Billet rolling mill equipped with a manipulator subassembly and method for controlling such a mill

Abstract

The blank rolling mill comprises two forming rolls for shaping a blank (E) to be shaped and a manipulator subassembly (20) for moving the blank with respect to the forming rolls, each forming roll being provided with at least one rolling tool and rotating about a rotation axis by means of at least one respective drive motor. The manipulator subassembly comprises a clamp (39) for clamping the blank and a carriage (35) for moving the clamp at least along a rolling direction (X38) of the blank. The manipulator subassembly (20) comprises at least one linear motor (200) for moving the carriage (35) along the rolling direction (X38). The rolling direction (X38) is perpendicular to the rotation axis of the rolling tools. The linear motor (200) is configured for accelerating the blank (E) and selectively applying on the blank a stretching force tending to extract the blank from a gap defined between the rolling tools (72, 82) or a braking force tending to limit the ejection speed of the blank.

Description

TECHNICAL FIELD

[0001] The present invention relates to a blank rolling mill, comprising in particular two forming rolls for hot forming of a blank to be shaped, and a manipulator subassembly for moving such a blank relative to the rolls. The invention also relates to a method for controlling such a rolling mill. BACKGROUND

[0002] In a blank rolling mill, the blanks or billets are generally constituted by steel, aluminum or titanium bars having a cylindrical or rectangular cross section. The rolling of each blank or billet is a hot rolling which is carried out several times between two forming rolls rotating in synchronism and in opposite directions. Each forming roll carries in a portion of the roll a stack of tools each defining a profile for shaping the volume of material forming the blank in the longitudinal direction. The rolling operation is carried out by feeding the blank between the forming rolls and then translating the blank between the two tools of a pair of tools mounted respectively on the two forming rolls in the direction of the rolling direction.

[0003] After each passage of the blank between the two tools of a pair of tools, the blank is moved translationally in a direction parallel to the axis of rotation of the rolls so as to place the blank opposite the next pair of tools before starting a new rolling by reinserting the blank between the forming rolls and then reshaping the blank by passing it between the next pair of tools in the rolling direction. By successively passing the blank between pairs of tools respectively mounted on the two forming rolls, this operation is repeated several times as necessary to shape the blank until the desired geometry is reached. Optionally, the orientation of the blank around its longitudinal axis can be changed between different rolling steps.

[0004] In order to move the blank relative to the pair of forming rolls, it is known to equip the blank rolling mill with a manipulator subassembly comprising a clamp for clamping the blank, the manipulator subassembly being used to move the blank in the rolling direction and, where appropriate, parallel to the axis of rotation of the rolls. The movement of the manipulator subassembly must be synchronized with the rotation of the forming rolls. Furthermore, the movement must be precise and rapid, since it contributes to the definition of the geometry of the rolled part and of the overall cycle time of the rolling.

[0005] When the blank is rolled, the blank comes into contact with the tools mounted on the two forming rolls, said tools having a variable diameter according to the geometry given to the blank. The variable nature of the tool diameter makes it impossible to determine the linear speed of the blank in the rolling direction with precision from the relationship v = r * ω, where v is the linear speed of the blank, r is the radius of the tool and ω is the angular speed of rotation of the rolls. Furthermore, elongation of the blank occurs as a result of the rolling operation, which is not perfectly controlled. Thus, the linear speed of the blank is not very precisely known during rolling.

[0006] In certain known rolling mills, the manipulator subassembly comprises a ram which carries the blank clamping jaws and which is actuated to push the blank into between the forming rollers, the tools of which are then in a configuration spaced apart from each other. The rollers of the forming rollers are then actuated to rotate in opposite directions and the rollers return the blank to the manipulator subassembly in the rolling direction, the ram of which is then deactivated to follow the movement imparted to the blank by the tools of the two rotating forming rollers. As a result of the movement of the blank in the direction of the manipulator subassembly and after a lateral displacement of the blank, the ram is again pressurized to insert the blank again between the forming rollers for a subsequent rolling step. This adjustment of the rollers is relatively difficult, while the movement of the blank is not really controlled because the ram is a follower when the blank returns to the manipulator subassembly during rolling.

[0007] It is known from CN-B-108296292 how to use a linear motor as an actuator in a rolling mill of a different type from that of the present invention, in which the axis of the rolling tools is slightly inclined with respect to the rolling direction. This rolling mill comprises an axial thrust system and a recovery system located on both sides of the rolling tools. The use of a separate axial thrust system and recovery system is complex and expensive.

[0008] It is also known from FR-A-2390224 how to use a linear motor to drive an automatic manipulator comprising clamping jaws in a separate manipulation system of a rolling mill. The rolling mill itself has no manipulation system, since the manipulation system must be able to move away to provide access to the working area for the tools of the rolling mill. The linear motor is used to drive a sleeve whose movement is synchronized with that of the rollers of the rolling mill, which only makes it possible to accompany the movement of the blank during rolling.

