Information
-
Patent Grant
-
6210141
-
Patent Number
6,210,141
-
Date Filed
Tuesday, February 10, 199826 years ago
-
Date Issued
Tuesday, April 3, 200123 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Pyon; Harold
- Leyson; Joseph
Agents
- Wood, Herron & Evans, L.L.P.
-
CPC
-
US Classifications
Field of Search
US
- 425 7
- 425 722
- 425 831
- 425 3822
- 425 463
- 425 464
- 425 192 S
- 425 190
- 425 186
- 425 188
- 264 12
-
International Classifications
-
Abstract
An adhesive dispensing die module for mounting on a manifold incudes (a) a die body having formed therein polymer and air flow passages, and a valve for selectively closing the polymer flow passage and (b) a die tip or die nozzle detachably mounted on the die body. The die tip or die nozzle is secured to the die body by a pair of clamping members depending from the die body and adapted to engage die tip or die nozzle therebetween. The clamping members can selectively be moved toward one another to clampingly secure the die tip or die nozzle therebetween or moved away from one another to release the die tip or die nozzle, permitting it to be replaced without the need to remove the die module from the manifold.
Description
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.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a front elevational view of the die assembly constructed according to the present invention and provided with three different applicator nozzles.
FIG. 2
is an enlarged sectional view of the modular die shown in
FIG. 1
with cutting plane indicated by
2
—
2
thereof.
FIG. 3
is an enlarged view of
FIG. 2
, illustrated internal features of the die module.
FIG. 4
is a fragmented view of the module shown in
FIG. 3
, illustrating the removal of a die tip from the die body.
FIG. 5
is a sectional view of the module shown in
FIG. 3
with the cutting plane taken along line
5
—
5
thereof.
FIG. 6
is a view of the die tip shown in
FIG. 4
taken from the perspective of the plane along line
6
—
6
thereof.
FIG. 7
is a cross-sectional view of the die tip nozzle shown in
FIG. 4
with the cutting plane taken along line
7
—
7
thereof.
FIG. 8
is a sectional view of the die tip nozzle of
FIG. 4
, with the cutting plane taken along line
8
—
8
thereof.
FIG. 9
illustrates the angle β of the air holes in relation to the apex.
FIGS. 10 and 11
are sectional views of different applicator nozzles useable in the module disclosed in
FIGS. 2
,
3
and
4
.
DESCRIPTION OF THE PREFERRED EMBODIMENT
With reference to
FIGS. 1 and 2
, the modular die assembly
10
of the present invention comprises a manifold
11
, a plurality of side-by-side self-contained die modules
12
, and a valve actuator assembly including actuator
20
for controlling the polymer flow through the modules
12
. As best seen in
FIG. 2
, each module
12
includes a die body
16
, a die tip or a nozzle
18
, and nozzle retainer
19
. Filaments
14
are discharged from modules
12
onto a substrate
15
(or collector). The manifold
11
distributes a hot melt adhesive and hot air to each of the modules
12
. The modular die
10
includes meltblowing die tips
18
mounted on most of the die bodies
16
. Some of the modules
12
, however, may be provided with various types of nozzles. As illustrated in
FIG. 1
, end modules
12
A are provided with spiral nozzles and center modules
12
B are provided with coating nozzles. Spray nozzles and bead nozzles may also be used.
The main components mentioned above are described in detail below.
Die Body
As best seen in
FIG. 3
, the die body
16
may be constructed in two parts, an upper die body portion
16
A and a lower die body portion
16
B. For convenience of description these body portions will be referred to a merely as upper die body
16
A and lower die body
16
B. Die body
16
A has an upper circular recess
17
formed therein, the upper end of which is closed by cap
24
. The cap
24
has a skirt portion
24
A, which in combination with the wall of recess
17
defines a generally cylindrical chamber
23
.
A diaphragm
25
is mounted in chamber
23
dividing it into an upper chamber
23
A and a lower chamber
23
B.
Side ports
26
and
27
are formed in the wall of the die body
16
A to provide communication to chambers
23
A and
23
B, respectively. As described in more detail below, the ports
26
and
27
serve to conduct air (referred to as instrument gas) to and from chambers
23
A and
23
B.
