Circular rolling mill and rolling process using such a rolling mill

Abstract

Circular rolling mill and rolling method using such a rolling mill A circular rolling mill (1) comprises a main frame (2), a radial stand (3) and at least one axial stand (4). The radial stand comprises a roller (10) and a mandrel. The axial stand comprises an auxiliary frame (60) and tapered rollers. The mandrel is supported by an upper mandrel holder (22) and selectively engaged in a lower mandrel holder (32). Each mandrel holder is integral, in translation along a longitudinal axis (X2) of the main frame, with at least one drive bar (24, 26, 34, 36) parallel to the longitudinal axis. The movement of the mandrel holders (22, 32) is controlled by a movement system (40) arranged on the same side of the shaping roller (10) as the mandrel. The auxiliary chassis (60) slides, along the longitudinal axis, on the drive bars, which pass right through it.A mechanism (70) moves the auxiliary chassis (60) relative to the drive bars (24, 26, 34, 36), in translation parallel to the longitudinal axis (X2). Figure for abstract: Fig 2.

Description

Title of the invention: Circular rolling mill and rolling method using such a rolling mill

[0001] The present invention relates to a circular rolling mill equipped, among other things, with a shaping roller and a shaping mandrel making it possible, within a radial stand, to shape respectively external and internal radial faces of a part to be rolled.

[0002] In the field of rolling, WO2009 / 125102A1 discloses a rolling mill which comprises a radial stand and an axial stand. The radial stand itself comprises a roll for shaping an external radial face of a part to be rolled and a mandrel for shaping an internal radial face of this part. The axial stand comprises, for its part, an auxiliary frame and lower and upper conical rolls for shaping the lower and upper radial faces of the part to be rolled. The movement of the mandrel relative to the roll for shaping the external radial face of the part to be rolled is controlled by a drive assembly located opposite the mandrel with respect to this shaping roll. The axial stand is, for its part, arranged opposite these drive means, that is to say on the same side as the mandrel with respect to the shaping roll. This makes this rolling mill relatively bulky.

[0003] On the other hand, to improve production rates, it is known to equip a circular rolling mill with two axial stands, each associated with one of two mandrels of the radial stand and arranged on either side of the shaping roll of the external radial face of the parts to be rolled. Such a rolling mill with two opposed axial stands is sometimes called "MIRA". While it makes it possible to increase production rates, such a rolling mill has the disadvantage that the diameter of the rolled parts is limited by the horizontal length of the tapered rollers of each of the axial stands. Indeed, as rolling progresses, the diameter of the rolled part increases to the point that it can reach the edge of the tapered rollers opposite the adjacent mandrel. If the diameter of the part being rolled increases further, then it escapes the tapered rollers of the axial stand.The part can no longer be rolled, which can lead to defects or even the scrapping of the part in question.

[0004] It is these drawbacks that the invention more particularly intends to remedy by proposing a new circular rolling mill which is compact and which makes it possible to roll parts of relatively large diameter.

[0005] To this end, the invention relates to a circular rolling mill for shaping annular parts, comprising a main frame, a radial stand and at least one axial cage, the radial cage comprising a roller for shaping an external radial face of a part to be rolled and a mandrel for shaping an internal radial face of the part to be rolled, the axial cage comprising an auxiliary frame and lower and upper conical rollers for shaping the lower and upper radial faces of the part to be rolled, the mandrel being supported by an upper mandrel holder and selectively engaged in a lower mandrel holder, each of the mandrel holders being integral, in translation along a longitudinal axis of the main frame, with at least one drive bar parallel to the longitudinal axis of the main frame.

[0006] According to the invention, the movement of the mandrel holders parallel to the longitudinal axis of the main frame is controlled by a movement system arranged on the same side of the shaping roller as the mandrel. The auxiliary frame is slidably mounted, parallel to the longitudinal axis of the main frame, on the drive bars of the mandrel holders, which pass right through it. In addition, the circular rolling mill comprises a mechanism for translational movement of the auxiliary frame relative to the drive bars, parallel to the longitudinal axis of the main frame.

[0007] Thanks to the invention, the position of the mandrel, and therefore the intensity of the force that it exerts on the internal radial face of the part to be rolled, can be controlled by means of the drive bars secured to the mandrel holders. Furthermore, the conical rollers, which are carried by the auxiliary frame of the axial stand, can be moved in translation, in a direction radial to the axis of rotation of the shaping roller of the external face of the part to be rolled, independently of the mandrel, while it exerts a shaping force on the internal radial face of this part. It is thus possible to adjust the longitudinal position of the conical rollers of the axial stand, as a function of the actual diameter of the part, during rolling.

