CN114618905A - Automatic control device and method for stretching amount in aluminum profile stretching and straightening - Google Patents

Automatic control device and method for stretching amount in aluminum profile stretching and straightening Download PDF

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CN114618905A
CN114618905A CN202210160953.9A CN202210160953A CN114618905A CN 114618905 A CN114618905 A CN 114618905A CN 202210160953 A CN202210160953 A CN 202210160953A CN 114618905 A CN114618905 A CN 114618905A
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stretching
trolley
movable
straightened
section bar
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CN114618905B (en
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孔庆顺
余忠华
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Zhejiang University ZJU
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Zhejiang University ZJU
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D3/00—Straightening or restoring form of metal rods, metal tubes, metal profiles, or specific articles made therefrom, whether or not in combination with sheet metal parts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21C—MANUFACTURE OF METAL SHEETS, WIRE, RODS, TUBES OR PROFILES, OTHERWISE THAN BY ROLLING; AUXILIARY OPERATIONS USED IN CONNECTION WITH METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL
    • B21C51/00—Measuring, gauging, indicating, counting, or marking devices specially adapted for use in the production or manipulation of material in accordance with subclasses B21B - B21F
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/02—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness
    • G01B11/028—Measuring arrangements characterised by the use of optical techniques for measuring length, width or thickness by measuring lateral position of a boundary of the object

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Straightening Metal Sheet-Like Bodies (AREA)

Abstract

The invention discloses a device and a method for automatically controlling stretching amount in aluminum profile stretching and straightening. The method comprises the steps of roughly estimating the length of a section bar, then clamping and stretching, carrying out data acquisition on a displacement sensor on a first movable stretching trolley and an oil pressure sensor on an oil cylinder for providing power for the first movable stretching trolley, identifying an elastic stretching interval through sliding window type least square fitting, and carrying out online parameter estimation through recursive least square fitting, and accurately measuring the initial length of the section bar in real time and accurately controlling the stretching amount. The invention realizes the real-time measurement of the initial length of the section bar and the control of the stretching amount in the stretching and straightening of the aluminum section bar during the design of the full-automatic production line of the stretching and straightening. The invention can accurately measure the initial length of the profile in real time, and simultaneously can accurately control the stretching amount of stretching and straightening, thereby solving the key problem for realizing the development of a full-automatic production line of stretching and straightening.

Description

Automatic control device and method for stretching amount in aluminum profile stretching and straightening
Technical Field
The invention relates to a profile stretching control device and method in the field of stretching and straightening, in particular to a method and a device for accurately controlling the stretching amount of a profile during stretching and straightening of aluminum or other alloys.
Background
With the development of the industry of China towards greenization, light weight, high speed and modernization, aluminum and aluminum alloy have the advantages of small density, high strength, good corrosion resistance and formability and the like, and the tendency of replacing steel with aluminum is greater, so that the aluminum alloy is widely applied to the industries of aviation, aerospace, weapons, automobiles, ships, naval vessels, mechanical manufacturing, household appliances, electronic communication and the like.
The aluminum profile has strict requirements on size and mechanical property, and the related fields have strict requirements on flatness and straightness. An important link in the manufacturing process of the aluminum profile is extrusion molding, and the extruded aluminum profile needs to be cooled through air cooling, fog cooling or water cooling. After the traction and the rapid cooling of the tractor, the aluminum profile is generally bent and twisted in different degrees, and uneven stress is also generated in the cross section direction. Therefore, in the post-processing zone in the extrusion production of the aluminum profiles, the aluminum profiles need to be stretch-straightened to eliminate the bending and twisting of the aluminum profiles and also eliminate the non-uniformity of the stress of the aluminum profiles in the cross-sectional direction. Therefore, the straightening process is also a non-negligible process.
At present, the aspects of the domestic stretching and straightening technology and equipment are behind developed countries, although semi-automation is realized, the key processes are still finished manually, for example, the control of the stretching amount of stretching and straightening still depends on manual experience, namely, the stretching amount depends on the feeling, workers can judge the stretching state by touching a section bar by hand, and a quantitative control technology is not realized. There are two major difficulties
(1) The lengths of the just extruded sections are different, some lengths even reach 45 meters, and the just extruded aluminum alloy sections are high in temperature and very soft, so that the sections are bent in the axial direction and the initial length of the sections is difficult to measure; secondly the jaws of the stretch-straightener would grip 30-40cm at the ends, which makes the actual length of the profile more difficult to measure.
(2) Secondly, when stretching the profile, there is an optimum stretching ratio at different temperatures in order not to break the profile and to make the profile theoretically straightest, which besides (1) the exact initial length cannot be measured and it is difficult to determine when the profile is taut and when it is the starting point for stretching, which makes it impossible to control the amount of stretching exactly.
Disclosure of Invention
Aiming at the full automation of an aluminum profile stretching and straightening production line, the invention aims to realize the real-time measurement and the stretching amount control of the initial length of a profile in stretching and straightening during the design of the full-automatic production line for stretching and straightening, and provides a method for the real-time accurate measurement and the stretching amount control of the initial length of the profile in stretching and straightening.
