Claims:1. A cupping test apparatus (100) comprising:
an upper die (106);
a lower die (108) configured to move relative to the upper die (106); and
a positioning mechanism (102) configured to align a sheet sample (101) at the center of the lower die (108), wherein the positioning mechanism (102) comprises:
at least three spring loaded pins (104a, 104b, 104c) disposed on an upper surface (112) of the lower die (108).
2. The cupping test apparatus (100) as claimed in the claim 1, wherein the at least three spring loaded pins (104a, 104b, 104c) includes a first spring loaded pin (104a), a second spring loaded pin (104b), and a third spring loaded pin (104c).
3. The cupping test apparatus (100) as claimed in the claim 2, wherein each of the at least three spring loaded pins (104a, 104b, 104c) are provided at an equal position on the upper surface (112) of the lower die (108).
4. The cupping test apparatus (100) as claimed in the claim 1, wherein the at least three spring loaded pins (104a, 104b, 104c) retract within the lower die (108), as the lower die (108) is moved relative to the upper die (106).
5. The cupping test apparatus (100) as claimed in the claim 1, wherein the sheet sample (101) is a circular sample and the at least three spring loaded pins (104a, 104b, 104c) are positioned in such a way that they act as tangent to the circumference of the circular sample.
6. The cupping test apparatus (100) as claimed in the claims 1 and 5, wherein the positioning mechanism (102) provides an effective way of carrying out flat bottom cup experiment with symmetric earing for an anisotropic sheet sample (101).
7. The cupping test apparatus (100) as claimed in the claim 1, wherein each of at least three spring loaded pins (104a, 104b, 104c) is made of low carbon steel.
8. A positioning mechanism (102) configured to align a sheet sample (101) at the center of a lower die (108) of a cupping test apparatus (100) comprises:
at least three spring loaded pin (104a, 104b, 104c) disposed on an upper surface (112) of the lower die (108), wherein the sheet sample (101) is a circular sample and the at least three spring loaded pins (104a, 104b, 104c) are positioned in such a way that they act as tangent to the circumference of the sheet sample (101).
9. The positioning mechanism (102) as claimed in the claim 8, wherein each of the at least three spring loaded pins (104a, 104b, 104c) are provided in equal position on the upper surface of the lower die (108).
, Description:FIELD OF INVENTION
[0001] The present invention relates to a positioning mechanism of a cupping test apparatus and more particularly, to the positioning mechanism provided on a lower die of the cupping test apparatus.

BACKGROUND
[0002] Automotive applications often experience state of stress in drawing deformation. Cup drawing is a classic example of such phenomenon. Earing is one of the major defects observed during deep drawing process due to anisotropic nature of sheet metal. Earing is defined as formation of trough and crust on uppermost portion of deep drawn cup. This phenomenon is observed while carrying out flat bottom cupping test. The test is carried out to determine the ear formation through punching followed by deep drawing of sheet metal blanks into hollow cylindrical cup.
[0003] In this test, a blank of circular sheet metal is used. It is required to keep the sample exactly at the center of the tool. The center of the cylindrical punch should match or coincide with the center of the circular sheet metal blank. After drawing the cup, the earing tendency is determined. The average height of the ear peaks and valleys is measured. Figure 1 shows the way height of peaks and valleys are measured. The ear height in the form of percent is calculated. To check the accuracy of various anisotropic yield criterion during cupping test simulation study, it is important to carry out flat bottom cupping test with sample positioned perfectly at the center of the cylindrical punch.
[0004] One such example of tool which can center the circular sheet metal blank is shown in Figure 2, wherein the tool has a provision of spring-loaded ring with three thin metal strips. When the ring is rotated, the metal strips rotate about a pivot point and all three together places the sample at the center. However, in this set up quite often the metal strip go under the circular sample because the sample surface not perfectly flat. This results in non-uniform clamping load on the sample due to the strip present below it. This makes the experiment invalid. For a valid experiment it is required to have a uniform clamping load throughout the sample after the sample is positioned at the tool center.
