embossing roll

Abstract

An embossing roller (1) having a cylindrical surface (2) comprising a central portion (3) having an embossing pattern (10) and side portions (4a, 4b) arranged on each side of the central portion without embossing pattern, wherein a circumferential buffer channel (5) is provided on each side of the central portion (3) between the central portion and the side portions along the cylindrical surface (2) of the embossing roller.

Description

Technical Field

[0001] This disclosure relates to an embossing roller suitable for embossing metal strips used in the manufacture of rolled and welded tubes. Background Technology

[0002] Welded pipes and tubes are typically manufactured by longitudinally forming a flat metal strip into a nearly complete tube and then welding the two edges together. Roll-formed tubes have numerous applications, including in the HVAC & R market (heating, ventilation, air conditioning, and refrigeration). Within this technological field, environmental demands have driven the development towards air conditioning and refrigeration equipment with improved efficiency. In response, efforts have been made to provide smaller diameter tubes with a variety of internal surface reinforcements, capable of increasing their heat transfer coefficients, relative to standard, streamlined solutions. Methods for manufacturing advanced products, such as small-diameter welded tubes with internal surface patterns for heat exchange applications, must minimize undesirable internal irregularities to achieve optimal flow characteristics and heat transfer. With increasing demands for cost reduction, there has been a desire to provide alternatives to copper tubes in the form of aluminum tubes, which have traditionally dominated the use of air conditioning and refrigeration equipment. Therefore, a method for manufacturing aluminum tubes with properties competitive for applications such as those in the HVAC & R field is desired. Summary of the Invention

[0003] This disclosure relates to an embossing roller by means of which metal strip can be preformed to facilitate welding and produce a final tube product with improved weld quality. The embossing roller of this disclosure has a cylindrical surface comprising a central portion having an embossed pattern and side portions disposed on each side of the central portion. The side portions have no embossed pattern, and circumferential buffer channels are provided on each side of the central portion, between the central portion and the side portions, along the cylindrical surface of the embossing roller. The buffer channels are configured to accommodate material laterally displaced due to the imprinting of the embossed pattern, thereby producing a preformed strip with an embossed surface pattern and improved straightness at the outer longitudinal edges.

[0004] The embossing pattern on the central portion of the embossing roller preferably comprises a plurality of elongated grooves, which have a certain depth and are arranged at an angle relative to the rotation direction of the embossing roller. The groove depth of the embossing pattern is preferably less than 0.35 mm.

[0005] The central portion of the embossing roller can be composed of a central embossing pattern roller assembly, and the side portions can be composed of side rollers. The side rollers are then arranged on each side of the central embossing pattern roller assembly, with the central embossing pattern roller assembly having a cylindrical surface forming the central portion of the embossing roller, and the side rollers having cylindrical surfaces forming the side portions of the embossing roller. This provides flexibility regarding the embossing pattern. The cylindrical surfaces of the central embossing pattern roller assembly and the side rollers can have beveled edges at the interface between them, such that a circumferential buffer channel is formed at the interface by the beveled edges of the central embossing pattern roller assembly and the side rollers, allowing for a convenient buffer channel.

[0006] Advantageously, the depth of the circumferential buffer channel formed by the beveled edges of the central embossing roller group and the side rollers is less than the depth of the embossing groove, preferably 50-70% of the depth of the embossing groove. Therefore, the buffer channel can accommodate displaced material without adversely affecting the flow characteristics of the finished tube product.

[0007] The cylindrical surface of the embossing roller may suitably have a total width of 15 mm or greater, and the central portion may have a width of 85-99% of the total width to suitably allow preforming of strips for manufacturing heat exchanger tubes for HVAC & R applications.

