RU2135768C1 - Cutting tool for mining machines (versions) - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: cutting tool for mining machines has at least one plate from hard alloy brazed to holder fitted with tail part and cutting edge. Plate has thickness h_pl meeting following relation

, where k is coefficient equal to 0.25-5.6; E_pl is modulus of elasticity of material of plate, kg/sq.mm; E_hold is modulus of elasticity of material of holder, kg/sq.mm; σ_pl is temporary resistance to bending of material of plate, kg/sq.mm; σ_hold is temporary resistance to bending of material of holder, kg/sq.mm and length L_pl meeting following relation L_pl= k₁•h $\genfrac{}{}{0ex}{}{\text{0,3}}{\text{pl}}$ , where k₁ is coefficient equal to 15.0-25.0. In this case holder has thickness h_hold equal to h_hold=(L_pl/2)•tgα in section corresponding to half-length of plate. Another version of cutting tool includes plate having variable thickness. EFFECT: decreased energy consumption for rock breaking and enhanced productivity of mining machine. 6 cl, 6 dwg

Description

 The present invention relates to the mining industry, namely to cutting tools of the executive bodies of mining machines, used mainly for the development of salt and coal deposits without strong inclusions.

 When developing a cutting tool for the destruction of weak media - salts and coals without strong inclusions - the main task is to provide the largest possible resource for the cutter while at the same time the lowest energy consumption of the medium destruction.

Known cutter for mining machines (AS USSR N 605956), including the holder - an axisymmetric body with a shank and a head formed by a truncated cone of rotation, and a carbide insert in the form of a cylindrical body with a conical tip on the working side. The holder is usually made of steel with a temporary bending resistance, σ = 140-160 kg / mm ² , and the insert is made of an alloy with a temporary bending resistance σ = 160-175 kg / mm ² .

 However, when the cutter rotates during operation of the machine, the part of the holder adjacent to the carbide insert is quickly worn away (washed out). In this case, the carbide insert is exposed and, when the exposure is 8-10 mm along the length of the insert, the insert, which is not protected by the holder material, is destroyed from bending.

 The closest in technical essence to the proposed one is the cutter for mining machines we took as a prototype (Cutting tool. Catalog of the Krasnoluchsk Machine Plant, Voroshilovogradskaya Pravda Publishing House, 1976, p. 17), containing a holder equipped with a shank and a head, which is located on the front the edges are reinforced with a plate of carbide material (hereinafter referred to as carbide plate), which protects the holder from leaching.

In this case, the working part of the carbide plate is made with a sharpening angle of 68-75 degrees. The holder is usually made of steel grade 35KhGSA with a temporary bending resistance σ = 160-165 kg / mm ² , and the carbide plate is usually made of a material with a temporary bending resistance σ = 160-175 kg / mm ² . The earliest cutter belonging to the cutters of this design, brand I79B, has a holder made of a thickness of 21 mm (hereinafter, by the thickness of the holder means the size of the holder in a cross section half the length of the carbide plate in the direction perpendicular to the main (“soldered” ) the plane of the carbide plate), the carbide plate is 7 mm thick, 22 mm long and weighs 26 g, and the point angle α = 75 degrees.

 A later cutter of this design - a cutter of the ЗР1.80 brand has a holder made of 23 mm thick, a carbide plate - 9 mm thick, 25 mm long and weighing 36 g, and an angle of sharpening α = 75 degrees.

 An even later cutter of this design - a cutter of the ЗР2.80 brand has a holder made in the thickness of 19 mm, a carbide plate - 13 mm thick, 30 mm long and 86 g in weight, and an angle of sharpening α = 68 degrees.

 However, with the I79B cutter, the strength of the carbide plate is insufficient and their frequent breakdowns took place. The energy intensity of the destruction of this cutter is high due to the large angle of sharpening.

 With the ZR180 cutter, the strength of carbide inserts is also unsatisfactory, although there are fewer breakdowns than with the I79B, and also the high energy intensity of failure due to the large sharpening angle.

 Cutter ЗР2.80 has a strength higher than cutter ЗР180. When working on salts and coals without strong inclusions, breakdowns of carbide inserts are less common, but still occur.

 In addition, the energy intensity of fracture by these cutters remains unacceptably high due to the large point angle (68 degrees) and the large width (25 mm) of the massive carbide plate.

 As can be seen from the above, in the practice of designing cutters there is a tendency to ensure the strength of the cutter by increasing the thickness (we took for the prototype cutter -7.9 and 13 mm) and, accordingly, the mass (26, 36 and 86 g) of the carbide plate.

