System and method for manufacturing of helical inner grooved tubes
The use of rollers in the grooving device for helical inner-grooved tubes addresses production limitations by enhancing line speed and reducing rotational speed, achieving efficient and high-quality groove formation without surface damage.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- HYDRO EXTRUDED SOLUTIONS AS
- Filing Date
- 2026-01-08
- Publication Date
- 2026-07-16
AI Technical Summary
The current maximum speed of the helical grooving process for manufacturing helical inner-grooved tubes is limited by tube breakage, poor groove filling, and uneven surface marks, leading to production inefficiencies and equipment damage.
A system and method utilizing a grooving device with rollers instead of balls to reduce tube diameter and create inner grooves, allowing for increased line speed and reduced rotational speed, while maintaining surface quality and preventing ball marks.
The system enhances production capacity by increasing the line speed to over 50 m/min and reducing rotational speed by 60%, while ensuring uniform groove filling and smoother surface finish, thus improving overall manufacturing efficiency.
Smart Images
Figure EP2026050234_16072026_PF_FP_ABST
Abstract
Description
[0001] System and method for manufacturing of helical inner grooved tubes
[0002] TECHNICAL FIELD
[0003] The present invention relates to a system and a method for manufacturing of inner-grooved tubes, in particular helical inner-grooved aluminium alloy tubes.
[0004] BACKGROUND
[0005] Tubes are a vital part of heat exchangers (as well as other HVAC-R applications) wherein they provide a surface area for heat transfer. By providing internal grooves in the tubes, the surface area is enlarged as compared to traditional smooth-bore tubes and turbulent flow is promoted. The internal grooves therefore improve the tube's heat exchange rate. Due to this increased heat exchange rate, a more compact design of the heat exchangers can be achieved as well as a reduction in refrigerant load. Internally grooved tubes (IGT) can have either straight grooves or helical grooves.
[0006] Straight inner-grooved tubes can be made directly in an extrusion process. Whereas helical grooves must be provided after extrusion by means of a grooving process. Alternatively, helical grooves can be provided on a sheet material which subsequently is made into a tube by means of rolling and high frequency welding.
[0007] During helical grooving, steel balls are placed in two steel bowls forming a gear box in which the steel balls are arranged to surround the tube. The steel balls are driven by a motor to spin around the tube at high speed to press tube material into grooves of a helical grooving plug (also referred to as a grooved mandrel) arranged inside the tube. The diameter of the tube is then slightly reduced, and the inner surface of the tube is provided with helical grooves. Forcing material into the grooves of the grooving plug while pulling the tube causes the plug to rotate.
[0008] The current maximum speed of the helical grooving process is typically a limiting factor for the overall production capacity. When exceeding the current maximum speed, the result is tube breakage, poor grooves filling, damaged steel balls, and / or uneven ball marks on the outer surface of the tube. Which in turn means that tubing will be scrapped. It is therefore an aim of the present invention to provide an apparatus and a method that can increase the maximum speed of the helical grooving process without damaging the tube or the production equipment.
[0009] SUMMARY OF INVENTION
[0010] The present invention is set forth and characterized in the independent claims, while the dependent claims describe other characteristics of the invention.
[0011] The present disclosure relates to a system for manufacturing of helical inner grooved aluminium alloy tubes, wherein the system comprises: a continuous drawing machine for moving a tube in a tube direction through the system, a drawing die configured to reduce a diameter of the tube from a first diameter to a second diameter, and a grooving device arranged downstream the drawing die and configured to provide inner grooves in the tube and simultaneously reduce the diameter of the tube from the second diameter to a third diameter.
