IMPROVED WOOL SHEARS

Abstract: A wool shearing handpiece enclosed within a casing (6) through which extends a drive fork (10) driven at a rear end for oscillation about an intermediate pivot (11, 36) to recipro­ cate at an open forward end (6B) of the casing a cutter (23) across a comb (17), and wherein the closing force between the cutter and the comb is derived from a frame (24) having a pair of depending arms (25, 26) which at least partly span and bear down upon a forward end portion (10A) of the fork with an adjustable force.

Description: This invention relates to handpieces used in the wool shearing industry. According to contemporary forms of shearing handpieces crank drive to a cutter reciprocating over a fixed comb is derived through a fork supported upon a medial pivot and to a rear end of which drive is applied. The cutter is secured by so-called "chicken's feet" to the forward end of the fork and closing pressure between the cutter and the comb is determined by an adjustable thrust pin (traditionally called a "tension pin") bearing upon the fork's forward end. Such an arrangement is disclosed in Australian Patent Specifications Nos. 7900/07 and 12099/28. However, it is known that uneven wear between the cutter and the comb arises due to a twisting force imposed upon the fork as the cutter reciprocates towards at least one of its extreme lateral positions with respect to the comb. Inefficient shearing also results. Attempts to overcome this problem have been made, one of which is disclosed in Australian Patent Specification No. 551 623, where an abutment is provided to engage an intermediate portion of the thrust pin to impart bending movement thereto to restrain rocking motion of the crank drive. A further proposal is disclosed in US-A-4 291 462 where the conventional thrust pin is replaced by a bent tensioning arm which is pivotally mounted with one end bearing upon the fork and its other end extending on an axis colinear with the pivotal axis of the fork. These proposals have only met with limited success mainly due to the rigorous task to which these appliances are applied. It is the object of the invention to provide an effective solution to the problem which is simple and inexpensive. As is known from US-A-4291462 the present invention provides a shearing handpiece comprising an elongate casing; a comb which is supported upon a forward end of the casing; a drive fork having a forward end portion and a rearward end portion, the said drive fork extending throughout the casing and being pivotally mounted about a pivotal axis supported by the casing; a cutter held against the comb by the forward end portion of the drive fork said fork being driven at its rearward end portion to reciprocally move the cutter attached to its forward end portion along an arcuate path; a tensioning, adjustable member which bears upon the fork at a position between the pivotal axis of the fork and the cutter; and an adjusting cap which is threadably engaged with an upper extension of the casing and adapted for adjustably applying a downward force upon the adjustable member so as to vary the closing force between the cutter and the comb. In one aspect the invention is characterized in that the forward end portion of the fork is separate from and is articulated with respect to the rearward end portion thereof by an intermediate pivot and the adjustable member is a frame of inverted Y-shape having an upwardly extending support leg and a pair of downwardly diverging arms, said support leg extending into the upper extension of the casing and each arm bearing downwardly upon either side of a centreline of the forward end portion of the fork to impose the closing force between the cutter and the comb about the intermediate pivot. In another aspect the invention is characterized in that the adjustable member is a frame of inverted Y-shape having an upwardly extending support leg and a pair of downwardly diverging arms, said support leg extending into the upper extension of the casing and each arm bearing downwardly upon either side of a centreline of the forward end portion of the fork of unitary construction to impose the closing force between the cutter and the comb about the pivotal bearing. Other preferred features of the invention are defined in the dependent claims. The invention will be better understood from a reading of the following description in conjunction with the accompanying drawings, in which: Fig. 1 shows in longitudinal cross-section the front section of a shearing handpiece constructed in accordance with one embodiment of the invention; Fig. 2 is a perspective of the fork incorporated in