GB2520672A

GB2520672A - A die and punch cutter

Info

Publication number: GB2520672A
Application number: GB1317759.7A
Authority: GB
Inventors: Peter Shorrock
Original assignee: CS TECHNICAL SERVICES Ltd
Current assignee: CS TECHNICAL SERVICES Ltd
Priority date: 2013-10-07
Filing date: 2013-10-08
Publication date: 2015-06-03
Also published as: GB201317722D0; GB201317759D0

Abstract

A die and punch cutter 32 for releasing rods or elongate elements (22, Fig. 1), respective ends of which extend through respective holes (14) in a grid (10), which are arranged in a honeycomb pattern. The cutter comprises a die 40, a punch 32 and a drive 44 coupled to the die and the punch to drive them towards one another for cutting portions of the grid, and away from one another to ready them for the next cutting operation. The punch is provided with three cutting edges (68, 70, 72, Fig. 9) corresponding in their relative positioning to three mutually adjacent bridging portions of the grid. Also claimed is a die and punch cutter in which the die is provided with hollows or recesses (58, 60, 62, Fig. 8) to accommodate at least one of the upper ends of the rods extending through the grid. The punch is located below the die when the cutter is in use. Also claimed is a method of cutting a grid to release elongate elements using a die and punch cutter made as disclosed. The inventions are particularly suitable for use in decommissioning nuclear power stations, wherein spent fuel rods or the like may be held in position by a metal grid.

Description

[0001] A die and punch cutter [0002] The present invention relates to a die and punch cutter.

[0003] An example of such a cutter is disclosed in JP55825529B2 [0004] A problem with such a cutter is that it is too cumbersome for certain applications. For example, in the decommissioning of nuclear pcwer stations, a problem is encountered with stainless steel rods or elongate elements held upright in their respective positions by a metal grid at their upper ends. Such rods or elements may be spent nuclear fuel rods or elements, control rods or elements, breeder rods or elements, or thermalising rods or elements. The grid comprises a plate formed with a plurality of through-holes arranged in a honeycomb pattern. Thus any and every cne hole within the pattern Is surrounded by six other hcles, each equidistant from that one hole. Bridging portions of the grid extend between and partly define respective pairs of immediately adjacent holes, and any three mutually adjacent bridging portions meet at a hub porticn of the grid defined by respective portions of respective Internal surfaces of the grid which define three mutually adjacent holes.

Upper ends of rods or elongate elements extend through respective holes of the grid. Normally, such a rod or element can be lifted away from the grid simply by grasping its upper end, and lifting it so that it slides cut of its hole in the grid. After use, however, some of the rods or elements have bulged, or have accumulated corrosive deposits on them, and cannot be slid out of the grid in this way. Such rods cr elements therefore need to be cut free from the grid. Hcwever, existing cutters, such as the one disclosed In JPS5825529B2, or scissor type cutters, are too cumbersome for this work, and would do dangerous damage to the rods or elements as well as the grid if used.

[0005] The present invention seeks to provide a remedy to this problem.

[0006] Accordingly a first aspeot of the present invention is direoted to a die and punch outter for releasing rods or elongate elements, respective ends of which extend through respective holes in a grid, which holes are arranged in a honeycomb pattern, the cutter oomprising a die, a punch, and a drive coupled to the die and the punch to drive them towards one another for cutting portions of such a grid, and away from one another to ready them for the next outting operation, in which the punch is provided with three cutting edges corresponding in their relative positioning to three mutually adjaoent bridging portions of suoh a grid.

[0007] Such a cutter provides the advantage that in one cutting operation, a hub portion of the grid, as defined hereinbefore, is cut clean away from the grid.

Successive cutting operations along a line of suoh holes may out two such hub portions away at each outting operation. Each such cutting operation therefore may be sufficient to free a further element from the grid in a region of the grid where all the holes have respeotive element ends extending through them.

[0008] The die may be provided with three cutting edges oorresponding in position to those of the punch.

[0009] Advantageously the die is so dimensioned that the three cutting edges when in use can be located at positions corresponding to positions on the grid at which the bridging portions are narrowest.

[0010] This affords the advantage that a minimum of force is needed to remove such a hub portion.

[0011] Preferably, the punch is formed with two concave surfaces which lead away frcm one of the cutting edges and extend respectively to the other two cutting edges, the radius of curvature of the two concave surfaces being the same as or substantially the same as that of the holes in the grid which is intended to be cut by the cutter.

