Abstract:
An assembly of fluid conduit parts is disclosed along with a method of assembling, a method of manufacturing and an apparatus for manufacturing the one of the fluid conduit parts. The assembly includes a blow molded part having a first portion. A second part includes a tapered section and a sealing flange extends from the first portion towards a central axis of the first portion at a distance, an end of the sealing flange defines an opening. The second part inserts into the opening and at least part of the tapered section is of a size larger than the opening. The sealing flange flexes upon insertion of the second part into the opening to define a contact surface between the tapered section and the sealing flange that extends around a perimeter of the tapered section where the sealing flange contacts the tapered section.

Description:
FIELD OF THE INVENTION 
       [0001]    The following invention relates generally to blow molded parts and the corresponding molds and methods for manufacturing the same. More particularly the invention relates to a mold, method and blow molded part that provides improved sealing at a junction with another part. 
       BACKGROUND OF THE INVENTION 
       [0002]    The use of blow-molding as a method for manufacturing various sorts of articles is generally well known. Typically, this process involves the use of a mold consisting of two separate halves or portions having cavities of particularly desired shapes and sizes. Usually, one extrudes a large-diameter, sealed tube of molten material (commonly referred to as a “parison”), places the tube between the mold halves, and closes the mold around the tube. Fluid pressure is then introduced into the tube, forcing the molten tube against the walls of the cavities, conforming the tube to the shape thereof. The pressure is maintained until the molten material cools and solidifies. The pressure is then released, the mold halves are pulled apart, and the hardened article is ejected therefrom. 
         [0003]    Before the blow molded part is removed from the mold, it is typically separated from excess parison material called flash. This step can be completed in-mold or can involve secondary operations. Typically, once the parison is extruded between the mold halves, it is pinched off at the top and/or bottom and then blown into a part that takes the shape of the mold cavity. The pinch-off generates excess plastic material in the form of top and/or bottom flash. 
         [0004]    Flash generation imposes limits on blow molding efficiency. In some cases, Flash removal is done with an in mold blade as shown and described in U.S. Pat. Pub. No. 20130175739, the content of which is incorporated by reference herein. 
         [0005]    Although the above referenced publication discusses various parts, systems, methods and/or features that can be used to the task of flash removal in mold, in cases where the part is joined to another part, an improved seal is desired and therefore such improved parts, machinery and methods of manufacture are desired. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an object of the present invention to provide improved in-mold cutting or punching techniques that control wall thickness and/or cut residue in order to provide improved sealing between two parts. 
         [0007]    It is further an object of the present invention to provide a mold and method for manufacture of parts with improved sealing features. 
         [0008]    It is a further object of the present invention to provide parts that securely and/or removably attach to another part to provide a reliable and lasting seal. 
         [0009]    These and other objects are achieved by providing a twist lock blow molded part and a second part having corresponding locking features where the interface between the twist lock blow molded part and the second part includes an integrally formed cut residue that pushes against the second part when the twist lock and second parts are joined and locked in place to provide improved sealing of the interface. 
         [0010]    In one aspect an assembly of fluid conduit parts having a sealed connection between the fluid conduit parts is provided and includes a blow molded part having a first portion. A second part includes an outer section which may be tapered. A sealing flange extends from the first portion towards a central axis of the first portion at a distance, an end of the sealing flange defining an opening. The second part adapted to insert into the opening and at least part of the tapered section of a size larger than the opening. The sealing flange flexing upon insertion of the second part into the opening to define a contact surface between the outer section and the sealing flange such that the contact surface extends around a perimeter of the outer section where the sealing flange contacts the outer section. 
         [0011]    The distance may be measured from an inner surface of the blow molded part and is at least as large as a wall thickness of the blow molded part. A fluid dispensing portion may be connected to the first portion, the fluid dispensing portion including at least one hole such that the fluid can escape the blow molded part through the hole. In some cases a maximum pressure is defined as a maximum fluid pressure against the sealing flange that can be sustained by the sealing flange to prevent fluid from exiting the blow molded part at the end, the fluid may generate a first pressure against the sealing flange, the first pressure having a first value and the at least one hole defining an escape area, the escape area sized such that the maximum pressure is greater than the first pressure. In some cases a lock may hold the blow molded part in place when a fluid is introduced into the blow molded part such that a pressure of the fluid presses against an inner surface of the sealing flange to thereby increase a sealing pressure between the contact area and the tapered section. The second part may be a pipe. A channel may be located between a first end of the first portion and another end of the blow molded part. A protrusion may be located on the second part and sized to fit in the channel such that the protrusion can move from a first position towards a second position, where the first position is closer to the first end than the second position. A catch may be located at an end of the channel such that when the protrusion is located at the second position, the blow molded part can be rotated relative to the second part to engage the protrusion against the catch. A notch may be defined by the catch, the notch located between two peaks formed in the blow molded part such that upon rotation of blow molded part the protrusion presses against one of the two peaks to thereby allow the protrusion to advance past the one of the two peaks such that the protrusion is located within the notch. 
