JP7416804B2 - Apparatus and method for thickening a tube at its edges - Google Patents

Description

The present disclosure relates to the field of manufacturing technology. In particular, but not exclusively, the present disclosure relates to apparatus for forming or thickening tubes. Further embodiments of the present disclosure disclose devices and processes for thickening a tube at its edges.

A tube is a long hollow cylinder made from a material such as metal, plastic, or composite. The tubes can be used in a variety of applications in the domestic, medical, fuel gas distribution, automotive fields, and other applications including air conditioning and cooling. For example, in automotive applications such as two-wheelers, tubes may be used in frames, seating systems, fuel supply components, and link arms of automobiles, where tubes are welded in series to produce an integrated frame. need to be done. Depending on the material of the tube and the dimensions of the tube, the tube can be welded using MIG welding, flux-cored arc welding, TIG welding, stick welding, etc. Welding can be performed using a variety of known welding methods. Welding is the process of joining parts together by heating the surfaces to their melting point. In the process of welding, different zones may be formed such as fusion zone, weld interface, heat affected zone, etc. The fusion zone is the part of the material that exists after the object has been welded. The melt zone begins and ends at the fused portion of material. This zone will have a chemical composition that is a mixture of the substrates being welded together and any additional filler material that may have been used.

A weld boundary is an area consisting of a zone of pure welding. A heat affected zone (HAZ) is a region of the base material that is not melted, but whose microstructure and properties have been altered by welding. The melt zone and HAZ behave like stress raiser zones within the material. Stress concentrators increase the stress concentration factor and further reduce the fatigue behavior of the welded connection. To avoid these stress concentrations, automotive applications can use larger tubes with uniform thickness, or tubes that are thicker only at the free end of the tube. Tubes of larger and more uniform thickness can be used in the above applications, but add unnecessary weight to the overall assembly. The latter approach, ie the use of tubes thickened at the ends, ensures a reduction in the overall weight of the entire assembly, since only the end sections to be welded are thickened.

Conventional processes known in the art for manufacturing tubes with varying thicknesses include flexible rolling, swage auto-frettage process, position controlled mandrel process, etc. extrusion with special mold setup, and internal and external upsetting of the tube ends. The ends of the tube can be thickened using the process described above. The process described above has several limitations such as increased investment in tooling and/or decreased productivity due to increased cycle time.

The present disclosure is directed to overcoming one or more of the above-mentioned limitations.

One or more disadvantages of conventional processes are overcome by the claimed process and additional advantages are provided in the present disclosure by providing the claimed process.

Additional features and advantages are realized by the techniques of this disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.

In one non-limiting embodiment of the present disclosure, an apparatus for thickening a tube at its edges is disclosed. The apparatus includes a first support configured to rigidly support a first longitudinal surface of a tube along the length of the first longitudinal surface excluding one or both ends of the tube. Contains parts. The apparatus includes a second support configured to rigidly support a second longitudinal surface of the tube along the length of the second longitudinal surface excluding one or both ends of the tube. It further includes a member. The device also includes a punch driven by an external power source, the punch being configured to exert a force on one or both ends of the tube. The application of force by the punch plastically deforms the ends of the tube, thereby thickening the tube at one or both ends.

In one embodiment of the present disclosure, the apparatus includes a block driven by a first external power source, and a longitudinal force on the block imparts lateral outward movement on the second support member to further configured to support a second longitudinal surface of the holder.

In one embodiment of the present disclosure, the blocks are wedge-shaped.

In one embodiment of the present disclosure, the first support member includes an outer tube retainer and an outer insert. Additionally, the first support member is driven by a second external power source.

In one embodiment of the present disclosure, the outer tube retainer and the outer insert are joined by at least one of a mechanical bond and a thermal bond.

In one embodiment of the present disclosure, the ends of the outer insert are chamfered such that the ends of the outer insert define part of the mold for plastic deformation of one or both ends of the tube.

In one embodiment of the present disclosure, the second support member includes an inner tube retainer and an inner insert. The inner tube retainer and inner insert are joined by at least one of a mechanical bonding process or a thermal bonding process.

In one embodiment of the present disclosure, one or both ends of the inner insert are chamfered such that the ends define part of the mold for plastic deformation of the end of the main tube.

