RU2245294C2 - Method of and device for moment protection of boom crane by signals from support pickups - Google Patents

Abstract

FIELD: mechanical engineering; materials handling equipment.

SUBSTANCE: in proposed case functions of overturning moment and nominal forces of supports are synthesized from signals of support pickups. Overturning moment is reduced to one "window" whose upper limit corresponds to maximum of overturning moment, and operation of protection and is defined by constant value of restoring moment which depends on size of support outline and mass of counterweight. Created no-program device is adaptive to overturning moment and distribution of forces in supports and contributes to correct mounting of crane on supports from traveling position. Horizontal arrangement of platform and nominal distribution of forces of supports are maintained. Mounting of crane on supports is provided even is deviation of actual forces in supports from nominal values is revealed.

EFFECT: provision of protection of higher reliability and accuracy, improved service and dynamic characteristics of crane.

6 cl, 4 dwg

Description

The invention relates to lifting and handling equipment, and in particular to protection devices for jib cranes. Jib crane protection devices using support sensor signals have not found an industrial solution.

We know the system C 30-1 VNIISStroydormash [1], used in addition to the load limiter. The basis of this system is the minimum pressure sensors built into the hydraulic system of each support, which are activated when the pressure (force) in the hydraulic support decreases below the set value, for example, 20 kg / cm ² with a maximum pressure reaching 200 kg / cm ² .

With the growth of the tipping moment, the unloading of the supports located behind the tipping line occurs. When the pressure drops below the set value, the electrical contacts of the pressure sensors open. The electrical connection diagram of the contacts of the sensors provides the possibility of unloading one support with the opening of the contact, if the other support, which is located beyond the tipping line, has a force (pressure) greater than the minimum value. If this condition is not met, the system shuts off the crane drive.

A device for instant protection according to the patent [2], containing the sensors of the supports and a device for calculating the signals of the sensors supports the coordinates of the center of mass of the crane. For safe operation of the crane, it is necessary that the coordinates of the center of mass be within the contour of a rectangle located inside the reference contour (shaded area in figb).

On figa shows a diagram of the static loads on the crane with a support contour of size a · in with the eccentricity of the axis of the turntable n and the angle of the arrow in the plan α (designation of the support contour according to the patent [2] is shown in fig.1b).

With the help of adders and subtractors in the device according to [2] the amounts are formed:

and difference modules

where P _i is the force in the i-th support, P is the sum of the efforts of all the supports.

The stability conditions of the crane are determined by the expressions:

where C = L ₁ / L; D = l _i / 1.

Consider the function of the nominal forces in the supports [3]

where M sinα, M cosα are the components of the tipping moment M relative to the Y and X axes, Fn is the moment caused by the eccentricity of the axis of the turntable. Having expressed the expressions (2) and (3) of the patent through the functions of the nominal efforts from (4) ... (8) we obtain:

where M cosα = Bl; M sinα + Fn = AL, N = P.

In the case of complete unloading of the support R _c = P = 0, the forces in the remaining supports are equal

Subsequently substituting expressions (10) ... (14) in (2) and (3), we obtain expressions for the x, y coordinates of the center of mass with a three-point bearing, which fully corresponds to expression (9) for four-point bearing. In fact, the center of mass with the tricycle support is inside the triangle. Therefore, in [2], additional protection is provided for minimizing the effort in the supports in accordance with the expression P _i ≤ α P, where P _i is the force in the i-th support, for which four comparators are used.

The considered protection system for the components of the tipping moment does not take into account the change in the sign of the moment caused by the eccentricity when turning and does not allow the crane to work when one of the supports located behind the tipping line is disconnected from the base, which is allowed, for example, by the "Rules" of Gosgortekhnadzor. Reliability, informativeness, the functional and operational characteristics of the system are low, which stems from the “switch” method, which is the basis of its operation. These disadvantages are eliminated in the proposed method of protection.

