AU711642B3

AU711642B3 - Shearing handpiece

Info

Publication number: AU711642B3
Application number: AU24985/99A
Authority: AU
Inventors: Jian Ding
Original assignee: XINJIANG AUSTRALIA UNITED MACH
Current assignee: XINJIANG AUSTRALIA UNITED MACHINERY Pty Ltd
Priority date: 1999-04-28
Filing date: 1999-04-28
Publication date: 1999-10-21
Anticipated expiration: 2005-04-28

Description

Regulation 3.2

AUSTRALIA

Patents Act 1990 PETTY PATENT SPECIFICATION

(ORIGINAL)

Name of Applicant: Xinjiang Australia United Machinery Pty Ltd Actual Inventor: DING, Jian Address for Service: DAVIES COLLISON CAVE, Patent Attorneys, of 1 Little Collins Street, Melbourne, Victoria 3000, Australia Invention Title: "Shearing handpiece" The following statement is a full description of this invention, including the best method of performing it known to me: -1 IP Australia D Documents received on: a 0 2 8 APR 1999 Batch No

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p:\I OPER\NDHMSUAR.E 28/4/99 -2- SHEARING HANDPIECE Field of the Invention The invention relates to a shearing handpiece and, in particular, to a coupling between the handpiece and an inner back-half joint.

Background of the Invention A known form of shearing handpiece includes a housing with a cutting head at one end and an inner back-half joint at the other end. The inner back-half joint forms part of a coupling used to transmit rotational drive force to a drive shaft of the handpiece. The shaft has a crank head which forms part of a cam mechanism to translate the rotational movement of the shaft into lateral oscillating movement of a cutter of the handpiece.

An example of such a handpiece is disclosed in Australian Petty Patent No.664,688. In that handpiece, the back-half joint includes an elongate sleeve which is mounted concentrically within a bush of the handpiece and the drive shaft is in turn mounted concentrically within the sleeve. The handpiece also includes a bearing between an end of the shaft and the sleeve and a second bearing of larger diameter, adjacent the crank head, between the shaft and the housing.

The shaft generally rotates at high speed and any misalignment or play between the housing, the back-half joint and the shaft will lead to vibration which in turn may cause heating of the handpiece and a reduction in operating efficiency. The vibration may also increase the rate at which component parts of the handpiece need replacing.

Since a number of concentrically arranged components are used in the handpiece of Petty Patent No. 664688, it is likely some minor play may result so as to lead to adverse vibration, as described above. Further, servicing becomes somewhat difficult since each part of the P:\OPER\DH\SHEAR.SPE 28/4/99 -3mechanism is independently mounted in the handpiece. For example, to replace the second bearing, the entire handpiece needs to be disassembled by firstly removing the back-half joint, the sleeve and associated first bearing, followed by a sealing ring and retaining clip to allow the bush to be removed. After the bush is removed the second bearing may finally be accessed for removal after the shaft itself has been withdrawn.

Object of the Invention The invention seeks to provide a simpler handpiece construction which is less susceptible to vibration.

Summary of the Invention In accordance with the invention, there is provided a shearing handpiece including a housing with a drive shaft mounted therein and a coupling for mounting a back-half joint in the housing, the coupling including a sleeve extending from the back-half joint into the housing for relative rotation therebetween, wherein the coupling includes first and second bearing assemblies mounted to the sleeve, at spaced locations for bearing engagement between the sleeve and the shaft.

Accordingly, the bearing assemblies and the sleeve may form a unitary structure which may be readily removed from the handpiece for servicing or replacement.

Preferably, the sleeve is in direct facing engagement with the housing.

Preferably, a groove is provided about a circumference of the sleeve, for registering with locating structure of the handpiece, so as to prevent relative axial movement between the housing and the sleeve, whilst allowing for free rotation therebetween. Preferably, the locating structure is in the form of ball bearings provided in an annular recess of the housing.

P:\%PER\DHSHAR.SPE 28/4/99 -4- In another aspect, there is provided a shearing handpiece including a housing with a drive shaft mounted therein and a coupling for mounting a back-half joint in the housing, the coupling including a sleeve extending from the back-half joint into the housing for relative rotation therebetween, wherein the sleeve is in direct facing engagement with the housing.

