Patent Publication Number: US-2022228376-A1

Title: Tape applicator with adjustable compound flow and method for adjusting the compound flow of such an applicator

Description:
The present invention relates to a tape applicator with adjustable compound flow rate and to a method for adjusting the compound flow rate of such an applicator. 
     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 compound fills the space between the two sheets and the tape holds them together. 
     The tape is laid between two sheets positioned in one and the same plane or at a corner-forming angle. Once the compound 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 joint between the sheets. 
     Tape applicators commonly known as taping “banjos” are already known, these comprising a mud chamber and a payout device for dispensing 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 front 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 the 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 U.S. Pat. No. 511,427. 
     However, the mounting plate and the adjusting mechanism are 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 a tape applicator equipped with adjusting means that are easy to operate, robust and precise, which means to say fairly insensitive to abrasion and heat, and inexpensive, which is to say easily replaceable independently of the application head. 
     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 adjustment of the height of the tape outlet slot. 
     Specifically, the application head in that document comprises a mounting plate equipped with simple fixing holes intended to accept a screw inserted into the frontal wall of the tool. 
     It is therefore an objective of the present invention to propose a tape applicator equipped with adjusting means that can be coupled reversibly (in order to allow them to be changed independently) to an application head arranged on the outside of the chamber so as to allow simultaneous adjustment of the height of the outlet slot and of the position of the application head. 
     According to the invention, the sliding function is removed to outside the chamber, making it possible to limit the number of parts inside the chamber and have only these to change, rather than the sliding mechanism. That also allows the sliding mechanism to be incorporated into the application head, allowing both the application head and the adjusting parts situated inside the chamber to be slid at the same time. 
     Thus, one subject of the invention is 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 outlet slot having a determined height and being equipped with heightwise adjustment means. 
     According to the invention, the adjusting means comprise:
         a plate for adjusting the height of said outlet slot, said plate being arranged inside the chamber against an interior face of the frontal wall of the chamber,   a mounting plate fixed with the ability to slide against an exterior contact face of the frontal wall of the chamber, the contact face comprising a sliding guide, of determined length, equipped with an oblong orifice, the mounting plate comprising a sliding end stop collaborating in sliding with the sliding guide, the sliding end stop being of a length greater than the determined length of the sliding guide and equipped with a central hole;   a coupling and clamping spindle for coupling and clamping the plate, said spindle being engaged in an orifice of the plate, in the oblong hole of the sliding guide, and in the central hole of the sliding end stop   means for tensioning/slackening-off the coupling and clamping spindle to allow the mounting plate and the plate to be clamped against/loosened off from the frontal wall of the chamber.       

     According to particular embodiments:
         the orifice in the plate may be polygonal and the coupling and clamping spindle has a polygonal cylindrical portion of a shape that complements the polygonal hole and that is intended to be inserted in the polygonal hole in order to prevent the plate from rotating about the coupling and clamping spindle;   the plate may comprise a second orifice, the coupling and clamping spindle comprising a bearing head bearing against the plate equipped with an immobilization pin intended to be engaged in the second orifice in order to prevent the plate from rotating about the coupling and clamping spindle;   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 mounting plate 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;   the sliding end stop borne by the bearing face of the mounting plate 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;   the plate may be made of a rustproof metal;   the mounting plate may be a mounting plate for fixing an application head, the mounting plate comprising a fixing web and two flanks perpendicular to the fixing web and each having two orifices facing each other in pairs to receive a mutually parallel first rotation spindle and a second rotational spindle, the first rotation spindle bearing two toothed wheels for driving the tape, the application head further comprising:
           two link rods mounted via a first end to rotate freely on the second rotation spindle, between a retracted position and an application position, 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   a spring having two bearing legs bearing against the mounting plate, each one 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 legs, the 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;   
           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; and/or   the free end of the rear wall of the chamber and the first free end of the lower wall of the chamber may comprise a cylinder of cross section greater than a thickness of the wall to which each cylinder is attached, each cylinder being covered with a removable protective sleeve of an internal cross section that complements the cylinder that the sleeve covers, each protective sleeve having a longitudinal opening delimited by two immobilization edges for immobilization against the wall bearing the cylinder that the sleeve covers.       

