Patent Publication Number: US-2022219844-A1

Title: Sealant cartridge air release apparatus and methods

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/844,950 filed on May 8, 2019, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to sealant cartridge air release apparatus and methods. 
     BACKGROUND OF THE INVENTION 
     When sealant cartridges are being filled with sealant formulations such as pre-mixed and frozen (PMF) sealants, pockets of air can be trapped between the cartridge plunger and the sealant filling the cartridge. Air bubbles in the sealant cause problems during dispensing by popping out and causing disruptions in the sealant bead formed on the application surface. 
     SUMMARY OF THE INVENTION 
     The present invention provides a sealant cartridge press fixture comprising: a bracket comprising a first side arm and a second side arm structured and arranged to receive a sealant cartridge therebetween, and a transverse support bar connected to the first and second side arms structured and arranged for attachment to a sealant filling nozzle. An air pressure cylinder mounted on the bracket comprises a reciprocating piston rod structured and arranged to contact and deform a sidewall of the sealant cartridge when the piston rod is extended from the air pressure cylinder. 
     The present invention also provides a method of releasing trapped air from a sealant cartridge. The method comprises mounting an empty sealant cartridge on a sealant filling nozzle, starting filling of the sealant cartridge with a sealant, pressing a sidewall of the sealant cartridge to temporarily deform the sidewall to create a gap between an interior surface of the sidewall and a plunger contained within the sealant cartridge in slidable contact with the interior surface wherein the gap allows trapped air to escape from a sealant filling region of the sealant cartridge, stopping the pressing of the sidewall, and continuing to fill the sealant cartridge with the sealant. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an isometric view of a sealant cartridge and press fixture of the invention. 
         FIG. 2  is a rear view of the sealant cartridge and press fixture of  FIG. 1 . 
         FIG. 3  is a partially broken away front view of the sealant cartridge and press fixture of  FIG. 1 . 
         FIG. 4  is a partially schematic cross-sectional view taken through line 4-4 of  FIG. 2 . 
         FIG. 5  is an isometric view of a press fixture of the invention. 
         FIG. 6  is a rear view of the press fixture of  FIG. 5 . 
         FIG. 7  is a front view of the press fixture of  FIG. 5 . 
         FIG. 8  is an isometric view of an air supply control unit for a press fixture of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1-4  illustrate a sealant cartridge  10  mounted in a press fixture  20  of the present invention. The sealant cartridge  10  includes a generally cylindrical sidewall  12 , a domed lower end  14  with a discharge opening  15  through which the cartridge  10  may be filled with sealant and through which the sealant may be subsequently discharged from the cartridge  10 . The discharge opening  15  may be interiorly threaded  16  for connection to a sealant dispensing tip during use. The sealant cartridge  10  includes an open upper end  17  through which a plunger  18  may be inserted in the sealant cartridge  10  and positioned at or near the domed lower end  14  prior to filling of the sealant cartridge  10  with sealant. The plunger  18  includes a side wiper edge  19  in contact with an interior surface of the sidewall  12  of the sealant cartridge  10 . The volume inside the cartridge  10  between the domed lower end  14  and plunger  18  defines a sealant volume inside the cartridge  10  that may contain air to be released from the sealant volume by a press fixture of the present invention. As more fully described below, the adhesive and sealant compositions may comprise any formulations known to those skilled in the art. 
     As shown in  FIGS. 1-7 , the press fixture  20  includes a bracket  21  having a first side arm  22 , second side arm  23  and a cross bar  24  connecting the first and second side arms. A longitudinal support bar  25  is fastened to the cross bar  24  by mounting bolts  26 . A transverse support bar  27  is attached to the longitudinal support bar  25  by mounting bolts  29 . A circular central opening  28  is provided through the transverse support bar  27 . 
