EP4121230B1

EP4121230B1 - A mandrel assembly for thickening brim portions in an inner surface of a tube

Info

Publication number: EP4121230B1
Application number: EP21717528.0A
Authority: EP
Inventors: Pala LAKSHMIKANT; Vishal KALUBHAI BHARODIYA; Gujre VINAY SANJAY; Rahul Kumar Verma
Original assignee: Tata Steel Ltd
Current assignee: Tata Steel Ltd
Priority date: 2020-03-18
Filing date: 2021-03-18
Publication date: 2024-12-04
Anticipated expiration: 2041-03-18
Also published as: JP2022529305A; EP4121230A1; CO2021012473A2; BR112021018992A2; WO2021186386A1; JP7237181B2

Description

TECHNICAL FIELD

The present disclosure relates to the field of metal working technology. Particularly, but not exclusively, the present disclosure relates to forming or thickening portions of a tube. Further embodiments of the present disclosure disclose a mandrel assembly for thickening a brim portion on either ends of the tube from its inner surface keeping the outer surface same.

BACKGROUND OF THE DISCLOSURE

A tube is a hollow elongated member made from materials including, but not limited to, metal, polymers, composites and the like. The tubes, in general, may be made by process including but not limited to, rolling, extrusion, pultrusion, protrusion, and the like, where the tube may include a defined thickness based on application. The tube may be used in various fields of domestic, medical, fuel gas distributions, automotive and other applications, including air conditioning and refrigeration. For example, in the automotive applications such as two-wheelers, tubes may be used in frames, seating systems, fuel delivery components and automotive link arms require tubes to be welded to create an integrated frame. The tubes may be welded using various known welding methods such as MIG welding, flux-cored arc welding, TIG welding, stick welding and the like, depending on factors including, but not limited to, material of the tube, the size [that is, thickness and diameter] of the tube, profile of the tube joining region, and the like, based on structural configuration required for application of the tube. Further, welding of two or more tubes may result in different zones being formed at a weld juncture, where the different zones include fusion zone, weld interface, heat affected zone, and the like. In general, the fusion zone and the HAZ acts stress affected zones at the joining region of the two or more tubes, where such stress affected zones tend to increase stress concentration in the joining region, impacting structural properties of the two or more tubes. For example, the stress affected zones may reduce durability of the two or more tubes at the joining region for loads including, but not limited to, fatigue load, axial load, shear load, and the like, whereby reducing industrial applicability of the tubes.
To avoid formation of such stress affected zones in the joining regions, conventionally, dimensions of the tubes including, but not limited to, thickness, may be increased, where either overall thickness of the tubes may be increased or thickness at predetermined portions of the tube may be increased to address the stress concentration at the joining regions. The tubes with overall increased thickness may add unnecessary weight to the application, while the tubes with increased thickness at predetermined portions may overcome the limitations of the tubes with overall increased thickness. The tubes may be defined with a thickened portion at the joining regions of the two or more tubes [generally, at brim portion to address impact of the stress concentration]. In general, for applications including, but not limited to, automotive industry, one end of the tubes is defined with a thickened portion [or commonly referred to as increased thickness at a given portion] at a brim portion [or commonly referred to as free ends of the tubes] of the tube such that, the thickened portion of the tube may be joined at a free end of subsequent tube having no thickened portions. This way, by defining one end of the tube with the thickened portion, stress concentration at the joining region of two or more tubes may be minimized, while maintaining add-on weight to a minimum value.
Conventionally some processes have been developed and employed for producing tubes with thickened portion. Some of such conventional processes may be including, but not limited to, flexible rolling, swage auto-frettage process, tube drawing using position controlled mandrel methods, extrusion with special die setup and also internally and externally upsetting ends of the tube. The above said processes have several restraints such as higher investment in tooling and/or low productivity due to increased cycle time. In some of the conventional processes, a punch-die assembly is employed for thickening the brim portions of the tube, where the punch-die assembly may be configured to thicken brim portion in one of the sides of the tube at a time. Though the punch-die assembly may address some of the limitations of the conventional methods, operation of the punch-die assembly may be restricted to producing the thickened portion at one end of the tube, as the die may be concealed within the brim portion if both brim portions of the tube are thickened simultaneously.
Example of known mandrel assemblies are disclosed in publications US2017/106431 A1 , forming the basis for the preamble of claim 1, CA1280942 C , CN105945201 A , DE 102007034938 A1 or US10514 113 B2 .
The present disclosure is directed to overcome one or more limitations stated above.