[0009] The present invention most particularly aims to overcome these drawbacks by proposing a new blank rolling mill whose manipulation subassembly makes it possible to control the rolling operation more effectively. SUMMARY

[0010] To this end, the invention relates to a blank rolling mill comprising two forming rolls for shaping a blank, each forming roll being provided with at least one rolling tool and rotating around an axis of rotation by means of at least one respective drive motor. The blank rolling mill further comprises a manipulator sub-assembly for moving the blank relative to the forming rolls, the manipulator sub-assembly comprising a clamp for clamping the blank and a carriage for moving the clamp at least along a rolling direction of the blank. The manipulator sub-assembly comprises at least one linear motor for moving the carriage along the rolling direction. According to the invention, the rolling direction is perpendicular to the axis of rotation of the rolling tools. Moreover, the linear motor is configured for accelerating the blank in a first step to insert the blank between the rolling tools at a speed synchronized with the speed of the rolling tools, and for selectively applying a stretching force on the blank during rolling of said blank in a second step, the stretching force tending to extract the blank from the gap defined between the rolling tools, or a braking force tending to limit the ejection speed of the blank.

[0011] With the invention, the linear speed of the movement of the blank along the rolling direction is defined by the linear motor and can thus be precisely controlled. The precise regulation of the movement of the blank along the rolling direction can be obtained by applying, by means of the linear motor, an additional stretching force or an opposite braking force compared to the force applied on the blank by the rolling tools during rotation. The additional stretching force or braking force results from an electromagnetic force applied between a primary magnetic element and a secondary magnetic element of the linear motor. The force can be precisely and quickly controlled, so that the blank rolling mill of the invention can be adapted to high-speed production.

[0012] According to an advantageous but non-mandatory aspect of the invention, such a blank rolling mill can comprise one or more of the following features, taken separately or according to any technically admissible combination:

[0013] - the carriage can also move along a transverse direction perpendicular to the rolling direction and parallel to the axis of rotation of the forming rolls, while the manipulator sub-assembly comprises at least one linear motor for moving the carriage along the transverse direction.

[0014] - each linear motor comprises a primary magnetic element supplied with an electric current, a secondary magnetic element not supplied with an electric current, and a guide device for guiding the relative translation of the primary and secondary magnetic elements.

[0015] - the guide device comprises at least one rail mounted on a first part of the manipulator sub-assembly and carrying a first of the primary and secondary magnetic elements, and a slider mounted on a second part of the manipulator sub-assembly and carrying a second of the primary and secondary magnetic elements.

[0016] - the guide device comprises two sets of tracks arranged on both sides of the primary and secondary magnetic elements and two sets of sliders arranged on both sides of the primary and secondary magnetic elements.

[0017] - the primary magnetic element of the linear motor for moving the carriage along the rolling direction is mounted on a frame that can move in translation along the transverse direction, while the secondary magnetic element of the linear motor for moving the carriage along the rolling direction is mounted on the carriage.

[0018] - the primary magnetic element of the linear motor for moving the carriage along the transverse direction is mounted on a frame that can move in translation along the transverse direction, while the secondary magnetic element of the linear motor for moving the carriage along the transverse direction is rigidly attached to the fixed structure of the blank rolling mill.

[0019] - the central distance between the rotation axes of the forming rollers can be adjusted by means of a cam mechanism that exerts a force on the forming rollers tending to reduce the central distance and an elastic system that exerts a force on the forming rollers tending to increase the central distance.

[0020] - the carriage carries an electric motor for manipulating the clamp.

[0021] - a damper system is arranged between the output shaft of the electric motor and the manipulation push rod of the opening / closing mechanism of the clamp.

[0022] - the carriage carries an electric motor for angularly orienting the clamp around an axis parallel to the rolling direction.

[0023] - the electric orientation motor controls the angular orientation of the clamp around an axis parallel to the rolling direction within a range, the angular amplitude of the angular orientation depending on the actuation time of the electric orientation motor.

[0024] - the electric orientation motor rotates a hollow shaft, on one end of which the opening / closing mechanism for opening / closing the clamp is mounted, while the electric motor for manipulating the clamp translates a push rod arranged inside the shaft and acting on the opening / closing mechanism of the clamp.

[0025] - each forming roller is rotated around its rotation axis by two electric motors, one of which is mounted near each of the ends of the forming roller.

[0026] - a reduction gear is interposed between the output shaft of each electric motor and the adjacent end of the roller of the forming roller driven by the motor.

[0027] According to a second aspect, the present application relates to a method for controlling a rolling mill of the above type, which method comprises steps implemented by supplying the main magnetic elements of the linear motors, and which comprises:

[0028] - accelerating the blank to insert it between the rolling tools at a speed synchronized with the speed of the rolling tools, and

[0029] - selectively applying on the blank a stretching force tending to extract the blank from the gap defined between the rolling tools, or a braking force tending to limit the ejection speed of the blank. BRIEF DESCRIPTION OF DRAWINGS

[0030] The present application will be better understood and other advantages of the present application will become more apparent when reading the following description of an embodiment of a rolling mill according to the principles of the present application, provided by way of example only and given with reference to the attached drawings wherein:

[0031] [ Figure 1 ] Figure 1 is a perspective view of a blank rolling mill according to the present application;

[0032] [ Figure 2 ] Figure 2 is a perspective view, at the same angle as the rolling mill shown in Figure 1 , with a partial cross-section at the plane II shown in Figure 1 ;

