AU652373B2 - Oscillating cutter drive - Google Patents

Description

P/00/0011 Regulation 3.2

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

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Qata 2 RalayPrae Cabrel Vitra 314,* Ausraia AtoreyCoe A Tile OSILTN CTERV Neaes of Asscae rvsoa pplicant:ns Nos:A A POO 135PO 4ile 2 ul 19 Th follwin sttmn safl ecipino hsivnin ncuigtebs ehdo pefrmn itkontom/s i:C 6 Ir I I "'1 r 2 TITLE: OSCILLATING CUTTER DRIVE r, 10 I C C

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C C -c c Field of the Invention: This invention relates to an improved drive mechanism for an oscillating severance device, which may for example be used for shearing sheep.

Background of the Invention: Existing oscillating cutters are typically driven by rotary motors which may be electrically, hydraulically or pneumatically powered using an eccentric crank either directly or indirectly coupled to the power source.

Pneumatic motors have not found favour due to unstable power against load, economy of use and to date their size, balance and interference to wool flow.

Direct electric drives have recently been introduced but still lack adequate power with problems associated with size and weight.

Direct rotary hydraulic drives have not yet been introduced due to size, weight and balance problems.

Indirect electric drives via a down tube or flexible shaft are the current preferred technology resulting in reasonable hand piece mass and envelope with adequate power.

All the above drives use eccentric cranks to impart an essentialy harmonic oscillation to a multi toothed cutter traversing a multi toothed comb typically having one cutter tooth traverse three comb valleys.

Research into the cause of drag forces between the cutter and the sheep have been found to comprise three 4o C it Ci r Li Si; r

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tbspe.056/awc 91 7 11 3 'C C significant elements: Undercomb friction being that created by contact of the comb with the sheep's skin while being traversed.

Penetration drag the force to penetrate the teeth of the comb into the fleece and push the fibres down the valleys of the comb.

Severance drag the force created as bunches of fibres are progressively pinched as they are being shorn while the cutter traverses forward with those fibres still attached to the animal's skin.

The latter forces have been shown to be dependent upon both cutter speed severence speed) and the number of teeth used to sever the fibres (typically four teeth in current shearing equipment).

As currently preferred shearing equipment uses eccentric or crank mechanisms to oscillate the cutter there is a gross difference in severance speed between the outer and central valleys of the comb swept by each cutter tooth. It can be shown experimentally that consequently high drag forces occur in these regions.

It has been suggested that in order to lower these drag forces the speed of oscillation of the cutter is increased or the number of cutting teeth is reduced together with an increase in oscillation speed. The result of doing so is to increase power requirements of the cutter drive and to generate additional heat and wear.

Summary of Invention and Object: 4

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*'4O tbspe.056/awc 91 7 11 4 The object of the present invention is to provide a drive capable of more uniform severance velocity by eliminating the eccentric drive with its associated rotary power source.

The invention provides a drive for an oscillating cutter, comprising a body, pivot means carried by said body and defining a pivotal axis, an arm mounted on said pivot means for oscillatory movement about said pivotal axis, said arm being adapted to carry cutting means which cooperates with a cutting member associated with is aid body and positioned forwardly of said body, said body having a width which is less than the width of said cutting member and drive means for oscillating said arm z about said pivotal axis, said drive means including a pair of driving means housed within said body, each C C driving means being positioned rearwardly of said pivot rC C so as to pivot said arm through one part of its •oscillatory movement, and means driving each of said rLr •driving means to cause oscillatory movement of said arm.

The drive described is smaller in mass and total envelope than existing commercial drives. It can output more power and oscillate at higher frequencies with a substantially uniform severance speed.

In a preferred form of the invention, each driving means is an hydraulically driven ram, said drive including controlled valve means for selectively directing drive fluid to one or the other of said rams to cause oscillation of said arm.

