EP1847664A1 - Set of surfacing tools for walk behind trowel - Google Patents

Abstract

The system has a massive bar (1) and a flat rod (2) presenting an cylinder-shaped end portion (11) that is handled and fixed in a rotating rotor of a surfacing machine, where the bar is made of steel and the rod is made of aluminum. A plain plate shaped polishing wheel (4) is fixed in a removable manner using a screw or blots under the rod and the bar. The rod and the bar are connected to a mounting component (3) that is positively fixed using the screw at an horizontal upper part (60) of a receptacle (6) of a concrete surface finisher (5).

Description

The present invention relates to a set of surfacing tools for trowel.

A mechanical trowel is a machine used to smooth and smooth a surface, for example a concrete floor, to ensure flatness.

The operation is done several hours after pouring the fluid concrete, when it began to make its decision.

The invention is more specifically directed to a machine comprising at least one rotary rotor of vertical axis, integral with a set of blade-shaped tools, generally three or four in number, which extend radially to the manner of the blades of a helicopter, "star" or "cross" with respect to the axis of the rotor and which are adapted to flatten the ground.

Such machines, sometimes called for this reason "helicopters" in the art, may comprise a single rotor (see for example the document EP 1 435 420 ), two rotors arranged side by side (see for example the FR 2 370 823 and the EP 0 223 859 ), or three rotors arranged in a triangle.

As a result of the heavy wear to which they are exposed, these tools must be replaced frequently.

Professionals generally use two different types of tools, namely a finishing tool, called "smoother", and a roughing tool, called "trowel".

For some works, not requiring a perfect surface condition, especially when the floor must be subsequently covered with a coating layer, only a float is achieved.

For other works, on the contrary, we proceed to two successive operations, one of float - which corresponds to a relatively coarse planarization of the surface - and the other of smoothing; this is particularly the case when the floor must then be used then naked, possibly after having been painted.

The trowel is adapted to be secured temporarily to the trowel, the upper face of the trowel having for this purpose a flat receptacle, open on one side, and thus conformed that the smoother can be partially inserted and immobilized, so that the The constituent blade of the smoothing blade is superimposed on that of the trowel.

Thus, for the first (or only) float stage, the machine is used with the floats mounted on the smoothers.

For the second step, if necessary, remove the floats, and only use the smoothers.

The trowel is a plate made of polished steel sheet, the corners are slightly raised; its length, which corresponds to the radial direction of the rotor, is significantly larger than its width.

On a traditional mounting system, a square-section spun steel stiffening bar is permanently fixed (by riveting or welding) against the upper face of this plate, along its long axis of symmetry.

The rotor carries a number of radial arms for mounting these plates. Each radial arm has an approximately cylindrical end portion adapted to be fitted and radially fixed in said rotor. The remaining part of the arm generally has a hexagonal section, the length of which corresponds to about half the length of the trowel. It has vertical holes that can be brought into coincidence with tapped holes provided in the aforementioned bar, which allows to fix the smoother under the arm by means of screws.

The bar is slightly shorter than the length of the wiper blade. Its width is equal to the side of the hexagon corresponding to the cross section of the arm.

In addition to its rigidifying function, the bar is a spacer which allows to lower the blade of the smoother relative to the hub of the rotor, and prevent it from coming untimely support against the ground during operation.

It extends substantially over half of its length, cantilevered outwards (relative to the rotor). This bare part (not covered by the arm) has the function of retaining the trowel when it is placed on the trowel.

For this purpose, the upper face of the trowel has a flat receptacle, open on one side (like a pocket) and thus shaped that the smoother can be partially inserted and immobilized, so that the blade constituting the smoothing blade is superimposed on that of the trowel, and the trowel is provided with a flexible tab adapted to cap said bar and retaining by snap elastic (clipping).

The bare part of the bar also has tapped holes allowing it to be fastened under the arm after it has been turned 180 ° in its own plane (its external edge becoming internal, and vice versa).

In this regard, it should be noted that the blade of the trowel tends to wear more intensely on one side than the other, depending on the direction of rotation of the rotor; this inversion distributes the wear and increases the service life of the trowel.

Such a system has several disadvantages.

Firstly, the cost of manufacture of the trowel is relatively high, because it requires, in addition to cutting and stamping the plate, the machining of the bar (including the realization of threaded holes for attachment to the arm) and fixing the bar to the plate (by riveting or welding), which requires a significant labor time.

This high cost is extremely damaging because the trowel is a wear part that needs to be changed frequently.

