WO2002004209A1

WO2002004209A1 - Heat fusion of plastic pipe without inner fusion bead

Info

Publication number: WO2002004209A1
Application number: PCT/US2001/021493
Authority: WO
Inventors: Robert Williams Carter; Robert Ward Carter
Original assignee: Wrb Company, Inc.
Priority date: 2000-07-06
Filing date: 2001-07-06
Publication date: 2002-01-17
Also published as: AU2001271899A1

Abstract

The fusion pipe joint of the present invention is formed without a heat fusion bead on the interior surfaces of the pipe joint. To form the joint, the end surfaces (64) of the two pipe ends (20) are faced by removing a quantity of pipe material from the inner edge of the pipe end surface (90). When the two pipe ends (20) are subsequently heated and brought together, a gap or channel is created, rather than protruding into the interior surface of the pipe joint.

Description

Specification HEAT FUSION OF PLASTIC PIPE WITHOUT INNER FUSION BEAD

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates generally to the joinder of the ends of plastic pipe, and more particularly to the heat fusion of polyethylene pipe.

Description of the Prior Art In fabricating plumbing systems, manageable lengths of pipe are joined together to create the plumbing system. As is well known to those skilled in the art, differing types of pipe joining systems are utilized with differing types of pipe materials. For instance, galvanized steel pipe is generally joined together utilizing threaded couplings, copper pipe is generally joined together utilizing soldered fittings, PVC pipe is generally joined utilizing glued fittings, and polyethylene or polyolefin pipes are generally joined together utilizing a heat fusion process. The present invention constitutes an improvement in the heat fusion process for joining lengths of pipe, particularly polyolefin and/or polyethylene pipe.

The standard prior art heat fusion process for joining the ends of polyolefin and polyethylene pipe is best described with reference to Figs. 1, 2 and 3, wherein Fig. 1 depicts the end 20 of a length of polyethylene pipe 24, and the standard heat fusion process involves the joinder of two such pipe ends together, as is described in the American Society for Testing and Materials Designation publication D2657-97. As is known to those skilled in the art, various pipe end heat fusion devices exist, such as the model BS-4 device manufactured by Central Plastics Company, Shawnee, OK. Such a device 26 is diagrammatically depicted in Fig. 2, and includes two opposed pipe alignment jig end clamping mechanisms 28. The pipe ends 20 to be joined together are inserted and clamped into the pipe alignment jig clamps 28 with a gap 32 between the ends 20. A pipe end facing tool 36, such as the Electric Trimmer Model TL-4B manufactured by Central Plastics Company, is then inserted within the gap to properly face each pipe end by creating a squared off end face 40 at a 90° angle to the longitudinal pipe axis 44. Such pipe end facing tools 36 typically include two flat knife blades 48 which simultaneously cut both pipe ends to remove material to achieve the appropriate flat parallel end facing surface 40.

After the two pipe ends are properly faced, the facing tool 36 is removed from the gap 32 and a pipe end heating iron is placed into the gap. The heating iron (not shown in Figs. 1- 3), which is preferably preheated to a temperature of 450-500° Fahrenheit, simultaneously heats both ends 20 of the pipes. The ends are sufficiently heated (typically about 50-60 seconds) when it is seen that the edges of the pipe ends curl back away from the heating iron. At this point, the pipe ends are pulled apart, the heating iron is removed and the pipe clamps 28 are brought together to pull the heated pipe ends together. As depicted in Fig. 3, where the prior art heat fusion step is properly done, the pipe end material has been pushed together to form an exterior radially projecting double bump bead 52 and an interior radially projecting double bump bead 56. The pipe joint is then allowed to cool, whereupon the pipe ends are heat fused together.

