Patent Publication Number: US-2022220750-A1

Title: Application head for a tape applicator, tape applicator provided with such a head

Description:
The present invention relates to an application head for an applicator of jointing tape for joining two sheets of plasterboard. 
     Such an applicator is intended for laying a tape made of paper or similar material, that comes in the form of a roll, between two adjacent sheets of plasterboard, during building or renovation work, using a pasty jointing compound known as mud. 
     Thus, the mud fills the space between the two sheets and the tape holds them together. 
     The tape is laid along two sheets positioned in one and the same plane or at a corner-forming angle. Once the mud and the tape are in position, the user smooths them using a flat spatula, or a corner spatula for the corners. The tape thus makes it possible to obtain a perfectly smooth join between the sheets. 
     Tape applicators commonly known as taping “banjos” are already known, these comprising a mud chamber and a payout device for paying out a jointing tape from a roll to perform numerous jointing operations, particularly on large jobs. 
     To this end, the chamber has, by reference to the position of use, a rear wall delimiting a tape inlet slot and a frontal wall delimiting a tape outlet slot. 
     An application head is generally intended to be attached to the frontal wall above the outlet slot to ensure correct application of the tape, namely to extract the mud-laden tape from the applicator and press the tape onto the sheets of plasterboard. The user then performs a finishing smoothing operation using a spatula. 
     Document WO2011094820 describes an application head configured to apply a tape between two sheets of plasterboard that are at a corner-forming angle to one another. The head comprises a mounting plate for fixing to the applicator, the mounting plate being extended by a fixed arm supporting a corner wheel of V-shaped profile to press the tape into a corner. 
     This head has numerous disadvantages. Specifically, it is suitable only for applying tape in a corner, which means that it has to be removed so that an application head suitable for applying tape flat can be refitted. Two distinct heads are therefore needed, and this is time-consuming and comes with the risk that one of the two heads may become lost. 
     Furthermore, the mounting plate is intended to be fixed inside the chamber and to collaborate with a shank of an external adjusting screw fitted with an eccentric and that is used not only for attaching the mounting plate but also for adjusting its position along the chamber in order to regulate the height of the tape outlet slot as illustrated in document US511427. The mounting plate and the adjusting mechanism are therefore directly in contact with the mud, and this fouls and damages the mechanism because it is necessary to force it in order to adjust the height of the slot. Furthermore, because the application head delimits the upper edge of the slot, the entirety of the head has to be changed regularly because the upper edge of the slot is subjected to a great deal of abrasion and to very high temperatures with repeated passage of the tape. 
     It is therefore an objective of the present invention to propose an application head that is multifunctional, namely able to apply the tape flat and apply it to corners, without needing to be removed between the two functions (of applying the tape flat and applying it to a corner) and without needing to be changed as a result of the wear created by the tape. 
     Document FR3007439 describes a multifunction application head which also has the advantage of not requiring removal between the two functions (applying the tape flat and applying it to a corner). 
     However, this application head is complex and its structure also does not allow the heightwise adjustment of the tape outlet slot. 
     Specifically, the application head comprises a mounting plate comprising a fixing web equipped with means for fixing the application head against the frontal wall of the chamber, and two flanks perpendicular to the fixing web and each having two orifices, facing each other in pairs, to receive a first rotation spindle and a second rotation spindle, which spindles are mutually parallel. 
     The application head also comprises two toothed wheels for driving the tape that are borne by the first rotation spindle, and two link rods mounted to rotate freely, on the second rotation spindle, between a retracted position and a position of use. A second end of each link rod is mounted to rotate freely on a third rotation spindle, on either side of a corner wheel. 
     The link rods are held elastically in the retracted position and in the position of use by two independent springs each one comprising an upstream arm (closest to the mounting plate) and a downstream arm (pressing elastically on the first rotation spindle bearing the toothed wheels). 
