GB2378407A

GB2378407A - Bearing assemblies for a shearing handpiece

Info

Publication number: GB2378407A
Application number: GB0215688A
Authority: GB
Inventors: Wayne Russell Small
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-07-06
Filing date: 2002-07-08
Publication date: 2003-02-12
Also published as: GB0215688D0; NZ520033A; AUPR619001A0

Abstract

A bearing assembly 90 for a shearing handpiece, the handpiece having a pivoting fork body 13 supported on a center post 30, the bearing assembly 90 being adapted to be positioned between the fork body 13 and the center post 30 and comprising a first contact surface for supporting the fork body 13, a second contact surface for mounting on a center post 30, and bearing means disposed between the first and second surfaces. A bearing means 66 provided between the stem 63 on the crank head 61 and the crank roller 62, and a shearing handpiece incorporating the features described above.

Description

FORK BODY BEARING ASSEMBLY FOR A SHEARING HANDPIECE The present invention relates to a fork body bearing assembly adapted to be located between the fork body and a supporting member in a shearing handpiece.

Specifically, the present invention relates to a fork body bearing assembly adapted to sit on the centrepost in a shearing handpiece or be located on the crankroller in a shearing handpiece.

Mechanically driven handpieces are used by shearers for shearing sheep and other fleecy animals. The handpieces are usually connected as a series in shearing stations, which are driven by a single overhead pulley system.

Figure A illustrates a stand-alone shearing station 20.

At the top of the station is an electric motor which axially drives a long vertical shaft known as the inner long gut 22 at high speeds of approximately 3000 rpm. An outer down tube 21 extends downwardly from the electric motor and houses the inner long gut-The lower end of the inner long gut is connected by way of elbow drive cogs 23 to an inner short gut 24. Rotary motion of inner long gut 22 is transferred by drive cogs 23 into rotary motion of short gut 24. Short gut 24 in turn couples to the back , joint of a shearing handpiece 10 by way of drive cogs at the back of the handpiece- Figure B illustrates a known shearing handpiece 10. The rotating short gut 24 causes a spindle 11 in the housing 16 of the handpiece to rotate. A crankhead assembly 12 at the end of the spindle converts the rotary motion of the spindle into reciprocal linear motion of a fork body 13.

A crankroller 25 is located in the fork body 13 to receive spindle 11 and provide a bearing surface for the rotating spindle against the fork body. The end of the fork body

supports cutters 14. The reciprocal motion of the cutters against a closely mounted comb 15 shears the wool as the handpiece is guided through the animal's fleece. The fork body 13 reciprocally pivots on a centrepost 30 screwed into an underside of the handpiece housing 16 at 3000 cycles per minute. A cup insert 19 in a fork body aperture 32 receives and pivots on the centrepost 30. The centrepost is carefully adjusted when the handpiece is new to ensure the fork body sits correctly in relation to the crankroller 25 and the cutters. The centrepost is generally not adjusted again in the life of the handpiece as this would disrupt the balanced interaction of handpiece components as they wear. Incorrect adjustment produces vibrations and a poor cut.

Frequently oiling and greasing of the handpiece and driving components is necessary owing to the large number of moving parts. Each of the drive cogs, crankhead assembly, centrepost, fork, comb and cutter require oiling every half hour the handpiece is in use. As oiling every half hour can become burdensome this requirement is not always adhered to and the parts become dry and wear much faster. The centrepost is particularly vulnerable to wearing given the constant pivoting of the fork body on tho centrepost. Wearing of the centrepost directly affects the quality and efficiency of the shearing. The - crankhead assembly too is susceptible to wear when not lubricated. Wearing of the centrepost and crankhead assembly also occurs if the cutters being used are worn down or are old and have been repeatedly ground to form new edges. Cutters generally wear after 15-20 minutes of use. Their edges are then resharpened. With old and worn cutters the fork body tends to tilt forwardly of the front of the handpiece causing the centrepost and crankshaft to be unevenly located in the fork body and thereby making them more susceptible to wear.

