Rolling tool for circular rolling mill, circular rolling mill comprising such a tool, rolling method using such a rolling mill and method of maintaining such a rolling mill

Abstract

Rolling tool for circular rolling mill, circular rolling mill comprising such a tool, method of rolling using such a rolling mill and method of maintaining such a rolling mill The present invention relates to a rolling tool (10) comprising a drive shaft (120), a first rolling wheel (160), integral with the drive shaft and defining a first rolling surface (S160), and a second rolling wheel (170), defining a second rolling surface (S170). The first and second rolling wheels are movable relative to each other, parallel to a longitudinal axis (A120) of the drive shaft, between a first configuration, in which the first rolling surface (S160) radially surrounds the second rolling surface (S170), and a second configuration, in which the first and second rolling surfaces are offset relative to each other, along the longitudinal axis. Figure for abstract: Figure 3

Description

Title of the invention: Rolling tool for a circular rolling mill, circular rolling mill comprising such a tool, rolling method using such a rolling mill and method of maintaining such a rolling mill

[0001] The invention relates to a rolling tool for a circular rolling mill, as well as to a circular rolling mill comprising, inter alia, such a rolling tool. The invention also relates to a method for rolling an annular part by means of a rolling mill according to the invention, as well as to a method for maintaining such a rolling mill.

[0002] In the field of rolling, it is known, for example from WO2009 / 125102A1, to use a rolling mill which comprises two tools, respectively a mandrel and an external cassette or roller, configured to shape internal and external radial faces of a circular part, as well as a pair of conical rollers, respectively upper and lower, configured to shape upper and lower front faces of the same part.

[0003] In this type of rolling mill, the rolling of the external radial face of the part to be rolled can be carried out in several passes, by means of different rolling surfaces of the external cassette, which are successively brought into contact with this external radial face. These rolling surfaces can have different profiles, the first rolling surface having a shape allowing the part to be rolled to be roughened, one or more other rolling surfaces having a shape allowing the geometry of the face in question to be refined.

[0004] To do this, it is known to use a cassette which has, along its height, two superimposed rolling wheels and which is moved vertically, during rolling, to bring each of its rolling wheels opposite, and into contact with, the part to be rolled. This approach requires vertical movement of the entire cassette which must be mounted on special bearings, compatible with such vertical movement. The rolling mill must be specially designed for this purpose and must include means for maneuvering the cassette, which is a relatively heavy and bulky part, at height. This approach is complex and expensive to implement.

[0005] Furthermore, this approach does not allow retrofitting of existing rolling mills, which are not already equipped with bearings compatible with vertical movement of the cassette and means for moving it in height.

[0006] It is these drawbacks that the invention more particularly intends to remedy by proposing a new rolling tool for a circular rolling mill, which makes it possible to shape a radial face of a part to be rolled successively with two surfaces rolling, without requiring vertical movement of the entire rolling tool.

[0007] To this end, the invention relates, according to a first aspect, to a rolling tool for a circular rolling mill comprising a drive shaft configured to rotate about an axis of rotation; a first rolling wheel secured to the drive shaft, rotating around the axis of rotation, and defining a first rolling surface configured to conform a radial face of a part to be rolled; and a second rolling wheel defining a second rolling surface configured to conform the radial face of the workpiece.

[0008] According to the invention, the first and second rolling wheels are movable relative to each other, parallel to a longitudinal axis of the drive shaft, between a first configuration, wherein the first rolling surface radially surrounds the second rolling surface; and a second configuration, wherein the first and second rolling surfaces are offset from each other, along the longitudinal axis.

[0009] Thanks to the invention, since the first and second rolling surfaces are movable relative to each other, parallel to the longitudinal axis of the drive shaft, it is possible to arrange, opposite a radial face of the part to be rolled, one or the other of these rolling surfaces, depending on the rolling surface which must be used at each stage of the rolling process, without moving the entire rolling tool in height. In other words, the relative mobility of the first and second rolling surfaces along the longitudinal axis of the drive shaft gives the rolling tool of the invention good adaptability to rolling ranges, without it being necessary to move the entire tool vertically during rolling.

[0010] According to advantageous but not mandatory aspects of the invention, such a rolling tool may incorporate one or more of the following features:

[0011] - The rolling tool comprises a device for moving the first wheel of rolling parallel to the longitudinal axis, between a first position in which the first rolling wheel covers the second rolling wheel and a second position in which the first rolling wheel is offset, along the longitudinal axis, relative to the second rolling wheel.

[0012] - The displacement device comprises an actuator and a screw / nut connection between a threaded rod rotated by the actuator and a nut secured to the first rolling wheel.

[0013] - The second rolling wheel is secured to the drive shaft, in rotation around the axis of rotation, by means of at least a first key housed radially between the drive shaft and the second rolling wheel and, in the first configuration, the first rolling wheel is secured to the second rolling wheel, in rotation around the axis of rotation, by means of at least a second key housed axially between the first and second rolling wheels.

