CN115784012A - Method for stably hoisting whole tower crane through asymmetric fixed-distance double-hook tower crane - Google Patents
Method for stably hoisting whole tower crane through asymmetric fixed-distance double-hook tower crane Download PDFInfo
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Abstract
The invention discloses a method for stably lifting a whole arrow of an asymmetric distance double-hook tower crane, which comprises the steps of firstly establishing a mechanical model of the stable lifting state of the whole arrow of the asymmetric distance double-hook tower crane; analyzing the mechanical model, establishing an equation set in a lifting balance state, solving the equation set, and determining the initial lifting position according to the calculation result; obtaining a condition and an implementation method capable of stably hoisting. The invention relates to a method for stably hoisting an entire rocket by using an asymmetric distance double-hook tower crane, which takes carrier rocket hoisting as an application background. The method considers the influence of the asymmetric state of the fixed-distance double-hook tower crane on the lifting stability, and provides a method for determining the tension proportional relation of the double hooks for stable lifting and the initial position of a lifted product by establishing a mechanical model of the whole lifting system; the method can realize the stable hoisting of the asymmetric fixed-distance double-hook tower crane and is verified by tests; the method can be compatible with the symmetrical state of the tower crane, and is also suitable for hoisting other slender members.
Description
Technical Field
The invention relates to a stable hoisting method of an asymmetric distance double-hook tower crane, in particular to a stable hoisting method of an asymmetric distance double-hook tower crane taking carrier rocket hoisting as an application background, and belongs to the field of machinery.
Background
The hoisting of the carrier rocket is an important work in the rocket test launching process, and the rocket is hoisted to a tower launching platform from a horizontal transport vehicle by using a tower crane. The method mainly comprises the following steps: horizontal lifting, turning and erecting and product butt joint. In engineering construction and aerospace tests, large-scale components are hoisted by three methods, namely double-crane hoisting, distance-adjustable double-hook hoisting and distance-fixed double-hook hoisting, according to rocket hoisting characteristics and requirements, a distance-fixed double-hook method is generally adopted in current launching sites, when a single-vehicle distance-fixed double-hook method is adopted for hoisting, double hooks incline along the front and rear hoisting point directions of a hoisted piece to form a certain angle, and horizontal hoisting is realized by continuously adjusting the mass center. Because two lifting hooks and the hoisted product are not in a vertical state, external force in the horizontal direction can be generated, and then the phenomenon of shaking occurs in the horizontal hoisting process, the horizontal shaking is a serious potential safety hazard of rocket hoisting, and the horizontal hoisting stage is the most critical step. In order to ensure stable hoisting, the initial position of the tower crane must be correctly selected before horizontal hoisting, and the tension and the proportional relation of the main hoisting mechanism and the auxiliary hoisting mechanism must be correctly configured.
The launching field hoisting work is carried out according to corresponding operation regulations, and the method adopted by the operation regulations is consistent with the method in Chinese patent CN106185598A (a method for stably hoisting a whole arrow at a fixed distance by double hooks). According to the operation rule strictly, in the process of hoisting a certain rocket at a certain station, obvious displacement and shaking occur at the moment of horizontal hoisting of the rocket body. Aiming at the problems in the method, the invention analyzes the reason of shaking, considers the influence of the asymmetric lifting hook on the lifting balance condition, and provides the stable lifting method of the asymmetric fixed-distance double-hook tower crane.
Disclosure of Invention
The invention aims to provide a stable hoisting method of an asymmetric fixed-distance double-hook tower crane, which considers the influence of asymmetric factors of the fixed-distance double-hook tower crane, establishes a complete mechanical model containing the state of a tower crane hook, obtains stable hoisting conditions and a specific implementation method, and is verified in a test.
The invention aims to solve the problem of shaking in the horizontal hoisting process, a basic mechanical model needs to be established when the hoisting moment is in a balanced state, the model considers the influence of all hoisting components such as a lifting hook and a lifting appliance and the relative position relation of the components on the hoisting balanced state, then the model is solved to obtain the initial position relation between a hoisted product and a tower crane and a tension setting method of double hooks, and the problem of hoisting shaking can be eliminated by hoisting according to the condition.
The tower crane has the core characteristics that the asymmetry of the tower crane is considered, the tower crane has better practicability, and the problem of horizontal shaking in hoisting practice can be completely solved. It should be noted that the method disclosed by the invention is compatible with the conditions of symmetry of the tower crane and negligible self weight of the lifting hook, and compared with the prior art, the method is mainly different in the determination link of the hoisting point position, has an accurate proportional relation and a definite reference value in the tension relation in the erecting process, and avoids the problem of shaking caused by accidental sliding or too large deviation of the tension value due to blind adjustment.