[0033] [ Figure 3 ] Figure 3 is a schematic cross-section along the plane III shown in Figure 1 , when the forming rolls of the rolling mill are in a first configuration;

[0034] [ Figure 4 ] Figure 4 is a cross-section similar to Figure 3 , when the forming rolls are in a second configuration;

[0035] [ Figure 5 ] Figure 5 is a schematic cross-section along the plane V shown in Figure 1 ;

[0036] [ Figure 6 ] Figure 6 is an elevation view of the rolling mill along the arrow VI shown in Figure 1 ;

[0037] [ Figure 7 ] Figure 7 is a bottom perspective view of the manipulator subassembly shown in Figures 1 to 6 ;

[0038] [Figure 8 ] Figure 8 is Figure 7 the manipulator subassembly shown in figure 1 along the direction of the arrow I; Figure 7 is a perspective view, in another angle and in cross section, of the manipulator subassembly shown in figure 1 along the plane VIII;

[0039] [ Figure 9 ] Figure 9 is Figure 7 and Figure 8 the manipulator subassembly shown in figure 1 along the direction of the arrow IX; Figure 7

[0040] [ Figure 10 ] Figure 10 is the end view of the manipulator subassembly shown in figure 1 along the arrow X, without the blank; Figure 7

[0041] [ Figure 11 ] Figure 11 is a schematic view of the four steps of rolling of the blank in the plane of figure 1 ; and Figure 5

[0042] [ Figure 12 ] Figure 12 is another exploded perspective view of the rolling mill shown in figure 1, viewed at a different angle than figure 1. Figure 1 Figures 1 to 11 DETAILED DESCRIPTION

[0043] Figures 1 to 12 The blank rolling mill 2 shown in figure 1 comprises a frame 3 made up of a fixed structure 4 and a removable upper crosspiece 5. The fixed structure 4 supports two guide systems 6 for the vertical movement of an upper shaping roller 7 and a lower shaping roller 8, mounted one above the other, and each provided with a stack 72 and 82 of rolling tools respectively, extending over a portion of the circumference and length of the rollers 74 and 84.

[0044] Each of the stacks 72 and 82 is formed by the juxtaposition of individual tool parts along the roller 74 or 84, working in pairs and intended to hot shape the blank or blank E. The number of individual tool parts in the stacks 72 and 82 is chosen by the user of the rolling mill 2. In the following, for the sake of simplicity, the stacks 72 and 82 of tools are referred to as "tools".

[0045] ​​​​​Each forming roller 7 or 8 is supported relative to the fixed structure 4 by two block bearings, namely a left block bearing 9 and a right block bearing 10. The block bearings 9 and 10 are guided in vertical translation by the guide system 6 and are arranged between two pillars 42 of the fixed structure. Since the crosspiece 5 is removable, the block bearings 9 and 10 can be arranged between the pillars 42 and can be removed during maintenance operations on the rolling mill 2.

[0046] Each block bearing 9 or 10 supports an electric motor 15, the output shaft of which rotates the roller 74 or 84 of the associated forming roller 7 or 8 via a reduction gear 152 integrated into the block bearing. Figure 2 Only one reduction gear 152 is shown, which is associated with the electric motor 15 shown in the upper right corner of the figure. Equivalent reduction gears (not shown in the figure) are associated with the other three motors 15 and are arranged in block bearings 9 or 10 between the output shafts of the motors and the rollers 74 or 84. Thus, each roller 74 or 84 is rotated by two motors 15 via the associated reduction gear 152 about an upper axis of rotation Y7 or a lower axis of rotation Y8, the two axes being parallel to each other.

[0047] In the example described above, the electric motor 15 is of the type sold by SIEMENS under the reference 1PH 8. Other types of motors are also conceivable.

[0048] The different electric motors 15 are controlled by an electronic control unit (not shown) which synchronizes the torques exerted on the same roller 74 or 84 by the two motors 15 arranged close to the two ends of the roller 74 or 84 .

[0049] An orthogonal coordinate system X2, Y2, Z2 is associated with the rolling mill 2, wherein the horizontal axis X2 of the orthogonal coordinate system points to the forming rollers 7 and 8, the axis Y2 of the orthogonal coordinate system is parallel to the rotation axes Y7 and Y8, and the vertical axis Z2 of the orthogonal coordinate system points upwards.

[0050] The heating system 14 partially surrounds each forming roller 7 or 8. More precisely, each heating system 14 surrounds the roller 74 or 84 of the adjacent forming roller 7 or 8 over an angular sector with a vertex angle α equal to approximately 120° and over the length of the tool 72 or 82.

[0051] exist Figures 1 to 6 In the configuration of , each of the rollers 74 and 84 is oriented about its axis of rotation Y7 or Y8 so that the tool 72 or 82 supported by the roller faces the adjacent heating system 14. In this configuration, both heating systems 14 can heat the tool 72 or 82 by radiation. On the other hand, as Figure 2As shown only for the upper forming roll 7, a channel 76 for the circulation of a heat transfer fluid, for example water, is formed inside each of the rolls 74 and 84 and is connected to two rotary seals 16 connected to ducts (not shown) for the introduction and discharge of the heat transfer fluid. The circulation of the heat transfer fluid through the channel 76 can make it possible to cool each of the rolls 74 and 84 during rolling.

