GB2177429A

GB2177429A - Control mechanism for a shuttleless power loom having flexible belts

Info

Publication number: GB2177429A
Application number: GB08614170A
Authority: GB
Inventors: Michel Volland; Walter Grundler; Theo Thalmann; Miguel Angelo Stacher
Original assignee: Saurer Diederichs SA
Current assignee: Saurer Diederichs SA
Priority date: 1985-07-04
Filing date: 1986-06-11
Publication date: 1987-01-21
Also published as: FR2584425A1; IT8620704A1; IT8620704A0; DE3620688A1; GB8614170D0; IT1189593B; BE905027A; JPS6215356A

Abstract

A control mechanism is provided for a shuttleless loom having flexible perforated belts (1) carrying grippers (2) for the insertion of weft threads and passing over respective toothed drive wheels (4). The mechanism has connected cams (8, 9) mounted on a continuously rotatable shaft (10), a rocker lever (13) co-operating with cams (8, 9) a coupler (28) connected by first and second spherical plain bearings (29, 30) respectively to an arm (21) of the lever (13) and to rocking toothed sector (24). A spur pinion (23) of the mechanism engages with the toothed sector (24) and is connected in rotation with a toothed wheel (4) driving one of the belts (1). <IMAGE>

Description

SPECIFICATION Control mechanism for a shuttleless power loom having flexible belts The present invention relates to shuttleless power looms in which the weft is placed in position by means offlexible belts provided with grippers and driven by alternating movement.

Shuttleless power looms are well known in which the weft is inserted by means of two rigid or flexible "needles" or"lances"which have grippers attheir ends and are driven by alternating reciprocal tracking movement in such a manner that: when the needles are moving towards each other, the needle pulling the weft th read in its gripper conveys thethread to the centre of the shed where the thread is transferred to the gripper of the other needle; during the reciprocal backward movement of the two needles, the needle that has just received the weft thread completes the positioning thereof.

There are also shuttleless power looms that operate substantially according to the same principle but in which the grippers for drawing the weft thread are carried at the ends of two flexible perforated belts.

Each belt passes over a toothed wheel serving to drive the belt. The toothed wheel is driven so that it rotates in alternate directions in such a manner that it transmits a back-andforth movement to the straig ht portion of the belt having the gripper at the end.

It is necessary to drive the toothed wheel, in synchronism with the operation ofthe whole ofthe power loom, so that it rotates in alternate directions to an extent corresponding to the desired path ofthe flexible belt. This is generally achieved by means of a control mechanism that is capable of converting the continuous rotation of a shaft of the power loom into alternating rotation of the toothed wheel driving the belt.

For this purpose, the existing control mechanisms generally use cams, couplers and gears, the combination of which forms a mechanical transmission of greater or lesser complexity. Since the shaft of the power loom forming the source of movement is usually perpendicular to the axis of the toothed wheel on which the belt runs, this mechanical transmission comprises, mostfrequently, conical gear wheels or other bevel gears which make it expensive to manufacture, create play in the mechanism and generate undesirable axial stresses. Mechanism constructed in this manner are described, for example, in Swiss Patent 606551 and in French Patent 2438697.

The present invention is designed to eliminate the disadvantages mentioned above by providing an especially simple control mechanism that is inexpensive and uses only spur gears, this mechanism being perfectly balanced and allowing easy adjustment of the path oftheflexible belts.

To this end, the control mechanism according to the invention for a shuttleless power loom having flexible belts comprises, for each belt, in combination: at least one cam arranged on a shaft ofthe power loom driven in continuous rotation about an axis parallel to the rectilinear displacement of the belt, a lever mounted sa that it can rock about an axis parallel to that of the above-mentioned shaft, and cooperating with the cam(s), a coupler connected by a firstjointto an arm ofthe rocker lever and connected by a second joint to a toothed sector mounted so that it can rock about an axis parallel to the axis of rotation ofthetoothed wheel driving the belt, and a spur pinion in engagement with the tooth ed sector and connected in rotation with the toothed wheel driving the belt.

The mechanism forming the subject of the invention comprises especially a couplerwhich, in a plane perpendicu la r to that of the toothed sector, transmits tothetoothed sectorthe rocking movementofthe lever. Thus, the bevel gears are eliminated and the number of spur gears required is reduced to a minimum since the mechanism requires only a toothed sector and a single pinion.

Since the couplerconnects two members which rock in perpendicular planes, it is preferably connected to the arm of the rocker lever by a first joint of the spherical plain bearing type and is connected to the rocking toothed sector by a second joint also of the spherical plain bearing type.

In a special embodiment ofthe invention,the rocker layer comprises, in addition to its arm connected to the coupler, two branches having rollers which cooperate respectively with two connected cams arranged on the shaft driven in continuous rotation.

