The invention relates to a device for drawing wire, comprising multiple cone pairs arranged in a row and drawing dies arranged between cones of a cone pair, wherein wire that is to be drawn runs from one cone pair to the next cone pair.
Devices of the type named at the outset are usually embodied as wet drawing machines, wherein a central drive is provided and operation occurs according to the sliding wire drawing principle, that is, with a slip between the wire and the pulling disc. Drawing machines of this type comprise multiple (drawing) cones, via which the wire is guided in a coiling manner and is drawn through drawing dies or drawing tools arranged next to one another in the wire path to reduce its cross section. Because of a tapered cross section in the individual drawing dies in the direction of wire travel, a defined wire elongation results. In accordance with this wire elongation of the cone pairs arranged one after another, the rotational speeds of the same also need to be increased. Within a cone pair, an increase in the speed of the wire, and therefore a circumferential speed matched to the wire path area, is achieved at the cone circumference via ascending cone diameter steps.
Normally, with conical wire drawing machines, an operation of the cones with a certain slip (that is, a higher rotational speed than is absolutely necessary) in relation to the wire is normally essential. By setting a slip, it is taken into consideration that the cones and the drawing dies are subjected to a wear that may also vary. However, the slip is to be minimized. At the last cone block in the drawing direction or a downstream drawing-off disc or drawing-out disc, however, no more slip should be present.
A disadvantage in the case of a fixed slip is that, because a constant machine slip is predefined, a total slip across the cone discs increases continuously in an unfavorable manner due to a necessary predefined technological slip in the direction of a decreasing wire diameter. This has a negative effect on a surface quality of the finished wire and influences the wire properties, the drawing disc wear, the machine-specific drawability, the energy use and the risk of wire breakage during the drawing process in an equally negative fashion.
A structural adjustment of a wet drawing device to different operating states, or a slip adjustment as disclosed, for example, in DE 197 53 008 A1, proves to be difficult in practice and is also inflexible in respect of a change in process parameters.
A more suitable method for defining a slip and ultimately also a loading of the wire passing through a wet drawing device, is a regulation of individual drive units, as this is disclosed in DE 10 2007 019 289 A1. In the case of a wet drawing device according to said document, exactly one driving motor is assigned to each drawing cone. Furthermore, a regulation is provided with which, as a function of a rotational speed of a drawing-out disc arranged downstream from the cones, a regulation of the drive units of the drawing cones, and therefore also of the slip, occurs. A wet drawing device of this type allows the slip to be adjusted; however, the regulation is complicated and the device is expensive overall due to the necessary number of drives. In particular, the complexity of the regulation of the drives interacting with one another and a high stress on the wire that is to be drawn, with the associated risk of a wire tear, are disadvantageous in the case of this wet drawing device.
The object of the invention is to disclose a device of the type named at the outset, for which a slip at individual cone pairs can be optimized by simple means so that fine wires and ultra-fine wires, particularly those made of steel, can be produced with high process reliability and good surface qualities, the lowest possible torsion, and low residual stress.
This object is attained according to the invention if, in a device of the type named at the outset, one motor is provided for each cone pair in order to drive the cone pair.
With the embodiment according to the invention of a device or a wet drawing machine, altered process parameters, for example caused by wear or clogging of drawing dies, can be accounted for in a simple manner. At the same time, a device-related cost is thereby minimized, as each cone pair is driven by a separate motor. For this purpose, the individual drive units are operated in a controlled and deviation-neutral manner in relation to the process parameters so that a slip can also be minimized. It is thereby possible to create wires with outstanding surface qualities at a high production speed. High production speeds can thereby also be achieved because the wire that is to be pulled is subjected to a smaller load in contrast to individual cones respectively provided and operated with one drive.
The individual cones can essentially be embodied in multiple pieces from individual discs having a different diameter. However, for the sake of a simple exchangeability of the cones, it is preferred if these cones are embodied in one piece.
