Method for rolling annular rolling blanks with exposed cylindrical cross sections in a ring rolling mill and ring rolling mill for carrying out said method

Abstract

The invention relates to a method for rolling an annular rolling blank (5) with an exposed cylindrical cross section in a ring rolling mill (1) while inductively heating the rolling blank (5) during the rolling process using at least one inductor (12) which is held at a predefined coupling distance relative to the rolling blank (5) and which is adapted or entrained correspondingly to dimensional changes of the rolling blank (5) during the deformation process, in which an alternating magnetic field, preferably having a frequency of 4 to 10 kHz, is input directly into the rolling blank (5) by the inductor (12). The invention further relates to a ring rolling mill (1) for carrying out this method.

Description

[Technical Field]

[0001] The present invention relates to a method for rolling an annular rolling stock with an exposed cylindrical cross section in a ring rolling mill while inductively heating the rolling stock during the rolling process.

[0002] The invention relates in particular to a method for producing by rolling metal rings with a rectangular or shaped cross section made of various steel grades and special alloys, such as titanium-based and nickel-based alloys, copper alloys and aluminum alloys.

[0003] Induction heating of a workpiece during the rolling process in the rolling of annular workpieces is basically known, for example from US Patent Application Publication No. 2012 / 0279268. This document describes a method for electrically heating the workpiece by induction and simultaneously forging the annular workpiece. This known method involves partially or completely surrounding the workpiece with a closed or C-shaped magnetizable core wound with a coil supplied with a low-frequency alternating current in the range of approximately 1000 Hz or less. Furthermore, this known method is cumbersome and time-consuming, particularly due to the need to surround the workpiece with a magnetic or magnetizable core.

[0004] Other prior art is known from CN109590417, CN109663821, and JP1-237036A.

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

[0006] The object of the present invention is to provide a method of the type mentioned at the beginning, in which the heat loss of the workpiece during deformation can be compensated for and induction heating of the rolled blank during the rolling process can be easily achieved with a particularly minimal effort.

[0007] Temperature control during rolling is particularly important to counteract heat loss due to radiation. As the size of the rolling material increases or the diameter of the ring increases, the surface area increases, which leads to increased heat loss. The present invention aims to compensate for such heat loss.

[0008] This problem is solved by a method having the features of claim 1 and by a ring rolling mill having the features of claim 11.

[0009] According to one aspect of the invention, the method comprises the use of at least one inductor held at a predetermined constant coupling distance relative to the rolled blank and adapted to follow or be entrained in response to dimensional changes of the rolled blank during the deformation process, wherein an alternating magnetic field, preferably having a frequency of 4 to 10 kHz, is input directly into the rolled blank by the inductor.

[0010] Surrounding or partial surrounding of the rolled material by an electrically conductive core is not envisaged or necessary in the method according to the invention. Instead, at least one inductor is positioned at a relatively small distance from the rolled material and maintained there during the rolling process. This distance, which is set to allow the induction of an alternating magnetic field into the rolled material and the associated heating of the rolled material, is referred to in the present application as the coupling distance.

[0011] The inductor may be formed as a flat coil or a coil formed in a C- or L-shape.

[0012] Inductors are 、 During the rolling process, the inductor is positioned and held on the outer periphery of the rolled blank. The rolled blank, preferably in the form of a cylindrical ring open at both ends and having a shaped cross section, is subjected to a dimensional change during the deformation process. The diameter of the annular rolled blank increases, the height of the ring decreases, and the width of the ring decreases as well. Accordingly, the present invention provides for the inductor to follow the rolled blank at a constant coupling distance in response to the dimensional change of the rolled blank.

[0013] In principle, the inductor can be attached to a support arm, which, together with a roller carrier for the axial rollers of a ring rolling mill, can follow the diameter expansion of the annular rolling blank. The support arm can be attached to the roller carrier, for example.

[0014] Alternatively, it may be provided that the inductor is controlled and followed by at least one linear and / or rotational movement along a predetermined axis of movement by at least one manipulator, which may be realized in particular by a multi-axis industrial robot in which at least one inductor may be arranged.

[0015] Method according to the invention in It is assumed that the actual distance between the inductors and the rolled blank is detected by a sensor during the rolling process, and the coupling distance is automatically controlled as a target distance depending on the actual distance. Such control can be performed by a control unit of the ring rolling mill provided for this purpose. Alternatively, this control can be performed by a separate control unit.

[0016] Based on the present invention ,The actual distance of the inductor from the rolled material is detected by the sensor. The rolling is carried out in a contact manner using at least two contact rollers or spacers, in which case the distance of the inductor from the rolled material is determined by the spacers that abut against the rolled material during the rolling process. .

[0017] Follow up Additionally, contactless detection of the actual distance using at least one optical sensor may be envisaged.

[0018] In one preferred variant of the method according to the invention, it is provided that the inductive coupling with at least one inductor is carried out at least upstream of the main roller or axial roller unit of the ring mill in the direction of rotation of the rolling stock, so that the heating of the rolling stock takes place just before the main roller or axial roller unit engages the rolling stock, respectively. The invention means that the inductor or inductors can be arranged around the rolling stock at any point in the ring mill.

