CN117754111B - Friction stir welding system and control method - Google Patents
Friction stir welding system and control method Download PDFInfo
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Abstract
The application discloses a friction stir welding system and a control method, wherein the friction stir welding system comprises a tool apron, a friction stir welding head and an infrared imaging instrument are arranged on the tool apron, and the working end of the infrared imaging instrument is aligned with the friction stir welding head; the welding system further comprises a controller, and the controller is electrically connected with the infrared imager; the application also discloses a control method of the welding system, which comprises the steps of firstly obtaining a standard thermal infrared image and a comparison thermal infrared image, selecting a comparison temperature value, then respectively obtaining a standard distribution curve graph and a comparison distribution curve graph, and judging whether the actual welding temperature reaches the standard or not through comparing the standard distribution curve graph and the comparison curve graph; finally, generating a corresponding control instruction according to whether the actual welding temperature reaches the standard or not, and realizing control of the welding process; compared with the prior art, the application can judge whether the actual welding temperature meets the requirement or not through the comparison of the temperature curves, and further generate corresponding control instructions, thereby realizing effective control of the temperature and improving the welding quality.
Description
Technical Field
The application relates to the technical field of welding equipment, in particular to a friction stir welding system and a control method.
Background
Friction stir welding is to utilize heat generated by friction stir between a welding tool rotating at a high speed and a workpiece to locally melt a welded material, and when the welding tool moves forwards along a welding interface, the plasticized material flows from the front part to the rear part of the welding tool under the action of the rotation friction stir force of the welding tool, and a compact solid-phase welding seam is formed under the extrusion of the welding tool;
The welding temperature is an important control parameter in the friction stir welding working process, and the temperature is generally monitored by an infrared imager or a temperature sensor in the prior art, but the monitoring capability of the temperature is limited in the mode, and the control capability of the welding temperature is limited.
Disclosure of Invention
The application mainly aims to provide a friction stir welding system and a control method, and aims to solve the defect of poor controllability of welding temperature in the prior art.
The application realizes the aim through the following technical scheme:
a friction stir welding system comprising a tool holder;
The friction stir welding head is rotatably arranged on the tool apron;
the infrared imaging instrument is arranged on the tool apron; the working end of the infrared imaging instrument is opposite to the friction stir welding joint;
And the controller is electrically connected with the infrared imager.
Optionally, the controller includes a data acquisition module, where the data acquisition module is configured to acquire a standard thermal infrared image and a comparison thermal infrared image, and select a comparison temperature value;
the parameter extraction module is used for acquiring a standard distribution curve graph on the standard thermal infrared image according to the comparison temperature value;
acquiring a comparison distribution curve graph on the comparison thermal infrared image according to the comparison temperature value;
The comparison module is used for comparing the standard distribution curve graph with the comparison distribution curve graph and judging whether the actual welding temperature meets the requirement;
and the control module is used for generating a control command according to the actual welding temperature and adjusting the rotating speed of the friction stir welding head according to the control command.
Correspondingly, the application also discloses a control method of the friction stir welding system, which comprises the following steps:
Acquiring a standard thermal infrared image and a comparison thermal infrared image, and selecting a comparison temperature value;
Acquiring a standard distribution curve graph on the standard thermal infrared image according to the comparison temperature value;
acquiring a comparison distribution curve graph on the comparison thermal infrared image according to the comparison temperature value;
comparing the standard distribution curve graph with the comparison distribution curve graph, and judging whether the actual welding temperature meets the requirement;
And generating a control command according to the actual welding temperature, and adjusting the rotating speed of the friction stir welding head according to the control command.
Optionally, extracting a standard distribution curve graph on the standard thermal infrared image according to the comparison temperature value, including the following steps:
Invoking a standard thermal infrared image;
Randomly selecting a plurality of standard characteristic points on the standard thermal infrared image according to the comparison temperature value;
and smoothing and connecting the standard characteristic points in series to obtain a standard distribution curve graph.
Optionally, the method for obtaining the comparison temperature contour map according to the comparison thermal infrared image comprises the following steps:
calling and comparing the thermal infrared images;
Randomly selecting a plurality of comparison characteristic points on the comparison thermal infrared image according to the comparison temperature value;
And smoothly connecting the comparison characteristic points in series to obtain a comparison distribution curve graph.