[0012] This enables the said one of the cutting edges to be inserted between two such elements the ends of which extend through two immediately adjacent holes of the grid respectively.

[0013] The die may be formed with two hollows capable of receiving respective ends of two adjacent such elements when the cutter is in use.

[0014] The punch may be provided with a portion having a uniform cross-section at least a part of which is substantially semicircular, from the middle of the periphery of which extends a portion of the punch which provides the three cutting edges, the radius of curvature of the semicircular part of the cross-section being the same or substantially the same as that of each hole of the grid.

[0015] This affords the advantage that the punch along with the rest of the cutter may be guided into the correct position by the remainder of one of the holes of the grid from which portions of the grid which define that one of the holes have already been cut.

[0016] The die may be provided with a hollow, or a third hollow, to receive that portion of the punch which has a uniform cross at least a part of which is semicircular.

[0017] Advantageously, the uniform cross-section may be substantially circular.

[0018] In the event that the ends of the rods or elongate elements project upwardly through the holes in the grid, it is desirable for the die to be above the punch - [0019] According to a second aspect of the present invention, there is provided a die and punch cutter for use in cutting a grid in which holes are formed and through which holes the upper ends of rods or elongate elements extend, the cutter comprising a die and a punch, in which the die is provided with hollows or recesses to accommodate at least one of those upper ends, and the punch is located below the die when the cutter is in use.

[0020] Such a cutter according to this second aspect of the present invention may have one or more of the features of the foregoing paragraphs setting out the first aspect of the present invention and optional features relating thereto.

[0021] The present invention extends to a method of cutting a grid to release elongate elements therefrom, respective ends of which extend through respective holes in the grid using a die and punch cutter made in accordance with the first or the second aspect of the present invention, with or without one or more of the optional features set out in the foregoing paragraphs in relation to those aspects of the present invention.

[0022] In such a method, the holes would be arranged in a honeycomb pattern if the cutter is in accordance with the first aspect of the present invention, but they may be in any pattern, honeycomb, sguare or other, if the cutter is in accordance with the second aspect of the present invention.

[0023] An example of a die and punch cutter made in accordance with the present invention, and a method of cutting elongate elements free from a grid using a cutter in accordance with the present invention, will now be described in greater detail with reference to the accompanying drawings, in which: [0024] Figure 1 shows a perspective view from above of a grid in whiob are held elongate elements; [0025] Figure 2 is a view of parts of what is shown in Figure 1, on a larger scale; [0026] Figure 3 shows a perspective view from above and to one side of such a grid with a cutter whioh embodies the present invention positioned ready to out portions of the grid; [0027] Figure 4 shows a perspective view from above and to the other side of such a grid and cutter, with a cover placed over the cutter and an element in the grid shown in Figure 3 being absent; [0028] Figure 5 shows the grid and the cutter shown in Figure 3 from one side and from underneath, on a larger scale; [0029] Figure 6 shows a perspective view from above and to one side of the cutter shown in Figures 3 and 5, on a larger scale; [0030] Figure 7 shows a perspective view of the cutter shown in Figure 6 from one side and below; [0031] Figure 8 shows a die of the cutter shown in Figures 6 and 7, from underneath; and [0032] Figure 9 shows a perspective view from one side and from above of a punch of the cutter shown in Figures 6 and 7, with other parts thereof, on a larger scale.

[0033] A metal grid 10 shown in Figure 1 comprises a metal plate 12 through which has been bored a multiplicity of holes 14 each of circular cross-section and each extending from one main face 16 of the plate 12 to the opposite main face thereof so that each hole is a through-hole. The holes are arranged in a honeycomb configuration or pattern. As a consequence, a portion of the grid 10 which constitutes a dividing wall between a pair of immediately adjacent boles 14 also constitutes a bridging portion 18 which extends between and partly defines those immediately adjacent holes 14. Each bridging portion 18 extends from one hub portion 20 of the grid 10 to another hub portion 20, so as to form a bridge between those hub portions 20. Because of the honeycomb pattern, any three mutually adjacent bridging portions 18 meet at a hub portion 20, the latter being defined by respective portions of respective internal surfaces of the grid 10 which define three mutually adjacent holes 14.

