GB2205113A

GB2205113A - Beat up mechanism

Info

Publication number: GB2205113A
Application number: GB08711986A
Authority: GB
Inventors: Cyril Millward Atkinson
Original assignee: ORBIT WEAVING MACHINERY LIMITE
Current assignee: ORBIT WEAVING MACHINERY LIMITE
Priority date: 1987-05-21
Filing date: 1987-05-21
Publication date: 1988-11-30
Also published as: GB8711986D0

Abstract

Beat up bar mechanism has a rotatable mounting with rings 10 which pivotably mount a plurality of beat up bars 22 formed of a lightweight member 30 and reeds 34 retained by resin. The bars 22 are clamped to cam follower brackets 12 and the followers are actuated by stationary cams so that the reeds 34 beat up the fabric fell. The member 30 may be of aluminium or reinforced resin and the reed dents 34 are held in position whilst the thermo-plastic resin is inserted during assembly. <IMAGE>

Description

TITLE: Beat-up bar mechanism for looms and looms having such mechanisms Field of invention The invention related to beat up bar mechanisms of the general kind described in the US Application 4388951 for use particularly in looms having rotary shed forming drums.

Background of invention The known beat up bar mechanism of US Application 4388951 had been designed for providing the required mechanical stability for the rapid rotary and reciprocatory individual beat up bar movement.

The inventions aims to provide an improved mechanism permitting higher operating speeds, reduced cost and/or simpler maintenance.

Summary of invention The invention provides beat up bar mechanism having a rotatable mounting, a plurality of beat up bars arranged generally in an annular array on the mounting, beat up reeds extending generally normal to the axis of mounting rotation, and a cam means for actuating the bars so as to cause the reeds to beat up a fell at a desired position in which the individual reeds are mounted by resin in a light member and the bar is removably mounted on a plurality of cam followers pivoted with respect to the mounting. Byjoining the reeds to the member by resin, the mechanical construction can be much simplified and made lighter. The individual reeds do not need to be clamped in position and the bar as a whole can be clamped more simply.Preferably the member is a metal profile, preferably of a light weight allcy such as aluminium, having an elongate cavity having a width matching that of the reeds. The bar is thus further simplified and made lighter. Conveniently the reeds are elongate metal strips whose extremities are set at the appropriate pitch by an appropriate holder during the setting of the resin.

Preferably each of the beat up bars is clamped to each of the individual followers controlling its reciprocatory movement. Thus the different followers are structurally interconnected and kept in mutual alignment by the bar to which they are clamped and a separate permanent supporting structure does not need to be provided.

The cam means may be of the double acting kind responsible for both senses of reciprocatory movement. Advantageously the cam means provides a trapezoidal curvature for initial rapid acceleration and deceleration for the reciprocatory movement and preferably a trapezoidal curvature for an initially rapid acceleration smoothly from standstill to maximum acceleration and vice versa. The smooth acceleration reduces vibration and so permits fairly light beat-up bars to be used for inter-connecting the followers. The cam means may be constituted by a fairly low number of cams well spaced along the axis of mounting rotation which act on a matching number of followers. The increased spacing minimizes the effect of any minor cam misalignment. Suitably the return stroke for reciprocatory movement away from the fell is reduced to permit lower acceleration and deceleration.

The cams are not only easy to manufacture but in turn complement the light beat up bar contruction to provide proper actuation even at high speeds without undue distorting of the bars. The cam curvature can be smoothed. A lower pressure angle can be provided at a maximum acceleration.

The overall result is a lighter beat up bar mechanism which can operate at higher speeds.

Drawings Figure 1 is a section through a beat-up bar mechanism of the invention normal to the axis of rotation; Figures 2 and 3 show alternative beat-up bars for use on the mechanism of Figure 1; and Figure 4 is a graph showing, at top, radial cam dimensions laid out developed over 3600 and at bottom the acceleration/deceleration imparted by such cam dimensions assuming a constant speed of rotation.

Description by reference to drawings A cam shaft assembly has a non-rotatable shaft 2 mounting cams 4 with grooves 6 milled in their sides.

The cams 4 are aligned accurately with respect to each other so as to act simultaneously and identically on cam followers.

