Not applicable.
This disclosure relates, in general, to improvements in cold-expansion compression collars or reinforcing rings for making leak-free tube connections. More particularly, this disclosure relates to a method for making compression collars for cold-expansion tubing connections, such as in piping made from polyolefin, polyethylene, cross-linked polyethylene, PEX-a, PEX-b, PEX-c, PERT, or any other similar material.
Cold-expansion tubing has been used in plumbing applications for decades in Europe and now increasingly in the United States. The principle behind its operation is to manufacture a hollow, tubular material and imbue it with shape memory properties (e.g., through cross-linking, irradiation, steam, etc.) such that when the tubing is stretched or deformed, the tubing returns to the shape set in its memory during the manufacturing process. In use, cold-expansion tubing can be widened or belled at its end and allowed to shrink back to its original shape after mere moments at room temperature. The elastic forces within the cold-expansion tubing material can be applied to any object that interferes with the cold-expansion tubing as it returns to its original shape. Thus, cold-expansion tubing can form interference fits or joints with fittings, other piping, etc.
It is known in the state of the art that such a cold expansion fitting connection between a pipe and a fitting may be further strengthen by placing a compression collar around the end of the pipe or tubing prior to cold expansion. See e.g., U.S. Pat. No. 5,735,554. By forming both the compression collar and the pipe from a cold-expansion material and by placing the compression collar at the axial end of the pipe, both the collar and pipe can be expanded simultaneously, moved over a fitting, and then allowed to return to substantially the same size and shape at room temperature. The addition of compression collar provides additional compressive forces beyond that of just the pipe to create a better seal for the connection and reinforces the interference fit between the pipe and the fitting over which the pipe is received.
However, more so than just the pipe, the compressive collar is subjected to high loads under elastic deformation. Thus, there is a need to attempt to develop compressive collars having more robust structure and increased strength.
The present disclosure is directed to an improved method of manufacturing compression collars or reinforcing rings for a cold-expansion joining system using injection molding. While injection molding has been used to produce compression collars (see e.g., U.S. Patent Application Publication No. 2008/0315579), such conventional injection molding has been known to introduce knitlines. Knitlines are lines within the injection molded part, often not visible by the naked eye, at which two fronts of material have flowed together during the injection molding process. Such knitlines form weak regions which are more prone to failure than otherwise homogeneous areas of the injection molded collar. To reinforce these lines of inherent weakness, it has been proposed to thicken the wall at the knitlines. See again, U.S. Patent Application Publication No. 2008/0315579.
Disclosed herein is a method of eliminating knitlines altogether in an injection molded compression collar. This elimination of knitlines has the clear advantage of strengthening the part (in comparison to a component having a similar geometry, but with knitlines) and further has the advantage of eliminating thick wall sections which has been proposed by others, thereby reducing material.
To mold a compression collar without knitlines, a continuous gate is utilized at the axial end of a precursor form from which the compression collar will be formed. As such, the injected material flows from the point or points of injection on the axial end, radially outward to the cylindrical walls, and then down the cylindrical walls without the injected material ever flowing into itself. Thus, this continuous gate initially forms a solid wall or capped end at one axial end of the collar which would otherwise be a substantially hollow cylinder. Once the precursor form is injection molded, the excess gate material is removed from the axial end. The removal of excess gate material can be accomplished, for example, through a trimming or punching operation. While it is possible to remove the gate entirely, in some preferred forms, some amount of the axial end wall remains to function as positioning stops or tabs thereby providing a locating mechanism for the compression collar when placed on the end of the piping.
According to one aspect, a method is disclosed for manufacturing a compression collar for reinforcing an interference fit between an end of a pipe and a fitting. A precursor form is injection molded using a cold-expansion material, in which the precursor form comprises a tubular body with an initially closed axial end and a bore that is initially blind formed in the other axial end. Material is removed from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end that connects to the bore thereby forming the compression collar. The opening has an inner periphery with a profile in axial cross section that is different than any profile in axial cross section of an inner periphery of the bore.
In many forms, the cold-expansion material may be one or more of a polyolefin, cross-linked polyolefin, polyethylene, cross-linked polyethylene, PEX, PEX-a, PEX-b, PEX-c, and PERT.
In some forms, because of the manner of injection molding and removed material, the compression collar may include no knitlines. It is contemplated that the injection point(s) may be located at the initially closed axial end, for example at the central axis, such that the injected material flows radially outward along the initially closed end and then axially downward along the tubular sidewalls, such that the front of the injected material never substantially flows into itself to form a knitline. In some forms, the step of removing material from the initially closed axial end of the tubular body of the precursor form to form an opening may involves removing any injection points on the precursor form used in the step of injection molding the precursor form.
