US2621680A

US2621680A - Picking mechanism for underpick looms

Info

Publication number: US2621680A
Application number: US221974A
Authority: US
Inventors: Vincent John Joseph; Davies Frank
Original assignee: British Cotton Industry Research Association
Current assignee: British Cotton Industry Research Association
Priority date: 1950-04-22
Filing date: 1951-04-20
Publication date: 1952-12-16
Anticipated expiration: 1969-12-16

Description

Dec. 16, 1952 J. J. VINCENT ETAL PICKING MECHANISM FOR UNDERPICK LOOMS 5 Sheets-Sheet 1 Filed April 20, 1951 mws/vroks Dec. 16, 1952 J. J. VINCENT ETAL PICKING MECHANISM FOR UNDERPICK LOOMS 5 Sheets-Sheet 2 Filed April 20, 1951 Dec. 16, 1952 J. J. VINCENT ET AL 2,621,680

PICKING MECHANISM FOR UNDERPICK LOOMS Filed April 20, 1951 5 Sheets-Sheet 3 and.

Dec. 16, 1952 J. J.'VlNCENT ETAL PICKING MECHANISM FOR UNDERPIC! LOOMS 5 Sheets-Sheet 4 Filed April 20, 1951 Dec. 16, 1952 I J. J. VINCENT ETAL 2,621,680

PICKING MECHANISM FOR UNDERPICK LOOMS Filed April 20, 1951 5 Sheets-Sheet 5 PIC-25A Patented Dec. 16, 1952 PICKING MECHANISM FOR UNDEBPICK LOOMS John Joseph Vincent and Frank Davies, Didsbury, Manchester, England, assignors to The British Cotton Industry Research Association, Didsbury, Manchester, England, a British association Application April 20, 1951, Serial No. 221,974 In Great Britain April 22, 1950 8 Claims.

This invention relates to an improved picking mechanism for underpick looms and is particularly concerned with the design of a picking mechanism which can be mounted in such a way as to reduce the number of machine-parts employed, the amount of metal used, the space ocgupied in the loom, and the mechanical wear and ear.

It has previously been proposed in such looms to utilize the bottom shaft of the loom as a combined swing rail and picking cam shaft, that is to say, the bottom shaft acts as the axis about which the sley swords oscillate and is also arranged to carry the picking cams. In one such previously known arrangement, each picking stick and its operating mechanism has been carried by a bracket j ournalled on the end of the rotating bottom shaft; the axis of the shaft lies in the plane of movement of the picking stick, and the bracket has necessarily had only a single bearing support disposed behind the cam so that the cam is on an overhanging end of the shaft and the bracket itself overhangs its bearing support. In another known arrangement, although the bottom of the picking stick socket is bifurcated so that it part straddles the end of the shaft, the end of the shaft and the bracket still overhang the main bearing support.

The present invention is based on an appreciation of the fact that, whereas certain advantages exist in mechanisms of the known kind, still further advantages can be obtained by continuing to use the bottom shaft as a combined swing rail and picking cam shaft, but by offsetting the plane of movement of the picking stick from the axis of the shaft. These advantages are:

1) Each bracket can conveniently be provided with two bearings on the shaft and the picking mechanism mounted there-between with a resulting increase of rigidity. Also the shaft can have two bearing supports and a secondary result of such mounting is that there is a greater degree of freedom for placing the cam on the shaft since, with one bearing and one bearing support only, it is essential that the cam is mounted as close as possible thereto.

