Abstract:
A multifunctional rotary cutting head is provided for cutting devices as well as portable devices equipped with such a cutting head. The cutting head comprises a rotary housing that has at least a top part and a bottom part and accommodates a support for one or more cutting elements or tools. The support is penetrated by an axial drive shaft on which the support is mounted. The support for the cutting element(s)or tool(s) has two leads to selectively mounting the cutting element(s) or tool(s), i.e. a first level designed to mount strands of cutting wire and a second level designed to mount an interchangeable cutting blade.

Description:
CROSS-REFERENCE TO RELATED U.S. APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       NAMES OF PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    Not applicable. 
       REFERENCE TO AN SUBMITTED ON COMPACT DISC Not applicable. 
     BACKGROUND OF THE. INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present invention concerns a multifunctional rotary cutting head. It is more specifically intended for equipping portable cutting tools such as edge-trimmers, also called grass cutters or grass trimmers, brush cutters, motorized grass mowers, grass-trimmers or the like. 
         [0006]    2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98 
         [0007]    Generally, it is customary to classify under the name of edge-cutter or grass-cutter all devices whose function it is to cut lawns or grasses with low resistance. The cutting heads used for this purpose are generally of the type where the cutting elements are constituted by lengths of flexible wires of plastic material, for example of ‘Nylon’ yarn. On the other hand, the devices that are used for cutting vegetation already lignified (small brush, tree or shrub shoots, tall grasses, hedges, . . . ) are more often called brush-cutters, hedge-trimmers, and their cutting head uses rotary metallic or hard plastic blades. By the way of examples documents US-2001/0023542, U.S. Pat. No. 6,401,344, U.S. Pat. No. 6,944,956, WO-2004/064489, WO-2005/032237, WO-2006/017372, WO-2008/139246, FR-2888085 are cited which describe various possible layouts of cutting heads using cutting elements constituted by lengths of flexible cutting wires. Examples of cutting heads using metallic cutting wires are for instance described in document WO-2007/099443. 
         [0008]    These cutting heads are mounted at the distal end of a handle equipped with a U-shaped grip or a dual guide and control handle for the motor ensuring the rotational drive of said cutting heads, as well as with a ring for fastening a carrying harness. 
         [0009]    The portable cutting devices currently available on the market are either designed for use of only one type of cutting tool, or, for the sake of being multifunctional, certain machines provide for each of these types of elements a specific interchangeable head: one for wire, one for a metal blade, etc. 
         [0010]    If one wants to go from one type to the other, it is necessary to remove all or a portion of the support of the one to replace it by all or part of the support of the other. These two types of support require a removal and the use of one or several tools. This situation has additional disadvantages:
       The need for training the user in the removal (often left-hand thread)/disassembly and re-assembly of the cutting tool supports, requiring the use of cutting tools one always has to keep within reach.   Loss of time and risk of injury; loss of parts during removal and re-assembly.       
 
         [0013]    It happens frequently that because of the location of the surfaces on which shearing or brush clearing needs to be performed, the users need to acquire one wire device for cutting soft grasses (for example, surfaces around trees or near hard obstacles such as edges of walls, terraces or bodies of masonry, etc.) and a blade device for the clearing of brush in high and bard grasses, or in ligneous plantings (brambles, ferns, . . . ) or in brush, or for the cutting of hedges or the thinning out of shrubby trees. It is clear that such a situation results in increased expenses for acquisition and initiation of the cutting materials. 
         [0014]    To remedy the disadvantages of the devices of the aforementioned kind which are meant for specific cutting jobs, in document WO-2007/099443, a tool iota shrub slasher with dual action has been proposed for combined cutting of grass and brush this tool consisting of a rectangular blade with a center hole for connection to a rotary head of a landscape brush rake and of suitable materials which are provided with a pair of cylindrical through-holes for the insertion of small lengths of Nylon or another durable plastic material. This tool allows simultaneous cutting of grass and brush, while avoiding the operations of attaching and detaching the blade, while also achieving efficient disintegration of the grass and brush. 
         [0015]    This tool is not versatile in so far as, even if it allows simultaneous cutting of grass and small woody plants in order to proceed with the fragmentation of the cut materials, it is not suitable for mounting on an edge-trimmer or grass cutter that has to be used in proximity to bard obstacles. 
