CA2838903A1 - Method for bending thermoplastic pipes - Google Patents
Method for bending thermoplastic pipes Download PDFInfo
- Publication number
- CA2838903A1 CA2838903A1 CA2838903A CA2838903A CA2838903A1 CA 2838903 A1 CA2838903 A1 CA 2838903A1 CA 2838903 A CA2838903 A CA 2838903A CA 2838903 A CA2838903 A CA 2838903A CA 2838903 A1 CA2838903 A1 CA 2838903A1
- Authority
- CA
- Canada
- Prior art keywords
- bent
- pipe
- bending
- temperature
- bent pipe
- 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.)
- Granted
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B13/00—Conditioning or physical treatment of the material to be shaped
- B29B13/02—Conditioning or physical treatment of the material to be shaped by heating
- B29B13/023—Half-products, e.g. films, plates
- B29B13/024—Hollow bodies, e.g. tubes or profiles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
- B29C53/02—Bending or folding
- B29C53/08—Bending or folding of tubes or other profiled members
- B29C53/083—Bending or folding of tubes or other profiled members bending longitudinally, i.e. modifying the curvature of the tube axis
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
- B29C53/80—Component parts, details or accessories; Auxiliary operations
- B29C53/84—Heating or cooling
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Shaping Of Tube Ends By Bending Or Straightening (AREA)
Abstract
The application relates to a method for producing a bent tube (10) from thermoplastic material with end cross-sections (11), the midpoints (13) of which have a positional tolerance with respect to one another according to LN xy/jAR xy/FAR xy, wherein a straight tube element (15) is inserted into a tool (60) that is heated in a bending region (62), and a section (12a) of the straight tube element (15) that is located in the bending region (62) is warmed, the bending region (62) is heated to a temperature that lies above the glass transition temperature of the thermoplastic material at a first temperature value, and the straight tube element (15) is bent around the heated bending region (62) of the tool (60), by a bending radius (18) that is ensured by the shape of the tool (60), through a freely selectable angle (19), which has a spatial orientation in an XYZ co-ordinate system that is fixed relative to the tube (10), and the tube element (20) bent in accordance with the preceding step is cooled to a second temperature value to below the glass transition temperature of the thermoplastic material.
Description
METHOD FOR BENDING THERMOPLASTIC PIPES
Prior art The bending of straight lengths of pipe into bent pipes by means of press bending, roll bending or 3-roller push bending is known in mechanical engineering. In the production of bent pipes for pipe networks, the prime objective is to achieve high production precision.
High production precision takes the form of maintaining narrow positional tolerances of end regions of pipes that can be installed at their intended location without additional bending stress.
In particular in the case of pipe networks, in which stress-free installation must be ensured for technical reasons, production with high accuracy is absolutely necessary. Production precision in the case of bent pipes also takes the form of maintaining the roundness of the bent pipe.
Deviations from the circular cross-section of a pipe, known as ovality, in the end cross-section make it more difficult to make a connection to another pipe to which the bent pipe is intended to be connected.
Furthermore, ovality between end cross-sections of a pipe in which fluid is carried under varying pressure has the effect that the region with the oval cross-section has a short lifetime.
Furthermore, many technical areas in which bent pipes are used strive for weight-saving constructions, and aim to use plastic pipes instead of metal pipes.
GB 2 390 566 A discloses a method for bending a thermoplastic pipe in which a thermoplastic pipe is bent in a heated state around a bending body. An infrared emitter is used there for heating the thermoplastic pipe. Furthermore, in a final step, the heated bent pipe is cooled. A
disadvantage of this method is the high thermal distortion and the limited production precision.
US 6,287,508 B1 relates to a method for producing bent thermoplastic pipes. A
tubular article has a certain three-dimensional bent configuration, the article having a substantially circular cross section that extends over the entire length of the bent article. The ends of the article are clamped in suitable coupling pieces, so that the bent article lies between these clamping elements. The coupling elements that receive the ends of the bent article can be braced one against the other. Subsequently, a heated fluid that is under pressure is introduced into the tubular body. With the fluid that is under pressure, the tubular article is preformed. By applying mechanical pressure to the outer surface of the preform filled with the fluid in one or more predetermined regions, the preform is brought into its predetermined three-dimensional configuration.
WO 97/07969 Al relates to the bending of pipes. A bent pipe is produced from a heat-sensitive
Prior art The bending of straight lengths of pipe into bent pipes by means of press bending, roll bending or 3-roller push bending is known in mechanical engineering. In the production of bent pipes for pipe networks, the prime objective is to achieve high production precision.
High production precision takes the form of maintaining narrow positional tolerances of end regions of pipes that can be installed at their intended location without additional bending stress.
In particular in the case of pipe networks, in which stress-free installation must be ensured for technical reasons, production with high accuracy is absolutely necessary. Production precision in the case of bent pipes also takes the form of maintaining the roundness of the bent pipe.
Deviations from the circular cross-section of a pipe, known as ovality, in the end cross-section make it more difficult to make a connection to another pipe to which the bent pipe is intended to be connected.
Furthermore, ovality between end cross-sections of a pipe in which fluid is carried under varying pressure has the effect that the region with the oval cross-section has a short lifetime.
Furthermore, many technical areas in which bent pipes are used strive for weight-saving constructions, and aim to use plastic pipes instead of metal pipes.
GB 2 390 566 A discloses a method for bending a thermoplastic pipe in which a thermoplastic pipe is bent in a heated state around a bending body. An infrared emitter is used there for heating the thermoplastic pipe. Furthermore, in a final step, the heated bent pipe is cooled. A
disadvantage of this method is the high thermal distortion and the limited production precision.
US 6,287,508 B1 relates to a method for producing bent thermoplastic pipes. A
tubular article has a certain three-dimensional bent configuration, the article having a substantially circular cross section that extends over the entire length of the bent article. The ends of the article are clamped in suitable coupling pieces, so that the bent article lies between these clamping elements. The coupling elements that receive the ends of the bent article can be braced one against the other. Subsequently, a heated fluid that is under pressure is introduced into the tubular body. With the fluid that is under pressure, the tubular article is preformed. By applying mechanical pressure to the outer surface of the preform filled with the fluid in one or more predetermined regions, the preform is brought into its predetermined three-dimensional configuration.
WO 97/07969 Al relates to the bending of pipes. A bent pipe is produced from a heat-sensitive
- 2 -thermoplastic material. For this purpose, the circumferential wall of the pipe is selectively heated, for example by coupling in high-frequency vibrations, parts of the circumferential wall being heated more on the inner and outer sides of the bend of the bent pipe than the remaining parts of the circumferential wall of the pipe.
