RU2259905C2 - Method for controlling speed mode of drum flying shears with electric connection of transporting and cutting apparatuses at measure cutting of rolled strip - Google Patents

Abstract

FIELD: rolled sheet production.

SUBSTANCE: parameters of speed mode of flying shears are determined according to division of the whole range of length values of cut sheets by two intervals. In one interval strip is cut at using two cutters in each drum; in other interval strip is cut at using one cutter in each drum. Limit length of sheets between intervals is determined at satisfying condition of equal cutting speed at using one or two cutters in each drum.

EFFECT: enhanced efficiency of shears providing high quality of strip surface.

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Description

The invention relates to sheet rolling production and is intended for use in installations of drum flying shears for dimensional cutting strip.

A known method of controlling the speed of installation of flying drum scissors (A.N. Iroshnikov, Flying scissors., M., Mashgiz, 1950, p.38-41, 48-49), the set of which includes feed rollers and drum scissors proper, with In this, each of the devices has an individual electric drive connected to each other by an electric control system for performing dimensional cutting of the strip.

For dimensional scissors, the length of the cut sheets is a function of the number of revolutions of the feed rollers and scissors drums or, in other words, depends on the speed of the strip in the scissors and the time intervals between successive cuts.

In the described installation of drum flying scissors, a change in the length of the cut sheets is achieved by changing the average speed of the strip while maintaining the speed of rotation of the drums constant between successive cuts. To maintain the equality of the strip speed and the speed of the knives during the cutting process (one of the conditions for ensuring the accuracy of the length of the cut sheets), the feed rollers receive a variable angular speed from the drive, the value of which corresponds to the synchronization condition when cutting.

The disadvantage of this method of controlling the speed of installation of flying drum scissors is the unstable movement of the strip, leading to rubbing on its surface during sharp acceleration or braking, longitudinal folding of the strip, especially of small thicknesses, due to large inertial loads, etc.

As a prototype, a method for controlling the high-speed mode of installation of flying drum scissors was selected (V.D. Sheinkman and others. Modern trends in the development of designs of flying shears for cutting tin. Collection of scientific works of VNIIMETMASH. Research and improvement of processes and machines for processing rolled metal, M., 1990, p.107-108), a transporting and cutting device in which they have separate electric drives, interconnected by an electric automated control system for measuring strip cutting.

In the installation of drum flying scissors according to the prototype, a change in the length of the cut sheets is achieved by changing the average speed of rotation of the drums between successive cuts while maintaining the speed of the strip constant.

To maintain the equality of the strip speed and the speed of the knives during the cutting process, the drums receive a variable angular velocity from the drive, the value of which during cutting is selected from the synchronization conditions.

Compared with the previous, this method allows you to keep the speed of the strip stable, to avoid its nativ and folding, to increase the accuracy of the length of the sheets.

However, large dynamic loads on the scissors drive from unevenly rotating drums when cutting sheets whose length differs from the main one (the main length of the sheet is the length equal to the circumference along which the cutting edge of the knife rotates), lead to the need to sharply reduce the speed of scissors and strips in depending on the degree of deviation of the sheet length from the base.

Moreover, in this method of controlling the high-speed mode, the maximum speed of scissors at various sheet lengths is calculated based on the design parameters of the scissors, including the structurally specified number of knives on each drum, which is not changed when cutting the entire range of sheet lengths.

In the described example, the main length of the sheets is 724 mm and one knife is installed on each of the drums. The cutting of the main length is carried out at a speed of 6.4 m / s. When cutting a length of 522 mm, the strip speed decreases to 2.3 m / s, i.e. the performance of scissors is reduced by almost 3 times.

The basis of the invention is the task of increasing the productivity of scissors while at the same time high quality of the strip surface.

This problem is solved due to the technical result, which consists in increasing the cutting speed of scissors when cutting strips into sheets in a wide range of their lengths.

To achieve the aforementioned result in the method for controlling the high-speed installation mode of drum flying scissors with electrical connection of the conveying and cutting devices when measuring strip rolling, which consists in the fact that the strip is set to a constant speed of movement from the conveying device, the shear drums are set to a variable angular velocity, the average value which depends on the length of the cut sheet, and the drums in the process of cutting set the speed from the condition of synchronizing the linear speeds of the knives and strips, while the maximum cutting speeds of the scissors are determined from the condition of permissible dynamic loads in the scissors drive from drums rotating with a variable angular velocity, according to the invention, the cutting speeds of the scissors are determined based on the breakdown of the entire range of lengths of the cut sheets into two intervals, while in one interval the strip cut using two knives on each drum, in the other - using one knife on each drum, and the boundary length of sheets between intervals is determined from the condition of equality scab cutting shears with one or two blades for each drum.