The essence of the method is the synthesis of supports sensors signals: the function of the tipping moment and the nominal effort in the crane supports. In this case, the overturning moment is reduced to one “window” (scale), the size of which corresponds to the maximum overturning moment and the operation of the protection and is determined by the constant value of the restoring moment. The method allows to create protection devices that are adaptive to the tipping moment and the distribution of forces in the supports, as well as to create a device for installing the crane from the transport position on the supports in compliance with the horizontal platform and the nominal distribution of the support forces.

Consider a method of synthesizing a tipping moment from the signals of the support sensors. Pairwise summing the signals of the sensors belonging to each tipping rib and subtracting the half-sum of the stress signals of all the supports for the cases of four-support and three-support bearing of the crane, respectively, the expressions ((4), ..., (7), (10), ... (13) ) we obtain the following equalities.

From (15), ..., (18) it follows that the sums S ₇ , ..., S ₁₀ do not depend on the complete unloading of one support, for example, R _C = 0. The same applies to the case of incomplete unloading of the support [4]. Multiplying (15) and (16) by c, and (17) and (18) by a we get

where F = N * -g _h = const, N * = NQ _G , N is the total mass of the crane with the load, G _H , Q _G is the mass of the fixed part of the crane and the load, respectively, n is the eccentricity.

Eliminating the term Fn from (19), we obtain the moment component M sinα and determine the total moment M equal to

Moreover, the function of the full overturning moment is determined by the expression.

G_i Gї _d - соответственно массы: груза, головки стрелы, i-ой секции стрелы, противовеса и приведенной к нему поворотной платформы, х - полная величина выдвижения секций телескопической стрелы, l₁ - длина первой базовой секции стрелы, φ - угол наклона стрелы, l_kop - коррекция на деформацию стрелы, R, r - геометрические размеры.Where

G _i Gї _d - respectively the masses: of the load, the boom head, the i-th boom section, the counterweight and the turntable brought to it, x - the total extension of the telescopic boom sections, l ₁ - the length of the first base boom section, φ - the boom angle , l _kop - correction for the deformation of the arrow, R, r - geometric dimensions.

Thus, the synthesized moment automatically takes into account the moment loads from the masses of the boom and the load, taking into account their functional relationships with variable parameters of the boom.

Due to the fact that according to the "Rules" of the Gosgortekhnadzor, the stability of the crane is determined relative to the edge of its minimum stability, and in terms of characteristics they are assumed to be circular, the stability equation has the form.

where a is the size of the reference contour, To _zu is the safety factor.

Due to the independence of the sums S ₇ , ..., S ₈ - functions (15), ..., (18) from the distribution of forces in the supports they are used to synthesize the nominal loads in the supports. To do this, form the following amounts:

The nominal forces of the supports (24) are used to calculate the deviation from them of the actual forces in the supports, determined by the signals of the respective sensors. For example, in the case of a three-support bearing of the crane (R * _c = 0), the force deviations Δ R _{i are} determined in accordance with the expressions (10), ..., (13) and (24)

In the proposed method, the difference between the actual and nominal efforts of the supports is used:

1. For additional protection of the crane during its operation, taking into account the deviation of the efforts in the supports from the nominal, caused, for example, by subsidence, of the soil under the support or leak in its hydraulic system.

2. For the correct installation of the crane on supports from the transport state with the simultaneous observance of two conditions: the horizontal platform and the nominal distribution of forces in them. Moreover, if the first condition is satisfied to some extent by known devices, the second, due to the lack of feedback on the efforts in the bearings, cannot be performed in a known manner, which reduces the nominal stability of the crane. The proposed method allows the creation of a protection system that is adaptive to moment loads and forces in the supports.

The implementation of the method allows the creation of protection devices by controlling the speeds of the crane drives as a function of the tipping moment or the efforts in the bearings, to reduce the oscillations of the crane due to their active damping by a negative feedback signal on the rate of change of the tipping moment and the speed of lifting the load, and also to exclude some sources of oscillation, for example boom when it is "raising-lowering" caused by a non-linear transfer function of the speed of the pusher-boom.