DE 39 39 352 Al relates to an apparatus for bending small-caliber lengths of pipe of thermoplastic materials. An apparatus for bending small-caliber lengths of pipe of thermoplastic materials is disclosed, having a bending form in which the length of pipe can be placed and braced at normal temperature, and having a device for supplying heat, the bent length of pipe being able to be removed from the bending form after cooling. The bending form has on at least a number of portions provided along the length of the bending line in each case a recess, the cross-sectional form of which corresponds in the lower, middle and partly upper region to the cross section of the length of pipe placed in. Only the cross-sectional/entry region extending beyond the bending line is kept smaller than the outside diameter of the length of pipe, specifically in a size ratio at which the length of pipe can be made to fit through the smaller cross-sectional/entry region by squeezing or deforming in the elastic region of the pipe cross section and can be arrested in the recess by the pipe wall springing back when it comes to lie on the lower region of the cross-sectional form.
Disclosure of the invention The method according to the invention overcomes the disadvantages of the methods known from the prior art. The method according to the invention provides a possibility for producing a bent pipe of thermoplastic material. The pipe produced by the method according to the invention has end sections each with a central point having in relation to one another a positional tolerance of at most +/-1 mm. The method according to the invention comprises the following steps:
A straight pipe element is introduced into a tool which has a bending region that is heated.
Furthermore, a portion of the straight pipe element that is located in the bending region of the tool is heated by the bending region being heated. The heated portion of the straight pipe element is thereby heated to a temperature which exceeds the glass transition temperature of the thermoplastic material by a first temperature value. This establishes a temperature distribution in a portion of the straight pipe element. In this case, the highest temperatures occur in the regions that assume a minimal distance from the heated bending region of the tool.
Furthermore, low temperatures occur in regions of the straight pipe element on a part of the circumference that is remote from the bending region. In a further step, the straight pipe
DE 39 39 352 Al relates to an apparatus for bending small-caliber lengths of pipe of thermoplastic materials. An apparatus for bending small-caliber lengths of pipe of thermoplastic materials is disclosed, having a bending form in which the length of pipe can be placed and braced at normal temperature, and having a device for supplying heat, the bent length of pipe being able to be removed from the bending form after cooling. The bending form has on at least a number of portions provided along the length of the bending line in each case a recess, the cross-sectional form of which corresponds in the lower, middle and partly upper region to the cross section of the length of pipe placed in. Only the cross-sectional/entry region extending beyond the bending line is kept smaller than the outside diameter of the length of pipe, specifically in a size ratio at which the length of pipe can be made to fit through the smaller cross-sectional/entry region by squeezing or deforming in the elastic region of the pipe cross section and can be arrested in the recess by the pipe wall springing back when it comes to lie on the lower region of the cross-sectional form.
Disclosure of the invention The method according to the invention overcomes the disadvantages of the methods known from the prior art. The method according to the invention provides a possibility for producing a bent pipe of thermoplastic material. The pipe produced by the method according to the invention has end sections each with a central point having in relation to one another a positional tolerance of at most +/-1 mm. The method according to the invention comprises the following steps:
A straight pipe element is introduced into a tool which has a bending region that is heated.
Furthermore, a portion of the straight pipe element that is located in the bending region of the tool is heated by the bending region being heated. The heated portion of the straight pipe element is thereby heated to a temperature which exceeds the glass transition temperature of the thermoplastic material by a first temperature value. This establishes a temperature distribution in a portion of the straight pipe element. In this case, the highest temperatures occur in the regions that assume a minimal distance from the heated bending region of the tool.
Furthermore, low temperatures occur in regions of the straight pipe element on a part of the circumference that is remote from the bending region. In a further step, the straight pipe
- 3 -element is bent into a bent pipe element which has a bending radius that is ensured by the form of the bending region of the tool. The bending of the straight pipe element into a bent pipe element takes place by a freely selectable bending angle, which has a spatial alignment in an xyz system of coordinates that is fixed with respect to the pipe.
In a further step, the bent pipe element is cooled to a temperature which lies below the glass transition temperature of the thermoplastic material by a second temperature value. During the cooling, all regions of the bent pipe element reach a temperature below the glass transition temperature, while retaining the temperature distribution from the step that comprises the heating at a reduced temperature level and in a less distinct form.
Furthermore, the preceding steps may be repeated at at least one different location of the bent pipe, the respective spatial alignments of the bending angles being freely selectable.
The method according to the invention may be designed such that the first temperature value lies in a range from 5 to 100 C. Furthermore, the method may be designed such that the second temperature value lies in a range from 5 to 100 C. The heated bending region of the tool may be provided with an electrically heated flank, channels with temperature-controlled liquid that run through the tool, an infrared emitter, an induction device or a hot-air blower.
Furthermore, the method according to the invention may be designed such that the first and second temperature values are set such that the bent pipe undergoes a tolerable temperature transition with minimal distortion in the method according to the invention. A
tolerable temperature transition with minimal distortion ensures that the central points of the end cross-sections of the bent pipe in an end state have a positional tolerance in relation to one another of +1- 1 mm and the bending angle has a narrow tolerance, preferably of 0.5 .
Furthermore, the step of the method according to the invention in which the straight pipe element is bent into a bent pipe element may be designed such that the bending angle lies in a tolerance range below 0.5 .
The step of the method according to the invention in which the bent pipe element is cooled to a temperature which lies below the glass transition temperature of the thermoplastic material by a second temperature value may perform the cooling for example by means of cold air, liquefied gas or water. In the method according to the invention, the first and second temperature values, the bending angle and the bending radius may be coordinated with one another, so that a deformation of the cross-section of the pipe in the direction of an ovality is prevented. If the first and second temperature values and the bending radius are coordinated with one another, the roundness of the pipe is maintained in the method according to the invention.
At the same time, a tolerable temperature transition ensures that the ovality is small, preferably less than 7%, =
In a further step, the bent pipe element is cooled to a temperature which lies below the glass transition temperature of the thermoplastic material by a second temperature value. During the cooling, all regions of the bent pipe element reach a temperature below the glass transition temperature, while retaining the temperature distribution from the step that comprises the heating at a reduced temperature level and in a less distinct form.
Furthermore, the preceding steps may be repeated at at least one different location of the bent pipe, the respective spatial alignments of the bending angles being freely selectable.
The method according to the invention may be designed such that the first temperature value lies in a range from 5 to 100 C. Furthermore, the method may be designed such that the second temperature value lies in a range from 5 to 100 C. The heated bending region of the tool may be provided with an electrically heated flank, channels with temperature-controlled liquid that run through the tool, an infrared emitter, an induction device or a hot-air blower.