[0008] According to advantageous but not mandatory aspects of the invention, such a circular rolling mill may incorporate one or more of the following features, taken in any technically admissible combination:

[0009] - A system for moving the drive bars is mounted on the chassis main, on the side of the auxiliary frame opposite the chuck holders; the drive bars extend between the movement system and the chuck holders and the auxiliary frame is provided with openings for the passage of the drive bars and for guiding the movements of the auxiliary frame on these drive bars.

[0010] - Each chuck holder is secured to two drive bars, distributed on either side and on the other side of a median longitudinal plane of the rolling mill, and the displacement mechanism synchronizes the displacement of the auxiliary frame along the two drive bars of one of the mandrel holders.

[0011] - The drive bars with respect to which the syn displacement mechanism chronos the movement of the auxiliary frame are integral with the lower chuck holder.

[0012] - The movement mechanism comprises a frame mounted on the two bars drive and immobilized, in translation along the longitudinal axis of the main chassis, on these two drive bars, as well as drive members of the auxiliary chassis along the drive bars, relative to the frame.

[0013] - The frame is provided with two holes for the passage of the longitudinal bars on which it is mounted and immobilized.

[0014] - The frame supports a motor for moving the auxiliary chassis along the bars drive and movement transmission components between the engine and the auxiliary chassis.

[0015] - The movement transmission members comprise a belt and two parts of ball screw systems, one belt and two parts of nut and worm systems or two parts of rack and pinion systems.

[0016] - The frame carries at least one cylinder for moving the frame and the chassis apart / closer auxiliary parallel to the longitudinal axis of the main chassis.

[0017] - An axial cage and a mandrel are provided on each side of the roller of conformation, along the longitudinal axis of the main frame, the auxiliary frame of each radial stand is slidably mounted, parallel to the longitudinal axis of the main frame, on the drive bars of the mandrel holders located on the same side, which pass right through it; and the circular rolling mill comprises two mechanisms for translational movement of the auxiliary frames relative to the drive bars, parallel to the longitudinal axis of the main frame.

[0018] According to another aspect, the invention relates to a method of rolling an annular part by means of a rolling mill according to one of the preceding claims comprising at least steps consisting of:

[0019] a) shaping the outer and inner radial faces of the annular part, by means of the shaping roller and the mandrel, and the lower and upper axial faces, by means of the lower and upper conical rollers; and

[0020] b) adjusting, as a function of a diameter of the annular part being rolled, a distance between the mandrel and a rear edge of the conical rollers by actuating the movement mechanism of the auxiliary frame along the drive bars.

[0021] The method of the invention makes it possible, by actuating the movement mechanism of the auxiliary frame, to take into account the increase in the diameter of the annular part during rolling.

[0022] The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of two embodiments of a circular rolling mill and a rolling process in accordance with its principle, given solely by way of example and made with reference to the attached drawings in which:

[0023] [Fig-1] [Fig. 1] is a perspective view of the principle of a circular rolling mill according to the invention;

[0024] [Fig.2] [Fig.2] is a perspective section along plane II in [Fig.l];

[0025] [Fig.3] [Fig.3] is a perspective section along plane III in [Fig.l];

[0026] [Fig.4] [Fig.4] is a semi-exploded perspective view of a decoupling mechanism placement of an auxiliary frame belonging to the rolling mill of figures 1 to 3;

[0027] [Fig.5] [Fig.5] is a longitudinal section of the circular rolling mill, in a rolling configuration different from that shown in Figures 1 to 3;

[0028] [Fig.6] [Fig.6] represents, on two inserts A) and B), an enlarged version of box VI in [Fig.5], in first and second rolling configurations, the first configuration being that of [Fig.5];

[0029] [Fig.7] [Fig.7] represents, on two inserts C) and D), partial sections similar to those of [Fig.6], when the rolling mill is in third and fourth rolling configurations;

[0030] [Fig.8] [Fig.8] represents, on two inserts E) and F), partial sections similar to those of [Fig.6], when the rolling mill is in a fifth rolling configuration and after the end of rolling; and

[0031] [Fig.9] [Fig.9] is a view similar to [Fig.1], for a rolling mill according to a second embodiment of the invention.