SUMMARY OF THE DISCLOSURE

One or more shortcomings of the conventional process are overcome by a mandrel assembly according to claim 1, a method for assembling a mandrel assembly according to claim 4 and a method for retracting a mandrel assembly according to claim
Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the disclosure.
It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other, without departing from the scope of the appended claims.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

The novel features and characteristic of the disclosure are set forth in the appended claims.
The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which:

FIG.1 is a sectional view of a mandrel assembly employed for thickening brim portion in an inner surface of a tube, in accordance with an embodiment of the present disclosure.
FIG.2 illustrates a perspective view of the mandrel assembly of FIG.1.
FIGs.3A-3D illustrates pictorial views of a press apparatus having the mandrel assembly for thickening brim portion in the inner surface of the tube, in accordance with an embodiment of present disclosure.
FIG.4 illustrates cross-sectional view of the tube that is plastically deformed in the inner surface of the tube using the mandrel assembly of FIG.1, in accordance with an embodiment of the present disclosure.
FIG. 5 illustrates a schematic representation of retracting of the mandrel assembly from FIG. 4, in accordance with an embodiment of the present disclosure.

The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the scope of the appended claims.

DETAILED DESCRIPTION

The foregoing has broadly outlined 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 will be described hereinafter which form the subject of the claims of the disclosure. It should be appreciated by those skilled in the art that the conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present disclosure, without departing from the scope of the disclosure as set forth in the appended claims. The novel features which are believed to be characteristic of the disclosure, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures. It is to be expressly understood, however, that each of the figures is provided for the purpose of illustration and description only and is not intended as a definition of the limits of the present disclosure. It will be readily understood that the aspects of the present disclosure, as generally described herein, and illustrated in the figures, can be arranged, substituted, combined, and designed in a wide variety of different configurations, all of which are explicitly contemplated and make part of this disclosure as defined in the appended claims.
Embodiments of the present disclosure discloses a mandrel assembly for thickening brim portion in an inner surface of a tube, particularly tubes that may be used in components of an automobile. The mandrel assembly includes a central core element, which is configured to rigidly support a plurality of segments on an outer surface and to accommodate the tube along its length. The plurality of segments are disposable between the central core element and the inner surface of the tube. Further, both ends of each of the plurality of segments are defined with a forming region that is aligned about a specific end, where the brim portion of the tube is deformable along the forming region of the plurality of segments. Also, the mandrel assembly is disassembled/dismantled by displacing the central core element from the plurality of segments. Due to such displacement of the central core element, one segment of the plurality of segments collapses due to gravity, thereby allowing retraction of remaining segments of the plurality of segments. This way, the brim portion of the tube at both ends can be thickened and the mandrel assembly can be effortlessly retrieved from inside of the tube. The terms "comprises", "comprising", or any other variations thereof used in the specification, are intended to cover a non-exclusive inclusion, such that an assembly that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or method. In other words, one or more elements in an assembly proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the assembly.
Henceforth, the present disclosure is explained with the help of one or more figures of exemplary embodiments. However, such exemplary embodiments should not be construed as limitation of the present disclosure.
The following paragraphs describe the present disclosure with reference to FIGS.1 to 4. In the figures, the same element or elements which have similar functions are indicated by the same reference signs.
FIGs.1 and 2 are exemplary embodiments of the present disclosure showing sectional view and perspective view of a mandrel assembly 100 for thickening portions of a tube 200. The mandrel assembly 100 may be employable in a press apparatus 300 herein after referred to as "the apparatus" [or generally referred to as punch unit] to enable thickening of sections about a brim portion 202 along an inner surface 201 of the tube 200. In an embodiment, the press unit may be including, but may not be limited to, a hydraulic press unit, a pneumatic press unit, a combination of the either of the two, and any other press unit that may be employable for thickening portions of the tube 200. The tube 200 may be of cross-sectional profiles including, but not limited to, triangle, square, rectangle, elliptical, and the like, while for illustration the tube 200 of the present disclosure is illustrated with circular or cylindrical profile. As shown in FIGs.1 and 2, the mandrel assembly 100 includes a central core element 1 and a plurality of segments 2 [or also referred to as die segments 2 of the mandrel assembly 100 for the press unit], where the plurality of segments 2 are disposable around the central core element 1. Each of the central core element 1 and the plurality of segments 2 may include an elongated portion which may be dimensioned to be at least one of equal to, greater than or lesser than longitudinal dimension of the tube 200. Further, the central core element 1 and the plurality of segments 2 may be made from homogenous material or heterogeneous material, where the material may be including, but not limited to, metals, non-metals, polymers, reinforced substances, and the like. Additionally, the central core element 1 and the plurality of segments 2 may be structured to be rigid and may be either solid composition or may be hollow, based on material employed for making the central core element 1 and the plurality of segments 2.
