Abstract:
An apparatus for applying fluid to a substrate which is movable relative to the apparatus. A slotted nozzle assembly of the apparatus communicates with a fluid supply and includes an elongated slot with an outlet aperture. The length of the slot may be varied using a stopper which can move in the slot and seal it off laterally. In another aspect, the entire slot can be shifted and fixed in the direction of the longitudinal axis of the slot using a guiding and adjusting device.

Description:
The present application is a continuation of PCT Serial No. PCT/EP00/04137 filed on May 9, 2000, published on Nov. 16, 2000, which claims the priority of German patent application No. 299 08 150.8, filed on May 10, 1999. The disclosures of each of these prior related applications are hereby fully incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention pertains to an apparatus for applying fluid to a substrate which is movable relative to the apparatus, in particular for applying adhesive to various substrates. 
     BACKGROUND OF THE INVENTION 
     Dispensing apparatus relevant to this invention are often referred to as applicator heads, and are used in various areas of industry in order to apply adhesives or other fluids to the surface of various substrates such as films, foils, or packaging materials. The applicator head may be mounted on a frame, and the substrate is typically moved past the applicator head by a transport device. In operation, the fluid may discharge from an elongate outlet aperture of a slot. 
     JP 05200346 (patent abstracts of Japan) describes a slotted nozzle coating apparatus with a slot for emitting coating material. The width of the slot can be adjusted on both sides by introducing so-called stoppers. 
     To vary the length of the slot in the slotted nozzle assembly and thereby vary the width of adhesive or other fluid application, it has been suggested that movable stoppers be placed on both lateral end sections of the slot, which can be shifted in the slot and held in various positions which limit the slot laterally. In this way the width of fluid application can be reduced on both sides, starting from a maximum fluid application width. 
     There is still a need for a fluid dispensing apparatus of this general type which has a more efficient and easily used design to provide for variation of the application width and adaptation to various application conditions. 
     SUMMARY OF THE INVENTION 
     The invention uses a simple design not only to enable varying the length of the slot in the slotted nozzle assembly, but also to shift the entire application head if needed, in order to be able to align the application head precisely in reference to various substrates which are transported past it. The apparatus in accordance with the invention has several adjustment options. By sliding the entire main body in the direction of the longitudinal axis of the slot and at the same time shifting the stopper in the same direction, the width of application remains constant and the slotted nozzle assembly is shifted together with the application head relative to a substrate while the length of the slot remains constant, so that the width of application remains the same and the slotted nozzle assembly can be positioned exactly with respect to the substrate. Alternatively, the slotted nozzle assembly can be shifted by using a guiding and adjusting device, while the stopper which is positioned movably in the slot and seals it laterally does not change its position, relative to a fixed-position frame of a production facility, but only changes its position relative to the slotted nozzle assembly of the application head. The length of the slot is reduced in this case and one lateral margin of the slot changes its position relative to the substrate. Alternatively, the stopper which is movable within the slot can be moved in the slot with the help of an adjusting device, while the main body remains stationary relative to a fixed-position frame, so that the length of the slot is varied and one lateral end section of the slot changes its position while the other end section of the slot retains its position. 
     The apparatus in accordance with the invention thus makes much more varied adjustment of the width of the slot and position of the slot possible relative to a substrate, compared to the state of technology. The two lateral margins of the slot can be varied and the entire slotted nozzle assembly can be moved. 
     A preferred implementation of the invention is distinguished by the fact that the guiding and adjusting device has several linear guides, preferably having rollers, so that simple shifting is possible with little force and a rigid arrangement of the application head is assured when it is in its fixed state. 
     In an especially preferred way, the guiding and adjusting device is designed with a rotatable threaded spindle and a threaded piece located on the main body and engaging the threaded spindle, so that reliable and precise adjustment is possible with simple design. Alternatively, a ball screw spindle could be used. It is useful for the threaded spindle to be coupled with a hand wheel for manually moving the main body, whereby simple and precise repositioning is possible. 
     According to an alternative preferred implementation, the stopper, which can move in the slot, is rigidly connected to a piston which is positioned movably and sealed in a distribution passage which communicates with the slot. It is useful for the stopper and the piston to be movable by means of a shared slot adjusting device. With the help of the piston which is positioned movably in the distribution passage and the stopper, the distribution passage is varied laterally—together with the slot length. Furthermore, fluid is fully squeezed out of the distribution passage, so that no fluid residues collect, a factor which is especially important when processing adhesives. Furthermore, with the help of the piston and the stopper the apparatus can be cleaned and adhesive can be pressed out of the slot and the distribution passage when operation is interrupted for an extended time, so that no hardening of the adhesive occurs. 
