"Large machine tool with device for the detection and correction of deformation"

[0001] The present invention relates to a machine tool for processing mechanical parts, in particular a large machine tool, fitted with a device for the detection and correction of deformation.

[0002] It is known how a machine tool encounters multiple deformations compared to the design configuration.

[0003] Some deformation is static, in other words present in the machine even in conditions of rest, that is when the machine is cold and not working. In particular this is deformation due to the weight of the members themselves, which manifests, for example, at the exit of the' head from the carriage of a milling-boring machine.

[0004] Generally speaking, such deformation is detected during the test phase of the machine to define the experimental tables, later used by the machine for a fixed correction during processing.

[0005] Other deformations, called dynamic, are related to the functioning of the machine; these are deformations caused by the action of forces on the machine tool and thermal deformation caused by heating of the tool and of the other members of the machine.

[0006] Generally speaking dynamic deformations is overlooked .

[0007] However, market demands impose very strict limits on processing tolerances, so much as to also have to take into account the dynamic deformation of the machine tool.

[0008] The purpose of the present invention is to make a machine tool, in particular a large machine tool, fitted with a device for the detection and correction of deformation, both static and dynamic.

[0009] Such purpose is achieved by a machine tool made according to claim 1. The dependent claims describe embodiment variations.

[0010] The characteristics and advantages of the machine tool according to the invention will be evident from the following description, made by way of a non-limiting example, with reference to the attached drawings wherein:

[0011]- figure 1 shows an embodiment diagram of a milling- boring machine fitted with a device for the detection and correction of deformation, according to a first embodiment of the present invention;

[0012] - figure 2 shows an embodiment diagram of a milling- boring machine fitted with a device for the detection and correction of deformation, according to a further embodiment of the present invention;

[0013] - figure 3 shows an embodiment diagram of a milling- boring machine fitted with a device for the detection and correction of deformation, according to yet a further embodiment of the present invention;

[0014] - figure 4 shows an embodiment diagram of a milling- boring machine fitted with a device for the detection and correction of deformation, according to one embodiment of the present invention;

[0015] - figure 5 shows an embodiment diagram of a milling- boring machine fitted with a device for the detection and correction of deformation, according to a further embodiment of the present invention;

[0016] - figures 6a and 6b show an embodiment diagram of a milling-boring machine fitted with a device for the detection and correction of deformation, according to yet a further embodiment of the present invention;

[0017] - figure 7 shows an embodiment diagram of a vertical portal milling machine fitted with a device for the detection and correction of deformation, according to one embodiment of the present invention;

[0018] - figure 8 shows an embodiment diagram of a vertical portal milling machine fitted with a device for the detection and correction of deformation, according to a further embodiment of the present invention;

[0019] - figure 9 shows an embodiment diagram of a drilling machine fitted with a device for the detection and correction of deformation, according to one embodiment of the present invention;

[0020] - figure 10 shows an embodiment diagram of a drilling machine fitted with a device for the detection and correction of deformation, according to a further embodiment of the present invention;

[0021] - figure 11 shows an embodiment diagram of a drilling machine fitted with a device for the detection and correction of deformation, according to yet a further embodiment of the present invention;

[0022] - figure 12 shows an embodiment diagram of a drilling machine fitted with a device for the detection and correction of deformation, according to one embodiment of the present invention;

[0023] - figure 13 shows an embodiment diagram of a drilling machine fitted with a device for the detection and correction of deformation, according to a further embodiment of the present invention;

[0024] - figure 14 shows an embodiment diagram of a drilling machine fitted with a device for the detection and correction of deformation, according to yet a further embodiment of the present invention;

[0025] According to a first embodiment of the present invention, a horizontal milling-boring machine 1 comprises a base 2, placed on a bench 3, in turn placed on a ground plane T. [0026] A vertical upright 4 extends above the base 2 along a vertical axis Y, substantially orthogonal to the ground plane T.

[0027] The machine 1 comprises a mobile group 6 supported by the upright 4; the mobile group 6 comprises a carriage 8, sliding upon command along the upright 4, thereby positioning itself at a desired position in altitude along the vertical axis Y, and a head 9 supported by the carriage 8, translating along a head axis W orthogonal to the vertical axis Y, that is substantially horizontal.

[0028] The mobile group 6 further comprises at least one mandrel 10, supported by the head 9, rotating around a working axis Z, it too substantially perpendicular to the vertical axis Y and preferably also translating along said working axis Z.

[0029] Perpendicular to the vertical axis Y and the working axis Z, a longitudinal axis X is defined.

[0030] The piece Q to be worked is positioned opposite the mandrel 10, for example positioned on a support Q' placed on the ground plane T.

[0031 ] In addition, the machine 1 comprises a correction group 20 to detect a deviation of the head from a reference condition and to correct said deviation.

[0032] In particular, the correction group 20 comprises a correction device 22 acting mechanically on the mobile group 6, in particular on the carriage 8 of this, so that, at a given position in altitude, it is mechanically influenced to modify the orientation of the working axis Z of the mandrel supported by the head 9.