Second, the plate component of the smoothing is improperly stiffened, because the portion of the bar which extends cantilevered outside the support arm tends to bend as a result of the significant pressure forces experienced by the tools at during work, which affects the quality of the result.

Thirdly, when using the trowel, the blocking of the trowel on the trowel is unreliable; it may be unclipped, especially in case of shock, which causes a risk of escape of the trowel at high speed, due to centrifugal force, causing damage or even bodily injury.

There are also versatile surfacing tools, supposed to perform both the float operation and the smoothing operation, subject to working in several passes.

However, this kind of tool, less efficient, is mostly used by individuals, not by professionals.

The document EP-1 382 775 relates to a mechanical trowel blade blade comprising a spacer bar interposed between a blade pad and the blade arm; the plate and the spacer bar are independent and fixed together to the blade arm by means of bolts. Thus, when the tool is worn, simply change the wafer, inexpensive manufacturing; the spreader bar can be kept and reused.

In addition, the arm and blade extend substantially the entire length of the wafer, giving the latter the necessary rigidity.

This solution therefore solves the two problems mentioned above.

However, the EP-1 382 775 , which probably concerns the mounting of a versatile type tool, does not provide the possibility of mounting a trowel on the wafer.

This solution is therefore not transferable to a system according to the invention that allows the use of two different tools, a smoothing machine or a trowel mounted on the smoothing machine.

A fortiori it does not solve the third difficulty mentioned above, namely a risk of escape of the trowel during work.

The invention aims to overcome these problems.

It relates to a set of blade-shaped surfacing tools for a mechanical trowel, which comprises at least one rotary rotor of vertical axis, integral with several sets of tools which extend radially with respect to the axis of the blade. rotor and which are adapted to flatten a floor, especially concrete, said assembly comprising at least two different tools, namely a finishing tool, called "smoothing", and a roughing tool, called "trowel", suitable for being secured to the trowel, the upper face of the trowel having a flat receptacle, open on one side, and thus shaped that the smoother can be partially inserted and immobilized, so that the blade constituting the smoothing blade is superimposed on that the trowel, said assembly also comprising a rigid arm having an end portion adapted to be fitted and radially fixed in the hub of said rotor, said trowel being a plate adapted to be fix e removably with screws or bolts under the said rigid arm.

The state of the art in this respect can be illustrated by the document US-2662,454 .

In this known embodiment, the trowel, referenced 29, is fixed under the straightener, referenced 18, by resilient snapping, by means of a mounting member consisting of a clip, referenced 37.

Such a device has a serious risk of inadvertent disconnection and escape of the trowel, in use, because of accidents, because their mutual fixation is not positively assured.

An object of the invention is precisely to avoid such a risk.

For this purpose, and in accordance with the invention, the rigid arm is secured to a mounting member adapted to be positively attached, using at least one screw, to the upper wall of said receptacle.

• ledit organe de montage consiste en une languette rigide à contour rectangulaire qui est encastrée et fixée dans un lamage creusé dans la face inférieure du bras rigide, dans sa zone médiane, et s'étendant transversalement par rapport à celui-ci, ladite languette faisant saillie sur un côté du bras ;
• la partie en saillie de l'organe de montage est adaptée pour se glisser sous la paroi supérieure du réceptacle lorsque la lisseuse est insérée dans ce dernier, cette partie en saillie présentant un trou taraudé apte à être positionné sous une ouverture, de préférence en forme de lumière, ménagée dans la paroi supérieure du réceptacle, permettant ainsi la fixation des deux éléments à l'aide d'une vis ;
• l'organe de montage est ainsi conformé qu'il peut être monté de manière réversible, de sorte sa partie en saillie soit déportée d'un côté ou de l'autre dudit bras rigide ;
• le bras rigide possède une section rectangulaire, et est ainsi conformé que l'une de ses faces latérales verticales vient en butée contre le bord libre de la paroi supérieure dudit réceptacle lorsque la lisseuse est correctement insérée dans ce dernier ;
• le bras rigide est composé de deux éléments superposés, à savoir un barreau massif de section sensiblement carrée, qui porte la portion d'extrémité apte à être emmanchée et fixée radialement dans le moyeu du rotor, et une tige plate solidaire dudit organe de montage, s'intercalant entre le barreau et la lisseuse ;
• les vis qui assurent la fixation de la lisseuse sous le bras rigide assurent également, ou contribuent à assurer, la fixation mutuelle des deux éléments constitutifs de ce dernier ;
• le barreau massif est en acier, tandis que la tige plate est en matériau léger, par exemple en aluminium ;
• les vis qui assurent la fixation de la lisseuse sous le bras rigide sont des vis à tête fraisée aptes à s'engager dans des trous à bord tronconique complémentaires ménagés dans la lisseuse de manière à ne pas dépasser en dessous du plan de la face inférieure de cette dernière, les tiges de ces vis passant dans des cheminées verticales traversant le bras et recevant à leur extrémité supérieure des écrous de fixation, de préférence à oreilles (permettant une fixation sans outil).
• le bras rigide possède une section constante, et la lisseuse a un contour sensiblement rectangulaire, dont le grand côté a une longueur légèrement supérieure à celle du bras.