[0014] According to a second aspect, the invention relates to a circular rolling mill for shaping annular parts comprising a pair of rolling tools, respectively internal and external, configured to shape internal and external radial faces of a part to be rolled and a pair of conical rollers, respectively lower and upper, configured to shape front faces of the part. According to the invention, at least one of the rolling tools is as described above.

[0015] Advantageously, the actuator is mounted on a bracket, itself mounted in a removable manner on a rolling mill frame and a kinematic connection between the actuator and the threaded rod is active or not depending on whether the bracket is mounted or not on the frame.

[0016] It may further be provided that the first and second rolling wheels are removably mounted on the drive shaft and may be released from this drive shaft while the latter remains in place in the rolling mill, being supported by the frame.

[0017] According to a third aspect, the invention relates to a rolling method using a rolling mill according to the invention and as mentioned above, this method comprising at least successive steps consisting of a. shaping radial faces of the annular part using the internal and external rolling tools, while the first and second rolling wheels are in their first configuration; b. moving the first rolling wheel relative to the drive shaft, so as to bring the first and second rolling wheels into their second configuration, without shifting the drive shaft along the axis of rotation; c. shaping the radial faces of the annular part by means of the internal and external rolling tools, while the first and second rolling wheels are in their second configuration.

[0018] Advantageously, the method as described above, implemented with a rolling mill in which the rolling tool is as mentioned above, in which the actuator is controlled to deliver a limited torque and drive the worm screw with a rotational speed greater or less than the rotational speed of the drive shaft, maintaining the first rolling wheel either in its first position or in its second position.

[0019] According to a fourth aspect, the invention relates to a method of maintaining a rolling mill according to the invention and as mentioned above, this method comprising at least successive steps consisting of: a. cancel the kinematic connection between the actuator and the threaded rod and dismantle the jib equipped with the actuator from the rolling mill frame, with an axial movement parallel to the longitudinal axis of the drive shaft; b. dismantle at least one rolling wheel from the drive shaft in place on the rolling mill frame or dismantle the drive shaft equipped with the two rolling wheels from the frame; c. fit at least one new rolling wheel to the drive shaft in place on the chassis or a drive shaft fitted with two rolling wheels to the chassis; d. remount the stem equipped with the actuator on the chassis; and e. reconstituting the kinematic connection between the actuator and the threaded rod, by moving a drive member of the threaded rod towards the first and second rolling wheels, with an axial movement parallel to the longitudinal axis of the drive shaft.

[0020] The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment of a rolling tool, a circular rolling mill and associated methods, given solely by way of example and with reference to the appended drawings in which: - [Fig.l] [Fig.l] is a principle perspective view of a rolling mill according to the invention, in a first configuration before rolling; - [Fig.2] [Fig.2] is a longitudinal section of the rolling mill of [Fig.l], in a second rolling configuration; - [Fig.3] [Fig.3] is an exploded perspective view of a rolling cassette according to the invention, belonging to the rolling mill of figures 1 and 2; - [Fig.4] [Fig.4] is a longitudinal section of the cassette of [Fig.3] in a first configuration of use; - [Fig.5] [Fig.5] is a section along line VV in [Fig.4]; - [Fig.6] [Fig.6] is a perspective section, with partial section, of the cassette in the configuration of figures 4 and 5; - [Fig.7] [Fig.7] is a view similar to [Fig.4], when the cassette is in a second configuration of use, corresponding to the rolling configuration of the rolling mill shown in [Fig.2]; - [Fig.8] [Fig.8] is a section along line VIII-VIII in [Fig.7]; - [Fig.9] [Fig.9] is a perspective view, with partial section, of the cassette in the configuration of Figures 7 and 8; and - [Fig. 10] [Fig. 10] is a perspective view, from another angle, of the cassette of figures 3 to 9 during a rolling mill maintenance operation.

[0021] The circular rolling mill 1 shown in Figures 1 and 2 comprises a main frame 2 on which is mounted a radial cage 3, fixed relative to the frame 2. X2 denotes a longitudinal axis of the frame 2. An axial cage 4 is also mounted on the frame and movable along the longitudinal axis X2, between a position spaced from the radial cage 3, shown in [Fig.l], and a position close to this cage, shown in [Fig.2].

[0022] The radial stand 3 comprises a rolling cassette 10, also identified as a “cassette” or “external rolling tool” in the following. The cassette 10 is rotatably mounted about a vertical axis Z10 defined by the radial stand 3 and driven in rotation, about the axis Z10, by a main electric motor 11.

[0023] The radial cage 3 also comprises a mandrel 12, also identified as an “internal rolling tool” in the following, mounted to rotate about an axis Z12 defined by the radial cage 3 and parallel to the axis Z10.

[0024] In the rolling configuration of a part to be rolled 100, the cassette 10 is arranged radially outside this part, while the mandrel 12 is arranged radially inside it, as shown in FIGS. 2, 4 and 7.

