Ring, part of carrier
Fixing bolt for capstan
Landing zone
Bearing
Coolant film

Claims

Claims
1 . A cooling system for a capstan of a wire drawing bench, said capstan being mounted rotatable to said drawing bench, said capstan having an inner wall with a surface of revolution over at least part of the axial length of said wire drawing capstan, said cooling system being mountable stationary to said wire drawing bench inside of said capstan,
characterized in that
said cooling system comprises a carrier and a number of deflectable flaps, said flaps are mounted at their carrier edge to said carrier and are at the opposite, pressed edge pressable against said inner wall, said flaps being deflected, during use, in the direction of rotation of said capstan thereby breaking the contact between said pressed edge and said inner wall, said pressed edge contacting said inner wall when the rotation of said capstan is stopped.
2. The cooling system according to claim 1 , wherein the wedge angle is an acute angle, said wedge angle being the angle between said deflectable flap and said surface of revolution in the plane perpendicular to the contact line, said contact line being the line where said pressed edge and said inner wall meet at standstill.
3. The cooling system according to claim 1 or 2 wherein the contact line pressure of said flaps to said surface is such that, at the operational speed of said capstan, a coolant film forms between said flap and said surface and, at ramp up or ramp down, said flaps scrape the surface of said inner wall.
4. The cooling system according to any one of claims 2 to 3 wherein the acute wedge angle is within the range including 0° to 45° over the length of the contact line.
5. The cooling system according to any one of claims 1 to 4 wherein each flap has an associated coolant supply, said coolant supply being oriented to inject coolant into the acute wedge angle between said deflectable flap and said inner wall.
6. The cooling system according to any one of claims 1 to 5 wherein said flaps are rigid and pressable against said surface by the action of a spring fixed between said carrier and each one of said flaps.
7. The cooling system according to any one of claims 1 to 5 wherein said flaps are flexible and pressable against said surface and are rigidly mounted to said carrier.
8. The cooling system according to any one of claim 6 or 7 wherein said flaps are further provided with a landing zone at the pressed edge, said landing zone following the shape of said surface.
9. The cooling system according to claim 8 wherein said landing zone is provided with a wear resistant and/or abrasive coating.
10. The cooling system according to any one of claims 1 to 9 wherein the contact line pressure is between 10 and 1000 newton per meter.
1 1 .The cooling system according to any one of claims 1 to 10 wherein said
contact line is substantially in a plane comprising the axis of rotation of said capstan.
12. The cooling system according to any one of 1 to 10 wherein the line where said flap and said surface meet is substantially in a plane making an inclined angle to the axis of rotation of said capstan, said inclined angle being such that, during operation, coolant is driven upward, opposite to the direction of gravitation.
13. The cooling system according to claim 12 wherein said inclined angle is
between 1 and 60 degrees.
14. The combination of the cooling system according to any one of claims 1 to 14 and a capstan adapted for use with said cooling system.
15. The combination of the cooling system and capstan according to claim 14
wherein the surface of revolution is recessed in said inner wall of said capstan.
16. A wire drawing bench comprising a least one cooling system according any one of claims 1 to 14.
EP15718161.1A 2014-04-29 2015-04-07 A cooling system for a dry drawing capstan Active EP3137236B1 (en)

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CN118477909B (en) * 2024-06-12 2024-11-01 江苏双之龙机械科技有限公司 Wire drawing reel of wire drawing machine

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SU939153A1 (en) * 1981-01-21 1982-06-30 Магнитогорский горно-металлургический институт им.Г.И.Носова Drawing drum
SU997890A1 (en) * 1981-07-02 1983-02-23 Пермский политехнический институт Drawing machine traction drum
SU1296254A1 (en) * 1984-10-07 1987-03-15 А.А.Кулибаев и А.Г.Егай Drawing block
CN201140234Y (en) * 2007-08-06 2008-10-29 蔡海进 Wound roll refrigerating device of wiredrawing bench
CN101698200B (en) * 2009-10-28 2011-04-20 无锡平盛科技有限公司 Intermediate winding drum device of wire-drawing machine
CN203292203U (en) * 2013-05-27 2013-11-20 昆山市线缆机械厂 Winding drum of wire drawing machine

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CN106457326B (en) 2018-11-02
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BR112016024857A2 (en) 2017-08-15
CR20160482A (en) 2017-01-02
WO2015165695A1 (en) 2015-11-05
CN106457326A (en) 2017-02-22
EP3137236B1 (en) 2018-03-14
HUE037338T2 (en) 2018-08-28
BR112016024857B1 (en) 2022-12-27

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