[0012] The grooving device comprises: a grooved mandrel configured to be arranged inside the tube and provide inner grooves in the tube, a floating plug configured to be held in place at a transition insidethe tube between the first diameter and the second diameter, a tie rod connected between the grooved mandrel and the floating plug such that the grooved mandrel is held in place and allowed to rotate freely at a position where the diameter of the tube is reduced to the third diameter, and a plurality of rollers configured to be rolled around the tube to reduce the diameter of the tube from the second diameter to the third diameter such that the tube is forced against the grooved mandrel and plastically deformed to obtain inner grooves, wherein each roller has a smooth outer surface. This grooving device allows the system to increase the line speed, i.e. a higher number of meters of tubing produced per minute, typically more than 50 m / min. As such the production rate can be increased.
[0013] The grooving device may comprise: a static outer body, a central body rotatably arranged in the static outer body and configured to receive the tube. The plurality of rollers is arranged in respective mounting points in the central body. The rollers are thus fixed in a radial direction, perpendicular to the tube direction. Each roller can preferably be made with an integrated shaft or alternatively be arranged on a separate shaft. The mounting point may be provided with a bushing.
[0014] This grooving device enables the system to maintain the same line speed while operating at a lower rotational speed, i.e. a lower number of revolutions per minute (rpm), as compared to the systems comprising bowls and balls.
[0015] Grooving processes will typically cause ball marks on the outer surface of the tube, resulting from the rotational movement of the balls. The ball marks are a result of the forming tool (such as balls) not being able to reduce the outer diameter of the tube and thus not being able to fill the grooves in the grooved mandrel to an equal extent in all areas. The closer the consecutive passages of the balls are, the less significant the ball marks. The passages of the balls should therefore overlap as much as possible to prevent ball marks and ensure uniform filling of helical grooves. However, the overlap depends on the rotational speed relative to the line speed. As the line speed increase, the rotational speed must be increased to maintain the required overlap. The maximum rotational speed of the system therefore sets limitations for the maximum line speed, and thus also the production rate. Since the rollers provide a larger contact surface than the balls, the overlap of consecutive passages on the tube is improved with the rollers. As compared to the balls, the rollers can provide a smoother surface at the same rotational speed, and a similar surface quality at a reduced rotational speed. For a given line speed, the rollers can allow the rotational speed to be reduced by 60 % while maintaining a similar surface quality as the rollers. As such, the ratio between rotational speed and line speed can be reduced.
[0016] Ball marks on the outer surface of the tube can be smoothed out in a subsequent (finishing) die. However, there is a correlation between the quality of the surface achieved on the outer surface and the quality of the grooves achieved on the inner surface of the tube. The inner grooves cannot be fixed in a subsequent die.
[0017] The rollers are arranged such that they can rotate around their own axis. This axis of rotation is preferably parallel to the tube direction.
[0018] The static outer body may comprise one or more bearings arranged to allow the central body to rotate. Alternatively, the bearings can be arranged on the central body.
[0019] The grooving device typically comprises a motor configured to rotate the central body, and thus the plurality of rollers.The central body is arranged to rotate around the tube such that the plurality of rollers also rotate around the tube along a rotation plane that is perpendicular to the tube direction.
[0020] To obtain a complete revolution around the outer circumference of the tube during the grooving process, the rollers of the present invention and the balls of the prior art must both complete the same amount of rolling. However, the rolling movement of the balls is imposed by the bowls interacting with the outer part of the balls, i.e. the part of the balls furthest away from the tube. Whereas the rolling movement of the rollers is imposed by the central body interacting with the shaft of the rollers. The required rotational speed of the central body is halved as compared to the bowls.
[0021] The outer body and the central body may preferably have lubrication channels configured to lubricate the plurality of rollers.
[0022] The central body and the rollers define a forming chamber in which the tube is formed to receive the inner grooves. In one embodiment, the lubrication channels of the outer body and the central body can lead directly into the forming chamber. In another embodiment, the lubrication channels of the outer body and the central body can lead into the forming chamber via the mounting points.
[0023] The rollers may comprise one or more lubrication channels. The lubrication channels of the rollers are preferably configured to connect with the lubrication channels of the central body. To connect with the lubrication channels from the central body, the lubrication channels of the rollers may be arranged in the shafts. The lubrication channels of the rollers can have an axial inlet and one or more radial outlets.