[0025] The mandrel 12 is mounted in a vertical support 13 which is movable, relative to a main part 31 of the radial cage 3, parallel to the longitudinal axis X2. The vertical support 13 is supported by two columns, one of which is visible in [Fig. 1] with the reference 14, these columns being able to slide relative to the part 31 to move the vertical support 13 parallel to the axis X2. The radial cage 3 also comprises a horizontal support 16 which defines a housing 17 for receiving the lower end of the mandrel 12 when the vertical support 13 and the horizontal support 16 are aligned vertically, that is to say when the axis Z12 passes through the center of the housing 17. It is then in fact possible to lower the mandrel 12 to partially engage it in the part to be rolled 100 and in the housing 17.

[0026] The rolling mill 1 also comprises a lower conical roller 20 supported by the axial cage 4 and driven in rotation by an electric motor 21. The axial cage 4 also supports an upper conical roller 22 driven in rotation by an electric motor 23. The axes of symmetry and rotation of the rollers 20 and 22 are denoted A20 and A22 respectively. These axes are inclined relative to the horizontal and the vertical and converge as they approach the radial cage 3.

[0027] When the rolling part 100 is in place in the rolling mill 1, as shown in [Fig.2] and partially in figures 4 and 7, this part 100 is subjected to radial compression forces F1 and F2 exerted respectively by the external and internal rolling tools, 10 and 12, and to axial compression forces not shown exerted by the lower and upper conical rollers, 20 and 22. The radial compression forces F1 and F2 make it possible to shape respectively the external radial face 101 and the internal radial face 102 of the part to be rolled 100. The intensity of the radial compression forces F1 and F2 depends on the intensity of two tensile forces exerted respectively on the vertical support 13 and on the horizontal support 16, parallel to the longitudinal axis X2.

[0028] The cassette 10 comprises a drive shaft 120 rotatably mounted in a lower bearing 32 supported by a lower bracket 33, itself mounted on a partition 34 which belongs to the main part 31 of the radial cage 3.

[0029] The drive shaft 120 is also rotatably mounted in an upper bearing 36 supported by an upper bracket 38, itself removably mounted on the partition 34.

[0030] A120 is a longitudinal axis of the drive shaft 120, the axis A120 is aligned with the vertical axis Z10 in the mounted configuration of the casette 10 in the rolling mill 1.

[0031] The shaft 120 is equipped with a toothing 122 which cooperates with an internal toothing not shown of a hollow shaft 112, driven in rotation around the axis Z10 by the main motor 11. Thus, the main motor 11 drives the drive shaft 120 in rotation around the vertical axis of rotation Z10,

[0032] The drive shaft 120 is equipped with an oblong slot 124, the largest dimension of which is parallel to the longitudinal axis A120 and in which is arranged a central bar 140, movable parallel to the longitudinal axis A120 in the oblong slot 124. The central bar 140 is immobilized in rotation about the longitudinal axis A120 by cooperation of shapes with the oblong slot 124.

[0033] The drive shaft 120 also comprises two notches 126 in each of which is arranged a key 150 of elongated shape, the largest dimension of which is parallel to the longitudinal axis A120.

[0034] The cassette 10 comprises a first rolling wheel 160 and a second rolling wheel 170, movable relative to each other along the longitudinal axis A120.

[0035] The first rolling wheel 160 is circular in shape, centered on an axis A160 which is aligned with the axis A120 in the mounted configuration of the first rolling wheel 160 in the cassette 10. The first rolling wheel 160 defines a first rolling surface S160 which is circular, centered on the axis A160 and, in the example of the figures, with a rectilinear generatrix.

[0036] In a variant of the invention not shown, the generator of the surface S160 is not rectilinear.

[0037] The first rolling wheel 160 comprises an annular skirt 162 and an annular flange 164 which are secured by screws 165.

[0038] The second rolling wheel 170 is also annular in shape and centered on an axis A170 aligned with the axis A120 in the mounted configuration of the second rolling wheel 160 in the cassette 10. The second rolling wheel 170 comprises a ring 172, advantageously in one piece, which defines a second rolling surface S170 which is circular and centered on the axis A170. Advantageously, the surface S170 has a left-hand generatrix and defines a channel C170.

[0039] In a variant of the invention not shown, the second rolling surface S170 may have another geometry, for example having a bead or having a rectilinear generatrix.

[0040] The ring 172 has, on its internal radial surface, two notches 174, only one of which is visible in [Fig. 3], which are diametrically opposite relative to the axis A170 and which are provided to each receive one of the keys 150. This makes it possible to secure in rotation, around the axes Z10, A120 and A170 combined, the second rolling wheel 170 and the drive shaft 120. Thus, a rotational movement RI 1 of the hollow shaft 112 is transmitted by the drive shaft 120 to the second rolling wheel 170 by the cooperation of the keys 150 and the notches 174.

[0041] Alternatively, the number of notches 126 and 174 and the number of keys 150 are different from two, for example equal to one, to three or more.

[0042] Advantageously, the keys 150 are housed, radially to the longitudinal axis A120, between the drive shaft 120 and the second rolling wheel 170. The keys 150 and the notches 126 and 174 are thus protected from pollution.