Optionally, comparing the standard distribution graph and the alignment distribution graph includes the steps of:
Establishing a standard polar coordinate system;
Placing the standard distribution graph and the comparison distribution graph into the standard polar coordinate system;
randomly establishing a plurality of screening lines in the standard polar coordinate system, taking the intersection points of the screening lines and the standard distribution curve graph as standard points, and taking the intersection points of the screening lines and the comparison distribution curve graph as comparison points;
Obtaining standard polar coordinates (R, theta) m of each standard point and comparison polar coordinates (R, alpha) n of each comparison point; wherein m represents the number of the standard point and n represents the number of the comparison point;
Judging whether the comparison distribution curve graph deviates or not and the deviation direction according to the standard polar coordinates and the comparison polar coordinates;
optionally, determining whether the alignment distribution graph is offset and the offset direction according to the standard polar coordinates and the alignment polar coordinates includes the following steps:
Obtaining a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates according to the screening line, wherein the mutually paired standard polar coordinates and comparison polar coordinates are positioned on the same screening line;
The paired standard polar coordinates and the paired comparison polar coordinates meet R < R, and the fact that the comparison point moves outwards is judged; if R > R is satisfied, judging that the comparison point moves inwards; if r=r, then determining that the comparison point is not shifted;
Counting the deviation condition of each comparison point, if the number of the comparison points with the outward movement is the largest, judging that the comparison distribution curve graph is outward moved, and if the number of the comparison points with the inward movement is the largest, judging that the comparison distribution curve graph is inward moved; if the comparison points which do not deviate are the most, the comparison distribution curve graph is judged to not deviate.
Optionally, determining whether the alignment distribution graph is offset and the offset direction according to the standard polar coordinates and the alignment polar coordinates includes the following steps:
obtaining a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates according to the screening lines, wherein the mutually paired standard polar coordinates and comparison polar coordinates belong to the same screening line and the same comparison temperature value;
setting standard deviation A, and calculating deviation a of each comparison point;
if a is less than or equal to A, judging that the comparison point does not deviate;
If a is more than A, and the paired standard polar coordinates and the paired comparison polar coordinates meet R < R, judging that the comparison point moves outwards; otherwise, judging that the comparison point moves inwards;
Counting the deviation condition of each comparison point, if the number of the comparison points with the outward movement is the largest, judging that the comparison distribution curve graph is outward moved, and if the number of the comparison points with the inward movement is the largest, judging that the comparison distribution curve graph is inward moved; if the comparison points which do not deviate are the most, the comparison distribution curve graph is judged to not deviate.
Alternatively, the degree of deviation a is expressed as
Optionally, a control command is generated according to the actual welding temperature, and the rotation speed of the friction stir welding head is adjusted according to the control command, including the following steps:
if the comparison distribution graph is shifted outwards and is not shifted, judging that the actual welding temperature meets the requirement, and generating no control instruction;
if the comparison distribution graph moves outwards, judging that the actual welding temperature is too high, and generating a control instruction for reducing the rotating speed;
if the comparison distribution graph moves inwards, the actual welding temperature is judged to be too low, and a control command for improving the rotating speed is generated.
Compared with the prior art, the application has the following beneficial effects:
The application comprises a tool apron, wherein a friction stir welding head is arranged on the tool apron, and an infrared imaging instrument is also arranged on the tool apron, and the working end of the infrared imaging instrument is opposite to the friction stir welding head; simultaneously, the welding system further comprises a controller, and the controller is electrically connected with the infrared imager;
Correspondingly, the application also discloses a control method based on the welding system, which comprises the steps of firstly obtaining a standard thermal infrared image and a comparison thermal infrared image, selecting a comparison temperature value, then respectively obtaining a standard distribution curve graph and a comparison distribution curve graph according to the comparison temperature value, the standard thermal infrared image and the comparison thermal infrared image, and judging whether the actual welding temperature reaches the standard or not through comparing the standard distribution curve graph and the comparison curve graph; finally, generating a corresponding control instruction according to whether the actual welding temperature reaches the standard or not, and realizing control of the welding process;
Compared with the prior art, the temperature distribution curve graph in the welding process is obtained through the thermal infrared image, namely the same temperature point is connected through the curve, compared with the thermal infrared image, the temperature distribution curve graph is not distinguished through the color, but is represented by the line graph similar to the contour graph, so that the distribution condition of graduation can be more accurately and clearly marked, further the later comparison process is simplified, the comparison effect is better, and the improvement of the control degree of the welding temperature is facilitated;
And secondly, the standard distribution curve graph selects a corresponding temperature curve graph with optimal welding quality, and whether the temperature distribution is reasonable can be rapidly judged through comparison of the front and rear times, so that whether the distribution change of the temperature is in a controllable range is rapidly judged, and a corresponding control instruction is generated.