[0052] The vertical central distance E78 between the axes Y7 and Y8 is measured parallel to the axis Z2 and is controlled by four wedges 17 that can be moved parallel to the axis X2, each wedge being controlled by means of an electric motor 19 by a screw-nut system 18. The rotary motion of the output shaft of each electric motor 19 is converted into translational motion of the wedge 17 by the associated screw-nut system 18.

[0053] In the example described above, the electric motors are of the type sold by SIEMENS under the reference 1FK7. Other types of motors are also conceivable.

[0054] The wedges 17 are arranged above each of the block bearings 9, 10 of the upper forming roll 7 and below each of the block bearings 9, 10 of the lower forming roll 8.

[0055] Each wedge 17 moves along an axis X17 parallel to the axis X2 and has a cam surface 172 inclined with respect to the axis X17 in the plane of Figure 3 and Figure 4 .

[0056] On the other hand, each block bearing 9 or 10 is equipped with a cam 9C or 10C having a sliding surface that bears against the surface 172 of the wedge 17. For the spacer 10C visible in Figure 3 and Figure 4 , the sliding surface is identified by the reference 10S. The sliding surface of the cam 9C is parallel to the sliding surface 10S of the cam 10C. The sliding surface 10S and the equivalent are also inclined with respect to the axis X17 in the plane of Figure 3 and Figure 4 .

[0057] The inclined surfaces 172 and 10S arranged respectively on the wedges 17 and on the cams 9C and 10C are oriented in such a way that the surfaces of the wedges and of the cams bear against each other and that each wedge exerts a force F17 on the cam 9C or 10C when the wedge 17 is displaced in the direction of the axis X2, the force pushing the block bearings 9 and 10 towards each other, the force tending to reduce the vertical distance between the axes Y7 and Y8.

[0058] On the other hand, two spring assemblies 55 are arranged in housings 56 provided in the block bearings 9 and 10, respectively. The springs 55 exert an elastic force that tends to separate the block bearings vertically. By Figure 3 and Figure 4 the elastic force indicated by the arrows F55 tends to increase the vertical center distance between the axes Y7 and Y8 by default. Thus, when the force for bringing the block bearings closer together is released, the springs 55 move the block bearings 9 and 10 apart vertically, which increases the vertical center distance E78 between the axes Y7 and Y8, and corresponds to a change from the configuration shown in Figure 3 to the configuration shown in Figure 4 .

[0059] The combination of the cam mechanism on the one hand, formed by the components 9C, 10C and 17, and the elastic system on the other hand, formed by the springs 55, is used to control the vertical center distance E78 between the axes Y7 and Y8 precisely by means of the motor 19.

[0060] Preferably, the operation of the electric motor 19 is synchronized to coordinate the movement of the wedge 17 along its translation axis X17. In this way, the block bearings 9 and 10 are prevented from being arranged at an angle between the guide systems 6.

[0061] The electric motor 19 is synchronized by an electronic unit (not shown), advantageously the same unit that controls the electric motor 15.

[0062] The manipulator subassembly 20 is provided to

[0063] - load the blank E (in other words, the billet) between the forming rollers 7 and 8,

[0064] - accompany the ejection movement of the blank in relation to the action of the tools 72 and 82, and

[0065] - displace the blank transversely parallel to the axis Y2 to make the blank cooperate successively with the components of the tools 72 and 82, which are juxtaposed along the rollers 74 and 84.

[0066] The manipulator subassembly 20 is supported by the frame 3 so that it is permanently correctly positioned with respect to the rollers 7 and 8. The manipulator subassembly does not impede access to the rollers, in particular to the tools 72 and 82 of the rollers.

[0067] Figure 11 Four steps of the rolling process by means of the rolling mill 2 of the invention are shown.

[0068] In Figure 11In a first step shown in the upper left part of the drawing, the tools 72 and 82 are respectively opposite the heating system 14 so that the blank E can be inserted into the volume V defined vertically between the rollers 84 and 74. This volume V can be in particular Figure 6 The insertion of the blank E into the volume V takes place in the direction of the arrow F1 , which is parallel to the axis X2 and oriented in the same direction.

[0069] exist Figure 11 In a second step, shown in the upper right part of the drawing, the forming rollers 7 and 8 rotate synchronously about axes Y7 and Y8, respectively, in two opposite directions, indicated by the rotation arrows R7 and R8. This double rotation has the effect of bringing the tools 72 and 82 into contact with the blank E, which then begins a horizontal translation movement parallel to the axis X2, in a direction opposite to the insertion movement, the translation movement being indicated by Figure 11 At the moment when the tools 72 and 82 come into contact with the blank E, the blank E should have been accelerated to be arranged in the correct position along the axis X2 and at a theoretical speed along the axis synchronous with the tools 72 and 82 .

[0070] As the rotational movement of the forming rollers 7 and 8 continues, as indicated by the arrows R7 and R8, the tools 72 and 82 bear firmly against the blank E, which is also plastically deformed and also tends to move in the direction of the arrow F2 towards Figure 11 Left side drive.

