Patent Application
20110154628
The present invention relates to the general field of circular needling machines for making needled textile structures, and more particularly it relates to automatically feeding such machines with fiber sheets.
It is known to make a circular type needling machine for fabricating annular textile structures for constituting the fiber reinforcement of annular parts made of composite material, in particular brake disks, such as disks made of carbon/carbon (C/C) composite material for airplane brakes.
In such a needling machine, a helical fiber sheet for needling is placed on a needling table and is driven in rotation by drive means, usually friction drive means. The feed for this type of machine may be performed flat on the needling table from a sheet of material for needling that is delivered by an unwinding device that is external to the needling machine.
Document WO 02/088449 discloses a needling machine in which the fiber sheets for needling are fed automatically. For that purpose, the needling machine comprises a storage basket located above the needling table and containing the fiber sheet for needling, a set of conical rollers for continuously extracting the sheet from the storage basket, and a helical chute for taking up the sheet unwound from the storage basket and bringing it to the needling table in register with friction drive means. Nevertheless, that needling machine presents the drawback that the conical rollers for driving the fiber sheet cause the fiber sheet to slip while it is being unwound, thereby deforming the fiber sheet when it reaches the needling table.
A main object of the present invention is thus to mitigate such drawbacks by proposing a circular needling machine in which the needling table is fed with fiber sheets automatically and without deforming the sheets.
This object is achieved by a circular needling machine for needling a textile structure formed from a helical fiber sheet, the machine comprising a needling table disposed beneath a feed table for feeding a helical fiber sheet for needling, and wherein, in accordance with the invention, the feed table comprises a circular belt conveyor for receiving thereon a helical fiber sheet for needling, the conveyor being centered on a vertical axis and having a radial slot opening out under the circular conveyor to unwind continuously the fiber sheet received on the conveyor, the slot opening out under the conveyor towards a substantially straight chute that extends vertically between the conveyor and a support tray of the needling table centered on the vertical axis of the conveyor so as to take up the sheet unwound from the conveyor and bring it onto the needling table, said support tray having means for driving the fiber sheet in rotation about the vertical axis.
The presence of a circular conveyor makes it possible to deliver the fiber sheet without tension, the sheet then being guided vertically towards the needling table by means of the chute. Thus, no deformation appears in the fiber sheet before it is needled. In addition, compared with a helical chute, the presence of a chute that is substantially straight makes it possible to save space for positioning other functions of the machine (such as engaging the fiber sheet and automatically cutting it).
In an advantageous provision, the needling table further includes a guide tray centered on the vertical axis and movable vertically relative to the support tray between a low, operating position in which it rests on said support tray, and a raised, disengaged position in which it is positioned above said support tray.
Under such circumstances, the chute has one portion secured to the feed table and another portion secured to the guide tray of the needling table, these portions being suitable for moving in translation one inside the other during the vertical movements of the guide tray.
The means for driving the fiber sheet in rotation may comprise two pairs of conical rollers that are angularly spaced apart from each other and that are designed to come into contact with the fiber sheet brought onto the needling table.
A conical presser roller may be secured to the guide tray of the needling table and may be placed at the outlet from the chute.
The feed table may further include a roller placed under the circular conveyor and angularly interposed between the slot and the inlet of the chute so as to enable a free end of the sheet being unwound from the conveyor to be taken up and guided towards the chute.
Means may be provided for removing the textile structure from the support of the needling table, said means advantageously comprising a manipulator arm provided with a hinged finger for taking hold of and removing the textile structure. Cutter means for cutting the fiber sheet may also be provided.
Preferably, the circular conveyor of the feed table has two curved conveyor portions, each in the form of a half-disk and disposed facing the other, the slot being formed by a gap left between the two conveyor portions.
Other characteristics and advantages of the present invention appear from the following description made with reference to the accompanying drawings which show an embodiment having no limiting character. In the figures:
The needling machine 10 comprises a feed table 100 for feeding fiber sheet for needling, a needling table 200 placed under the feed table and a removal table 300 for removing the needled structure from the needling table.
The feed table 100 for feeding the fiber sheet for needling comprises a circular conveyor 102 centered on a vertical axis 104 and receiving thereon a fiber sheet 106 for needling. The fiber sheet is more precisely wound as a plurality of layers around a central cylinder 108 centered on the vertical axis 104, and it is driven to rotate about said axis by the circular conveyor.
As shown in
Each curved conveyor portion 102a, 102b thus serves to perform a 180° half-revolution of the fiber sheet 106. For this purpose, and in known manner, each curved conveyor portion comprises a looped (or endless) belt 110a, 110b that is tensioned around a stationary cylindrical bar 112a, 112b of horizontal axis causing it to follow a semicircular trajectory. The curved edge 114a, 114b of said looped belt is secured to a looped chain 116a, 116b (or the like) suitable for following a semicircular trajectory. This looped chain is tensioned between two sprocket wheels 117a, 117b on the same axis as the cylindrical bar 112a, 112b, one of these sprocket wheels being rotated by a motor 118a, 118b. The motors 118a, 118b are synchronized so as to cause both looped belts of the curved conveyor portions to move at the same speed of rotation.
