Abstract: An abrasive grinding wheel having an inclined edge is obtained by subjecting an abrasive disc composed of spring steel sheet, preferably after flat grinding of the abrasive face, to stamping or turning followed by flat grinding. A grinding wheel of this type allows the capacity of a cutting off, smoothing, edge planing and polishing machine with automatic charging to be increased considerably.

Abstract: The invention relates to a process for manufacturing an inner tube element made of synthetic resin for a double tube coring apparatus provided for deep boring. The tube element is provided with coupling nipples for connecting it to other inner tube elements. Fibers coated with synthetic resin are wound helically onto a cylindrical mandrel so as to overlap each nipple. This process gives the tube element a higher strength than that of glued nipples.

Abstract: An inner tube element for a coring apparatus comprising a double tube, made of synthetic resin reinforced with fibers and provided at its ends with connecting nipples, is entirely made of synthetic resin and overlaps, at each of its ends, a part of the nipples having a rough surface gripped by said fibers, preferably in the form of webs of glass fibers.The inner tube element is manufactured by a process in which two nipples or couplings are placed onto a cylindrical mandrel having a constant section and rotating about its longitudinal axis, at a predetermined distance corresponding to the tube element to be manufactured, a part of said nipples having an inner diameter substantially identical to the diameter of the mandrel and having a rough surface, and fibers coated with a synthetic resin are wound helically onto said cylindrical mandrel, so as to overlap the rough part of said nipples.

Abstract: An inner tube 2 of a core barrel is releasably locked within an outer tube 1 by pivotable latch feet 32 engaging an annular recess 31 in the outer tube. A retrieving head 3 is slidably coupled via a pin 40 and slot 41 to the inner tube, and carries sealing rings 6 disposed, during coring, within a recess 5 in the outer tube to permit fluid passage. To retrieve a core sample in an ascending boring the pressure in the lower part of the column is reduced, whereupon the retrieving head drops by gravity to seal off the outer tube. A pin 37 on the inner tube then drops to cam release the latch feet and unlock the inner tube from the outer tube. Thereafter, as the lower column is drained, the inner tube and retained core sample descend by gravity down through the outer tube to a retrieval site.

Abstract: A double core barrel for carrying out boring and arc drilling in oilfields comprises a rotary outer tube 1 with a boring bit 3 and a non-rotary inner tube 2, with an extractor cone 9, screwed onto the lower non-rotary portion of a pivoting means 11 whose upper rotary position 12 is screwed into a tapped body 4 of the outer tube 1. The upper end 15 of the portion 12 cooperates with an adjustment spanner 16 which transmits a rotation couple to the upper end, to allow adjustment of the spacing for the passage of water between the bit 3 and the cone 9. The upper end 15 has an external longitudinal groove, while the tapped body has a slot 8 at the base of a smooth cylindrical bore 6 and at the level of the longitudinal groove 17.

Abstract: A cable-type core barrel comprising, within a set of outer tubes provided lowerly with a drill bit, an inner tube provided at its bottom with an extractor cone and at its top with a hooking head provided with an upper cone frustum hook and a release cone, the inner tube being lockable in the core boring position by a tongue latch supported by a tubular latch support which is rigid with the inner tube and does not affect the release of this latter. The core barrel is fitted with an inshot comprising a lower longitudinally slotted bell member connected to a rod extending upwards, an upper hooking head comprising an upper cone frustum hook and rigid with an intermediate tube extending downwards, a helical spring housed between the intermediate tube and the rod, and resting on supports on said intermediate tube and said rod, and a threaded ring which is screwed on to the intermediate tube and when in its lower position surrounds the bell member.