CA2073402C - Rigid/flexible tube - Google Patents
Rigid/flexible tubeInfo
- Publication number
- CA2073402C CA2073402C CA 2073402 CA2073402A CA2073402C CA 2073402 C CA2073402 C CA 2073402C CA 2073402 CA2073402 CA 2073402 CA 2073402 A CA2073402 A CA 2073402A CA 2073402 C CA2073402 C CA 2073402C
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- CA
- Canada
- Prior art keywords
- web
- tube
- relatively
- forming rollers
- speed
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Shaping Of Tube Ends By Bending Or Straightening (AREA)
- Extrusion Moulding Of Plastics Or The Like (AREA)
Abstract
A tube is disclosed having alternating relatively rigid and relatively flexible segments formed along its length. The tube wall is formed of overlapping wrappings of a continuous web of thermoplastic material. The thickness of the web is varied to form the rigid and flexible segments. A reinforcing strand of metal or plastic wire is helically coiled along with the web. A method and apparatus are disclosed in which the web is taken up around helically skewed forming rollers. The speed of rotation of the forming rollers or the rate of extrusion of the web is varied to produce the rigid and flexible segments. The reinforcing strand may be a thermoplastic wire formed by extrusion simultaneously with the formation of the tube.
Description
RIGID/FLEXIBLE TUBE
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a tube suitable for use as an air duct, conduit or the like and, more particularly, to a tube having relatively rigid and relatively flexible segments along its length and to a method and apparatus for producing such a tube.
Description of the Related Art Tubing of thermoplastic wall material is used in a wide variety of applications. For e~ample, in automobiles, such tubing may be used as ventilation or air intake ducting, as radiator hose, as wave tubes for cancelling engine noise, or as conduit for the routing and protection of electric wires. When used in such applications, the tubing must usually be routed with one or more bends. In order to accommodate the bending, the wall of the tubing must be sufficiently thin and flexible.
It is known in the prior art to provide tubing formed as a helically wrapped coil of an extruded strip of polymeric material. It is also known to include in such a tube a helically coiled reinforcing strand, such as a semi-rigid wire, situated between the wrapped layers of the polymeric strip. For example, United States Patent 4,486,260, issued December 4, 1984, and entitled "Fabricating Machine and Process", discloses an apparatus in which a flexible thermoplastic strip is helically wound on a mandrel of rollers with a wire introduced between the wrappings of the strip. The strip is uniformly thin and flexible so that the tube formed thereof is readily flexed; however, the reinforcing wire maintains the circular cross-sectional shape of the tube.
As a further example of the prior art, British Patent Specification 1,451,~69, published October 6, 1976, and entitled "Improvements Relating to Flexible Tubing", similarly discloses ~ ~ ~,~,?
the manufacture of a tube from a uniformly thin, helically coiled strip of extruded plastic material with a reinforcing wire situated between the coiled layers of the strip.
Even though the installed tubing must usually make one or more bends when installed, there are frequently installations where portions of the tubing may be routed in a substantially straight line. Along such straight runs, it is desirable to have the tubing wall thicker and more rigi~ to provide a greater degree of durability for the tubing and to facilitate its handling and installation.
When tubing is used in mass-produced articles such as automobiles, it is desirable to have a means for manufacturing large quantities of tubing. Optimally, the tubing would be provided in predetermined lengths bendable at least at the necessary predetermined locations and would provide a maximum degree of strength and durability. Furthermore, each bendable location of the tube would be formed so as to allow bending to a predetermined angle. However, the prior art has provided only for the manufacture of helically wrapped tubing having a uniform wall thickness and degree of flexibility throughout the entire length of the tube. Therefore, tubing of the past has necessarily been entirely relatively thin-walled in order to accommodate the bending required.
Therefore, there is an unmet need for an economically produced tubing which is flexible enough to be bent where necessary, rigid and durable enough to maintain its shape, and manufactured to conform to the geometry required for particular applications.
SUMMARY OF ~HE lNv~NllON
The present invention satisfies the aforementioned need by providing a tubing formed of a helically coiled strip in which ~? ~
the thickness of the strip is varied to provide relatively thin-walled and flexible segments and relatively thick-walled and rigid segments at predetermined locations along the length of the tubing.
According to the principles of the invention, a continuous web or strip of thermoplastic material is formed by extrusion from a die near a rolling apparatus. The rolling apparatus has a mandrel of a plurality of elongated forming rollers having their longitudinal axes helically skewed and spaced around a common axis, e~ually distant from the common axis, thereby defining a cylindrical envelope. The rollers all co-rotate in a common direction and speed. The advancing web, while still heated from the extrusion process, is taken up by the rollers such that the web i9 helically wrapped around the rollers. A reinforcing strand, such as a metal wire or a ~reformed plastic wire is introduced and also helically taken up by the rollers. The wrappings of the web overlap, thereby forming a helical lamination of layers of the web. The wrappings thus continuously form a cylindrical tube, the wall of the tube made up of the laminations of the web and reinforced by the helically wound strand.
As the tube is progressively formed, it advances on the rollers. A pressure roller may be provided along the exterior of the newly formed tube to exert compression on the laminations and cause them to fuse or adhere together.
According to the preferred embodiment of the invention in which a wire or preformed plastic reinforcing strand is used, a programmable logic controller is provided to con~rol the speed of the forming rollers. When a relatively thick-walled and rigid segment of the tubing is being formed, the controller causes the forming rollers to rotate at a relatively slower speed. When a ~ ? ~
relatively thin-walled and flexlble segment of the tubing is being formed, the controller causes the forming rollers to rotate at a relatively higher speed. The higher speed of the forming rollers causes the web to be drawn out to a lesser thickness.
When a relatively thick-walled and rigid segment of tubing is again desired, the controller slows the forming rollers to the relatively lower speed. By appropriate programming of the controller, a tube is produced which is relatively thick-walled and rigid over parts of its length, but which is relatively-thin walled, flexible, and easily bent at predetermined segments according to the geometry of the intended end use.