The curved conveyor portions 102a, 102b are spaced apart from each other so as to leave between them a radial slot 120 to allow the fiber sheet 106 positioned on the circular conveyor to be unwound. A plate 122 covers about half of this gap between the curved conveyor portions.
The radial slot 120 opens out under the circular conveyor 102 of the feed table into a substantially straight chute 400 that extends vertically between the circular conveyor and the needling table 200. The function of this chute is to take the sheet 106 that is being unwound from the conveyor and to guide it vertically onto the needling table.
For this purpose, and as shown in
The straight chute 400 is in the form of a hollow tubular duct extending vertically from its inlet 402 that opens out beneath the circular conveyor 102 to its curved outlet 404 of shape that matches the curvilinear profile of a support tray 202 of the needling table (see
The fiber sheet brought in this way onto the support tray 204 is driven in rotation about the vertical axis 104 in the same direction of rotation as the circular conveyor so as to pass under a needling head, as described below. For this purpose, rotary drive means for the fiber sheet comprise two (or more) pairs of conical rollers that are angularly spaced apart from one another. Each pair of rollers 204 comprises a conical roller 204a forming a presser roller continuously in contact with the fiber sheet, and a conical backing roller 204b placed in an opening in the support tray facing the presser roller 204a so that the fiber sheet is sandwiched between them. More precisely, the support tray is perforated so that the backing rollers 204b come directly into contact with the fiber sheet that is placed on the tray.
The presser rollers 204a are driven in rotation, e.g. each by means of respective independent gearmotor units 206 controlled by control means (not shown). The backing rollers 204b may be free to rotate or they may optionally be driven. The control means serve in particular to synchronize the speeds of rotation of the various rollers. Naturally, other conventional rotary drive and synchronization means could be envisaged for the rollers.
The needling table also has a guide tray 208 in the form of two annular walls 210 centered on the vertical axis 104 and extending vertically from the support tray 202. These vertical walls are connected together by lateral reinforcements 212 and they serve to provide lateral guidance of the fiber sheet while it is rotating about the vertical axis.
In an advantageous configuration, the guide tray is movable vertically relative to the support tray 202 between a low, operating position in which it rests on said support tray to provide lateral guidance for the fiber sheet 106 (
The vertical movement of the guide tray 208 is provided, by way of example, by means of an actuator 216 having its cylinder 216a secured to the feed table 100 and its rod 216b fastened to the guide tray. The actuator is actuated by control means (not shown). The guide tray is raised in translation about a bar 218 centered on the vertical axis 104 and fastened to the feed table.
Furthermore, this vertical movement is made possible because the chute 400 presents one portion 400a that is secured to the feed table 100 and another portion 400b that is secured to the guide tray 208 of the needling table, these two portions 400a, 400b being suitable for moving in translation one inside the other during movements of the guide tray (in the example of
It should be observed that the guide table 208 has an angular cutout 219 corresponding to the shape of the needling head (described below) and allowing the guide tray to pass when it moves vertically.
In another advantageous configuration, the guide tray 208 also has a conical presser roller 220 that is placed at the outlet from the chute 400. This presser roller is positioned more precisely immediately above the fiber sheet when it leaves the chute so as to flatten the fiber sheet correctly before it passes under the needling head. The two pairs of rollers 204 for delivering rotary drive to the fiber sheet and to the presser roller 220 are preferably spaced apart angularly from one another by about 120° (
The fiber sheet brought onto the support tray is needled by a needling head 222 that has some determined number of barbed needles and that is located vertically above the support tray between the two pairs of conical rollers 204 for delivering rotary drive to the sheet. In known manner, in order to enable the various superposed layers of fiber sheet to be needled to one another, the needling head is driven with vertical reciprocating motion by conventional drive means 224. In addition, the support tray 202 of the needling table is movable vertically under drive from drive means 226 as the needling operation progresses.
Cutter means located upstream from the needling head are also provided for cutting the sheet once a predetermined final thickness has been obtained for the textile structure (sensors that are not shown serve to monitor this thickness accurately as the various layers are superposed one on another). As shown in
Once the sheet has been cut and the structure has been needled, the removal means shown in
It should be observed that central control means (not shown in the figures) are connected to the motors 118a, 118b of the curved conveyor portions of the feed table, to the drive means 226 of the support tray 202 of the needling table, to the gearmotor unit 206 of the pairs of conical rollers 204 for driving the fiber sheet in rotation, to the drive means 224 for driving the needling head 222, to the cutter means 228, 230 for cutting the fiber sheet, and to the removal means 302, 304 for removing the textile structure. These central control means provide the synchronization and control that are needed for obtaining a continuous needling process.
| Number | Date | Country | Kind |
|---|---|---|---|
| 09/59406 | Dec 2009 | FR | national |