       BRIEF SUMMARY OF THE INVENTION 
       [0016]    One aim of the invention is to remedy the previously noted disadvantages of portable cutting devices of the edge-trimming or brush-slashing kind. 
         [0017]    According to the described example, the cutting head according to the invention is in particular remarkable in that it comprises a rotating housing constituted by at least two parts, namely an upper part and a tower part attached to the base of said upper part, and in which is housed, with an aptitude of axial translation of limited amplitude, a support of cutting element(s) or tool(s) through which passes an axial drive shaft integral in rotation of said support and the upper part of which is fitted to permit its coupling to the motor of a portable cutting device, said support of cutting element(s) or tool(s) being mounted with a possibility of axial movement of limited amplitude on said axial drive shaft, said support of cutting element(s) or tool(s) being provided with two levels for the selective mounting of the latter, namely:
       a first level fitted for the mounting of pieces of cutting wire, and,   a second level fitted for the mounting of an interchangeable cutting blade.       
 
         [0020]    According to a preferred method of production, said support of cutting element(s) or tool(s) is provided with two levels for the selective mounting of the latter, namely:
       a first upper level fitted for the mounting of pieces of cutting wire, and,   a second lower level fitted for the mounting of an interchangeable cutting blade.       
 
         [0023]    The cutting head comprises means for blocking or disconnecting of the selected cutting element(s) shaped so that the simultaneous application of relative axial movements in opposite direction to said exterior housing and to said support of cutting element(s) or tool(s) results in:—either the placement of the level corresponding to the selected type of cutting element(s) in a position allowing the positioning or the withdrawal of said element;—or the blocking of the latter on the level of said support corresponding to the chosen type of cutting element. 
         [0024]    According to a preferred and advantageous method of production, the exterior housing and the support of elements or cutting tool are fitted so that the simultaneous application of axial movement(s) convergent to said housing and to said support located inside the latter is used to allow the placement of the level corresponding to the selected type of cutting element in a position allowing the positioning or withdrawal of said cutting tool(s), whereas the simultaneous application of axial movements divergent to said housing and said support allows the automatic blocking of said cutting elements on the level of the support corresponding to the selected type of cutting elements. 
         [0025]    According to another characteristic disposition, the convergent relative axial movements of the exterior housing and of support of cutting element(s) or tool(s) are obtained automatically under the action of an elastic return device, so as to allow automatic blockage of the cutting elements after their positioning in the cutting head. 
         [0026]    According to a preferred method of production, the elastic return device consists of a spring acting in compression and interposed between an interior partitioning of the exterior housing and the interior support of cutting element(s) or tool(s). 
         [0027]    According to another characteristic disposition, the upper level of the support of cutting element(s) or tool(s) includes a fastening mechanism of the cutting wires engaged inside the exterior housing of the cutting head, through orifices made in the side wall of the housing, integral in rotation of said support of the fastening mechanism, features clamping cams mounted with an aptitude for swiveling in the parallel planes between them and to the axis of rotation of the cutting head, this support of cutting elements or tools is mounted with an aptitude of axial translation of limited amplitude in the exterior housing of the cutting head, the latter and the fastening mechanism being fitted in a complementary fashion, so that the simultaneous application of axial movements convergent to said housing and to said support is used to allow raising the clamping cams so as to permit the introduction, the sliding or the positioning of the cutting wires inside the cutting head, whereas the simultaneous application of axial movements divergent to said housing and said support permits lowering said cams in order to achieve the blockage in active position of the cutting wires in the cutting head. 
         [0028]    According to another characteristic disposition, the fastening mechanism comprises two guiding and positioning channels of the lengths of cutting wire, located in parallel on both sides of the rotational axis of the cutting head facing the openings of the exterior housing, an entrance portion of each of these channels is uncovered and a pivoting cam is raised opposite this uncovered portion, this cam being subject to the action of a spring tending to apply its clamping surface in the direction of said uncovered portion, so as to strongly press the cutting wire engaged in the positioning channel against the bottom of the latter, thereby ensuring the blockage of said cutting wire, the housing is equipped on the inside with thrust fingers integral with an tipper partitioning of said housing and allowing to push back and pivot the cam in order to remove the pressure of the cam from the cutting wire when the exterior housing and the support of the fastening mechanism are subjected to forces of convergent pressure tending to bring closer together the upper partitioning of said exterior housing and the upper face of the support of the fastening mechanism. 
