Needling device for consolidating a fibre fleece

Abstract

Needles (47) periodically penetrate into a needling path (1) between a stripper plate (26) and a needling table (24). In the process, the needles describe an elliptical movement by means of which they accompany the textile when they are in penetration phase. The elliptical movement is generated by oscillating-sliding of a rod (38) in a rotating guide (39). The rod (38) is actuated by two crank connecting-rod systems (51a, 51b), the adjustable phase shifting of which defines the horizontal amplitude of the movement of the needles. Use for simplifying elliptical guiding means, reducing plays and air turbulences.

Description

This invention relates to a needling or pre-needling device intended to consolidate a fleece of fibres.

In a standard needling device (or needle loom), a plurality of needles oriented transversely to the plane of the fleece are reciprocated rapidly in order to periodically pass through the fleece and thus interweave the fibres of the different layers. The needles carried by one or more needle bars are integral with a movable structure comprising a support for the needle bar or bars, and rods which slide in the frame of the machine in order to guide the movable structure according to said reciprocating movement. Pinch rolls placed at the needle loom outlet exert a tractive force on the consolidated fleece. This traction is transmitted to the fleece located at the needle loom inlet when the needles are in their withdrawal phase, i.e. disengaged from the fleece. Given the low mechanical strength of the fleece upstream of the needle loom, this traction transmitted across the needle loom is capable of damaging the homogeneity of the fleece entering the needle loom, and consequently damaging the quality of the final product.

In order to deal with this problem, needle looms with what is called an “elliptical” movement have been proposed. This term means that in profile view a point of the needles, for example the tip of each needle, describes a closed-loop trajectory, for example oval or ovoid, resembling an ellipse, without necessarily being an ellipse in the mathematical sense of the term. In such needle looms, the needles are given a combined movement comprising two components each constituted by a reciprocating movement: the penetration component as a first component, and a superimposed progression component parallel to the direction of progression of the fleece through the needle loom. This second movement takes place in the same direction as the progression of the fleece when the needles are in penetration phase, and in the return direction, opposite to the direction of progression of the fleece, when the needles are in withdrawal or disengagement phase. The sliding assembly which guides the movable structure relative to the frame is omitted. The movable structure is guided by several crank-and-connecting-rod systems which at the same time constitute the actuating mechanism imparting the more or less elliptical movement to the needles.

Documents DE-A-1 803 342, FR-A-2 180 928, U.S. Pat. No. 5,732,453, and EP-A-892 102 describe such needle looms with an “elliptical” movement.

As the needles follow the progressive movement of the fleece while they are in penetration phase, there is no longer the problem of a stretching of the fleece between the pinch rolls and the needles when the needles are in penetration phase. At the same time, by their movement in the direction of progression of the fleece when they are in penetration phase, the needles help the fleece to penetrate inside the needle loom.

However, these needle looms have the drawback of being expensive and mechanically complex, and comprising a large number of moving parts, some of which are heavy and bulky. This results in vibrations on the one hand, and air movements on the other hand. The latter are very disadvantageous for the fleece in the non-consolidated form in which said fleece enters the needle loom. The air movements tend to disperse the non-interlinked fibres and consequently to damage the fleece with inhomogeneities and width irregularities.

Document FR-A-2 180 928 accordingly describes a needle loom with an elliptical movement comprising first crank-and-connecting-rod-means, the connecting rod or rods of which have a general vertical orientation in order to generate the vertical penetration movement of the needle bar, and second crank-and-connecting-rod means, the connecting rod or rods of which have a general horizontal orientation, in order to generate the horizontal progressive movement of the needle bar.

Document EP-A-892 102 proposes improvements to the above-described needle loom, in particular means for easily adjusting the progression stroke of the needle bar. More particularly, two connecting-rod small ends are articulated to the two ends of a cross-bar, the central point of which is articulated to the needle-bar support. An adjustable angular lag of the cranks, for example by means of stepper motors, allows to adjust the progression stroke.

In order to reduce the length of the machine, the document proposes placing the crank-and-connecting-rod system, responsible for the progressive movement of the needle bar, on top of the machine. An oscillating bell-crank arm converts the generated movement into the desired horizontal alternating progressive movement. But the number of complex mechanical parts, and the mass of the reciprocating parts, have also increased.

The object of this invention is therefore to provide a needling apparatus of the elliptical-movement type which is mechanically simplified and has a small space requirement compared with the prior art machines, which makes it possible to consolidate a fleece of fibres at a relatively high rate with a particularly small deformation of the fleece. The invention also provides such an apparatus that can be used for the pre-needling of a fleece.

The invention is at least partly based on a recognition that the prior mechanisms are all designed to keep the movable structure carrying the needles substantially parallel to itself during its movement. It has been found according to the invention that it was possible to escape this constraint, and that this would result in a simplification and rationalization of the system.

According to the invention, the needling or pre-needling apparatus comprises a movable structure intended to carry needles, and an actuating mechanism for imparting to the needles an elliptical-type movement having a penetration component and a progression component. It is characterized in that one of the components, preferably the progression component, is at least to a large extent generated by angular oscillation of the movable structure.

The solution proposed according to the invention allows a more direct guiding of the movable structure relative to the frame, a reduction in the accumulated plays which affect the positioning of the movable structure and therefore of the needles, a reduction in the vibrations and in the space requirement.

