FIELD OF INVENTION
[0001] The present invention relates to a lower die of 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 circular sheet metal blank 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 or metal strips go under the circular sample. 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 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 which would be close to the simulation study.
SUMMARY OF INVENTION
[0006] This summary is provided to introduce concepts related to a lower die 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 an upper die and a lower die. The upper die configured to move relative to the lower die. The lower die comprises a first surface configured to align a sheet sample at the center of the lower die.
[0008] In an embodiment, the first surface is a tapered surface. In an embodiment, the lower die is provided with an aperture through which a punch of the cupping test apparatus extends.
[0009] In an embodiment, the first surface extends from an upper surface towards a second surface of the lower die.
[0010] In an embodiment, the first surface is a groove extending between the upper surface towards the second surface.
[0011] In an embodiment, the first surface aligns the sheet sample at the center of the lower die thereby providing an effective way of carrying out flat bottom cup experiment with symmetric earing for an anisotropic sheet sample.
[0012] In an embodiment, the sheet sample is a circular sample. In an embodiment, the sheet sample is of 100 mm diameter.
[0013] In an embodiment, the lower die (108) is made of hardened tool steel material with hardness varying from 58 to 64 HRC.

[0014] Other features and aspects of this disclosure will be apparent from the following description and the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Figure 1 illustrates an earing defect observed during deep drawing process (known in the art).
[0016] Figure 2 illustrates a prior art lower die (known in the art).
[0017] 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;
[0018] Figure 4a illustrates a view of the lower die, according to an embodiment of the present invention;
[0019] Figure 4b illustrates a sectional view taken along line A-A of the lower die of Figure 4a, according to an embodiment of the present invention; and
[0020] 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.
[0021] 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
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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. In an embodiment, the lower die (108) is made of hardened tool steel material with hardness varying from 58 to 64 HRC. Alternatively, the lower die (108) may be

made from any material, including, but not limited to steel, alloy steel etc., without any limitations.
[0028] Referring to Figures 4a and 4b, the lower die (108) comprises a first surface (102). The first surface (102) extends from an upper surface (110) towards a second surface (112) of the lower die (108). In one embodiment, the first surface (102) is a tapered surface (herein after alternatively referred to as tapered surface (102)). The first surface (102) is configured to align a sheet sample (101) at the center of the lower die (108). The first surface (102) aligns the sheet sample (101) at the center of the lower die (108) thereby providing an effective way of carrying out flat bottom cup experiment with symmetric earing for an anisotropic sheet sample (101). In one embodiment, the sheet sample (101) is a circular sample of 100 mm diameter. In the illustrated embodiment, the first surface (102) makes an angle 148.11 deg with the second surface (112). Alternatively, the first surface (102) may make any angle between in the range between 90 to less than 180 deg with the second surface (112), without any limitations.
[0029] In another embodiment, the first surface (102) may be a groove (not shown) extending between the upper surface (110) towards the second surface (112).
[0030] 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 portion of the first surface (102) during placement of the sheet sample (101) onto the lower die (108). As the first surface (102) is a tapered surface, the sheet sample
(101) aligns itself such that it helps place the circular sheet sample (101) of 100 mm diameter at the center. The first surface (102) is so designed that the least diameter is of 100 mm places the sheet sample (101) of 100 mm diameter with its center coinciding with the center of the tool or punch (105). The tapered surface
(102) helps locate the sheet sample (101) of diameter 100mm 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.

[0031] The present invention relates to the lower die (108) having the tapered surface (102) 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 tapered surface (102) is positioned in such a way that the sheet sample (101) is placed exactly at the center. Uniform clamping load is applied throughout the sample. By utilizing the lower die (108) having the tapered surface, the circular sheet sample (101) is placed exactly at the center of the cylindrical punch 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.
[0032] 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.
[0033] 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.
[0034] 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.

We claim:
1. A cupping test apparatus (100) comprising:
an upper die (106);
a lower die (108), wherein the lower die (108) is configured to move relative to upper die (106) wherein the lower die (108) comprises a first surface (102) configured to align a sheet sample (101) at the center of the lower die (108).
2. The cupping test apparatus (100) as claimed in the claim 1, wherein the first surface (102) is a tapered surface.
3. The cupping test apparatus (100) as claimed in the claim 1, wherein the lower die (108) is provided with an aperture (103) through which a punch (105) of the cupping test apparatus (100) extends.
4. The cupping test apparatus (100) as claimed in the claims 1 to 3, wherein the first surface (102) extends from an upper surface (110) towards a second surface (112) of the lower die (108).
5. The cupping test apparatus (100) as claimed in the claim 4, wherein the first surface (102) is a groove extending between the upper surface (110) towards the second surface (112).
6. The cupping test apparatus (100) as claimed in the claim 1, wherein the first surface (102) aligns the sheet sample (101) at the center of the lower die (108) thereby providing 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 claims 1 and 6, wherein the sheet sample (101) is a circular sample.
8. The cupping test apparatus (100) as claimed in the claims 1 to 7, wherein the sheet sample (101) is of 100 mm diameter.

9. The cupping test apparatus (100) as claimed in the claim 4, wherein the first surface (102) makes an angle 148.11 deg with the second surface (112).
10. The cupping test apparatus (100) as claimed in the claim 1 to 9, wherein the lower die (108) is made of hardened tool steel material with hardness varying from 58 to 64 HRC.