Multifunction Spindle for a Machine Tool

Abstract

A multifunction spindle for a machine tool for machining workpieces has a spindle housing, rotational drive, and tool-holding unit. The tool-holding unit is disposed within the spindle housing and pivots relative to the spindle housing about an axis perpendicular to the axis of rotation. The spindle has two measurement heads connected to a transmission path for measuring position angle and enhances positioning accuracy.

Claims

1. A multifunction spindle for a machine tool for machining workpieces, comprising a spindle housing, a rotational drive, and a tool-holding unit, wherein the tool-holding unit is disposed within the spindle housing and pivots relative to the spindle housing about an axis perpendicular to the axis of rotation, wherein at least two mutually independent and adjacent measurement heads for sensing identical position angles are connected to the tool-holding unit by which measurement heads the measured position angle signals are transmitted using a transmission unit on at least two mutually independent transmission paths to a controller of the machine tool equipped with the multifunction spindle, wherein at least one transmission path is used for position control and at least one transmission path establishes functional reliability of the pivot axis positioned perpendicular to the drive shaft, wherein the transmission unit supplies power, without contact, to at least two connected measurement heads, wherein the transmission unit consists of at least two parts which rotate relative to each other at the spindle rotational speed, and wherein the transmission unit has a central bore through which media ducts are passed centrally.

2. The multifunction spindle of claim 1, wherein the spindle shaft has at least two axially adjacent annular grooves, in each of which an annular segment is arranged which can be supplied via ducts with hydraulics such that its relative position within the annular groove can be adjusted.

3. The multifunctional spindle of claim 2, wherein an anterior bearing of the spindle shaft is designed with two separate bearing segments and further wherein a first annular segment and a second annular segment are arranged between the bearing segments, each segment having an annular contour and guided in a continuous annular groove extending in circumferential direction on the spindle shaft.

4. The multifunction spindle of claim 2, wherein each annular groove has supply bores for hydraulics, wherein the bores are spaced from one another on the two end sections of the annular grooves interrupted by a pressure chamber partition.

5. The multifunction spindle of claim 1, wherein the spindle housing is equipped with at least two mutually independent rotary joints, wherein at least one rotary joint accommodates hydraulic supply ducts for a hydrodynamic bearing of the spindle shaft which bearing is established as a consequence of a defined and adapted bleed oil flow from the control ducts of the rotary joint by superpositioning with the rotational speed of the machine spindle, and wherein the at least one other rotary joint is designed for a central passage of cooling lubricant and pneumatics.

6. A multifunction spindle comprising a spindle housing, a rotational drive, and a tool-holding unit disposed within the spindle housing which pivots relative to the spindle housing about an axis perpendicular to the axis of rotation wherein at least two independent and adjacent measurement heads for sensing identical position angles are connected to the tool-holding unit by which measurement heads measured position angle signals can be transmitted by a transmission unit on at least two mutually independent transmission paths, wherein at least one transmission path is used for position control and at least one transmission path is used to establish the functional reliability of the pivot axis positioned perpendicular to the drive shaft.

7. The multifunction spindle of claim 6, wherein the transmission unit comprises at least two parts which rotate relative to each other.

8. The multifunction spindle of claim 6, wherein the transmission unit has a central bore through which media ducts are centrally passed.

9. The multifunction spindle of claim 5, wherein the spindle shaft has at least two axially adjacent annular grooves.

10. The multifunction spindle of claim 6, wherein the spindle shaft has a first annular segment and a second annular segment between two bearing segments.

11. The multifunction spindle of claim 10, wherein each bearing segment has an annular contour guided in a continuous annular groove extending in circumferential direction on the spindle shaft.

12. The multifunction spindle of claim 9, wherein each annular groove has supply bores.

13. The multifunction spindle of claim 12, wherein the supply bores are spaced from one another on two end sections of the annular grooves.

14. The multifunction spindle of claim 13, wherein the two end sections of the annular grooves are between a pressure chamber partition.

15. The multifunction spindle of claim 6, wherein the spindle housing has at least two mutually independent rotary joints.