The invention provides a method for stably hoisting an entire asymmetric fixed-distance double-hook tower crane arrow, which comprises the following specific implementation steps:
s1: calculating to obtain an initial balance condition of horizontal lifting, obtaining the position relation between the main lifting hook and the auxiliary lifting hook and the rocket, and solving the double-hook initial tension (and proportional relation) during stable lifting;
s2: marking the projection position of the midpoint of the main and auxiliary lifting hooks on the lifting line and the projection position of the rocket center of mass on the lifting line obtained in the step S1 on the terrace, and parking the rocket body to a preset position;
s3: and (4) increasing the tension according to a preset proportional relation, and linking the main lifting hook with the auxiliary lifting hook to lift the arrow body.
The method for determining the balance condition in the step S1 comprises the following three steps:
s11: and establishing a basic mechanical model when the horizontal hoisting is in a balanced state at the moment without considering the influence of a lifting hook, a lifting appliance and the like. The specific process is as follows:
a hoisting product is used as a research object, the self weight of the lifting hook and the lifting appliance is ignored, and a basic mechanical model can be established.
The stress model of the hoisted product is shown in figure 1. The distance between the double hooks of the tower crane is fixed, and the distance is L 0 The self gravity of the hoisted product is G 0 The distance between the hoisting points is S 0 The distance between the mass center and the left suspension point is S 1 The distance between the mass center and the right lifting point is S 2 Main lifting rope tension F 1 Tension F of auxiliary lifting rope 2 The main lifting hook and the auxiliary lifting hook can horizontally move along a crane arm of the tower crane by controlling the single vehicle, so that the angles and the lengths of the main lifting rope and the auxiliary lifting rope are changed. If the hoisted product is expected to have no movement in the horizontal direction at the moment of leaving the ground, that is, the resultant force of external force applied to the hoisted product in the horizontal direction is zero, the following should be:
F 1 cosα＝F 2 cosβ ①
meanwhile, the left and right hoisting points of the hoisted product are ensured not to rotate when being hoisted, and then:
F 1 S 0 sinα＝G 0 S 2 ②
F 2 S 0 sinβ＝G 0 S 1 ③
if the hoisting is finished, the hoisted product generates upward displacement. Still need satisfy the pulling force that acts on the vertical direction of hoist and mount product and be greater than its self gravity, promptly:
F 1 sinα+F 2 sinβ≥G 0 ④
and (3) combining the constraint relations to obtain an equation set which is required to be met when the horizontal hoisting process is in a balanced state:
in the equation system, the formula (1) is substituted by the formula (2)/(3) to obtain:
S 1 /S 2 ＝tanβ/tanα ⑤
in fig. 1, the lengths of two sides of the triangle are a and b, respectively, and the height of the lifting arm from the lifted product is h, then according to the equation (1) and the corresponding relationship between the angle and the side length in the triangle, the tension relationship between the two lifting hooks can be obtained as follows:
according to the relation between the two angles determined by the formula (5), the positions and the angles of the two lifting hooks of the fixed-distance double-hook tower crane are uniquely determined when the tower crane is stably lifted, and the fixed distance L0 of the double hooks is determined according to S 1 /S 2 The proportion is divided into two sections, and the dividing point and the mass center of the hoisted product are on the same plumb line. Theoretically, the hoisting product can be stably hoisted by hoisting under the proportional relation of the initial position described by the formula (5) and the force described by the formula (6), and the hoisting product cannot shake or rotate.
And when the angle of the steel wire rope and the proportional relation of the two pulling forces are determined, the minimum value of the hoisting balance states F1 and F2 can be obtained according to the formula (4).
S12: and considering and quantifying the influence of lifting members such as a lifting hook, a lifting appliance and the like and the position relation thereof on the balance state at the moment of lifting, and correcting the initial position relation. The specific principle, modeling and solving method are as follows:
in practical experiment work, when the product is horizontally lifted according to the initial position obtained in the step S11, the product is displaced and shaken along the axial direction in the horizontal direction, which means that more factors must be considered. In engineering practice, the self-weight constant of the lifting hook is measured by tons, the main lifting hook and the auxiliary lifting hook are different in mass and asymmetric in position relation, the mass of the lifting hook is not greatly different from that of a lifted product or even in the same order of magnitude, influence is not negligible under the condition, qualitative judgment can be firstly obtained through the stress relation, namely the self weights of the lifting hook, a steel wire rope and a lifting appliance directly influence the tension on a lifting rope, so that the magnitude of components in the horizontal direction is influenced, and the mass of the component and the position distribution relation of the component are obviously not negligible.
Therefore, the whole body formed by the hoisting product and all hoisting members is taken as a research object, a new mechanical balance equation set is established under the condition of considering the self-weight and the position relation of the hoisting members, and the new balance point position relation considering the influence of the members such as the lifting hook and the like can be obtained by solving the equation set. According to the analysis for determining the initial position of the tower crane, the problem can be described by another clearer and more intuitive method: under the state of stable hoisting, the perpendicular line of the triangle peak formed by the two lifting ropes (extension lines) and the hoisted product is supposed to fall on the mass center of the hoisted product. As long as the centroid position is found, the initial positions of the two lifting hooks of the tower crane are uniquely determined.