Furthermore, the method according to the invention may be designed such that the first and second temperature values are set such that the bent pipe undergoes a tolerable temperature transition with minimal distortion in the method according to the invention. A
tolerable temperature transition with minimal distortion ensures that the central points of the end cross-sections of the bent pipe in an end state have a positional tolerance in relation to one another of +1- 1 mm and the bending angle has a narrow tolerance, preferably of 0.5 .
Furthermore, the step of the method according to the invention in which the straight pipe element is bent into a bent pipe element may be designed such that the bending angle lies in a tolerance range below 0.5 .
The step of the method according to the invention in which the bent pipe element is cooled to a temperature which lies below the glass transition temperature of the thermoplastic material by a second temperature value may perform the cooling for example by means of cold air, liquefied gas or water. In the method according to the invention, the first and second temperature values, the bending angle and the bending radius may be coordinated with one another, so that a deformation of the cross-section of the pipe in the direction of an ovality is prevented. If the first and second temperature values and the bending radius are coordinated with one another, the roundness of the pipe is maintained in the method according to the invention.
At the same time, a tolerable temperature transition ensures that the ovality is small, preferably less than 7%, =
- 4 -more preferably less than 5%, particularly preferably less than 3%.
In addition, the invention may have at least one measuring device, by means of which the temperature of a region of the surface of the pipe element is measured. The result of the measuring device is passed on to a control unit, which intervenes in the control of the heating and cooling device by means of a feedback control. The control unit ensures a processing temperature in the measured region of the surface of the pipe element that exceeds or lies below the glass transition temperature of the thermoplastic material by the first or second temperature value, depending on the method step.
Furthermore, the method according to the invention may be designed such that the surface quality of an inner side and an outer side of the bent pipe is not impaired by the bending method. The method according to the invention is substantially characterized by the parameters of the first and second temperature values, the bending radius and the bending angle.
Maintaining the surface quality of the inner side thus minimizes the frictional pipe resistance of the bent pipe. Furthermore, maintaining the surface quality of the outer side of the bent pipe makes it easier for the pipe to be installed in a situation with insulating material. In this case, the surface qualities of the inner side and outer side remain substantially the same.
Furthermore, polyether ether ketone, polyether sulphone, polyether ketone, polyphenylene sulphide or polyethyleneimine may be used in the method according to the inveniion as thermoplastic materials.
In the step of the method according to the invention in which the straight pipe element is bent into a bent pipe element, the bending region may be supported from the inside by an auxiliary means, preferably a mandrel, by gas pressure or a heat-resistant scratchproof filling material.
Heat-resistant scratchproof filling materials are, in particular, glass or steel beads.
Furthermore, the invention relates to a bent pipe which is produced from thermoplastic material and has at least one bent region. The bent region is characterized by a bending radius and a bending angle. Furthermore, the bent pipe of thermoplastic material has end cross-sections each with a central point at a distance from one another in all three coordinate axes in an xyz system of coordinates that is fixed with respect to the bent pipe. The distances of the central points of the end cross-sections in this case lie in the range of a positional tolerance of at most +1- 1 mm. Equally, the bending angle has a tolerance of below 0.5 .
Maintaining the tolerance of the bending angle and the positional tolerance of the central points of the end cross-sections ensures load-free installation of the bent pipe.
=
In addition, the invention may have at least one measuring device, by means of which the temperature of a region of the surface of the pipe element is measured. The result of the measuring device is passed on to a control unit, which intervenes in the control of the heating and cooling device by means of a feedback control. The control unit ensures a processing temperature in the measured region of the surface of the pipe element that exceeds or lies below the glass transition temperature of the thermoplastic material by the first or second temperature value, depending on the method step.
Furthermore, the method according to the invention may be designed such that the surface quality of an inner side and an outer side of the bent pipe is not impaired by the bending method. The method according to the invention is substantially characterized by the parameters of the first and second temperature values, the bending radius and the bending angle.
Maintaining the surface quality of the inner side thus minimizes the frictional pipe resistance of the bent pipe. Furthermore, maintaining the surface quality of the outer side of the bent pipe makes it easier for the pipe to be installed in a situation with insulating material. In this case, the surface qualities of the inner side and outer side remain substantially the same.
Furthermore, polyether ether ketone, polyether sulphone, polyether ketone, polyphenylene sulphide or polyethyleneimine may be used in the method according to the inveniion as thermoplastic materials.
In the step of the method according to the invention in which the straight pipe element is bent into a bent pipe element, the bending region may be supported from the inside by an auxiliary means, preferably a mandrel, by gas pressure or a heat-resistant scratchproof filling material.
Heat-resistant scratchproof filling materials are, in particular, glass or steel beads.
Furthermore, the invention relates to a bent pipe which is produced from thermoplastic material and has at least one bent region. The bent region is characterized by a bending radius and a bending angle. Furthermore, the bent pipe of thermoplastic material has end cross-sections each with a central point at a distance from one another in all three coordinate axes in an xyz system of coordinates that is fixed with respect to the bent pipe. The distances of the central points of the end cross-sections in this case lie in the range of a positional tolerance of at most +1- 1 mm. Equally, the bending angle has a tolerance of below 0.5 .
Maintaining the tolerance of the bending angle and the positional tolerance of the central points of the end cross-sections ensures load-free installation of the bent pipe.
=
- 5 -Furthermore, the bent pipe according to the invention may be designed such that in the bent region it has a cross-section with little deviation of the roundness of the pipe, and when the pipe is subjected to internal pressure ensures a uniform stress distribution in the cross-section of the bent region. In this case, the pipe cross-section has an ovality of less than 7%, preferably less than 5%, particularly preferably less than 3%. Furthermore, the pipe according to the invention may be designed such that the pipe has over the entire circumference in the bent portion a wall thickness which deviates less than 10% from the wall thickness of the straight portion.
The bent pipe according to the invention may be designed such that a bent portion of the bent pipe has a surface quality that is the same as a straight portion of the bent pipe.
The method according to the invention may be carried out on a conventional bending device, which requires only a small amount of modification. This substantially means that a heated bending region is formed in the conventional bending device. Furthermore, a conventional bending device has NC-controlled tools, which carry out the method step comprising the bending of a straight pipe element. Carrying out the method according to the invention on a bending device with NC-controlled tools ensures reproducible method results.
Furthermore, the invention relates to the use of the bent pipe in an aircraft.