It is therefore intended with the present invention to alleviate some of the problems associated, with known shearing handpieces to increase shearing efficiency and the quality of the cut.

According to the present invention there is provided a bearing assembly for a shearing handpiece, the handpiece having a pivoting fork body supported on a centrepost, the bearing assembly adapted to be positioned between the fork body and centrepost and comprising : a first contact surface for supporting the fork body, a second contact surface for mounting on a centre post; a bearing means disposed between the first and second surfaces.

The first and second contact surfaces are preferably defined by a first and second annular race respectively, with bearing elements located between the first and second races. The bearing elements can be ball bearings, tapered roller bearings, needle roller bearings or the like.

In one embodiment, the second contact surface has a recess suitable for receiving a centrepost of the handpiece such that the bearing assembly is mounted on the centrepost.

The first race preferably has a central hollow projection which is inserted into, and supports, the fork body. The 'second race, in this embodiment, has a smaller central projection that fits into the central hollow projection of the first race, the bearing elements located radially of the central projections. The first contact surface is preferably contoured to conformally seat the fork body.

According to the present invention there is still further provided a bearing assembly for a shearing handpiece, the handpiece having a rotating spindle adapted to drive a fork body, wherein the bearing assembly is disposed between the spindle and the fork body and comprises: a substantially cylindrical crankhead axially mounted to the

spindle and having an eccentrically projecting stem ; an annular crankroller adapted to be located on the fork body and having a central bore for receiving the stem ; and a bearing means provided between the stem and the crankroller.

The bearing means is preferably located around the circumference of the stem and is typically an array of needle rollers. An annular shoulder is preferably provided on the crankhead and an annular collar is preferably provided at the end of the bore opposite the crankhead. The annular shoulder and annular collar axially encase the bearing means. Bulbous portions on the shoulder and collar extend toward the bearing means to retain alignment of the bearing means According to the present invention there is still further provided a bearing assembly for a shearing handpiece, the handpiece having a pivoting fork body carrying shearing cutters and is supported on a centrepost and driven by a crankhead mounted on a rotating spindle, the bearing assembly being provided between one of the centrepost or crankhead, and the fork body, the bearing assembly comprising a bearing means.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is described further by way of example with reference to the accompanying drawings by which : Figure A is a perspective view of a shearer's station ; Figure B is a side sectional view of a known shearing handpiece ; Figure 1 is a side sectional view of a shearing

handpiece provided with a bearing assembly according to a first embodiment of the present invention ; Figure 2 is an end sectional view of the handpiece taken at line 2-2 of Figure 1 ; Figure 3 is a side sectional view of the embodiment illustrated in Figure 1 ; Figure 4 is a perspective transparent view of the embodiment illustrated in Figure 1 ; Figure 5 is a perspective view of the handpiece fork illustrating the bearing assembly in position; Figure 6 is a top view of the bearing assembly illustrated in Figure 1 ; Figure 7 is a side sectional view of a shearing handpiece provided with a bearing assembly according to a second embodiment of the invention ; Figure 8 is an end sectional view of the handpiece taken along the lines 8-8 of Figure 7 ; Figure 9 is a side sectional view of another . bearing assembly of the present invention ; Figure 10 is an end sectional view taken at line 9-9 of Figure 9 ; and Figure 11 is a top sectional view taken at line 10-10 of Figure 9.

DEATILED DESCRIPTION OF PERFERRED EMBODIMENTS OF THE INVENTION

Figure 1 illustrates a shearing handpiece 10 provided with a centrepost bearing assembly 40 and a crankroller being assembly 60 of the present invention. The shearing handpiece 10 has a housing 16 that accommodates a pivoting fork body 13. Left hand and right hand fork yokes 33, each holding a cutter 14, are fitted at the end of fork body 13. Comb 15 is attached to the underside of housing 16 and has sharp teeth that lie adjacent the sharp cutters. The pivoting motion of the fork body causes the cutters to reciprocally move closely over the comb in an arcuate path thereby cutting the animal's wool.