A problem that exists with the prior art heat fused pipe described above is the existence of the inner bead 56. Specifically, plumbing codes require that the inner surface of pipes and pipe joints be free of any inwardly projecting obstructions that can lead to debris accumulation and pipe clogging. Thus, to utilize pipe systems having heat fused joints it is often necessary to remove the inner bead 56 that has been created using the prior art heat fusion techniques described above. To achieve this, following the heat fusion step, a pipe reaming tool has typically been inserted into the end of the joined pipe to ream out the inner bead; where the typical joined pipe section is twenty feet long, the reaming tool is also about 20 feet long. The inner bead reaming step is particularly cumbersome and wasteful of time and energy, and therefore increases the expense of the heat fusion process.

The present invention provides a solution to this problem by joining the pipe ends together in a heat fusion process that does not create the unwanted inner bead 56. The present invention requires no new process steps or materials, and it omits the inner bead reaming step that was previously required, thus saving time and expense.

SUMMARY OF THE INVENTION

The fusion pipe joint of the present invention is formed without a heat fusion bead on the interior surfaces of the pipe joint. To form the joint, the end surfaces of the two pipe ends are faced by removing a quantity of pipe material from the inner edge of the pipe end surface. When the two pipe ends are subsequently heated and brought together, a gap or channel is created in the location of the removed material, and the heated pipe end material fills the channel, rather than protruding into the interior surface of the pipe joint. In the preferred embodiment, the material is removed from the end surface of the pipe to form a step which is cut into the inner edge of the pipe end face.

The pipe end face of the present invention is formed utilizing a novel pipe end facing blade. The blade includes a compound knife edge which is utilized in a standard pipe end facing device to remove material from the inner edge of the pipe end surface. A compound knife edge in the form of a stepped edge is utilized to create the stepped pipe end facing of the present invention.

It is an advantage of heat fusion pipe joint of the present invention that a pipe joint is created without an internal heat fusion bead.

It is another advantage of the heat fusion pipe joint of the present invention that the heat fusion pipe joint is created having a relatively smooth inner surface, such that pipe obstruction and clogging is reduced. It is a further advantage of the heat fusion pipe joint of the present invention that a subsequent pipe joint internal bead reaming step or tool is not required to complete the heat fusion joint.

It is an advantage of the pipe end for heat fusion joints of the present invention that it includes a recessed area wherein pipe material has been removed from an inner edge of the pipe end surface.

It is another advantage of the pipe end for heat fusion joints of the present invention that a step shaped recess is formed in the inner edge of the pipe end surface, such that no inwardly projecting heat fusion bead is formed upon the heat fusion joiner of two such pipe ends.

It is an advantage of the method for forming a heat fusion pipe joint of the present invention that no inwardly projecting heat fusion bead is formed during the heat fusion step, such that a subsequent pipe reaming step is not required.

It is another advantage of the method for fabricating a heat fusion pipe joint of the present invention that it is less time consuming and therefore less expensive than previously formed heat fusion pipe joints.

It is a further advantage of the method for fabricating a heat fusion pipe joint of the present invention that radiant heat melts the surface of a shoulder portion of a pipe end face recess, such that a fused joint is formed throughout the complete thickness of the pipe. These and other features and advantages of the present invention will no doubt become apparent to those skilled in the art upon reading the following detailed description, which makes reference to the several figures of the drawings.

IN THE DRAWINGS Fig. 1 is a perspective view of a prior art pipe end after a pipe end facing step;

Fig. 2 is a diagrammic depiction of a standard pipe end heat fusion apparatus; Fig. 3 is a cross-sectional view depicting a prior art heat fusion joint; Fig. 4 is a side cross-sectional view diagrammically depictmg the end facing step of the present invention;

Fig. 5 is a perspective view of the novel faced end configuration of the present invention;

Fig. 6 is a side cross-sectional view of the faced end configuration of the present invention, taking along lines 6-6 of Fig. 5;

Fig. 7 is a side cross-sectional view diagrammatically depicting two pipe ends of the present invention clamped within a standard heat fusion device; Fig. 8 depicts the pipe end heating step of the heat fusion device depicted in Fig. 7;

Fig. 9 depicts the initial butting together of the two pipe ends following the heating step depicted in Fig. 8;