[0019] Furthermore, if the ring rolling mill is configured as a radial-axial ring rolling mill, it may be assumed that at least two inductors can be positioned around the rolling material, for example in the direction of rotation of the rolling material, at least before the main roller and before the axial roller unit of the ring rolling mill.

[0020] As already mentioned above, it is advantageous if the inductor is guided in a support arm, preferably with at least two degrees of freedom, preferably three degrees of freedom. Preferably, the inductor is guided both linearly slidably and rotatably.

[0021] According to the invention, the inductor is entrained during the rolling process with the increase in radius and with the displacement of the axis of rotation of the cylindrical rolling blank.

[0022] Another aspect of the present invention relates to a ring rolling mill, preferably configured to carry out the above-mentioned method. The ring rolling mill is preferably configured as a radial ring rolling mill or a radial-axial ring rolling mill and includes at least one driven main roller, at least one mandrel roller, preferably at least two further axial rollers, preferably as conical rollers, and means for centering the annular rolled blank. The ring rolling mill according to the present invention is distinguished by the fact that at least one inductor can be positioned on the outer periphery of the rolled blank with a predetermined coupling gap relative to the rolled blank during the rolling process and can adapt to dimensional changes of the rolled blank to maintain a constant coupling gap. The inductor can then induce an alternating magnetic field in the rolled blank, preferably with a frequency of 4 to 10 kHz. At least one of the axial rollers can be configured as a driven roller.

[0023] The ring rolling mill can be configured as a radial ring rolling mill or as a radial-axial ring rolling mill, only in the latter case does the ring rolling machine according to the invention comprise axial rollers.

[0024] The means for centering the rolled material may include a pivoting arm having a centering roller that contacts the outer peripheral surface of the rolled material during the rolling process.

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

[0026] In one further advantageous variant of the ring rolling mill according to the invention, it is provided that the inductor is arranged at least in front of the main roller or the axial roller in the direction of rotation of the rolling blank.

[0027] Alternatively, it may be provided that one inductor is arranged in front of the main roller and one in front of the axial roller in the direction of rotation of the rolled stock.

[0028] The present invention means that three or more inductors may be provided around the rolled material.

[0029] The present invention will now be described with reference to the illustrated embodiments. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a perspective view of a ring rolling mill according to the present invention; [Figure 2] 1 is a plan view of a ring rolling mill according to the present invention; FIG. [Figure 3] FIG.

[0031] The illustrated ring rolling mill 1 includes a driven main roller 2 and a rolling table 4. The rolling blank, designated by the reference numeral 5, is configured as a closed ring or as a cylinder open on both sides. The rolling blank 5 has a rectangular cross-sectional profile and is placed on the rolling table 4. Between the main roller 2 and the mandrel roller 3, the rolling blank 5 is rolled clockwise in the radial direction, reducing its wall thickness, and simultaneously rolled axially, reducing its height. The rolling blank 5 is centered in the ring rolling mill 1 by a centering roller 7 attached to a pivoting arm 6. In the axial direction, the rolling blank 5 is rolled by two axial rollers 8. The axial rollers 8 are configured as conical rollers and are supported on an axial support 10. The axial support 10 is movable or adjustable relative to the center point of the rolling blank 5, which is displaced due to the expansion of its radius during the rolling process, and is also movable or adjustable radially relative to the rolling blank 5.

[0032] In the embodiment described, a support arm 11 is mounted on the axial mount 10, and an inductor 12 is arranged on the end of the support arm 11 that faces away from the support arm 11 and toward the radial inside with respect to the rolling blank 5. As already mentioned above, the inductor 12 may alternatively be mounted on a jointed arm of an industrial robot that is arranged around the ring rolling mill 1.

[0033] As can be seen in FIG. 3, the inductor 12 includes a transformer unit 14 and an induction coil 15 arranged on a base plate 13. The transformer unit 14 is connected to a condenser cabinet (not shown) via an air- and / or water-cooled cable and serves to electrically match the induced voltage to the output voltage of the frequency converter. The frequency converter operates in the frequency range of 4 to 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 formed as contact rollers extending parallel to the rotation axis of the rolling blank 5. The roller heads 17 of the contact rollers engage and hold the rolling blank 5 during the rolling process. The spacers 16 are water-cooled. A cooling medium connection 18 is provided for the spacers 16, through which a coolant flows.

[0034] The induction coil, transformer unit and spacer 16 are arranged on the base plate so that they can be displaced both linearly and pivotally. As mentioned above, a large linear displacement between spacer 16 and induction coil 15 is envisaged because the radius of the rolled blank 5 may expand during the rolling process, which may result in an increase in the spacing between induction coil 15 and rolled blank 5. This displacement ensures that the spacing of induction coil 15 relative to the rolled blank can be kept constant.