Die body
16
A has formed therein a lower downwardly opening recess
28
surrounded by annular surface
29
and defined in part by surface
33
. A central bore
31
formed in die body
16
A extends downwardly from chamber
23
B to recess
28
. As described below, bore
31
receives valve stem
30
.
The lower die body
16
B has a cylindrically shaped projection
35
adapted to fit in the recess
28
as illustrated in FIG.
3
. Surface
36
surrounding the base of cylindrical member
35
engages surface
29
of die body
16
A, with o-ring
32
provided at the junction thereof. Surfaces
29
and
36
may be of the same general shape.
A bore
37
extends downwardly through die body
16
B terminating at bottom surface
39
. A stem seal
40
(e.g. spring lip seal) is mounted in the upper end of the bore
37
, and a valve insert
38
is mounted in the lower end of the bore
37
in contact with bottom surface
39
(see FIG.
4
). Ports
41
and
42
formed, respectively, in insert
38
and surface
39
serve as a fluid outlet for bore
37
. The lower end of opening
42
is provided with an O-ring
43
. The bore
37
may be of variable diameter to accommodate the parts mounted therein.
The inlet to opening
41
is chamfered to provide a valve seat
44
for a valve stem
30
as described below.
As shown in
FIGS. 4 and 5
the lower end of the die body
16
B has formed therein a downwardly opening air chamber
49
which surrounds a central cylindrical portion
45
. The air chamber
49
is defined by interior walls
48
and cylindrical portion
45
. Bore
37
and port
42
are formed in the cylindrical projection
45
. Bottom surfaces
46
and
47
of die body
16
B are coplanar for receiving a die tip or nozzle
18
as described in detail below.
The back side
56
(side mounted on the manifold
11
) of body
16
B has a downwardly projecting narrow edge portion
51
terminating at end
52
.
The inner surface
53
of edge portion
51
is shaped to receive and support a complementary shaped edge portion of a die tip or nozzle
18
. As illustrated, the inner surface
53
is provided with a vertical wall and a downwardly tapered shoulder
54
projecting inwardly (with respect to die body
16
A) from the lower edge of wall
53
. The shoulder
54
has a flat angular surface for supporting an edge portion of die tip or nozzle
18
.
A polymer flow passage
57
formed in die body
16
A registers with polymer flow passage
58
formed in projection
35
. These passages deliver polymer melt to bore
37
.
Air passage
59
, formed in die body
16
B, serves to deliver air to air chamber
49
.
A valve assembly is provided in the module
12
to selectively start and stop the polymer flow therethrough. The valve seat
44
is opened or closed by movement of the diaphragm
25
which in turn moves stem
30
.
The valve stem
30
extends from chamber
23
B through opening
31
and into bore
37
. The upper end
61
of stem
30
is secured to diaphragm
25
and a lower end portion
62
of stem
30
is specially shaped to fit into the valve insert
38
. The insert
38
may be made of wear resistant material (carbide) and may include internal longitudinal ribs (spider members, one shown as
55
) for guiding the stem portion
62
into the interior of the insert
38
and to permit the flow of fluid therethrough. The tip
63
of the stem is shaped to seat on the valve seat
44
.
The stem upper end
61
is provided with a collar
64
which is threaded for receiving bolt
65
. Bolt
65
secures the diaphragm
25
to the upper end
61
of stem
30
. A spring
66
, interposed between cap
24
and diaphragm
25
, urges the diaphragm
25
and valve stem
30
downwardly causing the valve tip
63
to seat on valve seat
44
. A wipe seal
67
is provided around stem
30
at the upper end of opening
31
formed in die body
16
A.
As described in detail below, the valve seat
44
is opened by activating chamber
23
B with instrument gas moving the diaphragm
25
and valve stem
30
upwardly, and compressing spring
66
. This moves valve tip
63
off of its valve seat
44
. The upper extent of the diaphragm
25
movement is set by the space between bolt head
65
and downwardly projecting head
69
.
