RU2105641C1 - Method of slab cutting - Google Patents

Abstract

FIELD: plastic metal working. SUBSTANCE: separation of slab is effected by means of continuous vertical and horizontal movement of one of the blades towards the other with a subsequent covering of their cutting edges; the speed of blade horizontal movement is

Description

 The invention relates to the processing of metals by pressure, in particular to methods for cutting piece products after rolling.

A known method of cutting products with wedge-shaped knives with cutting edges mounted towards each other in the cutting plane by moving the knives in parallel until their cutting edges touch each other [1]
The disadvantage of this method is that the complete cutting of the workpiece is possible only when the mutual contact of the cutting edges of the knives. However, an inaccurate stop of the knives leads to a significant overload of the scissors and their breakage. However, the rapid blunting of the cutting edges limits the possibility of using this method on scissors with an unregulated value of the stroke of the knives, for example, with a crank mechanism for their drive.

 To increase the reliability of scissors and guarantee the cutting of products, cutting is usually performed with knives offset from each other while moving them in parallel in the cutting plane without touching the cutting edges.

Closest to the invention in technical essence and the achieved result is a method of cutting rolled billets, carried out in parallel-translational movement of one of the knives towards the other with a constant gap between their side planes in the cutting zone [2]
Cutting by this method is carried out with the overlapping of the cutting edges of the knives to ensure guaranteed separation of the cut parts of the roll.

 The necessary amount of overlap is taken depending on the gap between the side edges of the knife δ and the height of the cut section H (see, for example, Korolev A. A. Design and calculation of machines and mechanisms of rolling mills. M. Metallurgy, 1969, p.263).

 The lateral clearance d is assumed to be proportional to the initial cross-sectional height of the cut workpiece and remains constant, while the section height decreases as the knives approach each other. Therefore, with respect to the smaller cross-section, this lateral clearance d exceeds the permissible value and leads to an increase in cutting forces (Tselikov A.I. et al. Machines and assemblies of metallurgical plants T3. Second ed. M. Metallurgy, 1988, p. 389- 390).

 With an increase in cutting forces, energy costs increase. Due to the overestimated value of the lateral clearance when cutting the strip, the burr increases, worsening the quality of the ends, which leads to additional metal losses.

 The objective of the invention is the creation of such a cutting method that would reduce the cutting forces and energy costs, as well as reduce the burrs of the cut parts of the metal workpiece.

где V_B скорость перемещения ножей в вертикальной плоскости;
δ_o начальный боковой зазор между ножами;
δ_min минимально допустимый боковой зазор, мм;
H_o высота разрезаемой заготовки, мм.The problem is solved as follows: in a method of cutting a rolling workpiece, including the separation of the workpiece and the detachable part by continuously moving vertically one of the knives in the direction of the other with subsequent overlapping of their cutting edges, the knife is told horizontal movement at a speed of V _g towards the other until the cutting edges are overlapped, wherein

where V _{B the} speed of movement of the knives in a vertical plane;
δ _o initial lateral clearance between the knives;
δ _{min the} minimum allowable lateral clearance, mm;
H _{o the} height of the cut workpiece, mm

По мере сближения ножей высота разрезаемого сечения уменьшается прямо пропорционально вертикальной скорости перемещения ножа, чтобы обеспечить оптимальные условия процесса за весь период резания, в такой же пропорции должен изменяться боковой зазор между ножами, что достигается при данном соотношении скоростей. Следовательно, в данном случае при определении усилий резания коэффициентом, учитывающим увеличение усилий резания при увеличении бокового зазора (см. Целиков А.И. и др. Машины и агрегаты металлургических заводов Т3. М. Металлургия, 1988, с.390), можно пренебречь, т.е. принимать его значение ≈1. При этом усилия резания понижаются на 25-30% а следовательно, снижается и расход электроэнергии при разрезании заготовок. По мере сближения ножей уменьшается абсолютная величина бокового зазора, в результате чего повышается степень надреза металла при сближении ножей, что способствует более эффективному отделению разрезаемых частей заготовки без значительного перекрытия кромок ножей, это позволяет уменьшить степень перекрытия ножей, принимая минимальные допуски (см. там же, с.387), а следовательно, уменьшить общий ход ножей и величину холостого перемещения. Улучшается качество торцов, так как снижается величина образуемого при разделении полос заусенца в связи с уменьшением бокового зазора и затекаемого в него металла в период дорезания заготовки.A distinctive feature of this method is that the knives come together not in one plane, but in two mutually perpendicular planes. The movement of the knife in the horizontal direction is carried out with a constant ratio

