GB2097299A - Toolholder for rotary tool - Google Patents

Abstract

A toolholder for a rotary tool has a driving part (1) adapted to be coupled to a spindle; and a driven part (2) in which a cutting tool may be mounted along a tool axis. The driving part and the driven part are coupled to permit pivotal movement and lateral movement perpendicularly to the tool axis by a joint mechanism. This comprises a two- part spherical body (10, 24) pivotable in a sphered-bore housing (4, 5) of the driving part. The body has a drive-ball connection (12, 13) with the housing. The body retains a tool carrying sleeve (21) between bearings (20, 23), allowing relative radial floating of the sleeve. One bearing (20) has drive balls (30) for transmitting torque to the sleeve. <IMAGE>

Description

SPECIFICATION Toolholder for rotary tool This invention relates to a toolholder for a rotary tool having a driving part and a driven part which are coupled so that the driving part and the driven part may pivot and move laterally relative to one another.

In some cutting operations performed by rotary cutting tools (for example, the finishing of a rough-bored hole, the drilling of a hole with a drill-jig bushing to guide the cutting tool, or the formation of a thread in a roughbored hole), special toolholders are required for attaching the cutting tools to machine spindles for rotating the tools. Known and conventional toolholders for such cutting operations have a joint-type coupling between the driving and driven parts thereof to permit angular adjustment of the position of the cutting tool relative to the spindle. These conventional joint coupling toolholders permit the axis of the driven part to be inclined relative to the axis of the driving part.The relative angular adjustment of the axes of the driven and driving parts is intended to allow the driven part to adapt itself to the drilling axis defined by the rough-bored hole or the drill-jig bushing. Various conventional devices have been used for toolholders to permit this angular adjustment. However, such devices have not been capable of accurately matching the particular hole being cut, despite the pivotal or angular adjustment provided by the joint coupling of the toolholder, and despite the capability of changing the pivotal axis of the joint coupling relative to the hole being cut. Adjustment of the pivotal axis relative to the hole generally makes the angle of the driven part relative tosthe driving part smaller.

If the cutting tool is not accurately positioned to match the particular hole being cut, the hole's axis is modified or there is a jamming of the cutting tool in the hole or drill-jig bushing. Both instances result in undesirable effects, such as increased wear on the tooling and remachining of the tool. Although this problem associated with conventional machinery may be reduced to some extent by making the machine's spindle (which drives the toolholder) also pivotable, such modification of the machine's spindle significantly increases the costs and complexity of the machine's spindle.

According to one aspect of the present invention, there is provided a tool holder for a rotary tool, said toolholder comprising: a driving part adapted to be coupled to a spindle; a driven part adapted to mount a said tool (e.g. a cutting tool) along a tool axis; and joint means for coupling said driving and driven parts so as to permit relative pivotal movement and lateral movement thereof at least substantially perpendicularly (e.g. 90 ) to said tool axis.

According to a second aspect of the present invention, there is provided a tool holder for a rotary tool, said toolholder comprising: a casing; a driving part coupled to said casing; a driven part having mounting means for coupling thereto (e.g. therein) a said tool (e.g.

a cutting tool) along a tool axis; and joint means mounted to said casing (e.g.

therein) for coupling said driving and driven parts so as to permit relative pivotal movement and lateral movement thereof at least substantially perpendicularly (e.g. 90 ) to said tool axis.

Preferably, said joint means comprises: a substantially spherically shaped recess; and a substantially spherically shaped body mounted in said recess, so as to permit pivotal movement to all sides. Preferably, said recess comprises a portion of said casing.

Said joint means can comprise a bearing plane on said body, and roller bearing means supporting on said bearing plane said driven part. Preferably, said roller bearing means comprises a bearing ring with axial bores and radial grooves on each side thereof, said bores receiving first balls for directly transferring axial forces between said body and said driven part, said radial grooves receiving second balls for transmitting torque between said body and said driven part. Preferably, said driven part has a bearing flange; and said body preferably has radial grooves aligned with said radial grooves on the sides of said bearing ring which face said bearing flange and said body, respectively, which grooves receive respective second balls.Said body and said casing can be coupled for simultaneous rotation by balls mounted in said casing, said body preferably having peripheral slots for these balls. Said joint means can comprise means for locking in a predetermined position said body relative to said recess. Said joint means can comprise a space in said body, which space receives said driven part and has lateral dimensions greater than corresponding lateral dimensions of said driven part so as to permit said lateral movement. Said joint means can comprise bearing means, for coupling said body and said driven part, so as to permit said lateral movement and transmitting therebetween of torque.