     Another subject of the invention is a method for adjusting the mud flow rate of an applicator of jointing tape joining two adjacent sheets of plasterboard, the method comprising the following steps:
     a) providing an abovementioned jointing-tape applicator, the chamber of the applicator being filled with jointing compound and the tape being ready for use and comprising a free end protruding from the tape outlet slot;   b) operating the means for tensioning/slackening-off the coupling and clamping spindle in order to slacken off the mounting plate and the plate from against the frontal wall of the chamber   c) sliding the mounting plate coupled to the adjusting plate using the coupling and clamping spindle until the outlet slot for the tape has an operational height corresponding to a datum mud-application flow output;   d) operating the means for tensioning/slackening-off the coupling and clamping spindle in order to clamp the mounting plate and the plate against the frontal wall of the chamber.   

    
    
     
       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; 
         FIG. 2  depicts a schematic perspective view of the tape applicator of  FIG. 1 , with the cover that provides access to the inside of the chamber open; 
         FIG. 3  depicts a schematic exploded partial perspective view, from a first perspective, of a first embodiment of the means for the heightwise adjustment of the outlet slot of an applicator according to the invention; 
         FIG. 4  depicts a schematic exploded partial perspective view, from a second perspective, of the means for the heightwise adjustment of the outlet slot of an applicator according to the invention of  FIG. 3 , showing the plate for the heightwise adjustment of the tape outlet slot; 
         FIG. 5  a schematic perspective view of one advantageous embodiment of a spring for an application head that can be combined with heightwise adjustment means according to the invention; 
         FIG. 6  depicts a schematic perspective view of a second embodiment of an applicator according to the invention which further comprises a system for protecting the tape inlet slot; 
         FIG. 7  depicts a schematic perspective view of an enlargement of  FIG. 6 , centered on the tape inlet slot, which comprises protective sleeves affording protection against abrasion; and 
         FIG. 8  depicts a schematic exploded perspective view of  FIG. 7 , illustrating the particular structure of the protective sleeves according to the invention. 
     
    
    