[0008] The central portion of the embossing roller may include an embossing pattern roller assembly comprising one or more embossing pattern discs having cylindrical embossing surfaces with identical or different embossing patterns disposed thereon, allowing flexibility in the selection of embossing patterns. The embossing pattern roller assembly may also include smooth spacer rings located between each embossing pattern disc, the cylindrical surface of each spacer ring being flush with the cylindrical surface of the central portion between grooves. This allows for further flexibility in the embossing patterns.

[0009] The embossed patterned disc and the optionally included smooth spacer ring preferably have beveled edges at the interface between them. This minimizes localized stress in the material and thus reduces the risk of tool breakage.

[0010] The embossing pattern on the central portion of the embossing roller preferably includes a plurality of grooves arranged in the cylindrical surface of the central portion, and the cylindrical surface of each side portion is appropriately flush with the cylindrical surface of the central portion between the grooves in order to facilitate the subsequent welding process. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the preforming device; Figure 2 This is an exploded perspective view of an example of an embossing roller according to this disclosure; Figure 3a yes Figure 2 A cross-sectional view of the embossing roller; Figure 3b yes Figure 3a The cross-sectional view with circled details shown; Figure 3c yes Figure 3b The cross-sectional view with circled details shown; Figure 4 Details of an embossing roller according to an example of this disclosure are shown schematically; Figure 5 Details of an embossing roller according to another example of this disclosure are shown schematically; Figure 6 A partial cross-sectional view of a tube with an internal embossed pattern is shown; Figure 7 The edge of a strip that has been pre-formed by an embossing roller according to this disclosure is shown schematically. Detailed Implementation

[0012] This disclosure relates to an embossing roller used in a tool for preforming metal strip for use in manufacturing tubes. The embossing roller has a cylindrical surface comprising a central portion having an embossed pattern and side portions arranged on each side of the central portion. The side portions do not have an embossed pattern. On each side of the central portion, a circumferential buffer channel is provided between the central portion and the side portions along the cylindrical surface of the embossing roller. With the aid of the embossing roller of the present invention, metal strip can be preformed to facilitate welding and produce a final tube product with improved weld quality.

[0013] The final product may suitably be an advanced small-diameter tube product made of aluminum or its alloys, with a diameter of 20 mm or less, preferably 5-10 mm. The tube product is preferably manufactured as a continuous tube coil with a length of more than 500 m, preferably more than 1000 m, and such tube products are used, for example, in the fields of heating, ventilation, air conditioning or refrigeration.

[0014] The process of roll forming a welded tube involves rolling a pre-formed strip into a tubular shape and welding the longitudinal edges of the strip together by means of high-frequency welding in an induction-heated welded coil to obtain a tube. To achieve this, the strip is fed into a forming mill or apparatus that shapes the strip through different successive forming steps performed by as many forming rolls as possible. As the strip passes through the welded coil, an electromagnetic field is induced around the coil, inducing a current flowing through the strip, primarily concentrated at the edges to be joined. The metal's resistance to the current at these edges generates the necessary heat development, causing the edges to rapidly reach their melting point. While the edges are still molten, they are forged together by interaction with side extrusion rolls, which apply force to the strip and thus generate the required pressure at the interface of the two edges. As the weld passes through the welding rolls, the oxidized and molten metals are extruded together, and a clean lower layer of metal is bonded. After welding, the process is finished with a sizing roll to give the tube the desired final geometry.

[0015] The production of advanced tubular products from metal strip, such as small-diameter welded tubes with internal surface patterns for heat exchange applications, comprises a two-stage process, including a stage of preforming the strip and a stage of rolling the strip into a tubular shape and welding it into a tube.

[0016] In the manufacture of tubes made from aluminum strip through rolling and welding, it is important to mitigate problems that may arise due to the properties of aluminum. To achieve the desired heat transfer performance, the tubes have an internal embossed surface pattern. Preferably, variations in strip width should be kept to a minimum to improve stability during the welding process and the quality of the finished tube product.