The present invention can provide a toolholder for a rotary tool, which toolholder will simply and accurately position the tool relative to the hole to be cut. The tool-holder can be accurately positioned relative to a rough-bored hole or drill-jig bushing without jamming. The tool-holder can be relatively easy and inexpensive to manufacture.

In the accompanying drawings, which are given by way of example of the present invention: Figure 1 is a side elevational view of one embodiment of a toolholder for a rotary tool, in partial section taken along line I-I of Fig.

3; Figure 2 is a partial, side elevational view of the tool-holder of Fig. 1, in partial cross section generally perpendicular to that of Fig.

1; Figure 3 is a plan view of the toolholder in cross section, taken along line Ill-Ill of Fig. 1; and Fig. 4 is a partial, partially sectioned side elevational view of another embodiment of toolholder for a rotary tool.

In Figs. 1 and 2, the toolholder comprises a driving part 1 and a driven part 2. Driving part t has a driving taper 3 forming its upper portion which is adapted to be coupled to a spindle of a rotary tool. The lower portion of driving part I comprises a casing part 4 and a casing cover 5. Casing part 4 is connected to casing cover 5 in any suitable manner, e.g. by countersunk screws 6 which are threaded into casing cover 5 and project into small cavities 7 in casing part 4, to form a clutch casing connected to driving taper 3.

The internal surfaces of casing part 4 and casing cover 5 define a substantially spherically shaped recess 8 with a substantially spherically shaped contact area 9. A substantially spherically shaped or ball shaped body 10 is mounted in recess 9 so as to be free from play relative to contact area 9, while permitting relative pivoting movement of body 10 to all sides and directions relative to casing part 4. Body 10 is coupled to casing part 4, for simultaneous rotation therewith to enable body 10 to be driven by casing part 4.

The torque transmitting coupling between body 10 and casing part 4 comprises balls 12 which are mounted in holes 14 of casing part 4. Balls 12 project from their mounting and from casing part 4 into peripheral slots 13 formed in body 10. Preferably, four balls 12 are equally spaced about the periphery of body 10, although any desired number of balls 12 may be provided. The more balls 12 employed to couple body 10 and casing part 4, the smaller the non-uniformity of rotation of body 10 is relative to casing part 4.

Elongated peripheral slots 13 and balls 12 mounted in holes 14 of casing part 4 fix body 10 relative to driving part 1 against relative rotation about the longitudinal axis of driving part 1, while permitting relative pivoting movement to all sides and directions about axes perpendicular to the longitudinal axis of driving part 1.

The upper surface of body 10 is formed with a generally hemispherically shaped cavity 15. A locking ball 16 is movably mounted in a vertically extending bore in driving taper 3 opposite cavity 15 and is biased by a spring 17 into engagement with cavity 15. The engagement of cavity 15 with locking ball 16 releasably locks body 10 relative to recess 8 in a position in which body 10 is vertically aligned with driving part 1. Body 10 has a planar bearing surface or bearing plane 18 on its lower surface. When locking ball 16 is fully received in cavity 15, bearing plane 18 is oriented precisely perpendicular to the axis of driving part 1, as illustrated in Fig. 1.As illustrated in Fig. 2, when body 10 is pivoted in recess 8 with respect to driving part 1, bearing plane 18 is inclined at an acute angle relative to the axis of driving part 1 and locking ball 16 is dislodged, against the bias of spring 17, from cavity 15.

A cylindrical, axially extending space 35 (Fig. 2) is provided in body 10 and opens onto bearing plane 18. A spherical segment 24 is supported on the lower portion of spherical contact area 9 in casing cover 5. Body 10 and spherical segment 24 form a ball or sphere having a gap 25 therein.