In the known needle looms with an elliptical movement, the largest dimension of the ellipse, parallel to the direction of travel of the fleece, is situated more or less halfway between the maximum-penetration position and the maximum-withdrawal position. This is the case in particular when the trajectory is a perfect ellipse having two axes of symmetry: the small median, parallel to the direction of progression of the fleece, is at an equal distance from the two ends of the large median, which correspond respectively to the maximum-penetration and maximum-withdrawal positions of the needles. It has been found according to the invention that this configuration is not advantageous: the needles accompany the progressive movement of the fleece for only half of the penetration stroke of the needles. In the other half, i.e. the upper half if referring to the case where the needles are above a fleece with horizontal progression, the needles move in the opposite direction to the fleece and must therefore be disengaged from the fleece. The reciprocating stroke of the needles in the direction of penetration must be double the desired useful stroke. This results in increased vibrations, wear, and a reduction in the rates.

According to a feature of the invention, in order to deal with these drawbacks, the elliptical-type movement of the needles takes place along a trajectory having, parallel to the direction of progression of the fleece, a larger dimension which is closer to the maximum-withdrawal position than to the maximum-penetration position of the needles.

The movable structure is preferably guided relative to a frame of the machine by a functional chain comprising a sliding which is operatively in series with an articulation about an oscillation axis which is parallel to the width of the fleece of fibres. The sliding provides one of the components, typically the penetration, and the articulation allows the angular oscillation generating the other component, typically the progressive movement.

According to a possible embodiment, the actuating mechanism comprises two crank connecting-rod systems, each system comprising a connecting rod one small end of which is articulated to said movable structure in a so-called positioning axis parallel to said axis of oscillation.

Thus, according to the invention, the movable structure to which the needle bar is attached is both i) reciprocating in a direction which is globally vertical or more generally globally transverse to the plane of the path of the fleece and ii) oscillating about an axis of oscillation integral with the frame. Thanks to an asymmetry preferably consisting of a phase-shift between the two crank connecting-rod systems, there is provided that, relative to the direction of progression of the fleece through the needle loom:

in the drop phase, the connecting rod situated downstream is more proximal (relative to the fleece) than the other connecting rod, so that the needle bar is located tilted upstream;

in the vicinity of the position of maximum-penetration in the fleece, the needle bar tilts from upstream to downstream when the reversal of the direction of the vertical component of the needle bar movement occurs;

in the lift phase, the connecting rod situated downstream is this time more distal (relative to the fleece) than the other connecting rod, so that the needle bar remains tilted downstream; and

in the vicinity of the position of maximum-withdrawal of the needles from the fleece, the needle bar tilts from downstream to upstream when the reversal of the direction of the vertical component of the movement occurs.

Consequently, according to the invention, the elliptical-type movement differs from the prior art in particular in that the needle bar is in a position tilted (i.e. not parallel to the plane of the fleece) either downstream or upstream, with a downstream/upstream tilting movement when the bar is in the distal part of its reciprocating penetration movement and an upstream/downstream tilting movement when the bar is in the proximal part of its reciprocating penetration movement. In the prior art (described in particular in the documents mentioned above) the needle bar, while still travelling along its “elliptical” path, always remains more or less in a plane parallel to the fleece of fibres. Moreover, according to the invention, the needle bar passes from a position tilted upstream to a position tilted downstream in the proximal part of its reciprocating penetration stroke, which indeed produces the sought effect of accompanying the progression of the fleece.

The aim of the invention is achieved thanks to this novel mechanism, mechanically simplified as it can comprise only two crank connecting-rod systems in order to carry out both the vertical component and the horizontal component of the elliptical movement.

Preferably, separately or in combination:

• • a guide-way providing the abovementioned sliding is placed substantially between two eccentric means turning in opposite directions to each other and each belonging to a respective one of the two crank connecting-rod systems; this allows better balancing of the forces of inertia;
  • the two connecting rods are oriented with their ends forming the connecting-rod small end pointing in a direction generally away from the plane of the fleece; thus, the process of reversing the direction of the vertical component of the movement of the needles in the vicinity of the position of maximum penetration takes place very slowly, with a virtual stoppage time during which part of the movement of the needles in the direction of progression of the fleece takes place efficiently and under good conditions. Moreover, thus arranged, the mechanism is particularly compact;
  • the two centre-distance lines each connecting the axis of a crank and the axis of the associated connecting-rod small end form between them an angle very different from 0° and from 180°, preferably of the order of 70°. The two connecting-rod small end axes are preferably closer to each other than the two crank axes;
  • for adjusting the phase shift between two crank connecting-rod systems, it is possible to use a differential gear placed operatively between the two crank connecting-rod systems, and comprising a planet gear carried by a case having an adjustable fixed angular position;
  • according to another modified embodiment, it is possible to use servomotors (“brushless” motors) which are mechanically independent but coordinated by a central control, in order to drive the two crank connecting-rod systems at an equal speed with an adjustable phase shift;
  • according to a preferred modified embodiment, for said adjustment of the phase shift between two crank connecting-rod systems, it is possible to use, between two co-axial half-shafts each of which is coupled to one of the crank connecting-rod systems, a clutch comprising two discs each integral in rotation with one of the half-shafts, and being able to be applied one against the other in a chosen relative angular position for carrying out the desired phase shift;
  • in a particularly preferred fashion, these discs have, on their mutual contact faces, radial splines, in particular Hertz gear teeth having between them a pitch of the angle-degree order about the common axis of the half-shafts;
  • at least the half-shaft linked to the motor is associated with an angle encoder;
  • in order to modify the adjustment of the phase shift, the discs are moved apart from each other, the half-shaft associated with the motor is turned through an angle that is monitored preferably by means of the encoder, while still locking the other half-shaft, then the discs are brought back into mutual angular interlocking contact;
  • by providing an encoder on each half-shaft the phase shift carried out is verified.

