GB2501100A

GB2501100A - Shearing hand-piece body with internal tubular bush

Info

Publication number: GB2501100A
Application number: GB1206451.5A
Authority: GB
Inventors: John Alun Harris Williams; Robin James Howell; Jamie William Michael Stanfield; Wayne Thomas Mason
Original assignee: Lister Shearing Equipment Ltd
Current assignee: Lister Shearing Equipment Ltd
Priority date: 2012-04-12
Filing date: 2012-04-12
Publication date: 2013-10-16
Also published as: AU2013204287A1; AU2013204287B2; GB2502877A; GB2502877B; GB201206451D0; GB201306644D0

Abstract

A sleeve bush 30, a back half joint 40 and a spindle 50 are provided in a through bore 21 of a shearing hand-piece body 10. The bush 30 has rearward and forward ends 32, 34. The back half joint 40 rotates relative to the body 10, and the spindle 50 rotates relative to the body 10 and back half joint 40. A first bearing 60 is retained within the interior of the sleeve bush 30. The spindle 50 has forward, intermediate and rearward portions 52, 54, 56, and the intermediate portion 54 may have a larger diameter than the forward and rearward portions 52, 56. The bearing 60 may be formed integrally with the bush 30. Axial movement of the first bearing 60 relative to the bush 30 may be prevented via retaining means such as clips 70, 72. Axial movement of the bush 30 relative to the body 10 may be prevented via retaining means such as a flange 36 and/or connector 38, or a forward shoulder (22, fig. 2) and rearward resilient means (90, fig 2) of body 10. A second bearing 80 may be provided between the spindle and inner back half joint.

Description

Improvements In or Relating To the Assembly of a Shearing Handpiece Body The present invention relates to a shearing handpiece body and particularly to the retention of a sleeve bush and associated bearings within the shearing handpieee body.

A shearing handpiece typically includes a handpiece body having a crank spindle which drives a crank pin. The crank pin carries a crank roller. The crank roller, in turn, drives a fork assembly which converts thc rotational motion of thc crank pin into reciprocal lateral motion. The crank spindle is typically supported within the handpiece body by a front bearing which is mounted to the handpiece body, and a rear bearing which is mounted to a portion of the shearing handpiece known as the back joint. In the prior art the front bearing is typically seated against a forward shoulder within the handpiece body. During assembly of the shearing handpiece, the front bearing is inserted into the handpiece body from the rear and moved into engagement with the forward shoulder. The shoulder thus prevents further axial movement in a forward direction.

The outer diameter of the front bearing is mounted into a forward bearing seat within the shearing handpiece body. Behind the forward bearing seat within the shearing handpiccc body is a larger diameter rear bore into which the external diameter of a sleeve bush is mounted. The external diameter of the inner back half joint is then assembled within the internal bore of the sleeve bush such that the inner back half joint is free to rotate. The rear bearing is mounted into a rear bearing seat within the inner back halfjoint.

In order for the handpiece to operate reliably, it is important that the front and rear bearings are in vety close axial alignment and concentric with one another such that the crank spindle and inner back half joint can rotate freely. It follows therefore that, amongst other requirements, the front bearing seat and rear bore of the shearing handpiece body, along with the external diameter and internal bore of the sleeve bush, along with the external diameter and rear bearing seat of the inner back half joint, must all have close axial alignment and be concentric with each other.

During the manufacturing process of a handpiece it is very difficult to achieve perfect alignment and concentricity between all six of the above specified critical diameters', firstly due to limitations in the processes used to manufacture the shearing handpiece body and sleeve bush, and secondly due to misalignment errors which may be introduced during the assembly procedure.

The present invention seeks to improve the alignment between the front bearing and rear bearing of a handpiece. It does this firstly by eliminating the requirement for (at least) two of the critical diameters' to either exist or else to be aligned and concentric with the other critical diameters', and secondly by enabling the two critical diameters into which the front bearing and inner back half joint are assembled to be ground / machined concurrently into a separate cylindrical cartridge', thereby simplif'ing the machining operations required during production of the complex shaped shearing handpiece body. The present invention also seeks to ease the assembly procedures by reducing the number of operations that require accurate alignment to be maintained.

According to the first aspect of the present invention there is provided a shearing handpiece body having a through bore, the through bore defining a longitudinal space within which there is provided a sleeve bush, an inner back half joint and a spindle, and wherein the shearing handpiece body includes a first bearing retained to the interior of the sleeve bush between the interior of the sleeve bush and the spindle.