the handpiece of Fig. 1; Fig. 3 is a perspective of another form of the fork; and Fig. 4 is a fragmentary view of the fork showing a modification. The embodiment shown in Figs. 1 and 2 consists of a handpiece 4, of which only the forward end section 5 is depicted, having an outer metal casing 6 with a rearward end 6A and a forward end 6B. The driving crank 7 and rotatable ball 8 from the rear driving section (not shown) of the handpiece 4 engages within a driven socket 9 at the rear end of a drive fork 10. A fulcrum pin 11 passing through a boss 12 in the underside of the casing 6 serves as an intermediate journal for the drive fork 10. The pin 11 penetrates a boss 13 integral with the fork 10 and is secured by a nut 14 at the distal side of the fork 10. Flat washers 15 and 16 are provided to reduce friction between the boss 13 and the nut 14 and casing 6 as the fork oscillates about the fulcrum pin 11 in response to force applied by the drive crank 7. A comb 17 is fixed to the forward end 6B of the casing 6 at its underside with the forward end 6B open to allow the fork 10 to protrude therethrough. The forward protruding end 10A of the fork 10 terminates in a spigot 18 upon which is rotatably mounted a carrier 19 provided with two lateral sockets 20 and 21 which rotatably mount chicken's feet 22 which in turn hold the cutter 23 against the comb 17. Therefore, as the fork 10 reciprocates under the action of the crank pin 7 the cutter 23 is caused to oscillate across the comb 17. It is necessary to provide the operator with a facility for adjustment of the closing force between the cutter 23 and the comb 17. In this embodiment the facility is provided by a frame 24, of inverted Y-shape with the end of the arms 25 and 26 formed as cylindrical enlargements 27 journalled upon posts 28 laterally and integrally formed upon the forward end portion 10A of the fork 10. A ball 29 provided at the opposite end of the frame 24 is accommodated within a socket 30 forced against the ball 29 by thimble, or cap, 31 threadably engaged with an upper extension 6C of the casing 6. Furthermore, the forward end 10A of the fork 10 is articulated with respect to the rearward end by a hinge pin 32 penetrating a clevis 33 on the fork forward end 10A. From an appreciation of the above-described construction it will be apparent that should the thimble 31 be screwed down onto the extension 6C of the casing 6 force will be applied through the frame 24 to rotate the forward end 10A of the fork 10 about the hinge pin 32 to urge the cutter 23 onto the comb 17, to increase the closing force therebetween. As the fork 10 reciprocates about its fulcrum pin 11 the frame 24 will move to and fro through universal movement provided between the ball 29 and its socket 30 while the frame 24 will restrain torque forces acting upon the fork 10. According to the alternative embodiment shown in Fig. 3, the fork 10 is of unitary construction and its reciprocation is facilitated by the insertion therein of a hardened steel socket 34 the cavity 35 of which accommodates a fulcrum ball 36 fixed, or integrally formed, upon a support post 37 upstanding from the bottom part of the casing 6. Therefore, with increasing closing tension applied to the cutter, the fork 10 tilts forwardly about the ball 36. As shown in both this and the former embodiment the fork 10 may be composed of inverted channel section as shown by the outline 38. A strut 39 may interconnect the arms 25 and 26 of the frame 24 as shown in Fig. 3, for reinforcement. It is conceivable, also, that a different form of engagement between the frame 24 and the fork 10 may be employed and this is illustrated in Fig. 4 which represents a modification of the embodiment of Fig. 2. In this instance the end of each of the arms 25 and 26 may be formed with a hardened rounded end, or ball, 40 engaged in a respective one of transverse guide slots 41 formed in the upper part of the forward end 10A of the fork 10 with the frame 24 restrained from lateral movement. Hence, as the forward end 10A of the fork 10 reciprocates the balls, or ends, 40 on the arms 25 and 26 will slide along their respective slots 41. The bottom of these slots preferably are towards their outer ends upwardly inclined out of the plane of the fork 10 to maintain uniform closing force between the cutter 23 and its comb 17 during the whole of its reciprocation. The same modification may, of course, be applied to the embodiment of Fig. 3. Whereas several embodiments have been disclosed in the foregoing passages it should be understood that other forms, modifications and refinements are possible within the scope of the appended claims.