[0043] The second rolling wheel 170 carries two secondary keys 176 which are intended to engage in two housings 166 provided on the annular flange 164 of the first rolling wheel 160, on the side of the second guide wheel 170.

[0044] When the secondary keys 176 are engaged in the housings 166, they allow a rotational movement to be transmitted from the second rolling wheel 170 to the first rolling wheel 160.

[0045] Alternatively, the number of housings 166 and the number of keys 176 are different from two, for example equal to one, to three or more.

[0046] Advantageously, the keys 176 are housed, axially along the longitudinal axis A120, between the first and second rolling wheels 160 and 170. The keys 150 and the notches 126 and 174 are thus protected from pollution when the first rolling wheel is in the position of FIGS. 4 to 6. Furthermore, these housings and notches do not reduce the area of ​​the rolling surfaces S160 and S170.

[0047] The cassette 10 also comprises two end bars 142 and 144 which are secured, in rotation and in translation relative to the longitudinal axis A120, to the central bar 140.

[0048] The bars 140, 142 and 144 together constitute a connecting bar 146 which makes it possible to guide the first guide wheel 160 in translation along the longitudinal axis A120 when the central bar 140 moves in the oblong slot 124.

[0049] Advantageously, the end bars 142 and 144 are secured to the flange 164 by means of screws 145. Through the end bars 142 and 144, the central bar 140 is also secured to the flange 164, therefore to the first rolling wheel 160.

[0050] The drive shaft 120 is hollow and defines a stepped central housing L120. In the example of the figures, the stepped central housing L120 extends above and below the lumen 124.

[0051] A threaded rod 180 is arranged in the housing 120 while being aligned with the longitudinal axis A120. It extends between an upper end 127 of the drive shaft 120 and the connecting bar 146 into which it is screwed. More particularly, the threaded rod is screwed into a thread of the central bar 140 which is aligned with the longitudinal axis A120. Thus, the central bar 140 forms a captive nut in the slot 124.

[0052] In the vicinity of the upper end 127, a bearing 182 supports the threaded rod 180 in the housing L120 and in the light 124, without contact with the drive shaft 120.

[0053] The connection between the threaded rod 180 and the central bar 140 is a screw-nut type connection. Thus, a rotational movement of the threaded rod 180 around the longitudinal axis A120 of the drive shaft 120 induces a movement of the central bar 140 in the slot 124, parallel to this longitudinal axis.

[0054] This vertical movement of the central bar 140 is transmitted to the other parts of the connecting bar 146 and, by the same token, to the first rolling wheel 160.

[0055] The upper end 184 of the threaded rod 180 is of polygonal shape. More generally, this end can be of any shape allowing the transmission of a torque.

[0056] An electric motor 200 mounted on a coupling 202 supported by the upper bracket 38 rotates, around the vertical axis Z10, a coupling nut 204 configured to transmit a torque, around the vertical axis Z10, to the upper end 184 of the threaded rod 180.

[0057] Thus, an electronic control unit 206 which controls the electric motor 200 makes it possible to control the rotation of the threaded rod 180 and, due to the screw-nut connection between the parts 180 and 146, the vertical displacement of the first guide wheel 160 relative to the rest of the cassette 10, in particular relative to the drive shaft 120 and to the second guide wheel 170.

[0058] For the sake of clarity of the drawing, the electronic control unit 206 is shown only in [Fig. 3]. This control unit may be part of a control unit of the rolling mill 1, a software brick of a control controller of the rolling mill 1 or a control unit dedicated to the function of controlling the electric motor 200.

[0059] The cassette 10 also comprises a primary retaining sleeve 210 which is engaged in a plain bearing 168 formed by the flange 164.

[0060] The primary holding sleeve 210 defines a stop 212 on which a portion 214 of a telescopic cover 216 bears. A retaining ring 218 is mounted in a groove 128 of the drive shaft 120 and makes it possible to hold the upper part of the telescopic cover 216 and the primary sleeve 210 in position relative to the drive shaft 120 and to limit the upward travel of the primary wheel 170. A lower edge of the telescopic cover 216 bears on the top of the flange 164.

[0061] The telescopic cover makes it possible to isolate the primary holding sleeve 210, the notches 126 and the keys 150 from the outside, which limits the risks of pollution of the cassette 10 in this zone and of jamming of the first rolling wheel along the drive shaft 120.

[0062] The crew 202 is mounted on springs relative to the upper bracket 38. Springs integrated into the columns of the coupling 202 are visible, by partial tearing, in figures 4 and 5, respectively with the references 220 and 222.

[0063] A clamping mechanism 224 makes it possible to push the coupling 202, therefore the coupling nut 204, towards the lower bearing 32, against the elastic force exerted by the springs 220 and 222, which makes it possible to adjust the axial position of the coupling nut 204 relative to the upper end 184 of the threaded rod 180.

[0064] The electric motor 200 constitutes an actuator which is integrated into a displacement device 230, this displacement device also comprising the coupling 202, the coupling nut 204, and the clamping mechanism 224.