The technical scheme of the invention is as follows:
a stretching amount automatic control device in aluminum profile stretching and straightening comprises:
the device comprises a first movable stretching trolley, a second movable stretching trolley, a stay wire displacement sensor, an absolute encoder, a cooling bed, a first movable depth camera, a second movable depth camera, a proximity switch, a track and a positioning cylinder; the second movable stretching trolley and the first movable stretching trolley are respectively arranged at two ends of the track, the second movable stretching trolley and the first movable stretching trolley are movably arranged on the track along the track, a second movable depth camera is arranged on the second movable stretching trolley, and a first movable depth camera is fixed beside the side of the first movable stretching trolley; a cooling bed is arranged on the side of the track, a plurality of sectional materials to be straightened are transported on the cooling bed, the plurality of sectional materials to be straightened stretch and then span the plurality of cooling beds and are transported by the cooling bed, each sectional material to be straightened is arranged in parallel with the track, and the sectional materials to be straightened move horizontally on the cooling bed from a position far away from the track to a position close to the track; the second mobile depth camera and the first mobile depth camera face the section bar to be straightened on the cooling bed.
And a proximity switch is arranged on the cooling bed and close to the side part of the track, and the proximity switch is used for detecting whether the section bar to be straightened is fed to the position.
The first movable stretching trolley is connected with the stay wire displacement sensor, and the moving distance of the first movable stretching trolley along the track is detected through the stay wire displacement sensor;
the second movable stretching trolley is connected with the absolute encoder, and the distance of the second movable stretching trolley moving along the track is detected through the absolute encoder.
And a positioning cylinder is arranged on the side part of the cooling bed close to the track, and the positioning cylinder blocks the limit position of the section bar to be straightened, which is transported by the cooling bed.
The first movable stretching trolley and the second movable stretching trolley are both provided with a mechanical arm and a clamping jaw, the mechanical arm is used for clamping the end part of the section to be straightened and loading the section to the clamping jaw, and the clamping jaw clamps and fixes the end part of the section to be straightened.
The first movable stretching trolley is characterized in that an oil cylinder is arranged beside the first movable stretching trolley, a cylinder rod of the oil cylinder is fixedly connected with the first movable stretching trolley to drive the first movable stretching trolley to move along a track, an oil pressure sensor is installed on an oil cavity of the oil cylinder and used for detecting oil pressure in the oil cylinder, and then the oil pressure sensor is converted into driving force for driving the first movable stretching trolley to move.
Secondly, an automatic control method for stretching amount in aluminum profile stretching and straightening comprises the following steps:
s1, in the initial condition, two reference positions are set up, the position of the initial starting point of the second movable stretching trolley is measured through an absolute encoder to be used as a second reference position, the position of the initial starting point of the first movable stretching trolley is measured through a stay wire displacement sensor to be used as a first reference position, the distance X0 between the second reference position and the first reference position is obtained through measurement in advance, and the position of the first movable depth camera is fixed, so the distance relative to the first reference position is fixed;
s2, when the proximity switch detects that the section to be straightened is carried to a position to be straightened of the cooling bed, the first movable stretching trolley and the second movable stretching trolley move along the track to drive the first movable depth camera and the second movable depth camera to shoot and position the two end parts of the section to be straightened below, then respective mechanical hands are driven to grab and clamp the end parts of the section to be straightened and are arranged in respective clamping jaws, the clamping jaws of the first movable stretching trolley and the second movable stretching trolley respectively clamp and fix the two end parts of the section to be straightened, and the section to be straightened is in a naturally drooping state; in the process, the moving distance X4 'of the first mobile stretching trolley from the first reference position is acquired in real time through a stay wire displacement sensor, and the moving distance X6' of the second mobile stretching trolley from the second reference position is acquired in real time through an absolute encoder;
s3, roughly obtaining the length L of the profile to be straightened along the horizontal direction in the natural sagging state according to the distance X0, the moving distance X4 'and the moving distance X6', namely, as shown in fig. 2, the horizontal distance between the clamping point of the first moving stretching trolley 1 and the clamping point of the second moving stretching trolley 2:
L＝X0-X4′-X6′
wherein, X4 'and X6' are initial data before stretching after clamping, respectively.