Under the stable hoisting state, the integral shape of the lifting rope, the lifting hook, the lifting appliance and the hoisted product is kept unchanged from the shape before hoisting. In the plane, there is no horizontal swing and no vertical rotation, so the lifting rope, the lifting hook, the lifting appliance and the lifting product can be considered as a combined rigid body, and for convenience of description, the rigid body is named as a lifting combined body. The above formulas (1), (2), (3) and (4) are also applicable to the hoisting assembly. Furthermore, as long as the position of the center of mass of the hoisting assembly in the horizontal direction is obtained, the positional relationship between the rocket and the hook can be determined accordingly. (the height of the mass center in the vertical direction does not influence the angle and the position of the tower crane, so that the change of the mass center in the vertical direction does not need to be discussed.)
The mass distribution of the hoisting assembly is shown in figure 2. Wherein the quality of the hoisted product is M 0 The mass center of the hoisting assembly is at the point P, and the plumb line passing through the mass center of the hoisting assembly is handed to the point P' with the hoisting product. Wherein the main lifting hook mass M 1 Mass M of auxiliary hook 2 Mass M of main wire rope 3 Mass M of auxiliary wire rope 4 Mass M of main spreader 5 Mass M of auxiliary sling 6 The distance from a projection point P' of the center of mass of the hoisting assembly on the central axis of the product to the left hoisting point is S 1 ' from right hanging point S 2 '. The distance between the lifting hooks of the tower crane is L 0 Hoisting cantilever distance of tower craneThe distance of the products is h. If the point P' of the intersection point of the plumb line passing through the center of mass of the whole hoisting assembly and the central axis of the product is the origin of the abscissa axis, the central axis of the product is the x axis, only the direction of the x axis is considered, and the formula should be calculated according to the center of mass:
wherein x is 1 And x 2 And m is mass and is a dependent variable of x, the mass at a corresponding infinitesimal dx with the abscissa as x is dm, and the corresponding linear density is rho, so that dm = rho dx.
For ease of calculation, the components of the study may be discretized. If the hoisting assembly is divided into a left part and a right part by the plumb line passing through the P' point, which corresponds to 4,M in the figure i (i =1,2,3,4,5,6) is the mass of a member of the hoisted assembly, N i To correspond to mass M i The distance from the centroid of the member to the Y-axis is then:
M 1 ×N 1 +M 3 ×N 3 +M 5 ×N 5 ＝M 2 ×N 2 +M 4 ×N 4 +M 6 ×N 6 +M 0 ×(S 1 -S 1 ′) ⑧
according to the corresponding relation between the variables in the graph, the variable S can be composed of only one variable S 1 The algebraic expression of' means. Equation (8) has only one unknown S 1 ', the equation can be solved. After the value of S1' is obtained, a new centroid position under the influence of the asymmetry of the lifting hook can be obtained. In engineering practice, for convenience of operation, a projection point of a centre of mass point P of a hoisting product on a hoisting line and a middle point of a double-hook distance are reference points of relative positions, and then the distance between the two points is as follows:
ΔL＝S 1 -S 1 ′+L 0 S 1 ′/S 0 -L 0 /2 ⑨
it should be noted that Δ L may be a negative value, and when the value is a negative value, the physical meaning corresponds to moving to the left in fig. 4.
S13: and determining related parameters such as the mass and the length of the hoisting member required in the equation solving calculation process, substituting the known parameters into formulas (8) and (9) for manual solving, and finally obtaining the relative position relation between the hoisting product and the double hooks of the tower crane by taking the Delta L as a result. Or inputting the data into special calculation software for calculation and solving (an asymmetric fixed-distance double-hook tower crane certificate stable hoisting calculation software developed by the project team, which has applied for the copyright of computer software), the position relation between the rocket center of mass and the midpoint of the main and auxiliary lifting hooks can be obtained.
After considering the mass of each component of the hoisting system and calculating the S1', the specific value of the double-hook tension when the hoisting system is just stably hoisted can be calculated, and the calculation method comprises the following steps:
wherein the content of the first and second substances,
the distance from the projection point of the center of mass of the hoisting assembly on the central axis of the product to the left hoisting point is S 1 ' from right hanging point S 2 ', g is the acceleration of gravity.
Further, the method for determining the relative position of the rocket and the hook in the step S2 comprises the following steps:
s21: marking a ground hoisting line on the terrace, marking the projection point of the middle point of the distance between the main and auxiliary lifting hooks in the no-load state on the hoisting line, and enabling the distance between the projection point O' of the rocket center of mass on the hoisting line and the projection point to be delta L.