         [0029]    According to another characteristic disposition, the cutting blade is inserted in a removable manner between the upper and lower parts of the housing. According to the interesting embodiment shown:
       the lower level of the support of cutting elements or tools is constituted by a blade support, this blade support and the cutting blade being provided with complementary means of positioning and coupling in rotation of the latter, these means can be disengaged from their active position by simultaneous manual application, on said housing and said blade support, of convergent relative axial movements;   complementary means ensure the axial blockage of the cutting blade on the distal portion of the drive shaft;   a coupling device provides an automatic rotational connection of the blade support and of the blade when a blade is positioned on said blade support.       
 
         [0033]    According to another characteristic disposition, the central part of the blade features:
       on the one hand, a central opening for the passage of the drive shaft, two coupling orifices placed on both ends of said central shaft, two openings presenting a curved exterior side; and   on the other hand, solid parts which allow the driving in of the blade on the distal part of the rotation shaft, up to its locking position.       
 
         [0036]    According to an another advantageous embodiment, the blade support and the central part of the blade are fitted so as to permit the installation of said blade on said blade support by a convergent relative axial movement of these, followed by a rotational movement of the blade; the removal of the blade is done by reverse movements. 
         [0037]    According to another embodiment, the means of positioning and coupling of the cutting blade to the blade support include, on the one hand, two coupling studs placed on the underside of said blade support, on both sides of the axial opening made in the latter, and, on the other hand, two orifices made on either side of the axial opening of the blade in which the distal portion of the drive shaft is engaged. 
         [0038]    According to another preferred embodiment, the rotation coupling of the lower blade support and the exterior housing is made by drive pins integral with the inside face of an upper partition of the housing and oriented parallel to the rotational axis of the cutting head, towards the inside of the latter, these drive pins being engaged with an aptitude of sliding in grooves made in the blade support. 
         [0039]    According to another embodiment, the coupling grooves are made in at least opposite sides of the blade support. 
         [0040]    According to another characteristic disposition, the drive shaft traverses an axial passage made in the blade support, and the traversing portion of the shaft and said axial passage present a complementary profile suitable for the rotational drive of said support. 
         [0041]    According to a preferred method of production, said cutting head features means to limit the amplitude of the axial translation of the blade support on the traversing portion of the drive shaft. 
         [0042]    According to another characteristic disposition, the cutting head includes restraint fixtures of the blade support on the drive shaft. 
         [0043]    According to a preferred embodiment, the axial restraining fixtures of the cutting blade on the drive shaft comprise, on the one hand, an axial opening on the cutting blade, and, on the other hand, a ring-shaped groove featured on the distal portion of the drive shaft, at the distance of its end, the end portion of said drive shaft presenting, from said groove on, a circular shape with two longitudinal, diametrically opposed female grooves, whereas the axial opening of the cutting blade presents a male shape identical to that of the profile of said end portion. 
         [0044]    According to another characteristic disposition, the lower edge of the upper part of the housing and the cutting blade are provided with complementary means of positioning. 
         [0045]    According to a preferred embodiment, the complementary means of positioning of the housing and of the cutting blade include, on the one hand, two openings delineated by an external arched edge and located on either side and at equal distance of the diametrical alignment of openings on the blade, and, on the other hand, diametrically opposed guide and stop cleats on the base of said upper part; at least one of the ends of said openings extends itself by a notch. 
         [0046]    According to another characteristic disposition, the lower part of the side wall of the housing and the circular upper part of the sliding bowl are provided with complementary retaining fixtures the assembly of which requires only a relative axial movement of the two parts, followed by a rotational movement of limited amplitude, enabling the engagement of the complementary elements of said retaining fixtures. 
