EP3389885B1

EP3389885B1 - Automatic detection of matrix unit

Info

Publication number: EP3389885B1
Application number: EP16831739.4A
Authority: EP
Inventors: Davide TURLA
Original assignee: Turla Srl
Current assignee: Turla Srl
Priority date: 2015-12-16
Filing date: 2016-12-15
Publication date: 2019-10-02
Anticipated expiration: 2036-12-15
Also published as: WO2017103828A1; EP3389885A1; US20180369890A1; ITUB20159680A1

Description

The present invention relates to a device for automatically detecting the size of a matrix stack on an extrusion press for aluminum or other metals.
At the end of an extrusion process of metal section bars, part of a billet remains in contact with a press matrix and must be removed before starting a new extrusion process because any slag present in the slab may concentrate therein. Removing the butt of the metal billet is fundamental to obtain always optimal extrusion products; the incomplete removal of the billet residues and/or an inaccurate cut on the matrix may cause problems during the next extrusion cycle.
Shears, which are fitted directly on the press at the matrix, are used to solve this problem. At the end of each extrusion cycle, the shear removes the billet butt from the matrix.
Conventional shears are mounted directly over the matrix with one blade oriented towards the bottom of the press; at the end of the extrusion cycle, the blade descends and cuts the billet butt.
One of the main problems of conventional shears is certainly accuracy; the shear must remove all the billet which remained in contact with the matrix as to not invalidate the next extrusion cycle, but at the same time the shear must not touch the extrusion matrix to prevent damaging it.
Adjusting the distance between the shear blade and the matrix is thus fundamental. In common practice, the distance of the blade from the matrix is calibrated manually in occasion of stops for maintenance.
The distance between the blade and the matrix may vary as a consequence of thermal variations to the matrix itself or to different matrix lives; accurate adjustment, which may be performed multiple times during the extrusion process and which does not envisage the intervention of an operator is thus necessary.
US2014/0260488A1 , on which the preamble of claim 1 is based, describes an automatic adjustment system of a shear on an extrusion press. In particular, such system envisages that the shear blade is positioned at a safe distance from the matrix each time; such distance may vary after a matrix change which may imply fluctuations of the thickness of the matrix used. This operation is carried out by letting the cutting guide, which rests on the matrix, slide when is hot; the distance between the shear blade and the matrix is adjusted by means of a shim positioned between the blade and the shear guide. This procedure makes it possible to adjust the distance without a direct intervention by the operator.
The structure of the cutting cylinder, to which the blade is connected, envisages a pin at its upper end, which pin either permits or blocks the inclination of the blade. To adjust the distance between the blade and the matrix, the system envisages that the blade is inclined until it touches the matrix. After having removed the billet, the blade returns to the initial position over the matrix.
Disadvantageously, the cutting cylinder may associate different inclinations to adapt to the different matrixs and over time requires supplementary maintenance which must result in costs for personnel and machine downtime.
Another advantage is in that after having removed the billet butt, the shear returns to the initial position with a movement which is equal and contrary to the shearing position without moving away from the matrix. Any metal residues which may be deposited on the shear blade could come into contact with the matrix, thus damaging it.
WO2013/108222 describes a shear for removing the non-extruded material butt mounted over the extrusion matrix. The shear is mounted on an axis orthogonal with respect to the extrusion axis. The cut follows a preset horizontal axis on the cutting axis so as to remove the billet butt accurately and not to score the matrix.
The shear is made to slide within the guides so as to predetermine the exact cutting position. Once the ideal position for the cut has been chosen, the position is blocked and cannot be modified during the processing steps.
Disadvantageously, the shear of the present invention envisages a complex setting of the cutting position of the shear with personnel costs which can increase according to the extrusion process.
Furthermore, after the cut, the shear returns to its initial position by sliding vertically near the extrusion matrix. Any remaining small metal parts of the shear could damage the matrix.
US2014/0250967 describes a cutting mechanism for removing the non-extruded billet part. The system envisages that a shear is mounted over the extrusion matrix. The shear moves vertically and horizontally with respect to the extrusion axis. The distance between the matrix and the blade may be set to different preset values.
Disadvantageously, the distance between the shear blade and the matrix is preset to standard values not allowing an accurate cut of the material remaining on the matrix.
US4593552 describes a mechanism for removing the non-extruded portion of a billet. A shear is mounted on the press so that it can move with respect to the extrusion plane so as to remove the billet portion from the matrix. The shear blade is adjusted to remove the billet and pass near the matrix.
US8490453B2 describes a cutting mechanism for removing the non-extruded portion of a billet. The shear is supported by a cylinder and a piston allows the movement of the shear in a guide.
It is the object of the present invention to have an extrusion press with a shear capable of accurately removing the non-extruded billet portion.
It is another object of the present invention to have an extrusion press with a shear capable of moving safely near the extrusion matrix.
It is a further object that of having an extrusion press with a shear that can be adjusted accurately according to the extrusion matrix in use.
It is an additional object that of having an extrusion press with a shear that can be adjusted and moved with different systems.
Such an object is achieved by a shear unit as described in claim 1 and by an extrusion press as described in claim 2.
It is yet another object to have a shear for extrusion presses capable of accurately removing the billet which remains stuck to the press matrix.
It is yet another object to have a shear for extrusion presses capable of moving without scoring the press matrix.
It is a further object to have a shear for extrusion presses which can be adjusted and moved by means of a different adjustment systems.
It is the object of the present invention also a method for adjusting and moving the shear for an extrusion press which allows a fine adjustment of the shear and vertical and horizontal movements of the shear to prevent damage to the extrusion press matrix and to remove the possible residues of the billet completely.
In accordance with the invention, such an object is achieved by the method described in claim 6.
These and other features of the present invention will become more apparent from the following detailed description of the example of practical embodiment illustrated by way of non-limitative example in the accompanying drawings, in which:

Figure 1 shows a side view of a shear for extrusion presses in a starting position;
Figure 2 shows a side view of a resetting mechanism of the shear;
Figure 3 shows a side view of a shear for extrusion presses in a resetting position;
Figure 4 shows a side view of a shear for extrusion presses in a removing position after resetting with an enlarged portion in a circle A;
Figure 5 shows a side view of a shear for extrusion presses in a return to starting position;
Figure 6 shows a side view of a shear for extrusion presses in a start of shearing position;
Figure 7 shows a side view of a shear for extrusion presses in a shearing position;
Figure 8 shows a side view of a shear for extrusion presses in a removing position after shearing;
Figure 9 shows a side view of a shear for extrusion presses in a return to starting position after shearing;
Figure 10 shows a side view of a shear for extrusion presses in a return to a predetermined distance position.

Figure 1 shows the front of a press 1 comprising a shearing unit with a shear 2, an adjustment mechanism 3 of the shear 2, a matrix 11 and a reaction plate 10 of the press 1.
The press 1 of the present invention is a conventional press 1 comprising a punch adapted to press on a metal billet, preloaded on the press 1, to obtain extruded metal section bars following the passage inside the matrix 11.
The punch is operated by a hydraulic system, e.g. by means of cylinders, which are actuated, in turn, by a control fluid via a guiding circuit. The control fluid is pushed within the guiding circuit by at least one pump, e.g. a piston or gear pump.
As shown in figure 1, the shear 2 is mounted on the press 1 to separate the non-extruded end portion of the billet after extrusion. The shear 2 is connected to the press 1 so that it can perform both horizontal and vertical movements. It is very important for both the vertical and horizontal movements of the shear 2 to be finely adjusted to prevent damaging the press 1, in particular the matrix 11.
The shear 2 comprises a slide blade holder 24 and a blade 21. The metal material structure 20 connects the shear 2 to the press 1. Said structure 20 has a triangular shape; one of the two three sides of the structures 20 is connected to the shear 2 and another side of the structure 20 is connected to the press 1. Said structure 20 is adapted to slide within sliding guides of the press 1 allowing the shear 2 to move horizontally.
The shear 2 is fixed to the press 1 so that the blade 21 of the shear 2 is facing towards a lower portion of the press 1, slightly over the matrix 11.
The slide blade holder 24 is adapted to contain the blade 21 of the shear 2 and to slide within the guides 25 of the press 1. Said guides 25 extend longitudinally from the slide blade holder and allow a vertical sliding of the slide blade holder 24 and of the blade 21.
An actuator 22 for actuating the blade 21 is fixed over the shear 2 and controls the vertical movements thereof. In particular, the actuator 22 maintains the shear in a distanced position from the matrix 11 during the extrusion process, while it allows the shear 2 to move and remove the bottom of the billet remained stuck to the matrix 11 at the end of the extrusion process.
The vertical sliding of the shear 2 is controlled by means of a hydraulic circuit, a control fluid maintains in under pressure the cylinders which control the movement of the shear 2 and the return of the shear 2 in distanced position from the matrix 11, such movements are controlled by means of the transducer 23.
The horizontal sliding of the shear 2 is possible by virtue of an adjustment mechanism 3 of the shear 2 and a removal actuator 36. The adjustment mechanism 3 is adapted to adjust the distance of the blade 22 from the matrix 11, said adjustment is very important to prevent the blade 22 from damaging the matrix 11 and the adjustment is in the order tenths of a millimeter. Once the distance between the blade 22 and the matrix 11 has been adjusted, the distance is kept stable until the matrix 11 is changed.
The removal actuator 36, instead, it used to remove the blade 22 from the matrix 11 whenever the blade 22 has removed a billet part remained on the matrix 11. The actuator 36 moves the blade 22 by a fixed distance which is not adjusted and which is in the order of centimeters.