Claims: A shearing handpiece (4) comprising an elongate casing (6); a comb (17) which is supported upon a forward end (6B) of the casing; a drive fork (10) having a forward end portion (10A) and a rearward end portion, the said drive fork extending throughout the casing and being pivotally mounted about a pivotal axis (11) supported by the casing; a cutter (23) held against the comb (17) by the forward end portion (10 A) of the drive fork (10), said fork being driven at its rearward end portion to reciprocally move the cutter (23) attached to its forward end portion along an arcuate path; a tensioning, adjustable member (24) which bears upon the fork at a position between the pivotal axis (11) of the fork and the cutter (23); and an adjusting cap (31), which is threadably engaged with an upper extension (6c) of the casing (6) and adapted for adjustably applying a downward force upon the adjustable member (24) so as to vary the closing force between the cutter (23) and the comb (17), characterised in that : the forward end portion (10A) of the fork (10) is separate from and is articulated with respect to the rearward end portion thereof by an intermediate pivot (32); and the adjustable member (24) is a frame of inverted Y-shape having an upwardly extending support leg and a pair of downwardly diverging arms (25, 26), said support leg extending into the upper extension (6c) of the casing and each arm bearing downwardly upon either side of a centreline of the forward end portion of the fork to impose the closing force between the cutter (23) and the comb (17) about the intermediate pivot (32). A shearing handpiece (4) comprising an elongate casing (6); a comb (17) which is supported upon a forward end (6B) of the casing; a drive fork (10) of unitary construction having a forward end portion (10A) and a rearward end portion, the said drive fork extending throughout the casing and being pivotally mounted about a pivotal bearing (34, 36) supported by the casing; a cutter (23) held against the comb (17) by the forward end portion (10A) of the drive fork (10); said fork being driven at its rearward end portion to reciprocally move the cutter (23) attached to its forward end portion along an arcuate path; a tensioning, adjustable member (24) which bears upon the fork at a position between the pivotal bearing (34, 36) and the cutter (23); and an adjusting cap (31), which is threadably engaged with an upper extension (6c) of the casing (6) and adapted for adjustably applying a downward force upon the adjustable member (24) so as to vary the closing force between the cutter (23) and the comb (17), characterised in that the adjustable member (24) is a frame of inverted Y-shape having an upwardly extending support leg and a pair of downwardly diverging arms (25, 26), said support leg extending into the upper extension (6c) of the casing and each arm bearing downwardly upon either side of a centreline of the forward end portion of said fork of unitary construction to impose the closing force between the cutter (23) and the comb (17) about the pivotal bearing (34, 36). A shearing handpiece as claimed in claim 2 wherein said frame further comprises a transverse strut (39) interconnecting the arms (25, 26). A shearing handpiece as claimed in claim 1, wherein said articulation is accomplished by a hinge pin (32) penetrating a clevis (33). A shearing handpiece as claimed in claim 1 or 4 wherein each arm, (25, 26) terminates in a cylindrical enlargement (27), each enlargement engaging a post (28) laterally and integrally formed on the forward end portion of the fork (10). A shearing handpiece as claimed in any one of claims 1 to 4, wherein the arms (25, 26) of said frame are pivotally fixed to opposite sides of the forward end portion of the fork (10). A shearing handpiece as claimed in any one of claims 1 to 4, wherein the arms (25, 26) of said frame terminate in ball ends (40), the ball ends being engaged within respective guide slots (41) extending transversely across the forward end portion of the fork (10), to permit relative movement between said arms and said fork. A shearing handpiece as claimed in any one of claims 1 to 7, wherein the rearward end portion of the fork is formed as a generally U-shaped channel.

Inventors: MORAN, VICTOR ANTHONY
Applicants: SUNBEAM CORPORATION LIMITED
Application year: 1986
Main classification: B26B19
IPC codes: B26B19