An arrangement of the cones of a cone pair can occur in any desired manner. For example, the cones can be arranged next to one another. However, it is advantageous, again in terms of a lowest possible loading of the wire that is to be pulled, if the cones of a cone pair are arranged above one another. Furthermore, an optimal flushing of the drawing dies can be ensured by means of a perpendicular drawing direction directed from bottom to top. Abraded particles can be reliably removed from the deformation zone, which has a positive effect on the service lives of the drawing dies.
It has proven particularly advantageous if the cone pairs are offset from one another such that the wire travels on a plane lying perpendicular to rotation axes of the cones during a transfer from one cone pair to the next cone pair. It is thus prevented that the wire must travel at an incline to the rotation axes during the transfer, which could cause additional tensions and loads.
The individual cone pairs are preferably arranged in multiple chambers, wherein the chambers can be flooded with a liquid separately from one another. Ordinarily, three to five cone pairs are provided. The first two cone pairs in particular can then be arranged in a shared chamber. Because of the leak-tightness of the chambers, a liquid lubricant and coolant can be applied to these chambers in order to, on the one hand, facilitate a passage through the drawing dies and, on the other hand, to dissipate the deformation heat produced by the deformation.
After the last cone pair, at least one end drawing die can be provided which performs a final deformation. It is preferred that two end drawing dies are provided, wherein the end drawing dies are spaced apart from one another. This makes it possible to measure the drawn wire, in particular the diameter thereof, in the region of the last drawing die. The last end drawing die performing a deformation can be rotatably positioned by means of a holder so that the wire can be fed to downstream units on an adjustable plane.
Preferably, a drawing-out disc is arranged downstream from the last cone pair, which disc is preferably operated without slip. The drawing-out disc can be arranged such that the wire extends from the last cone pair on a plane lying perpendicular to the rotation axes of the last cone pair and the drawing-out disc.
To avoid a device-related cost, it is preferably provided that the drawing-out disc and the last cone pair are connected to the same motor and can be driven by this motor. The number of the necessary motors is thus reduced with a simultaneously good controllability of the process. Particularly in terms of the process management, a regulation can be provided with which a rotational speed regulation of the motors occurs as a function of a rotational speed of the drawing-out disc. In addition, a testing disc can be arranged downstream from the drawing-out disc, with which testing disc a defined test load can be applied to the wire. This allows the wire to be tested immediately for suitability for use. It is thereby also advantageous if the applied test load is maintainable as a function of the rotational speed of the drawing-out disc, in particular by means of a corresponding regulation. The test load can then be adjusted to the rotational speed of the drawing-out disc and therefore to the wire speed.
Both the drawing-out disc and also the testing disc can be equipped on a front face with a co-rotating disc which comprises openings through which a suctioning of air occurs when the disc rotates. The rotation of the drawing-out disc or the testing disc, which rotation is necessary in any case, is thus utilized in order to cool the discs themselves, but also the wire traveling over these discs, in a natural manner. This can occur in a particularly efficient manner if the drawing-out disc and/or the testing disc are arranged in closeable chambers, wherein the chambers comprise a corresponding recess in the region of the disc or discs. Air is then suctioned, as in the case of a fan, from the outside, which air produces the desired cooling.
A regulation of the individual motors in the motor cluster can then be achieved particularly easily if the motors are servomotors. Constant tensile stresses in the wire path can then be set within a narrow range at the transition between the individual cone pairs so that no wire tear occurs due to overloading. Any individual torque changes occurring are measured so that re-adjustment is also possible as needed. For this purpose, it can be provided that predefined nominal torques are stored or that comparative torques are configured as differences between adjacent drives or cone pairs, which differences serve as reference values.