     A refinement of the invention is designed with the adjusting device having a threaded spindle mounted so that it can turn, and a threaded sleeve which is rigidly connected to the piston and engages the threaded sleeve. Preferably the threaded spindle of the adjusting device is coupled with a hand wheel for manual adjustment. 
     Especially simple handling of the application head in accordance with the invention is achieved by having the hand wheel of the guiding and adjusting device and the hand wheel of the slot adjusting device positioned parallel, side-by-side on one side relative to the main body and the threaded spindles, since the guiding and adjusting device for the main body and the slot adjusting device can be operated from one side, even while the device is in operation during application. 
     According to a refinement there is a substrate guiding device, having a frame which can be caused to rotate on the main body by means of a pneumatic cylinder and two elongated guide elements mounted on the frame parallel to the slot, and the guide elements for their part are arranged so that they can be rotated or fixed jointly relative to the frame. 
     Because the frame can be rotated relative to the main body on the one hand, and because on the other hand the two guide elements which are in contact with the substrate are arranged so that they can be fixed or rotated relative to the frame, in operation the substrate is positioned optimally relative to the outlet aperture of the slot in the slotted nozzle assembly and guided past it so that optimal application of fluid is achieved. In an especially simple design, the guide elements are designed as guide rods with a polished surface. Alternatively, the guide elements could be constructed as rotatable shafts in order to reduce the friction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other objects, advantages, and features of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description of the preferred embodiments, taken in conjunction with the accompanying drawings. 
     FIG. 1 is a side view of an illustrative apparatus in accordance with the invention for applying adhesive; 
     FIG. 2 is a top view of the apparatus from FIG. 1 partially sectioned to show certain inner details; 
     FIG. 3 is a side view of the apparatus taken along line  3 — 3  of FIG. 1; 
     FIG. 4 is another side view of the apparatus taken along line  4 — 4  of FIG. 1; 
     FIG. 5 is a side view of part of the apparatus in accordance with the invention; 
     FIG. 6 is a top view of a substrate guiding device; 
     FIG. 7 is a side view of the substrate guiding device from FIG. 6; and 
     FIG. 8 is another side view of the substrate guiding device. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Apparatus  1  shown in the figures applies fluid on a substrate (not shown) which is movable relative to the apparatus  1 . Typically, the substrate may comprise sheets of film or foil which are transported past the apparatus  1 . Of course the surfaces of other substrates could also be coated, such as packaging material or other materials. 
     Referring to FIG. 1, Apparatus or applicator head  1  has a main body  2  and a fluid supply passage  4  which can be connected to a source of adhesive (not shown). The fluid supply passage  4  can be in the form of a cylindrical hole bored in the main body  2  and is supplied with fluid, such as adhesive, through a supply passage, such as in a flexible adhesive line (not shown). The main body can have an upper part  3  and a lower part  5  which are threaded together. There is a cylindrical distribution passage  6  inside the main body  2 , which like the fluid supply passage  4  extends the entire length of the applicator head  1 . The distribution passage  6  is formed half as a semi-cylindrical recess in the upper part  3  and the other half as a semi-cylindrical recess in the lower part  5 , so that the distribution passage  6  can easily be cleaned other shapes may be used instead. The distribution passage  6  communicates with a horizontal slot  8  in a slotted nozzle assembly  10 . The slot  8  opens into an elongated outlet aperture  12 , from which adhesive flows during operation and is then transferred to the substrate. 
     Above the fluid supply passage  4 , attached to the main body  2 , there are six application valves  14  for selectively stopping and starting the flow of adhesive from the fluid supply passage  4  into the distribution passage  6  and thus through the slot  8 . Of course, other manners of controlling the fluid flow may be used instead. In this implementation example, and as those of ordinary skill will understand, each application valve  14  is designed as a pneumatically operable valve and has a needle  16  which is coupled with a pressurized gas piston that is positioned for movement in a cylinder, and can be moved up and down when pressure differences are applied to the piston. The lower section of the needle  16  interacts with a valve seat which is formed on the main body  2 . In the immediate vicinity of the valve seat, between the fluid supply passage  4  and the distribution passage  6 , there is a vertical connecting hole, which is closed by the point of the needle  16  when the application valve is in the closed position and is open when the needle  16  is in the open position. Each application valve  14  has a connecting hole associated with it. In a manner which is not shown, the application valves  14  are connected to pressurized gas lines. 
     As FIGS. 2 and 3 illustrate, a stopper  18  is positioned movably in the slot  8  of the slotted nozzle assembly  10  and seals off the slot  8  laterally. The stopper  18  is rigidly coupled with a cylindrical piston  20 , which is axially movable within the distribution passage  6 . The stopper  18  extends from the piston  20  to the outlet aperture  12  of the slotted nozzle assembly  10 . The piston  20  has an outer jacket  22 , which is attached to a threaded sleeve  24 . 