Die Tip or Nozzle and Retainer
The die tip or nozzle
18
is adapted to be mounted on the downwardly facing and coplanar surfaces
46
and
47
of body
16
B. The nozzle
18
illustrated in
FIGS. 2
,
3
and
4
, is a meltblowing die tip, but as described below, may be a nozzle such as a spiral nozzle, a bead nozzle, a spray nozzle or a coating nozzle.
As shown in
FIGS. 3 and 4
, the die tip
18
comprises a base member
71
which is generally coextensive with the mounting surface
47
of die body
16
B, and a triangular nosepiece
72
which may be integrally formed with the base
71
. The nosepiece
72
is defined by converging surfaces
73
and
74
which meet at apex
76
. The apex
76
may be discontinuous, but preferably is continuous along the die module
12
. The height of the nosepiece
72
may vary from 100% to 25% of the overall height of the die tip
18
, but preferably is not more than 50% and most preferably between 20% and 40%.
The portions of the base
71
extending laterally from the nosepiece
72
serve as flanges for mounting the die tip
18
to the die body
16
B and having passages for conducting air and polymer melt through the base
71
. As best seen in
FIG. 6
, the flanges of the base
71
have two rows of air holes
77
and
78
formed therein. As shown in
FIG. 4
the rows of air holes
77
and
78
define converging planes. The plane defined by air holes
77
extends at the same angle as nosepiece surface
73
, and the plane defined by air holes
78
extend at the same angle as nosepiece surface
74
. The included angles (α) of the planes and surfaces
73
and
74
ranges from 30° to 90°, preferably from 60° to 90°. (It is understood that reference to holes lying in a plane means the axes of the holes lie in the plane.)
While each row of air holes
77
and
78
lie in their respective planes, at least some of the air holes
77
and
78
within their respective planes need not be parallel. As best seen in
FIGS. 8 and 9
, the die tip
18
is provided with an odd number (e.g.
17
) of air holes
77
, each having an inlet
79
and an outlet
80
. (Note the row of air holes
78
, on the opposite side of the nosepiece
72
is preferably the mirror image of the row of air holes
77
, although they need not be. For example the air holes
78
may be offset from air holes
77
.)
The die tip
18
further includes surface
70
which is mounted on surface
47
of the die body
16
A, closing cavity
49
. Surface
70
also engages surface
46
with O-ring
43
providing a fluid seal at the junction of these two surfaces. Surface
70
is substantially coextensive with the outer periphery of surface
47
.
With the die tip
18
mounted on the die body
16
, the inlets
79
of all of the air holes
77
and
78
register with cavity
49
as shown in FIG.
3
.
The central air holes (in this embodiment air hole
77
A) extends perpendicular to the apex
76
as shown in FIG.
8
. One or more air holes
77
located at the longitudinal center of the die tip
18
may extend parallel to air hole
77
A. In designs with an even number of air holes
77
, at least two of the center air holes
77
A are preferably provided.
The air holes
77
flanking the center air hole
77
A form an angle β (see
FIG. 9
) with the apex
76
which decreases progressively (arithmetic) and symmetrically from the center hold
77
A outwardly. The outermost holes are shown as
77
B on
FIGS. 8 and 9
. The air holes
77
B form an angle with the apex
76
that decreases in constant increments outwardly. For example, center air hole
77
A forms an angle of 90° with the apex
76
. If the angle increment is −1°, then the two air holes
77
adjacent air hole
77
A form an angle of 89° with the apex
76
. Continuing the incremental arithmetic progression to the eighth (outermost) air holes
77
B, the angle of these air holes would be 82°. Of course, the incremental angle may vary, but preferably is between ½ and 4° most preferably between 1° and 3.5°. The arithmetic progression may be represented by the following equation:
Angle β=90
°−nι
Where n is the hole position or each side of the center air hole and preferably ranges from 4 to 15, most preferably 5 to 10 and ι is the constant incremental degree change.
Polymer passages
85
are formed in the die tip
13
, as shown in
FIGS. 4 and 7
. The passages
85
may be in the form of a distribution system comprising a plurality of passages
85
connected to inlet
87
by passage
88
. Inlet
87
registers with die body port
42
with die tip
18
mounted on die body
16
A.