[0065] As is apparent from the comparison of Figures 4 to 6, on the one hand, and Figures 7 to 9, on the other hand, the displacement device 230 makes it possible to move longitudinally, along the axis A120, the first rolling wheel 160 between a first position shown in Figures 4 and 6, in which the first rolling surface S160 radially surrounds the second rolling surface S170, and a second position shown in Figures 7 to 9, in which the first and second rolling surfaces S160 and S170 are offset relative to each other along the axis Ion- gitudinal A120.

[0066] By "offset" is meant that, in the second position of the first rolling wheel 160, the radial projections on the longitudinal axis A120 of the first and second rolling surfaces S160 and S170 do not have a common area.

[0067] Advantageously, in the first position shown in Figures 4 to 6, the first rolling wheel 160 covers the second rolling wheel 170, whereas in the second position shown in Figures 7 to 9, the first rolling wheel S160 is offset vertically upwards, along the longitudinal axis A120, relative to the second rolling wheel 170.

[0068] This makes it possible to successively use, during a rolling range, the surfaces S160 and S170 to shape the external radial face 101 of the part to be rolled 100, without having to vertically move the entire external cassette 10 since the drive shaft 120, the second rolling wheel 170, the threaded rod 180 and the displacement device 230 remain in position, along the axes A120 and Z10 combined, relative to the main part 31 of the radial cage 3 in the two configurations shown respectively in FIGS. 4 to 6 and in FIGS. 7 to 9.

[0069] The bearings 32 and 36 can therefore be conventional bearings, in the example roller bearings, without having to be compatible with axial movements of the drive shaft 120. The same applies to the hollow shaft 112 which does not have to follow vertical movements of the drive shaft, which have no place.

[0070] Thus, according to an advantageous but not obligatory aspect of the invention, subject to the arrangement of the partition 34 so as not to interfere with the first rolling wheel 160 in its two positions, the cassette 10 can be mounted on a rolling mill which was not originally intended for a cassette with two rolling surfaces. In other words, the cassette 10 makes it possible to retrofit an existing rolling mill to add the possibility of successively using the two rolling surfaces S160 and S170, without having to dismantle the cassette 10 with respect to the radial stand 3 of the rolling mill 1.

[0071] The telescopic nature of the cover 216 allows it to follow the movements of the first rolling wheel 160 relative to the second rolling wheel 170 to move from the first position shown in Figures 4 to 6 to the second position shown in Figures 7 to 9, and vice versa.

[0072] In practice, the electric motor 200 and the screw-nut connection constituted by the parts 140 and 180 make it possible to move the first rolling wheel 160 between its two positions respectively shown in Figures 4 to 6 and 7 to 9 in a few seconds, for example approximately 5 seconds. This makes it possible to chain the rolling operations at a sustained rate in the circular rolling mill 1.

[0073] Considering the mass and the relatively low inertia of the first wheel of rolling 160 relative to the entire cassette 10, the electric motor 200 is sized to develop a relatively low force compared to a hydraulic cylinder which would have to move the entire cassette in height, as in the prior art. This allows a saving of space and a reduction in the cost price for the circular rolling mill 1.

[0074] In the first configuration of the cassette 10 shown in Figures 4 to 6, the central bar 140 is pushed by the screw-nut connection constituted by the elements 180 and 140 into the low position in the slot 124, while the end bars 142 and 144 are respectively received in two notches 178 and 179 formed in the upper part of the ring 172, that is to say on the side of the ring 172 oriented towards the flange 164.

[0075] In the second configuration of the cassette 10 shown in Figures 7 to 9, a lower edge 163 of the skirt 162, which is arranged opposite the skirt 162 relative to the flange 164, radially surrounds an upper heel 173 of the ring 172. This makes it possible to ensure good centering of the first rolling wheel 160 on the second rolling wheel 170, including in the second position of the first rolling wheel shown in Figures 7 to 9

[0076] It is apparent from the comparison of Figures 4 and 7 that, depending on the rolling surface S160 or S170 in use, the geometry of the mandrel 12 can be adapted. Advantageously, a first mandrel 12 is used when the cassette 10 is in the configuration of Figures 4 to 6, where the first rolling wheel 160 is in its first position. A second mandrel 12' is used when the cassette 10 is in the configuration of Figures 7 to 9, where the second rolling surface S170 is used, while the first rolling wheel 160 is in its second position.

[0077] The second mandrel 12' differs from the first mandrel 12 in that it comprises a widened portion which has a bead B12 of a shape generally complementary to that of the channel C170 of the second rolling surface S170.

[0078] During a rolling process of the annular part 100 by means of the rolling mill 1, the radial faces 101 and 102 of the annular part 100 are first shaped by means of the cassette 10 and the mandrel 12, while the first and second rolling wheels 160 and 170 are in their first configuration, in which the first rolling surface S160 is opposite the external radial face 101 of the part to be rolled 100 and exerts thereon the axial compressive force FL

[0079] At the end of this step, the mandrel 12 is moved away from the part to be rolled 100 and removed, then replaced by the second mandrel 12'.