[0017] The strip is typically supplied in the form of a preform strip coil, where it is prepared for tube forming and welding in the next stage. The preform stage includes the steps of embossing the strip on the surface of the interior of the tube to be formed, creating an embossed pattern for the internal grooves of the tube. After the preform stage, the strip can be appropriately stored in coil form until it is rolled and welded into a tube.

[0018] The embossing process is performed in an embossing station, which includes a cold deformation process performed on the strip to obtain a surface pattern. The embossing pattern on the central portion of the embossing roller preferably comprises multiple elongated grooves of a certain depth, arranged at an angle relative to the rotation direction of the embossing roller. The groove depth of the embossing roller pattern is preferably less than 0.35 mm. Various embossing patterns can be applied; for example, spiral patterns improve performance in evaporation applications, and herringbone patterns improve performance in condensation applications.

[0019] The cold roll forming process involves applying a desired pattern to the surface of a strip by embossing, in which a blank strip is fed into a roll system comprising an embossing roll and a support roll to apply the necessary forming pressure. The embossing roll has a cylindrical surface comprising a central portion with an embossed pattern and side portions arranged on each side of the central portion. The side portions do not have an embossed pattern. The central portion of the embossing roll is provided with a negative image of the desired strip pattern and is pressed against the strip supported by the support rolls, thereby cold roll forming and embossing the strip. The embossed pattern on the embossing roll results in a corresponding embossed pattern being imprinted on the strip surface, wherein the grooves of the embossing roll pattern correspond to protruding fins on the strip, thus creating a fin pattern on the strip surface. The maximum fin height corresponds to the groove depth of the embossing roll pattern.

[0020] Before feeding the strip to the embossing station, the strip is properly unwound at a controlled speed, and after the embossing step, it is properly rewound. The support rollers can be fixed in a horizontal position, while the embossing rollers can have the freedom to adjust in the vertical direction, thereby changing the gap between the rollers and thus allowing for adjustment and optimal distribution of forming pressure on the strip.

[0021] The central portion of the embossing roller can be composed of a central embossing pattern roller assembly, and the side portions can be composed of side rollers arranged on each side of the central embossing pattern roller assembly. The central embossing pattern roller assembly has a cylindrical surface forming the central portion of the embossing roller, and the side rollers have cylindrical surfaces forming the side portions of the embossing roller. This provides flexibility regarding the embossing pattern. Alternatively, the embossing roller can be integrally molded.

[0022] The central embossing pattern roller assembly can consist of a single embossing pattern disc, or two or more embossing pattern discs with or without spacer discs between them. The embossing pattern discs and optionally included smooth spacer rings preferably have beveled edges at their interfaces, such that circumferential channels are formed at said interfaces through the beveled edges. This minimizes localized stress in the material and thus reduces the risk of tool breakage.

[0023] The central embossing roller assembly is responsible for pattern formation, while the side rollers are used to provide unpatterned side portions on the strip by pressing on the outer sides, as described below. The two side rollers can be bolted to the central embossing ring, which can be clamped to the central shaft and fixed in place in the embossing station.

[0024] As mentioned, the side portions of the embossing rolls do not have an embossing pattern. Therefore, the outer portion of the strip formed and embossed by the cold rolls does not exhibit any embossing pattern, but instead has a smooth surface. By providing these unpatterned side portions along the length of the strip during the preforming stage, the risk of strip edge thickness variations can be minimized, the risk of uneven geometry at the strip edge present at weld points can be reduced, and the risk of embossed fins being welded together, resulting in large internal weld seams, can be avoided. Therefore, providing unpatterned side portions on the embossed strip allows for optimal control over the strip edge geometry, which is necessary to ensure optimal welding conditions, improve process stability, and enhance post-weld tube quality.

[0025] The cylindrical surface of the embossing roller may suitably have a total width of 15 mm or greater, with the central portion having 85-99% of the total width. A strip width of 15 mm or greater is suitable for manufacturing heat exchanger tubes for HVAC & R applications.