16. The multifunction spindle of claim 15, wherein at least one rotary joint has hydraulic supply ducts.

17. The multifunction spindle of claim 16, wherein the at least one other rotary joint has a central passage fir cooling lubricant and pneumatics.

Description

[0017] Other advantageous designs will be described based on the drawings as exemplary embodiments in the following. In these drawings,

[0018] FIG. 1 is a sectional view of the structure of a multifunction spindle according to the invention

[0019] FIG. 2 shows the arrangement of a first annular segment for compensation of imbalances

[0020] FIG. 3 shows the arrangement of a second annular segment for compensation of imbalances

[0021] The multifunction spindle shown in FIG. 1 is designed for a machine tool for machining workpieces. A spindle shaft 1 is arranged in a spindle housing 2. The spindle shaft 1 is supported by an anterior bearing 3 and a posterior bearing 4 in the spindle housing 2. The anterior bearing 3 is formed by two separate bearing segments 3′ and 3″. The spindle shaft 1 rotates about an axis 24. The rotational drive required for this rotation comprises a stator unit 5 and a rotor unit 6.

[0022] The multifunction spindle comprises at least two rotary joints or ducts 11 for hydraulics and pneumatics as well as 12 and 23 for cooling lubricant and pneumatics.

[0023] On the end section directed towards the workpiece (not shown), the spindle shaft 1 has a recess in which a tool-holding unit 9 is arranged. This tool-holding unit 9 is disposed so that it can pivot relative to the spindle housing 2 about an axis 10 perpendicular to the axis of rotation 24. The pivot motion is shown stylised by an arched arrow.

[0024] A tool 8 is clamped in the tool-holding unit 9 on the end face directed towards the workpiece. A material measure 13 is arranged on the opposite end face. Two measuring heads 14 are arranged immediately adjacent to the material measure 13. In the further course, a telemetric transmitter 15 and a telemetric receiver 16 are arranged behind the measuring heads 14.

[0025] A first annular segment 22 and a second annular segment 7 are arranged at a short distance from each other between the bearing segments 3′ and 3″. The two annular segments 22 and 7 have an annular contour and are each guided in a continuous annular groove extending in circumferential direction on spindle shaft 1. By the annular segments 7 and 22, a compensation of imbalances is realised during operation of the multifunction spindle, which will be explained in more detail below. For this purpose, at least two such annular segments 22 and 7 are required. More annular segments may also be provided, however.

[0026] The data to be collected during operation of the multifunction spindle and the adjustments of parameters possibly to be made are generated either wirelessly or via measuring lines. In the drawing, such measuring lines are shown stylised in an exemplary manner as line 25 to a measuring head 14, as line 26 to a telemetric receiver 16, and as line 27 to hydraulics and pneumatics components.

[0027] If during operation of the multifunction spindle while machining of a workpiece, a deviation of position of the tool-holding unit 9 relative to its optimal position—and thereby the risk of imbalances—should occur, this irregularity is detected by the material measure 13 in operative connection with the measuring heads 14. The corresponding signals are transmitted to the machine controller which triggers a change in the supplied hydraulics quantities in the annular grooves of the annular segments 7 and 22.

[0028] According to FIG. 2, hydraulics are supplied via the bores 17 and 18 to the annular groove in which the annular segment 7 is arranged. The bores 17 and 18 are arranged on the end sections of the annular groove interrupted by a pressure chamber partition 19. In this manner, the relative position of the annular segment 7 within this annular groove may be changed.

[0029] At the same time, according to FIG. 3, hydraulics are supplied via the bores 20 and 21 to the annular groove in which the annular segment 22 is arranged. The bores 20 and 21 are arranged on the end sections of the annular groove interrupted by a pressure chamber partition 19. In this manner, the relative position of the annular segment 22 within this annular groove may be changed.

[0030] Thereby it is possible that the annular segments 7 and 22 are dislocated to a position offset relative to each other preferably by 180°, so that the imbalances that have occurred can be very well compensated. As imbalances occur especially during the machining of polygonal profiles, the multifunction spindle according to the invention is particularly advantageous for polygonal turning.