[0080] Concomitantly or in a time-shifted manner relative to the change of the internal rolling tool 12, the first rolling wheel 160 is moved longitudinally, along the drive shaft 120, which brings this first rolling wheel rolling in its second position of figures 7 to 9, that is to say in a configuration where the second rolling surface S170 of the second rolling wheel 170 is opposite the external radial face 101 of the part to be rolled 100 and can come directly into contact with this radial face. This axial displacement of the first rolling wheel 160 takes place without axial displacement of the drive shaft 120, nor of the second rolling wheel 170.

[0081] In a following step, the external radial faces 101 and internal 102 of the annular part 100 are shaped by means of the cassette 10 and the mandrel 12', while the first and second rolling wheels 160 and 170 are in their second configuration shown in FIGS. 7 to 9. In this configuration, the second rolling surface S170 is opposite the external radial face 101 of the part to be rolled 100 and exerts on it the axial compressive force F1.

[0082] According to a variant of the invention not shown, the two shaping steps mentioned above can be reversed, in the sense that the first shaping step is carried out by means of the second rolling surface S170 of the second rolling wheel 170, while the second shaping step is carried out by means of the first rolling surface S160 of the first rolling wheel 160. In this case, the geometry of the rolling surfaces is advantageously adapted, the second rolling surface S170 being used for roughing, while the first rolling surface S160 is used for finishing the external radial face 101.

[0083] When the first guide wheel 160 is in its first position, it should be kept pressed against the second guide wheel 170, so that the secondary keys 176 remain engaged in the housings 166, in order to guarantee efficient driving of the first guide wheel 160 by the second guide wheel 170 and axial positioning, along the vertical axis Z10, stable over time of the first rolling wheel.

[0084] In order to ensure that the connecting bar 146 does not oscillate vertically in the oblong slot 124, the rotation speed of the worm screw 180 must be synchronized with the rotation speed of the shaft 120 around the rotation axis Z10. In this case, the actuator formed by the electric motor 200 is speed-controlled by the electronic control unit 206, with a rotation speed similar to that of the drive shaft 120 and a limited torque.

[0085] Because the electric motor 200 is speed-controlled with a limited torque, this motor becomes a follower when it reaches its torque limit, even if it is driven at a speed different from its set speed.

[0086] To ensure that the first guide wheel 160 maintains its first position or its second position during rolling, the speed control of the motor 200 by the control unit 206 is carried out by providing a speed difference between the rotation speed of the threaded rod 180 and rotation speed of the drive shaft 120 around the vertical axis Z10.

[0087] More precisely, when the drive shaft 120 is rotated around the vertical axis Z10 with a given rotation speed and when it is appropriate for the first rolling wheel to be in its first position shown in FIGS. 4 to 6, the actuator formed by the electric motor 200 is controlled by the electronic control unit 206 to drive the threaded rod with a rotation speed close to but different from the rotation speed of the drive shaft 120, in particular slightly higher. This overspeed of rotation of the threaded rod has the effect that the screw-nut connection made between the parts 140 and 180 tends to press the central bar 140 against the lower end of the oblong slot 124 and the end bars 142 and 144 respectively in the notches 178 and 179. This ensures that the first rolling wheel 160 is held in axial position against the second rolling wheel 170.

[0088] Conversely, when the first rolling wheel 160 must be in its second position shown in Figures 7 to 9 during a rolling step, the actuator formed by the electric motor 200 is controlled by the electronic control unit 206 with a rotation speed close to but different from the rotation speed of the drive shaft 120, with a direction of difference opposite to that mentioned previously, for example slightly lower. This lower rotation speed of the threaded rod has the effect of pressing the central bar 140 against the upper end of the oblong slot 124 and of ensuring that the skirt 162 does not risk descending towards the lower bracket 33, to the point that it could partially or totally mask the second rolling surface S170.

[0089] Thus, by acting on a difference between, on the one hand, the speed of rotation of the drive shaft 120 around the vertical axis Z10 and, on the other hand, the speed of rotation of the threaded rod 180 around this same axis Z10, it is possible to guarantee that the first rolling wheel 160 is held in its first position shown in Figures 4 to 6 or in its second position shown in Figures 7 to 9.

[0090] Advantageously, in both configurations, the difference between the rotation speeds of the threaded rod 180 and the drive shaft 120 is between 1 and 5% of the nominal rotation speed of the drive shaft 120. This applies to the case of the overspeed mentioned for the first position and to the case of the underspeed mentioned for the second position of the first rolling wheel.

[0091] Depending on the direction of the thread of the threaded rod 180 and the tapping thread of the central bar 160, an overspeed or an underspeed is used in the first configuration of Figures 4 to 6, while an underspeed or an overspeed is used in the second configuration of Figures 7 to 9. The speed difference is in the opposite direction between these two configurations.