According to an alternate embodiment of the invention, the reinforcing strand may be of a thermoplastic material and formed by extrusion substantially simultaneously with the formation of the tube. With this arrangement, the speed of rotation of the forming rollers and the rate of extrusion of the strand are kept constant, while the programmable logic controller varies the rate of extrusion of the web to form the rigid and flexible segments of the tube.
According to a feature of the invention, the length of the flexible segments of the tube is controlled such that the tube may be bent at predetermined angles. For example, where a 90 degree bend is desired, a flexible segment is formed having a length of approximately twice the length required for a 45 degree bend. This construction facilitates installation of the tube and m;nlml zes the amount of relatively weaker areas of the tube.
These and other objects, advantages, and features of the present invention will be more fully understood and appreciated by reference to the written specification and appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 ~ 9 a perspective view of a rigid/flexible tube according to the invention' Fig. 2 is a fragmentary perspective view of a length of tube according to the invention;
Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2;
Fig. 4 is a top plan view of an apparatus for producing a rigid/flexible tube according to the invention;
Fig. 5 is an end elevational view taken along the line 5-5 of Fig. 4;
Fig. 6 is an end elevational view taken along the line 6-6 of Fig. 4;
Fig. 7 is a sectional view taken substantially along the line 7-7 of Fig. 4, illustrating the alternate use of either an extruded reinforcing wire or a metal reinforcing wire;
Fig. 8 is similar to Fig. 3, but shows an alternate construction of the rigid/flexible tube; and Fig. 9 is similar to Fig. 3, but shows a second alternate construction of the rigid/flexible tube.
DESCRIPTION OF THE PREFERRED EMBODIMENT
By way of disclosing a preferred embodiment of the invention, and not by way of limitation, there is shown in Fig. 1 a rigid/flexible tube 10. The tube includes three relatively thick-walled, straight, and rigid segments 12, 14 and 16, and two relatively thin-walled and flexible segments 18 and 20 disposed between the rigid segments. Flexible segment 18 is bent at approximately 45 degrees, while flexible segment 20 is bent at approximately 90 degrees. The tube is manufactured to a predetermined length, and the rigid and flexible segments are provided at predetermined locations and lengths alternating along the length of the tube according to the intended end use of the tube. The tube i9 shown bent to illustrate the rGuting of the tubing when it is installed. The tube illustrated is but one example of the many possible configurations within the scope of the invention.
Figs. 2 and 3 show greater detail of the tubing of the invention. The tube has a substantially circular transverse cross section and has a helical ridge 22 formed by the helically wrapped continuous web 23 overlying a reinforcing ~trand 24. The length of tube shown includes two, longitudinally spaced-apart, relatively thick-walled and rigid segments 26 and 28, and a relatively thin-walled an~ flexible segment 30 disposed intermediate the two rigid segments.
As best shown in Fig. 3, in which the thickness of the web 23 is exaggerated for clarity of illustration, the relatively rigid segments of the tube 26, 28 have walls made up of wrappings of the continuous web 23 in which the web is relatively thick as at wrappings 31-34. The relatively flexible section 30 has a wall made of wrappings of the web in which the web is relati~ely thin as at wrappings 35 and 36. The reinforcing strand 24 is a preformed metal or plastic wire. Alternatively the reinforcing strand may be a plastic-coated metal wire or a plastic wire formed by extrusion simultaneously with the formation of the tube, as more fully described below.
Figs. 4 through 7 illustrate the apparatus and method for producing the rigidtflexible tube 10 according to the invention. In its general organization, the apparatus includes a web extruder die 38 positioned near a rolling apparatus 40. The extruder includes, in a well known manner (not shown in the figures), a hopper of pelletized thermoplastic material, a heater for melting the material, and a screw for forcing the molten or softened material through a die. The die 38 is configured to extrude the material into a ribbon-like continuous web 23.
The drive means 42 includes in its general organization a variable speed electric motor 102 with a motor drive gear 103, a drive chain 104, a linking chain 106, a support frame 108, five flexible drive shafts, three of which designated at llOa-llOc in Fig. 4 (two others being hidden from view) support plates 112 and 114, five outer drive gears 116a-116e, and five inner drive gears, three of which are designated at 118a-118c (two others being hidden from view). The inner and outer drive gears are fixedly mounted on five drive shafts 120a-120e which, in turn, are fixed to the flexible drive shafts llOa-llOc etc. The number of drive shafts, rollers, etc., may vary according to the diameter of the tube to be formed. Preferably, at least four are used.
Electric motor 102 rotates motor drive gear 103 which, in turn, drives drive chain 104. As best shown in Fig. 5, drive chain 104 engages outer drive gears 116a, 116b, 116d, and 116e, thus rotating the corresponding drive shafts 120a, 120b, 120d, and 120e. The rotation of these drive shafts also rotates the commonly mounted inner drive gears 118a etc. All five of the inner drive gears 118a etc. are linked by linking chain 106, thus causing all five drive shafts 120a etc. to rotate in a common direction and speed.
The drive shafts 120a etc. in turn cause the flexible drive shafts llOa etc. to commonly rotate. The flexibility of the drive shafts llOa etc. transfers the rotational motion from the larger circumference encompassing the gears 118a etc. to the smaller circumference encompassing the forming rollers 44a etc.
and accommodates the skewing of the forming rollers.
A pipe 130 extends from t~le rear of the apparatus ~hrough the drive means and to the forward end of the forming rollers 44a etc. At the forward end of the pipe, an end plate 132 is fixed to the end of the pipe. The end plate carries five pin bearings such as bearing 134 disposed equally spaced about a circle. The forming rollers 44a etc. each extend from a pin bearing rearwardly to the support plate 112 where they are journalled for rotation and driven by the flexible drive shafts llOa etc.
The longitudinal axes of the forming rollers are not parallel to the longitudinal axis of the apparatus 40 but are instead slightly helically skewed. As best shown in Fig. 6, the ends of the forming rollers 44a etc., supported on the pin bearings 134 of end plate 132, are offset slightly counterclockwise with respect with the opposite ends of the forming rollers journalled on plate 112 as indicated by arrow 13a. A clamp with tightening screws 140 is provided to allow for adjustment of the amount of helical skewing of the forming rollers.