As a result of a comparative analysis of the proposed method with the prototype, it was found that they have the following common features:

- lane set a constant speed of movement from the conveying device;

- scissor drums are given a variable angular velocity;

- the average value of the angular velocity depends on the length of the cut sheet;

- the drums in the process of cutting set the speed from the condition of synchronizing the linear speeds of the knives and strip;

- the maximum cutting speed of the scissors is determined from the condition of permissible dynamic loads in the drive of the scissors from the drums rotating with a variable angular speed;

as well as distinguishing features:

- the cutting speed of the scissors is determined based on the breakdown of the entire range of lengths of the cut sheets into two intervals;

- in one interval, the strip is cut using one knife on each drum;

- in another interval, the strip is cut using two knives on each drum;

- the boundary length of the sheets between the intervals is determined from the condition of equality of cutting speeds of scissors using one or two knives on each drum.

Thus, the proposed method for controlling the high-speed mode of installation of drum scissors has new conditions for operations.

Between the distinguishing features and the achieved technical result, there is a causal relationship.

By dividing the entire range of lengths of cut sheets into two intervals and determining the speed characteristics of the scissors in each interval from the condition of permissible dynamic loads of the scissors drive from the drums rotating with a variable angular velocity, it was possible to cut in each interval with the highest possible speeds, which led to an increase in the productivity of the drum unit flying scissors.

The choice of the boundary length of the sheets between the intervals from the condition of equality of the cutting speeds of the scissors using one or two knives on each made it possible to determine the optimal cutting speeds for the intervals of the range of cut lengths, ensuring a high cutting speed in these intervals and high productivity of the scissors.

The exception from the above set of distinctive features of at least one does not ensure the achievement of a technical result.

The inventive method is not known from the prior art and therefore it is new.

The proposed method has an inventive step, because This method for controlling the high-speed mode of installation of drum flying scissors with electrical connection for specialists does not explicitly follow from the prior art.

The inventive method is industrially applicable in the units of transverse cutting adjustage departments of metallurgical plants. In particular, the claimed method of controlling the speed of installation of drum flying scissors was used in the development of the technical design of scissors for the Severstal steel mill (Cherepovets, Russia) installed in the transverse cutting unit of the strip 0.5-2.5 × 1600 (contract No. 22 / 506 dated 03.16.01).

Thus, the claimed method of controlling the speed of installation of drum flying scissors can be provided with legal protection, because it is new, has an inventive step and is industrially applicable, i.e. meets all the criteria of the invention.

The invention is illustrated by drawings, which depict:

figure 1 is a kinematic diagram of the installation of flying drum scissors;

figure 2 - tachograms of the peripheral speed of the knives when cutting various lengths of sheets depending on the phase position of the knives;

figure 3 - graphs of the changes in the speed of the knives when cutting, depending on the length of the cut sheets within a given range of lengths.

For dimensional cutting of strip 1 (Fig. 1), the installation of flying drum scissors has a transport device consisting of lower 2 and upper 3 feed rollers associated with electric motor 4. When the rollers are uniformly rotated, the strip receives a given speed V _n .

Measured cutting is carried out by a cutting device consisting of upper 5 and lower 6 drums of equal diameter, with knives 7, 8, 9, 10 installed on them. The drums are connected by gear wheels 11 and are driven into rotation with a constant or variable angular speed from electric motor 12. Electric motors 4 and 12 are in electrical communication with each other, made, for example, in the form of a system with numerical program control, which ensures high accuracy of working out the parameters set for scissors.

The knives move along circular paths with a radius r _n , the same for the upper 5 and lower 6 drums.

Measured cutting strip 1 can also be carried out when each of the drums 5, 6 is installed on one knife, which are mated with each revolution of the drums.

Consider, for example, the conditions for measuring cutting strip 1 when installed on the upper 5 and lower 6 reels, one knife each. When the speed of the strip V _n and the time between successive cuts t _{c the} cut length is:

If the speed of the knives V _n along circular paths is constant and equal to the speed of the strip V _n , then the sheet length is cut, equal to the main one, i.e. equal to the length of the circular path 2πr _n . In this case, there are no dynamic loads on the electric motor 12 and the real speeds in the transverse cutting units reach 5-6 m / s. For example, when cutting the main sheet length of 2.4 m (with a drum diameter of 0.78 m), the strip speed in the transverse cutting units of 0.6-3 × 1600 of the Severstal steel mill reaches 5 m / s.