Fig. 10 depicts the completed heat fusion joint of the present invention; Fig. 11 is a perspective view depicting a prior art pipe end facing blade that is utilized in the prior art pipe fusion device depicted in Fig. 2 to create the prior art pipe end facing depicted in Fig. 1;

Fig. 12 is a perspective view depicting the novel pipe end facing blade of the present invention that is utilized in the heat fusion device to create the novel pipe end face configuration of the present invention depicted in Figs. 5 and 6; Fig. 13 is a rear elevational view of the end facing blade depicted in Fig. 12;

Fig. 14 is a side elevational view of the pipe end facing blade depicted in Figs. 12 and 13; and

Fig. 15 is an end elevational view of the end facing blade depicted in Fig. 12 as used to face a pipe end.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As described hereabove with regard to Fig. 1, 2 and 3, prior art heat fusion pipe joints are fabricated with an unwanted internal, radially inwardly projecting bead 56. Where plumbing codes require that the inner surface of pipe systems be relatively smooth and unobstructed, the internal bead 56 must be removed, and this removal process typically requires an additional, time-consuming and therefore expensive step in which a pipe reaming tool is inserted into the pipe end following the pipe joint heat fusion step, to mechanically smooth the inner surface of the heat fusion joint. The pipe reaming tool is similar to a large tooth hole saw mounted on a shaft and powered by a heavy duty Vz HP drill motor. Where the length of the joined pipe section may reach twenty to forty feet or more, it is extremely cumbersome and time-consuming to insert a pipe reaming tool at the end of a twenty to forty foot shaft to remove the inner bead. As is next described, the present invention creates a heat fusion pipe joint that does not have the inner bead. Rather the heat fusion joint is formed with relatively smooth interior joint surfaces. Therefore, the cumbersome, expensive, time- consuming pipe joint inner bead reaming step is no longer required and pipe reaming debris is not left within the pipe.

Fig. 4 is a side cross-sectional view that is similar to Fig. 2 described hereabove. Specifically, Fig. 4 depicts two unfinished pipe ends 20 that are held by clamps 28 of a pipe end heat fusion device 26. Each pipe end 20 is defined by a cylindrical side wall 58 of pipe material having an exterior surface 60, an interior surface 62 and an end surface 64. An outer end edge 66 is formed between the exterior surface 60 and the end surface 64, and an inner end edge 68 is formed between the interior surface 62 and the end surface 64. A novel pipe end facing blade 70 of the present invention is used with a standard pipe end facing tool 36 that is disposed in the gap 32 between the two pipe ends 20. A detailed description of the pipe end facing blade 70 of the present invention is provided hereinbelow with reference to Figs. 11-14. Two of the pipe end facing blades 70 are adapted to fit within the standard pipe end facing tool 36 of the prior art heat fusion device 26, and for purposes of the current discussion, it is seen that each blade 70 includes a knife edge 74 having a stepped outer portion 78.