The upper portion of driven part 2 comprises a cylindrical sleeve body 21 which is hollow for receiving and mounting a cutting tool therein. The lower portion of driven part 2 comprises a collar 36 which is loosened or tightened by an internally threaded sleeve nut 37 for removal, insertion and fixing of a cutting tool within driven part 2. A bearing flange 22 is unitarily formed with and extends outwardly from the lateral surface of sleeve body 21 perpendicularly to the longitudinal axis of driven part 2. Cylindrical sleeve body 21 is located within space 35 in body 10 and extends through an aligned opening in spherical segment 24. Bearing flange 22 is located within gap 25 with an annular roller bearing 20 and an annular roller bearing 23. Roller bearing 23 is positioned between bearing flange 22 and spherical segment 24 and is located about cylindrical sleeve 21.Roller bearing 20 supports driven part 2 on bearing plane 18 of body 10. Lateral movement is permitted between body 10 and driven part 2 because the lateral dimensions of space 35 and of gap 25 in body 10 are greater than the corresponding lateral dimensions of driven part 2.

Roller bearing 20 (Fig. 3) comprises a generally annular bearing ring 26 having a plurality of axial bores 27 extending entirely through the thickness of ring 26, and a plurality of radially extending grooves 28 on each of its sides. Bores 27 house a first plurality of balls 29 which directly transfer axial forces between body 10 and driven part 2 by bearing directly on bearing plane 18 and the upper surface of bearing flange 22. Two pairs of grooves 28 are provided in ring 26. Each of these grooves extends radially in ring 26 and has a depth less than the thickness of bearing flange 22. The pair of grooves 28 on the upper surface of ring 26 are diametrically opposed.The pair of grooves 28 located on the lower surface of ring 26 (illustrated in phantom lines in Fig. 3) are diametrically opposite each other and are angularly displaced 90 relative to the pair of grooves 28 on the upper surface of bearing ring 26. A second plurality of balls 30 is received in grooves 28 for transmitting torque between body 10 and driven part 2.

As illustrated in Fig. 1, bearing flange 22 has radially extending grooves 31 formed on its upper surface facing bearing ring 20, which grooves are aligned with grooves 28 formed in the lower surface of bearing ring 26 and receive the lower portions of second balls 30 located in grooves 28 in the lower surface of ring 26. In a similar manner, as illustrated in Fig. 2, radially extending grooves 32 are formed in bearing plane 18 and are aligned with grooves 28 formed in the upper surface of bearing ring 26 and receive the upper portions of second balls 30 in grooves 28 in the upper surface of bearing ring 26. In this manner, roller bearing 20 transfers both axial forces and torque between body 10 and driven part 2, while permitting lateral movement therebetween in a direction transverse to the longitudinal axis of sleeve body 21.

A cutting tool when fixed in sleeve body 21 can be laterally displaced perpendicular to its longitudinal axis owing to the construction of bearing ring 20 and the provision of appropriate spacing between body 10 and driven part 2. The cutting tool may be angularly adjusted relative to the longitudinal axis of driving part 1 as a result of the pivotal connection of body 10 to casing 4, 5. By making the tool-holder capable of both pivoting movement and lateral movement perpendicular to the tool axis, holes or bores may be formed by the tool which are not aligned with the axis of driving part 1 either as a result of angular or lateral displacement.

During rotation of the toolholder of Figs.

1-3, torque is transmitted from driving taper 3, through casing part 4 and balls 12 and into body 10 through peripheral slots 13.

From body 10, the torque is transmitted to the upper pair of second balls 30 through grooves 32, and into bearing ring 26 through grooves 28 in the upper surface of ring 26.

From ring 26, the torque passes into lower second balls 30 through lower grooves 28 and into driven part 2 through grooves 31 and bearing flange 22.

In Fig. 4, those features of the toolholder which are similar to those of the embodiment of Figs. 1-3 are indicated with like reference numerals. Casing part 4 and casing cover 5 of this embodiment are coupled in a suitable manner, e.g., by bolts. In the Fig. 4, the generally spherical body comprises two parts 10' and 10". These parts are fixed together in a suitable manner, e.g., by bolts, and define an internal recess 25' therebetween.

This recess corresponds to gap 25 of the embodiment of Figs. 1-3 and houses bearing flange 22 and roller bearing 20. The construction of roller bearing 20 is the same as that illustrated in Figs. 1-3. However, roller bearing 23 has been replaced by a plurality of balls 23' supported in the lower body part 10". Balls 23' support driven part 2 by bearing against a lower surface of bearing flange 22. A cutting tool is coupled to driven part 2 in the Fig. 4 embodiment within a driving taper 38. A slot 39 is formed in casing part 4 to facilitate the release of the cutting tool by use of a mandrel which may be inserted into slot 39.