The passages
85
have outlets at
89
which are uniformly spaced along the apex
76
. Passages
85
preferably extend perpendicular to apex
76
. The design illustrated in
FIG. 7
serves well for small modules (i.e. lengths less than about 3″ to 4″). For longer dies, a pressure balance coat hanger design may be preferred. The passages
85
are preferably small diameter orifices and serve as the fiber forming means. The die tip body
71
has beveled edges
81
and
82
as shown in
FIG. 4
which define surfaces for engaging complementary shaped retaining shoulders
54
and
84
of the clamping members.
The nozzle retainer means is a quick disconnect design permitting the die tip
18
to be quickly and easily replaced, requiring only a few minutes. Key to the quick disconnect feature is a retainer plate
80
mounted on the front of die body
16
A as shown in
FIGS. 3 and 4
. The plate
80
comprises body portion having an inwardly projecting (with respect to the die body
16
A) shoulder
84
at its lower end and a inwardly projecting rounded member
86
at its upper end.
A hole
91
found in an intermediate portion of plate
80
receives bolt
92
which screws into threaded hole
93
found in die body
16
A. Two side by side compression springs, one shown at
94
, are mounted in recesses
95
and
96
and bias plate
80
outwardly with respect to die body
16
A.
The rounded member
86
extends horizontally along the face of die body
16
A and is received in a complementary shaped round groove
97
to form a hinge structure.
The die tip
18
is secured to the die body
16
A by unscrewing the bolt
92
sufficiently to permit the lower end
84
to move outwardly by action of springs
94
. The die tip
18
is inserted in place with beveled edge
82
supported on shoulder
54
of member
52
. The bolt
92
is screwed into body
16
A. This compresses the springs
94
and brings shoulder
84
into contact with beveled edge
81
of die tip
18
.
The clamping action of the plate
80
squeezes the die tip
183
between clamping member
51
and lower clamping member
80
(plate). The wedging action of beveled surfaces
81
and
82
engaging surfaces
54
and
84
causes the die tip
18
to move upwardly into sealing engagement with surfaces
46
and
47
of die body
16
A and o-ring
43
. The wedging action of the clamping member imparts a squeezing horizontal force component and a vertical force component on the die tip
18
.
The rounded member
86
pivots within groove
97
as the plate
80
is moved by action of the bolt
92
.
The die tip
18
is replaced by merely unscrewing the bolt
92
sufficiently to permit the die tip
18
to be removed from the die body
16
A, as illustrated in FIG.
4
.
As mentioned above, the quick change feature enables the die tip
18
to be replaced with the same or different type nozzles.
FIGS. 10 and 11
depict different types of nozzles
18
that may be mounted on die body
16
A.
As shown in
FIG. 10
, the nozzle
18
for generating a spiral filament comprises a circular nozzle
130
threadedly mounted in a body
135
. Extending axially through the circular insert member
130
is a polymer passage
134
that discharges at the apex of cone
133
. Angular air passages
136
extend through the body member and are angularly oriented with respect to the axis of polymer passage
134
. The direction of the air passages
136
are such to impart a circular or helical motion to the polymer as the air from the plurality of air passages
136
contact the polymer discharging from the polymer passage
134
. The orientation of the air passages with respect to the polymer filament can be in accordance with U.S. Pat. No. 5,102,484 or U.S. Pat. No. 4,983,109, the disclosures of which are incorporated herein by reference.
The body
135
is adapted to be mounted on the module body
16
A as described with respect to the meltblowing die tip
18
. With the nozzle
130
positioned in body
135
and mounted on surfaces
46
and
47
, air passage
136
are in fluid communication with air cavity
49
, and polymer flow passage
134
is in fluid communication with port
42
.
A bead or coating nozzle
18
(without air assistance) is disclosed schematically in FIG.
11
. With this structure, the bead nozzle
141
is threadedly mounted in body
142
, similar to body
135
described with reference to the spiral nozzle
130
, and a polymer flow passage
143
extends axially therethrough, but this nozzle has no air passages. When mounted on the die body
16
A, the inlet of flow passage
143
is in fluid communication with polymer flow passage port
42
. The nozzle has an inverted conical portion
144
, through which passage
143
extends to a position within about ½ to 1 inch from the substrate for depositing the bead or coating thereon. Since air is not used with this nozzle, the nozzle
141
in combination with the body
142
blocks out or seals the air chamber
49
.
