Section steel bending method based on vision measurement
阅读说明：本技术 基于视觉测量的型钢弯曲方法 (Section steel bending method based on vision measurement ) 是由 马子领 高兵涛 张利 张海林 于 2021-06-23 设计创作，主要内容包括：本发明公开了一种基于视觉测量的型钢弯曲方法,第一是上料,将型钢由进口送入壳体并穿过各型钢支撑装置；第二是顶压和进前；第三是在第二步骤的进行过程中使照明灯保持开启状态,同时电控装置持续进行图像识别型钢弯曲度,在型钢弯曲度与预定弯曲度不一致时实时调节顶推装置的伸出杆的伸出量,使型钢的弯曲度一次成型达到预定的弯曲度；最后是持续进行第二步骤和第三步骤,使型钢无须后退一次顶压并回弹至预定弯曲度。本发明使得型钢在一次受压弯曲后经非线性回弹直接达到预定弯曲度,避免反复进退并顶压型钢,大幅提高了型钢折弯的工作效率,节约了反复进退并顶压时消耗的能耗,整体上大幅降低了型钢折弯所需的能耗,节能提效的作用十分明显。(The invention discloses a section steel bending method based on visual measurement, which comprises the steps of firstly, feeding section steel into a shell from an inlet and penetrating through various section steel supporting devices; secondly, jacking and advancing; thirdly, in the process of the second step, the illuminating lamp is kept in an on state, meanwhile, the electric control device continuously conducts image recognition on the curvature of the section steel, and when the curvature of the section steel is inconsistent with the preset curvature, the extension amount of an extension rod of the pushing device is adjusted in real time, so that the curvature of the section steel is formed at one time to reach the preset curvature; and finally, continuously performing the second step and the third step to ensure that the section steel does not need to retreat for one time to be pressed and rebounded to the preset bending degree. The invention ensures that the section steel directly reaches the preset curvature after being bent by one-time compression through nonlinear resilience, avoids repeated advance and retreat and jacking the section steel, greatly improves the working efficiency of section steel bending, saves the energy consumption consumed during repeated advance and retreat and jacking, greatly reduces the energy consumption required by section steel bending on the whole, and has very obvious effects of saving energy and improving efficiency.)
1. The profile steel bending method based on vision measurement uses a profile steel bending degree measuring device to carry out, the profile steel bending degree measuring device comprises a profile steel bending machine, the profile steel bending machine comprises a workbench, the advancing direction of the profile steel is the downstream direction, a profile steel driving device and a profile steel supporting device used for supporting the profile steel are arranged on the workbench along the arc line from the upstream to the downstream direction, and a pushing device is further arranged on the workbench and is characterized in that:
the profile steel driving device comprises a positive and negative rotation motor and driving wheels driven by the positive and negative rotation motor, two sets of profile steel driving devices are arranged at intervals, the two sets of profile steel driving devices are symmetrically arranged about the pushing device, the pushing device is provided with an extension rod, and the end part of the extension rod is provided with a pressing shaft which is used for pressing the profile steel on the driving wheels of the two sets of profile steel driving devices; the pushing device is a working hydraulic cylinder or a working electric push rod or a working air cylinder;
a curvature measuring mechanism is arranged in the downstream direction of the workbench and comprises a camera mechanism and an illuminating mechanism;
the profile steel advancing path on the downstream side of the workbench is called a downstream profile steel path, the camera mechanism comprises a portal frame crossing the downstream profile steel path, a camera is arranged at the top of the portal frame, the camera is positioned right above the downstream profile steel path, and the shooting direction of the camera faces downwards;
the lighting mechanism is provided with a plurality of sets of lighting devices, and the lighting devices are dispersedly arranged on two sides of the downstream section steel path; each illuminating mechanism has the same structure and comprises an illuminating bracket, the top end of the illuminating bracket is provided with an illuminating lamp, and the illuminating lamp is higher than the camera;
the illuminating lamp, the camera, the forward and reverse rotating motors of the various steel driving devices and the pushing device are respectively connected with an electric control device through lines, and the electric control device is connected with a display screen;
a first section steel supporting device, a first driving device, a second section steel supporting device, a second driving device and a third section steel supporting device are arranged on a workbench of the section steel bending machine at intervals along an arc line from the upstream to the downstream; the first section steel supporting device and the fourth section steel supporting device are symmetrically arranged around the pushing device, and the second section steel supporting device and the third section steel supporting device are symmetrically arranged around the pushing device; the structural steel supporting devices are identical in structure and respectively comprise a supporting frame, an upper limiting shaft and a lower supporting shaft which are arranged on the supporting frame at intervals up and down, the distance between the upper limiting shaft and the lower supporting shaft is matched with the thickness of the structural steel, and a supporting limiting space is defined by the upper limiting shaft and the lower supporting shaft; the profile steel sequentially penetrates through the various profile steel supporting devices through supporting limiting spaces of the various profile steel supporting devices, the lower supporting shaft is used for supporting the profile steel, and the upper limiting shaft is used for preventing the profile steel from moving up and down in the bending process;
the device also comprises a shell, wherein the shell covers the workbench, the profile steel driving device, the profile steel supporting device, the pushing device and the curvature measuring mechanism;
