The present invention generally relates to a liquid material dispensing apparatus and nozzle and, more specifically, to an apparatus and nozzle for dispensing controlled patterns of liquid adhesive strands or filaments.
Many reasons exist for dispensing liquid adhesives, such as hot melt adhesives, in the form of a thin filament or strand with a controlled pattern. Conventional patterns used in the past have been patterns involving a swirling effect of the filament by impacting the filament with a plurality of jets of air. This is generally known as controlled fiberization or CFJ in the hot melt adhesive dispensing industry. Controlled fiberization techniques are especially useful for accurately covering a wider region of a substrate with adhesive dispensed as single filaments or as multiple side-by-side filaments from nozzle passages having small diameters, such as on the order of 0.010 inch to 0.060 inch. The width of the adhesive pattern placed on the substrate can be widened to many times the width of the adhesive filament itself. Moreover, controlled fiberization techniques are used to provide better control of the adhesive placement. This is especially useful at the edges of a substrate and on very narrow substrates, for example, such as on strands of material, such as Lycra®, used in the leg bands of diapers. Other adhesive filament dispensing techniques and apparatus have been used for producing an oscillating pattern of adhesive on a substrate or, in other words, a stitching pattern in which the adhesive moves back-and-forth generally in a zig-zag form on the substrate. Some types of these dispensers or applicators have a series of liquid and air orifices arranged on the same plane.
Conventional swirl nozzles or die tips typically have a central adhesive discharge passage surrounded by a plurality of air passages. The adhesive discharge passage is centrally located on a protrusion which is symmetrical in a full circle or radially about the adhesive discharge passage. A common configuration for the protrusion is conical or frustoconical with the adhesive discharge passage exiting at the apex. The air passages are typically disposed at the base of the protrusion. The air passages are arranged in a radially symmetric pattern about the central adhesive discharge passage, as in the protrusion itself. The air passages are directed in a generally tangential manner relative to the adhesive discharge passage and are all angled in a clockwise or counterclockwise direction around the central adhesive discharge passage.
Conventional meltblown adhesive dispensing apparatus typically comprise a die tip having multiple adhesive or liquid discharge passages disposed along an apex of a wedge-shaped member and air passages of any shape disposed along the base of the wedge-shaped member. The wedge-shaped member is not a radially symmetric element. Rather, it is typically elongated in length relative to width. The air is directed from the air discharge passages generally along the side surfaces of the wedge-shaped member toward the apex and the air impacts the adhesive or other liquid material as it discharges from the liquid discharge passages to draw down and attenuate the filaments. The filaments are discharged in a generally random manner.
Various types of nozzles or die tips, such as those of the type described above, have been used to dispense adhesive filaments onto one or more elastic strands. For such applications, the strand or strands typically need to be guided at specific spaced apart positions as the adhesive is discharged onto the strand or strands. For this purpose, strand guides may take the form of rollers which are fixed to the dispensing module or some other fixed structure. While this works appropriately in many situations, the strand guides do present additional expense and spacing considerations.
The invention provides an adhesive applicator that results in repeatable filament orientation with improved placement control. Further, the invention provides a predictable relationship between a specific geometric configuration of liquid and air discharge passages and the resulting pattern width and frequency. Thus, the nozzle configuration can be controlled to give a tighter, high frequency filament pattern or a more open, lower frequency filament pattern.
The present invention generally provides a liquid dispensing module or applicator for discharging at least one liquid filament onto a moving substrate in a particular pattern such as a generally swirling pattern. The dispensing module includes a dispenser or module body for receiving pressurized liquid and air and a nozzle is coupled to the module body. In one exemplary embodiment, the nozzle comprises a nozzle body having a first side and an opposite second side with the first side coupled to the module body and including a liquid supply port and an air supply port coupled with respective liquid and air supply passages of the module body. A frustoconical protrusion extends from a recessed or inwardly angled surface formed into the second side of the nozzle body. A liquid discharge passage extends along an axis through the apex of the frustoconical protrusion. The liquid discharge passage communicates with the liquid supply port of the nozzle body. The nozzle body further includes a plurality of air discharge passages positioned proximate the frustoconical protrusion. In an exemplary embodiment, at least two of the air discharge passages are positioned on a surface which is recessed into the second side of the nozzle body, adjacent the frustoconical protrusion. Each of the side surfaces and each of the air discharge passages is angled in a direction generally toward the liquid discharge passage.
Preferably, the nozzle body includes four of the air discharge passages positioned in a generally square pattern about the liquid discharge passage. In one exemplary embodiment, two of the air discharge passages are positioned adjacent the frustoconical protrusion and two of the air discharge passages are positioned at lower positions of the nozzle body. The nozzle body further includes a strand guide coupled directly to the nozzle body for guiding movement of a strand of substrate material. In one exemplary embodiment, the strand guide comprises a notch formed into a lower surface of the nozzle body and having opposed sidewalls for guiding a strand past the nozzle. The liquid and air discharge passages have outlets positioned near the notch so that the liquid may be deposited on the strand in a desired pattern. In another exemplary embodiment, the notch extends between side surfaces of the nozzle body, and the side surfaces form acute angles with a mounting surface of the nozzle body.