         [0012]    In another aspect a method of creating a sealed connection between two parts is provided and includes one or more of the steps of: providing a blow molded part having a first portion with an inner surface and a sealing flange extending a distance from the inner surface towards a center of the first portion; providing a second part; inserting the second part into the first portion, the first portion having an insertion point defining a radius in a range between a first radius and second radius where the first radius is defined by the inner surface at an end of the first portion and the second radius is equal to the first radius minus the distance; deforming the flange upon insertion of the first portion towards the insertion point; locking the blow molded part in place such that the blow molded part remains stationary relative to the second part when a fluid is introduced into the blow molded part. 
         [0013]    The distance may be equal to or greater than a wall thickness of the first portion. A channel may be located between the end and another end of the blow molded part. A protrusion may be located on the second part and sized to fit in the channel. A catch may be located at an end of the channel. The inserting step may include including moving the protrusion from a first position towards a second position, where the first position is closer to the end than the second position. The locking step may include rotating the blow molded part relative to the second part to engage the protrusion against the catch. The locking step may include engaging the protrusion against a notch defined by the catch, the notch located between two peaks formed in the blow molded part such that upon rotation of blow molded part the protrusion presses against one of said two peaks to thereby allow the protrusion to advance past the one of said two peaks such that the protrusion is located within the notch. The deforming step may include deforming the flange such that an area of contact is created between the flange and an outer surface of the second part and the area of contact is annular. 
         [0014]    In another aspect an apparatus for creating a blow molded part for a fluid conduit assembly is provided and includes a mold having at least two mold sections which when aligned at least partially define a mold cavity. Two mold blades are each movably disposed in one of the two mold sections. A portion of the mold cavity adjacent to the two mold blades defines an end of the mold cavity and the portion of the mold cavity defines a first size aperture at the end of the mold cavity. The two mold blades define a second size aperture, the first size aperture larger than the second size aperture to define a size difference between the first and second size apertures where the size difference is greater than a desired wall thickness of the blow molded part. 
         [0015]    The size difference may be at least two times the desired wall thickness. The two mold blades may be moved to cut the blow molded part contained in the mold cavity, the cut forms a sealing flange that extends towards a center of the first size aperture and is attached to the blow molded part. A channel may extend from a first location towards a second location wherein the first location is located closer to said two mold blades than the second location. A recess at an end of the channel may be located closer to the second location than the first location and may intersect with the end of the channel. Two peaks may be located on either side of a notch, the two peaks and notch formed in the recess such that a protrusion of a second part is retained within the notch to secure the blow molded part to the second part. 
         [0016]    In another aspect a method of manufacturing a blow molded part for a fluid conduit assembly is provided and may include one or more of the steps of: providing at least two mold sections each having a blade therein, the at least two mold sections when aligned defining a mold cavity, the blades when aligned forming a blade aperture wherein an end of the mold cavity adjacent to the blades is larger than the blade aperture by a distance greater than a desired wall thickness of the blow molded part; expanding a parison against the mold cavity such that the parison is thins between the end and a cutting edge of the blade; and moving at least one of the blades to cut the parison at the end. 
         [0017]    The step of expanding may force the parison against the blade such that a local wall thickness of the blow molded part at the blade prior to the moving step is 50% or less of a desired wall thickness of the blow molded part. In some cases the local wall thickness is 75% or less of the desired wall thickness. The desired wall thickness may be approximately half a distance measured from a surface of the mold cavity at the end to the blade aperture. The blade aperture may be round. At least one of the at least two mold sections may include a channel and a recess, the channel extending from a first location towards a second location wherein the first location is located closer to the blades than the second location, the recess at an end of the channel located closer to the second location than the first location and intersecting with the end of the channel. The expanding step may include expanding the parison against the channel and recess such that an inner surface of the parison defines a part channel and part recess corresponding to the channel and recess of the at least one of the at least two mold sections. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  is a perspective view of an exemplary assembly including a blow molded part according to the present disclosure. 
