An automatic device for removing windings of fibres from a unit for drawing a sliver of textile fibres

Abstract

 A unit for drawing a sliver of textile fibres includes a drawing head (1) with a plurality of combs (8) which are movable along an endless path. Brushes for cleaning the combs (8) are carried by motor-driven shafts (12) and are adapted to collect windings of fibres formed on the combs. Sensors detect the accumulation of textile fibres on the brushes (8) and cause the intervention of a cycle in which the whole of a winding which has started to form is collected automatically on the brush in question and the intervention of a device which replaces said brush (10) with a spare brush (10a).

Description

[0001] The present invention relates to a unit for drawing a sliver of textile fibres, of the type including a drawing head with a plurality of combs which are movable along an endless path with a working portion in which the combs cooperate with the sliver and a return portion where there is at least one brush for cleaning the combs, the brush being carried by a motor-driven shaft which has sensor means for detecting an accumulation of textile fibres wound around the brush.

[0002] In known drawing units of the type defined above, a portion of the sliver frequently becomes detached from the main sliver and follows the return path of the combs. This portion of the sliver is collected by the brush and forms a winding which in most cases tends to grow until the sliver itself is completely broken. When this occurs, sensor means indicate the anomaly to the personnel supervising the machine, who replace the brush.

[0003] The object of the present invention is to provide a drawing unit of the type specified above which enables normal operating conditions to be re-established without the need for manual intervention when fibres become wound around the head or in order to replace the brush, the replacement of which may be programmed.

[0004] According to the present invention, this object is achieved by the provision of a drawing unit of the type defined above, characterised in that it includes an automatic device for replacing the brush, possibly after completely removing windings which have started to form on the combs, the device including:

• manipulator means for removing a brush from the motor-driven shaft, taking a new brush, and fitting it on the motor-driven shaft, and
• a control unit which is arranged to receive a signal from sensor means for detecting windings on the combs in order to stop the supply to the head so as to break the sliver, to advance the drawing head until all the fibres liberated have collected on the brush in question, and to cause the manipulator means to intervene.

[0005] By virtue of this characteristic, the windings are removed and the brush is replaced completely automatically without the need for manual intervention.

[0006] Further characteristics and advantages of the present invention will become clear in the course of the detailed description which follows with reference to the appended drawings, provided purely by way of non-limiting example, in which:

Figure 1 is a schematic, perspective view of a drawing unit according to the present invention,

Figure 2 is a section taken on the line II-II of Figure 1, and

Figures 3 to 5 are schematic, perspective views showing the operating sequence of the unit of Figure 1.

[0007] With reference to Figure 1, a drawing head of the known type with two sets of needles (see, for example, the Applicant's U.S. patent 4554709) is indicated 1. Upstream of the drawing head 1 is a pair of motor-driven rollers 5 between which the sliver supplied to the drawing head 1 is gripped. The head 1 is constituted by an upper set of needles 2 and a lower set of needles 4, between which a sliver of textile fibres 6 is inserted. Each set of needles 2, 4 has a plurality of combs 8 which are movable in the senses indicated by the arrows A and B. The combs 8 of each set of needles 2, 4 move along an endless path with a working portion in which the combs cooperate with the sliver 6 and a return portion in which there is a brush 10 for cleaning the combs 8. The brushes 10 are keyed to respective motor-driven shafts 12 which are rotated by a motor (not shown), by means of gears 14. The shafts 12 are carried by respective arms 15, each of which can pivot about an axis C between a lowered position, shown in Figure 4, and a raised position, shown in Figures 3 to 5.

[0008] A blade 16, carried by an arm 18, is also disposed on the return path of each set of needles 2, 4 and is spaced from the combs 8. The arms 18 of the blades 16 are associated with respective position sensors 20 for detecting movements of the blade 16 away from the combs 8.

[0009] The drawing unit shown in Figure 1 also includes a device for automatically replacing the brushes 10. This device includes a holder, indicated 22, for spare brushes and a manipulator 24 associated with each motor-driven shaft 12 for moving the brush 10. The structure of the devices 22 and 24 will be described below with reference only to the upper set of needles 2, since the portion of the device which relates to the lower set of needles 4 is identical to the former.

[0010] As can be seen in Figure 2, the brush 10 is keyed to the motor-driven shaft 12 by a key 26 which is articulated on the shaft 12 at 28. The key is urged outwardly by a helical spring 30 and engages a groove 32 in the brush 10. A push-rod 29, slidable in the shaft 12, has a first end 31 which acts on the key 26 and a second end 33 which cooperates with a cam profile 35.

[0011] The manipulator 24 is constituted essentially by a fluid actuator 34 carrying an arm 36 on the distal end of which is a plate 38 which fits with clearance in a circumferential groove 40 in the brush 10 (see Figure 2). The plate 38 of the manipulator 24 retains the brush 10 axially on the motor-driven shaft 12 and can move the brush 10 axially as a result of the activation of the actuator 34. The plate 38 does not, however, prevent the brush 10 from rotating with the shaft 12.

