EP0621095A1 - Method for the intermittent straightening of wire - Google Patents

Abstract

In an apparatus for the intermittent straightening of wire, separate drives are provided for the wire feed and the straightening rotor. The speed of rotation (v2) of the straightening rotor varies essentially in synchronism with the feeding speed (v1) of the wire. To cut the wire (t4), the wire and the rotor are halted. According to the invention, the direction of rotation of the rotor is reversed between successive working cycles. <IMAGE>

Description

Technical field

• a) der Draht auf eine vorgegebene Vorschubgeschwindigkeit beschleunigt,
• b) durch eine Gruppe von Richtsteinen eines ortsfest gelagerten, mit einer gegebenen Winkelgeschwindigkeit rotierenden Richtrotors radial ausgelenkt und
• c) für eine nachfolgende Drahtbearbeitung verzögert wird.

The invention relates to a method for intermittent straightening of wire, in which during a working cycle

• a) the wire accelerates to a predetermined feed rate,
• b) radially deflected by a group of straightening stones of a stationary straightening rotor rotating at a given angular velocity, and
• c) is delayed for subsequent wire processing.

State of the art

A method of the type mentioned at the outset is known from EP-O 313 769-B1. The device for carrying out the method, which is also evident from this patent, is characterized in that the mass moment of inertia of the straightening rotor is dimensioned so small that the straightening rotor can be decelerated and accelerated at least approximately at the same time as the wire. The conveying means for advancing the wire and the straightening rotor can be synchronously accelerated and decelerated by a common drive device. In this way, the mechanical problems of flying scissors, respectively. moving the straightening rotor in the wire direction can be avoided.

Presentation of the invention

The object of the invention is now to provide a method of the type mentioned with a view to reduced wear. to develop a longer lifespan for straightening rotor stones.

According to the invention, the solution is that the straightening rotor rotates with a rotational direction that alternates between the working cycles. The straightening rotor is therefore no longer constantly driven in the same direction. Rather, the direction of rotation is changed at least from time to time. For the straightening stones, this results in more uniform wear and tear. a longer service life.

The direction of rotation is preferably changed periodically. However, the direction of rotation does not have to be changed for every working cycle. Two, three or more working cycles in succession can also have the same direction of rotation. Due to the periodic change of direction, the degree of wear of the straightening stones should be approximately the same in both directions at all times.

At the end of a working cycle, the straightening rotor is advantageously brought into an angular position in which the torque exerted by the wire on the straightening rotor is essentially zero. If the straightening rotor is simply braked and then locked, the wire has an internal twist and thus a certain internal tension. This can be eliminated by briefly turning the straightening rotor back after braking.

The wire and straightening rotor are preferably accelerated and decelerated essentially synchronously. According to a preferred embodiment of the invention, the straightening rotor and the conveying means for transporting the wire are driven by two separate drives (e.g. electric motors). A common control ensures synchronous operation. The feed per rotor revolution (straightening quality) can be chosen almost freely. be programmed.

The control circuit, which, among other things, specifies the changing direction of rotation, is advantageously programmable for the purpose of setting the ratio of the feed speed of the wire to the angular speed of the straightening rotor. The device according to the invention can thus be easily adjusted to different wire thicknesses.

In order to cancel the twisting of the wire at the end of a working cycle, which leads to a torque transmitted to the straightening rotor, the control circuit generates z. B. a signal that leads to a number of revolutions of the straightening rotor opposite to the direction of rotation of the corresponding work cycle. This enables the rotor drive to be activated in the pauses between cuts. The drive does not have to generate a standstill torque during this time and therefore does not need any energy from the supply network.

From the entirety of the description and the patent claims, further advantageous features and combinations of features of the invention result.

Brief description of the drawings

Fig. 1

Eine Blockschaltbilddarstellung einer erfindungsgemässen Vorrichtung;

Fig. 2a, b

zwei Geschwindigkeits-Zeit-Diagramme, nach welchen die erfindungsgemässe Vorrichtung betrieben werden kann;

Fig. 3

Kurven im Geschwindigkeits-Zeit-Diagramm zur Erzielung eines verschwindenden Drehmoments während der Schneidpausen.