[0026] The width of the unpatterned side portions is determined based on considerations related to weldability and the heat transfer performance of the finished tube. Wider unpatterned side portions will be easier to weld, as this will be closer to the standard process for welding smooth strip. However, excessively wide unpatterned side portions may adversely affect the final heat transfer performance, since ideally, a continuous pattern around the entire inner circumference of the tube would be desirable. Therefore, the width of the unpatterned side portions should preferably be as small as possible, while still ensuring that embossed fins are not included in the internal weld. It has been found that when the strip has a total width of 15 mm or greater, the combined width of the two unpatterned side portions should preferably be 1-15% of the total strip width.

[0027] The cylindrical surface of the side portion of the embossing roller is preferably flush with the cylindrical surface of the central portion between the grooves in the embossing roller pattern. This ensures that the thickness of the internal weld height on the finished welded tube is kept to a minimum. Therefore, during the embossing stage, the strip in the unpatterned side portion is preferably rolled to the nominal bottom wall thickness of the tube, i.e., flush with the bottom of the grooves between the fins in the embossed surface pattern. Thus, the side portion remains smooth but is still rolled to a thickness less than the original thickness of the billet. This improves the performance of the final tube because the internal weld height can be reduced, resulting in less disturbance to the hydrodynamics within the final tube.

[0028] By selecting the outer diameter of the embossing roller at the side portion to be the same as the outer diameter of the embossing roller at the center portion, the desired thickness of the unpatterned side portion can be obtained.

[0029] As mentioned, circumferential buffer channels are advantageously disposed on the embossing rolls on each side of the central portion, between the central and side portions, along the cylindrical surface of the embossing rolls. The buffer channels are configured to accommodate material that has laterally shifted due to the imprinting of the embossing pattern during cold rolling and embossing, thus acting as a material displacement buffer during embossing deformation, reducing edge geometry waviness that could otherwise occur due to the irregular geometry of the embossing pattern being imprinted into the surface of the strip by cold deformation. Therefore, the provision of buffer channels results in pre-formed strips with improved straightness at the outer edges.

[0030] The preformed strip of the finished product will typically exhibit small indentations on its surface corresponding to the buffer channels. These small indentations may remain in the finished tube, where they constitute negligible and acceptable defects.

[0031] A buffer channel is a continuous channel (notch) located at the interface between the central and side portions of the embossing roller. The buffer channel can be obtained by engraving the channel into the embossing roller. Preferably, the buffer channel can be obtained by grinding the corner radius to create a beveled edge at the outer edge of the central embossing roller assembly and on the side roller at the edge adjacent to the central embossing roller assembly. Therefore, the cylindrical surfaces of the central embossing roller assembly and the side rollers can have beveled edges at the interface between them, forming a circumferential buffer channel at the interface through the beveled edges of the central embossing roller assembly and the side rollers, allowing for a convenient way to obtain the buffer channel.

[0032] Advantageously, the depth of the circumferential buffer channel formed by the beveled edges of the central embossing pattern roller group and the beveled edges of the side rollers is less than the depth of the embossing pattern groove, preferably 50-70% of the depth of the embossing pattern groove, more preferably 60-65%. Therefore, the buffer channel can accommodate displaced material without adversely affecting the flow characteristics of the finished tube product.

[0033] Furthermore, if desired, the longitudinal side edges of the metal strip on each side of the strip, on the side facing the embossing roller, can be chamfered by passing between subsequent pairs of rollers, such as... Figure 7 As shown in the diagram. This reduces the size of the internal weld seams and thus improves the performance of the finished pipe.

[0034] Description of exemplary embodiments This disclosure will now be described with reference to the accompanying drawings, in which preferred exemplary embodiments of the disclosure are shown. However, this disclosure may be implemented in other forms and should not be construed as limited to the embodiments disclosed herein. The disclosed embodiments are provided to fully convey the scope of this disclosure to those skilled in the art.

