Wiremesh reinforcement-plastic composite pipe component and method for making the same

A pipe has a wiremesh reinforcement-plastic composite construction that includes a first and second spiral reinforcing wire layer. The first spiral reinforcing layer has grooves formed at selected intervals, and the second spiral reinforcing wire layer is pressed into the grooves. The first and second spiral reinforcing wire layers are deformed and joined together by pressure to form a wiremesh reinforcement. The two spiral reinforcing wire layers have a left and right spiral angle .alpha.1 and .alpha.2 respectively relative to the central line, the left and right spiral angles .alpha.1 and .alpha.2 can change in the range of 0.degree. to 90.degree.. Thermoplastic penetrates the wiremesh reinforcement and fills both sides of the wiremesh reinforcement to form the composite pipe or component.

FIELD OF THE INVENTION
 This invention relates generally to a steel-plastic composite pipe
 component, and specifically to a wire-mesh reinforcement-plastic composite
 pipe component and method for making the same.
 BACKGROUND OF THE INVENTION
 Plastic pipes have been widely used in many fields due to good corrosion
 resistance, light weight and convenience of installation. However,
 applications in the industrial field are limited because of lower
 mechanical strength, lower rigidity and decreased heat-resistance over
 standard metal pipes. There are numerous configurations of pipe and
 methods of manufacturing same found in the prior art that have been
 designed to provide increased mechanical strength, increased rigidity, and
 greater heat-resistance over plastic pipes.
 One example is described in U.S. Pat. No. 3,242,691 to Robinson et al.,
 which describes a method of producing a pipe that includes a flexible
 shaft assembly including a flexible rotatable metal core, an inner plastic
 tubing sized to receive the metal core, a plurality of metallic wires
 helically wound in one direction, and a second plurality of metallic wires
 helically wound in the opposite direction.
 Another example is described in U.S. Pat. No. 3,460,578 to Schmid, which
 describes a composite flexible shaft casing including an inner plastic
 liner, a wire braid having wires helically wound to form interstices
 between the wires, an outer covering extruded over the wire braid and
 passing through the interstices to engage the liner, and a plurality of
 axially extending ribs or projections.
 U.S. Pat. No. 3,526,692 to Onaka describes a mechanism for continuously
 coiling wire into a helix and feeding the helix axially through a plastic
 extruding die where a plastic pipe body is extruded so that the wire helix
 is embedded in but projects from the outer surface of the pipe body. The
 pipe body is then passed through a second plastic extruding die in which a
 tubular plastic layer is bonded to the outer surface of the pipe body.
 U.S. Pat. No. 4,258,755 to Higbee describes a flexible reinforced cured
 resin hose including a combination of helically wound cable wires and body
 wires embedded therein. Two plies of wires are wrapped in opposite
 directions around the periphery of a liner tube supported on a mandrel,
 the plies being supported in a resin filler layer applied over the liner
 to hold the wires spaced apart.
 Yet another example is found in U.S. Pat. No. 4,657,049 to Fourty et al.,
 which describes a reinforced composite tubular body including a metallic
 reinforcement of helical convolutions completely embedded in a tubular
 body of thermosetting polymer which has a coefficient of elongation at
 rupture less than 15%.
 Another example of a steel skeleton-plastic composite pipe is described in
 China Patent 94104509. The pipe described in China Patent 94104509 has
 distinct advantages over plastic pipes and over other steel-plastic
 composite pipes known to those skilled in the art, including increased
 mechanical strength, increased rigidity, and a greater heat resistance.
 The steel skeleton according to that patent is constructed by both
 longitudinal and traverse reinforcing wires, and the amount of both
 longitudinal reinforcing wires and traverse reinforcing wires in the steel
 skeleton are 50% respectively. To increase the strength of the pipe, the
 diameter of the transverse reinforcing wire is increased. This results in
 increasing the wall thickness of the composite pipe.