Drawings
FIG. 1 is a schematic diagram of a friction stir welding system according to embodiment 1 of the present application;
FIG. 2 is a schematic diagram of a controller structure;
FIG. 3 is a flow chart of a control method;
FIG. 4 is a schematic diagram of standard point and comparative point acquisition;
reference numerals: the device comprises a cutter holder 1, a friction stir welding head 2, a 3-infrared imager, a 4-controller, a 401-data acquisition module, a 402-parameter extraction module, a 403-comparison module and a 404-control module;
The achievement of the objects, functional features and advantages of the present application will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that all directional indicators (such as up, down, left, right, front, and rear … …) in the embodiments of the present invention are merely used to explain the relative positional relationship, movement, etc. between the components in a particular posture (as shown in the drawings), and if the particular posture is changed, the directional indicator is changed accordingly.
In the present invention, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and/or" appearing throughout the text includes three parallel schemes, taking "robot coordinate system and/or m" as an example, including a robot coordinate system scheme, or an m scheme, or a scheme in which the robot coordinate system and m are satisfied simultaneously. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.
Example 1
Referring to fig. 1 and 2, this embodiment is an alternative embodiment of the present application, which discloses a friction stir welding system, comprising a tool holder, on which a friction stir welding head is rotatably arranged, the tool holder being connected to an external driving assembly;
An infrared imager is further arranged on the outer surface of the tool apron, and the working end of the infrared imager is opposite to the friction stir welding head, so that a thermal infrared image can be acquired more accurately, and the control precision is improved; meanwhile, it is pointed out that 2-3 infrared imagers can be arranged, and each infrared imager is uniformly arranged around the rotation axis of the friction stir welding head;
In the actual working process, after intercepting and splicing each infrared imager according to the need, 360-degree dead-angle-free thermal infrared images around the axis of the friction stir welding joint can be obtained, namely if two infrared imagers are used, the images of the shielding area on the back of the friction stir welding joint are removed according to an angle of 180 degrees, and the front images of the two friction stir welding joints are spliced with each other; if 3 are selected, cutting according to an angle of 120 degrees;
By the mode, the accuracy of the thermal infrared image of the shielding area of the friction stir welding joint can be effectively improved, and the control accuracy of temperature is further improved;
the welding system further comprises a controller, wherein a data acquisition module, a parameter extraction module, a comparison module and a control module are arranged in the controller, and the data acquisition module acquires comparison thermal infrared images shot by an infrared imager on one hand and also needs to fetch pre-stored standard thermal infrared images from a database; meanwhile, staff sets a comparison temperature through the data acquisition module;
The output end of the data acquisition module is also connected with a parameter extraction module, the parameter extraction module respectively extracts a standard distribution curve and a comparison distribution curve according to the received data, the extracted standard distribution curve and the comparison distribution curve are transmitted to a comparison module, and the comparison module is used for comparing the standard distribution curve and the comparison distribution curve, judging whether the actual welding temperature meets the requirement or not and generating a control instruction;
The generated control instruction is uploaded to a control module, and the control module adjusts the rotating speed of the friction stir welding head according to the control instruction, so as to control the heat generated by friction stir heating, thereby realizing rapid control of welding temperature;
Embodiment 2
Referring to fig. 3, as a further alternative embodiment of the present application, the present embodiment discloses a control method based on the above friction stir welding system, comprising the steps of:
S1, acquiring a standard thermal infrared image and a comparison thermal infrared image, and selecting a comparison temperature value;
the standard thermal infrared images are prestored in a database, and the standard thermal infrared images are derived from historical data, namely thermal imaging images of products with the best processing quality in the same type of processed products;
therefore, when the standard thermal infrared image is selected, only the thermal infrared image of the same type of product can be selected as the standard thermal infrared image;
the comparison thermal infrared image is taken by an infrared imager, and the comparison thermal infrared image can be used as a standard thermal infrared image for processing parts in the next batch;
Then, the staff sets a comparison temperature value, and it should be noted that the comparison temperature value generally selects the best welding temperature, and a plurality of comparison temperature values can be selected, but 1-2 comparison temperature values are preferably selected based on the complexity consideration of later calculation;
s2, acquiring a standard distribution curve graph on the standard thermal infrared image according to the comparison temperature value;
s21, calling a standard thermal infrared image;
S22, randomly selecting a plurality of standard feature points on the standard thermal infrared image according to the comparison temperature value;
after the standard thermal infrared image is acquired, automatically acquiring the temperature of each region by reading the color of the standard thermal infrared image, and simultaneously selecting a plurality of standard characteristic points on the standard thermal infrared image by combining with the comparison temperature value;
It should be noted that, the temperature value represented by each standard feature point is equal to the comparison temperature value, and each standard feature point is automatically selected by a computer, and the number of the standard feature points is not less than 100;
S23, smoothing and connecting the standard characteristic points in series to obtain a standard distribution curve graph.
