Cylindrical tool for thin sample grinding and polishing

Abstract

The design of a stainless-steel cylindrical tool for manual grinding and polishing of cement-based thin sample (two cylinders one within the other, connected by the movable threaded holder with a plate, that passes through the middle) enables very precise removal of sample layers to its thickness of 1-mm ( 1/32 inch) and less. The squared, young aged sample rests on the circular plate on a holder, that can be slowly and safely rotated during thin layer removal, to obtain a smooth and flat sample surface, which can produce sharp digital images in ESEM, necessary for detailed and accurate image analysis. The cylindrical tool can be reassembled. It is reusable, easy to maintain and clean. Its design is practical since inner cylinder can be replaced if damaged, with the identically designed inner cylinder or with differently designed inner cylinder adjusted to another sample size.

Claims

1. Stainless steel cylindrical tool for grinding and polishing thin cement-based samples to 1-mm ( 1/32 inch) thickness and below, further comprising an stainless steel outer cylinder with the engraved rounded scale on its upper side, a threaded vertical opening through the middle of solid part, the circular inner opening of the half-height of outer cylinder at the bottom side that is circularly coated with thin rectangular metal (A1) sheets at a certain distance that are fixed to the interior of outer cylinder in the rounded slots, and ‘ring’-like layer around the lower outer part.

2. Outer cylinder as in claim 1, further comprising the stainless steel inner cylinder(s) to fit in the outer cylinder in the round opening, one at the time, with vertical threaded opening through the middle of solid part.

3. Outer and inner cylinder(s) as in claim 2, further comprising a threaded stainless steel holder with the extension in the form of a circular plate at one end, and a notch with a marker at the other end.

4. Inner cylinder(s) as in claim 2, further comprising the specially shaped squared opening at the bottom, sufficiently deep for fitting in the rounded plate on a holder and sample(s) of two different sizes, one at the time, surrounded by the four inner “walls” with engraved horizontal short marks on all “walls”, with four open rounded corners between four “walls”, for fitting in the four corners of the thin sample(s) that rests on the plate(s), when grinding and polishing is performed.

Description

4. DETAILED DESCRIPTION OF INVENTION

[0034] I. The stainless steel cylindrical tool is designed to hold an early aged (2-3 days old and above) thin sample 2 mm ( 1/16 inch) thick during manual grinding and polishing to 1-mm ( 1/32 inch) thickness or less, without damaging or breaking it. The invention of cylindrical tool followed the invention of the stainless-steel mould for thin sample casting from the same inventor*.

[0035] II. The stainless steel cylindrical tool consists of three parts: outer (larger) cylinder, FIGS. 1, 1A, 1B and FIGS. 10, 10A, 10B, inner (smaller) cylinder, FIGS. 2, 2A-2C, and holder with a plate, FIGS. 3, 3A, 3B (for the sample size 10×10×2 mm or ⅜×⅜× 1/16 inch). Both cylinders can be disassembled and reassembled again except for the holder and plate as they form a whole. The disassembling and reassembling enable a thorough cleaning of the cylindrical tool after sample preparation. It also gives the possibility of the insertion of another inner cylinder (FIGS. 4, 4A-4C) with the holder and plate (FIGS. 5, 5A, 5B) for the larger sample 30×30×2 mm ( 9/8× 9/8× 1/16 inch) preparation.

[0036] III. The total height of the cylindrical tool is determined by the total height of the outer cylinder, which is 45 mm (9 3/16 inch). The outer cylinder has an additional ‘ring’-like outer layer (FIGS. 1, 10, 6, 7) as a result of mechanical steel processing, where this part of outer cylinder is left as not-fully-polished. As a consequence, the diameter of outer cylinder is reduced from ϕ60 (9 2/8 inch) at the bottom and up to 11 mm (⅜ inch) height, to ϕ58 (3 6/8 inch) at the remaining height of 34 mm (1⅛ inch). The ‘ring’-like layer enables easier handling of the heavy tool during grinding and polishing.

[0037] IV. The inner cylinder is 22.5 mm (9 3/32 inch) high, with diameter ϕ39.5 ( 3/2 inch). Two inner cylinders, FIGS. 2, 2A-2C vs. FIGS. 4, 4A-4C, differ in the design and the size of the inner opening, which is created as a free space for the vertical movement of circular plate (FIGS. 2C, 4C).

[0038] V. The smooth fitting of any of two inner cylinders to the outer cylinder is done by making a circular opening ϕ40.5 ( 3/2 inch) and 22.5 mm (9 3/32 inch) high in the outer cylinder (FIGS. 1A and 10A) for the placement of inner cylinder(s), FIGS. 2, 4, 6, 7. Easier pulling out of the inner cylinder and the prevention of any friction between outer and inner cylinder during the tool disassembling or reassembling, is done by vertically inserting nine thin A1 sheets 5 mm ( 3/16 inch) wide, 22.5 mm (9 3/32 inch) high at the circular distance of 8 mm ( 5/16 inch) in the circular opening, fixed to the rounded 3 mm (⅛ inch) high slot, FIG. 1A, 10A.