The method of this invention generally involves dispensing a filament of adhesive onto a strand from a liquid discharge passage forming an acute angle with the direction of movement of the strand. The filament of adhesive is impinged by process air from a plurality of process air discharge passages. Advantageously, the impingement points of the process air streams with the adhesive are preferably also closely proximate the strand. While the liquid filament discharge passage is generally oriented in the direction that the strand moves, it is also oriented or angled toward the strand in the preferred method.
The inventive concepts apply to dispensing modules having one or more sets of the liquid and air discharge passages. For many applications, it will be desirable to provide a nozzle having multiple side-by-side sets of liquid and air discharge passages with each set configured as described above. In each case, a desirable liquid pattern is achieved by the angular orientation of the air discharge passages with respect to the liquid discharge passage. As a result, different configurations of the air and liquid discharge passages may be made with predictable results.
These and other features, objects and advantages of the invention will become more readily apparent to those of ordinary skill in the art upon review of the following detailed description, taken in conjunction with the accompanying drawings.
Referring first to
Referring first to
Air discharge passages 60, 62, 64, 66 exit at outlets 60b, 62b, 64b, 66b on front surface 34 and on semi-circular recess 54, adjacent liquid discharge outlet 48b best shown in
As viewed from the front surface 34 of nozzle body 32 (
The four discharge outlets 60b, 62b, 64b, 66b have centers which are positioned along a common radius from a point corresponding to the location of a substrate received into notch 42. In an exemplary embodiment, the centers of air discharge outlets 60b, 62b, 64b, and 66b are positioned along a radius located from a point which is 0.027-inch from the apex of notch 42 when notch 42 has converging side walls 42a and 42b separated by an angle of 60°. This corresponds to a strand 44 having a cross sectional diameter of 0.031 inch.
The four discharge outlets 60b, 62b, 64b, 66b are arranged to form a generally square pattern below the liquid discharge outlet 48b when viewed along axis 48a, as depicted in
Referring to
Referring now to
The second side 126 of the nozzle body 106 further includes a plurality of air discharge outlets 136 proximate the liquid discharge outlet 132 and in fluid communication with air discharge passages 138, 140 by way of respective air passages 139, 141 which extend to the air supply ports 122, 124 on the first side 118 of the nozzle body 106. The air discharge passages 138, 140 of the exemplary nozzle body 106 are inclined at approximately 20° and approximately 28° from an axis through liquid passage 135. As shown in
In the exemplary nozzle body 106, four air discharge outlets 136 are disposed in a generally square pattern around the liquid discharge outlet 132 at the base of the frustoconical protrusion 130. Diagonally opposite air discharge passages 138, 140 or, in other words, air discharge passages disposed at opposite corners of the square-shaped pattern, are symmetric and disposed in planes that are at least nearly parallel to each other. The air discharge passages 138, 140 are each offset from axes 152 that are normal to a longitudinal axis of the liquid discharge passage 134, and each forms a true angle of approximately 30° with the longitudinal axis of the liquid discharge passage 134 such that the air stream discharged from each air discharge passage 138 is tangential to the liquid filament 100 discharged from the liquid discharge passage 134, as opposed to directly impacting the filament 100. This arrangement of air and liquid discharge passages provides a liquid filament which is moved in a controlled manner as it is dispensed from the liquid discharge passage to create a desired pattern on the strand 102 of substrate material. Variation of the pattern is possible by adjusting the offset spacing and orientation of the air discharge passages 138, 140 relative to the liquid discharge passage 134, as will be apparent to those skilled in the art.
The nozzle body 106 further includes a notch 150 formed into an end of the nozzle body 106 opposite the first side 118 and proximate the liquid discharge outlet 132 to direct the strand 102 of substrate material past the air and liquid discharge outlets 132, 136 disposed on the second side 126 of the nozzle body 106. As shown more clearly in
While the present invention has been illustrated by a description of various 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 what is claimed is:
This application is a continuation of application Ser. No. 11/121,894, filed May 4, 2005 (pending) which is a continuation of application Ser. No. 10/294,867 filed Nov. 14, 2002 (now U.S. Pat. No. 6,911,232), which claims the benefit of U.S. Provisional Application No. 60/372,134 filed on Apr. 12, 2002 (expired), and the disclosures of which are hereby incorporated by reference herein.
Number | Date | Country | |
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60372134 | Apr 2002 | US |
Number | Date | Country | |
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Parent | 11121894 | May 2005 | US |
Child | 12433164 | US | |
Parent | 10294867 | Nov 2002 | US |
Child | 11121894 | US |