     An air pressure cylinder  30  is secured to the first side arm  22  of the bracket  21 . As shown most clearly in  FIGS. 3 and 4 , the air pressure cylinder  30  includes a pressure chamber  31  in flow communication with a pressurized air inlet  32 . A piston  33  with a piston rod  34  is reciprocally mounted in the air pressure cylinder  30 . When pressurized air P is fed through the pressurized air inlet  32  into the pressure chamber  31 , the piston  33  and piston rod  34  are forced outwardly from the pressure chamber  31 . A pressure pad  35  mounted on the end of the piston rod  34  contacts the sidewall  12  of the sealant cartridge  10  as a result of the air pressure delivered to the pressure chamber  31 . The force applied by the piston rod  34  and pressure pad  35  against the sidewall  12  of the sealant cartridge  10  causes controlled deformation of the sidewall  12 . Air bubbles formed between the cartridge plunger  18  and sealant when the sealant cartridge is being filled may be removed by squeezing the cartridge sidewall  12  in a region near the plunger  18  at a selected moment during the filling process. The trapped air is therefore allowed to escape. The deformation creates an air gap between the interior surface of the sidewall  12  and the side wiper edge  19  of the plunger  18 . The temporary air gap allows air that may be trapped inside the sealant cartridge  10  between the plunger  18  and domed end  14  to escape pass the side wiper edge  19  of the plunger  18  toward the open end  17 . When the piston rod  34  and pressure pad  35  are pressed against the sidewall  12  of the sealant cartridge  10 , the radial opposite side of the sidewall  12  may contact and press against a stationary pressure pad  38  mounted on the second side arm  23  of the bracket  21 . As shown most clearly in  FIG. 4 , the stationary pressure pad  38  may be partially inserted in a mounting hole  39  extending through the second side arm  23  of the bracket  21 . 
     As shown most clearly in  FIG. 3 , the press fixture  20  may be releasably attached to a sealant filling nozzle  50  for delivery of uncured sealant into the sealant cartridge  10 . The filling nozzle  50  includes a sealant feed tube  51  having an interior sealant feed line  52 . A threaded discharge tube  53  extends from the sealant feed tube  51  and threadingly engages with the interior threads  16  of the cartridge discharge opening  15 . A sealant discharge opening  54  is provided at the end of the discharge tube  53 . The interior sealant feed line  52  extends through the threaded discharge tube  53  to allow sealant to flow into the interior of the sealant cartridge  10 . A nut  56  is threaded onto the threaded discharge tube  53 . As shown in  FIG. 3 , the threaded discharge tube  53  extends through the central opening  28  of the transverse support bar  27  of the press fixture  20 . The nut  56  may be used to tighten the transverse support bar  27  against the sealant feed tube  51  to thereby releasably secure the press fixture  20  on the filling nozzle  50 . 
     After the press fixture  20  is secured to the filling nozzle  50  as shown in  FIG. 3 , the interiorly threaded  16  discharge opening  15  of the sealant cartridge  10  may be threaded onto the threaded discharge tube  53  to thereby secure the sealant cartridge  10  in a desired filling position in relation to the filling nozzle  50 . Although a threaded discharge tube  53  is shown in  FIG. 3 , it is to be understood that any other suitable connection may be used that adequately secures the press fixture  20  and the sealant cartridge  10  onto the filling nozzle  50 . For example, the portion of the discharge tube  53  extending into the interiorly threaded discharge opening  15  of the sealant cartridge  10  may be replaced with a non-threaded cylindrical fitting that may contact or frictionally engage the interior threads  16  in order to provide a sufficient seal that prevents escape of sealant when it is dispensed from the filling nozzle  50  into the sealant cartridge  10 . In this case, the mounting nut  56  may be fixed or integrally formed with the cylindrical portion of the discharge tube extending through the central opening  28  of the transverse support bar  27 , and the opposite end of the discharge tube may be threaded for removable engagement with interior threads (not shown) inside the sealant feed tube  51 . 