Furthermore, according to a number of advantageous, but not limiting, features of the invention:

• said mounting member consists of a rigid tongue with a rectangular contour which is embedded and fixed in a countersink cut in the lower face of the rigid arm, in its central zone, and extending transversely thereto, said tongue projecting on one side of the arm;
• the projecting part of the mounting member is adapted to slide under the upper wall of the receptacle when the trowel is inserted into the latter, this protruding part having a threaded hole adapted to be positioned under an opening, preferably in the form of light, formed in the upper wall of the receptacle, thus allowing the attachment of the two elements by means of a screw;
• the mounting member is thus shaped that it can be mounted reversibly, so that its projecting portion is offset on one side or the other of said rigid arm;
• the rigid arm has a rectangular section, and is thus shaped so that one of its vertical lateral faces abuts against the free edge of the upper wall of said receptacle when the smoother is correctly inserted in the latter;
• the rigid arm is composed of two superimposed elements, namely a solid bar of substantially square section, which carries the end portion adapted to be fitted and radially fixed in the hub of the rotor, and a flat rod integral with said mounting member, interspersed between the bar and the smoother;
• the screws which secure the stretcher under the rigid arm also ensure, or help to ensure, the mutual attachment of the two components of the latter;
• the solid bar is made of steel, while the flat bar is of light material, for example aluminum;
• the screws which secure the smoothing machine under the rigid arm are countersunk screws adapted to engage in complementary frustoconical edge holes formed in the smoothing so as not to exceed below the plane of the lower face of the latter, the rods of these screws passing through vertical chimneys crossing the arm and receiving at their upper end fixing nuts, preferably with ears (allowing attachment without tools).
• the rigid arm has a constant section, and the smoother has a substantially rectangular contour, the long side has a length slightly greater than that of the arm.

• La figure 1 est une vue générale, éclatée et en perspective, d'un mode de réalisation possible de l'invention (sans les boulons ni vis de montage) ;
• La figure 2 est une vue de dessus schématique d'une lisseuse portée par le rotor d'une truelle mécanique ;
• La figure 3 est une vue de dessus schématique d'une taloche adaptable sur la lisseuse de la figure 2 ;
• La figure 4 est une vue similaire à celle de la figure 2, mais à échelle plus petite, sur laquelle sont représentées partiellement les trois autres lisseuses du jeu de quatre outils mis en oeuvre sur la machine ;
• La figure 5 est analogue aux figures 2 et 3, et montre la taloche montée sur la lisseuse ;
• Les figures 6 et 7 sont des coupes transversales selon les plans VI-VI et, respectivement, VII-VII de la figure 2 ;
• La figure 8 est une coupe transversale selon le plan VIII-VIII de la figure 5.

Other features and advantages of the invention will emerge from the description which will now be made, with reference to the appended drawings, in which:

• Figure 1 is a general view, exploded and in perspective, of a possible embodiment of the invention (without the bolts or mounting screws);
• Figure 2 is a schematic top view of a trowel carried by the rotor of a trowel;
• Figure 3 is a schematic top view of a trowel adaptable on the smoother of Figure 2;
• FIG. 4 is a view similar to that of FIG. 2, but on a smaller scale, on which are partially represented the other three smoothing machines of the set of four tools used on the machine;
• Figure 5 is similar to Figures 2 and 3, and shows the float mounted on the smoother;
• Figures 6 and 7 are cross sections along the planes VI-VI and VII-VII of Figure 2, respectively;
• FIG. 8 is a cross-section along the plane VIII-VIII of FIG.

