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 fixed, in translation along a longitudinal axis (X2) of the main frame, to 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 displacement system (40) located on the same side of the forming roller (10) as the mandrel. The auxiliary frame (60) slides, along the longitudinal axis, on the drive bars, which pass through it from one side to the other.A mechanism (70) moves the auxiliary frame (60) relative to the drive bars (24, 26, 34, 36), in translation parallel to the longitudinal axis (X2). Figure for the abbreviation: 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 forming roller and a forming mandrel allowing, within a radial stand, the external and internal radial faces of a part to be rolled to be formed respectively.

[0002] In the field of rolling, WO2009 / 125102A1 discloses a rolling mill comprising a radial stand and an axial stand. The radial stand itself comprises a forming roller for an external radial face of a workpiece and a forming mandrel for an internal radial face of that workpiece. The axial stand comprises an auxiliary frame and lower and upper conical rollers for forming the lower and upper radial faces of the workpiece. The movement of the mandrel relative to the forming roller of the external radial face of the workpiece is controlled by a drive assembly located opposite the mandrel with respect to this forming roller. 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 forming roller. 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 forming roll of the outer radial face of the parts to be rolled. Such a rolling mill with two opposing axial stands is sometimes called a "MIRA". While it allows for increased production rates, such a rolling mill has the drawback that the diameter of the rolled parts is limited by the horizontal length of the conical rolls 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 conical rolls opposite the adjacent mandrel. If the diameter of the part being rolled increases further, then it escapes the conical rolls 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 intends to remedy in particular by proposing a new circular rolling mill which is compact and which allows rolling of 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 forming roller for an external radial face of a workpiece to be rolled and a forming mandrel for an internal radial face of the workpiece to be rolled, the axial cage comprising an auxiliary frame and lower and upper conical rollers for forming lower and upper radial faces of the workpiece 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 fixed, 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 located on the same side of the forming roller as the mandrel. The auxiliary frame is mounted to slide parallel to the longitudinal axis of the main frame on the drive bars of the mandrel holders, which pass through it completely. In addition, the circular rolling mill includes a mechanism for moving the auxiliary frame in translation 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 it exerts on the inner radial face of the workpiece to be rolled, can be controlled by means of the drive bars attached to the mandrel holders. Furthermore, the conical rollers, which are supported by the auxiliary frame of the axial stand, can be moved in translation, along a radial direction to the axis of rotation of the forming roller of the outer face of the workpiece to be rolled, independently of the mandrel, while it exerts a forming force on the inner radial face of this workpiece. It is thus possible to adjust the longitudinal position of the conical rollers of the axial stand, according to the actual diameter of the workpiece 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 permissible 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 attached 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 movement of the auxiliary frame along the two drive bars of one of the mandrel holders.

[0011] - The drive bars relative to which the syn displacement mechanism The movement of the auxiliary chassis is fixed to the lower chuck holder.

[0012] - The displacement 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 elements of the auxiliary chassis along the drive bars, relative to the frame.

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

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

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

[0016] - The frame carries at least one cylinder for spacing / bringing the frame and the chassis together 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 conformation, along the longitudinal axis of the main frame, the auxiliary frame of each radial stand is mounted sliding, parallel to the longitudinal axis of the main frame, on the drive bars of the mandrel holders located on the same side, which pass through it; and the circular rolling mill includes two mechanisms for moving the auxiliary frames in translation 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 for rolling an annular part using a rolling mill according to one of the preceding claims, comprising at least the steps of:

[0019] a) shaping the external and internal 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) adjust, according to a diameter of the annular part being rolled, a distance between the mandrel and a rear edge of the conical rollers by actuating the mechanism for moving the auxiliary frame along the drive bars.

[0021] The method of the invention makes it possible, by actuating the mechanism for moving 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 become more apparent in the light of the following description of two embodiments of a circular rolling mill and a rolling process conforming to its principle, given solely by way of example and with reference to the attached drawings in which:

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

[0024] [Fig.2] The [Fig.2] is a perspective section along plane II in the [Fig.1];

[0025] [Fig.3] The [Fig.3] is a perspective section along plane III in the [Fig.1];

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

[0027] [Fig.5] The [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 analogous to those of [Fig.6], when the rolling mill is in third and fourth rolling configurations;

[0030] [Fig.8] [Fig.8] shows, on two insets E) and F), partial sections analogous 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] The [Fig.9] is a view analogous to the [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 workpiece 100, of which 101 is noted an external radial face, 102 an internal radial face, 103 a superior axial face and 104 an inferior axial face.