     The air pressure cylinder  30  may be actuated by supplying pressurized air from an air supply control unit  60 , as shown in  FIG. 8 . The air supply control unit  60  includes a first pressurized air outlet fitting  61 , first pressurized air pressure regulator  62 , first pressurized air pressure gauge  63 , and first pressurized air pressure delivery timer  64 . The air supply control unit  60  also includes a second pressurized air outlet fitting  65 , second pressurized air regulator  66 , second pressurized air pressure gauge  67  and second pressurized air pressure delivery timer  68 . A first pressurized air flow Pi may be provided from the first pressurized air outlet fitting  61  of the air supply control unit  60 , and a second pressurized air flow P 2  may be provided from the second pressurized air pressure outlet fitting  65 . In this manner, separate pressurized air flows P 1  and P 2  may be made to two separate press fixtures  20  and air pressure cylinders  30  during a sealant filing operation, as more fully described below. The air supply control unit  60  may contain pneumatic components such as the first and second pressure regulators  62  and  66 , the first and second pressure gauges  63  and  67 , and the first and second timers  64  and  68 , with no electrical power supply needed. 
     The pressure regulators  62  and  66  control the level of air pressure delivered into the pressure chamber  31  of the air cylinder  30 . The pressure level can be adjusted to increase or decrease the force applied by the piston rod  34  and pressure pad  35  against the sidewall  12  of the cartridge  10 . The pressure gauges show the operator what the current pressure level is, e.g., measured in psi. The air pressure may typically range from 10 to 100 psi, or from 40 to 80 psi, or from 50 to 70 psi. For example, the pressure may be about 60 psi. When air pressure at such levels is supplied to the air cylinder  30 , the reciprocating piston is forced outwardly from the pressure cylinder to press against and slightly deform the sidewall  12  of the sealant cartridge  10 . 
     The piston rod  34  may typically be pressed against the cartridge sidewall  12  with a force of from 5 to 50 pounds, for example, from 10 to 30 pounds, or from 15 to 20 or 25 pounds. The force is sufficient to deform the sidewall  12  of the sealant cartridge  10  while causing less deformation of the plunger  18  that is located inside the cartridge  10 . The cartridge  10  may be made of known types of polymeric materials, such as high-density polyethylene (HDPE), and the sidewall  12  is slightly deformable due to the flexibility of the polymeric material and the cylindrical geometry of the sidewall  12 . The plunger  18  may also be made of the same or different type of polymeric material, but its shape, including its domed front end near the location of the pressing force of the piston rod  34  and pressure pad  35 , resists deformation. Thus, the sidewall  12  is deformed slightly from its circular cross-section, but the plunger  18  substantially maintains its circular shape. In this manner, an air gap is provided between the deformed cartridge sidewall  12  and plunger  18  that allows air to escape. The air gap is sufficient to allow the escape of air, for example, a localized gap of the at least 0.2 mm may be temporarily formed, such as from 0.5 to 3 mm, or from 1 to 2 mm. 
     Each air delivery timer  64 ,  68  may determine how long the air pressure cylinder  30  is activated once the sealant filling nozzle  50  starts injecting sealant in the cartridge  10 . After the timer expires, the piston  33  retracts into the air pressure cylinder  30  allowing the cartridge  10  to continue filling normally. If the timer is on too long, sealant may bypass around the plunger  18  and cause a mess. If the timer is too short, all the air is not allowed to escape. The air pressure may typically be applied at the beginning of a filling operation for at least 0.5 or 1 second, and up to 5 seconds. For example, the air pressure may be applied for from 0.5 to 3 seconds, or from 1 to 1.5 seconds. The total filling time for a sealant cartridge may typically range from 10 to 30 seconds, for example, from 12 to 20 seconds, or from 14 to 16 seconds. The air pressure may thus be applied for only a limited time during the initial stage of the filling process, for example, less than 50 percent of the filling time, or less than 15 or 20 percent of the time, or less than 5 or 10 percent of the time. The operator can adjust such air release times as necessary. 