S22: furthermore, for convenient operation, according to the width of the transfer vehicle, the contour line (backing line) of the outer edge of the single-side tire of the transfer vehicle is marked on the terrace, the transfer vehicle is controlled according to the backing line, so that the hoisting line is parallel to the axial center line of the rocket, and the projection of the central axis on the ground is superposed with the hoisting line;
s23: and adjusting the position of the transfer trolley to ensure that the central axis of the rocket is right below the connecting line of the main hook and the auxiliary hook, and the projection point of the rocket centroid P on the hoisting line is coincided with the point O'.
Further, the method for lifting the main and auxiliary lifting hooks in the step S3 comprises the following steps:
s31: hanging a lifting appliance, tensioning the lifting appliance (the tension is controlled to be about 1/5 of the total load), and confirming the initial lifting state (if the position of the transport vehicle is stopped with left and right deviation, the rotation angle adjustment is needed, and the front and back deviation exists, and the front and back position adjustment of amplitude variation is needed);
s31: adjusting the initial tension of the main and auxiliary lifting hooks according to the proportional relation according to the result of the model solution, and observing the lifting state by a lifting operator when the actual tension value is close to the solution result (before reaching 90% of the solution tension value of the lifted product), and connecting a supporting arrow body;
s32: the main hook and the auxiliary hook are linked until the arrow body is 50cm away from the support, and then the arrow body stops, and the fixed pin for connecting the transport vehicle and the arrow body is removed;
s33: the main hook and the auxiliary hook are linked, the product is lifted to a height of about 3m from the ground (the product can be removed from the transport vehicle), and the transport vehicle is removed from the hoisting area;
s34: the main hook and the auxiliary hook are linked to turn over and erect the product.
The invention has the beneficial effects that:
(1) During the rocket lifting process, if the rocket is greatly shaken, the lifted products are likely to collide with the tower and slide and rub with the transfer trolley to cause the damage of the rocket body, so that direct economic loss is generated and the launching period is delayed, and in addition, sudden shaking in the direction which is difficult to predict can also cause the injury of lifting auxiliary personnel; the invention can analyze and clear the shaking reason, adopts an effective method to solve the shaking reason, and can greatly improve the safety and reliability of hoisting.
(2) The method can well serve the space flight test task, can be popularized to hoisting of similar slender components, and has good portability and popularization value.
Drawings
FIG. 1 is an ideal mechanical model diagram neglecting the self weight of the hook;
FIG. 2 is a mass distribution diagram of a hoisting assembly considering the influence of a lifting hook;
FIG. 3 is a diagram showing the relationship between the position of a hoisted product and the position of a double hook;
fig. 4 is a schematic diagram of the composition and parameters of the hoisting assembly in the embodiment.
Detailed Description
The present invention is further illustrated by, but is not limited to, the following examples.
In this embodiment, a sub-level hoisting of a certain type of rocket is taken as an example, and the specific implementation manner is as follows:
s1: calculating to obtain an initial balance condition of horizontal lifting, and obtaining the position relation between the main lifting hook and the auxiliary lifting hook and the rocket;
s11: and establishing a basic mechanical model when the horizontal hoisting moment is in a balanced state without considering the influence of a lifting hook, a lifting appliance and the like. The specific process is as follows:
a hoisting product is taken as a research object, the self weight of a lifting hook and a lifting appliance is ignored, and a basic mechanical model can be established as shown in figure 1:
the stress model of the hoisted product is shown in figure 1. The distance between the double hooks of the tower crane is fixed, and the distance is L 0 The self gravity of the hoisted product is G 0 The distance between the hanging points is S 0 The distance between the mass center and the left suspension point is S 1 The distance between the mass center and the right lifting point is S 2 The mechanical model aims at finding the suitable initial positions of the main lifting hook and the auxiliary lifting hook relative to a hoisted product and ensuring that the hoisted product is not shaken instantly. If the hoisted product is expected to have no movement in the horizontal direction at the moment of leaving the ground, that is, the resultant force of external force applied to the hoisted product in the horizontal direction is zero, the following should be:
F 1 cosα＝F 2 cosβ ①
meanwhile, the left and right hoisting points of the hoisted product are ensured not to rotate when being hoisted, and then:
F 1 S 0 sinα＝G 0 S 2 ②
F 2 S 0 sinβ＝G 0 S 1 ③
if the hoisting is finished, the hoisted product generates upward displacement. Still need satisfy the pulling force that acts on the vertical direction of hoist and mount product and be greater than its self gravity, promptly:
F 1 sinα+F 2 sinβ≥G 0 ④
and (3) combining the constraint relations to obtain an equation set which is required to be met when the horizontal hoisting process is in a balanced state:
in the equation system, the formula (1) is substituted by the formula (2)/(3) to obtain:
in fig. 1, the lengths of two sides of the triangle are a and b, respectively, and the height of the lifting arm from the lifted product is h, then according to the equation (1) and the corresponding relationship between the angle and the side length in the triangle, the tension relationship between the two lifting hooks can be obtained as follows:
according to the relation between the two angles determined by the formula (5), the positions and the angles of the two lifting hooks of the fixed-distance double-hook tower crane are uniquely determined during stable hoisting, and the fixed distance L of the double hooks is determined 0 According to S 1 /S 2 The proportion is divided into two sections, and the dividing point and the mass center of the hoisted product are on the same plumb line. Theoretically, the hoisting product can be stably hoisted by hoisting under the proportional relation of the initial position described by the formula (5) and the force described by the formula (6), and the hoisting product cannot shake or rotate.