[0035] In order to be able to guide and hold the inductor 12 with a constant, close coupling gap relative to the outer periphery of the rolled blank 5 throughout the rolling process, the support arm 11 together with the axial mount 10 is also able to slide radially relative to the rolled blank 5. During the rolling process, the height of the rolled blank 5 is reduced on the one hand, and the diameter of the rolled blank 5 is enlarged on the other hand, so that the support arm 11 must be displaced at least radially relative to the rolled blank 5.

[0036] The induction coil 15 shown in Figure 3 has a generally L-shaped cross-sectional profile that extends below a portion of the lower surface of the annular rolling blank 5. In accordance with the invention, the induction coil may have other geometric shapes. It is not essential that the induction coil 15 extend below the lower surface of the annular rolling blank 5. [Explanation of symbols]

[0037] 1. Ring rolling mill 2 Main rollers 3 Mandrel Roller 4 Rolling Table 5 Rolled material 6 Swivel Arm 7 Centering roller 8 Axial Roller 9 Manipulator 10 Axial mount 11 Support frame 12 Inductors 13 Base Plate 14 Transformer Unit 15 Induction Coil 16 spacer 17 Roller head 18 Coolant connection

Claims

1. 1. A method for rolling an annular rolling blank (5) having an exposed cylindrical cross section in a ring rolling mill (1) while inductively heating the rolling blank (5) during the rolling process using at least one inductor (12) that is held at a predetermined coupling distance from the rolling blank (5) and that is caused to follow or be entrained in response to dimensional changes of the rolling blank (5) during the deformation process, the method comprising: inputting an alternating magnetic field directly into the rolling blank (5) by the inductor (12), The actual distance between the inductor (12) and the rolled material (5) is detected by a sensor during the rolling process, and the coupling distance is automatically controlled as a target distance depending on the actual distance. The detection of the actual distance between the inductor (12) and the rolled material by the sensor is performed in a contact manner, and the contact detection of the actual distance is performed using at least two contact rollers or at least two spacers (16) that are engaged with the outer circumferential surface of the rolled material. A method characterized by:

2. 2. The method of claim 1, wherein the inductor (12) is positioned and held on the outer periphery of the rolled blank (5) during the rolling process.

3. The method of claim 1, wherein the inductor (12) is controlled to follow at least one linear and one rotational movement on at least one axis of motion.

4. A method as described in claim 1, wherein inductive coupling between the rolling material (5) and at least one of the inductors (12) is performed at least in the direction of rotation of the rolling material (5) before the main roller (2) or axial roller unit of the ring rolling mill (1).

5. A method as described in claim 1, wherein inductive coupling between the rolling material (5) and at least two of the inductors (12) is performed at least in the direction of rotation of the rolling material (5) before the main roller (2) of the ring rolling mill (1) and before the axial roller unit.

6. 2. The method of claim 1, wherein the inductor (12) is guided in a support arm (11) having at least two degrees of freedom.

7. The method of claim 1, wherein an alternating magnetic field having a frequency of 4 to 10 kHz is generated by the inductor and input to the rolling material.

8. The method of claim 1, wherein the inductor is guided in a support arm having three degrees of freedom.

9. A ring rolling mill (1) comprising at least one driven main roller (2), at least one mandrel roller (3), at least two axial rollers (8), and means for centering an annular rolling material (5), wherein at least one inductor (12) is positionable on the outer periphery of the rolling material (5) with a predetermined coupling distance from the rolling material (5) during the rolling process and is capable of following dimensional changes of the rolling material (5), and wherein an alternating magnetic field can be induced into the rolling material (5) by the inductor (12), The inductor (12) has at least two spacers (16), which can be engaged with the outer peripheral surface of the rolling material (5), and at this time, define a predetermined distance between at least one induction coil (15) and the outer peripheral surface of the rolling material (5), and the position of the induction coil (15) can be displaced relative to the spacers (16). A ring rolling mill (1) characterized by:

10. 10. Ring rolling mill according to claim 9, characterized in that the inductor (12) is attached to a support arm (11) of a manipulator (9) movable in at least two degrees of freedom.

11. 10. Ring rolling mill according to claim 9, characterized in that the inductor (12) is mounted on a support arm (11) of an axial frame (10) of the ring rolling mill (1).

12. 10. The ring rolling mill according to claim 9, wherein the inductor (12) is arranged at least before the main roller (2) or the axial roller (8) in the direction of rotation of the rolling material (5).

13. 10. The ring rolling mill according to claim 9, wherein one inductor (12) is arranged before the main roller (2) and one before the axial roller (8) in the direction of rotation of the rolling material (5).

14. The ring rolling mill according to claim 9, wherein an alternating magnetic field having a frequency of 4 to 10 kHz is generated by the inductor and input to the rolling material.

15. A ring rolling mill as described in claim 9, wherein the inductor is guided in a support arm having three degrees of freedom.

16. The ring rolling mill according to claim 9, wherein the ring rolling mill is configured as a radial-axial ring rolling mill.

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