[0032] The circular rolling mill 1 shown in Figures 1 to 8 comprises a main frame 2 which extends along a longitudinal axis X2.

[0033] The main frame 2 supports a radial cage 3 and an axial cage 4.

[0034] The rolling mill 1 is used to shape a part to be rolled 100 of which we note 101 an outer radial face, 102 an inner radial face, 103 an upper axial face and 104 a lower axial face.

[0035] The radial cage 3 comprises a first roller 10 for shaping the external radial face 101 of the part to be rolled 100, which is rotatably mounted around a vertical axis Z10, defined by a support and drive assembly 12 comprising in particular an electric motor 14. The electric motor 14 is covered by a cover 15. When it is actuated, the electric motor 14 drives the shaping roller in rotation around the axis Z10.

[0036] 10A denotes the external peripheral surface of the shaping roller 10 which comes into contact with the external radial face 101 of the part 100 during rolling.

[0037] The radial cage 3 also comprises a mandrel 20 which constitutes a second shaping roller for the internal radial face 102 of the part to be rolled 100.

[0038] The mandrel 20 is supported by a first mandrel holder 22, or mandrel holder upper, which is mounted at the end of two drive bars 24 and 26. The mandrel holder 22 can also be called a "cradle". The upper mandrel holder 22 carries a mechanism 28 for lowering / raising the mandrel 20 along its longitudinal axis A20, which is vertical in the mounted configuration of the mandrel 20 in the rolling mill 1. The lowering / raising mechanism is controlled by means of two electric motors 30 and 31 mounted on the mandrel holder 22, from which the mandrel 20 extends downwardly.

[0039] The rolling mill 1 also comprises a second mandrel holder 32, or lower mandrel holder, which defines a housing 33 for receiving the lower end of the mandrel 20. The mandrel 20 is selectively engaged in the housing 33, therefore in the lower mandrel holder 32, during the rolling phases, and released from this housing for loading a part to be rolled or unloading a rolled part. The lower mandrel holder 32 is mounted at the end of two drive bars 34 and 36. The mandrel holder 32 can also be called a “cradle”. The lower mandrel holder 32 is equipped with rollers, only one of which is visible in [Fig.2] with the reference 38. The other roller is arranged symmetrically to the one visible, relative to the main chassis 2. The mandrel holder 32 rests, by its rollers 38 and equivalent, on two tracks 52 arranged in the upper part of the main chassis 2.The rollers 38 and equivalent facilitate the movement of the lower mandrel holder 32 along the longitudinal axis X2.

[0040] The drive bars 24, 26, 34 and 36 extend parallel to the longitudinal axis X2 of the chassis 2 and are superimposed two by two, the drive bar 24 being arranged above the drive bar 34, while the drive bar 26 is arranged above the drive bar 36. The drive bars 24 and 26 are at the same horizontal level, as are the drive bars 34 and 36.

[0041] PI denotes a median longitudinal plane of the rolling mill 1 which is vertical, located midway between the sides of the main frame 2 and which includes the longitudinal axis X2. The drive bars 24 and 26 are arranged on either side of the median longitudinal plane PI, preferably symmetrically, while the drive bars 34 and 36 are also arranged on either side of this plane PI, preferably symmetrically.

[0042] The upper and lower mandrel holders 22 and 32 make it possible to maintain the mandrel 20 in a pressed configuration against the internal radial face 102 of the part to be rolled 100 during rolling.

[0043] Each of the drive bars 24, 26, 34 and 36 is movable, parallel to the longitudinal axis X2, by means of a displacement system 40 which comprises a carcass 42, two electric motors 44 and 45 and two angle transmissions 46 and 47, each driven by one of the electric motors 44 and 45. Each angle transmission 46 or 47 drives two pinions 48 arranged on either side of the mean longitudinal plane PI, each meshing with a rack 50 provided on one of the drive bars 24, 26, 34 and 36.

[0044] Thus, the actuation of the electric motor 44 makes it possible to move, parallel to the longitudinal axis X2, the drive bars 24 and 26, therefore the upper mandrel holder 22. On the other hand, the actuation of the electric motor 45 makes it possible to move, parallel to the axis X2, the drive bars 34 and 36, therefore the lower mandrel holder 32. The motors 44 and 45 are synchronized so that the movements of the mandrel holders 22 and 32 are also synchronized. The movement system 40 therefore controls the movement of the mandrel holders 22 and 32 parallel to the longitudinal axis X2.