Since the bodies of the die tip or nozzles
18
, regardless of the type, are shaped to fit onto the die body
16
A in the same manner as described above, they are interchangeable. That is, a module
12
along the die assembly
10
, (as shown in
FIG. 1
) may be provided with any of the nozzles or die tip, or may change one for another at any time by merely releasing the clamping means and replacing the nozzle as described above.
The Manifold
As best seen in
FIG. 2
, the manifold
11
is constructed in two parts: an upper body
98
, and a lower body
99
bolted to the upper body by spaced bolts
100
. The upper body
98
and lower body
99
have mounting surfaces
101
and
102
, respectively, which lie in the same plane for receiving modules
12
. Surface
56
of each module engage surfaces
101
and
102
of manifold
11
.
The upper manifold body
98
has formed therein polymer header passages
103
extending longitudinally along the interior of body
98
and side feed passages
104
spaced along the header passage
103
for delivering polymer to each module
12
. The polymer feed passages
104
have outlets which register with passage
57
of its associated module
12
. The polymer header passage
103
has a side inlet at one end of the body
98
and terminates at near the opposite end of the body
98
. A connector block
90
(see
FIG. 1
) bolted to the side of body
98
has a passage for directing polymer from feed line to the header channel
103
. The connector block
90
may include a polymer filter. A polymer melt delivered to the die
10
flows from a source such as an extruder or metering pump through connector block
90
to passage
103
and in parallel through the said feed passages
104
to the individual modules
12
.
Returning to
FIG. 2
, air is delivered to the modules
12
through the lower block
99
of the manifold
11
. The air passages in the lower block
99
are in the form of a network of passages comprising a pair of passages
101
A and
102
A, interconnecting side ports
103
A, and module air feed ports
105
longitudinally spaced along bore
101
A. Air inlet passage
106
connects to air feed line
107
near the longitudinal center of block
99
. Air feed ports
105
register with air passage
59
of its associated module.
Heated air enters body
99
through line
107
and inlet
106
. The air flows through passage
102
A, through side passages
103
A into passage
101
A, and in parallel through module air feed ports
105
and module passages
59
. The network design of manifold
99
serves to balance the air flow laterally over the length of the die
10
.
The instrument air for activating each module valve is delivered to the chamber
23
of each module
12
by air passages formed in the block
98
of manifold
11
. As best seen in
FIG. 2
, instrument air passages
110
and
111
extend through the width of body
98
and each has an inlet
112
and an outlet
113
. Outlet
113
of passage
110
registers with port
26
formed in module
12
which leads to chamber
23
A; and outlet
113
of passage
111
registers with port
27
of module
12
which leads to chamber
23
B.
An instrument air block
114
bolted to block
98
and traverses the full length of the instrument air passages
110
and
111
spaced along body
98
. The instrument air block
114
has formed therein two longitudinal channels
115
and
116
. With the block
114
bolted to body
98
, channels
115
and
116
communicate with the instrument air passages
110
and
111
, respectively. Instrument tubing
117
and
118
delivers instrument air from control valve
119
to flow ports
108
and
109
and passages
110
and
111
in parallel.
For clarity, actuator
20
and tubing
117
and
118
are shown schematically in FIG.
2
. Actuator
20
comprises three-way solenoid air valve
119
coupled with electronic controls
120
.
The manifold
11
is described in more detail in U.S. Pat. No. 5,618,566, the disclosure of which is incorporated herein by reference.
Assemblage and Operation
The three main components of the die body
16
may be assembled by interference fit. Other fabrication means may be used such as those described in the above referenced U.S. Pat. No. 5,618,566, but the interference assemblage is inexpensive. Since the interference fit precludes disassembly for repair, they are disposable after use. The nozzles and plates, of course can be removed before disposal.
The three body components
24
,
16
A and
16
B are assembled by an interference fit. The skirt
24
A fits in circular recess
17
and cylindrical member
35
fits in recess
28
. The clearance between the male members and female members of these couplings is 0.0015 to 0.0020. The parts are hydraulically pressed together at a high pressure (in the range of 1,000 to 2,000 psi, typically 1,500 psi).
