CUTTING INSERT AND MILLING TOOL FOR USE IN A WELLBORE

This invention relates to a cutting insert for a tool for wellbore milling operations. Cutting inserts are already known from US-A-5 626 189.

Milling tools are used to cut out window or pockets from a tubular, e.g. for directional drilling and sidetracking; and to mill out for removal materials downhole in a wellbore, such as pipe, casing, casing liners, tubing, or jammed tools (a "fish").

Typically, the milling tool comprises a body on which are mounted a multiplicity of cutting inserts which cut away the unwanted material whilst being eroded themselves.

Because of the very high costs associated with running a drilling rig enormous effort is expended on improving cutting inserts either to increase longevity or to increase cutting rate or both.

The present invention addresses these problems.

According to the present invention there is provided a cutting insert for a tool for wellbore milling operations, the cutting insert comprising:

• a body having a top;
• a plurality of spaced-apart chipbreaking indentations in the top of the body; and
• a strengthening ridge projecting from the top of the body between adjacent chipbreaking indentations of the plurality of spaced-apart chipbreaking indentations

The strengthening ridge helps to reduce or eliminate the propagation of cracks between adjacent chipbreaking indentations.

Preferably, said cutting insert further comprises a peripheral strengthening ridge around an outer edge of the top of the body surrounding the plurality of spaced-apart chipbreaking indentations. These ridges may be, in cross-section, for example square, rounded, semi-circular, trapezoidal with a lower base longer than an upper base, or rectangular.

Advantageously, said spaced-apart chipbreaking indentations extend substantially across the entire top of the body.

Preferably, each of the plurality of spaced-apart chipbreaking indentations is of substantially-circular outline with a similar diameter and is spaced-apart from at least one other of the plurality of spaced-apart chip breaking indentations by a distance at least equal to the diameter of the chipbreaking indentations.

Advantageously, said cutting inserts further comprises a central indentation surrounded by the plurality of spaced-apart chipbreaking indentations.

Conveniently, the central indentation may be circular, square, rectangular or regularly polygonal as viewed from above.

The chipbreaking indentations may be any suitable shape, as viewed from above, including but not limited to circular, oval, elliptical, square; rectangular, or regular polygonal.

The chipbreaking indentations may be arranged side by side in rows and columns, or offset with respect to each other. In cutting inserts with a central indentation, one, two, three or more lines or chipbreaking indentations may surround the central indentation. Preferably a strengthening raised portion is positioned between the central indentation and adjacent dimples.

By using a regularly symmetrically shaped insert body and a patter or chipbreaking indentations there across, a cutting insert is provided which has noncontinuous separate and distinct chipbreaker indentations which can be applied to a mill or blade in a correct orientation in a fool-proof manner.

Preferably, said body has a lower curved edge and two upper curved edges, each of the upper curved edges corresponding substantially complimentary in shape to a portion of the lower curved edge.

The present invention also provides a cutting insert for a tool for wellbore milling operations, the cutting insert having a body having a top, at least one chipbreaking indentation in the top of the body, and the at least one chipbreaking indentation having a substantially semi-circular shape.

Preferably, the at least one chipbreaking indentation is at least two spaced-apart semi-circular chipbreaking indentations.

The body has

The present invention also provides a cutting insert for a tool for wellbore milling operation, the cutting insert comprising a body having a lower curved edge and two upper curved edges, each of the upper curved edges corresponding substantially complimentarily in shape to a portion of the lower curved edge.

There is also provided an array of cutting inserts in accordance with the present invention and a tool for wellbore milling operations, the tool comprising a mill body, at least one milling surface on the mill body, and an array of cutting inserts in accordance with the present invention secured to the at least one cutting surface of the mill body.