S4, keeping the second movable drawing trolley fixed, and generating a drawing force F through the oil cylinder to drive the first movable drawing trolley to move in a direction away from the second movable drawing trolley to draw the section bar to be straightened, so that the section bar to be straightened gradually hangs down naturally, and is stretched, stretched and deformed gradually from straightening;
s5, at S4 in-process, gather the oil pressure that detects the hydro-cylinder through oil pressure sensor in real time and gather the tensile displacement S that detects the tensile dolly of first removal through acting as go-between displacement sensor in real time, convert oil pressure that oil pressure sensor detected the hydro-cylinder into tensile force F, constitute a data point by tensile force F and the tensile displacement S at single moment, judge that the data point of gathering at the present moment has or not to be in the elastic stretching interval:
if the data point collected at the current moment is in the elastic stretching interval, the next step is carried out;
if the data point collected at the current moment is not in the elastic stretching interval, continuously driving the first movable stretching trolley to pull the section bar to be straightened;
the stretching distance S after the first movable stretching trolley begins to stretch has the following relationship:
L+S＝X0-X4-X6
s represents the stretching displacement of the first movable stretching trolley after the first movable stretching trolley starts to pull the section bar to be straightened; x4 represents the real-time acquisition of the moving distance of the first mobile stretching car from the first reference position by the pull wire displacement sensor after the stretching is started, and X6 represents the real-time acquisition of the moving distance of the second mobile stretching car from the second reference position by the absolute encoder after the stretching is started.
S6, if the elastic stretching region is located, carrying out online parameter estimation on the variation trend of 200 data points which are collected after the elastic stretching region and are expected to be 100, obtaining the fitting parameters of the fitting straight line of the elastic stretching region, wherein the stretching distance S and the stretching force F in the data points have the following relation:
F＝β0×1+β1×S+e
wherein S is a state value which is a stretching distance after the start of stretching, F is a stretching force obtained by converting hydraulic sensor data which is an observed value of the stretching force, and β0×1+β1Xs is the predicted value of the tensile force, where β0Denotes the first fitting parameter, β1Representing a second fitting parameter; e is the residual, i.e. the observed value F minus the predicted value beta of the force0×1+β1Difference of xs;
fitting a parameter beta with the minimum sum of the observed value of the force and the square of the residual error of the predicted value as a target0、β1Comprises the following steps:
Figure BDA0003514643780000041
Figure BDA0003514643780000042
PN＝(PN-1 -1+xN TFN)-1
P1 -1＝WTW
Figure BDA0003514643780000043
wherein Q is the initial Q data points in the elastic stretching interval, and beta1First, selecting the first Q data points to carry out least square fitting, and taking the least square fitting as an initial parameter. SNFor the displacement data of the first mobile stretching carriage collected at time t, FNFor the pressure value of the pressure sensor acquired at time t being converted into force data, xN TIs the state vector at time t, PNFor continuously iteratively correcting the parameters, P1Denotes the initial correction parameter, W is the first QA state matrix composed of state vectors; beta is atIs represented by beta0、β1Form of a matrix of compositions, SQRepresents the tensile displacement S of the Q-th data point; sQAnd SNIs distinguished by SNFor data acquired in real time at the moment t, the system samples with the stretching displacement S at equal intervals, and the first acquired data is S1The Q-th data is SQ。
S7 fitting parameter beta obtained according to S60And beta1Then, a fitting straight line F' ═ beta of the elastic stretching region is obtained0×1+β1Xs, F' represents the predicted value of force;
then the predicted value F' of the force is used as the friction force of the first movable stretching trolley to obtain the moving distance S of the first movable stretching trolley when the section bar is in the state of being naturally suspended initially to be straightened, and the moving distance S is represented by X:
Figure BDA0003514643780000044
and finally, calculating and obtaining the displacement S' for controlling the first movable stretching trolley to start moving from the starting point of the second reference position according to the following formula:
S′＝X+Δ
Δ ═ X (X0-X4 '-X6' + X) elongation
And controlling and moving the second movable stretching trolley according to the displacement S' so that the section is precisely stretched, and the length of the section reaches a precise stretching amount.
The stretching ratio is obtained by single-axis stretching experimental treatment at different temperatures in advance.
Therefore, the stretching force F exists in the stretching process, the data of the stretching force F and the stretching displacement S are collected for analysis, and then the stretching, straightening and stretching amount is accurately controlled.
In S5, determining whether the data point collected at the current time is in the elastic stretching region is shown in fig. 6, which specifically includes: the slope k of the change between the stretching force F and the stretching displacement S of the m data points before the current moment is obtained by fitting calculation by adopting the following formula, namely the m data points which are continuously collected are fitted:
Figure BDA0003514643780000051
wherein m represents the total number of collected data points and i represents the ordinal number of the collected data points; siTensile displacements S, F representing the ith data pointiTensile force F representing the ith data point;
and if the fitting slopes of the continuous m data points are all larger than a preset slope threshold K, the data points acquired at the current moment are in an elastic stretching interval.
The specific implementation can establish a data process library, and different threshold values K are set according to the specification and the material of the section bar so as to adapt to different section bars.
When collecting data points at S5, the step size is determined as follows:
the movement distance l in the elastic stretch zone of the profile 6 is first roughly calculated according to the following formula, as shown in fig. 6:
Figure BDA0003514643780000052
wherein σsThe yield strength at the corresponding temperature, and E the modulus of elasticity at normal temperature;
calculating the distance of data acquisition points after the movement distance l in the elastic stretching region is distributed, acquiring at least N points in the movement distance l in the elastic stretching region, specifically predicting 100 and 200 data points in N times, and making the step length of the acquisition distance interval be less than
Figure BDA0003514643780000053
The distance of (c).