         [0047]    According to another characteristic disposition, the retaining fixtures of the housing and the bowl include, on the one hand, in the vicinity of and along the circular lower edge of the inside surface of the cylindrical sidewall of the housing, at least two diametrically opposed rounded shoulders, and, on the other hand, at least two diametrically opposed lock stops extending parallel to the axis of the sliding bowl and the free end of which is provided with a locking peg or lug oriented in direction of this axis. 
         [0048]    Preferably, the cutting head comprises a stop located at one of the ends of each shoulder, limiting the rotational movement of the locking pegs or lugs during the placement of the sliding bowl in the engagement position. 
         [0049]    According to an advantageous disposition, the edge of the pea and the rounded shoulder of the pegs are provided with complementary locking means at the end of the rotational movement when the housing parts are engaged. 
         [0050]    According to a preferred embodiment, the complementary locking means of the lower part on the upper part of the housing are constituted by a stud on the upper face of the shoulders and by a notch provided in the outside edge of the peg in which said locking stud engages automatically at the end of the rotational movement of engagement. 
         [0051]    The portable cutting device according to the invention, such as grass-cutter, or edge cutter, or shrub slasher, or motorized lawn mower, or hedge trimmer . . . is remarkable and advantageous in that it is equipped with a rotary cutting head using flexible lengths of cutting wire or cutting blades featuring the aforementioned characteristics, depending on the work to be performed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0052]    The above aims, characteristics and advantages and still others will become more evident in the following detailed description and attached drawings in which: 
           [0053]      FIG. 1A  is a perspective view of a cutting head according to the invention, provided with lengths of flexible cutting wires and which can be equipped with a cutting blade. 
           [0054]      FIG. 1B  is a perspective view of a cutting head according to the invention, provided with a cutting blade and which can be equipped with lengths of flexible cutting wires. 
           [0055]      FIG. 2  is a perspective view of a cutting head provided with an interchangeable cutting blade, according to the invention, with the sliding bowl removed. 
           [0056]      FIG. 3A  is a front view of the cutting head provided with lengths of cutting wire, in unlocked position. 
           [0057]    FIG.  3 Ab is a front view of the cutting head provided with a cutting blade, in locked position. 
           [0058]    FIG.  3 Ba is a cross-section along line Ea-Ea of FIG.  3 Aa. 
           [0059]    FIG.  3 Bb is a cross-section along line Eb-Eb of FIG.  3 Ab. 
           [0060]    FIG.  3 Ca is a cross-section along line La-La of FIG.  3 Ba. 
           [0061]    FIG.  3 Cb is a cross-section along line Lb-Lb of FIG.  3 Bb. 
           [0062]    FIG.  3 Da is a cross-section along line Ka-Ka of FIG.  3 Ba. 
           [0063]    FIG.  3 Db is a cross-section along line Kb-Kb of FIG.  3 Bb. 
           [0064]      FIG. 3E  is a bottom view and cross-section along line R-R of FIG.  3 Ba unlocked position). 
           [0065]    FIGS.  3 Aa to  3 F illustrate a phase of positioning of the lengths of cutting wire in the housing, according to which the fastening mechanism constituting the upper level of the mobile support of cutting element or tool is displaced in the high position, allowing the retraction of the clamping cams and the insertion of the wires into said mechanism. 
           [0066]      FIG. 4A  is a perspective view showing the first phase of positioning, manually, a metal blade on or against the lower face of the upper part of the exterior housing. 
           [0067]      FIG. 4B  is a bottom view of  FIG. 4A , after retraction of the cutting blade and the sliding bowl. 
           [0068]      FIG. 4C  is an exterior exploded view of  FIG. 4A  without the sliding bowl. 
           [0069]      FIG. 5A  is a bottom view and cross-section along line E-E of  FIG. 5B . 
           [0070]      FIG. 5B  is a cross-section along line D-D of  FIG. 4C . 
           [0071]      FIG. 5C  is a detail view according to reference mark F of  FIG. 5B . 
           [0072]      FIG. 6A  is a perspective view analog to  FIG. 3A  showing the second phase of positioning of the metal blade. 
           [0073]      FIG. 6B  is a bottom view of  FIG. 6A  without the sliding bowl. 
           [0074]      FIG. 6C  is an exterior view of  FIG. 6A  without the sliding bowl. 