[0045] In the phases of loading and unloading the part to be rolled / rolled 100 onto or from the rolling mill 1, the mandrel holders 22 and 32 can be desynchronized, in order to facilitate loading and / or unloading.

[0046] The displacement system 40 is arranged, along the longitudinal axis X2, on the same side of the shaping roller 10 as the mandrel 20. In the representation of FIGS. 1 to 3 and 5, the mandrel 20, the mandrel holders 22 and 32 and the drive system 40 are all arranged to the right of the shaping roller 10 and its rotation axis Z10. Thus, the rolling mill 1 is compact.

[0047] When the part to be rolled 100 is in place in the rolling mill 1, as shown in FIGS. 1 to 3 and 5 to 8 E), this part is subjected to radial compression forces F1 and F2, respectively exerted by the shaping roller 10 and by the mandrel 20, on its internal and external radial faces 101 and 102. The intensity of these radial compression forces depends on the intensity of a thrust force exerted on the mandrel holders 22 and 32 by the electric motors 44 and 45, through the drive bars 24, 26, 34 and 36, in the direction of the shaping roller 10.

[0048] The movement of the mandrel holders 22 and 32 by the movement system 40 constitutes a primary movement, within the rolling mill 1, which makes it possible to exert the radial compression forces F1 and F2.

[0049] The axial cage 4 comprises an auxiliary chassis 60 mounted on the main chassis 2 and movable, relative to this chassis, along the longitudinal axis X2.

[0050] The axial cage 4 comprises a lower conical roller 62 supported by the auxiliary frame 60 and driven in rotation by an electric motor 63. The axial cage 4 also comprises an upper conical roller 64 driven in rotation by an electric motor 65. The axes of symmetry and rotation of the conical rollers 62 and 64 are denoted A62 and A64 respectively. These axes are inclined relative to the horizontal and the vertical. They converge as they approach the mandrel 20 and the axis A20.

[0051] The useful surfaces of the conical rollers 62 and 64 are denoted respectively by S62 and S64. By active surfaces S62 and S64, we mean the surfaces of the conical rollers 62 and 64 which make it possible to exert the axial compression forces F3 and F4. The edges of larger diameter of the useful surfaces S62 and S64 are denoted respectively by 62A and 64A. The useful surfaces S62 and S64 are superimposed, that is to say aligned vertically, as are their edges 62A and 62B.

[0052] We note dl a maximum distance, measured parallel to the axis X2, between the longitudinal axis A20 of the mandrel 20 and the rear edge 62A of the active surface S62. Advantageously, the distance dl is measured at the level of a horizontal portion of the useful surface S62. This distance dl has a minimum value in the configurations of the inserts A) and B) of [Fig.6] and C) of [Fig.7].

[0053] When the part to be rolled is in place in the rolling mill 1, it is subjected to axial compression forces F3 and F4 exerted respectively by the upper conical roller 64 and by the lower conical roller 62 on the axial faces 103 and 104 of the part 100 during rolling.

[0054] The chassis 60 is interposed, along the longitudinal axis X2, between, on the one hand, the two mandrel holders 22 and 32 and, on the other hand, the displacement system 40. In other words, the displacement system 40 is mounted, on the main chassis 2, on the side of the auxiliary chassis 60 opposite the mandrel holders 22 and 32.

[0055] To do this, the chassis 60 is equipped with four sleeves 66 which each define a cylindrical volume V66 whose cross-section corresponds to that of the drive bars 24, 26, 34 and 36.

[0056] In the example, the drive bars 24, 26, 34 and 36 are of circular section and the volumes V66 are also of circular section, with a diameter slightly greater than that of the drive bars.

[0057] Alternatively, the drive bars 24, 26, 34 and 36 may have sections other than circular, for example polygonal, in which case the geometry of the volumes V66 is adapted.

[0058] The volumes V66 pass through the auxiliary chassis from one side to the other and allow the driving bars 24, 26, 34 and 36 to be guided in translation over the entire length of the sleeves 66, through the auxiliary chassis 60. In other words, the auxiliary chassis 60 is slidably mounted on the driving bars 24, 26, 34 and 36 and guided in longitudinal translation, parallel to the axis X2, by the cooperation of the sleeves 66 and the driving bars.

