RU2553108C1 - Cutter for rotary drilling - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: cutter comprises a body with a shank and feathers reinforced with carbide blades, the cutting edges of which are arranged symmetrically relative to the longitudinal axis of the housing. The front face of the carbide blades is made convex-shaped in the form of a cylindrical surface, the generant of which is parallel to the axis of the feather. The height of the convex decreases from the inner part of the feather to its outer part and constitutes 0.5 … 2 mm.

EFFECT: increase in cutting tool life, reduction of specific energy consumption of destruction through the contact stress redistribution on the front face of the cutter.

2 dwg

Description

The invention relates to cutters for rotary drilling, specifically for feather crowns, and may find application in drilling coals and rocks of high strength.

Known cutting tools for drilling, consisting of a body with a shank and a cutting part of 2 or 3 feathers, reinforced with carbide plates. Hard alloy plates have a flat front face and are fixed on the feathers of the cutter by soldering symmetrically with respect to the axis of rotation of the rod [1]. Also known is a cutter for rotary drilling, in which the cutting edge of the carbide plate of one of the feathers is rotated towards the longitudinal axis of the housing at an angle of 4-8 ° [2].

Most rotary drilling cutters are reinforced with carbide inserts having a flat front surface.

A feature of rotary drilling cutters is that the peripheral sections of the hard alloy plates farther from the axis of rotation have a larger radius of rotation than the sections close to the axis of rotation.

This determines the picture of compression stresses along the front face of each feather in the process of fracture and features of the process of chips of the destroyed volume. Studies [3] showed that the order of chips in front of the front face of each feather is due to the distribution of compression stress in front of the front face of the cutter and occurs sequentially from the peripheral part of the carbide plate to the axis of rotation.

At the same time, the chips in the peripheral areas are in a more blocked state than subsequent chips following them closer to the axis of rotation. A rock cleavage at the periphery of the hard alloy plate provides surface exposure for the next cleavage, which occurs closer to the axis of rotation, which occurs at a lower contact stress. In this case, the most unfavorable cleaving conditions are formed precisely on the peripheral sections of carbide plates. As you know, the specific energy consumption of the destruction of the cutting process depends on the degree of blocking of the cutter, determined by the cutting scheme. The sequence of chips from the periphery to the axis of rotation determines the specific energy consumption of the process of destruction of the pre-cutter zone of the rock being destroyed, which is overestimated for rotary drilling cutters with a flat front face.

The distribution of contact stresses along the front face, the sequence and conditions of chips in front of the front face cause more intense wear on the peripheral part of the hard alloy plates and explains the more frequent breakdowns (during overloads) of the hard alloy plates on the peripheral areas. This leads to an increased failure of the incisors from breakdowns, an increase in downtime for replacing the incisors, a decrease in productivity, which is a drawback of analogues and the incisor selected as a prototype.

The objective of the invention is to remedy these disadvantages, namely reducing the energy intensity of the drilling process, increasing the resistance of the cutters, mainly when drilling hard rocks.

The problem is solved in that the front face of the carbide inserts is made convex in the form of a cylindrical surface, the generatrix of which is parallel to the axis of the pen, so that the height of the bulge decreases from the inside of the pen to its outer part, and the height of the bulge is Δh = 0.5 ... 2 mm .

The invention is illustrated by drawings, where figure 1 shows a General view of the feather cutter and cross-section of feathers, figure 2 shows two schemes for the formation of chips.

The cutter consists of a housing 1 with a shank 2 and feathers 3, on which the plates of hard alloy 4 are fixed. The shape of the plates is illustrated by sections A-A and B-B. The front face of each plate is made convex in the form of a cylindrical surface, the generatrix of which is parallel to the axis of the pen, so that from the inside of the pen to its outer part, the height of the bulge decreases. The height of the bulge is Δh = 0.5 ... 2 mm The convexity of the hard alloy plate can be ensured by thinning its peripheral part to provide sufficient strength or by tilting the plane of the carbide plates so that the part of the plate close to the axis of rotation of the cutter outstrips the peripheral part of the plate in contact with the walls (borehole) of the borehole. This can be achieved by a relatively simple change in the shape of the grooves on the shanks under the typical hard alloy plates. It is also possible to manufacture plates of a hard alloy with a cylindrical convexity along the axis of symmetry, so that the convexity of the plate is maximum on the part of the front face, which will be closer to the axis of rotation when soldering. The magnitude of the bulge is determined taking into account studies of the process of indentation of a flat slit stamp into the rock [4]. The same tests revealed patterns of stress formation under the plane of the stamp. For hard rocks, the convex height is sufficient Δh = 0.5 ... 1.0 mm, for soft rocks the convex height can be increased to Δh = 2.0 mm.

The process of formation of chips of figure 2 in the claimed technical solution differs from the typical. In the direction of rotation, in the circumferential space, compression stresses are successively formed. First, in the leading edge part ahead of the cutting direction (in the area of maximum convexity of the hard alloy plates), and then in the peripheral, lagging part of the hard alloy plates. In the inventive cutter, the portion of maximum convexity of the hard alloy plates is made close to the axis of rotation, and the peripheral portion of the front face lags in the direction of rotation of the cutter.

Figure 2 shows comparative diagrams of the formation of chips for a typical cutter with a flat face and the inventive cutter with a bulge on the front face. For a typical design of a cutting tool (FIG. 2, C), primary chips primarily occur in front of the peripheral sections (darkened areas) of the hard alloy plates, and for the inventive cutter (FIG. 2, D), chips primarily occur in middle, in width, part of the carbide plate or simultaneously with chips in front of the peripheral part of the carbide plates. In the latter case, the stress fields formed by the convexity and the peripheral part of the plates are added together, this ensures a reduction in the specific energy consumption of the destruction of rock particles in front of the front face of the cutter. The described features of the fracture process are manifested in a random unpredictable sequence and are a probabilistic picture of chip formation. Changing the pattern of formation of destructive stresses in the pre-cutter zone provides a decrease in the load on the peripheral sections of carbide plates, thereby increasing the resistance of reinforcement and reducing the wear rate of these sections, and also reduces the specific energy consumption of fracture.

Literature

1. Krapivin M.G., Rakov I.Ya., Sysoev N.I. Mountain Tools, / 3rd ed. reslave. and add. M .: Nedra, 1990.256 s.

2. Cutter for rotary drilling. E.I. Suslov, G.V. Lindo, N.S. Kamysheva et al. RF Patent No. 1305296, E21B 10/42 of 11/27/85.

3. Sysoev N.I., Mirny S.G. Fundamentals of the theory of the functioning of rotary drilling machines. Uch. allowance, SRSTU (NPI). Novocherkassk: SRSTU. 2006. S. 6-17.

4. Karabanov M.G., Lemeshko M.A., Samohodkin I.N. The mechanics of the interaction of the cutting tool with destructible material // Technology and technique of plow excavation of anthracite: Sat. labor. Issue 16. / Mine Research Institute: Mines, 1975. S. 34-41.

Claims (1)

Cutter for rotary drilling, including a housing with a shank and feathers reinforced with carbide inserts, the cutting edges of which are located symmetrically relative to the longitudinal axis of the housing, characterized in that the front face of the carbide inserts is convex in the form of a cylindrical surface, the formation of which is parallel to the axis of the pen, so that the height of the bulge decreases from the inner part of the pen to its outer part, and the height of the bulge is 0.5 ... 2 mm

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