A centrepost 30 is screwed into the housing from the underside 17 of the housing. The height of the centrepost, and therefore the fork body 13, in the housing can be adjusted using a screwdriver and is fixed at a desired height by a locknut 34 at its base. To reduce vibration and wear in the handpiece it is important to adjust the height of the fork body level relative to the crankhead assembly 12. With known handpieces the centrepost is only adjusted once throughout its life, which can lead to problems with vibration and poor cut as wearing of the cutters, comb, fork body, crankroller and centrepost increases. However because the present centrepost bearing assembly eliminates centrepost wear and thereby reduces the wear at the crankhead assembly, the . centrepost can be adjusted at any time through its life or the life of the handpiece, which is typically twelve months.

As illustrated in Figure 1 a tension nut 35 at the upper forefront of the housing 16 allows the operator to apply tension to the cutter when the cutter and comb begin to wear. Turning the tension nut 35 moves tension pin 36 axially. The end of the pin 36 is held in a fork body seat 37 on the upper, front side of the fork body.

Tightening the tension nut moves the front of the fork

body downwardly thereby moving the cutters closer to the comb to maintain a good cut.

Figure 2 is an end sectional view of Figure 1 and illustrates the bearing assembly in more detail. In this embodiment, bearing assembly 40 is designed to be supported on centrepost 30 so as to provide a low friction point of swivel for the fork body 13. The bearing assembly 40 comprises a first, upper contact surface 41 for supporting the fork body 13, a second, lower contact surface 42 adapted to be mounted on the center post 30, and bearing means 43 disposed between the upper and lower surfaces. As seen in the transparent view of figure 4 and in figure 6, the bearing means is a circular array of bearing elements, and specifically ball bearings 44. A small gap 58 between the ball bearings prevents binding, or wearing, of adjacent ball bearings. The lower contact surface 42 is the underside of an annular inner race 45, on which the ball bearings 44 are carried. Lower contact surface 42 is recessed to receive the centrepost projecting from the underside of the handpiece 10. Inner race 45 has a central upwardly projecting boss 50. An outer race 46 encases the ball bearings from an upper, outer side and defines the upper contact surface 41, which seats the fork body. Outer race 46 has an apertured central projection 51 ; which receives boss 50 therethrough . and aligns the inner and outer races of the bearing assembly. Central boss 50 and central projection 51 are disposed within a fork aperture 32 in the fork body 13.

A circlip 52 on boss 50 retains the inner and outer races together. The bearing assembly is lubricated with grease 47 at the ball bearings and between the inner and outer races. As illustrated in Figure 2, when assembled, a screw cap 53 is screwed into the fork body aperture 32 to provide easy access to the bearing for regreasing and removal. It is envisaged that with regular usage the centrepost bearing assembly will require regreasing about

2 to 3 times a year.

Hence, when assembled with the handpiece, the present bearing assembly sits on centrepost 30 and projects upward through fork aperture 32 with the fork body 13 seated on upper contact surface 41 of the bearing assembly. Fork body 13 is thereby able to pivot freely at the centrepost without directly contacting the centrepost and causing it to wear. Furthermore, the frictional resistance is reduced which allows the shearing handpiece a greater torque under load and reduces the generation of heat. The centrepost bearing assembly 40 enables the fork body to pivot smoothly and evenly at an adjustable centrepost height. This, in turn, produces a good cut through the animals fleece.

Figure 5 illustrates the fork body 13 with yokes 33 and the centrepost bearing assembly 40 in position. Screw cap 53 is removed from above the fork body with a screwdriver for regreasing the bearing elements. The upper contact surface 41 of the outer race 46 is contoured to properly seat the underside of the fork body at the fork aperture 32. The apertured central projection 51 of the outer race 46 fits inside the fork aperture 32 as illustrated in figures 1 and 2. A shoulder 55 adjacent projection 51 on the upper contact surface curves slightly downwardly to accommodate the curved underside of the fork body.

The recess of the lower contact surface 42 is accurately machined to accommodate the partly spherical shaped top of the centrepost 30.