Additional features, benefits and effects of the invention are derived from the following exemplary embodiment of the same. The drawings which are thereby referenced show the following:
In
Between the individual cones 21, 22, 31, 32, 41, 42 of a cone pair 2, 3, 4, drawing die holders with drawing dies 23, 33, 43 are arranged, through which wire 5 is drawn which is drawn off from a spool and fed to the device 1 and drawn by this device. By means of the drawing die holders with drawing dies 23, 33, 43, the diameter of the wire which is fed through, typically a steel wire, is reduced continuously, wherein deformation heat is produced. The cross-sectional decreases at the first two cone pairs 2, 3 typically lie within the range of 13% to 18% and are approximately 1% to 3% less at the third cone pair 4. Each drawing die holder holds at least one drawing die 23, 33, 43, but usually multiple drawing dies.
In a manner to be explained below, each individual cone pair 2, 3, 4 is driven by a motor 6, 7, 8 which is located respectively behind the cone pair 2, 3, 4. A drawing-out disc 11 is arranged downstream from the last cone pair 4, with which disc the wire 5 is drawn off from the last cone pair 4 with an additional cross-sectional reduction of approx. 8% to 12% and is fed to a testing disc 12 following another coiling revolution. The wire 5 is guided on the drawing-out disc 11 without slip. At the testing disc 12, a test load is applied in order to test the wire for suitability for use. The applied test load is variable and depends on the rotational speed of the drawing-out disc 11 or is regulated according to the rotational speed thereof. From the testing disc 12, which is also operated without slip, the wire 5 is ultimately fed via a placer 17 onto a winder 18, where a finished wire roll 19 can be removed upon completion. A dedicated motor is provided for the testing disc 12.
In
As can be seen in the perspective representation in
A drawing-out disc 11 is arranged downstream of the actual wet drawing device or at the cone pairs 2, 3, 4, which disc is arranged in a separate section, as is a testing disc 12 which is arranged downstream of drawing-out disc 11. By means of the drawing-out disc 11, the wire 5 is drawn off from the last cone pair 4 without slip, wherein a further cross-sectional reduction of approximately 8% to 12% can occur. After the wire 5 is guided in a coiling manner until a complete frictional fit is achieved, but is guided at least once in a coiling manner, this wire is fed to the testing disc 12, with which a defined testing load is applied to the wire 5. It is thus ensured that the wire 5 exhibits a required strength. The testing load that is applied by the testing disc 12 is regulated as a function of the rotational speed at the drawing-out disc 11 in order to account for the respective current circumstances. Furthermore, a stretching load is also advantageously applied via this arrangement, by means of which load the wire 5 is straightened and residual tensions can be effectively eliminated, for which reason none of the roller straighteners used in current practice are required, which straighteners frequently exhibit bearing damage after a brief period of use and are exposed to significant wear. The drawing-out disc 11 is arranged such that, similar to between the cone pairs 2, 3, 4, a plane is again formed between the last cone pair 4 and the drawing-out disc 11, which plane lies perpendicular to the rotation axis of the driving disc 11 and in which the wire 5 travels during the transfer.
The drive concept is illustrated in greater detail on the basis of
A regulation of the device 1 occurs via the drawing-out disc 11. A load torque ratio between two adjacent drives must not exceed a critical limit value, which would inevitably lead to wire breakage. As a result of a drawing die wear or diameter increases in the individual drawing dies 22, 23, 43, however, torque changes occur which are measured, or are transmitted by the servomotors, and corrected if necessary by a re-adjustment of the rotational speeds. For this purpose, the rotational speed of the drawing-out disc 11 is calculated, which as a rule must be equal to a predefined setpoint value (a maximum production rotational speed, in the ideal case). In the event of corresponding deviations from the setpoint value, a regulation of the servomotors 6, 7, 8 respectively arranged upstream occurs so that, on the one hand, a slip minimization is achieved at the cones 2, 3, 4 and, on the other hand, a minimization of the wire loading is achieved.