The shaft 2 is adjustable angularly as a whole so as to provide the beat-up of the fell formed on an associated loom (not shown) at the required position.

Apart from the camshaft assembly, the beat-up mechanism also includes a beat-up bar assembly including rotatable rings 10 journal led on the shaft 2 which pivotably support six cam follower brackets 12 in close proximity to the cams 4. The brackets 12 have rollers 14 engaged within the grooves 6. The rings 10 are kept mutually aligned by bars 16 extended parallel to one another and fastened to the rings. The brackets 12 have threaded members 18 with discs 20 for use in clamping beat up bars 22 as shown in the Figure 1 details. The bars 22 are located prior to clamping by a recess 24 in the bracket body 26. The reed bars or beat up bars 22 may have (Figure 2? an extruded aluminium profile 30 wltn a central cavity 32 with walls engaging and iocating the edges of elongate straight-sided reeds 34.The reeds 34 are, in construction, mounted in a holder at the required pitch; then introduced with resin into the cavity 32; after which the resin is allowed to set and harden. Thus the reeds 34 do not have to be clamped and are at the correct pitch without pliering.

Alternatively (Figure 3) the reed bars 22 may be of a composite reinforced-resin construction 35 to provide a rigid, yet light weight construction. Whilst the reeds are sufficiently rigid for beating up the fabric fell, they can accomodate by minor distortion any residual misalignment of the cams 4 or cam follower brackets 12.

With reference now to Figure 4, the reeds 34 will be kept radially outward by elevated cam section A until the fell has been beaten up. Then in section B the ends of reeds 34 drop radially inward until they rest inside the outer periphery formed by the bars 16 in which action they move backwards clears of the fell and then pass underneath in the forward direction.

During the pivoting action withdrawing from the fell to an extent of 8 millimetre approximately, the reed bars 22 will first accelerate smoothly before reaching the maximum acceleration and then decelerate (dotted line in Figure 4j. The bars 22 will be moved radially outwards gradually when clear of the fell at section C.

The modified trapezoidal cam curvature provides the benefits associated with that from of cam profile.

Shock loads and steep initial cam angles are avoided.

The follower can track the cam accurately under bidirectional control. In addition surprisingly, the less abrupt cam profile permits the beat-up bars 22 to undergo minor distortion so as to keep all followers in good cam contact, reducing peak loads and vibration.

The gradual acceleration, low weight and inertia permit higher operational speeds.

Claims

CLAIMS:

1. Beat up bar mechanism having a rotatable mounting, a plurality of beat up bars arranged generally in an annular array on the mounting, beat up reeds extending generally normal to the axis of mounting rotation, and a cam means for actuating the bars so as to cause the reeds to beat up a fell at a desired position in which the individual reeds are mounted by resin in a light member and the bar is removably mounted on a plurality of cam followers pivoted with respect to the mounting.

2. Mechanism according to claim 1 in which the member is a metal profile, preferably of a light weight alloy such as aluminium, having an elongate cavity with a width matching that of the reeds.

3. Mechanism according to claim 1 or claim 2 in which the reeds are elongate metal strips whose extremities are set at the appropriate pitch by an appropriate holder during setting of the resin.

4. Mechanism according to any of the preceding claims in which each of the beat up bars is clamped to each of the individual followers controlling its reciprocetory movement.

5. Mechanism according to any of the preceding claims in which the cam means provides a trapezoidal curvature for initially rapid acceleration and deceleration for the reciprocatory movement.

6. Mechanism according to claim 5 in which the cam means provides a trapezoidal curvature for an initially rapid acceleration but changing acceleration smoothly from stand still to maximum acceleration and vice versa.

7. Mechanism according to claim 5 or claim 6 in which the reciprocatory movement away from the fell is reduced e.g. to from 6 to 10 mm, to permit lower acceleration and deceleration.

8. Beat-up bar mechanism substantially as described with reference to and as shown in the drawings.

9. A rotary shed forming loom having a beat-up 'bar mechanism according to any of the preceding claims.

10. A method of making a beat-up bar mechanism in which the reeds have extremities set at appropriate pitch by an appropriate holder during setting of resin for securing the reeds to the member in a cavity in the member.