 The technical problem to which the invention is directed is to create a cutter in which the holder, and not the carbide plate, takes on the bending load.

где k - коэффициент, равный 0,25-5,6,
E_пл - модуль упругости материала пластинки, кг/мм²,
E_держ - модуль упругости материала державки, кг/мм²,
σ_пл - временное сопротивление изгибу материала пластинки, кг/мм²,
σ_держ - временное сопротивление изгибу материала державки, кг/мм²,
при этом державка в сечении, соответствующем половине длины пластинки, выполнена по меньшей мере толщиной h_держ, равной

где L_пл - длина пластинки, мм.The problem is solved in that a cutter for mining machines is proposed, comprising at least one plate of carbide material, brazed with a holder provided with a shank, and having a taper angle α of the cutting edge, in which according to the invention the plate is made with a thickness of h _pl , mm, satisfying the following ratio:

where k is a coefficient equal to 0.25-5.6,
E _PL - the modulus of elasticity of the plate material, kg / mm ² ,
E _hold - the modulus of elasticity of the material of the holder, kg / mm ² ,
σ _PL - temporary bending resistance of the plate material, kg / mm ² ,
σ _hold - temporary bending resistance of the material of the holder, kg / mm ² ,
while the holder in the cross section corresponding to half the length of the plate is made of at least a thickness h _holding equal to

where L _PL - the length of the plate, mm

где k - коэффициент, равный 0,25-5,6,
E_пл - модуль упругости материала пластинки, кг/мм²,
E_держ - модуль упругости материала державки, кг/мм²,
σ_пл - временное сопротивление изгибу материала пластинки, кг/мм²,
σ_держ - временное сопротивление изгибу материала державки, кг/мм²,
при этом державка в сечении, соответствующем половине длины пластинки, выполнена по меньшей мере толщиной h_держ, равной

где L_пл - длина пластинки, мм.A variant of a cutter for mining machines is also proposed, comprising at least one carbide plate soldered to a holder provided with a shank, in which according to the invention the plate is made of variable thickness, decreasing to the cutting edge, and the average thickness h _pl , mm, satisfies the following the ratio:

where k is a coefficient equal to 0.25-5.6,
E _PL - the modulus of elasticity of the plate material, kg / mm ² ,
E _hold - the modulus of elasticity of the material of the holder, kg / mm ² ,
σ _PL - temporary bending resistance of the plate material, kg / mm ² ,
σ _hold - temporary bending resistance of the material of the holder, kg / mm ² ,
while the holder in the cross section corresponding to half the length of the plate is made of at least a thickness h _holding equal to

where L _PL - the length of the plate, mm

Preferably, the plate is made with a length of L _PL , mm, satisfying the following ratio: L _PL = k ₁ • h _PL ^0.3 , where k ₁ coefficient equal to 15-25.

The angle of sharpening α is made preferably satisfying the following ratio:
tgα = k ₂ × h $\genfrac{}{}{0ex}{}{\text{0.25}}{\text{pl}}$ ,
where k ₂ is a coefficient equal to 1.15-1.5.

 The point angle of the cutter is preferably 40-60 degrees.

 The carbide plate is preferably made in a thickness of 0.1 - 2.0 mm.

 The carbide plate is preferably made of a length of 8-30 mm.

 Carbide inserts may be mounted relative to each other with or without clearance.

 The essence of the invention lies in the fact that the relationships were established between the properties used for the manufacture of the cutter materials and the optimal thickness of the carbide plate, the thickness of this plate and its length, as well as the thickness and optimal angle of sharpening of the cutter, providing a sufficient (at least three) safety factor for carbide plates, meaning that at critical loads applied to the cutter, at which stresses arising in the holder will be destructive for it, stresses arising in a carbide plate, will be no more than one third of the destructive ones (n ≥ 3).

The actual safety factor "n" of the carbide plate for the selected parameters h _PL , L _PL , and α, if necessary, is determined from the following expression:
n = h _hold / h _PL • (E _hold • σ _PL / (E _PL • σ _hold ).

 Thus, it was possible to create a cutter in which the holder, and not the carbide plate, assumes the bending load.

In this case, the holder can be made of any thickness to take on a bending load with a sufficient margin of safety, but not less than L _PL / 2 • tg α in the section corresponding to half the length of the carbide plate, starting from the tip, since for a real cutter The section of a carbide plate that is most vulnerable to bending is, as practice has shown, its section at half length.

 Thus, based on the above ratios, for real materials commonly used for the manufacture of such cutters, materials, for example, 35KhTSA steel, and VK8 carbide, the real thickness limits of the carbide plate were 0.1-2.01 mm with the plate length 8-30 mm.