(2) The maximum side thrust component on the picking stick and its pivot can be reduced by offsetting the picking stick in a direction opposite to the direction of rotation of the cam, for during the application of the picking force the radius of the cam acting on the follower is increasing. If the centre of the follower is in the common vertical plane of the aXis of the bottom shaft and central plane of movement of the picker stick (as 2 is the case if the picking mechanismis not 011- set) the point of application of the picking force to the follower, initially the uppermost point of the follower, moves during acceleration out of this plane, as the follower moves from the base towards the nose of the cam thereby introducing an unwanted horizontal component in the force applied to the follower. Wherever the follower is sited in a common plane of the shaft and picker stick, such horizontal component is all to one side of the plane of the picker stick. By offsetting the plane of movement of the follower in a direction opposite to the direction of rotation "so that it no longer passes through the centre of the shaft and so that the radius vector joining the centre of the shaft and the centre of the cam follower is shifted, it can be arranged that when the picking force is first applied, the point of contact lies to one side of the plane of movement of the follower and during the remainder of the time that the cam is accelerating the follower the point of contact moves through the said plane of movement (at which instant there is no horizontal component) and pastit, for example to an equal distance and thereby the maximum value of the horizontal component applied to the follower and relative to the plane of movement is substantially reduced.

(3) There is no necessity for a forking of the base of the picking stick.

(4) The system can be readily adapted to ensure that the reed strikes the fell of the cloth at any desired angle. p

(5) The effect of offsetting and locating the pressure angle partly on one side and partly on the other side of the plane of movement of the follower is that the maximum angle of pressure relative to such plane is less than the total change of angle of pressure and therefore the maximum pressure angle and size of cam can be co-related consistent with known principles of good cam design, and so that both or either are or is smaller than would be possible without such offsetting.

According to the invention, an underpick loom having a combined swing rail and picking cam shaft, picking mechanism at each end of the shaft comprising a picking edge cam thereon, a bracket journalled on the'shaft adapted to carry a sword arm of the loom and a picking stick pivotally mounted in the bracket with the axis of its pivot at right angles to the axis of the shaft and a cam follower attached to the picking stick, is characterised in that the cam follower is ofi-set relativc to the shaft so that it is angularly displaced about the shaft axis in the opposite direction to the shaft and the axis of the roller is angularly displaced about the shaft axis in the opposite direction to the rotation of the cam to such amount that the initial point of contact between the cam and roller at the commencement of the picking operation lies to one side of the said plane of movement and at some time during the acceleration of the picker such point of contact crosses the said plane and thereby the maximum value of the horizontal component of force applied to the follower relative to the plane of movement is reduced.

The picking mechanism for a loom aforesaid may be further characterised in that the relative displacement of the point of contact to each side of the; plane of movement of the cam follower is so proportioned that the maximum horizontal component of force at each side is substantially equal; or ina loom wherein the cam is designed to. give, substantially constant acceleration, the arrangement wherein the relative displacement of the point of contact to each side of the plane of movement of the cam follower is equal so that the maximum horizontal component of force at each side is substantially equal.

.Preferab1y, .thebracket is journalled on the shaft n e'ach side of the cam and preferably also the; shaft isprovided with a bearing support on each side of. the. bracket. I II I I According toa further feature of the inventor, a pneumatic cushioning means is mounted on the bracket, adapted to arrest the picking stick after, the cam movement is completed, though applying no resistance while the picking is in progress. I

In the accompanying drawings: I

Fig. 1 is a part sectional side elevation, and

Fi'g. 2 is an end view of one example of picking mechanism made in accordance with the invention. I

Figs. 3 and 4 are similar views of another example of picking mechanism according to the invention. I I I V I Figs. 5A and 5B are diagrams showing the cam theory when the follower is not off-set.