The invention will be explained in more detail below on the basis of exemplary embodiments and in connection with the drawings. Show it:

Fig. 1

A block diagram representation of a device according to the invention;

2a, b

two speed-time diagrams, according to which the device according to the invention can be operated;

Fig. 3

Curves in the speed-time diagram to achieve a disappearing torque during the cutting breaks.

Ways of Carrying Out the Invention

1 shows a block diagram of a device for carrying out the method according to the invention. A wire 1 is pushed through a stationary straightening rotor 2 with the aid of conveying means (still to be described in detail). In this, the wire 1 experiences radial deflections in straightening stones 22.1, 22.2, 22.3. The wire 1 is cut at desired intervals with a cutting device 3.

The funding includes drive wheels 4.1, 4.2, 4.3, which are driven by a gear 5 via indicated axes. The gear 5 is z. B. a worm gear, which is attached via a toothed belt 6 to the axis of a motor 7.

The straightening rotor 2 in turn is driven by a motor 12 via a toothed belt 13. The two motors 7 and 12 are each via a separate servo amplifier 8. 11 controlled. The servo amplifiers 8, 11 in turn are supplied with direct current by a converter 9. The entire system is fed by a 3-phase network 10.

The switching stages 8 and 11 are controlled and monitored by a CNC controller 15.

The CNC controller 15 is in data exchange with a known PLC circuit 14. Furthermore, it receives signals from rotary angle transmitters 17, 18 and possibly 19. Via an input device 16, certain operating conditions and / or operating modes can be specified. The input device is connected to the CNC via a communication line.

Finally, there is also a communication line to the cutting device 3.

The rotary encoder 18 is coupled to a measuring wheel 20 which, for. B. is designed as a counter wheel to the drive wheel 4.3. The wire feed at the input of the straightening rotor 2 can thus be measured. A measuring wheel 21 can also be provided at the output of the straightening rotor 2, which determines the feed and the speed of the straightened wire (rotary angle sensor 19). The rotational speed of the straightening rotor 2 is determined with the rotary angle sensor 17 provided on the axis of the motor 12.

The structural details of the device according to the invention can, as long as they do not emerge from the above description and FIG. 1, be designed as described in EP-0 313 769-B1. However, other design variants are also possible within the scope of the invention.

The basic features of the method according to the invention will now be explained with reference to FIGS. 2a, 2b. Time t is plotted on the abscissa and speed v on the ordinate. v₁ stands for the speed of the wire 1 (measuring wheel 20). v₂ stands for the speed of the motor 12, and is proportional to the rotational speed of the straightening rotor 2.

At the beginning of a working cycle, wire 1 and straightening rotor 2 are accelerated synchronously (time interval t 1). When a predetermined feed speed and a corresponding rotor speed are reached, the two motors 7 and 12 run at an essentially constant speed (time interval t 2). The relationship between wire feed speed and rotation speed is, among other things, by determines the wire thickness.

After a predetermined wire length has been straightened in this way, the motors 7 and 12 are decelerated to a standstill (time interval t₃). In the subsequent time interval t₄ the wire is cut by the cutting device 3.

Now the next work cycle begins. Within the time interval t₅, the two motors 7 and 12 are accelerated again. However, according to the invention, the direction of rotation of the motor 12 and thus the straightening rotor 2 was reversed. That is, it rotates in a direction opposite to the direction of rotation of the previous work cycle (t₁, ..., t₄). (The direction of rotation of the motor 7, which is responsible for the feed speed, is of course not reversed, i.e. v₁ remains positive.) In the time interval t₆, the motors 7 and 12 again rotate at a substantially constant speed. Then wire 1 and rotor 2 are decelerated again (time interval t₇). After the time interval t₈ has ended, the second work cycle is ended. According to a particularly preferred embodiment, the direction of rotation of the rotor 2 is reversed again. H. 2 begins again from the beginning (t 1, t 2 ...).

Of course, the direction of rotation does not need to be rotated after each working cycle. You can e.g. B. also inverted every two, three, etc. work cycles. This can be particularly advantageous if it is not desired that the rotor come to a complete standstill. The rotor only needs to be stopped whenever the direction of rotation is changed.