[0035] Figure 1This is a schematic diagram of an apparatus 20 for preforming metal strip 40. The apparatus includes an embossing station with an embossing roller 1 and a support 22, and an optional edge forming tool 30 including a pair of rollers 31, 32. The strip 40 travels along the travel direction T through the preforming tool.

[0036] Figure 2 This is an exploded perspective view of an example of an embossing roller according to the present disclosure, and Figure 3a This is a cross-sectional view of the same roller, and Figures 3b-3c Details are shown. The embossing roller 1 has a cylindrical surface 2, which includes a central portion 3 having an embossed pattern 10 and side portions 4a, 4b arranged on each side of the central portion 3. The side portions 4a, 4b do not have an embossed pattern, such as... Figures 3b-3c As shown. Figure 3c As shown, a circumferential buffer channel 5 is disposed between the central portion and the side portions along the cylindrical surface 2 of the embossing roller. Buffer channels 5 are disposed on each side of the central portion 3, the cylindrical surface of the embossing roller has a total width W1, and the central portion has a width W2, which is 85-99% of the total width W1.

[0037] In the example shown, the central portion 3 of the embossing roller 1 is composed of a central embossing pattern roller 6, and the side portions 4a and 4b are composed of side rollers 7a and 7b. The side rollers are arranged on each side of the central embossing roller. The embossing pattern 10 on the central portion of the embossing roller includes a plurality of elongated grooves 11 having a depth D1, and arranged at an angle relative to the rotation direction of the embossing roller. The groove depth D1 of the embossing pattern is preferably less than 0.35 mm. Figure 3c As shown, the cylindrical surfaces of the central embossing pattern roller group 6 and the side rollers 7a and 7b can have beveled edges 8 and 9 at the interface 12 between the central embossing pattern roller group and the side rollers, thereby forming a circumferential buffer channel 5 at the interface through the beveled edges of the central embossing pattern roller group and the side rollers 7a and 7b. Figures 3a-3c As shown, the cylindrical surfaces of the side portions 4a and 4b are flush with the cylindrical surface of the central portion 3 between the grooves.

[0038] The circumferential buffer channel 5 is formed by the beveled edge of the central embossing pattern roller group and the beveled edges of the side rollers 7a and 7b, and has a depth D2, which is less than the depth D1 of the embossing pattern groove 11, preferably 50-70% of the depth D1 of the embossing pattern groove.

[0039] The central embossing roller can be in the form of an embossing pattern roller group, including multiple embossing pattern rollers. Therefore, the central portion 3 of the embossing roller 1 may include an embossing pattern roller group, which includes one or more embossing pattern discs 13a, 13b, each embossing pattern disc having a cylindrical embossing surface with the same or different embossing patterns disposed thereon. Figure 4 Details of an embossing roller assembly including two pattern rollers, a metal strip 40 to be embossed, and a support portion 22 are shown. In this case, the embossing pattern roller assembly includes two embossing pattern discs 13a and 13b, each embossing pattern disc having an embossing pattern consisting of grooves arranged at an angle but having a mirror pattern, which together form a herringbone pattern on the embossed strip. Figure 5 Details of an embossing roller assembly are shown, which includes smooth spacer rings 15 located between embossing pattern discs 13a and 13b. In this case, the cylindrical surface of each spacer ring is flush with the cylindrical surface of the central portion 3 between the grooves. Figure 5 As shown, the embossed pattern discs 13a, 13b and the smooth spacer ring 15 have beveled edges 16, 17 at the interface between them.

[0040] Figure 6 A partial cross-sectional view of a tube 18 with an internally embossed herringbone pattern 19 is shown.