Other features and advantages of the invention will also emerge from the following description, which relates to non-limitative examples.

In the attached drawings:

FIG. 1 is a diagrammatic side view of a needle loom according to the invention;

FIG. 2 is a diagrammatic side view of a pre-needling/needling installation illustrating another embodiment of the invention;

FIGS. 3 and 4 are diagrammatic perspective views of two embodiments of a phase-shift device; and

FIG. 5 is a diagram of the needle loom according to FIG. 1.

The needling apparatus 2 according to the invention shown in FIG. 1 is located in a box 11 having an entry window 12 in which a feed apparatus 4 is installed and an exit window 13 in which an extractor apparatus 7 is installed. A fleece of fibres (not shown) thus follows in the box 11 a path 1 with a direction of progression 6.

In the following, “distal” and “proximal” respectively mean “relatively distant from” and “relatively close to” the plane of the path 1.

The needling apparatus 2 comprises a movable structure 36 which in turn comprises at least one rod 38. In practice, there are several parallel rods 38 aligned in the direction of the width of the fleece, and only one of which therefore appears in the drawings. In order to simplify the description, it is often considered in the following that there is only one rod 38. The movable structure 36 also comprises a support 44 rigidly secured to the proximal end of the rod 38. A needle bar 46 is rigidly but interchancheably secured to the support 44, on the face thereof which is remote from the rod 38. The bar 46 carries needles 47 which extend towards the fleece parallel to a longitudinal axis 42 of the rod 38. In the region of the needles 47, the fleece path 1 is defined by a needling table 24 adjacent to the face of the fleece opposite the needle bar 47, and by a stripper plate 26 adjacent to the fleece face turned towards the needle bar 47. The table 24 and the stripper plate 26 have orifices (diagrammatically shown in each case as grouped together in a large opening in FIG. 1) which are suitable for the needles 47 to pass through when they are in their maximum-penetration position.

Each sliding rod 38 is mounted so as to slide along its longitudinal axis 42 in a respective guide 39 itself supported in an oscillating manner in a frame 19 of the apparatus 2, about an axis of oscillation 37 which is parallel to the width of the fleece of fibres. The axis 37 intersects the longitudinal axis 42 of the sliding rod 38 in the middle of the axial length of the bore of the guide 39 in which the rod 38 slides. By means which will be described hereafter, the longitudinal axis 42 oscillates about the oscillation axis 37 on either side of a general axis 43 intersecting the axis 37 and perpendicular to the plane of the path 1. The movable structure 36 simultaneously performs a reciprocating movement in a direction of penetration transverse to the plane of the path 1 of the fleece, and an oscillating movement about the oscillation axis 37 integral with the frame 19. The oscillation movement is intended to impart to the needles 47 what is called a “progressive” component of movement, essentially parallel to the direction 6 of progression of the fleece.

Thus, there is between the needles 47 and the frame 19 of the machine a kinematic linkage comprising a sliding which is operativealy in series with an articulation. In this example, starting from the needles 47 there is first the sliding of the rod 38 in the guide 39, then the rotation of the guide 39 in the frame 19. The kinematic linkage in question means that there is between the needles and the frame of the machine a mechanical part, in this case the guide 39, which is guided in rotation relative to one of the two elements, here the frame, and is slidingly guided relative to the other element, here the needles. This kinematic linkage does not serve to actuate the movable structure.

Moreover, in this embodiment, the sliding guide surface of the guide 39 is situated inside its surface 40 of articulation in the frame. Thus, the two guidings are extremely close to each other, the accumulated plays are as small as possible, and the guiding of the movable structure 36 relative to the frame is almost as precise and robust as a simple and single articulation.

The pre-needling installation also comprises an actuating mechanism which in turn comprises two eccentric shafts—or cranks—48a, 48b supported in rotation by the frame 19 about axes 49a, 49b parallel to the oscillation axis 37 and situated in the example symmetrically on either side of the general axis 43. The actuating mechanism also comprises two connecting rods 51a, 51b, the big end 52a, 52b of which is articulated to a respective eccentric journal 53a, 53b of the eccentric shafts 48a, 48b. The small end 54a, 54b of each connecting rod 51a, 51b is articulated to the oscillating-sliding rod 38 about a respective positioning axis 56a, 56b. The positioning axes 56a, 56b are close to the distal end of the rod 38. Along the axis 42 of the rod 38, the sliding guide 39 is placed between the support 44 and the centre-distance line 56c passing through the two positioning axes 56a, 56b. In the example shown, the guide 39 is more or less halfway between the support 44 and the centre-distance line 56c. Each connecting rod 51a, 51b is situated on a same respective side of the axis 42 of the oscillating-sliding rod 38.

