EXTRUSION PRESS PROVIDED WITH A DEVICE FOR THE AUTOMATIC CONTROL OF THE ECCENTRICITY OF A MANDREL OF SUCH A PRESS

Abstract

 An extrusion press comprises a device (15) for automatically checking the eccentricity of a mandrel (7) of such press (1), said mandrel (7) being movable with respect to a container (3) of a billet to be extruded and to an extrusion die (4) integral with said container, said mandrel (7) being movable along a longitudinal axis (W) thereof and being rotatable about it, such mandrel (7) being insertable within the extrusion die (4) and the container (3) with said movement along the axis (W) thereof in order to carry out the extrusion of the billet.
Detecting means (20) are provided adapted to detect the eccentricity of the mandrel (7) outside the container (3) of the billet, said means (20) being placed in the vicinity of the mandrel and detecting the eccentricity of such mandrel during a movement towards or away from the container (3) of the billet, such detection intervening during the rotation of said mandrel.

Description

[0001] The object of the present invention is an extrusion press provided with a device for checking the eccentricity of a mandrel of such press according to the preamble of the main claim.

[0002] As is known, an extrusion press or extruder is provided with a mandrel adapted to penetrate within a container where a metal billet is placed and provided with its own extrusion die in order to extrude an article of desired shape from such billet. The mandrel moves along its own axis under the thrust action of a pressing member in order to penetrate into the container or extrude the article. After this operation, the mandrel retracts from said container away from it in order to allow the introduction of another billet into the container. Then, the extrusion process resumes.

[0003] The mandrel is further supported by a member associated with a fixed body and which can rotate about such longitudinal so as to set the mandrel in rotation about such axis.

[0004] In the extrusion steps, it is absolutely necessary that the mandrel is perfectly coaxial to the extrusion die and to the container in order to obtain the desired article. It can however happen that, over time, the mandrel gets deformed and take up an eccentricity (i.e. a deformation on a plane orthogonal to its longitudinal axis) such as not to allow making the article properly or such that it cannot penetrate into the die without touching it. It is noted that a deformation of the mandrel of the type mentioned above is not a "misalignment" of the entire mandrel with respect to the extrusion die, a misalignment that still leads to a lack of coaxiality between the mandrel and the press die or container; this is because the misalignment provides a movement of the mandrel (and of the piston or extrusion punch in its entirety) with respect to an original axle (coaxial with the die and container). If the eccentricity changes, the mandrel and piston are aligned with the die and the container, but superficially the mandrel has deformed, so problems may arise during the extrusion.

[0005] Therefore, it is known to carry out a check of the eccentricity of such mandrel, a check which however is usually performed only through a visual analysis of the mandrel set in rotation carried out by an operator.

[0006] It is clear that such visual analysis by the operator is not accurate and since said element has a transversal dimension which is very close to the width of a seat of the die in which it is adapted to penetrate, it is understandable that even a slightest mistake by the operator in detecting a change of the eccentricity of the mandrel (i.e. a deformation thereof on a plane orthogonal to its longitudinal axis) can lead to a contact of such mandrel with the die during the extrusion.

[0007] FR 2 148 293 describes an apparatus for checking the correct operation of an extrusion press and comprising means adapted to detect the relative displacement of the axis of the container and of the extrusion punch during the extrusion. This prior document describes such detection of each parallelism defect between punch and container carried out by measuring the alignment between extrusion punch and container, by measuring the tilting angle of the container or punch with respect to a reference or by measuring any elongation and bending of each column of the press.

[0008] FR 2 148 293 does not describe nor suggest the measurement of a variation of eccentricity of the press mandrel understood as deformation of the mandrel on a plane orthogonal to its longitudinal axis; such prior art instead describes the check of a relative displacement between punch (and mandrel supported thereby) and die and the container with respect to an axis coaxial to the latter.

[0009] US 2009/0266133 relates to the same problem as FR 2 148 293, but does not mention, describes or suggest anything about the measurement of the mandrel eccentricity. US 2009/0266133 describes the check of the coaxiality between punch and container of a billet in an extrusion press and moving the extrusion punch vertically through a hydraulic cylinder in order to make its axis coaxial with that of the billet container if such coaxiality was lost during the use of the press.

[0010] The object of the present invention is to provide an extrusion press provided with a device that is automatically and accurately able to detect a change in the eccentricity or an undesired eccentricity value in the mandrel of an extrusion press.

[0011] Another object is to provide an extrusion press with a device of the above type which can be used without any time constraint between two or more extrusions.

[0012] A further object is to provide an extrusion press with a device of the above type which can automatically provide an alert if an undesired eccentricity value of the mandrel is detected.