In the pipe end facing step, the end surface 64 of each pipe end 20 is simultaneously directed 82 against a blade 70 to create an end face that is generally perpendicular to the longitudinal axis of the pipe. Fig. 5 presents a perspective view of the pipe end face 86 of the present invention that is achieved using the stepped facing blade 70 of the present invention; and Fig. 6 is a side cross-sectional view of the pipe end face 86 of Fig. 5 taken along lines 6-6 of Fig. 5. Significantly, in comparison with the prior art flat end pipe face 40 depicted in Fig. 1, the pipe end face 86 of the present invention includes an internal recess or step 90 that is cut into the end surface 64 of the pipe end 20 to create a shoulder 92 within the pipe end face 86. The step 90 essentially results from the removal of pipe material from the inner end edge 68 of the pipe end surface 64. As is best seen in Fig. 6, the step 90 basically comprises a cylindrical bore that is coaxial with the central axis 44 of the pipe 20 and cut into the sidewall 58 of the pipe end 20. The step 90 is cut into the sidewall 58 to a depth D at the shoulder 92, and is cut into the sidewall 58 a radial distance R where the total sidewall thickness is T. As will be understood by those skilled in the art, suitable dimensions D and R will vary for pipe of differing diameters and differing sidewall thickness T, and different blades 70 with differing dimensions must be used for different pipe wall thicknesses. Furthermore, a range of values for D and R will provide suitable results for each particular dimension of pipe. For instance, for 4 1/2 inch OD polyethylene pipe having a sidewall thickness T of approximately 0.291 inches, a step 90 having a depth D of from 0.025 to 0.05 inches and a radial projection R of from 0.05 to 0.175 inches can provide suitable results. Preferred step dimensions for a 4 1/2 inch pipe are where D equals 0.04 inches and R equals 0.15 inches. Generally R is about one half of T for good results. Suitable step dimensions for pipe of various diameters and sidewall thicknesses can be determined by those skilled in the art after comprehending the basic concepts of the invention and the general range of step dimensions given above. Fig. 7 is a side cross-sectional view that depicts the two pipe ends 20 clamped within the fusion device 26 after they have been properly faced with the internal step 90. The facing tool 36 has been removed such that a gap 32 exists between the ends 20. Thereafter, as depicted in Fig. 8, a heating iron 104, such as a Model 4 Electric Fusion tool manufactured by Central Plastics Company, is inserted into the gap 32 between the pipe ends 20, and the pipe ends are brought together against the heating surfaces of the iron 104. A preferred fusion temperature is approximately 495 to 505° Fahrenheit. Preferably, the iron 104 is heated to the appropriate pipe fusion temperature prior to insertion between the pipe ends 20. As seen in Fig. 8, the pipe ends 20 are heated in contact with the iron 104 until external beads 108 commence to form on the exterior surface 60 of the pipe ends 20; the beads 108 are visible to the user. Simultaneously, although not visible to the user, internal beads 112 that are formed on the inner surface of the pipe ends 20, are formed within the steps 90 of the pipe ends 20. Also the shoulders 92 are radiantly heated to melting temperature although no bead is formed. Thereafter, as depicted in Fig. 9, the heating iron 104 is removed and the clamps 28 of the fusion device 26 are manipulated to move 116 the heated pipe ends 20 together, such that the heated end surfaces 86, external beads 108, and the internal beads 112 also make fusion contact. The two pipe ends 20 are pressed together 116 as the heat fusion process is conducted. As depicted in Fig. 10, the pipe ends 20 are held together within the heat fusion device until the pipe ends 20 are properly coupled and fused together to form a heat fusion joint 118. Significantly, as shown in the cross-sectional view of Fig. 10, when the heat fusion process is completed the exterior beads 108 are formed on the exterior surface 60 of the pipe, just as they existed in the prior art fused pipe (see Fig. 3), however, no interior bead is formed to project into the interior diameter of the pipe. Rather, the interior beads 112, as depicted in Fig. 10, have been merged into and fill and fuse the space created by the steps 90 that were cut into the end surface 64 of the pipes ends. That is, the steps 90 effectively form an interior channel 122 (See Fig. 9) within the heat fusion joint 118 that is filled by the internal beads 112, such that the internal beads from the heat fusion process do not project into the internal diameter of the pipe at the fusion joint. The heat fusion joint 118 of the present invention thus includes a relatively smooth heat fusion formed joint surface throughout the interior surfaces of the pipe ends 20. Because the heat fusion joint of the present invention is completed without the creation of an internally projecting bead, the cumbersome, expensive and time-consuming mechanical step of reaming out such an internally projecting bead deep inside the pipe is no longer required. Thus, the present invention constitutes a significant improvement over the prior art heat fusion joint, and it is accomplished without any additional fabrication steps or expense. It can now be realized that a significant feature of the present invention is the removal of material from the inner surface of the pipe end wall 40 during the pipe end facing step. In the preferred embodiment described above, the material was removed through the formation of a step 90 that was accomplished with the novel pipe facing blade 70, and a more detailed description of the blade 70 is next presented with the aid of Figs. 11-14. Initially, by way of comparison, a perspective view of a standard prior art pipe facing blade is presented in Fig. 11. Basically, the prior art blade 48 is a generally rectangular piece of hardened steel having a beveled surface 124 that forms a single, straight knife edge 128. Two blade engagement bores 132 are formed through the blade 48 and machine screws (not shown) are utilized to removably engage the blade 48 into the pipe end facing tool 36 that is supplied with the standard heat fusion device 26, as described hereabove with regard to Figs. 2 and 4. As described hereinabove, the flat, straight knife edge 128 of the prior art facing blade 48 is utilized to create the two parallel, flat faced pipe end surfaces 40 as depicted in Fig. 1.