Fig. 3 shows the parameterized model in the pre-stretched state after clamping. A position reference is respectively arranged on the trolleys on the two sides, and the distance X0 between the two references is known. Since the first carriage is equipped with the stretching displacement sensor 3, X4 (distance from reference 1 to point D in fig. 2) indicates that the initial data of clamped and unstretched state is X4'; since the second carriage 2 is equipped with an absolute encoder, X6 knows (distance from the reference 2 to the point D of the other carriage), and the initial data of the clamped and unstretched carriage is X6'; the distance between the D points (the clamping point of the trolley shown in figure 2, the same trolley on the other side) of the profile in any state is known (X0-X4-X6). Then, the two difficulties mentioned in the background of the art can be solved by studying the relationship between the distance between the D points on both sides (different stretching states of the profile) and the stretching force (data conversion of the oil pressure sensor) in the stretching process at different temperatures.
Taking a solar profile as an example, fig. 4 is a graph of displacement-tension (S-F) relationship of a first mobile stretching trolley for simulating the stretching process by stretching with a length of 20m through finite element analysis. The curve 1 is completely suspended and stretched; the curve 2 simulates stretching in a real state, and the height difference between the jaw and the horizontal plane of the cooling bed is set to be 3 cm; and 3, removing the stretching under the gravity acceleration. The distance between the D points on the two sides when the jaws clamp the profile and the stretching starts is X0-X4-X6, and X is the stretching distance of the first movable stretching trolley 1, and if the profile is stretched to the position of 21cm in figure 5 in 3 simulation states, the distance between the D points on the two jaws is equal to the length (the length of the profile counted by the D points on the two sides is the same) of the stretched profile (the length of the profile is not stretched but the straightness is 0), so that the displacement-tension relationship graph is as shown in figure 3. Curve 3 is the stretching without gravity, and only the friction force of the stretching trolley is needed before the stretching to 21 cm; the curve 1 is in a curve state at the initial stretching stage because the section bar can droop under the action of gravity; curve 2 is between curves 1 and 3 because of some time during the initial stage of stretching, but the difference in stretching force between the three curves is still large. However, the curves finally converge on a line under constant stretching, and the point of 21cm is the intersection point of the slope line F (F) and F, which is the friction force of the second mobile stretching trolley 1. Therefore, the straight line during the drawing process can be identified by the on-line parameter identification, and then the intersection point X of the friction force of the second traveling carriage and F is obtained, that is, the profile length X0-X4 ' -X6 ' + X can be obtained, and on the basis of this point, the actual drawing length S ' to be controlled is calculated in accordance with the drawing ratio.
After S 'is calculated, the data are issued to the PLC, and the PLC compares the numerical value change of the stay wire displacement sensor with S' in real time, so that the stretching distance of the oil cylinder is controlled.
According to the method, firstly, the length of the section is roughly estimated through a parameter model shown in FIG. 3, then clamping and stretching are carried out, data acquisition is carried out on a displacement sensor on a first movable stretching trolley and an oil pressure sensor on an oil cylinder for providing power for the first movable stretching trolley, an elastic stretching interval is identified through sliding window type least square fitting, online parameter estimation is carried out through recursive least square fitting, the initial length of the section is accurately measured in real time, and meanwhile, the stretching amount of the section is accurately controlled.
The invention has the beneficial effects that:
the invention can accurately measure the initial length of the profile in real time, and simultaneously can accurately control the stretching amount of stretching and straightening, thereby solving the key problem for realizing the development of a full-automatic production line of stretching and straightening.
Drawings
FIG. 1 is a layout view of a stretching portion of a stretching alignment line;
FIG. 2 is a view showing a state of clamping jaws and a state of a section bar;
FIG. 3 is a parameterized model in a post-clamping, pre-tension state;
FIG. 4 is a drawing showing a comparison of tensile force-displacement finite element simulation in a stretching and straightening process under different conditions;
FIG. 5 is a drawing of a tension-displacement finite element simulation during a stretching and straightening process with noise added under a real condition;
FIG. 6 is a slope plot of a sliding window least squares fit to the data of FIG. 6;
FIG. 7 is a graph of convergence of parameter identification;
FIG. 8 is a graph of the identified convergence of the intersection of the fitted line and the friction force;
fig. 9 is a flowchart of a precise control method.
In the figure: the device comprises a first movable stretching trolley 1, a second movable stretching trolley 2, a wire pulling displacement sensor 3, an absolute encoder 4, a cooling bed 5, a section to be straightened 6, a first fixed depth camera 7, a second movable depth camera 8, a proximity switch 9, a track 10, a positioning cylinder 11, an oil cylinder 12, an oil pressure sensor 13, a manipulator 14 and a clamping jaw 15.
Detailed Description
The invention is further described with reference to the accompanying drawings and the detailed description.