     For the corner wheel to pass from the retracted position to the position of use, these springs need to be deactivated and then activated in a complicated way. Specifically, the upstream arms of the springs have first of all to be disengaged one by one from the link rods and the downstream arms of the springs have to be moved one by one from the outside of the toothed wheels to the inside of the toothed wheels, this representing four actions. The link rods are then pivoted into contact with the first rotation spindle in order to bring the corner wheel into the position of use. The downstream arms of the springs are then activated one by one by positioning them against the link rods, and the upstream arms of the springs are activated one by one by positioning them against the flanks, this again representing four actions. A total of nine actions is therefore required in order to switch from the retracted position to the position of use, all the while handling small components, something which is not easy to do on a work site with mud-covered hands. Correspondingly, the risks of fouling the elastic retaining components of the head are great. 
     It is an objective of the present invention to propose an application head that provides simple dynamics and manipulations for switching from the retracted position to the position of use without the need to remove the entire head. 
     According to the invention, the function of maintaining a retracted position and the function of elastically maintaining a position of use are performed by two independent structures, allowing the switch between the two positions to be achieved in just three operations while at the same time very greatly limiting the risks of the elastic retention parts becoming fouled. 
     Thus, one subject of the invention is an application head for an applicator of jointing tape for joining two sheets of plasterboard, the applicator comprising a payout device for paying out a jointing tape that comes in a roll and a mud chamber through which the tape is paid out, in use, the chamber having, with reference to the position of use, a tape inlet slot formed between a free end of a rear wall of the chamber and a first free end of a lower wall of the chamber, and a tape outlet slot formed between a free end of a frontal wall of the chamber and a second free end of the lower wall of the chamber, the chamber further comprising two lateral walls, one of which constitutes a removable side cover providing access to the inside of the chamber, the application head being intended to be fixed to the frontal wall above the outlet slot, the application head comprising:
         a mounting plate comprising a fixing web equipped with means for fixing the application head against the frontal wall of the chamber, and two flanks perpendicular to the fixing web and each having two orifices, facing each other in pairs, to receive a first rotation spindle and a second rotation spindle, which spindles are mutually parallel,   two toothed wheels for driving the tape that are borne by the first rotation spindle;   two link rods being mounted via a first end to rotate freely, on the second rotation spindle, between a retracted position and a position of use, a second end of each link rod being mounted to rotate freely on a third rotation spindle, on either side of a corner wheel, itself free to rotate on the third rotation spindle;
 
the application head according to the invention comprising:
   a spring having two legs bearing against the mounting plate, each bearing leg being extended by a bend connected to an immobilizing arm equipped with a catch for immobilizing the link rods in the position of use, the immobilizing arms extending in a plane secant to a plane passing through the two bearing legs, the immobilizing arms being joined together by a return arch extending in a plane secant to the plane passing through the two immobilizing arms   reversible immobilization means independent of the spring, for immobilizing the link rods in the retracted position.       

     According to particular embodiments:
         the immobilization means may comprise at least one immobilization claw and at least one end stop configured so that, in the immobilization position, at least one link rod is kept pressed against the end stop by the claw;   the claws and/or the link rods may be configured to allow the link rods to be forcibly unlocked from the claws   the immobilization means may comprise an immobilization orifice and an immobilization pin intended to be inserted removably into the immobilization orifice;   wherein the return arch may be chosen from straight arches or curved arches;   the immobilization catches may comprise a lateral locking loop to lock the link rods laterally in the position of use;   the application head being intended to be fixed against an exterior contact face of the frontal wall of the chamber, in the fixed position, the contact face comprising a sliding guide equipped with an oblong orifice, the chamber further comprising a tape outlet slot, a plate for adjusting the height of said outlet slot, said plate being arranged inside the chamber, and a plate coupling and clamping spindle, the spindle being engaged in an orifice of the plate and in the oblong hole of the sliding guide, the fixing web of the application head may comprise a bearing face intended to bear against the contact face of the frontal wall of the chamber, in the fixed position, the bearing face of the fixing web bearing a sliding end stop equipped with a central hole through which the coupling and clamping spindle is intended to pass, and wherein the means for fixing the application head against the frontal wall of the chamber are able to collaborate with the coupling and clamping spindle to allow the fixing web to be clamped against the frontal wall of the chamber, or loosened therefrom;   the fixing means may comprise a quick clamp lever comprising a cam fixed in a pivoting and eccentric manner to a coupling member intended to be fixed to the coupling and clamping spindle;   the sliding end stop borne by the bearing face of the fixing web may consist of an oblong groove intended to collaborate with the sliding guide borne by the contact face of the frontal wall of the chamber, the sliding guide being an oblong rib; and/or   the sliding end stop borne by the bearing face of the fixing web may consist of an oblong rib intended to collaborate with the sliding guide borne by the contact face of the frontal wall of the chamber, the sliding guide being an oblong groove.       

