DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
AN EXPANSION MANDREL

Applicant:
BEML Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
BEML Soudha, 23/1, 4th Main,
Sampangirama Nagar, Bengaluru - 560 027,
Karnataka, India

The following specification particularly describes the invention and the manner in which it is to be performed.

CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] This patent application claims priority from Indian Provisional Application 202041004328 filed on January 31, 2020.
TECHNICAL FIELD
[002] The present subject matter described herein, in general, relates to a device for holding workpiece. More specifically, the present invention relates to an expansion mandrel.
BACKGROUND
[003] Generally, during machining of tubes with less wall thickness on any machine such as horizontal milling center, vertical milling center, turning center etc. the tube tends to produce ovality while clamping / de-clamping. This ovality severely affects the final dimensions of the tube to be achieved. Also geometric dimensioning and tolerance (GD&T) parameters are affected due to ovality. Thus, there is a need to eliminate the ovality and achieve the GD&T parameters, which ensures the final dimensions of the tube as per the drawing requirement.
[004] The present invention is directed to overcome one or more limitations of the prior art discussed above.
OBJECT OF THE INVENTION
[005] It is an object of the present invention to provide support from inside of the mandrel for tubes with less wall thickness.
[006] It is an object of the present invention to avoid formation of ovality in tubes having less wall thickness.
[007] It is an object of the present invention to accommodate tube of any inside diameter.
[008] It is an object of the present invention to adjust according to changes in inside diameter of the tube.
[009] It is an object of the present invention to design an expansion mandrel which is light in weight and easy to handle.
SUMMARY
[0010] Before the present system and method are described, it is to be understood that this application is not limited to the particular machine or an apparatus, and methodologies described, as there can be multiple possible embodiments that are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular versions or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to an expansion mandrel, and the aspects are further elaborated below in the detailed description. This summary is not intended to identify essential features of the proposed subject matter nor is it intended for use in determining or limiting the scope of the proposed subject matter.
[0011] An expansion mandrel for clamping a tube from inside comprises a splitted ring configured for mounting plurality of segments circumferentially, a screw mounted on said splitted ring is configured to interlock with segment, a nut configured for fastening said screw at a pre-determined position and a dowel pin configured to be inserted in hole provided on said splitted ring for locking rotary movement of said segment interlocked with said screw.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The foregoing summary, as well as the following detailed description of embodiments, is better understood when read in conjunction with the appended drawing. For the purpose of illustrating the disclosure, there is shown in the present document example constructions of the disclosure, however, the disclosure is not limited to the specific methods and apparatus disclosed in the document and the drawing:
[0013] The detailed description is described with reference to the accompanying figure. In the figure, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawing to refer like features and components.
[0014] Figure 1 illustrates an expansion mandrel, in accordance with one embodiment of the present subject matter.
[0015] Figure 2 illustrates a front view of the expansion mandrel, in accordance with one embodiment of the present subject matter.
[0016] The figure depicts various embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAILED DESCRIPTION
[0017] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising", “having”, and "including," and other forms thereof, are intended to be equivalent in meaning and be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. Although any systems and methods similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, systems and methods are now described. The disclosed embodiments are merely exemplary of the disclosure, which may be embodied in various forms.
[0018] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments. However, one of ordinary skill in the art will readily recognize that the present disclosure is not intended to be limited to the embodiments illustrated, but is to be accorded the widest scope consistent with the principles and features described herein.
[0019] Referring now to figure 1 and 2, an expansion mandrel is disclosed. An expansion mandrel (100) for clamping a tube from inside comprises a splitted ring (102) configured for mounting plurality of segments (104) circumferentially, a screw (106) mounted on said splitted ring (104) is configured to interlock with segment (104), a nut (108) configured for fastening said screw (106) at a pre-determined position and a dowel pin (110) configured to be inserted in hole (110) provided on said splitted ring (102) for locking rotary movement of said segment (104) interlocked with said screw (106). The screw (106) is configured with a groove (112) for receiving said dowel pin (110) to interlock said segment (104).
[0020] The screw (106) is configured to translate rotary motion into linear motion of said segment (104). The screw (106) is configured to be hexagonal socket headed or an allen screw. Plurality of segments (104) are configured for clamping on inner side of said tube to prevent deformation of said tube during machining. The nut (108) is configured to be hexagonal.
[0021] In one embodiment, the splitted ring 102 and segments 104 are machined separately and then assembled as a unit using cap screw 106, hexagonal nut 108 and a dowel pin 110. After assembling, the entire unit is split into half before positioning inside the tube. Once it is positioned inside the tube, the segment 104 can be moved using cap screw 106 until the segment 104 contacts the inside wall of the tube. Once the segment 104 contacts the tube inside diameter, the required torque can be applied by the cap screw 106 and the pre-determined position can be locked using the nut 108. Once the combined unit is assembled within the tube, the tube can be loaded on the machine to perform various machining operations. After completion of the machining operation, the expansion mandrel 100 can be disassembled and then removed from the tube.
[0022] Exemplary embodiments discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features.
[0023] Some object of the present invention is suitable to tube of any diameter range.
[0024] Some object of the present invention maintains roundness of the tube during clamping and de-clamping.
[0025] Some object of the present invention eliminates ovality after machining of the tube.
[0026] Some object of the present invention ensures manufacturing of tubes as per engineering drawings and thereby prevent rejections.
[0027] Some object of the present invention enables adjustment of individual segments to suit inside diameter of the tube at various positions.
[0028] Some object of the present invention permits application of torque individually to each segment to lock in a desired position.
[0029] Some object of the present invention enables easy replacement of the segment in case of damage.
,CLAIMS:
1. An expansion mandrel (100) for clamping a tube from inside comprises:
a splitted ring (102) configured for mounting plurality of segments (104) circumferentially;
a screw (106) mounted on said splitted ring (104) is configured to interlock with said segment (104) ;
a nut (108) configured for fastening said screw (106) at a pre-determined position; and
a dowel pin (110) configured to be inserted in hole (110) provided on said splitted ring (102) for locking rotary movement of said segment (104) interlocked with said screw (106).

2. The expansion mandrel (100) as claimed in claim 1, wherein said screw (106) is configured with a groove (112) for receiving said dowel pin (110) to interlock said segment (104).

3. The expansion mandrel (100) as claimed in claim 1, wherein said screw (106) is configured to translate rotary motion into linear motion of said segment (104).

4. The expansion mandrel (100) as claimed in claim 1, wherein said screw (106) is configured to be hexagonal socket headed or an allen screw.

5. The expansion mandrel (100) as claimed in claim 1, wherein said plurality of segments (104) are configured for clamping on inner side of said tube to prevent deformation of said tube during machining.

6. The expansion mandrel (100) as claimed in claim 1, wherein said nut (108) is configured to be hexagonal.