[0034] As can be seen in Figure 1, the grid 10 supports a number of upright circularly cross-sectioned stainless steei rods or elongate elements 22 at their upper ends 24. These rods 22 are slightly swollen or have corrosive deposits on them so they cannot simply be lifted upwardly out of the grid 10, and need to be out free therefrom.

[0035] The manner in which the die and punch cutter 32 shown in Figures 3 to 9 achieves this is illustrated in Figure 2. Thus the cutter 32 effects three outs at such positions as those labelled in Figure 2 as positions 26, 28 and 30, at the centres and therefore at the narrowest positions of three mutually adjacent bridging portions 18 of the grid 10 so as to enable the hub portion 20 of the grid 10 at which these three bridging portions 18 meet, to be removed.

[0036] The die and punch cutter 32 shown in Figures 3 to 9 has already effected a series of cuts through portions of the grid 10 which lie along a line 34, and in Figure 5 is being positioned to effect a cutting operation to remove the hub portion 36.

[0037] With reference to Figures 6 to 9, the die and punch cutter 32 comprises a die 40, a punch 42, and a drive 44 coupled to the die 40 and the punch 42 in such a fashion as to be able to move the die 40 and punch 42 towards one another with sufficient force to sheer portions of the grid 10 when the cutting operation is effected by the cutter 32.

[0038] The drive 44 comprises a main hydraulic cylinder 46,the body of the cylinder of which is connected to a cylinder support block 52 which is in turn solidly connected to the pillars 48 on which is mounted a sliding die support block 50 that is driven up and down the pillars 48 by the cylinder piston (not shown) connected to the support block 50. The die 40 fixed to the die support block 50 is driven towards the punch 42 which in turn is affixed to a punch support block 56 which in turn is fixed to the base of the pillars 48. As the die 40 is urged downwardly relative to the cutter 32, the die 40 engages the grid plate 10, whereafter continued hydraulic action moving the die 40 towards the punch 42 lifts the whole cutter 32 relative to the grid plate 10 as the punch 42 is forced upwardly relative to the grid plate 10 and onwards into the die 40.

[0039] A guide member 54 which is effective in guiding the cutter 32 into position ready for a cutting operation to be effected is also mounted on the pillars 48.

[0040] The punch 42 is mounted on the pillars 48 via an punch support block 56.

[0041] Details of the die 40 are shown in Figures 7 and 8. Thus it comprises three hollow cylindrical portions 58, 60, and 62. The internal cross section of each of these cylindrical portions is circular, the diameter of each hollow cylindrical portion corresponding to that of the internal diameter of the holes 14 in the grid 10. Furthermore, the hollows of these three cylindrical pcrtions have central axes which are generally upright and pass through an imaginary horizontal plane at the apices of an imaginary eguilateral triangle, in such a fashicn that the spacing between the hollows of the cylindrical portions correspond to the spacing between three mutually adjacent holes 14 in the grid 10. The die is oriented in such a fashicn that twc of its hollow cylindrical portions 58 and 60 are located in an intended forward position, with a third cylindrical portion 62 located rearwardly of these two forward cylindrical portions 58 and 60. The material from which the die 40 is made comprises tool steel.

[0042] The punch 42 comprises an elongate generally cylindrical upright member of uniform cross-section, and is made of tungsten carbide or tool steel. Its cross-section comprises a first part 64 which is generally circular, having a diameter very slightly less than that of one of the holes 14 in the grid 10, and a second part 66 extending forwardly of the first part 64 and having the general shape of an arrowhead. More especially it is provided with three cutting or shearing edges 68, 70 and 72 located at the apices of an imaginary equilateral triangle, with a spacing corresponding to the spacing between the oentres of three mutually adjacent bridging portions 18 of the grid 10. Two of the cutting edges 68 and 70 are immediately adjacent to the periphery of the circular part 64, the third outting edge 72 being located forwardly of the cutting edges 68 and 70. Continuing with a description of the cross-section of the punch 42, the cross-seotion is formed with two arcs 74 and 76 both having a radius of curvature equal or substantially equal to the radius of ourvature of eaoh hole 14 in the grid 10. One of the arcs 74 extends from the cutting edge 72 to the cutting edge 70, and the other of the arcs 76 extends from the cutting edge 72 to the cutting edge 68.

Respective portions of the two arcs 74 and 76 are substantially parallel at the cutting edge 72.

