Search

EP-4204183-B1 - MACHINE TOOL

EP4204183B1EP 4204183 B1EP4204183 B1EP 4204183B1EP-4204183-B1

Inventors

  • ECEIZA AGOTE, PATXI
  • MARTÍN, Alex
  • ATUTXA OCERIN, Amaiur

Dates

Publication Date
20260506
Application Date
20210625

Claims (17)

  1. A machine tool for the machining of elongate workpieces, comprising: a workpiece support column (1) having a first workpiece support side (1') comprising first workpiece support means (1001, 1003) for supporting a first workpiece (W1) and second workpiece support means (1002, 1004) for supporting a second workpiece (W2), the first workpiece support means (1001, 1003) and the second workpiece support means (1002, 1004) being arranged for supporting the first workpiece (W1) vertically above the second workpiece (W2); and a machining station (B) comprising at least a first tool spindle (B1) for machining the first workpiece, and a second tool spindle (B2) for machining the second workpiece; wherein the workpiece support column (1) is rotatable around a vertical axis (C) so as to shift the workpieces between the machining station (B) and a station (A) for loading and unloading of workpieces; wherein the first workpiece support means (1001, 1003) comprise at least a first chuck (11) for clamping a first end of the first workpiece, and a first additional support element (12) for supporting a second end of the first workpiece, the first chuck (11) and the first additional support element (12) facing each other along a first horizontal axis (D1) so as to allow for rotation of the first workpiece around the first horizontal axis, and the second workpiece support means (1002, 1004) comprise at least a second chuck (21) for clamping a first end of the second workpiece and a second additional support element (22) for supporting a second end of the second workpiece, the second chuck (21) and the second additional support element (22) facing each other along a second horizontal axis (D2) so as to allow for rotation of the second workpiece around the second horizontal axis, characterized in that the first workpiece support means (1001, 1003) comprise drive means (100) for applying torque to the first workpiece via the first chuck (11) to rotate the first workpiece around the first horizontal axis (D1) for machining of the first workpiece by turning, and in that the second workpiece support means (1002, 1004) comprise drive means for applying torque to the second workpiece via the second chuck (21) to rotate the second workpiece around the second horizontal axis (D2) for machining of the second workpiece by turning.
  2. The machine tool according to claim 1, wherein the first additional support element is a third chuck (12) for clamping the second end of the first workpiece, wherein the second additional support element is a fourth chuck (22) for clamping the second end of the second workpiece, wherein the first workpiece support means (1001, 1003) comprise drive means for applying torque to the first workpiece via the third chuck (12) to rotate the first workpiece around the first horizontal axis (D1) for machining of the first workpiece by turning, and wherein the second workpiece support means (1002, 1004) comprise drive means for applying torque to the second workpiece via the fourth chuck (22) to rotate the second workpiece around the second horizontal axis (D2) for machining of the second workpiece by turning.
  3. The machine tool according to claim 2, wherein the machine is arranged for selectively retracting workpiece clamping jaws (11a, 12a, 22a) of one of the first chuck (11) and the third chuck (12), and of one of the second chuck (21) and the fourth chuck (22), while applying torque to the respective workpiece via the other one of the first chuck and the third chuck, and via the other one of the second chuck and the fourth chuck, so as to allow for machining of the workpieces along their entire lengths, while the workpieces remain axially and radially fixed by the first and second workpiece support means.
  4. The machine tool according to claim 2 or 3, wherein each of the first and third chucks (11, 12) comprises jaws (11a, 12a) arranged to apply pressure onto a surface of the workpiece in the radial direction to allow torque to be applied to the workpiece via the chuck, and whereas the machine is arranged to selectively - withdraw the jaws (11a) of the first chuck (11) from the workpiece to allow for machining of the corresponding part of the workpiece while rotating the workpiece by applying torque to the workpiece via the third chuck (12), and - withdraw the jaws (12a) of the third chuck (12) from the workpiece to allow for machining of the corresponding part of the workpiece while rotating the workpiece by applying torque to the workpiece via the first chuck (11).
  5. The machine tool according to any one of the preceding claims, wherein the workpiece support column has a second workpiece support side (1") angularly spaced from the first workpiece support side, the second workpiece support side comprising third workpiece support means (15, 16) for supporting a third workpiece and fourth workpiece support means (25, 26) for supporting a fourth workpiece, the third workpiece support means and the fourth workpiece support means being arranged for supporting the third workpiece vertically above the fourth workpiece, and wherein, optionally, the third workpiece support means (15, 16) and the fourth workpiece support means (25, 26) are different from the first workpiece support means (1001, 1003) and the second workpiece support means (1002, 1004), in order to allow machining operations to be carried out on workpieces supported on the second workpiece support side (1") that cannot be carried out on workpieces supported on the first workpiece support side (1'), in particular due to the manner in which the workpieces are supported on the first workpiece support side (1').
  6. The machine tool according to any one of the preceding claims, wherein: - the workpiece support column, including the first workpiece support means (1001, 1003) and the second workpiece support means (1002, 1004), is dimensioned to fit into a cylinder that is co-axial with the vertical axis (C) and that has a diameter of less than 2.5 m, preferably less than 2 m, more preferably less than 1.8 m, while allowing for turning of workpieces having a length of 0.75 m; and/or - the drive means are configured for rotation of the respective workpiece by more than 100 rpm, such as by more than 200 rpm.