For a better understanding of the present invention reference will now be made, by way of example, to the accompanying drawings, in which:-

• Fig. 1 is a plan view of a first cutting insert;
• Fig. 2 is a section on line II-II of Fig. 1;
• Fig. 3 is a plan view of a second cutting insert;
• Fig. 4 is a section on line IV-IV of Fig. 3;
• Fig. 5 is a plan view of a cutting insert;
• Fig. 6 is a plan view of a fourth cutting insert;
• Fig. 7 is a plan view of a fifth cutting insert according to the present invention;
• Fig. 8 is a plan view of an array of cutting inserts as shown in Fig. 7;
• Fig. 9 is a plan view of an array of cutting inserts as shown in Fig. 5;
• Fig. 10 is a plan view of a sixth cutting insert;
• Fig. 11 is a plan view of a seventh cutting insert;
• Fig. 12 is a plan view of an embodiment of a cutting insert according to the present invention;
• Fig. 13 is a plan view of a further embodiment of a cutting insert according to the present invention;
• Fig. 14 is a plan view of an other embodiment of a cutting insert;
• Fig. 15 is a section on line XV-XV of Fig. 14;
• Fig. 16 is a plan view of a further embodiment of a cutting insert according to the present invention;
• Fig. 17 is a section on line XVII-XVII of Fig. 16;
• Fig. 18 is a plan view of a further embodiment of a cutting insert according to the present invention;
• Fig. 19 is a plan view of a scallop array of cutting inserts as shown in Fig. 16;
• Fig. 20 is a schematic side view of a scallop array (similar to that of Fig. 19) of cutting inserts according to the present invention;
• Fig. 21 is a schematic side view of a scallop array (similar to that of Fig. 19) of cutting inserts according to the present invention; and
• Fig. 22 is a plan view of a further embodiment of a cutting insert according to the present invention.

Figs. 1-11, 14 are described for a better understanding of the invention only and are not part of the invention.

Referring to the drawings, Figs. 1 and 2 show a cutting insert which is generally identified by reference numerals 610. The cutting insert 610 has a square body 612 having a plurality of chipbreaking indentations 614, which are arranged in a pattern across the top surface 616 of the body 612. Strengthening ridges 618 extend between chipbreaking indentations 614 and a strengthening ridge 620 extends around the outer periphery of the body 612.

Preferably, the strengthening ridges 618 and 620 are of sufficient size and strength to inhibit or prevent propagation of cracks from one chipbreaking indentation 614 to an adjacent chipbreaking indentation 614.

In one particular embodiment a chipbreaking indentation 610 is ahout 6.4mm (¼ inch) in height with a side length of _ inch and strengthening ridges 618 with a trapezoidal cross-sectional shape (see Fig. 2) with a top width of about 2.2mm (0.085 inches) and a bottom width of about 1.44mm (0.055 inches). The strengthening ridge 620 for this particular insert has a top width of about 0.8mm (0.030 inches) and a bottom width of about 1.1mm (0.045 inches). Each chipbreaking indentation is substantially circular and has a diameter at the surface of about 2.2mm (0.085 inches).

Figs. 3 and 4 show a cutting insert 630 with a square body 632 having a plurality of chipbreaking indentations 634 in a pattern around the periphery of the top surface 636 of the body 632. Strengthening ridges 638 extend between the chipbreaking indentations 634 and a strengthening ridge 640 extends around the outer periphery of the body 632.

Preferably, the strengthening ridges 638 and 640 are of sufficient size and strength to inhibit or prevent propagation of cracks from one chipbreaking indentation 634 to an adjacent chipbreaking indentation 634. The strengthening ridges may be trapezoidal, square, rounded, or semi-circular (as viewed in cross-section in Figs. 2 and 4). A central square chipbreaking indentation 639 is surrounded by the chipbreaking indentation 634. The central square chipbreaking indentation 639 may be any desired suitable size and/or shape ( e.g. but not limited to square or circular, as may be the peripheral chipbreaking indentations).