As best shown in Fig. 4 and 7, the freshly extruded web 23, preferably made of a thermoplastic elastomer material, such as a blend of EDPM rubber and polypropylene, emerges from the die 38 near the rolling apparatus 40 in a direction tangent to the cylindrical envelope of the forming rollers 44a-44e. The rotation of the forming rollers takes up the web as it advances, thereby wrapping the web into a cylindrical, continuous tube 10.
A reel 71 of plastic or metal reinforcing wire 24 is rotatably supported below the web extruder die. '~he wire is taken up by the forming rollers and helically wrapped therearound lying between overlapping wrappings of the web.
S~ L ~ J ~
A pressure roller 48 is provided situated externally of the newly formed tube. The wall material of the tubing is still hot from the extrusion process when it reaches the pressure roller. The pressure roller 48 presses the tube against the 5 forming roller 44c to enhance the bonding of the wrappings of the web and to aid in maintaining tension in the web 23. The pressure roller 48 is formed with a circumferential groove 73 to accommodate the ridge formed by the reinforcing strand. The forming rollers are similarly formed with grooves 74 to accommodate a corresponding ridge on the inside of the tube.
Optionally, the pressure roller 48 may be omitted if the characteristics of the web material are such that the wrappings spontaneously bond together without the application of additional pressure.
As the tube 10 is formed it is cooled by a jet of air 59 from the nearby nozzle 58. The forward end of the pipe 130 is formed with perforations 160 through which cooling air 161 is also blown. An ample flow of cooling air is necessary to harden the tube as soon as possible after its formation.
As the tube is being formed, the rate of rotation of the forming rollers 44a-44e is controlled by programmable logic controller 80. Controller 80 is electrically connected by suitable wiring 81 to the variable speed electric motor 102.
When a relatively thick-walled and rigid segment of tube is being formed, the controller causes the motor to operate at a relatively slower speed. The forming rollers thereby rotate at a correspondingly slower speed causing the tubing wall to be formed of relatively thicker wrappings of the web 23 such as shown with wrappings 31-34 of Fig. 3. The controller 80 is fed signals from which the rate of speed of the forming apparatus by wiring 83 connected to a suitable pick up on shaft 120a. Alternatively, 2r~t?.~,~
wiring 82 is connected to a suitable pick up for detecting the rotation of reel 71.
When a relatively thin-walled and flexible segment of the tube is being formed, the controller causes the motor to operate at a relatively faster speed. The forming rollers thereby rotate at a correspondingly higher speed. The higher speed causes the web to be drawn out to a lesser thickness. The helical wrappings of the drawn out web, such as wrappings 35 and 36 of Fig. 3, form the flexible segments of the tube.
The reinforcing strand may be a thermoplastic wire formed by extrusion substantially simultaneously with the formation of the web. As shown in Fig. 7, a wire extruder 72 is used instead of the reel 71 to form wire 24'. The freshly extruded plastic wire 24' is taken up on the forming rollers in the same manner as metal wire 24. With this embodiment, varying the speed of rotation of the forming rollers is undesirable since it would be difficult to control the diameter of the freshly extruded plastic wire 24'. Instead, the programmable logic controller 80 is connected to the web extruder 28 by wire 85, and the rate of extrusion of the web 23 is varied. When a relatively thin and flexible segment of the tube is being formed, the extrusion of the web 23 is slowed, while the rotation speed of the forming rollers and the extrusion rate of the wire extruder 72 is kept substantially constant. For a rigid tube segment, the web extruder is speeded up while the forming rollers and wire extruder again remain at constant speed and rate.
The controller is preferably preprogrammed to automatically vary the speed of the apparatus so as to form the rigid and flexible segments of the tube at the desired locations and at the desired lengths. Preferably, the lengths of the flexible segments correspond to the angle of the bends to be made when the tube is installed. As will be apparent to those familiar with the art, the length required for a given bend angle will depend on the tube diameter and the bend radius.
After the tube 10 has advanced off the forming rollers, it is cut to desired lengths at appropriate locations, thus forming a rigid/flexible tube such as shown in Fig. 1. The controller 80 recycles to produce large numbers of identical tubes, or is reprogrammed to produce a new tube configuration.
An alternate construction of the rigid/flexible tube according to the principles of the invention i9 shown in Fig. 8.
The reinforcing strand 24" comprises a metal wire core 141 having a plastic coating 142. Preferably, the coating 142 is of a material compatible with the web 23" such that the coating spontaneously bonds to the hot web upon contact.
Fig. 8 further shows an alternate wrapping configuration in which the width of the web 23' is approximately equal to twice the pitch P of the reinforcing strand 24". The reinforcing strand further is disposed under the wrapping and exposed to the interior of the tubing.
Fig. 9 shows a second alternate construction of the tube in which the width of the web 23" is somewhat greater than the pitch of the wire 145 but less than twice the pitch. Each winding of the wire is disposed between a single layer of the web. Numerous other configurations are possible within the scope of the invention.
The above description is that of a preferred embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as set forth in the appended claims, which are to be interpreted in accordance with the principles of patent law, including the Doctrine of Equivalents.
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a tube suitable for use as an air duct, conduit or the like and, more particularly, to a tube having relatively rigid and relatively flexible segments along its length and to a method and apparatus for producing such a tube.
Description of the Related Art Tubing of thermoplastic wall material is used in a wide variety of applications. For e~ample, in automobiles, such tubing may be used as ventilation or air intake ducting, as radiator hose, as wave tubes for cancelling engine noise, or as conduit for the routing and protection of electric wires. When used in such applications, the tubing must usually be routed with one or more bends. In order to accommodate the bending, the wall of the tubing must be sufficiently thin and flexible.