As a result, the reliability of the crane increases and its operational characteristics expand.

Checking the accuracy of the protection system using the proposed method on the crane is carried out according to its passport freight characteristics.

DEVICE FOR IMPLEMENTING METHOD OF PROTECTION.

Figure 2 shows the structural diagram of the momentary protection of the crane, including.

Knots: 1 protection at the maximum moment, 24 four-quadrant roll measurement with roll indicators 25, 26 protection according to the condition of supports with indicators, 61 correct installation of the crane on supports from the transport state.

FORCES: 2, 3, 5, 6, outriggers.

CORNER SENSOR arrows in the plan of the supports 4.

Node 1 instant protection contains: force meters 2, 3, 5, 6; three-input adders 7, 8, 9, 10 of the first group; two-input adders 12, 14, 20 of the second group; quadrators 13, 15; two-input adder of the signals of the quadrators 16; corrector 17; adder of the moment 19; additional adder 18, four-input adder of signals of all load meters 11; comparator of maximum torque 21; indicators: moment 22 and mass of cargo 23.

PRINCIPLE OF OPERATION. The function of the overturning moment, independent of the actual efforts in the supports, is synthesized from the latter as follows: each adder 7, 8, 9, 10 is connected by two inputs with the corresponding load cells 2, 3, 5, 6, and third subtracting inputs with a transfer coefficient of 0.5 with the output of the adder 11. Namely: 7 with 2, 6 and 11; 8 s 3,5 and 11; 9 s 2,3 and 11; 10 s 2,3 and 11. The signals of the sums S ₇ , ..., S ₁₀ from the outputs 46, 47, 48, 50 of the adders of the first group, corresponding to expressions (15), ..., (18), are fed to one input adders 12, 14 of the second group and two inputs of adder 20 in the following order: from 48 through the diode to 14, from 46 through the diode to 12, from 47 and 50 through diodes to 20. The second inputs 12 and 14 are connected to the voltage Fn. The outputs 12 and 14 of the diodes are connected to the input of the quadrator 13, and the output of the 20 diodes is connected to the quadrator 15, the output signals of which correspond to the functions M ² sin ² α and M ² cos ² α are summed 16, the output connected to the input of the corrector 17, the output connected to one the input of the adder of the moment 19, the second subtracting input with a transfer coefficient of 0.5A, associated with the output of the adder 18, one input associated with the output of the adder 11, and the second subtracting input with a constant voltage N *. The output signal 19, corresponding to the overturning moment relative to the rib of minimum crane stability, is supplied to the inputs: the moment indicator 22 and the moment comparator 21, the second input associated with a constant restoring moment, and the moment indicator 22. Output 18 is connected with the cargo mass indicator 23.

Thus, the overturning moment is reduced to one “window”, the size of which is determined by the magnitude of the restoring moment. If the alternating overturning moment of the restoration moment, reduced to a constant value, is exceeded, a comparator is activated, which turns off the drive.

Due to the fact that the moment is a function of the mass of the load and the variable parameters of the boom, the protection is triggered at a single value of the moment, but at different boom departures in accordance with the passport cargo characteristics of the crane.

In figure 3. The structural diagram of the crane protection unit 26 according to the state of the supports is shown. The synthesis of the nominal efforts of the supports is carried out using three-input adders 28, 30, 32, 34 of the third group, two inputs associated with the outputs 46, 47, 48, 50 of the adders of the first group, and the third inputs with the output 49 of the adder 11. Adders with two inputs with a gear ratio 0.5 are associated with the above outputs to the following images: 28 s 46 and 47; 30 s 47 and 48; 32 with 48 and 50, 34 with 46 and 50, and the third subtracting inputs with a transmission coefficient of 0.75 with an output of 49. In the subtractors 29, 31, 33, 35, their synthesized nominal values are subtracted from the outputs of the power meters from the outputs of the adders 28, 30, 32, 34. Coincidence elements 36, 37, 38, 39 are connected to the outputs of the subtractors by one of the inputs and diodes, and by the inputs of the quadrant 40 of the boom position connected to the output of the angle sensor 4 by the other inputs. The outputs of the "And" elements are connected to the corresponding light emitters indicator of the condition of the supports 27 and the control inputs of the keys 41, 42, 43, 44 power meters poles located diagonally opposite to the light emitters installed in the configuration of the supports. The comparator 45 with one input connected to the outputs of the keys, the inputs associated with the power meters, and the other input with a valid voltage. Output 45 is connected to a drive shutdown device.