 The devices and methods described in the prior art achieve a certain degree
 of success in increasing mechanical strength, increasing rigidity, and
 providing greater heat tolerance in pipe. However, it would be desirable
 to increase the mechanical strength of a component pipe without
 significantly increasing the wall thickness. It would also be desirable to
 provide a method of manufacture of not only composite straight pipe, but
 also composite pipe components, wherein the method of manufacture offers
 significant savings in the cost of manufacture.
 SUMMARY OF THE INVENTION
 It is therefore one object of the invention to provide a composite pipe and
 components having improved pressure resistance.
 It is another object of the invention to provide a composite pipe and
 components that have improved mechanical strength while maintaining a
 smaller wall thickness.
 Another object of the invention is to provide a composite pipe that has a
 low hydraulic loss.
 Yet another object of the invention is to provide a highly efficient and
 low cost method for making a composite pipe.
 These and other objects are attained by a wiremesh reinforcement-plastic
 composite pipe and components. The pipe has a wiremesh
 reinforcement-plastic composite construction that includes a first and
 second spiral reinforcing wire layer. The first spiral reinforcing layer
 has grooves formed at selected intervals, and the second spiral
 reinforcing wire layer is pressed into the grooves. The first and second
 spiral reinforcing wire layers are deformed and joined together by
 pressure to form a wiremesh reinforcement. The two spiral reinforcing wire
 layers have a left and right spiral angle .alpha.1 and .alpha.2
 respectively relative to the central line, the left and right spiral
 angles .alpha.1 and .alpha.2 can change in the range of 0.degree. to
 90.degree.. Thermoplastic penetrates the wiremesh reinforcement and fills
 both sides of the wiremesh reinforcement to form the composite pipe or
 component.

DETAILED DESCRIPTION OF THE INVENTION
 Referring now to FIGS. 1 and 2, the method of manufacturing the wiremesh
 reinforcement-plastic composite pipe of the invention are depicted, and
 the composite pipe is depicted in FIG. 5. The method of manufacture
 includes a device which comprises a wiremesh reinforcement braiding
 machine 22 including a main shaft 7. A thermoplastic extruder 12 is
 provided and is located to the rear of the braiding machine 22. A pipe
 forming chamber 16 and a puller 15 are provided downstream of the extruder
 12. A plurality of threaded rods 8 are mounted on the main shaft 7. A
 first spiral reinforcing wire 2 is pulled from a first winding roll 1 and
 wound onto a disk follower 4, which includes one or preferably a plurality
 of first winding rollers 3. The first winding rollers 3 are arranged
 outside the main shaft 7 for winding the first spiral reinforcing wire
 layer 2 onto the main shaft 7. A cut roller 10 is used to cut a plurality
 of spaced grooves as shown in FIG. 1a in the transversal section of the
 first spiral reinforcing wire layer 2a. The grooves are placed at
 intervals, the intervals are determined by the specific materials that are
 used for the wire.
 During the winding of the wire 2 onto the main shaft 7, the rotation rate
 of the winding roller 3 is n3, the rotation rate of the main shaft 7 is
 n1, and the relationship between the rates of rotations is n3&gt;n1. When the
 first winding roller 3 rotates in the same rotation direction as that of
 the main shaft 7, the first reinforcing wire 2 is wound onto the threaded
 rods 8 of main shaft 7 with a right spiral angle .alpha.1, to form the
 first spiral reinforcing wire layer 2a, shown in FIG. 5. When the main
 shaft 7 rotates, the threaded rods 8 rotate in a manner of planetary
 motion around the axial of main shaft 7. When the first reinforcing wire
 layer 2a which is wound on the main shaft 7 the wire 2 passes over the cut
 roller 10, the cut roller 10 forms grooves (not shown) in the transverse
 section of the first spiral reinforcing wire layer 2a.