As shown in figure 2, the adjustment mechanism 3 of the position of the shear 2 is connected to the structure 20.
The adjustment mechanism comprises an electric motor 31, a worm screw 32, a nut screw 33, adjusting slide plates 34, and a cylinder lock 37. The adjustment mechanism 3 is adapted to adjust the distance between the blade 21 of the shear 2 and the matrix 11 of the press 1. Said adjustment is carried out when an extrusion process has ended and/or it is necessary to change the matrix stack 11 of the press 1.
The electric motor 31, integral with the reaction plate 10 of the press 1 is adapted to actuate the rotation of the worm screw 32. The nut screw 33 is integral with the structure 20 and at least one adjusting slide plate 34. The slide plate 34 is adapted to slide along a guide 340. The rotation of the electric motor 31 is adapted to turn the worm screw 32 and make the worm screw 33 slide with the adjusting slide plate 34; said sliding of the screw nut 33 is adapted to cause the horizontal movement of the shear 2. The electric motor 31 is integral with the reaction plate 10 of the press 1 and remains static, while the adjusting slide plate 34, integral with the worm screw 33, is adapted to slide along the guide 340 following the rotation of the worm screw 32 actuated by the electric motor 31.
The removal actuator 36 comprises a rear attachment 360 integral with the adjusting slide plate 34, a cylinder 362 and a piston 361.
The piston 361 is adapted to slide within the cylinder 362; one end 363 of the piston 361 is integral with a plate 364 anchored to the shear-to-press connecting structure 20. The sliding of the piston 361 within the cylinder 362 is adapted to cause the horizontal movement of the structure 20 and thus of the shear 2. During the step of adjusting of the distance between the blade 22 and the matrix 11, by means of the activation of the electric motor 31 and the sliding of the plates 34, the piston 361 is pressurized, i.e. stopped with respect to the cylinder 362, so that the structure 20 can move only after the sliding of the adjustment plates 34 and not following the sliding of the piston 361 within the cylinder 362.
A cylinder lock 37, adapted to press the adjusting slide plate against the guide 340, thus locking its sliding, is positioned at the end of the adjusting slide plate 34.
The cylinder lock 37 is integral with the press 1 and a single-acting hydraulic cylinder with spring return. Once the distance between the shear 2 and the matrix 11 is adjusted, a hydraulic pressure is applied and the cylinder lock 37 moves downwards thus pressing the adjusting slide plate 34 against the slide 340 and locking its sliding. The hydraulic fluid for feeding the cylinder lock 37 comes from a press pump 1, being said cylinder lock 37 integral with the reaction plate 10 of the press 1.
With regards to operation, once the extrusion process has ended, the press 1 is stopped and the matrix 11 must be replaced. After having loaded the matrix 11 on the press 1, said matrix is blocked by means of specific cylinder locks. The slide blade holder 25 and the blade 21 are taken to the matrix 11 by operating with the shearing actuator 22, the position of which is controlled by the linear transducer 23. Hydraulic pressure is removed from the cylinder lock 37, thus allowing the movement of the adjusting slide plate 34 by means of the electric motor 31, which is supplied again and by means of the worm screw 32 and the nut screw 33, moves the blade 21 to the matrix 11 until they come into contact (Figure 3). The sliding of the adjusting slide plate 34 causes the movement of the structure 20 because said structure 20 is connected to said adjusting slide plate 34 by means of the plate 364. The distance between the blade 21 and the matrix 11 of the press 1 is reset in this manner. The contact between the blade 21 and the matrix 11 is monitored by means of torque control of the electric motor 31.
The electric motor 31 is supplied again and, by means of the worm screw 32 and the nut screw 33, moves the sliding adjustment plate 34 so as to remove the blade 21 and the blade holder 24 from the matrix 11 (circle A in Figure 4).