[0035] The radial cage 3 includes a first forming roller 10 of the external radial face 101 of the workpiece to be rolled 100, which is mounted to rotate about a vertical axis Z10, defined by a support and drive assembly 12 including in particular an electric motor 14. The electric motor 14 is covered by a hood 15. When activated, the electric motor 14 drives the forming roller in rotation about the axis Z10.

[0036] We note 10A the external peripheral surface of the forming roller 10 which comes into contact with the external radial face 101 of the part 100 being rolled.

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

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

[0039] The rolling mill 1 also includes 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, and therefore in the lower mandrel holder 32, during the rolling phases, and disengaged from this housing for loading a workpiece to be rolled or unloading a rolled workpiece. The lower mandrel holder 32 is mounted at the end of two drive bars 34 and 36. The mandrel holder 32 can also be referred to as a "cradle". The lower chuck holder 32 is equipped with rollers, only one of which is visible in [Fig.2] with reference 38. The other roller is arranged symmetrically to the one visible, with respect to the main frame 2. The chuck holder 32 rests, by its rollers 38 and equivalent, on two tracks 52 provided in the upper part of the main frame 2.The rollers 38 and equivalent facilitate the movement of the lower chuck 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 in pairs, with 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 is 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 allow the mandrel 20 to be held in a configuration pressed against the internal radial face 102 of the workpiece 100 being rolled.

[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 frame 42, two electric motors 44 and 45 and two right-angle drives 46 and 47, each driven by one of the electric motors 44 and 45. Each angle gearbox 46 or 47 drives two pinions 48 arranged on either side of the average longitudinal plane PI, each in contact with a rack 50 provided on one of the drive bars 24, 26, 34 and 36.

[0044] Thus, actuation of the electric motor 44 allows the drive bars 24 and 26, and therefore the upper chuck holder 22, to be moved parallel to the longitudinal axis X2. Conversely, actuation of the electric motor 45 allows the drive bars 34 and 36, and therefore the lower chuck holder 32, to be moved parallel to the axis X2. The motors 44 and 45 are synchronized so that the movements of the chuck holders 22 and 32 are also synchronized. The movement system 40 therefore controls the movement of the chuck holders 22 and 32 parallel to the longitudinal axis X2.

[0045] During the loading and unloading phases of 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 forming roller 10 as the mandrel 20. In the representation of figures 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 forming roller 10 and its axis of rotation Z10. Thus, the rolling mill 1 is compact.

[0047] When the rolling piece 100 is in place in the rolling mill 1, as shown in Figures 1 to 3 and 5 to 8 E), this piece is subjected to radial compressive forces Fl and F2, respectively exerted by the forming roller 10 and by the mandrel 20, on its internal and external radial faces 101 and 102. The intensity of these radial compressive forces depends on the intensity of a pushing 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 forming 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 allows the radial compression forces Fl and F2 to be exerted.

[0049] The axial cage 4 includes an auxiliary frame 60 mounted on the main frame 2 and movable, relative to this frame, 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. A62 and A64 are respectively denoted as the axes of symmetry and rotation of the conical rollers 62 and 64. These axes are inclined with respect to the horizontal and vertical. They converge as they approach the mandrel 20 and the axis A20.

[0051] The effective surfaces of the conical rollers 62 and 64 are denoted S62 and S64, respectively. The active surfaces S62 and S64 are those surfaces of the conical rollers 62 and 64 that allow the axial compression forces F3 and F4 to be applied. The edges of largest diameter of the effective surfaces S62 and S64 are denoted 62A and 64A, respectively. The effective surfaces S62 and S64 are superimposed, that is, vertically aligned, as are their edges 62A and 62B.

[0052] A maximum distance dl, measured parallel to the axis X2, is denoted by dl 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 a horizontal portion of the working surface S62. This distance dl has a minimum value in the configurations of 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 being rolled.