the upstream end of the shell is provided with an inlet for entering the section steel, the downstream end of the shell is provided with an outlet for sending out the section steel, the outlet and the inlet are respectively provided with a cloth curtain or a plastic curtain for shielding external light, and the cloth curtain or the plastic curtain is provided with an opening for passing the section steel;
the section steel bending method based on visual measurement comprises the following steps:
the first step is feeding; feeding the section steel into the shell from the inlet and penetrating through each section steel supporting device;
secondly, jacking and advancing; the pushing device is controlled by the electric control device to apply a preset jacking force to the profile steel, so that the profile steel is jacked on the driving wheels of the two sets of profile steel driving devices;
starting positive and negative rotating motors of various profile steel driving devices to synchronously operate, driving wheels drive the profile steel to move towards a downstream direction under the action of friction force, and enabling the upstream end part of the profile steel to enter a bending degree measuring mechanism;
thirdly, the extending amount of an extending rod of the pushing device is adjusted in the process of the second step;
the method comprises the steps that an illuminating lamp is kept in an open state, meanwhile, an electric control device continuously conducts image recognition on the curvature of the section steel, and when the curvature of the section steel is inconsistent with the preset curvature, the extension amount of an extension rod of a pushing device is adjusted in real time, so that the curvature of the section steel is formed at one time to reach the preset curvature;
and finally, continuously performing the second step and the third step to ensure that the section steel does not need to retreat for one time to be jacked and rebound to a preset bending degree, and continuously performing section steel bending operation.
2. The method of bending section steel according to claim 1, characterized in that: in the third step, the method for adjusting the extending amount of the extending rod of the pushing device comprises the following steps:
carrying out a threshold value test before the section steel curvature measuring device leaves a factory, and presetting the obtained threshold value for binarization processing in a memory of an electric control device;
the first is graying;
in the working process of the section steel bending machine, the electric control device reads an image shot by the camera and grays the image;
secondly, binaryzation is carried out;
thirdly, a circular curve is fitted by utilizing camera calibration parameters and a least square method to obtain the curvature radius R of the bent section steelsI.e. radius R of the arc formed by bending the section steels；
Fourthly, the electric control device controls the advance and retreat amount of the extension rod of the pushing device;
specifically, the electric control device calculates the advance and retreat amount of the extension rod of the pushing device according to a relation formula of the radius and the advance and retreat amount, and controls the extension rod of the pushing device to stretch and contract to accord with the advance and retreat amount;
the relation formula of the radius and the advancing and retreating amount is as follows:
dT is the calculated advancing and retreating amount of the extending rod of the pushing device; rsThe radius of an arc formed by bending steel obtained by visual measurement is r is the radius of the driving wheels, and D is the distance between the center distances of the two driving wheels; dR is RsThe difference obtained by subtracting a predetermined bending radius of the section steel, i.e., a target value of the bending radius of the section steel.
3. The method of bending section steel according to claim 2, characterized in that: the method for carrying out the threshold test before delivery comprises the following steps:
firstly, creating a lighting environment;
building a section steel curvature measuring device, placing section steel at a downstream section steel path, enabling the section steel to penetrate through an opening in a cloth curtain or a plastic curtain, turning on an illuminating lamp, building a real illumination environment during section steel bending operation, and controlling a camera to take pictures in the environment through an electric control device;
secondly, performing threshold value test;
a worker inputs a specific threshold value to the electric control device, and the image shot by the camera is subjected to binarization processing; a worker observes the binarized image through a display screen;
repeating the operation of inputting the threshold value and observing the image, wherein the threshold value input every time is different; through the operation of inputting the threshold value and observing the image for a plurality of times, the worker determines a threshold value capable of obtaining the best binary image and uses the threshold value as a final threshold value, and the final threshold value is stored in a memory of the electric control device to be used for carrying out the binary processing.
Technical Field
The invention relates to the technical field of machining, in particular to a section steel bending technology.
Background
The section steel is a construction material commonly used in various construction scenes of tunnel engineering, bridge engineering, railway engineering and the like at present, the requirements of various construction occasions on the bending degree of the section steel are also various, and the section steel is bent into various shapes and bending degrees by a section steel bending machine. The bending degree refers to the bending degree of the long-strip rolled piece (a profile, a rod and a pipe) in the length direction, and the chord height of the bending in each meter of length is the bending degree in each meter; the ratio of the total chord height to the total length of the total length bend is the total bend. The curvature depends on the radius of a circle where the arc is located, the curvature can be indicated by using the radius of the arc, and the curvature of the section steel is controlled by using the radius of the section steel after the section steel is subjected to nonlinear springback control.