Referring now to FIG.2, an outer section of the central core element 1 and interior portion of each of the plurality of segments 2 may be configured to complement one another at the interface therebetween. The interface between the plurality of segments 2 and the central core element 1 may be defined with tolerance along portions on the circumference or may be seamless, based on required portion for thickening of the tube 200. The plurality of segments 2 are defined with a forming region 3, where the forming region 3 may act as a pressure-acting-surface for the inner surface 201 of the tube 200. The forming region 3 of the plurality of segments 2 may be configured to allow thickening at defined portions of the tube 200. The forming region 3 may be defined at any section along the length of the plurality of segments 2 in order induce thickening at defined portion of the inner surface 201 of the tube 200. In an embodiment, the plurality of segments 2 may be assembled to align the forming region 3 at one end such that, the brim portion 202 of the tube 200 on at least one end may be deformable along the forming region 3 to induce thickened portion in the tube 200. According to the invention, the forming region 3 is defined at both ends of the plurality of segments 2. The forming regions may be assembled at one side of each of the plurality of segments 2 or at different sides such that, thickening of the brim portion 202 of the tube 200 may be symmetric or asymmetric respectively, about a predetermined axis of the central core element 1. In an embodiment, the forming region 3 may be defined with at least one of depression pattern, bulge portion, a defined pattern [such as, knurled pattern, thread pattern] and/or a combination of each. In the illustrative embodiment, the forming region 3 is defined with a tapered profile [for example, a depression at ends of the segments 2] on both sides of the plurality of segments 2, in order to thicken the inner surface 201 of the tube 200 at both ends, while one or some of the plurality of segments 2 may be defined with the forming region 3 in order to thicken. Also, the forming region 3 may be defined about a predetermined length of the plurality of segments 2.
In an embodiment, the plurality of segments 2 may include two or more segments 2, which may be configured to surround the central core element 1 about perimeter region and along length of the central core element 1. The two or more segments 2 of the plurality of segments 2 may be positioned on the central core element 1 about a reference section. For example, a reference line may be indicated on interface surface between the central core element 1 and the plurality of segments 2. Also, the central core element 1 may be defined with at least one of splines, keyways, grooves, and the like on the outer surface, to accommodate and restrain rotational motion of the two or more segments 2 on the central core element 1. In the illustrative embodiment, the plurality of segments 2 may include four segments 2, namely a first segment [also referred to as one segment 2a] and second segment, third segment and fourth segment [also referred to as remaining segments 2b] as 2a, 2b, respectively, as depicted in FIG.2. Further, one segment 2a of the plurality of segments 2 may be positioned between the central core element 1 and the inner surface 201 of the tube 200 and, remaining segments 2b of the plurality of segments 2 may be positioned relatively [for example, on either side of the one segment 2a and subsequently adjacent thereto] around the perimeter of the central core element 1. This way each of the plurality of segments 2 may be assembled within the tube 200 and on the central core element 1.
Referring now to FIGs 3A-3D, which illustrates a schematic diagram of the apparatus 300, where the apparatus includes a first support member 301, a second support member 302 and a punch 303. The first support member 301 may be installed on a rigid platform [for example, the ground] where the apparatus may be mounted and, the second support member 302 may be selectively operable to be positioned proximal and/or distal from the first support member 301. Further, the central core element 1 may be longitudinally suspended [for example, connected or held] from the first support member 301 at one end, while the tube 200 may be inserted and secured [for example, by virtue of gravity and self-weight] about perimeter of the central core element 1 about the other end, as best seen in FIG. 3A. Also, the second support member 302 may be operable by an operation element including, but not limited to, a hydraulic operation element, a pneumatic operation element, an electric operation element, a gear arrangement element, and the like, to displace [that is, vertically move] the second support member 302 for rigidly gripping the tube 200 and centrally [for example, concentrically or symmetrically] aligning the tube 200 about the central core element 1, defining a predetermined gap therebetween. In an embodiment, the second support member 302 may be driven by the operational element to provide necessary force for firmly gripping the tube 200 about the central core element 1. In an embodiment, degree of alignment of the tube 200 about the central core element 1 may be configured to vary thickening of the brim portion 202 of the tube 200, at its inner surface 201.
