Plastic article or earthenware shaping or treating: apparatus – Means making particulate material directly from liquid or... – By means applying fluid jet or blast to unconfined liquid...
Reexamination Certificate
1998-02-10
2001-04-03
Pyon, Harold (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Means making particulate material directly from liquid or...
By means applying fluid jet or blast to unconfined liquid...
C425S072200, C425S186000, C425S188000, C425S19200R, C425S463000, C425S464000
Reexamination Certificate
active
06210141
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to dies for applying hot melt adhesives to a substrate using meltblowing, spiral, bead, spray, or coating patterns. In one aspect, the invention relates to modular die bodies with interchangeable and replaceable die tips or nozzles. In still another aspect the invention relates to an inexpensive disposable die module.
The deposition of hot melt adhesives onto substrates has been used in a variety of applications including diapers, sanitary napkins, surgical drapes, and the like. This technology has evolved from the application of linear beads such as that disclosed in U.S. Pat. No. 4,687,137, to air assisted deposition such as that disclosed in U.S. Pat. No. 4,891,249, and to spiral deposition such as that disclosed in U.S. Pat. Nos. 4,949,668 and 4,983,109. More recently, meltblowing dies have been adapted for the application of hot melt adhesives (see U.S. Pat. No. 5,145,689).
At the present, the most commonly used adhesive applicators are intermittently operated air assisted dies. U.S. Pat. No. 5,618,566 discloses a modular die assembly comprising a row of side-by-side modules mounted on a manifold. Each module is provided with a die tip or nozzle through which the adhesive is extruded. U.S. Pat. No. 5,728,219 discloses a modular die assembly comprising side-by-side modules mounted on a manifold. Selected modules of the array may be provided with different types of extrusion die tips or nozzles. The term “nozzle” is used herein in the generic sense to describe the part of the applicator which determines the pattern of adhesive deposition (e.g. spray, bead, spiral, coating or meltblown). The nozzles for bead and spiral deposition are adapted to deposit a monofilament onto a substrate. The nozzles for meltblown applicators, also referred to as die tips, are designed to meltblow a row of filaments onto the substrate. Nozzles for bead and coating deposition are non-air assisted.
The availability of different types of nozzles for each module permits the operator to select a variety of deposition patterns. Each of the nozzle types has its own advantages and disadvantages. Meltblown nozzles provide a generally uniform covering of a predetermined width of the substrate, but do not provide precise edge control which is needed or desirable in some applications. On the other hand, the spiral nozzles deposit a controlled spiral bead on the substrate giving good edge control but not uniform substrate coverage. The bead and coating nozzles provide a heavier adhesive deposit than the meltblown or spiral patterns.
In order to replace a nozzle of a particular die module in the die assembly disclosed in U.S. Pat. No. 5,618,566, or change a nozzle type of a module in the die assembly disclosed in U.S. Pat. No. 5,728,219, it generally is necessary to (1) remove the module from the manifold (2) unscrew the four bolts mounting the nozzle assembly to the module, (3) substitute the new nozzle for the old nozzle, (4) resecure the nozzle assembly to the module, and (5) reattach the module to the manifold. Although this is a simple procedure compared to the non-modular die constructions, it nevertheless requires some shutdown time (on the order of 30 to 60 minutes). For this reason, the entire module is generally replaced and the old module repaired.
SUMMARY OF THE INVENTION
The modular dies of the present invention feature a die module having a quick disconnect assembly that permits the die tip or nozzle to be replaced without removing the module from the die manifold. Briefly, the die module comprises two main components: a die body mounted on a manifold, and a die tip or nozzle mounted on the die body. The die tip or nozzle is secured to the die body by a pair of clamping members adapted to engage opposite edges or sides of the die tip or nozzle. The members with the die body mounted on the manifold are movable between a clamping position and a nonclamping position. In the clamping position, the die tip or nozzle is forcefully secured to the die body. In the nonclamping position, the die tip or nozzle is free to be removed from the die body.
A novel feature of the invention vis-a-vis prior art die modules is the principle of operation of the clamping means for securing the die tip or nozzle to the body.
In the prior art devices (e.g. those disclosed in U.S. Pat. No. 5,618,566), the die tip is secured to the die body by bolts which apply a force in a direction normal to the plane of the mounting surface. In the module of the present invention, the mounting clamps create opposite forces on the opposite ends of the die tip, each force having a major component in a direction parallel to the plane of the die tip mounting surface and a component of forcing action in a direction normal to the mounting surface. The clamping force thus may be activated by a single pressure member (e.g. bolt) acting on one of the clamping members.
Another important novel feature of the clamping means is the location of the pressure member. Since only a single pressure applying member is needed it can be conveniently placed on the exposed front surface of the die body, permitting the clamping member to be activated or deactivated without removing the module from the manifold.
The die body comprises three main components: an upper body portion, a lower body portion and a cap. These components may be fabricated by interference fits which avoids the expensive machining required in prior art modules.
The interference-fit construction prevents access to the die body interior for repair. However, this is not a problem because economically it is cheaper to dispose of the damaged or faulty module and replace it with a new one.
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Leyson Joseph
Nordson Corporation
Pyon Harold
Wood Herron & Evans L.L.P.
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