It is known in the prior art to provide tubing formed as a helically wrapped coil of an extruded strip of polymeric material. It is also known to include in such a tube a helically coiled reinforcing strand, such as a semi-rigid wire, situated between the wrapped layers of the polymeric strip. For example, United States Patent 4,486,260, issued December 4, 1984, and entitled "Fabricating Machine and Process", discloses an apparatus in which a flexible thermoplastic strip is helically wound on a mandrel of rollers with a wire introduced between the wrappings of the strip. The strip is uniformly thin and flexible so that the tube formed thereof is readily flexed; however, the reinforcing wire maintains the circular cross-sectional shape of the tube.
As a further example of the prior art, British Patent Specification 1,451,~69, published October 6, 1976, and entitled "Improvements Relating to Flexible Tubing", similarly discloses ~ ~ ~,~,?
the manufacture of a tube from a uniformly thin, helically coiled strip of extruded plastic material with a reinforcing wire situated between the coiled layers of the strip.
Even though the installed tubing must usually make one or more bends when installed, there are frequently installations where portions of the tubing may be routed in a substantially straight line. Along such straight runs, it is desirable to have the tubing wall thicker and more rigi~ to provide a greater degree of durability for the tubing and to facilitate its handling and installation.
When tubing is used in mass-produced articles such as automobiles, it is desirable to have a means for manufacturing large quantities of tubing. Optimally, the tubing would be provided in predetermined lengths bendable at least at the necessary predetermined locations and would provide a maximum degree of strength and durability. Furthermore, each bendable location of the tube would be formed so as to allow bending to a predetermined angle. However, the prior art has provided only for the manufacture of helically wrapped tubing having a uniform wall thickness and degree of flexibility throughout the entire length of the tube. Therefore, tubing of the past has necessarily been entirely relatively thin-walled in order to accommodate the bending required.
Therefore, there is an unmet need for an economically produced tubing which is flexible enough to be bent where necessary, rigid and durable enough to maintain its shape, and manufactured to conform to the geometry required for particular applications.
SUMMARY OF ~HE lNv~NllON
The present invention satisfies the aforementioned need by providing a tubing formed of a helically coiled strip in which ~? ~
the thickness of the strip is varied to provide relatively thin-walled and flexible segments and relatively thick-walled and rigid segments at predetermined locations along the length of the tubing.
According to the principles of the invention, a continuous web or strip of thermoplastic material is formed by extrusion from a die near a rolling apparatus. The rolling apparatus has a mandrel of a plurality of elongated forming rollers having their longitudinal axes helically skewed and spaced around a common axis, e~ually distant from the common axis, thereby defining a cylindrical envelope. The rollers all co-rotate in a common direction and speed. The advancing web, while still heated from the extrusion process, is taken up by the rollers such that the web i9 helically wrapped around the rollers. A reinforcing strand, such as a metal wire or a ~reformed plastic wire is introduced and also helically taken up by the rollers. The wrappings of the web overlap, thereby forming a helical lamination of layers of the web. The wrappings thus continuously form a cylindrical tube, the wall of the tube made up of the laminations of the web and reinforced by the helically wound strand.
As the tube is progressively formed, it advances on the rollers. A pressure roller may be provided along the exterior of the newly formed tube to exert compression on the laminations and cause them to fuse or adhere together.
According to the preferred embodiment of the invention in which a wire or preformed plastic reinforcing strand is used, a programmable logic controller is provided to con~rol the speed of the forming rollers. When a relatively thick-walled and rigid segment of the tubing is being formed, the controller causes the forming rollers to rotate at a relatively slower speed. When a ~ ? ~
relatively thin-walled and flexlble segment of the tubing is being formed, the controller causes the forming rollers to rotate at a relatively higher speed. The higher speed of the forming rollers causes the web to be drawn out to a lesser thickness.
When a relatively thick-walled and rigid segment of tubing is again desired, the controller slows the forming rollers to the relatively lower speed. By appropriate programming of the controller, a tube is produced which is relatively thick-walled and rigid over parts of its length, but which is relatively-thin walled, flexible, and easily bent at predetermined segments according to the geometry of the intended end use.
According to an alternate embodiment of the invention, the reinforcing strand may be of a thermoplastic material and formed by extrusion substantially simultaneously with the formation of the tube. With this arrangement, the speed of rotation of the forming rollers and the rate of extrusion of the strand are kept constant, while the programmable logic controller varies the rate of extrusion of the web to form the rigid and flexible segments of the tube.
According to a feature of the invention, the length of the flexible segments of the tube is controlled such that the tube may be bent at predetermined angles. For example, where a 90 degree bend is desired, a flexible segment is formed having a length of approximately twice the length required for a 45 degree bend. This construction facilitates installation of the tube and m;nlml zes the amount of relatively weaker areas of the tube.
These and other objects, advantages, and features of the present invention will be more fully understood and appreciated by reference to the written specification and appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 ~ 9 a perspective view of a rigid/flexible tube according to the invention' Fig. 2 is a fragmentary perspective view of a length of tube according to the invention;
Fig. 3 is a sectional view taken along the line 3-3 of Fig. 2;
Fig. 4 is a top plan view of an apparatus for producing a rigid/flexible tube according to the invention;
Fig. 5 is an end elevational view taken along the line 5-5 of Fig. 4;
Fig. 6 is an end elevational view taken along the line 6-6 of Fig. 4;
Fig. 7 is a sectional view taken substantially along the line 7-7 of Fig. 4, illustrating the alternate use of either an extruded reinforcing wire or a metal reinforcing wire;
Fig. 8 is similar to Fig. 3, but shows an alternate construction of the rigid/flexible tube; and Fig. 9 is similar to Fig. 3, but shows a second alternate construction of the rigid/flexible tube.
DESCRIPTION OF THE PREFERRED EMBODIMENT
By way of disclosing a preferred embodiment of the invention, and not by way of limitation, there is shown in Fig. 1 a rigid/flexible tube 10. The tube includes three relatively thick-walled, straight, and rigid segments 12, 14 and 16, and two relatively thin-walled and flexible segments 18 and 20 disposed between the rigid segments. Flexible segment 18 is bent at approximately 45 degrees, while flexible segment 20 is bent at approximately 90 degrees. The tube is manufactured to a predetermined length, and the rigid and flexible segments are provided at predetermined locations and lengths alternating along the length of the tube according to the intended end use of the tube. The tube i9 shown bent to illustrate the rGuting of the tubing when it is installed. The tube illustrated is but one example of the many possible configurations within the scope of the invention.