Turning now to FIG. 3B, upon aligning the tube 200 about the central core element 1, predetermined gap defined between the tube 200 and the central core element 1 may substantially be equal to thickness of the plurality of segments 2. Further, one segment 2a of the plurality of segments 2 may be disposable between the inner surface 201 of the tube 200 and central core element 1. In the illustrative embodiment, the one segment 2a of the plurality of segments 2 may be positioned at top section and at the center in the predetermined gap between the tube 200 and the central core element 1. Further, the remaining segments 2b of the plurality of segments 2 may be positioned around the perimeter of the central core element 1, as best seen in FIG. 3C. Upon positioning and aligning the plurality of segments 2 and the tube 200 relative to the central core element 1, the tube 200 may be co-axially [also referred to as lateral direction] engaged by the punch 303 from either ends. The punch 303 may be aligned such that, an outer edge of the punch 303 may be in-line [that is, having minimal tolerance therebetween] with an outer surface of the tube 200 in order to mitigate action of shear force at portions of the tube 200. Also, dimension of the punch 303 may be greater than thickness of the tube 200, in order to enhance deformation of the tube 200 at the brim portion 202 and mitigate piercing of the tube 200. In continuation, the punch 303 may be configured to exert pressure [for example, compressive pressure] about the brim portion 202 [or at lateral surface or perimeter] of the tube 200 to axially deform [or press] the tube 200 about its inner surface 201. The second support member 302 may restrict upward movement [or flow of the material] of the tube 200, whereby restricting deformation to the inner surface 201 of the tube 200 and maintaining external dimensions of the tube 200. The prolonged application of pressure by the punch 303 at the brim portion 202 on the inner surface 201 of the tube 200 may be complemented by an outward force imparted by the plurality of segments 2, as best seen in FIG.3D. Due to the combined pressure applied by the punch 303 and the plurality of segments 2, the brim portion 202 may be thickened about the inner surface 201 of the tube 200, where the thickening may resemble the profile defined on the outer surface of the plurality of segments 2, as best seen in FIG.2.
Additionally, thickness at the brim portion 202 of the tube 200 increases after the plastic deformation, as it takes the shape of the plurality of segments 2, as best seen in FIG. 4. Due to such increase in thickness at the inner surface 201 of the tube 200, the mandrel assembly 100 having the central core element 1 and the plurality of segments 2 within the tube 200 may get rigid, whereby the plurality of segments 2 may not be retrievable from inside of the tube 200. For retrieving the plurality of segments 2 from the tube 200, interface between the central core element 1 and the plurality of segments 2 may be defined to be a slideable such that, the central core element 1 may be displaced from such interface. The central core element 1 may be axially displaced [for example, pulled or pushed along the longitudinal axis of the tube 200] by either operating the first support member 301 to extrude the central core element 1 from inside of the tube 200 or by employing a pull mechanism to draw out the central core element 1 from inside of the tube 200. The central core element 1 includes a provision such as, but not limited to, a recess, protuberance, protrusion, and the like, which may enable the central core element 1 to be axially retrieved from the plurality of segments 2 and the tube 200. The central core element 1 which may be surrounded by the plurality of segments 2 and the tube 200, from interior to exterior, respectively, may loosen rigidity of the assembly 100, upon retracting [or displacing]. Further, retraction of the central core element 1 may result in collapse of the one segment 2a of the plurality of segments 2 due to gravity [or self-weight]. As the one segment 2a of the plurality of segments 2 collapses, connection between the remaining segments 2b of the plurality of segments 2 within the tube 200 may be fragile and may be individually retrieved from inside of the tube 200, as seen in FIG. 5.
In an embodiment, the punch 303 may be simultaneously from either ends of the tube 200 and may be driven by an external actuation source [not shown in figures], where the external actuation source may be driven by mechanisms such as, but not limited to, hydraulic mechanism, pneumatic mechanism, electrical means, and the like. Further, the pressure exerted by the punch 303 may plastically deform the brim portion 202 about internal surface of the tube 200 at its either ends.
The assembly 100 can simultaneously thicken the inner surface 201 of the brim portion 202 on both the ends of the tube 200, this ensures lower cycle time which improves the productivity in manufacturing plant. Further, the process has low operation cost over the conventional device due use of less tonnage equipment. Also, the tubes undergo strain hardening during the process, facilitating in increase in strength of the tube 200.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art within the scope of the appended set of claims.