As shown in fig. 1, the device comprises a first movable stretching trolley, a second movable stretching trolley, a stay wire displacement sensor, an absolute encoder, a cooling bed, a first movable depth camera, a second movable depth camera, a proximity switch, a track and a positioning cylinder; the second movable stretching trolley and the first movable stretching trolley are respectively arranged at two ends of the track, the second movable stretching trolley and the first movable stretching trolley are movably arranged on the track along the track, a second movable depth camera is arranged on the second movable stretching trolley, and a first movable depth camera is fixed beside the side of the first movable stretching trolley; a plurality of cooling beds are arranged on the side of the track, each cooling bed is provided with a conveyor belt, a plurality of sectional materials to be straightened are transported on the cooling beds, the plurality of sectional materials to be straightened are stretched and then arranged across the plurality of cooling beds and transported by the cooling beds, each sectional material to be straightened is arranged in parallel to the track, and the sectional materials to be straightened are translated on the cooling beds from a position far away from the track to a position close to the track; the second mobile depth camera and the first mobile depth camera face the section to be straightened on the cooling bed, and the lens of the two cameras is vertically downward and is positioned at a certain height above the cooling bed.
And a proximity switch is arranged on the cooling bed and close to the side part of the track, the proximity switch is used for detecting whether the section to be straightened is fed to the position, namely whether the section to be straightened reaches the position on the cooling bed close to one side of the track, and when the feeding is detected to be in place, the two cameras start to simultaneously acquire data.
The first movable depth camera is positioned above the end part of the section to be straightened, which is close to one end of the first movable stretching trolley.
The first mobile stretching trolley is used for moving in a small range and is connected with the stay wire displacement sensor, and the stay wire displacement sensor is used for detecting the moving distance of the first mobile stretching trolley along the track;
the second movable stretching trolley is used for moving in a larger range and is connected with the absolute encoder, and the distance of the second movable stretching trolley moving along the track is detected through the absolute encoder.
And a positioning cylinder is arranged on the side part of the cooling bed close to the track, and the positioning cylinder blocks the limit position of the section bar to be straightened, which is transported by the cooling bed.
The absolute encoder adopts the encoder of gyro wheel structure, specifically can adopt meter rice wheel, and meter rice wheel rolls on following the track and detects.
The first movable stretching trolley 1 provides stretching force and stretching displacement, and the second movable stretching trolley 2 is used for clamping one end of the section bar for fixing. A first mobile depth camera 7 is fixed on the ground for detecting the end position of this side profile end. Second mobile depth camera 8 years old second mobile stretching trolley 2 moves to identify and locate the position of the profile end on this side.
The cooling bed 5 is arranged on one side of the track 10 and used for carrying and placing the section bar, and the proximity switch 9 is used for detecting whether the section bar to be straightened is carried to a position to be loaded by the cooling bed 5. Each conveyor belt side of the cooling beds 5 is provided with a positioning cylinder 11 (for positioning but not limited to air cylinder) and is used for positioning the section bar to be straightened in a straight line, and the section bar 6 is positioned by being blocked by the positioning cylinder 11 on each cooling bed 5 when being transported to the end closest to the track 10 by each cooling bed 5, so that the section bar 6 is kept in a straight line during length measurement.
And the first movable stretching trolley and the second movable stretching trolley are both provided with a manipulator and a clamping jaw, the manipulator is used for grabbing the end part of the section bar to be aligned and loading the section bar into the clamping jaw, and the clamping jaw clamps and fixes the end part of the section bar to be aligned.
An oil cylinder is arranged beside the first movable stretching trolley, a cylinder rod of the oil cylinder is fixedly connected with the first movable stretching trolley to drive the first movable stretching trolley to move along a track, an oil pressure sensor is arranged in an oil cavity of the oil cylinder and used for detecting oil pressure in the oil cylinder, and then the oil pressure sensor is converted into driving force for driving the first movable stretching trolley to move. The driving force for driving the first movable stretching trolley to move has a direct proportion relation with the oil pressure in the oil cylinder.
As shown in fig. 9, the specific implementation process of the present invention is as follows:
step 1, in fig. 3, a parameterized model in a state before stretching after clamping is provided, a position reference is respectively arranged near the trolleys at two sides, and the distance X0 between the two references is known. Since the first mobile stretching cart 1 is equipped with the stretching displacement sensor 3, X4 (distance from reference 1 to point D in fig. 2) indicates that the initial data of the clamped and unstretched state is X4'; since the absolute encoder 4 is attached to the second mobile stretching carriage 2, X6 knows (distance from the reference 2 to the point D of the other stretching carriage) that the initial data of the clamped and unstretched state is X6'; in order to determine the next data acquisition step length, recording the rough length of the profile, namely the initial distance between D points of trolleys on two sides before stretching after clamping:
L＝X0-X4’-X6’
meanwhile, the distance between the D points of the trolleys (the clamping point of the first movable drawing trolley 1 shown in figure 2, and the same second movable drawing trolley 2 on the other side) of the section bar 6 in any drawing state is known during drawing (X0-X4-X6). Assuming that the stretching distance after the first mobile stretching trolley 1 starts stretching is S, there are:
L+S＝X0-X4-X6
and then, the stretching is accurately controlled by analyzing the stretching force F and the stretching displacement S. Since noise exists in the stretching process, that is, the data has some interference or fluctuation, taking the solar aluminum alloy profile as an example, random vibration is added into curve 2 of fig. 4, and a finite element simulation is performed, and the result is shown in fig. 6. This data illustrates the parameter online identification process.
