Abstract:
A dispenser of viscous fluid, in at least one embodiment a hot melt glue adhesive, has a heater element, an adhesive source, a main common passage, and a series of valves that all fluidly connect to the main passage. A sheet of receiving material, such as an envelope, has hot melt glue applied to its surface as it passes under the series of valves. A variable amount of valves can be activated by moving control rods inwardly or outwardly of the main common passage. The moving control rods have indicator markers, a securing screw and are housed in U-shaped beds which collectively make adjusting the dispensing pattern very easy.

Description:
The present application claims the priority of German Utility Model Application No. 202007002156.9 filed Feb. 9, 2007 under 35 U.S.C. §119. The disclosure of that priority application is hereby fully incorporated by reference herein. 
     TECHNICAL FIELD 
     The present invention generally relates to apparatus for applying fluids such as adhesive to a substrate movable relative to the apparatus. 
     BACKGROUND 
     Utility model specification DE202006014743U1 discloses an apparatus in which a length of a distributor passage, which can be acted upon with fluid, is varied with a closure body driven by way of a drive device. Drive devices which are typically used have a holding device, a screwthreaded spindle mounted in the holding device, a screwthreaded body and a guide rod for the screwthreaded body. The screwthreaded body is displaced along the guide rod by rotation of the screwthreaded spindle. The screwthreaded body is connected in positively locking relationship to the closure body, whereby the movement of the screwthreaded body is transmitted to the closure body. 
     In a first limit position the closure body is pushed to a minimum distance into the distributor passage and the screwthreaded spindle projects over almost the entire length out of the nozzle arrangement. In a second limit position, that is, in a position in which the length of the distributor passage and the nozzle opening is at its smallest, the closure body is pushed into the distributor passage by the maximum extent. In order to ensure mobility of the closure body between those two limit positions, the screwthreaded spindle must be at least as long as the part of the closure body that projects out of the distributor passage, when the closure body is in the first limit position. As the screwthreaded spindle must be supported and requires an engagement portion at its end remote from the distributor passage so that it can be rotated, additional structural space is required for the drive device. The drive device not only requires structural space in line with the longitudinal axis of the distributor passage but also in radial relationship therewith, in particular for the holding device for mounting the screwthreaded spindle. The fact that a relatively large amount of structural space is required for the drive unit of the closure body can have a disadvantageous effect. Thus, the extent of the drive device in the longitudinal direction of the closure body can be detrimental as the drive device can collide with adjoining machines such as labelling machines or can collide with walls of a room. 
     Therefore the object of the invention is to provide an apparatus which makes it possible for the applicator apparatus to be of a more compact structure but at the same time does not adversely affect the displaceability of the closure body. 
     SUMMARY 
     In one aspect, the invention provides a closure body that can be fixed in various positions by a fixing device. The fixing device performs the fixing function for the closure body. By virtue thereof a drive device, which moves the closure body, can be separated from the closure body without the closure body being able to move. Therefore, in the operating condition in which the fixing device fixes the closure body, the structural space occupied by the apparatus can be reduced, and this is advantageous in certain installation or operating situations. 
     The invention is distinguished in that the closure body may, for example, be a piston rod or may be movable by means of a piston rod. Piston rods are particularly well suited for sealing off a cylindrical passage or for displacement of a closure body fixed to the piston rod when the length thereof, that can be acted upon with fluid, is to be quickly and easily altered. 
     In accordance with a further aspect, the fixing device is in the form of a clamping device. The clamping device makes it possible to selectively enable or prevent the movement of the piston rod along the longitudinal axis of the distributor passage, reliably and at a relatively low level of structural complication and expenditure. 
     In another aspect, the clamping device includes a housing and a clamping element which is movable therein by means of a clamping screw and which embraces the piston rod. This provides a clamping device which is of a compact and simple structure and inexpensive to manufacture. 