OBJECTIVE OF INVENTION
[0005] It is an object of the invention to provide a positioning mechanism on a lower die of a cupping test apparatus which ensures perfect placement of circular sample at the center of the tool and perform a valid experiment.
SUMMARY OF INVENTION
[0006] This summary is provided to introduce concepts related to a positioning mechanism of cupping test apparatus. The concepts are further described below in the detailed description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.
[0007] In one aspect of the present invention, a cupping test apparatus is provided. The cupping test apparatus comprises a lower die and an upper die. The lower die is configured to move relative to the upper die. The cupping test apparatus also comprises a positioning mechanism configured to align a sheet sample at the center of the lower die. The positioning mechanism comprises at least three spring loaded pins disposed on an upper surface of the lower die.
[0008] In an embodiment, the at least three spring loaded pins includes a first spring loaded pin, a second spring loaded pin, and a third spring loaded pin.
[0009] In an embodiment, each of the at least three spring loaded pins are provided at an equal position on the upper surface of the lower die.
[0010] In an embodiment, the at least three spring loaded pins retract within the lower die as the lower die is moved relative to the upper die.
[0011] In an embodiment, the sheet sample is a circular sample and the at least three spring loaded pins are positioned in such a way that they act as tangent to the circumference of the sheet sample.
[0012] In an embodiment, the positioning mechanism provides an effective way of carrying out flat bottom cup experiment with symmetric earing for an anisotropic sheet sample.
[0013] In an embodiment, each of the at least three spring loaded pins is made of low carbon steel with surface hardened 45-50 RC.
[0014] In another aspect of the present invention, a positioning mechanism configured to align a sheet sample at the center of a lower die of a cupping test apparatus is provided. The positioning mechanism comprises at least three spring loaded pin disposed on an upper surface of the lower die. The sheet sample is a circular sample and the at least three spring loaded pins are positioned in such a way that they act as tangent to the circumference of the circular sample.
[0015] In an embodiment, each of the at least three spring loaded pins are provided in equal position on the upper surface of the lower die.
[0016] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Figure 1 illustrates an earing defect observed during deep drawing process (known in the art).
[0018] Figure 2 illustrates a prior art lower die (known in the art).
[0019] Figure 3 illustrates a view of a cupping test apparatus comprising an upper die and a lower die, according to an embodiment of the present invention;
[0020] Figure 4a illustrates a view of the lower die comprising a positioning mechanism, according to an embodiment of the present invention;
[0021] Figure 4b illustrates a sectional view taken along line B-B of the lower die of Figure 4a, according to an embodiment of the present invention; and
[0022] Figures 5a and 5b illustrate different views of a sheet sample being positioned on the lower die, according to an embodiment of the present invention.
[0023] The drawings referred to in this description are not to be understood as being drawn to scale except if specifically noted, and such drawings are only exemplary in nature.

DETAILED DESCRIPTION
[0024] The detailed description of various exemplary embodiments of the disclosure is described herein with reference to the accompanying drawings. It should be noted that the embodiments are described herein in such details as to clearly communicate the disclosure. However, the amount of details provided herein is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0025] It is also to be understood that various arrangements may be devised that, although not explicitly described or shown herein, embody the principles of the present disclosure. Moreover, all statements herein reciting principles, aspects, and embodiments of the present disclosure, as well as specific examples, are intended to encompass equivalents thereof.
[0026] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising”, “includes” and/or “including,” when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof.
[0027] It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may, in fact, be executed concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved.
[0028] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, e.g., those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
[0029] Figure 3 illustrates a cupping test apparatus (100), according to an embodiment of the present invention. The cupping test apparatus (100) comprises an upper die (106) and a lower die (108). The lower die (108) is configured to move relative to the upper die (106). The lower die (108) is provided with an aperture (103) through which a punch (105) of the cupping test apparatus (100) extends.