[0059] Furthermore, the sleeves 66 allow for the absorption of force, in particular weight or axial reaction forces of the part 100 during rolling, which limits the effect of the overhang of the drive bars 24, 26, 34 and 36 relative to the displacement system 40. This is particularly noticeable at the level of the drive bars. upper 24 and 26, which support the upper mandrel holder 22 and its accessories, including the mandrel 20 and the lowering / raising mechanism 28. This is less sensitive at the level of the lower drive bars 34 and 36 because the lower mandrel holder rests on the tracks 52 by rollers 38 and equivalent.

[0060] Furthermore, a mechanism 70 is provided for moving the auxiliary chassis 60, therefore the axial cage 4, along the longitudinal axis X2, relative to the drive bars, that is to say relative to the radial cage 3, in particular relative to the lower drive bars 34 and 36.

[0061] More precisely, the displacement mechanism 70 comprises a frame 72 equipped with two sleeves 74 whose internal volume V74 constitutes a housing which makes it possible to accommodate a portion of the drive bars 34 and 36. The volumes or housings V74 pass right through the frame 72. The frame 72 is immobilized along the drive bars 34 and 36, for example by screws, pins or keys not shown.

[0062] The frame 72 is of elongated shape and extends transversely to the longitudinal axis X2, between the drive bars 34 and 36. It constitutes a beam resting on these two bars.

[0063] Advantageously, as can be seen in particular in [Fig. 4], the frame is made up of two sheet metal plates assembled together and which define between them a volume for receiving accessories of the movement mechanism 70.

[0064] The frame 74 supports an electric motor 76 which drives a belt 78, which partially surrounds pulleys 80 each secured to a worm screw 82. The belt 78 and the pulleys 80 are mounted in the frame 72, in the volume defined between the sheets of this frame, and protected by a cover 73.

[0065] Each worm screw 82 is engaged in a housing 84 equipped with balls, not shown, and designed to circulate in the threads of the worm screw in question.

[0066] Thus, a ball screw type connection is made between the elements 82 and 84.

[0067] As a result, a rotation of a worm screw 82 around its longitudinal axis has for the effect of moving the housing 84, in which it is engaged, parallel to the longitudinal axis X2, relative to the frame 72, which is fixed relative to the drive bars 24, 26, 34 and 36, as explained above.

[0068] The two housings 84 are integral with the auxiliary chassis 60, so that the movement of these housings along the two endless screws 82 has the effect of moving, concomitantly, the auxiliary chassis 60 relative to the frame 72.

[0069] The belt 78 and the pulleys 80 ensure synchronization of the movement of the worm screws 82 around their respective longitudinal axes A82, therefore synchronization of the movement of the housings 84 and movement of the auxiliary chassis 60 parallel to the longitudinal axis X2, without risk of jamming of the latter relative to to the main chassis 2.

[0070] In this respect, the auxiliary chassis 60 is equipped with rollers, two of which are visible in [Fig. 2] with the reference 68. Other rollers are arranged symmetrically to those visible, with respect to the plane PI. The rollers 68 and equivalent allow the auxiliary chassis 60 to move with a minimum of friction on the tracks 52. Counter-rollers 69 engaged against the sides of the main chassis 2 ensure the stability of the auxiliary chassis 60 and prevent it from tilting during its movements along the longitudinal axis X2 and during rolling.

[0071] Since the frame 72 is immobilized on the drive bars 34 and 36, it serves as a fixed point for the movement of the auxiliary chassis 60 relative to these drive bars.

[0072] Thus, the actuation of the electric motor 76 makes it possible to move the auxiliary frame 60, and therefore the conical rollers 62 and 64 which it supports, parallel to the longitudinal axis X2, while the lower mandrel holder 32 remains in a position fixed by the drive bars 34 and 36, where the mandrel 20 contributes to the application of the compression forces F1 and F2 on the external and internal radial faces 101 and 102 of the part 100 during rolling. The movement of the auxiliary frame 60 and the conical rollers 62 and 64 by the movement mechanism 70 constitutes a secondary movement, within the rolling mill 1, which makes it possible to adapt the longitudinal position of the conical rollers 62 and 34, therefore the points of application of the axial compression forces F3 and F4, while the mandrel 20 remains in a position allowing the application of the radial compression forces F1 and F2.

[0073] Thus, the displacement system 40 constitutes a primary displacement system of the mandrel 20 and the mandrel holders 22 and 32, while the displacement mechanism 70 constitutes a secondary displacement mechanism of the auxiliary frame 60 and the conical rollers 62 and 64, along the longitudinal axis X2.