The sleeve bush features a flange at its proximal end which abuts the shearing handpiece body so as to prevent axial movement of the sleeve bush relative to the shearing handpiccc body in the distal direction. Here the terms distal and proximal refer to the two ends of the shearing handpiece body, with the proximal end being commonly referred to as the "back end" where the handpiece connects to a drive arrangement, and the distal end being commonly referred to as the "front end" where the comb and cutter arc located. In one embodiment a connection may provided towards the proximal end of the shearing handpiece body which prevents axial movement of the sleeve bush relative to the shearing handpiece body in the proximal direction. The connection is a screw which extends through an aperture in the shearing handpiece body and an aligned recess of the sleeve bush.

In an alternative embodiment axial movement of the sleeve bush relative to the handpiece body may be achieved by other means. For example, a threaded portion of the sleeve bush may be received in and mated to a eomplementarily threaded portion of the handpieee body.

The front bearing is pre-assembled into the sleeve bush and held in place between two bearing retainers, preferably cirelips, within the sleeve before the whole lot is pressed into the handpieee. Movement of the bearing in an axial direction is prevented by these bearing retainers.

In an alternative embodiment the sleeve bush may define the outer race of the front bearing.

The front bearing may be a double row bearing. In an alternative embodiment the sleeve may be provided with multiple single row front bearings.

Advantageously the through bore of the shearing handpiece body is straight and requires neither a shoulder nor a recess, leading to simpler machining of the part and less wastage of material during manufacture. Also it will be appreciated that the present invention eliminates the front bearing seat found in handpiece bodies known from the prior art. This thereby removes one of the diameters within the handpieee body which, as mentioned above, was previously critical to the alignment and concentricity of the front and rear bearings. Further it will be appreciated that in the present invention the alignment and concentricity of the external diameter of the sleeve bush is no longer critical to the alignment and concentricity of the front and rear bearings.

Preferably the distal portion of the bore of the sleeve bush where the front bearing is mounted has the same diameter as the proximal portion of the sleeve bush bore into which the back joint is assembled. This ifirther minimises the number of critical diameters' within the shearing handpiece which must be within very close axial alignment and concenflic with respect to each other.

According to an alternative embodiment of the present invention, the shearing handpiece body may includes a shoulder which abuts the distal end of the sleeve bush so as to prevent axial movement of the sleeve bush relative to the shearing handpiece body in the distal direction.

The shearing handpiece body may further include a recess in its bore such that when the sleeve bush is inserted into said bore, a resilient retaining means can located in said recess and abut the proximal end of the sleeve bush, to substantially prevent axial movement of said sleeve bush relative to the shearing handpiccc body when the shearing handpiece body is loaded axially through a forward stroke of the shearing handpiece body.

According to a second aspect of the present invention there is provided a method of assembling a sleeve bush and a bearing to a shearing handpiece body, the method comprising the steps of providing a sleeve bush and bearing sub assembly, the bearing being retained within the sleeve bush, fitting the subassembly to a through bore of the handpiece body; and axially locating the sleeve bush within the through bore.

According to a third aspect of the present invention there is provided a shearing handpiece sleeve bush comprising a tubular member having first and second ends wherein a bearing is retained in the bore of the tubular member at a location closer to one of the ends than the other.

Advantageously the sleeve bush, front bearing, bearing retaining means and spindle can be loaded and unloaded in the manner akin to a cartridge to allow for simple cleaning, replacement and maintenance. Furthermore this cartridge' sub-assembly minimises the number of critical diameters' within the shearing handpiece which must be within very close axial alignment and concentric with respect to each other.

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Embodiments of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 shows a cross-sectional view of the rear portion of the shearing handpiece body according to a first embodiment of the present invention; Figure 2 shows a cross-sectional view of the rear portion of the shearing handpiece body according to a second embodiment of the present invention; Figure 3 shows a cross-sectional view of the rear portion of the shearing handpiece body according to a third embodiment of the present invention; Figure 4 shows a cross-sectional view of the rear portion of the shearing handpiece body according to a fourth embodiment of the present invention; and Figure 5 shows a cross-sectional view of a combined bearing and sleeve bush assembly of the embodiment of figure 4.

Referring firstly to figure 1 there is shown a cross-sectional view of the shearing handpiece generally designated 10. The shearing handpiece includes a handpiece body having a through bore 21 defining a longitudinal space, a sleeve bush 30, an inner back half joint 40 and a crank spindle 50, all retained within the longitudinal space.

The crank spindle 50 includes a crank pin 51 which is offset in relation to the rotational axis 53 of the crank spindle 50. The crank spindle 50 is supported by a first bearing 60 and a second bearing 80.