The hydraulic pressing procedure may be as follows:
(a) the upper die body
16
A with internal members (diaphragm
25
, wiper seal
67
, spring
66
, and stem
30
) inserted therein is pressed fit with cap
24
. The diaphragm
25
, is inserted in recess and is held in place by skirt
24
A; and the wiper seal
67
is held in place by retainer ring
75
.
(b) This assembly then is press fit with the lower die body
16
B (recess
27
mated with projection
35
) having internal parts mounted therein.
A particularly advantageous feature of the present invention is that it permits (a) the construction of a meltblowing die with a wide range of possible lengths using standard sized manifolds and interchangeable, self-contained and disposable modules, and (b) variation of die nozzles (e.g. meltblowing, spiral, or bead applicators) to achieve a predetermined and varied pattern. Variable die length and adhesive patterns may be important for coating substrates of different sizes from one application to another. The following sizes and numbers are illustrative of the versatility of modular construction.
|
Die Assembly
Broad Range
Preferred Range
Best Mode
|
|
Number of Modules
3-6,000
5-100
10-50
|
Length of Modules
0.25-3.00″
0.5-1.50″
0.5-0.8″
|
(inches)
|
Orifice Diameter
0.005-0.050″
0.01-0.040″
0.015-0.030″
|
(inches)
|
Orifices/Inch (for
5-50
10-40
10-20
|
each module)
|
No air holes (77)/
15-50
20-40
25-35
|
Inch
|
No air holes (78)/
15-50
20-40
25-35
|
Inch
|
Air hole Diameter
0.05-0.050
0.010-0.040
0.15-0.030
|
(inch)
|
No Air hole/No
1-10
3-8
4-6
|
Orifices
|
|
Depending on the desired length of the die, standard sized manifolds may be used. For example, a die length of one member could employ 54 modules mounted on a manifold 40 inches long. For a 20 inch die length, 27 modules would be mounted on a 20 length manifold. Note that the modules
10
are mounted in side-by-side relation using bolts
79
which extend through the die body
16
A and screw into manifold block
98
. O-rings may be mounted around passages extending from manifold
11
into die body
16
.
As indicated above, the modular die assembly can be tailored to meet the needs of a particular operation. As exemplified in
FIG. 1
the die assembly
10
comprises fourteen modules
12
, two of which have spiral nozzles, two have coating nozzles and ten have meltblowing die tips. The lines, instruments, and controls are connected and operation commenced. A hot melt adhesive is delivered to the die
10
through block
90
, hot air is delivered to the die through line
107
, and instrument air or gas is delivered through lines
117
and
118
.
Actuation of the controls
20
, pressurizes chamber
23
B, and vents chamber
23
A. This moves diaphragm
25
and stem
30
upwardly, opening port
42
of each module as described previously causing polymer melt to flow through each module
12
. In the meltblowing modules
12
, the melt flows in parallel streams through manifold passages
104
, through side ports
57
, through bore
37
, and through ports
41
and
42
into the die tip
18
. The polymer melt is distributed laterally and discharges through orifices
85
as side-by-side filaments
14
. Hot air meanwhile flows from manifold passages
103
A into port
59
through chamber
49
, holes
78
and
79
, and discharges it as converging air jets at the nosepiece
72
. The converging air jets contact the filaments discharging from the orifices and by drag forces stretch them and deposit them onto an underlying substrate
15
in a random pattern. This forms a generally uniform layer of meltblown material on the substrate.
In each of the flanking spiral nozzle modules
12
A the polymer flows from manifold through passage
57
, through bore
37
, through ports
41
and
42
, through passage
134
of nozzle
130
(
FIG. 10
) discharging at the apex of cone
133
. Air flows from manifold passage
105
, passage
59
into chamber or cavity
49
, through passages
136
. Air discharging from passages
136
impart a swirling motion of the polymer issuing from passage
134
. The polymer is deposited on the substrate as a circular or helical bead, giving good edge control for the adhesive layer deposited on the substrate.