The existing section steel bending machine comprises a workbench, the advancing direction of section steel is used as the downstream direction, a driving device and a plurality of section steel supporting devices are arranged on the workbench at intervals along the direction from the upstream to the downstream, and a working hydraulic cylinder (namely a working oil cylinder) for jacking and bending the section steel is also arranged on the workbench. When the bending machine is used, the section steel is placed on the bending machine and supported by the section steel supporting device, the working oil cylinder tightly supports the section steel, the driving device is started to enable the section steel to move towards the downstream direction, and the section steel is bent to the preset bending degree under the supporting force of the working oil cylinder in the moving process.
And (3) pushing the working oil cylinder to tightly push the section steel and start to calculate the bending degree when the section steel is not bent and deformed, wherein the length of the pushing of the oil cylinder is 10-15 mm (millimeter) each time, the driving device is enabled to rotate forwards or backwards, the section steel is driven to move forwards or backwards, and the operation is repeated until the section steel reaches the required radius. In the whole, the section steel is fed from the upstream end of the table and is fed from the downstream end.
Due to the existence of nonlinear springback characteristics, the condition that the preset bending degree is achieved by one-time bending is very rare, and the bending degree of the section steel can be controlled to the preset target by bending for many times. The prior art lacks a technology for ensuring that the preset curvature is reached by one-time bending, so that the section steel repeatedly moves forward and backward on a section steel bending machine to repeatedly press and bend, the section steel can finally reach the preset curvature, the working efficiency is low, and the energy consumption is obviously improved by repeatedly moving forward, backward and pressing.
When the bending deviation value of the section steels such as H-shaped steel, I-shaped steel, channel steel and the like is measured, a traditional measuring method needs to use a cord which is long enough, two workers respectively press the two ends of the section steel on the same side and pull the cord with force, and the cord is tensioned as far as possible to be used as a chord of the section steel; meanwhile, the third operator determines the position where the maximum bending degree is measured by visual observation using a steel plate ruler, and visually observes the bending type (lateral bending, "S" bending, local bending at the end, and the like) of the whole branch profile, and records the value after measurement as the maximum bending degree value of the branch profile.
The traditional measuring tool and the traditional measuring method have the defects of complex measuring method, poor accuracy of measured data, low precision of the measuring tool, large influence degree of human factors, low measuring efficiency, more needed labor and the like, and the measured deviation value has larger error and can not be suitable for the quality control requirement of the modern section steel production line.
The patent "bending degree measuring device for section steel bending machine" (application number: 201821917879.6) and the patent "bending angle measuring device for section steel bending machine" (application number: 202021048808.4) propose solutions.
The solution provided by the patent 'curvature measuring device for a section steel bending machine' (application number: 201821917879.6) can measure the curvature of section steel in real time, but the service life of the device is short, because the top of a measuring rod of the device is directly contacted with the surface of the section steel, a large friction force can be generated between the measuring rod and the section steel, the friction can cause irreversible damage to the measuring rod, the abrasion of the measuring rod can be caused after a period of use, the accuracy of a measuring result is influenced, and the accuracy of a long-time measuring result cannot be ensured; if the device is replaced frequently, the cost is increased and the time is wasted.
The solution proposed by the patent 'bending angle measuring device of a section steel bending machine' (application number: 202021048808.4) can also solve the problems encountered in the traditional method for measuring the bending degree, but the device also has the phenomenon that the measuring device is in direct contact with the section steel when the bending degree is measured, so that the abrasion phenomenon can occur, and the service life of the measuring device is shortened; in the measuring process, the numerical value on the graduated scale is read manually to carry out manual calculation, and the precision of the result is influenced by manual reading errors in the process; and the manual calculation is slow, and the real-time measurement of the bending degree of the section steel cannot be realized.
Disclosure of Invention
The invention aims to provide a section steel bending method based on visual measurement, which can be used for bending section steel and is beneficial to directly achieving the preset bending degree after the section steel is subjected to one-time compression bending through nonlinear resilience.
