Abstract:
The invention relates to an elongated, preferably cylindrical plunger located in a chamber of a cartridge gun for the expression and dosed application of a free-flowing, paste-like substance. The exterior of the plunger comprises two seals that are preferably located in a peripheral groove. To express the contents of fixed cartridges, the plunger is equipped with an additional peripheral sealing ring for sealing purposes.

Description:
TECHNICAL FIELD  
       [0001]     The invention relates to a device for the expression and dosed application of a flowable paste-like substance, such as a adhesive/sealing substance, comprising a housing, an accommodating chamber provided for a disposable substance pack and adapted to be opened on at least one end thereof, a discharge nozzle, and a plunger arranged on the other end of the accommodating chamber and being displaceable in the direction of the discharge nozzle, the plunger being operative to directly or indirectly press out the paste-like substance from the discharge nozzle in that the plunger is subjected to a corresponding pressure by use of pressurized air which is generated by a compressor driven by an electric motor connected to an accumulator.  
       STATE OF THE ART  
       [0002]     A device of the above type for the expression and dosed application of a flowable substances is described e.g. in European Patent Application EP 0 998 983 A2. A further device of this type is described in European Patent Application EP 0 490 555 A1 wherein, however, in contrast to the above mentioned device, the pressure required for pressing out the flowable substance is generated by an inserted CO 2  cartridge instead of using a compressor integrated into the device.  
         [0003]     A disadvantage of these known devices resides in that, when film tubes are used in case of disposable substance packs, the pressing process will cause parts of the film tube to be squeezed in between the flat plunger and the inner wall of the accommodating chamber containing the substance packs so that the plunger can be moved on, if at all, only by applying a high pressure to it.  
         [0004]     In so-called rigid cartridges wherein the substance to be pressed out is accommodated in a container of a circular cylindrical shape, it frequently happens that the container end facing away from the discharge nozzle has been more or less damaged so that a considerable part of the applied pressurized air will deflagrate without effect and the paste-like substance can thus not be pressed out. Consequently, such a cartridge can normally not be used and will have to be discarded. Further, it will occur ever again that paste-like substance escapes into the cartridge press-out device, entailing the necessity of a time-consuming cleaning process performed on the device.  
       SUMMARY OF THE INVENTION  
       [0005]     In view of the above, it is the object of the invention to provide a tool in the form of a device for the expression and dosed application of a flowable paste-like substance, such as an adhesive/sealing substance, in such a manner that it can be handled easily and safely, that the paste-like substance can be applied in an unobjectionably uniform manner and that the tool is suited for continuous operation. Further, the tool according to the invention shall be adapted to press out tubular cartridge packs as well as rigid containers of a circular cylindrical shape.  
         [0006]     According to the invention, the above object is achieved, in a device for the expression and dosed application of a flowable paste-like substance according to the preamble of claim  1 , by the features mentioned in the characterizing part of claim  1 .  
         [0007]     According to the invention, an elongate plunger provided with two continuous seals on its outer side is arranged for free movement within the accommodating chamber of the device for the expression and dosed application of a flowable paste-like substance. Preferably, in this arrangement, each of the two seals is accommodated within a continuous groove in the region of both ends of a circularly cylindrical plunger.  
         [0008]     By providing the plunger as an elongate body, a tilting and resultant jamming of the plunger is precluded. Further, by the continuous seals of the elongate plunger which are arranged in abutment on the inner wall of the accommodating chamber, it is safeguarded that no pressurized air can escape between the plunger and the accommodating chamber.  
         [0009]     To be able to press out the paste-like substance from a rigid cartridge in a uniform manner, the upper side of the plunger facing towards the cartridge container is provided with a continuous sealing ring.  
         [0010]     The plunger has formed therein an e.g. circularly cylindrical or e.g. frustoconical or otherwise shaped pressure chamber merging into a centrally arranged connector piece having a continuous axial bore therein. For using the inventive device also for pressing out paste-like substances contained in film bags, the continuous axial bore can be closed by a cap nut.  