[0041] Figure 7 A cross-section of a portion of a preformed strip, which has been preformed by an embossing roller according to the present disclosure, is shown. The figure illustrates small indentations 45 present at the interface between the unpatterned side portion 42 and the center portion 41, on which an embossed pattern comprising multiple protruding fins 44 (only one fin is shown in this figure) is present. The small indentations 45 are buffer channels provided on the embossing roller. Figure 3c The result of 5) is shown. The fins 44 correspond to the grooves 11 of the embossing pattern 10 on the embossing roller. The figure also shows how the surface of the side portion 42 is flush with the bottom of the grooves formed between the fins 44. Alternatively, the outermost edge of the strip can be as follows: Figure 7 It is beveled as shown in the diagram.

[0042] Those skilled in the art will recognize that this disclosure is not limited to the preferred embodiments described above. They will further recognize that modifications and variations are possible within the scope of the appended claims. Furthermore, those skilled in the art, in practicing the claimed disclosure, can understand and implement variations of the disclosed embodiments by studying the accompanying drawings, the disclosure, and the appended claims.

Claims

1. An embossing roller (1) having a cylindrical surface (2), characterized in that, The cylindrical surface includes a central portion (3) having an embossed pattern (10) and side portions (4a, 4b) without an embossed pattern arranged on each side of the central portion, wherein a circumferential buffer channel (5) is provided along the cylindrical surface (2) of the embossing roller between the central portion and the side portions on each side of the central portion (3), wherein the circumferential buffer channel (5) is configured to accommodate material that is laterally displaced due to the imprinting of the embossed pattern.

2. The embossing roller as described in claim 1, wherein, The embossing pattern (10) on the central portion of the embossing roller includes a plurality of elongated grooves (11), the plurality of elongated grooves having a groove depth (D1) and arranged at an angle relative to the rotation direction of the embossing roller.

3. The embossing roller as described in claim 2, wherein, The central portion (3) of the embossing roller (1) is composed of a central embossing pattern roller group (6), and the side portions (4a, 4b) are composed of side rollers (7a, 7b), the side rollers being arranged on each side of the central embossing pattern roller group, wherein the central embossing pattern roller group has a cylindrical surface forming the central portion (3), and the side rollers have cylindrical surfaces forming the side portions (4a, 4b).

4. The embossing roller as described in claim 3, wherein, The cylindrical surfaces of the central embossed pattern roller group (6) and the side rollers (7a, 7b) have beveled edges (8, 9) at the interface (12) between the central embossed pattern roller group and the side rollers, so that the circumferential buffer channel (5) is formed at the interface by the beveled edges of the central embossed pattern roller group and the side rollers (7a, 7b).

5. The embossing roller as described in claim 4, wherein, The circumferential buffer channel (5) formed by the beveled edge of the central embossing pattern roller group and the beveled edges of the side rollers (7a, 7b) has a channel depth (D2), which is less than the groove depth (D1) of the groove (11).

6. The embossing roller according to any one of claims 1-2 and 4-5, wherein, The cylindrical surface of the embossing roller has a total width (W1) of 15 mm or more, and the central portion has a width (W2) that is 85-99% of the total width (W1).

7. The embossing roller as described in claim 2, wherein, The central portion (3) of the embossing roller (1) includes a central embossing pattern roller group (6), which includes one or more embossing pattern discs (13a, 13b), each embossing pattern disc having a cylindrical embossing surface with the same or different embossing patterns disposed thereon.

8. The embossing roller as described in claim 7, wherein, The central embossing pattern roller group (6) includes two or more embossing pattern discs (13a, 13b) and a smooth spacer ring (15) located between every two adjacent embossing pattern discs (13a, 13b).

9. The embossing roller as described in claim 8, wherein, The embossed pattern discs (13a, 13b) have beveled edges (16, 17) at their interface.

10. The embossing roller as claimed in claim 1, wherein, The embossing pattern (10) on the central portion of the embossing roller includes a plurality of elongated grooves (11) arranged in the cylindrical surface of the central portion (3), wherein the cylindrical surface of each side portion (4a, 4b) is flush with the cylindrical surface of the central portion (3) between the grooves.

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