[0024] The lubrication channels form a path from the outside of the grooving tool through the outer body, the central body, optionally through the rollers, into the forming chamber, and out via outlets or along the tube.
[0025] The lubrication channels provide lubrication to the rollers and the tube. As such, wear and temperature can be reduced during operation. This enables the system to operate at higher rotational speeds.
[0026] Each roller has two end portions and one of the end portions has a frustoconical shape which in use taper in an opposite direction to the tube direction. The rollers are in this way configured to receive the tube. The other end portion may preferably also have a frustoconical shape, wherein the two end portions taper in opposite directions. The two end portions can be identical in shape or at least have the same tapering angle. The tapering angle is typically less than 30 degrees and typically more than 3 degrees, preferably 10 - 20 degrees, e.g. 13 - 15 degrees.
[0027] Final dimensions of the produced tube will typically have the following approximate dimensions: 5 - 10 mm outer diameter; 0.4 - 1.0 mm wall thickness; 0.1 - 0.4 mm groove depth; and 15° - 60° helix angle of the groove pattern.
[0028] The wall thickness of the tube is typically 0.4 - 1.0 mm. However, the wall thickness may be up to 3.0 mm.
[0029] The groove depth of the tube is typically 0.1 - 0.4 mm. However, the groove depth may be up to 1.0 mm.
[0030] Each roller preferably has a straight portion on the outer surface which in use is arranged parallel to the tube direction. The straight portion, i.e. flat portion, typically has a length that is 15 - 80 % of the tube diameter.The rollers are spaced apart in a rolling plane arranged orthogonal to the tube direction. The rollers are preferably equally spaced apart. The rollers are arranged adjacent each other and preferably arranged to cover a full circumference, i.e. with a minimum spacing between the rollers. The arrangement of the rollers will depend on the tube diameter and the size and number of rollers. It will typically be preferred to have the same number of rollers regardless of the tube diameter. To accommodate this, the size of the rollers can be increased as the tube diameter increases.
[0031] The plurality of rollers is typically 4-8 rollers, preferably 5-7 rollers, and more preferred 6 rollers. The central body (or at least a part of the central body) and the rollers can be configured as a replaceable package. The packages can easily be replaced if a different roller configuration is required because of a change in tube diameter. The package can also be replaced because of maintenance.
[0032] The system may comprise a plurality of replaceable packages, wherein each replaceable package has a number of rollers, and the number of rollers vary between the replaceable packages. Additionally, or alternatively, the rollers of the same replaceable package may have an equal roller size and the roller size vary between the replaceable packages.
[0033] The grooved mandrel typically has grooves oriented at an angle of 15° - 60° relative the tube direction.
[0034] The grooved mandrel typically has grooves with a height of 0.1 - 0.4 mm. However, the groove height may be larger, e.g. up to 1.0 mm.
[0035] The grooved mandrel typically has a diameter of 4.0 - 10.0 mm. However, the grooved mandrel may be larger, e.g. up to 17 mm.
[0036] The third diameter of the tube is typically 4.5 - 11.0 mm. However, the diameter may be larger, e.g. up to 20 mm.
[0037] The grooved mandrel is a self-rotating.
[0038] The system may comprise: a finishing die, a straightener, a tube speed measurer, a tube temperature sensor, a coil, and / or an annealing device.
[0039] The present disclosure also relates to a method for manufacturing of helical inner grooved aluminium alloy tubes using the system as described herein.
[0040] The method comprises the steps of: extruding a tube having a first diameter, drawing the tube to a second diameter, and grooving the tube to obtain inner helical grooves and a third diameter.
[0041] The method may comprise the steps of: drawing the tube to obtain a smooth outer surface and a fourth diameter, coiling the tube on a coil, and / or heat treating the tube by means of diffusion annealing.