[0043] The centre of the imaginary equilateral triangle defined by the three cutting edges 68, 70 and 72 of the punch 42 lies on the central axis of the die 40.

The central region of the die 40 is a void, and portions of it which extend inwardly from its exterior between adjacent hollows of the die 40 terminate at respective cutting or shearing edges 78, 80 and 82 corresponding in position, looking directly from above or directly from underneath, substantially to the positions of the cutting edges 68, 70, and 72, but slightly outwardly therefrom so that the second part 66 of the punch 42 can be received within the central region of the die 40, and the first part 64 of the punch 42 can be received in the hollow of the cylindrical portion 62 of the die 40, with the cutting edges 68, 70, and 72 immediately adjacent to the shearing edges 78, 80 and 82 respectively.

[0044] The guide 54 is provided with two forwardly projecting portions 84 and 86. These are spaced to correspond with portions of the grid 10. These portions may therefore be brought into alignment with out bridging portions 18 remaining with the grid 10 and being spaced apart by substantially three times the diameter of each hole 14, such as those portions labelled 88 in Figure 1.

[0045] When in use, the die and punch cutter 32 is brought into position adjacent to a cut edge of the grid 10, and for example to out away the hub portion labelled in Figure 1 and in Figure 2. Away from which hub portion 90 extends a bridging portion 18 between the upper ends of two stainless steel circularly cross- -10 -sectioned rods 92 and 94 as shown in Figure 1. As the cutter 32 approaches this position, the projecting portions 84 and 86 of the guide 54 locate against the remainder of bridging portions 96 and 98 shown in Figure 1. This brings the punch 42 into alignment with the hub portion 90 of the grid 10. Further forward movement into the grid 10 brings the first part 64 of the punch 42 and the cylindrical portion 62 of the die 40 into alignment with what would have been the hole immediately adjacent to the hub 90 and the upper ends of the rods 92 and 94, but which is now only a half hole 100 in view of earlier cutting of the grid 10. The cther two hollow cylindrical portions 58 and 60 of the die 40 and are now located immediately above the upper ends of the rods 92 and 94.

Also, the cutting edges 68, 70 and 72 of the punch 42, and the shearing edges 78, 80, and 82 of the die 40, are In registration with the centres of the three bridging portions 18 which are mutually adjacent to one another and which extend away from the hub portion 90 of the grid 10.

[0046] With the cutter 32 so positioned, a cutting operation is now effected by the hydraulic drive 44 urging the die 40 downwardly towards the grid 10 guided by the pillars 48. The upper ends of the rods 92 and 94 are thereby received In the hollows of the cylindrical portions 58 and 60 of the die 40, and this further ensures correct alignment of the cutter 32. Continued operation of the drive 44 pushes the punch 42 upwardly towards the die 40 guided by the pillars 48. As a result, the cutting edges 68, 70 and 72 acting as a male cutting edges and the cutting edges 78, 80, 82 acting as a female cutting edges operate to cut away the hub portion 90 in the form of a tn-point junction. This Is received wIthin -11 -the die 40 and may be transferred thereby subsequently to a desired location, or simply allowed to fall away.

[0047] The punch 42 may now be lowered, and the die 40 retraoted upwardly, to drive the punch and the die away from one another ready for the next cutting operation.

[0048] A further cutting or shearing of the next such hub portion of the grid 10 in a given direction will enable one or other of the rods 92 and 94 to be released from the grid 10 whereafter the next suoh hub portion of the grid 10 in the opposite direction may be cut away to release the other of the rods 92 and 94.

[0049] It will be appreoiated that because of the shape of the part 66 of the punch 42, it is able to operate notwithstanding the presence of the rods 92 and 94. Likewise the die 40 is able to be brought down all the way to the upper surface of the plate 12 notwithstanding the upper ends of the rods 92 and 94, because these upper ends are received comfortably in the hollows of the cylindrical portions 58 and 60 of the die 40.

[0050] Numerous variations and modifications to the illustrated die and punch cutter 32 may occur to the reader without taking the resulting construction outside the scope of the present invention. To give one example only, the part 64 of the punch 42 may be shaped differently, for example its cross-section might have the rear part of the circle cut away, so that the punch 42 has a flat on its rear side.

[0051] The rods 92 and 94 may have a cross-sectional diameter of substantially 35mm, and the holes 14 in the grid 10 may have a cross-sectional diameter of substantially 37mm.