           [0075]      FIG. 7A  is a cross-section along line EE of  FIG. 6C . 
           [0076]      FIG. 7B  is a cross-section along line D-D of  FIG. 6C . 
           [0077]      FIG. 7C  is a detail view according to reference mark F of  FIG. 7B . 
           [0078]      FIG. 8A  is a perspective view showing the third phase of the positioning of the metal blade. 
           [0079]      FIG. 8B  is a bottom view of  FIG. 8A , the sliding bowl being removed. 
           [0080]      FIG. 8C  is an exterior view of  FIG. 8A  without the sliding bowl. 
           [0081]      FIG. 9A  is a cross-section along line E-E of  FIG. 9B . 
           [0082]      FIG. 9B  is a cross-section along line D-D of  FIG. 8C . 
           [0083]      FIG. 9C  is a detail view according to reference mark F of  FIG. 9B . 
           [0084]      FIG. 10A  is a perspective view showing the fourth phase of the positioning of the metal blade, in locked position. 
           [0085]      FIG. 10B  is a bottom view of FIG  10 A. 
           [0086]      FIG. 10C  is an exterior view of  FIG. 10A  without the sliding bowl. 
           [0087]      FIG. 11A  is a cross-section along line E-E of  FIG. 11B . 
           [0088]      FIG. 11B  is a cross-section along line D-D of  FIG. 10C . 
           [0089]      FIG. 11C  is a detail view according to reference mark F of  FIG. 11B . 
           [0090]      FIG. 12A  is a front view showing a cutting head equipped with lengths of wire in locked position with the sliding bowl in unlocked position. 
           [0091]      FIG. 12B  is a front view showing a cutting head equipped with a metal blade in locked position. 
           [0092]      FIG. 13A  is a cross-section along line M-M of  FIG. 12A  with the sliding bowl in unlocked position. 
           [0093]      FIG. 13B  is a cross-section along line M-M of  FIG. 12B  with the sliding bowl in locked position. 
           [0094]      FIG. 14A  is a cross-section along line N-N of  FIG. 13A . 
           [0095]      FIG. 14B  is a cross-section along line N-N of  FIG. 13B . 
           [0096]      FIG. 15A  is a cross-section along line M-M of  FIG. 12A  with the sliding bowl in unlocked position. 
           [0097]      FIG. 15B  is a cross-section along line M-M of  FIG. 12B  with the sliding bowl in looked position. 
           [0098]      FIG. 16A  is a cross-section along line N-N of  FIG. 15A . 
           [0099]      FIG. 16B  is a cross-section along line N-N of  FIG. 15B . 
           [0100]      FIG. 17  is a perspective view of a grass-cutter equipped with a cutting head using a metal blade according to the invention. 
       
    
    
       [0101]    Reference is made to these drawings to describe interesting, although by no means limiting, examples of production of the multifunctional cutting head according to the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0102]    In the following disclosure and the claims, in order to facilitate the description of the invention, words such as high. “low”, “upper”, “lower”, “lateral”, “upper level”, “lower level” . . . are used in reference to a position of the cutting head in operation, when the axis of said cutting head is oriented vertically. Hence, these words and terms do not have any restrictive character. 
         [0103]    The cutting head  1  comprises a rotating housing constituted by at least two parts  1 A and  1 B, or an upper part  1 A and a lower part  1 B assembled at the base of said upper part, and in which is housed, with an aptitude of axial translation of limited amplitude, a support  2  of cutting element(s) ( FIGS. 1A and 1B ) or tool(s)  3 , 5 , traversed by an axial drive shaft  6  integral in rotation of said support  2  and whose upper part is fitted so as to permit its coupling to the motor of a portable cutting device, said support of cutting element(s) or tool(s) being mounted with a capability of axial movement of limited amplitude on said axial drive shaft  6 , said support of cutting element(s) or tool(s) being provided with two levels for the selective mounting of the latter, namely:
       a first upper level fitted for the mounting of lengths of cutting wire  3  (Fig. Aa to  3 F), and   a second lower level fitted for the removable mounting of an interchangeable cutting blade  5  ( FIG. 4A to 10C ).       