V Each ram is preferably connected to a fluid line 5571wool.spe 93 06 24 4 and said valve means causes fluid under pressure to be connected to one or the other of said ram means, the other fluid line serving as a return line for fluid *4t S* *5 S S

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Brief Description of Drawings: In order that the invention may be more readily understood, a presently preferred embodiment of the invention will now be described with reference to the accompanying drawings in which: Figure 1 is a sectional side elevation of a cutter incorporating the drive of the present invention attached to a manipulating mechanism forming part of an automated shearing device; Figure 2 is a sectional plan view of the cutter and drive; Figure 2A is an enlarged fragmentary sectional plan view of one ram of the drive; Figure 3 is a plan view of the lower body showing the positioning the valve control mechanism, and Figure 4 are side elevations of the cutter embodying the invention and a standard cutter illustrating the comparative sizes thereof.

Description of Preferred Embodiment: Referring to the drawings the drive mechanism consists of a lower body 1 and an upper body 2 secured together by screws 3. The upper body supports a pivotal shaft 4 having an axis normal to the base plane of the lower body 1 to which a severance comb 5 is attached with mounting screws 6. It will be noted from Figure 2 that the width of the body 1, 2 is significantly narrower than the width of the comb 5. The lower body 1 supports an inflatable bag 7, the construction and t tr t Il 9* a I a 9l a

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r ktf o tbspe.056/awc 93 8 16 L h 5 function of which are further described in copending Patent Application AU-B-12154/88 (591834).

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0005 A rocker arm 8 is mounted to the pivotal shaft 4 and oscillates about this axis sufficiently to traverse a cutter 9 across the full width of the comb The cutter 9 is held in contact with, and driven by, chicken's feet 10 with a self balancing pivotal arrangement to distribute the closing force between the cutter 9 and the comb 5 such that the force applied to each tooth of the cutter 9 is approximately equal. Such a chicken's foot arrangement is described in Australian Patent No. AU-B 13160/&3 (551623).

The closing force is achieved by tightening the tension adjustment screw 11 against a tension post 12, carrying friction reducing balls 12a,12b bearing on a tension washer 13 within the pivotal shaft 4.

As shown most clearly in Figures 2 and 2A, oscillation of the rocker arm 8 is achieved by alternately feeding high pressure oil to opposing chambers 14 and 15 for rams 17 and 18, while venting the oil in the opposite chamber to hydraulic power supply return lines L (Fig. 1) through passages P. This is done by a suitable control servo valve 16, mounted directly adjacent to the ram chambers 14 and 15, such as a Moog J030-131A, so that a reasonable percentage of the oil fed into the ram chamber 14 or 15 is subsequently exhausted through the valve 16 to the return line L. The rams 17 and 18 are sealed by step seals S and O-rings 0 (Fig. 2A) located in the walls of the chambers 14 and by bushes B.

As chamber 14 is supplied with high pressure oil it

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C t cCCr, L e c st r c cc rte t r CCio~ E t c ieloc r t causes ram 17 and its associated vertical pin 19 to extend. The vertical pin 19 contacts a matching concave seating 21 in opposed drive arms 22 extending from the hub of the rocker arm 8. The seatings 21 are vertically extended such that limited vertical adjustment of the rocker arm 8 may take place with respect to the rams 17 and 18 and their respective vertical pins 19 and As the ram 17 extends it causes the rocker arm 8 to oscillate clockwise until a magnet 25 mounted in a 10 carrier 26 affixed to the rocker arm 8 is in sufficient proximity to one of two spaced Hall effect sensor 23,24, mounted in a recess in the lower body 1 (Figs. 1 and 3), to switch its electrical output. This signal is used to reverse the state of valve 16 so that high pressure oil is now directed to ram chamber 15 to reverse the oscillation of the cutter 9.

The speed of reciprocation of the cutter 9 is directly controlled by the valve 16 which may be controlled in a variety of ways known in the art, including microprocessor control.

