METHOD FOR ROLLING A RING-SHAPED ROLLED STOCK WITH AN OPEN CYLINDRICAL CROSS-SECTION IN A RING ROLLING MACHINE AND RING ROLLING MACHINE FOR CARRYING OUT THE METHOD

Description

[0001] The invention relates to a method for rolling an annular rolling stock with an open cylindrical cross-section in a ring rolling machine with inductive heating of the rolling stock during the rolling process.

[0002] The invention particularly relates to a method for producing metal rings with rectangular or profiled cross-sections from various types of steel, as well as special alloys such as titanium and nickel-based alloys, copper alloys and aluminum alloys by rolling.

[0003] The inductive heating of rolling stock during the rolling process for rolling an annular rolling stock is generally known, for example from US 2012 / 0279268 A1. This document relates to a method for forging an annular workpiece with simultaneous electrical heating of the workpiece by induction. The method comprises partially or completely enclosing the workpiece with a closed or C-shaped magnetizable core, which is wound with a coil that is supplied with a low-frequency alternating current in the range of approximately 1000 Hz or less. This method is cumbersome and complex, not least because of the necessary enclosing of the workpiece with the magnetic or magnetizable core.

[0004] Further prior art is known from CN 109590417 A, CN 109663821 A and JP 01237036 A.

[0005] A method according to the preamble of claim 1 and a ring rolling machine according to the preamble of claim 7 are known from EP 3 385 005 A1.

[0006] The invention is based on the object of providing a method of the type mentioned at the outset in which it is easily possible to compensate for temperature losses of the workpiece during forming and, in particular, to achieve inductive heating of the rolling stock during the rolling process with the least possible effort.

[0007] Temperature control during rolling is intended to counteract heat losses, particularly due to radiation. As the size of the rolled stock increases, or as the diameter of the ring increases during rolling, the surface area increases, leading to increasing heat losses. The invention aims to compensate for these temperature losses.

[0008] The object is achieved by a method having the features of claim 1 and by a ring rolling machine having the features of claim 7.

[0009] According to one aspect of the invention, the method comprises the use of at least one inductor which is held at a predetermined and constant coupling distance relative to the rolling stock and is tracked or carried along during the forming process in accordance with the dimensional change of the rolling stock, wherein an alternating magnetic field, preferably with a frequency between 4 and 10 kHz, is coupled directly into the rolling stock by means of the inductor.

[0010] Enclosing the rolling stock, or partially enclosing it, with an electrically conductive core is neither provided nor required in the method according to the invention. Instead, at least one inductor is positioned at a relatively small distance from the rolling stock and held there during the rolling process. This distance, which is dimensioned to enable the induction of an alternating magnetic field in the rolling stock and the concomitant heating of the rolling stock, is referred to in the present application as the coupling distance.

[0011] The inductor can be designed as a flat or C-shaped or L-shaped coil.

[0012] The inductor is positioned and held on the outer circumference of the rolled stock during the rolling process. The rolled stock, in the form of a cylindrical ring open on both sides and preferably with a profiled cross-section, undergoes dimensional changes during the forming process. The diameter of the annular rolled stock increases, the height of the ring decreases, and its width also decreases. Accordingly, the invention provides for the inductor to be adjusted according to the dimensional change of the rolled stock, maintaining a constant coupling distance to the rolled stock.

[0013] In principle, the inductor can be attached to a support arm, which can, for example, follow the diameter increase of the ring-shaped rolled stock with a rolling stand for axial rolling of the ring rolling machine. The support arm can, for example, be attached to the rolling stand.

[0014] Alternatively, it can be provided that the inductor is tracked in a controlled manner by means of at least one manipulator with at least one linear movement and / or one rotary movement along a movement axis. This can be accomplished, in particular, by means of a multi-axis industrial robot on which at least one inductor can be arranged.

[0015] The method according to the invention provides for the actual distance between the inductor and the rolling stock to be detected by sensors during the rolling process, and for the coupling distance to be automatically controlled as a target distance depending on the actual distance. Such control can be implemented using a dedicated control unit on the ring rolling machine. Alternatively, the control can be implemented using a separate control unit.

[0016] According to the invention, the sensory detection of the actual distance of the inductor from the rolling stock is carried out tactilely by means of at least two sensing rollers or spacers, whereby the distance of the inductor from the rolling stock is predetermined by the spacers in contact with the rolling stock during the rolling process.

[0017] In addition, contactless detection of the actual distance can be provided by means of at least one optical sensor.

[0018] In a preferred variant of the method according to the invention, an inductive coupling with at least one inductor is provided in the direction of rotation of the rolled stock at least upstream of a main roll or an axial roll arrangement of the ring rolling machine, so that heating of the rolled stock occurs immediately before the main roll or the axial roll arrangement engages the rolled stock. The invention is to be understood in such a way that the inductor or several inductors can be provided at any location on the circumference of the rolled stock on the ring rolling machine.