[0031] Embodiment 1. Multifunction spindle for a machine tool for machining workpieces, comprising a spindle housing, a rotational drive, and a tool-holding unit, wherein the tool-holding unit is disposed within the spindle housing and can pivot relative to the spindle housing about an axis perpendicular to the axis of rotation, characterised in that at least two mutually independent and immediately adjacent measurement systems for sensing identical position angles are connected to the tool-holding unit, by which measurement systems the measured position angle signals can be transmitted using a transmission unit on at least two mutually independent transmission paths to a controller of the machine tool equipped with the multifunction spindle, wherein at least one transmission path is used for position control, and at least one transmission path is used to establish the functional reliability of the pivot axis positioned perpendicular to the drive shaft, wherein the transmission unit contactlessly supplies power to at least two connected measurement systems, wherein the transmission unit consists of at least two parts which rotate relative to each other at the spindle rotational speed, and wherein the transmission unit has a central bore through which media ducts are passed centrally.

[0032] Embodiment 2. Multifunction spindle according to embodiment 1, characterised in that the spindle shaft (1) has at least two axially adjacent annular grooves, in each of which an annular segment (7, 22) is arranged which can be supplied via ducts with hydraulics in such a way that its relative position within the annular groove can be adjusted.

[0033] Embodiment 3. Multifunction spindle according to embodiment 2, characterised in that an anterior bearing of the spindle shaft (1) is designed with two separate bearing segments (3′, 3″), and that between the bearing segments (3′, 3″), a first annular segment (7) and a second annular segment (22) are arranged at a short distance from each other, each of which segments has an annular contour and is guided in a continuous annular groove extending in circumferential direction on spindle shaft (1).

[0034] Embodiment 4. Multifunction spindle according to embodiment 2, characterised in that each annular groove has supply bores (17, 18, 20, 21) for hydraulics, wherein the bores (17, 18, 20, 21) are spaced from one another on the two end sections of the annular grooves interrupted by a pressure chamber partition (19).

[0035] Embodiment 5. Multifunction spindle according to embodiment 1, characterised in that the spindle housing (2) is equipped with at least two mutually independent rotary joints (11, 12, 23), wherein at least one of these rotary joints (11) is designed to accommodate hydraulic supply ducts for a hydrodynamic bearing of the spindle shaft (1) which bearing is established as a consequence of a defined and adapted bleed oil flow from the control ducts of the rotary joint (11) by superpositioning with the rotational speed of the machine spindle, and wherein the at least one other rotary joint (12, 23) is designed for a central passage of cooling lubricant and pneumatics.

LIST OF REFERENCE NUMERALS

[0036] 1 spindle shaft [0037] 2 spindle housing [0038] 3 anterior bearing of the spindle shaft [0039] 3′ separate bearing segment [0040] 3″ separate bearing segment [0041] 4 posterior bearing of the spindle shaft [0042] 5 stator unit [0043] 6 rotor unit [0044] 7 annular segment [0045] 8 tool [0046] 9 tool-holding unit [0047] 10 pivot axis perpendicular to the spindle's axis of rotation [0048] 11 rotary joint, hydraulics and pneumatics [0049] 12 rotary joint, cooling lubricant and pneumatics [0050] 13 material measure [0051] 14 measuring heads [0052] 15 telemetric transmitter [0053] 16 telemetric receiver [0054] 17 bore to the annular groove for annular segment 7 [0055] 18 bore to the annular groove for annular segment 7 [0056] 19 pressure chamber partition [0057] 20 bore to the annular groove for annular segment 22 [0058] 21 bore to the annular groove for annular segment 22 [0059] 22 annular segment [0060] 23 rotary joint, cooling lubricant and pneumatics [0061] 24 axis of rotation of the spindle shaft [0062] 25 line to the measuring head [0063] 26 line to the telemetric receiver [0064] 27 line to hydraulics/pneumatics components