An essential feature of the toolholders of both embodiments of the present invention is that the driven part may be both: (a) angularly adjusted to all sides relative to the rotational axis of the spindle and driving part 3, and (b) slideably adjusted in lateral directions perpendicular to the tool axis. The pivotal adjustment is provided by the ball and socket connection between body 10 and casing 4, 5. The lateral movement or adjustment is permitted by the spacing between driven part 2 and the openings within body 10 in which driven part 2 is mounted and by the construction of bearing 20. Thus, recess 8 in casing 4, 5, body 10 and bearing 20 provide a joint arrangement for coupling driving part 1 and driven part 2 for relative pivotal movement and lateral movement perpendicular to the tool axis. This joint arrangement provides the necessary adjustment with a single ball and socket type joint to simplify the toolholder.

The spring biased locking ball 16 illustrated in Figs. 1 and 2 can be replaced by a catch which can be threaded to secure body 10 relative to casing 4 and driving part 3. Such catch would retain body part 10 in angular alignment with driving part 1 (by eliminating the pivoting movement), while permitting lateral adjustment of driven part 2 relative to driving part 1.

It will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as claimed in the appended claims.

Claims (16)

1. A toolholder for a rotary tool, said toolholder comprising: a driving part adapted to be coupled to a spindle; a driven part adapted to mount a said tool (e.g. a cutting tool) along a tool axis; and joint means for coupling said driving and driven parts so as to permit relative pivotal movement and lateral movement thereof at least substantially perpendicularly (erg. 90 ) to said tool axis.

2. A toolholder as claimed in claim 1, comprising: a casing; a driving part coupled to said casing; a driven part having mounting means for coupling thereto (e.g. therein) a said tool (e.g.

a cutting tool) along a tool axis; and joint means mounted to said casing (e.g.

therein) for coupling said driving and driven parts so as to permit relative pivotal movement and lateral movement thereof at least substantially perpendicularly (e.g. 90 ) to said tool axis.

3. A toolholder as claimed in claim 1 or 2, wherein said joint means comprises: a substantially spherically shaped recess; and a substantially spherically shaped body mounted in said recess so as to permit pivotal movement to all sides.

4. A toolholder as claimed in any one of claims 1 to 3, wherein said recess comprises a portion of said casing.

5. A toolholder as claimed in any one of claims 1 to 4, wherein said joint means comprises a bearing plane on said body and roller bearing means supporting on said bearing plane said driven part.

6. A toolholder as claimed in claim 5, wherein said roller bearing means comprises a bearing ring with axial bores and radial grooves on each side thereof, said bores receiving first balls for directly transferring axial forces between said body and said driven part, said radial grooves receiving second balls for transmitting torque between said body and said driven part.

7. A toolholder as claimed in claim 6, wherein said driven part has a bearing flange; and said bearing flange and said body have radial grooves aligned with said radial grooves on the sides of said bearing ring which face said bearing flange and said body, respectively, which grooves receive respective second balls.

8. A toolholder as claimed in any one of claims 1 to 7, wherein said body and said casing are coupled for simultaneous rotation by balls mounted in said casing.

9. A toolholder as claimed in claim 8, wherein said body has peripheral slots for receiving said coupling balls.

10. A toolholder as claimed in any one of claims 1 to 9, wherein said joint means comprises means for locking in a predetermined position said body relative to said recess.

11. A toolholder as claimed in any one of claims 1 to 10, wherein said joint means comprises a space in said body, which space receives said driven part and has lateral dimensions greater than corresponding lateral dimensions of said driven part, so as to permit said lateral movement.

12. A toolholder as claimed in any one of claims 1 to 11, wherein said joint means comprises bearing means, for coupling said body and said driven part, so as to permit said lateral movement and transmitting therebetween of torque.

13. A toolholder, substantially as hereinbefore described with reference to and as shown in Figs. I to 3 of the accompanying drawings.

14. A toolholder, substantially as hereinbefore described with reference to and as shown in Fig. 4 of the accompanying drawings.

15. A toolholder as claimed in any one of claims 1 to 14, when holding a said rotary tool.

16. A toolholder as claimed in claim 15, wherein said rotary tool is a cutting tool.