           [0019]      FIGS. 2 and 3  are respectively bottom and front views of a blow molded part as shown in  FIG. 1 . 
           [0020]      FIG. 4  is a side view of the blow molded part shown in  FIG. 1 . 
           [0021]      FIGS. 5 and 6  are exploded and assembled cutaway views of the blow molded part shown in  FIG. 1 . 
           [0022]      FIGS. 7-9  show how assembly is performed for the exemplary assembly of  FIG. 1 . 
           [0023]      FIG. 10  is a perspective view of the blow molded part shown in  FIG. 1 . 
           [0024]      FIG. 11  is a partial cutaway view of the assembly of  FIG. 1 . 
           [0025]      FIG. 12  is an exploded view of a mold for manufacturing the blow molded part of  FIG. 1 . 
           [0026]      FIG. 13A  is a detail view of the mold of  FIG. 12  which is used to manufacture the blow molded part shown in  FIG. 1 . 
           [0027]      FIG. 13B  is a detail partial cutaway view of the blow molded part of  FIG. 1  shown during the molding process prior to movement of the blades. 
           [0028]      FIGS. 14A-C  are detail cutaway views of the sealed connection of  FIG. 1 . 
           [0029]      FIG. 15  is a side view of the cutting blades of the mold shown in  FIGS. 12 and 13A and 13B  which is used to manufacture the blow molded part shown in  FIG. 1 . 
           [0030]      FIG. 16  is a partial cutaway perspective view of a second exemplary assembly including a blow molded part according to the present disclosure. 
           [0031]      FIG. 17  is a perspective of the blow molded part assembly of  FIG. 16 . 
           [0032]      FIGS. 18 and 19  show how the blow molded part assembly of  FIG. 16  is assembled. 
           [0033]      FIG. 20  is a top detail view of the blow molded part assembly of  FIG. 16 . 
           [0034]      FIG. 21  is a side detail view  FIG. 18 . 
           [0035]      FIG. 22  is a partial cross section view of the blow molded part of  FIG. 16 . 
           [0036]      FIG. 23  is a top view of part of a mold for making the blow molded part of  FIG. 16 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0037]    In  FIG. 1  a blow molded part  2  and a second part  4  (in this case a watering can) is shown. It is understood that the second part may also be blow molded.  FIGS. 2 and 3  show additional views of the blow molded part  2 . The blow molded part  2  secures to the second part  4  and creates an connection  6 . The blow molded part has holes  8  at one of its end for dispensing of water and the connection  6  creates a seal between the blow molded part  2  and the second part  4 . It is further understood that the second party may be made by other processes, for example, the second part may be a brass, copper, iron, PEX or other type of pipe/pipe fitting. In one application, the blow molded part  2  is arranged as a shower head such that household plumbing can be used and a pipe or a fitting at the end of the pipe may include the tapered section  146  and/or the protrusions  18  as described in more detail below. 
         [0038]    The outsides of channel  30 ′ and notch  22 ′ are shown in  FIGS. 2 and 3 . The inner sides of these structures allow for insertion and locking of the second part  4  to the blow molded part. The notch  22  may be provided on more than one circumferential location of the blow molded part  2  such that the blow molded part  2  may be rotated to different positions relative to the second part  4 . For example,  FIG. 1  shows the blow molded part  2  having a generally vertical surface  9 , but the blow molded part  2  in this case may be rotated around so that the surface  9  is at approximately a  45  degree angle. Other positions and relative angles are possible, depending on the orientation of the surface  9  relative to the axis of the sealing region  5  and/or the angle of the spout  7  or pipe (not shown). Although  FIG. 1  shows a watering can, it is understood that the features described herein could be applied to other water holding or dispensing devices such as showerheads or end caps for pipes. 
         [0039]      FIG. 4  shows a side view of the blow molded part  2  and section line  5 - 5 .  FIG. 5  shows an exploded sectional view along section line  5 - 5  of the assembly shown in  FIG. 1 . The blow molded part  2  includes peak  20  on either side of the notch  22 . The protrusion  18  on the second part  4  locks within the notch  22  once inserted into the channel and then rotated as shown in  FIGS. 7-9 . Catch  24  retains protrusion  18  within the notch to prevent axial movement of the blow molded part  2  relative to the second part  4 .  FIG. 6  shows an assembled view of  FIG. 5  and the protrusion  18  is retained in the notch  22  between peaks  20 / 20 ′ and further retained by catch  24 . 