         [0011]     To make it possible that, even in case of damaged plastic containers, it is on the one hand safely precluded that pressurized air can escape between the container and the inner wall of the accommodating chamber and it is on the other hand prevented that, in case of more or less heavily damaged containers, the paste-like substance is urged back into the container while massively contaminating the same, the invention provides the use of a dome-like cap of an elastic rubbery material. In this manner, an absolutely tight closure of the cartridge container is effected, and an undesired leakage of paste-like substance is reliably prevented.  
         [0012]     To be able to reliably and safely press out paste-like substances contained in film bags, there is provided, according to an advantageous embodiment of the invention, a disk of a diameter corresponding to the cartridge accommodating chamber and formed with a number of radial recesses and with a central opening having a diameter substantially corresponding to the diameter of the axial bore in the connector piece. By way of alternative to the above described disk, use can be made of a circularly cylindrical crown made of elastically resilient material and comprising a number of axial recesses.  
         [0013]     Further embodiments and variants of the device according to the invention are indicated in the further claims. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0014]     In the drawings as listed hereunder, the following is shown:  
         [0015]      FIG. 1  is a simplified, schematic, perspective general view of a device for the expression and dosed application of a flowable paste-like substance;  
         [0016]      FIGS. 2   a  and  2   b  are a perspective view of an elongate plunger and a sectional view thereof, respectively, said views being not true to scale;  
         [0017]      FIG. 3  is a sectional view of a rod;  
         [0018]      FIGS. 4 and 5  are views of a disk and of a crown-like member of elastically resilient material, respectively;  
         [0019]      FIGS. 6   a  to  6   c  are views of a dome-like cap prior to mounting to a damaged rigid cartridge ( FIG. 6   b ), during the mounting ( FIG. 6   c ) and after the mounting ( FIG. 6   a );  
         [0020]      FIG. 7  is a sectional view of a novel compressor;  
         [0021]      FIG. 8  is a view of a device for the simultaneous expression and dosed application of two different paste-like substances;  
         [0022]      FIG. 9   a  is a perspective view of a heating means for use in devices for the expression of paste-like substances;  
         [0023]      FIG. 9   b  is a view of a heating means mounted to an expression device, and  
         [0024]      FIGS. 10 and 11  are views of “cartridge press-out devices” with one or several commercially available CO 2  cartridges connected thereto. 
     
    
     DESCRIPTION OF THE INVENTION  
       [0025]     A tool in the form of a device for the expression and dosed application of a paste-like substance comprises a housing, generally designated by reference numeral  1 , which at lower portion thereof is provided with a detachable accumulator  2  and which on the top is provided with an accommodating chamber  3  for film bags or cartridges filled with a paste-like substance. Integrated into housing  1  is an electric motor having connected thereto a commercially available small-sized compressor  5  which is connected to the cartridge accommodating chamber via tubes or hoses  6 . At an intermediate position, an electric valve  7  is arranged for pressure release, which valve is operable by a switch  14 . As an alternative to the electric valve, a mechanical discharge valve can be integrated into switch  14 .  
         [0026]     For closing the accommodating chamber  3 , there is provided a cap nut  8  formed with a small central opening leading into a projecting discharge nozzle  9  or into a projecting discharge nozzle  51  of the cartridge itself, the latter nozzle being not shown (see  FIG. 6   c  instead). Further, an on/off switch  11 , a pressure regulator  12  and a back-check valve  13  are provided.  
         [0027]     The cartridge accommodating chamber  3  is designed as a pressure chamber accommodating an elongate plunger  15  ( FIG. 2   a ) arranged for free movement in the longitudinal direction of accommodating chamber  3 . As evident from the sectional view of  FIG. 2   b , in the region of the two ends of plunger  15 , seals  16  are provided which preferably are arranged in grooves, the latter not shown in greater detail. By the two continuous seals  16 , the elongate plunger  15  is sealed in two regions against leakage of pressurized air. Thus, by means of plunger  15 , so-called cartridge bags can be pressed out. To make it possible that paste-like substances can be pressed out from rigid cartridge containers in an unobjectionable manner, an additional continuous sealing ring  17  is provided on the upper side of plunger  15 .  