The device shown in FIG. 1 can of course also be used to straighten a wire in a conventional manner (cf. EP-O 313 769-B1). This is indicated in Fig. 2b. In the successive working cycles A₁, A₂, the course of the speeds v₁, v₂ are the same in terms of both sign and amount at corresponding times.

The different operating modes are e.g. B. stored in the PLC circuit 14 and can be selected by input on the input device 16. Because independent drives are available for the wire feeder and the straightening rotor, which are "connected" only by a common control ("electronic axis"), there are a multitude of possibilities for operating the device.

An embodiment of the invention will be explained with reference to FIG. 3, in which the elastic tension of the wire caused by the twisting is released towards the end of each working cycle. The dissolution of the twisting of the wire takes place in the time intervals t₄ or. t₈. The speed v₁ of the wire 1 has the same time course as shown in Fig. 2a. In contrast, the speed v₂ of the motor 12 runs. It is not constantly zero during the time interval t₄, but makes a small negative peak in the subinterval t₄₁ before it assumes the zero value again (subinterval t₄₂). That is, at the end of the deceleration process, the speed v₂ makes a zero crossing, rises briefly in the opposite direction and is then decelerated to zero. The reverse rotation of the wire generated in the time interval t₄₁ is just about so large that a twisting torque prevailing in the wire is at least approximately zero.

The same happens in the time interval t₈, in which the speed v₂ makes a zero crossing from negative to positive, a small peak and then a drop to zero. This brief turning back of the rotor is preferably carried out each time the direction of rotation changes.

The curve profiles shown in FIGS. 2a, 2b and 3 are to be regarded in the sense of basic representations rather than as concrete specifications. Of course, the speed increases and decreases do not necessarily have to be linear. In particular, the need in the periods t .₁ resp. t₈₁ indicated tips not to be realized in this form. What is important is primarily the integral of the peaks shown, which is proportional to the angle of rotation. Of course, the goal should also be to dissolve the twist as quickly and energetically efficiently as possible.

In principle, the direction of rotation of the straightening rotor can also be changed by using a suitable gear. In this sense, it is not absolutely necessary to provide two separate motors for the wire feed and the straightening rotor.

In summary, it can be stated that with a device operated according to the invention, more even wear of the wearing parts (straightening stones) is made possible.

Claims (8)

Method for the intermittent straightening of wire (1), in which (t₁, ..., t₄) during a working cycle a) the wire (1) accelerates to a predetermined feed rate (t 1), b) radially deflected by a group of straightening stones (22.1, 22.2, 22.3) of a stationary straightening rotor (2) rotating at a given angular velocity and c) for a subsequent wire processing (3) is delayed (t₃)
characterized in that d) the straightening rotor (2) with repeated between the working cycles (t₁, ..., t₄ and t₅, ..., t₈) rotating direction of rotation. A method according to claim 1, characterized in that the direction of rotation is changed periodically. A method according to claim 1 or 2, characterized in that the straightening rotor (2) at the end of a working cycle (t₄₁) is brought into an angular position in which the torque caused by an elastic twisting of the wire (1) in the straightening rotor (2) essentially Is zero. Method according to one of claims 1 to 3, characterized in that the wire (1) and the straightening rotor (2) are synchronously accelerated (t₁) and decelerated (t₃). Device for carrying out the method according to claim 1, comprising conveying means for transporting the wire and a rotatable straightening rotor for radially deflecting the wire, characterized in that the conveying means (4.1, 4.2, 4.3) and the straightening rotor (2) each have a motor (7 or 12) and controlled by a common controller (15). Apparatus according to claim 5, characterized in that the control circuit (15) is designed such that the direction of rotation changes periodically. Apparatus according to claim 5 or 6, characterized in that the control circuit (15) is programmable (14) for the purpose of setting the ratio of the feed speed of the wire (1) to the angular speed of the straightening rotor (2). Device according to one of claims 5 to 7, characterized in that the control circuit (15) is designed such that the straightening rotor (2) at the end of a working cycle in order to minimize the torque exerted by the wire (1) briefly opposite to the direction of rotation used in the working cycle is rotated.

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