And when the angle of the steel wire rope and the proportional relation of the two pulling forces are determined, the minimum value of the hoisting balance states F1 and F2 can be obtained according to the formula (4).
S12: and considering and quantifying the influence of lifting members such as a lifting hook, a lifting appliance and the like and the position relation thereof on the balance state at the moment of lifting, and correcting the initial position relation. The specific principle, modeling and solving method are as follows:
in practical experiment work, when the product is horizontally lifted according to the initial position obtained in the step S11, the product is displaced and shaken along the axial direction in the horizontal direction, which means that more factors must be considered. In engineering practice, the self weight constant of the lifting hook is measured by ton, the main lifting hook and the auxiliary lifting hook have different masses and asymmetric position relations, the mass of the lifting hook is different from that of a lifted product and even in the same order of magnitude, the self weights of the lifting hook, a steel wire rope and a lifting appliance directly influence the tension on a lifting rope, and therefore the magnitude of the component in the horizontal direction is influenced, and the mass of the component and the position distribution relation of the component cannot be ignored obviously.
Therefore, the whole body formed by the hoisting product and all hoisting members is taken as a research object, a new mechanical balance equation set is established under the condition of considering the self-weight and the position relation of the hoisting members, and the new balance point position relation considering the influence of the members such as the lifting hook and the like can be obtained by solving the equation set. According to the analysis for determining the initial position of the tower crane, the problem can be described by another clearer and more intuitive method: under the state of stable hoisting, the perpendicular line of the triangle peak formed by the two lifting ropes (extension lines) and the hoisted product is supposed to fall on the mass center of the hoisted product. As long as the centroid position is found, the initial positions of the two lifting hooks of the tower crane are uniquely determined.
Under the stable hoisting state, the integral shape of the lifting rope, the lifting hook, the lifting appliance and the hoisted product is kept unchanged from the shape before hoisting. In the plane, there is no horizontal swing and no vertical rotation, so the lifting rope, the lifting hook, the lifting appliance and the lifting product can be considered as a combined rigid body, and for convenience of description, the rigid body is named as a lifting combined body. The above formulas (1), (2), (3) and (4) are also applicable to the hoisting assembly. Furthermore, as long as the position of the center of mass of the hoisting assembly in the horizontal direction is obtained, the positional relationship between the rocket and the hook can be determined accordingly. (the height of the mass center in the vertical direction does not influence the angle and the position of the tower crane, so that the change of the mass center in the vertical direction does not need to be discussed.)
Hoisting combined physiqueThe amount distribution is shown in FIG. 2. Wherein the quality of the hoisted product is M 0 The mass center of the hoisting assembly is at the point P, and the plumb line passing through the mass center of the hoisting assembly is handed to the point P. Wherein the main lifting hook mass M 1 Mass M of auxiliary hook 2 Mass M of main wire rope 3 Mass M of auxiliary wire rope 4 Mass M of main spreader 5 Mass M of auxiliary sling 6 The distance from the center of mass of the hoisting assembly to the left hoisting point on the projection point P on the X axis is S 1 ' from right hanging point S 2 '. The distance between the lifting hooks of the tower crane is L 0 The distance between the cantilever of the tower crane and the hoisted product is h. If the point P of the intersection point of the plumb line passing through the center of mass of the whole hoisting assembly and the product is the origin of the abscissa axis, only the direction of the x axis is considered, and the formula should be calculated according to the center of mass:
wherein, X 1 And X 2 And m is mass and is a dependent variable of X for the end point of the projection of the hoisting assembly on the X axis, the mass at a corresponding infinitesimal dx with the abscissa as X is dm, and the corresponding linear density is rho, and then dm = rho dx.
