AU773841B2

AU773841B2 - Shearing handpiece assembly

Info

Publication number: AU773841B2
Application number: AU59925/01A
Authority: AU
Inventors: Jian Ding; Lei Wang
Original assignee: XINJIANG AUSTRALIA UNITED MACH
Current assignee: XINJIANG AUSTRALIA UNITED MACHINERY Pty Ltd
Priority date: 1999-04-28
Filing date: 2001-08-16
Publication date: 2004-06-10
Anticipated expiration: 2019-04-28
Also published as: AU1135700A; AU5992501A; AU739668B2

Description

AUSTRALIA

PATENTS ACT 1990 DIVISIONAL APPLICATION NAME OF APPLICANT: Xinjiang Australia United Machinery Pty. Ltd.

ADDRESS FOR SERVICE: DAVIES COLLISON CAVE Patent Attorneys 1 Little Collins Street Melbourne, 3000.

INVENTION TITLE: "Shearing handpiece assembly" The following statement is a full description of this invention, including the best method of performing it known to us: P:\OPERDH{I 1357-00 div.do-16/08/01 -2- SHEARING HANDPIECE ASSEMBLY Field of the Invention The invention relates to a shearing handpiece assembly and, in particular, to an assembly for mounting a cutting fork in the handpiece.

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 cutting fork of the handpiece. Such movement can lead to vibration, heat generation and general wear.

Object of the Invention The invention seeks to provide an assembly for mounting a cutting fork in the handpiece to reduce vibration and heat generation.

Summary of the Invention In accordance with the invention, there is provided an assembly for pivotally mounting a cutting fork relative to a housing of a shearing handpiece, the assembly including a pivot post extending from the housing and a cup for receipt of an end of the post, wherein the cup is fitted in the fork and includes a bearing to provide for substantially smooth rotation between the fork and the pivot post.

Preferably, the bearing is provided about an outer periphery of the cup, in facing engagement with a bore formed in the cutting fork.

P:AOPER\DMI 1357-00 div.doc- 16/0801 -3- Preferably, the assembly includes a locating screw arranged in the housing opposite the pivot post, for capturing the cup between the pivot post and the screw.

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; Figure 3 is a view similar to that of Figure 2, showing a modified handpiece; Figure 4 is a cross-sectional view of part of a handpiece, showing an assembly for mounting a cutting fork; and Figure 5 is a cross-sectional view, similar to that of Figure 4, showing a modified assembly.

Detailed description of a preferred embodiment of the invention 20 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 of a cutting fork 50 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 5, via the cam mechanism 4. The handpiece also includes a coupling 10 between the handpiece 1 and an inner back-half joint 11.

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 P:PER\DMI 1357-00 div.do-160/01 -4housing, to prevent relative axial movement between the housing 2 and the sleeve 12, whilst still allowing for relative rotation 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-halfjoint 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-halfjoint 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 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.

P:'OPER\DHI 1357-0 di,.do.-1608/01 In either embodiment, the handpiece 1 may be further secured against unnecessary vibration, noise and/or heat generation by provision of an assembly 40 which includes a pivot post 41 (see Figure 1) which mounts the cutting fork 50 relative to the housing, intermediate the cutter 5 and drive shaft 6. In operation then, the cutting fork is constrained to rotate about the post 41. A cup 42 is fitted in the cutting fork 50 and an adjustable locating screw 44 is provided to capture the cup between the pivot post 41 and the screw 44. As shown in more detail in Figure 4, the cup 42 includes a bearing 45 about an outer periphery 46 thereof. The bearing 45 is positioned in direct facing arrangement with a bore 47 formed in the cutting fork 50 so as to facilitate smooth rotation of the cutting fork about the post 41, during oscillatory cutting motion. The cup 42 also has an outwardly flared open end 48 to accommodate changes in orientation between the fork and the post 41 when the fork 50 is pivoted in an end to end manner such as when the cutter 5 is tensioned against the cutter head 3 via adjusting screw 49.

15 A modified assembly 40 is shown in Figure 5, where like reference numerals denote like parts. The assembly of Figures 4 and 5 is essentially the same except that a second axially positioned bearing 51 is provided in the cup 42 and the configuration of the pivot post 41 is altered accordingly. With either of the assemblies 40, however, it should be appreciated S:that smooth rotation of the cutting fork may be achieved to thereby further minimise vibration of the handpiece and resultant heat generation.

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.

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Claims

1. An assembly for pivotally mounting a cutting fork relative to a housing of a shearing handpiece, the assembly including a pivot post extending from the housing and a cup for receipt of an end of the post, wherein the cup is fitted in the fork and includes a bearing to provide for substantially smooth rotation between the fork and the pivot post.

2. An assembly as claimed in claim 1, wherein the bearing is provided about an outer periphery of the cup, in facing engagement with a bore formed in the cutting fork.

3. An assembly as claimed in claim 1 or 2, wherein the assembly includes a locating screw arranged in the housing opposite the pivot post, for capturing the cup between the pivot post and the screw.

4. An assembly, substantially as hereinbefore described with reference to Figures 4 and 5 of the drawings. DATED this 16th day of August, 2001 Xinjiang Australia United Machinery Pty Ltd .By DAVIES COLLISON CAVE Patent Attorneys for the applicant *o*