     An applicator equipped with means for the height-wise adjustment of the outlet slot according to the invention is illustrated in  FIGS. 1 and 2 . 
     The applicator  1  comprises a payout device  2  for paying out a roll  3  of jointing tape (illustrated by 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  8   b  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 . 
     The tape outlet slot  9  is formed between a free end  10   a  of a frontal wall  10  of the chamber and a second free end  8   b  of the lower wall  8  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 a mounting plate  110 , external to the chamber  4 , a plate, internal to the chamber  4 , structurally independent of the mounting plate, 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. 
     The heightwise adjustment means according to the invention are detailed in  FIGS. 3 and 4 . 
     Thus, according to the invention, the adjusting means comprise an adjusting plate  16  for adjusting a height H 2  of said outlet slot, the adjusting plate  16  being arranged inside the chamber, against an interior face  10   c  of the front wall  10  of the chamber. 
     The invention makes provision for the contact face  10   b  of the frontal wall  10  to comprise a longitudinal sliding guide  14  perpendicular to the outlet slot  9 . The sliding guide  14  is 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 adjusting plate and therefore the resultant height H 2  of the outlet slot  9 . 
     The adjusting means also comprise a coupling and clamping spindle  17  for coupling and clamping the plate  16 , which spindle is engaged in an orifice  16   a  of the plate  16  and in the oblong hole  15  of the sliding guide  14 . 
     The adjusting means also comprise a mounting plate  110 , fixed with the ability to slide against an exterior contact face  10   b  of the frontal wall  10  of the chamber. 
     The mounting plate  110  comprises at least a fixing web  111  which 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 mounting plate  110  may comprise structures other than the web  111 , such as flanks  112   a - 112   b  which may have a function of supporting at least one tape application wheel. 
     To complement the sliding guide  14 , 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. 
     In use, the sliding end stop  111   b  collaborates in sliding with the sliding guide  14 . 
     The hole  115  is intended to have the coupling and clamping spindle  17  pass through it to fix the mounting plate  110  against the frontal wall of the chamber. 
     The fixing means also comprise tensioning/slackening-off means to collaborate with the coupling and clamping spindle  17  in order to allow the fixing web  111  of the mounting plate  110  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 XX 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 rib 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 adjust the flow of mud during application, the height H 2  of the outlet slot is adjusted. The flow of mud is the amount of mud per unit area of tape: the taller the slot, the greater the quantity of mud under the tape and therefore the greater the mud flow rate. 
     In order to do that, the means for tensioning/slackening-off the coupling and clamping spindle  17  are operated in order to slacken off the mounting plate  110  and the plate  16  from against the frontal wall  10  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  is 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 flow output. 
     The means for tensioning/slackening-off the coupling and clamping spindle  17  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. 
     Alternatively, the plate may comprise a second orifice, the coupling and clamping spindle comprising a bearing head bearing against the plate equipped with an immobilization pin intended to be engaged in the second orifice in order to prevent the plate from rotating about the coupling and clamping spindle. 
     The structure of the adjusting means 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 the lower face  8  on a support. In this position, it is generally difficult to see the outlet slot  9  because of the presence of an application head. 
     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 outlet slot  9 , that makes it possible to constitute 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 mounting plate 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 adjusting means according to the invention thus allow 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 fixed on the mounting plate. 
     This structure makes it possible to provide for the mounting plate to bear a tape application head. For example, the structure of the adjusting means and, in particular, the use of an exterior mounting plate, allows the bearing of means which provide a particular tape application function such as, notably, the ability to apply tape into a corner, a tape-cutting head, etc. 
     Furthermore, it means that different materials can be used for the mounting plate (and possibly the rest of 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. 
     An example of an application head that may advantageously be combined with the means for the height-wise adjustment of the outlet slot according to the invention is illustrated in  FIGS. 1 and 2 . 
     In this case, the mounting plate  110  is a mounting plate for fixing an application head  100 , the mounting plate comprising a fixing web and two flanks perpendicular to the fixing web and each having two orifices, facing each other in pairs, to receive a first rotation spindle  120  and a second rotational spindle  130  which spindles are mutually parallel. 
     The first rotation spindle bears two toothed wheels  121  for driving the tape. 
     The application head  100  further comprises two link rods  131  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 is mounted to rotate freely on a third rotation spindle, on either side of a corner wheel  133 , itself free to rotate on the third rotation spindle. 
     The application head  100  also comprises a spring  140  like the one illustrated in  FIG. 5 . 