[0042] BRIEF DESCRIPTION OF DRAWINGS
[0043] Following drawings are appended to facilitate the understanding of the invention. The drawings show embodiments of the invention, which will now be described by way of example only, where:
[0044] Fig. 1 is a diagram of a tube grooving process;Fig. 2 is a diagram of a tube grooving system;
[0045] Fig. 3 is a cross-sectional view of a prior art grooving device;
[0046] Fig. 4 is a cross-sectional view of a grooving device according to the invention;
[0047] Fig. 5 is a cross-sectional view of a detail of the grooving device in Fig. 4;
[0048] Fig. 6 is a perspective view of a roller of the grooving device in Fig. 4; and
[0049] Fig. 7 is the same cross-sectional view as Fig. 4 indicating a replaceable package.
[0050] DETAILED DESCRIPTION
[0051] In the following, embodiments of the invention will be discussed in more detail with reference to the appended drawings. It should be understood, however, that the drawings are not intended to limit the invention to the subject-matter depicted in the drawings.
[0052] Fig. 1 illustrates a grooving process and some steps typically involved in such processes.
[0053] 1. The first step SI is casting of an aluminium alloy billet, e.g. a 1050 alloy which has good corrosion resistance and high thermal conductivity. The billets are well suited for storage and shipping.
[0054] 2. The billet is extruded to a base tube in step S2. The base tube will have a smooth inner surface and a diameter that is larger than the final product. The base tube may have a standardized size. After extrusion, the base tube may be stored on a coil before the cold drawing process.
[0055] 3. In step S3 the base tube is drawn through a die to reduce the diameter of the tube to a required size before grooving, i.e. to fit the grooving device. At the same time, the tube will obtain the strength required for the grooving process.
[0056] 4. In step S4, grooving is performed, e.g. with a grooving device according to the present invention, to provide helical inner grooves on the tube.
[0057] 5. After grooving, the tube may optionally be drawn to a final size in step S5. The final size must then be smaller than the size obtained during the grooving of step S4. This may typically be done to smoothen out the outer surface of the tube after grooving.
[0058] 6. The finished tube is coiled in step S6, as a means of storing and transporting the tube. The tube can be cut to lengths based on customer requirements.
[0059] 7. Each coil is diffusion annealed in step S7.
[0060] Fig. 2 illustrates a system 1 for manufacturing of helical inner grooved aluminium alloy tubes and some devices typically involved in such systems. The system 1 of Fig. 2 can be used to perform the method of Fig. 1.
[0061] The system 1 in Fig. 2 comprises a coil 500, a straightener 600, a drawing die 100, a grooving device 200, a finishing die 300, a continuous drawing machine 400, and a coil 500. Additionally, the system 1 may typically comprise a dancer, a speed measurer, a lubricant cleaner, and a temperature sensor. Fig. 3 illustrates a cross-sectional view of a prior art grooving device 200'. This prior art grooving device 200' can be used in a system 1 as illustrated in Fig. 2. In Fig. 3, the prior art grooving device 200' is illustrated in-line with a drawing die 100 arranged upstream and a finishing die 300 arranged downstream.The tube 7 is drawn through the system 1 in a tube direction TD, typically by means of a continuous drawing machine 400, also referred to as a drawing block (not included in Fig. 3).
[0062] Before entering the drawing die 100, the tube Thas a first diameter 01. This may be the unprocessed base tube. The drawing die 100 reduces the diameter of the tube 7 to prepare it for the grooving process. Thus, the tube exits the drawing die 100 with a second diameter 02 that is smaller than the first diameter 01. As part of the grooving process taking place in the prior art grooving device 200', the tube diameter is further reduced to a third diameter 03 which is smaller than the second diameter 02. Optionally, a finishing die 300 can be used after the prior art grooving device 200'. The finishing die 300 will reduce the tube diameter to a fourth diameter 04 which is smaller than the third diameter 03. The finishing die 300 can be used to smoothen the outer surface of the tube 7 after the grooving process.
