1. A downhole debris recovery tool comprising:
an elongate body having an axial throughbore and pin and box end configurations for assembly of the tool into a workstring, the elongate body further having a recessed surface for receipt of magnetic elements, and
a pair of semi-cylindrical parts each having an array of uniformly sized magnetic elements configured to form an Halbach array when the semi cylindrical parts are formed together into a cylinder, wherein the semi-cylindrical parts are arranged in the recessed surface of the elongate body to form the Halbach array of cylindrical form, and
a close-fitting cylindrical sleeve slidable over the cylinder having the Halbach array, the close-fitting cylindrical sleeve secured to the elongate body by provision of stabilizers which overlay respective ends of the sleeve with sufficient clearance in respective recesses so that the sleeve is restrained with respect to axial displacement between the stabilizers and freely rotatable with respect to the stabilizers.
2. The downhole debris recovery tool of claim 1, wherein the tool comprises a cylindrical body and the magnets are arranged in an Halbach cylinder configuration around the body, wherein the component magnets are arranged such that the effective magnetic field is entirely outside the cylinder, with substantially zero field inside.
3. The downhole debris recovery tool of claim 1, wherein the magnets are encased within stainless steel and sealed in the tool.
4. The downhole debris recovery tool of claim 1, wherein the magnets are made of rare earth magnetic materials, optionally associated with flux carrying materials.
5. The downhole debris recovery tool of claim 1, wherein the magnets comprise at least one of the group consisting of neodymium iron boron, ceramic ferrite, samarium cobalt, and aluminium nickel cobalt.
6. The downhole debris recovery tool claimed in claim 1, wherein the semi-cylindrical parts each contain an even number of magnetic elements covering 180 degrees.
7. The downhole debris recovery tool of claim 6, wherein the semi-cylindrical parts each comprise a plurality of void spaces around the magnets, wherein the void spaces are filled to inhibit corrosion.
8. The downhole debris recovery of claim 1, wherein the semi cylindrical parts are individually sealed for protection of the magnets.
9. The downhole debris recovery tool of claim 6, wherein there are 8 magnetic elements.
10. The downhole debris recovery tool of claim 6, wherein there are 10 magnetic elements.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A cabinet anti-tilt safety apparatus comprising:
a cabinet body which is a rectangular body composed of five rectangular panels which define an internal space and a vertical open face, at least two drawers being back and forth slidably arranged in the open face;
an activation section which is a rod body leftward and rightward extending by a certain length, the activation section being disposed on a predetermined section of rear side of each drawer;
a base seat fixed on inner face of a panel of the cabinet body corresponding to the rear side of each drawer;
a slide seat slidably fitted with the base seat, the slide seat being up and down reciprocally movable between a first position and a second position, a block body being disposed on the slide seat corresponding to the activation section, the block body having an inner slide way and a middle slide way, the inner slide way being an elongated slot vertically extending by a predetermined length, the middle slide way being an elongated slot obliquely downward extending from upper end of the inner slide way toward the activation section by a predetermined length, the activation section being reciprocally movable to get into or out of the corresponding block body so as to push inner edge of the middle slide way, whereby the slide seat can be reciprocally moved between the first and second positions;
a first connecting section disposed at one end of the base seat;
a second connecting section disposed at one end of the slide seat corresponding to the first connecting section, after one drawer is drawn out, the activation section of the drawn out drawer driving the slide seat and then the first connecting section being engaged with the second connecting section, whereby the slide seat is positioned in the first position and the activation sections of the remaining drawers are engaged with lower ends of the corresponding inner slide ways, after the drawn out drawer is pushed back into the cabinet body, the activation section of the pushed back drawer driving the slide seat and then the first connecting section being disengaged from the second connecting section, whereby the slide seat is positioned in the second position and the activation sections of all the drawers are disengage from the corresponding inner slide ways.
2. The cabinet anti-tilt safety apparatus as claimed in claim 1, wherein the block body further includes an outer slide way, a lower edge of the outer slide way further extending from lower edge of the middle slide way, an upper edge of the outer slide way further obliquely upward extending from upper edge of the middle slide way to form a restoring slope, in the case that after one drawer is drawn out, an unexpected external force is applied to the cabinet body to make the slide seat move to the second position, when the drawn out drawer is again pushed in, the activation section of the drawn out drawer will push the corresponding restoring slope to move the slide seat, whereby the first and second connecting sections are engaged with each other and the slide seat is positioned in the first position.
3. The cabinet anti-tilt safety apparatus as claimed in claim 1, wherein the first connecting section is a resilient clip body having an internal cavity and an opening and the second connecting section is a rod body.
4. The cabinet anti-tilt safety apparatus as claimed in claim 2, wherein the first connecting section is a resilient clip body having an internal cavity and an opening and the second connecting section is a projecting body.
5. The cabinet anti-tilt safety apparatus as claimed in claim 3, wherein the rod body has an elliptic cross-section and the internal cavity of the clip body has a shape corresponding to the profile of the rod body.
6. The cabinet anti-tilt safety apparatus as claimed in claim 4, wherein the projecting body has an elliptic cross-section and the internal cavity of the clip body has a shape corresponding to the profile of the projecting body.