The sleeve bush 30 has a proximal end 32 and a distal end 34. The terms "proximal" and "distal" are construed with reference to an operator who holds the shearing handpiece body 20 in use.

The proximal end 32 of the sleeve bush 30 features a flange 36, which abuts the shearing handpiece body 20 so as to prevent axial movement of the sleeve bush 30 relative to the shearing handpiece body 20 in the distal direction. The shearing handpiece body 20 also features a hole 23 which aligns with a recess 37 in the sleeve bush 30 so that a connector 38 can be fitted in order to prevent axial movement of the sleeve bush 30 relative to the shearing handpieee body 20 in the proximal direction.

Said hole 23 is threaded. In the embodiment shown the connector 38 is a screw. It will be appreciated that other forms of connector may be used, for example a roll pin.

The distal end 34 of the sleeve bush 30 is chamfered 39 to assist insertion of the sleeve bush 30 into the through bore 21 defined by the shearing handpieee body 20.

The first bearing 60 is prevented from moving axially relative to the sleeve bush 30 by a first retaining means 70, in the form of a cirelip, abutting its forward face 62 and a second retaining means 72, also in the form of a eirclip, abutting its rearward face 64, in addition to a step 58 between the crank spindle forward portion 52 and the crank spindle intermediate portion 54, which also abuts its rearward face 64. The first and second circlips 70 and 72 are located longitudinally in a first annular recess 71 and second annular recess 73 respectively, in the sleeve bush 30.

The second bearing 80 is prevented from moving axially relative to the sleeve bush 30 by a third retaining means 74, also in the form of a circlip, abutting its rearward face 84 and the inner back half joint 40 abutting its forward face 82 in addition to a step 59 between the crank spindle intermediate portion 54 and the crank spindle rearward portion 56, which also abuts its forward face 82. The third circlip 74 is located longitudinally in an annular recess 75 in the inner back half joint 40. The inner back half joint 40 is rotatable with respect to the sleeve bush 30 and is retained axially thanks to the second bearing 80.

At the proximal end 32 of the sleeve bush 30 is a dust seal 45, located between the flange 36 of the sleeve bush and the inner back half joint 40.

Referring now to Figure 2, there is shown a second embodiment of the present invention generally designated 110. Features similar to the embodiment of figure 1 arc identified with like reference numerals prefixed with 1.

The shearing handpiece includes a handpiece body 120 having a through bore 121 defining a longitudinal space, a sleeve bush 130, an inner back half joint 140 and a crank spindle 150, all retained within the longitudinal space. The crank spindle 150 includes a crank pin 151 which is offset in relation to the rotational axis 153 of the crank spindle 150. The crank spindle 150 is supported by a first bearing 160 and a second bearing 180.

The sleeve bush 130 has a proximal end 132 and a distal end 134. The terms "proximal" and "distal" are construed with reference to an operator who holds the shearing handpiece body in use.

The shearing handpiece body 120 includes a shoulder 22 which abuts the distal end 134 of the sleeve bush 130. This prevents axial movement of the sleeve bush 130 relative to the shearing handpiece body 120 in the distal direction. The shearing handpiece body 120 further including an annular recess 24 in its through bore 121 such that when the sleeve bush 130 is inserted into said through bore 121, a resilient retaining means 90 is located in said annular recess 24 and abutting the proximal end 132 of the sleeve bush 130, thereby preventing axial movement of the sleeve bush 130 relative to the shearing handpiece body 120 in the proximal direction.

At the proximal end 132 of the sleeve bush 130 is a dust seal 145, located between the shearing handpiece body 120 and the inner back halfjoint 140.

It will be appreciated that the arrangements for the first and second bearings 160, 180 of the second embodiment are similar to that of the arrangements for the first and second bearings 60, 80 of the first embodiment, when comparing figures 1 and 2 and therefore no further description of these arrangements is necessary.

Figure 3 shows a further embodiment of the present invention generally designated 210. Features common to the embodiment described with reference to figure 1 are identified with like reference numerals.

The embodiment of figure 3 differs from the embodiment of figure 1 in that handpiece body and sleeve bush 20,30 are not provided with the respective hole 23 and recess 37, and connector 38. Instead, the distal end 34 of the sleeve bush 30 is provided with a thread 35, while the distal end of the handpiece through bore 21 is provided with a

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corresponding thread 25. It will be appreciated that the interengagement of the threads 35,25 prevents axial movement of the sleeve bush 30 relative to the shearing handpiece body 20 in the proximal direction.

Figures 4 and 5 show a further embodiment of the present invention generally designated 310. Features common to the embodiment described with reference to figure 2 are identified with like reference numerals.