According to a further characteristic, the toothed sector is extended, beyond its rocking axis, by an arm on which is located the second joint ofthe coupler.

This arrangement is especially balanced, the toothed sector itself, on the one hand, and the extension arm to which the coupler isjoined, onthe other hand, extending into diametrally opposedzoneswith respect to the rocking axis of the toothed sector.

Advantageously,the position ofthe second joint of the coupler is adjustable along the arm forming the extension ofthe toothed sector. This allows the rocking angle or of the toothed sector to be varied and thus allows the path of the beltto be adjusted. The second spherical plain bearing joint ofthe coupler is, for example, held by a support that can slide along the extension arm of the toothed sector and is locked on the arm in the desired position by at ieast one screw.

The arm extending thetoothed sector advantageously has a dished shape, the concavity of which is turned towards the first joint of the coupler, which allows adjustment to be made by pivoting the coupler about its first joint, without having to displace the toothed sector.

The inventionwill be more readily understood, however, from the following description which refers to the attached diagrammatic drawings showing, by way of a non-limiting example, an embodiment of this control mechanism for a shuttieless power loom having flexible belts: Figure lisa perspective view of a mechanism according to the inventionforthecontrol of a belt of such a power loom; Figure 2 is a cross-section of the mechanism of Figure 1, showing more precisely certain detailsofthis mechanism.

The mechanism shown in the drawing is designed to control a flexible belt (1) having at oneend a gripper (2) suitable for holding a weft th read. The belt (1) has perforations (3) and coils round a toothed drive wheel (4) which is mounted so that it can rotate about an axis (5) and theteeth ofwhich engage in the perforations (3). The mechanism forming the subjectofthe invention drives the toothed wheel (4) so that it rotates in alternate directions indicated bythe double-headed arrow (6) in such a manner as to drive the straight portion ofthe belt (1) having the gripper (2) at one end alternating translational movement, indicated by a second double-headed arrow (7). The portion of the belt (1) located on this side of the toothed drive wheel (4) may be guided and stored in a casing, not shown.

In Figure 1 the toothed drive wheel (4) is shown at a distance from the control mechanism for the sake of the clarity of the drawing.

This control mechanism comprises two connected cams (8,9) mounted on a shaft (10) ofthe power loom which, in operation, is driven in continuous rotation, as indicated byan arrow(1 1), aboutan axis (12) parallel tothe rectilinear displacement of the belt (1), that is to say at right-anglesto the axis of rotation (5) of the toothed drivewheel (4).

Thetwo connected cams (8,9) are associated with a lever (13) mounted so that it can rock about an axis (141 parallel to the axis (12) ofthe shaft (10). The lever t13r has a first branch (15) which has at its free end a roller (16) rotating about an axis (17) and rolling on the first cam (8); the lever (13) has also a second branch (18) which has at its free end a further roller (19) rotating about an axis (20) and rolling on the second cam (9t This rocker lever (13) is also provided with anarm (21).

Thetoothed drive wheel (4) is mounted on ashaft (22) on which is mounted a spur pinion (23), the shaft (22) being mounted so that it can turn aboutthe axis (5). The pinion (23t engages with a toothed sector (24) which is integral with a huh (25) by which it ismou nted so that it can rock about an axis (26) parallel to the axis (5). The hub (25) of the toothed sector is is extended by a dished arm (27) formed buy two parallel branches, as shown in greater detail in Figure 2. With respect two the hub (25),the toothed sector (24) on the one hand andthe arm (27) on the other hand extend into diametrally opposed zones.

The arm (21) of the rocker lever (13) is connected to the arm (27) integralwith the toothed sector (24) by means of a coupler (28). One end of the coupler (28) is connected to the free end ofthe arm (21) by a first spherical plain bearing (29). The other end of the coupler (28) is connected by a second spherical plain bearing (30) to a point onthe dished arm (27).

Figure 2 shows thetwo spherical plain bearings (29,30) in detail. Thefree end of the arm (21) of the rockerlever (13) is provided with a spherical bearing surface (31) around which is mounted an annular element (32) having a spherical internal surface and housed and retained in a cylindrical recess (33) formed inone end of the coupler (28).

The other end of the coupler t28) also hasa cylindrical recess (34) in which is housed andretained anannularelement(35) having aspherical internal surface surrounding a spherical bearing surface(36).

The spherical bearing surface (361 is held by a support (37) which passes rightthrough itand which isftxedto the two branches of the dished arm (27) in such a mannerthatthe second spherical plain bearing (30) is located between the two branches ofthe dished arm (27).

The support (37) is fixed on each branch ofthe dished arm (27) by means of a locking screw (38) which passes th rough the corresponding branch and is screwed into a supportthread (37). The head of each screw (38) rests on the upperface of the corresponding branch by means of a collar (39),whilethe support (37) is applied, by tightening the screw (38), against the lowerface ofthis branch ofthe arm (27).