Advantages of the invention The method according to the invention provides a possibility of producing reliably and inexpensively bent pipes of thermoplastic material that meet high precision requirements, as are demanded for example in aircraft registration regulations. In numerous technical areas, the use of pipes of thermoplastic material is preferred over metal pipes on account of the weight advantage. Maintaining close production tolerances allows end cross-sections of a pipe and central points thereof to be brought into an exactly defined relative position in relation to one another. This provides the possibility of carrying out stress-free installation. A pipe which is installed stress-free is not under any pre-loading and, as a result, is less sensitive to operationally dependent load changes. Furthermore, loads which act on a structure of the installation space are avoided. For numerous applications, such as for example aircraft construction, this requirement is indispensable, so that the method according to the invention provides weight-saving pipes of thermoplastic material for numerous technical areas that have high precision requirements.
According to the method according to the invention, in a first step, a straight pipe element is
The bent pipe according to the invention may be designed such that a bent portion of the bent pipe has a surface quality that is the same as a straight portion of the bent pipe.
The method according to the invention may be carried out on a conventional bending device, which requires only a small amount of modification. This substantially means that a heated bending region is formed in the conventional bending device. Furthermore, a conventional bending device has NC-controlled tools, which carry out the method step comprising the bending of a straight pipe element. Carrying out the method according to the invention on a bending device with NC-controlled tools ensures reproducible method results.
Furthermore, the invention relates to the use of the bent pipe in an aircraft.
Advantages of the invention The method according to the invention provides a possibility of producing reliably and inexpensively bent pipes of thermoplastic material that meet high precision requirements, as are demanded for example in aircraft registration regulations. In numerous technical areas, the use of pipes of thermoplastic material is preferred over metal pipes on account of the weight advantage. Maintaining close production tolerances allows end cross-sections of a pipe and central points thereof to be brought into an exactly defined relative position in relation to one another. This provides the possibility of carrying out stress-free installation. A pipe which is installed stress-free is not under any pre-loading and, as a result, is less sensitive to operationally dependent load changes. Furthermore, loads which act on a structure of the installation space are avoided. For numerous applications, such as for example aircraft construction, this requirement is indispensable, so that the method according to the invention provides weight-saving pipes of thermoplastic material for numerous technical areas that have high precision requirements.
According to the method according to the invention, in a first step, a straight pipe element is
- 6 -heated beyond the glass transition temperature of the thermoplastic material by a value from a range from 5 to 100 C. After exceeding the glass transition temperature, the thermoplastic material has good deformability. Even when the glass transition temperature is exceeded by a small temperature value, there is deformability of the thermoplastic material, which increases with further increasing of the temperature. Furthermore, the deformability of the thermoplastic material is no longer obtained at a temperature below the glass transition temperature. To save energy, it is therefore possible to dispense with cooling any further.
Furthermore, continuous measurement and feedback control of the temperature at the surface of the pipe element ensures good deformability thereof in the entire portion to be bent of the pipe element. The measuring of the temperature of the surface may be carried out here by means of thermocouples. In addition, a selection of temperature values that lie between 50 and 100 C
above or below the glass transition temperature of the thermoplastic material represents a tolerable temperature transition of the pipe in the method. A tolerable temperature transition ensures a minimization of the thermal distortion of the pipe in the method according to the invention. A minimal thermal distortion reduces the deviation from the desired deformation and increases the production precision. Positional tolerances of the central points of the end cross-sections of at most +/- 1 mm and tolerances of the bending angle of below 0.5 are made possible as a result.
Furthermore, such a temperature transition of the thermoplastic material in the method according to the invention reduces the need for heating and cooling power and increases the possible speed of the process.
Furthermore, the method according to the invention ensures that pipes produced by means of the method have a minimal ovality. A minimal ovality, and consequently a high degree of roundness, ensures that, when there is varying loading from internal pressure, a state ot stress that is uniform over the circumference of the pipe is established in the pipe cross-section. A
uniform state of stress is free from stress peaks, which cause high degrees of loading on the material at the locations at which they occur, and thus reduce the lifetime of the pipe. An ovality of less than 3% in this case ensures a lifetime of bent portions that are substantially identical to the lifetime of straight portions.
In principle, the ovality is all the less the greater the bending radius 18.
Ovalized cross-sections also have a smaller cross-sectional area than the circular cross-sections from which they are produced. As a result, a fluid flow is accelerated in an ovalized region. An increased speed of a liquid flow in a pipe causes additional flow resistance, and consequently additional pressure loss. The method according to the invention minimizes these disadvantageous effects.
Furthermore, continuous measurement and feedback control of the temperature at the surface of the pipe element ensures good deformability thereof in the entire portion to be bent of the pipe element. The measuring of the temperature of the surface may be carried out here by means of thermocouples. In addition, a selection of temperature values that lie between 50 and 100 C
above or below the glass transition temperature of the thermoplastic material represents a tolerable temperature transition of the pipe in the method. A tolerable temperature transition ensures a minimization of the thermal distortion of the pipe in the method according to the invention. A minimal thermal distortion reduces the deviation from the desired deformation and increases the production precision. Positional tolerances of the central points of the end cross-sections of at most +/- 1 mm and tolerances of the bending angle of below 0.5 are made possible as a result.
Furthermore, such a temperature transition of the thermoplastic material in the method according to the invention reduces the need for heating and cooling power and increases the possible speed of the process.
Furthermore, the method according to the invention ensures that pipes produced by means of the method have a minimal ovality. A minimal ovality, and consequently a high degree of roundness, ensures that, when there is varying loading from internal pressure, a state ot stress that is uniform over the circumference of the pipe is established in the pipe cross-section. A
uniform state of stress is free from stress peaks, which cause high degrees of loading on the material at the locations at which they occur, and thus reduce the lifetime of the pipe. An ovality of less than 3% in this case ensures a lifetime of bent portions that are substantially identical to the lifetime of straight portions.
In principle, the ovality is all the less the greater the bending radius 18.
Ovalized cross-sections also have a smaller cross-sectional area than the circular cross-sections from which they are produced. As a result, a fluid flow is accelerated in an ovalized region. An increased speed of a liquid flow in a pipe causes additional flow resistance, and consequently additional pressure loss. The method according to the invention minimizes these disadvantageous effects.
- 7 -Furthermore, when the glass transition temperature is exceeded in a thermoplastic material, a transition takes place from a brittle energy-elastic behaviour to a soft entropy-elastic behaviour of the thermoplastic material. Thermoplastic materials which exhibit entropy-elastic behaviour have a high degree of formability and present virtually no forces of resilience to external mechanical effects. Formability without significant forces of resilience allows the thermoplastic material to be deformed with precision with little expenditure of force. The method according to the invention ensures precise formability with respect to bending radii and bending angles.
Precise bending radii and bending angles consequently allow the central points of the end cross-sections of a pipe processed with the aid of the method according to the invention to be brought into a relative position in relation to one another that lies within narrow positional tolerances.