  7. The machine tool according to any one of the preceding claims, wherein at least one of the workpiece support means comprises a motor and chuck assembly, the assembly comprising an electric motor (100) comprising a stator (101) and a rotor (102) placed radially inside the stator, the assembly further comprising a hollow workpiece-spindle (103) extending through the rotor (102), the workpiece-spindle (103) having a first end (103a) and a second end (103b), the assembly further comprising a retractable jaw chuck (11) at least partly arranged within the workpiece-spindle (103) at the second end (103b), the retractable jaw chuck (11) comprising jaws (11a) for clamping a workpiece, wherein the workpiece-spindle (103) is surrounded by the rotor (102) at a position between the first end (103a) and the second end (103b), wherein the workpiece-spindle (103) is rotationally fixed to the rotor (102) so that it rotates with the rotor (102), wherein the workpiece-spindle (103) has a first inner diameter (d1) at the first end (103a) and a second inner diameter (d2) at the second end (103b), wherein the rotor (102) has a third inner diameter (d3), wherein the second inner diameter (d2) is substantially larger than the first inner diameter (d1) and/or than the third inner diameter (d3).
  8. The machine tool according to claim 7, wherein the workpiece-spindle (103) is rotationally supported by a first bearing (112) placed at the first end (103a) of the workpiece-spindle or between the rotor (102) and the first end (103a), and a second bearing (110) placed at the second end (103b) of the workpiece-spindle or between the rotor (102) and the second end (103b), the first bearing (112) having a fourth inner diameter (d4) and the second bearing (110) having a fifth inner diameter (d5), the fifth inner diameter (d5) being at least 25% larger than the fourth inner diameter (d4).
  9. The machine tool according to claim 7, wherein the workpiece-spindle (103) is rotationally supported by a first bearing (112) placed at the first end (103a) of the workpiece-spindle or between the rotor (102) and the first end (103a), and a second bearing (110) placed at the second end (103b) of the workpiece-spindle or between the rotor (102) and the second end (103b), the first bearing (112) having a fourth inner diameter (d4) and the second bearing (110) having a fifth inner diameter (d5), wherein the workpiece-spindle has an axial length (L) between the first end (103a) and the second end (103b), wherein the axial length (L) is less than three times the fifth inner diameter (d5), such as less than two times the fifth inner diameter (d5), such as less than 1.5 times the fifth inner diameter (d5).
  10. The machine tool according to any one of claims 7-9, wherein: - the third inner diameter (d3) is smaller than the second inner diameter (d2); and/or - the electric motor is capable of applying a torque larger than 400 Nm to the workpiece; and/or - the jaws (11a) are capable of movement in the radial direction, so as to apply radial clamping forces onto the workpiece, wherein the jaws (11a) are optionally capable of applying a clamping force of more than 75 kN onto the workpiece.
  11. The machine tool according to claim 9, the machine tool being arranged for turning of workpieces having a maximum diameter S, wherein the fifth inner diameter (d5) is larger than 0.5 S, for example, larger than 0.75 S, such as larger than 0.9 S.
  12. A method of machining workpieces, comprising: loading at least a first workpiece (W1) and a second workpiece (W2) onto a workpiece support column (1) so that each of the first workpiece (W1) and the second workpiece (W2) is supported by the workpiece support column (1) with a longitudinal axis (D1, D2) of the respective workpiece extending horizontally, one of the workpieces (W1) being placed vertically above the other one (W2) of the workpieces; rotating the workpiece support column (1) around a vertical axis (C) to bring the workpieces to a machining station (B); carrying out at least a first machining operation comprising removing material from the workpieces by turning the workpieces, whereby turning the workpieces includes rotating the workpieces around the longitudinal axes (D1, D2) of the respective workpieces; unloading the workpieces (W1, W2) from the workpiece support column (1).
  13. The method according to claim 12, further comprising carrying out at least a second machining operation on the workpieces, different from the first machining operation, prior to unloading the workpieces from the workpiece support column (1).
  14. The method according to claim 13, wherein: - the first and second machining operations are both carried out by contacting the first workpiece (W1) with a tool (B51, B52, B53) using a first tool spindle (B1), and by contacting the second workpiece (W2) with a tool (B51, B52, B53) using a second tool spindle (B2); and/or - the second machining operation comprises one of milling, drilling and power-skiving; and/or - the workpiece support column is rotated by an angle of more than 5 degrees and less than 85 degrees between the first machining operation and the second machining operation.
  15. The method according to any one of claims 12-14, wherein: - the first machining operation is carried out by rotating the first workpiece (W1) by applying torque to the first workpiece (W1) with a first chuck (11) and by rotating the second workpiece (W2) by applying torque to the second workpiece (W2) with a second chuck (21) during one part of the first machining operation, and by rotating the first workpiece (W1) by applying torque to the first workpiece (W1) with a third chuck (12) and by rotating the second workpiece (W2) by applying torque to the second workpiece (W2) with a fourth chuck (22) during another part of the first machining operation.
  16. The method according to any one of claims 12-15, wherein at least one machining operation is carried out on the workpieces (W1, W2) while the workpieces are supported on a first side (1') of the workpiece support column, and wherein at least another machining operation is carried out on the workpieces (W1, W2) while the workpieces are supported on a second side (1") of the workpiece support column.
  17. The method according to any one of claims 12-16, wherein the method is carried out using a machine tool according to any one of claims 1-11.