After each standard characteristic point is selected, generating a curve by a fitting operation mode, wherein the curve is used for smoothly connecting all the selected standard characteristic points in series, the curve is a standard distribution curve, the number of the standard distribution curves is the same as that of the comparison temperature values, and each standard distribution curve forms a standard distribution curve graph;
s3, acquiring a comparison distribution curve graph on the comparison thermal infrared image according to the comparison temperature value;
s31, calling and comparing the thermal infrared images;
The comparison thermal infrared image processed in the step S1 is obtained, namely, if a plurality of infrared imagers are arranged, the thermal infrared image after interception and splicing is obtained;
S32, randomly selecting a plurality of comparison characteristic points on the comparison thermal infrared image according to the comparison temperature value;
After the comparison thermal infrared image is obtained, the temperature of each region is automatically obtained by reading the color of the comparison thermal infrared image, and a plurality of comparison characteristic points are selected on the comparison thermal infrared image by combining the comparison temperature values;
it should be noted that, the temperature value represented by each comparison characteristic point is equal to the comparison temperature value, and meanwhile, each comparison characteristic point is automatically selected by a computer, and the number of the comparison characteristic points is not less than 100;
s33, smoothing and connecting the comparison characteristic points in series to obtain a comparison distribution curve graph.
After each comparison characteristic point is selected, generating a curve by means of fitting operation, wherein the curve is formed by smoothly connecting all the selected comparison characteristic points in series, namely, the number of the comparison characteristic points is the same as that of comparison temperature values, and each comparison characteristic point forms a comparison distribution curve graph;
S4, comparing the standard distribution curve graph with the comparison distribution curve graph, and judging whether the actual welding temperature meets the requirement;
S41, establishing a standard polar coordinate system;
it should be noted that, whether the standard thermal infrared image or the comparative thermal infrared image has a partial shadow area, the shadow area is a friction stir welding joint, because of the more accurate calibration image, the center of the shadow area is taken as the origin, and a standard polar coordinate system is established by taking the origin;
S42, placing the standard distribution curve graph and the comparison distribution curve graph into the standard polar coordinate system;
Because the standard distribution curve graph and the comparison distribution curve graph are acquired based on corresponding thermal infrared images, shadow areas matched with the friction stir welding head are arranged on the standard distribution curve graph and the comparison distribution curve graph, the origin of the shadow areas is used as an alignment point, and the alignment point is overlapped with the origin of the standard polar coordinate system; simultaneously correcting the standard distribution curve graph and the comparison distribution curve graph by combining an image acquisition mode, so that the standard distribution curve graph and the comparison distribution curve graph are placed into the standard polar coordinate system;
S43, randomly establishing a plurality of screening lines in the standard polar coordinate system, taking the intersection points of the screening lines and the standard distribution curve graph as standard points, and taking the intersection points of the screening lines and the comparison distribution curve graph as comparison points;
And automatically generating a plurality of screening lines in the standard polar coordinate system, wherein each screening line passes through the origin of the standard polar coordinate system, and meanwhile, in order to improve the control precision, each screening line is randomly arranged around the origin of the standard polar coordinate system.
S44, obtaining standard polar coordinates (R, theta) m of each standard point and comparison polar coordinates (R, alpha) n of each comparison point; wherein m represents the number of the standard point and n represents the number of the comparison point;
As shown in fig. 4, the dashed line in the figure represents a standard distribution curve, and the implementation represents an alignment distribution curve, so that after the screening lines are determined, each screening line must intersect with the standard distribution curve and the alignment distribution curve respectively, if one comparison temperature value is selected, each screening line has two intersection points, and if two comparison temperature values are selected, 4 intersection points must exist;
The intersection points of the screening lines and the standard distribution curve graph are standard points, polar coordinates of the standard points are respectively obtained to serve as standard polar coordinates, the expression of the standard polar coordinates is (R, theta) m, wherein m represents the reference sign R of the standard points, the polar diameter is represented by the reference sign R, and the polar angle is represented by the theta;
Similarly, the intersection point of each screening line and each comparison distribution graph is a comparison point, the polar coordinates of each comparison point are respectively obtained to serve as comparison polar coordinates, the expression of the standard polar coordinates is (r, alpha) n, wherein n represents the reference numeral r of the standard point, the polar diameter is represented by alpha, and the polar angle is represented by alpha;
S45, judging whether the comparison distribution curve graph deviates or not and the deviation direction according to the standard polar coordinates and the comparison polar coordinates;
s451, acquiring a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates according to the screening line, wherein the mutually paired standard polar coordinates and comparison polar coordinates are positioned on the same screening line;
Because a standard point and a comparison point are necessarily arranged on one screening line, the standard point and the comparison point which belong to the same comparison temperature value are paired, and therefore a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates are obtained;
S452, judging that the paired standard polar coordinates and the paired comparison polar coordinates meet R < R, and outwards moving the comparison point; if R > R is satisfied, judging that the comparison point moves inwards; if r=r, then determining that the comparison point is not shifted;
The standard point and the comparison point on the same sieving line necessarily have the same polar angle, i.e., θ=α; therefore, polar angles do not need to be compared;
If the comparison point deviates to the original point side deviating from the standard polar coordinate, the standard polar coordinate and the comparison polar coordinate are inevitably caused to meet R < R, and the comparison point is judged to deviate;
If the comparison point deviates to the original point side of the standard polar coordinate, the standard polar coordinate and the comparison polar coordinate are inevitably caused to meet R & gtr, and the comparison point is judged to move inwards at the moment;
if the comparison point does not deviate, R=r exists, and then the comparison point is judged not to move;
S453, counting the deviation situation of each comparison point, if the number of the comparison points with the outward movement is the largest, judging that the comparison distribution curve graph is outward moved, and if the number of the comparison points with the inward movement is the largest, judging that the comparison distribution curve is inward moved; if the comparison points which do not deviate are the most, the comparison distribution curve graph is judged to not deviate.