Although various ways of removing material from the initially closed axial are contemplated, in some forms the step of removing material from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end may involve punching.
In some forms, the step of removing material from the initially closed axial end of the tubular body of the precursor form to form an opening in the initially closed axial end may form one or more positioning tabs in the inner periphery of the opening. Such position tabs might be useful to position the compression collar on the end of the pipe on which it will be received so that the collar is not, for example, slid past the axial end of the pipe. If there are multiple positioning tabs, then those tabs may be located at even intervals around the inner periphery.
It is contemplated that, in some forms, the opening may have an inner periphery with a profile in axial cross section that matches, in part, an adjacent profile in axial cross section of an inner periphery of the bore with a non-matching part of the profiles providing at least one positioning tab in the inner periphery of the opening.
In some forms, the compression collar may further include a supporting extension or “tail” on the axial end of the compression collar opposite the axial end having the opening that is removed. Such a supporting extension may be configured to reinforce a thinned section of the pipe past the fitting. The supporting extension may have different shapes. For example, in some forms, the supporting extension mat tapers as it extends away from the opening (meaning that the wall thickness decreases). In some other forms, the supporting extension may have a relatively constant wall thickness, although this wall thickness may still be less than the wall thickness of the main portion of the compression collar.
In some forms, the method may further involve, during injection molding, forming flat surfaces on the inner periphery of the bore of the compression collar that are parallel to a central axis of the compression collar. These flat surfaces may be configured to be tangent to a radially-outward facing surface of the pipe around which the compression collar will be received during its attachment to the end of the pipe in forming a connection.
In some forms, the method may further include forming a chamfered edge or a curved corner with a radius of curvature in the bore at the axial end of the bore that is opposite the axial end in which opening is removed.
According to another aspect, a compression collar is disclosed for reinforcing an interference fit between an end of a pipe and a fitting. The compression collar includes a tubular body formed by injection molding a cold-expansion material in which the tubular body has a bore extending axially therethrough and a removed opening on one initially-closed axial end of the tubular body in which the removed opening connects to the bore. The opening has an inner periphery with a profile in axial cross section that is different than any profile in axial cross section of an inner periphery of the bore.
In some forms, the cold-expansion material may be one or more of a polyolefin, cross-linked polyolefin, polyethylene, cross-linked polyethylene, PEX, PEX-a, PEX-b, PEX-c, and PERT.
In some forms, the compression collar includes no knitlines and no residual injection points from injection molding.
In some forms, the compression collar may further include flat surfaces on the inner periphery of the bore that are parallel to a central axis of the compression collar such that the flat surfaces are configured to be tangent to a radially-outward facing surface of the pipe around which the compression collar is to be received. In some forms, the removed opening may include positioning tabs and there may be as many flat surfaces on the inner periphery as there are positioning tabs.
In some forms, the compression collar may further include a supporting extension or “tail” on the axial end of the compression collar opposite the axial end having the opening that is removed. Such a supporting extension may be configured to reinforce a thinned section of the pipe past the fitting. The supporting extension may have different shapes. For example, in some forms, the supporting extension mat tapers as it extends away from the opening (meaning that the wall thickness decreases). In some other forms, the supporting extension may have a relatively constant wall thickness, although this wall thickness may still be less than the wall thickness of the main portion of the compression collar.
In some forms, the compression collar may further include a chamfered edge or a curved corner with a radius of curvature in the bore at the axial end of the bore that is opposite the removed opening.
In some forms of the compression collar, the inner periphery of the removed opening includes one or more positioning tabs in which the positioning tab(s) is/are configured to axially position the compression collar on an end of a pipe.
In some forms, the removed opening may have an inner periphery with a profile in axial cross section that matches, in part, an adjacent profile in axial cross section of an inner periphery of the bore and with a non-matching part of the profiles defining one or more positioning tabs in the inner periphery of the removed opening.
These and still other advantages of the invention will be apparent from the detailed description and drawings. What follows is merely a description of some preferred embodiments of the present invention. To assess the full scope of the invention the claims should be looked to as these preferred embodiments are not intended to be the only embodiments within the scope of the claims.