The present centrepost bearing assembly removes the need for a fork stop commonly located at the top of shearing handpieces and illustrated in Figure B as 18. When the tension on the fork body is removed by releasing the tension nut 35, fork stop 18 prevents the fork body from

dislodging from its position on the centrepost. The present centrepost bearing assembly when positioned between the centrepost and fork body, raises the fork body in the housing closer to the top of the housing such that dislodgment is not possible and the need for a fork stop is eliminated.

The reduction of wear of the centrepost contributes to the reduction of heat and vibrations in the handpiece. The reduced friction between components at the pivot point increases the torque under load and provides for a good clean cut through the wool. It also reduces the need to oil the pivot point of the fork body every half-hour.

In a second embodiment shown in Figures 7 and 8, the fork body 13 has a stepped annular recess 80 has a closed end 81 and enlarged portion 84 on its underside. The recess 80 supports a bearing assembly 90 that includes an annular thrust bearing 91 as well as needle roller bearing 92.

The thrust bearing sits on the closed end 81 of the stepped recess 80 and accommodates a projecting spigot 85 of a center post cup 86. The remainder of the body of the center post cup 86 is a press fit within the needle roller bearing 92 that is located on the exterior of the center post cup 86 by an outer annular race 93. The needle roller bearing 92 fits closely to the interior of the enlarged portion 84 of the stepped recess 80. A retainer 95 with an annular lip 96 that extends over the forward edge of the center post cup 86 is screwed to the fork body 13 to hold the assembly together. The center post cup 86 has a spherical recess 87 that closely accommodates the spherical head of the center post 30. The combination of the thrust bearing 91 and needle roller bearing 92 provides positive location in two planes and ensures that the center post cup 86 is mounted on two bearings against the fork body 13.

It is also understood that other bearing combinations are envisaged such as replacing the needle roller bearing with two abutting deep groove single ball bearings to take the lateral loads. The use of the thrust bearing can then be optional.

Figures 9 to 11 illustrate a crankroller bearing assembly 60 of the present invention. The crankroller bearing assembly 60 reduces the friction and wear at the crankhead assembly 12, where rotary motion is converted into reciprocating linear motion. Furthermore, crankroller bearing assembly 60 assists to increase torque under load and reduces the necessity for frequent oiling of the crankroller.

Crankroller bearing assembly 60 comprises a substantially cylindrical crankhead 61 having a stem 63 offset from a longitudinal axis 64 of crankhead 61, a crankroller 62 having a bore 65 therethrough to receive stem 63, and bearing means 66 disposed between the stem 63 and crankroller 62. The crankhead 61 is mounted along its longitudinal axis 64 on a main spindle 73 in a handpiece.

The main spindle 73 and crankhead 61 could alternatively be fabricated as one component. The bearing means 66 is typically an array of needle bearing elements disposed around stem 63 and encased by crankroller 62, as . illustrated in Figure 10. To prevent escape of needle bearings 66 a crankhead shoulder 67 is provided at the base of stem 63 where it meets crankhead 61 and is adapted to abut one end of the needle bearings 66. The other end of needle bearings 66 abuts a crankroller shoulder 68 extending inwardly of bore 65 at one end of crankroller 62. With needle bearings securely caged at either end by crankhead shoulder 67 and crankroller collar 68, crankroller 62 is able to rotate freely around stem 63.

Crankroller 62 has a part spherical surface 69 that allows it to swivel freely in a corresponding part spherical

aperture 70 of fork body 13. Crankhead shoulder 67 and crankroller collar 68 are shaped with slightly bulbous portions 71 that make contact with the ends of needle bearings 66. Shoulder 67 and collar 68 maintain correct alignment of the needle rollers reducing the incidence of needle roller wearing or binding.

The present invention provides the benefit of a significant reduction in wear of components in a shearing handpiece. The life of the handpiece is extended and the overall quality of the cut is much higher. In the shearing trade where the nature of the equipment dictates high maintenance needs with frequent oiling, greasing and changing of parts, the present invention significantly reduces maintenance time allowing instead a greater shearing output and increased shearer efficiency.