The novel pipe end facing blade 70 of the present invention is depicted in Figs. 12, 13 and 14, wherein Fig. 12 is a perspective view, Fig. 13 is a rear elevational view and Fig. 14 is a side elevational view. As depicted in Figs. 12, 13 and 14, the facing blade 70 of the present invention is formed from a generally rectangular piece of hardened stainless steel that includes a beveled surface 140 that terminates in a central knife edge 74. At least one, and preferably two recessed areas 152 are formed in the rear surface 156 of the blade, such that a stepped knife edge 78 is formed at the outer edges of the central knife edge 74. The recesses 152 are defined by edges 160 that are cut into the rear surface 156. Thus, whereas the prior art knife edge 128 was a single straight edge, the knife edge of the present invention is a compound edge, including more than one straight section, such as the outer sections 78 and the central section 74. Two blade engagement bores 168 are formed through the blade 70, such that the blade 70 can be engaged with the prior art pipe end facing tool 36 in the same location and orientation as the prior art blade 48 depicted in Figs. 2 and 11. For further comprehension, Fig. 15 is an end elevational view depicting the blade 70 as used to face the end surface 64 of a section of pipe. As depicted therein, the blade 70 is positioned with its beveled surface 140 outward, with the rear surface 156 disposed against the pipe end surface 64. With the pipe end held stationary, the facing blade 70 is rotated in direction 180 to make cutting contact with the pipe end surface 64. As is best seen in Fig. 13, the edge 160 is preferably curved, with a radius of curvature that is approximately equal to the radius R of the cut step 90, in order to best facilitate the end facing procedure of the present invention. It can now be understood that the location and depth of the recessed areas 152 that are cut into the rear surface 156 of the blade 70 are a determining factor in producing the depth D of the step 90 of the present invention that is cut into the end face 64 of the pipe end 20. The radial dimension R of the step 90 is determined primarily by the setting of the blade 70 within the pipe end facing tool 36.

It is therefore to be understood that the present invention generally involves the removal of material from the interior edge of the pipe sidewall during the pipe end facing step, and that the compound shape of the pipe end facing blade can be altered to achieve that pipe material removal. The stepped blade edge of the blade 70 is therefore suitable to remove pipe material to create the pipe end face step 90 as depicted in Figs. 5 and 6.

While the present invention has been shown and described with regard to certain preferred embodiments, it will be understood that those skilled in the art may develop certain alterations and modifications thereto that nevertheless include the true spirit and scope of the invention described herein. It is therefore intended that the following claims cover all such alterations and modifications in form and detail that nevertheless include the true spirit and scope of the invention.

What is claimed is:

Claims

1. A heat fusion pipe j oint, compromising: a first pipe end having an interior surface, an exterior surface and a pipe end surface; a second pipe end having an interior surface, an exterior surface and a pipe end surface; a heat fusion joint including integrally heat bonded portions of said first pipe end surface and said second pipe end surface; said heat fusion joint including a smooth joint surface formed throughout said interior surfaces of said first pipe end and said second pipe end.

2. A heat fusion pipe joint as described in claim 1, wherein said heat fusion joint further includes an outwardly projecting heat fusion bead formed on said exterior surfaces of said first and second pipe ends.

3. A pipe end for heat fusion joints, compromising: a pipe end, including a cylindrical wall having a longitudinal pipe axis thereof, and having an interior wall surface and an exterior wall surface and an end wall surface; said pipe end surface and said exterior surface fonriing an outer pipe end edge, and wherein said pipe end surface and said interior surface form an inner pipe end edge; and wherein said inner pipe end edge is disposed longitudinally inwardly relative to the location of said outer pipe end edge.