         [0028]     Internally of the plunger, a pressure chamber  15   1  is formed which in  FIG. 2   b  substantially has the shape of a circular cylinder. Alternatively, the pressure chamber can also have a substantially frustoconical shape as well as any other desired shape. As further evident from  FIG. 2   b , pressure chamber  15 , merges into a centrally arranged connector piece  20  provided with a continuous axial bore  19  extending centrally therethrough. The upper portion of connector piece  20  is formed with an external thread which is adapted, as indicated in  FIG. 2   a , for threaded engagement with a cap nut  18  which, to accomplish a reliable sealing effect, is provided with an inner sealing, not specifically shown. For pressing out paste-like substance from a rigid cartridge container, cap nut  18  must be screwed into place.  
         [0029]     Additionally, to safeguard that paste-like substance contained in film bags is correctly pressed out, a disk  24  of elastically resilient material is provided as schematically illustrated in  FIG. 4 , said disk being formed with a central opening  24   2  adapted to the outer diameter of connector piece  20 , and with a number of radial recesses  24   1 .  
         [0030]     By the provision of disk  24 , it is precluded that that, when pressing out paste-like substance from a film bag, parts of the bag being pressed out may enter the space between the plunger  15  and the inner wall of accommodating chamber  3 . For the same purpose, use can be made also of a circularly cylindrical crown  25 , shown in  FIG. 5 , in which a number of radial slots  25   1  are formed.  
         [0031]     In order to prevent, in rigid cartridge containers  50  wherein the edge opposite the discharge nozzle  51  has been damaged, that pressurized air will escape between the cartridge container and the accommodating chamber, there is provided, according to an advantageous embodiment of the invention, a dome-shaped cap  23  made of an elastic rubbery material and having a central opening  23   1 . Damages of the type referred to above are schematically indicated in  FIGS. 6   b  and  6   c  on the upper edge of cartridge container  50 .  FIG. 6   c  further schematically indicates the manner in which the dome-shaped cap  23  can be pulled over the damaged end of a cartridge container  50 .  FIG. 6   a  illustrates a cap  23  as correctly mounted. To prevent contamination of paste-like substance which occasionally happens to leak out of a rigid cartridge container, it has been proven useful to mount the dome-shaped cap  23  even in case of undamaged or only slightly damaged cartridge containers.  
         [0032]     For the practical use of a device for the expression and dosed application of a paste-like substance, the following process is provided. Prior to insertion of a rigid cartridge  50  with discharge nozzle  51 , the cap nut  8  has to be screwed off, and the cartridge  50  will be inserted and the cap nut  8  will be screwed on again. By actuating the on/off switch  11 , the electric motor  4  driving the compressor  5  will be switched on. Thus, pressurized air will be generated and be supplied via the tube or hose conduits  6  into the rear part of the cartridge accommodating chamber  3 .  
         [0033]     When the obtained pressure is large enough, an adhesive bead is pressed in a uniform manner from the cartridge discharge nozzle  51 . Upon release of the switch  11 , the back-check valve  13  prevents a return flow of pressurized air back into the compressor  5 . However, the pressure will slowly decrease, and the discharge of the adhesive bead is decelerated down to the point of standstill. If it is desired to bring the adhesive bead to a standstill immediately, a discharge valve can be opened by actuation of an additional switch  14 . The pressure can be suitably adjusted, i.e. increased or decreased, by means of pressure regulator  12  so that the adhesive bead will be pressed out at a higher or lower speed.  
         [0034]     Depending on the type of the cartridge used, a different technical process will have to be performed. When using a film bag, the cap nut  18  has to remain on the plunger  15 . Thus, the axial bore  19  remains closed, and pressure is built up in the pressure chamber  15   1  of the plunger. When a predetermined pressure is reached, the plunger  15  is pushed forwards. Thereby, the film bag is pressed together, and the adhesive/sealing substance is pressed out via the discharge nozzle  9 .  