• un bras rigide 1, 2 présentant une portion d'extrémité 11 apte à être emmanchée et fixée radialement dans le moyeu du rotor rotatif d'une truelle mécanique non représentée ;
• un organe de montage 3 pour la fixation de la taloche ;
• une lisseuse 4 en forme de plaque essentiellement plane adaptée pour être fixée de manière amovible à l'aide de boulons sous le bras rigide 1 -2 ;
• une taloche 5, comprenant également une plaque 50 essentiellement plane apte à être solidarisé temporairement de la lisseuse, sa face supérieure présentant un réceptacle plat 6, ouvert sur un côté, et ainsi conformé que la lisseuse 4 peut y être partiellement insérée, immobilisée et fixée.

The trowel face tool mounting system shown in Figure 1 includes:

• a rigid arm 1, 2 having an end portion 11 adapted to be fitted and radially fixed in the hub of the rotating rotor of a not shown trowel;
• a mounting member 3 for fixing the trowel;
• an essentially planar plate-shaped smoothing device 4 adapted to be detachably fastened with bolts under the rigid arm 1 -2;
• a trowel 5, also comprising a substantially planar plate 50 adapted to be secured temporarily to the trowel, its upper face having a flat receptacle 6, open on one side, and thus conformed that the smoother 4 can be partially inserted, immobilized and fixed .

As will be seen below, this fixing is done by means of the mounting member 3.

The rigid arm is composed of two superimposed elements, namely a solid bar 1, for example steel, which includes the end portion 11, and a flat rod 2, for example extruded aluminum, interposed between the bar 1 and the smoother 4.

The end portion 11 has a cylindrical shape of given diameter, and a standardized configuration, comprising a helical groove 111 and a transverse groove 110, which allows its mounting, in a radial orientation, in the rotor hub of a machine of the trade, hub which bears the reference 7 in Figures 2, 4 and 5.

The remainder 12 of the bar 1 has a length substantially greater than that of the portion 11, and a square section, whose side is slightly greater than the diameter of the portion 11.

The portions 11 and 12 may be made by machining, from a single piece or be manufactured independently of one another and then fixed to one another coaxially, for example by force fitting the portion 11 in an axial bore pierced in the portion 12.

The portion 12 is crossed by several vertical bores, or chimneys, 10. In the example shown there are four in number, arranged along the longitudinal axis of symmetry of the bar, and regularly spaced.

On the upper face of the portion 12 is fixed, for example by means of screws (not shown) an angle plate 13; it has a vertical and transverse wing, raised upwards, pierced by a longitudinal orifice 130.

As seen in Figure 4, this plate serves to secure the arm 1, for example by means of a screw passing through the orifice 130, to a ring 9 which connects all the arms (four in this case) of the machine, which stabilizes the tool set during operation, according to an arrangement known per se.

The flat shank 2 has the same length as the portion 12; it has a rectangular section, whose small side is arranged vertically and the long side, equal to that of the part 12, horizontally. It is traversed by four vertical holes 20 having a disposition and a diameter identical to those of the chimneys 10.

In its central zone, the lower face of the rod 2 has a transverse counterbore 22 of rectangular cross section; this zone is pierced by a vertical and central hole 21 opening into the counterbore.

A central position of the countersink is not obligatory, of course.

The respective dimensions of the bar portion 12 and the flat rod 2 are such that the latter can be positioned exactly under the part 12, the side and front edges of these two elements being then in the same plane, and the axis of each of the chimneys 10 being aligned with that of a hole 20.

Similarly, the axis of the orifice 21 is then aligned with the vertical axis of a threaded blind hole drilled in the lower face of the part, not visible in Figure 1, and referenced 120 in Figures 7 and 8 .

The mounting member 3 is a rigid rectangular tongue, for example steel, whose width and thickness respectively correspond to the width and depth of the counterbore 22; its length is equal, for example, to twice the width of the flat rod 2.

It is crossed by two holes 30, 31 of vertical axis located on its major axis of symmetry, a quarter and three quarters of its length.

Hole 30 is cylindrical and threaded.

The hole 31 is frustoconical and smooth, complementary to a milled screw head, referenced 32 in Figures 7 and 8, for fixing the tongue 3 under the arm 1-2.

It should be noted that the tongue 3, recessed in the counterbore 22, can be positioned in two different ways, offset by 180 °, so that its protruding portion projects on one or the other of the two edges. In each of these positions, the hole 31 is opposite the hole 21. Thanks to this arrangement, it is possible to adapt the mounting of the trowel to the direction of rotation of the rotor.