In one embodiment of the present disclosure, the shape of the inner tube retainer matches the shape of the block.

In one embodiment of the present disclosure, the external power source is a hydraulic drive.

In one embodiment of the present disclosure, the first support member and the second support member are chamfered away from each other at the extreme ends of each side so that they do not contact the edges of the tube.

In one embodiment of the present disclosure, the first longitudinal surface of the tube is the outer surface of the tube and the second longitudinal surface of the tube is the inner surface of the tube.

In another non-limiting embodiment of the present disclosure, a tube is formed using the present apparatus. The tube includes a body portion and a lip portion at one or both ends of the body portion. The edge portions at one or both ends of the body portion are such that the thickness of the edge portion of the tube is greater than the thickness of the body portion of the tube.

In one embodiment of the present disclosure, the body portion of the tube is uniform in thickness.

In one embodiment of the present disclosure, the thickness of the edge portion of the tube may vary uniformly from the thickness of the body portion to 20-30% greater than the thickness of the body portion; It does not have to change to .

In another non-limiting embodiment of the present disclosure, a process for thickening a tube at its edges is disclosed. The process includes supporting, by a first support member, a first longitudinal surface of a tube along the length of the first longitudinal surface excluding one or both ends of the tube; supporting a second longitudinal surface of the tube along the length of the second longitudinal surface, excluding one or both ends of the tube, by means of two support members; compressing one or both ends. The application of force by the punch plastically deforms the ends of the tube and increases the thickness of the tube at one or both ends.

In one embodiment of the present disclosure, the process further includes moving the second support member laterally outwardly to firmly support a central portion of the inner surface of the tube. The blocks used in the process can be wedge-shaped.

In one embodiment of the present disclosure, the first support member, punch, and block are driven by an external hydraulic pressure source.

It should be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Some of the aspects and embodiments may be combined to form further embodiments of the present disclosure.

The above summary is illustrative only and is not intended to be limiting in any way. In addition to the exemplary aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent with reference to the drawings and the detailed description below.

1 is a perspective view of a device used to thicken a tube at its edges, according to one embodiment of the present disclosure; FIG. FIG. 3 is an isometric view of one half of an inner tube retainer assembly according to one embodiment of the present disclosure. FIG. 3 is an isometric view of one half of an outer tube retainer assembly according to one embodiment of the present disclosure. FIG. 3 is a cross-sectional view of a tube held rigidly between a first support member and a second support member for thickening at one or both ends, according to an embodiment of the present disclosure. FIG. 3 is a cross-sectional view of a tube held rigidly between a first support member and a second support member for thickening at one or both ends, according to an embodiment of the present disclosure.

The novel features and characteristics of the disclosure are pointed out in the appended claims. However, the present disclosure itself, as well as preferred modes of use, further objects and advantages thereof, are best understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings. Good morning. One or more embodiments will now be described, by way of example only, with reference to the accompanying figures. In the accompanying figures, like reference numbers represent like elements.

The figures depict embodiments of the disclosure for purposes of illustration only. Those skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be used without departing from the principles of the disclosure described herein. Will.

The foregoing has outlined broadly the features and technical advantages of the present disclosure in order that the detailed description of the disclosure that follows may be better understood. Additional features and advantages of the disclosure are described below which form the subject matter of the claims of the disclosure. Those skilled in the art will recognize that the concepts and specific embodiments disclosed can readily be utilized as a basis for modifications or designs of other structures to accomplish the same objectives of the present disclosure. Those skilled in the art should also realize that such equivalent processes do not depart from the spirit and scope of this disclosure as set forth in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS The novel features believed to be unique to this disclosure, both as to its construction and method of operation, as well as further objects and advantages, will be better understood from the following description when considered in conjunction with the accompanying figures. However, it should be clearly understood that each of the figures is provided for purposes of illustration and explanation only and is not intended as a definition of a limitation of the present disclosure. The aspects of the present disclosure, as generally described herein and illustrated in the figures, may be constructed, substituted, combined, and designed in a wide variety of different forms, all of which may be expressly as will be readily understood to be considered and form part of this disclosure.