Referral Numerals:

Particulars	Numeral
Mandrel assembly
	100
Central core element	1
Plurality of segments	2
One segment of the plurality of segments	2a
Remaining segments
	2b
Forming region
	3
Tube	200
Inner surface	201
Brim portion	202
Press apparatus	300
First support member	301
Second support member	302
Punch	303

Claims

A mandrel assembly (100) for thickening a brim portion (202) of a tube (200), the assembly (100) comprising:
a central core element (1) receivable by an inner surface (201) of the tube (200); and

a plurality of segments (2), disposable between the central core element (1) and the inner surface (201) of the tube (200),

characterized in that

the plurality of segments (2) are configured to surround the central core element (1) about perimeter region and along entire length of the central core element (1) and both ends of each of the plurality of segments (2) are defined with a forming region (3), wherein each of the plurality of segments (2) is detachably positioned on the central core element (1), wherein, in use, the brim portion (202) of the tube (200) is deformable along the forming region (3) in both ends of each of the plurality of segments (2).
The assembly (100) as claimed in claim 1, wherein the forming region (3) of each of the plurality of segments (2) is defined with a tapered profile.
The assembly (100) as claimed in claim 1, wherein the central core element (1) is a solid core.
A method for assembling a mandrel assembly (100) as claimed in claim 1 within a tube (200), said mandrel assembly (100) being configured for thickening a brim portion (202) of said tube (200), the method comprising:
positioning the central core element (1) about an internal surface of the tube (200),

positioning the plurality of segments (2) between the central core (1) and the inner surface (201) of the tube (200), wherein the plurality of segments (2) are configured to surround the central core element (1) about perimeter region and along entire length of the central core element (1) and both ends of each of the plurality of segments (2) are defined with a forming region (3) that aligns with the brim portion (202) of the tube (200), wherein each of the plurality of segments (2) is detachably positioned on the central core element (1).
The method as claimed in claim 4, comprising:
positioning the central core element (1) abutting the inner surface (201) of the tube (200), positioning one segment (2a) of the plurality of segments (2) between the central core element (1) and the inner surface (201) of the tube (200), and positioning remaining segments (2b) of the plurality of segments (2) around the perimeter of the central core element (1).
A method for retracting a mandrel assembly (100) as claimed in claim 1 from within a tube (200), said mandrel assembly (100) being configured for thickening a brim portion (202) of said tube (200), the method comprising : displacing the central core element (1) axially from the plurality of segments (2) and out of the tube wherein the plurality of segments (2) are configured to surround the central core element (1) about perimeter region and along entire length of the central core element (1); and wherein, retraction of the central core element from the plurality of segments (2) collapses one of the plurality of segments (2a) due to gravity, and
retracting remaining segments (2) of the plurality of segments (2) from the tube.