Looking first at
The precursor form 100 may have an overall tubular shape with a cylindrical bore formed through one end of the cylindrical shape with an initially closed axial end 108 at the opposing end, having been injection molded with an axial length 102, an inner diameter 104, and an outer diameter 106. This makes the bore initially a blind bore. The cylindrical bore of the precursor form 100 is formed in the one end of the cylindrical shape that will be slid over the end of a section of pipe in use. In order to facilitate sliding the final collar 200 over the pipe, an end chamfer 120 (as illustrated in
The desired axial length 102 of the precursor form 100 may be based on the inner and outer diameters 104, 106 and/or the intended use of the compression collar 200 manufactured from the precursor form 100. For example, the inner diameter 104 of the precursor form 100 may range from about a ¼″ to about 6″ in order to just fit or slide over the outer diameter of standard cold-expansion pipe for residential or commercial applications. Additionally, the compression collar 200 resulting fabricated from the precursor form 100 may be certified under the ASTM F1960 standard and may be used with standard manual pipe expanders or even automatic expander power tools, such as the M12™ 12V Cordless Lithium-Ion ProPEX® Expansion Tool by Milwaukee Electric Tool®, for example.
The formation of the closed axial end or continuous gate 108 at the end of the precursor form 100 during injection molding may be facilitated by using a fan gate or other similar gate, such as a sprue gate or submarine gate, for example. A fan gate injection point 110 is preferably located at the center of the closed end 108 corresponding with the central axis of the precursor form 100. The mold for the precursor form 100 of the compression collar 200 may be arranged such that the closed end 108 is located at the top. In this way, the injection molding material flowing through the central gate injection point 110 has a single front that flows radially outward and then substantially uniformly down and around the whole mold to fill in the tubular-shaped sidewall of the precursor form 100. Because there is only one material front flowing around and down into the mold, no knitlines are formed where the flowing materials meet. This advantageously eliminates any potential weak points in the final compression collar 200 that may tear when subjected to expanding forces or that may otherwise have to be reinforced.
After molding, the material comprising the closed axial end 108 of the precursor form 100 is then removed to form an opening (i.e., a removed opening) that is connected to the bore. In order to remove the material from the closed axial end 108 of the precursor form 100, cutting, trimming, punching, or similar known operations may be performed. As a non-limiting example, material may be removed or punched from the initially closed axial end 108 of the precursor form 100 by using a die on a punch press. The die is shaped to match the material to be removed from the closed end 108.
Rather than remove the closed end 108 material completely, some material may be left to function as positioning tabs or stops 212, as seen in
The positioning tabs 212 may vary in height (measured axially) and are not limited to the embodiment shown in
Similarly to the height, the shape of the positioning tabs 212 may vary and are not limited to the embodiment shown in
The positioning tabs 212 may vary in width from the embodiment shown in
As an alternative to the plurality of positioning tabs 212, there may be only one positioning tab. The single positioning tab may vary in width from the positioning tabs 212 shown in
The compression collar 400 includes positioning tabs 412 as well as a supporting extension 422 that extends beyond a nominal length 406 of the compression collar 400. The supporting extension 422 may taper in wall thickness moving from the region of nominal length 406 toward the end. Alternatively, the supporting extension 422 may maintain the same wall thickness.
In production, the supporting extension 422 may be incorporated into the compression collar 400 during injection molding, as described above. The combined lengths of the nominal length 406 of the compression collar 400 and the supporting extension 422 may be based on the desired wall thickness and the inner and outer diameters of the compression collar 400, the intended use of the compression collar 400, and/or the type and insertion length of the fitting 600.
The supporting extension 422 may advantageously provide additional strength and external support for an area 316 of the connection 300 where the pipe 500 meets the axial end of the fitting 600. In this area 316, the wall of the pipe 500 may be stretched or thinned due to the expansion joining process. Thus, providing the compression collar 400 with the supporting extension 220 surrounding this area 316 may reduce the hydrostatic stress in the wall of the pipe 500, increasing the pressure capability of the pipe 500 and bringing the margin of safety for practical applications back up to at least the original design limits. In this way, the compression collar 400 can provide not only extra compressive force at the sealing interface on the fitting 600 to prevent the connection 300 from leaking, but also additional external support for the pipe 500 in the area 316 of potential weakening just beyond the inserted length of the fitting 600.
Additionally included on the compression collar 700 is one or more flat surfaces or strips 714 that are axially tangent to the pipe over which the collar 700 is placed in use. These flat surfaces 714 may be formed on the inner wall of the cylindrical bore during the injection molding process. The flat surfaces 714 advantageously provide a slight amount of friction for a lightly snug fit between the compression collar 700 and the radially outward facing surface of the pipe that will keep the collar 700 from sliding off the pipe prior to expansion. A further advantage of the flat surfaces 714 is that they are parallel with the central axis of the compression collar 700 such that the same slight amount of friction is applied evenly all along the end of the section of pipe which is inserted into the collar 700.