[0019] Furthermore, it can be provided that at least two inductors are positioned on the circumference of the rolling stock, for example in the direction of rotation of the rolling stock at least in front of a main roll and in front of an axial roll arrangement of the ring rolling machine if this is designed as a radial-axial ring rolling machine.

[0020] As already mentioned above, it is expedient for the inductor to be guided on a support arm that preferably has at least two degrees of freedom, preferably three. The inductor is preferably guided so that it can be moved linearly as well as rotated.

[0021] According to the invention, the inductor is moved along with the increasing radius and with the displacement of the rotation axis of the cylindrical rolling stock during the rolling process.

[0022] A further aspect of the invention relates to a ring rolling machine, which is preferably designed to carry out the method described above. The ring rolling machine is preferably designed as a radial or radial-axial ring rolling machine and comprises at least one driven main roll and at least one mandrel roll, preferably furthermore at least two axial rolls, preferably as tapered rolls, as well as means for centering an annular rolling stock. The ring rolling machine according to the invention is characterized by at least one inductor, which can be positioned on an outer circumference of the rolling stock during the rolling process with a predetermined coupling distance from the rolling stock and can be adjusted according to the dimensional change of the rolling stock in order to maintain a constant coupling distance, wherein an alternating magnetic field, preferably with a frequency between 4 and 10 kHz, can be induced in the rolling stock using the inductor.At least one of the axial rollers can be designed as a driven roller.

[0023] The ring rolling machine can be designed as a radial ring rolling machine or as a radial-axial ring rolling machine. Only in the latter case would the ring rolling machine according to the invention comprise axial rollers.

[0024] As a means for centering the rolling stock, pivoting arms with centering rollers can be provided, which rest against the outer circumference of the rolling stock during the rolling process.

[0025] In a preferred variant of the ring rolling machine according to the invention, it is provided that the inductor is fastened to a support arm of a manipulator movable in at least two degrees of freedom, preferably in three degrees of freedom.

[0026] In a further advantageous variant of the ring rolling machine according to the invention, it is provided that the inductor is arranged at least in front of the main roll or the axial rolls in the direction of rotation of the rolling stock.

[0027] Alternatively, it can be provided that an inductor is arranged in front of the main roll and the axial rolls in the direction of rotation of the rolling stock.

[0028] The invention is to be understood in such a way that more than two inductors can be provided on the circumference of the rolling stock.

[0029] The invention is explained below with reference to an embodiment shown in the drawings.

[0030] They show: Figure 1 is a perspective view of a ring rolling machine according to the invention, Figure 2 is a plan view of the ring rolling machine according to the invention, and Figure 3 is a perspective view of the inductor.

[0031] The ring rolling machine 1 shown in the figures comprises a driven main roll 2 and a rolling table 4. The rolled stock, designated 5, is designed as a closed ring or as a cylinder open on both sides. The rolled stock 5 has a rectangular cross-sectional profile and rests on the rolling table 4. The rolled stock 5 is rolled clockwise between the main roll 2 and the mandrel roll 3, reducing the wall thickness radially and simultaneously reducing the height axially. The rolled stock 5 is centered in the ring rolling machine 1 by means of centering rollers 7 attached to pivot arms 6. The rolled stock 5 is rolled axially by means of two axial rolls 8. The axial rolls 8 are designed as tapered rolls and mounted in an axial stand 10. The axial stand 10 is movable or adjustable with respect to the center of the rolling stock 5, which shifts during the rolling process as a result of the increase in the radius, and specifically radially with respect to the rolling stock 5.

[0032] In the described embodiment, a support arm 11 is attached to the axial stand 10, at the distal end of which, directed radially inward with respect to the rolling stock 5, an inductor 12 is arranged. As already mentioned above, the inductor 12 can alternatively be attached to an articulated arm of an industrial robot mounted on the periphery of the ring rolling machine 1.

[0033] The inductor 12 comprises a transformer unit 14 arranged on a base plate 13 and an induction coil 15, as can be seen from Figure 3The transformer unit 14 is connected to a capacitor cabinet (not shown) via air- and / or water-cooled cables and ensures the electrical adaptation of the induction voltage to the output voltage of a frequency converter. The frequency converter operates in a frequency range between 4 and 10 kHz. Two spacers 16 are also arranged on the base plate 13, between which the induction coil 15 is located. The spacers 16 are designed as sensing rollers extending parallel to the rotational axis of the rolling stock 5, the roller heads 17 of which are held in engagement with the rolling stock 5 during the rolling process. The spacers 16 are water-cooled. Coolant connections 18 are provided for the aforementioned spacers 16, through which coolant flows.

[0034] The induction coil, the transformer unit, and the spacers 16 are arranged on the base plate for both linear and rotational adjustment. Since, as described above, the radius of the rolling stock 5 increases during the rolling process and, consequently, the distance between the induction coil 15 and the rolling stock 5 would increase, a further linear adjustment is provided between the spacers 16 and the induction coil 15. This adjustability ensures that the distance between the induction coil 15 and the rolling stock can be kept constant.