The embodiment of figures 4 and 5 differs from that described with reference to figure 2 in that it is not provided with a separate sleeve bush 130 and bearings 160, where the bearings 160 are retained in the sleeve bush 130 by cirelips 170,172. Instead, the sleeve bush is formed integrally with the bearings 360. More specifically, the outer race 361 of the bearings 360 is extended so as to have a length that is substantially equivalent to that of the sleeve bush 130.

Claims

Claims 1. A shearing handpiecc body having a through bore defining a longitudinal space within which there is provided a sleeve bush, an inner back half joint and a spindle, the sleeve bush having a proximal end and a distal end, the inner back half joint being rotatable relative to the handpiece body, the spindle also being rotatable relative to the handpiece body and the inner back half joint, and the spindle having forward, intermediate and rearward portions, wherein the shearing handpieee body includes a first bearing retained within the interior of the sleeve bush.
2. The shearing handpieee body of claim 1 wherein the intermediate portion of the spindle has a larger diameter than both the forward and rearward portions of the spindle.
3. The shearing handpicce body of any preceding claim wherein the first bearing is prevented from moving axially relative to the sleeve bush by a retaining means, the first bearing and retaining means being located substantially towards the distal end of the sleeve bush.
4. The shearing handpieee body of the claim 3 wherein the first bearing has a forward face and a rearward face, the first bearing forward face being located against a first retaining means and the first bearing rearward face being located against a second retaining means and a step defined between the spindle forward portion and the spindle intermediate portion.
5. The shearing handpiece body of any preceding claim within which there is further provided a second bearing, wherein the second bearing is retained between the spindle and the inner back halfjoint.
6. The shearing handpiccc body of claim 5 wherein the second bearing has a forward face and a rearward face, the second bearing forward face being located against the inner back half joint and a step defined between the spindle intermediate portion and the spindle rearward portion, and the second bearing rearward face being located against a third retaining means.
7. The shearing handpiece body of any preceding claim wherein the distal end of the sleeve bush is chamfered to facilitate insertion of the sleeve bush into the shearing handpiece body.
8. The shearing handpieee body of any preceding claim wherein the sleeve bush further includes a flange at its proximal end which abuts the shearing handpiece body so as to prevent axial movement of the sleeve bush relative to the shearing handpiece body in the distal direction.
9. The shearing handpieee body of claim 8, thrthcr including a connector which prevents axial movement of the sleeve bush relative to the shearing handpiece body in the proximal direction.
10. The shearing handpiece body of claim 9, wherein the connector is a screw which extends through an aperture in the shearing handpiece body and an aligned recess of the sleeve bush.
11. The shearing handpiece body of any claims 1 to 8 whereby the shearing handpiece body includes a shoulder which abuts the distal end of the sleeve bush so as to prevent axial movement of the sleeve bush relative to the shearing handpiece body in the distal direction.
12. The shearing handpiece body of claim 11 wherein the shearing handpiece body features a recess in its bore, such that when the sleeve bush is inserted into said bore, a resilient retaining means is located in said recess and abuts the proximal end of the sleeve bush, to substantially prevent axial movement of said sleeve bush relative to the shearing handpiece body when the shearing handpieee body is loaded axially through a forward stroke of the shearing handpiece body.
13. The shearing handpiece body of any preceding claim whereby the resilient bearing retainer is a circlip.
14. The shearing handpiece body of claim 8, wherein a portion of the sleeve bush is threaded and engages with a complementarily threaded potion of the shearing handpiece body so as to prevent axial movement of the sleeve bush relative to the shearing handpiece body.
15. The shearing handpiece body of claim 1 wherein the first bearing is formed integrally with the sleeve bush.
16. The shearing handpiece body of claim 15 wherein the sleeve bush defines an outer race of the first bearing.
17. A method assembling a sleeve bush and a bearing to a shearing handpiece body, the method comprising the steps of: providing a sleeve bush and bearing sub assembly, the bearing being retained within the sleeve bush, fitting the subassembly to a through bore of the handpiece body; and axially locating the sleeve bush within the through bore.
18. A shearing handpiece sleeve bush comprising a tubular member having first and second ends wherein a bearing is retained in the bore of the tubular member at a location closer to one of the ends than the other.
19. A shearing handpiece body substantially as hereinbefore described with reference to or as shown in figure 1, figure 2, figure 3 or figure 4.
20. A shearing handpiece sleeve bush substantially as hereinbefore described with reference to or as shown in figure 1, figure 2, figure 3 or figures 4 and 5.