The sense of rotation of the electric motor 31 is thus inverted to detach the blade 21 from the matrix 11 by a distance that varies from 0.5 to 3 tenths of a millimeter (Figure 4).
A multiturn absolute encoder integrated in the electric motor 31 detects the measurement of the distance between the matrix 11 and the blade 21. The absolute encoder makes it possible to always know the position of the adjusting slide plate 34 and, even if there is no electricity, no additional resetting will be needed when the electricity is re-established. The cylinder lock 37 is made to descend on the adjustment plate 34, thus pressing it against the guide 340 and blocking the sliding thereof. In this manner, the shear is adjusted and blocked on the measurement of the matrix 11 loaded on the press 1. The cylinder lock 37 will thus remain blocked until a new measuring cycle of the matrix 11.
By operating with the shearing actuator 22, the slide blade holder 24 is lifted up completely, taking it the starting position (Figure 5).
At the end of the extrusion cycle, the press 1 makes it possible to load a new billet to be extruded. The end part of the extruded billet 100 remain attached to the matrix 11 and must be removed by means of shearing.
The blade 21 of the shear 2, previously reset as described above, is in the starting position (Figure 6). The shearing actuator 22 is actuated and the blade 21 descends downwards removing the end part of the billet which was not extruded 100 (Figure 7). The auxiliary device makes it possible to detach any parts of the billet 100 which could remain stuck to the blade 21 of the shear 2.
The hydraulic pressure of the piston 361 is decreased, the piston 361 returns into the cylinder 362, and the structure 20 thus moves in direction opposite to the matrix 11 (Figure 8).
As shown in Figure 9, the movement of the structure 20 caused by the decrease of the hydraulic pressure in the cylinder 362, does not cause any movement of the sliding plates 34 which remain blocked by the cylinder lock 37; the movement only concerns the structure 20. Once the pressure is restored in the cylinder 362, the cylinder 361 protrudes thus pushing out the structure 20 into its initial position previously adjusted by means of the electric motor 31 and the worm screw 32.
In this manner, it is ensured that the blade 21 does not slide on the matrix 11 ruining the newly sheared surface during the step of returning to the starting position (Figure 10).
The horizontal movement caused by the removal actuator 36 does not modify the preset distance between the blade 21 and the shear 2 because the adjusting slide plate remains always blocked by the cylinder lock 37. The only movement which occurs is that of the removal actuator 36, which moves the structure 20 and thus causes the horizontal movement of the shear 2.
The shearing actuator is actuated again, the blade 21 moves up again to starting position (Figure 10). The removal actuator 36 fully extends, the piston 361 fully exits from the cylinder 362 and the blade 21 is at the predetermined distance from the matrix 11 again (Figure 11).
Advantageously, the shear 2 may remove the billet with an accuracy necessary not to damage the matrix 11 and not to leave metal residues.
Another advantage is in the adjustment of the shear 2 which may be performed before the beginning of the extrusion cycle and allows the rapid adjustment of the distance of the blade 21 to the matrix 11.
Again another advantage is given by the horizontal movement of the shear 2 after the removal of the end part of the billet, said movement guarantees that the blade does not damage the matrix.
Again another advantage is that only the initial adjustment is performed by means of an electric motor; all the other press movements are carried out using a hydraulic circuit.
Such contrivance makes it possible to adopt an electric motor of lower power and smaller size (being used only to move the mass of the shear off cycle), so as to provide more sensitivity during matrix stack detection by means of torque control.
The translation movements of the mass of the shear during the working cycle, being these performed by the hydraulic cylinder, make it possible to move the considerable mass quickly by means of a compact actuator.

