Patent Application
20070006432
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:
Other features and advantages of the invention will also emerge from the following description, which relates to non-limitative examples.
In the attached drawings:
The needling apparatus 2 according to the invention shown in
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
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 ra and rb, relationship (1) applies:
|E−e|>ra+rb (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 ra=rb=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 La and Lb, relationship (2) applies:
|E−e|<(La+Lb)−(ra+rb) (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
ra=rb=r
La=Lb=L
relationship (2) becomes (2A):
E−e<2L−2r (2A)
The combined relationships (1) and (2) produce relationship (3):
(La+Lb)−(ra+rb)>|E−e|>(ra+rb) (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
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
As a result:
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
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
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
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 (
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
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 82v driven by the servomotor 79 and a ring gear 82c 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 82v. 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
Alternatively, if the two eccentrics 48a and 48b must turn in the same direction (case of
A description follows, with reference to
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.
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
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
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
The invention is not limited to the examples described and shown.
In the example of
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
The solutions with a differential gear according to
In the example shown in
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05 06301 | Jun 2005 | FR | national |