Embodiments of the present disclosure disclose an apparatus for thickening a tube, particularly a tube used in automotive parts, at its edges. The apparatus includes a first support configured to rigidly support a first longitudinal surface of a tube along the length of the first longitudinal surface excluding one or both ends of the tube. Contains parts. The first support member may be driven by a second external power source. The apparatus further includes a second support member configured to rigidly support the second longitudinal surface of the tube along the length of the second longitudinal surface excluding the ends of the tube. .

In one embodiment, the device includes a punch driven by an external power source. The punch may be configured to exert a force on either end of the tube. The application of force by the punch plastically deforms the end of the tube, making it thicker at its edges. In one embodiment, the tube can be thickened at one or both ends of the tube. The device also includes a block that can be driven by a first external power source. The block is driven by a first power source that provides a longitudinal force on the block. The longitudinal force on the block is configured to impart lateral outward movement to the second support member. This movement moves the second support member toward the second longitudinal surface so as to firmly support the second longitudinal surface of the tube. Additionally, the first support member includes an outer tube retainer and an outer insert. The outer tube retainer and the insert are joined by at least one of a mechanical bond and a thermal bond. The end of the outer insert can be chamfered such that the end of the outer insert defines part of the mold for plastic deformation of the end of the tube.

Similarly, the second support member also includes an inner tube retainer and an inner insert, the inner tube retainer and the inner insert being joined by a mechanical connection such as nuts and bolts or a thermal connection such as welding. are joined by at least one of the following. The ends of the inner insert are chamfered so that they define part of the mold for plastic deformation of the end of the main tube. The inner tube holder also conforms to the shape of the block, which may be wedge-shaped or any such shape.

A tube formed using this apparatus includes a body portion and a lip portion at one or both ends of the body portion. The edge portions at one or both ends of the body portion are such that the thickness of the edge portion of the tube is greater than the thickness of the body portion of the tube. The body portion of the tube may be of uniform thickness, and the edge portions at either end of the body may have an increased thickness than the thickness of the body portion.

Subsequently, the tube is supported along the first longitudinal plane in the central portion by the first support member. Furthermore, the tube is supported along a second longitudinal plane in the central portion by a second support member. Both free ends of the tube are unsupported and this part forms the material that is deformed in the mold. A movable block driven by the first external drive exerts a lateral outward force on the second support member to firmly support the central portion of the second longitudinal surface of the tube. The first support member, punch and block can be driven by an external hydraulic source to perform the required process.

The terms "comprising," "comprising," or other variations thereof, as used herein, are intended to cover non-exclusive inclusion, and therefore exclude listing of components or steps. The provided assembly does not include only those components or steps, but may include other components or steps not explicitly listed or that are specific to such a situation or method. In other words, one or more elements within an assembly expressed by "comprising" does not exclude the presence of other or additional elements within the assembly, without further restriction.

The present disclosure is now described with the help of one or more illustrations of example embodiments. However, such exemplary embodiments should not be construed as a limitation of this disclosure.

The following paragraphs describe the present disclosure with reference to FIGS. 1, 2, 3, 4a and 4b. In the figures, identical element(s) with similar functions are designated by identical reference symbols.

FIG. 1 is an exemplary embodiment of the present disclosure, showing a perspective view of a device (100) used to thicken a tube (101) at one or both ends. As shown in FIG. 1, the apparatus (100) includes a first support member (102), a second support member (103), a punch (104), and a block (105). The tube (101) is held rigidly between a first support member (102) and a second support member (103) in the longitudinal planes (110 and 111) of the tube. The first support member (102) is configured to rigidly support the tube (101) in a first longitudinal plane (110). The first longitudinal surface (110) of the tube (101) may be the outer surface of the tube (101). Furthermore, the second support member (103) is configured to firmly support the tube (101) in the second longitudinal plane (111). The second longitudinal surface (111) of the tube (101) may be the inner surface of the tube (101). The block (105) as shown in Figure 1 is configured to impart lateral outward movement to the second support member (103). The block (105) is driven longitudinally by the first external power source to impart lateral outward movement to the second support member (103). The lateral outward movement provided by the block (105) helps the support member (103) to firmly hold the second longitudinal surface (111) of the tube (101). The first support member (102) is also driven by a second external power source, and the second external power source drives the tube (101) between the first support member and the second support member (102 and 103). Provides the necessary force to hold firmly between the Punch (104) is located above block (105) and configured for a third external power source (not shown). The first external power source longitudinally drives the block (105), where the block (105) applies a lateral outward force on the second support member (103) as described above. A longitudinal force of the punch (104), driven by a third external power source, is applied onto the free end of the tube (101). The force applied by the punch (104) acts as a compressive force at one or both ends of the tube (101). This compressive force causes either end of the tube (101) to plastically deform into the part of the mold formed by the first support member and the second support member (102 and 103). Furthermore, the compressive force acting on the end of the tube (101) deforms the tube (101) into the shape of the mold formed by the support members (102 and 103). The mold as described above is formed by chamfers provided at the extreme ends of the first and second support members (102 and 103).