[0071] The movement continues from Figure 11 to the step shown in the lower left part of the figure, and then to the step shown in the lower right part of the figure, in which the blank E leaves without contact with the tools 72 and 82, which are still rotating around the axes Y7 and Y8 and are close to reaching the starting position of the movement as shown in the upper left part of the figure again.

[0072] The adjustment accuracy of the vertical center distance E78 between the axes Y7 and Y8 obtained by means of the cam mechanism and the elastic system is used to adjust the Figure 11 The rolling forces exerted by the tools 72 and 82 on the blank E are precisely adjusted between the steps correspondingly shown on the right side of FIG.

[0073] The manipulator subassembly 20 is configured to actively move the blank E in the direction of arrow F1 parallel to the axis X2 for reaching Figure 11 The position shown in the upper left part of the Figure 11 The subsequent steps shown are accompanied by the movement of the blank E under the action of the shaping rollers 7 and 8 .

[0074] once Figure 11the step shown in the lower right part of the figure, the manipulator subassembly 20 can also be used to move the blank E perpendicularly to the plane of the figure, i.e. parallel to the axis Y2, to bring the blank into opposition with the other single part of the tool 72 and 82, thus causing the restart of the cycle with the other part of the tool, as shown in the figure. Figure 11 Figure 11

[0075] The manipulator subassembly 20 comprises a first crosspiece 30 and a second crosspiece 31, which are rigidly supported on two ledges 44 of the fixed structure 4. The crosspiece 31 has a larger cross section than the crosspiece 30, since it supports the means for moving the blank E parallel to the axis Y2.

[0076] The movable assembly 33 is suspended on the crosspieces 30 and 31 by means of a slide 32, which is rigidly attached to a frame 33c of the movable assembly 33 and is designed to move parallel to the axis Y2 along a track 30R, 31R provided on the lower surface of the crosspieces 30 and 31, respectively. The movement of the movable assembly 33 parallel to the axis Y2 and with respect to the crosspieces 30 and 31 is obtained by means of a linear motor 100, which comprises a primary magnetic element 102 attached to the frame 33c of the movable assembly 33, which is supplied with an electric current when the linear motor is operating, to generate a variable magnetic field in a direction parallel to the axis Y2. By having a secondary magnetic element attached to the crosspiece 31, which is rigidly attached to the fixed structure 4 of the rolling mill 2. The linear motor 100 also comprises a secondary magnetic element 104 attached to the crosspiece 31, which is in fact constituted by a plurality of permanent magnets juxtaposed in a direction parallel to the axis Y2. The secondary magnetic element is not supplied with an electric current.

[0077] The supply of the primary magnetic element 102 of the linear motor 100 can be used to exert a magnetic force parallel to the axis Y2 between the elements 102 and 104 of the linear motor 100, which induces a controlled movement of the movable assembly 33 in a transverse direction Y33 below the crosspieces 30 and 31 parallel to the axis Y2.

[0078] The track 31R is arranged on both sides of the magnetic elements 102 and 104 of the linear motor 100 in a direction parallel to the axis X2, as is the slide 32. The above facilitates the translation and improves the accuracy of control of the position of the movable assembly 33 with respect to the crosspiece 31.

[0079] ​​The movable assembly 33 comprises a carriage 35 to which the frame 33C is connected by means of a system of slides 34 rigidly attached to the carriage 35, which slides along a rail 33R provided on the frame 33C. The longitudinal direction of the rail 33R is parallel to the axis Y2, so that the motion of the carriage 35 with respect to the frame 33C of the movable assembly 33 takes place along a direction perpendicular to the direction of motion of the movable assembly 33 with respect to the crossbeams 30 and 31.

[0080] The second linear motor 200 is used to control the motion of the carriage 35 with respect to the frame 33C of the movable assembly 33 and comprises a primary magnetic element 202, which is mounted on a portion of the frame 33C and is supplied with electric current when the linear motor 200 is active, and a secondary magnetic element 204, which is mounted on the carriage 35 and is not supplied with electric current and is in fact constituted by a plurality of permanent magnets juxtaposed along a direction parallel to the axis X2. The electric current supplied to the primary magnetic element 202 is used to generate a magnetic force between the elements 202 and 204, which has the effect of displacing the carriage 35 parallel to the axis X2 with respect to the frame 33C.

[0081] The rail 33R is arranged on both sides of the magnetic elements 202 and 204 of the linear motor 200 along a direction parallel to the axis X2, as is the slide 34. The above facilitates translation and improves the accuracy of control of the position of the carriage 35 with respect to the frame 33C of the movable assembly 33.

[0082] The carriage 35 supports a workpiece clamping system 36 for manipulating the blank E. The workpiece clamping system 36 comprises a hollow rod 38 and two bearings 37 rigidly connected to the carriage 35. A clamp 39 comprising two jaws 39A and 39B and a drawbar mechanism 40 also belong to the workpiece clamping system 36 and are mounted at a first end of the rod 38. The drawbar mechanism 40 is configured for converting the translational motion of a push rod 54 arranged inside the rod 38 into a motion that brings the jaws 39A and 39B closer together / moves them apart. The clamping rod 38 is cantilevered mounted in one of the bearings 37 from a second end of the clamping rod opposite the end that supports the assembly 39 and 40.