In the case of using (if necessary) for the manufacture of a holder of steels with other strength properties (for example, steel ШХ15 with σ = 280 kg / mm ² ) or steel 35ХГСА with a milder heat treatment mode and σ = 130 kg / mm ² ) the plate thickness limits for the adopted coefficient k ₁ = 0.25-5.6 will be wider, namely 0.05-2.47 mm.

 The cutter, the parameters of which correspond to the ratios we have proposed, can significantly reduce the consumption of expensive hard alloy: so, the weight of 2 plates (per cutter) 1 mm thick, 15 mm long and 14 mm wide will be 3.05 g, while the weight of the carbide insert for the RKS cutter is 12 g, and for the cutters ЗР1.80 and ЗР2.80, the weight of the plate is 36 and 86 g, respectively.

 Cutters reinforced with plates with a thickness of 0.1-2.0 mm, it seems possible to give small (40-60 degrees) sharpening angles, which can significantly reduce the energy intensity of the destruction of the developed formation. This comes from the following. It is known that during blunting of incisors working on potassium salts (for example, Starobinsky deposit), up to 3-6 mm along the back face at the carbide plates, chips appear. Chipped carbide along the front face from the feed force, increasing in proportion to the bluntness on the back side. Moreover, the smaller the angle of sharpening, the less chipping begins.) With sharpening angles of α 60 65 degrees, chipping begins with blunting 4-6 mm, with α 55 degrees - with blunting 2.5-4 mm. On experimental incisors with a sharpening angle of 45 degrees, chipping along the front face began with a blunting of 2-2.55 mm.

и надо полагать, что скалывания от усилия подачи у этой пластинки при α 45 град происходить не будет.With thin plates (2 mm or less), hard metal blunting is limited by the thickness of the plates. So for a plate with a thickness of 0.5 mm with α 45 degrees and a back angle β 10 degrees, the maximum blunting Δ ₃ in the hard alloy will not exceed

and it must be assumed that shearing from the feed force of this plate at α 45 degrees will not occur.

 For blades of even smaller thickness (0.2 and 0.1 mm), the maximum bluntness along the rear face will be 0.26 and 0.13 mm, respectively, and shearing from the feed force will not occur even at α 40 deg.

 The implementation of carbide plates with a thickness of 0.5-2.0 mm is currently more preferred. When sintering carbide plates with a thickness of less than 0.5 mm, special techniques have to be applied that limit their warpage, and plates with a thickness of 0.3-0.1 mm are obtained by grinding. The relative difficulties in the manufacture of very thin (0.3-0.1 mm) plates are justified in those cases when a decrease in the energy intensity of destruction is a priority and when relatively decreasing the cutting edge (for example, to 40 degrees) in relatively thick plates (0, 5 mm or more) the cutting edge of the cutter is chipped from the feed force along the rear face.

 The cutter variant is intended for cases when it is necessary to reduce the likelihood of chipping of the cutting edge from the feed force without reducing the average thickness of the plate.

 For cutters with carbide inserts with a thickness of 0.1-2.0 mm, the most optimal point angle is 60-40 degrees.

 An increase in the angle of more than 60 degrees is impractical, since on the one hand it leads to an increase in the energy intensity of destruction, and a decrease in the angle of less than 40 degrees is also undesirable due to the limited strength of the carbide material and steel.

 Due to warping of small-thickness plates during sintering, their length is limited, and the more, the smaller the thickness of the plates. The length of the plates is also limited by the presence of residual (solder) stresses in the hard alloy, solder and steel holder. These stresses are most dangerous for the carbide plate due to its small thickness relative to the holder. Moreover, the shorter the length of the plate, the less solder stresses in it.

 The invention is illustrated by graphic materials, where in FIG. 1 is a schematic representation of the proposed cutter A; in FIG. 2 is a schematic representation of cutter B; in FIG. 3 is a schematic illustration of an embodiment of cutter B; in FIG. 4 is a schematic illustration of cutter A with extreme blunting; figure 5 is a schematic representation of the cutter B with limiting blunting; figure 6 is a schematic representation of the cutter ZR2.80 with limiting blunting.

 The proposed cutter (Fig. 1, 2, 3) contains a carbide plate 1, a steel holder 2 and has a point angle α, a trailing angle β, a cutting edge 3, a front face 4 and a rear face 5.