The axes 49a, 49b of the eccentric shafts 48a, 48b have between them a centre distance E which is very different from the centre distance e between the positioning axes 56a, 56b of the connecting-rod small ends. If the radii of the eccentricities 61a and 61b of the connecting-rod big-ends axes 53a and 53b relative to the axes of rotation 49a and 49b of the eccentric shafts 48a and 48b are respectively designated r_a and r_b, relationship (1) applies:
|E−e|>r_a+r_b   (1)

The result is that the two connecting rods never become parallel to each other and always keep the same direction of inclination relative to each other.

In the example shown, E is greater than e, and r_a=r_b=r, so that relationship (1) becomes relationship (1A):
E−e>2r   (1A)

Moreover, if the centre-distance length of each of the two connecting rods 51a and 51b is respectively designated L_a and L_b, relationship (2) applies:
|E−e|<(L_a+L_b)−(r_a+r_b)   (2)

The result is that the two connecting rods are never substantially aligned, even when the two connecting-rod big ends are in a position of maximum distance from each other.

In the example shown where:
E>e
r_a=r_b=r
L_a=L_b=L
relationship (2) becomes (2A):
E−e<2L−2r   (2A)

The combined relationships (1) and (2) produce relationship (3):
(L_a+L_b)−(r_a+r_b)>|E−e|>(r_a+r_b)   (3)

The combined relationships (1A) and (2A) produce relationship (3A):
2L−2r>E−e>2r   (3A)

Relationships (3) and (3A) state that the centre-distance lines 60a and 60b between each eccentric axis 49a or 49b and the corresponding connecting-rod small-end axis 56a or 56b form between them an angle A which is very different from 0° and from 180°. This angle A is approximately 70° in the example shown.

The arrangement is such that the two connecting-rod small ends 54a, 54b are directed obliquely towards each other, and away from the path 1 of the fleece. The vertex of the angle A is therefore situated beyond the two connecting-rod small ends.

The two positioning axes 56a, 56b are arranged symmetrically relative to the axis 42 of the oscillating-sliding rod 38 and relatively close to each other. In other words, the value e is low. This reduces the space requirement, as well as the stresses in the rod 38, which can therefore be made lighter.

The two eccentric shafts 48a, 48b are driven in opposite rotation directions and at the same rotation speed, as indicated by arrows 57a, 57b, for example by means of mutually meshing toothed wheels 58a, 58b, each turning integrally with a respective one of the shafts 48a, 48b. In the example shown, the arrangement and the rotation directions 57a, 57b are such that when the eccentric journals 53a, 53b travel along the part of their circular trajectory directed towards the plane of the path 1 of the fleece, the connecting rods 51a, 51b operate in traction and are only slightly inclined relative to a line perpendicular to the plane of the fleece. They thus very efficiently transmit their force for the penetration of the pre-needling needles 47 into the fleece. During the lift phase, the connecting rods 51a, 51b are much more oblique, they operate in compression and in a less favourable orientation, but the effort to be provided is less. Overall, the distribution of efforts over a cycle is optimized, which makes it possible to lighten the mechanism, and therefore to reduce the inertia forces and vibrations, which further increases the possible lightening.

The mechanism comprises means for shifting the phase of the shaft 48b relative to the shaft 48a. These means are diagrammatically shown in FIG. 5 by an adjustment 59 of the angular position of the shaft 48b relative to the toothed wheel 58b which rotatably drives said shaft about its axis 49b.

The adjustment of the phase-shift angle between the radii 61a and 61b allows adjustment of the length of the progression component (parallel to the direction of progression of the fleece) of the movement of the needles 47. The phase shift is considered to be zero when the two cranks 48a, 48b are in symmetrical angular positions relative to the axis 43 of the mechanism. The axis 42 of the rod 38 then permanently coincides with the axis 43 of the mechanism and the progression component is zero.

As shown in FIG. 1, in order to obtain a progression component which is not zero, the adjustment device 59 is adjusted so that the eccentric shaft 48b situated upstream relative to the direction 6 of progression of the fleece lags relative to the shaft 48a situated downstream.

As a result:

• • When the rod 38 moves away from the fleece, the connecting rod 51a situated downstream is at the same time more distal than the other connecting rod 51b, which places the distal end of the rod 38 upstream; consequently the proximal end of the rod 38 is displaced downstream, and the set of needles 47 is itself displaced in the direction 6 relative to the axis 43;
  • During the drop phase, this is reversed, the connecting rod 51a ahead of the other is more proximal and keeps the proximal end of the rod 38 in a position tilted towards the rear;
  • A significant part of the movement of the needles 47 downstream takes place in the vicinity of the maximum-penetration position in the fleece, where the reversal of the direction of the vertical component of movement takes place with accelerations that are further reduced due to the non-coincidence of the dead centres of the two crank connecting-rod systems; this position just after tilting is shown in FIG. 1; and
  • The tilting from downstream to upstream takes place largely in the vicinity of the maximum-withdrawal position of the needles 47.

The orifices of the table 24 and of the stripper plate 26 are oblong with a sufficient length for the needles 47 to be able to carry out the progression component of their elliptical movement (parallel to the direction of travel 6 of the fleece).