[0074] Starting from the configuration of the insert A) of [Fig. 6] where the part 100 is at the start of rolling, it is possible to exert, thanks to the shaping roller 10, the mandrel 20 and the conical rollers 62 and 64, the compressive forces F1, F2, F3 and F4, respectively on the faces 101, 102, 103 and 104. This has the effect of progressively increasing an external diameter D100 of the part being rolled, as is apparent from the comparison of the inserts A) and B) of [Fig. 6] and the insert C) of [Fig. 7]

[0075] The external diameter D100 is the diameter of the radial face 101 of the part 100 being rolled.

[0076] In the configuration of insert C) of [Fig.7], the diameter D100 of the part 100 being rolled is such that its part on which the forces F3 and F4 are exerted is close to the edges of larger diameter 62A, 64A of each of the conical rollers 62 and 64. The tapered rollers 62 and 64 are in the same position as on the inserts A) and B) of [Fig.6].

[0077] To allow rolling of the part 100 to continue, and as is apparent from the comparison of inserts C) and D) of [Fig. 7], the movable nature of the auxiliary frame 60 relative to the mandrel holder 32 is used to move the conical rollers 62 and 64 back relative to the mandrel 20, in the direction D2 marked on the insert D) of [Fig. 7], by moving the auxiliary frame 60 along the longitudinal axis X2, in the direction of the primary displacement system 40, by means of the secondary displacement mechanism 70.

[0078] This allows the useful surface S62, respectively S64, of each conical roller 62 and 64 to remain in overlap with the part 100 during rolling, including when its external diameter D100 increases beyond the sum of the thickness of the part 100, the radius of the mandrel 20 and the initial value of the distance dl in the configuration of the inserts A) and B) of [Fig. 6]. This allows the forces F3 and F4 mentioned above to be exerted throughout the rolling of the part 100.

[0079] This movement of the conical rollers 62 and 64 in the direction D2 is carried out without shifting the mandrel holders 22 and 32 along the longitudinal axis X2, which ensures that the radial compression forces F1 and F2 continue to be applied to the external and internal radial surfaces 101 and 102 of the part 100. This movement of the conical rollers 62 and 64 is carried out by actuating the electric motor 76 to move the housings 84 in the direction of the frame 72, that is to say also in the direction D2, while the frame 72 remains stationary along the longitudinal axis X2, as do the drive bars 34 and 36.

[0080] As the part 100 is rolled, the electric motor 72 is actuated to progressively move the conical rollers 62 and 64 in the direction D2, which makes it possible to reach the configuration shown in the insert E) of [Fig. 8] which corresponds to the position of the auxiliary frame 60 shown in Figures 1 to 3.

[0081] Comparison of inserts C), D) and E) of figures 7 and 8 shows that the mobile nature of the auxiliary frame 60 along the drive bars 24, 26, 34 and 36 makes it possible to increase the maximum admissible value of the external diameter D100 of the part 100 during rolling, which gives good adaptability to the rolling mill 1, compared to the rolling mills of the prior art.

[0082] At the end of the rolling operation, the mandrel 20 is lifted relative to the mandrel holders 22 and 32, to the point that it is extracted from the housing 33 and brought above the rolled part 100. On the other hand, an electric motor 49, which belongs to the axial cage 4, is then actuated to lift the upper conical roller 62 relative to the lower conical roller 64, which makes it possible to reach the configuration of the insert F) of [Fig. 8], where the rolled part 100 can be extracted from the rolling mill by means of a multi-axis robot or a specific manipulator, not shown. This multi-axis robot or this specific manipulator can also be used to load the part to be rolled 100 onto the circular rolling mill 1.

[0083] During rolling, the part 100 is centered with respect to the mandrel 22 by means of two centering arms, only one of which is visible in Figures 1 and 2 with the reference 85. The two centering arms, 85 and equivalent, are arranged symmetrically with respect to the median longitudinal plane PI. Each centering arm is rotated about a vertical axis Z85 by an electric motor 86 and carries a centering roller 87 which comes to bear against the external radial face 102 of the part 100 during rolling.

[0084] As the tapered rollers 62 and 64 move back in the direction D2, the value of the distance dl increases, as can be seen by comparing the inserts C) and D) of [Fig.7] and the insert E) of [Fig.8]. This increase in the value of the distance dl is achieved by actuating the electric motor 76 as a function of the increase in the external diameter D100 of the part 100 during rolling.

