AU1135700A - Shearing handpiece - Google Patents

Description

Regulation 3.2

AUSTRALIA

Patents Act 1952 COMPLETE

SPECIFICATION

FOR A STANDARD

PATENT

(ORIGINAL)

*M

a

C

CC *V.

Name of Applicant: Actual Inventor: Xinjiang Australia United Machinery Pty Ltd 59 Ressiter Avenue, Roxburgh Park, Victoria 3064, Australia DING, Jian Address for Service: DAVIES COLLISON CAVE, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

Invention Title: "Shearing handpiece" The following statement is a full description of this invention, including the best method of performing it known to us: -1- P:\OPER\DH\SHEAR.DIV- 14/1/00 -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. In another aspect, the invention relates 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.

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, P:\OPER\DH\SHEAR.DIV- 14/1/00 -3as described above. Further, servicing becomes somewhat difficult since each part of the mechanism 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. As an alternative object, the invention seeks to provide an assembly for mounting a cutting fork in the handpiece to further reduce vibration and heat generation.

Summary of the Invention In accordance with the invention, there is provided a shearing handpiece including a housing o 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 0 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 osleeve and the shaft.

•oooo 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.

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 P:\OPER\DH\SHEAR.DIV 14/1/00 -4rotation therebetween, wherein 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.

Preferably, the handpiece includes a cutting fork, a cam mechanism for transferring rotational movement of the shaft into oscillatory cutting motion of the fork and an assembly for "'"pivotally mounting the cutting fork relative to the housing, 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. More preferably, a locating screw is provided in the housing, opposite the pivot post, for capturing the cup between the pivot post and the screw.

oooo In another aspect, 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.

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 P:\OPER\DH\SHEAR.DIV 14/1/00 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 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 o*o.

via the cam mechanism 4. The handpiece also includes a coupling 10 between the handpiece 1 and an inner back-half joint 11.

20 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 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.

P:\OPER\DH\SHEAR.DIV 14/1/00 -6- 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 housing 2 dispenses with the "-"need for an additional bush, as provided in the known form of handpiece and, as a result of o•.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.

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 P:\OPER\DH\SZEAR DIV 14/1/00 -7bearing 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 50 and the post 41 when the fork 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.

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 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 ei a °o invention as described.

Claims (12)

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 the bearing assemblies and the sleeve are formed as a unitary structure.

4. 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 *oo* extending from the back-half joint into the housing for relative rotation therebetween, wherein the sleeve is in direct facing engagement with the housing. oo

5. A shearing handpiece as claimed in any one of the preceding claims, 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.

6. A shearing handpiece as claimed in claim 5, wherein the locating structure is in the form of ball bearings provided in an annular recess of the housing.

7. A shearing handpiece as claimed in any one of the preceding claims, wherein the handpiece includes a cutting fork, a cam mechanism for transferring rotational movement of the shaft into oscillatory cutting motion of the fork and an assembly for pivotally mounting P:\OPER\DH\SHEARDIV 14/1/00 -9- the cutting fork relative to the housing, 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.

8. A shearing handpiece as claimed in claim 7, wherein a locating screw is provided in the housing, opposite the pivot post, for capturing the cup between the pivot post and the screw.

9. 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 9*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.

An assembly as claimed in claim 9, wherein the bearing is provided about an outer periphery of the cup, in facing engagement with a bore formed in the cutting fork.

11. An assembly as claimed in claim 9 or 10, 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.

12. A shearing handpiece, substantially as hereinbefore described with reference to the drawings. °ooio DATED this 14th day of January, 200 Xinjiang Australia United Machinery Pty Ltd By DAVIES COLLISON CAVE Patent Attorneys for the applicant