[0083] The second end of the clamping lever 38 supports a pulley 38A surrounded by a belt 45 which also passes around a pulley 44A rotated by an electric step motor 44 which forms the electric motor for angularly orienting the clamp 39. In fact, by actuating the electric motor 44 it is possible to rotate the pulley 38A and thus the clamping lever 38 about its longitudinal axis X38 parallel to the axis X2. In this way it is possible to angularly orient the lever mechanism 40 and thus the blank E held by the clamp 39 about the axis X38. Since the orientation of the blank E about the axis X38 is controlled by means of the electric motor 44, the angular amplitude of the adaptive movement of the orientation of the blank about the axis is selected by the user of the blank rolling mill 2, since once the electric motor 44 has been selected, the orientation depends only on the duration of the actuation of the motor. The angular amplitude is not limited by the stroke of the ram. The blank rolling mill 2 of the application therefore has greater flexibility compared to some known blank rolling mills in which the ram is used to rotate the blank about the central axis of the clamp by 90°, since it enables the blank E to be angularly moved about the axis X38 by an amplitude freely selected by the user, in which the amplitude can even be greater than 360°.

[0084] The carriage 35 also carries an electric step motor 42 which drives a screw-nut system 41 which converts the rotational movement of the output shaft 42A of the motor 42 into translational movement of the push rod 54 along the axis X38. Therefore, by means of the motor 42, by moving the push rod 54 along the axis X38 to actuate the lever mechanism 40, it is possible to control the opening-closing movement of the clamp 39.

[0085] The step motors 42 and 44 are controlled by an electronic unit (not shown) which can be the same as or different from the unit which drives the motors 15 and 19.

[0086] A spring system 43 is interposed between the screw-nut mechanism 41 and the push rod 54. The spring system is used to absorb any shocks in the screw-nut system 41 while the jaws 39A and 39B of the clamp 39 have reached the position in which the blank E is clamped. The spring system 43 enables elastic coupling between the nut of the screw-nut system 41 and the push rod 54 in the closing direction of the clamp 39.

[0087] Thanks to the use of the linear motor 200, the movement of the carriage 35 parallel to the axis X38, and therefore of the clamp 39 supported by the carriage, is controlled in a precise manner along the direction of the arrow Fl in Figure 11 and in the direction of the arrow F2 in Figure 11 during the pushing back of the blank E towards the crosspiece 30 during rolling of the blank. More specifically, the linear motor 200 is used to control the movement of the carriage 35 parallel to the axis X38 in a precise manner along the direction of the arrow Fl inFigure 11 between the first step, illustrated in the upper left part of the figure, and the second step, illustrated in the upper right part of the figure, the blank is accelerated along the rolling direction X38 to insert the blank between the tools 72 and 82 and to arrange the blank in the correct position along the axis X2 and at a speed along said axis synchronized with the speed of the tools 72 and 82. During the movement of the blank along Figure 11 During the movement of the blank E in the direction of the arrow F1, in particular during the insertion of the blank between the tools 72 and 82, the acceleration force of the blank is obtained according to the supply of the primary magnetic element 202 of the linear motor 200. According to the second step, illustrated in the upper right part of the figure, according to the electric supply of the primary magnetic element 202 of the linear motor 200, the motor can exert a stretching force tending to extract the blank E from the gap defined between the tools 72 and 82 or a braking force tending to limit the ejection speed of the blank E along the rolling direction defined by the axis X38. In all cases, the linear speed of the movement of the blank E along the rolling direction is controlled by the linear motor. Therefore, it is possible to know the linear speed precisely without the need to make estimates based on the rotational speed of the forming rollers 7 and 8. Figure 11 According to the second step, illustrated in the upper right part of the figure, according to the electric supply of the primary magnetic element 202 of the linear motor 200, the motor can exert a stretching force tending to extract the blank E from the gap defined between the tools 72 and 82 or a braking force tending to limit the ejection speed of the blank E along the rolling direction defined by the axis X38. In all cases, the linear speed of the movement of the blank E along the rolling direction is controlled by the linear motor. Therefore, it is possible to know the linear speed precisely without the need to make estimates based on the rotational speed of the forming rollers 7 and 8.

[0088] The precise control of the linear speed of the movement of the blank E along the rolling direction parallel to the axis X2 is used to optimize the rolling effect obtained between the tools 72 and 82. Moreover, the low inertia of the linear motor 200, compared to the inertia of a ram or a traditional electric motor, makes it possible to achieve high-speed movements of the carriage 35 and of the clamp 39 along the axis X38. Therefore, the optimized use of the linear motor 2, in particular the generation of the aforementioned acceleration, stretching force and braking force, makes it possible to improve the quality of the rolled product obtained with the blank mill 2.

[0089] In fact, during the rolling of the blank, the pulling or braking of the blank between the rollers improves the quality of the rolling while maintaining a high productivity. For example, the stretching force exerted on a product with a small cross section between the rolling tools 72 and 82, at the rolling exit of the rolling tools, improves the linearity of the product. On the other hand, the braking of a product with a large cross section between the rolling tools, at the end of the rolling of the rolling tools, improves the filling of the rolling profile defined between the tools.