Claims

Shearing unit for extrusion presses, comprising:
- a shear (2) comprising a blade (21) and a slide blade holder (24), the slide blade holder (24) being suitable for holding the blade (21) and for sliding vertically within the guides (25) of a shear-to-press connecting structure (20);

- a shearing actuator (22) suitable for adjusting the vertical movements of the shear (2);

- a linear transducer (23) suitable for controlling the position of the shearing actuator (22);
characterized by further comprising an adjustment mechanism (3) for the shear (2), comprising a motor (31) suitable for adjusting the distance between the blade (21) and the matrix (11) of the press (1) before the start of a process of extrusion, a cylinder lock (37) for blocking said distance, and a removal actuator (36) suitable for moving away the shear (2) from a matrix (11) of the press (1) after shearing.
Press (1) for the extrusion of non-ferrous metal section bars comprising a matrix (11) and a shearing unit according to claim 1.
Press (1) according to claim 2, characterized in that the adjustment mechanism (3) for the shear (2) comprises at least a worm screw (32) connected to the motor (31), at least a nut screw (33) and at least one adjusting slide plate (34).
Press (1) according to claims 2 or 3, characterized in that the adjustment mechanism (3) for the shear (2) is connected to the shear (2) by means of said press-to-shear connecting structure (20).
Press (1) according to one of claims 2-4, characterized in that the motor (31) is an electric motor comprising an encoder suitable for detecting the position of the blade (21).
Method for removing a terminal part of a billet in an extrusion press (1), characterized in that:
- a first step for adjusting the distance between a shear (2) and a matrix (11) comprises moving the shear (2) vertically up to the height of the matrix (11) of the press (1),
move horizontally the shear (2) up to which a blade (21) of said shear (2) comes into contact with the matrix (11) of the press (1),
remove the blade (21) of the shear (2) from the matrix (11) of the press (1) for a said distance,
record the distance between the blade (21) and the matrix (11); and

- a second step of shearing comprises vertically moving the shear (2) for the removal of the terminal part of an extruded billet,
move horizontally the shear (2) by means of a removal actuator (36) to move away the blade (21) of the shear (2),
vertically moving the shear (2) to return to a starting position,
move horizontally the shear (2) to return to the recorded distance between the matrix (11) and the blade (21).
Method according to claim 6, characterized in that the adjustment of the distance between the blade (21) of the shear (2) and the matrix (11) of the press (1) comprises the following steps:
actuating a motor (31) integral with a worm screw (32) connected in turn with a nut screw (33),

horizontal movement of said nut screw (33) positioned on at least one adjusting slide plate (34),

horizontal movement of a structure (20) integral with the shear (2) and the nut screw (33),

block of said at least one adjusting slide plate (34) with a cylinder lock (37).
Method according to claim 6, characterized in that the distance between the blade (21) of the shear (2) and the matrix (11) is 0.5-3 tenths of a millimeter.