In order to achieve the purpose, the section steel bending method based on vision measurement is carried out by using a section steel bending degree measuring device, the section steel bending degree measuring device comprises a section steel bending machine, the section steel bending machine comprises a workbench, the advancing direction of the section steel is taken as the downstream direction, a section steel driving device and a section steel supporting device used for supporting the section steel are arranged on the workbench along an arc line from the upstream direction to the downstream direction, a pushing device is further arranged on the workbench,
the profile steel driving device comprises a positive and negative rotation motor and driving wheels driven by the positive and negative rotation motor, two sets of profile steel driving devices are arranged at intervals, the two sets of profile steel driving devices are symmetrically arranged about the pushing device, the pushing device is provided with an extension rod, and the end part of the extension rod is provided with a pressing shaft which is used for pressing the profile steel on the driving wheels of the two sets of profile steel driving devices; the pushing device is a working hydraulic cylinder or a working electric push rod or a working air cylinder;
a curvature measuring mechanism is arranged in the downstream direction of the workbench and comprises a camera mechanism and an illuminating mechanism;
the profile steel advancing path on the downstream side of the workbench is called a downstream profile steel path, the camera mechanism comprises a portal frame crossing the downstream profile steel path, a camera is arranged at the top of the portal frame, the camera is positioned right above the downstream profile steel path, and the shooting direction of the camera faces downwards;
the lighting mechanism is provided with a plurality of sets of lighting devices, and the lighting devices are dispersedly arranged on two sides of the downstream section steel path; each illuminating mechanism has the same structure and comprises an illuminating bracket, the top end of the illuminating bracket is provided with an illuminating lamp, and the illuminating lamp is higher than the camera;
the illuminating lamp, the camera, the forward and reverse rotating motors of the various steel driving devices and the pushing device are respectively connected with an electric control device through lines, and the electric control device is connected with a display screen;
a first section steel supporting device, a first driving device, a second section steel supporting device, a second driving device and a third section steel supporting device are arranged on a workbench of the section steel bending machine at intervals along an arc line from the upstream to the downstream; the first section steel supporting device and the fourth section steel supporting device are symmetrically arranged around the pushing device, and the second section steel supporting device and the third section steel supporting device are symmetrically arranged around the pushing device; the structural steel supporting devices are identical in structure and respectively comprise a supporting frame, an upper limiting shaft and a lower supporting shaft which are arranged on the supporting frame at intervals up and down, the distance between the upper limiting shaft and the lower supporting shaft is matched with the thickness of the structural steel, and a supporting limiting space is defined by the upper limiting shaft and the lower supporting shaft; the profile steel sequentially penetrates through the various profile steel supporting devices through supporting limiting spaces of the various profile steel supporting devices, the lower supporting shaft is used for supporting the profile steel, and the upper limiting shaft is used for preventing the profile steel from moving up and down in the bending process;
the device also comprises a shell, wherein the shell covers the workbench, the profile steel driving device, the profile steel supporting device, the pushing device and the curvature measuring mechanism;
the upstream end of the shell is provided with an inlet for entering the section steel, the downstream end of the shell is provided with an outlet for sending out the section steel, the outlet and the inlet are respectively provided with a cloth curtain or a plastic curtain for shielding external light, and the cloth curtain or the plastic curtain is provided with an opening for passing the section steel;
the section steel bending method based on visual measurement comprises the following steps:
the first step is feeding; feeding the section steel into the shell from the inlet and penetrating through each section steel supporting device;
secondly, jacking and advancing; the pushing device is controlled by the electric control device to apply a preset jacking force to the profile steel, so that the profile steel is jacked on the driving wheels of the two sets of profile steel driving devices;
starting positive and negative rotating motors of various profile steel driving devices to synchronously operate, driving wheels drive the profile steel to move towards a downstream direction under the action of friction force, and enabling the upstream end part of the profile steel to enter a bending degree measuring mechanism;
thirdly, the extending amount of an extending rod of the pushing device is adjusted in the process of the second step;
the method comprises the steps that an illuminating lamp is kept in an open state, meanwhile, an electric control device continuously conducts image recognition on the curvature of the section steel, and when the curvature of the section steel is inconsistent with the preset curvature, the extension amount of an extension rod of a pushing device is adjusted in real time, so that the curvature of the section steel is formed at one time to reach the preset curvature;
and finally, continuously performing the second step and the third step to ensure that the section steel does not need to retreat for one time to be jacked and rebound to a preset bending degree, and continuously performing section steel bending operation.
In the third step, the method for adjusting the extending amount of the extending rod of the pushing device comprises the following steps:
carrying out a threshold value test before the section steel curvature measuring device leaves a factory, and presetting the obtained threshold value for binarization processing in a memory of an electric control device;
the first is graying;
in the working process of the section steel bending machine, the electric control device reads an image shot by the camera and grays the image;
secondly, binaryzation is carried out;
thirdly, a circular curve is fitted by utilizing camera calibration parameters and a least square method to obtain the curvature radius R of the bent section steelsI.e. radius R of the arc formed by bending the section steels；
Fourthly, the electric control device controls the advance and retreat amount of the extension rod of the pushing device;
specifically, the electric control device calculates the advance and retreat amount of the extension rod of the pushing device according to a relation formula of the radius and the advance and retreat amount, and controls the extension rod of the pushing device to stretch and contract to accord with the advance and retreat amount;
the relation formula of the radius and the advancing and retreating amount is as follows:
dT is the calculated advancing and retreating amount of the extending rod of the pushing device; rsThe radius of an arc formed by bending steel obtained by visual measurement is r is the radius of the driving wheels, and D is the distance between the center distances of the two driving wheels; dR is RsSubtracting a predetermined bending radius of the section steel (i.e., a target value of the bending radius of the section steel) to obtain a difference;
the method for carrying out the threshold test before delivery comprises the following steps:
firstly, creating a lighting environment;
building a section steel curvature measuring device, placing section steel at a downstream section steel path, enabling the section steel to penetrate through an opening in a cloth curtain or a plastic curtain, turning on an illuminating lamp, building a real illumination environment during section steel bending operation, and controlling a camera to take pictures in the environment through an electric control device;
secondly, performing threshold value test;
a worker inputs a specific threshold value to the electric control device, and the image shot by the camera is subjected to binarization processing; a worker observes the binarized image through a display screen;
repeating the operation of inputting the threshold value and observing the image, wherein the threshold value input every time is different; through the operation of inputting the threshold value and observing the image for a plurality of times, the worker determines a threshold value capable of obtaining the best binary image and uses the threshold value as a final threshold value, and the final threshold value is stored in a memory of the electric control device to be used for carrying out the binary processing.