     In another aspect, the clamping device is releasably connectable to the nozzle arrangement and/or the main body. The nozzle arrangement which is used as standard and/or the main body only have to be modified in such a way that the clamping device can be secured to them. Such a modification can involve the provision of screwthreads for screws, which would signify only minor interventions. No special manufactures of main bodies and/or nozzle arrangements are required for that purpose. In addition there is the advantage that the clamping device can be quickly assembled and rapidly replaced in the event of failure. The nozzle arrangement does not have to be separated from the main body for that purpose. 
     A further development provides that the drive device includes a holding device, a screwthreaded spindle mounted therein, a screwthreaded body, a guide rod and/or a latching engagement element. A drive device of such a structure manages without complicated, expensive parts which are susceptible to trouble. The individual elements involved are mass-produced items which are quickly available and inexpensive. The drive device according to the invention can be quickly assembled and dismantled again in a simple fashion. There is no need for special tools or especially trained operating personnel. 
     Preferably the individual parts of the drive device form an interconnected unit and are connectable as a whole releasably to the main body and/or the nozzle arrangement and the piston rod. Assembly and dismantling are further facilitated by virtue of that configuration of the drive device. The drive device can be completely assembled before it is mounted to the main body and/or to the nozzle arrangement. The same thing also applies to the situation where the drive unit is to be removed. That is advantageous insofar as the stoppage times of the applicator apparatus can be kept short, which in turn affords economic advantages. 
     It is further preferred if the drive device can be fixed with only one fixing element, in particular a screw to the main body and/or to the nozzle arrangement. By virtue of that design configuration the drive device can be even more quickly fitted to the main body and/or the nozzle arrangement and released again. The amount of time necessary for that purpose is further reduced. 
     In accordance with a further aspect of the invention the latching engagement element co-operates with the screwthreaded spindle in such a way that the piston rod is discontinuously displaceable in each case by the spacing of two adjacent mutually spaced outlet passages. Such a design configuration is preferred for the situation where the nozzle opening communicates with the distributor passage by means of a plurality of mutually spaced outlet passages and the fluid flow through the outlet passages can be selectively enabled or interrupted by means of the piston rod and the length of the distributor passage which can be acted upon with fluid is stepwise variable. The latching engagement element assists the operator who rotates the screwthreaded spindle in displacing the piston rod into the correct position in the distributor passage in order to prevent an outlet passage being only partially closed by the piston rod, which would have a detrimental effect on the pattern of adhesive applied to the substrate. 
     In a preferred configuration of the invention the piston rod has markings, the spacing of which corresponds to the spacing of two adjacent outlet passages. That configuration also relates to the situation where the nozzle opening communicates with the distributor passage by means of a plurality of mutually spaced outlet passages. The markings serve as a means for checking that the piston rod is in the correct position in the distributor passage and also that the latching engagement element and the screwthreaded spindle are correctly co-operating. In addition in that respect the markings help to be able to better determine the position of the piston rod in the distributor passage. Thus the markings can be consecutively numbered, whereby information can be afforded about the number of outlet passages acted upon with fluid and thus about the width of the pattern with which the adhesive is applied to the substrate. 
     In accordance with a further aspect of the invention the nozzle opening communicates with the distributor passage by means of a continuous slot and the length, which can be acted upon with fluid, of the distributor passage and of the nozzle opening is steplessly variable by means of the piston rod and a projection which can be secured thereto. In comparison with the structure in which the nozzle opening communicates with the distributor passage by means of a plurality of outlet passages, it is possible in this case for the width of the applied pattern of adhesive to be adapted with a high level of accuracy to the individual specifications of the substrate to be worked upon. 
     It is further preferred if the drive device has a lateral projection relative to the main body, which can be oriented in the same direction or the opposite direction to the nozzle opening. That selection option means that account can be taken of the particular factors involved at the location of installation of the drive device and the applicator apparatus. One orientation of the lateral projection or the other may be preferred, depending on how the substrate is respectively moved in relation to the nozzle opening. 
     At least one holding element can be mounted on the same side or the opposite side of the main body as the nozzle opening and/or the lateral projection of the drive device. 
     At least one holding element can be mounted to the main body on the same side as the nozzle opening or on the opposite side to the nozzle opening. 
     It is further preferred if the lateral projection of the drive device can be mounted to the main body on the same side as the nozzle opening or on the opposite side to the nozzle opening. 