PRINCIPLE OF OPERATION. The device continuously compares the actual and synthesized nominal functions of the supports. For this, the outputs of the adders 28, 30, 32, 34 are respectively connected to one of the inputs of the subtractors 29, 31, 33, 35, the second inputs of which are connected to the corresponding outputs 52, 51, 54, 53 of the power meters. In this case, the underloaded supports correspond to the difference of the negative sign at the outputs of the subtractors, which, through the diodes, go to one of the inputs of the I elements, the second inputs of which are connected with the quadrant of the position of the boom. Of the two underloaded supports, the “dangerous support" located in the same quadrant with the arrow is selected using logic. In this case, the corresponding element And is triggered and the “dangerous support” indicator “lights up” the output signal, and also turns on the key of the power meter of the support located diagonally opposite to the highlighted support. Through the public key, the signal of the selected load meter is fed to the input of the comparator 45 and compared with its minimum acceptable value at the second input. When the force in the support decreases below the permissible value, it activates 45 and turns off the crane drive with the output signal.

Protection of the crane by the state of the supports is carried out to a minimum of effort in the support diagonally opposite, dangerously underloaded.

In figure 4. The structural diagram of the node 61 for the correct installation of the crane from the transport state to the outriggers is shown.

She contains. Adders 62, 63, 64, 65, connected by one input to the outputs 55, 56, 57, 58 of the subtractor of the actual and nominal forces, the second inputs - with the outputs 74, 73, 72, 71 of the quadrant crank meter 24, and the third inputs through a normally closed key 68 - with reference voltage. The control input of the key is connected to the output of the comparator 70, the inputs associated with the reference voltage and the output 49 of the adder signals of the power meters 11.

Two elements 4 OR NOT 66 and 69 inputs connected to the outputs 55, 56, 57, 58 of the subtractor and 71, 72, 73, 74 of the roll gauge, respectively, and the outputs through the element "And" 67 output 79 - with the indicator light to install the crane on the supports.

PRINCIPLE OF OPERATION. In the initial state, the forces in the supports are zero, therefore, there are no signals at the outputs 55, 56, 57, 58 of the subtracters. Therefore, the control signals for the extension of the hydraulic supports at the outputs 75, 76, 77, 78 are determined by the signals at the outputs of the roll measure 71, 72, 73, 74 and the reference voltage. As the supports extend and their touches with the base, signals appear at the outputs of the respective load cells. Due to the greater sensitivity of the crannometer channels, platform leveling can also occur with incomplete loading of the supports (when touching the crane wheels). When the voltage at the output 49 of the adder 11 reaches a predetermined nominal value, the comparator 70 is activated, the key 68 is turned off and the supply of the reference voltage to the adders 62 ... 65 is stopped. Now, the extension control of the supports is carried out only by negative differential signals of efforts and signals of the roll gauge. With the simultaneous fulfillment of the platform leveling conditions and the nominal distribution of efforts in the supports, the signals at the inputs of the elements 66 and 69 are equal to zero, and their outputs are logical units that, through the And element, “light” the indicator of completion of the crane installation on the supports. During the operation of the crane, the protection system provides information on the distribution of forces in the supports and protects the crane according to their condition.