[0063] The prior art grooving device 200' comprises:
[0064] A grooved mandrel 201 for making inner grooves TIG on an inner surface of the tube 7. A floating plug 202 configured to be held in place by the drawing die 100.
[0065] A tie rod 203 connecting the grooved mandrel 201 and the floating plug 202, such that the grooved mandrel 201 is held in place and allowed to rotate around.
[0066] A plurality of balls 204 configured to be rolled around the tube 7 to press the tube 7 against the grooved mandrel 201.
[0067] A set of bowls 205 configured to hold the balls 204 in place. By rotating the bowls 205 in a direction of rotation R, typically by means of a motor, the balls 204 are also rotated. As the balls 204 compress the tube 7 and tube material is forced against the grooved mandrel 201, the grooved mandrel 201 is also rotated.
[0068] During the grooving process, the tube 7 is moved in the tube direction 7Dat a line speed while the balls 204 are moved in the direction of rotation R at a rotational speed. The line speed and the rotational speed must be adjusted such that the balls 204 press as much as possible of the tube 7 against the grooved mandrel 201. If the line speed is to high relative to the rotational speed, some parts of the tube 7 will not be properly rolled by the balls 204. This will result in inner grooves TIG of inferior quality and an uneven diameter of the tube 7.
[0069] Since the line speed is limited by the maximum rotational speed, the production rate is also limited by the maximum rotational speed. Prior art grooving devices 200' using balls 204 and bowls 205 typically have a maximum rotational speed of 19.000 rpm.
[0070] Fig. 4 illustrates a cross-sectional view of a grooving device 200 according to the invention. This grooving device 200 is configured to be used in a system 1 as described above, replacing the prior art grooving device 200'. Like the prior art grooving device 200', the present grooving device 200 comprises:
[0071] A grooved mandrel 201 configured to be arranged inside the tube Tand provide inner grooves TIG on an inner surface of the tube 7.
[0072] A floating plug 202 configured to be held in place at a transition inside the tube 7 between the first diameter 01 and the second diameter 02, i.e. be held in place by the drawing die 100. A tie rod 203 connected between the grooved mandrel 201 and the floating plug 202 such that the grooved mandrel 201 is held in place and allowed to rotate freely around its own axis at a position where the diameter of the tube 7 is reduced to the third diameter 03.In Fig. 4, the floating plug 202, the tie rod 203, and the drawing die 100 are not illustrated. However, these can be similar to those illustrated in Fig. 3.
[0073] Instead of balls 204, the present grooving device 200 comprises a plurality of rollers 206. The rollers have smooth outer surfaces and are configured to be rolled around the tube T. Just like the balls 204, the rollers 206 reduce the diameter of the tube T from the second diameter 02 to the third diameter 03 such that the tube 7” is forced against the grooved mandrel 201 and is plastically deformed to obtain inner grooves TIG- The grooving device 200 may also comprise:
[0074] A static outer body 208.
[0075] A central body 209 rotatably arranged in the static outer body 208 and configured to hold the plurality of rollers 206 and to receive the tube T. The tube T enters the central body 209 on a tube inlet side 213 and exits the central body 209 on a tube outlet side 214 (in Fig. 4 the tube direction TDis from right to left, not left to right as in Fig. 3).
[0076] A motor configured to rotate the central body 209. The central body 209 may have a flange 210 configured for connection to the motor.
[0077] When the tube T is moved in the tube direction TD(by the continuous drawing machine 400) and the rollers 206 are rotated in a direction of rotation R around the tube T (by the central body 209), the grooved mandrel 201 is also rotated (by the tube material being pressed into its helical grooves). Lubrication channels 211 may preferably be provided in the outer body 208 and the central body 209 to lubricate the rollers 206. Lubrication will reduce friction and temperature increase. The lubrication channels 211 have an interface on the outside of the outer body 208 in the form of a port / nipple 217 or similar. In the transition between the outer body 208 and the central body 209, the lubrication channels 211 should be sealed with dynamic sealing 216 that can withstand the required sliding contact speed.