 A second reinforcing wire 5 is pulled from a second winding roll 6 and
 wound onto one or a plurality of second winding rollers 11. Following the
 rotation of the main shaft 7, the second reinforcing wire layer 5 is wound
 onto the first spiral reinforcing wire layer 2 with a spiral angle
 .alpha.2 in opposite direction to the angle .alpha.1 of the first spiral
 reinforcing wire layer 2a. This forms the second spiral reinforcing wire
 layer 5a, which is pressed by a second winding roller 11 into the grooves
 formed on the first spiral reinforcing layer.
 At this point, both of the spiral reinforcing wire layers are deformed
 under pressure and are joined together in the grooves to form a wiremesh
 reinforcement 23. It should be noted, if the mechanical connection between
 the two layers is difficult due to special characteristics of the
 materials used in the wire, a welding roller may be used instead of the
 second winding roller 11 and the cut roller 10 will be omitted. The
 wiremesh reinforcement 23 is continuously moved into a pipe forming
 chamber 16 by the threaded rod 8. At the same time, the melted
 thermoplastic 25 is extruded into the pipe forming chamber 16 by an
 extruder 12. The melted thermoplastic 25 penetrates the wiremesh
 reinforcement 23 and fills both sides of the wiremesh reinforcement 23 to
 form a composite straight pipe 24. Then the composite straight pipe is
 cooled by an inner cool case 9 and an outside cool case 13.
 Although in the preferred embodiment the wire is formed of steel, one
 skilled in the art would recognize that there are numerous materials with
 various material characteristics that can be used. Likewise, one skilled
 in the art would recognize that there are various thermoplastics that can
 be utilized for specific material characteristics related to the end use
 of the pipe.
 When the spiral reinforcing wire layers are wound, the first winding roller
 3, the threaded rods 8 and the main shaft 7 rotate in the same direction,
 and the second winding roller 11 and cut roller 10 are static.
 Alternatively, when the spiral reinforcing wire layers are wound, the main
 shaft 7 is static, the first winding roller 3, second winding roller 11
 and cut roller 10 rotate around the axial of main shaft, and the second
 winding roller 11 and the cut roller 10 rotate in the same direction, but
 the first winding roller 3 rotates in the direction opposite to that of
 roller 11 and cut roller 10, thus a wiremesh reinforcement is formed. The
 spiral angles .alpha.1 and .alpha.2 can vary in the range of 0.degree. or
 90.degree.. The spiral angles .alpha.1 and .alpha.2 may or may not be
 equal; the choice being dependent upon the different pressure requirements
 of the pipe and the different plastic materials used in the construction
 of the pipe.
 For the connection of composite pipe components, the invention provides two
 kinds of joints, both of them having a wiremesh reinforcement-plastic
 composite construction as described above. Referring now to FIG. 3, there
 is shown an electrofusion coupler 17 which has an electrothermal wire 19
 in its inner layer, the electrothermal wire 19 connected with an electric
 wire outside the joint by an electrical connector 18. When composite
 straight pipe is inserted into the electrofusion coupler, an electric
 circuit is set up, and the connection of the electrofusion coupler is
 achieved.
 Referring now to FIG. 4, a flange coupler 28 is depicted. The ends of the
 composite straight pipe may be moulded into a cone 20 to form a means to
 connect the pipe to components or to other sections of pipe. The ends of
 the flange coupler are moulded into a cone 20, the cone 20 having a
 surface which cooperates with a respective surface of the composite
 straight pipe. There is a circular groove 21 on the surface of cone 20 of
 the flange coupler, a rubber seal ring (not shown) is placed into the
 groove 21. A pair of metal flanges engage with the cones 20 and press two
 cones 20 together with bolts, such that the surfaces are sealed.
 While the present invention has been particularly shown and described with
 reference to the preferred mode as illustrated in the drawing, it will be
 understood by one skilled in the art that various changes in detail may be
 effected therein without departing from the spirit and scope of the
 invention as defined by the claims.