After the deviation condition of each comparison point is judged, counting the number of the comparison points which are moved outwards, counting the number of the comparison points which are moved inwards and the number of the comparison points which are not moved;
If the outward moving comparison point is the most, the comparison distribution curve graph is judged to be outward moved, and if the inward moving comparison point is the most, the comparison distribution curve graph is judged to be inward moved; if the comparison points which do not deviate are the most, judging that the comparison distribution curve graph does not deviate;
S5, generating a control command according to the actual welding temperature, and adjusting the rotating speed of the friction stir welding head according to the control command;
S51, if the comparison distribution graph is shifted outwards and is not shifted, judging that the actual welding temperature meets the requirement, and generating no control instruction;
According to the determination result of step S453, if it is determined that the comparative distribution graph is shifted outward and not shifted, it is determined that the actual welding temperature meets the requirement, and no control instruction is generated;
S52, if the comparison distribution graph moves outwards, judging that the actual welding temperature is too high, and generating a control instruction for reducing the rotating speed;
and S53, if the comparison distribution graph moves inwards, judging that the actual welding temperature is too low, and generating a control command for improving the rotating speed.
Embodiment 3
This embodiment, which is another optional embodiment of the present application, discloses a control method based on the friction stir welding system, including the following steps:
S1, acquiring a standard thermal infrared image and a comparison thermal infrared image, and selecting a comparison temperature value;
the standard thermal infrared images are prestored in a database, and the standard thermal infrared images are derived from historical data, namely thermal imaging images of products with the best processing quality in the same type of processed products;
therefore, when the standard thermal infrared image is selected, only the thermal infrared image of the same type of product can be selected as the standard thermal infrared image;
the comparison thermal infrared image is taken by an infrared imager, and the comparison thermal infrared image can be used as a standard thermal infrared image for processing parts in the next batch;
Then, the staff sets a comparison temperature value, and it should be noted that the comparison temperature value generally selects the best welding temperature, and a plurality of comparison temperature values can be selected, but 1-2 comparison temperature values are preferably selected based on the complexity consideration of later calculation;
s2, acquiring a standard distribution curve graph on the standard thermal infrared image according to the comparison temperature value;
s21, calling a standard thermal infrared image;
S22, randomly selecting a plurality of standard feature points on the standard thermal infrared image according to the comparison temperature value;
after the standard thermal infrared image is acquired, automatically acquiring the temperature of each region by reading the color of the standard thermal infrared image, and simultaneously selecting a plurality of standard characteristic points on the standard thermal infrared image by combining with the comparison temperature value;
It should be noted that, the temperature value represented by each standard feature point is equal to the comparison temperature value, and each standard feature point is automatically selected by a computer, and the number of the standard feature points is not less than 100;
S23, smoothing and connecting the standard characteristic points in series to obtain a standard distribution curve graph.
After each standard characteristic point is selected, generating a curve by a fitting operation mode, wherein the curve is used for smoothly connecting all the selected standard characteristic points in series, the curve is a standard distribution curve, the number of the standard distribution curves is the same as that of the comparison temperature values, and each standard distribution curve forms a standard distribution curve graph;
s3, acquiring a comparison distribution curve graph on the comparison thermal infrared image according to the comparison temperature value;
s31, calling and comparing the thermal infrared images;
The comparison thermal infrared image processed in the step S1 is obtained, namely, if a plurality of infrared imagers are arranged, the thermal infrared image after interception and splicing is obtained;
S32, randomly selecting a plurality of comparison characteristic points on the comparison thermal infrared image according to the comparison temperature value;
After the comparison thermal infrared image is obtained, the temperature of each region is automatically obtained by reading the color of the comparison thermal infrared image, and a plurality of comparison characteristic points are selected on the comparison thermal infrared image by combining the comparison temperature values;
it should be noted that, the temperature value represented by each comparison characteristic point is equal to the comparison temperature value, and meanwhile, each comparison characteristic point is automatically selected by a computer, and the number of the comparison characteristic points is not less than 100;
s33, smoothing and connecting the comparison characteristic points in series to obtain a comparison distribution curve graph.