Figs. 6A; 6B and 6C are diagrams. showing the cam theory with the follower off-set as in the construction shown in Figs. 1 to-4. v I I In the example of the invention shown in Figs. land 2 the combined swing rail and picking cam shaft In, one end only of which. is shown, is mounted in an inner bearing ll attached to a girder member l2 ofthe loom frame, and its extreme end is supported from the ground by. a further bearing. I3. The shaft is adapted to be rotated by gearing, not shown, at the usual halfspeed for a cam shaft. .Journalled on the. shaft is a U-shap'ed bracket [4 each arm of which carries. a bearing bushing l5 by which the bracket issuspended from the shaft. The arm nearest the bearing. l I is extended upwardly and laterally at Ma above the shaft and bearing II and is constructed of rigid angle members to form at [4b one side of a socket for the sley sword l6, theother side of such socket being. formed of plate; lllournalled atv I 8 on the shaft Ill on the inside of the bearing l l. The socket includes clamping bolts [9. By this construction the bearing [8 for part of the socket of the sword 4 arm substantially forms a third bearing for the bracket l4. On the shaft l0 and immediately inside the longer arm of the U-shaped bracket is a picking edge cam 28. The U-shaped bracket If is substantially of channel cross section and has its medial plane indicated by the line 21 offset about 2 inches from the axis of the shaft It. At the bottom of the bracket and substantially centrally between the arms are bearing lugs 22 at each side of the channel in which lugs is located a pivot pin 23 for the socket 2A of the picking stick 25. At its lower end and substantially at right angles to the picking stick socket is a short crank arm 26 carrying a follower bowl 21 having a 2 inch diameter spherical surface adapted to be engaged by the nose 20a of the cam 20. Between the shorter limb of the U-shaped bracket [4 and a lug 28 on the socket 24 for the picking stick is a tension return spring 29. At the upper end of the socket for the picking stick is a further lug 3i] for a connecting rod 3! of a piston 32 slidably mounted in a cylinder 33 carried on the lateral extension Ma of the bracket M, the wall of the cylinder having a longitudinal slot 33a terminating short of its closed end 33b'so that air may be trapped in the bottom of the cylinder by the piston to cushion the picking stick at the inner end of its stroke.

In a further example of the invention. as shown in Figs. 3 and i, all the mechanism is carried in orby a substantially closed box-like unitv 34' taking the place of the bracket Ill of theprevicusly described example,- which unit is mounted around that portion of the bottom shaft 35' which extends beyond the side frame 35 of the loom, the extreme end of the shaft being carried by an additional bearing support El overhung from the loom frame or separately secured to the ground. The box is journalled on extensions of bearing bushings 39 for the shaft, carried respectively by the parts 36, 3?, and is splitlongi'tudinally and the parts secured together by bolts. 41) to facilitate assembly and removal from its bearings without disturbing the shaft. bearings and the box 3:1 has a face to which a base flange ll on the sword arm socket 42 may be bolted. Ther is also a further face 34b on the box to which the cylinder 43 of the pneumatic cushioning device may be attached.

I In cross-section the box-like unit 34 is mainly circular about the axis of the shaft except that the lower forward portion is provided with a longitudinal bulge 34a carrying in its length the lugs se ior the lower end of the picking stick socket 45 off-set to the front of the shaft as in the first example. The direction of rotation of the shaft is clockwise, as shown in Fig. 4. In the upper end of the box 35 is a slot 34b in which the picking stick socket 45 may move longitudinally. The picking stick socket is connected to the piston 46 of the pneumatic cushioning device by a connecting rod M as in theexample first described.

At one end of the loom, the box 3Q as shown is adapted to house the driving gear 48 for the shaft, which gear is adapted to carry the cam 49. 'I'he box may be constructed to hold lubricants. I I I II In operation, the offsetting of the picking stick so that its plane of movement is at the side of the cam shaft, not only enables the bracket to be additionally journalled at the outer end of the shaft aswell as in the usual place behind the cam, but also enables the pressure angle for a given size of cam to be reduced.

Figs. 5A and 5B show diagrammatically a cam 50 with a roller follower 5| having its radius vector coinciding with the direction of movement of the follower. As shown in Fig. 5A the force vector 52 also coincides with the direction of movement. As shown in Fig. 5B the force vector 52 has deviated through an angle 01 from the direction of movement indicated by the arrow 53.