The invention makes it possible to easily separate a part lubricated for example with oil and including the crank connecting-rod mechanisms and the top of the oscillating-sliding rod 38 as far as the guide 39, and a “textile” part protected from the oil, situated between the guide 39 and the path 1 of the fleece. This is facilitated in particular when the guide 39 guides the rod 38 between the needle bar support 44 on one side and the connecting-rod small ends 56a, 56b on the other side. There is then an oil-tight barrier which separates the two parts and through which the rod 38 passes just below the guide 39. This barrier is for example a metal plate (not shown) comprising, for the passage of the rod 38, an opening equipped with a bellows seal (not shown) leak-tightly secured on the one hand to the periphery of the opening and on the other hand to the periphery of the rod 38.

In a preferred modified embodiment, the two crank connecting-rod systems and the top of the oscillating-sliding rod 38 are enclosed in a casing (not shown) having an opening surrounding the guide 39. A bellows seal tightly seals this opening about the guide 39. There is moreover in the bore of the guide 39 at least one annular lip seal (not shown) which is in leak-tight sliding contact with the cylindrical side wall of the rod 38.

The example shown in FIG. 2 relates to an installation which comprises, along the path 1 for the fleece of fibres, a consolidation apparatus 2 directly preceded by a pre-needling apparatus 3 according to the invention, i.e. driven with an elliptical-type movement generated according to the invention.

The pre-needling apparatus 3 and the consolidation apparatus 2 are housed jointly in a single box and form part of the same machine also comprising a feed apparatus 4 and an extractor apparatus 7.

The consolidation apparatus is here a needling apparatus 2 which comprises a movable structure 14 reciprocating linearly in a fixed sliding direction 16, perpendicular to the plane of the path 1 of the fleece. A sliding rod 17 forming part of the structure 14 is slidingly mounted in a slide guide 18 secured to the frame 19 of the machine. The structure 14 also comprises a support 21 fixed to the proximal end of the rod 17 by means of a bracket 92 or intermediate part, and a needle bar 22 secured in an interchangeable manner to the support 21. Needling needles 23, of which only two are shown and the ends of the others are diagrammatically shown by the dot-dash line 23a, are oriented perpendicularly to the plane of the path 1 and distributed over the surface of the bar 22. In the region of the needles 23, the path of the fleece is defined between a stripper plate 126 and a needling table 124 which is adjacent to that face of the fleece which faces away from the needle bar 22. The table 124 and the stripper plate 126 have orifices (not all shown) through which the needles 23 pass when they are in the maximum-penetration position as shown in FIG. 2.

For the generation of the reciprocating movement, the needling apparatus 2 comprises an alternating-movement generator, and more particularly a connecting rod 127 the big end 28 of which is articulated to an eccentric journal 29 of an eccentric shaft 31, and the small end 32 of which is articulated to the distal end of the sliding rod 17. The shaft 31, rotatably supported in a bearing integral with the frame 19, is driven in rotation by an adjustable-speed motor, not shown.

The pre-needling apparatus 3 corresponds to a second embodiment of the invention. The movable structure 136 of the pre-needling apparatus comprises, instead of the oscillating-sliding rod 38 of the needling mechanism of the apparatus of FIG. 1, a bell crank 138 a proximal end of which is secured to the support 44 carrying the needle bar 46. The bent part of the crank 138 is articulated at an axis of oscillation 137 to the intermediate part 92 integral with the sliding rod 17 of the consolidation apparatus 2. The distal end of the crank 138 is articulated at a positioning axis 156 to the small end 93 of a connecting rod 94 the big end 96 of which is articulated to the eccentric journal 97 of an eccentric shaft 98 mounted in rotation relative to the frame 19 and driven at the same speed of rotation as the eccentric shaft 31 of the apparatus 2. The eccentricity radius 161b of the eccentric shaft 98 lags relative to the eccentricity radius 161a of the eccentric shaft 31, which actuates the axis of oscillation 137 via the connecting rod 127 and the rod 17. Thus, when the consolidation needles 23 are in maximum-penetration position, the eccentric shaft 98 will carry out a part of its movement in which it will push the small end of connecting rod 93 further downwards and therefore cause the bell crank 138 to pivot in anti-clockwise direction in FIG. 2. This result in the component of movement as indicated by the arrow 91a when the pre-needling needles 47 are in a substantially maximum-penetration position.

This solution reduces the distance between the pre-needling needles 47 and the entrance to the fleece between the table 124 and the stripper table 126 of the needling apparatus 2.

In the example shown, the table of the pre-needling apparatus is replaced by a driven drum 224 carrying a succession of discs 225 defining between them annular grooves which are deep enough to receive the tips of the needles 47 in maximum-penetration position. The bottoms of the grooves are defined by fingers 227 which extend as far as the beginning of the table 124.

Instead of a coupling by toothed wheel (FIG. 1) or timing belt (FIG. 2), the two crank connecting-rod systems of FIG. 1 or of FIG. 2 could each be driven by a respective servomotor. The two servomotors are connected to a common control which adjustably controls their common speed and their reciprocal phase shift.

However, this solution has the drawback that a breakdown of one of the two motors can cause damage, in particular mechanical interference between the needles and the stripper plates or the needling table.

In the example shown in FIG. 3, a more advantageous solution consists of coupling the eccentrics 48a, 48b of the two crank connecting-rod systems of the example of FIG. 1, by an adjustable differential gear 71.