     Another subject of the invention is a spring for an abovementioned application head, the spring comprising two legs bearing against the mounting plate, each bearing leg being extended by a bend connected to an immobilizing arm equipped with a catch for immobilizing the link rods in the position of use, the immobilizing arms extending in a plane secant to a plane passing through the two bearing legs, the immobilizing arms being joined together by a return arch extending in a plane secant to the plane passing through the two immobilizing arms. 
     According to particular embodiments:
         the return arch may be chosen from straight arches or curved arches; and/or   the immobilization catches may comprise a lateral locking loop to lock the link rods laterally in the position of use.       

     Another subject of the invention is an applicator of jointing tape between two sheets of plasterboard, the applicator comprising a payout device for paying out a jointing tape that comes in a roll and a mud chamber through which the tape is paid out, in use, the chamber having, with reference to the position of use, a rear wall delimiting a tape inlet slot, and a frontal wall delimiting a tape outlet slot, characterized in that the frontal wall of the chamber bears an abovementioned application head. 
     According to particular embodiments:
         the frontal wall of the chamber may comprise an exterior contact face for contact with a bearing face of the application head, the contact face bearing a sliding guide equipped with an oblong orifice, the chamber further comprising a plate for adjusting a height of the outlet slot, said plate being arranged inside the chamber, and a plate coupling and clamping spindle, the spindle being engaged in an orifice in the plate and in the oblong hole of the sliding guide, wherein the bearing face of the fixing web bears a sliding end stop equipped with a central hole through which the coupling and clamping spindle passes, and wherein the means for fixing the application head against the frontal wall of the chamber collaborate with the coupling and clamping spindle to allow the mounting plate and the adjusting plate to be clamped against the frontal wall of the chamber, or loosened therefrom;   the fixing means may comprise a quick clamp lever comprising a cam fixed in a pivoting and eccentric manner to a coupling member fixed to the coupling and clamping spindle;   the sliding end stop borne by the bearing face of the fixing web may consist of an oblong groove collaborating in sliding with the sliding guide borne by the contact face of the frontal wall of the chamber, the sliding guide being an oblong rib; and/or   the sliding end stop borne by the bearing face of the fixing web may consist of an oblong rib collaborating in sliding with the sliding guide borne by the contact face of the frontal wall of the chamber, the sliding guide being an oblong groove.       

     Another subject of the invention is a method for applying a jointing tape between two adjacent sheets of plasterboard making an angle between them, the method comprising the following steps:
     a) providing an abovementioned jointing-tape applicator, the chamber of the applicator being filled with compound and the tape being ready for use and comprising a free end protruding from the tape outlet slot;   b) if the link rods bearing the corner wheel are in the retracted position, deactivating the link rod fixing means so that they can be pivoted toward the first rotation spindle;   c) squeezing the spring by applying a squeezing force between the two arms of the spring and at the level of the return arch so as to allow the link rods to pivot until they come to bear against the first rotation spindle;   d) positioning the spring arm immobilization catches above the link rods then releasing the spring so that the link rods are in the position of use, returned elastically toward the first pivot spindle;   e) pressing the free end of the tape against the two adjacent sheets of plasterboard, in the corner formed by the two sheets of plasterboard, then pressing the head of the applicator against the two sheets of plasterboard so that the drive wheels press the tape against the sheets;   f) moving the applicator along so that the drive wheels drive the tape which is paid out, carrying mud out with it, and so that the corner wheel, borne by the link rods in the position of use, presses the tape into the corner in all positions of inclination of the applicator with respect to the sheets of plasterboard, by virtue of the elastic return of the link rods toward the first pivot spindle.   