The smoother 4 is a plate of thin sheet (indicative, between 1 and 2 mm), rigorously flat, preferably hardened and polished steel, rectangular in shape, whose large direction extends radially (relative to the axis of the rotor). The length of this plate is a little larger than that of the 12-2 assembly.

Its corners 42 are slightly raised.

On its major axis of symmetry it is crossed by a series of four holes 40 intended to coincide with the holes 10 and 20 of the arm 1-2.

These holes have a frustoconical shape, complementary heads 81 countersunk screws 80 for securing the trowel under the arm 1-2 with wing nuts 8 (see Figure 6).

The trowel 5 comprises a plate made of sheet steel 50, of the same length as the trowel 4, but of substantially larger width. Its thickness is a little higher than that of the smoother (as an indication, between 2 and 3 mm). It has bevelled wedges, as well as slightly raised edges, as is known per se.

On one of the long sides of the trowel is fixed, by welding, a sheet metal plate folded by stamping, and thus shaped that it forms a flattened pocket 6 in which it is possible to insert and immobilize a lateral portion of the smoother.

As can be seen in FIGS. 1 and 8 in particular, this folding is such that the sheet has a horizontal lateral edge 62 by which it is welded to the trowel plate 50, an intermediate vertical recess 61, and a horizontal main part 60 spaced apart. of the plate 50 of a spacing sufficient to accommodate the smoothing machine 4 and the tongue 3.

At its ends, the portion 60 is folded down at right angles, forming vertical transverse cheeks 65. At its ends, the portion 61 is indented and has open spaces 64, which promotes the proper positioning of the smoothing machine 4 in the receptacle 6, despite its raised corners 42.

In its central zone, in the vicinity of its free edge 600, the upper horizontal wall portion 60 has a small oblong opening or light, 63, arranged transversely, whose major axis corresponds to the minor axis of symmetry of the trowel 5.

With a surfacing tool mounting system according to the invention, the user of a trowel will have to supply, at his first order, for each rotor, a kit comprising a set of arms 1-2. , tongues 3, smoothers 4 and floats 5, the number of elements of this set being for example four, since the rotor has four blades.

Then, it will have to stock up only in trimmers and trowel, which are the only wear parts and which, considering their structure are of a relatively low cost price.

Mounting a trowel on the rotor hub of a trowel is as follows.

The tongue 3 is embedded in the countersink 22 of the rod 2 so that its protruding portion projects from the right side, which depends on the direction of rotation of the rotor.

A screw 32 is inserted through the superimposed holes 31 and 21, and after correctly positioning the rod 2 against the part 12 of the bar 1, it is screwed into the threaded hole 120. The countersunk head of this screw is housed without exceeding in the conical hole 31 (see Figure 7).

The same procedure is applied for attaching the trowel 4 to the rod 2 and to the arm 1, by introducing countersunk countersunk rods through the holes 40, 20 and 10, the fixing being done this time by means of hexagon nuts. ears (or others) 8, which is screwed on the free ends protruding from these rods (see Figure 6). The countersunk head 81 of these screws 80 is housed without protruding into the conical hole 40 (see FIG. 6), and therefore does not interfere with the use

The portion 11 of the bar 1 is then fitted into the hub 7 and fixed thereon by means of conventional and standardized mounting members (not shown) fitted to the rotor of the machine.

With the aid of the ring 9, which is centered on the axis of the spring, the set of arms 1 is connected together.

This ring is optional.

For smoothing, the machine thus equipped is used.

The solid arm 1-2, which runs over almost the entire length of the trowel stiffens the stripper plate optimally, without risk of deformation of the latter.

Despite its high rigidity, this arm remains of acceptable weight, given that the inserted insert rod, which also serves as spacer element (lowering the tool) is lightweight material, for example aluminum.

After a certain period of use, we return the wiper to 180 ° (as is already done with traditional smoothers) to better distribute the wear, which is not done symmetrically, but depends the direction of rotation of the rotor; the "inverted" assembly and reassembly of the plate is particularly easy and fast, since it only requires handling the bolts 8-80 which, thanks to the wing nuts 8, can be unscrewed and screwed easily without tools.

The replacement of a permanently worn trowel is done in the same way.