The invention has the following advantages:
the camera is positioned right above the downstream section steel path, the shooting direction of the camera faces downwards, the camera shoots images which are in a top view facing the section steel, the shot images have the best shooting angle compared with other shooting directions, the shot images have the minimum deformation and are most beneficial to image recognition of the bending degree of the section steel.
The profile steel and the pressing shaft are in rolling fit, so that the extending rod of the pushing device can be prevented from being damaged by sliding friction under the action of the pressing force.
The upper limiting shaft is arranged, so that the section steel cannot move up and down and turn over in the bending process, the bending effect is not affected by the up-down turning or movement of the section steel, and the bending quality is improved.
The setting of casing and cloth curtain or plastics curtain, on the one hand guarantee that the bending machine of shaped steel does not receive external debris influence (if there is the foreign matter to get into the bending machine of shaped steel chance and cause the influence to the normal operating of bending machine of shaped steel), on the other hand has reduced external light by a wide margin to measuring environment's influence, makes the light of crookedness measuring mechanism department come from crookedness measuring mechanism's each light basically, guarantees measuring effect.
The arrangement of the universal tripod head is convenient for adjusting the shooting angle of the camera, and particularly, when the field is uneven or needs to be replaced and used, the camera can be adjusted to the optimal shooting angle under various conditions.
The illuminating mechanism forms the effect of a shadowless lamp through a plurality of illuminating lamps, eliminates the shadow in the image shot by the camera, makes the image shot by the camera more convenient for image processing, and improves the accuracy of the image processing result.
By adopting the section steel bending method, the bending degree of the section steel after nonlinear resilience can be measured in real time in the section steel bending process, and the extension amount of the extension rod of the pushing device is adjusted according to the relation between the input condition and the extension amount of the extension rod of the pushing device, so that the section steel can directly reach the preset bending degree through the nonlinear resilience after being bent by one-time pressing, the section steel is prevented from repeatedly advancing and retreating and jacking, the section steel bending working efficiency is greatly improved, the energy consumption consumed during repeatedly advancing and retreating and jacking the section steel is saved, the energy consumption required by the section steel bending is greatly reduced on the whole, and the effects of energy conservation and efficiency improvement are very obvious. The input conditions refer to the characteristics of the section steel curvature measuring device (the radius of the driving wheels and the center distance between the two driving wheels), the section steel curvature (arc radius) after nonlinear springback at present and the preset section steel curvature.
Specifically, according to the invention, through a relation formula of the radius and the advancing and retreating amount, the electric control device can calculate the advancing and retreating amount of the extension rod of the pushing device in real time after obtaining the radius R of the arc formed by bending the section steel through visual measurement, so that the extension of the extension rod of the pushing device is correspondingly controlled. The invention can automatically control the extension amount of the extension rod of the pushing device according to the result of the vision measurement, so that the extension amount of the extension rod of the pushing device is matched with the curvature radius of the profile steel after being pressed and rebounded, thereby realizing that the profile steel does not need to be repeatedly advanced and retreated, and the curvature radius obtained after the profile steel is naturally rebounded is just the preset curvature radius after being pressed once and passes through a profile steel bending machine, thereby greatly improving the working efficiency, avoiding the energy consumption waste caused by repeatedly pressing the same section of profile steel, and having very obvious energy-saving effect and the effect of improving the processing efficiency.
Drawings
FIG. 1 is a schematic perspective view of a section steel curvature measuring device with a housing removed;
FIG. 2 is a plan view of the section steel bending degree measuring apparatus;
FIG. 3 is a schematic perspective view of a section steel bending degree measuring apparatus;
FIG. 4 is a schematic perspective view of a device for measuring the degree of bending of a section steel at another angle;
fig. 5 is a schematic diagram of solving A, B and R.