    
    
     
       Further features of the invention will be stated in the following detailed description, given with reference to the attached drawings, which respectively depict: 
         FIG. 1  depicts a schematic perspective view of a tape applicator according to the invention in the position of use, namely in the position for applying a tape, and equipped with an application head according to the invention; 
         FIG. 2  depicts a schematic perspective rear view of the tape applicator of  FIG. 1  and from which one of the lateral walls has been removed in order to show the internal structure of the applicator; 
         FIG. 3  depicts a schematic exploded perspective view of an application head according to the invention; 
         FIG. 4  depicts a schematic perspective view of a first embodiment of a spring for an application head according to the invention; 
         FIG. 5  depicts a schematic perspective view of a second embodiment of a spring for an application head according to the invention; 
         FIG. 6  depicts a schematic perspective view of an application head according to the invention, with the corner wheel in the retracted position; 
         FIG. 7  depicts a schematic perspective view of an application head according to the invention, with the corner wheel in the process of being deployed to the position of use; 
         FIG. 8  depicts a schematic perspective view of an application head according to the invention, with the corner wheel in the position of use; 
         FIG. 9  depicts a schematic exploded perspective view, from a first perspective, of a second embodiment of an application head according to the invention, further comprising a means for the heightwise adjustment of the tape outlet slot of the applicator according to the invention; and 
         FIG. 10  depicts a schematic exploded perspective view, from a second perspective, of the embodiment of an application head of  FIG. 8 , showing the plate for the heightwise adjustment of the tape outlet slot. 
     
    
    
     An applicator equipped with an application head according to the invention is illustrated in  FIG. 1 . 
     The applicator  1  comprises a payout device  2  for paying out a roll  3  of jointing tape (illustrated in dotted line) and a mud chamber  4  through which the tape is paid out during use. 
     The applicator also comprises a holding handle  5  for transporting it or handling it operationally when applying the tape. 
     Alternatively or in combination, the applicator may comprise a carry strap (not illustrated) allowing the applicator to be picked up from beneath. 
     As illustrated in  FIG. 2 , the chamber  4  has, with reference to the position of use, a tape inlet slot  6  formed between a free end  7   a  of a rear wall  7  of the chamber and a first free end  8   a  of a lower wall  8  of the chamber. 
     The chamber  4  also has a tape outlet slot  9  formed between a free end  10   a  of a frontal wall  10  of the chamber and a second free end lib of the lower wall  8  of the chamber. 
     The chamber further comprising two lateral walls  11  and  12 , one of which constitutes a removable side cover  11  providing access to the inside of the chamber  4 . 
     An application head  100  according to the invention is fixed to the frontal wall  10  of the chamber  4 . 
     The application head  100 , illustrated in exploded perspective in  FIG. 3 , comprises a mounting plate  110  comprising a fixing web  111  and two flanks  112   a - 112   b  perpendicular to the fixing web  111 . Each flank  112   a - 112   b  having two orifices  113 - 114  facing one another in pairs. Thus, the orifice  113  of the flank  112   a  faces the orifice  113  of the flank  112   b  to receive a first rotation spindle  120 , and the orifice  114  of the flank  112   a  faces the orifice  114  of the flank  112   b  to receive a second rotation spindle  130 . The rotation spindles  120  and  130  are mutually parallel. 
     The fixing web  111  is equipped with means  115  for fixing against the frontal wall  10  of the chamber, to fix the application head  100  to the chamber. In  FIG. 3 , these fixing means consist of at least one orifice  115  able to accept a screw (not illustrated) for fixing to the chamber. Alternatively, as described in connection with  FIGS. 8 and 9 , the fixing means may be more elaborate and also allow heightwise adjustment of the outlet slot, again by means of the orifice  115 . 
     The first rotation spindle  120  bears two toothed wheels  121  for driving the tape as it is being applied. As a preference, the toothed wheels  121  are mounted with the freedom to rotate about the rotation spindle  120  and on the outside of the flanks  112   a - 112   b  by means of spacers  122 . The assembly is held in position by means of washers  123  and a nut  124 . 