 
         [0106]    The cutting head comprises blocking or disconnecting means of the selected cutting element(s)  3  or  5  shaped so that the simultaneous application of a relative axial movement in the opposite direction to the exterior housing  1 A and to said support of cutting elements or tool  2 , results in:
       either the placement of the level corresponding to the cutting element  3  or  5  in a position enabling the positioning or the retraction of said element,   or the blockage of the latter on the level of said support corresponding to the type of cutting elements selected.       
 
         [0109]    According to this example of production, the exterior housing  1 A and the support  2  of cutting elements or tools are fitted so that the simultaneous application of axial movements convergent to said housing and to said support located inside the latter, is used to allow the placement of the level corresponding to the selected cutting element  3 ,  5 , in a position allowing the positioning or retraction of said cutting element, whereas the simultaneous application of axial movements divergent from said housing and said support allows automatic blockage on the level of the support corresponding to the selected type of cutting element. 
         [0110]    The convergent relative axial movements of the exterior housing  1 A and of the support  2  of cutting element(s) or tool(s)  3 ,  5 , are obtained automatically by the action of an elastic return device  7 , so as to permit automatic blockage of the cutting elements or tools after their positioning in the cutting head. 
         [0111]    The elastic return device is constituted by a spring  7  acting under compression and interposed between an interior partition  4  of the outside housing and the interior support of cutting element(s)  2  or tools  3 ,  5 . 
         [0112]    Below is described a possible, non-limiting example of layout of the upper level of the support of cutting elements ( 2 ), which has been the subject of a separate patent application submitted on the same day by the applicant. 
         [0113]    The upper level of the support of cutting element(s) or tools comprises a fastening mechanism for the lengths of cutting wire engaged inside the exterior housing  1 A of the cutting head, through orifices  1 C made in its sidewall  1 D, integral in rotation of said fastening mechanism features clamping cams  9  mounted with an aptitude for swiveling in the parallel planes between them and to the axis of rotation of the cutting head, this support of cutting elements or tools is mounted with an aptitude of axial translation of limited amplitude in the exterior housing of the cutting head, the latter  1 A and the support  2  of the fastening mechanism being fitted in a complementary fashion, so that the simultaneous application of axial movements (Arrows F 1 , FIG.  3 Ba) convergent to said housing and to said support is used to allow raising the clamping cams so as to permit the introduction, the sliding or the positioning of the cutting wires  3  inside the cutting head, whereas the simultaneous application of axial movements (Arrow F 2 , FIG.  3 Bb) divergent to said housing and said support permits lowering said cams in order to achieve the blockage in active position of the cutting wires in the cutting head. 
         [0114]    The fastening mechanism comprises two guiding and positioning channels  2 H of the lengths of cutting wire  3 , located in parallel on both sides of the rotational axis  6  of the cutting head facing the openings  1 C of the exterior housing, an entrance portion of each of these channels is uncovered and a pivoting cam  9  is raised opposite this uncovered portion, this cam being subject to the action of a spring  10  tending to apply its clamping surface in the direction of said uncovered portion, so as to strongly press the cutting wire engaged in the positioning channel against the bottom of the latter, thereby ensuring the blockage of said cutting wire. The housing is equipped on the inside with thrust fingers  12  integral with an upper partitioning  4  of said housing and allowing to push back and pivot the cam in order to remove the pressure of the cam from the cutting wire  3  when the exterior housing and the support of the fastening mechanism are subjected to forces of convergent pressure tending to bring closer together the upper partitioning  4  of said exterior housing and the upper face of the support of the fastening mechanism. 
         [0115]    Below is described a possible, non-limiting example of layout of the lower level of the cutting head permitting the mounting of an interchangeable cutting blade  5 , this layout having been the subject of separate Patent application submitted on the same day by the applicant. 
         [0116]    According to this embodiment, the cutting blade  5  is inserted between the upper part  1 A and the lower part  1 B of the housing. 