After each comparison characteristic point is selected, generating a curve by means of fitting operation, wherein the curve is formed by smoothly connecting all the selected comparison characteristic points in series, namely, the number of the comparison characteristic points is the same as that of comparison temperature values, and each comparison characteristic point forms a comparison distribution curve graph;
S4, comparing the standard distribution curve graph with the comparison distribution curve graph, and judging whether the actual welding temperature meets the requirement;
S41, establishing a standard polar coordinate system;
it should be noted that, whether the standard thermal infrared image or the comparative thermal infrared image has a partial shadow area, the shadow area is a friction stir welding joint, because of the more accurate calibration image, the center of the shadow area is taken as the origin, and a standard polar coordinate system is established by taking the origin;
S42, placing the standard distribution curve graph and the comparison distribution curve graph into the standard polar coordinate system;
Because the standard distribution curve graph and the comparison distribution curve graph are acquired based on corresponding thermal infrared images, shadow areas matched with the friction stir welding head are arranged on the standard distribution curve graph and the comparison distribution curve graph, the origin of the shadow areas is used as an alignment point, and the alignment point is overlapped with the origin of the standard polar coordinate system; simultaneously correcting the standard distribution curve graph and the comparison distribution curve graph by combining an image acquisition mode, so that the standard distribution curve graph and the comparison distribution curve graph are placed into the standard polar coordinate system;
S43, randomly establishing a plurality of screening lines in the standard polar coordinate system, taking the intersection points of the screening lines and the standard distribution curve graph as standard points, and taking the intersection points of the screening lines and the comparison distribution curve graph as comparison points;
And automatically generating a plurality of screening lines in the standard polar coordinate system, wherein each screening line passes through the origin of the standard polar coordinate system, and meanwhile, in order to improve the control precision, each screening line is randomly arranged around the origin of the standard polar coordinate system.
S44, obtaining standard polar coordinates (R, theta) m of each standard point and comparison polar coordinates (R, alpha) n of each comparison point; wherein m represents the number of the standard point and n represents the number of the comparison point;
As shown in fig. 3, after the screening lines are determined, each screening line must intersect with the standard distribution graph and the comparison distribution graph, respectively, if one comparison temperature value is selected, each screening line has two intersection points, and if two comparison temperature values are selected, there must be 4 intersection points;
The intersection points of the screening lines and the standard distribution curve graph are standard points, polar coordinates of the standard points are respectively obtained to serve as standard polar coordinates, the expression of the standard polar coordinates is (R, theta) m, wherein m represents the reference sign R of the standard points, the polar diameter is represented by the reference sign R, and the polar angle is represented by the theta;
Similarly, the intersection point of each screening line and each comparison distribution graph is a comparison point, the polar coordinates of each comparison point are respectively obtained to serve as comparison polar coordinates, the expression of the standard polar coordinates is (r, alpha) n, wherein n represents the reference numeral r of the standard point, the polar diameter is represented by alpha, and the polar angle is represented by alpha;
S45, judging whether the comparison distribution curve graph deviates or not and the deviation direction according to the standard polar coordinates and the comparison polar coordinates;
s451, acquiring a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates according to the screening line, wherein the mutually paired standard polar coordinates and comparison polar coordinates are positioned on the same screening line;
Because a standard point and a comparison point are necessarily arranged on one screening line, the standard point and the comparison point which belong to the same comparison temperature value are paired, and therefore a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates are obtained;
S452, setting standard deviation A, and calculating the deviation a of each comparison point;
setting a standard deviation degree A according to the requirement by a worker, wherein the standard deviation degree A is an allowable deviation value of a comparison point relative to a standard point, namely r+A=R or R-A=R; the standard deviation degree needs to be freely set by a worker;
The expression of the deviation degree a of the comparison point is that
S453, if a is less than or equal to A, judging that the comparison point is not deviated;
S454, if a is larger than A, and the paired standard polar coordinates and comparison polar coordinates meet R < R, judging that the comparison point moves outwards; otherwise, judging that the comparison point moves inwards;
Through setting up of standard deviation degree A, establish reasonable fault-tolerant interval in standard comparison curve's inside and outside both sides, and then effectively prevent the error control that equipment detection error leads to, improve the accuracy to temperature monitoring, and then improve the accuracy of follow-up control instruction.