[0035] In order to guide and maintain the inductor 12 at a constant, close coupling distance from the outer circumference of the rolling stock 5 throughout the entire rolling process, the support arm 11 with the axial stand 10 is also radially displaceable relative to the rolling stock. During the rolling process, the height of the rolling stock 5 will decrease, while the diameter of the rolling stock 5 will increase, so the support arm 11 must be adjusted radially, at least relative to the rolling stock 5.

[0036] The Figure 3 The induction coil 15 shown has an approximately L-shaped cross-sectional profile that extends beneath a portion of the underside of the annular rolling stock 5. According to the invention, the induction coil may also have a different geometry. It is not necessary for the induction coil 15 to extend beneath the underside of the annular rolling stock 5. List of reference symbols

[0037] 1 Ring rolling machine 2 Main roll 3 Mandrel roll 4 Rolling table 5 Rolled stock 6 Swivel arms 7 Centering rolls 8 Axial rolls 9 Manipulator 10 Axial stand 11 Support frame 12 Inductor 13 Base plate 14 Transformer unit 15 Induction coil 16 Spacer 17 Roll heads 18 Coolant connections

Claims

1. Method of rolling an annular rolling material (5) with an open cylindrical cross-section in a ring rolling machine (1) under inductive heating of the rolling material (5) during the rolling process with use of at least one inductor (12), which is held at a predetermined coupling spacing relative to the rolling material (5) and during the reshaping process is adjusted or carried along in correspondence with the dimensional change of the rolling material (5), wherein a magnetic alternating field preferably with a frequency between 4 and 10 kHz is coupled into the rolling material (5) by the inductor (12), characterised in that an actual spacing of the inductor (12) from the rolling material (5) during the rolling process is detected by sensor and the coupling pacing is automatically regulated as a target value in dependence on the actual spacing, that the sensor-based detection of the actual spacing of the inductor (12) from the rolling material is carried out in tactile manner and that the tactile detection of the actual spacing is carried out by means of a least two scanning rollers or by means of at least two spacers, which are brought into engagement with the outer circumference of the rolling material.

2. Method according to claim 1, characterised in that the inductor (12) is positioned and held at the outer circumference of the rolling material (5) during the rolling process.

3. Method according to claim 1 or 2, characterised in that the inductor (12) is adjusted in regulated manner by at least one linear movement and rotational movement on at least one movement axis.

4. Method according to any one of claims 1 to 3, characterised in that an inductive coupling is carried out by at least one inductor (12) in rotational direction of the rolling material (5) at least in front of a main roll (2) or an axial rolling arrangement of the ring rolling machine (1).

5. Method according to any one of claims 1 to 4, characterised in that an inductive coupling is carried out by at least two inductors (12) in rotational direction of the rolling material (5) at least in front of a main roll (2) and in front of an axial rolling arrangement of the ring rolling machine (1).

6. Method according to any one of claims 1 to 5, characterised in that the inductor (12) is guided at a support arm (11) having at least two, preferably three, degrees of freedom.

7. Ring rolling machine (1) preferably for carrying out the method according to any one of claims 1 to 6, preferably as a radial or radial / axial ring rolling machine with at least one driven main roll (2), at least one mandrel roll (3) and preferably at least two axial rolls (6) as well as with means for centring an annular rolling material (5), with at least one inductor (12) which during the rolling process is positionable at a predetermined coupling spacing from the rolling material (5) at an outer circumference of the rolling material (5) and is adjustable in correspondence with the dimensional change of the rolling material (5), wherein a magnetic alternating field, preferably with a frequency between 4 and 10 kHz, is inducible in the rolling material (5) by the inductor (12), characterised in that the inductor (12) comprises at least two spacers (16) which can be brought into engagement with an outer circumference of the rolling material (5) and in that case predetermine a defined spacing of at least one induction coil (15) with respect to the outer circumference of the rolling material (5) and that the position of the induction coil (15) with respect to the spacers (16) is adjustable.

8. Ring rolling machine according to claim 7, characterised in that the inductor (12) is secured to a support arm (11) of a manipulator (9) movable in at least two, preferably three, degrees of freedom.

9. Ring rolling machine according to claim 7, characterised in that the inductor (12) is secured to a support arm (11) of an axial stand (10) of the ring rolling machine (1).

10. Ring rolling machine according to any one of claims 7 to 9, characterised in that the inductor (12) is arranged at least in front of the main roll (2) or the axial rolls (8) in rotational direction of the rolling material (5).

11. Ring rolling machine according to any one of claims 7 to 10, characterised in that a respective inductor (12) is arranged in front of each of the main roll (2) and the axial rolls (8) in rotational direction of the rolling material (5).