[0090] On the other hand, the linear motor 100 is used to move the movable assembly 33 and the elements supported by the movable assembly, including the carriage 35 and the clamp 39, quickly along the transverse direction Y33. In this way it is possible to quickly realign the blank E with a portion of the tools 72 and 82 for a subsequent rolling step.

[0091] Therefore, the linear motors 100 and 200 contribute to reducing the cycle time of the rolling of the blank E in the blank rolling mill 2. The motors are controlled by an electronic unit (not shown), which can be the same as or different from the unit that controls the motors 15, 19, 42 and 44.

[0092] The linear motors 100 and 200 can be commercial products, for example the motors sold by SIEMENS under the reference 1FN3450-2WE00-0BA3 or 1FN3300-2WE00-0BA3, or in particular for the purposes of the present application, devices developed on the same principle.

[0093] In the embodiment shown, no linear motor is provided in the interface region between the movable assembly 33 and the crosspiece 30. However, it is also possible to include a linear motor in the interface region between the movable assembly and the crosspiece. The use of one or two linear motors and the choice of the position of these linear motors are made taking into account the moving mass of the movable assembly 33. According to a variant (not shown) of the application, the linear motor 100 can be arranged near the crosspiece 30, while the linear motor is not arranged near the crosspiece 31.

[0094] Even if the use of the linear motor 100 is particularly advantageous, according to a variant (not shown) of the application, it is possible to envisage the use of a rotary electric motor and a rotation / linear motion conversion system known per se to drive the movable assembly 33 parallel to the axis Y2.

[0095] According to another variant (not shown) of the application, the guide tracks of the linear motors 100 and 200 can be provided respectively on the frame 33C and on the carriage 35, while the sliders are provided respectively on the crosspiece 31 and on the frame 33C. According to another variant (not shown), the mounting of the magnetic elements 102 and 104 can be reversed, the primary magnetic element 102 being mounted on the crosspiece 31 and the secondary magnetic element 104 being mounted on the frame 33C. Similarly, the mounting of the magnetic elements 202 and 204 can be reversed, the primary magnetic element 202 being mounted on the carriage 35 and the secondary magnetic element 204 being mounted on the frame 33C.

[0096] According to another variant (not shown) of the application, the reduction gear 152 can be replaced by a belt system, or even removed if the rotational speed of the output shaft of the motor 15 is compatible with the direct drive of the rollers 74 and 84. According to another variant (not shown) of the application, the forming rollers 7 and 8 are each rotated by a single electric motor 15.

[0097] In a variant (not shown) of the application, the number of springs 55 can be different from 4. Furthermore, the springs 55 of the elastic system can be replaced by other elastic assemblies, for example elastomeric blocks or gas springs.

[0098] In a variant of the application (not shown), the movement axis X17 of the wedge 17 can be parallel to the axis Y2 or inclined with respect to the axes X2 and Y2, while remaining perpendicular to the axis Z2. According to a further variant of the application (not shown), the forming rollers 7 and 8 are not arranged one above the other, but side by side. In this case, the central distance between the rotation axes of the forming rollers is horizontal, and the rolling direction is vertical. The fixed structure 4 and the manipulator subassembly 20 of the blank mill 2 are then adjusted accordingly.

[0099] The aforementioned embodiments and variants can be combined to produce new embodiments of the application as defined in the attached claims.

Claims

1. A billet rolling mill (2), comprising two forming rollers (7, 8) for forming a billet (E) to be formed and a manipulator subassembly (20) for moving the billet relative to the forming rollers, each forming roller being provided with at least one rolling tool (72, 82) and being rotated about a rotation axis (Y7, Y8) by at least one corresponding drive motor (15), the manipulator subassembly comprising a clamp (39) for clamping the billet, a bracket (35) for moving the clamp at least along a rolling direction (X38) of the billet, and at least one linear motor (200) for moving the bracket (35) along the rolling direction (X38), wherein The rolling direction (X38) is perpendicular to the rotation axis (Y7, Y8) of the rolling tools (72, 82), and the billet rolling mill is characterized in that the linear motor (200) is configured to accelerate the billet (E) in a first step to insert the billet between the rolling tools (72, 82) at a speed synchronized with the speed of the rolling tools, and the linear motor is configured to selectively apply a tensile force or a braking force to the billet (E) during the rolling of the billet in a second step, the tensile force tending to remove the billet from the gap defined between the rolling tools (72, 82) and the braking force tending to limit the ejection speed of the billet.

2. The billet rolling mill according to claim 1, characterized in that The carriage (35) is also movable in a transverse direction (Y33) perpendicular to the rolling direction (X38) and parallel to the rotation axes (Y7, Y8) of the forming rollers (7, 8), and the manipulator subassembly (20) includes at least one linear motor (100) for moving the carriage in the transverse direction.

3. The billet rolling mill according to claim 1, characterized in that Each linear motor (100, 200) includes a primary magnetic element (102, 202) supplied with current, a secondary magnetic element (104, 204) not supplied with current, and a guide device (31R, 32; 33R, 34) for guiding relative translation of the primary magnetic element and the secondary magnetic element.