In
Furthermore, the device 1 advantageously has a leakage indicator 300 for monitoring the leak-tightness of the cone shafts and for preventing the drawing agent from entering the bearings with subsequent bearing damage. For this purpose, an intermediate chamber is provided in the region of a sealing unit and a shaft bearing, via which chamber the leak flow of a drawing agent is drained in a collected manner and guided into indicator containers via lines which are each distinctly assigned to the sealing unit, whereby a leaking shaft bearing becomes clearly identifiable for a device operator and, if necessary, suitable measures can be taken in order to specifically counteract costly bearing damage subsequently occurring in the event of an unidentified leak flow. Lengthy downtimes can thus be effectively avoided.
In
As follows in particular from a review of both
In
To limit the disadvantageous case of a continuous slip accumulation across all stages of the deformation and to be able to autonomously perform all adjustments of the device 1 via the regulation thereof, wherein additional sensors can be completely omitted and the device 1 nevertheless produces in a manner adjusted to an optimal operating state, a regulation or control according to
Unlike a frequency converter, a servo controller has vastly quicker intervention options, since along with the voltage amplitude and the frequency, a phasing of the current can also be modified. In particular, through the option of interfering with the phasing, very quick current modifications, and therefore torque modifications, are possible. This is also a prerequisite for a dynamic drive behavior, which is necessary if the overlaid rotational speeds or torques are supposed to be or need to be dynamically adjusted. The servo control concept used for the device 1 occurs by means of a storage of a motor model in the servo controller so that the magnetizing component and the active component of the motor current can be regulated independent of one another. The dynamic characteristics of the controller are thus significantly improved.
Since, for functional reasons, the drawing process with a device 1 is always to be operated with a certain slip, it is expedient to provide a base slip on the order of approximately 2% across the individual geometries. The startup of the device 1 is therefore carried out using a pure rotational speed control. The regulation of the rotational speeds thereby occurs in a simple manner via the rotational speed of the drawing-out disc 11, which specifies a reference setpoint value or a maximum production speed. During the startup, the testing disc 12 can already be driven via the torque to achieve optimal wire qualities. Then, once stable production conditions have been achieved, it is expediently possible to change over into a torque-controlled operation of the motors 6, 7, 8. This transition can be performed manually or automatically. Although a complete frictional connection must not occur during a sliding drawing process, since otherwise a wire tear inevitably occurs in the device 1 and a slip measurement is also not possible, as no suitable systems are available on the market in this regard which can metrologically capture the wire speed at all drawing stages, an adjustment to changing conditions (process parameters and/or changes in tool condition), and therefore an optimized product speed, can be achieved using the speed information or torque information or the corresponding shafts without sensor systems while avoiding a wire tear.
With a regulation diagram according to
Number | Date | Country | Kind |
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50097/2012 | Mar 2012 | AT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/AT2013/050071 | 3/22/2013 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2013/138836 | 9/26/2013 | WO | A |
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English translation of JP 63-010020. |
Japan Office Action (Decision of Refusal) conducted in counterpart Japan Appln. No. 2015-500713 (dated Dec. 14, 2016) (w/ English translation). |
Japan Office Action (Notice of Reasons for Rejection) conducted in counterpart Japan Appln. No. 2015-500713 (dated Dec. 20, 2016) (w/ English translation). |
China First Office Action conducted in counterpart China Appln. No. 201380026812.7 (dated Aug. 31, 2015) (w/ English translation). |
China Second Office Action conducted in counterpart China Appln. No. 201380026812.7 (dated May 3, 2016) (w/ English translation). |
China Third Office Action conducted in counterpart China Appln. No. 201380026812.7 (dated Nov. 2, 2016) (w/ English translation). |
China Fourth Office Action conducted in counterpart China Appln. No. 201380026812.7 (dated Mar. 17, 2017) (w/ Engl. translation). |
Austria Office Action conducted in counterpart Austria Appln. No. A 50097/2012 (dated Jan. 18, 2013) (w/ machine translation). |
Number | Date | Country | |
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20150158066 A1 | Jun 2015 | US |