[0013] Another object is to provide an extrusion press with a device of the above type which can be easily positioned along the movement path of the mandrel to and from the billet container.

[0014] These and other objects that will become apparent to the person skilled in the art are achieved by an extrusion press provided with a device for automatically checking the eccentricity of a mandrel of such press according to the accompanying claims.

[0015] For a better understanding of the present invention, the following drawings are attached by way of non-limiting example, in which:

figure 1 shows a longitudinal sectional view of an extrusion press provided with a device adapted to check the eccentricity of a mandrel of such press according to the invention;

figure 2 shows a perspective view from one side of the device associated with the press according to the invention;

figure 3 shows a view according to section 3-3 in figure 2; and

figure 4 shows a perspective view from another side of the device associated with the press according to the invention with some parts omitted for clarity.

[0016] With reference to the above figures, an extruder machine or extrusion press 1 is shown in its entirety in figure 1 and comprises a base 2 that is associated with several known parts adapted to allow the extrusion of an aluminum (or other metal) billet, in particular comprising a container 3 where an extrusion die 4 is placed and integral to the base, a main axially movable cylinder 5 in which a member 6A moves, supporting a mandrel or spindle 7 provided with a free end or nose 8 and attached at the other end 8A to member 6A. Such member 6A is inserted in a fixed body 6.

[0017] A drilling piston 10 moves mandrel 7 through the action on such support member 6A of said mandrel 7, said movement being obtained along a longitudinal axis W of the mandrel coincident with the longitudinal axis of piston 10, of container 3, of die 4 and ultimately, of extruder 1.

[0018] A device 15 is provided in the vicinity of die 4 and container 3 which is adapted to check automatically and in a certain manner the eccentricity of mandrel 7 after (or before) an extrusion, i.e. when it is still outside die 4 with nose 8 thereof. Device 15 is attached to container 3 through a casing 18 and is placed on a side 3A of such container facing towards mandrel 6.

[0019] In the embodiment shown in the figures, such device comprises detecting means 20 adapted to contact the surface of mandrel 7 when it is outside the extrusion die and is in rotation. Such detecting means check the eccentricity (i.e. a possible deformation of the mandrel on a plane orthogonal to its longitudinal axis) of mandrel 7 and if it has a value outside a range of eccentricity values allowed, they allow the generation of an alert for an operator related to the fact that the eccentricity measured (i.e. the surface deformation of the mandrel) is excessive and that therefore the mandrel needs replacement.

[0020] More in particular, device 15 comprises a body or frame 22 (preferably box-shaped in order to limit the weight thereof) at a face 23 whereof the detecting means 20 are provided. The latter comprise a feeler element 25 integral with an actuator 26, such as hydraulic or pneumatic or hydropneumatic; preferably, such actuator is a pneumatic cylinder whose movable element is defined by the feeler element 25. The pneumatic actuator or cylinder 26 also comprises a further movable rod 30 (at least functionally convex to the feeler element 25 or directly connected to the latter) protruding from a first side 26A of the actuator 26 opposite to that 26B (second side) at which the feeler or feeler element 25 moves. The feeler element 25 is pushed towards mandrel 7 in a yielding manner by actuator 26 so that during contact it can be pushed from the surface of such mandrel (with which the feeler is in contact) towards the actuator, without the latter being able to prevent such a movement. Therefore, there is the possibility that feeler 25 carries out a free alternating movement away from and towards such actuator 26 depending on the eccentricity of the mandrel, i.e. on the deformation of the mandrel on a plane orthogonal to its longitudinal axis.

[0021] The movable rod 30 cooperates, through a slider 31, with a linear transducer 33 connected to a control unit of device 15 or of extruder 1 which, in case of unacceptable eccentricity of mandrel 7, generates an alert in a per se known manner (sound and/or light alert) indicating the need to replace such mandrel.

[0022] The detecting means 20 are movable with respect to the body or frame 22 in order to move at mandrel 7 when this is outside the extrusion die (position reached after a previous extrusion and which creates a space between such die and a pressing body 40 carried by the main cylinder 5 and adapted to close onto container 3 during the extrusion). When this position is reached, the feeler element 25 is brought into contact with the surface of mandrel 7 set in rotation about its axis W in a known manner; in this way, through the movement of the feeler element on such surface, parallel to the body or frame 22 and due to the measurement of such movement made by the linear transducer 33 it is possible to know the eccentricity of mandrel 7.

[0023] More in particular, the detecting means 20 (that is: feeler 25, actuator 26, linear transducer 33 and the elements connected thereto) are integral to with a panel or plate 43 sliding along opposite guides 44 provided on face 23 of the body or frame 22. Of course, such movement can also take place along a single guide or a plurality of parallel guides.