Description

TECHNICAL FIELD The present invention relates to the field of machine tools and, more particularly, to the field of machine tools for carrying out different kinds of machining operations on workpieces, in particular on metal workpieces. STATE OF THE ART Machining of workpieces implies removing material using cutting tools. There are many different kinds of machining operations, but they can generally be classified into three groups of processes, namely, turning, drilling and milling. Typically, a specific machine tool is required for taking care of each machining operation. For example, drilling is a process for creating a hole in a workpiece: the drill enters the workpiece and cuts a hole with a diameter equal to the one of the tool. Boring and reaming are other machining operations that can be considered to pertain to the same group as drilling, but which are carried out on a hole that has typically been previously established by drilling. Milling is a process that is typically used to remove material from a metal workpiece that is not axially symmetric. Removal of material is carried out using a tool, also referred to as a cutter, that is rotated at high speed. Differently from drilling and milling where rotary tools are applied to a stationary workpiece, in turning operations it is the workpieces that is rotated at high speed, using a lathe in which a workpiece is clamped - typically, between a headstock and a tailstock- and rotated at high speed, whereby a cutting tool contacts the workpiece to remove the material. The torque that produces the rotational movement of the workpiece is applied to the workpiece via a chuck that forms part of the headstock and that clamps the workpiece at one of its ends. Typically, for the mass production of objects, such as metal objects, such as metal components for vehicles or other applications, different operations are carried out on the workpieces in different machining stations. Typically, for high productivity and reliability, special purpose machines are used. The workpieces may be processed in different machining stations, whereby a workpiece may be subjected to a sequence of different machining operations. Operations such as turning, milling, drilling, reaming, etc. can be carried out in different machines forming a production line. Production lines are typically designed for high productivity and reliability. If demand exceeds the capacity of existing production lines, one or more additional lines may be added. It is known in the art to design machines capable of carrying out a plurality of different machining operations. For example, a lathe for processing workpieces by turning can additionally incorporate sub-systems for, for example, milling. An example of this kind of system is disclosed in US-6684500-B1 which describes an example of the typical robust machine bed incorporating spindle stocks with chucks for gripping and high-speed rotation of a workpiece, and displaceable tool supports carrying different kinds of tools for carrying out different types of machining operations on the workpiece. Due to the particularities of high-speed rotation of workpieces for turning operations, including the need to transfer torque to the workpiece and to ensure compensation of unbalances, machine tools intended to allow for machining by turning and additionally by other types of machining are typically based on a lathe machine layout, additionally incorporating the spindles needed for other machining operations. Another example of a machine tool that allows for different types of machining operations (namely, both machining operations based on rotation of the workpiece and machining operations based on rotation of the tool) is disclosed in DE-10343003-A1. On the other hand, WO-2017/220290-A1 discloses, inter alia, how a machine tool can be adapted so as to carry out different kinds of operations, such as milling and turning, and how this may involve adaptation of the drive means in charge of the rotation of the workpiece. Due to the need for stability and torque transfer, lathes for turning of metal workpieces typically have a substantial size in the axial direction, that is, in the direction of the axis of rotation. This is often due to the need for radial stability and the need to accommodate the clamping mechanism, typically involving a hydraulic cylinder or other means for actuating the clamping jaws of the chuck to firmly hold the end of the workpiece. WO-02/07920-A1 discloses a drive and chuck design that aims at reducing the axial extension, but still embodied in a machine with a typical lathe layout. Loading and unloading of workpieces can be a time-consuming task, and may hamper productivity. WO-05/087414-A1 discloses a system for bringing workpieces to the machining area in a so-called vertical turning machine, including two turning spindles for parallel turning of two workpieces. The machine comprises a carriage channel, which extends from the rear side of the