         [0040]    The process of locking the blow molded part  2  to the second part  4  is shown by  FIGS. 7-9 , where the parts are inserted together such that the protrusions  18  align with the channels  30  and the blow molded part  2  is inserted  26  over the second part  4 . The parts  2 , 4  are rotated relative to each other  28  such that the protrusion travels over the peak  20 / 20 ′ and is retained in the notch  22  and further retained by the catch  24 . Connection  6  is created to seal the parts  2 / 4 . 
         [0041]    As shown in  FIGS. 10, 11 and 14 , in order to provide improved sealing, a sealing flange  14  extends towards a center of the sealing portion  5  towards central axis  110 . This creates end surface  10 , which is wider than the wall thickness at the sealing portion  5 . Upon insertion  26 , the sealing flange  14  may bend from position  140  to  142  as the outer surface of the second part  4  progressively is inserted into the sealing portion  5 . Since the outer surface  400  may be tapered, the progressive insertion likewise progressively bends the sealing flange  14  and provides pressure between the sealing flange  14  and the outer surface  400  which thereby improves the seal of the connection  6 . Further, when water pressure is introduced through the parts  2 / 4 , the water pressure although relieved by the holes  8  may also provide pressure against the inner surface  146  of the sealing flange. This pressure would tend to press the sealing flange harder against the outer surface and thus provide a more leak resistant seal. 
         [0042]    In  FIGS. 12, 13A /B and  15 , aspects of the mold used in making the blow molded part are shown. Mold cavity  48  is formed upon joining mold sections  40  and  42 . Reference protrusions/recesses  44 / 46  provide for proper alignment of the mold sections. Knives  50  are activated/moved within the mold by ram  52 . As seen in  FIG. 13A , the channel  54  and a recess  58  are defined within the mold cavity and the notch and peak structures of the blow molded part are also provided by the corresponding peak  56  and notch that are shown in the mold. Note that the notch is adjacent to the peak and the second mold half  42  includes the opposite side of the notch/peak combination which thereby creates the notch/peak  22 / 20  of the blow molded part  2 . 
         [0043]    In  FIG. 13B , the blow molded part  2  is shown in the mold prior to cutting. The blade  50  and the corresponding blade on the other side of the mold are aligned such that the center of the blade aperture aligns with center  66 . At the blade tip, the wall thickness  64  is less than the wall thickness  62 . In some cases thickness  64  is  50 % of thickness  62 . In other cases,  75 %. It is understood that the thickness may range anywhere from  90 %- 5 %. This reduction in thickness creates the sealing flange  14  and the movement of the blades severs the parison along a line  60  that aligns with the blade edge. Although in some figures, the sealing flange  14  may have a constant thickness or a gradually reducing thickness. 
         [0044]    In  FIG. 14A  the assembly is shown before part  4  is inserted into the blow molded part  2 .  FIG. 14B  shows the assembly and  FIG. 14C  shows a detail view of  FIG. 14B . As can be seen, sealing flange  14  is generally pointed downward in  FIG. 14A  (in this view) towards the central axis of the assembly. Protrusion  18  inserts along channel  30  in the blow molded part  2  and rotated  28  (as shown in  FIG. 9 ) to engage the protrusion  18  with catch  24 . Upon insertion of the tapered section  146  causes the sealing flange  14  to bend and in some cases stretch inwards to create contact surface  142  which has a width  140 . This contact surface is cylindrical in that the sealing flange defines a round hole. It is understood that the contact surface could be annular in the sense that the tapered  146  and straight  144  sections may have other cross sectional profiles such as square, elliptical and others. In each case, regardless of cross section, the sealing flange would extend into the opening beyond the thickness of the wall (C). Due to the molding process shown, the sealing flange is created both by stretching over the blade and cutting of the blade. The blade initially thins the sealing flange most of the way before cutting, and then upon cutting, there may be a pointed tip  148  or optionally a narrow flat surface at the tip  148  of the sealing flange. As can also be seen, the sealing flange rapidly increases in thickness when moving from the tip  148  towards inner corner  150  of the blow molded part  2 . This provides sufficient flexing such that the sealing flange bends easily while reducing the possibility of plastic deformation of the sealing flange which would decrease the sealing pressure. Pressure such as water pressure is forced against surface  154  which increases sealing pressure at the sealing surface  142 , which may in turn reduce gap  152  and increase the width  140  of contact surface  142 . When the blow molded part  2  is installed over part  4 , the blow molded part is moved in a installation direction and the tip  148  bends opposite the installation direction (or away from part  4 ) while the base of the sealing flange moves in the installation direction (or with the blow molded part  2 ) thus causing the sealing flange to flex in a curved shape to form the gap  152  between stop  12  and the outer surface of the sealing flange. As shown, the sharpness of the curve in the sealing flange when installed progressively increases from the base  150  towards the tip  148  due to the narrowing of the sealing flange from base towards tip  148 . 