Detailed Description
As shown in fig. 1 to 5, the section steel bending method based on visual measurement of the present invention is performed using a section steel bending degree measuring apparatus including a section steel bending machine including a table 1, the method comprises the following steps that the advancing direction of profile steel 22 is taken as the downstream direction, a profile steel driving device and a profile steel supporting device used for supporting the profile steel 22 are arranged on a workbench 1 along an arc line from the upstream to the downstream direction, a pushing device is further arranged on the workbench 1, the profile steel driving device comprises a forward and reverse rotating motor 2 and a driving wheel 3 (or called a driving rotating shaft) driven by the forward and reverse rotating motor 2, two sets of profile steel driving devices are arranged at intervals, the two sets of profile steel driving devices are symmetrically arranged relative to the pushing device 5, the pushing device 5 is provided with an extension rod 4, the end part of the extension rod 4 is provided with a pressing shaft 6, and the pressing shaft 6 is used for pressing the profile steel 22 on the driving wheels 3 of the two sets of profile steel driving devices; the pushing device 5 is a working hydraulic cylinder or a working electric push rod or a working air cylinder;
a curvature measuring mechanism is arranged in the downstream direction of the workbench 1 and comprises a camera mechanism and an illuminating mechanism;
the advancing path of the section steel 22 at the downstream side of the workbench 1 is called a downstream section steel path, the camera mechanism comprises a portal frame 7 crossing the downstream section steel path, the top of the portal frame 7 is provided with a camera 8, the camera 8 is positioned right above the downstream section steel path, and the shooting direction of the camera is downward;
the lighting mechanism is provided with a plurality of sets of lighting devices, and the lighting devices are dispersedly arranged on two sides of the downstream section steel path; each illuminating mechanism has the same structure and comprises an illuminating bracket 9, the top end of the illuminating bracket 9 is provided with an illuminating lamp 10 (preferably a strip-shaped illuminating lamp 10), and the illuminating lamp 10 is higher than the camera 8; the lighting mechanism forms the effect of a shadowless lamp through a plurality of lighting lamps 10, eliminates the shadow in the image shot by the camera, makes the image shot by the camera more convenient for image processing, and improves the accuracy of the image processing result.
The illuminating lamp 10, the camera 8, the forward and reverse rotating motor 2 of each type of steel driving device and the pushing device 5 are respectively connected with an electric control device 11 through lines, and the electric control device 11 is connected with a display screen. The display screen is conventional and not shown. The electric control device 11 is a PLC or an industrial control computer.
The camera 8 is positioned right above the downstream section steel path and the shooting direction thereof is directed downward, and the arrangement is such that the image shot by the camera 8 is a top view facing the section steel 22, the shot image has the best shooting angle compared with other shooting directions, the shot image has the least amount of deformation and is most beneficial for image recognition of the section steel curvature.
The profile steel 22 is in rolling fit with the pressing shaft 6, so that the extension rod 4 of the pushing device 5 can be prevented from being damaged by sliding friction under the action of the pressing force.
A first section steel supporting device, a first driving device, a second section steel supporting device, a second driving device and a third section steel supporting device are arranged on a workbench 1 of the section steel bending machine at intervals along an arc line from the upstream to the downstream; the first section steel supporting device and the fourth section steel supporting device are symmetrically arranged around the pushing device 5, and the second section steel supporting device and the third section steel supporting device are symmetrically arranged around the pushing device 5; the structural steel supporting devices are identical in structure and respectively comprise a supporting frame 12 and an upper limiting shaft 13 and a lower supporting shaft 14 which are arranged on the supporting frame 12 at intervals up and down, the distance between the upper limiting shaft 13 and the lower supporting shaft 14 is matched with the thickness of the structural steel 22, and a supporting limiting space is defined by the upper limiting shaft 13 and the lower supporting shaft 14; the section steel 22 sequentially penetrates through the section steel supporting devices through supporting limiting spaces of the section steel supporting devices, the lower supporting shaft 14 is used for supporting the section steel 22, the upper limiting shaft 13 is used for limiting the section steel 22, and the section steel 22 is prevented from moving up and down in the bending process.
The upper limiting shaft 13 is arranged, so that the section steel 22 cannot move up and down and turn over in the bending process, the bending effect is not affected by the up-down turning or movement of the section steel 22, and the bending quality is improved.
The bending device comprises a workbench 1, a section steel driving device, a section steel supporting device, a pushing device 5 and a bending degree measuring mechanism, and is characterized by further comprising a shell 15, wherein the shell 15 covers the workbench 1, the section steel driving device, the section steel supporting device, the pushing device 5 and the bending degree measuring mechanism;
an inlet 16 for the profile steel 22 to enter is arranged at the upstream end of the shell 15, an outlet 17 for the profile steel 22 to be sent out is arranged at the downstream end of the shell 15, a cloth curtain or a plastic curtain for shielding external light is respectively arranged at the outlet 17 and the inlet 16, and an opening for the profile steel 22 to pass through is arranged on the cloth curtain or the plastic curtain.
The setting of casing 15 and cloth curtain or plastics curtain, on the one hand guarantee that the bending machine of shaped steel does not receive external debris influence (if there is the foreign matter to get into the bending machine of shaped steel chance and cause the influence to the normal operating of bending machine of shaped steel), on the other hand has reduced external light by a wide margin to measuring environment's influence, makes the light of crookedness measuring mechanism department come from crookedness measuring mechanism's each light 10 basically, guarantees measuring effect. The cloth or plastic curtain and its opening are conventional devices and conventional structures, not shown.
The illumination support 9 and the portal frame 7 both comprise telescopic support legs for adjusting the height, and the shell 15 is provided with an observation window 19 for observing the camera mechanism; the camera 8 is arranged at the top of the portal frame 7 through a universal cradle head; the electric control device 11 is mounted on the table 1, and a movable door 20 for operating the electric control device 11 is mounted on the housing 15 corresponding to the electric control device 11. The movable door 20 is provided with a handle 21.
