ROTARY INDEXING TABLE WITH POWER-OPTIMIZED DRIVE

Abstract

Disclosed is a rotary indexing table (10) having an output flange (12) which is suitable for receiving a workpiece, mounted on a housing (14) of said rotary indexing table (10) for rotation about an axis of rotation (A) and drivingly connected to at least one drive element (24) which engages a driving groove (22) in a cylindrical cam (20) which can be driven by a motor, the cylindrical cam (20) being disposed asymmetrically to the axis of rotation (A) of the output flange (12).

Claims

1.-8. (canceled)

9. A rotary indexing table having an output flange that is suitable for receiving a workpiece, the output flange being supported rotatably about an axis of rotation at a housing of the rotary indexing table, and the output flange being drive effectively connected to at least one entrainer, the at least one entrainer engaging into a drive groove of a barrel cam that is drivable by a motor, wherein the barrel cam is arranged asymmetrically to the axis of rotation of the output flange.

10. The rotary indexing table in accordance with claim 9, wherein a drive effective section of the barrel cam is arranged asymmetrically to the axis of rotation of the output flange, with the drive effective section of the barrel cam being defined by the axial section of the drive groove.

11. The rotary indexing table in accordance with claim 10, wherein the drive effective section of the barrel cam is offset with respect to an arrangement that is symmetrical with respect to the axis of rotation of the output flange by an amount that approximately corresponds to 5 to 30% of the length of the drive effective section of the barrel cam.

12. The rotary indexing table in accordance with claim 11, wherein the drive effective section of the barrel cam is offset with respect to an arrangement that is symmetrical with respect to the axis of rotation of the output flange by an amount that approximately corresponds to approximately 7 to 25% of the length of the drive effective section of the barrel cam.

13. The rotary indexing table in accordance with claim 12, wherein the drive effective section of the barrel cam is offset with respect to an arrangement that is symmetrical with respect to the axis of rotation of the output flange by an amount that approximately corresponds to approximately 10 to 20% of the length of the drive effective section of the barrel cam.

14. The rotary indexing table in accordance with claim 13, wherein the drive effective section of the barrel cam is offset with respect to an arrangement that is symmetrical with respect to the axis of rotation of the output flange by an amount that approximately corresponds to approximately 15% of the length of the drive effective section of the barrel cam.

15. The rotary indexing table in accordance with claim 9, wherein the output flange is supported at the housing of the rotary indexing table by means of a ball bearing supported slewing ring.

16. The rotary indexing table in accordance with claim 9, wherein the ball bearing supported slewing ring is designed as a four-point bearing.

17. The rotary indexing table in accordance with claim 9, wherein the ball bearing supported slewing ring is designed as an eight-point bearing.

18. The rotary indexing table in accordance with claim 9, wherein the ball bearing supported slewing ring is designed as a cross roller bearing.

Description

[0010] The invention will now be explained in the following purely by way of example with reference to the drawings, in which:

[0011] FIGS. 1a-1c show an embodiment of a rotary indexing table in accordance with the invention in different views;

[0012] FIG. 2 illustrates the effective lever arm relationships of a conventional rotary indexing table having a symmetrically arranged barrel cam; and

[0013] FIG. 3 illustrates the effective lever arm relationships of a rotary indexing table in accordance with the invention having an asymmetrically arranged barrel cam.

[0014] FIG. 1a perspectively shows a rotary indexing table 10 in accordance with the invention that in the embodiment specifically shown here has an annular output flange 12 formed as a turntable 11 to receive workpieces to be machined (not shown). The output flange 12 or the turntable 11 is here supported rotatably about an axis of rotation A at a housing 14 of the rotary indexing table 10 so that the output flange 12 can be rotationally moved from one position of rest into a second position of rest. In the embodiment shown here, the output flange 12 is annular and surrounds a central opening 16 in which, for example, one or more machining tools (not shown) can be located to machine workpieces located on the turntable 11.

[0015] The rotary indexing table 10 or its output flange 12 is driven by a motor, not shown here, whose shaft can be coupled to a drive shaft 18 of the rotary indexing table 10. The drive shaft 18 here drives a barrel cam 20 that is rotatably supported in the housing 14 of the rotary indexing table 10. For this purpose, a spirally peripheral drive groove 22 is formed in the barrel cam 20 and the entrainers 24 that are drive effectively connected to the drive flange 12 at its side that is lowerin the position of useengage into said drive groove 22. The entrainers 24 are here designed as roller pins having cam rollers 26. The entrainers 24 engaging into the drive groove 22 are thus dragged along by the rotational movement of the barrel cam 20, whereby the output flange 12 is driven to make a rotational movement in the desired manner.