The carbide plate 1 of cutter A (Fig. 1) is made of 2 VK8 hard alloy plates having E = 5.85 • 10 ⁶ kg / cm ² and δ = 16000 kg / cm ² , 0.7 mm thick and each 15 mm long. The plates 1 can be installed with or without clearance relative to each other. The holder 2 of the cutter A (Fig. 1) is made of steel grade 35KhGSA, having E = 2.1 • 10 ⁶ kg / cm ² and δ = 16000 kg / cm ² , AA thickness 7.5 mm. The angle α is 47 degrees, β - 12 degrees.

Plate 1 of cutter A is made with a thickness of 0.7 mm and, accordingly, the angle α of sharpening is made equal to 45 degrees because potassium salt is on the horizon 264 m of the Beloruskali plant, for which cutter A is intended - the weakest (resistance to cutting ≤ 350 kg / cm) and developed potassium salts and not abrasive. When the thickness of the plate 1 is equal to 0.7 mm, its length is preferably within
L _PL = (15-25) • 0.7 ^0.3 mm = 13.5-22.5 mm
We accept L = 15mm.

The angle α of the sharpening of the cutter is preferable in the range:
tg α = (1.15-1.5) • 0.70 ^0.25 mm = 1.052-1.372,
α = 46.4 - 53.9 degrees.

 We take α = 47 deg.

As indicated above, the actual safety factor of the carbide plate is determined from the expression:
n = h _hold / h _pl • (E _hold • δ _pl ) / (E _pl • δ _hold ),
where h _hold = L _PL / 2 • tg α = 15/2 • 1,072 = 8,043 (mm),
from here n = 8.043 / 0.7 • (2.1 • 10 ⁶ • 16000) / (5.85 • 10 ⁶ • 16000) = 4.124> 3.

The preferred limits of the thickness of the carbide plate 1 for the cutter, the holder 2 of which is made of steel 35HGSA, and the plate 1 of the VK8 alloy in accordance with the stated ratio are:
h _pl = (0.25-5.6) • (2.1 • 10 ⁶ • 16000) / 5.85 • 10 ⁶ • 16000) = 0.09 - 2.01 mm.

 Thus, the plate thickness adopted by us 1 0.7 mm satisfies the stated ratio. Such a cutter can be used in combines of the KShZM and U10KS brands with a load on the cutter up to 600 kg.

Cutter B (Fig. 2) is made of the same materials as cutter A. However, due to the fact that potassium salt at the horizon of 430 m 1 of the Beloruskali mine, for which cutter B is intended to be stronger, has a cutting resistance of 380 kg / cm ² and more abrasive, the thickness of the plate 1 is taken equal to 2 mm

Hence, L _PL = (15-25) • 2.0 ^0.3 = 18.5 - 30.8 mm.

 We accept L = 30 mm.

tg α = (1.15-1.5) • 2.0 ^0.25 = 1.388-1.784,
α = 53.8 - 60.7 degrees.

 We take α = 60 degrees.

h _hold = L _PL / 2 • tg α = 30/2 • 1.732 = 26 (mm),
Hence the actual safety factor of the carbide plate
n = 26/2 • (2.1 • 10 ⁶ • 16000) / (5.85 • 10 ⁶ • 16000) = 4.67> 3.

The thickness of the plate 1 h _PL = 2.0 mm satisfies the stated ratio.

 Such a cutter can be used in PK8 combines with a cutting force of more than 700 kg.

The work of the cutter and its variant consists in the destruction of weak media - salts and coals without strong inclusions. In this case, the edge 3 of the cutter wears out (wears out) during the operation, the cutter is sharpened, wears out again and this happens several times until the resource is fully depleted. In FIG. 4, 5, 6 schematically depict the cutting parts of the cutters A and B, respectively, and for comparison, the cutter ЗР2.80 with the limiting blunting of the cutting edge 3, after which the cutters should be re-sharpened, while the blunting along the rear face 5 is designated as Δ _z and along the front face 4 - Δ _p
As can be seen from FIG. 4, 5, 6, Δ _p - the same for all incisors and in this particular example is 2.5 mm, which corresponds to the same distance traveled or the same operating time per incisor.