     As a preference, the first rotation spindle  120  also bears a smooth pressing wheel  125  mounted to rotate freely between the two flanks  112   a - 112   b  and which serves to press the tape against the sheets of plasterboard. 
     The application head also comprises two link rods  131  mounted to rotate freely on the second rotation spindle via a first end  131   a , between a retracted position (illustrated in  FIG. 6 ) and a position of use (illustrated in  FIG. 7 ). 
     A second end  131   b  of each link rod is mounted to rotate freely on a third rotation spindle  132 , on either side of a corner wheel  133 , itself free to rotate on the third rotation spindle  132 . The corner wheel has a V-shaped rolling edge to press the tape onto sheets of plasterboard that form an angle between them. 
     According to the invention, the application head  100  comprises a spring  140  (illustrated in greater detail in  FIG. 4 ) comprising two bearing legs  141  bearing against the mounting plate  111 , each bearing leg  141  being extended by a bend  142  connected to an immobilizing arm  143  for immobilizing the link rods in the position of use, each immobilizing arm being equipped with an immobilizing catch  144 . 
     The immobilizing arms  143  extend in a plane secant to a plane passing through the two bearing legs  141 . As a preference, the arms are substantially perpendicular to the mounting plate  11 , in the position of use. 
     The immobilizing catches have a bearing portion  144   a  to bear against the flanks  112   a - 112   b  or against the link rods  131 , depending on the position—retracted position or position of use. The bearing portion is preferably perpendicular to the flanks  112   a - 112   b  or to the link rods  131 , whereas the immobilizing arms  143  are substantially parallel to the flanks  112   a - 112   b  or to the link rods  131 . 
     The bearing portion has a length greater than or equal to the sum of the thickness of the flanks  112   a - 112   b  and the thickness of the link rods  131 . 
     In one advantageous embodiment, the immobilizing catches  144  comprise a lateral locking loop  144   b  for locking the link rods laterally in the position of use. The loop prevents any accidental lateral disengagement of the link rods in the position of use. 
     The loop  144   b  is situated at the outside end of the contact portion  144   a . What is important is that the bearing portion has a length L 1 , measured between the arm  143  and the loop  144   b , that is greater than or equal to the sum of the thickness of the flanks  112   a - 112   b  and the thickness of the link rods  131 . 
     A coil of spring  145  is arranged between the free ends of the bearing legs  141  and the bends  142  for connecting to the arms  143 . This coil  145  performs two functions simultaneously: an elastic return function which allows the entire part consisting of the portion of the legs connected to the bends  142 , the bends  142 , the arms  143  and the arch  146  to pivot together while the portion of the legs bearing their free end remains in contact with the mounting plate  111 . The coil also houses the second rotation spindle  130 , holding the spring in position and ensuring that the spring pivots about the rotation spindle  130 . 
     Furthermore, the immobilizing arms  143  are joined together by a return arch  146  extending in a plane secant to the plane passing through the two immobilizing arms  143 . 
     This return arch may be a curved arch ( FIG. 4 ) or straight arch  146   a  ( FIG. 5 ). It may be arranged toward the first rotation spindle  120  as illustrated in the figures. In that case, the spring takes the overall shape of an S when viewed in profile. The arch may also be arranged toward the second rotation spindle  130  (this is not illustrated), in which case the spring takes the overall shape of a C when viewed in profile. 
     The return arch  146  performs an unexpected return function which, when the spring is squeezed at said arch  146 , ensures that the bends have a tendency to move closer to one another, allowing the immobilizing catches  144  to disengage from the flanks in order to allow the link rods  131  to pass during the transition between the retracted position and the position of use, and vice versa, as explained with reference to  FIGS. 6 to 8 . This also allows the bends  142  to be immobilized temporarily against the inside of the flanks  112   a - 112   b  during the transition between the retracted position and the position of use, thereby avoiding the need to hold the spring. 