Figs. 2 and 3 show greater detail of the tubing of the invention. The tube has a substantially circular transverse cross section and has a helical ridge 22 formed by the helically wrapped continuous web 23 overlying a reinforcing ~trand 24. The length of tube shown includes two, longitudinally spaced-apart, relatively thick-walled and rigid segments 26 and 28, and a relatively thin-walled an~ flexible segment 30 disposed intermediate the two rigid segments.
As best shown in Fig. 3, in which the thickness of the web 23 is exaggerated for clarity of illustration, the relatively rigid segments of the tube 26, 28 have walls made up of wrappings of the continuous web 23 in which the web is relatively thick as at wrappings 31-34. The relatively flexible section 30 has a wall made of wrappings of the web in which the web is relati~ely thin as at wrappings 35 and 36. The reinforcing strand 24 is a preformed metal or plastic wire. Alternatively the reinforcing strand may be a plastic-coated metal wire or a plastic wire formed by extrusion simultaneously with the formation of the tube, as more fully described below.
Figs. 4 through 7 illustrate the apparatus and method for producing the rigidtflexible tube 10 according to the invention. In its general organization, the apparatus includes a web extruder die 38 positioned near a rolling apparatus 40. The extruder includes, in a well known manner (not shown in the figures), a hopper of pelletized thermoplastic material, a heater for melting the material, and a screw for forcing the molten or softened material through a die. The die 38 is configured to extrude the material into a ribbon-like continuous web 23.
The drive means 42 includes in its general organization a variable speed electric motor 102 with a motor drive gear 103, a drive chain 104, a linking chain 106, a support frame 108, five flexible drive shafts, three of which designated at llOa-llOc in Fig. 4 (two others being hidden from view) support plates 112 and 114, five outer drive gears 116a-116e, and five inner drive gears, three of which are designated at 118a-118c (two others being hidden from view). The inner and outer drive gears are fixedly mounted on five drive shafts 120a-120e which, in turn, are fixed to the flexible drive shafts llOa-llOc etc. The number of drive shafts, rollers, etc., may vary according to the diameter of the tube to be formed. Preferably, at least four are used.
Electric motor 102 rotates motor drive gear 103 which, in turn, drives drive chain 104. As best shown in Fig. 5, drive chain 104 engages outer drive gears 116a, 116b, 116d, and 116e, thus rotating the corresponding drive shafts 120a, 120b, 120d, and 120e. The rotation of these drive shafts also rotates the commonly mounted inner drive gears 118a etc. All five of the inner drive gears 118a etc. are linked by linking chain 106, thus causing all five drive shafts 120a etc. to rotate in a common direction and speed.
The drive shafts 120a etc. in turn cause the flexible drive shafts llOa etc. to commonly rotate. The flexibility of the drive shafts llOa etc. transfers the rotational motion from the larger circumference encompassing the gears 118a etc. to the smaller circumference encompassing the forming rollers 44a etc.
and accommodates the skewing of the forming rollers.
A pipe 130 extends from t~le rear of the apparatus ~hrough the drive means and to the forward end of the forming rollers 44a etc. At the forward end of the pipe, an end plate 132 is fixed to the end of the pipe. The end plate carries five pin bearings such as bearing 134 disposed equally spaced about a circle. The forming rollers 44a etc. each extend from a pin bearing rearwardly to the support plate 112 where they are journalled for rotation and driven by the flexible drive shafts llOa etc.
The longitudinal axes of the forming rollers are not parallel to the longitudinal axis of the apparatus 40 but are instead slightly helically skewed. As best shown in Fig. 6, the ends of the forming rollers 44a etc., supported on the pin bearings 134 of end plate 132, are offset slightly counterclockwise with respect with the opposite ends of the forming rollers journalled on plate 112 as indicated by arrow 13a. A clamp with tightening screws 140 is provided to allow for adjustment of the amount of helical skewing of the forming rollers.
As best shown in Fig. 4 and 7, the freshly extruded web 23, preferably made of a thermoplastic elastomer material, such as a blend of EDPM rubber and polypropylene, emerges from the die 38 near the rolling apparatus 40 in a direction tangent to the cylindrical envelope of the forming rollers 44a-44e. The rotation of the forming rollers takes up the web as it advances, thereby wrapping the web into a cylindrical, continuous tube 10.
A reel 71 of plastic or metal reinforcing wire 24 is rotatably supported below the web extruder die. '~he wire is taken up by the forming rollers and helically wrapped therearound lying between overlapping wrappings of the web.
S~ L ~ J ~
A pressure roller 48 is provided situated externally of the newly formed tube. The wall material of the tubing is still hot from the extrusion process when it reaches the pressure roller. The pressure roller 48 presses the tube against the 5 forming roller 44c to enhance the bonding of the wrappings of the web and to aid in maintaining tension in the web 23. The pressure roller 48 is formed with a circumferential groove 73 to accommodate the ridge formed by the reinforcing strand. The forming rollers are similarly formed with grooves 74 to accommodate a corresponding ridge on the inside of the tube.
Optionally, the pressure roller 48 may be omitted if the characteristics of the web material are such that the wrappings spontaneously bond together without the application of additional pressure.
As the tube 10 is formed it is cooled by a jet of air 59 from the nearby nozzle 58. The forward end of the pipe 130 is formed with perforations 160 through which cooling air 161 is also blown. An ample flow of cooling air is necessary to harden the tube as soon as possible after its formation.
As the tube is being formed, the rate of rotation of the forming rollers 44a-44e is controlled by programmable logic controller 80. Controller 80 is electrically connected by suitable wiring 81 to the variable speed electric motor 102.