The same diagrams also show the removals of the carbide plate 1 during regrinding and the removals 7 of the steel of the holder 2. As seen from FIG. 4, cutter A has a blunt pad Δ _s which is basically a holder steel. In this case, the holder steel practically does not participate in the formation of the feed force and the load from the feed force to the rear platform of the blunting of the cutter is 1 / 3-1 / 10 of the load that would have occurred when using an analogue - cutter of the ЗР2.80 brand when blunting it along the back edges up to 3-6mm. Therefore, the proposed incisor (A, B) blunts along the rear face 3 can reach 10-15 mm to regrind and, accordingly, the life of the proposed incisor to regrind is 2-3 times greater than that of the well-known incisor ЗР2.80 and it must be resharpened in 2 -3 times less frequently, and, as can be seen from FIG. 4, when regrinding, mainly the toolholder steel will be removed. Thus, in the cutter A, made with a plate 1 of a thickness of 0.7 mm, with regrinding, the carbide plate will not be “removed” (sharpened) (see figure 4). In the cutter B, made with a plate 1 with a thickness of 2.0 mm., At regrinding, the carbide plate 1 will be “removed” (sharpened) (see Fig. 5), however, the grinding value will be 15 times less than that of the known cutter ЗР2. 80, as can be seen from FIGS. 5, 6.

This greatly facilitates the process of periodically sharpening cutters, since it is known that toolholder steel is incomparably easier to sharpen than carbide. The implementation of the cutters with a sharpening angle of 45 - 40 degrees can reduce the energy intensity of destruction by at least 25% and, therefore,
- increase the performance of the combine;
- reduce dust formation in the face;
- reduce the yield of small difficult to float fractions and thereby reduce the loss of the final product during the enrichment operation;
- reduce energy consumption per ton of ore mined.

The use of the proposed incisors also allows
- reduce the number of regrinding incisors;
- reduce the consumption of incisors;
- more than an order to reduce the consumption of expensive hard alloy.

Claims (10)

1. The cutter for mining machines, containing at least one plate of carbide material, brazed with a holder equipped with a shank, and having a point angle α of the cutting edge, characterized in that the plate is made of thickness h _PL , mm, the average value of which satisfies the following ratio:

where k is a coefficient equal to 0.25 - 5.6;
E _PL - the modulus of elasticity of the plate material, kg / mm ² ;
E _hold - the modulus of elasticity of the material of the holder, kg / mm ² ;
σ _PL - temporary bending resistance of the plate material, kg / mm ² ;
σ _hold - temporary bending resistance of the material of the holder, kg / mm ² ,
while the holder in the cross section corresponding to half the length of the plate is made of at least a thickness h _holding equal to

where L _PL - the length of the carbide plate, mm 2. The cutter according to claim 1, characterized in that the carbide plate is preferably made of a length L _PL , mm, satisfying the following ratio:
L _PL = k ₁ • h $\genfrac{}{}{0ex}{}{\text{0.3}}{\text{pl}}$ ,
where k ₁ is a coefficient equal to 15 - 25. 3. The cutter according to claim 1, characterized in that the angle of sharpening α of the cutting edge is made preferably satisfying the following ratio:
tgα = k ₂ • h $\genfrac{}{}{0ex}{}{\text{0.25}}{\text{pl}}$ ,
where k ₂ is a coefficient equal to 1.15 - 1.5.  4. The cutter according to claim 1, characterized in that the carbide inserts are installed without a gap relative to one another.  5. The cutter according to claim 1, characterized in that the carbide inserts are installed with a gap relative to one another. 6. The cutter for mining machines, containing at least one plate of carbide material, brazed with a toolholder equipped with a shank, and having a point angle α of the cutting edge, characterized in that the plate is made of a thickness h _PL , decreasing to the cutting edge, and the average value thickness h _PL , mm, satisfies the following ratio:

where k is a coefficient equal to 0.25 - 5.6;
E _PL - the modulus of elasticity of the plate material, kg / mm ² ;
E _hold - the modulus of elasticity of the material of the holder, kg / mm ² ;
σ _PL - temporary bending resistance of the plate material, kg / mm ² ;
σ _hold - temporary bending resistance of the material of the holder, kg / mm ² ,
while the holder in the cross section corresponding to half the length of the plate is made of at least a thickness h _holding equal to

where L _PL - the length of the carbide plate, mm 7. The cutter according to claim 6, characterized in that the carbide plate is preferably made of a length L _PL , mm, satisfying the following ratio:
L _PL = k ₁ • h $\genfrac{}{}{0ex}{}{\text{0.3}}{\text{pl}}$ ,
where k ₁ is a coefficient equal to 15 - 25. 8. The cutter according to claim 6, characterized in that the angle of sharpening α of the cutting edge is made preferably satisfying the following ratio:
tgα = k ₂ • h $\genfrac{}{}{0ex}{}{\text{0.25}}{\text{pl}}$ ,
where k ₂ is a coefficient equal to 1.15 - 1.5.  9. The cutter according to claim 6, characterized in that the carbide inserts are installed without a gap relative to one another.  10. The cutter according to claim 6, characterized in that the carbide inserts are installed with a gap relative to one another.

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