The method according to the invention is not restricted to applying to a pipe only bends that lie in a common plane. Furthermore, a geometrical variability of the bent pipes to be produced is ensured by the method according to the invention. If, after a prior implementation of the method according to the invention, the pipe to be processed is turned by any desired defined angle about the longitudinal axis of the pipe, it is possible in a further implementation of the method according to the invention to provide the pipe to be processed with a further bending. Further bending of the pipe to be processed may lie here in a different plane than the prior bending.
Pipe longitudinal axes of straight portions of pipe extend here in any desired spatial directions.
In addition, the method according to the invention provides a possibility of producing bent thermoplastic pipes in which extension and compression effects only occur to a small degree in the bent regions. In this case, the wall thickness of a bent thermoplastic pipe remains virtually constant in the bent regions. A constant wall thickness ensures a uniform stress distribution when the pipe is subjected to internal pressure. The wall thickness in a bent portion of the pipe deviates from a straight portion by at most 10%. As a result, the occurrence of stress peaks is avoided and the lifetime of the bent region of the bent thermoplastic pipe is increased.
Furthermore, the method according to the invention can be carried out easily and on conventional bending devices with simple modifications. As a result, the method according to the invention increases the number of possibilities for producing bent thermoplastic pipes and can be easily put into practice.
Furthermore, conventional bending devices today have NC-controlled tools which can carry out the method according to the invention. The NC-controlled tools allow process parameters, such as for example the bending angle and bending rate, to be set. Furthermore, the use of NC-
Precise bending radii and bending angles consequently allow the central points of the end cross-sections of a pipe processed with the aid of the method according to the invention to be brought into a relative position in relation to one another that lies within narrow positional tolerances.
The method according to the invention is not restricted to applying to a pipe only bends that lie in a common plane. Furthermore, a geometrical variability of the bent pipes to be produced is ensured by the method according to the invention. If, after a prior implementation of the method according to the invention, the pipe to be processed is turned by any desired defined angle about the longitudinal axis of the pipe, it is possible in a further implementation of the method according to the invention to provide the pipe to be processed with a further bending. Further bending of the pipe to be processed may lie here in a different plane than the prior bending.
Pipe longitudinal axes of straight portions of pipe extend here in any desired spatial directions.
In addition, the method according to the invention provides a possibility of producing bent thermoplastic pipes in which extension and compression effects only occur to a small degree in the bent regions. In this case, the wall thickness of a bent thermoplastic pipe remains virtually constant in the bent regions. A constant wall thickness ensures a uniform stress distribution when the pipe is subjected to internal pressure. The wall thickness in a bent portion of the pipe deviates from a straight portion by at most 10%. As a result, the occurrence of stress peaks is avoided and the lifetime of the bent region of the bent thermoplastic pipe is increased.
Furthermore, the method according to the invention can be carried out easily and on conventional bending devices with simple modifications. As a result, the method according to the invention increases the number of possibilities for producing bent thermoplastic pipes and can be easily put into practice.
Furthermore, conventional bending devices today have NC-controlled tools which can carry out the method according to the invention. The NC-controlled tools allow process parameters, such as for example the bending angle and bending rate, to be set. Furthermore, the use of NC-
- 8 -controlled tools ensures that the method according to the invention can be carried out automatically and produces reproducible results. The method according to the invention improves the process efficiency when bending thermoplastic pipes.
Brief description of the drawings In the following figures, the invention is schematically represented. The figures specifically represent the following:
Figure 1 shows a pipe bent according to the method according to the invention Figure 2 shows a pipe element before and after the method according to the invention Figure 3 shows a pipe bent according to the method according to the invention with three-dimensional alignment of the portions Figure 4 shows a flow diagram of the method according to the invention Embodiments of the invention Figure 1 shows a schematic representation of a pipe 10, which has been produced by the method according to the invention. The bent pipe 10 has end cross-sections 11, which each have a central point 13. The end cross-sections 11 have a circular cross-section. The pipe 10 has straight portions 12 and bent portions 16. A bent portion 16 is characterized by a bending radius 18 and a bending angle 19. The pipe 10 also has an inner side 22 and an outer side 24.
Furthermore, the longitudinal axes of the straight portions 12 lie in spatially different planes.
Furthermore, the straight portions 12 that end in the end cross-sections 13 are designed such that the longitudinal axes of the straight portions 12 are in line with longitudinal axes of further pipes, not depicted, with which the bent pipe 10 is to be connected.
Figure 2 schematically shows the method according to the invention for bending a thermoplastic pipe. For this purpose, in a first step, the straight pipe element 15 is introduced into the tool 60, which has a heatable bending region 62. In a following step that is not represented, the portion 12a of the straight pipe element 15 that is adjacent to the bending region 62 is heated by heating the bending region 62. In a further step that is not represented, the glass transition temperature of the thermoplastic material from which the straight pipe element 15 is produced is exceeded by 5 to 100 C. The exceeding of the glass transition
Brief description of the drawings In the following figures, the invention is schematically represented. The figures specifically represent the following:
Figure 1 shows a pipe bent according to the method according to the invention Figure 2 shows a pipe element before and after the method according to the invention Figure 3 shows a pipe bent according to the method according to the invention with three-dimensional alignment of the portions Figure 4 shows a flow diagram of the method according to the invention Embodiments of the invention Figure 1 shows a schematic representation of a pipe 10, which has been produced by the method according to the invention. The bent pipe 10 has end cross-sections 11, which each have a central point 13. The end cross-sections 11 have a circular cross-section. The pipe 10 has straight portions 12 and bent portions 16. A bent portion 16 is characterized by a bending radius 18 and a bending angle 19. The pipe 10 also has an inner side 22 and an outer side 24.
Furthermore, the longitudinal axes of the straight portions 12 lie in spatially different planes.
Furthermore, the straight portions 12 that end in the end cross-sections 13 are designed such that the longitudinal axes of the straight portions 12 are in line with longitudinal axes of further pipes, not depicted, with which the bent pipe 10 is to be connected.
Figure 2 schematically shows the method according to the invention for bending a thermoplastic pipe. For this purpose, in a first step, the straight pipe element 15 is introduced into the tool 60, which has a heatable bending region 62. In a following step that is not represented, the portion 12a of the straight pipe element 15 that is adjacent to the bending region 62 is heated by heating the bending region 62. In a further step that is not represented, the glass transition temperature of the thermoplastic material from which the straight pipe element 15 is produced is exceeded by 5 to 100 C. The exceeding of the glass transition
- 9 -temperature of the thermoplastic material brings about a transition from brittle energy-elastic behaviour to soft entropy-elastic behaviour. A formability of the thermoplastic material which ensures that the following step can be carried out is thereby achieved. In a further step, the straight pipe element 15 adjacent to the bending region 62 is bent by the bending radius 18, which is defined by the form of the tool 60. The heated portion 12a thereby undergoes forming into the bent portion 16. Furthermore, the bending about the bending region 62 of the tool 60 takes place by a bending angle 19, which can be freely chosen. The bending angle 19 also defines the position of the straight portions 12 in relation to one another.