For ease of calculation, the components of the study may be discretized. If the hoisting assembly is divided into a left part and a right part by a plumb line passing through the P grinding point, the drawing 4,M corresponds to i (i =1,2,3,4,5,6) is the mass of a member of the hoisted assembly, N i To correspond to mass M i The distance from the centroid of the member to the Y-axis is then:
M 1 ×N 1 +M 3 ×N 3 +M 5 ×N 5 ＝M 2 ×N 2 +M 4 ×N 4 +M 6 ×N 6 +M 0 ×(S 1 -S 1 ′) ⑧
according to the corresponding relation between the variables in the graph, the variable S can be composed of only one variable S 1 The algebraic expression of' is given. Equation (8) has only one unknown S 1 ', the equation is solvable. To obtain S 1 After the value is obtained, the influence of the asymmetry of the lifting hook can be consideredThe new centroid position is entered. In engineering practice, for convenience of operation, a projection point of a centre of mass point P of a hoisting product on a hoisting line and a middle point of a double-hook distance are reference points of relative positions, and then the distance between the two points is as follows:
ΔL＝S 1 -S 1 ′+L 0 S 1 ′/S 0 -L 0 /2 ⑨
s13: and determining related parameters such as the mass and the length of the hoisting member required in the equation solving calculation process, substituting the known parameters into formulas (8) and (9) for manual solving, and finally obtaining the relative position relation between the hoisting product and the double hooks of the tower crane by taking the Delta L as a result. Or inputting the data into special calculation software for calculation and solving (a calculation software for the stable hoisting of the asymmetric fixed-distance double-hook tower crane certificate developed by the project team, which has applied for the copyright of computer software), the position relation between the rocket center of mass and the midpoint of the main and auxiliary lifting hooks can be obtained.
After considering the mass of each component of the hoisting system and calculating the S1', the specific value of the double-hook tension when the hoisting system is just stably hoisted can be calculated, and the calculation method comprises the following steps:
wherein the content of the first and second substances,
the distance from the projection point of the center of mass of the hoisting assembly on the central axis of the product to the left hoisting point is S1', the distance from the projection point to the right hoisting point is S2', and g is the gravity acceleration.
Corresponding to the method in the step S1, a mechanical model in a horizontal hoisting instant equilibrium state is established, and a corresponding equation set is solved, wherein the composition and parameters of the hoisting assembly in the embodiment are shown in fig. 4. Wherein the x-axis is a central axis of the rocket, and the y-axis is a plumb line in which the center of mass of the hoisting assembly is located. The known input parameter definitions and values referred to therein are shown in table 1:
known input parameters in the example of Table 1
The definitions and expressions of the intermediate parameter physical quantities involved in the calculation process are shown in table 2.
Table 2 process parameters in the calculation of hoisting examples
Substituting the parameters in Table 1 and Table 2 into equation (9), solving the equation to obtain S 1 ' further, the following values were obtained:
ΔL＝S 1 -S 1 ′+L 0 S 1 ′/S 0 -L 0 /2＝0.72(m)
according to equation r, we find:
F 1 /F 2 ＝cosβ/cosα＝1.323
the specific value of the tension when the crane is just stably lifted is that the tension values of the main and auxiliary lifting hooks are respectively:
F 1 ＝92180(N)
F 2 ＝69660(N)
(the relationship between the tension and the tension ratio is the actual tension of the lifting rope at the top end.)
S2: marking the projection point of the midpoint of the main and auxiliary lifting hooks on the lifting line on the terrace, marking the projection point of the rocket mass center on the lifting line, and parking the rocket body to a preset position:
s21: marking a ground hoisting line on the terrace, marking a projection point O of the middle point of the main and auxiliary lifting hooks on the hoisting line, and marking an O' point with the distance of 0.72m from the O point on the hoisting line.
S22: furthermore, for convenient operation, according to the width of the transfer vehicle, the contour line (backing line) of the outer edge of the single-side tire of the transfer vehicle is marked on the terrace, the transfer vehicle is controlled according to the backing line, so that the hoisting line is parallel to the axial center line of the rocket, and the projection of the central axis on the ground is superposed with the hoisting line;
s23: and adjusting the position of the transfer trolley to ensure that the central axis of the rocket is right below the connecting line of the main hook and the auxiliary hook, and the projection point of the rocket centroid P on the hoisting line is coincided with the point O'.
S3: increasing the tension according to a preset proportional relation, and linking the main lifting hook with the auxiliary lifting hook to lift the arrow body:
s31: hanging a lifting appliance, tensioning the lifting appliance (the tension of the tensioning lifting appliance is about one fifth of the instant tension just balanced in lifting, namely the tension of a main hook is about 18436N, the tension of an auxiliary hook is about 13932N, and the tension is properly adjusted according to the tightness observed on site), and confirming the initial lifting state (if the position of a transport vehicle is stopped with left and right deviation, the rotation angle adjustment is needed, the front and back deviation exists, and the front and back position adjustment of amplitude variation is needed);
s31: according to the result of the model solution, gradually increasing the tension of the main and auxiliary lifting hooks according to a proportional relation, and when the actual tension value is close to the solution result (the tension is about nine tenths of the magnitude of the instantaneous tension just balanced for lifting, namely the tension of the main hook is lower than 82962N, and the tension of the auxiliary hook is lower than 62694N), observing the lifting state by a lifting operator, and connecting a supporting arrow body;
s32: the main hook and the auxiliary hook are linked until the arrow body is 50cm away from the support, and then the arrow body stops, and the fixed pin for connecting the transport vehicle and the arrow body is removed;
s33: the main hook and the auxiliary hook are linked, the product is lifted to a height of about 3m from the ground (the product can be removed from the transport vehicle), and the transport vehicle is removed from the hoisting area;
s34: the main hook and the auxiliary hook are linked to turn over and erect the product.