[0078] Bearings 215 are preferably arranged in the outer body 208 as illustrated to allow the central body 209 to rotate freely relative the outer body 208.
[0079] Fig. 5 illustrates a cross-sectional view of a detail of the grooving device 200 of Fig. 4, in particular the arrangement of the rollers 206 in the central body 209. The central body 209 has mounting points 207 for the rollers 206. The mounting points 207 are configured to hold the rollers 206 in place and allow them to rotate around their own axis. The rollers 206 may be arranged on a shaft or have integrated shafts 206d configured to be arranged in the mounting points 207. The shaft 206d and the mounting points 207 are typically cylindrical.
[0080] The central body 209 can be an assembly of parts. In the example in Fig. 4, the central body 209 comprises four parts. The rollers 206 will typically be assembled with the central body 209.
[0081] The lubrication channels 211 can be arranged to lubricate the interface between the shafts 206d and the mounting points 207. In this way, heat and wear can be reduced. The rollers 206 may also have lubrication channels 206e to further distribute the lubricant supplied via the central body 209. As an example, the lubrication channels 206e of the rollers 206 may have an axial portion configured to communicated with the lubrication channel 211 of the central body 209, and one or more radial portion(s) configured to spread the lubricant across the mounting point 207 and shaft 206d. When the rollers 206 rotate, the lubricant will be evenly distributed by the lubrication channel(s) 211.The lubrication channels 211 are arranged to lubricate the interface between the rollers 206 and the tube T. In this way, heat and wear can be reduced. The lubrication channels 211 can provide lubrication directly to the part of the rollers 206 that are configured to be in contact with the tube T, or indirectly via the mounting points 207, e.g. as described above.
[0082] The lubricant can be any suitable type available to the skilled person.
[0083] The rollers 206 are configured to receive the tube T with an appropriate diameter, in this example the second diameter 02. When the tube T meets the rollers 206, the rollers 206 will start to press the tube T against the grooved mandrel 201 and the tube material will plastically flow into the grooves of the grooved mandrel 201. Thus, as illustrated in Fig. 5, the tube T enters the grooving device 200 with the second diameter 02 and a smooth inner surface and exits the grooving device 200 with the third diameter 03 and inner helical grooves TIG- The geometry of the inner helical grooves TIG made inside the tube T are determined by the grooves of the grooved mandrel 201. The grooved mandrel 201 will typically have grooves oriented at an angle of 15° - 60° relative the tube direction TD. Thus, the inner grooves TIG will correspondingly be helical and oriented at an angle of 15° - 60° relative the tube direction TD.
[0084] The grooved mandrel 201 will typically have grooves with a height of 0.1 - 0.4 mm. Thus, the inner grooves TIG will correspondingly have a height of 0.1 - 0.4 mm.
[0085] The grooved mandrel 201 will typically have a diameter of 4.0 - 10.0 mm. Thus, the tube T will correspondingly have an inner diameter of 4.0 - 10.0 mm (not taking the grooves into account) after grooving. The outer diameter of the tube T after grooving (the third diameter 03 in this example) is typically 4.5 - 11.0 mm.
[0086] Fig. 6 illustrates a perspective view of a roller 206. The exemplified roller 206 is the same as the roller in Fig. 5. This roller 206 has two shafts 206d, both with respective lubrication channels 206e.
[0087] Between the shafts 206d, the roller 206 has a shaping area comprising a straight portion 206c. In use, the outer surface is arranged parallel to the tube direction TD. On opposite sides of the straight portion 206c the shaping area comprises two end portions 206a, 206b. The first end portion 206a that is configured to receive the tube Thas a frustoconical shape which in use taper in the opposite direction of the tube direction TD. As such, the tube T will meet the end portion 206a and be applied a radial force until it reaches the straight portion 206c. The second end portion 206b can preferably also have a frustoconical shape tapering in the same direction as the tube direction TD.
