Patent Publication Number: US-10781543-B2

Title: Guide tooling for a circular needling table for needling a textile structure made from a helical fiber sheet

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to the general field of circular needling tables for making needled textile structures from a helical fiber sheet. 
     It is known to use a needling table of circular type for fabricating annular textile structures that are to constitute the fiber reinforcement of annular parts made out of composite material, in particular brake disks, such as carbon/carbon (C/C) composite material disks for airplane brakes. 
     A circular needling table generally comprises a horizontal annular turntable on which a helical fiber sheet is placed, drive means (usually friction drive means) for driving the fiber sheet in rotation about the vertical axis of the turntable, and a needling device having a needling head extending over an angular sector of the turntable and driven to move vertically relative to the turntable. Reference may be made to Document WO 02/088451, which describes an embodiment of such a needling table. 
     Also known from Document EP 2 339 055 is a needling machine in which the needling table includes guide tooling in the form of two annular walls centered on the vertical axis of the turntable and connected together by lateral reinforcement serving to provide lateral guidance for the fiber sheet during its rotation about the vertical axis. 
     With that type of needling table, once the structure has been needled, it is necessary to take hold of it and remove it from the table without damaging it, in particular by exerting mechanical stresses. Unfortunately, the presence of walls for guiding the sheet makes that operation difficult to perform without damaging the fiber structure. 
     OBJECT AND SUMMARY OF THE INVENTION 
     A main object of the present invention is thus to propose guide tooling that does not present the above-mentioned drawbacks and that enables the needled structure to be removed without exerting mechanical stresses. 
     This object is achieved by guide tooling for a circular needling table for needling a textile structure made from a helical fiber sheet, the tooling comprising an inner guide rail of circularly arcuate shape, and an outer guide rail of circularly arcuate shape arranged coaxially around the inner guide rail and connected thereto by radial reinforcement, the outer and inner guide rails defining between them a passage for guiding the helical fiber sheet under a needling head, and wherein, in accordance with the invention, the outer guide rail is made up of two outer guide rail angular sectors that are connected to each other by an outer actuator, the outer actuator being suitable for moving the adjacent free ends of the outer guide rail angular sectors apart from each other so as to expand the outer guide rail. 
     The guide tooling of the invention is remarkable in that it is possible to expand the outer guide rail once the structure has been made, thereby making it easier to extract the structure from the guide tooling without exerting mechanical stress thereon, and thus without risk of damaging it. Naturally, during the stage of needling proper, the outer guide rail is maintained in its contracted position by the outer actuator. 
     The outer actuator may comprise an actuator cylinder fastened to a free end of one of the two outer guide rail angular sectors, and a rod fastened to an adjacent free end of the other outer guide rail angular sector, the outer actuator being positioned outside the outer guide rail and extending in a direction that is tangential thereto. 
     Furthermore, the outer guide rail may expand by pivoting of the two outer guide rail angular sectors about distant free ends of said outer guide rail angular sectors. 
     In an advantageous provision, the inner guide rail is made up of two inner guide rail angular sectors that are connected together by an inner actuator, the inner actuator being suitable for moving the distant free ends of the inner guide rail angular sectors towards each other so as to contract the inner guide rail. 
     Contracting the inner guide rail further facilitates extracting the finished needled structure from the guide tooling, thereby further reducing any risk of damaging it. 
     Under such circumstances, the inner actuator may comprise an actuator cylinder fastened to one of the two inner guide rail angular sectors, and a rod fastened to the other inner guide rail angular sector, the inner actuator being positioned inside the inner guide rail and extending along a direction tangential thereto. 
     Furthermore, the inner guide rail may be contracted by pivoting the two inner guide rail angular sectors about adjacent free ends of said inner guide rail angular sectors. 
     The radial reinforcement may be secured to a plate positioned over the inner and outer guide rails. Under such circumstances, the plate advantageously includes a deflector designed to guide the helical fiber sheet from a feed table towards the passage defined between the outer and inner guide rails. 
     The invention also provides a circular needling table for needling a textile structure made from a helical fiber sheet, the table including guide tooling as defined above. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       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: 
         FIG. 1  is a side view showing a needling machine in which the needling table is provided with guide tooling of the invention; and 
         FIGS. 2 and 3  are perspective views, respectively from above and from below, of the  FIG. 1  guide tooling. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a circular needling machine  2  for needling a textile structure, or annular preform, made from a helical fiber sheet (or strip). 
     Typically, and as described in publication EP 2 339 055, the needling machine  2  has a feed table  4  for feeding fiber sheets for needling, which feed table is located above a needling table  6 . 
     By way of illustration, the feed table  4  for feeding fiber sheets for needling may comprise a circular conveyor  8  centered on a vertical axis  10  and having a fiber sheet  12  for needling placed thereon. More precisely, the fiber sheet may be wound as a plurality of turns about the vertical axis  10  and may be driven in rotation about the vertical axis by the circular conveyor  8 . 
     Under the circular conveyor  8 , the feed table  4  leads to a straight chute  14  that extends vertically between the circular conveyor and the needling table  6 . The function of this chute is to take up the sheet  12  as it is unwound from the conveyor and to guide it vertically towards the needling table. 