Typical operational parameters are as follows:
|
Polymer
Hot met adhesive
|
Temperature of the
280° F. to 325° F.
|
Die and Polymer
|
Temperature of Air
280° F. to 325° F.
|
Polymer Flow Rate
0.1 to 10 grms/hole/min.
|
Hot Air Flow Rate
0.1 to 2 SCFM/inch
|
Deposition
0.5 to 500 g/m
2
|
|
As indicated above, the die assembly
10
may be used in meltblowing any polymeric material, but meltblowing adhesives is the preferred polymer. The adhesives include EVA's (e.g. 20-40 wt % VA). These polymers generally have lower viscosities than those used in meltblown webs. Conventional hot melt adhesives useable include those disclosed in U.S. Pat. Nos. 4,497,941, 4,325,853, and 4,315,842, the disclosure of which are incorporated herein by reference. The preferred hot melt adhesives include SIS and SBS block copolymer based adhesives. These adhesives contain block copolymers, tackifier, and oil in various ratios. The above melt adhesives are by way of illustration only; other melt adhesives may also be used.
The wide bead nozzles
12
B are positioned at an interval location of the assembly shown in FIG.
1
. This array of modules with three different applicator heads deposits a layer of meltblown (random filaments) onto the substrate with an internal wide bead for increased strength as required in diaper lamination, and flanking spiral beads for edge control.
The locations of the types of die tips and nozzles may be changed along the die by merely unscrewing the retainer plate bolt, withdrawing the nozzle and replacing it with another nozzle. If the internal parts become inoperative, the module may be removed from the manifold and replaced with a new module.
In summary, the die assembly of the present invention embodies several features:
(a) a quick change die tip or nozzle
(b) interferences fit construction
(c) a solid state die tip
(d) interchangeable nozzles on each module.
Although the die modules and assemblies of the present invention has been described with particular reference to hot melt adhesive applications, it will be appreciated by those skilled in the art that the invention also applies to meltblowing of polymers to form nonwovens.
Claims
- 1. A die module for dispensing a polymer melt comprising:(a) a die body having (i) an air flow passage formed therein (ii) a polymer melt flow passage formed therein, (iii) valve means for opening and closing said polymer melt flow passage; and (iv) a nozzle mounting surface; (b) a nozzle positioned on said mounting surface of said die body and having at least one orifice formed therein and air passages formed therein, said orifice and said air passages being in fluid communication with said polymer melt flow passage and said air passage of said die body, respectively, and (c) a clamping structure affixed to said die body for clamping said nozzle securely to said mounting surface of said die body by the application of clamping force on opposite sides of said nozzle with a force component substantially parallel to said nozzle mounting surface, said clamping structure including a hinged member pivotally affixed to said die body and pivotally movable between a clamped position and an unclamped position thereby permitting said nozzle to be removed from said mounting surface.
- 2. The die module of claim 1 wherein said clamping structure further includes a fixed member depending from said die body and cooperating with said hinged member to secure said nozzle to said mounting surface, said hinged member being moveable forward and away from said fixed member whereby movement of said hinged member in one direction causes said clamping structure to forcefully engage said nozzle securing said nozzle to said mounting surface, and movement of said hinged member in the opposite direction moves said clamping structure apart permitting said nozzle to be removed from said mounting surface.
- 3. The die module of claim 1 wherein said nozzle is a meltblowing die tip.
- 4. The die module of claim 1 wherein said nozzle is selected from the group consisting of meltblown die tips, spiral nozzles, bead nozzles, spray nozzles, and coating nozzles.
- 5. The die module of claim 2 wherein each of said clamping members includes wedging surfaces engageable with opposite sides of said nozzle to impart an inward and upward clamping force on said nozzle attendant to movement of said hinged member in said one direction whereby said clamping members force said nozzle upwardly into sealing engagement with said mounting surface.
- 6. The die module of claim 2 wherein said hinged member comprises a retainer plate having a lower end engageable with one side of said nozzle, said plate being secured to said die body by a bolt whereby turning said bolt in one direction causes said plate to move into forceful engagement with said one side of said nozzle and turning said bolt in the opposite direction causes said plate to move away from said one side of said nozzle.