         [0035]     When using a rigid cartridge, i.e. a cartridge comprising a rigid container, the cap nut  18  in the center of the plunger has to be removed so that the connector piece  20  projecting slightly above the plunger  15  and provided with the continuous axial bore  19  will be exposed. During the insertion of the rigid cartridge, the protective film provided at the rear end will be perforated, thus offering access to the cover of the actual adhesive substance. The pressurized air built up in the pressurized air chamber  15   1  of plunger  15  will flow through the axial bore  19  and build up a corresponding pressure behind the cartridge  50 . Thereby, the adhesive substance will be pressed in the forward direction out of the cartridge discharge nozzle  51 .  
         [0036]     In situations where, after use of a rigid cartridge, a film bag or cartridge bag shall be used, the following problem arises. The plunger  15  has taken a fully rearward position and can be moved to the forward position by pressurized air only after the axial bore  19  will have been closed. Since, however, in this position of the plunger  15 , the cap nut  18  cannot be screwed on, the bore/opening  19  will first be closed with the aid of a correspondingly long rod  40  having a recess  41  on one end; at the same time, the device will be switched on. By the developing pressure, the plunger  15  is slowly advanced far enough in the forward direction for allowing the cap nut  18  to be screwed on.  
         [0037]     With reference to  FIG. 7 , a compressor  30  will be described hereunder which can be used in an advantageous manner in the device of the invention, particularly in situations where a larger quantity of pressurized air is required for dosed expression of two cartridges at the same time. The novel compressor  30  comprises a cylinder  31  having one of its ends supported in a fixed position; in the sectional view of cylinder  31 , this support is schematically marked by an encircled cross above reference numeral  32 .  
         [0038]     Two mutually opposite end portions  32  and  33 , exemplified as formed by the bottom and the cover of the cylinder, are provided with respective inlet openings  32   1  and  33   1 , respectively, and outlet openings  32   2  and  33   2 , respectively. The inlet openings  32   1  and  33   1  have assigned thereto a respective inlet valve  32   11  or  33   11 , while the outlet openings  32   2  and  33   2  have assigned thereto a respective outlet valve  32   21  or  33   21 .  
         [0039]     A piston  37  is connected via a piston rod  38  to an eccentric disk  39  which in turn is driven by a pinion  41  provided on the output shaft of a motor  40 . In the rotational direction indicated by an arrow on eccentric disk  39 , piston  57  is driven in the direction indicated by an arrow to the right-hand side in  FIG. 7 . When this movement of piston  37  takes place, inlet valve  33   11  is opened, and through outlet valve  32   21  pressurized air is led via a connection member  34  into a pressurized air conduit  36 .  
         [0040]     After reaching the dead center located on the left side in  FIG. 7 , piston  37  is moved to the left whereby inlet valve  33   11  and outlet valve  32   21  will be closed and inlet valve  32   11  and outlet valve  33   21  will be opened. Thereby, air is conveyed via a connection member  35  into the same pressure line  36 . This means that, at each rotation of eccentric disk  39 , piston  37  will perform a dual stroke so that, as compared to the conventional compressors used up to now, twice the previous air quantity will be conveyed.  
         [0041]     If, as in the embodiment illustrated in  FIG. 8 , a device for the expression and dosed application of a paste-like substance is provided with two accommodating chambers  3   1  and  3   2 , one of the accommodating chambers, e.g.  3   1 , can accommodate a cartridge filled with adhesive, and the other accommodating chamber  3   2  can accommodate a cartridge filled with a hardener. As soon as the compressor  30  has built up a suitable pressure, e.g. identical quantities of the substance can be squeezed out from both cartridges; subsequently these quantities will be mixed in a discharge nozzle  9   1  and be applied as an adhesive bead to the desired site. The pressurizes air required for simultaneously pressing out the contents of two cartridges can be generated by the compressor  30  described with reference to  FIG. 7 .  
         [0042]     The effort to perform as many processes as possible in a more rapid manner has led to the development of a sealing/adhesive substance adapted to harden quickly. However, a disadvantage of this product resides in that this material is very hard at the usual ambient temperatures. To lend the material the required flowability for processing, the material has to be heated correspondingly. Up to now, for this purpose, the above-mentioned quick-hardening sealing/adhesive substance has been heated in separate heating means until reaching the flowability necessitated for discharging it.  