Sources of information

1. Auth. USSR certificate No. 698903.

2. Patent 2.277.027 (France) publ. 10/04/76.

3. Vinson A.A. Hoisting machines. M: - Engineering, - 1989.

4. Mamaev K.M. On the functional relationships of loads with signals of load meters in crane protection systems. RAS - Bulletin of the Dagestan Scientific Center of the city of Makhachkala, 2000, No. 7, p. 49-57.

Claims (6)

1. A method of protecting the jib crane from tipping, according to which the signals of the force sensors of the outriggers and the angle sensor of the boom in terms of the supports are used and when the protection is triggered, the drives are turned off, characterized in that the protection is carried out to the maximum of the tipping moment relative to the rib of minimum crane stability, which is compared at the same time, in order to determine the module of the tipping moment acting in the plane of the boom, the signals of the force sensors belonging to each a possible tipping edge, subtract from the sums received the signal of the half-sum of the signals of all sensors and extract the signals of the sine and cosine components of the moment from the found differences. 2. The method according to claim 1, characterized in that the protection is additionally carried out by minimizing the actual force in the support diagonally opposite to the dangerously underloaded support, which is compared with the nominal one, while to determine the nominal force of the supports, summarize the signals of the results of summing the signals of the force sensors belonging to each tipping rib, and by subtracting the last of the signals from the force sensors, an underloaded support is detected. 3. The method according to claim 1, characterized in that for the installation of the crane from the transport position on the supports in compliance with the horizontal conditions of the crane platform and the nominal distribution of forces in the supports, the differences of the signals of the actual and nominal forces in the supports are used together with the signals of the quadrant cranometer. 4. A device for protecting the jib crane from tipping over, containing the force sensors of the outriggers made in the form of force meters of supports, adders, a comparator, characterized in that the force meters of the supports forming the side of the support contour are connected to two inputs of the corresponding from the adders of the first group, the third inputs of which connected to the output of the adder connected to all load meters, the outputs of one pair of adders of the first group through diodes are connected to one of the inputs of the first and second adders of the second group, the outputs of another pair The adders of the first group are connected through diodes to two inputs of the third adder of the second group, the outputs of the first and second adders of the second group are connected through diodes to the input of the first quadrator, and the output of the third adder through a diode is connected to the input of the second quadrator, the outputs of the quadrators through the adder of the quadrator signals are connected to by the corrector, the output of the corrector is connected to one input of the moment adder, another input through an additional adder associated with the output of the adder of the signals of all load meters, the output of the moment adder indicator input torque and to one input of a comparator, the other input of which is intended for sensing DC signal restoring moment, the other inputs of the adders of the second group are connected with respective reference voltage sources. 5. The device according to claim 4, characterized in that the first and fourth adders of the first group are connected to the first, second and fourth to the second, second and third to the third, the first and third to the fourth adder of the third group, the third inputs of the adders of the third groups are associated with the output of the adder of all force meters; the outputs of the power meters and adders of the third group are paired with the inputs of the corresponding subtractors, the outputs through the diodes associated with one input of the matching elements, the other inputs of the matching elements are connected with the corresponding outputs of the quadrant of the position of the boom, the input connected to the angle sensor in terms of supports, and the outputs are with light emitters of the indicator the state of the supports and the control inputs of the keys of the power meters located in the configuration of the supports diametrically opposite to the corresponding light emitters of the supports, s key associated with one of the inputs of the comparator state poles, a second input associated with a corresponding reference voltage, and output a drive control device. 6. The device according to claim 5, characterized in that it is equipped with a roll gauge, two elements 4 OR NOT and a fourth group of adders connected by the first inputs to the outputs of the subtractors, the second inputs - with the outputs of the roll measure, and the third inputs through a normally closed key - with the corresponding source of the reference voltage, the control input of the key is connected to the output of the additional comparator, connected by the inputs to the output of the adder of the signals of all load meters and with the same source of the reference voltage, the inputs of the first and second elements 4 OR NOT connected are connected with the inputs of the adders of the fourth group and the outputs of the roll gauge, respectively, and the outputs are with an additional matching circuit, the output of which is connected to the light indicator of the crane installation on the supports.

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