The telescopic support legs, the universal holder and the movable door 20 are all conventional devices, the specific structure is not described again, and the telescopic support legs are not shown in the figure. The arrangement of the universal tripod head is convenient for adjusting the shooting angle of the camera 8, and particularly, when the field is uneven or needs to be replaced, the camera 8 can be adjusted to the best shooting angle under various conditions.
The telescopic supporting legs are conventional technologies, the walking stick and the camera 8 tripod are particularly widely applied, and the specific structure is not described in detail.
The section steel bending method based on visual measurement is carried out according to the following steps:
the first step is feeding; the section steel 22 is sent into the shell 15 from the inlet 16 and passes through a supporting and limiting space surrounded by the upper limiting shaft 13 and the lower supporting shaft 14 of each section steel supporting device;
secondly, jacking and advancing; the pushing device 5 is controlled by the electric control device 11 to apply preset jacking pressure to the section steel 22 through the pressing shaft 6, so that the section steel 22 is jacked on the driving wheels 3 of the two sets of section steel driving devices;
starting positive and negative rotating motors 2 of various profile steel driving devices to synchronously run, driving wheels 3 drive profile steel 22 to move towards the downstream direction under the action of friction force, and the upstream end part of the profile steel 22 enters a bending degree measuring mechanism;
thirdly, the extending amount of an extending rod 4 of the pushing device 5 is adjusted in the process of the second step;
the method specifically comprises the steps that an illuminating lamp 10 is kept in an opening state, meanwhile, an electric control device 11 continuously conducts image recognition on the bending degree of the section steel, and when the bending degree of the section steel is inconsistent with the preset bending degree, the extending amount of an extending rod 4 of a pushing device 5 is adjusted in real time, so that the bending degree of the section steel 22 is formed at one time to reach the preset bending degree;
the bending section steel 22 is pressed by the extending rod 4 of the pushing device 5 through the pressing shaft 6, nonlinear rebound occurs after the bent section steel 22 leaves the driving wheel 3 on the downstream side, and then the camera 8 shoots images, and a certain time interval is provided, namely, after the third step is to adjust the extending amount of the extending rod 4 of the pushing device 5, the curvature of the subsequent section steel section is ensured, and the curvature of the section steel section (section steel part) which is reflected by the shot images is not ensured. For the section steel with unqualified bending degree of the section steel head section when the machine is just started, two processing modes are provided. Efficiency is emphasized, the direct continuous operation can be realized, and the part with unqualified curvature is cut off; the other mode is that after the extension amount of the extension rod 4 of the pushing device 5 is adjusted in the third step, the electric control device 11 controls the forward and reverse rotation motor to rotate reversely, so that the part of the section steel 22 with unqualified bending degree backs to the upstream side of the pushing device 5, and then the electric control device 11 controls the forward and reverse rotation motor to rotate forwardly, so that the part of the section steel 22 with unqualified bending degree passes through the pushing device 5 again; since the extension amount of the extension rod 4 of the pushing device 5 is corrected, the part of the section steel 22 with unqualified original curvature can be corrected until the curvature reaches a preset value.
And finally, continuously performing the second step and the third step to ensure that the section steel 22 does not need to retreat for one time to be pressed and rebounded to the preset bending degree, and continuously performing the section steel bending operation.
In the third step, the method for adjusting the extending amount of the extending rod 4 of the pushing device 5 comprises the following steps:
carrying out a threshold test before the section steel curvature measuring device leaves a factory, and presetting the obtained threshold for binarization processing in a memory of the electric control device 11;
the first is graying; image graying is a conventional technique and will not be described in detail.
In the working process of the section steel bending machine, the electric control device 11 reads an image shot by the camera 8 and grays the image;
the graying treatment can eliminate the color influence factor and simplify the subsequent image processing and identification work.
Secondly, binaryzation is carried out; the image binarization is a conventional technique and is not described in detail.
Thirdly, the curvature radius R of the bent section steel 22 is obtained by utilizing the calibration parameters of the camera 8 and the least square method to fit a circular curvesI.e. radius R of the arc formed by bending the section steel 22s；
Fourthly, the electric control device 11 controls the advance and retreat amount of the extension rod 4 of the pushing device 5;
specifically, the electric control device 11 calculates the advance and retreat amount of the extension rod 4 of the pushing device 5 according to a relation formula of the radius and the advance and retreat amount, and controls the extension rod 4 of the pushing device 5 to stretch and contract to accord with the advance and retreat amount;
the relation formula of the radius and the advancing and retreating amount is as follows:
dT is the calculated advancing and retreating amount of the extension rod 4 of the pushing device 5; rsThe radius of an arc formed by bending steel obtained by visual measurement is r is the radius of the driving wheels 3, and D is the distance between the center distances of the two driving wheels 3; dR is RsA difference obtained by subtracting a predetermined bending radius of the section steel 22 (i.e., a target value of the bending radius of the section steel 22);
by the relation formula of the radius and the advance and retreat amount, the electric control device 11 obtains the radius R of the arc formed by bending the section steel 22 through visual measurementsAnd then, the advancing and retreating amount of the extension rod 4 of the pushing device 5 can be calculated in real time, so that the extension of the extension rod 4 of the pushing device 5 is correspondingly controlled. The invention can automatically control the extension amount of the extension rod 4 of the pushing device 5 according to the result of visual measurement, so that the extension amount of the extension rod 4 of the pushing device 5 is matched with the curvature radius of the section steel 22 after being pressed and rebounded, thereby realizing no need of repeatedly advancing and retreating the section steel 22, ensuring that the curvature radius obtained after the section steel 22 is naturally rebounded is just the preset curvature radius (in the normal radius fluctuation range) after being pressed once and passes through a section steel bending machine, greatly improving the working efficiency, avoiding the energy consumption waste caused by repeatedly pressing the same section of section steel 22, and having very obvious energy-saving effect and the effect of improving the processing efficiency.