4. A pipe end as described in claim 3 wherein said pipe end surface includes a radially symmetrical, longitudinally inwardly projecting beveled surface.

5. A pipe end as described in claim 4, wherein said pipe end surface includes a radially symmetrical, longitudinally inwardly projecting stepped surface.

6. A pipe end for heat fusion pipe joints, compromising: a pipe end including a cylindrical wall having a pipe longitudinal axis thereof, and having an interior wall surface, and exterior wall surface, and a pipe end surface; said pipe end surface having a cylindrical bore formed therein, said bore having a bore longitudinal axis that is coaxial with said pipe longitudinal axis, whereby a step is formed in said pipe end surface.

7. A pipe end as described in claim 6, wherein said step is formed with a depth D into said pipe end surface and parallel to said pipe longitudinal axis, and wherein said cylindrical wall is formed with a thickness T, and said step is further formed with a radially projecting surface that projects a distance R into said thickness of said wall.

8. A pipe end as described in claim 7 wherein D is from 0.025 to 0.05 inches, and wherein R is from 0.05 to 0.175 inches.

9. A pipe end as described in claim 8 wherein D is approximately 0.04 inches and R is approximately 0.15 inches.

10. A pipe joint heat fusion device, comprising: a first engagement mechanism for a first pipe end; a second engagement mechanism for a second pipe end; a pipe end facing device adapted for removable insertion between said first engagement mechanism and said second engagement mechanism; said pipe end facing device including at least one pipe end facing blade having an edge portion thereof for the removal of pipe material from said first and second pipe ends; said edge portion of said blade having a compound shape that is adopted to remove said pipe material in a corresponding compound surface shape.

11. A pipe j oint heat fusion device as described in claim 10 wherein said compound shape of said edge portion is a stepped shape.

12. A pipe joint heat fusion device as described in claim 10 wherein said compound shape of said edge portion is a beveled shape.

13. A pipe end facing blade adapted for use in a pipe end facing tool of a pipe joint heat fusion device, comprising: a generally rectangular body portion, including a front surface, a rear surface, two side surfaces and two end surfaces; one of said end surfaces being beveled from said front surface to said rear surface, such that said beveled surface and said rear surface form a cutting edge; said cutting edge having a compound shape.

14. A pipe end facing blade as described in claim 13 wherein said compound shape of said cutting edge includes at least one stepped portion.

15. A pipe end facing blade as described in claim 13 wherein said rear surface includes at least one notch formed therein, such that said cutting edge is formed with at least one stepped portion.

16. A pipe end facing blade as described in claim 13 wherein said blade is formed with two said stepped portions, such that said blade is reversible within a pipe end facing device to present a new cutting edge upon such reversing.

17. A method for forming a heat fusion pipe joint, comprising the steps of: engaging an end of a first pipe in a pipe joint heat fusion device; engaging an end of a second pipe in said pipe joint heat fusion device; facing said ends of said first pipe and said second pipe by removing pipe material from inner end edge portions of each said pipe end; heating said end surface portions of said pipe ends; and contacting said end surfaces of said pipe ends together to form a heat fusion joint.

18. A method for forming a heat fusion pipe joint, as described in claim 17, wherein said step of removing pipe material creates a step in an end surface of each said pipe end.

19. A method for forming a heat fusion pipe joint, as described in claim 18, wherein said step is formed with a depth D into said pipe end surface and parallel to a pipe longitudinal axis, said step further including a radially projecting surface that projects a distance R into a thickness of said pipe end.

20. A method for forming a heat fusion pipe joint, as described in claim 19, wherein D is from 0.025 to 0.05 inches, and wherein R is from 0.05 to 0.175 inches.

21. A method for forming a heat fusion pipe joint, as described in claim 19, wherein D is approximately 0.04 inches and R is approximately 0.15 inches.