4. The billet rolling mill according to claim 3, characterized in that The guiding device comprises at least one track (31R, 33R) mounted on a first part (31, 33) of the manipulator subassembly (20), the at least one track carrying one of the primary magnetic element and the secondary magnetic element, and a slide (32, 34) mounted on a second part (33, 35) of the manipulator subassembly (20), the at least one track carrying one of the primary magnetic element and the secondary magnetic element, and the slide carrying the other of the primary magnetic element and the secondary magnetic element.

5. The billet rolling mill according to claim 4, characterized in that The guiding device comprises two groups of tracks (31R, 33R) and two groups of sliding members (32, 34), wherein the two groups of tracks are arranged on both sides of the corresponding primary magnetic element (102, 202) and the secondary magnetic element (104, 204), and the two groups of sliding members are arranged on both sides of the corresponding primary magnetic element and the secondary magnetic element.

6. The billet rolling mill according to claim 2, characterized in that Each linear motor (100, 200) includes a main magnetic element (102, 202) supplied with current, a secondary magnetic element (104, 204) not supplied with current, and a guide device (31R, 32; 33R, 34) for guiding the relative translation of the main magnetic element and the secondary magnetic element. The main magnetic element (202) of the linear motor (200) for moving the bracket (35) along the rolling direction (X38) is mounted on a frame (33C) capable of translational movement along the transverse direction (Y33), and the secondary magnetic element (204) of the linear motor (200) for moving the bracket along the rolling direction is mounted on the bracket (35).

7. The billet rolling mill according to claim 2, characterized in that Each linear motor (100, 200) includes a main magnetic element (102, 202) supplied with current, a secondary magnetic element (104, 204) not supplied with current, and a guide device (31R, 32; 33R, 34) for guiding the relative translation of the main magnetic element and the secondary magnetic element, the main magnetic element (102) of the linear motor (100) for moving the bracket (35) along the transverse direction (Y33) is mounted on a frame (33C) capable of translational movement along the transverse direction, and the secondary magnetic element (104) of the linear motor (100) for moving the bracket along the transverse direction is rigidly attached to the fixed structure (4) of the billet rolling mill (2).

8. The billet rolling mill according to any one of claims 1 to 7, characterized in that The center distance (E78) between the rotation axes (Y7, Y8) of the forming rollers (7, 8) can be adjusted by means of a cam mechanism (9C, 10C, 17), which exerts a force (F17) on the forming rollers tending to reduce the center distance, and an elastic system (55), which exerts a force (F55) on the forming rollers tending to increase the center distance.

9. The billet rolling mill according to any one of claims 1 to 7, characterized in that The bracket (35) carries an electric motor (42) for operating the clamp, and a damper system (43) is arranged between an output shaft (42a) of the electric motor (42) and a push rod (54) for operating an opening or closing mechanism (40) of the clamp (39).

10. The billet rolling mill according to any one of claims 1 to 7, characterized in that The carriage (35) carries an electric orientation motor (44) for angularly orienting the clamp (39) about an axis (X38) parallel to the rolling direction.

11. The billet rolling mill according to claim 10, characterized in that The electric orientation motor (44) controls the angular orientation of the clamp (39) about the axis (X38) parallel to the rolling direction within a range, the angular amplitude of the angular orientation depending on the activation time of the electric orientation motor.

12. The billet rolling mill according to claim 10, characterized in that The bracket (35) carries an electric motor (42) for operating the clamp (39), and the electric directional motor (44) rotates the hollow rod (38), an opening or closing mechanism (40) for opening or closing the clamp (39) is mounted at one end of the hollow rod, while the electric motor (42) for operating the clamp (39) translates a push rod (54) which is arranged inside the hollow rod and acts on the opening or closing mechanism (40) of the clamp (39).

13. The billet rolling mill according to any one of claims 1 to 7, characterized in that Each forming roller (7, 8) is rotated about its axis of rotation (Y7, Y8) by two electric motors (15) which are mounted near the ends of the respective forming roller.

14. The billet rolling mill according to claim 13, characterized in that A reduction gear (152) is interposed between the output shaft of each electric motor (15) and the adjacent ends of the rollers (74, 84) of the forming rollers (7, 8) driven by the electric motor.

15. A method for controlling a billet rolling mill, the billet rolling mill comprising two forming rollers (7, 8) for forming a billet (E) to be formed and a manipulator subassembly (20) for moving the billet relative to the forming rollers, each forming roller being provided with at least one rolling tool (72, 82) and being rotated about a rotation axis (Y7, Y8) by at least one corresponding drive motor (15), the manipulator subassembly comprising a clamp (39) for clamping the billet, a bracket (35) for moving the clamp at least along one rolling direction (X38) of the billet and at least one linear motor (200) for moving the bracket (35) along the rolling direction (X38), characterized in that The method comprises steps implemented by supplying a primary magnetic element (202) of the linear motor (200), and includes: - accelerating the blank (E) in a first step in order to insert it between the rolling tools (72, 82) at a speed synchronized with the speed of the rolling tools, and - In a second step, a tensile force or a braking force is selectively applied to the blank (E) during its rolling, the tensile force tending to remove the blank from the gap defined between the rolling tools (72, 82) and the braking force tending to limit the ejection speed of the blank.

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