The method for carrying out the threshold test before delivery comprises the following steps:
firstly, creating a lighting environment;
building a section steel curvature measuring device, placing section steel 22 at the path of downstream section steel, enabling the section steel 22 to penetrate through an opening in a cloth curtain or a plastic curtain, opening an illuminating lamp 10, building a real illumination environment during section steel bending operation, and controlling a camera 8 to take a picture in the environment through an electric control device 11;
secondly, performing threshold value test;
the staff inputs a specific threshold value to the electric control device 11, and carries out binarization processing on the image shot by the camera 8; a worker observes the binarized image through a display screen;
repeating the operation of inputting the threshold value and observing the image, wherein the threshold value input every time is different; by inputting the threshold value and observing the image for a plurality of times, the worker determines a threshold value that enables the best binarized image to be obtained and uses the threshold value as a final threshold value, and stores the final threshold value in the memory of the electronic control device 11 for binarization processing.
When observing the image, the staff selects the optimal threshold value according to the following principle:
1. portions of the profile are to remain bright (i.e., whiter, better), and the complete continuity of the profile is to be maintained;
2. the larger the difference in brightness between the outline and the portion other than the outline, the better, that is, the darker the portion other than the outline (i.e., the darker the portion, the better).
The third step of the method for adjusting the extension amount of the extension rod 4 of the pushing device 5 is to utilize a camera 8 to calibrate parameters and a least square method to fit a circular curve to obtain the bending degree R of the section steel, wherein the camera 8 calibrates parameters comprising internal parameters and external parameters of a camera, and the internal parameters are parameters of the camera and are obtained by the camera; the external parameters are measured and determined by staff before the camera 8 is installed and used, and are input into the electric control device.
The specific method and the principle in this embodiment are as follows: the shape of the section steel 22 in the image taken by the camera 8 is an arc shape having two concentric contours, an outer contour and an inner contour, respectively, the outermost contour and the innermost contour, where needed.
The chord lengths corresponding to the innermost layer contour and the outermost layer contour are different, and the arc corresponding to the maximum chord length is found by utilizing an interception method and is the outermost layer contour.
As shown in fig. 5, the least squares fit circular curve is: r2＝(x-A)2+(y-B)2；
Namely R2＝x2-2Ax+A2+y2-2By+B2；
Let a ═ 2A, B ═ 2B, c ═ A2+B2－R2Obtaining another form of the circular arc curve equation:
x2+y2+ ax + by + c is 0, which is formula one, and hereinafter referred to as "formula (1)";
contour point set (X) for fitting circular curvei,Yi) The distance d from a point in i e (1,2,3 … N) to the center of the circle (A, B)i：
Then point (X)i,Yi) The square of the distance to the fitted arc is:
let Q (a, b, c) be the set of contour points (X)i,Yi) δ for all points in i ∈ (1,2,3 … N)iHas a sum of squares of
Then Q (a, b, c) calculates the partial derivatives of a, b and c, and the partial derivatives are equal to 0, thus obtaining the minimum value point.
This is formula two; hereinafter abbreviated as formula (2);
this is formula three, hereinafter referred to as formula (3);
this is formula four, hereinafter referred to as formula (4);
solving the system of equations consisting of equation (2), equation (3) and equation (4) can yield:
wherein the content of the first and second substances,
an estimated fit of A, B and R is thus obtained:
the radius R of the fitted arc is a pixel value and needs to be converted into an actual value Rs. The conversion is carried out by adopting a proportion method, and the conversion formula is as follows:
Rsr × L × 2/(x + y); the scaling method is a conventional technique for mapping and converting pixel values (i.e., the number of pixels) to actual (length) values in image processing, and the principle is that the pixel values of lines (contours) in an image have a proportional relationship with the actual values, and details are not described.
Wherein, L is the actual edge length value of a grid (the grids are all square) on a square chessboard used in calibrating the internal and external parameters of the camera, x is the pixel value of a grid on the x direction of the calibration board, and y is the pixel value of a grid on the y direction of the calibration board. The x-direction pixel value and the y-direction pixel value of one grid on the calibration board are theoretically equal, but there is a slight difference due to camera distortion. R is L2/(x + y) ═ R is L/[ (x + y)/2], the average value of (x + y) is taken in the conversion formula of the proportional method of the invention, and the invention has certain function of neutralizing the distortion of the camera, and the result is more accurate.
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