As the knives approach, the height of the cut section decreases in direct proportion to the vertical speed of the knife to ensure optimal process conditions for the entire cutting period, the lateral clearance between the knives should be changed in the same proportion, which is achieved with this ratio of speeds. Therefore, in this case, when determining cutting forces by a coefficient that takes into account an increase in cutting forces with an increase in lateral clearance (see Tselikov A.I. et al. Machines and Units of Metallurgical Plants T3. M. Metallurgy, 1988, p. 390), , i.e. take its value ≈1. At the same time, the cutting forces are reduced by 25-30% and, consequently, the energy consumption when cutting workpieces is also reduced. As the knives come closer, the absolute value of the lateral gap decreases, resulting in an increase in the degree of metal cut when the knives come closer, which contributes to a more efficient separation of the cut parts of the workpiece without significant overlap of the edges of the knives, this allows to reduce the degree of overlap of the knives, taking minimal tolerances (see ibid. , p. 387), and therefore, reduce the overall stroke of the knives and the value of idle movement. The quality of the ends improves, since the size of the burr formed during the separation of the bands decreases due to a decrease in the lateral gap and the metal flowed into it during the cutting of the workpiece.

 A known method of cutting products from soft metals (see RF patent N 2008143, B 23 D 15/02, 1990) with the movement of the knife in the vertical and horizontal planes. However, each type of movement does not occur simultaneously, sequentially, first in a vertical plane until the horizontal edges of the knives come closer by the amount of lateral clearance, and then the horizontal movement of the knives to cut the metal with overlapping knives in the horizontal plane in order to increase the degree of overlap of the knives with increasing wear cutting edges. In this method, during the period of metal cutting, the horizontal faces perform the function of the side, and the side - horizontal. Moreover, during the entire cutting process, the lateral gap between the knives remains unchanged and equal to the initial value, i.e. The known method does not reduce the cutting forces and the size of the burr.

 In the method of cutting products (ed. St. 1326395, class B 23 D 23/00, 06/27/83) with the movement of the knife in the horizontal and vertical directions, both types of movement are performed in the same plane (cutting plane). The horizontal movement of the knife here provides the possibility of cutting not over the entire section at the same time, but in separate parts, which allows to reduce the cutting force, however, the overall cutting work is not reduced, since the path traveled by the knife increases. Therefore, this process cannot lead to a reduction in energy costs. The horizontal movement of the knife in the cutting plane does not affect the formation of the burr and its size.

 Thus, a comparison of the claimed solution with other technical solutions shows that the features introduced into it are known in the art, however, the conditions for their use are new and they exhibit new properties, which leads to a change in cutting conditions: reduced cutting forces and energy costs, as well as improved quality cut ends of the workpiece by changing the path of the mutual movement of the knives. This allows us to conclude that the claimed invention has the criterion of "inventive step".

 In FIG. 1 shows the initial position of the knives; in FIG. 2 diagram of the movement of knives in the first cutting period; in FIG. 3 position of the knives at the end of the first cutting period; in FIG. 4 the same during the period of metal cutting; in FIG. 5 ends of the cut workpiece; in FIG. 6 kinematics of scissors to explain their work.

 The method of cutting rolling stocks is as follows.

The cut product 1 is placed between the knives 2 and 3, installed with an initial lateral clearance. By turning on the drive, the movable knife is notified of a vertical movement in the direction of the other and at the same time horizontal with a speed of V _g , at which the side planes of the knives approach each other by the amount of the minimum clearance. Then the horizontal movement of the knife is stopped and the workpiece is cut by moving the knife in a vertical plane.

 The knives return to their original position in the reverse order.

 As an example, we consider the possibility of cutting a workpiece by the proposed method on scissors with a crank-crank cutting mechanism mounted on large-billet mills, in particular blooming (A. Korolev, Design and calculation of machines and mechanisms of rolling mills. M. Metallurgy, 1969, p. 239-250).

 On scissors, low-carbon steels are cut: steel 10, steel 20, st. 3 and others. Cutting is carried out by turning the crank shaft 4 around point 5 by raising the lower slide in vertical guides with the upper knife fixed.

 To inform the lower knife of horizontal movement, its guides 6 are inclined.