     A typical procedure is as follows: the operator loads an empty cartridge (with a plunger already installed inside) onto the sealant filling machine through the neck side (small end with threads); the pressure cylinder fixture installed on the filling machine is timed to automatically squeeze the cartridge to help trapped air escape out of the cartridge during the filling process, with no operator action required, and the operator loads the cartridge on the filling machine in the normal fashion; the full cartridge is removed from the filler and a cap is placed on; and the filled cartridge is placed in the freezer for storage. 
     The system may include a left and right sealant filling nozzle to allow filling of two sealant cartridges to be installed on the machine. When one sealant cartridge  10  is filled, the operator may trigger a sensor on the filling machine and the other sealant cartridge  10  may begin to fill with sealant. For example, the trigger may include a standard motion detector (not shown) that senses an operator&#39;s hand movement to switch between the cartridge-filling nozzles. A dual air supply control unit  60  as shown in  FIG. 8  may be used to alternately supply pressurized air to first and second press fixtures  20  during such a filling operation. 
     As used herein, the term “sealant” includes both sealant and adhesive formulations. Sealants useful in aerospace and other applications are often pre-mixed frozen compositions (PMF) or two-part systems. Unlike two-component systems, which require mixing the curing paste and the base before use, PMFs may be cured by external factors, such as temperature. For this reason, PMFs may be frozen at, for example, -40° F. to -80° F. in order to suppress or slow the curing reaction. When the PMFs are later brought to room temperature, the curing rate increases significantly. PMFs offer the convenience of being ready for use without mixing and therefore can be more cost- and time-effective than certain two-part systems. 
     As used herein, the term “one component” or “1K” refers to a composition in which all of the ingredients of the sealant may be premixed and stored at ambient conditions or optionally may be premixed and frozen and stored (“pre-mixed frozen” or “PMF” as described below), and wherein the reactive components do not readily react at stored conditions and remain “workable” for at least  10  days after mixing, but instead react only upon activation by an external energy source, under pressure, and/or under high shear force, and in the case of PMFs, thawing. External energy sources that may be used to promote curing include, for example, radiation (i.e., actinic radiation such as ultraviolet light) and/or heat. As used herein, the term “workable” means that the composition is of a viscosity that it is able to be deformed and/or shaped under manual pressure and may have a viscosity less than such viscosity. 
     For purposes of the description above, it is to be understood that the invention may assume various alternative variations and step sequences except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers expressing, for example, quantities of ingredients used in the specification and claims, are to be understood as being modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. 
     It should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between (and including) the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. 
     In this application, the use of the singular includes the plural and plural encompasses singular, unless specifically stated otherwise. In addition, in this application, the use of “or” means “and/or” unless specifically stated otherwise, even though “and/or” may be explicitly used in certain instances. In this application, the articles “a,” “an,” and “the” include plural referents unless expressly and unequivocally limited to one referent. 
     For purposes of the detailed description, it is to be understood that the invention may assume various alternative variations and step sequences, except where expressly specified to the contrary. Moreover, other than in any operating examples, or where otherwise indicated, all numbers such as those expressing values, amounts, percentages, ranges, subranges and fractions may be read as if prefaced by the word “about,” even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open-ended numerical range is described herein, all numbers, values, amounts, percentages, subranges and fractions within or encompassed by the numerical range are to be considered as being specifically included in and belonging to the original disclosure of this application as if these numbers, values, amounts, percentages, subranges and fractions had been explicitly written out in their entirety. 
     Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard variation found in their respective testing measurements. 
     As used herein, “including,” “containing” and like terms are understood in the context of this application to be synonymous with “comprising” and are therefore open-ended and do not exclude the presence of additional undescribed or unrecited elements, materials, ingredients or method steps. As used herein, “consisting of” is understood in the context of this application to exclude the presence of any unspecified element, ingredient or method step. As used herein, “consisting essentially of” is understood in the context of this application to include the specified elements, materials, ingredients or method steps “and those that do not materially affect the basic and novel characteristic(s)” of what is being described. 
     Whereas particular embodiments of this invention have been described above for purposes of illustration, it will be evident to those skilled in the art that numerous variations of the details of the present invention may be made without departing from the invention as defined in the appended claims.