[0016] As can be seen from FIG. 1c, the output flange 12 is supported in accordance with the invention by means of a ball bearing supported slewing ring 28 designed as a four point bearing at the housing 14 of the rotary indexing table 10, whereby the bearing friction can be minimized in the desired manner in favor of the reduction of the required drive power for the rotary indexing table 10.

[0017] As can be seen from FIGS. 1a and 1n particular from FIG. 1b, the barrel cam 20 and in particular its drive effective section, that is defined by the axial extent of the drive groove 22, is arranged asymmetrically to the axis of rotation A of the output flange 12 in favor of the optimization of the effective lever arm length via which the output flange 12 is driven by the barrel cam 20. In the embodiment shown here, the drive effective section of the barrel cam 20 is here offset with respect to an arrangement that is symmetrical with respect to the axis of rotation A of the output flange 12 by an offset amount V that approximately corresponds to 15% of the length of the drive effective section of the barrel cam 20. The specific offset amount V, however, depends on the geometry of the respective rotary indexing table and is preferably in the region between 10 and 20% of the length of the drive effective section of the barrel cam 20.

[0018] The effect of the asymmetrical arrangement of the barrel cam 20 in accordance with the invention on the effective lever arm length will be explained in the following with reference to FIGS. 2 and 3. FIG. 2 here explains the effective lever arm length in a conventional rotary indexing table 10 having a symmetrically arranged barrel cam 20 as is schematically illustrated in the left hand representation of FIG. 2. The right hand representation of FIG. 2 here illustrates the effective lever arm length in dependence on the angle of rotation of the output flange, that is not shown here. As can be seen from this representation, the individual entrainers 24 enter into the drive groove 22 of the barrel cam 20 at an angle of rotation of approximately 31, whereupon they are dragged along by the drive groove 22 as a result of the rotational movement of the barrel cam 20 and exit the same again at an angle of approximately 31. The effective lever arm length here increases during this engagement region from a starting value of approximately 270 mm to a maximum value of approximately 275 mm before the effective lever arm length subsequently continuously reduces down to a minimal lever arm length of approximately 190 mm at that point in time at which the entrainers 24 leave the drive groove 22 again. The effective lever arm length can be determined here in that the radial spacing of the respective entrainer 24 from the axis of rotation A at every angle of rotation of the output flange is split into two vectors which are perpendicular to one another and of which the one vector is perpendicular on the border of the drive groove 22. The other vector then represents the effective lever arm length.

[0019] If corresponding considerations are made for a rotary indexing table 10 having an asymmetrically arranged barrel cam, the relationships result such as are shown with reference to FIG. 3. As can here be seen from the right hand diagram of FIG. 3, the entrainers 24 already enter into the drive groove 22 at an angle of rotation of approximately 45 due to the asymmetrical arrangement of the barrel cam 20, with a lever arm length of 230 mm resulting. The effective lever arm length here also increases up to a value of approximately 275 mm, with this maximum effective lever arm length being adopted at an angle of approximately 14 from where the effective lever arm length continuously reduces down to a minimal value of 230 mm at an angle of approximately +15.

[0020] In contrast to the symmetrical arrangement of the barrel cam in accordance with FIG. 2, the minimal effective lever arm length is thus 40 mm larger (230 mm with the asymmetrically arranged barrel cam with respect to 190 mm with a symmetrically arranged barrel cam), whereby the maximum strain on both the entrainers 24 and the barrel cam 20 can be reduced. Due to the larger minimal effective lever arm length, less torque is furthermore also required for the drive of the output flange 12, whereby the drive power required for the drive of the rotary indexing table 10 can be minimized

REFERENCE NUMERAL LIST

[0021] 10, 10 rotary indexing table [0022] 11 turntable [0023] 12 output flange [0024] 14 housing [0025] 16 opening [0026] 18, 18 drive shaft [0027] 20, 20 barrel cam [0028] 22 drive groove [0029] 24, 24 entrainer [0030] 26 roller cam [0031] 28 ball bearing supported slewing ring [0032] A axis of rotation [0033] V offset amount