When a relatively thick-walled and rigid segment of tube is being formed, the controller causes the motor to operate at a relatively slower speed. The forming rollers thereby rotate at a correspondingly slower speed causing the tubing wall to be formed of relatively thicker wrappings of the web 23 such as shown with wrappings 31-34 of Fig. 3. The controller 80 is fed signals from which the rate of speed of the forming apparatus by wiring 83 connected to a suitable pick up on shaft 120a. Alternatively, 2r~t?.~,~
wiring 82 is connected to a suitable pick up for detecting the rotation of reel 71.
When a relatively thin-walled and flexible segment of the tube is being formed, the controller causes the motor to operate at a relatively faster speed. The forming rollers thereby rotate at a correspondingly higher speed. The higher speed causes the web to be drawn out to a lesser thickness. The helical wrappings of the drawn out web, such as wrappings 35 and 36 of Fig. 3, form the flexible segments of the tube.
The reinforcing strand may be a thermoplastic wire formed by extrusion substantially simultaneously with the formation of the web. As shown in Fig. 7, a wire extruder 72 is used instead of the reel 71 to form wire 24'. The freshly extruded plastic wire 24' is taken up on the forming rollers in the same manner as metal wire 24. With this embodiment, varying the speed of rotation of the forming rollers is undesirable since it would be difficult to control the diameter of the freshly extruded plastic wire 24'. Instead, the programmable logic controller 80 is connected to the web extruder 28 by wire 85, and the rate of extrusion of the web 23 is varied. When a relatively thin and flexible segment of the tube is being formed, the extrusion of the web 23 is slowed, while the rotation speed of the forming rollers and the extrusion rate of the wire extruder 72 is kept substantially constant. For a rigid tube segment, the web extruder is speeded up while the forming rollers and wire extruder again remain at constant speed and rate.
The controller is preferably preprogrammed to automatically vary the speed of the apparatus so as to form the rigid and flexible segments of the tube at the desired locations and at the desired lengths. Preferably, the lengths of the flexible segments correspond to the angle of the bends to be made when the tube is installed. As will be apparent to those familiar with the art, the length required for a given bend angle will depend on the tube diameter and the bend radius.
After the tube 10 has advanced off the forming rollers, it is cut to desired lengths at appropriate locations, thus forming a rigid/flexible tube such as shown in Fig. 1. The controller 80 recycles to produce large numbers of identical tubes, or is reprogrammed to produce a new tube configuration.
An alternate construction of the rigid/flexible tube according to the principles of the invention i9 shown in Fig. 8.
The reinforcing strand 24" comprises a metal wire core 141 having a plastic coating 142. Preferably, the coating 142 is of a material compatible with the web 23" such that the coating spontaneously bonds to the hot web upon contact.
Fig. 8 further shows an alternate wrapping configuration in which the width of the web 23' is approximately equal to twice the pitch P of the reinforcing strand 24". The reinforcing strand further is disposed under the wrapping and exposed to the interior of the tubing.
Fig. 9 shows a second alternate construction of the tube in which the width of the web 23" is somewhat greater than the pitch of the wire 145 but less than twice the pitch. Each winding of the wire is disposed between a single layer of the web. Numerous other configurations are possible within the scope of the invention.
The above description is that of a preferred embodiment of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention as set forth in the appended claims, which are to be interpreted in accordance with the principles of patent law, including the Doctrine of Equivalents.
Claims
The embodiments of the invention in which an exclusive property or privilege is claimed as follows:
A tube comprising a substantially cylindrical wall formed of helically coiled, overlapping wrappings of a continuous extruded web of thermoplastic material and including at least one relatively rigid segment and at least one relatively flexible segment, the extrusion section of the web being variable, with said relatively rigid segment being formed of wrappings of said web having a relatively greater web thickness, and said relatively flexible segment being formed of wrappings of said web having a relatively lesser web thickness.
The tube of claim 1 further comprising a helically coiled reinforcing strand.
The tube of claim 2 wherein said reinforcing strand comprises a metal wire.
The tube of claim 2 wherein said reinforcing strand comprises a wire of thermoplastic material.
The tube of claim 4 wherein said reinforcing strand comprises a plastic-coated metal wire.
The tube of claim 1 further comprising at least two of said rigid segments wherein said at least one flexible segment is disposed between said rigid segments at a predetermined location along the length of said tube.
The tube of claim 6 wherein said at least one flexible segment is formed in a predetermined length corresponding to a desired tube bend angle.
A method for forming a tube having at least one relatively rigid segment and at least one relatively flexible segment comprising the steps of:
providing an advancing web of freshly extruded, thermoplastic material;
helically coiling said web into overlapping wrappings at a relatively lower coiling speed to form said relatively rigid segment as having a wall formed of web wrappings of relatively greater thickness;
helically coiling said web into overlapping wrappings at a relatively higher coiling speed so as to draw out said web and form said relatively flexible segment as having a wall formed of web wrappings of relatively lesser thickness.
The method of claim 8 further comprising the step of helically coiling a reinforcing strand along with said web.
The method of claim 8 wherein said steps of coiling at a relatively lower coiling speed and coiling at a relatively higher coiling speed are alternately repeated thereby forming a plurality of said rigid and flexible segments disposed at predetermined locations along the length of the tube.
The method of claim 10 further comprising the step of forming said flexible segments in predetermined lengths corresponding to desired tube bend angles.
A method for producing a tube having relatively rigid segments and relatively flexible segments disposed at intervals along the length of the tube comprising the steps of:
extruding an advancing web of heated, thermoplastic material;
taking up said freshly extruded advancing web on a plurality of rotating forming rollers disposed within a cylindrical envelope;
helically wrapping said advancing web around said forming rollers into a tube having a wall formed of a plurality of overlapping layers of said web while advancing said tube along said forming rollers;
varying the speed of at least one of either the rotation of said forming rollers or the extruding of said web such that portions of said web are taken up on said forming rollers at a relatively greater thickness to form said rigid segments of said tube and portions of said web are taken up on said forming rollers at a relatively lesser thickness to form said relatively flexible segments.
The method of claim 12 further comprising the step of helically taking up a reinforcing strand on said forming rollers.
The method of claim 12 wherein said step of varying the speed comprises varying the speed of rotation of said forming rollers while keeping the rate of extrusion of said web substantially constant.
