Patent Application
20170211727
1. Field of the Invention
The present invention relates to a water pipe fitting, and more particularly to a pipe connecting structure.
2. Description of the Prior Art
PERT pipes are non-crosslinked polyethylene pipes used in hot water piping systems, which are also medial density polyethylene pipes and have the features of high temperature resistance, good flexibility, pressure resistance, non-toxic, odorless, non-pollution, low temperature resistance, and so on. PERT is suitable for a water pipe assembly material. Nowadays, the water pipe assembly is made of PERT instead of a copper material, so that the material cost and the manufacturing cost of the parts are lowered greatly. Because the water pipe assembly made of a copper material may harm to health, the water pipe assembly made of PERT has been widely used on the market.
In general, the connecting structure of pipes includes a metallic connector or a metal fitting to wrap the joint of a plastic tube and a plastic connector. This structure provides a better sealing function in the beginning, but it may have a leak at the joint after a period of time due to the hard metal. Besides, its burst resistance and pressure resistance are not perfect.
Therefore, an improved connecting structure is developed on the market. The connecting structure includes a PERT plastic pipe and a PERT plastic connector which are connected by laser welding. This connecting structure provides a better sealing and connecting function, but the PERT plastic connector is soft. The joint is not strong enough, so it is not durable for use. Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.
The primary object of the present invention is to provide a pipe connecting structure which is cost-effective, durable and safe.
In order to achieve the aforesaid object, the pipe connecting structure of the present invention comprises a tube made of PERT (polyethylene of raised temperature resistance) or PEX (crosslinked polyethylene) having a light-absorption color and a tubular connector made of PP (polypro pylene), PE (poly ethylene), POM (polyformaldehyde) or PA (polyamide) having a light-pervious color; or comprises a tube made of PERT (polyethylene of raised temperature resistance) or PEX (crosslinked polyethylene) having a light-pervious color and a tubular connector made of PP (polypro pylene), PE (poly ethylene), POM (polyformaldehyde) or PA (polyamide) having a light-absorption color. One end of the tube and one end of the tubular connector are mated with each other to be welded together.
Preferably, the end of the tubular connector is formed with a two-grade stepped hole corresponding to an outer diameter of the end of the tube. The two-grade stepped hole includes a small hole and a big hole which are arranged from inside to outside in an axial direction of the tubular connector. The end of the tube is fitted in the big hole of the two-grade stepped hole. The tubular connector is made of a light-pervious material. The tube is made of a light-absorption material.
Preferably, the end of the tube is coupled to the big hole by an interference fit.
Alternatively, the end of the tube is formed with a two-grade stepped hole corresponding to an outer diameter of the tubular connector. The two-grade stepped hole includes a small hole and a big hole which are arranged from inside to outside in an axial direction of the tube. The end of the tubular connector is fitted in the big hole of the two-grade stepped hole. The tube is made of a light-pervious material. The tubular connector is made of a light-absorption material.
Preferably, the end of the tubular connector is coupled to the big hole by an interference fit.
Preferably, the interference fit has a unilateral tolerance in the range of 0-0.10 mm.
Preferably, the unilateral tolerance is in the range of 0-0.08 mm.
Preferably, the PP or PE contains 15-20% glass fibers.
Preferably, the end of the tube and the end of the tubular connector are welded together by laser welding with parameters comprising a power in the range of 13-28 W and a rotational speed in the range of 45-50 rpm.
Preferably, the power is 18 W and the rotational speed is 45 rpm.
Accordingly, the tubular connector made of PP, PE, POM or PA and the tube made of PERT of the present invention are mated with each other, and they can be preferably welded together. PP, PE, POM or PA is harder than PERT and can be welded with PERT better. After they are welded together, the strength is up to 500 psi when making a burst pressure test. The tensile strength and modulus of the PERT is in the range of one third to a half of the tensile strength and modulus of the PP or PE. After laser welding, the strength of the connecting structure of the same structure is two-three times as much as the original PERT tubular connector.
Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings.
As shown in
In a preferred embodiment, one end of the tubular connector 1 is formed with a two-grade stepped hole 10. The two-grade stepped hole 10 includes a small hole 101 and a big hole 102 which are arranged from inside to outside in an axial direction of the tubular connector 1. One end of the tube 2 is fitted in the big hole 102 of the two-grade stepped hole 10. The end of the tube 2 is coupled to the big hole 102 by an interference fit with a unilateral tolerance in the range of 0-0.10 mm. Preferably, the unilateral tolerance is in the range of 0-0.08 mm. The joint of the tube 2 and the tubular connector 1 has a certain prepressing force, which greatly strengthens mutual heat contact during laser welding.
Preferably, the tubular connector 1 is made of PP or PE. In a preferred embodiment, the PP or PE contains 15-20% glass fibers. Preferably, the tube 2 is made of PERT. The tensile strength and modulus of the PERT is in the range of one third to a half of the tensile strength and modulus of the PP or PE. After laser welding, the strength of the connecting structure of the same structure is two-three times as much as the original PERT tubular connector.
Referring to
Thereby, the tubular connector 1 made of PP, PE, POM or PA and the tube 2 made of PERT of the present invention are mated with each other, and they can be preferably welded together. PP, PE, POM or PA is harder than PERT and can be welded with PERT better. After they are welded together, the strength is up to 500 psi when making a burst pressure test. The tensile strength and modulus of the PERT is in the range of one third to a half of the tensile strength and modulus of the PP or PE. After laser welding, the strength of the connecting structure of the same structure is two-three times as much as the original PERT tubular connector.
Although particular embodiments of the present invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the present invention. Accordingly, the present invention is not to be limited except as by the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 201610050962.7 | Jan 2016 | CN | national |