S455, counting the offset condition of each comparison point, if the number of the comparison points with the outward movement is the largest, judging that the comparison distribution curve graph is outward moved, and if the number of the comparison points with the inward movement is the largest, judging that the comparison distribution curve is inward moved; if the comparison points which do not deviate are the most, the comparison distribution curve graph is judged to not deviate.
After the deviation condition of each comparison point is judged, counting the number of the comparison points which are moved outwards, counting the number of the comparison points which are moved inwards and the number of the comparison points which are not moved;
If the outward moving comparison point is the most, the comparison distribution curve graph is judged to be outward moved, and if the inward moving comparison point is the most, the comparison distribution curve graph is judged to be inward moved; if the comparison points which do not deviate are the most, judging that the comparison distribution curve graph does not deviate;
S5, generating a control command according to the actual welding temperature, and adjusting the rotating speed of the friction stir welding head according to the control command;
S51, if the comparison distribution graph is shifted outwards and is not shifted, judging that the actual welding temperature meets the requirement, and generating no control instruction;
According to the determination result of step S453, if it is determined that the comparative distribution graph is shifted outward and not shifted, it is determined that the actual welding temperature meets the requirement, and no control instruction is generated;
S52, if the comparison distribution graph moves outwards, judging that the actual welding temperature is too high, and generating a control instruction for reducing the rotating speed;
and S53, if the comparison distribution graph moves inwards, judging that the actual welding temperature is too low, and generating a control command for improving the rotating speed.
Compared with the prior art, the temperature distribution curve graph in the welding process is obtained through the thermal infrared image, namely the same temperature point is connected through the curve, compared with the thermal infrared image, the temperature distribution curve graph is not distinguished through the color, but is represented by the line graph similar to the contour graph, so that the distribution condition of graduation can be more accurately and clearly marked, further the later comparison process is simplified, the comparison effect is better, and the improvement of the control degree of the welding temperature is facilitated;
And secondly, the standard distribution curve graph selects a corresponding temperature curve graph with optimal welding quality, and whether the temperature distribution is reasonable can be rapidly judged through comparison of the front and rear times, so that whether the distribution change of the temperature is in a controllable range is rapidly judged, and a corresponding control instruction is generated.
The foregoing description is only of the preferred embodiments of the present application, and is not intended to limit the scope of the application, but rather is intended to cover any equivalents of the structures or equivalent processes disclosed herein or in the alternative, which may be employed directly or indirectly in other related arts.
Claims (9)
1. Friction stir welding system characterized by comprising a tool holder (1);
the friction stir welding head (2) is rotatably arranged on the tool apron (1);
An infrared imager (3), wherein the infrared imager (3) is arranged on the tool apron (1); the working end of the infrared imaging instrument (3) is opposite to the friction stir welding head (2);
The controller (4) is electrically connected with the infrared imager (3); the controller (4) comprises a data acquisition module (401), wherein the data acquisition module (401) is used for acquiring a standard thermal infrared image and a comparison thermal infrared image, and selecting a comparison temperature value;
a parameter extraction module (402) for acquiring a standard distribution curve graph on the standard thermal infrared image according to the comparison temperature value;
acquiring a comparison distribution curve graph on the comparison thermal infrared image according to the comparison temperature value;
A comparison module (403) for comparing the standard distribution curve graph and the comparison distribution curve graph and judging whether the actual welding temperature meets the requirement;
And the control module (404) is used for generating a control command according to the actual welding temperature and adjusting the rotating speed of the friction stir welding head (2) according to the control command.
2. The method for controlling a friction stir welding system according to claim 1, comprising the steps of:
Acquiring a standard thermal infrared image and a comparison thermal infrared image, and selecting a comparison temperature value;
Acquiring a standard distribution curve graph on the standard thermal infrared image according to the comparison temperature value;
acquiring a comparison distribution curve graph on the comparison thermal infrared image according to the comparison temperature value;
comparing the standard distribution curve graph with the comparison distribution curve graph, and judging whether the actual welding temperature meets the requirement;
And generating a control command according to the actual welding temperature, and adjusting the rotating speed of the friction stir welding head according to the control command.
3. The control method according to claim 2, wherein the extracting a standard distribution graph on the standard thermal infrared image according to the comparison temperature value includes the steps of:
Invoking a standard thermal infrared image;
Randomly selecting a plurality of standard feature points on the standard thermal infrared image according to the comparison temperature value, wherein the temperature value represented by each standard feature point is equal to the comparison temperature value, and simultaneously, each standard feature point is automatically selected by a computer, and the number of the standard feature points is not less than 100;
and smoothing and connecting the standard characteristic points in series to obtain a standard distribution curve graph.