     That configuration can also provide that the arrangement of the applicator apparatus and the drive device can be individually adapted to the factors involved at the location of installation. In particular the spacing of the applicator apparatus and/or the drive device relative to the substrate can be enlarged thereby. There is a reduced probability of the substrate coming into contact with the drive device and/or the applicator apparatus and of the substrate being damaged or destroyed. 
     Aspects of the invention are described in greater detail hereinafter by means of embodiments by way of example illustrated in the drawings in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1   a  is a side view of an applicator apparatus with a mounted drive device, the piston rod being in a first limit position. 
         FIG. 1   b  is a perspective view of the applicator apparatus with a mounted drive device, the piston rod being in the first limit position. 
         FIG. 2  is a perspective view of the apparatus with the drive device removed, and the piston rod being in the first limit position. 
         FIG. 3  is a perspective view of the apparatus with a partial block of the nozzle arrangement removed, and the piston rod being in a second limit position. 
         FIG. 4   a  is a side view of the apparatus with the piston rod in a second limit position with the drive device mounted thereto. 
         FIG. 4   b  is a side view of the apparatus with the drive device removed. 
         FIG. 5  is a partial section of the apparatus and a view on an enlarged scale of a clamping device. 
     
    
    
     DETAILED DESCRIPTION 
     The apparatus  10  shown in  FIGS. 1   a  and  1   b  serve for applying fluids such as adhesive, in particular hot melt adhesive, to a substrate which is movable relative to the apparatus  10  in the direction of the arrow P. The structure in principle of the apparatus  10  corresponds to that of an apparatus known from DE202006014743 and the disclosure thereof is hereby incorporated by reference. 
     The apparatus  10  has a main body  12  with a first end face  14  and a second end face  16 . On the first end face  14  an electropneumatically actuable valve  18  is connected to the main body  12 . As illustrated in this embodiment the first end face can have a partial region  14 ′ with an angular displacement in which the valve  18  is connected to the main body  12 . The valve  18  has a compressed air connection  20  for a supply with compressed air and a connection  21  for supplying electrical power. The apparatus  10  has an electrical connection  22  for supplying a heating cartridge (not shown) with electrical power and a hose connection  24  which can be connected to a fluid source (not shown) for the supply of fluid. The flow of fluid through the main body  12  can be selectively enabled or interrupted by means of the valve and an intermittent application of adhesive can be effected by way of a nozzle arrangement  26  communicating with the main body  12 . The nozzle arrangement  26  is connected to the main body  12  at the second end face  16  and includes a first partial block  34  and a second partial block  36  which form a substantially slot-shaped nozzle opening  27 . A cylindrical distributor passage  28  (see  FIG. 3 ) extends in the nozzle arrangement  26 , with a piston rod  30  being arranged movably in the distributor passage  28 . The piston rod  30  is displaceable in the distributor passage  28  by means of a drive device  32 . In the illustrated embodiment at the end disposed in the distributor passage  28  the piston rod  30  has a closure body  31  which seals off the distributor passage  28 . Alternatively, the closure body  31  can extend over the overall length of the piston rod  30 . The distributor passage  28  can be delimited and sealed off laterally by the two partial blocks  34 ,  36  and at the end faces thereof by a sealing plate  38  with a seal (not shown) and by a sealing first end  39  of the piston rod  30 . 
     The drive device  32  has a holding device  40 , a mounting plate  42  screwed thereto, a screwthreaded spindle  44 , a screwthreaded body  46 , a guide rod  47  and/or a latching engagement element  60 . The holding device  40  of the drive device  32  is connected to the main body  12  on a surface  41  by way of a securing portion  79 . Alternatively, the holding device  40  can also be connected to the nozzle arrangement and/or the main body  12 . 