The first support member (102) includes an outer tube retainer (106) and an outer insert (107) (half of the outer tube retainer assembly) as shown in FIG. Outer tube retainer (106) and outer insert (107) are connected by at least one means, such as, but not limited to, mechanical bonding and thermal bonding. The outer tube holder (106) is a hollow cylindrical part divided into two equal halves. The outer tube retainer (106) is uniform in cross-section, ie, the inner and outer diameters of the retainer (106) are the same throughout. The outer insert (107) is a hollow cylindrical part with a varying cross section. The outer insert (107) is also divided into two equal halves, each half of the outer insert being coupled to a respective half of the outer retainer (106). The outer insert (107) may be designed to define a part of the mold to fulfill the purpose of thickening the tube (101). The outer insert (107) at the extreme end is chamfered, the chamfered end defining part of the mold for plastic deformation of the end of the tube (101). The second support member (103) includes an inner tube retainer (108) and an inner insert (109), as shown in FIG. The inner tube holder (108) is a hollow cylindrical part whose cross section changes uniformly from the top to the bottom. The uniformly varying cross section may be configured to accommodate the block (105). The inner insert (109) may be designed to define a part of the mold to fulfill the purpose of thickening the tube (101). The inner insert (109) is chamfered at one or both extreme ends, this chamfer defining part of the mold for plastic deformation of the end of the tube (101). The inner insert (109) is also divided into two equal halves, each half of the inner insert (109) being coupled to a respective half of the inner retainer (108). Additionally, both halves of the two parts, the inner tube retainer assembly (108 and 109) and the outer tube retainer assembly (106 and 107), are assembled together into the device (100). The assembled parts, namely the outer tube retainer assembly (106 and 107) and the inner tube retainer assembly (108 and 109), form a first support member and a second support member (102 and 103), respectively. . The chamfered ends of the first support member (102) and the second support member (103) define a complete mold section for plastic deformation of the ends of the main pipe.

Furthermore, the tube (101) is held rigidly over the central portions of the first and second longitudinal surfaces (110 and 111). The ends of the tube (101) other than the central part of the longitudinal planes (110 and 111) are unsupported. The ends of the tube (101) at one or both ends can be subjected to a compressive force by the punch. The force applied on the end of the tube (101) plastically deforms this tube into the shape of the mold created by the first support member and a portion of the second support member (102 and 103). . A first support member (102) cooperates with a second support member (103) to firmly hold the tube, centrally between the first and second longitudinal surfaces (110 and 111). Support only parts. The force required to grip this portion of the tube (101) is applied to the first and second support members (102 and 103) by a first external power source and a second external power source. are given to each. The first power source provides longitudinal movement to block (105), which moves into inner tube retainer (108). The block applies a lateral outward force to the second support member (103), which, in combination with the support of the first support member (102), then forces the tube (101). hold firmly. The first support member (102) is driven by a second external power source, such as a hydraulic actuator. When the tube (101) is held firmly by the first support member and the second support member (102 and 103), the tube is subjected to a compressive force. Compressive force is provided by a punch (104) that may be driven by a third external power source. As shown in Figure 4a, the tube (101) is subjected to compressive forces at one or both ends. The compressive force applied to the end of the tube (101) causes the end of the tube (101) to plastically deform. The plastically deformed tube (101) assumes the shape of a mold formed by a portion of the first support member and the second support member (102 and 103) as described above. Since the tube (101) takes the shape of a mold, the thickness of the end of the tube (101) increases after plastic deformation. The first external power source and the second external power source may be any one of a hydraulic drive device, a pneumatic drive device, etc., but are not limited thereto. A first external power source, a second external power source, and a third external power source may be used to drive block (105), punch (104), and first support member (102). However, the second support member (103) is driven by a block (105) which provides a lateral outward force on the second support member (103). The block (105) may be of any shape, such as, but not limited to, a wedge shape. A tube (101) formed using the apparatus (100) and the process may have a body portion (200) and a lip portion (201).