[0054] The chassis 60 is interposed, along the longitudinal axis X2, between, on the one hand, the two chuck 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 chuck 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 have a circular cross-section and the volumes V66 also have a circular cross-section, with a diameter slightly larger 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 frame from one side to the other and allow the drive bars 24, 26, 34 and 36 to be guided in translation along the entire length of the sleeves 66, through the auxiliary frame 60. In other words, the auxiliary frame 60 is mounted to slide on the drive 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 drive bars.

[0059] Furthermore, the sleeves 66 allow for the absorption of forces, particularly weight or axial reaction forces of the workpiece 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 drive bars. upper 24 and 26, which support the upper chuck holder 22 and its accessories, including the chuck 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 chuck holder rests on the tracks 52 by rollers 38 and equivalent.

[0060] Furthermore, a mechanism 70 is provided to move the auxiliary frame 60, i.e. the axial cage 4, along the longitudinal axis X2, relative to the drive bars, i.e. relative to the radial cage 3, in particular relative to the lower drive bars 34 and 36.

[0061] More specifically, the displacement mechanism 70 comprises a frame 72 equipped with two sleeves 74, the internal volume V74 of which constitutes a housing which allows to accommodate part of the drive bars 34 and 36. The volumes or housings V74 pass 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 elongated in shape and extends transversely to the longitudinal axis X2, between the drive bars 34 and 36. It constitutes a beam supported on these two bars.

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

[0064] The frame 74 supports an electric motor 76 which drives a belt 78, which partially surrounds pulleys 80 each attached to a worm gear 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 intended to circulate in the threads of the worm screw in question.

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

[0067] It follows that a rotation of a worm screw 82 around its longitudinal axis has to move 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 fixed to the auxiliary chassis 60, so that the movement of these housings along the two worm 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 gears 82 around their respective longitudinal axes A82, thus synchronizing the movement of the housings 84 and setting the auxiliary frame 60 parallel to the longitudinal axis X2 in motion, without risk of jamming the latter relative to to the main chassis 2.

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

[0071] As 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 Fl and F2 on the external and internal radial faces 101 and 102 of the part 100 being rolled. 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 allows the longitudinal position of the conical rollers 62 and 34 to be adapted, and 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 Fl and F2.

[0073] Thus, the displacement system 40 constitutes a primary displacement system of the chuck 20 and the chuck 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 insert A) of [Fig. 6] where the part 100 is at the beginning of rolling, it is possible to exert, by means of the forming roller 10, the mandrel 20 and the conical rollers 62 and 64, the compressive forces Fl, 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 can be seen from the comparison of inserts A) and B) of [Fig. 6] and 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 workpiece 100 being rolled is such that its portion 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 conical rollers 62 and 64 are in the same position as on inserts A) and B) of [Fig.6].

[0077] To allow the rolling of the part 100 to continue, and as can be seen 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 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 ensures that the effective surface S62, respectively S64, of each conical roller 62 and 64 remains in overlap with the workpiece 100 being rolled, even when its external diameter D100 increases beyond the sum of the thickness of the workpiece 100, the radius of the mandrel 20, and the initial value of the distance dl in the configuration of inserts A) and B) of [Fig. 6]. This allows the forces F3 and F4 mentioned above to be applied throughout the rolling of the workpiece 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 Fl 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, i.e. 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 activated to progressively move the conical rollers 62 and 64 in the direction D2, which makes it possible to reach the configuration shown on 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 permissible value of the external diameter D100 of the part 100 being rolled, which gives good adaptability to the rolling mill 1, compared to 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 workpiece 100. Meanwhile, an electric motor 49, which belongs to the axial stand 4, is then actuated to lift the upper conical roll 62 relative to the lower conical roll 64, thus achieving the configuration of insert F) of [Fig. 8], where the rolled workpiece 100 can be extracted from the rolling mill by means of a multi-axis robot or specific manipulator, not shown. This multi-axis robot or specific manipulator can also be used to load the workpiece to be rolled 100 onto the circular rolling mill 1.

[0083] During rolling, the workpiece 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 reference numeral 85. The two centering arms, 85 and equivalent, are arranged symmetrically with respect to the median longitudinal plane PI. Each centering arm is driven in rotation about a vertical axis Z85 by an electric motor 86 and carries a centering roller 87 which bears against the outer radial face 102 of the workpiece 100 being rolled.