     In the illustrated embodiment the mounting plate  42  is releasably connected in the form of a separate component to the holding device  40  but it can also be in the form of an integral constituent part of the holding device  40 . A screwthreaded spindle  44  is mounted rotatably by means of plain or roller bearings (not shown) between the mounting plate  42  and the surface  41 . The screwthreaded spindle  44  is connected to a screwthreaded body  46  which is supported displaceably on a guide rod  47  and which can be moved between the mounting plate  42  and the surface of the main body  12  along the longitudinal axis of the guide rod  47  by rotation of the screwthreaded spindle  44 . The screwthreaded body  46  is releasably connected to the piston rod  30 . In order to produce a connection which can be easily released, the screwthreaded body  46  has a recess  48  into which a portion  50  of the second end  52  of the piston rod  30  can be introduced, which is of a reduced diameter. The displacements of the screwthreaded body  46  in the direction of the longitudinal axis of the distributor passage  28  are transmitted from the screwthreaded body  46  to the piston rod  30  by positively locking engagement in the regions within which the diameter of the piston rod  30  is enlarged again at the two ends of the portion  50 . The screwthreaded spindle  44  is actuated by rotation of the latching engagement element  60 . Optionally the screwthreaded spindle  44  can be actuated by a suitable tool, for example a screw wrench, which is fitted on to an engagement portion  54  of the screwthreaded spindle  44 . That option presents itself for the situation where the latching engagement element is not accessible or is only accessible with difficulty. 
     When the piston rod  30  is in the desired position, that is to say the desired length of the distributor passage  28  which can be acted upon with fluid is reached, the piston rod  30  is fixed in its position by means of a clamping device  56 . That ensures that the piston rod  30  is not displaced even when fluids such as hot melt adhesive are conveyed under high pressure through the distributor passage  28 . 
       FIG. 2  shows the apparatus  10  according to the invention with the drive device  32  removed. The piston rod is in its first limit position in which the length of the distributor passage  28  which can be acted upon with fluid is at its maximum length. With the drive device  32  removed the piston rod  30  is no longer axially fixed in position by the screwthreaded body  46 . 
     In order to prevent the piston rod  30  from dropping out of the distributor passage  28  even in the situation where the drive device  32  has been removed without the clamping device  56  having been activated the diameter of the bore of the clamping device  56  with which it embraces the piston rod  30  is smaller than the diameter of the closure body  31 . 
     The individual parts of the drive device  32  form an interconnected unit which can be connected as a whole releasably to the main body  12  and/or the nozzle arrangement  26  and the piston rod  30 . The drive device  32  can be fixed with only one fixing element, in particular a screw, to the main body  12  and/or to the nozzle arrangement  26 . 
       FIG. 3  shows the apparatus  10  according to the invention with the drive device  32  removed, with the piston rod  30  in its second limit position. In that second limit position, the length of the distributor passage  28  which can be acted upon with fluid is at its minimum.  FIG. 3  shows the nozzle arrangement  26  with the second partial block  36  removed in order better to be able to demonstrate the position of the piston rod  30  in the distributor passage  28 . In addition it can be seen from  FIG. 3  that the nozzle opening communicates with the distributor passage  28  by way of a large number of outlet passages  58 . The advantages of that arrangement are described in detail in Utility model specification DE202006014743U1. 
     When the screwthreaded spindle is rotated by rotation of the latching engagement element  60  a biased ball of the latching engagement element  60  latches perceptibly into a part-spherical recess after a rotary movement of 360°. (see  FIG. 1 ). The pitch of the screwthread of the screwthreaded spindle  44  is so selected that a rotary movement of the screwthreaded spindle  44  through 360° causes axial displacement of the screwthreaded body  46  and thus also of the piston rod  30  by precisely the spacing of two adjacent outlet passages  58 . The piston rod  30  includes markings  61  in the form of grooves, the spacing of which precisely corresponds to the spacing of two adjacent outlet passages  58 . The markings  61  are so arranged that they are aligned with the top side of the clamping device  56  when the piston rod  30  has been displaced by the correct distance. Thus in addition to the latching engagement element  60  that arrangement provides a certainty that the piston rod  30  is in the correct position and for example the outlet passage  58 ′ adjacent to the first end  39  of the piston rod  30  is not partially closed. The consequence of that would be that an irregular application pattern of adhesive would be produced at the edge region, which is not desirable. 