A drive motor 72 drives a primary pinion 73 which drives in the same direction as itself the eccentric 48b via a cascade of an intermediate pinion 74b and a secondary pinion 76b which is connected to the eccentric 48b by a shaft 77b. The primary pinion 73 is coaxial with the secondary pinion 76a which is integral with the eccentric 48a by a shaft 77a. The primary pinion 73 drives the secondary pinion 76a via a movement-reversing conical pinion 74a, constituted by the planet gear of the differential 71. The planet gear rotates freely on its own axis in a differential-gear case 78. The angular position of the case 78 about the common axis 81 of the pinions 73 and 76a determines the phase shift between the shafts 77a and 77b. A servomotor 79 secured to the frame of the apparatus controls the angular position of the case 78 about the axis 81 via a reduction gear 82 comprising a screw 82_v driven by the servomotor 79 and a ring gear 82_c formed on the periphery of the radially outer face of the case 78. The reduction gear 82 is irreversible in as much as torques undergone by the case 78 about its axis 81 relative to the frame of the needling apparatus are unable to rotate the screw 82_v. The case 78 is therefore immobilized against rotation about its axis 81 relative to the frame of the needling apparatus when the servomotor 79 is at rest.

Another solution for adjusting the phase shift between two crank connecting-rod systems, shown in FIG. 4, consists of omitting the differential gear 71 as well as its motor 79 and its reduction gear 82 and replacing all this with a dog clutch 401 mounted between the primary pinion 73 and the eccentric 48a with which it is coaxial along the axis 81. As the eccentric 48a now turns in the same direction as the primary pinion 73, the counter gear 74b between the primary 73 and secondary 76b pinions has been omitted in order to reverse the direction of rotation of the eccentric 48b relative to that of the eccentric 48a. Relative to the common motor 72, the clutch 401 is downstream of the gear train 73, 76, which transmits the movement to the other eccentric 48b, with the result that the eccentrics 48a and 48b can turn independently of each other when the clutch 401 is disengaged. The clutch comprises two discs 402, 403 one of which is axially movable as indicated by the arrow 404. The mutual contact faces of these discs comprise radial gear teeth 406, 407 capable of mutually fitting together when the clutch is engaged. The pitch of the gear teeth is typically of the angle-degree order. There is also a brake 408 making it possible to lock the eccentric 48a situated downstream of the clutch 401, and a respective angle encoder (not shown) on each eccentric 48a, 48b. In order to adjust the phase shift, the brake 408 is applied, the clutch 401 is disengaged and the eccentric 48b is turned through the desired angle with the motor 72, until the desired relative angular position is reached, monitored with the coders. The clutch 401 is then re-engaged and the brake 408 released. In this embodiment, the motor 72 and the eccentric 48a with which it is coaxial turn in the same direction in operation. The advantage is that the transmissible torque is far greater than that of a differential gear, the cost is much lower and the assembly simpler and therefore more reliable than that of FIG. 3.

Alternatively, if the two eccentrics 48a and 48b must turn in the same direction (case of FIG. 2) the counter gear 74b between the primary pinion 73 and the secondary pinion 76b is retained.

A description follows, with reference to FIG. 5, of certain features which are preferred for the configuration, the development and the dimensioning of the embodiment of FIG. 1.

In the position shown, the crank 48a is in the angular position θ relative to the line 49c passing through the centres 49a and 49b of the two cranks, and the crank 48b is in advance by the phase shift φ, so that its angular position is θ+φ relative to the line 49c.

FIG. 5 shows, as representative of the “elliptical” trajectory of the needles, the trajectory T of a point P of the needle bar 46, this point situated on the axis 42 of the oscillating-sliding rod 38.

The trajectory T is divided into a proximal part and a distal part by an ideal line TL parallel to the direction of progression of the fleece, so that in the whole of the proximal part, i.e. that passing through the maximum-penetration point TP, the movement of the needles has a progression component which is in the direction of progression of the fleece.

For a trajectory T of given shape, the line chosen as being the line TL is that situated as far as possible from the point TP, i.e. if the line TL were moved still slightly further from the point TP, there would be in the proximal part of the trajectory T at least one point of the trajectory where the progression component of the movement of the needles would be in the opposite direction to the direction of progression of the fleece. Consequently, the line TL passes through at least one end of the reciprocating stroke of progression of the needles. In the preferred configuration shown, the two ends of the reciprocating stroke of progressive movement of the needles are on the line TL. It is consequently possible to measure along the line TL the stroke of progression CA of the needles.

According to a feature of the invention, the shape of the trajectory T is chosen so that the line TL is situated closer to the point TR of the trajectory which corresponds to the maximum-withdrawal position of the needles, than to the point TP of the trajectory T which corresponds to the maximum-penetration position of the needles.

Thus, the useful stroke CU of penetration of the needles, from the line TL to the maximum-penetration point TP, and along which the needles can be engaged in the fleece while accompanying the progressive movement of the fleece, is particularly long relative to the total stroke CP of the needles in the direction of penetration.