Step 2, temperature can affect the parameter performance of the material, preparation work is carried out in the early stage of equipment development, a mathematical model of material parameters and temperature needs to be established, and if the model of yield strength and temperature is:
σs T＝f(T)
the distance L, σ of the elastic stretch interval (fig. 5) of the profile 6 is then roughly calculated from the rough length L and the yield strength and the elastic modulus of the profile 6 at the respective temperaturesFor the yield strength at the corresponding temperature, E is the modulus of elasticity at room temperature (used to calculate roughly l):
Figure BDA0003514643780000091
calculating the distance, i.e. the step size, from the start of distributing data acquisition points after l, predicting to acquire at least N points (predicting 100-200 data points) in the elastic region, so that the acquisition step size is smaller than
Figure BDA0003514643780000092
A certain distance of (a).
Step 3, after stretching starts, the PLC starts to collect data points (displacement and stretching force) immediately, and in order to identify parameters accurately and accelerate convergence, it is first determined whether the collected data points are in an elastic stretching interval (fig. 5), and therefore at the beginning of data collection, a sliding window least square fitting is adopted to fit a slope k, i.e. m continuous points are fitted:
Figure BDA0003514643780000093
and moving forward one point at a time integrally, if the fitting slope of the continuously moving r points is larger than the slope threshold K,
min(k1，…，kr)＞K
i.e. the acquisition point is considered to have reached the elastic stretch zone, a sliding window minimum two-way fit is performed on the data of fig. 5, and m is 10, and the result is fig. 6, and the numerical jump is obvious.
And 4, in order to reduce the system performance requirement, accelerate the calculation and perform parameter identification in real time, performing parameter estimation on the variation trend of the data points in the elastic interval by adopting a recursive least square algorithm. The following relationship between stretch distance S and stretch force F is known at the elastic stretch interval data points:
F＝β0×1+β1×S+e
wherein S is a state value which is a stretching distance after the start of stretching, F is a stretching force obtained by converting data of a hydraulic sensor (13) which is an observed value of the stretching force, and beta0×1+β1X S is prediction of tensile forceValue of wherein0Denotes the first fitting parameter, β1Representing a second fitting parameter; e is the residual, i.e. the observed value F minus the predicted value beta of the force0×1+β1The difference of x S, the minimum of the sum of the squares of the observed and predicted residual values of the force, is used as a target to fit a parameter beta0、β1，
Then there are:
Figure BDA0003514643780000101
wherein
Figure BDA0003514643780000102
PN＝(PN-1 -1+xNFN)-1
P1 -1＝WTW
Figure BDA0003514643780000103
Q is the initial Q point in the elastic stretching interval. Beta is atAnd selecting the first Q points to perform least square fitting to serve as initial parameters, and then utilizing the N points to perform iteration. Wherein Q is the initial Q data points in the elastic stretching interval, and beta1First, selecting the first Q data points to carry out least square fitting, and taking the least square fitting as an initial parameter. SNFor the displacement data of the first mobile stretching trolley (1) collected at the time t, FNThe pressure value of the pressure sensor collected for time t is converted into force data, xN TIs the state vector at time t, PNFor continuously iteratively correcting the parameters, P1Representing initial correction parameters, wherein W is a state matrix formed by the first Q state vectors; beta is atIs expressed by beta0、β1Form of a matrix of compositions, SQRepresents the tensile displacement S of the Q-th data point; sQAnd SNIs distinguished by SNFor time t in real timeThe collected data is sampled by the system along with stretching displacement S at equal intervals, and the first collected data is S1The Q-th data is SQ。
Identification with the simulated data of FIG. 5, β0，β1The identified convergence curve of (2) is shown in fig. 7.
Assuming that the predicted value of the force is represented by F ', a fitted line F' β of the elastic stretch zone is obtained0×1+β1×S，
Then changing F' to FFriction of the first mobile stretching trolley (1)Substituting to obtain the moving distance S of the first moving stretching trolley (1) when the section bar is from the initial natural sagging state to the state of being straightened, and if X is used,
Figure BDA0003514643780000104
as shown in FIG. 8, X converges rapidly, at 20.9137cm, within 1mm of 21cm from the theoretical position.
And 5, the accurate length of the profile is X0-X4-X6+ X. On the basis of this point, the stretch length was calculated as:
Δ ═ X (X0-X4 '-X6' + X) elongation
The controlled travel distance for the final fixed trolley as it is stretched is:
S′＝X+Δ
and 6, after the S is calculated, the data are issued to the PLC, and the PLC compares the numerical value change of the stay wire displacement sensor with the S in real time, so that the stretching distance of the oil cylinder is controlled, and the stretching amount is accurately controlled.