To set up the trowel, it is sufficient to fit it on one half of the trowel, so that this half slips into the receptacle 6. The mutual spacing of the inner faces of the cheeks 65 corresponds to the interlocking play. near the length of the trowel, so that its short sides are perfectly guided during this setting up. Advantageously, the wall 60 is thus dimensioned and positioned at the end of nesting a lateral flank of the arm 1-2 abuts against the free edge 600 of this wall (see Figures 5 and 8), and that the trowel 5 is is then perfectly centered in relation to the arm, the hole tapped 30 of the tongue 3 being in turn above the hole 63. The fact that it has the shape of a light makes it possible to compensate for dimensional irregularities or possible deformations.

Finally, the trowel is positively secured to the trowel by means of the screw 8 'whose rod passes through the aperture 63 and is screwed into the hole 30. As it is a screw having a head-to-ear, the screwing operation can be done easily, without tools.

It is the same when you want to unscrew this screw to remove the trowel.

The positive fixing, by bolting, of the trowel with the trowel, eliminates the risk of accidental and dangerous escape of the trowel, that one meets with the conventional locking systems, with elastic tab of clipping.

This attachment could be achieved by means of more than one screw or bolt, and / or associated with an additional or complementary fastening means.

The important thing is that the attachment is positive (and not detachable unexpectedly) and that the assembly and disassembly of the trowel can be performed both quickly and conveniently.

Claims (10)

A trowel-shaped planing tool assembly for a trowel, which comprises at least one rotatable rotor (7) of vertical axis, secured to a plurality of tool sets which extend radially with respect to the axis of the rotor and which are adapted to flatten a floor, especially of concrete, said assembly comprising at least two different tools, namely a finishing tool, called "smoothing" (4), the upper face of the trowel (5) having a flat receptacle ( 6), open on one side, and thus conformed that the smoother can be partially inserted and immobilized, so that the blade constituting the smoothing blade (4) is superimposed on that of the trowel (5), said assembly comprising also a rigid arm (1-2) having an end portion (11) adapted to be fitted and radially fixed in the hub of said rotor (7), said smoothing (4) being a plate adapted to be removably attached to using screws or bolts (8-80) under said rigid arm (1-2), characterized in that the rigid arm (1-2) is integral with a mounting member (3) adapted to be positively fixed, with the aid of at least one screw (8 ') at the upper wall (60) of said receptacle (6). Assembly according to claim 1, characterized in that said mounting member (3) consists of a rigid tongue with a rectangular contour which is embedded and fixed in a recess (22) hollowed in the underside of the rigid arm (1-2) in its median zone and extending transversely thereto, said tongue projecting from one side of the arm. An assembly according to claim 2, characterized in that the projecting portion of said mounting member (3) is adapted to slide under the upper wall (60) of said receptacle (6), when the smoother is inserted in the latter, this projecting part having a tapped hole (30) adapted to be positioned under an opening (63), preferably in the form of a light, formed in the upper wall (60) of the receptacle (6), thus allowing the attachment of the two elements ( 3-6) using a screw (8 '). Assembly according to Claim 2 or 3, characterized in that the mounting member (3) is thus shaped so that it can be mounted reversibly, so that its projecting part is offset on one side or on the other. other of said rigid arm (1-2). Assembly according to one of claims 1 to 4, characterized in that said rigid arm (1-2) has a rectangular section, and is thus in that one of its vertical lateral faces abuts against the free edge of the upper wall (60) of said receptacle (6), when the smoother is correctly inserted in the latter. Assembly according to claim 5, characterized in that said rigid arm is composed of two superimposed elements, namely a massive bar (1) of substantially square section, which carries said end portion (11) adapted to be fitted and fixed radially in the hub of said rotor (7), and a flat rod (2), integral with said mounting member (3), and interposed between the bar (1) and the smoothing (4). Assembly according to Claim 6, characterized in that the screws (80) which secure the straightener (4) under the rigid arm also ensure or contribute to the mutual fixing of the two constituent elements (1, 2). of the last. Assembly according to claim 6 or 7, characterized in that said solid bar (1) is made of steel, whereas said flat rod (2) is of light material, for example aluminum. Assembly according to one of claims 6 to 8, characterized in that the screws (80) which secure the stripper (4) under the rigid arm are countersunk screws (81) adapted to engage in holes (40) complementary frustoconical edge formed in the straightener (4) so as not to exceed below the plane of the lower face of the latter, the rods of these screws passing through vertical chimneys (10-20) passing through said arm (1-2), and receiving at their upper end fastening nuts (8), preferably with ears. Assembly according to one of claims 1 to 9, characterized in that said rigid arm (1-2) has a constant section, and that the smoother (4) has a substantially rectangular contour, whose long side has a slightly length greater than that of the arm.

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