     In the absence of the arch, the bends  142  have a tendency to move apart during squeezing, thereby preventing sufficient disengagement of the immobilizing catches  144  and additionally preventing them from being able to be inserted temporarily between the flanks  112   a - 112   b.    
     According to the invention, the application head  100  according to the invention also comprises reversible immobilization means  150 , independent of the spring, for reversibly immobilizing the link rods  131  in the retracted position. 
     One preferred embodiment is illustrated in  FIG. 3  in which the immobilization means  150  comprise at least one immobilization claw  151  and at least one end stop  152  configured so that, in the immobilization position, at least one link rod is kept pressed against the end stop  152  by the claw  151 . 
     The end stop  152  takes the form of a ramp, preventing the corner wheel  133  from being in contact with the chamber  4  in the retracted position. The claws  151  have a longitudinal portion  151   a  in the vertical continuation of the flanks  112   a - 112   b , and a shoulder  151   b  that immobilizes and clamps the link rods against the end stop  152 . 
     The claws  151  and/or the link rods  131  are configured to allow the link rods to be forcibly unlocked from the claws. Thus, when the user wishes to switch the link rods from the retracted position to the position of use, in the direction of the arrow F 1  ( FIG. 7 ), they force the link rods to disengage from the claws  151 . This forcible unlocking is allowed through the elasticity of the link rods  131  and/or the elasticity of the claws (particularly the longitudinal portion  151   a ) which allow elastic deformation of the link rods and/or of the claws. 
     At the moment at which a tape is to be applied across two sheets that form an angle between them, it is necessary to ensure that the tape is properly pressed into the corner and against the sheets of plasterboard. For that, the corner wheel must be used. 
     Thus, in order to apply a jointing tape to join two adjacent sheets of plasterboard that make an angle between them, using an applicator equipped with an application head according to the invention, the following procedure, illustrated in  FIGS. 6 to 8 , is followed. 
       FIG. 6  illustrates an application head according to the invention in the retracted position, namely in the position in which the corner wheel is inactive and cannot come into contact with the tape. In other words, in this position, only the toothed wheels  121 , and possibly the pressing wheel  125 , are in contact with the tape. This position is the position used when the tape is to be applied to join two coplanar sheets of plasterboard. 
     In this figure, it may be seen that the chamber is full of mud E and that the tape B is in the position of use, namely positioned in contact with the mud in the chamber and that it has a free end B 1  protruding from the outlet slot  9 . 
     In the retracted position ( FIG. 6 ), when the link rods  131  bearing the corner wheel  133  are in the retracted position, the link rod fixing means  150  are deactivated so that they can be pivoted in the direction of the arrow F 1  toward the first rotation spindle  120  ( FIG. 7 ). In the embodiment illustrated, the link rods are forced in the direction of the arrow F 1  so that they are forcibly disengaged from the claws  151 . 
     Once the link rods  131  have been released from the claws  151 , the spring is squeezed by applying a squeezing force (illustrated by the arrows F 2  and F 3 ) between the two arms of the spring  140  and at the level of the return arch  145  in order to retract the immobilizing catches  144  towards the space situated between the two flanks  112   a - 112   b  and allow the link rods to pass and to pivot until they are bearing against the first rotation spindle  120 . 
     The immobilizing catches  144  of the spring arms are then positioned above the link rods  131  then the spring is released (as illustrated by the arrows F 4  and F 5 ) so that the immobilizing catches are in elastic contact with the link rods and the latter are, in the position of use, elastically returned toward the first pivot spindle. More specifically, the spring is configured in such a way that, in the position of use, the immobilizing catches are in elastic contact with the link rods between the second pivot spindle of the link rods and that portion of the link rods that is in contact with the first pivot spindle  120 . 
     The free end of the tape can then be pressed against the two adjacent sheets of plasterboard, in the corner formed by the two sheets of plasterboard, then the head of the applicator is pressed against the two sheets of plasterboard so that the drive wheels press the tape against the sheets. 