[0088] The amount of tapering on the first end portion 206a corresponds at least to the required radial deformation of the tube T during grooving, preferably more. The amount of tapering on the second end portion 206b does not have to be identical to the tapering of the first end portion 206a.
[0089] The number of rollers 206 in the exemplified grooving device 200 is six. However, a different number of rollers 206 can be used, e.g. 4-8 or 5-7 rollers 206. The rollers 206 are spaced apart in a circular pattern in the central body 209, and preferably arranged as close together as possible without interfering with each other. When seen in a cross-section that is orthogonal to the tube direction TD(also referred to as a rolling plane), points on the straight portions 206c of the rollers 206 will define a circle that corresponds to the diameter of the tube T after grooving.
[0090] The number of rollers 206 and their size will depend on the diameter of the tube before and after the grooving process. The rollers 206 of the same grooving device 200 will typically have the same size.Fig. 7 illustrates the same cross-section of the grooving device 200 as Fig. 4. In Fig. 7 a square indicates how a part of the central body 209 and the rollers 206 can be configured as a replaceable package 212. The replaceable package 212 can be disassembled from the system 1 (such as the outer body 208 and motor) for maintenance. In this way the system 1 may comprise a plurality of interchangeable replaceable packages 212. One advantage of having several replaceable packages is reduced downtime as the system can run on a second replaceable package 212 while the first replaceable package is being maintenance. Such maintenance will typically involve inspection and replacement / repair of components if needed.
[0091] Additionally, the system 1 may comprise replaceable packages 212 with different configurations. As an example, at least some of the replaceable packages 212 may have a different number of rollers 206. The replaceable packages 212 with different numbers of rollers 206 will typically have rollers 206 of different sizes. However, replaceable packages 212 with the same number of rollers 206 can also have rollers 206 of different sizes. The system 1 can then change the replaceable package 212 according to the requirements of the tube Tto be grooved. One advantage of the replaceable packages 212 with different configurations is that different tubes T can be produced with one system 1.
[0092] LIST OF REFERENCE NUMBERS
[0093] 1 System
[0094] 100 Drawing die
[0095] 200' Grooving device (prior art)
[0096] 200 Grooving device
[0097] 201 Grooved mandrel
[0098] 202 Floating plug
[0099] 203 Tie rod
[0100] 204 Ball
[0101] 205 Bowl
[0102] 206 Roller
[0103] 206a, 206b End portion, of roller
[0104] 206c Straight portion, of roller
[0105] 206d Shaft, of roller
[0106] 206e Lubrication channel, of roller
[0107] 207 Mounting point, of central body
[0108] 208 Outer body
[0109] 209 Central body
[0110] 210 Flange, for motor connection211 Lubrication channel
[0111] 212 Replaceable package
[0112] 213 Tube inlet side, of grooving device (bearing side) 214 Tube outlet side, of grooving device
[0113] 215 Bearing
[0114] 216 Dynamic sealing
[0115] 217 Port / nipple
[0116] 300 Finishing die
[0117] 400 Continuous drawing machine
[0118] 500 Coil
[0119] 600 Straightener
[0120] T Tube
[0121] TIG Inner (helical) grooves
[0122] TD Tube direction
[0123] R Direction of rotation
[0124] 01 First diameter
[0125] 02 Second diameter
[0126] 03 Third diameter
[0127] 04 Fourth diameter
Claims
CLAIMS1. A system (1) for manufacturing of helical inner grooved aluminium alloy tubes (T), wherein the system (1) comprises:- a continuous drawing machine (400) for moving a tube (T) in a tube direction (TD) through the system (1),- a drawing die (100) configured to reduce a diameter of the tube (1) from a first diameter (01) to a second diameter (02), and- a grooving device (200) arranged downstream the drawing die (100) and configured to provide inner grooves (TIG) in the tube (T) and simultaneously reduce the diameter of the tube (T) from the second diameter (02) to a third diameter (03),wherein the grooving device (200) comprises:- a grooved mandrel (201) configured to be arranged inside the tube (T) and provide inner grooves (TG) in the tube (T),- a floating plug (202) configured to be held in place at a transition inside the tube (T) between the first diameter (01) and the second diameter (02),- a tie rod (203) connected between the grooved mandrel (201) and the floating plug (202) such that the grooved mandrel (201) is held in place and allowed to rotate freely at a position where the diameter of the tube (T) is reduced to the third diameter (03), and- a plurality of rollers (206) configured to be rolled around the tube (T) to reduce the diameter of the tube (T) from the second diameter (02) to the third diameter (03) such that the tube (T) is forced against the grooved mandrel (201) and plastically deformed to obtain inner grooves (TIG), wherein each roller (206) has a smooth outer surface.