[0012] The holder 22 includes a fixed structure 42 carrying a pair of rods 44 each of which carries a disc 46. Each disc 46 carries a plurality of shafts 48, one of which is empty, spare brushes 10a being fitted on the others. The rod 44 of each disc 46 is rotatable on the fixed structure 42 about an axis parallel to the axis of rotation of the motor-driven shaft 12 and is spaced therefrom by a distance equal to the distance between the axis of the rod 44 and the axis of each shaft 48. The rotation of the disc 46, thus aligns the shafts 48 selectively with the motor-driven shaft 12 when it is in its raised position. The fixed structure 42 carries a chain 50 which is connected to the rods 44 by gears 52. The chain 50 also engages a motor-driven pinion 54 which is rotated by a geared motor unit 56.

[0013] The operation of the drawing unit will be described below.

[0014] During the operation of the drawing head 1 a portion 6a of the sliver 6 frequently becomes detached from the main sliver 6 and follows the return path of the combs 8. When the portion of sliver 6a meets the brush 10 it is wound around the latter as shown in Figure 1. The portion 6a of the sliver thus becomes taught, resulting in the raising of the blade 16, which is detected by the sensor 20. A conventional control unit (not shown) receives the fault signal from the sensor 20 and stops the rollers 5 upstream of the drawing head 1. The drawing head continues to operate for a certain time, however, so as to tear the sliver between the rollers (5) and the head 1. The whole of the portion of the sliver which remains on the drawing head 1 is thus collected by the brush 10 (Figure 3). At this point, the arm 15 of the motor-driven shaft 12 pivots about the axis C, to its raised position. In this position, the empty shaft 48 of the holder 22 is aligned with the motor-driven shaft 12 and is thus ready to receive the brush 10. As the arm 15 pivots, the push-rod 29 of the motor-driven shaft 12 comes into contact with the fixed cam profile 35 and withdraws the key 26 inwardly of the shaft 12, releasing the brush 10. The control unit activates the actuator 24 which urges the brush 10 along the motor-driven shaft 12 and along the shaft 48 aligned therewith by means of the arm 36 and the plate 38 (Figure 4). At this point, the geared motor unit 56 rotates the rods 44 through an angle equal to the angular distance between two successive shafts 48. During this rotation, the plate 38 which previously engaged the groove 40 in the brush 10 becomes engaged in the groove 40 of a spare brush 10a. At this point, the actuator (24) is made to effect a return stroke and pulls the replacement brush 10a onto the motor-driven shaft 12 (Figure 5).

[0015] The brushes 10 for both sets of needles 2, 4 are replaced even if the anomaly occurred in only one. The personnel supervising the machine periodically remove the dirty brushes from the holder 22 and replace then with clean brushes.

[0016] The control unit is also arranged to change the brushes, if faults of the type described above do not occur for a predetermined period of time, so as to prevent an excessive accumulation of dirt on the brushes.

Claims

1. An automatic device for removing windings of fibres from a unit for drawing a sliver of textile fibres including a drawing head (1) with a plurality of combs (8) which are movable along an endless path with a working portion in which the combs (8) cooperate with the sliver (6) and a return portion where there is at least one brush (10) for cleaning the combs (8), the brush being carried by a motor-driven shaft (12) which has sensor means (16, 20) for detecting an accumulation of textile fibres (6a) wound around the brush (10), characterised in that it includes an automatic device for replacing the brush, the device including:

- manipulator means (24) for removing a brush (10) from the motor-driven shaft (12), taking a new brush (10a), and fitting it on the motor-driven shaft (12), and

- a control unit which is arranged to receive a signal from the sensor means (20) in order firstly to stop the supply of the sliver to the drawing head and then the operation of the head and to cause the manipulator means (24) to intervene.

2. A device according to Claim 1, characterised in that it includes a holder (22) for spare brushes (10a), including a plurality of parallel shafts (48) projecting from a motor-driven disc (46) which is rotatable about an axis (44) parallel to the axis of the motor-driven shaft (12) and is adapted to bring the shafts (48) selectively into alignment with the motor-driven shaft (12).

3. A device according to Claim 2, characterised in that the manipulator means (24) include an arm (36) which is movable parallel to the axis of the motor-driven shaft (12) and is adapted to perform an outward stroke during which it urges the brush (10) along the motor-driven shaft (12) towards an empty shaft (48) of the holder (22), to engage a replacement brush (22) which is brought into alignment with the motor-driven shaft (12) as a result of the rotation of the disc (46), and to perform a return stroke during which it pulls the replacement brush (10a) onto the motor-driven shaft (12).

4. A device according to Claim 3, characterised in that each brush (10, 10a) has a circumferential groove (40) in which an engagement portion (38) of the arm (36) is disposed, the engagement portion extending radially relative to the axis of the brush (10).

5. A device according to Claim 1, characterised in that the motor-driven shaft (12) has a key (26) which is urged resiliently outwardly of the shaft (12) and is intended to engage a groove (32) in the brush (10).

Drawing