Figs. 6A, 6B and 60 show the same cam 59 and roller follower 5! but the roller follower has been off-set so that the radius vector is angularly displaced about the shaft axis in the opposite direction to the rotation of the cam and is therefore inclined to the direction of movement. Consequently, as shown in Fig. 6A the force vector 54 is initially coincident with the radius vector and inclined at an angle 02 to one side of the direction of movement indicated by th arrow 53. As shown in Fig. 6B the angle 02 by reason of change of position of the point of contact is zero and the force vector coincides with the direction of movement. In Fig. 60 the force vector 54 is inclined at an angle 03 on the other side of the direction of movement the point of contact having crossed to the other side of the direction of movement and thereby the maximum value of the component of force at right angles to the direction of movement is reduced. The useful component of the force (i) applied to the follower from the cam is 7 cos and it will be noted that in the diagrams 02 and 63 are each less than 01, and therefore the size of cam and the maximum pressure angle can be smaller when the cam and follower are arranged as in Figs. 6A, 6B and 6C than when arranged as in Figs. A and 53.

We claim:

1. In an under-pick loom having a combined swing rail and picking cam shaft, picking mechanism at each end of the shaft comprising a picking edge cam thereon, a bracket journalled on the shaft adapted to carry a sword arm of the loom and a picking stick pivotally mounted in the bracket with the axis of its pivot at right angles to the axis of the shaft and a cam follower attached to the picking stick, characterized in that the cam follower is off-set relative to the shaft so that it is angularly displaced about the shaft axis in the opposite direction to the rotation of the cam and its plane of movement is to one side of the axis of said shaft.

2. In a picking mechanism for a loom according to claim 1, wherein the roller cam follower is off-set so that the radius vector joining the axis of the shaft and the axis of the roller is angularly displaced about the shaft axis in the opposite direction to th rotation of the cam to such amount that the initial point of contact between the cam and roller at the commencement of the picking operation lies to one side of the said plane of movement and at some time during the acceleration of the picker such point of contact crosses th said plane and thereby the maximum value of the horizontal component of force applied to the follower relative to the plane of movement is reduced.

3. In a picking mechanism for a loom according to claim 2 the arrangement wherein the relative displacement of the point of contact to each side of the plane of movement of the cam follower is so proportioned that the maximum horizontal component of force at each side is substantially equal.

4. In a picking mechanism for a loom according to claim 2 and wherein the cam is designed to give substantially constant acceleration the arrangement wherein the relative displacement of the point of contact to each side of the plane of movement of the cam follower is equal so that the maximum horizontal component of force at each side is substantially equal.

5. In a picking mechanism for a loom according to claim 1, journals supporting the bracket on each side of the cam, and further journals, adjacent to each of the first mentioned journals, supporting the shaft.

6. In an under-pick loom having a combined swing rail and picking cam shaft, a picking mechanism at each end of the shaft carrying a picking edge cam on said shaft, a bracket journalled on the shaft on each side of the cam, mounting means on the bracket adapted to carry a sword arm of the loom, supporting bearings for the shaft on each side of the bracket, picking stick bearings on the bracket having its axis below and at right angles to the axis of the shaft, a picking stick mounted in such bearings and a spherical-surfaced cam follower roller mounted on and in bell crank relation to said picking stick so that it is angularly displaced about the shaft axis in the opposite direction to the rotation of the cam and its plane of movement is to one side of the axis of said shaft.

7. In an under-pick loom having a combined swing rail and picking cam shaft, picking mechanism according to claim 6 characterized in that the bracket is U-shaped.

8. In an under-pick loom having a combined swing rail and picking cam shaft, picking mechanism according to claim 7 further characterised in that the U-shaped bracket has a lateral extension overhanging the inner shaft bearing, having clamping means for the attachment of the sword arm and an additional bearing on the shaft in line with the sword arm.

JOHN JOSEPH VINCENT. FRANK DAVIES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Switzerland Dec. 1, 1930 Switzerland May 1, 1951 France Apr. 26, 1915 Great Britain Nov. 7, 1939 Number Number