[0085] Thus, it is possible to implement on the rolling mill 1 a method of rolling the annular part 100 which comprises at least the steps consisting of: a. shaping the outer and inner radial faces 101 and 102 of the annular part 100 by means of the shaping roller 10 and the mandrel 20, as well as the lower and upper axial faces 104 and 103 by means of the lower and upper conical rollers 62 and 64; b. adjust, as a function of the diameter D100 of the annular part 100 being rolled, the distance dl, by actuating the secondary mechanism 70 for moving the auxiliary chassis 60 along the drive bars 24, 26, 34 and 36, preferably by actuating the electric motor 76 of this mechanism.

[0086] Such a method makes it possible to roll parts 100 of relatively large diameter, with a compact and relatively simple, therefore reliable, rolling mill.

[0087] In the second embodiment of the invention shown in [Fig. 8], elements similar to those of the first embodiment bear the same reference, possibly accompanied by the index A or B. In what follows, if a reference is used in the description without being shown in [Fig. 9] or shown in this figure without being mentioned in the description, it designates the same object as that bearing the same reference in the first embodiment, possibly after removal of the index A or B

[0088] The circular rolling mill 1 of this second embodiment differs from the first embodiment in that the radial cage 3 comprises two mandrels, not shown, each supported by an upper mandrel holder 22A or 22B and a mandrel holder lower 32A or a mandrel holder not shown located under the upper mandrel holder 22b. This circular rolling mill 1 also comprises two radial stands 4A and 4B. In other words, the structure of the circular rolling mill of the first embodiment is symmetrical with respect to the axis Z10 of rotation of the shaping roller 10.

[0089] The circular rolling mill 1 of this second embodiment comprises two sets of four drive bars 24A, 26A, 34A and 36A, on the one hand, 24B, 26B, 34B and 36B, on the other hand.

[0090] This embodiment proceeds from the approach known in so-called “MIRA” circular rolling mills, according to which a part 100 to be rolled or already rolled can be loaded or unloaded from the rolling mill 100 in masked time, while another part 100 is being rolled, on the other side of the shaping roller 10.

[0091] In this second embodiment, the movement system is duplicated in the form of two primary movement systems 40A and 40B, while the movement mechanism is duplicated in the form of two secondary movement mechanisms 70A and 70B, which makes it possible to move each of the auxiliary carriages 60A and 60B independently of the upper and lower mandrel holders 22A, 22b 32a and equivalent, on each side of the vertical axis of rotation Z10.

[0092] In this second embodiment, two rolling arms 85A and 85B are provided on either side of the main frame and driven by electric motors 86A and 86B. This embodiment therefore comprises four rolling arms and four motors for moving this arm. In [Fig.9], the rolling arms 85A and 85B are shown in the position separated from their rollers 87A and 87B relative to the part to be rolled 100.

[0093] A method of the type mentioned above can be carried out alternately on both sides of the shaping roller 10 of the circular rolling mill 1 of [Fig.9].

[0094] According to a variant of the invention not shown, the secondary drive mechanism(s) is or are mounted on the upper drive bars 24 and 26 or equivalent. According to another variant, the secondary drive mechanism(s) is or are mounted on both the lower drive bars and the upper drive bars. In this case, it is not possible to desynchronize the chuck holders 22 and 32.

[0095] According to another variant of the invention, not shown, each ball screw system 82 + 84 can be replaced by a nut and worm screw system or by a rack and pinion system which are also driven by a belt of the belt type 78. According to another variant, also not shown, these systems can be replaced by cylinders for moving the frame 72 and the auxiliary chassis 60 apart / together parallel to the longitudinal axis X2, these cylinders being able to be of the electric, pneumatic or hydraulic type.

[0096] According to another variant of the invention, not shown, one or all of the mandrel holders is or are integral, in translation along the longitudinal axis X2, with a single drive bar. The primary drive system 40 and the secondary drive mechanism 70 are then adapted.

[0097] The embodiments and variations mentioned above can be combined to generate new embodiments of the invention.