It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS: 1. A bearing assembly for a shearing handpiece, the handpiece having a pivoting fork body supported on a center post, the bearing assembly being adapted to be positioned between the fork body and the center post and comprising : a first contact surface for supporting the fork body, a second contact surface for mounting on a center post, a bearing means disposed between the first and second surfaces.

2-The bearing assembly according to claim 1, wherein the first and second contact surfaces are defined by a first and second annular race respectively, with bearing elements located between the first and second races- 3. The bearing assembly according to claim 2, wherein the bearing elements are roller bearings, tapered roller bearings, or needle roller bearings.

4. The bearing assembly according to claim 2, wherein the second contact surface has a recess suitable . for receiving a center post of the handpiece such that the bearing assemblies are mounted on the center post.

5. The bearing assembly according to claim 4, wherein the first race has a central hollow projection which is inserted into, and supports, the fork body.

6. The bearing assembly according to either claim 4 or claim 5, wherein the second race has a smaller central projection that fits into the central hollow projection of the first race, the bearing elements being located

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radially of the central projections.

7. The bearing assembly according to claim 6, wherein the first contact surface is contoured to conformably seat the fork body.

8. The bearing assembly according to claim 1 wherein the first contact surface is the outer race of a needle roller bearing and the second contact surface is a cup with a projecting spigot that engages a thrust bearing arranged to he positioned against the fork body, the cup being adapted to be mounted on the center post.

9. A bearing assembly substantially as described herein with reference to and as illustrated in the accompanying drawings.

10. A bearing assembly for a shearing handpiece, the handpiece having a rotating spindle adapted to drive a fork body, wherein the bearing assembly is disposed between the spindle and the fork body and comprises : a substantially cylindrical crank head axially mounted to the spindle and having an eccentrically projecting stem, a annular crank roller adapted to be located on the fork body and having a central ball for receiving the - stem, and a bearing means provided between the stem and the crank roller.

11. The bearing assembly according to claim 10, wherein the bearing means is located around the circumference of the stem and is typically an array of needle rollers.

12. The bearing assembly according to claim 11, wherein a annular shoulder is provided on the crank head

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and an annular collar is provided at the end of the ball opposite the crank head.

1. 3. The bearing assembly according to claim 12, wherein the annular shoulder and annular collar axially encase the bearing means.

14. The bearing assembly according to claim 13 wherein bulbous portions on the shoulder and collar extend towards the bearing means to retain alignment of the bearing means.

15. A bearing assembly for a shearing handpiece ; the handpiece having a pivoting fork carrying shearing cutters, the fork being supported on a center post and driven by a crank head mounted on a rotating spindle, the bearing assembly being provided between one of the center posts or crank head and the fork body, the bearing assembly comprising a bearing means- 16. A shearing handpiece comprising : A housing adapted at one end to be attached to a rotating drive spindle, the other end of the housing supporting a cutting head, the housing supporting a pivoting fork body ~about a center post, the pivotal movement of the fork body driving the cutting head, means to impart pivotal movement to the fork body, and a bearing assembly according to anyone of claims 1 to 9 positioned between the fork body and the center post.

17. The shearing handpiece according to claim 16 wherein the means to impart pivotal movement to the fork

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body comprises a crank head axially mounted on the drive spindle, the crank head having an eccentrically projecting stem that engages in annular crank roller located on the fork body via bearing means between the stem and the crank roller.

18. A shearing handpiece comprising a housing adapted at one end to be attached to a rotating drive spindle, the other end of the housing supporting a cutting head, the housing supporting a pivoting fork body about a center post, the pivotal movement of the fork body driving the cutting head, a crank head axially mounted on the drive spindle, the crank head having an eccentrically projecting stem that engages an annular crank roller located on the fork body via bearing means between the stem and crank roller.

19. A shearing handpiece substantially as described herein with reference to and as illustrated in the accompanying drawings.