It has been found according to the invention that such an ovoid trajectory T with the more tapered part directed towards the fleece can be obtained with dimensioning searches case by case, more easily when the “high dead centres” of the crank connecting-rod systems correspond to the region of the point TR of the trajectory of the needles. By “dead centre” of a crank connecting-rod system is meant each of the two states of the system where the crank axis, connecting-rod small-end axis and connecting-rod big-end axis are aligned. By “high dead centre” of a crank-connecting rod system is meant the one of said two dead centres where the connecting-rod big end 52a, b is placed between the crank axis 49a, b and the connecting-rod small end 54a, b.

The configuration shown, with the guide 39 situated between the connecting-rod small ends 54a, 54b on the one hand and the needle bar 46 on the other hand, has advantages of compactness, rigidity, relatively simple possibility of placing the whole of the device in the oil above the bar support 44. Moreover, the torques exerted on the frame by the operating forces are reduced because the distance between the needle bar 46, and the axes 49a, 49b of the cranks is reduced.

It is also conceivable to place the sliding guide such as 39 beyond the connecting-rod small ends 54a, 54b, the rod 38 also being extended in this direction in order to cooperate with the guide. The progressive movement component of the needles is then greatly increased by leverage, which makes it possible to reduce the phase shift between the two crank connecting-rod systems for a given progression stroke of the needles. This simplifies the problems of balancing which will now be discussed.

When operating without phase shift, and therefore with a linear trajectory of the needles (progression stroke CA=0), the balancing of the vertical inertial vibrations (in the direction of penetration) is optimal by placing on each crank a counterweight which is in the low position when the sliding rod 38 is at the high end of the stroke, and in the high position when the sliding rod is at the low end of the stroke. The angular position of the counterweight about the axis of each crank, calculated from the angular position of the connecting-rod big-end axis, is Asin[(E−e)/(2*(r+L))]+π. As the two crank connecting-rod systems are identical and turn in phase with each other, but in opposite directions, they are permanently symmetrical with each other relative to the transverse symmetry plane (perpendicular to a plane of FIG. 5) containing the axis 43, and thus the horizontal efforts produced by the counterweights balance each other. Such a balancing is illustrated by the counterweights 301c on the crank 48a and 301b on the crank 48b.

However, the result of a balancing carried out in this manner deteriorates when, as illustrated, the phases of the two cranks are shifted relative to each other to cause appearance of a progression component in the movement of the needles. Horizontal vibrations (parallel to the direction of progression of the fleece) appear. In order to deal with this, there is provided according to the invention to angularly displace the counterweights relative to each other in the opposite direction of the phase-shift angle φ between the connecting rod big ends, in order to bring the two counterweights closer to the situation where they are in symmetrical position relative to the transverse plane containing the axis 43. A practical solution consists of permanently displacing the counterweights in the abovementioned direction, during construction, by an angle φ equal to approximately half of the design maximum phase shift foreseen between the connecting rod big ends. Thus for example 7° if the maximum phase shift φ provided between the connecting rod big ends is 15°. (In FIG. 5, the phase shift φ shown is much greater than 15°, for illustrative purposes, and the angle δ is correspondingly increased).

Thus, when the phase shift φ is zero, the two counterweights are in asymmetrical position relative to the transverse plane, then the two counterweights move closer to the position of symmetry when the phase shift of the cranks is increased from φ=0 to φ=7°. At φ=7°, the position of symmetry of the counterweights is reached, then their asymmetry increases again up to the maximum phase shift φ.

This is the solution shown in FIG. 5, where the counterweight 301b is in “nominal” angular position and the counterweight 301a has, relative to the “nominal” position 301c, an angular displacement δ in the direction bringing it closer to the position of symmetry with the counterweight 301b relative to the axis 43.

The invention is not limited to the examples described and shown.

In the example of FIG. 1, the positioning axes 56a and 56b could be merged (distance e equal to zero). Independently or in combination, the rod 38 could be passed through by an axially elongated port through which an articulation shaft with the frame 19 could extend, so that the oscillating articulation surface is inside the sliding surfaces, instead of the reverse in FIG. 1.

The articulated link between the connecting rods 51a, 51b and the rod 38 can be placed between the sliding guide 39 and the support 44, in particular if the machine is lubricated with grease.

The example of FIG. 2 is not necessarily coupled to a linear needling apparatus 2. The rod 17 could on the contrary be directly linked to the oscillation articulation along the axis 137, and serve only to produce the penetration component of the elliptical movement.

The solutions with a differential gear according to FIG. 3 or with a clutch according to FIG. 4 are applicable to the structure according to FIG. 2, for the drive of the two crank connecting-rod systems with a chosen angular adjustment between them.

In the example shown in FIG. 5, instead of shifting only one counterweight through a certain angle δ relative to its optimum angular position in order to balance the vibrations in the direction of penetration (typically vertical direction), the two counterweights could be displaced, typically each through δ/2, so that the overall displacement between the two counterweights reaches the desired value.

In one dimensioning example, it is possible to have:

E=280 mm

e=80 mm

L=189 mm

r=25 mm

Distance B between the line 49c and the articulation axis 37=65 mm.

Distance C between the line 56c passing through the positioning axes 56a, 56b and the tip of the needles=572 mm.

Claims

1. An apparatus (3) for needling or pre-needling a fleece to be processed, comprising a movable structure (36, 136) intended to carry needles (47), and an actuating mechanism for imparting to the needles (47) an elliptical-type movement having a penetration component and a progression component, characterized in that one of the components, preferably the progression component, is at least to a large extent generated by angular oscillation of the movable structure.