[0092] When it is necessary to carry out a maintenance operation on the rolling mill 1, during which the rolling surfaces must be exchanged, the first step is to dismantle the displacement device 230. This is done by operating the clamping mechanism 224 in a loosening direction, which has the effect of axially separating the coupling nut 204 from the end 184 of the threaded rod parallel to the longitudinal axis A120 and the vertical axis Z10, as shown by the arrow F230 in [Fig. 10], and to cancel the kinematic connection between the actuator formed by the electric motor 200 and the threaded rod 180. Then, the bracket 38 equipped with the electric motor 200 is dismantled with respect to the partition 34, that is to say with respect to the frame 2 of the rolling mill 1, this with an axial movement, represented by the arrow F38 in [Fig. 10] and parallel to the axes A120 and Z10.

[0093] It is then possible to disengage the two rolling wheels 160 and 170 from the drive shaft 120 which remains held in place relative to the chassis 2, by the lower bearing 32 and the lower bracket 33, by lifting and sliding these wheels along the drive shaft, along the vertical axis Z10. During this removal of the rolling wheels, the drive shaft is not offset along the rotation axis Z10.

[0094] New rolling wheels can then be installed on the drive shaft 120 in place of those which have just been removed, by sliding them downwards along the drive shaft 120. These new rolling wheels advantageously have rolling surfaces of different geometries from those of the rolling surfaces S160 and S170.

[0095] Alternatively, only one of the rolling wheels 160 or 170 is changed during the maintenance operation.

[0096] It is then possible to reassemble the upper bracket 38 equipped with the electric motor 200 on the partition 34, therefore on the chassis 2. The springs 220 and 222 make it possible to adapt the height position of the displacement device 230 relative to that of the upper end 184 of the threaded rod 180, before the operation of the clamping mechanism 224, without risk of damaging the upper end 184 of the threaded rod 180.

[0097] Then, the kinematic connection between the actuator formed by the electric motor 200 and the upper end 184 of the threaded rod 180 is reconstituted by lowering the coupling nut 204, that is to say by moving it in the direction of the first and second rolling wheels, with an axial movement parallel to the longitudinal axis A120, in the opposite direction to the arrow F230. This lowering movement of the electric motor 200 takes place by maneuvering the clamping mechanism 224 against the elastic force of the springs 220 and 222.

[0098] In this respect, the springs 220 and 222 allow a progressiveness of the kinematic coupling between the actuator formed by the electric motor 200 and the threaded rod 180 and limit the risks of crushing the hand or fingers of an operator when reassembling the cassette 10.

[0099] In a variant of the invention not shown, the disassembly and / or reassembly of the upper part of the cassette 10 can take place in two stages: the displacement device 230 is removed before the upper bracket 38 and / or the bracket is replaced on the partition 34 before the displacement device 230 is reassembled on this bracket.

[0100] In a variant of the invention not shown, during a maintenance operation of the rolling mill 1, the drive shaft 120, the lower bracket 33, the upper bracket 38 and the displacement device 230 are dismantled relative to the chassis 2 at the same time as the rolling wheels 160 and 170, then a new cassette, comprising a new drive shaft, two new rolling wheels, a new lower bracket, a new upper bracket and a new displacement device is put in place on the partition 34, which reduces the time taken to change the cassette 10.

[0101] According to another variant of the invention, not shown, the actuator is not constituted by an electric motor of the type of motor 200 but by a hydraulic motor or by a brake clutch which makes it possible to immobilize the threaded rod 180 either in relation to the drive shaft 120, or in relation to the fixed structure of the rolling mill 1, that is to say in relation to the chassis 2.

[0102] According to another variant of the invention, not shown, the movement of the first rolling wheel between its first position, where it is opposite the external face of the part to be rolled, and its second position, where it is axially offset relative to this external face, can take place downwards and not upwards as shown in the figures.

[0103] According to another variant of the invention not shown, the connection between the actuator and the first rolling wheel is of a type other than screw-nut, for example pinion-rack or by jack(s).

[0104] Changing the mandrel 12 when switching from the use of the first rolling wheel 160 to the second rolling wheel 170 is not mandatory. In other words, the same mandrel 12 can be used with both rolling wheels 160 and 170. For example, this same mandrel 12 can have two superimposed zones intended to bear against the internal radial face 102 of the part to be rolled 100. In this case, the jack 12 is moved in height when the rolling surface used changes from the first rolling surface S160 to the second rolling surface S170, or vice versa. Furthermore, it is not mandatory to use two zones distinct from the single mandrel 12 to shape the internal radial face 102 of the part to be rolled 100. The same area of ​​this mandrel can be used in conjunction with the first and second rolling surfaces S160 and S170.

[0105] The figures represent the case where the external rolling tool, namely the external cassette 10, is in accordance with the invention. In a variant not shown or in addition, it is the mandrel 12, namely the internal rolling tool, which is in accordance with the invention. In this case, it is not necessary to change from the mandrel 12 to the mandrel 12', or to move the complete mandrel 12 in height, between the two rolling steps respectively shown in Figures 4 and 7.