Fig. 5 is a top view of a cutting insert 650 with a circular body 652 having a plurality of chipbreaking indentations 654 in a pattern across the top surface 656 of the body 652. Strengthening ridges 658 extend between chipbreaking indentations 654 and a strengthening ridge 660 extends around the outer periphery of the body 652. The cutting insert 650 and any insert herein, including but not limited to those shown only in top view, may be of any suitable thickness and may have a top surface parallel to a bottom surface (e.g. as the cutting inserts 770, below) or may have a top surface not parallel to the bottom surface (e.g. as in the cutting insert 770a, Fig. 21).

Fig. 9 shows an array of cutting inserts 650. Such an array may be used on a milling blade (substantially all of its surface or part thereof) or milling surface of a milling tool. Although the array shown has twenty-one cutting inserts, it is within the scope of this invention to use any desire number of the cutting inserts 650, any cutting insert disclosed herein, or any combination thereof and cutting inserts of any desire dimensions may be used. The cutting inserts may be offset as shown in Fig. 9 or may be lined up. Halves of cutting inserts may be used: within a row of cutting inserts; anywhere in an array of cutting inserts; and/or at the ends of rows of offset cutting inserts. Alternatively an array may be composed entirely of half inserts. As shown in Fig. 9, "dimples" or chipbreaking indentations in one cutting insert in one row are offset from those of a cutting insert in a row above or below.

Fig. 6 shows a cutting insert 670 with a triangular body 672 having a plurality of chipbreaking indentations 674 arranged in a pattern across the top surface 676 of the body 672. Strengthening ridges 678 extend between the chipbreaking indentations 674 and a strengthening ridge 679 extends around the outer periphery of the body 672.

Fig. 7 shows a cutting insert 680 with a square body 682 having a plurality of chipbreaking indentations 684 and 687 in a pattern on the top surface 686 of the body 682. Strengthening ridges 688 extend between the chipbreaking indentations 684 and a strengthening ridge 689 extends around the outer periphery of the body 682. Fig. 8 shows an array of the cutting inserts 680 (or halves thereof) on part of a milling blade 685.

Fig. 10 shows a cutting insert 700 with a square body 712 having a plurality of chipbreaking indentations 714 in a pattern across a top surface 716 of the body 712. Strengthening ridges 718 extend between the chipbreaking indentations 714 and a strengthening ridge 719 extends around the outer periphery of the body 712.

Fig. 11 shows a cutting insert 720 with a circular body 722 having a plurality of circular chipbreaking indentations 724 in a pattern across the top surface 726 of the body 722. Strengthening ridges 728 extend between the chipbreaking indentations 724 and a strengthening ridge 729 extends around the outer periphery of the body 722. A central circular chipbreaking indentation 725 is surrounded by the chipbreaking indentations 624. Any cutting insert disclosed herein may be made of material of a suitable hardness for wellbore milling operations including but not limited to hard steels, carbides, tungsten carbide, composites, and diamond or diamond impregnated material.

Fig. 12 shows a cutting insert 750 with a plurality of spaced-apart chipbreaking indentations 752. A side view (not shown) of the insert 750 is generlally similar to that of the cutting insert shown in Fig. 17; but may be like that of the cutting inserts shown in Fig. 21. The cutting insert 750 has a curved upwardly (as viewed in Fig. 12) extending tang or tongue 751 and, in one aspect, curved sides 753 corresponding complimentarily to the curve of the lower edge (as viewed in Fig. 12) of the cutting insert to facilitate side-by-side placement and correct placement of the cutting inserts. Such a shape as viewed from above as in Figs. 12, 13, 16, 18 and 22 is referred to as "chevron" shape.