In addition, because the material is different and the profile specifications are various, the threshold value K in step 4 has a certain difference, so that a process database needs to be established so as to straighten the profiles with different specifications.

Claims (9)

1. The utility model provides a tensile volume automatic control device in tensile alignment of aluminium alloy which characterized in that:
the device comprises a first movable stretching trolley (1), a second movable stretching trolley (2), a stay wire displacement sensor (3), an absolute encoder (4), a cooling bed (5), a first movable depth camera (7), a second movable depth camera (8), a proximity switch (9), a track (10) and a positioning cylinder (11); the second movable stretching trolley (2) and the first movable stretching trolley (1) are respectively arranged at two ends of the track (10), the second movable stretching trolley (2) and the first movable stretching trolley (1) can be movably mounted on the track (10) along the track (10), the second movable stretching trolley (2) is provided with a second movable depth camera (8), and a first movable depth camera (7) is fixed beside the side of the first movable stretching trolley (1); a cooling bed (5) is arranged on the side of the track (10), a plurality of sectional materials (6) to be straightened are transported on the cooling bed (5), the plurality of sectional materials (6) to be straightened stretch and then span the plurality of cooling beds (5) and are transported by the cooling bed (5), each sectional material (6) to be straightened is arranged in parallel to the track (10), and the sectional material (6) to be straightened is translated on the cooling bed (5) from a position far away from the track (10) to a position close to the track (10); the second mobile depth camera (8) and the first mobile depth camera (7) face the section bar (6) to be straightened on the cooling bed (5).
2. The automatic control device for the stretching amount in the stretching and straightening of the aluminum profile according to claim 1, is characterized in that: and a proximity switch (9) is arranged on the cooling bed (5) and close to the side part of the track (10), and the proximity switch (9) is used for detecting whether the section bar (6) to be straightened is fed in place.
3. The automatic control device for the stretching amount in the stretching and straightening of the aluminum profile according to claim 1, is characterized in that: the first mobile stretching trolley (1) is connected with the stay wire displacement sensor (3), and the moving distance of the first mobile stretching trolley (1) along the track (10) is detected through the stay wire displacement sensor (3);
the second movable stretching trolley (2) is connected with the absolute encoder (4), and the distance of the second movable stretching trolley (2) moving along the track (10) is detected through the absolute encoder (4).
4. The automatic control device for the stretching amount in the stretching and straightening of the aluminum profile according to claim 1, is characterized in that: and a positioning cylinder (11) is arranged on the side part of the cooling bed (5) close to the track (10), and the limiting position of the section bar (6) to be straightened, which is transported by the cooling bed (5), is blocked by the positioning cylinder (11).
5. The automatic control device for the stretching amount in the stretching and straightening of the aluminum profile according to claim 1, is characterized in that: the first movable stretching trolley (1) and the second movable stretching trolley (2) are respectively provided with a manipulator (14) and a clamping jaw (15), the manipulators (14) are used for clamping the end part of the section bar (6) to be straightened and loading the section bar into the clamping jaws (15), and the clamping jaws (15) clamp and fix the end part of the section bar (6) to be straightened.
6. The automatic control device for the stretching amount in the stretching and straightening of the aluminum profile according to claim 1, is characterized in that: the first tensile dolly of removal (1) other hydro-cylinder (12) that is equipped with, the cylinder pole and the tensile dolly of first removal (1) rigid coupling of hydro-cylinder (12), the tensile dolly of drive first removal (1) moves along track (10), hydro-cylinder (12) oil cavity body installation oil pressure sensor (13), oil pressure sensor (13) are used for detecting the oil pressure in hydro-cylinder (12), and then convert the drive power that the tensile dolly of drive first removal (1) removed into.