2. Apparatus according to claim 1, characterized in that the elliptical-type movement of the needles takes place along a trajectory (T) comprising a proximal part (TP) directed towards the fleece and along which the progression component is in the direction (6) of progressive movement of the fleece, and a distal part (TD) along which the progression component is in the direction opposite to the direction of progression of the fleece, the proximal part (TD) being greater than the distal part (TD) when the proximal (TP) and distal (TD) parts are measured parallel to the penetration component of the movement of the needles.

3. Apparatus according to claim 1, characterized in that the movable structure (36, 136) is guided relative to a frame of the machine by a functional chain comprising a sliding in series with an articulation about an axis (37, 137) parallel to the width of the fleece of fibres.

4. Apparatus according to claim 3, characterized in that the sliding and the articulation are carried out by means arranged inside one another.

5. Apparatus according to claim 1, characterized in that the movable structure (36) is slidingly guided by a guide (39) mounted for angular oscillation.

6. Apparatus according to claim 5, characterized in that the actuating mechanism comprises two crank connecting-rod systems, each system comprising a connecting rod (51a, 51b) a small end of which (54a, 54b) is at least indirectly linked to said movable structure (36) by an articulation about a so-called positioning axis (56a, 56b) which is parallel to said oscillation axis (37).

7. Apparatus according to claim 6, characterized in that the two crank connecting-rod systems are similar and capable of a phase shift (φ), one being situated ahead of and the other behind the positioning axis (56a, 56b), relative to the direction of progression (6) of the fleece.

8. Apparatus according to claim 6, characterized in that there is an adjustable phase shift (φ) between the two crank connecting-rod systems.

9. Apparatus according to claim 8, characterized in that a differential gear (71) mounted operatively between the two crank connecting-rod systems comprises a planet gear (74a) carried by a case (78) having an adjustable fixed angular position.

10. Apparatus according to claim 8, characterized by a common motor (72) for the two crank connecting-rod systems and a clutch (401) mounted operatively between one of the crank connecting-rod systems and a drive member (73) which is common to the two crank connecting-rod systems.

11. Apparatus according to claim 7, characterized in that each crank connecting-rod system comprises a balancing counterweight (301a, 301b) associated with its crank, and in that an angular deviation between counterweight and connecting-rod big-end axis about the crank axis exhibits a difference (δ) between the two crank connecting-rod systems.

12. Apparatus according to claim 11, characterized in that the angular deviation difference (δ) is such that the two counterweights (301a, 301b) are becoming closer and closer to a state of symmetry with each other relative to a plane transverse to the path of the fleece when the phase shift (φ) is caused to increase, at least in a first range of variation starting from a zero phase shift.

13. Apparatus according to claim 6, characterized in that there is a respective positioning axis (56a, 56b) for each of the two crank connecting-rod systems.

14. Apparatus according to claim 13, characterized in that the two positioning axes (56a, 56b) have a very small centre-to-centre distance (e).

15. Apparatus according to claim 6, characterized in that two crank axes (49a, 49b) of the two crank connecting-rod systems form with the two connecting-rod-small-end axes (54a, 54b) two centre-distance lines (60a, 60b) having between them an angle (A) very different from 0° and from 180°, having a vertex preferably situated in the vicinity of the two connecting-rod small-end axes, preferably a short distance beyond said small-end axes.

16. Apparatus according to claim 6, characterized in that the two connecting rods (51a, 51b) are oriented with their connecting-rod small end (54a, 54b) pointing in a direction generally away from the plane (1) of the fleece (41).

17. Apparatus according to claim 6, characterized in that the guide (39) is placed substantially between two eccentric means (48a, 48b) turning in mutually opposite directions and each forming part of respective one of the two crank connecting-rod systems.

18. Apparatus according to claim 5, characterized in that, along a sliding direction defined by the guide (39), said guide is placed between the needles (47) on the one hand and the coupling of the movable structure (36) to the actuating mechanism on the other hand.

19. Apparatus according to claim 18, characterized in that said apparatus comprises means, forming a lubricating-oil barrier, through which the movable structure (36) passes in the vicinity of the guide (39).

20. Apparatus according to claim 3, characterized in that the movable structure (136) is articulated by said articulation to a slider (17) actuated by a first reciprocation generator, in particular a crank connecting-rod system (31, 127), generating one of the components, preferably the penetration component, and the movable structure (136) is also articulated about a positioning axis (156) to a second crank connecting-rod system (94, 98) generating said angular oscillation of the movable structure (136) about said articulation to the slider (17).

21. An apparatus for needling a non-woven material with at least one needle bar which is drivable in a reciprocating manner by at least one eccentric drive in the needle-penetration direction, which needle bar is linked to the eccentric drive via oscillating sliding rods each displaceably held in a bore of a guide, which eccentric drive consists of two parallel eccentric shafts which are drivable in opposite directions and are provided with connecting rods, with the guides being pivotably held about an axis extending parallel to the eccentric shafts, characterized in that the two eccentric shafts are provided with a different angular position and that the connecting rods of the two eccentric shafts extend in an inclined manner with respect to each other.

22. An apparatus as claimed in claim 21, characterized in that the two eccentric shafts are adjustable in their mutual angular position.