The straight pipe element 15 thereby becomes the bent pipe element 20. In this case, the straight pipe element 15 to be bent is supported from the inside by an auxiliary means that is not represented. In a further step, the bent pipe element 20 is cooled in the bending region 18. The cooling has the effect that a temperature which lies 5 to 100 C below the glass transition temperature of the thermoplastic material is reached in the bent region 16. A transition of the thermoplastic material from soft entropy-elastic behaviour to brittle energy-elastic behaviour thereby takes place.
Figure 3 schematically shows a bent pipe 10, in which the bending angles 19 have different spatial alignments. The central points 13 of the end cross-sections 11 are relatively at a distance from one another along the x, y and z axes of a system of coordinates 40. The bent pipe 10 has in each straight portion 12 a longitudinal axis 26. The longitudinal axes 26 have a spatial alignment in relation to one another. Furthermore, the longitudinal axes 26 of the straight portions 12 that end in end cross-sections 11 are in line with longitudinal axes of pipes not represented to which the bent pipe 10 is to be connected.
Figure 4 shows the method according to the invention in a flow diagram. The initial state 100 here is the straight pipe element 15. In a first step 110, this is introduced into the tool 60. The heatable bending region 62 formed in the tool 60 lies here adjacent to the region 12a of the straight pipe element 15 that is to be bent.
Furthermore, in step 110, the region 12a of the straight pipe element 15 is heated by the heatable bending region 62. After the first step 110, the heating is carried out up to a specific temperature. The first step 110 goes over here into the second step 120, in which the region 12a of the straight pipe element 15 exceeds the glass transition temperature of the thermoplastic material from which it is produced by a first temperature value.
The first temperature value lies here between 5 and 100 C. Furthermore, in the second step 120, a transition from a brittle energy-elastic behaviour to a soft entropy-elastic behaviour takes place in the thermoplastic material. The transition to soft entropy-elastic behaviour ensures a
The straight pipe element 15 thereby becomes the bent pipe element 20. In this case, the straight pipe element 15 to be bent is supported from the inside by an auxiliary means that is not represented. In a further step, the bent pipe element 20 is cooled in the bending region 18. The cooling has the effect that a temperature which lies 5 to 100 C below the glass transition temperature of the thermoplastic material is reached in the bent region 16. A transition of the thermoplastic material from soft entropy-elastic behaviour to brittle energy-elastic behaviour thereby takes place.
Figure 3 schematically shows a bent pipe 10, in which the bending angles 19 have different spatial alignments. The central points 13 of the end cross-sections 11 are relatively at a distance from one another along the x, y and z axes of a system of coordinates 40. The bent pipe 10 has in each straight portion 12 a longitudinal axis 26. The longitudinal axes 26 have a spatial alignment in relation to one another. Furthermore, the longitudinal axes 26 of the straight portions 12 that end in end cross-sections 11 are in line with longitudinal axes of pipes not represented to which the bent pipe 10 is to be connected.
Figure 4 shows the method according to the invention in a flow diagram. The initial state 100 here is the straight pipe element 15. In a first step 110, this is introduced into the tool 60. The heatable bending region 62 formed in the tool 60 lies here adjacent to the region 12a of the straight pipe element 15 that is to be bent.
Furthermore, in step 110, the region 12a of the straight pipe element 15 is heated by the heatable bending region 62. After the first step 110, the heating is carried out up to a specific temperature. The first step 110 goes over here into the second step 120, in which the region 12a of the straight pipe element 15 exceeds the glass transition temperature of the thermoplastic material from which it is produced by a first temperature value.
The first temperature value lies here between 5 and 100 C. Furthermore, in the second step 120, a transition from a brittle energy-elastic behaviour to a soft entropy-elastic behaviour takes place in the thermoplastic material. The transition to soft entropy-elastic behaviour ensures a
- 10 -formability of the straight pipe element 15 that is required for the then following third step 130.
In the case of the third step 130, the straight pipe element 15 is bent about the bending region 62 of the tool 60. The region 12a, the temperature of which lies 5 to 100 C
above the glass transition temperature, is formed thereby into the bending region 16. The bending region 16 is characterized by the bending radius 18 and the bending angle 19. In this case, the bending radius 18 is dependent on the contour of the tool 60. The bending angle 19 can be freely chosen. The bending angle 19 establishes in which relative position the central points 13 of the end cross-sections 11 of the straight portions 12 are in relation to one another. The bent region 16 lies here between the straight pipe portions 12. Furthermore, the bending angle 19 may be set exactly in such a way that the positional tolerance of the central points 13 of the end cross-sections 11 meets the requirements of aircraft registration regulations. In addition, the bending angle 19 can be set exactly in such a way that the pipe longitudinal axis 26 of a straight pipe portion 12 that opens out in an end cross-section 11 is in line with a pipe longitudinal axis of another pipe to which the bent pipe element 20 is to be connected.
Furthermore, the parameters of the first temperature value, the bending radius 18 and the bending angle 19 are coordinated with one another in order to avoid an ovalization of a circular cross-section of the straight pipe element 15 in the region 12a.
In a further step 140, the bent pipe element 20 is cooled in the bent portion 16. In the case of step 140, the temperature is 5 to 100 C below the glass transition temperature of the thermoplastic material from which the bent pipe element 20 is produced. A
transition from soft entropy-elastic behaviour to brittle energy-elastic behaviour thereby takes place in the thermoplastic material. The formability of the bent pipe element 20 then subsides to the greatest extent. After the fourth step 140, the bent pipe element 20 remains substantially free of distortion. The bent pipe element 15 in the end state 150 thereby meets the requirements with respect to positional tolerance of the central points 13 of the end cross-sections 11 of a positional tolerance of +1- 1 mm. Equally, the bent element 15 meets the requirement of a tolerance of the bending angle of 0.5' and has an ovality of less than 3%. The wall thickness of the pipe element 15 in the bent portions 16 deviates from the wall thickness in a straight portion 12 by at most 10%.