[0084] As the conical rollers 62 and 64 retract in direction D2, the value of the distance dl increases, as can be seen by comparing inserts C) and D) of [Fig. 7] and insert E) of [Fig. 8]. This increase in the value of the distance dl is achieved by actuating the electric motor 76 according to the increase in the external diameter D100 of the workpiece 100 being rolled.

[0085] Thus, it is possible to implement on the rolling mill 1 a rolling process for the annular part 100 which includes at least the steps of: a. conform the external and internal radial faces 101 and 102 of the annular part 100 by means of the conforming 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, according to the diameter D100 of the annular part 100 being rolled, the distance dl, by actuating the secondary mechanism 70 for moving the auxiliary frame 60 along the drive bars 24, 26, 34 and 36, preferably by actuating the electric motor 76 of this mechanism.

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

[0087] In the second embodiment of the invention shown in [Fig. 8], elements analogous to those of the first embodiment bear the same reference numeral, possibly with the subscript A or B. In what follows, if a reference numeral is used in the description without being shown in [Fig. 9] or shown in that figure without being mentioned in the description, it designates the same object as that bearing the same reference numeral in the first embodiment, possibly after the subscript A or B has been removed.

[0088] The circular rolling mill 1 of this second embodiment differs from the first embodiment in that the radial stand 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 below the upper mandrel holder 22b. This circular rolling mill 1 also includes 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 forming roll 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 circular rolling mills called "MIRA", 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 forming roll 10.

[0091] In this second embodiment, the displacement system is duplicated in the form of two primary displacement systems 40A and 40B, while the displacement mechanism is duplicated in the form of two secondary displacement mechanisms 70A and 70B, which allows each of the auxiliary carriages 60A and 60B to be moved independently of the upper and lower chuck 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 these arms. In [Fig. 9], the rolling arms 85A and 85B are shown with their rollers 87A and 87B positioned away from the workpiece 100.

[0093] A process of the type mentioned above can be implemented alternately on both sides of the forming roller 10 of the circular rolling mill 1 of [Fig.9].

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

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

[0096] According to another, unshown, embodiment of the invention, one or all of the chuck holders are fixed, in translation along the longitudinal axis X2, to a single drive bar. The primary drive system 40 and the secondary drive mechanism 70 are then adapted.

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

Claims

Demands

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 fixed, in translation about a longitudinal axis (X2) of the main frame (2), with at least one drive bar (24, 26, 34, 36) parallel to the longitudinal axis of the main frame,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 displacement system (40) arranged on the same side of the forming roller (10) as the mandrel (20); - the auxiliary frame (60) is mounted to slide, parallel to the longitudinal axis of the main frame, on the drive bars (24, 26, 34, 36) of the mandrel holders, which pass through it; and - the circular rolling mill (1) includes a displacement mechanism (70) for translating the auxiliary frame (60) 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, wherein: - a drive bar transport system (40) 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 transport 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 any one of the preceding claims, wherein 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 wherein the displacement mechanism (40) synchronizes the displacement 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 displacement mechanism (40) synchronizes the displacement of the auxiliary frame (60) are integral with the lower mandrel holder (32).

5. Rolling mill according to any one of claims 3 and 4, wherein the displacement 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 frame (2), on these two drive bars, as well as drive elements (82) of the auxiliary frame (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 openings (V74) for the passage of the longitudinal bars (34, 36) on which it is mounted and immobilized.

7. Rolling mill according to any one of claims 5 and 6, wherein the frame (72) supports a motor (76) for moving the auxiliary frame (60) along the drive bars (34, 36) and motion transmission elements (78, 80, 82) between the motor and the auxiliary frame.

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

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

10. Rolling mill according to any one of the preceding claims, wherein a axial cage (4A, 4B) and a mandrel are provided on each side of the forming roller (10), along the longitudinal axis (X2) of the main frame (2), in which the auxiliary frame (60A, 60B) of each radial cage is mounted to slide, 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 through it; and in which the circular rolling mill includes two translational displacement mechanisms (70A, 70B) of the auxiliary frames (60A, 60B) relative to the drive bars, parallel to the longitudinal axis (X2) of the main frame (2).

11. A method for rolling an annular part (100) using a rolling mill (1) according to any one of the preceding claims, comprising at least the steps of: a. shaping the external and internal 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. adjust, according to 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 displacement mechanism (70) of the auxiliary frame (60) along the drive bars (24, 26, 34, 36).

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