2. The system (1) according to claim 1, wherein the grooving device (200) comprises:- a static outer body (208),- a central body (209) rotatably arranged in the static outer body (208) and configured to receive the tube (T), andwherein the plurality of rollers (206) is arranged in respective mounting points (207) in the central body (209).
3. The system (1) according to any one of the preceding claims, wherein the grooving device (200) comprises:- a motor configured to rotate the central body (209).
4. The system (1) according to any one of the preceding claims, wherein the outer body (208) and the central body (209) has lubrication channels (211) configured to lubricate the plurality of rollers (206).
5. The system (1) according to any one of the preceding claims,wherein each roller (206) has two end portions (206a, 206b) and one of the end portions (206a) has a frustoconical shape which in use taper in an opposite direction to the tube direction (TD).
6. The system (1) according to any one of the preceding claims,wherein each roller (206) has a straight portion (206c) on the outer surface which in use is arranged parallel to the tube direction (TD).
7. The system (1) according to any one of the preceding claims,wherein the rollers (206) are spaced apart in a rolling plane arranged orthogonal to the tube direction (TD).
8. The system (1) according to any one of the preceding claims,wherein the plurality of rollers (206) is 4-8 rollers (206), preferably 5-7 rollers (206), and more preferred 6 rollers (206).
9. The system (1) according to any one of the preceding claims,wherein the central body (209) and the rollers (206) are configured as a replaceable package (212).
10. The system (1) according to claim 9,wherein the system (1) comprises a plurality of replaceable packages (212), andeach replaceable package (212) has a number of rollers (206) and the number of rollers (206) vary between the replaceable packages (212), and / orthe rollers (206) of the same replaceable package (212) have an equal roller size and the roller size vary between the replaceable packages (212).
11. The system (1) according to any one of the preceding claims,wherein the grooved mandrel (201) has grooves oriented at an angle of 15° - 60° relative the tube direction (TD).
12. The system (1) according to any one of the preceding claims,wherein the grooved mandrel (201) has grooves with a height of 0.1 - 0.4 mm.
13. The system (1) according to any one of the preceding claims,wherein the grooved mandrel (201) has a diameter of 4.0 - 10.0 mm.
14. The system (1) according to any one of the preceding claims,wherein the third diameter (03) of the tube (T) is 4.5 - 11.0 mm.
15. The system (1) according to any one of the preceding claims,wherein the system (1) comprises: a finishing die (300), a straightener (600), a tube speed measurer, a tube temperature sensor, a coil (500), and / or an annealing device.
16. A method for manufacturing of helical inner grooved aluminium alloy tubes (T) using the system (1) according to anyone of the preceding claims, wherein the method comprises the steps of:- extruding a tube (T) having a first diameter (01),- drawing the tube (T) to a second diameter (02), and- grooving the tube (T) to obtain inner helical grooves and a third diameter (03).
17. The method according to claim 16, wherein the method comprises the steps of:- drawing the tube (T) to obtain a smooth outer surface and a fourth diameter (04),- coiling the tube (T) on a coil (500), and / or- heat treating the tube (T) by means of diffusion annealing.