The flat surfaces 714 may vary in width and are not limited to the embodiment shown in
The number of flat surfaces 714 may be based on the width of the flat surfaces 714, the inner and outer diameters 704, 706 of the compression collar 700, the outer diameter of the pipe over which the collar 700 is to be placed, and/or the number of positioning tabs 712. The flat surfaces 714 may be evenly distributed around the inner diameter 704 of the compression collar 700 or alternatively distributed unevenly. The flat surfaces 714 may be aligned and/or misaligned with the positioning tabs 712. As an alternative to the plurality of flat surfaces 714, there may be only one flat surface. The single flat surface may vary in width from the flat surfaces 314 shown in
It should be appreciated that various other modifications and variations to the preferred embodiments can be made within the spirit and scope of the invention. Therefore, the invention should not be limited to the described embodiments. To ascertain the full scope of the invention, the following claims should be referenced.
This application claims the benefit of U.S. Provisional Patent Application No. 62/383,001 entitled “Injection Molded Cold-Expansion Compression Collar” filed Sep. 2, 2016, the contents of which are incorporated by reference herein in its entirety for all purposes.
Number | Name | Date | Kind |
---|---|---|---|
2433602 | Coss | Dec 1947 | A |
2739829 | Pedlow et al. | Mar 1956 | A |
2930634 | Merritt | Mar 1960 | A |
2933428 | Mueller | Apr 1960 | A |
3260540 | Houot | Jul 1966 | A |
3291670 | Usab | Dec 1966 | A |
3567259 | Benson et al. | Mar 1971 | A |
3591674 | Engel | Jul 1971 | A |
3656783 | Reeder | Apr 1972 | A |
3759553 | Carter | Sep 1973 | A |
3887992 | Parmann | Jun 1975 | A |
3972548 | Roseen | Aug 1976 | A |
4036514 | Hannover | Jul 1977 | A |
4070044 | Carrow | Jan 1978 | A |
4305608 | Stuemky | Dec 1981 | A |
4408786 | Stuemky | Oct 1983 | A |
4682797 | Hildner | Jul 1987 | A |
4997214 | Reese | Mar 1991 | A |
5099888 | Valls, Jr. | Mar 1992 | A |
5254824 | Chamberlain et al. | Oct 1993 | A |
5566708 | Hobbs, Jr. | Oct 1996 | A |
5735554 | Imgam | Apr 1998 | A |
5744085 | Sorberg | Apr 1998 | A |
5829795 | Riesselmann | Nov 1998 | A |
5931200 | Mulvey et al. | Aug 1999 | A |
6159408 | Kitayama et al. | Dec 2000 | A |
6270125 | Rowley et al. | Aug 2001 | B1 |
6367850 | Thrift et al. | Apr 2002 | B1 |
6581982 | Nghiem | Jun 2003 | B1 |
6585297 | Mullen, Jr. | Jul 2003 | B2 |
6783160 | Rowley | Aug 2004 | B2 |
6832502 | Whyte et al. | Dec 2004 | B1 |
7128560 | Tandart | Oct 2006 | B2 |
7364206 | Romanelli et al. | Apr 2008 | B2 |
7370889 | Maunder et al. | May 2008 | B2 |
7448652 | Poast et al. | Nov 2008 | B2 |
7654588 | Schwalm | Feb 2010 | B2 |
7744803 | Jackson et al. | Jun 2010 | B2 |
D623277 | Guzzoni et al. | Sep 2010 | S |
7922475 | Gueit | Apr 2011 | B2 |
D637697 | Steiner | May 2011 | S |
7959429 | Munoz De Juan | Jun 2011 | B2 |
8069699 | Glenn et al. | Dec 2011 | B2 |
8146225 | Olinger et al. | Apr 2012 | B2 |
8211347 | Tabanelli | Jul 2012 | B2 |
8302448 | Woelcken et al. | Nov 2012 | B2 |
8365382 | Hedstrom | Feb 2013 | B2 |
8517715 | Thorson et al. | Aug 2013 | B2 |
8562331 | Schramm et al. | Oct 2013 | B2 |
8745843 | Michels et al. | Jun 2014 | B2 |
D730494 | Arment et al. | May 2015 | S |
9248617 | Lundequist et al. | Feb 2016 | B2 |