С целью предотвращения утыкания ножей примем δ_min= 4-5 мм. Боковой зазор между ножами принимаем δ_o= (0,05)H_o (Целиков А.И. и др. Машины и агрегаты металлургических заводов Т3, вып. второй. М. Металлургия, 1988, с.400).Slope angle tangent

In order to prevent the sticking of knives, we take δ _min = 4-5 mm. We take the lateral gap between the knives δ _o = (0.05) H _o (Tselikov A.I. et al. Machines and assemblies of metallurgical plants T3, second issue. M. Metallurgy, 1988, p. 400).

α = 2^°.
Перекрытие режущих кромок ножей принимаем Δ_min= 10 мм (см. там же, с. 387).Scissors are designed for cutting blooms with a section of 350x350 and slabs 200x900. Take the average height of the workpiece 300 mm, then

α = 2 ^° .
Overlap of the cutting edges of the knives take Δ _min = 10 mm (see ibid., P. 387).

 Due to the small angle of inclination of the guides, the lateral movement of the knives continues even when their cutting edges overlap.

The lateral displacement of the knives during the overlapping of their cutting edges will be
X = Δ _min tgα = 10 • 0.036 = 0.4 mm,
i.e., the minimum lateral clearance at the end of the cutting period is 4.6 mm, which corresponds to the permissible value.

Thus, during the entire cutting period, the movement of the lower knife can be carried out in inclined guides with an angle of inclination of 2 ^o , which does not require significant adjustment of the scissors. Therefore, for the implementation of the proposed method can be used typical scissors, using inclined guides for a movable knife.

 The calculation of cutting forces and engine power for scissors with an existing cutting method is considered in the book. Korolev A.A. 1969, p. 237-252.

For comparison, we will calculate these parameters when cutting workpieces with a cross section HxB = 200x900 = 0.18 m ² , the proposed method.

Minimum cutting temperature 950 ^o C; at the same temperature for alloy steel σ _in ≈ σ _s 75 mn / m ² .

The maximum cutting force is determined by the formula
P _max = k ₁ k ₂ k ₃ σ _in BH (1-ε _in ),
where k ₁ = 0.6-0.7; k ₂ = coefficient taking into account the blunting of knives; k ₃ coefficient taking into account the increase in lateral clearance; ε _in - the value of the relative indentation of the knives.

We take k ₂ = 1.2, k ₃ = 1.05 (instead of 1.25), ε _is 0.3. Then P _max = 0.7 • 1.2 • 1.05 (1-0.3) 75 • 0.18 = 8.3 MH.

The shoulder of the force P _max , a = 0.22 m, the friction shoulder a _tr = 0.052 m.

Thus, the total maximum moment corresponding to P _max ,
M _st = 8.4 (0.22 + 0.052) = 2.485 MH • m.

Average moment for the period of own cutting
M _cf. = M _st / 1.4 = 1.775 MH.

Cutting work
A = M _cp • φ,
where φ is the angle of rotation of the shear shaft during the period of cutting itself;
φ = φ _max -φ _ref = 169-98 = 71 ^° = 1.239 rad.
In this way,
A _rez = 1.775 • 1.239 = 2.2 MH • m.

Cutting work when cutting a slab in an existing way
A _cut = 1.95 • 1.239 = 2.42 MH • m.

 It can be seen from the data presented that both the cutting forces and the cutting work decreased approximately 1.2 times.

ЫяIf we assume that the size of the burr corresponds to about half the volume of metal enclosed between the side faces of the knives when they overlap, then in the existing method of cutting
v _c = (Δ • δ _o • B) / 2 = 15 • 15 • 900/2 = 101 250 mm ³ ,
in the proposed method of cutting
v _p = (Δ _min • δ _min • B) / 2 = 10 • 5 • 900/2 = 22500 mm ³ .
Those. the size of the burr will decrease approximately

Yy

Claims (1)

A method of cutting a rolling workpiece, comprising separating the workpiece and the detachable part by continuously moving vertically one of the knives in the direction of the other with subsequent overlapping of their cutting edges, characterized in that the knife is informed of horizontal movement at a speed of v ₂ towards the other until the cutting edges overlap, while

where v _{is the} speed of movement of the knives in the vertical plane, mm / s;
δ _o initial lateral clearance between the knives, mm;
δ _{min the} minimum allowable lateral clearance, mm;
N _{about the} height of the cut workpiece, mm

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