If it is necessary to cut sheets longer than the main length, then to increase t _{c, the} average angular rotation speed ω _{cf of the} drums is reduced (respectively, the linear speed of the knives V _n ), and the synchronization conditions, i.e. V _n = V _n = ω _p r _n , where ω _p - the angular velocity of the drums during cutting reach, changing the speed of the knives during the cycle between successive cuts. For example, a graph of the speed of knives when cutting a length of 3.5 m is shown in figa). Due to the dynamic loads arising on the electric motor 12, the speed of the strip should be reduced to a level limited by the characteristics of the electric drive. The speed of the strip and knives during the cutting process, taking into account the above, can be determined from a system of equations compiled under the condition of acceleration-braking of the drums in a linear relationship:

where ω _min is the minimum angular velocity of rotation of the drums during their movement with variable speed;

M _din - the dynamic moment in the drive of scissors;

I - moment of inertia of the drums and drive;

ε is the angular acceleration of the drums.

Then

For example, with M _dyne = 28435 Nm, the moment of inertia of the drums I = 1767 kgm ² ; L _Otr = 3.5 m; r _n = 0.39 m the speed of the knives during cutting should not exceed 4.3 m / s.

If it is necessary to cut off sheets shorter than the main length, then to reduce t _u, increase the average angular rotation speed ω _{cf of the} drums (respectively, the linear speed of the knives V _n ), and the synchronization conditions are fulfilled in the same way as in the previous case.

For example, a graph of the speed of knives when cutting a length of 2 m is shown in Fig.2b). At the time of cutting, the speed of the knives decreases, in the period between two consecutive cuts increases.

Determining the speed of knives according to the above method gives the following formula:

Calculation with the previously selected initial data and L _sp = 2 m gives a limitation of the speed of the knives to a value of 3.7 m / s.

Next, we consider the conditions for measuring cutting of strip 1 when installed on the upper 5 and lower 6 reels, two knives.

In this case, cutting the strip into measured lengths occurs at 1/2 rotation of the drum and the main length of the sheets is two times less than with a single knife.

можно резать при равномерной скорости вращения барабанов и скорость полосы поднять до 5 м/с (более высокая скорость недостижима из условий работы агрегата).In this case, the main sheet lengths

can be cut at a uniform speed of rotation of the drums and the strip speed can be raised to 5 m / s (a higher speed is unattainable from the operating conditions of the unit).

When cutting lengths longer or shorter than the main (1.2 m), the mode of rotation of the drums and the movement of the knives does not fundamentally differ from the described mode with one knife, however, it must be taken into account that in the case of two knives, the acceleration-braking mode occurs at an angle of rotation drum equal to π instead of 1π with one knife.

The speed of the knives during cutting (the length of the sheets is longer than the main one) is determined by the formula:

and with sheet lengths shorter than the main:

According to the formula (3-6), graphs of changes in the speed of knives during cutting are plotted depending on the length of the cut sheets within a given range of lengths and when one or two knives are installed on the drum. The shaded area of the graph shows the possibility of increasing the speed of the knives and strip when varying the number of knives on each drum.

The described method for controlling the high-speed installation mode of drum flying scissors is to select the values of the main cut sheet lengths (based on the source data), to break down the entire range of lengths of cut sheets into two intervals, in one of which the strip is cut using two knives on each drum, in friend - one knife.

The boundary length of the sheets between the intervals is determined by calculation if the cutting speeds of the scissors are equal using one or two knives (from the equality V _n according to formulas (3) and (6)):

From all the described it is clear that the application of the considered method of controlling the high-speed mode allows to increase the productivity of the installations of drum flying scissors, without increasing the power of their drive while ensuring high quality of the surface of the cut strip.

Claims (1)

A method of controlling the speed of the installation of flying drum scissors with electrical connection of the transporting and cutting devices for dimensional cutting of strip products, namely, that the strip is set to a constant speed of movement from the conveying device, the shears of the shears are set to a variable angular velocity, the average value of which depends on the length of the cut sheet , and the drums during the cutting process are set the speed from the condition of synchronizing the linear speeds of the knives and strip, while the maximum shear speeds are determined dividing from the condition of permissible dynamic loads in the scissors drive from drums rotating with a variable angular speed, characterized in that the shear cutting speeds are determined based on the breakdown of the entire range of lengths of the cut sheets into two intervals, while in one interval the strip is cut using each drum two knives, in the other - using one knife on each drum, and the boundary length of the sheets between the intervals is determined from the condition that the cutting speeds of the scissors are equal using one or two n burns on each drum.

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