Fig. 13 shows a cutting insert 754 with a plurality of spaced-apart chipbreaking indentations 756. A side view (not shown) of the cutting insert 754 is generally like that of the cutting insert shown in Fig. 17; but may be like that of the cutting inserts shown in Fig. 21. The cutting insert 754 has a curved, upwardly (as viewed in Fig. 13) extending tang or tongue 758 and, in one aspect, curved sides 757 corresponding complimentarily to the curve of a lower edge 759 (as viewed in Fig. 13) of the cutting insert to facilitate side-by-side placement and correct placement of the cutting inserts.

Fig. 14 shows a cutting insert 760 with a body 761 and an array or pattern of chipbreaking indentations 762 spaced apart by ridges, masses or amounts 763 of the body 761. Preferably, no chipbreaking indentation is completely surrounded by other indentations closely adjacent thereto; i.e., each indentation is either located adjacent an edge of the cutting insert and/or has a space between it and at least one other chipbreaking indentation that approximates or exceeds the width (diameter as viewed from above, e.g. as in Fig. 14) of one of the chipbreaking indentations. In one particular embodiment the cutting insert 760 has a diameter d of about 9.5mm (0.375 inches); a height c of about 5.1mm (0.2 inches); and twenty-nine chipbreaking indentations each with a diameter of about 1.2mm (0.047 inches) and about 0.2mm (0.01 inches) deep with those along the outer edge spaced about 0.3mm (0.01 inches) inwardly of the edge.

Figs 16 and 17 show a cutting insert 770 with a body 771 whose lower portion is generally semi-circular and which has a correspondingly-shaped chipbreaking indentation 772 spaced inwardly from a lower curved edge' 775 by an amount 776 of the body 771. An upper tang or tongue 773 is defined by curved sides 774 whose curved shape corresponds to the curved shape of the lower edge 775 to facilitate correct and side-by-side emplacement of a plurality of the cutting inserts 770 in a "scal-loped" array like the array 777, Fig. 19.

Fig. 18 shows a cutting insert 780 with a body 781 whose lower portion is generally semi-circular and which has a correspondingly-shaped chipbreaking indentation 782 spaced inwardly from a lower curved edge 785 by an amount 786 of the body 781. Another chipbreaking indentation 787 is shaped like the indentation 782 and is spaced-apart therefrom by an amount 788 of the body 781. An upper tang or tongue 783 is defined by curved sides 784 whose curved shape corresponds to the curved shape of the lower edge 785 to facilitate correct and side-by-side emplacement of a plurality of the inserts 780 in a "scalloped" array like the array 777, Fig. 19. As previously stated, any of the inserts in Figs. 12-22 may have either a locating tab, a tab receiving recess, or both as described above.

Fig. 20 shows schematically part of any array of cutting inserts 770 and 780 which is like the array 777. Fig. 21 shows an array of cutting inserts 770a (like the cutting inserts 770, but with a bottom that is not parallel to the top) and cutting insert 780a (like the cutting inserts 780, but with a bottom that is not parallel to the top).

Fig. 19 shows an array 777 of cutting inserts 770 placed in abutting side-by-side and top-to-bottom relationship. Alternatively, the cutting inserts may be placed in a similar pattern, but with an amount of matrix milling material between cutting inserts.

Fig. 22 shows a cutting insert 790 with a body 791 whose lower portion is generally semi-circular and-which has a correspondingly-shaped chipbreaking indentation 792 spaced inwardly from a lower curved edge 795 by an amount 796 of the body 791. Another chipbreaking indentation 797 not shaped like the chipbreaking indentation 792 is spaced apart from the chipbreaking indentation 792 by an amount 798 of the body 791. An upper tang or tongue 793 is defined by curved sides 794 whose curved shape corresponds to the curved shape of the lower edge 795 to facilitate correct and side-by-side emplacement of a plurality of the cutting inserts 790 in a "scal-loped" array like the array 777, Fig. 19. The tang or tongue 793 is only as thick as the body 791 is at the location of the indentation 797 (e.g. with cutting inserts 770 and 790 comparable in size, the tongue 793 would not be as thick as the tongue 773 as shown in Fig. 17).