Mounting device for a rotary spindle of a balancing machine

Abstract

Disclosed is a mounting device (6) including a receiving opening (8) with a circular inner locating surface (10) which is coaxial with the axis of rotation (3) and serves for engagement with radially outer vertices (24) of the polygon profile of a holding pin (23). Arranged adjacent to the inner locating surface is a positioning disk (14) which has an opening (15) coaxial with the axis of rotation (3) and of such polygonal shape and size that the polygon profile of the holding pin (23) engaging in the opening (15) is supported in the opening (15) in a manner preventing relative rotation.

Claims

1. A mounting device for a rotary spindle of a balancing machine, with a central receiving opening for receiving a holding pin of substantially polygon profile of a rotary body to be balanced, the central receiving opening comprising a circular inner locating surface having a central axis that is coaxial with the axis of rotation of the spindle and adapted to directly contact a plurality of radially outer vertices of the polygon profile of the holding pin such as to cause the inner locating surface to center the holding pin, and an inner cylindrical bore portion of a diameter greater than that of the inner locating surface which inner cylindrical bore portion accommodates a positioning disk arranged adjacent to the inner locating surface and secured to the mounting device in a manner preventing relative rotation, the positioning disk having an opening coaxial with the axis of rotation and of such shape and size that the polygon profile of the holding pin engaging in the opening is held in the opening in a manner preventing relative rotation.

2. The mounting device according to claim 1 wherein in the positioning disk is a component manufactured separately, being arranged on a shoulder of the receiving opening adjacent to the inner locating surface and supported on the mounting device in a manner preventing relative rotation.

3. The mounting device according to claim 1, wherein the opening of the positioning disk has the same shape as the polygon profile of the holding pin.

4. The mounting device according to claim 1 wherein the opening of the positioning disk is shaped in such a manner that the polygon profile of the holding pin is adapted to be non-rotationally supported on the positioning disk in a first angular position and in a second angular position turned through 180°.

5. The mounting device according to claim 1 wherein the mounting device includes a plane seating surface for a shoulder of the rotary body.

6. The mounting device according to claim 1 wherein the receiving opening accommodates a clamping device for clamping the holding pin.

7. Use of a mounting device according to claim 1 wherein the mounting device is arranged in an insert detachably connected to the spindle of a balancing machine.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An embodiment of the present invention is illustrated in the accompanying drawing and will be described in greater detail in the following. In the drawing,

(2) FIG. 1 is a cross-sectional view of the spindle of a balancing machine, showing a mounting device arranged therein and a toolholder arranged in the mounting device;

(3) FIG. 2 is a cross-sectional view of the mounting device taken along line II-II of FIG. 1;

(4) FIG. 3 is a cross-sectional view of the mounting device taken along line III-III of FIG. 1; and

(5) FIG. 4 is a view of a positioning disk showing an embodiment with a hexagonal opening capable of receiving a trigonal holding pin in a first angular position and in a second angular position turned through 180°.

DETAILED DESCRIPTION OF THE DRAWINGS

(6) FIG. 1 shows a housing part 1 of a balancing machine having a spindle 4 carried therein for rotation about an axis of rotation 3 by means of rolling bearings 2. For dynamic unbalance measurement, the spindle 4 is drivable into rotary motion by means of a motor. Arranged in a central bore 5 of the spindle 4 is a mounting device 6 which is configured as an exchangeable insert. The mounting device 6 includes a flange 7 secured to the frontal end of the spindle 4 by means of screws. The mounting device 6 has a central receiving opening 8, and on its frontal end a plane, annular seating surface 9. The receiving opening 8 has at its end adjacent to the plane seating surface 9 a coaxial locating surface 10 and, adjoining the latter inwardly, a circular cylindrical transition surface 11 of a diameter greater than the locating surface 10. The transition surface 11 terminates on a radial shoulder 12 which is adjoined by an inner cylindrical bore portion 13 coaxial with the axis of rotation 3. The bore portion 13 accommodates a positioning disk 14 having an opening 15. The positioning disk 14 has a cylindrical envelope surface 16 causing it to be centrally located in the bore portion 13. The positioning disk 14 abuts the shoulder 12 and is fixedly connected with the mounting device 6 by screws 17 parallel to the axis.

(7) Arranged in the receiving opening 8 of the mounting device 6 is a toolholder 20 carrying a tool 21. The toolholder 20 has a shoulder 22 in abutting engagement with the plane seating surface 9 and includes a holding pin 23 constructed as a polygonal hollow tapered shank which extends through the receiving opening 8 and with its inner end into the opening 15 of the positioning disk 14.

(8) The holding pin 23 is conical and, as becomes apparent from FIGS. 2 and 3, has a trigonal polygon profile formed of eccentric circular arcs of differing diameter and known by the standard designation P3G. The locating surface 10 is configured in the shape of a circular section of a cone envelope, its inclination and radius matching the inclination and the center-to-center distance of the vertices 24 of the holding pin 23 in such fashion as to cause the locating surface 10 to center the holding pin 23 to the required precision. FIG. 3 shows the points of contact where the more pronounced curvatures of the polygon profile of the holding pin 23 rest against the lesser pronounced curvatures of the locating surface 10.

(9) As FIG. 2 shows, the opening 15 in the positioning disk 14 is provided with the hub profile matching the profile of the holding pin 23, thereby ensuring a non-rotatable support of the toolholder 20 in the mounting device 6 with defined angle assignment. Considering that three mounting positions are possible, it is recommended to add an external marking to identify the selected mounting position. The accuracy demands of such a marking are however low.

(10) To clamp the toolholder 20 into place in the receiving opening 8, the spindle 4 houses a clamping device 25 which engages in an undercut groove in a bore of the toolholder 20 and is capable of being actuated by means of an actuating rod 26.

(11) FIG. 4 shows a second embodiment of a positioning disk 28 suitable for insertion into the mounting device 6 in lieu of the positioning disk 14. The positioning disk 28 has an opening 29 with a polygonal inner contour divided evenly into six profile sections 30. Each of the profile sections 30 including an angle of 60° is shaped in the form of a correspondingly large section of the outer contour of the pin profile in the center of which a vertex 24 of the pin profile lies. The opening 29 divided into six sections enables the polygonal holding pin 23 to be received in two positions turned relative to one another by 180°. In this manner it is possible to balance the toolholder 20 by index balancing, that is, by performing a first measurement run in a first mounting position, and a second measurement run in a second mounting position indexed at 180°. With such an approach (index balancing) it is possible to detect and compensate for errors caused by the mounting in the balancing machine.

(12) The mounting device disclosed in the present invention is suitable for equally thick and conical holding pins with a polygonal cross-sectional profile. The cross-sectional profile may have three or a greater or smaller number of vertices. The “polygonal” cross-sectional profile is not a precise geometrical polygon with sharp corners. The polygon corners and sides correspond to a trochoidal curve and are well rounded as lobes, as illustrated, in the manner well known in the art as disclosed in U.S. Pat. No. 3,630,534 and as defined by standard DIN ISO 26623. The polygon profile of this kind is commonly used in driving shaft and hub connections, in particular in mounting devices for mounting tool holders and driving spindles. For the mounting device to mount a particular profile, it is only necessary according to the invention to match the inner diameter of the locating surface and the inner contour of the positioning disk to this particular profile. Both these requirements can be met in simple and economical manner.