         [0117]    More precisely:
       the lower level of the support of cutting elements or tool  5  is constituted by a blade support  2 , this blade support and the cutting blade  5  being provided with complementary means of positioning and coupling in rotation latter, these means being able to be disconnected, from their active position through the simultaneous manual application to said housing and to said blade support, of convergent relative axial movements;   the central part of the blade features:
           on the one hand, a central opening  5 B for the passage of the drive shaft  6 , two coupling orifices  5 F located on either side of the central opening, two openings  13  presenting a curved outer edge  13 A and   on the other hand, solid portions  5 E enabling the driving in of the blade on the distal part of the rotation shaft, up to its locking position.   
               
 
         [0122]    The blade support and the central part of the blade  5  are fitted so as to allow the installation of said blade on said blade support  2  through a convergent relative axial movement of the latter, followed by a rotational movement of the blade; the removal of the blade is done by reverse movements. 
         [0123]    The means for positioning and coupling of the cutting blade to the blade support comprise, on the one hand, two coupling studs  14  placed on the underside of said blade support, on both sides of the lower opening of the axial passage  24  made in the latter, and on the other hand, two orifices  5 F on either side of the axial opening  5 B of the blade in which the distal portion  6 A of the drive shaft  6  is engaged. 
         [0124]    According to another preferred embodiment, the rotational coupling of the interior blade support  2  and of the exterior housing  1 A is achieved by means of drive pins  11  integral with the internal face of an upper partition  4  of the housing and oriented parallel to the rotational axis of the cutting head, towards the interior of the latter, these drive pins  11  being engaged with an aptitude for sliding in the grooves R made in the blade support. 
         [0125]    The coupling grooves R are made in at least two opposite sides of the blade support. 
         [0126]    According to another disposition, the drive shaft  6  traverses an axial passage  24  made in the blade support  2 , and the traversing portion of the shaft and said axial passage present a complementary profile  2 C,  6 D adapted to allow the rotational drive of said support  2 . 
         [0127]    According to a preferred embodiment, said cutting head features means to limit the amplitude of axial translation of the blade support  5  on the traversing portion of the drive shaft  6 . These means comprise, for example, two circlips  17  engaged in annular grooves  6 C provided on the drive shaft  6 . The cutting head includes means for blocking the blade support on the drive shaft. 
         [0128]    According to a preferred embodiment, the means which allow the axial locking of the cutting blade  5  on the drive shaft  6  include, on the one hand, an axial opening  5 B on the cutting blade and, on the other hand, an annular groove  6 C on the distal portion  6 A of the drive shaft, at the distance of its end, the end portion of said drive shall presenting from said groove on, a circular shape with two female, diametrically opposed longitudinal grooves  6 D, whereas the axial opening  5 D of the cutting blade presents a male shape  5 C identical to that of the profile of said end portion. 
         [0129]    According to another disposition, the lower edge  21  of the upper part  1 A of the housing and the cutting blade  5  are provided with complementary positioning means  13 - 33 . 
         [0130]    The complementary means of positioning of the housing  1  and of the cutting blade  5  include, on the one hand, two openings delineated by an external arched edge  13 A and located on either side and at equal distance of the diametrical alignment of openings  5 F on the blade  5 , and, on the other hand, diametrically opposed guide and stop cleats  33  provided at the base of the upper part  4  of the housing. 
         [0131]    According to another characteristic disposition of the invention, the part of the lateral wall  1 D of the housing and the upper circular part of the sliding bowl are provided with complementary restraining fixtures  15 ,  16 , the assembly of which requires only a relative axial movement of the two parts, followed by a rotational movement of limited amplitude, allowing the engagement of the complementary elements of said retaining fixtures. 
         [0132]    According to another disposition, the restraining fixtures of housing  1 A and of the bowl  1 B comprise, on the one hand, in the vicinity of and along the circular lower edge of the internal surface of the cylindrical sidewall  1 D of the housing, at least two diametrically opposed rounded shoulders  16 , and, on the other hand, at least two diametrically opposed lock stops  15  extending parallel to the axis of the sliding bowl and the free end of which is provided with a locking peg or lug  15 A oriented in direction of this axis. 
         [0133]    Preferably, the cutting head includes a stop  16 A located at one of the ends of each shoulder  16 , limiting the rotational movement of the locking pegs or lugs  15 A during the placement of the sliding bowl in the engagement position. 