[0030] Referring to Figures 4a and 4b, the cupping test apparatus (100) comprises a positioning mechanism (102). In an embodiment, the positioning mechanism (102) is provided on the lower die (108). The positioning mechanism (102) is configured to align a sheet sample (101) (shown in Figure 4b) at the center of the lower die (108), thereby providing an effective way of carrying out flat bottom cup experiment with symmetric earing for the anisotropic sheet sample (101). The positioning mechanism (102) comprises at least three spring loaded pins (104a, 104b, 104c) disposed on an upper surface (112) (also shown in Figure 3) of the lower die (108). The at least three spring loaded pins (104a, 104b, 104c) includes a first spring loaded pin (104a), a second spring loaded pin (104b), and a third spring loaded pin (104c).
[0031] In the illustrated embodiment, each of the at least three spring loaded pins (104a, 104b, 104c) are provided at an equal position on the upper surface of the lower die (108). Alternatively, each of the at least three spring loaded pins (104a, 104b, 104c) may be provided at any position relative to one another on the upper surface (112) of the lower die (108), without limiting the scope of the invention.
[0032] The at least three spring loaded pins (104a, 104b, 104c) retract within the lower die (108) as the lower die (108) is moved relative to the upper die (106). In an embodiment, the sheet sample (101) is a circular sample and the at least three spring loaded pins (104a, 104b, 104c) are positioned in such a way that they act as tangent to the circumference of the circular sample. The at least three spring loaded pins (104a, 104b, 104c) of the positioning mechanism (102) provides an effective way of carrying out flat bottom cup experiment with symmetric earing for the anisotropic sheet sample (101). Each of at least three spring loaded pins (104a, 104b, 104c) is made of low carbon steel with surface hardened 45-50 RC.
[0033] Referring to Figures 5a and 5b, different views of the sheet sample (101) being positioned on the lower die (108) are illustrated. As seen in Figures 5a and 5b, at least portion of the sheet sample (101) comes into contact with at least two spring loaded pins of the at least three spring loaded pins (104a, 104b, 104c) during placement of the sheet sample (101) onto the lower die (108). As these two spring-loaded pins act as tangent to the circumference of the circular sheet sample (101), the sheet sample (101) of 100 mm diameter aligns itself such that it gets placed at the center. The at least three spring loaded pins (104a, 104b, 104c) are so located on the lower die (108) that curved surfaces of the at least three spring loaded pins (104a, 104b, 104c) are tangent to the circular sheet sample (101) of 100mm diameter with its center coinciding with the center of the tool or punch (105). The position of the at least three spring loaded pins (104a, 104b, 104c) help locate the sheet sample (101) of diameter 100 mm exactly at the center of the cylindrical punch or tool (105). This results in performing the cup drawing experiment as it is done in cup drawing simulation study. The sheet sample (101) having anisotropy is fully drawn to get symmetric earing.
[0034] The present invention relates to positioning mechanism (102) provided on the lower die (108) which facilitates in aligning the sheet sample (101) at the center of the lower die (108). The lower die (108) has no metal strips, as compared to the prior art shown in Figure 2. The positioning mechanism (102) comprising the at least three spring loaded pins (104a, 104b, 104c) are positioned in such a way that they act as tangent to the circumference of the sheet sample (101). Uniform clamping load is applied throughout the sheet sample (101). By utilizing the lower die (108) having the positioning mechanism (102), the circular sheet sample (101) is placed exactly at the center of the cylindrical punch (105) resulting in symmetric earing for anisotropic sheet. This helps in close correlation of experiment with simulation study. Further, the design of lower die (108) is ergonomically safe and economic. It saves the time of experimentation as lot of time goes in ensuring centering if done visually.
[0035] Furthermore, the terminology used herein is for describing embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[0036] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[0037] While the foregoing describes various embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. The scope of the invention is determined by the claims that follow. The invention is not limited to the described embodiments, versions, or examples, which are included to enable a person having ordinary skill in the art to make and use the invention when combined with information and knowledge available to the person having ordinary skill in the art.