[0033] For example, the correction device 22 is able to modify the orientation of the working axis Z on the plane YZ (figures 1 and 2) .

[0034] For example, the correction device 22 comprises a tie-rod 24, for example lying on the plane YZ or on a plane parallel to this, connected to a front end of the carriage 8, that is to the extremity which the head comes out of 9.

[0035] In addition, the correction device comprises pulling means 26 of the tie-rod 24, for example comprising an electric motor or hydraulic group, suitable to pull the tie-rod 24 to impose a forced rotation on the carriage 8.

[0036] In addition, the correction group 20 comprises detection devices 30 of the deviation of the head 9 from a reference condition, for example a condition of parallelism to the ground plane T which the machine is placed on, operatively, and preferably permanently, connected to the correction device 22 to activate it when needed .

[0037] According to a preferred variation, the detection means 30 are applied to the head 9 of the mobile group 6, for example to the upper surface, facing the top of the upright 4 (figure 1) .

[0038] For example, the detection means 30 comprise a sensor suitable to detect the inclination of the head, for example of its upper surface.

[0039] According to a further variation, the detection means 30 are applied to the head 9 and to the piece being worked Q, for example to its upper surface (figure 2) .

[0040] For example, the detection means 30 comprise a first sensor 30' suitable to detect the inclination of the head, for example of its upper surface, and a second sensor 30" suitable to detect the inclination of the piece Q, for example of its upper surface.

[0041 ] The two sensors 30' , 30" co-operate so that the correction device 20 operates on the basis of a comparison of the measurement taken by the first sensor 30' and that of the second sensor 30".

[0042] According to yet a further variation, the sensors 30, 30' , 30" are suitable to detect the inclination of the head on the plane YZ .

[0043] According to a further example, the correction device 22 is able to modify the orientation of the working axis Z on the plane XY, by acting on the head 9 on the plane XY (figures 3 and 4), and further sensors 32, 32', 32" are provided suitable to detect the inclination of the head on the plane XY.

[0044] Preferably, in such variations, the correction device 22 comprises means of pushing or pulling the rod 40, for example housed in the upright 4, for example operated hydraulically, engaged with at least one of its walls, suitable to influence the upright to make it perform a fixed deformation in the plane XY.

[0045] According to a further example, the correction device 22 is able to modify the orientation of the working axis Z on the plane XZ (figure 5) .

[0046] For example, the mobile group 6 comprises the carriage 8, the head 9 and the mandrel 10 and detection devices suitable for detecting the deviation of the head 9 from a reference condition in the plane XZ are provided.

[0047] For example, said detection devices comprise at least one bar 42 in material non deformable by heat, for example in INVAR®, housed in the head 9, along the working axis Z.

[0048] Preferably, the correction device 22 comprises pushing or pulling means, such as hydraulic pulling bars 50, housed in the head 9, along the working axis Z.

[0049] According to a further variation (figures 6a and 6b) , the non-deformable bars 42 and the pulling bars 50 are also used to detect and correct the deviations in the plane YZ .

[0050] According to a further embodiment of the present invention, the machine 1 is a vertical portal milling machine (figures 7 and 8) .

[0051] The machine 1 comprises two uprights 70' , 70", extending along a respective vertical axis Rl, R2, placed on respective bases 72 positioned on a bench 74 placed on the ground plane T.

[0052] The two uprights 70', 70" are distanced along a transversal axis Y and joined to each other by the mobile group 6, comprising a beam 76 which extends along said transversal axis Y.

[0053] The beam 76 is engaged with the uprights 70', 70" at the ends and is translatable along the vertical axes Rl, R2, independently at the first and at the second end.

[0054] The mobile group 6 further comprises a carriage 78 sliding along the beam 76, a head 79 supported by the carriage 78 and translatable along a head axis W and a mandrel 80, supported by the head 79, rotating around a working axis Z, substantially parallel to the vertical axes Rl, R2, and preferably translatable along said working axis Z.

[0055] The piece Q to be worked is positioned under the mandrel 80, for example on a support Q' placed on the ground plane T. [0056] In addition, the machine 1 comprises a correction group to detect a deviation of the head 79 from a reference condition and correct said deviation.

[0057] In particular, the correction group comprises a correction device acting on the beam 76 so as to impose different movements lengthwise at the two ends engaged with the uprights, to modify the orientation of the working axis Z of the mandrel 80 supported.

[0058] In addition, the correction group 20 comprises detection devices 30 of the deviation of the head 6 from a reference condition, such as a condition of orthogonality to the ground plane T which the machine is placed on, operatively, and preferably permanently, connected to the correction device to activate it when needed.

[0059] According to a preferred variation, the detection means 30 are applied to the head 79 (figure 7).

[0060] For example, the detection means 30 comprise a sensor suitable to detect the inclination of a surface of the head 79, in relation to the ground plane T.

[0061] According to a further variation, the detection means 30 are applied to the head 79 and to the piece being worked Q, for example to its upper surface (figure 8) .