     The fiber sheet is taken onto a support platform  16  of the needling table  6  and is driven in rotation about the vertical axis  10  in the same direction of rotation as the circular conveyor so as to pass under a needling head  18 , which head is driven with vertical reciprocating motion by conventional drive means  19 . 
     For this purpose, the rotary drive means for the fiber sheet may comprise a plurality of pairs of rollers  20  that are angularly spaced apart from one another. Each pair of rollers  20  typically comprises a conical roller  20   a  forming a presser roller in continuous contact with the fiber sheet, and a conical backing roller  20   b  arranged in an opening in the support platform of the needling table and facing the presser roller  20   a  so as to sandwich the fiber sheet between the rollers. More precisely, the support platform  16  is slotted so that the backing rollers come directly into contact with the fiber sheet placed on the platform. 
     The needling table  6  also has guide tooling  22  pressing on the support platform  16 . This guide tooling serves to guide the fiber sheet while it is being needled. 
     For this purpose, in the invention and as shown in  FIGS. 2 and 3 , the guide tooling  22  comprises an inner guide rail  24  in the form of a circular arc centered on the vertical axis  10 , and an outer guide rail  26  in the form of a circular arc arranged coaxially around the inner guide rail. 
     The inner and outer guide rails are connected to each other by radial reinforcement  28 , thereby defining a passage for guiding the helical sheet under the needling head of the needling table. The radial reinforcement  28  is secured to a plate  29  positioned above the inner and outer guide rails. 
     Still in the invention, the outer guide rail  26  is made up of two outer guide rail angular sectors  26   a ,  26   b , which are connected to each other by an outer actuator  28  positioned outside the outer guide rail and extending in a direction that is tangential thereto. 
     This outer actuator  28  is suitable for moving the adjacent free ends  26   a - 1  and  26   b - 1  of the two outer guide rail angular sectors  26   a  and  26   b  apart from each other so as to expand the outer guide rail. 
     More precisely, the outer actuator  28  has an actuator cylinder  30  that is fastened to one free end  26   a - 1  of one of the two outer guide rail angular sectors (specifically the outer guide rail sector  26   a  in  FIGS. 2 and 3 ), and a rod  22  that is fastened to an adjacent free end  26   b - 1  of the other outer guide rail angular sector  26   b.    
     Thus, when the outer actuator is actuated, its rod  32  extends from the actuator cylinder  30  so as to move apart the adjacent free ends  26   a - 1  and  26   b - 1  of the two outer guide rail angular sectors  26   a  and  26   b . The distant free ends  26   a - 2  and  26   b - 2  of the outer guide rail sectors pivot about respective stationary pivots  34   a  and  34   b.    
     Once needling has terminated, expanding the outer guide rail serves to facilitate extracting the needled fiber structure from the guide tooling  22  without exerting mechanical stress thereon, and thus without risk of damaging it. 
     The inner guide rail  24  is also made up of two inner guide rail angular sectors  24   a  and  24   b , which sectors are connected together by an inner actuator  36  positioned inside the inner guide rail and extending in a direction that is tangential thereto. 
     This inner actuator  36  is suitable for moving towards each other the distant free ends  24   a - 2 ,  24   b - 2  of the two inner guide rail angular sectors  24   a  and  24   b  so as to contract the inner guide rail. 
     More precisely, the inner actuator  26  comprises an actuator cylinder  38  that is fastened to one of the two inner guide rail angular sectors (specifically the sector  24   b  of the inner guide rail in  FIGS. 2 and 3 ), and a rod  40  that is fastened to the other inner guide rail angular sector  24   b.    
     Thus, when the inner actuator is actuated, its rod  40  enters into the actuator cylinder  38  so as to move the distant free ends  24   a - 2  and  24   b - 2  of the inner guide rail angular sectors towards each other so as to contract the inner guide rail. The adjacent free ends  24   a - 1  and  24   b - 1  of the inner guide rail angular sectors pivot about respective stationary pivots  42   a ,  42   b.    
     Once needling has terminated, contracting the inner guide rail  24  serves likewise to facilitate extracting the needled fiber structure from the guide tooling without exerting mechanical stress thereon, and thus without risk of damaging it. By expanding the outside diameter and contracting the inside diameter of the guide tooling, extraction of the needled fiber structure is made considerably easier. 
     In an advantageous arrangement, the plate  29  to which the radial reinforcement  28  of the guide tooling  22  is secured includes a deflector  44  for guiding the fiber sheet from the outlet of the chute  14  ( FIG. 1 ) towards the passage defined by the outer and inner guide rails of the guide platform. 
     It should be observed that the needling table also includes a conical roller  46  that is arranged at the outlet from the chute  14  in association with the deflector  44 . More precisely, this roller is positioned immediately above the fiber sheet as it leaves the chute in such a manner as to drive the fiber sheet before it passes under the needling head. 
     It should also be observed that the support platform  16  on which the guide tooling  22  rests is movable vertically under drive from motion-transmission means  48  progressively while the needling operation is taking place. 
     It should also be observed that the inner and outer actuators used for expanding the outside diameter and contracting the inside diameter of the guide platform may be actuators of any type (pneumatic, electrical, hydraulic, mechanical, manual, etc.).