[0106] According to another variant of the invention, not shown, the transmission of torque between the coupling nut 204 and the endless screw 180 can take place by one or more key(s) or by grooves provided on the end 184.

[0107] All the features and all the variants mentioned above can be combined with each other, as far as this is technically possible.

Claims

Claims

1. Rolling tool (10) for a circular rolling mill (1) comprising - a drive shaft (120) configured to be rotated about an axis of rotation (Z 10); - a first rolling wheel (160) integral with the drive shaft, rotating about the axis of rotation, and defining a first rolling surface (S 160) configured to shape a radial face (101) of a part to be rolled (100); and - a second rolling wheel (170) defining a second rolling surface (S 170) configured to shape the radial face of the part to be rolled, characterized in that the first and second rolling wheels (160, 170) are movable relative to each other, parallel to a longitudinal axis (A 120) of the drive shaft, between - a first configuration, in which the first rolling surface (S 160) radially surrounds the second rolling surface (S 170);and - a second configuration, in which the first and second rolling surfaces (S 160, 170) are offset from each other, along the longitudinal axis (A120).;

2. Rolling tool according to claim 1, comprising a device for moving (230) the first rolling wheel (160) parallel to the longitudinal axis (A120), between a first position in which the first rolling wheel covers the second rolling wheel (170) and a second position in which the first rolling wheel is offset, along the longitudinal axis, relative to the second rolling wheel.

3. Rolling tool according to claim 2, wherein the displacement device (230) comprises an actuator (200) and a screw / nut connection between a threaded rod (180) driven in rotation by the actuator and a nut (140) secured to the first rolling wheel (160).

4. Rolling tool according to one of the preceding claims, in wherein the second rolling wheel (170) is secured to the drive shaft (120), rotating about the axis of rotation (Z10), by means of at least one first key (150) housed radially between the drive shaft (120) and the second rolling wheel (170) and, in the first configuration, the first rolling wheel (160) is secured to the second rolling wheel (170), rotating about the axis of rotation, by means of at least one second key (176) housed axially between the first and second rolling wheels.

5. Circular rolling mill for shaping annular parts comprising a pair of rolling tools (10, 12), respectively internal and external, configured to shape internal and external radial faces (101, 102) of a part to be rolled (100) and a pair of conical rollers (20, 22), respectively lower and upper, configured to shape front faces of the part, characterized in that at least one of the rolling tools is according to one of the preceding claims.

6. Rolling mill according to the preceding claim, in which the rolling tool is according to claim 3, the actuator (200) is mounted on a bracket (38), itself mounted in a removable manner on a frame (34) of the rolling mill (1) and a kinematic connection between the actuator and the threaded rod (180) is active or not depending on whether the bracket is mounted or not on the frame.

7. Rolling mill according to one of claims 5 and 6, in which the first and second rolling wheels (160, 170) are removably mounted on the drive shaft and can be disengaged from this drive shaft while the latter remains in place in the rolling mill (1) being supported by the frame (2).

8. A method of rolling an annular part (100) by means of a rolling mill (1) according to one of claims 5 to 7 comprising at least successive steps consisting of: a. shaping radial faces (101, 102) of the annular part by means of the internal and external rolling tools (10, 12), while the first and second rolling wheels (160, 170) are in their first configuration; b. moving the first rolling wheel (160) relative to the drive shaft, so as to bring the first and second rolling wheels (160, 170) into their second configuration, without shifting the drive shaft (120) along the axis of rotation (Zl); c. shaping the radial faces (101, 102) of the annular part (100) by means of the internal and external rolling tools (10, 12), while the first and second rolling wheels (160, 170) are in their second configuration.

9. A method according to claim 8, implemented with a rolling mill (1) in which the rolling tool (10) is according to claim 3, wherein the actuator (200) is controlled to deliver a limited torque and drive the worm screw (180) with a rotational speed higher or lower than the rotational speed of the drive shaft (120), maintaining the first rolling wheel (160) either in its first position or in its second position.

10. Method of maintaining a rolling mill according to claim 6, comprising at least successive steps consisting of: a. cancel the kinematic connection between the actuator (200) and the threaded rod (180) and dismantle the bracket (38) equipped with the actuator relative to the frame (2) of the rolling mill, with an axial movement (F38) parallel to the longitudinal axis (A120) of the drive shaft; b. dismounting at least one rolling wheel (160, 170) from the drive shaft (120) in place on the frame (2) of the rolling mill (1) or dismounting the drive shaft (120) equipped with the two rolling wheels (160, 170) from the frame; c. mounting at least one new rolling wheel on the drive shaft (120) in place on the frame (2) or a drive shaft equipped with two rolling wheels on the frame; d. reassemble the bracket (38) equipped with the actuator (200) on the chassis (2); and e. reconstituting the kinematic connection between the actuator and the threaded rod (180), by moving a drive member (204) of the threaded rod towards the first and second rolling wheels (160, 170), with an axial movement parallel to the longitudinal axis (A120) of the drive shaft. 20

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