[0024] Said movement of panel 43 is generated by a gearmotor or electric motor 45 attached to body 22 and actuating a worm screw 46 (for example, ball recirculating) cooperating with a threaded bush 47 integral with a shelf 48 projecting from panel 43. The rotation of the screw generated by the gearmotor or electric motor 45 results in the displacement of bush 47 along the screw itself and thus to the corresponding movement of shelf 48 and panel 43 along guides 44. In this way, feeler 25 can reach (or move away from) mandrel 7 to measure, as said, the eccentricity thereof.

[0025] Said movement is also controlled by usual displacement sensors associated with the movable panel 43.

[0026] The feeler element or feeler 25 can autonomously move parallel to frame 22 pushed by actuator 26 so as to reach mandrel 7; its movement results in that of rod 30 cooperating with the linear transducer 33.

[0027] A preferred embodiment of the invention has been described. However, still others are possible within the context of the invention described above. For example, the feeler point 25 could also be a simple pin subject to the thrust of a spring towards the exterior of frame 22 and its "return" movement therein, as a result of the contact with the mandrel in rotation, could allow the measurement of the eccentricity of such mandrel (provided that the pin is properly connected to a displacement gauge such as the linear transducer 33).

[0028] Another embodiment of the invention is not mechanical like the one described with detecting means adapted to physically contact mandrel 7, but it is of optical type wherein a laser light beam generator emits such beam orthogonally tangentially to mandrel 7, allowing to detect the variation of eccentricity thereof.

[0029] These solutions also fall within the scope of the following claims.

Claims

1. Extrusion press comprising a device (15) for automatically checking the eccentricity of a mandrel (7) of such extrusion press (1), said mandrel (7) being movable with respect to a container (3) of a billet to be extruded and to an extrusion die (4) integral with said container, said mandrel (7) being movable along a longitudinal axis (W) thereof and being rotatable about it, said mandrel (7) being insertable within the extrusion die (4) and the container (3) with said movement along its axis (W) in order to carry out the extrusion of the billet, said press being characterized in that said device (15) for checking the eccentricity comprises detecting means (20) placed in the vicinity of the mandrel and adapted to detect the eccentricity of said mandrel (7), or the deformation thereof on a plane orthogonal to its longitudinal axis (W) when the mandrel (7) is outside the container (3) and when it rotates about it axis.

2. Press according to claim 1, characterized in that said detecting means (20) are adapted to contact the surface of the mandrel (7).

3. Press according to claim 2, characterized in that said detecting means (20) comprise a feeler element (25) adapted to contact said surface of the mandrel (7) and functionally associated with a yielding thrust member (26) adapted to allow an alternating movement of said feeler element (25) to and from such yielding thrust member (26) when the feeler element contacts the surface of the mandrel (7) set in rotation, means (33) being provided for measuring such alternating movement adapted to thus detect the eccentricity of the mandrel (7).

4. Press according to claim 3, characterized in that said yielding thrust member is a pneumatic actuator (26).

5. Press according to claim 3, characterized in that said yielding thrust member is an elastic thrust body such as a spring.

6. Press according to claim 3, characterized in that said measurement means are a linear transducer 33).

7. Press according to claim 6, characterized in that the feeler element (25) is functionally connected to a rod (30) carrying a slider (31) sliding along the linear transducer (33), the movement of such slider (31) consequent to the movement of the feeler element (25) in contact with the mandrel (7) allowing said linear transducer (33) to detect the eccentricity of said mandrel (7).

8. Press according to claim 3, characterized in that the detecting means (20) are associated with a bearing member (43) movable in a guided manner with respect to a body (22) attached to a fixed part of the extrusion press (1).

9. Press according to claim 8, characterized in that it includes an electric motor (45) acting on a screw (46) on which a bush (47) relatively slides, integral with said bearing member (43), the latter being a panel or plate (23) sliding along at least one guide (44) provided on the fixed body (22), said panel or plate carrying the detecting means (20).

10. Press according to claim 9, characterized in that the feeler element (25) is movable with respect to such panel or plate (23).

11. Press according to claim 1, characterized in that it comprises control means of the detecting means (20) adapted to generate an alert if the eccentricity of the mandrel (7) detected by the detecting means (20) corresponds to an unacceptable value.

12. Press according to claim 1, characterized in that said detecting means are of the type suitable for detecting the eccentricity of the mandrel (7) in contactless mode, said contactless detecting means alternately comprising a laser light generator or means for acquiring the shape of said mandrel.

Drawing