The method of claim 12 wherein said step of varying the speed comprises varying the rate of extrusion of said web while keeping the speed of rotation of said forming rollers substantially constant.
The method of claim 15 further comprises extruding a reinforcing strand of thermoplastic material and taking up the freshly extruded reinforcing strand on the forming rollers along with said web.
An apparatus for producing a tube having at least one relatively rigid segment and at least one relatively flexible segment from a helically coiled continuous web of thermoplastic material comprising:
means for extruding a continuous web of thermoplastic material;
means for helically wrapping the freshly extruded web into a tube having a wall formed of a plurality of overlapping layers of said web; and means for varying at least one of either the rate of helical wrapping of the web or the rate of extrusion of the web such that portions of the web are wrapped at a relatively greater thickness to form a relatively rigid tube wall segment and portions of the web are wrapped at a relatively lesser thickness to form a relatively flexible tube wall segment.
The apparatus of claim 17 further comprising means for introducing a helically coiled reinforcing strand around said means for helically wrapping.
The apparatus of claim 18 wherein said means for introducing comprises a thermoplastic wire extruder.
The apparatus of claim 17 further comprising programmable logic controller means for controlling the varying of said rates so as to form said flexible and rigid segments at predetermined locations and lengths along the length of said tube.
An apparatus for producing a tube formed as helically coiled wrappings of a continuous web of thermoplastic material, said tube having a plurality of relatively thick-walled rigid segments and relatively thin-walled flexible segments disposed at intervals along the length of said tube, said apparatus comprising:
means for extruding an advancing web of heated, drawable, thermoplastic material;
a plurality of co-rotating forming rollers disposed in helically skewed relationship about a central axis having their outer extents defining a cylindrical envelope, said forming rollers further disposed near said means for extruding and adapted to helically wrap said web into an advancing tube having a wall formed of overlapping layers of said web;
means for selectively varying the speed of rotation of said forming rollers between a relatively lower speed of rotation and a relatively higher speed of rotation;
whereby portions of said web taken up on said forming rollers at said relatively lower speed of forming roller rotation form said relatively rigid segments of said tube, and whereby portions of said web taken up on said forming rollers at said relatively higher speed of forming roller rotation are drawn out to a lesser web thickness and form said flexible segments of said tube.
The apparatus of claim 21 wherein said means for selectively varying the speed of rotation of said forming rollers comprises a programmable logic controller causing said relatively rigid and flexible segments to be formed at predetermined locations and lengths along the length of said tube corresponding to the intended end use of the tube.
The apparatus of claim 21 further comprising means for introducing a reinforcing strand helically coiled along with said web.
An apparatus for producing a tube formed as helically coiled wrappings of a continuous web of thermoplastic material, said tube having a plurality of relatively thick-walled rigid segments and relatively thin-walled flexible segments disposed at intervals along the length of said tube, said apparatus comprising:
means for extruding an advancing web of heated, drawable, thermoplastic material;
a plurality of co-rotating forming rollers disposed in helically skewed relationship about a central axis having their outer extents defining a cylindrical envelope, said forming rollers further disposed near said means for extruding and adapted to helically wrap said web into an advancing tube having a wall formed of overlapping layers of said web;
means for selectively varying the speed of extrusion of said web between a relatively lower speed of extrusion and a higher speed of rotation;
whereby portions of said web taken up on said forming rollers at said relatively lower speed of extrusion form said relatively flexible segments of said tube, and whereby portions of said web taken up on said forming rollers at said relatively higher speed of extrusion form said relatively rigid segments of said tube.
The apparatus of claim 24 wherein said means for selectively varying the speed of extrusion comprises a programmable logic controller causing said relatively rigid and flexible segments to be formed at predetermined locations and lengths along the length of said tube corresponding to the intended end use of the tube.
The apparatus of claim 25 further comprising means for introducing a reinforcing strand helically coiled along with said web.
The apparatus of claim 26 wherein said means for introducing comprises a thermoplastic wire extruder.
A tube comprising a substantially cylindrical wall formed of helically coiled, overlapping wrappings of a continuous extruded web of thermoplastic material and including at least one relatively rigid segment and at least one relatively flexible segment, the extrusion section of the web being variable, with said relatively rigid segment being formed of wrappings of said web having a relatively greater web thickness, and said relatively flexible segment being formed of wrappings of said web having a relatively lesser web thickness.
The tube of claim 1 further comprising a helically coiled reinforcing strand.
The tube of claim 2 wherein said reinforcing strand comprises a metal wire.
The tube of claim 2 wherein said reinforcing strand comprises a wire of thermoplastic material.
The tube of claim 4 wherein said reinforcing strand comprises a plastic-coated metal wire.
The tube of claim 1 further comprising at least two of said rigid segments wherein said at least one flexible segment is disposed between said rigid segments at a predetermined location along the length of said tube.
The tube of claim 6 wherein said at least one flexible segment is formed in a predetermined length corresponding to a desired tube bend angle.
A method for forming a tube having at least one relatively rigid segment and at least one relatively flexible segment comprising the steps of:
providing an advancing web of freshly extruded, thermoplastic material;
helically coiling said web into overlapping wrappings at a relatively lower coiling speed to form said relatively rigid segment as having a wall formed of web wrappings of relatively greater thickness;
helically coiling said web into overlapping wrappings at a relatively higher coiling speed so as to draw out said web and form said relatively flexible segment as having a wall formed of web wrappings of relatively lesser thickness.
The method of claim 8 further comprising the step of helically coiling a reinforcing strand along with said web.
The method of claim 8 wherein said steps of coiling at a relatively lower coiling speed and coiling at a relatively higher coiling speed are alternately repeated thereby forming a plurality of said rigid and flexible segments disposed at predetermined locations along the length of the tube.
The method of claim 10 further comprising the step of forming said flexible segments in predetermined lengths corresponding to desired tube bend angles.