Claims

Claims

1. Circular rolling mill (1) for shaping annular parts (100), comprising a main frame (2), a radial stand (3) and at least one axial stand (4), the radial stand comprising a roller (10) for shaping an external radial face (101) of a part to be rolled (100) and a mandrel (20) for shaping an internal radial face (102) of the part to be rolled, the axial stand comprising an auxiliary frame (60) and lower and upper conical rollers (62, 64) for shaping lower and upper radial faces (104, 103) of the part to be rolled, the mandrel being supported by an upper mandrel holder (22) and selectively engaged in a lower mandrel holder (32), each of the mandrel holders (22, 32) being integral, in translation along a longitudinal axis (X2) of the main chassis (2), with at least one drive bar (24, 26, 34, 36) parallel to the longitudinal axis of the main chassis,characterized in that - the movement of the mandrel holders (22, 32) parallel to the longitudinal axis (X2) of the main frame (2) is controlled by a movement system (40) arranged on the same side of the shaping roller (10) as the mandrel (20); - the auxiliary frame (60) is slidably mounted, parallel to the longitudinal axis of the main frame, on the drive bars (24, 26, 34, 36) of the mandrel holders, which pass right through it; and - the circular rolling mill (1) comprises a mechanism (70) for moving the auxiliary frame (60) in translation relative to the drive bars (24, 26, 34, 36), parallel to the longitudinal axis (X2) of the main frame (2).,

2. Rolling mill according to claim 1, in which - a system (40) for moving the drive bars is mounted, on the main frame (2), on the side of the auxiliary frame (60) opposite the mandrel holders (22, 32), - the drive bars (24, 26, 34, 36) extend between the moving system (40) and the mandrel holders (22, 32) and - the auxiliary frame (60) is provided with openings (V66) for the passage of the drive bars and for guiding the movements of the auxiliary chassis on these drive bars.

3. Rolling mill according to one of the preceding claims, in which each mandrel holder (22, 32) is integral with two drive bars (24, 26, 34, 36), distributed on either side of a median longitudinal plane (PI) of the rolling mill, and in which the movement mechanism (40) synchronizes the movement of the auxiliary frame (60) along the two drive bars of one of the mandrel holders.

4. Rolling mill according to the preceding claim, in which the drive bars (34, 36) with respect to which the movement mechanism (40) synchronizes the movement of the auxiliary frame (60) are integral with the lower mandrel holder (32).

5. Rolling mill according to one of claims 3 and 4, in which the movement mechanism (40) comprises a frame (72) mounted on the two drive bars (34, 36) and immobilized, in translation along the longitudinal axis (X2) of the main chassis (2), on these two drive bars, as well as members (82) for driving the auxiliary chassis (60) along the drive bars (34, 36), relative to the frame.

6. Rolling mill according to the preceding claim, in which the frame (72) is provided with two orifices (V74) for the passage of the longitudinal bars (34, 36) on which it is mounted and immobilized.

7. Rolling mill according to one of claims 5 and 6, in which the frame (72) supports a motor (76) for moving the auxiliary chassis (60) along the drive bars (34, 36) and members (78, 80, 82) for transmitting movement between the motor and the auxiliary chassis.

8. Rolling mill according to the preceding claim, in which the movement transmission members comprise a belt (78) and two parts (82) of ball screw systems (82+84), a belt and two parts of nut and worm systems or two parts of rack and pinion systems.

9. Rolling mill according to one of claims 5 and 6, in which the frame (72) carries at least one cylinder for separating / bringing together the frame and the auxiliary chassis (60) parallel to the longitudinal axis of the main chassis.

10. Rolling mill according to one of the preceding claims, in which a axial cage (4A, 4B) and a mandrel are provided on each side of the shaping roller (10), along the longitudinal axis (X2) of the main frame (2), in which the auxiliary frame (60A, 60B) of each radial cage is slidably mounted, parallel to the longitudinal axis of the main frame, on the drive bars (24A, 26A, 34A, 36A, 24B, 26B, 34B, 36B) of the mandrel holders (22A, 32A, 22B) located on the same side, which pass right through it; and in which the circular rolling mill comprises two mechanisms (70A, 70B) for moving the auxiliary frames (60A, 60B) in translation relative to the drive bars, parallel to the longitudinal axis (X2) of the main frame (2).

11. Method for rolling an annular part (100) by means of a rolling mill (1) according to one of the preceding claims comprising at least steps consisting of: a. shaping the outer and inner radial faces (101, 102) of the annular part, by means of the shaping roller (10) and the mandrel (20), and the lower and upper axial faces (104, 103), by means of the lower and upper conical rollers (62, 64); and b. adjusting, as a function of a diameter (D100) of the annular part (100) being rolled, a distance (dl) between the mandrel and a rear edge (62A, 64A) of the conical rollers (62, 64) by actuating the movement mechanism (70) of the auxiliary frame (60) along the drive bars (24, 26, 34, 36).

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