9475965 | Conrad et al. | Oct 2016 | B2 |
9625069 | Schwager | Apr 2017 | B2 |
9822915 | Smahl | Nov 2017 | B2 |
20030212180 | Rietz et al. | Nov 2003 | A1 |
20030230895 | Brown et al. | Dec 2003 | A1 |
20050161939 | Poll | Jul 2005 | A1 |
20060082156 | Runyan | Apr 2006 | A1 |
20080315579 | Smahl et al. | Dec 2008 | A1 |
20090302602 | Larsson | Dec 2009 | A1 |
20110151045 | Gueit | Jun 2011 | A1 |
20120153614 | Olinger et al. | Jun 2012 | A1 |
20120181727 | Lindner et al. | Jul 2012 | A1 |
20120211978 | Gardiner | Aug 2012 | A1 |
20120217674 | Greding | Aug 2012 | A1 |
20120217743 | Parisi | Aug 2012 | A1 |
20130307260 | Laakso et al. | Nov 2013 | A1 |
20140300107 | Altenrath | Oct 2014 | A1 |
20140338178 | Lehmann et al. | Nov 2014 | A1 |
20150000368 | Barthlein et al. | Jan 2015 | A1 |
20150165507 | Reese | Jun 2015 | A1 |
20150167874 | Buerli et al. | Jun 2015 | A1 |
20150258598 | Frenken | Sep 2015 | A1 |
20150306652 | Baerthlein et al. | Oct 2015 | A1 |
20160008866 | Houle et al. | Jan 2016 | A1 |
Number | Date | Country |
---|---|---|
2793501 | Jul 2006 | CN |
19948597 | Apr 2000 | DE |
0878287 | Nov 1998 | EP |
0897081 | Feb 1999 | EP |
0530387 | Oct 1999 | EP |
0728979 | May 2000 | EP |
1031781 | Aug 2000 | EP |
1240981 | Sep 2002 | EP |
1118401 | Mar 2004 | EP |
1326045 | Feb 2005 | EP |
1160027 | Apr 2005 | EP |
1543903 | Jun 2005 | EP |
1674241 | Jun 2006 | EP |
1837581 | Sep 2007 | EP |
1933073 | Jun 2008 | EP |
2025988 | Feb 2009 | EP |
2090384 | Aug 2009 | EP |
2090385 | Aug 2009 | EP |
2153917 | Feb 2010 | EP |
2130664 | Jul 2011 | EP |
2607764 | Jan 2015 | EP |
1158011 | Jul 1969 | GB |
2352665 | Feb 2003 | GB |
2371253 | Apr 2004 | GB |
2398612 | Aug 2004 | GB |
9418486 | Aug 1994 | WO |
9529360 | Nov 1995 | WO |
9625255 | Aug 1996 | WO |
9841790 | Sep 1998 | WO |
0079172 | Dec 2000 | WO |
0173330 | Oct 2001 | WO |
0232597 | Apr 2002 | WO |
02077510 | Oct 2002 | WO |
03004917 | Jan 2003 | WO |
03004918 | Jan 2003 | WO |
2005046906 | May 2005 | WO |
2007006863 | Jan 2007 | WO |
2007065955 | Jun 2007 | WO |
2011128049 | Oct 2011 | WO |
2014032911 | Mar 2014 | WO |
20140758 | May 2014 | WO |
2014141190 | Sep 2014 | WO |
2014177435 | Nov 2014 | WO |
2015162155 | Oct 2015 | WO |
Entry |
---|
Uponor Plumbing System, Uponor Professional Plumbing Installation Guide [online], 2013 [retrieved on Jan. 10, 2022], Retrieved from the Internet:<URL: https://www.gwkent.com/media/pdf/product/4245/AQUAPEX_Install.pdf>. |
Uponor, ProPEX Ring [online], Mar. 13, 2008 [retrieved on Jan. 12, 2022], Retrieved from the Internet:<URL: https://sweets.construction.com/swts_content_files/3210/275466.pdf>. |
WIRSBO, Installation Handbook, Radiant Floor, Radiant Ceiling, RADIPEX Baseboard, and Radiator Supply Systems [online], 6th Edition. Aug. 1999 [retrieved on Jan. 12, 2022], Retrieved from the Internet:<URL: http://www.republicsupplyco.com/SpecSheets/HeatInstall6thEd_Hbk1-17.pdf>. |
Office Action issued from the United States Patent Office for U.S. Appl. No. 15/686,758 dated Jan. 6, 2021 (12 Pages). |
Huang et al., “Experimental Study and Computer Simulation of the Effect of Spider Shape on the Weld-Lines in Extruded Plastic Pipe”, Polymer Engineering and Science, Sep. 1998, vol. 38 No. 9, pp. 1506-1522. |
Number | Date | Country | |
---|---|---|---|
20180065282 A1 | Mar 2018 | US |
Number | Date | Country | |
---|---|---|---|
62383001 | Sep 2016 | US |