     Alternatively the nozzle opening  27  can communicate with the distributor passage  28  over a continuous slot. In that case the length of the distributor passage  28  and the nozzle opening  27 , which can be acted upon with fluid, is variable steplessly by the position of the piston rod  30 . So that the length of the distributor passage  28  and of the nozzle opening  27 , which can be acted upon with fluid, are of equal magnitude and thus the fluid is not uncontrolledly distributed in the slot, a projection is fixed at the end of the piston rod  30 , which is in the distributor passage  28 . An end of the projection is aligned with the end of the piston rod  30  and extends as far as the nozzle opening  27 . That projection seals off the slot and delimits the length of the nozzle opening  27 , which can be acted upon with fluid. Such an arrangement can be seen in DE299 08 150 U1. 
     An end of a through bore  62  can also be seen in  FIG. 3 . The apparatus  10  is connected to a fluid source (not shown) by way of the hose connection  24 . Fluid is conveyed into the apparatus  10  by a conveyor unit (not shown), for example a pump. Adjoining the hose connection  24  is a bore (not shown) which passes through the main body  12  and which extends almost to an underside  68  of the main body  12 . A valve needle  64  of the electropneumatically actuable valve  18  engages into that bore and can open or close the bore. Depending on the respective position of the valve needle  64  therefore the flow of fluid is selectively enabled or interrupted. When the bore is opened the fluid flows further along the through bore  62  which opens into the distributor passage  28 . The fluid passes into the distributor passage  28  and acts thereon over the length which is predetermined by the piston rod  30 . By way of the outlet passages  58  communicating with the distributor passage  28 , the fluid goes to the nozzle opening  27  where it leaves the nozzle arrangement  26  and is applied to a substrate (not shown). 
       FIGS. 4   a  and  4   b  show the apparatus  10  according to the invention in such a way that the piston rod  30  is in its second limit position. The drive device  32  is fitted in  FIG. 4   a  whereas it has been removed in  FIG. 4   b . The region of the nozzle opening  27  is almost freely accessible when the drive device  32  is removed. 
     The clamping device  56  is shown in greater detail in  FIG. 5 . The clamping device  56  has a housing  66  which is releasably connected to the nozzle arrangement  26  and/or the main body  12 . The housing  66  has a U-shaped opening  70  which embraces the piston rod  30 . A substantially cylindrical clamping element  72  is arranged movably in a bore  74  extending from the opening  70  into the interior of the housing  66 . That clamping element  72  has a perpendicular bore  84  with which it completely embraces the piston rod  30 . In addition a female screwthread into which a clamping screw  76  engages is disposed in the clamping element  72 . The clamping screw  76  can be rotated by way of a hexagonal socket recess and bears with its head against a base surface of a countersink in the housing  66 . Depending on the respective direction in which the clamping screw  76  is rotated the clamping element  72  is moved towards or away from the screw head and thus the piston rod  30  is clamped or released. 
     After the piston rod  30  has been moved into its desired position the clamping screw  76  is tightened and the piston rod  30  is fixed in its position. The drive device  32  is separated from the main body  12  by releasing only one fixing screw  78 . In order to facilitate access to the screw  78  a securing portion  79  is mounted to the holding device  40  of the drive device  32 . The screwthreaded body  46  can also be quickly released from the piston rod  30  by the released drive device  32  being moved away from the free end of the opening in the screwthreaded body  46 . The diameter of the bore  84  is selected to be smaller than that of the closure body  31 . That prevents the piston rod  30  from being able to drop out of the distributor passage  28  if the clamping element  56  cannot fix the piston rod  30 , either by virtue of failure of the clamping element  56  or due to incorrect operation, for example if the clamping screw  76  was not tightened or was not adequately tightened. After dismantling of the drive device  32  the nozzle opening is freely accessible, in particular the lateral projection portion  80  which in the assembled condition of the drive device  32  causes difficulty in gaining access to the nozzle opening  27  and thus in substrate guidance is removed. 
     While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The various features disclosed herein may be used alone or in any combination depending on the needs and preferences of the user. The scope of the invention itself should only be defined by the appended claims.