Brief Description of the Drawings The invention is described by way of non-limiting example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic cross sectional view of a shearing handpiece; Figure 2 is an enlarged view of part of the handpiece of Figure 1; and Figure 3 is a view similar to that of Figure 2, showing a modified handpiece.

Detailed description of a preferred embodiment of the invention Referring firstly to Figure 1, a shearing handpiece 1 is shown as including a housing 2 a cutting head 3, a cam mechanism 4 for driving a cutter 5 and a drive shaft 6 mounted in a handle 7 formed by the housing 2. The drive shaft 6 includes a crank head 8 which allows rotational movement of the shaft 6 to be translated to oscillatory cutting motion of the cutter via the cam mechanism 4. The handpiece also includes a coupling 10 between the handpiece 1 and an inner back-half joint 1 The coupling is described in more detail in Figure 2 as including an elongate sleeve 12 which serves to mount the back half joint 3 in the housing 2 for relative rotation therebetween. The sleeve 12 is in direct facing engagement with the housing 2 and includes a circumferential groove 13 which registers with locating structure 14, in the form of ball bearings 15 which are accommodated in an annular recess 16 formed within the housing, to prevent relative axial movement between the housing 2 and the sleeve 12, whilst still allowing for relative rotation P:\OPER\DH\SHEAR.SPE 28/4/99 therebetween. The housing 2 also includes an access opening 17 which is closed by a suitable screw 18. The screw 18 may be removed if required to grease the bearings or allow removal of same to facilitate removal of the back-half joint 11 from the housing 2.

The coupling 10 also includes first and second bearing assemblies 19 and 20 to allow for relative rotation between the shaft 6 and the sleeve 12. The first bearing assembly includes two adjacent bearings 21 which are captured between circlips 22 and the second bearing assembly 20 includes a single bearing 23, which is formed in an identical manner to, and with the same dimension as, the bearings 21. The assemblies 19 and 20 are spaced apart in a direction of extent of the sleeve by a spacer 24. The bearing assemblies 19, 20 thereby form a unitary structure with the sleeve 12 such that removal of the back-half joint 11 from the housing 2 simultaneously effects removal of the bearings for maintenance and the like.

The one step action of removing the bearings 21, 23 with the sleeve 12, provides a significant advantage as compared to the known form of shearing handpiece in which each of the components needed to be separately removed for maintenance. Further, providing the bearings between only the sleeve 12 and the shaft 6 results in an advantage that identically dimensioned bearings may be utilised which again simplifies construction and replacement difficulties. The direct engagement between the sleeve 12 and a housing 2 dispenses with the need for an additional bush, as provided in the known form of handpiece and, as a result of reduced component parts, decreases the opportunity for vibration and wear between the parts which may otherwise result.

In a modified embodiment, as shown in Figure 3, where like parts to those shown in Figures 1 and 2 are denoted with like reference numerals, the bearings 19, 20 are mounted to abut opposed ends 30 of the sleeve 12, instead of wholly within the sleeve so that the spacer 24 can be dispensed with, to further reduce componentry of the handpiece 1.

The shearing handpiece has been described by way of example only and many modifications and variations may be made thereto without departing from the spirit and scope of the invention as described.

Claims

1. A shearing handpiece including a housing with a drive shaft mounted therein and a coupling for mounting a back-half joint in the housing, the coupling including a sleeve extending from the back-half joint into the housing for relative rotation therebetween, wherein the coupling includes first and second bearing assemblies mounted to the sleeve, at spaced locations for bearing engagement between the sleeve and the shaft.

2. A shearing handpiece as claimed in claim 1, wherein the sleeve is in direct facing engagement with the housing.

3. A shearing handpiece as claimed in claim 1 or 2, wherein a groove is provided about a circumference of the sleeve, for registering with locating structure of the handpiece, so as to prevent relative axial movement between the housing and the sleeve, whilst allowing for free rotation therebetween.