In the case of the third step 130, the straight pipe element 15 is bent about the bending region 62 of the tool 60. The region 12a, the temperature of which lies 5 to 100 C
above the glass transition temperature, is formed thereby into the bending region 16. The bending region 16 is characterized by the bending radius 18 and the bending angle 19. In this case, the bending radius 18 is dependent on the contour of the tool 60. The bending angle 19 can be freely chosen. The bending angle 19 establishes in which relative position the central points 13 of the end cross-sections 11 of the straight portions 12 are in relation to one another. The bent region 16 lies here between the straight pipe portions 12. Furthermore, the bending angle 19 may be set exactly in such a way that the positional tolerance of the central points 13 of the end cross-sections 11 meets the requirements of aircraft registration regulations. In addition, the bending angle 19 can be set exactly in such a way that the pipe longitudinal axis 26 of a straight pipe portion 12 that opens out in an end cross-section 11 is in line with a pipe longitudinal axis of another pipe to which the bent pipe element 20 is to be connected.
Furthermore, the parameters of the first temperature value, the bending radius 18 and the bending angle 19 are coordinated with one another in order to avoid an ovalization of a circular cross-section of the straight pipe element 15 in the region 12a.
In a further step 140, the bent pipe element 20 is cooled in the bent portion 16. In the case of step 140, the temperature is 5 to 100 C below the glass transition temperature of the thermoplastic material from which the bent pipe element 20 is produced. A
transition from soft entropy-elastic behaviour to brittle energy-elastic behaviour thereby takes place in the thermoplastic material. The formability of the bent pipe element 20 then subsides to the greatest extent. After the fourth step 140, the bent pipe element 20 remains substantially free of distortion. The bent pipe element 15 in the end state 150 thereby meets the requirements with respect to positional tolerance of the central points 13 of the end cross-sections 11 of a positional tolerance of +1- 1 mm. Equally, the bent element 15 meets the requirement of a tolerance of the bending angle of 0.5' and has an ovality of less than 3%. The wall thickness of the pipe element 15 in the bent portions 16 deviates from the wall thickness in a straight portion 12 by at most 10%.
Claims (17)
1. Method for producing a bent pipe (10) from thermoplastic material with end cross-sections (11), the central points (13) of which have in relation to one another a positional tolerance of at most +/-1 mm in relation to one another, comprising the steps of:
a) introducing a straight pipe element (15) into a tool (60), which is heated in a bending region (62), b) heating a portion (12a) of the straight pipe element (15) that is located in the bending region (62), c) heating the bending region (62) to a temperature which lies above the glass transition temperature of the thermoplastic material by a first temperature value, d) bending the straight pipe element (15) about the heated bending region (62) of the tool (60) by a bending radius (18) that is ensured by the form of the tool (60), by a freely selectable bending angle (19), which has a spatial alignment in an xyz system of coordinates that is fixed with respect to the pipe (10), e) cooling the pipe element (20) bent after step d) below the glass transition temperature of the thermoplastic material by a second temperature value, wherein, in step c), a tolerance range of at most 0.50 is maintained for the bending angle, and, after step e), the bending angle (19) in the bent region still has a tolerance of 0.5 , and the thermoplastic material is polyether ether ketone, polyether sulphone, polyether ketone, polyphenylene sulphide or polyethyleneimine.
a) introducing a straight pipe element (15) into a tool (60), which is heated in a bending region (62), b) heating a portion (12a) of the straight pipe element (15) that is located in the bending region (62), c) heating the bending region (62) to a temperature which lies above the glass transition temperature of the thermoplastic material by a first temperature value, d) bending the straight pipe element (15) about the heated bending region (62) of the tool (60) by a bending radius (18) that is ensured by the form of the tool (60), by a freely selectable bending angle (19), which has a spatial alignment in an xyz system of coordinates that is fixed with respect to the pipe (10), e) cooling the pipe element (20) bent after step d) below the glass transition temperature of the thermoplastic material by a second temperature value, wherein, in step c), a tolerance range of at most 0.50 is maintained for the bending angle, and, after step e), the bending angle (19) in the bent region still has a tolerance of 0.5 , and the thermoplastic material is polyether ether ketone, polyether sulphone, polyether ketone, polyphenylene sulphide or polyethyleneimine.
2. Method according to Claim 1, characterized in that steps a) to e) are repeated at least once at a different location of the bent pipe (10), and the spatial alignments of the bending angles (19) are different.
3. Method according to Claim 1 or 2, characterized in that the first temperature value lies in a range from 5° to 100°C.
4. Method according to one of Claims 1 to 3, characterized in that the second temperature value lies in a range from 5° to 100°C.
5. Method according to one of Claims 1 to 4, characterized in that the heated bending region (62) of the tool (60) has an electrically heated flank, channels with temperature-controlled liquid, an infrared emitter, an induction device or a hot-air blower.
6. Method according to one of Claims 1 to 5, characterized in that the first and second temperature values ensure a tolerable temperature transition with minimal distortion of the bent portion of the bent pipe (10).
7. Method according to one of Claims 1 to 6, characterized in that, in step d), cold air, liquefied gas, a cooled tool (60) or water is used for cooling the bent pipe (10).
8. Method according to one of Claims 1 to 7, characterized in that the first and second temperature values and the bending radius are coordinated with one another, and the roundness of the pipe (10) is maintained, the ovality being less than 7%, preferably less than 5%, particularly preferably less than 3%.
9. Method according to one of Claims 1 to 8, characterized in that an inner side (22) and an outer side (24) of the bent pipe (10) have a surface quality that is the same.
10. Method according to one of Claims 1 to 9, characterized in that, in step d), the bending region (62) is supported from the inside by an auxiliary means.
11. Method according to Claim 10, characterized in that the auxiliary means is a mandrel, gas pressure or a heat-resistant scratchproof filling material, in particular glass or steel beads.
12. Bent pipe of thermoplastic material with straight portions (12) and at least two bent portions (16), pairs of the straight portions (12) spanning different planes, and each bent portion (16) having a bending radius (18) and a bending angle (19), and two straight portions (12) each having an end cross-section (11) with a central point (13), characterized in that the central points of the end cross-sections have a positional tolerance in relation to one another of +/- 1 mm, and the thermoplastic material is polyether ether ketone, polyether sulphone, polyether ketone, polyphenylene sulphide or polyethyleneimine, the bending angles (19) having a tolerance of below 0.5°.
13. Bent pipe according to Claim 12, characterized in that the bent pipe has in the bent region a cross-section with little deviation of the roundness, and substantially the same mechanical load-bearing capacity and lifetime as straight portions of the bent pipe.
14. Bent pipe according to Claim 13, characterized in that the deviation of the bent portions (16) has an ovality of less than 7%, preferably less than 5%, particularly preferably less than 3%.
15. Bent pipe according to one of Claims 12 to 14, characterized in that the bent pipe has in the bent portions (16) a wall thickness which deviates by less than 10% from the wall thickness of a straight portion (12) of the bent pipe.
16. Bent pipe (10) according to one of Claims 12 to 15, characterized in that the pipe element has on the inner side (22) and the outer side (24) a surface quality that is substantially the same.