In this embodiment, the erecting process is stable without shaking. In addition, in order to further check the accuracy of the calculation result in engineering practice, after the lifting is stable, when the product is lifted by 50cm away from the support, the distance between the projection point of the center of mass of the product on the lifting line and the projection point of the middle point of the double-hook distance on the lifting line is measured, and the error between the distance and the calculation result is within 3 cm; the distance is measured again in the process of descending the rocket in the reverse process of the rocket, and good consistency is achieved.
Claims (5)
1. A method for stably hoisting a whole tower crane by using an asymmetric fixed-distance double-hook tower crane is characterized by comprising the following steps:
s1: calculating to obtain an initial balance condition of horizontal lifting, obtaining the position relation between the main lifting hook and the auxiliary lifting hook and a lifted product, and solving the initial tension and proportion relation of double hooks during stable lifting;
the hoisting product, a lifting hook, a lifting appliance and other components are regarded as a combined rigid body, the position of the mass center of the rigid body is obtained, the position relation between the hoisting product and the double hooks of the tower crane, which is considered to be influenced by the asymmetry of the lifting hook of the fixed-distance double-hook tower crane, is further obtained according to the formula, the proportional relation and the magnitude of the tension of the double hooks during stable hoisting are obtained, the magnitude of the tension of the double hooks can be adjusted in real time during the hoisting process, and the swinging caused by improper tension configuration can not occur during the hoisting process;
s2: marking the projection position of the midpoint of the main and auxiliary lifting hooks on the lifting line and the projection position of the center of mass of the lifted product obtained in the step S1 on the lifting line on the terrace, and parking the arrow body to a preset position;
s3: and increasing the tension according to a preset proportional relation, and linking the main lifting hook with the auxiliary lifting hook to lift the arrow body.
2. The method for stably hoisting the whole asymmetric distance double-hook tower crane according to claim 1, characterized in that: the method for determining the equilibrium condition in the step S1 comprises the following three steps:
s11: under the condition of not considering the influence of hoisting members such as a lifting hook, a lifting appliance and the like, a basic mechanical model when the horizontal hoisting is in a balanced state at the moment is established and solved to obtain two conclusions:
firstly, the hoisting product and position condition when the fixed-distance double-hook tower crane is stably hoisted is the fixed distance L of the double hooks 0 According to S 1 /S 2 The proportion is divided into two sections, and the dividing point and the mass center of the hoisted product are on the same plumb line; the conclusion is the theoretical support of the calculation of the initial position of the stable hoisting;
secondly, the proportion relation of the double-hook tension during stable hoisting is as follows:
wherein, the distance between the double hooks of the tower crane is fixed, and the distance is L 0 The distance between two hoisting points of the hoisted product is S 0 The product is at the center of mass at the left hanging point S 1 Distance S from right hanging point 2 Main lifting rope tension F 1 Tension F of auxiliary lifting rope 2 The height of the lifting arm from a lifted product is h, and alpha and beta are respectively included angles formed by the stress directions of the main lifting hook and the auxiliary lifting hook and a straight line where the lifted product is located;
s12: considering and quantifying the influence of the hoisting component and the position relation thereof on the hoisting instant balance state, and correcting the initial position relation:
the correction method is characterized by comprising the following two points:
firstly, the influence of the asymmetry of a lifting hook and a lifting appliance on lifting balance is considered, and a method for determining the initial position during stable lifting after the influence is considered is obtained, wherein the calculation method comprises the following steps:
each component of the hoisting system and a hoisting product are regarded as rigid bodies, namely a hoisting assembly, and each component is discretized; taking a plumb line passing through a point P 'as a Y axis, dividing the hoisting assembly into a left part and a right part, wherein Mi (i =1,2,3,4,5,6) is the mass of a certain member of the hoisting assembly, and Ni is the distance from the center of mass of the member with the corresponding mass Mi to the Y axis, wherein the distance from a projection point of the center of mass of the S1' hoisting assembly on the central axis of the product to a left hoisting point can be obtained according to the conclusion obtained by S11:
M 1 ×N 1 +M 3 ×N 3 +M 5 ×N 5 ＝M 2 ×N 2 +M 4 ×N 4 +M 6 ×N 6 +M 0 ×(S 1 -S 1 ′)
the equation has only one unknown number S1', and the equation can be solved; after the value of S1' is obtained, the position of the mass center of the hoisting assembly can be obtained; in order to facilitate operation in engineering practice, a projection point O' point of a centre of mass point P of a hoisted product on a hoisting line and a projection point O point of a middle point of a double-hook distance on the hoisting line are used as reference points of relative positions of the hoisted product and the double hooks, and the distance calculation method comprises the following steps:
ΔL＝S 1 -S 1 ′+L 0 S 1 ′/S 0 -L 0 /2
secondly, after considering the mass of each component of the hoisting system and calculating the S1' value, the specific magnitude of the double-hook tension when the hoisting is just stable can be calculated, and the calculation method comprises the following steps:
wherein the content of the first and second substances,
the distance from the projection point of the center of mass of the hoisting assembly on the central axis of the product to the left hoisting point is S 1 ' from right hanging point S 2 ', g is the acceleration of gravity.