     The spring having two legs  141  bearing against the mounting plate, each one being extended by a bend  142  connected to an immobilizing arm  143  equipped with a catch  144  for immobilizing the link rods in the position of use. 
     The immobilizing arms  143  thus extend in a plane secant to a plane passing through the two legs  141 , the arms being joined together by a return arch  146  extending in a plane secant to the plane passing through the two immobilizing arms. 
     A coil of spring  145  is arranged between the free ends of the bearing legs  141  and the bends  142  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 . 
     Finally, the application head  100  comprises reversible immobilization means, independent of the spring  140 , for reversibly immobilizing the link rods in the retracted position. These immobilization means here 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 by the claw. In this case, the claws and/or the link rods are configured to allow the link rods to be forcibly unlocked from the claws in order to switch into a position for applying tape in a corner. 
     The invention also provides means for limiting leaks of mud from the tape  3  inlet slot  6 . These means, by reducing leaks according to the viscosity of the mud, allow better control over the flow rate of mud at the outlet slot  9 . 
     Furthermore, these means provide effective and inexpensive protection of the tape inlet slot against abrasion and increases in temperature, and do so in a way that offers great ease of maintenance. 
     As illustrated in  FIGS. 6 to 8 , the free end  7   a  of the rear wall  7  of the chamber and the first free end  8   a  of the lower wall  8  of the chamber each comprise a cylinder,  7   a   1  and  8   a   1  respectively, of cross section D 1  greater than a thickness E 1  of the wall ( 7  and  8  respectively) to which each cylinder  7   a   1  and  8   a   1  is attached. 
     According to the invention, each cylinder,  7   a   1  and  8   a   1  respectively, is covered with a removable protective sleeve  201  and  202  respectively, of an interior cross section that complements the cylinder,  7   a   1  and  8   a   1  respectively, that the sleeve covers. 
     Each protective sleeve  201  and  202  has a longitudinal opening  201   a - 202   a , delimited by two immobilization edges  201   b - 202   b  for immobilization against the wall ( 7  and  8  respectively) bearing the cylinder  7   a   1  and  8   a   1  respectively, that the sleeve  201  and  202  respectively, covers. 
     The sleeves  201 - 202  are thus self-immobilizing against the wall that bears the cylinders because the edges  201   b - 202   b  of the longitudinal openings  201   a - 202   a are arranged at the junction where the wall and the cylinder meet, which junction exhibits a point of inflection preventing the sleeves from sliding or from falling off the cylinder.    
     These sleeves are advantageously made of metal, such as stainless steel. The material thus exhibits resistance to abrasion and to heat that is far greater than that of the plastic generally used in the manufacture of the tape applicators. 
     Moreover, this structure of the free ends of the rear and lower walls is very easy to produce using molding. 
     The sleeves, if they have become worn, are very easy to change. 
     [The method for performing maintenance on such a type tape applicator comprises a first step of opening the side wall that constitutes the removable side cover  11  providing access to the inside of the chamber  4  and to the free ends  7   a  and  8   a  of the rear wall  7  and of the lower wall  8 . 
     The worn protective sleeve or sleeves  201 - 202  is or are then removed from the free ends  7   a  and  8   a  of the rear wall  7  and/or of the lower wall  8  of the chamber by sliding them along the cylinders  7   a   1 - 8   a   1  borne by said free ends. 
     New protective sleeves are then inserted, by sliding them along the cylinders  7   a   1 - 8   a   1  borne by the free ends of the rear wall and of the lower wall of the chamber. To do that, the longitudinal opening of each sleeve is aligned with the wall  7  or  8  bearing the cylinder onto which the sleeve is slipped. The immobilization edges of the longitudinal openings of the sleeves therefore position themselves at the junction where the wall meets the cylinder. 
     Finally, the lateral wall  11  that constitutes the removable side cover is closed again. 
     As a preference, each cylinder  7   a   1 - 8   a   1  has a circular cross section and each protective sleeve  201 - 202  has an open C-shaped circular cross section. This ensures optimal contact with the tape as it is being applied, without sharp edges, and avoids the tape tearing. 
     It is then possible to apply the tape very quickly, without fear that the free edges of the rear and lower walls might melt, and without the risk of tearing the tape, thanks to the rounded shape of the sleeves. 
     Aside from affording protection against abrasion, this structure of the sleeves also allows the applicator to be adapted according to the viscosity of the mud used. 
     Thus, a user wishing to employ a mud that is more fluid than normal will change the sleeves so that the tape inlet slot is not as tall, thus limiting mud leaks. 
     For this purpose, the protective sleeves  201 - 202  have a thickness such that when inserted around the cylinders of the free end of the rear wall and of the lower wall, they are spaced apart by an inlet slot height that is such that, in use, the tape is able to run freely but the mud stored in the mud chamber is not. 
     It is therefore possible to offer a kit for applying jointing tape between two sheets of plasterboard, comprising a tape applicator and a plurality of protective sleeves of different thicknesses to allow the height of the inlet slot to be adjusted according to the viscosity of the mud that is to be used. 
     By virtue of the invention, it is possible very easily to set and adjust the height of the tape inlet and tape outlet slots, according to the viscosity of the mud, and according to user practices in terms of mud flow rate.