     The applicator is then moved along such that the drive wheels drive the tape which is paid out, carrying mud with it. At the same time, the corner wheel, borne by the link rods in the position of use, presses the tape into the corner and against the sheets, and does so in any position of inclination of the applicator with respect to the sheets of plasterboard, thanks to the elastic return of the link rods toward the first pivot spindle. 
     In order to place the head back in the retracted position, the spring is squeezed between the two arms of the spring  140  and at the return arch  145  to retract the immobilizing catches  144  toward the space situated between the two flanks  112   a - 112   b  and allow the link rods to pass and to pivot in the opposite direction to the arrow F 1 , then the immobilization means are activated to immobilize the link rods in the retracted position. In the embodiment illustrated, this is done by forcing the link rods to pass against the claws  151  until the link rods come into contact with the end stop  152 . In this position, the link rods have completely passed against the claws  151  which deploy over the link rods elastically and immobilize the latter, preventing them from pivoting under the effect of gravity. 
     The application head according to the invention is therefore multifunctional and very simple and quick to use. It requires just three movements to switch from one position to the other, where heads of the prior art require a greater number of movements. 
     Furthermore, it allows the tape to be pressed down while permitting a wide variety of movements because the link rods (and therefore the corner wheel) are pressed elastically toward the front of the head, namely toward the first pivot spindle  120 . 
     Finally, the structure of the application head allows it to bear means of attachment to the chamber which, furthermore, perform a function of heightwise adjustment of the tape outlet slot  9 . 
     Specifically, the tape outlet slot  9  is formed between a free end of a frontal wall of the chamber and a second free end of the lower wall of the chamber. The height H 1  of this slot determines the amount of mud carried by the tape. 
     Now, it is desirable to be able to alter this amount of mud, according to the conditions of use, the viscosity of the mud, etc. 
     The invention proposes mechanically coupling to the application head a plate, that is structurally independent of the head and able to slide relative to the slot in order to reduce the resultant height H 2  of the slot  9  and thus reduce the amount of mud applied with the tape. 
     This embodiment, illustrated in  FIGS. 9 and 10 , takes advantage of the structure of the application head according to the invention and, in particular, the mounting plate. 
     In these figures, only the elements necessary for understanding this functionality have been illustrated. Of course, the link rods  131 , the corner wheel  133 , the spring  140  according to the invention, the pivot spindles  120 - 130 , the drive wheels  121 , etc., may be added. 
     The application head  100  according to the invention is intended to be fixed against an exterior contact face  10   b  of the frontal wall  10  of the chamber  4 , in a fixing position. 
     The invention plans for the contact face  10   b  to comprise a sliding guide  14  equipped with an oblong orifice  15 . As will be described later, the length of the oblong hole determines the length of sliding travel of the plate and therefore the resultant height H 2  of the outlet slot  9 . 
     The chamber further comprises an adjusting plate  16  for adjusting a height H 2  of said outlet slot, the adjusting plate  16  being arranged inside the chamber, against the front wall  10  of the chamber. 
     A coupling and clamping spindle  17  for coupling and clamping the plate  16  is engaged in an orifice  16   a  of the plate  16  and in the oblong hole  15  of the sliding guide  14 . 
     To complement this, the fixing web  111  of the application head comprises a bearing face  111   a  intended to bear against the contact face  10   b  of the frontal wall  10  of the chamber, in a fixing position. 
     The bearing face  111   a  of the fixing web comprises a sliding end stop  111   b  provided with a hole  115  arranged centrally with respect to the sliding end stop. 
     The hole  115  is intended to have the coupling and clamping spindle  17  pass through it to fix the application head against the frontal wall of the chamber. 
     Complementary fixing means are provided to collaborate with the coupling and clamping spindle  17  to allow the fixing web  111  to be clamped against/loosened with respect to the frontal wall  10  of the chamber. 
     In the preferred embodiment illustrated, the fixing means comprise a quick clamp lever  116  comprising a cam  116   a  fixed eccentrically and such that it can pivot with respect to the axis X-X to a coupling member  117  intended to be fixed to the coupling and clamping spindle. Advantageously, a washer  118  is provided between the coupling member and the fixing web  111  to protect the latter from the friction of the cam  116   a  during clamping/loosening. 