S13: determining related parameters such as the quality and the length of a hoisting member required in the equation solving calculation process, and substituting the known parameters into the solving process to obtain a relative position relation between a hoisting product and double hooks of a tower crane with the Delta L as a result;
the step is characterized in that: the influence of the mass distribution of each component of the hoisting system on the hoisting balance is completely considered, and the hoisting balance can be clearly quantized.
3. The method for stably hoisting the whole asymmetric distance double-hook tower crane arrow according to claim 1, is characterized in that: the method for determining the relative position of the hoisted product and the lifting hook in the step S2 comprises the following steps:
s21: marking a ground hoisting line on the terrace, marking a projection point O of the middle point of the distance between the main and auxiliary lifting hooks in the no-load state on the hoisting line, and marking a point with a distance delta L from the point O on the hoisting line as an O' point;
s22: according to the width of the transfer vehicle, marking a contour line (a backing line) of the outer edge of a single-side tire of the transfer vehicle on a terrace, and controlling the transfer vehicle according to the backing line to enable the hoisting line to be parallel to the axial center line of a hoisted product, and enabling the projection of the central axis on the ground to be superposed with the hoisting line;
s23: adjusting the position of the transfer trolley to enable the central axis of the hoisted product to be right above the hoisting line, and enabling the projection point of the barycenter P of the hoisted product on the hoisting line to be superposed with the point O';
step S2 is characterized in that: a specific implementation method for the stable hoisting initial position is provided, and the method considers the influence of the mass distribution condition of each component of the hoisting system on the hoisting balance.
4. The method for stably hoisting the whole asymmetric distance double-hook tower crane arrow according to claim 1, is characterized in that: the method for lifting the main and auxiliary lifting hooks in the step S3 comprises the following steps:
s31: hanging a lifting appliance, tensioning the lifting appliance, controlling the tension to be about 1/5 of the total load, and confirming the initial lifting state; if the position of the transport vehicle is stopped with left and right deviation, the rotation angle needs to be adjusted. The front and the back have deviation, and the front and the back positions of amplitude variation need to be adjusted;
s31: adjusting the initial tension of the main and auxiliary lifting hooks according to the proportional relation according to the result of the model solution, and observing the lifting state by a lifting operator before the actual tension value is close to the solution result and reaches 90% of the solution tension value of the lifted product, and connecting a supporting arrow body;
s32: the main hook and the auxiliary hook are linked, and stop until the distance between the arrow body and the support is 50cm, and the fixing pin for connecting the transport vehicle and the arrow body is removed;
s33: the main hook and the auxiliary hook are linked, so that the product is lifted to a height of 3m from the ground, the transport vehicle can withdraw and the transport vehicle withdraws from a hoisting area;
s34: the main hook and the auxiliary hook are linked to turn over and erect the product.
5. The method for stably hoisting the whole asymmetric distance double-hook tower crane arrow according to claim 4, is characterized in that: in step S3, in the first step, in the process of gradually increasing the tension before hoisting, the tension values of the main hook and the auxiliary hook have a definite proportional relation and definite reference values, so that accidental sliding caused by blind increase of the tension is avoided;
secondly, after the lifting is stable, the lifting mode is that the main hook and the auxiliary hook are linked to lift, and the main hook or the auxiliary hook does not act independently, so that the lifting process is more stable.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116730260A (en) * | 2023-08-10 | 2023-09-12 | 常熟市安得电力机具制造有限公司 | Hanging table for electric power construction |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116730260A (en) * | 2023-08-10 | 2023-09-12 | 常熟市安得电力机具制造有限公司 | Hanging table for electric power construction |
| CN116730260B (en) * | 2023-08-10 | 2023-10-24 | 常熟市安得电力机具制造有限公司 | Hanging table for electric power construction |
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