         [0043]     After the sealing/adhesive substance had been sufficiently heated, the cartridge was removed from the heating means and introduced into the not preheated and thus comparatively cool “cartridge press-out device”. Consequently, in many cases, the heated substance happened to cool down so very rapidly that it had to be removed from the cartridge press-out device before termination of the respective working step and had to be heated again, which course took a corresponding length of time.  
         [0044]     To abbreviate the heating of this quick-hardening sealing/adhesive substance, there has been developed a novel detachable heater device  60  surrounding the accommodating chamber of a cartridge press-out device ( FIG. 9   a ). This heater device  60  comprises two mutually attached circularly cylindrical heater bodies  61 , 62  foldable into an opened position. Each of the two heater bodies  61 , 62  comprises two double-walled half shells  63  and  64  which form a respective circularly cylindrical hollow body and are articulated to each other. Arranged internally of the double-walled heating shells  63  and  64  are heating wires which can be energized by an accumulator or by the power network.  
         [0045]     The embodiment illustrated in  FIGS. 9   a  and  9   b  is provided with a mains plug  67  with integrated transformer for reducing the voltage. Further, an on/off switch  66  is provided in half shell  64 . The two heater bodies  61 , 62  are connected to each other by a connection cable  65  reinforced by e.g. steel mesh.  
         [0046]     In  FIG. 9 , the novel heater device  60  is shown to surround the accommodating chamber of a schematically illustrated cartridge press-out device. A cartridge filled with a hard adhesive/sealing substance can be inserted into a cartridge press-out device equipped in the above manner so as to bring the substance to the operating temperature at which it is flowable.  
         [0047]     During the length of the heat-up process, which—depending on the respective ambient temperature—can be in the magnitude of e.g. 10 to 15 minutes, corresponding preparatory measures can be taken during the heating of the adhesive/sealing substance.  
         [0048]     Since, simultaneously with the heating of the adhesive/sealing substance, the cartridge press-out device is heated along with the substance, it is guaranteed that a longer working process can be completely performed without the danger of the adhesive substance cooling down so massively that the working process has to be interrupted. Therefore, using the novel heater device  60 , the process of applying the adhesive substance in the form of an adhesive bead can be considerable abbreviated, and the pressing-out and dosed application adhesive/sealing substance can thus be performed within a considerably shorter time period.  
         [0049]     In  FIGS. 10 and 11 , “cartridge guns” are shown wherein, instead of a compressor, at least one commercially available CO 2  cartridge is connected via a pressure reducer  21 . In the embodiment shown in  FIG. 11 , two commercially available CO 2  cartridges  22  are mounted in the accommodating chamber  3  of a corresponding “cartridge gun” and connected to the “cartridge gun” via a hose connection  26  and a pressure reducer  21 .  
       LIST OF REFERENCE NUMERALS  
       [0000]    
       
           1  housing  
           2  accumulator  
           3  accommodating chamber  
           4  electric motor  
           5  small-sized compressor  
           6  tubes/hoses  
           7  electric valve  
           8  cap nut  
           9  discharge nozzle  
           11  switch  
           12  pressure regulator  
           13  back-check valve  
         
           12 
         
           14  switch  
           15  plunger  
           16  seal  
           17  sealing ring  
           18  cap nut  
           19  bore  
           20  connector piece  
           20   1  external thread  
           21  pressure reducer  
           22  cartridge  
           23  cap  
           23   1  opening in  23   
           24  disk  
           24   1  radial recesses  
           24   2  central opening in  24   
           25  crown  
           25   1  recesses in  25   
           26  hose connection  
           30  compressor  
           31  cylinder  
           32 , 33  end portion of  31   
           32   1 , 33   1  inlet  
           32   2 , 33   2  outlet  
           32   11 , 33   11  inlet valve  
           32   21 , 33   21  outlet valve  
           34 , 35  connection member  
           36  pressure line  
           37  piston  
           38  piston rod  
           39  eccentric disk  
           40  electric motor  
           41  pinion  
           45  rod  
           46  recess in  40   
           50  cartridge container  
           51  discharge nozzle on  50   
           60  heater device  
           61 , 62  heater bodies  
           63 , 64  double-walled half shells  
           65  connection cable  
           66  switch  
           67  mains plug with integrated transformer