It will be appreciated from the above description that the cutter drive embodying the invention reduces the mass and total size of cutter so that the cutter may be oscillated at higher frequencies at a substantially uniform severance speed to provide a significantly higher power output than a standard cutter of equivalent size. As shown in Figure 4 of the drawings, the new cutter is significantly smaller than the standard electric hand piece, and may therefore be more easily tbspe.056/awc 91 7 11 8manipulated either manually or by automated machinery.

Also, the width of the body 1, 2 being narrower than the width of the comb 5 improves the flow of severed wool past the body 1, 2 thereby reducing "drag" forces on the cutter.

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Also, the width of the body 1, 2 being narrower than the width of the comb 5 improves the flow of severed wool past the body 1, 2 thereby reducing "drag" forces on the cutter.

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Claims (10)

1. A drive for an oscillating cutter, comprising a body, pivot means carried by said body and defining a pivotal axis, an arm mounted on said pivot means for oscillatory movement about said pivotal axis, said arm being adapted to carry cutting means which cooperates with a cutting member associated with said body and positioned forwardly of said body, said body having a width which is less than the width of said cut-ing member and drive means for oscillating said arm about said pivotal axis, said drive means including a pair of Sdriving means housed within said body, each driving means being positioned rearwardly of said pivot so as to pivot said arm through one part of its oscillatory 15 movement, and means driving each of said driving means rt re to cause oscillatory movement of said arm.

2. The drive of claim 1, wherein each driving means is an hydraulically driven ram, said drive including controlled valve means for selectively directing drive fluid to one or the other of said rams to cause oscillation of said arm.

3. The drive of claim 2, wherein each ram is connected to a fluid line and said valve means causes fluid under pressure to be connected to one or the other of said ramr meae the other fluid line serving as a return line for fluid displaced from the other of said rams. 5571wool.spe 93 06 24 10

4. The drive of claim 3, wherein said controlled valve means is positioned in close proximity to said driving means to maximize displacement of fluid from said rams to said return line. t *r CcrC C CCL C C The drive of any one of claims 2, 3 or 4, wherein said valve is controlled by position sensing means carried by said arm and a fixed portion of said cutter.

6. The drive of claim 5, wherein said position sensor comprises a magnet carried by said arm and Hall-effect sensor means mounted on said arm.

7. The drive of claim 6, wherein said magnet and said sensors are arranged substantially as hereinbefore described with reference to Figures 1, 2 and 3 of the accompanying drawings.

8. The drive of any preceding claim, wherein said arm includes a hub carrying said pivot means, said hub having drive arms extending oppositely from said hub and including concave seatings receiving correspondingly convex end portions of said rams.

9. The drive of any one of claims 2, 3 or 4, wherein said drive arms and rams are arranged substantially as hereirbefore described with reference to Figures 2 and 2A of the accompany drawings. tbspe.056/awc 93 816 I 11 A drive for a cutter substantially as hereinbefore described with reference to Figures 1 to 3 of the accompanying drawings.

11. A cutter substantially as described with reference to Figures 1 to 3 of the accompanying drawings. DATED this 9th day of July 1993 CARTER SMITH BEADLE Fellows Institute of Patent Attorneys of Australia Patent Attorneys for the Applicant: e 1 10 WOOL RESEARCH DEVELOPMENT CORPORATION 1 o 't ~tr e cc i93 5571 wool.spe 93 06 24 S

12- ABSTRACT A drive mechanism for a cutter comprising a rocker arm mounted to a pivotal shaft to oscillate about the axis of the shaft to traverse a cutter (9) across a comb said rocker arm being oscillated by hydraulic rams (17) and (18) to which high pressure oil is alternately fed under the control of a servo valve (16) controlled by position sensor means in the form of a magnet (21) mounted on the rocker arm and two spaced Hall-effect sensors (23,24) mounted on a fixed portion of the cutter so as to detect the magnetic field of the magnet (21) as the arm oscillate to control the operation of the servo valve (16) to thereby Senable oscillation of the arm and higher frequencies at a substantially uniform severence speed to provide significantly high power output than an equivalent standard cutter. i .t t l i tbspe.056/awc 91 7 11