[0039] VI. The rounded holder ϕ8 ( 5/16 inch) is 45 mm (9 3/16 inch) long, merged with the rounded plate ϕ10 (⅜ inch) or ϕ30 ( 9/8 inch), which is 3 mm (⅛ inch) thick, FIGS. 3, 5. The plate holder has horizontal threads at each 0.25 mm ( 3/320 inch), from top of the holder till 2 mm ( 1/16 inch) above the plate due to mechanical processing. The same threads are also engraved in the outer cylinder opening (height 17.5 mm or ⅝ inch) and inner cylinder opening (height 14.5 mm or ½ inch), FIGS. 1A, 10A, 2A, 4A, in order to assemble both cylinders with the holder. The holder and plate can rotate with a help of a notch that is 1 mm ( 1/32 inch) wide and 8 mm long ( 5/16 inch), FIGS. 3A, 5A, 6A, 7A, and a screwdriver.

[0040] VII. The circular plate, FIGS. 3B, 5B, 6, 7 serves as a sample carrier. In order to easily move holder and the plate up and down, through the vertical threaded hole in the cylinders, the plate must be rounded, not squared, although the cement-based samples are squared. The cylindrical shape of the tool is also more practical for handling, in comparison to any other shape. In order to control a thickness of a sample-layer during its removal, the rounded scale with numbers (0-4) is engraved at the top of the outer cylinder (FIG. 1B, 10B, 6A, 7A), where the holder of the rounded plate sticks out for 3 mm (⅛ inch), FIGS. 6, 7.

[0041] VIII. A smaller marker 4 mm (⅛ inch) long engraved vertically to the notch, is used to mark one of the numbers on the scale (0-4), FIGS. 3A, 5A, 6A, 7A during plate rotation. The depth of the bottom opening in inner cylinder(s) is 8 mm ( 5/16 inch), FIGS. 2A, 4A, while the size of plate (ϕ10 or ⅜ inch), FIG. 3B or ϕ30 ( 9/8 inch), FIG. 5B, ‘dictates’ the width of the openings in both inner cylinders, FIGS. 2C, 4C, 6B, 7B.

[0042] IX. The five short horizontal marks are engraved on the inner “walls” (edges) around the openings in the inner cylinders, FIGS. 2A, 4A. They are about 5 mm ( 3/16 inch) long. They are used to help measuring (doublecheck) the sample thickness during sample layer removal. The four small rounded openings (ϕ4 or 5/32 inch), on the bottom of the inner cylinder for 10×10×2 mm (⅜×⅜× 1/16 inch), FIGS. 2C, 6B are made for the safety of the sample corners, in order to prevent the sample corners from breaking, during grinding and polishing. For the larger sample (30×30×2 mm or 9/8× 9/8× 1/16 inch), the four larger openings are left at four corners from the outside, FIGS. 4C, 7B.

[0043] X. The cylindrical tool is developed in a few steps almost like trial-and-error method: by adding the possibility of disassembling of cylinders, by reducing the thickness of threads, by enabling the four open corners for the sample corners at the bottom of inner cylinder, by engraving the circular scale at the outer cylinder, notch and the marker at one of the holders ends.

[0044] XI. The grinding and polishing procedure is as follows. The tool is assembled such that (one of) inner cylinder is placed in the outer cylinder and fasten with the threaded holder (with a circular plate). In the assembled cylindrical tool, the plate on a holder is first elevated to the same level of the bottom surface of inner and outer cylinder (FIGS. 6B, 7B), with a help of the notch, screwdriver and scale, so that the sample can be placed on its surface. To prevent the sample from falling off the plate, a barely visible layer of a special paste can be applied to the plate surface for a slight sample attachment, if the dry (dry-cured) cement-based sample is tested. If the sample is wet (wet-cured in water), then it is not necessary to use any paste since the thin water layer keeps sample ‘fixed’ to the plate surface.

[0045] XII. The plate with a sample is then elevated such that first layer of approximately 0.25 mm ( 1/128 inch), sticks above the bottom of the assembled cylindrical tool surface (thickness controlled via scale and engraved inner notches). The first layer is removed by grinding on the grinding and polishing machine, with two wheels with SiC sandpapers of different granulations. For the initial grinding for the layer removal of 0.25 mm ( 1/128 inch) the SiC paper grit 320 is used. Then the grinding is switched to the SiC paper grit 500. When the grinding is completed and the 1-2 layers of 0.25 mm ( 1/128 inch) are removed, the sample is taken out from the elevated plate for the thickness measurements in a special device with a needle. If the newly measured sample thickness is about 1.5 mm ( 1/16 inch), the sample is returned to the plate and polishing is performed until the sample thickness reaches 1 mm ( 1/32 inch). The polishing is done on SiC paper grit 1200. After polishing of new 1-2 layers, the sample is again taken to the special needle device for the thickness measurements. Grinding and polishing can be done even to the thickness of 0.5 mm ( 1/64 inch) of cement-based sample.

[0046] XIII. Grinding and polishing is done by hand, in a few steps, carefully and very precisely holding the cylindrical tool vertically to avoid damaging the sample and to obtain the equally thick sample. The duration of grinding and polishing depends on the sample age, way of curing (wet or dry) and its cement-based composition (concrete/mortar/cement paste). If it is 2-3 days old, the sample can be polished to 1 mm in 10-12 min. If the sample is older (7 days and beyond), it can take up to 20 min.

[0047] XIV. Due to the construction of lower part of inner cylinders 8 mm ( 5/16 inch) high, it is possible to place cement-based samples up to 5 mm thickness. The inventor* believes that such stainless steel cylindrical tool could be possibly used for grinding and polishing of samples made of other materials as long as they do not damage the cylindrical tool. *Inventor: MSc. Dragana Janković, Structural Civil Engineer, UCF, FL