As shown in Figures 4a and 4b, the tube (101) includes a body portion (200) and a lip portion (201). The body portion (200) of the tube (101) may be uniform in cross section. Edge portions (201) may be present at one or both ends of the body portion (200) of the tube (101). The edge portion (201) is formed by plastic deformation into the mold. The rim (201) has a thickness greater than the thickness of the body portion (201) of the tube (101). The thickness of the tube edge portion (201) is approximately 20% to 30% greater than the thickness of the body portion (200) according to the present disclosure and varies uniformly. As shown in Figure 4b, Figure 4b depicts a fully manufactured tube (101) held between the first and second support members (102 and 103) of the device (100). It is shown in The end of the tube (101) after deformation takes the shape of a mold section, thereby increasing the thickness only at the end. The thickened end of the tube (101) defines an edge portion (201) as shown in Figure 4b. The body portion (200) of the tube (101) is uniform in cross section. The thickening process can be performed in a variety of materials including, but not limited to, mild steel with certain alloying elements.

The device (100) allows the tube (101) to be thickened at one or both ends simultaneously, which ensures lower cycle times and thereby improves the productivity of the device (100). The process has lower operating costs relative to conventional equipment due to the use of less tonnage equipment. The tube (101) also undergoes strain hardening during this process, which facilitates an increase in the strength of the tube (101).

Equivalents With respect to the use of virtually any plural and/or singular term in this application, those skilled in the art will be able to convert from the plural to the singular and/or from the singular as appropriate to the context and/or use. Can be replaced with plural form. In this application, various singular/plural permutations may be explicitly set forth for the sake of clarity.

In general, those skilled in the art will understand that the terms used in this application are generally intended as "open" terms (e.g., the term "comprising" means "including but not limited to"). The term "having" should be interpreted as "having at least" and the term "comprising" should be interpreted as "having at least" should be interpreted as ``including, but not limited to,'' (and so on). If a specific number is intended in the introduced claim statement, such intent will be expressly stated in the claim, and if no such statement is made, then the Those skilled in the art will further understand that there is no such intention. For example, as an aid to understanding, the description may include the use of the introductory phrases "at least one" and "one or more" to introduce claim subject matter. However, the use of such phrases does not mean that the introduction of claim subject matter by the indefinite article "a" or "an" may be used even if the introduction of "one or more" or "at least one" in the same claim Even if an introductory phrase and an indefinite article such as "a" or "an" are included, any particular claim containing the claim recitation so introduced cannot be defined as such recitation. nothing should be construed as meant to limit the invention to only one item (e.g., "a" and/or "an" typically refers to "at least one" or "one or more"). (should be construed as meaning). The same applies to the use of definite articles used to introduce claim subject matter. In addition, where a specific number is expressly recited in the introduced claim recitation, such recitation should generally be construed to mean at least the recited number. Those skilled in the art will recognize that (e.g., the mere statement "two entries" without other modifiers usually means at least two entries, or more than one entry) . Furthermore, in those cases where idiomatic expressions similar to "at least one of A, B, C, etc." are used, such constructions generally have the meaning that a person skilled in the art would understand the idiomatic expression to mean. (e.g., "a system having at least one of A, B, and C") is intended to include only A, only B, only C, both A and B, both A and C, B and (including, but not limited to, systems having both A, B, and C, etc.). In those cases where an idiomatic expression similar to "at least one of A, B, or C, etc." is used, such construction generally means that a person skilled in the art would understand this idiomatic expression. (e.g., "a system with at least one of A, B, or C") is intended to include A only, B only, C only, A and B together, A and C together, B and C. and/or systems having both A, B, and C). Substantially any disjunctive word and/or disjunctive phrase indicating two or more alternative terms may be used in either the description or the drawings to indicate one, either, or both of the terms. Those skilled in the art will further understand that it should be understood to take into account the possibility of including. For example, the phrase "A or B" will be understood to include the possibilities "A" or "B" or "A and B."