17. Use of a bent pipe (10) according to one of Claims 12 to 16 in an aircraft.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201161495954P | 2011-06-10 | 2011-06-10 | |
| DE201110105279 DE102011105279A1 (en) | 2011-06-10 | 2011-06-10 | Method for bending thermoplastic pipes |
| DE102011105279.1 | 2011-06-10 | ||
| US61/495,954 | 2011-06-10 | ||
| PCT/EP2012/002297 WO2012167881A1 (en) | 2011-06-10 | 2012-05-30 | Method for producing a bent thermoplastic tube and tube obtained therefrom and use thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2838903A1 true CA2838903A1 (en) | 2012-12-13 |
| CA2838903C CA2838903C (en) | 2019-02-26 |
Family
ID=47220579
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2838903A Active CA2838903C (en) | 2011-06-10 | 2012-05-30 | Method for bending thermoplastic pipes |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP2718090B1 (en) |
| CA (1) | CA2838903C (en) |
| DE (1) | DE102011105279A1 (en) |
| WO (1) | WO2012167881A1 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103272901B (en) * | 2013-06-17 | 2016-04-20 | 沈阳飞机工业（集团）有限公司 | A kind of conduit full pattern gets method processed |
| DE102015226807A1 (en) * | 2015-12-29 | 2017-06-29 | Robert Bosch Gmbh | Component for fuel injection system and method for manufacturing a component of a fuel injection system |
| FR3074877B1 (en) | 2017-12-13 | 2019-11-01 | Stelia Aerospace | LONGITUDINAL TUBULAR CANALIZATION COMPRISING AN INTERCALAR BODY AND METHODS OF MOUNTING AND BENDING SUCH A CANALIZATION |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2601818A1 (en) * | 1976-01-20 | 1977-07-21 | Hoechst Ag | Thermoplastics tube turn or bend prodn. - by heating a straight tubular piece, introducing a supporting core, and bending about a template |
| JPS6141524A (en) * | 1984-08-03 | 1986-02-27 | Maruyasu Kogyo Kk | Method and apparatus for bending synthetic tube by resistance heating |
| JPS6184223A (en) * | 1984-10-02 | 1986-04-28 | Meiji Gomme Kasei:Kk | Bending process of thermoplastic resin tube |
| DE3727717A1 (en) * | 1987-08-17 | 1989-03-02 | Mannesmann Ag | Process and bending device for bending small-calibre pipe sections of thermoplastic, in particular for fuel lines, brake lines or hydraulic lines |
| DE3939352A1 (en) * | 1989-11-29 | 1991-06-06 | Bundy Gmbh | Bending tool for thermoplastic tubes - consists of heated block made up of lengths with suitably shaped groove which is narrower along its mouth so that tube snap-fits into it |
| US5326524A (en) * | 1990-03-23 | 1994-07-05 | Phillips Petroleum Company | Method of making plastic rods |
| DE4215920C2 (en) * | 1992-05-14 | 1994-11-17 | Schulte Franz | Method and device for bending plastic pipes |
| DE9304603U1 (en) * | 1993-03-26 | 1993-06-17 | Lippenoo, Olaf, 7573 Sinzheim | Device for bending plastic pipes |
| GB9518171D0 (en) * | 1995-08-24 | 1995-11-08 | Bundy Int Ltd | Tube bending |
| US6287508B1 (en) * | 1999-02-26 | 2001-09-11 | Dayco Products, Inc. | Method for manufacturing curved thermoplastic tubes |
| GB2390566A (en) | 2002-07-09 | 2004-01-14 | Tfx Group Ltd | Improved shaping of thermoplastic tubes |
-
2011
- 2011-06-10 DE DE201110105279 patent/DE102011105279A1/en not_active Withdrawn
-
2012
- 2012-05-30 WO PCT/EP2012/002297 patent/WO2012167881A1/en active Application Filing
- 2012-05-30 CA CA2838903A patent/CA2838903C/en active Active
- 2012-05-30 EP EP12724917.5A patent/EP2718090B1/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CA2838903C (en) | 2019-02-26 |
| DE102011105279A1 (en) | 2012-12-13 |
| EP2718090B1 (en) | 2016-02-03 |
| WO2012167881A1 (en) | 2012-12-13 |
| EP2718090A1 (en) | 2014-04-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US8931521B2 (en) | Bent thermoplastic pipe | |
| CN107755490B (en) | A kind of martensite steel 3D free bend manufacturing process | |
| CN106734429A (en) | A kind of aero titanium alloy 3D free bend warm forming devices and manufacturing process | |
| CA2838903C (en) | Method for bending thermoplastic pipes | |
| KR20110022613A (en) | Method for producing a large steel tube | |
| CN104607512B (en) | Bend forming method of large-angle pipeline with high precision, large pipe diameter and small bending diameter ratio | |
| WO2011162376A1 (en) | Pipe machining device and method | |
| Furushima et al. | Development of semi-dieless metal bellows forming process | |
| EP2072158A1 (en) | Method for bending tubular articles with a relative ratio of the bending radius and the outer diameter of the finished pipe which is less than 3. | |
| CN104858278A (en) | Die-free metal corrugated tube forming process method | |
| Lăzărescu | Effect of internal fluid pressure on quality of aluminum alloy tube in rotary draw bending | |
| Yu et al. | Theoretical analysis and experimental investigations on the symmetrical three-roller setting round process | |
| US20150367394A1 (en) | Tube flanging method | |
| CN114346021A (en) | Differential temperature free bending forming device and method for pipe made of difficult-to-deform material | |
| CN109328120A (en) | Method for the ducted body of ferrite FeCrAl alloy to be shaped to pipe | |
| CA2979430A1 (en) | Method for induction bend forming a compression-resistant pipe having a large wall thickness and a large diameter, and induction pipe bending device | |
| EP2327486A1 (en) | Method for making lined pipe bends | |
| CA2600204A1 (en) | Socketing of pipe | |
| CN112805135A (en) | Method for bending plastic pipes and device for carrying out said method | |
| RU2410180C1 (en) | Method of dieless hot forming of oil-gas-water supply steel tee pipes and system to this end | |
| CN112872285B (en) | Preparation method of titanium alloy square tube | |
| CN102672016A (en) | Manufacturing method for U-shaped tubes with ultra-small bent radiuses | |
| CN107676564A (en) | A kind of X90/X100 steel bend pipes and its manufacture method | |
| RU2329114C1 (en) | Device for formation of hollow body with alternate cross-section (options) | |
| RU2381859C2 (en) | Method of receiving of coil-type element with u-shaped bends of specified curvature of flexible monometallic or bimetallic finned conduits |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request |
Effective date: 20170511 |