         [0134]    According to another advantageous disposition, the edge of the peg  15  and the rounded shoulder of the pegs  16  are provided with complementary locking means at the end of the rotational movement when the housing parts are engaged. 
         [0135]    According to a preferred embodiment, the complementary locking means of the lower part on the upper part of the housing are constituted by a stud  17  on the upper face of the shoulders  16  and by a notch  18  provided in the outside edge  15 A of the peg in which said locking stud engages automatically at the end of the rotational movement of engagement. 
         [0136]    The mounting and removal of an interchangeable mobile blade  5  on a cutting head is easily understood after the preceding disclosure, while considering the mounting of a cutting blade on a cutting head:
       the sliding bowl  1 B is removed by a rotational movement, in order to disconnect the shoulders  16  and the locking tabs  15 ; the external hemispherical face featuring two diametrically opposed indentations  28  facilitate this manipulation;   the blade  5  is placed on the end of the drive shaft  3  (only one position is possible because of the complementary profile of said end and of the axial opening  5 B of the blade  5 ) in this position the cutting blade rests on the studs  14  of the blade support  2 ;   a movement of convergent approach is imparted on the blade support  5  and the exterior housing  1 , by exerting moderate manual pressure on the cutting blade  5  which rests on the drive studs  14  of the blade support, until said blade  5  reaches the level of the groove  6 C; one observes that the drive studs  14  of the blade support  2  find themselves pushed against the full sections SE of the blade and distant at 90° from the coupling orifices  5 F. In practice this convergent approach movement achieved by pushing on the blade  5 , has the effect of displacing the blade support  2 , against the opposing action of spring  7 .   a rotational movement in the order of 90° is imparted on the blade. During this action the blade is guided by arched openings  13  in which slide the centering stop cleats  33 , integral with the base of the exterior housing  1 A. At the end of this rotational movement:
           on the one hand, the male elements or lobes protruding in the axial opening  5 B of the cutting blade  5  find themselves engaged between the walls of the annular groove  6 C of the drive shaft  6 , whereas   on the other hand, the coupling studs  14  penetrate automatically, under the action of the spring  7 , into the coupling orifices  5 F, the blade support  2  moves axially along the drive shaft  6  under the action of the compression spring  7  until it hits against the retaining circlip  20  of said drive shaft.   
               
 
         [0143]    To facilitate maintaining the blade support  2  in a fixed position during this rotation of the blade  5 , said blade support  2  is equipped on its upper surface, with two tenons  29  which, during the upward movement of said blade support engage in two holes  30  in the upper partitioning  4  of the exterior housing to engage in the orifices  31  made in the fixed support  32  of the cutting head  1  serving as housing for motor  37 , whereby rotation of said blade support  2  during this operation is avoided. 
         [0144]    The sliding bowl  1 B is put back in place by an axial movement, followed by a rotation of said sliding bowl  1 B in relation to the exterior housing  1 . 
         [0145]    To perform retraction of the blade  5 :
       the sliding bowl  1 B must be removed, then one must push on the coupling studs  14  of the blade support  2  in order to withdraw the from the orifices  5 F of the blade and perform rotation of said blade of about 90°.       
 
         [0147]    The drive studs find themselves again under the cutting blade  5  and the lobes  5 A opposite the complementary profile of the drive shaft  6  which allows the cutting blade  5  to move in direction of the distal part of the drive shaft  6  until it disengages from said drive shaft under the action of the blade support  2  on which acts the compression spring  7 . 
         [0148]    The invention concerns also portable cutting devices such as grass-cutters, edge-trimmers, shrub slashers, hedge-trimmers, equipped or likely to be equipped with a cutting head featuring the previously described characteristics. 
         [0149]    Such devices, an example of which is shown in its entirety by reference  35  in  FIG. 17 , generally feature: a handle  36  supporting at its distal end the cutting head  1  ( 1 A,  1 B,  1 C), a motorization  37  installed at the lower part or at the upper part of the handle for the rotational drive of the cutting head, a U-grip or a guiding double grip  38  for control of this motorization, a ring  39  for the attachment of a carrying harness  40 . The drive motorization of the cutting head may be powered by a thermal engine, an electrical motor driven by a portable battery or by connection to the net.