- 7. The die module of claim 6 wherein said retainer plate further includes a spring for biasing said plate away from said nozzle.
- 8. The die module of claim 1 wherein said valve means includes a movable member selected from a piston or diaphragm mounted in said die body, a valve seat formed in said polymer melt flow passage, a valve stem having an upper end secured to said moveable member and a lower end adapted to seat on said valve seat and means for selectively moving said moveable member (a) upwardly whereby said lower end of said valve stem moves off said valve seat, and (b) downwardly whereby said lower end of said valve stem seats on said valve seat.
- 9. The die module of claim 8, wherein said moveable member is a diaphragm.
- 10. A modular die assembly for depositing a hot melt adhesive onto a substrate which comprises:(a) a manifold having adhesive and air passages formed therein; (b) a plurality of substantially identical modular die bodies mounted in side-by-side relation on said manifold, each of said die bodies having an inner surface in contact with said manifold and an opposite outer surface facing outwardly from said manifold and having an adhesive passage and an air passage in fluid communication with said adhesive passage and air passage of said manifold exiting through a downwardly facing mounting surface; (c) an air-assisted die nozzle mounted on said mounting surface of each of said die bodies, each of said die nozzles having an adhesive flow passage and an air passage formed therein in fluid communication with said adhesive flow passage and air flow passage, respectively, of said die body, the improvement comprising a pair of members depending from said die body for clampingly engaging opposite sides of said die nozzle, at least one of said members being hingedly secured to said die body for allowing selective pivotal movement of said one member toward the other member to clamp said die nozzle therebetween.
- 11. The modular die assembly of claim 10 wherein each die body includes a meltblowing nozzle secured thereto, and at least one side module includes a spiral nozzle.
- 12. The modular die assembly of claim 10 wherein each die nozzle is selected from the group consisting of meltblowing, spiral, and spray nozzles, said nozzles being interchangeable on each die module.
- 13. The modular die assembly of claim 10 wherein said members include a nonmoveable clamping member depending from a back surface of said module and a moveable clamping member depending from and secured to a front surface of said module, and means for applying a clamping force to said moveable clamping member to clampingly engage said die nozzle between said moveable and nonmoveable members.
- 14. The module die assembly of claim 13 wherein said moveable clamping member is in the form of a plate, and said means for applying a force thereto is a bolt extending through said plate and threadedly mounted on said front surface of said die body, whereby turning said bolt in one direction causes said plate to apply a clamping force on said nozzle and turning of said bolt in the opposite direction releases said clamping force on said nozzle, permitting said nozzle to be removed from said die body.
- 15. The modular die assembly of claim 14 and further comprising a spring interposed between said plate and said die body to bias said plate outwardly.
- 16. The modular die assembly of claim 14 wherein said moveable clamping member and said nonmoveable clamping member each includes an inwardly projecting wedge surface for contacting said nozzle therebetween and forcing said nozzle upwardly into forceful engagement with said mounting die body surface.
- 17. A die module for dispensing liquids, the module comprising:a die body having a liquid inlet passage and a liquid outlet passage, a valve disposed within said die body and moveable between open and closed positions to respectively allow and prevent liquid flow through said liquid outlet passage, a nozzle coupled to said die body and having a dispensing orifice communicating with said liquid outlet passage, and a spring-biased clamping member coupled with said die body and engaging said nozzle, said clamping member being spring biased away from said die body and moveable between clamped and unclamped positions relative to said nozzle to allow said nozzle to be quickly attached to and removed from said die body.
- 18. The die module of claim 17, wherein said spring-biased clamping member is secured to said die body with a hinge structure.
- 19. The die module of claim 18 further comprising a stationary clamping member positioned on an opposite side of said nozzle relative to said spring-biased clamping member and said nozzle is held between said spring-biased clamping member and said stationary clamping member.
- 20. The die module of claim 19 further comprising respective wedging surfaces on said nozzle, said stationary clamping member and said spring-biased clamping member, said wedging surfaces holding said nozzle on said die body.
US Referenced Citations (19)
Foreign Referenced Citations (1)
Number |
Date |
Country |
54-73916 |
Jun 1979 |
JP |