The fixing means described above allow adjustment of the position ofthesecond joint (30) ofthe coupler (28) along the dished arm (27) integral with the toothed sector (24), loosening of the screws (38) allowing the support(37) to be moved on the arm (27).

The wholeofthe control mechanism previously described is housed in a casing (40) partially shown in Figure 2.

When the power loom is in operation, the continuous rotation ofthe shaft (10) in the direction ofthe arrow (11) causes, by means of the connected cams (8,9), a rocking movement of the lever (13) about the axis (14), each complete turn oftheshaft(10) being accompaniedbyone rocking movement of the lever (13) in a plane perpendicularto the axis (12).

By means of the coupler (28), the rocking movement ofthe lever (13) is transmitted to the toothed sector (24) which rocks in a plane perpendicularto the axes (5,26) and also perpendicularto the rocking plane of the lever (13). The alternating rotation of the toothed sector (24) istransmitted to the pinion (23), and thus communicated also to the toothed wheel (4), which thus makes the straight portion of the belt (1), having the gripper (2) atthe end, move back and forth as desired.

The extent of th is back-and-forth movement is determined by the radius of the toothed wheel (4) and also by the ratio ofthe radii of the pinion (23) and the toothed sector (24). The radius ofthe pinion (23) is selected small with respect to that of the toothed sector (24) so that one rocking movement of the toothed sector (24) over a limited angle causes one alternating rotation ofthe pinion (23), the extent of which can be severai turns so thatthe belt (1)travels over a substantial path.

The adjustment of position of the joint (30) of the coupler (28)on the arm (27) makes it possibleto modifythe rocking angle of the toothed sector (24) and thus the extent of the alternating rotation of the pinion (23) and the toothed wheel (4), and consequently the path of the belt (1).

Acontrol mechanism similartothe mechanism described above and operating in synchronism with the latter is provided forthe second flexible belt ofthe power loom.

Naturally, the inventionis not limited to the single embodiment of this control mechanism for shuttleless power looms having flexible belts that has been described above by way of example; on the contrary, the invention includesall variants rnspectingthe same principle, whatever the details of construction.

Claims

1. Acontrol mechanismforashuttleless power loom having at least one perforated flexible belt which has a gripperforthe insertion of a weft th read and passes over a toothed drive wheel driven so that it rotates in alternate directions, said mechanism comprising at least one cam arranged on a shaftofthe power loom driven in continuous rotation about an axis parallel to the rectilinear displacement ofthe belt, a lever mounted so that it can rock about an axis parallel to the axis ofthe above mentioned shaft and co-operating with the or each cam, a coupler con nected by a firstjointto an arm ofthe rocker lever and connected by a second joint to a toothed sector mounted so that it can rock about an axis parallel to the axis of rotation ofthe toothed wheel driving the belt, and a spur pinion in engagement with the toothed sector and connected in rotation with the toothed wheel driving the belt.

2. Acontrol mechanism according to Claim 1, wherein the rocker lever comprises, in addition to its arm connected to the coupler, two branches having rollers which co-operate respectively with two connected cams arranged on the shaft.

3. A control mechanism according to Claim 1 or Claim 2, wherein the coupler is connected to the arm ofthe rocker lever by a firstjoint of the spherical plain bearing type and is connected to the rocking toothed sector by a second joint also ofthe spherical plain bearing type.

4. Acontrol mechanism according to anyone of Claims 1 to 3, wherein the toothed sector is extended, beyond its rocking axis, by an arm on which is located the second joint ofthe coupler.

5. A control mechanism according to Claim 4, wherein the toothed sector itself and the extension arm to which the coupler is joined extend respectively into diametrally opposed zones with respect to the rocking axis of the toothed sector.

6. A control mechanism according to Claim 4 or Claim 5, wherein the position ofthe second joint on the coupler is adjustable along the arm extending the toothed sector.

7. A control mechanism according to the combination of Claims 3 and 6, wherein the second spherical plain bearing ofthe coupler is held by a supportthat can slide along the arm extending the toothed sector and is locked on the arm in the desired position by at least one screw.

8. A control mechanism according to Claim 7, wherein the arm extending the toothed sector is formed by two parallel branches and the support of the second spherical plain bearing located between these two branches, is fixed in an adjustable position on each branch by means of a locking screw passing through the associated branch.

9. A control mechanism according to any one of Claims 4to 8, wherein thearm extending the toothed sector has a dished shape,the concavity ofwhich is turned towards the firstjoint ofthe coupler.

10. A control mechanism for a shuttleless loom having perforated belts with grippersforthe insertion ofweftth reads, substantially as hereinbefore de scribedwith reference to the accompanying drawings.

11. Ashuttleless loom having perforated belts with grippersforthis insertion of weft threads and incorporaton a control mechanismaccording to anv one ofthe preceding claims.