     The threaded sleeve  24  is part of an adjusting device  26 , for varying the length of the slot  8  by shifting the stopper  18  in the slot  8  together with the piston  20  in the distribution passage  6 . The adjusting device  26  also has a threaded spindle  30  which is mounted by two ball bearings  28  so that it can rotate. Male threads of spindle  30  engage female threads of the threaded sleeve  24 . The ball bearings  28  are set into a plate  32 . Attached to the end of the threaded spindle is a hand wheel  34  for manually turning and adjusting the adjusting device  26 . Turning the hand wheel  34  rotates the threaded spindle  30 , causing the threaded sleeve  24 , the piston  20  and the stopper  18  to be moved axially in the direction of the longitudinal axis of the slot  8  and of the distribution passage  6 , so that depending on the direction in which the hand wheel  34  is turned the length of the slot—viewed in the longitudinal direction of the application head  1 —is reduced or increased, and thus is variable. Those of ordinary skill will recognize that other mechanisms may be used to provide axial movement of such a stopper  18 . 
     The main body  2 , and with it the entire application head  1 , is mounted so that it can be moved back and forth relative to a fixed-position frame in the direction of the longitudinal axis of the slot  8  of the slotted nozzle assembly  10  and fixed in different positions by a guiding and adjusting device. The guiding and adjusting device has two supports  36  which can be attached to a frame of a production apparatus (not shown) and attached to them two mutually parallel cylindrical guide rods  38 ,  39 , and surrounding the guide rods  38 ,  39  the linear guides  40 ,  42 ,  44 ,  46 ; these have several rollers which roll along the guide rods  38 ,  39 . The lower section of the main body  2  is screwed together with the linear guides  40 ,  42 ,  44 ,  46 . That enables the main body  2  to move linearly along the longitudinal axes of the guide rods  38 ,  39 . The guide rods  38 ,  39  have their end sections connected to the supports  36  by screws, as shown in FIG.  1 . The linear guides are screwed to the main body  2  of several angle sections. 
     The guiding and adjusting device also has a threaded spindle  50  with male threads which is mounted in the plate  32  with ball bearings so that it can rotate, as well as a threaded piece with female threads which is engaged with the male threads of the threaded spindle  50  and is screwed to an angle section  48  (see FIG.  1 ). Turning a hand wheel  54  which is coupled with the threaded spindle  50  causes the main body  2  and thus the entire application head  1  to move back and forth linearly depending on the direction of rotation of the hand wheel  54 . The maximum travel displacement depends on the length of the guide rods  38 ,  39 . The main body  2  is fixed in any position desired by the friction between the male threads of the threaded spindle  50  and the female threads of the threaded piece  52 . The hand wheels  34  and  54  and the threaded spindles  30  and  50  are positioned on one side relative to the main body  2 , so that they can be operated simply from one side in order to vary the length of the slot  8  and the position of the main body  2 , and thus of the application head  1 . 
     FIGS. 3 to  8  illustrate a substrate guiding device for transporting a sheet of film or foil or the like past the outlet aperture  12  of the slotted nozzle assembly  10  along a defined travel path. The substrate guiding device has a frame  58  which is mounted on the main body  2  so that it can be rotated by two pneumatic cylinders  56 , and two parallel guide elements  60 ,  62  with a space between them, designed as guide rods with a polished surface, which can be rotated simultaneously and fixed in various rotated positions. 
     The two guide rods  60 ,  62  are mounted by their end sections on two plates  64 ,  66 , which can be rotated around a rotational axis  68  (see FIG. 7) relative to the frame  58 . It can be seen from FIGS. 3 and 5 that the frame  58 , the plates  64 ,  66  and the guide elements  60 ,  62  can be rotated with the help of the pneumatic cylinder  56  from a first diverted position to a second operating position, and the substrate can be moved past the outlet aperture  12  by adjusting the rotational position of the plates  64 ,  66  and fixing them with screws in an optimal position for guiding the substrate according to the needs of the application. Alternatively, instead of the guide elements  60 ,  62  there can be a pressure roller opposite the outlet aperture  12 . 
     While the present invention has been illustrated by a description of a preferred embodiments and while these embodiments have been described in some detail, it is not the intention of the Applicants 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 of the invention may be used alone or in numerous combinations depending on the needs and preferences of the user. This has been a description of the present invention, along with the preferred methods of practicing the present invention as currently known. However, the invention itself should only be defined by the appended claims, wherein.