[0062] For example, the detection means 30 comprise a first sensor 30' suitable to detect the inclination of a surface of the head 79 and a second sensor 30" suitable to detect the inclination of the piece Q, for example of its upper surface.

[0063] The two sensors 30', 30" co-operate so that the correction device operates on the basis of a comparison of the measurement taken by the first sensor 30' and that of the second sensor 30".

[0064] According to a further embodiment of the present invention, the machine 1 is a drilling machine (figures 9 to 14), for example a multi-mandrel machine.

[0065] The machine 1 comprises an upright 4 extending along a vertical axis Y, placed on a bench 3, placed on a ground plane T.

[0066] The machine 1 comprises a head 9 supported by the upright 4, sliding upon command along the upright 4, thereby positioning itself at a desired position of altitude along the vertical axis Y.

[0067] In addition, the head 9 comprises and supports at least one drilling group, supported by the carriage 6.

[0068] For example, the machine 1 comprises three drilling groups 90a, 90b, 90c vertically overlapping.

[0069] Each drilling group comprises a mandrel 10 rotating around a respective working axis Zl, Z2, Z3, substantially perpendicular to the vertical axis Y and preferably also translating along said working axes.

[0070] The piece Q to be machined is positioned opposite the mandrels 10, for example positioned on a support Q' placed on the ground plane T.

[0071] In addition, the machine 1 comprises a correction group to detect a deviation of the head 9 from a reference condition and correct said deviation.

[0072] In particular, the correction group 20 comprises a correction device 22 acting mechanically on the head, so that, at a given position in altitude, it is mechanically influenced to modify the orientation of the working axis Z of the mandrels supported.

[0073] For example, the correction device comprises a tie- rod, for example lying on the plane YZ, connected to a front end of the head 9, that is, to the extremity which the mandrels 10 come out of.

[0074] In addition, the correction device comprises pulling means of the tie-rod, for example comprising an electric motor or hydraulic group, suitable to pull the tie-rod to impose a forced rotation on the head.

[0075] In addition, the correction group 20 comprises detection means 30 of the deviation of the head 6 from a reference condition, for example a condition of parallelism to the ground plane T which the machine is placed on, operatively, and preferably permanently, connected to the correction device to activate it when needed .

[0076] According to a preferred variation, the detection means 30 are applied to the head 9, for example to its upper surface, facing the top of the upright 4 (figure 9) .

[0077] For example, the detection means 30 comprise a sensor suitable to detect the inclination of the head, for example of its upper surface.

[0078] According to a further variation, the detection means are applied to the head 9 and to the piece being worked Q, for example to its upper surface (figure 10) .

[0079] For example, the detection means 30 comprise a first sensor 30' suitable to detect the inclination of the head 9, for example of its upper surface, and a second sensor 30" suitable to detect the inclination of the piece Q, for example of its upper surface.

[0080] The two sensors 30', 30" co-operate so that the correction device operates on the basis of a comparison of the measurement taken by the first sensor 30' and that of the second sensor 30".

[0081] Preferably, the correction device comprises pushing or pulling means, such as a hydraulic group 100, situated externally to the upright 4 and suitable to push the upright 4, for example bracing against the foundations of the machine (figures 11 and 12) .

[0082] According to a further variation (figures 9 and 10), a hydraulic group 40 of said correction device is housed in the upright .

[0083] According to a preferred embodiment, the sensors 30, 30' , 30" comprise an electronic clinometer, that is an electronic instrument able to transmit an electric signal in output depending on the inclination of the surface on which it is placed compared to the horizontal, that is to say in relation to the ground plane T which the machine is placed on.

[0084] Preferably, moreover, the clinometer has a full scale, that is an upper measurement limit, of ±1° degree (±17455 μιη/m) , with a resolution of 0.3 μιη/m to 10 μιη/m, preferably 0.4 μιη/m to 8 μιη/m, preferably 0.5 (μιη/m to 5

[0085] Preferably, the clinometer is suitable for working in a wide temperature range, such as -50°C to +90°C.

[0086] Preferably, the clinometer is compensated in temperature so as not to encounter thermal drift.

[0087] Preferably, in addition, the clinometer is fitted with a vibration damping system.

[0088] Preferably, the head of the machine 1, to which the clinometer must be applied, has a sealed housing, which the clinometer is housed in, sheltered from coolant liquid, shavings, impact etc.

[0089] Innovatively, the machine tool according to the present invention, fitted with a correction group, makes it possible to overcome the drawbacks of the prior art, in that the detection and correction of the deviations from a reference condition, are carried out during machining, that is with the mandrel in rotation, or during brief pauses betwen one job and the next, for example while the machine is still hot.

[0090] Advantageously, the clinometer makes it possible to avail of an absolute reference given by the horizontal.

[0091] Advantageously, moreover, the clinometer is not affected by high temperatures, by the presence of dirt, shavings etc or by the presence of vibrations and occupies limited space.

[0092] It is clear that a person skilled in the art may make modifications to the machine tool and correction group described above so as to satisfy contingent requirements while remaining within the sphere of protection defined by the following claims.