     In the embodiment illustrated, the sliding end stop  111   b  borne by the bearing face  111   a  of the fixing web  111  consists of an oblong groove intended to collaborate with the sliding guide  114  borne by the contact face  10   b  of the frontal wall  10  of the chamber, the sliding guide  114  being an oblong web of a shape that complements, except in terms of length, the groove  111   b . In this case, the groove borne by the fixing web will have a length L 3 , and the rib borne by the chamber will have a length L 2  less than the length L 3 . 
     Of course, it is possible to reverse the volumes and for the sliding end stop borne by the bearing face of the fixing web to consist of an oblong rib intended to collaborate with the sliding guide borne by the contact face of the frontal wall of the chamber, the sliding guide being an oblong groove. In this case, the groove borne by the chamber will have a length L 3 , and the rib borne by the fixing web will have a length L 2  less than the length L 3 . 
     In order to set the height H 2  of the outlet slot, the means for tensioning/slackening-off the coupling and clamping spindle are operated in order to loosen the mounting plate and the plate against the frontal wall of the chamber. 
     To do that, the lever  116  is pivoted in such a way as to position the cam  116   a  a smaller distance away from the washer. This then reduces the clamping tension applied to the coupling and clamping spindle  17 . 
     The mounting plate  110  coupled to the adjusting plate  16  are then slid using the coupling and clamping spindle  17  until the outlet slot for the tape has an operational height H 2  corresponding to a datum mud-application output. 
     The means for tensioning/slackening-off the coupling and clamping spindle are then operated in order to clamp the mounting plate and the plate against the frontal wall of the chamber. In the embodiment illustrated, the lever  116  is pivoted in such a way as to position the axis of rotation X-X of the cam  116   a  at a greater distance from the washer, thereby increasing the clamping tension applied to the coupling and clamping spindle  17 . 
     In one advantageous embodiment, the orifice  16   a  in the plate  16  is polygonal and the coupling and clamping spindle  17  has a polygonal cylindrical portion  17   a  of a shape that complements the polygonal hole  16   a  and that is intended to be inserted in the polygonal hole  16   a  in order to prevent the plate from rotating about the coupling and clamping spindle. That then easily ensures perfect parallelism of the functional edges of the outlet slot  9  during application. 
     The structure of the application head according to the invention also allows easier adjustment of the height H 2 . Specifically, adjustment is generally performed when the applicator is set down via its lower face  8  on a support. In this position, it is difficult to see the outlet slot  9 . 
     The invention makes provision for the mounting plate  110  to have a rectilinear distal edge  119 , which is to say the edge at the opposite end to the first axis of rotation, that constitutes an adjustment marker against a graduated scale  13  parallel to the rectilinear distal edge  19  and borne by the exterior contact face  10   b  of the frontal wall  10  of the chamber. This scale thus directly represents the outlet slot, so that the user can directly visualize, above the immobilizing head, the measurement of the opening of the outlet slot which is situated below the head and which is not visible when the user is adjusting the height of the outlet slot. 
     This avoids said user having to turn the applicator over after or during adjustment. 
     The fixing head  100  according to the invention thus allows heightwise adjustment of the slot, while at the same time being structurally independent of the adjusting plate. 
     Thus, in the event of plate wear, it is possible to change the plate without having to change the application head. 
     Furthermore, it means that different materials can be used for the application head and for the plate. The latter is advantageously made of a non-rusting metal which is more resistant to the heat and abrasion of the mud and of the tape than the plastic generally used in the manufacture of the application heads. 
     According to alternative or complementary embodiments which have not been illustrated:
         the immobilization means  150  may be comprise an immobilization orifice and an immobilization pin intended to be inserted removably into the immobilization orifice. The immobilization orifice is, for example, borne by the flanks  112   a - 112   b  and the immobilization pin is borne by the link rods. The immobilization pin (which may be combined with an elastic return means) is then extracted from the immobilization orifice in order to allow the link rods to be pivoted into the position of use.   the rectilinear distal edge  119  may be beveled to make the outlet slot height setting easier to read against the graduated scale  13 .