Device for Preparing Sheet Specimens

Abstract

The device for preparing sheet specimens comprises a base (1) for placing on it a sheet specimen (2) and a cutting punch (3) for cutting sheared cracks or sharp notches in said sheet specimen (2). Preferably, said cutting punch (3) comprises a beveled lower end (31) and/or a central vertical groove (32). Permits the cracks to be formed cutting directly the sheet, and not by cyclic loading, so that the preparation of the sheet specimen takes a reduced time in comparison with the conventional devices.

Claims

1. A combination comprising a sheet specimen and a device for preparing the sheet specimen, comprising: a base (1) having centering means (11) (12) for centering a sheet specimen (2), wherein said centering means comprise a plurality of holes (11) inside which pins (12) protruding from the base (1) are housed, a cutting punch (3) comprising two cutting portions (34) divided by a central vertical groove (32) with a length greater than a width thereof and a cutting zone sized within and disposed between the cutting portions (34) of the cutting punch (3), and a closed end for cutting sheared cracks in the zone between the notches of the sheet specimen (2) wherein each of the cutting portions (34) defines an obtuse angle with respect to the vertical axis (A) of the cutting punch (3); and the sheet specimen produced by the device having sheared cracks disposed between the notches of the sheet specimen and corresponding to the dimensions of the cutting zone of the device.

2. The combination for preparing the sheet specimen according to claim 1, wherein said cutting punch (3) comprises a beveled lower end (31).

3. The combination for preparing the sheet specimen according to claim 1, wherein the device also comprises a pressing element (4) for pressing the sheet specimen (2) against the base (1).

4. The combination for preparing the sheet specimen according to claim 3, wherein said pressing element (4) is placed in a central vertical groove (32) of the cutting punch (3).

5. The combination for preparing the sheet specimen according to claim 1, wherein said cutting punch (3) is mounted on a pressing frame (5).

6. The combination for preparing the sheet specimen according to claim 5, wherein said pressing element (4) is also mounted on said pressing frame (5).

7. The combination for preparing the sheet specimen according to claim 2, wherein said cutting punch (3) comprises a central vertical groove (32) perpendicular to the sheet specimen.

8. The combination for preparing the sheet specimen according to claim 1, wherein a pressing element (4) is placed in said central vertical groove (32) of the cutting punch (3) for pressing the sheet specimen (2) against the base (1).

9. The combination for preparing the sheet specimen according to claim 1, where the sheet specimen has a rectangular shape.

10. The combination for preparing the sheet specimen according to claim 1, wherein the sheet specimen has notches in opposite sides of a larger side of the rectangular shape.

11. A method to prepare a sheet specimen comprising: securing a sheet specimen to a base (1) having centering means for centering a sheet specimen (2); centering the sheet specimen using the centering means; holding and pressing the sheet specimen (2) in secure engagement with the base (1) with a pressing element (4) lowered onto the sheet specimen in combination with the base (1); and directly cutting cracks in the sheet specimen (2) while pressed together with the base (1) by lowering a cutting punch (3) comprising two cutting portions (34) divided by a central vertical groove (32) with a length greater than a width thereof to create a cutting zone sized within and disposed between the cutting portions (34) of the cutting punch (3); and producing the sheet specimen (2) having sheared cracks disposed in the area of the sheet specimen (2) corresponding to the cutting zone.

12. The method of claim 11, wherein the centering means comprises a plurality of holes (11) inside which pins (12) protruding from the base (1) are housed.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0018] For a better understanding the above explanation and for the sole purpose of providing an example, some non-limiting drawings are included that schematically depict a practical embodiment.

[0019] FIG. 1 is a perspective view of the device for preparing sheet specimens according to the present invention.

[0020] FIG. 2 is a cross-sectional view of the device for preparing sheet specimens according to the present invention.

[0021] FIG. 3 is a frontal elevation view of the cutting punch of the device for preparing sheet specimens according to the present invention.

[0022] FIG. 4 is a side cross-section elevation view of the cutting punch of the device for preparing sheet specimens according to the present invention.

[0023] FIG. 5 is an elevation view of a detail of the contact zone between the cutting punch and the sheet specimen in the device for preparing sheet specimens according to the present invention.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0024] The device for preparing sheet specimens according to the present invention can be seen in FIG. 1 in a perspective view.

[0025] The device according to the present invention comprises a base 1 on which a sheet specimen 2 is placed and a cutting punch 3, which makes little cracks on the sheet specimen 2, as will be explained hereinafter.

[0026] The sheet specimen 2 is conventional (it can be made e.g. from steel) and its shape can be seen in this FIG. 1. Preferably, the sheet specimen 2 has a rectangular shape with curved notches provided in opposite sides of the larger sides of the rectangle, e.g. in a centered position. This way, the little cracks will be made in the zone between these curved notches.

[0027] For granting the correct positioning of the sheet specimen 2 on the base 1, and therefore the correct positioning of the little cracks, the base 1 comprises centering means, which can be seen in more detail in FIG. 2.

[0028] These centering means comprise a plurality of holes 11 placed in the base 1 inside which pins 12 are housed. These pins 12 protruding slightly from the base 1, so that these pins 12 are also housed inside corresponding through holes 21 of the sheet specimens 2.

[0029] These centering means permit a very simple and accurate positioning of the sheet specimen 2 in the desired position on the base 1.

[0030] The configuration of the cutting punch 3 can be seen more clearly from FIGS. 3 and 4.

[0031] The cutting punch 3 comprises a beveled lower end, e.g. having a beveled portion defining an angle of about 45 with respect to the vertical axis A of the cutting punch 3.

[0032] The cutting punch 3 also comprises a central vertical groove 32. This central vertical groove 32 divides the lower end of the cutting punch 3 in two cutting portions 34, which are symmetrical with respect the vertical axis A of the cutting punch and define an obtuse angle with said vertical axis A. The obtuse angle can range, e.g. between 100 and 120, but can be any obtuse angle that permits a correct cutting of the little cracks in the sheet specimen 2.

[0033] The device for preparing sheet specimens according to the present invention also comprises a pressing element 4 (shown in FIG. 5) for holding and pressing the sheet specimen 2 against the base 1.

[0034] This pressing element 4, and preferably also the cutting punch 3, is mounted on a pressing frame 5, which is not shown in detail, and whose function is just lowering and raising the pressing element 4 and the cutting punch 3, as described hereinafter.

[0035] The operation of the device for preparing sheet specimens according to the present invention is very simple.

[0036] Firstly, the sheet specimen 2 is placed on the base 1 in the correct position. To this end, the pins 12 are used, so that the pins 12 are housed inside the through holes 21 of the sheet specimen 2.

[0037] Once the sheet specimen 2 is positioned in its correct position, the pressing element 4 and the cutting punch 3 are lowered by conventional means, so that little sheared cracks are cut in the zone between the notches of the sheet specimen 2.

[0038] After that, the sheet specimen 2 can be removed from the base 1 and used for mechanical testing purposes.

[0039] Even though reference has been made to a specific embodiment of the invention, it is obvious for a person skilled in the art that the device described herein is susceptible to numerous variations and modifications, and that all the details mentioned can be substituted for other technically equivalent ones without departing from the scope of protection defined by the attached claims.