         [0045]    In  FIG. 15 , the end surface  10  and the sealing flange  14  of the blow molded part  2  is shown. The distance (A) that the sealing flange  14  extends from the inner wall of the blow molded part  2  is approximately equal to the wall thickness, for example, distance (B) is approximately twice or more distance (A). It is understood that depending on the taper of the outer surface  400  of the second part, the wall thickness of the blow molded part  2 , the distance (A) may vary. For example, a steeper taper of outer surface  400  would result in less extension (A) of the sealing flange being necessary. A shallower taper would likewise require longer extension of the sealing flange. 
         [0046]    Referring to  FIGS. 16-23  a dishwasher  1  includes a feed tube  3  assembly installed therein. The feed tube moves water to different locations within the dishwasher, for example to clean both the bottom and top trays. For example, water spray bars  300 ,  300 ′ may rotate to distribute water and cleaning solution to aid in cleaning. The feed tube assembly  3  may include a number of parts, including parts  2 ′ and  4 ′. One end  21 ′ of part  2 ′ may include the sealing flange  14 ′ which extends and tapers beyond the inner wall at the end  21 ′. This sealing flange  14 ′ is similar to sealing flange  14  shown in the watering can example depicted in  FIG. 1 . 
         [0047]    Part  4 ′ is inserted  26 ′ into the opening of end  20 ′ and rotated  28 ′. As shown in  FIG. 21 , part  2 ′ includes a catch  24 ′. As shown on the outer side of the part  2 ′ edge  24 ″ corresponds to catch  24 ′ and is located at an angle  210  with respect to perpendicular. This angle  210  of the catch  24 ′ acts like a screw thread to cause a slight axial movement  29 ′ of part  4 ′ during rotation  28 ′ because protrusion  18 ′ is retained by the catch  24 ′. This angle  210  and the axial movement  29 ′ may progressively compress or deform the sealing flange  14 ′ during coupling of the parts  274 ′. 
         [0048]    A hose (not shown) may insert over end  204  and rings  200  may provide additional sealing against the hose. 
         [0049]    As shown in  FIG. 22 , a contact area  140 ′ is created between part  4 ′ and part  2 ′ when assembled, which causes the sealing flange  14 ′ to deform slightly. The sealing flange  14 ′ may have a length equal to wall thickness C′ or greater than wall thickness C′ when measured from inner surface  160 ′. 
         [0050]    Referring to  FIG. 23 , a detail of mold section  40 ′ is shown. This mold section includes a moveable blade with two blade sections  50 ′ and  50 ″. Blade section  50 ′ extends into the mold cavity and operates in a similar manner to blade  50  shown for example in  FIG. 13A . Blade  50 ″ does not extend as far into the mold cavity as blade  50 ′ so that end  204  does not include sealing flanges and end  21 ′ does include sealing flanges. Depending on the desired configuration, it is also contemplated that a blade extending into the cavity as blade  50 ′ does could be substituted for  50 ″ to thereby create a blow molded part that would have two end sections  204 / 21 ′ having the sealing flanges. As shown in  FIG. 23 , the recess  202 ′ that creates the edge  24 ′ and catch  24 ″ is approximately perpendicular to the axis of end  21 ′. Depending on the desired configuration, the assembly, recess  202 ′ could be angled to cause the axial movement  29 ′ described herein. 
         [0051]    It is contemplated that the location of the sealing flange could be reversed with respect to the two parts  2 / 4  such that the sealing flange would extend outwardly from the part  4  and that tapering could be used on the outer part. The protrusions, notches and channels described herein may also be reversed with respect to parts  2 / 4  to create the locking features described herein. It is also contemplated that the protrusion and the sealing flange could extend from the same part, depending on the desired configuration. 
         [0052]    Although the invention has been described with reference to a particular arrangement of parts, features and the like, these are not intended to exhaust all possible arrangements or features, and indeed many other modifications and variations will be ascertainable to those of skill in the art.