7. An automatic control method of stretching amount in stretching and straightening of aluminum section bar applied to the device of any one of claims 1-6, characterized in that:
s1, in the initial condition, measuring the position of the initial starting point of the second mobile stretching trolley (2) as a second reference position through an absolute encoder (4), measuring the position of the initial starting point of the first mobile stretching trolley (1) as a first reference position through a stay wire displacement sensor (3), and measuring in advance to obtain a distance X0 between the second reference position and the first reference position;
s2, when the proximity switch (9) detects that the section bar (6) to be straightened is carried to the position of the cooling bed (5) to be straightened, the first movable stretching trolley (1) and the second movable stretching trolley (2) move along the track (10) to drive the first movable depth camera (7) and the second movable depth camera (8) to shoot and position the two end parts of the section bar (6) to be straightened below, then the respective mechanical arms (14) are driven to grab and clamp the end parts of the section bar (6) to be straightened and are loaded into the respective clamping jaws (15), and the clamping jaws (15) of the first movable stretching trolley (1) and the second movable stretching trolley (2) clamp and fix the two end parts of the section bar (6) to be straightened respectively; then acquiring the moving distance X4 'of the first moving stretching trolley (1) from the first reference position in real time through a stay wire displacement sensor (3), and acquiring the moving distance X6' of the second moving stretching trolley (2) from the second reference position in real time through an absolute encoder (4);
s3, roughly obtaining the length L of the section bar (6) to be straightened along the horizontal direction in a naturally sagging state according to the distance X0, the moving distance X4 'and the moving distance X6':
L＝X0-X4′-X6′
s4, keeping the second movable drawing trolley (2) fixed, and generating a drawing force F through the oil cylinder (12) to drive the first movable drawing trolley (1) to move so as to draw the section bar (6) to be straightened, so that the section bar (6) to be straightened is gradually straightened from natural sagging, and then is gradually stretched, elongated and deformed from straightening to gradual stretching;
s5, in the process of S4, the oil pressure of the oil cylinder (12) is collected and detected through the oil pressure sensor (13) in real time, the stretching displacement S of the first movable stretching trolley (1) is collected and detected through the stay wire displacement sensor (3) in real time, the oil pressure of the oil cylinder (12) detected by the oil pressure sensor (13) is converted into a stretching force F, a data point is formed by the stretching force F and the stretching displacement S at a single moment, and whether the data point collected at the current moment is in an elastic stretching interval or not is judged:
if the data point collected at the current moment is in the elastic stretching interval, the next step is carried out;
if the data point collected at the current moment is not in the elastic stretching interval, the first movable stretching trolley (1) is continuously driven to pull the section bar (6) to be straightened;
s6, carrying out online parameter estimation on the variation trend of 200 data points which are collected after the elastic stretching region and are expected to be 100-:
F＝β0×1+β1×S+e
wherein S is a state value which is a stretching distance after the start of stretching, F is a stretching force obtained by converting data of a hydraulic sensor (13) which is an observed value of the stretching force, and beta0×1+β1Xs is the predicted value of the tensile force, where β0Denotes the first fitting parameter, β1Representing a second fitting parameter; e is the residual, i.e. the observed value F minus the predicted value beta of the force0×1+β1Difference of xs;
fitting a parameter beta with the minimum sum of the observed value of the force and the square of the residual error of the predicted value as a target0、β1Comprises the following steps:
Figure FDA0003514643770000031
Figure FDA0003514643770000032
PN＝(PN-1 -1+xN TFN)-1
P1 -1＝WTW
Figure FDA0003514643770000033
wherein Q is the initial Q data points in the elastic stretching interval, SNFor the displacement data of the first mobile stretching trolley (1) collected at the time t, FNThe pressure value of the pressure sensor collected for time t is converted into force data, xN TIs the state vector at time t, PNFor continuously iteratively correcting the parameters, P1Representing initial correction parameters, wherein W is a state matrix formed by the first Q state vectors; beta is atIs represented by beta0、β1Form of a matrix of compositions, SQRepresents the tensile displacement S of the Q-th data point;
s7 fitting parameter beta obtained according to S60And beta1Then obtainFitting a straight line F' ═ beta to the elastic stretch zone0×1+β1Xs, F' represents the predicted value of force;
and then the predicted value F' of the force is used as the friction force of the first movable stretching trolley (1) to obtain the moving distance S of the first movable stretching trolley (1) when the section bar is in the initial natural sagging state to the just stretched state, and the moving distance S is represented by X:
Figure FDA0003514643770000034
and finally, calculating and obtaining the displacement S' for controlling the first movable stretching trolley (1) to start moving from the starting point of the second reference position according to the following formula:
S′＝X+Δ
Δ ═ X (X0-X4 '-X6' + X) elongation
The second mobile stretching trolley (1) is controlled to move according to the displacement S' so that the section bar is precisely stretched.
8. The automatic control method for the stretching amount in the stretching and straightening of the aluminum profile as claimed in claim 7, characterized in that: in S5, determining whether the data point collected at the current time is in the elastic stretch zone, specifically: the slope k of the change between the stretching force F and the stretching displacement S of m data points before the current moment is obtained by fitting calculation by adopting the following formula:
Figure FDA0003514643770000041
wherein m represents the total number of collected data points and i represents the ordinal number of the collected data points; siTensile displacements S, F representing the ith data pointiTensile force F representing the ith data point;
and if the fitting slopes of the continuous m data points are all larger than a preset slope threshold K, the data points acquired at the current moment are in an elastic stretching interval.
9. The automatic control method for the stretching amount in the stretching and straightening of the aluminum profile according to claim 7 is characterized in that: when collecting data points at S5, the step size is determined as follows:
firstly, the moving distance l in the elastic stretching interval of the section bar 6 is roughly calculated according to the following formula:
Figure FDA0003514643770000042
wherein σsThe yield strength at the corresponding temperature, and E the modulus of elasticity at normal temperature;
at least N points are collected according to the roughly calculated moving distance l under the elastic stretching interval.
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