A method for producing a tube having relatively rigid segments and relatively flexible segments disposed at intervals along the length of the tube comprising the steps of:
extruding an advancing web of heated, thermoplastic material;
taking up said freshly extruded advancing web on a plurality of rotating forming rollers disposed within a cylindrical envelope;
helically wrapping said advancing web around said forming rollers into a tube having a wall formed of a plurality of overlapping layers of said web while advancing said tube along said forming rollers;
varying the speed of at least one of either the rotation of said forming rollers or the extruding of said web such that portions of said web are taken up on said forming rollers at a relatively greater thickness to form said rigid segments of said tube and portions of said web are taken up on said forming rollers at a relatively lesser thickness to form said relatively flexible segments.
The method of claim 12 further comprising the step of helically taking up a reinforcing strand on said forming rollers.
The method of claim 12 wherein said step of varying the speed comprises varying the speed of rotation of said forming rollers while keeping the rate of extrusion of said web substantially constant.
The method of claim 12 wherein said step of varying the speed comprises varying the rate of extrusion of said web while keeping the speed of rotation of said forming rollers substantially constant.
The method of claim 15 further comprises extruding a reinforcing strand of thermoplastic material and taking up the freshly extruded reinforcing strand on the forming rollers along with said web.
An apparatus for producing a tube having at least one relatively rigid segment and at least one relatively flexible segment from a helically coiled continuous web of thermoplastic material comprising:
means for extruding a continuous web of thermoplastic material;
means for helically wrapping the freshly extruded web into a tube having a wall formed of a plurality of overlapping layers of said web; and means for varying at least one of either the rate of helical wrapping of the web or the rate of extrusion of the web such that portions of the web are wrapped at a relatively greater thickness to form a relatively rigid tube wall segment and portions of the web are wrapped at a relatively lesser thickness to form a relatively flexible tube wall segment.
The apparatus of claim 17 further comprising means for introducing a helically coiled reinforcing strand around said means for helically wrapping.
The apparatus of claim 18 wherein said means for introducing comprises a thermoplastic wire extruder.
The apparatus of claim 17 further comprising programmable logic controller means for controlling the varying of said rates so as to form said flexible and rigid segments at predetermined locations and lengths along the length of said tube.
An apparatus for producing a tube formed as helically coiled wrappings of a continuous web of thermoplastic material, said tube having a plurality of relatively thick-walled rigid segments and relatively thin-walled flexible segments disposed at intervals along the length of said tube, said apparatus comprising:
means for extruding an advancing web of heated, drawable, thermoplastic material;
a plurality of co-rotating forming rollers disposed in helically skewed relationship about a central axis having their outer extents defining a cylindrical envelope, said forming rollers further disposed near said means for extruding and adapted to helically wrap said web into an advancing tube having a wall formed of overlapping layers of said web;
means for selectively varying the speed of rotation of said forming rollers between a relatively lower speed of rotation and a relatively higher speed of rotation;
whereby portions of said web taken up on said forming rollers at said relatively lower speed of forming roller rotation form said relatively rigid segments of said tube, and whereby portions of said web taken up on said forming rollers at said relatively higher speed of forming roller rotation are drawn out to a lesser web thickness and form said flexible segments of said tube.
The apparatus of claim 21 wherein said means for selectively varying the speed of rotation of said forming rollers comprises a programmable logic controller causing said relatively rigid and flexible segments to be formed at predetermined locations and lengths along the length of said tube corresponding to the intended end use of the tube.
The apparatus of claim 21 further comprising means for introducing a reinforcing strand helically coiled along with said web.
An apparatus for producing a tube formed as helically coiled wrappings of a continuous web of thermoplastic material, said tube having a plurality of relatively thick-walled rigid segments and relatively thin-walled flexible segments disposed at intervals along the length of said tube, said apparatus comprising:
means for extruding an advancing web of heated, drawable, thermoplastic material;
a plurality of co-rotating forming rollers disposed in helically skewed relationship about a central axis having their outer extents defining a cylindrical envelope, said forming rollers further disposed near said means for extruding and adapted to helically wrap said web into an advancing tube having a wall formed of overlapping layers of said web;
means for selectively varying the speed of extrusion of said web between a relatively lower speed of extrusion and a higher speed of rotation;
whereby portions of said web taken up on said forming rollers at said relatively lower speed of extrusion form said relatively flexible segments of said tube, and whereby portions of said web taken up on said forming rollers at said relatively higher speed of extrusion form said relatively rigid segments of said tube.
The apparatus of claim 24 wherein said means for selectively varying the speed of extrusion comprises a programmable logic controller causing said relatively rigid and flexible segments to be formed at predetermined locations and lengths along the length of said tube corresponding to the intended end use of the tube.
The apparatus of claim 25 further comprising means for introducing a reinforcing strand helically coiled along with said web.
The apparatus of claim 26 wherein said means for introducing comprises a thermoplastic wire extruder.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US72852691A | 1991-07-11 | 1991-07-11 | |
| US728,526 | 1991-07-11 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2073402A1 CA2073402A1 (en) | 1993-01-12 |
| CA2073402C true CA2073402C (en) | 1999-01-12 |
Family
ID=24927209
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2073402 Expired - Fee Related CA2073402C (en) | 1991-07-11 | 1992-07-08 | Rigid/flexible tube |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2073402C (en) |
| MX (1) | MX9204065A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11382543B2 (en) | 2018-06-11 | 2022-07-12 | Edwards Lifesciences Corporation | Tubing system for use in a blood sampling-blood pressure monitoring system |
-
1992
- 1992-07-08 CA CA 2073402 patent/CA2073402C/en not_active Expired - Fee Related
- 1992-07-10 MX MX9204065A patent/MX9204065A/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US11382543B2 (en) | 2018-06-11 | 2022-07-12 | Edwards Lifesciences Corporation | Tubing system for use in a blood sampling-blood pressure monitoring system |
| US12121354B2 (en) | 2018-06-11 | 2024-10-22 | Edwards Lifesciences Corporation | Tubing system for use in a blood sampling-blood pressure monitoring system |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2073402A1 (en) | 1993-01-12 |
| MX9204065A (en) | 1994-06-30 |
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| Date | Code | Title | Description |
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| EEER | Examination request | ||
| MKLA | Lapsed |