4. The control method according to claim 2, wherein the step of acquiring a comparison temperature contour map from the comparison thermal infrared image includes the steps of:
calling and comparing the thermal infrared images;
Randomly selecting a plurality of comparison characteristic points on the comparison thermal infrared image according to the comparison temperature value; the temperature value represented by each comparison characteristic point is equal to the comparison temperature value, and each comparison characteristic point is automatically selected by a computer, wherein the number of the comparison characteristic points is not less than 100;
And smoothly connecting the comparison characteristic points in series to obtain a comparison distribution curve graph.
5. The control method according to claim 2, characterized in that the comparing the standard distribution graph and the comparison distribution graph includes the steps of:
Establishing a standard polar coordinate system;
Placing the standard distribution graph and the comparison distribution graph into the standard polar coordinate system;
randomly establishing a plurality of screening lines in the standard polar coordinate system, taking the intersection points of the screening lines and the standard distribution curve graph as standard points, and taking the intersection points of the screening lines and the comparison distribution curve graph as comparison points;
Obtaining standard polar coordinates (R, theta) m of each standard point and comparison polar coordinates (R, alpha) n of each comparison point; wherein m represents the number of the standard point and n represents the number of the comparison point;
Judging whether the comparison distribution curve graph deviates or not and the deviation direction according to the standard polar coordinates and the comparison polar coordinates;
6. the control method according to claim 5, wherein the determining whether the alignment distribution graph is shifted and the shift direction according to the standard polar coordinates and the alignment polar coordinates includes the steps of:
Obtaining a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates according to the screening line, wherein the mutually paired standard polar coordinates and comparison polar coordinates are positioned on the same screening line;
The paired standard polar coordinates and the paired comparison polar coordinates meet R < R, and the fact that the comparison point moves outwards is judged; if R > R is satisfied, judging that the comparison point moves inwards; if r=r, then determining that the comparison point is not shifted;
Counting the deviation condition of each comparison point, if the number of the comparison points with the outward movement is the largest, judging that the comparison distribution curve graph is outward moved, and if the number of the comparison points with the inward movement is the largest, judging that the comparison distribution curve graph is inward moved; if the comparison points which do not deviate are the most, the comparison distribution curve graph is judged to not deviate.
7. The control method according to claim 5, wherein the determining whether the alignment distribution graph is shifted and the shift direction according to the standard polar coordinates and the alignment polar coordinates includes the steps of:
obtaining a plurality of groups of mutually paired standard polar coordinates and comparison polar coordinates according to the screening lines, wherein the mutually paired standard polar coordinates and comparison polar coordinates belong to the same screening line and the same comparison temperature value;
setting standard deviation A, and calculating deviation a of each comparison point;
if a is less than or equal to A, judging that the comparison point does not deviate;
If a is more than A, and the paired standard polar coordinates and the paired comparison polar coordinates meet R < R, judging that the comparison point moves outwards; otherwise, judging that the comparison point moves inwards;
Counting the deviation condition of each comparison point, if the number of the comparison points with the outward movement is the largest, judging that the comparison distribution curve graph is outward moved, and if the number of the comparison points with the inward movement is the largest, judging that the comparison distribution curve graph is inward moved; if the comparison points which do not deviate are the most, the comparison distribution curve graph is judged to not deviate.
8. The control method according to claim 7, characterized in that the expression of the degree of deviation a is
9. The control method according to claim 2, characterized in that the control command is generated according to the actual welding temperature, and the rotational speed of the friction stir welding head is adjusted according to the control command, comprising the steps of:
if the comparison distribution graph is shifted outwards and is not shifted, judging that the actual welding temperature meets the requirement, and generating no control instruction;
if the comparison distribution graph moves outwards, judging that the actual welding temperature is too high, and generating a control instruction for reducing the rotating speed;
if the comparison distribution graph moves inwards, the actual welding temperature is judged to be too low, and a control command for improving the rotating speed is generated.
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| KR20140088261A (en) * | 2012-12-28 | 2014-07-10 | 재단법인 포항산업과학연구원 | Apparatus and method for friction stir welding |
| KR20140131306A (en) * | 2014-10-16 | 2014-11-12 | 재단법인 포항산업과학연구원 | Apparatus and method for friction stir welding |
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| KR20140088261A (en) * | 2012-12-28 | 2014-07-10 | 재단법인 포항산업과학연구원 | Apparatus and method for friction stir welding |
| KR20140131306A (en) * | 2014-10-16 | 2014-11-12 | 재단법인 포항산업과학연구원 | Apparatus and method for friction stir welding |
| CN108692817A (en) * | 2018-04-11 | 2018-10-23 | 燕山大学 | Agitating friction welds transient temperature online test method |
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