Although various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are illustrative and not intended to be limiting, with the true scope and spirit being indicated in the description.

100 apparatus, 101 tube, 102 first support member, 103 second support member, 104 punch, 105 block, 106 outer tube holder, 107 outer insert, 108 inner tube holder, 109 inner insert, 110 first Longitudinal surface, 111 Second longitudinal surface, 200 Body portion, 201 Edge portion.

Claims (19)

A device (100) for thickening a tube (101) at an edge (201) of the tube (101), said device (100) comprising:
rigidly supporting a first longitudinal surface (110) of said tube (101) along the length of said first longitudinal surface (110) except at one or both ends of said tube (101); a first support member (102) configured to;
a second longitudinal surface (111) of said tube (101) is made rigid along the length of said second longitudinal surface (111) excluding said one or both ends of said tube (101); a second support member (103) configured to support;
a punch (104) driven by an external power source;
Equipped with
the punch (104) is configured to exert a force on either end of the tube (101);
Device (100), characterized in that the application of force by said punch (104) plastically deforms said end of said tube (101), thickening said tube (101) at one or both ends. 2. The apparatus (100) of claim 1, comprising a block (105) driven by a first external power source, wherein a longitudinal force on the block (105) is applied to the second support member ( Apparatus (100) characterized in that the device (100) is configured to impart a lateral outward movement to the tube (103) to further support said second longitudinal surface (111) of said tube (101). Device (100) according to claim 2, characterized in that said block (105) is wedge-shaped. Apparatus (100) according to claim 1, characterized in that said first support member (102) is driven by a second external power source. Apparatus (100) according to claim 1, characterized in that said first support member (102) comprises an outer tube retainer (106) and an outer insert (107). 100). The apparatus (100) of claim 5, wherein the outer tube retainer (106) and the outer insert (107) are joined by at least one of a mechanical bond and a thermal bond. A device (100) characterized by: 7. Apparatus (100) according to claim 6, wherein the end of the outer insert (107) defines a part of a mold for plastic deformation of the end of the tube (101). A device (100) characterized in that it is chamfered so as to. Device (100) according to claim 1, characterized in that said second support member (103) comprises an inner tube holder (108) and an inner insert (109). 100). The apparatus (100) of claim 8, wherein the inner tube retainer (108) and the inner insert (109) are joined by at least one of a mechanical bond and a thermal bond. A device (100) characterized by: Apparatus (100) according to claim 9, characterized in that the end of the inner insert (109) defines part of a mold for plastic deformation of the end of the tube (101). A device (100) characterized in that it is chamfered so as to. The apparatus (100) of claim 2, wherein the second support member (103) comprises an inner tube retainer (108) and an inner insert (109), the inner tube retainer (108) A device (100) characterized in that the shape of the block corresponds to the shape of the block (105). Apparatus (100) according to claim 2, characterized in that the first external power source is a hydraulic drive. The apparatus (100) according to claim 1, wherein the first support member (102) and the second support member (103) are spaced apart from each other at opposite ends of the support member. A device (100) characterized in that it is chamfered in such a way that it does not come into contact with the edge (201) of said tube. Device (100) according to claim 1, characterized in that the first longitudinal surface (110) of the tube (101) is an outer surface of the tube (101). ). Device (100) according to claim 1, characterized in that said second longitudinal surface (111) of said tube is an inner surface of said tube. A process of thickening a tube (101) at the edge (201) of the tube (101), said process comprising:
A first support member (102) supports a first longitudinal surface (110) of said tube (101), excluding one or both ends of said tube (101). ) along the length of the
A second support member (103) extends the length of the second longitudinal surface (111) of the tube (111), excluding one or both ends of the tube (101). to support along the lines of
compressing one or both ends of said tube (101) by a punch (104);
including;
A process characterized in that the application of force by said punch (104) plastically deforms said end of said tube (101) and increases the thickness of said tube (101) at one or both ends. 17. Process according to claim 16 , characterized in that the block (105) moves the second support member (103) laterally outwardly to stiffen a central portion of the inner surface of the tube (101). A process characterized by comprising supporting. Process according to claim 17 , characterized in that said block (105) is wedge-shaped. Process according to claim 18 , characterized in that the first support member (102), the punch (104) and the block (105) are driven by an external hydraulic pressure source.

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