[0052] withdrawal of the punch 42 from the die 40 may be assisted by a sprung bolster plate (not shown) . Such a -12 -bolster plate also improves the ability of the cutter 32 to be moved into position with the grid plate 10 located between the guide 54 and the bolster plate without damaging the punch 42. To this end, such a bolster plate would be seated on springs extending upwardly from the punch support block 56, the upper surface of the bolster plate being level with the top of the punch 42.

[0053] The force applied by the drive 44 to the die 40 and the punch 42 may be about 20 tons with a hydraulic pressure of 700 bar.

[0054] The cross-sectional diameter of the cutter 32 may be substantially 170 mm to enable it to pass through a restricted access space of 9 inches in diameter and manipulated relative to the grid plate 10 about Sm below the access. Cameras and/or proximity sensors may be positioned to assist alignment.

[0055] In the absence of rods to assist in alignment of the cutter 32, such alignment may instead be assisted by dummy rods inserted into the hollows of the cylindrical portions 58 and 60.

[0056] The cutter 32 avoids a rough edge or burrs being formed at the cut that would cause an obstruction for a subsequent cutting operation.

[0057] The die 40 and the punch 42 have flat opposing surfaces to allow re-grinding for sharpening.

[0058] The cylinder support block 52, the pillars 48 and the punch support block 56 constitute a C-frame which rigidly supports and aligns the main hydraulic cylinder 46, the mounting block 50, the die 40 and the punch 42.

[0059] The die 40 may be provided with a bore (not shown) to receive a guide pin (not shown) extending upwardly from the punch 42 to ensure continual alignment of the cutting edges of the punch 42 with those of the die 40 during a cutting operation.

-13 - [0060] The punch 42 may have flats on its sides to avoid burrs from previous out portions.

Claims

-14 -Claims: 1. A die and punch cutter for releasing rods or elongate elements, respective ends of which extend through respective holes in a grid, which holes are arranged in a honeycomb pattern, the cutter comprising a die, a punch, and a drive coupled to the die and the punch to drive them towards one another for cutting portions of such a grid, and away from one another to ready them for the next cutting operation, in which the punch is provided with three cutting edges corresponding in their relative positioning to three mutually adjacent bridging portions of such a grid.
2. A die and punch cutter according to claim 1, in which the die is provided with three cutting edges corresponding in position to those of the punch.
3. A die and punch cutter according to claim 2, in *0* which the die is so dimensioned that the three cutting edges when in use can be located at positions corresponding to positions on the grid at which the bridging portions are narrowest.
4. A die and punch cutter according to any preceding claim, in which the punch is formed with two concave surfaces which lead away from one of the cutting edges and extend respectively to the other two cutting edges, the radius of curvature of the two concave surfaces being the same as or substantially the same as that of the -15 -holes in the grid which is intended to be cut by the cutter.
5. A die and punch cutter according to any preceding claim, in which the die is formed with two hollows capable of receiving respective ends of two adjacent such elements when the cutter is in use.
6. A die and punch cutter according to any preceding claim, in which the punch is provided with a portion having a uniform cross-section at least a part of which is substantially semicircular, from the middle of the periphery of which extends a portion of the punch which provides the three cutting edges, the radius of curvature of the semicircular part of the cross-section being the same or substantially the same as that of each hole of the grid.
7. A die and punch cutter according to claim 6, in which the die is provided with a hollow, or a third hollow, to receive that portion of the punch which has a * * uniform cross-section at least a part of which is *0.semicircular. *

*
8. A die and punch cutter according to claim 6 or claim 7, in which the uniform cross-section is substantially circular.
9. A die and punch cutter according to any preceding claim, in which the die is above the punch when the cutter is in use.

-16 -
10. A die and punch cutter for use in cutting a grid in which holes are formed and through which holes the upper ends of rods or elongate elements extend, the cutter comprising a die and a punch, in which the die is provided with hollows or recesses to accommodate at least one of those upper ends, and the punch is located below the die when the cutter is in use.
11. A die and punch cutter according to claim 10, and also in accordance with any one of claims 1 to 9.
12. A die and punch cutter substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
13. A method of cutting a grid to release elongate elements therefrom, respective ends of which extend through respective holes in the grid, using a die and punch cutter according to any one of claims 1 to 12. U..*4**** * . * * *0* *0** * * * * **.**.